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Sample records for cascaded second-harmonic generation

  1. Dispersive waves in fs cascaded second-harmonic generation

    DEFF Research Database (Denmark)

    Bache, Morten; Bang, Ole; Krolikowski, Wieslaw;

    2009-01-01

    Dispersive waves are observed in simulations of cascaded (phase-mismatched) second-harmonic generation. When generating ultra-short fs compressed near-IR solitons the dispersive waves are strongly red-shifted, depending on the soliton wavelength. Semi-analytical calculations predict the wavelengths....

  2. Optical Cherenkov radiation in ultrafast cascaded second-harmonic generation

    DEFF Research Database (Denmark)

    Bache, Morten; Bang, Ole; Zhou, Binbin

    2010-01-01

    the dispersive wave. Finally, an investigation of recent experimental results uncovers a four-wave-mixing phenomenon related to Cherenkov radiation that is an additional generation mechanism of long-wavelength radiation that can occur during soliton compression. We discuss the conditions that lead......We show through theory and numerics that when few-cycle femtosecond solitons are generated through cascaded (phase-mismatched) second-harmonic generation, these broadband solitons can emit optical Cherenkov radiation in the form of linear dispersive waves located in the red part of the spectrum....... The beating between the dispersive wave and the soliton generates trailing temporal oscillations on the compressed soliton. Insertion of a simple short-wave pass filter after the crystal can restore a clean soliton. On the other hand, bandpass filtering around the dispersive wave peak results in near...

  3. Second harmonic generation imaging

    CERN Document Server

    2013-01-01

    Second-harmonic generation (SHG) microscopy has shown great promise for imaging live cells and tissues, with applications in basic science, medical research, and tissue engineering. Second Harmonic Generation Imaging offers a complete guide to this optical modality, from basic principles, instrumentation, methods, and image analysis to biomedical applications. The book features contributions by experts in second-harmonic imaging, including many pioneering researchers in the field. Written for researchers at all levels, it takes an in-depth look at the current state of the art and possibilities of SHG microscopy. Organized into three sections, the book: Provides an introduction to the physics of the process, step-by-step instructions on how to build an SHG microscope, and comparisons with related imaging techniques Gives an overview of the capabilities of SHG microscopy for imaging tissues and cells—including cell membranes, muscle, collagen in tissues, and microtubules in live cells—by summarizing experi...

  4. Concept for power scaling second harmonic generation using a cascade of nonlinear crystals

    DEFF Research Database (Denmark)

    Hansen, Anders Kragh; Tawfieq, Mahmoud; Jensen, Ole Bjarlin;

    2015-01-01

    Within the field of high-power second harmonic generation (SHG), power scaling is often hindered by adverse crystal effects such as thermal dephasing arising from the second harmonic (SH) light, which imposes limits on the power that can be generated in many crystals. Here we demonstrate a concept...

  5. Genetic algorithm applied to the optimization of quantum cascade lasers with second harmonic generation

    Science.gov (United States)

    Gajić, A.; Radovanović, J.; Milanović, V.; Indjin, D.; Ikonić, Z.

    2014-02-01

    A computational model for the optimization of the second order optical nonlinearities in GaInAs/AlInAs quantum cascade laser structures is presented. The set of structure parameters that lead to improved device performance was obtained through the implementation of the Genetic Algorithm. In the following step, the linear and second harmonic generation power were calculated by self-consistently solving the system of rate equations for carriers and photons. This rate equation system included both stimulated and simultaneous double photon absorption processes that occur between the levels relevant for second harmonic generation, and material-dependent effective mass, as well as band nonparabolicity, were taken into account. The developed method is general, in the sense that it can be applied to any higher order effect, which requires the photon density equation to be included. Specifically, we have addressed the optimization of the active region of a double quantum well In0.53Ga0.47As/Al0.48In0.52As structure and presented its output characteristics.

  6. Controllable nonlocal behaviour by cascaded second-harmonic generation of fs pulses

    DEFF Research Database (Denmark)

    Bache, Morten; Bang, Ole; Krolikowski, Wieslaw

    2008-01-01

    Second-harmonic generation (SHG) of ultra-short pulses can act as a prototypical nonlocal nonlinear model, since the strength and nature of the temporal nonlocality can be controlled through the phase-mismatch parameter. The presence of a group-velocity mismatch namely implies that when the phase...... compression to few-cycle pulses in the cascaded quadratic soliton compressor, the spectral content of the full coupled SHG model is predicted by the nonlocal model even when few-cycle pulses are interacting....... mismatch is small the nonlocal response function becomes oscillatory, while for large phase mismatch it becomes localized. In the transition between the two regimes the strength of the nonlocality diverges, and the system goes from a weakly nonlocal to a strongly nonlocal state. When simulating soliton...

  7. Second harmonic generation microscopy

    DEFF Research Database (Denmark)

    Brüggemann, Dagmar Adeline; Brewer, Jonathan R.; Risbo, Jens;

    2010-01-01

    Myofibers and collagen show non-linear optical properties enabling imaging using second harmonic generation (SHG) microscopy. The technique is evaluated for use as a tool for real-time studies of thermally induced changes in thin samples of unfixed and unstained pork. The forward and the backward......-temperature endotherm peak observable in the differential scanning calorimetry (DSC) thermograms. DSC analysis of epimysium, the connective tissue layer that enfold skeletal muscles, produces one large endotherm starting at 57 °C and peaking at 59.5 °C. SHG microscopy of collagen fibers reveals a variability of thermal...... indicating regions of much higher thermal stability. It is seen that the benefits of the structural and temporal information available from SHG microscopy reveals complementary information to a traditional DSC measurement and enables a more complete understanding of the thermal denaturation process....

  8. Spatial mode discrimination using second harmonic generation

    DEFF Research Database (Denmark)

    Delaubert, Vincent; Lassen, Mikael Østergaard; Pulford, David

    2007-01-01

    Second harmonic generation can be used as a technique for controlling the spatial mode structure of optical beams. We demonstrate experimentally the generation of higher order spatial modes, and that it is possible to use nonlinear phase matching as a predictable and robust technique for the conv...

  9. Super/subradiant second harmonic generation

    Science.gov (United States)

    Koganov, Gennady A.; Shuker, Reuben

    2017-04-01

    A scheme for active second harmonics generation is suggested. The system comprises N three-level atoms in ladder configuration, situated into a resonant cavity. The system generates the field whose frequency is twice the frequency of the pumping laser, and the field phase is locked to the phase of the pumping field. It is found that the system can lase in either superradiant or subradiant regime, depending on the number of atoms N. When N passes some critical value the transition from the super to subradiance occurs in a phase-transition-like manner. Stability study of the steady state supports this conclusion. For experimental realization of the super/subradiant second harmonics generation we propose semiconductor quantum well structures, superconducting quantum circuits, and evanescently coupled waveguides in which equally spaced levels relevant to this study exist.

  10. Glass devices for efficient second harmonic generation

    DEFF Research Database (Denmark)

    Fage-Pedersen, Jacob; Jacobsen, Rune Shim; Kristensen, Martin

    2005-01-01

    We show here that quasi-phase matched (QPM) planar nonlinear devices of high quality can be fabricated by means of periodic poling of the glass. The devices, used for second-harmonic generation (SHG), have accurately-controlled centre wavelengths, and the normalised conversion efficiencies...... are approximately one order of magnitude higher than what has previously been reported for periodically poled glass. In conclusion, we have demonstrated that high-quality nonlinear QPM devices can be fabricated in glass-on-silicon. The technology is easily adaptable to any desired wavelength (e.g. 1550 nm) and can...

  11. GaInAs/AlInAs quantum cascade laser design based on optimized second harmonic generation

    Science.gov (United States)

    Gajić, A.; Radovanović, J.; Milanović, V.; Indjin, D.; Ikonić, Z.

    2014-09-01

    In this work, we present an innovative procedure for the design and optimization of GaInAs/AlInAs quantum cascade laser (QCL) structures based on the use of the genetic algorithm. The purpose of the algorithm is to determine the set of design parameters that would enable the maximization of the second order nonlinear susceptibility, thus facilitating significant optical nonlinearities to take place. In our optimization model, we start from the existing design in which the active region consists of two coupled InGaAs quantum wells separated by an AlInAs barrier, and the active region levels form double resonant nonlinear cascades. Upon obtaining the optimized structure and evaluating its energies and wave functions, the output characteristics are calculated by applying the full self-consistent rate equation modeling of the electron transport in a periodic QCL structure. The results of the calculations predict a noticeable improvement of targeted properties of the optimized design, while at the same time the original design calculations show excellent agreement with experimental results. The described procedure is applicable to various active region designs and can be used for other wavelength ranges.

  12. Second-Harmonic Generation of Bessel Beams in Lossy Media

    Institute of Scientific and Technical Information of China (English)

    丁德胜; 许坚毅; 王耀俊

    2002-01-01

    We present a further analysis for the second-harmonic generation of Bessel beams in lossy media. The emphasis is put on the effect of absorption to the radial pattern of the second-harmonic beam. It is shown that within the absorption length of the second harmonic, the Bessel second-harmonic beam approaches limited diffraction in the radial direction and behaves as in the case of lossless media.

  13. Second-harmonic generation with Bessel beams

    Science.gov (United States)

    Shatrovoy, Oleg

    We present the results of a numerical simulation tool for modeling the second-harmonic generation (SHG) interaction experienced by a diffracting beam. This code is used to study the simultaneous frequency and spatial profile conversion of a truncated Bessel beam that closely resembles a higher-order mode (HOM) of an optical fiber. SHG with Bessel beams has been investigated in the past and was determined have limited value because it is less efficient than SHG with a Gaussian beam in the undepleted pump regime. This thesis considers, for the first time to the best of our knowledge, whether most of the power from a Bessel-like beam could be converted into a second-harmonic beam (full depletion), as is the case with a Gaussian beam. We study this problem because using HOMs for fiber lasers and amplifiers allows reduced optical intensities, which mitigates nonlinearities, and is one possible way to increase the available output powers of fiber laser systems. The chief disadvantage of using HOM fiber amplifiers is the spatial profile of the output, but this can be transformed as part of the SHG interaction, most notably to a quasi-Gaussian profile when the phase mismatch meets the noncollinear criteria. We predict, based on numerical simulation, that noncollinear SHG (NC-SHG) can simultaneously perform highly efficient (90%) wavelength conversion from 1064 nm to 532 nm, as well as concurrent mode transformation from a truncated Bessel beam to a Gaussian-like beam (94% overlap with a Gaussian) at modest input powers (250 W, peak power or continuous-wave operation). These simulated results reveal two attractive features -- the feasibility of efficiently converting HOMs of fibers into Gaussian-like beams, and the ability to simultaneously perform frequency conversion. Combining the high powers that are possible with HOM fiber amplifiers with access to non-traditional wavelengths may offer significant advantages over the state of the art for many important applications

  14. Surface structure enhanced second harmonic generation in organic nanofibers

    DEFF Research Database (Denmark)

    Fiutowski, Jacek; Maibohm, Christian; Kostiucenko, Oksana;

    Second-harmonic generation upon femto-second laser irradiation of nonlinearly optically active nanofibers grown from nonsymmetrically functionalized para-quarterphenylene (CNHP4) molecules is investigated. Following growth on mica templates, the nanofibers have been transferred onto lithography-d......-defined regular arrays of gold square nanostructures. These nanostructure arrays induce local field enhancement, which significantly lowers the threshold for second harmonic generation in the nanofibers.......Second-harmonic generation upon femto-second laser irradiation of nonlinearly optically active nanofibers grown from nonsymmetrically functionalized para-quarterphenylene (CNHP4) molecules is investigated. Following growth on mica templates, the nanofibers have been transferred onto lithography...

  15. Squeezed light from second-harmonic generation: experiment versus theory.

    Science.gov (United States)

    Ralph, T C; Taubman, M S; White, A G; McClelland, D E; Bachor, H A

    1995-06-01

    We report excellent quantitative agreement between theoretical predictions and experimental observation of squeezing from a singly resonant second-harmonic-generating crystal. Limitations in the noise suppression imposed by the pump laser are explicitly modeled and confirmed by our measurements.

  16. Optical fiber tip for field-enhanced second harmonic generation.

    Science.gov (United States)

    Pal, Sudipta Sarkar; Mondal, Samir K; Bajpai, Phun Phun; Kapur, Pawan

    2012-10-01

    We propose a simple optical fiber tip for field-enhanced second harmonic generation (SHG). The tip shows nonlinear phenomena of SHG over a wide range of sources, at least from 630 to 830 nm. The optical field corresponding to the second harmonic appears as a nondiffracting bottle beam with voids due to the surface curvature of the tip. The field-enhanced second harmonic can also induce surface plasmons, converting the tip to a plasmonic probe with reduced background signal. The tip can be useful in nanophotonics characterization. As an example, we demonstrate the tip's response as a surface-enhanced Raman spectroscopy probe.

  17. Efficient Dual-LBO Second-Harmonic Generation by Using a Polarization Modulation Configuration

    Institute of Scientific and Technical Information of China (English)

    毕勇; 孙志培; 李瑞宁; 张瑛; 姚爱云; 林学春; 许祖彦; 王舫

    2003-01-01

    We analyse the relationship of conversion efficiency with the inter-crystal phase shift by the heuristic theory and propose a novel configuration of two cascaded nonlinear crystals for the second-harmonic generation with the polarization modulation. With this configuration, 70% external doubling efffciency is obtained, which is, to the best of our knowledge, the highest conversion efficiency with LBO crystal external frequency doubling. This configuration provides a simple and effective method to improve the second harmonic conversion efficiency.

  18. Induced Diffraction in Phase-Mismatched Second-Harmonic Generation

    Institute of Scientific and Technical Information of China (English)

    SU Wen-Hua; QIAN Lie-Jia; FU Xi-Quan; YANG Hua; ZHU He-Yuan

    2007-01-01

    We show analytically that in phase-mismatched second-harmonic generation,an effective diffraction is induced at the second-harmonic (SH) frequency.Numerical simulation results agree with the analytical predictions.Compared to the case of linear propagation,the effect of the overall diffraction at the SH frequency becomes doubled due to the induced diffraction,which causes an interesting result that the SH beam width will be larger than that of the fundamental field.

  19. Second Harmonic Generation in Scanning Probe Microscopy for Edge Localization

    Institute of Scientific and Technical Information of China (English)

    HU Xiao-Gen; LI Yu-He; LIN Hao-Shan; WANG Dong-Sheng; QI Xin

    2011-01-01

    We present an approach of second harmonic generation for edge localization of nano-scale defects measurement,based on the impact of the oscillating tip on the sample that induces higher harmonics of the excitation frequency.The harmonic signals of tip motion are measured by the heterodyne interferornetry. The edge amplitude ratio for the edge characterization can be calculated by a mechanics model and the threshold of edge localization is experimentally determined by second harmonic profiles. This approach has been successfully utilized to measure the pitch of a standard sample. The results show that the second harmonic is sensitive to locating the edge of nano-scale defects with high accuracy.%@@ We present an approach of second harmonic generation for edge localization of nano-scale defects measurement,based on the impact of the oscillating tip on the sample that induces higher harmonics of the excitation frequency.The harmonic signals of tip motion are measured by the heterodyne interferometry.The edge amplitude ratio for the edge characterization can be calculated by a mechanics model and the threshold of edge localization is experimentally determined by second harmonic profiles.This approach has been successfully utilized to measure the pitch of a standard sample.The results show that the second harmonic is sensitive to locating the edge of nano-scale defects with high accuracy.

  20. Terahertz-field-induced second harmonic generation through Pockels effect in zinc telluride crystal.

    Science.gov (United States)

    Cornet, Marion; Degert, Jérôme; Abraham, Emmanuel; Freysz, Eric

    2014-10-15

    We report on the second harmonic generation (SHG) of a near-infrared pulse in a zinc telluride crystal through the Pockels effect induced by an intense terahertz pulse. The temporal and angular behaviors of the SHG have been measured and agree well with theoretical predictions. This phenomenon, so far overlooked, makes it possible to generate second harmonic through cascading of two second-order nonlinear phenomena in the near-infrared and terahertz ranges. We also show how this cascading process can be used to sample terahertz pulses.

  1. Spin-Squeezing Entanglement of Second-Harmonic Generation

    Science.gov (United States)

    Shu, Jian

    2016-10-01

    An experimentally feasible scheme for generating spin-squeezing entanglement via second-harmonic generation was presented. Its shown that spin-squeezing entanglement can be generated rapidly in the dynamical process by adjusting coupling constant, detuning, the total number of particles and the evolution time.

  2. Second harmonic generation in thin optical fibers via cladding modes.

    Science.gov (United States)

    Elzahaby, Eman A; Kandas, Ishac; Aly, Moustafa H

    2016-05-30

    Since silica goes under the category of amorphous materials, it is difficult to investigate important processes such as second harmonic generation (SHG) in silica-based fibers. In this paper, we proposed a method for SHG relaying on cladding modes as pump modes. Cladding modes are introduced in optical fibers through tilted long period grating (T-LPG), where power of core mode is transferred into cladding modes. By functionalizing T-LPG with nonlinear coating, the interaction occurs between cladding modes and the coating material, consequently second harmonic signal (SHS) is generated with efficiency up to 0.14%.

  3. Multi-order nonlinear diffraction in second harmonic generation

    DEFF Research Database (Denmark)

    Saltiel, S. M.; Neshev, D.; Krolikowski, Wieslaw

    We analyze the emission patterns in the process of second harmonic (SH) generation in χ(2) nonlinear gratings and identify for the first time, to the best of our knowledge, the evidence of Raman-Nath type nonlinear diffraction in frequency doubling processes.......We analyze the emission patterns in the process of second harmonic (SH) generation in χ(2) nonlinear gratings and identify for the first time, to the best of our knowledge, the evidence of Raman-Nath type nonlinear diffraction in frequency doubling processes....

  4. Confocal Imaging of Biological Tissues Using Second Harmonic Generation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, B-M.; Stoller, P.; Reiser, K.; Eichler, J.; Yan, M.; Rubenchik, A.; Da Silva, L.

    2000-03-06

    A confocal microscopy imaging system was devised to selectively detect Second harmonic signals generated by biological tissues. Several types of biological tissues were examined using this imaging system, including human teeth, bovine blood vessels, and chicken skin. All these tissues generated strong second harmonic signals. There is considerable evidence that the source of these signals in tissue is collagen. Collagen, the predominant component of most tissues, is known to have second order nonlinear susceptibility. This technique may have diagnostic usefulness in pathophysiological conditions characterized by changes in collagen structure including malignant transformation of nevi, progression of diabetic complications, and abnormalities in wound healing.

  5. Near-field second-harmonic generation from gold nanoellipsoids

    Energy Technology Data Exchange (ETDEWEB)

    Celebrano, M.; Zavelani-Rossi, M.; Polli, D.; Cerullo, G. [Istituto di Fotonica e Nanotecnologie, CNR, Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo Da Vinci 32, 20133 Milano (Italy); Biagioni, P.; Finazzi, M.; Duo, L. [LNESS - Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo Da Vinci 32, 20133 Milano (Italy); Labardi, M.; Allegrini, M. [CNR-INFM, polyLab, Dipartimento di Fisica ' Enrico Fermi' , Universita di Pisa, Largo Pontecorvo 3, 56127 Pisa (Italy); Grand, J.; Adam, P.M.; Royer, P. [Laboratoire de Nanotechnologie et d' Instrumentation Optique, Universite de Technologie de Troyes, 12 rue Marie Curie, BP 2060 10010 Troyes cedex (France)

    2008-07-01

    Second-harmonic generation from single gold nanofabricated particles is experimentally investigated by a nonlinear scanning near-field optical microscope (SNOM). High peak power femtosecond polarized light pulses at the output of a hollow pyramid aperture allow for efficient second-harmonic imaging, with sub-100-nm spatial resolution and high contrast. The near-field nonlinear response is found to be directly related to both local surface plasmon resonances and particle morphology. The combined analysis of linear and second-harmonic SNOM images allows one to discriminate among near-field scattering, absorption and re-emission processes, which would not be possible with linear techniques alone. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Effect of Structural Modification on Second Harmonic Generation in Collagen

    Energy Technology Data Exchange (ETDEWEB)

    Stoller, P C; Reiser, K M; Celliers, P M; Rubenchik, A M

    2003-04-04

    The effects of structural perturbation on second harmonic generation in collagen were investigated. Type I collagen fascicles obtained from rat tails were structurally modified by increasing nonenzymatic cross-linking, by thermal denaturation, by collagenase digestion, or by dehydration. Changes in polarization dependence were observed in the dehydrated samples. Surprisingly, no changes in polarization dependence were observed in highly crosslinked samples, despite significant alterations in packing structure. Complete thermal denaturation and collagenase digestion produced samples with no detectable second harmonic signal. Prior to loss of signal, no change in polarization dependence was observed in partially heated or digested collagen.

  7. Effect of structural modification on second harmonic generation in collagen

    Science.gov (United States)

    Stoller, Patrick C.; Reiser, Karen M.; Celliers, Peter M.; Rubenchik, Alexander M.

    2003-07-01

    The effects of structural perturbation on second harmonic generation in collagen were investigated. Type I collagen fascicles obtained from rat tails were structurally modified by increasing nonenzymatic cross-linking, by thermal denaturation, by collagenase digestion, or by dehydration. Changes in polarization dependence were observed in the dehydrated samples. Surprisingly, no changes in polarization dependence were observed in highly crosslinked samples, despite significant alterations in packing structure. Complete thermal denaturation and collagenase digestion produced samples with no detectable second harmonic signal. Prior to loss of signal, no change in polarization dependence was observed in partially heated or digested collagen.

  8. Einstein-Podolsky-Rosen correlations in second-harmonic generation

    NARCIS (Netherlands)

    Lodahl, P.

    2003-01-01

    A quantum model for singly resonant second-harmonic generation in a cavity with transverse degrees of freedom is analyzed. An instability threshold for pattern formation exists in this system. Below threshold, a strong modulation of the noise is demonstrated in the transverse structure of the far fi

  9. Second harmonic generation from photonic structured GaN nanowalls

    Energy Technology Data Exchange (ETDEWEB)

    Soya, Takahiro; Inose, Yuta; Kunugita, Hideyuki; Ema, Kazuhiro; Yamano, Kouji; Kikuchi, Akihiko; Kishino, Katsumi, E-mail: t-soya@sophia.ac.j [Department of Engineering and Applied Sciences, Sophia University 7-1, Kioi-cho, Chiyoda-ku, Tokyo 102-8554 (Japan)

    2009-11-15

    We observed large enhancement of reflected second harmonic generation (SHG) using the one-dimensional photonic effect in regularly arranged InGaN/GaN single-quantum-well nanowalls. Using the effect when both fundamental and SH resonate with the photonic mode, we obtained enhancement of about 40 times compared with conditions far from resonance.

  10. Surface structure enhanced second harmonic generation in organic nanofibers

    DEFF Research Database (Denmark)

    Fiutowski, Jacek; Maibohm, Christian; Kostiucenko, Oksana;

    Second-harmonic generation upon femto-second laser irradiation of nonlinearly optically active nanofibers grown from nonsymmetrically functionalized para-quarterphenylene (CNHP4) molecules is investigated. Following growth on mica templates, the nanofibers have been transferred onto lithography-d...

  11. Imaging collagen orientation using polarization-modulated second harmonic generation

    Science.gov (United States)

    Stoller, Patrick C.; Celliers, Peter M.; Reiser, Karen M.; Rubenchik, Alexander M.

    2002-06-01

    We use polarization-modulated second harmonic generation to image fiber orientation in collagen tissues, with an axial resolution of about 10 micrometers and a transverse resolution of up to 1 micrometers . A linearly polarized ultra-short pulse (200 fs) Ti:Sapphire laser beam is modulated using an electro-optic modulator and quarter-wave plate combination and focused onto a translation stage mounted sample using a microscope objective. The generated second harmonic light is collected using a photomultiplier tube and demodulated using phase sensitive detection to obtain signal intensity and fiber orientation information. In order to obtain second harmonic generation images of different types of collagen organization, we analyze several different tissues, including rat-tail tendon, mouse aorta, mouse fibrotic liver, and porcine skin. We can use our technique to image fibrotic tissue in histological sections of damaged liver and to identify burned tissue in porcine skin to a depth of a few hundred microns. Polarization-modulated second harmonic generation potentially could be a useful clinical technique for diagnosing collagen related disease or damage, especially in the skin.

  12. Imaging Collagen Orientation Using Polarization-Modulated Second Harmonic Generation

    Energy Technology Data Exchange (ETDEWEB)

    Stoller, P; Celliers, P M; Reiser, K M; Rubenchik, A M

    2002-01-10

    We use polarization-modulated second harmonic generation to image fiber orientation in collagen tissues, with an axial resolution of about 10 {micro}m and a transverse resolution of up to 1 {micro}m. A linearly polarized ultra-short pulse (200 fs) Ti:Sapphire laser beam is modulated using an electro-optic modulator and quarter-wave plate combination and focused onto a translation stage mounted sample using a microscope objective. The generated second harmonic light is collected using a photomultiplier tube and demodulated using phase sensitive detection to obtain signal intensity and fiber orientation information. In order to obtain second harmonic generation images of different types of collagen organization, we analyze several different tissues, including rat-tail tendon, mouse aorta, mouse fibrotic liver, and porcine skin. We can use our technique to image fibrotic tissue in histological sections of damaged liver and to identify burned tissue in porcine skin to a depth of a few hundred microns. Polarization-modulated second harmonic generation potentially could be a useful clinical technique for diagnosing collagen related disease or damage, especially in the skin.

  13. All-Optical Field-Induced Second-Harmonic Generation

    CERN Document Server

    Davidson, Roderick B; Ziegler, Jed I; Avanesyan, Sergey M; Lawrie, Ben J; Haglund, Richard F

    2015-01-01

    Efficient frequency modulation techniques are crucial to the development of plasmonic metasurfaces for information processing and energy conversion. Nanoscale electric-field confinement in optically pumped plasmonic structures enables stronger nonlinear susceptibilities than are attainable in bulk materials. The interaction of three distinct electric fields in (chi)^3 optical processes allows for all-optical modulation of nonlinear signals. Here we demonstrate effcient third-order second harmonic generation (SHG) in a serrated nanogap plasmonic geometry that generates steep electric field gradients within a dielectric material. We utilize an ultrafast optical pump to control the plasmonically induced electric-fields and to generate bandwidth-limited ultrafast second-harmonic pulses driven by the control pulses. The combination of plasmonic metasurfaces with all-optical control and the freedom to choose the dielectric allow multiple generalizations of this concept and geometry to other four-wave mixing process...

  14. Dynamic investigation of Drosophila myocytes with second harmonic generation microscopy

    Science.gov (United States)

    Greenhalgh, Catherine; Stewart, Bryan; Cisek, Richard; Prent, Nicole; Major, Arkady; Barzda, Virginijus

    2006-09-01

    The functional dynamics and structure of both larval and adult Drosophila melanogaster muscle were investigated with a nonlinear multimodal microscope. Imaging was carried out using a home built microscope capable of recording the multiphoton excitation fluorescence, second harmonic generation, and third harmonic generation signals simultaneously at a scanning rate of up to ~12 frames/sec. The sample was excited by a home built femtosecond Ti:Sapphire laser at 840 nm, or by a Yb-ion doped potassium gadolinium tungstate (Yb:KGW) crystal based oscillator at 1042 nm. There was no observable damage detected in the myocyte after prolonged scanning with either of the lasers. Microscopic second harmonic generation (SHG) appears particularly strong in the myocytes. This allows the fast contraction dynamics of the myocytes to be followed. The larger sarcomere size observed in the larvae myocytes is especially well suited for studying the contraction dynamics. Microscopic imaging of muscle contractions showed different relaxation and contraction rates. The SHG intensities were significantly higher in the relaxed state of the myocyte compared to the contracted state. The imaging also revealed disappearance of SHG signal in highly stretched sarcomeres, indicating that SHG diminishes in the disordered structures. The study illustrates that SHG microscopy, combined with other nonlinear contrast mechanisms, can help to elucidate physiological mechanisms of contraction. This study also provides further insight into the mechanisms of harmonic generation in biological tissue and shows that crystalline arrangement of macromolecules has a determining factor for the high efficiency second harmonic generation from the bulk structures.

  15. Wide-bandgap III-Nitride based Second Harmonic Generation

    Science.gov (United States)

    2014-10-02

    Box 12211 Research Triangle Park, NC 27709-2211 nonlinear optics, gallium nitride , quasi-phase matching, lateral polar structures REPORT...meeting for UV Second Harmonic Generation in Aluminum Gallium Nitride semiconductors M. Hoffmann, et al, 2013 Best student paper award at the European...Materials Research Society meeting for Point defect reduction via UV illumination during growth of Aluminum Gallium Nitride Semiconductors Received

  16. Second harmonic generation spectroscopy on hybrid plasmonic/dielectric nanoantennas

    Institute of Scientific and Technical Information of China (English)

    Heiko Linnenbank; Yevgen Grynko; Jens F(o)rstner; Stefan Linden

    2016-01-01

    Plasmonic nanoantennas provide unprecedented opportunities to concentrate light fields in subwavelength-sized volumes.By placing a nonlinear dielectric nanoparticle in such a hot spot,one can hope to take advantage of beth the field enhancement provided by nanoantennas and the large,nonlinear optical susceptibility of dielectric nanoparticles.To test this concept,we combine gold gap nanoantennas with second-order,nonlinear zinc sulfide nanoparticles,and perform second harmonic generation (SHG) spectroscopy onthe combined hybrid dielectric/plasmonic nanoantennas as well as on the individual constituents.We find that SHG from the bare gold nanoantennas,even though it should be forbidden due to symmetry reasons,is several orders of magnitude larger than that of the bare zinc sulfide nanoparticles.Even stronger second harmonic signals are generated by the hybrid dielectric/plasmonic nanoantennas.Control experiments with nanoantennas containing linear lanthanum fluoride nanoparticles reveal;however,that the increased SHG efficiency of the hybrid dielectric/plasmonic nanoantennas does not depend on the nonlinear optical susceptibility of the dielectric nanoparticles but is an effect of the modification of the dielectric environment.The combination of a hybrid dielectric/plasmonic nanoantenna,which is only resonant for the incoming pump light field,with a second nanoantenna,which is resonant for the generated second harmonic light,allows for a further increase in the efficiency of SHG.As the second nanoantenna mediates the coupling of the second harmonic light to the far field,this double-resonant approach also provides us with control over the polarization of the generated light.

  17. Second harmonic generation of shear waves in crystals.

    Science.gov (United States)

    Jiang, Wenhua; Cao, Wenwu

    2004-02-01

    Nonlinear self-interaction of shear waves in electro-elastic crystals is investigated based on the rotationally invariant state function. Theoretical analyses are conducted for cubic, hexagonal, and trigonal crystals. The calculations show that nonlinear self-interaction of shear waves has some characteristics distinctly different from that of longitudinal waves. First, the process of self-interaction to generate its own second harmonic wave is permitted only in some special wave propagation directions for a shear wave. Second, the geometrical nonlinearity originated from finite strain does not contribute to the second harmonic generation (SHG) of shear waves. Therefore, unlike the case of longitudinal wave, the second-order elastic constants do not involve in the nonlinear parameter of the second harmonic generation of shear waves. Third, unlike the nonlinearity parameter of the longitudinal waves, the nonlinear parameter of the shear wave exhibits strong anisotropy, which is directly related to the symmetry of the crystal. In the calculations, the electromechanical coupling nonlinearity is considered for the 6 mm and 3 m symmetry crystals. Complement to the SHG of longitudinal waves already in use, the SHG of shear waves provides more measurements for the determination of third-order elastic constants of solids. The method is applied to a Z-cut lithium niobate (LiNbO3) crystal, and its third-order elastic constant c444 is determined.

  18. Quantitative second-harmonic generation microscopy in collagen

    Science.gov (United States)

    Stoller, Patrick; Celliers, Peter M.; Reiser, Karen M.; Rubenchik, Alexander M.

    2003-09-01

    The second-harmonic signal in collagen, even in highly organized samples such as rat tail tendon fascicles, varies significantly with position. Previous studies suggest that this variability may be due to the parallel and antiparallel orientation of neighboring collagen fibrils. We applied high-resolution second-harmonic generation microscopy to confirm this hypothesis. Studies in which the focal spot diameter was varied from ~1 to ~6 μm strongly suggest that regions in which collagen fibrils have the same orientation in rat tail tendon are likely to be less than ~1 μm in diameter. These measurements required accurate determination of the focal spot size achieved by use of different microscope objectives; we developed a technique that uses second-harmonic generation in a quartz reference to measure the focal spot diameter directly. We also used the quartz reference to determine a lower limit (dXXX > 0.4 pm/V) for the magnitude of the second-order nonlinear susceptibility in collagen.

  19. Second Harmonic Generation from Co Magnetic Thin Films

    Institute of Scientific and Technical Information of China (English)

    卢永雄; 叶骏; 金庆原

    2003-01-01

    The magnetization-induced second harmonic generation (MSHG) in the sputtered and epitaxial-grown Co thin films was studied. The magnetic contrast of the MSHG intensity could be clearly distinguished for the cobalt films prepared by both the methods, but the signal measured in air for sputtered films was not smoother than that for the in-situ measurement of epitaxial films. Compared with the magneto-optical Kerr effect, the MSHG shows some new behaviour indicating that more information could be obtained if these two methods are combined. The MSHG reveals a giant nonlinear Kerr rotation in orders of magnitude larger than its linear one.

  20. Stokes vector formalism based second harmonic generation microscopy

    Science.gov (United States)

    Qiu, Jianjun; Mazumder, Nirmal; Tsai, Han-Ruei; Hu, Chih-Wei; Kao, Fu-Jen

    2012-02-01

    In this study, we have developed a four-channel Stokes vector formalism based second harmonic generation (SHG) microscopy to map and analyze SHG signal. A four-channel Stokesmeter setup is calibrated and integrated into a laser scanning microscope to measure and characterize the SH's corresponding Stokes parameters. We are demonstrating the use of SH and its Stokes parameters to visualize the birefringence and crystalline orientation of KDP and collagen. We believe the developed method can reveal unprecedented information for biomedical and biomaterial studies.

  1. Reconstruction of complementary images in second harmonic generation microscopy

    Science.gov (United States)

    Gao, Liang; Jin, Lei; Xue, Ping; Xu, Jun; Wang, Yi; Ma, Hui; Chen, Dieyan

    2006-05-01

    Second harmonic generation microscopy(SHGM) has become widely used to image biological samples. Due to the complexity of biological samples, more and more effort has been put on polarization imaging in SHGM technology to uncover their structures. In this work, we put forward a novel stitching method based on careful mathematical calculation, and accomplish it by rotating laser polarization. We first show its validity in imaging a perfectly synthesized bio-origin polymer poly (3-hyroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx). Then, we test its power by getting a true image of fibrillar collagen structure of rat-tail tendon.

  2. Multicolour second harmonic generation by strontium barium niobate nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, E Martin; Jaque, D; Sole, J Garcia [Departamento de Fisica de Materiales, C-IV, Universidad Autonoma de Madrid, C/ Francisco Tomas y Valiente 7, 28049, Madrid (Spain); Speghini, A [DiSTeMeV, Universita di Verona and INSTM, UdR Verona, Via della Pieve 70, I-37029 San Floriano (Italy); Piccinelli, F; Nodari, L; Bettinelli, M [Dipartimento Scientifico e Tecnologico, Universita di Verona and INSTM, UdR Verona, Ca Vignal, Strada Le Grazie 15, I-37134 Verona (Italy)

    2009-05-21

    Infrared to visible second harmonic generation (SHG) has been demonstrated from 40 nm Sr{sub 0.6}Ba{sub 0.4}Nb{sub 2}O{sub 6} nanoparticles in a broad spectral range of infrared fundamental wave excitation (800-1200 nm). The efficiency for SHG is compared with that obtained from powdered samples of larger crystallite sizes so that the mechanism leading to optical frequency conversion is discussed. The obtained results point out the possibility of using nonlinear nanoparticles for multifrequency optical imaging. (fast track communication)

  3. Second harmonic generation spectroscopy on Si surfaces and interfaces

    DEFF Research Database (Denmark)

    Pedersen, Kjeld

    2010-01-01

    Optical second harmonic generation (SHG) spectroscopy studies of Si(111) surfaces and interfaces are reviewed for two types of systems: (1) clean 7 x 7 and root 3 x root 3-Ag reconstructed surfaces prepared under ultra-high vacuum conditions where surface states are excited and (2) interfaces......-like interband transitions that can be referred to excitations of dangling bond surface states. Adsorption of oxygen leads to formation of a new surface resonance. Such resonances appearing in the region between the bulk critical points E-1 and E-2 are also shown to be important for Si/oxide interfaces in SOI...

  4. Second harmonic generation of chiral-modified silver nanoparticles

    Science.gov (United States)

    Tao, Yue

    Chiral molecules, which exist under enantiomers with non-mirror-symmetrical structures, have been the subject of intense research for their linear and nonlinear optical activities. Cysteine is such a chiral amino acid found as a building block of proteins throughout human bodies. Second harmonic generation (SHG) has been considered to investigate chiral molecules. SHG from metallic nanoparticles is promising for nanoplasmonics and photonic nanodevice applications. Therefore, it's desirable to combine and study nonlinear properties due to both chirality and metallic nanoparticles, and help developing an alternatively optical diagnostic of chiral molecules. Our experiments are carried out with the FemtoFiber Scientific FFS laser system. SHG of silver nanoparticles (Ag NPs) modified by either L-Cysteine (L-C) or D-Cysteine (D-C) is observed, where L-Cysteine and D-Cysteine are a pair of enantiomers. Ag NPs are deposited through Vacuum Thermal Evaporation, controlled under different deposition thicknesses. UV-Vis/IR spectra and AFM are used to characterize Ag NPs under different conditions. Transmitted SHG measurements dependent on incidence are recorded with standard lock-in techniques. Deposition thickness of vacuum thermal evaporation plays an important role in forming diverse Ag NPs, which strongly imparts the intensity of SHG. Second harmonic intensity as a function of the incident angle presents similar results for Ag NPs with or without L-Cysteine or D-Cysteine modification, in the output of p- and s-polarization. However, we monitor reversed rotation difference in second harmonic intensities at linearly +45° and -45° polarization for L-C/Ag NPs and D-C/Ag NPs, while there's no difference at linearly +45° and -45° polarization for Ag NPs alone. This optical rotation difference in SHG is termed as SHG-ORD. Also, for second harmonic light fixed at p-polarization, L-C/Ag NPs and D-C/Ag NPs exhibit a reversely net difference for SHG excited by right and left

  5. Strain dependence of second harmonic generation in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Schriever, Clemens; Bohley, Christian; Schilling, Joerg [ZIK Silinano, Martin-Luther-University Halle (Germany); Wehrspohn, Ralf [Martin-Luther-University Halle Wittenberg (Germany)

    2010-07-01

    In recent years, silicon has become a favored material in photonics, mainly due to its highly optimized CMOS processing technology and its suitable optical properties at telecommunication wavelengths. Here it has proven itself as passive optical component. The difficulty of integrating silicon into active optoelectronics, where electrical and optical functionalities are combined in a monolithic device is due to its limited active optical properties. Generally, second order nonlinear optical effects like second harmonic generation are forbidden in silicon because of its inversion symmetry. However, an induced inhomogeneous strain can reduce the symmetry of the crystal and therefore give rise to a second order nonlinear susceptibility. This opens the possibility to create silicon based active optical devices, e.g. electro-optical modulators and switches. Here we determine experimentally the strain dependence of the second order nonlinear susceptibility on the applied strain by means of second harmonic generation in a reflecting geometry. The components of the second order nonlinear susceptibility are determined and compared to the unstrained case. The results agree well with theoretical predictions that take into account the applied strain. There, an analytical dependence of the second order nonlinear susceptibility on the strain is derived from an sp{sup 3}-orbital concept.

  6. Second-harmonic generation investigation of collagen thermal denaturation

    Science.gov (United States)

    Chen, Wei-Liang; Sun, Yen; Lin, Sung-Jan; Jee, Shiou-Hwa; Chen, Yang-Fang; Lin, Ling-Chih; So, Peter T. C.; Dong, Chen-Yuan

    2007-02-01

    Using the technique of second-harmonic generation (SHG) microscopy we obtained large area image of type I collagen from rat tail tendon as it is heated from 40°C to 70°C for 0 to 180 minutes. The high resolution images allowed us to investigate the collagen structural change. We observed that heating the tendon below the temperature of 54°C does not produce any change in the averaged SHG intensity. At the heating temperature of 54°C and above, we find that increasing the heating temperature and time leads to decreasing SHG intensity. As the tendon is heated above 54°C, a decrease in the SHG signal occurs uniformly throughout the tendon, but the regions where the SHG signal vanishes form a tiger-tail like pattern. By comparing the relative SHG intensities in small and large areas, we found that the denaturation process responsible for forming the tiger-tail like pattern occurs at a higher rate than the global denaturation process occurring throughout the tendon. Our results show that second-harmonic generation microscopy is effective in monitoring the thermal damage to collagen and has potential applications in biomedicine.

  7. Second-harmonic mode coupling in microresonator-based optical frequency comb generation

    CERN Document Server

    Xue, Xiaoxiao; Xuan, Yi; Jaramillo-Villegas, Jose A; Wang, Pei-Hsun; Leaird, Daniel E; Erkintalo, Miro; Qi, Minghao; Weiner, Andrew M

    2016-01-01

    Microresonator-based optical frequency comb (microcomb) generation can potentially achieve ultra-compact volume and low power consumption for portable applications. The comb formation is a consequence of cascaded four-wave-mixing due to the third-order Kerr nonlinearity. Mode coupling can affect the comb self-starting and mode-locking behaviors, resulting in complex dynamics that is far from well understood. Understanding the mechanism of mode coupling in comb generation proves highly important to achieve stable and robust microcomb sources. Here, we report a nonlinear mode coupling mechanism in microresonators with simultaneous second- and third-order nonlinearities. The nonlinear dynamics governed by the third-order nonlinearity is altered by second-harmonic mode coupling. As a demonstration of this effect, second-harmonic assisted coherent comb generation is achieved in the normal dispersion region, where comb creation is prohibited in the absence of mode coupling. Since second-order nonlinearity has been ...

  8. Polarization-Modulated Second Harmonic Generation Microscopy in Collagen

    Energy Technology Data Exchange (ETDEWEB)

    Stoller, P C

    2002-09-30

    Collagen is a key structural protein in the body; several pathological conditions lead to changes in collagen. Among imaging modalities that can be used in vivo, second harmonic generation (SHG) microscopy has a key advantage: it provides {approx}1 {micro}m resolution information about collagen structure as a function of depth. A new technique--polarization-modulated SHG--is presented: it permits simultaneous measurement of collagen orientation, of a lower bound on the magnitude of the second order nonlinear susceptibility tensor, and of the ratio of the two independent elements in this tensor. It is applied to characterizing SHG in collagen and to determining effects of biologically relevant changes in collagen structure. The magnitude of the second harmonic signal in two dimensional images varies with position even in structurally homogeneous tissue; this phenomenon is due to interference between second harmonic light generated by neighboring fibrils, which are randomly oriented parallel or anti-parallel to each other. Studies in which focal spot size was varied indicated that regions where fibrils are co-oriented are less than {approx}1.5 {micro}m in diameter. A quartz reference was used to determine the spot size as well as a lower limit (d{sub xxx} > 0.3 pm/V) for the magnitude of the second order nonlinear susceptibility. The ratio of the two independent tensor elements ranged between d{sub XYY}/d{sub XXX} = 0.60 and 0.75. SHG magnitude alone was not useful for identifying structural anomalies in collagenous tissue. Instead, changes in the polarization dependence of SHG were used to analyze biologically relevant perturbations in collagen structure. Changes in polarization dependence were observed in dehydrated samples, but not in highly crosslinked samples, despite significant alterations in packing structure. Complete thermal denaturation and collagenase digestion produced samples with no detectable SHG signal. Collagen orientation was measured in thin

  9. Second harmonic generation in microcrystallite films of ultrasmall Si nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Nayfeh, M. H.; Akcakir, O.; Belomoin, G.; Barry, N.; Therrien, J.; Gratton, E.

    2000-12-18

    We dispersed crystalline Si into a colloid of ultrasmall nano particles ({approx}1 nm), and reconstituted it into microcrystallites films on device-quality Si. The film is excited by near-infrared femtosecond two-photon process in the range 765--835 nm, with incident average power in the range 15--70 mW, focused to {approx}1 {mu}m. We have observed strong radiation at half the wavelength of the incident beam. The results are analyzed in terms of second-harmonic generation, a process that is not allowed in silicon due to the centrosymmetry. Ionic vibration of or/and excitonic self-trapping on novel radiative Si--Si dimer phase, found only in ultrasmall nanoparticles, are suggested as a basic mechanism for inducing anharmonicity that breaks the centrosymmetry.

  10. Thermal optimization of second harmonic generation at high pump powers.

    Science.gov (United States)

    Sahm, Alexander; Uebernickel, Mirko; Paschke, Katrin; Erbert, Götz; Tränkle, Günther

    2011-11-07

    We measure the temperature distribution of a 3 cm long periodically poled LiNbO₃ crystal in a single-pass second harmonic generation (SHG) setup at 488 nm. By means of three resistance heaters and directly mounted Pt100 sensors the crystal is subdivided in three sections. 9.4 W infrared pump light and 1.3 W of SHG light cause a de-homogenized temperature distribution of 0.2 K between the middle and back section. A sectional offset heating is used to homogenize the temperature in those two sections and thus increasing the conversion efficiency. A 15% higher SHG output power matching the prediction of our theoretical model is achieved.

  11. Broadband second harmonic generation in whispering gallery mode resonators

    CERN Document Server

    Lin, Guoping; Strekalov, Dmitry V; Yu, Nan

    2013-01-01

    Optical frequency conversion processes in nonlinear materials are limited in wavelength by the accessible phase matching and the required high pump powers. In this letter, we report a novel broadband phase matching (PM) technique in high quality factor (Q) whispering gallery mode (WGM) resonators made of birefringent crystalline materials. This technique relies on two interacting WGMs, one with constant and the other with spatially oscillating phase velocity. Thus, phase matching occurs cyclically. The technique can be implemented with a WGM resonator with its disk plane parallel to the optic axis of the crystal. With a single beta barium borate (BBO) resonator in that configuration, we experimentally demonstrated efficient second harmonic generation (SHG) to harmonic wavelengths from 780 nm in the near infrared to 317 nm in the ultraviolet (UV). The observed SHG conversion efficiency is as high as 4.6% (mW)-1. This broadband PM technique opens a new way for nonlinear optics applications in WGM resonators. Th...

  12. Second harmonic generation and crystal growth of new chalcone derivatives

    Science.gov (United States)

    Patil, P. S.; Dharmaprakash, S. M.; Ramakrishna, K.; Fun, Hoong-Kun; Sai Santosh Kumar, R.; Narayana Rao, D.

    2007-05-01

    We report on the synthesis, crystal structure and optical characterization of chalcone derivatives developed for second-order nonlinear optics. The investigation of a series of five chalcone derivatives with the second harmonic generation powder test according to Kurtz and Perry revealed that these chalcones show efficient second-order nonlinear activity. Among them, high-quality single crystals of 3-Br-4'-methoxychalcone (3BMC) were grown by solvent evaporation solution growth technique. Grown crystals were characterized by X-ray powder diffraction (XRD), laser damage threshold, UV-vis-NIR and refractive index measurement studies. Infrared spectroscopy, thermogravimetric analysis and differential thermal analysis measurements were performed to study the molecular vibration and thermal behavior of 3BMC crystal. Thermal analysis does not show any structural phase transition.

  13. Second harmonic generation from an individual amorphous selenium nanosphere

    Science.gov (United States)

    Ma, C. R.; Yan, J. H.; Wei, Y. M.; Yang, G. W.

    2016-10-01

    Among the numerous nonlinear optics effects, second harmonic generation (SHG) is always a hotspot and it is extensively used for optical frequency conversion, biomedical imaging, etc. However, SHG is forbidden in a medium with inversion symmetry under the electric-dipole approximation. Here, we demonstrated SHG from a single amorphous selenium (a-Se) nanosphere under near-infrared femtosecond pulse excitation. It was found that SH spectra are tunable with the size of a-Se nanospheres and the SHG efficiency of a single a-Se sphere with a diameter over 300 nm is estimated at 10-8. We also established two physical mechanisms of SHG from the amorphous nanospheres. There is an electric-dipole contribution to the second-order nonlinearity in view of the inevitable structural discontinuity at the surface. The discontinuity of the normal component of the electric field strength leads to the quadrupole-type contributions arising from the large electric field gradient. The SHG process can be enhanced by resonance near the fundamental wavelength, giving rise to the detectable second harmonic (SH) spectra of a single a-Se nanosphere (d > 300 nm) or two small a-Se nanospheres (d = 200 nm) aggregated into a dimer, while the single nanosphere with smaller size (d > 300 nm) is undetectable. As an essential trace element for animals, a-Se features unique biological compatibility and has specific properties of optical nonlinearity within the optical window in biological tissue. This discovery makes a-Se nanospheres promising both in nonlinear optics and biomedicine.

  14. The second-harmonic generation in a dissipative and dispersion layered structure

    Science.gov (United States)

    Soltanmohammadi, Jamshid; Jamshidi-Ghaleh, Kazem; Arghand-Hesar, Afshin; Lotfi, Erik S.; Masalehdan, Hossein

    2015-10-01

    Conversion efficiency of second-harmonic generation (SHG) in a multicrystal structure arrangement, under linearly absorption of interacting waves was analytically investigated. Different linear absorption and nonlinear interaction coefficients were considered for both of the fundamental and the second harmonic waves in cascade layers. The intensity-constant approximation on fundamental wave radiation was applied in calculations. Behavior of conversion efficiency with interaction coherence length of fundamental wave, phase miss-matching and ratio of linear absorption coefficients were graphically illustrated. The results are shown that in multicrystal structure scheme, the conversion efficiency can be tuned by the interaction coherent length and it is possible to compensate the phase differences induced in the previous layers. The phase compensation between the layers is the physical reason of efficiency improvement. Contribution to the topical issue "Advanced Electromagnetics Symposium (AES 2014) - Elected submissions", edited by Adel Razek

  15. Efficient Forward Second-Harmonic Generation from Planar Archimedean Nanospirals

    CERN Document Server

    Davidson, Roderick B; Vargas, Guillermo; Avanesyan, Sergey M; Haglund, Richard F

    2015-01-01

    The enhanced electric field at plasmonic resonances in nanoscale antennas can lead to efficient harmonic generation, especially when the plasmonic geometry is asymmetric on either inter-particle or intra-particle levels. The planar Archimedean nanospiral offers a unique geometrical asymmetry for second-harmonic generation (SHG) because the SHG results neither from arranging centrosymmetric nanoparticles in asymmetric groupings, nor from non-centrosymmetric nanoparticles that retain a local axis of symmetry. Here we report forward SHG from planar arrays of Archimedean nanospirals using 15 fs pulse from a Ti:sapphire oscillator tuned to 800 nm wavelength. The measured harmonic-generation efficiencies are 2.6*10-9, 8*10-9 and 1.3*10-8 for left-handed circular, linear, and right-handed circular polarizations, respectively. The uncoated nanospirals are stable under average power loading of as much as 300 uW per nanoparticle. The nanospirals also exhibit a selective conversion between polarization states. These exp...

  16. Research of second harmonic generation images based on texture analysis

    Science.gov (United States)

    Liu, Yao; Li, Yan; Gong, Haiming; Zhu, Xiaoqin; Huang, Zufang; Chen, Guannan

    2014-09-01

    Texture analysis plays a crucial role in identifying objects or regions of interest in an image. It has been applied to a variety of medical image processing, ranging from the detection of disease and the segmentation of specific anatomical structures, to differentiation between healthy and pathological tissues. Second harmonic generation (SHG) microscopy as a potential noninvasive tool for imaging biological tissues has been widely used in medicine, with reduced phototoxicity and photobleaching. In this paper, we clarified the principles of texture analysis including statistical, transform, structural and model-based methods and gave examples of its applications, reviewing studies of the technique. Moreover, we tried to apply texture analysis to the SHG images for the differentiation of human skin scar tissues. Texture analysis method based on local binary pattern (LBP) and wavelet transform was used to extract texture features of SHG images from collagen in normal and abnormal scars, and then the scar SHG images were classified into normal or abnormal ones. Compared with other texture analysis methods with respect to the receiver operating characteristic analysis, LBP combined with wavelet transform was demonstrated to achieve higher accuracy. It can provide a new way for clinical diagnosis of scar types. At last, future development of texture analysis in SHG images were discussed.

  17. Second harmonic generation spectroscopy on Si surfaces and interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Pedersen, Kjeld [Department of Physics and Nanotechnology, Aalborg University, Skjernvej 4A, 9220 Aalborg Oest (Denmark)

    2010-08-15

    Optical second harmonic generation (SHG) spectroscopy studies of Si(111) surfaces and interfaces are reviewed for two types of systems: (1) clean 7 x 7 and {radical}(3) x {radical}(3)-Ag reconstructed surfaces prepared under ultra-high vacuum conditions where surface states are excited and (2) interfaces in silicon-on-insulator (SOI) structures and thin metal films on Si surfaces where several interfaces contribute to the SHG. In all the systems resonances are seen at interband transitions near the bulk critical points E{sub 1} and E{sub 2}. On the clean surfaces a number of resonances appear below the onset of bulk-like interband transitions that can be referred to excitations of dangling bond surface states. Adsorption of oxygen leads to formation of a new surface resonance. Such resonances appearing in the region between the bulk critical points E{sub 1} and E{sub 2} are also shown to be important for Si/oxide interfaces in SOI structures. Finally, examples of spectroscopy on layers buried below thin Ag and Au films are given. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  18. Second harmonic generation imaging in tissue engineering and cartilage pathologies

    Science.gov (United States)

    Lilledahl, Magnus; Olderøy, Magnus; Finnøy, Andreas; Olstad, Kristin; Brinchman, Jan E.

    2015-03-01

    The second harmonic generation from collagen is highly sensitive to what extent collagen molecules are ordered into fibrils as the SHG signal is approximately proportional to the square of the fibril thickness. This can be problematic when interpreting SHG images as thick fibers are much brighter than thinner fibers such that quantification of the amount of collagen present is difficult. On the other hand SHG is therefore also a very sensitive probe to determine whether collagen have assembled into fibrils or are still dissolved as individual collagen molecules. This information is not available from standard histology or immunohistochemical techniques. The degree for fibrillation is an essential component for proper tissue function. We will present the usefulness of SHG imaging in tissue engineering of cartilage as well as cartilage related pathologies. When engineering cartilage it is essential to have the appropriate culturing conditions which cause the collagen molecules to assemble into fibrils. By employing SHG imaging we have studied how cell seeding densities affect the fibrillation of collagen molecules. Furthermore we have used SHG to study pathologies in developing cartilage in a porcine model. In both cases SHG reveals information which is not visible in conventional histology or immunohistochemistry

  19. Second-harmonic generation from hyperbolic plasmonic nanorod metamaterial slab

    CERN Document Server

    Marino, Giuseppe; Krasavin, Alexey V; Ginzburg, Pavel; Olivier, Nicolas; Wurtz, Gregory A; Zayats, Anatoly V

    2015-01-01

    Hyperbolic plasmonic metamaterials provide numerous opportunities for designing unusual linear and nonlinear optical properties. We show that the modal overlap of fundamental and second-harmonic light in an anisotropic plasmonic metamaterial slab results in the broadband enhancement of radiated second-harmonic intensity by up to 2 and 11 orders of magnitudes for TM- and TE-polarized fundamental light, respectively, compared to a smooth Au film under TM-polarised illumination. The results open up possibilities to design tuneable frequency-doubling metamaterial with the goal to overcome limitations associated with classical phase matching conditions in thick nonlinear crystals.

  20. Studies of surfaces using optical second-harmonic generation

    Energy Technology Data Exchange (ETDEWEB)

    Tom, H.W.K.

    1984-04-01

    The experiments reported in this thesis demonstrate the use of second-harmonic generation (SHG) and sum-frequency generation (SFG) in reflection from surfaces to study various surface properties. The experiments firmly establish SHG as a viable new surface probe that complements existing surface probes in ultrahigh vacuum environments and is in many ways unique for studying interfaces between dense media. Surface structural symmetry can be revealed through the anisotropy in the SH signal from the surface as the sample is rotated about its normal. The form of this anisotropy is derived in theory and verified with an experiment on the Si(100) and (111) surfaces. The SHG and SFG signals from molecules adsorbed on noninteracting substrates have a direct relationship to the number, average orientation, and spectroscopic properties of the molecules. The SH intensity was used to measure the isotherm for adsorption of p-nitrobenzoic acid from ethanolic solution to fused silica. Experiments performed on a strongly-interacting well-characterized Rh(111) surface in ultrahigh vacuum establish the sensitivity of the SH probe in corroboration with other surface probes. For the first time, the SH coverage-dependence was fit by theory in a quantitative way for the case of O-atom adsorption. The sensitivity of SH to adsorption at different sites was established for CO on top- and bridge-sites. SHG was shown to be surface specific in that the SHG from alkali metal surfaces originates from the first two monolayers. SH sensitivity to the adsorption of catalytically-important hydrocarbons and to chemical processes such as benzene dehydrogenation was also demonstrated. 122 references, 27 figures, 2 tables.

  1. Multiphoton fluorescence and second harmonic generation microscopy for imaging keratoconus

    Science.gov (United States)

    Sun, Yen; Lo, Wen; Lin, Sung-Jan; Lin, Wei-Chou; Jee, Shiou-Hwa; Tan, Hsin-Yuan; Dong, Chen-Yuan

    2006-02-01

    The purpose of this study is to assess the possible application of multiphoton fluorescence and second harmonic generation (SHG) microscopy for imaging the structural features of keratoconus cornea and to evaluate its potential as being a clinical in vivo monitoring technique. Using the near-infrared excitation source from a titanium-sapphire laser pumped by a diode-pumped, solid state (DPSS) laser system, we can induce and simultaneously acquire multiphoton autofluorescence and SHG signals from the cornea specimens with keratoconus. A home-modified commercial microscope system with specified optical components is used for optimal signal detection. Keratoconus cornea button from patient with typical clinical presentation of keratoconus was obtained at the time of penetrating keratoplasty. The specimen was also sent for the histological examination as comparison. In all samples of keratoconus, destruction of lamellar structure with altered collagen fiber orientation was observed within whole layer of the diseased stromal area. In addition, the orientation of the altered collagen fibers within the cone area shows a trend directing toward the apex of the cone, which might implicate the biomechanical response of the keratoconus stroma to the intraocular pressure. Moreover, increased autofluorescent cells were also found in the cone area, with increased density as one approaches the apical area. In conclusion, multiphoton autofluorescence and SHG microscopy non-invasively demonstrated the morphological features of keratoconus cornea, especially the structural alternations of the stromal lamellae. We believe that in the future the multiphoton microscopy can be applied in vivo as an effective, non-invasive diagnostic and monitoring technique for keratoconus.

  2. Studies of interfaces and vapors with Optical Second Harmonic Generation

    Energy Technology Data Exchange (ETDEWEB)

    Mullin, Christopher Shane [Lawrence Berkeley Lab., CA (United States); California Univ., Berkeley, CA (United States). Dept. of Physics

    1993-12-01

    Optical Second Harmonic Generation (SHG) has been applied to the study of soap-like molecules adsorbed to the water-air interface. By calibrating the signal from a soluble monolayer with that of an insoluble homolog, absolute measurements of the surface density could be obtained and related to the bulk concentration and surface tension. We could then demonstrate that the soluble surfactant forms a single monolayer at the interface. Furthermore, it deviates significantly from the ideal case in that its activity coefficients are far from 1, yet those coefficients remain constant over a broad range of surface pressures. We present evidence of a first-order phase transition taking place during the adsorption of this soluble monolayer. We consider the effects of the non-ideal behavior and the phase transition on the microscopic model of adsorption, and formulate an alternative to the Langmuir picture of adsorption which is just as simple, yet it can more easily allow for non-ideal behavior. The second half of this thesis considers the problem of SHG in bulk metal vapors. The symmetry of the vapor forbids SHG, yet it has been observed. We consider several models whereby the symmetry of the vapor is broken by the presence of the laser and compare their predictions to new observations we have made using a few-picosecond laser pulse. The two-lobed output beam profile shows that it is the vapor-plus-beam combination whose symmetry is important. The dependence on vapor pressure demonstrates the coherent nature of the radiation, while the dependence on buffer gas pressure hints at a change of the symmetry in time. The time-dependence is measured directly with a preliminary pump-probe measurement. The magnitude and intensity dependence of the signal are also measured. All but one of the models are eliminated by this comparison.

  3. Three-dimensional structural imaging of starch granules by second-harmonic generation circular dichroism.

    Science.gov (United States)

    Zhuo, G-Y; Lee, H; Hsu, K-J; Huttunen, M J; Kauranen, M; Lin, Y-Y; Chu, S-W

    2014-03-01

    Chirality is one of the most fundamental and essential structural properties of biological molecules. Many important biological molecules including amino acids and polysaccharides are intrinsically chiral. Conventionally, chiral species can be distinguished by interaction with circularly polarized light, and circular dichroism is one of the best-known approaches for chirality detection. As a linear optical process, circular dichroism suffers from very low signal contrast and lack of spatial resolution in the axial direction. It has been demonstrated that by incorporating nonlinear interaction with circularly polarized excitation, second-harmonic generation circular dichroism can provide much higher signal contrast. However, previous circular dichroism and second-harmonic generation circular dichroism studies are mostly limited to probe chiralities at surfaces and interfaces. It is known that second-harmonic generation, as a second-order nonlinear optical effect, provides excellent optical sectioning capability when combined with a laser-scanning microscope. In this work, we combine the axial resolving power of second-harmonic generation and chiral sensitivity of second-harmonic generation circular dichroism to realize three-dimensional chiral detection in biological tissues. Within the point spread function of a tight focus, second-harmonic generation circular dichroism could arise from the macroscopic supramolecular packing as well as the microscopic intramolecular chirality, so our aim is to clarify the origins of second-harmonic generation circular dichroism response in complicated three-dimensional biological systems. The sample we use is starch granules whose second-harmonic generation-active molecules are amylopectin with both microscopic chirality due to its helical structure and macroscopic chirality due to its crystallized packing. We found that in a starch granule, the second-harmonic generation for right-handed circularly polarized excitation is

  4. Characterization of muscle contraction with second harmonic generation microscopy

    Science.gov (United States)

    Prent, Nicole

    Muscle cells have the ability to change length and generate force due to orchestrated action of myosin nanomotors that cause sliding of actin filaments along myosin filaments in the sarcomeres, the fundamental contractile units, of myocytes. The correlated action of hundreds of sarcomeres is needed to produce the myocyte contractions. This study probes the molecular structure of the myofilaments and investigates the movement correlations between sarcomeres during contraction. In this study, second harmonic generation (SHG) microscopy is employed for imaging striated myocytes. Myosin filaments in striated myocytes inherently have a nonzero second-order susceptibility, [special characters omitted] and therefore generate efficient SHG. Employing polarization-in polarization-out (PIPO) SHG microscopy allows for the accurate determination of the characteristic ratio, [special characters omitted] in birefringent myocytes, which describes the structure of the myosin filament. Analysis shows that the b value at the centre of the myosin filament, where the nonlinear dipoles are better aligned, is slightly lower than the value at the edges of the filament, where there is more disorder in orientation of the nonlinear dipoles from the myosin heads. Forced stretching of myocytes resulted in an SHG intensity increase with the elongation of the sarcomere. SHG microscopy captured individual sarcomeres during contraction, allowing for the measurement of sarcomere length (SL) and SHG intensity (SI) fluctuations. The fluctuations also revealed higher SHG intensity in elongated sarcomeres. The sarcomere synchronization model (SSM) for contracting and quiescent myocytes was developed, and experimentally verified for three cases (isolated cardiomyocyte, embryonic chicken cardiomyocyte, and larva myocyte). During contraction, the action of SLs and SIs between neighbouring sarcomeres partially correlated, whereas in quiescent myocytes the SLs show an anti-correlation and the SIs have no

  5. Near-field second-harmonic generation in single gold nanoparticles

    Science.gov (United States)

    Zavelani-Rossi, M.; Celebrano, M.; Biagioni, P.; Polli, D.; Finazzi, M.; Duò, L.; Cerullo, G.; Labardi, M.; Allegrini, M.; Grand, J.; Adam, P.-M.

    2008-03-01

    Second-harmonic generation from single gold elliptical nanoparticles is experimentally investigated by a nonlinear scanning near-field optical microscope (SNOM). The near-field nonlinear response is found to be directly related to local surface plasmon resonances and to particle morphology. The combined analysis of linear and second-harmonic SNOM images provides discrimination among different light extinction particle behaviors, not achievable just with linear techniques. The polarization state of the emitted second harmonic is also investigated, providing experimental evidence of second-harmonic particle emission modes peculiar to near-field excitation.

  6. Squeezing and entanglement in doubly resonant, type II, second-harmonic generation

    DEFF Research Database (Denmark)

    Andersen, Ulrik Lund; Buchhave, Preben

    2003-01-01

    We investigate, theoretically, the generation of bright and vacuum-squeezed light as well as entanglement in intracavity, type II, phase-matched second-harmonic generation. The cavity in which the crystal is embedded is resonant at the fundamental frequency but not at the second-harmonic frequenc...

  7. Contribution of longitudinal electric field of a gaussian beam to second harmonic generation

    Science.gov (United States)

    Mishra, S. R.; Rustagi, K. C.

    1990-01-01

    A laser beam with a nonuniform transverse intensity profile necessarily has a longitudinal component of the electric field. We show that a detectable second harmonic can be generated due to coupling of this longitudinal component with the transverse field of a gaussian beam in a configuration in which second harmonic generation is forbidden for plane wave interaction.

  8. Experimental observation of cumulative second-harmonic generation of lamb waves propagating in long bones.

    Science.gov (United States)

    Zhang, Zhenggang; Liu, Dan; Deng, Mingxi; Ta, Dean; Wang, Weiqi

    2014-07-01

    The experimental observation of cumulative second-harmonic generation of fundamental Lamb waves in long bones is reported. Based on the modal expansion approach to waveguide excitation and the dispersion characteristics of Lamb waves in long bones, the mechanism underlying the generation and accumulation of second harmonics by propagation of the fundamental Lamb waves was investigated. An experimental setup was established to detect the second-harmonic signals of Lamb wave propagation in long bones in vitro. Through analysis of the group velocities of the received signals, the appropriate fundamental Lamb wave modes and the duration of the second-harmonic signals could be identified. The integrated amplitude of the time-domain second-harmonic signal was introduced and used to characterize the efficiency of second-harmonic generation by fundamental Lamb wave propagation. The results indicate that the second-harmonic signal generated by fundamental Lamb waves propagating in long bones can be observed clearly, and the effect was cumulative with propagation distance when the fundamental Lamb wave mode and the double-frequency Lamb wave mode had the same phase velocities. The present results may be important in the development of a new method to evaluate the status of long bones using the cumulative second harmonic of ultrasonic Lamb waves.

  9. Second harmonic generation in nanoscale films of transition metal chalcogenides: Taking into account multibeam interference

    Science.gov (United States)

    Lavrov, S. D.; Kudryavtsev, A. V.; Shestakova, A. P.; Kulyuk, L.; Mishina, E. D.

    2016-05-01

    Second harmonic generation is studied in structures containing nanoscale layers of transition metal chalcogenides that are two-dimensional semiconductors and deposited on a SiO2/Si substrate. The second harmonic generation intensity is calculated with allowance for multibeam interference in layers of dichalcogenide and silicon oxide. The coefficient of reflection from the SiO2-layer-based Fabry-Perot cavity is subsequently calculated for pump wave fields initiating nonlinear polarization at every point of dichalcogenide, which is followed by integration of all second harmonic waves generated by this polarization. Calculated second harmonic intensities are presented as functions of dichalcogenide and silicon oxide layer thicknesses. The dependence of the second harmonic intensity on the MoS2 layer thickness is studied experimentally in the layer of 2-140 nm. A good coincidence of the experimental data and numerical simulation results has been obtained.

  10. Efficient second harmonic generation of picosecond laser pulses.

    Science.gov (United States)

    Rabson, T. A.; Ruiz, H. J.; Shah, P. L.; Tittel, F. K.

    1972-01-01

    Efficient conversion to the second harmonic (SH) using KD2PO4 and CsH2AsO4 crystals inside a folded cavity of a high-power-dye mode-locked neodymium-glass laser is reported. For the first time, frequency-doubled picosecond light pulses have been obtained in CsH2AsO4 with peak powers of the order of 1 GW/sq cm at 0.531 micron for an effective pump power density of 4 GW/sq cm.

  11. Cumulative second-harmonic generation of Lamb waves propagating in a two-layered solid plate

    Institute of Scientific and Technical Information of China (English)

    Xiang Yan-Xun; Deng Ming-Xi

    2008-01-01

    The physical process of cumulative second-harmonic generation of Lamb waves propagating in a two-layered solid plate is presented by using the second-order perturbation and the technique of nonlinear reflection of acoustic waves at an interface.In general,the cumulative second-harmonic generation of a dispersive guided wave propagation does not occur.However,the present paper shows that the second-harmonic of Lamb wave propagation arising from the nonlinear interaction of the partial bulk acoustic waves and the restriction of the three boundaries of the solid plates does have a cumulative growth effect if some conditions are satisfied.Through boundary condition and initial condition of excitation,the analytical expression of cumulative second-harmonic of Lamb waves propagation is determined.Numerical results show the cumulative effect of Lamb waves on second-harmonic field patterns.

  12. Surface second-harmonic generation from coupled spherical plasmonic nanoparticles: Eigenmode analysis and symmetry properties

    Science.gov (United States)

    Butet, Jérémy; Dutta-Gupta, Shourya; Martin, Olivier J. F.

    2014-06-01

    The surface second-harmonic generation from interacting spherical plasmonic nanoparticles building different clusters (symmetric and asymmetric dimers, trimers) is theoretically investigated. The plasmonic eigenmodes of the nanoparticle clusters are first determined using an ab initio approach based on the Green's functions method. This method provides the properties, such as the resonant wavelengths, of the modes sustained by a given cluster. The fundamental and second-harmonic responses of the corresponding clusters are then calculated using a surface integral method. The symmetry of both the linear and nonlinear responses is investigated, as well as their relationship. It is shown that the second-harmonic generation can be significantly enhanced when the fundamental field is such that its second harmonic matches modes with suitable symmetry. The role played by the nanogaps in second-harmonic generation is also underlined. The results presented in this article demonstrate that the properties of the second-harmonic generation from coupled metallic nanoparticles cannot be fully predicted from their linear response only, while, on the other hand, a detailed knowledge of the underlying modal structure can be used to optimize the generation of the second harmonic.

  13. Effect of loss on slow-light-enhanced second-harmonic generation in periodic nanostructures

    DEFF Research Database (Denmark)

    Saravi, Sina; Quintero-Bermudez, Rafael; Setzpfandt, Frank;

    2016-01-01

    We theoretically analyze the dependence of second-harmonic generation efficiency on the group index in periodic optical waveguides with loss. We investigate different possible scenarios of using slow light to enhance the efficiency of this process and show that in some cases there exists a maxima......We theoretically analyze the dependence of second-harmonic generation efficiency on the group index in periodic optical waveguides with loss. We investigate different possible scenarios of using slow light to enhance the efficiency of this process and show that in some cases there exists...... of second-harmonic generation in periodic nanobeam waveguides with loss. (C) 2016 Optical Society of America...

  14. Effects of transverse profile of pump field on second harmonic generation in periodic nonlinear materials

    Institute of Scientific and Technical Information of China (English)

    张汉壮; 杨建冰; 高锦岳

    2003-01-01

    We report on a theoretical analysis of the effects of a converging pump field of Gaussian transverse profile on second harmonic generation in a periodic nonlinear material with quasi-phase-matching. The outputs of the centre intensity and the intensity flux for second harmonic generation are derived by simulation, based on the parameters of quasi-phase-mismatch, the waist and focus positions of the input pump beam. The results show that when the transverse profile of the pump field is taken into account, the quasi-phase-match value and focus position of input beam for maximal second harmonic generation follow new criteria.

  15. Phase-matched relativistic second harmonic generation in clusters with density ripple

    Science.gov (United States)

    Vij, Shivani; Aggarwal, Munish; Kant, Niti

    2017-01-01

    An intense short-pulse laser obliquely incident on a clustered gas quickly converts the atomic clusters into hot plasma balls. The laser beam produces a second harmonic due to nonlinear response of cluster and plasma electrons. For enhancement of efficiency of second harmonic generation, there should be appropriate phase-matching between the incident laser beam and the generated harmonic. To achieve the required phase-matching, the ripple in cluster density and plasma electron density outside the cluster is introduced. The efficiency of second harmonic generation is sensitive to the angle between ripple wave vector k→o and the direction of the incident laser beam.

  16. Effects of transverse profile of pump field on second harmonic generation in periodic nonlinear materials

    Institute of Scientific and Technical Information of China (English)

    GaoJin-Yue; ZhangHan-Zhuang; YangJian-Bing

    2003-01-01

    We report on a theoreticalanalysis of the effects of a converging pump field of Gaussian transverse profile on second harmonic generation in a periodic nonlinear material with quasi-phase-matching. The outputs of the centre intensity and the intensity flux for second harmonic generation are derived by simulation, based on the parameters of quasi-phase-mismatch, the waist and focus positions of the input pump beam. The results show that when the transverse profile of the pump field is taken into account, the quasi-phase-match value and focus position of input beam for maximal second harmonic generation flollow new criteria.

  17. Radially polarized annular beam generated through a second-harmonic-generation process.

    Science.gov (United States)

    Sato, Shunichi; Kozawa, Yuichi

    2009-10-15

    A radially polarized beam with an annular intensity pattern was generated through a second-harmonic-generation process by focusing an azimuthally polarized Ti:sapphire pulsed laser beam to a c-cut beta-barium borate (BBO) crystal. The annular intensity pattern of the second-harmonic wave had a nearly sixfold symmetry as a result of the nonlinear susceptibility tensor of the BBO crystal. The width of the annulus was as narrow as less than 1/40th of its radius.

  18. Optical second harmonic generation induced by picosecond terahertz pulses in centrosymmetric antiferromagnet NiO

    Science.gov (United States)

    Ovchinnikov, A. V.; Chefonov, O. V.; Agranat, M. B.; Grishunin, K. A.; Il'in, N. A.; Pisarev, R. V.; Kimel, A. V.; Kalashnikova, A. M.

    2016-10-01

    Optical second harmonic generation at the photon energy of 2ℏω = 2eV in the model centrosymmetric antiferromagnet NiO irradiated with picosecond terahertz pulses (0.4-2.5 THz) at room temperature is detected. The analysis of experimental results shows that induced optical second harmonic generation at the moment of the impact of a terahertz pulse arises through the electric dipole mechanism of the interaction of the electric field of a pump pulse with the electron subsystem of NiO. Temporal changes in optical second harmonic generation during 7 ps after the action of the pulse are also of an electric dipole origin and are determined by the effects of propagation of the terahertz pulse in a NiO platelet. Coherent oscillations of spins at the antiferromagnetic resonance frequency induced by the magnetic component of the terahertz pulse induce a relatively weak modulation of magnetic dipole optical second harmonic generation.

  19. Second-Harmonic and Third-Harmonic Generations in the Thue-Morse Dielectric Superlattice

    Institute of Scientific and Technical Information of China (English)

    蔡祥宝

    2002-01-01

    Theoretical work on the optical properties of the one-dimensional dielectric superlattice is extended. 3Byv means of a transfer matrix method, the second-harmonic and third-harmonic generations in a one-dimensional tinite Thue Morse dielectric superlattice are analysed. The electric field amplitude variables of the second-harmonic and third-harmonic can be expressed by the formula of matrices. Taking advantage of numerical procedure, we discuss the dependence of the second-harmonic and third-harmonic on the fundamental wavelength and the field amplitude variables of the fundamental wave. High conversion efficiency of the third-harmonic can be obtained at some special fundamental wavelength.

  20. Giant Enhancement of Second Harmonic Generation at Photonic Band Gap Edges

    Institute of Scientific and Technical Information of China (English)

    MA Dong-Li; REN Ming-Liang; DOU Jun-Hong; LI Zhi-Yuan

    2010-01-01

    @@ Second harmonic generation(SHG)in one-dimensional nonlinear photonic crystals made from periodically alternating ferroelectric and dielectric layers is investigated by means of the transfer matrix method.When tunedat the photonic band gap(PBG)edges,the fundamental wave and second harmonic wave slow down,and the filed enhancement takes place within the nonlinear photonic crystal.The phase mismatching can be compensated for to some extent and the second harmonic process will be enhanced.Numerical results show that the enhancement of SHG in the PBG structure can be up to four orders of magnitude compared with the traditional quasi-phase-matching structure.

  1. Type I and type II second harmonic generation of conically refracted beams

    CERN Document Server

    Turpin, Alex; Kalkandjiev, Todor K; Trull, Jose; Cojocaru, Crina; Mompart, Jordi

    2014-01-01

    Type I and type II second harmonic generation (SHG) of a beam transformed by the conical refraction phenomenon are presented. We show that, for type I, the second harmonic intensity pattern is a light ring with a point of null intensity while, for type II, the light ring possesses two dark regions. Taking into account the different two-photon processes involved in SHG, we have derived analytical expressions for the resulting transverse intensity patterns that are in good agreement with the experimental data. Finally, we have investigated the spatial evolution of the second harmonic signals, showing that they behave as conically refracted beams.

  2. Impedance matching in photonic crystal microcavities for second-harmonic generation.

    Science.gov (United States)

    Di Falco, Andrea; Conti, Claudio; Assanto, Gaetano

    2006-01-15

    By numerically integrating the three-dimensional Maxwell equations in the time domain with reference to a dispersive quadratically nonlinear material, we study second-harmonic generation in planar photonic crystal microresonators. The proposed scheme allows efficient coupling of the pump radiation to the defect resonant mode. The outcoupled generated second harmonic is maximized by impedance matching the photonic crystal cavity to the output waveguide.

  3. Second harmonic generation in carbon nanotubes induced by transversal electrostatic field.

    Science.gov (United States)

    Trolle, Mads Lund; Pedersen, Thomas Garm

    2013-08-14

    Carbon nanotubes (CNTs) of armchair and zigzag type contain an inversion centre, and are thus intrinsically unable to generate dipole even-order nonlinearities, such as second harmonic generation (SHG). Breaking the inversion symmetry by application of an external voltage transversal to the CNT axis will, however, induce a second harmonic response. Similarly, additional non-vanishing second harmonic tensor elements will be induced in chiral tubes already displaying an intrinsic response. Many geometries realizing such a setup can be envisaged, e.g., an experimental gate setup or deposition of CNTs on, or integration in, strongly polarized host media, perhaps facilitating a tunable second harmonic response. In this work, we calculate the SHG signal from CNTs under transversally applied electric fields based on a tight-binding model.

  4. Optical second harmonic generation of single metallic nanoparticles embedded in a homogeneous medium.

    Science.gov (United States)

    Butet, Jérémy; Duboisset, Julien; Bachelier, Guillaume; Russier-Antoine, Isabelle; Benichou, Emmanuel; Jonin, Christian; Brevet, Pierre-François

    2010-05-12

    We report the optical second harmonic generation from individual 150 nm diameter gold nanoparticles dispersed in gelatin. The quadratic hyperpolarizability of the particles is determined and the input polarization dependence of the second harmonic intensity obtained. These results are found in excellent agreement with ensemble measurements and finite element simulations. These results open up new perspectives for the investigation of the nonlinear optical properties of noble metal nanoparticles.

  5. Extracavity and external cavity second-harmonic generation in a periodically poled silica fibre

    Science.gov (United States)

    Dontsova, E. I.; Kablukov, S. I.; Lobach, I. A.; Dostovalov, A. V.; Babin, S. A.; Gladyshev, A. V.; Dianov, E. M.; Corbary, C.; Ibsen, M.; Kazansky, P. G.

    2016-11-01

    We have studied second-harmonic generation (SHG) of a cw single-frequency ytterbium-doped fibre laser, using a periodically poled silica fibre as a nonlinear medium for frequency conversion. All-fibre external cavity SHG has been investigated for the first time. A twofold increase in second-harmonic power in a fibre ring cavity has been demonstrated and possibilities of further optimising the fibre scheme have been analysed.

  6. Using the self-filtering property of a femtosecond filament to improve second harmonic generation.

    Science.gov (United States)

    Shwa, David; Eisenmann, Shmuel; Marcus, Gilad; Zigler, Arie

    2009-04-13

    In this paper we demonstrate the use of NIR femtosecond filament for improving the generation of second harmonic using a type I BBO crystal. Using this method the beam propagation factor (M(2)) of the second harmonic was improved significantly; which led to enhancement of the attainable SH intensity by up to two orders of magnitude. This method can be beneficial for applications demanding high intensities, small spot size or long interaction lengths.

  7. Determination of collagen fibril size via absolute measurements of second-harmonic generation signals

    Science.gov (United States)

    Bancelin, Stéphane; Aimé, Carole; Gusachenko, Ivan; Kowalczuk, Laura; Latour, Gaël; Coradin, Thibaud; Schanne-Klein, Marie-Claire

    2014-09-01

    The quantification of collagen fibril size is a major issue for the investigation of pathological disorders associated with structural defects of the extracellular matrix. Second-harmonic generation microscopy is a powerful technique to characterize the macromolecular organization of collagen in unstained biological tissues. Nevertheless, due to the complex coherent building of this nonlinear optical signal, it has never been used to measure fibril diameter so far. Here we report absolute measurements of second-harmonic signals from isolated fibrils down to 30 nm diameter, via implementation of correlative second-harmonic-electron microscopy. Moreover, using analytical and numerical calculations, we demonstrate that the high sensitivity of this technique originates from the parallel alignment of collagen triple helices within fibrils and the subsequent constructive interferences of second-harmonic radiations. Finally, we use these absolute measurements as a calibration for ex vivo quantification of fibril diameter in the Descemet’s membrane of a diabetic rat cornea.

  8. Imaging the bipolarity of myosin filaments with Interferometric Second Harmonic Generation microscopy.

    Science.gov (United States)

    Rivard, Maxime; Couture, Charles-André; Miri, Amir K; Laliberté, Mathieu; Bertrand-Grenier, Antony; Mongeau, Luc; Légaré, François

    2013-01-01

    We report that combining interferometry with Second Harmonic Generation (SHG) microscopy provides valuable information about the relative orientation of noncentrosymmetric structures composing tissues. This is confirmed through the imaging of rat medial gastrocnemius muscle. The inteferometric Second Harmonic Generation (ISHG) images reveal that each side of the myosin filaments composing the A band of the sarcomere generates π phase shifted SHG signal which implies that the myosin proteins at each end of the filaments are oriented in opposite directions. This highlights the bipolar structural organization of the myosin filaments and shows that muscles can be considered as a periodically poled biological structure.

  9. The second-harmonic generation susceptibility in semiparabolic quantum wells with applied electric field

    Science.gov (United States)

    Yuan, Jian-Hui; Zhang, Yan; Mo, Hua; Chen, Ni; Zhang, Zhihai

    2015-12-01

    The second-harmonic generation susceptibility in semiparabolic quantum wells with applied electric field is investigated theoretically. For the same topic studied by Zhang and Xie [Phys. Rev. B 68 (2003) 235315] [1], some new and reliable results are obtained by us. It is easily observed that the second harmonic generation susceptibility decreases and the blue shift of the resonance is induced with increasing of the frequencies of the confined potential. Moreover, a transition from a two-photon resonance to two single-photon resonances will appear adjusted by the frequencies of the confined potential. Similar results can also be obtained by controlling the applied electric field. Surprisingly, the second harmonic generation susceptibility is weakened in the presence of the electric field, which is in contrast to the conventional case. Finally, the resonant peak and its corresponding resonant energy are also taken into account.

  10. Quantum properties of transverse pattern formation in second-harmonic generation

    DEFF Research Database (Denmark)

    Bache, Morten; Scotto, P.; Zambrini, R.;

    2002-01-01

    We investigate the spatial quantum noise properties of the one-dimensional transverse pattern formation instability in intracavity second-harmonic generation. The Q representation of a quasi-probability distribution is implemented in terms of nonlinear stochastic Langevin equations. We study...... these equations through extensive numerical simulations and analytically in the linearized limit. Our study, made below and above the threshold of pattern formation, is guided by a microscopic scheme of photon interaction underlying pattern formation in second-harmonic generation. Close to the threshold...

  11. Phase-matched second harmonic generation with on-chip GaN-on-Si microdisks

    Science.gov (United States)

    Roland, I.; Gromovyi, M.; Zeng, Y.; El Kurdi, M.; Sauvage, S.; Brimont, C.; Guillet, T.; Gayral, B.; Semond, F.; Duboz, J. Y.; de Micheli, M.; Checoury, X.; Boucaud, P.

    2016-09-01

    We demonstrate phase-matched second harmonic generation in gallium nitride on silicon microdisks. The microdisks are integrated with side-coupling bus waveguides in a two-dimensional photonic circuit. The second harmonic generation is excited with a continuous wave laser in the telecom band. By fabricating a series of microdisks with diameters varying by steps of 8 nm, we obtain a tuning of the whispering gallery mode resonances for the fundamental and harmonic waves. Phase matching is obtained when both resonances are matched with modes satisfying the conservation of orbital momentum, which leads to a pronounced enhancement of frequency conversion.

  12. The second harmonic generation in symmetrical and asymmetrical Gaussian potential quantum wells with applied electric field

    Science.gov (United States)

    Yuan, Jian-Hui; Chen, Ni; Mo, Hua; Zhang, Yan; Zhang, Zhi-Hai

    2015-12-01

    A detailed investigation of the second harmonic generation in symmetrical and asymmetrical Gaussian potential quantum wells under the influence of applied electric field by using the compact-density-matrix approach and the finite difference method. The results show that the second-harmonic generation susceptibility obtained in two cases can reach the magnitude of 10-4 m/V, which depend dramatically on the applied electric field and the structural parameters. Finally, the resonant peak and its corresponding to the resonant energy are also taken into account.

  13. Phase-matched second harmonic generation with on-chip GaN-on-Si microdisks

    Science.gov (United States)

    Roland, I.; Gromovyi, M.; Zeng, Y.; El Kurdi, M.; Sauvage, S.; Brimont, C.; Guillet, T.; Gayral, B.; Semond, F.; Duboz, J. Y.; de Micheli, M.; Checoury, X.; Boucaud, P.

    2016-01-01

    We demonstrate phase-matched second harmonic generation in gallium nitride on silicon microdisks. The microdisks are integrated with side-coupling bus waveguides in a two-dimensional photonic circuit. The second harmonic generation is excited with a continuous wave laser in the telecom band. By fabricating a series of microdisks with diameters varying by steps of 8 nm, we obtain a tuning of the whispering gallery mode resonances for the fundamental and harmonic waves. Phase matching is obtained when both resonances are matched with modes satisfying the conservation of orbital momentum, which leads to a pronounced enhancement of frequency conversion. PMID:27687007

  14. Analysis of Second-Harmonic Generation from CuttbPc LB Film/Metal Interface

    Institute of Scientific and Technical Information of China (English)

    程晓曼; 姚素薇; 李成全; 间中孝彰; 岩本光正

    2004-01-01

    Second-harmonic generation signals from a CuttbPc LB film deposited on metal (Al or Au)-glass substrates were investigated. It was observed that there were two second-harmonic peaks at the wavelength of 1060 and 1250nm in the CuttbPc/A1 film, but only one peak at 1050nm in the CuttbPc/Au film. Meanwhile the surface electric potentials (SEP) at the interfaces of LB film/metals were also measured using a Kelvin probe. The SEP in the CuttbPc/Al decreases and eventually approaches a saturated value of -1.0 V as the film thickness increases,while the SEP in the CuttbPc/Au is nearly zero. Based on the experimental results and theoretical analysis, it was considered that the space-charge-induced electric field makes a main contribution to the second-harmonic generation at 1250nm in the CuttbPc/Al film.

  15. Second harmonic generation of Cosh-Gaussian laser beam in collisional plasma with nonlinear absorption

    Science.gov (United States)

    Singh, Navpreet; Gupta, Naveen; Singh, Arvinder

    2016-12-01

    This paper investigates second harmonic generation (SHG) of an intense Cosh-Gaussian (ChG) laser beam propagating through a preformed underdense collisional plasma with nonlinear absorption. Nonuniform heating of plasma electrons takes place due to the nonuniform irradiance of intensity along the wavefront of laser beam. This nonuniform heating of plasma leads to the self-focusing of the laser beam and thus produces strong density gradients in the transverse direction. The density gradients so generated excite an electron plasma wave (EPW) at pump frequency that interacts with the pump beam to produce its second harmonics. To envision the propagation dynamics of the ChG laser beam, moment theory in Wentzel-Kramers-Brillouin (W.K.B) approximation has been invoked. The effects of nonlinear absorption on self-focusing of the laser beam as well as on the conversion efficiency of its second harmonics have been theoretically investigated.

  16. Performance optimization of an external enhancement resonator for optical second-harmonic generation

    Science.gov (United States)

    Jurdik, E.; Hohlfeld, J.; van Etteger, A. F.; Toonen, A. J.; Meerts, W. L.; van Kempen, H.; Rasing, Th.

    2002-07-01

    We study the factors that ultimately limit the performance of an external enhancement resonator for optical second-harmonic generation (SHG). To describe the resonant SHG process we introduce a theoretical model that accounts for the intensity-dependent cavity loss that is due to harmonic generation and that also includes a realistic assumption about the shape and the frequency width of the laser mode. With the help of this model we optimized the performance of a doubling cavity based on a lithium triborate (LBO) crystal. This cavity was used for frequency doubling the output of a single-frequency titanium-doped sapphire laser at 850 nm. We were able to push the total second-harmonic conversion efficiency to 53% (a 1.54-W pump resulted in 820 mW of second-harmonic light), which to our knowledge is the best result ever reported for a LBO-based doubling cavity. , Laser-focused atomic deposition.

  17. Silencing and enhancement of second-harmonic generation in optical gap antennas.

    Science.gov (United States)

    Berthelot, Johann; Bachelier, Guillaume; Song, Mingxia; Rai, Padmnabh; Colas des Francs, Gérard; Dereux, Alain; Bouhelier, Alexandre

    2012-05-07

    Amplifying local electromagnetic fields by engineering optical interactions between individual constituents of an optical antenna is considered fundamental for efficient nonlinear wavelength conversion in nanometer-scale devices. In contrast to this general statement we show that high field enhancement does not necessarily lead to an optimized nonlinear activity. In particular, we demonstrate that second-harmonic responses generated at strongly interacting optical gap antennas can be significantly suppressed. Numerical simulations are confirming silencing of second-harmonic in these coupled systems despite the existence of local field amplification. We then propose a simple approach to restore and amplify the second-harmonic signal by changing the manner in which electrically-connected optical antennas are interacting in the charge-transfer plasmon regime. Our observations provide critical design rules for realizing optimal structures that are essential for a broad variety of nonlinear surface-enhanced characterizations and for realizing the next generation of electrically-driven optical antennas.

  18. Widely tunable second-harmonic generation in a chalcogenide-tellurite hybrid optical fiber.

    Science.gov (United States)

    Cheng, Tonglei; Gao, Weiqing; Kawashima, Hiroyasu; Deng, Dinghuan; Liao, Meisong; Matsumoto, Morio; Misumi, Takashi; Suzuki, Takenobu; Ohishi, Yasutake

    2014-04-01

    When a chalcogenide-tellurite hybrid optical fiber with a high refractive index difference Δn=0.24 is pumped by an optical parametric oscillator with a pump wavelength from 1700 to 3000 nm, widely tunable second-harmonic generation (SHG) from 850 to 1502 nm is obtained. The observation of SHG is primarily due to the surface nonlinearity polarization at the core-cladding interface and the second-harmonic signal remains stable at the maximal level throughout the laser pulse irradiation.

  19. Efficient second harmonic generation in χ(2) profile reconfigured lithium niobate thin film

    Science.gov (United States)

    Cai, Lutong; Wang, Yiwen; Hu, Hui

    2017-03-01

    Second harmonic wave was efficiently generated in proton exchanged lithium niobate thin film channel waveguides. Modal dispersion phase matching was achieved between two guided modes at pump and second-harmonic wavelengths with the same polarization, enabling using the largest second-order nonlinear component d33. The χ(2) profile in the lithium niobate thin film was reconfigured by proton exchange, leading to significantly enhanced modal overlap integral between the interacting modes. Normalized conversion efficiency up to 48% W-1 cm-2 was achieved in experiments.

  20. Excitons in C-60 studied by temperature-dependent optical second-harmonic generation

    NARCIS (Netherlands)

    Janner, A.M; Eder, R; Koopmans, B; Jonkman, H.T.; Sawatzky, G.A

    1995-01-01

    The electric-dipole-forbidden T-1(1g) excitonic state of solid C-60 at hw=1.81 eV can be probed with a second-harmonic generation (SHG) experiment. We show that the SHG line shape depends strongly on the degree of rotational order. We observe a splitting into two peaks below the rotational ordering

  1. Green bright squeezed light from a cw periodically poled KTP second harmonic generator

    DEFF Research Database (Denmark)

    Andersen, Ulrik Lund; Buchhave, Preben

    2002-01-01

    We present the experimental observation of bright amplitude squeezed light from a singly resonant second harmonic generator (SHG) based on a periodically poled potassium titanyl phosphate (KTP) crystal. Contrary to conventional SHG, the interacting waves in this device couple efficiently using qu...

  2. Second-Harmonic Generation and Shielding Effects on Alkali Clusters on Ultrathin Organic Films

    DEFF Research Database (Denmark)

    Balzer, Frank; Rubahn, Horst-Günter

    2001-01-01

    with the alkali metal, thus demonstrating the sensitivity of second-harmonic generation to morphological changes in these complex systems. Simultaneously performed extinction and scanning force microscopy measurements under ambient air conditions allow us to obtain independent information on the surface coverage...

  3. Phase transition of lipid-like monolayer characterized by second harmonic generation

    Institute of Scientific and Technical Information of China (English)

    于安池; 常青; 赵新生; 周晴中; 李东; 黄岩谊; 程天蓉; 黄春辉

    1999-01-01

    Phase transition of a lipid-like hemicyanine compound characterized by second harmonic generation is studied carefully. The phase transition is assigned as the first order transition between solid state and liquid state. The transition temperature increases with an increase in the surface molecular concentration. A monolayer structure parameter a which is very sensitive to the phase transition is introduced.

  4. Second-Harmonic Generation Scanning Microscopy on Domains in Al Surfaces

    DEFF Research Database (Denmark)

    Pedersen, Kjeld; Bozhevolnyi, Sergey I.

    1999-01-01

    Scanning optical second-harmonic generation microscopy has been used to investigate domains in the surface of polycrystaline Al. Strong contrast among the crystalline grains is obtained due to variations in their crystallographic orientations and thus also nonlinear response. The origin of the co...

  5. Quasi-phase-matching bandwidth for second harmonic generation in crystals with a regular domain structure

    NARCIS (Netherlands)

    Dmitriev, VG; Yur'ev, YV

    1999-01-01

    The question of the quasi-phase-matching bandwidth for second harmonic generation in crystals with a regular domain structure is considered in terms of the approximation of a constant field of the fundamental-frequency radiation and in the nonlinear conversion regime.

  6. Second harmonic generation microscopy reveals hidden polar organization in fluoride doped MIL-53(Fe)

    NARCIS (Netherlands)

    Markey, K.; Putzeys, T.; Horcajada, P.; Devic, T.; Guillou, N.; Wübbenhorst, M.; Van Cleuvenbergen, S.; Verbiest, T.; De Vos, D.E.; Van der Veen, M.A.

    2016-01-01

    Polar metal–organic frameworks have potential applications as functional non-linear optical, piezoelectric, pyroelectric and ferroelectric materials. Using second harmonic generation microscopy we found that fluoride doping of the microporous iron(III) terephthalate MOF MIL-53(Fe) induces a polar or

  7. A Microscopic Model for the Second-Harmonic Generation from C60

    NARCIS (Netherlands)

    Koopmans, Bert; Janner, Anna-Maria; Guardini, Roberta; Jonkman, Harry T.; Sawatzky, George A.; Woude, Folkert van der

    1994-01-01

    We discuss the microscopic origin of the Second-Harmonic Generation (SHG) resonance at ħω=1.81 eV, based on spectroscopic and thickness dependent SHG measurements on C60 thin films. We assign the three-level diagram responsible for the observed SHG resonance, and show it to be of magnetic-dipole-ind

  8. Mode matching in multiresonant plasmonic nanoantennas for enhanced second harmonic generation

    Science.gov (United States)

    Celebrano, Michele; Wu, Xiaofei; Baselli, Milena; Großmann, Swen; Biagioni, Paolo; Locatelli, Andrea; de Angelis, Costantino; Cerullo, Giulio; Osellame, Roberto; Hecht, Bert; Duò, Lamberto; Ciccacci, Franco; Finazzi, Marco

    2015-05-01

    Boosting nonlinear frequency conversion in extremely confined volumes remains a challenge in nano-optics research, but can enable applications in nanomedicine, photocatalysis and background-free biosensing. To obtain brighter nonlinear nanoscale sources, approaches that enhance the electromagnetic field intensity and counter the lack of phase matching in nanoplasmonic systems are often employed. However, the high degree of symmetry in the crystalline structure of plasmonic materials (metals in particular) and in nanoantenna designs strongly quenches second harmonic generation. Here, we describe doubly-resonant single-crystalline gold nanostructures with no axial symmetry displaying spatial mode overlap at both the excitation and second harmonic wavelengths. The combination of these features allows the attainment of a nonlinear coefficient for second harmonic generation of ˜5 × 10-10 W-1, enabling a second harmonic photon yield higher than 3 × 106 photons per second. Theoretical estimations point toward the use of our nonlinear plasmonic nanoantennas as efficient platforms for label-free molecular sensing.

  9. Mode matching in multiresonant plasmonic nanoantennas for enhanced second harmonic generation.

    Science.gov (United States)

    Celebrano, Michele; Wu, Xiaofei; Baselli, Milena; Großmann, Swen; Biagioni, Paolo; Locatelli, Andrea; De Angelis, Costantino; Cerullo, Giulio; Osellame, Roberto; Hecht, Bert; Duò, Lamberto; Ciccacci, Franco; Finazzi, Marco

    2015-05-01

    Boosting nonlinear frequency conversion in extremely confined volumes remains a challenge in nano-optics research, but can enable applications in nanomedicine, photocatalysis and background-free biosensing. To obtain brighter nonlinear nanoscale sources, approaches that enhance the electromagnetic field intensity and counter the lack of phase matching in nanoplasmonic systems are often employed. However, the high degree of symmetry in the crystalline structure of plasmonic materials (metals in particular) and in nanoantenna designs strongly quenches second harmonic generation. Here, we describe doubly-resonant single-crystalline gold nanostructures with no axial symmetry displaying spatial mode overlap at both the excitation and second harmonic wavelengths. The combination of these features allows the attainment of a nonlinear coefficient for second harmonic generation of ∼5 × 10(-10) W(-1), enabling a second harmonic photon yield higher than 3 × 10(6) photons per second. Theoretical estimations point toward the use of our nonlinear plasmonic nanoantennas as efficient platforms for label-free molecular sensing.

  10. Evaluation of the optical axis tilt of Zinc oxide films via noncollinear second harmonic generation

    CERN Document Server

    Bovino, Fabio Antonio; Belardini, Alessandro; Sibilia, Concita

    2009-01-01

    We investigated noncollinear second harmonic generation form Zinc oxide films, grown on glass substrates by dual ion beam sputtering technique. At a fixed incidence angle, the generated signal is investigated by scanning the polarization state of both fundamental beams. We show that the map of the generated signal as a function of polarization states of both pump beams, together with the analytical curves, allows to retrieve the orientation of the optical axis and, eventually, its angular tilt, with respect to the surface normal

  11. Second harmonic generation from metamaterials strongly coupled to intersubband transitions in quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Campione, Salvatore, E-mail: sncampi@sandia.gov [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Center for Integrated Nanotechnologies (CINT), Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Department of Electrical Engineering and Computer Science, University of California Irvine, Irvine, California 92697 (United States); Benz, Alexander; Brener, Igal, E-mail: ibrener@sandia.gov [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Center for Integrated Nanotechnologies (CINT), Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Sinclair, Michael B. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Capolino, Filippo [Department of Electrical Engineering and Computer Science, University of California Irvine, Irvine, California 92697 (United States)

    2014-03-31

    We theoretically analyze the second harmonic generation capacity of two-dimensional periodic metamaterials comprising sub-wavelength resonators strongly coupled to intersubband transitions in quantum wells (QWs) at mid-infrared frequencies. The metamaterial is designed to support a fundamental resonance at ∼30 THz and an orthogonally polarized resonance at the second harmonic frequency (∼60 THz), while the asymmetric quantum well structure is designed to provide a large second order susceptibility. Upon continuous wave illumination at the fundamental frequency we observe second harmonic signals in both the forward and backward directions, with the forward efficiency being larger. We calculate the overall second harmonic conversion efficiency of the forward wave to be ∼1.3 × 10{sup −2} W/W{sup 2}—a remarkably large value, given the deep sub-wavelength dimensions of the QW structure (about 1/15th of the free space wavelength of 10 μm). The results shown in this Letter provide a strategy for designing easily fabricated sources across the entire infrared spectrum through proper choice of QW and resonator designs.

  12. A study of electric-field-induced second-harmonic generation in asymmetrical Gaussian potential quantum wells

    Science.gov (United States)

    Zhai, Wangjian

    2014-12-01

    Electric-field-induced second-harmonic generation in asymmetrical Gaussian potential quantum wells is investigated using the effective mass approximation employing the compact density matrix method and the iterative approach. Our results show that the absolute value, the real part and the imaginary part of second-harmonic generation are greatly affected by the height of the Gaussian potential quantum wells, the range of the Gaussian confinement potential and the applied electric field. The relationship between the absolute value and the imaginary part of second-harmonic generation together with the relationship between the absolute value and the real part of second-harmonic generation is studied. It is found that no matter how the height of the Gaussian potential quantum wells, the range of the Gaussian confinement potential and the applied electric field vary, the resonant peaks of the absolute value of second-harmonic generation do not originate from the imaginary part but from the real part.

  13. Determine electric field directions at semiconductor surfaces by femtosecond frequency domain interferometric second harmonic (FDISH) generation

    Science.gov (United States)

    Nelson, C. A.; Zhu, X.-Y.

    2016-10-01

    Optical excitations at semiconductor surfaces or interfaces are accompanied by transient interfacial electric fields due to charge redistribution or transfer. While such transient fields may be probed by time-resolved second harmonic generation (TR-SHG), it is difficult to determine the field direction, which is invaluable to unveiling the underlying physics. Here we apply a time-resolved frequency domain interferometric second harmonic (TR-FDISH) generation technique to determine the phase relationship between the SH field emitted from bulk GaAs(1 0 0) and the transient SH field from the space charge region. The interference between these two SH fields allow us to unambiguously determine the directions of transient electric fields. Since SH fields from a static bulk contribution and a changing electric field contribution are present at most semiconductor surfaces or interfaces under optical excitation, the TR-FDISH technique is of general significance to probing the dynamics of interfacial charge transfer/redistribution.

  14. Monitoring of collagen shrinkage by use of second harmonic generation microscopy

    Science.gov (United States)

    Lin, Sung-Jan; Chen, Jau-Shiuh; Lo, Wen; Sun, Yen; Chen, Wei-Liang; Chan, Jung-Yi; Tan, Hsin-Yuan; Lin, Wei-Chou; Hsu, Chih-Jung; Young, Tai-Horng; Jee, Shiou-Hwa; Dong, Chen-Yuan

    2006-02-01

    Thermal treatment induced collagen shrinkage has a great number of applications in medical practice. Clinically, the there is lack of reliable non-invasive methods to quantify the shrinkage. Overt treatment by heat application can lead to devastating results. We investigate the serial changes of collagen shrinkage by thermal treatment of rat tail tendons. The change in length is correlated with the finding in second harmonic generation microscopy and histology. Rat tail tendon shortens progressively during initial thermal treatment. After a certain point in time, the length then remains almost constant despite further thermal treatment. The intensity of second harmonic generation signals also progressively decreases initially and then remains merely detectable upon further thermal treatment. It prompts us to develop a mathematic model to quantify the dependence of collagen shrinkage on changes of SHG intensity. Our results show that SHG intensity can be used to predict the degree of collagen shrinkage during thermal treatment for biomedical applications.

  15. Resonant second-harmonic-generation circular-dichroism microscopy reveals molecular chirality in native biological tissues

    CERN Document Server

    Chen, Mei-Yu; Kan, Che-Wei; Lin, Yen-Yin; Ye, Cin-Wei; Wu, Meng-Jer; Liu, Hsiang-Lin; Chu, Shi-Wei

    2016-01-01

    Conventional linear optical activity effects are widely used for studying chiral materials. However, poor contrast and artifacts due to sample anisotropy limit the applicability of these methods. Here we demonstrate that nonlinear second-harmonic-generation circular dichroism spectral microscopy can overcome these limits. In intact collagenous tissues, clear spectral resonance is observed with sub-micrometer spatial resolution. By performing gradual protein denaturation studies, we show that the resonant responses are dominantly due to the molecular chirality.

  16. Photoinduced Second Harmonic Generation of Bi2S3 Microcrystallite Doped Silica Glass

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Silica glasses doped with Bi2S3 microcystallite was prepared by the sol-gel process. Photoinduced second harmonic generation (SHG) was observed in the glass when it was irradiated with intense 1.06 μm and frequency doubled laser beams from a mode-locked Nd: YAG laser. It was found that the signal intensity increased with the irradiating time and approached a saturation gradually.The effect may be explained reasonably by the DC field model.

  17. Second-harmonic generation in shear wave beams with different polarizations

    Energy Technology Data Exchange (ETDEWEB)

    Spratt, Kyle S., E-mail: sprattkyle@gmail.com; Ilinskii, Yurii A.; Zabolotskaya, Evgenia A.; Hamilton, Mark F. [Applied Research Laboratories, The University of Texas at Austin, P. O. Box 8029, Austin, Texas 78713–8029, US (United States)

    2015-10-28

    A coupled pair of nonlinear parabolic equations was derived by Zabolotskaya [1] that model the transverse components of the particle motion in a collimated shear wave beam propagating in an isotropic elastic solid. Like the KZK equation, the parabolic equation for shear wave beams accounts consistently for the leading order effects of diffraction, viscosity and nonlinearity. The nonlinearity includes a cubic nonlinear term that is equivalent to that present in plane shear waves, as well as a quadratic nonlinear term that is unique to diffracting beams. The work by Wochner et al. [2] considered shear wave beams with translational polarizations (linear, circular and elliptical), wherein second-order nonlinear effects vanish and the leading order nonlinear effect is third-harmonic generation by the cubic nonlinearity. The purpose of the current work is to investigate the quadratic nonlinear term present in the parabolic equation for shear wave beams by considering second-harmonic generation in Gaussian beams as a second-order nonlinear effect using standard perturbation theory. In order for second-order nonlinear effects to be present, a broader class of source polarizations must be considered that includes not only the familiar translational polarizations, but also polarizations accounting for stretching, shearing and rotation of the source plane. It is found that the polarization of the second harmonic generated by the quadratic nonlinearity is not necessarily the same as the polarization of the source-frequency beam, and we are able to derive a general analytic solution for second-harmonic generation from a Gaussian source condition that gives explicitly the relationship between the polarization of the source-frequency beam and the polarization of the second harmonic.

  18. Enhanced second-harmonic generation driven from magnetic dipole resonance in AlGaAs nanoantennas

    Science.gov (United States)

    Carletti, Luca; Rocco, Davide; Locatelli, Andrea; Gili, Valerio; Leo, Giuseppe; De Angelis, Costantino

    2016-04-01

    We model the linear and nonlinear optical response of disk-shaped AlGaAs nanoantennas. We design nanoantennas with a magnetic dipole resonant mode in the near-infrared wavelength range, and we analyze volume second-harmonic generation driven by a magnetic dipole resonance by predicting a conversion efficiency exceeding 10-3 with 1 GW/cm2 of pump intensity.

  19. Second-Harmonic Generation in Optical Fibres Induced by a Cross-Phase Modulation Effect

    Institute of Scientific and Technical Information of China (English)

    CUI Wei-Na; HUANG Guo-Xiang

    2005-01-01

    @@ When two optical pulses copropagate inside a single-modefibre, intensity-dependent refractive index couples the pulses through a cross-phase modulation (XPM). We show that a second-harmonic generation (SHG) on a continuous-wave background is possible in the optical fibre induced by the XPM effect. By means of a multiscale method the nonlinearly coupled envelope equations for the SHG are derived and their explicit solutions are provided and discussed.

  20. Grain size effect of monolayer MoS2 transistors characterized by second harmonic generation mapping

    KAUST Repository

    Lin, Chih-Pin

    2015-08-27

    We investigated different CVD-synthesized MoS2 films, aiming to correlate the device characteristics with the grain size. The grain size of MoS2 can be precisely characterized through nondestructive second harmonic generation mapping based on the degree of inversion symmetry. The devices with larger grains at the channel region show improved on/off current ratio, which can be explained by the less carrier scattering caused by the grain boundaries.

  1. Multibeam second-harmonic generation by spatiotemporal shaping of femtosecond pulses.

    Science.gov (United States)

    Martínez-Cuenca, Raúl; Mendoza-Yero, Omel; Alonso, Benjamín; Sola, Íñigo Juan; Mínguez-Vega, Gladys; Lancis, Jesús

    2012-03-01

    We present a technique for efficient generation of the second-harmonic signal at several points of a nonlinear crystal simultaneously. Multispot operation is performed by using a diffractive optical element that splits the near-infrared light of a mode-locked Ti:sapphire laser into an arbitrary array of beams that are transformed into an array of foci at the nonlinear crystal. We show that, for pulse temporal durations under 100 fs, spatiotemporal shaping of the pulse is mandatory to overcome chromatic dispersion effects that spread both in space and time the foci showing a reduced peak intensity that prevents nonlinear phenomena. We experimentally demonstrate arbitrary irradiance patterns for the second-harmonic signal consisting of more than 100 spots with a multipass amplifier delivering 28 fs, 0.8 mJ pulses at 1 kHz repetition rate.

  2. Second Harmonic Generation and Confined Acoustic Phonons in HighlyExcited Semiconductor Nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Son, Dong Hee; Wittenberg, Joshua S.; Banin, Uri; Alivisatos, A.Paul

    2006-03-30

    The photo-induced enhancement of second harmonic generation, and the effect of nanocrystal shape and pump intensity on confined acoustic phonons in semiconductor nanocrystals, has been investigated with time-resolved scattering and absorption measurements. The second harmonic signal showed a sublinear increase of the second order susceptibility with respect to the pump pulse energy, indicating a reduction of the effective one-electron second-order nonlinearity with increasing electron-hole density in the nanocrystals. The coherent acoustic phonons in spherical and rod-shaped semiconductor nanocrystals were detected in a time-resolved absorption measurement. Both nanocrystal morphologies exhibited oscillatory modulation of the absorption cross section, the frequency of which corresponded to their coherent radial breathing modes. The amplitude of the oscillation also increased with the level of photoexcitation, suggesting an increase in the amplitude of the lattice displacement as well.

  3. Second-harmonic generation in single-mode integrated waveguides through mode-shape modulation

    CERN Document Server

    Chiles, Jeff; Rao, Ashutosh; Malinowski, Marcin; Camacho-González, Guillermo Fernando; Fathpour, Sasan

    2016-01-01

    A simple and flexible technique for achieving quasi-phase-matching in integrated photonic waveguides without periodic poling is proposed and experimentally demonstrated, referred to as mode-shape-modulation (MSM). It employs a periodic variation of waveguide width to modulate the intensity of the pump wave, effectively suppressing out-of-phase light generation. This technique is applied to the case of second-harmonic generation in thin-film lithium niobate ridge waveguides. MSM waveguides are fabricated and characterized with pulsed-pumping in the near-infrared, showing harmonic generation at a signal wavelength of 784 nm.

  4. Surface plasmon polariton excitation by second harmonic generation in single organic nanofibers.

    Science.gov (United States)

    Simesen, Paw; Søndergaard, Thomas; Skovsen, Esben; Fiutowski, Jacek; Rubahn, Horst-Günter; Bozhevolnyi, Sergey I; Pedersen, Kjeld

    2015-06-15

    Coherent local excitation of surface plasmon polaritons (SPPs) by second-harmonic generation (SHG) in individual aligned crystalline organic functionalized para-phenylene nanofibers deposited on a thin silver film is demonstrated. The SH-SPP generation is considered theoretically and investigated experimentally with angular-resolved leakage radiation spectroscopy for normal incidence of the excitation beam. Both measurements and simulations show asymmetric excitation of left- and right-propagating SH-SPPs, which is explained as an effect of fiber molecules being oriented at an angle relative to the silver film surface.

  5. Selective imaging in second-harmonic-generation microscopy by polarization manipulation

    Science.gov (United States)

    Chu, Shi-Wei; Tai, Shih-Peng; Sun, Chi-Kuang; Lin, Chi-Hung

    2007-09-01

    Second-harmonic-generation (SHG) has proved itself as an important contrast mechanism in microscopic applications. Its noninvasiveness, optical sectioning capability, and high-penetrability provide attractive features in observation of thick biological tissues. Fibrous proteins, such as myosin and collagen, are dominant SHG harmonophores in vertebrates. Due to their biophotonic crystal nature, SHGs from these proteins are known to exhibit specific polarization dependencies, reflecting local molecule arrangements. Here the authors demonstrate a scheme to distinguish SHG from myosin-based muscle fibers and intertwined collagenous perimysium through polarization selection, without complicated staining or sample/image processing required.

  6. Characterization of magnetization-induced second harmonic generation in iron oxide polymer nanocomposites.

    Science.gov (United States)

    Vandendriessche, Stefaan; Valev, Ventsislav K; Verbiest, Thierry

    2012-01-10

    We have measured the magnetization-induced second harmonic generation (MSHG) of a nanocomposite consisting of iron oxide nanoparticles in a polymer film. The existing theoretical framework is extended to include DC magnetic fields in order to characterize the MSHG signal and analyze the measurements. Additionally, magnetic hysteresis loops are measured for four principal polarizer-analyzer configurations, revealing the P(IN)-P(OUT) and S(IN)-P(OUT) polarizer-analyzer configurations to be sensitive to the transverse magnetic field. These results demonstrate the use of MSHG and the applied formalism as a tool to study magnetic nanoparticles and their magnetic properties.

  7. Nanoscale optical properties of metal nanoparticles probed by Second Harmonic Generation microscopy.

    Science.gov (United States)

    Shen, Hong; Nguyen, Ngoc; Gachet, David; Maillard, Vincent; Toury, Timothée; Brasselet, Sophie

    2013-05-20

    We report spatial and vectorial imaging of local fields' confinement properties in metal nanoparticles with branched shapes, using Second Harmonic Generation (SHG) microscopy. Taking advantage of the coherent nature of this nonlinear process, the technique provides a direct evidence of the coupling between the excitation polarization and both localization and polarization specificities of local fields at the sub-diffraction scale. These combined features, which are governed by the nanoparticles' symmetry, are not accessible using other contrasts such as linear optical techniques or two-photon luminescence.

  8. Organic inclusion complex novel materials for optical second-harmonic generation in ultraviolet region

    Science.gov (United States)

    Meng, Fanqing; Lu, Mengkai

    1996-10-01

    Herein is presented a new class of materials for second harmonic generation (SHG) -- organic inclusion complex, in which 'SHG-active units' (guest) are incorporated into chiral handle polycondensed anions (host) through short hydrogen bonds. The former can provide nonlinear optical response. The latter is expected to produce noncentrosymmetric structural 'molecular framework' and improve fundamental properties of materials such as thermal stability, mechanical strength and fabrication behavior, et al. Several new SHG active inclusion complexes were synthesized. In particular, optically fine bulk crystals of urea-(d)tartaric acid (UDT) and urea-(dl)tartaric acid (UDLT) have been obtained. They have good powder SHG intensity and short cutoff wavelengths.

  9. Second harmonic generation imaging of collagen fibrils in cornea and sclera

    Science.gov (United States)

    Han, Meng; Giese, Günter; Bille, Josef F.

    2005-07-01

    Collagen, as the most abundant protein in the human body, determines the unique physiological and optical properties of the connective tissues including cornea and sclera. The ultrastructure of collagen, which conventionally can only be resolved by electron microscopy, now can be probed by optical second harmonic generation (SHG) imaging. SHG imaging revealed that corneal collagen fibrils are regularly packed as a polycrystalline lattice, accounting for the transparency of cornea. In contrast, scleral fibrils possess inhomogeneous, tubelike structures with thin hard shells, maintaining the high stiffness and elasticity of the sclera.

  10. Electric-field-induced second harmonic generation in GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Lafrentz, Marco; Brunne, David; Kaminski, Benjamin; Bayer, Manfred [Experimentelle Physik 2, Technische Universitaet Dortmund, D-44221 Dortmund (Germany); Yakovlev, Dmitri R. [Experimentelle Physik 2, Technische Universitaet Dortmund, D-44221 Dortmund (Germany); Ioffe Physico-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation); Pavlov, Victor V.; Pisarev, Roman V. [Ioffe Physico-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation)

    2011-07-01

    We report on electric-field-induced second-harmonic generation (SHG) in the GaAs semiconductor in the vicinity of the band gap. The light has been send along 001-crystallographic direction. In this geometry SHG is forbidden in electric-dipole approximation. In applied electric field the SHG signal arises due to field-induced symmetry breaking causing new optical nonlinearities. Electric-field and temperature investigations assign the strong signal at E(2{omega})=1.517 eV for T=2 K to excitonic resonance. This phenomenon is a supplementary tool for detailed investigation of complex susceptibilities we have reported on in the past.

  11. Impact of longitudinal fields on second harmonic generation in lithium niobate nanopillars

    Science.gov (United States)

    Baghban, Mohammad Amin; Gallo, Katia

    2016-09-01

    An optimized focused ion beam process is used to fabricate micrometer-long LiNbO3 nanopillars with diameters varying between 150 and 325 nm. Polarimetric mappings of second harmonic generation from a wavelength of 850 nm demonstrate the ability to modify the polarization features of the nonlinear response through a fine adjustment of the pillar size. The effect is ascribed to the non-negligible contribution of the longitudinal fields associated with sub-wavelength light confinement in the LiNbO3 nanopillars. The results also highlight the importance of a fine control over the nanopillar size in order to effectively engineer their nonlinear response.

  12. Near-Field Second-Harmonic Generation Induced by Local Field Enhancement

    OpenAIRE

    Bouhelier, Alexandre; Beversluis, M.; Hartschuh, Achim; Novotny, Lukas

    2003-01-01

    The field near a sharp metal tip can be strongly enhanced if irradiated with an optical field polarized along the tip axis. We demonstrate that the enhanced field gives rise to local second-harmonic (SH) generation at the tip surface thereby creating a highly confined photon source. A theoretical model for the excitation and emission of SH radiation at the tip is developed and it is found that this source can be represented by a single on-axis oscillating dipole. The model is experimentally v...

  13. Electric field-induced optical second harmonic generation in nematic liquid crystal 5CB

    Science.gov (United States)

    Torgova, S. I.; Shigorin, V. D.; Maslyanitsyn, I. A.; Todorova, L.; Marinov, Y. G.; Hadjichristov, G. B.; Petrov, A. G.

    2014-12-01

    Electric field-induced second harmonic generation (EFISH) was studied for the liquid crystal 4-cyano-4'-pentylbiphenyl (5CB) (a nematic phase material at room temperature). The intensity of coherent SHG from 5CB cells upon DC electric field was measured for various initial orientations of the liquid crystal. The dependence of the SHG intensity on the pump beam incidence angle was obtained in transmission geometry using sample rotation method. The experimental results (the registered light intensity in the output SHG interference patterns) were theoretically modelled and analyzed.

  14. Quantitative biomarkers of colonic dysplasia based on intrinsic second-harmonic generation signal

    Science.gov (United States)

    Zhuo, Shuangmu; Zhu, Xiaoqin; Wu, Guizhu; Chen, Jianxin; Xie, Shusen

    2011-12-01

    Most colorectal cancers arise from dysplastic lesions, such as adenomatous polyps, and these lesions are difficult to be detected by the current endoscopic screening approaches. Here, we present the use of an intrinsic second-harmonic generation (SHG) signal as a novel means to differentiate between normal and dysplastic human colonic tissues. We find that the SHG signal can quantitatively identify collagen change associated with colonic dysplasia that is indiscernible by conventional pathologic techniques. By comparing normal with dysplastic mucosa, there were significant differences in collagen density and collagen fiber direction, providing substantial potential to become quantitative intrinsic biomarkers for in vivo clinical diagnosis of colonic dysplasia.

  15. Orbital Angular Momentum in Noncollinear Second Harmonic Generation by off-axis vortex beams

    CERN Document Server

    Bovino, Fabio Antonio; Giardina, Maurizio; Sibilia, Concita

    2011-01-01

    We experimentally study the behavior of orbital angular momentum (OAM) of light in a noncollinear second harmonic generation (SHG) process. The experiment is performed by using a type I BBO crystal under phase matching conditions with femtosecond pumping fields at 830 nm. Two specular off-axis vortex beams carrying fractional orbital angular momentum at the fundamental frequency (FF) are used. We analyze the behavior of the OAM of the SH signal when the optical vortex of each input field at the FF is displaced from the beam's axis. We obtain different spatial configurations of the SH field, always carrying the same zero angular momentum.

  16. Second-harmonic generation with zero group-velocity mismatch in nonlinear photonic crystal fibers

    DEFF Research Database (Denmark)

    Bache, Morten; Lægsgaard, Jesper; Bang, Ole;

    2006-01-01

    We consider an index-guiding silica photonic crystal fiber with a triangular hole-pattern and a periodically poled quadratic nonlinearity. By tuning the pitch and the relative size of the holes, second-harmonic generation with zero group-velocity mismatch is found to be feasible for any fundamental...... wavelength above 780 nm. The phase-velocity mismatch has a lower limit with coherence lengths in the micron range. The nonlinear strength is optimized when the fundamental has maximum confinement in the core. The conversion bandwidth allows for fs-pulse conversion and 4-180%/(Wmiddotcm2) relative...

  17. Application of quantitative second-harmonic generation microscopy to dynamic conditions.

    Science.gov (United States)

    Kabir, Mohammad M; Inavalli, V V G Krishna; Lau, Tung-Yuen; Toussaint, Kimani C

    2013-01-01

    We present a quantitative second-harmonic generation (SHG) imaging technique that quantifies the 2D spatial organization of collagen fiber samples under dynamic conditions, as an image is acquired. The technique is demonstrated for both a well-aligned tendon sample and a randomly aligned, sparsely distributed collagen scaffold sample. For a fixed signal-to-noise ratio, we confirm the applicability of this method for various window sizes (pixel areas) as well as with using a gridded overlay map that allows for correlations of fiber orientations within a given image. This work has direct impact to in vivo biological studies by incorporating simultaneous SHG image acquisition and analysis.

  18. Growth direction of oblique angle electron beam deposited silicon monoxide thin films identified by optical second-harmonic generation

    Energy Technology Data Exchange (ETDEWEB)

    Vejling Andersen, Søren; Lund Trolle, Mads; Pedersen, Kjeld [Department of Physics and Nanotechnology, Aalborg University, Skjernvej 4A, DK-9220 Aalborg Øst (Denmark)

    2013-12-02

    Oblique angle deposited (OAD) silicon monoxide (SiO) thin films forming tilted columnar structures have been characterized by second-harmonic generation. It was found that OAD SiO leads to a rotationally anisotropic second-harmonic response, depending on the optical angle of incidence. A model for the observed dependence of the second-harmonic signal on optical angle of incidence allows extraction of the growth direction of OAD films. The optically determined growth directions show convincing agreement with cross-sectional scanning electron microscopy images. In addition to a powerful characterization tool, these results demonstrate the possibilities for designing nonlinear optical devices through SiO OAD.

  19. Optical second-harmonic generation in lossy media: Application to GaSe and InSe

    Science.gov (United States)

    Bringuier, E.; Bourdon, A.; Piccioli, N.; Chevy, A.

    1994-06-01

    The paper deals with optical second-harmonic generation in a medium absorbing the second-harmonic radiation, and where phase matching between the fundamental and second-harmonic radiation is not necessarily achieved. We first take the waves to be in the form of traveling waves, and describe the damping of the fundamental beam due to harmonic creation. It is found that both second-harmonic absorption and phase mismatch enhance the depletion length of the pump wave. Before depletion, the second-harmonic output power is independent of the traversed thickness if it exceeds the second-harmonic attenuation length. When depletion occurs, the second-harmonic output power is constant, instead of quadratic, in the input power. Next, second-harmonic generation in a plane-parallel plate of lossy material is envisaged in the case of normal incidence, including the multiple reflections expected in high-reflectance materials. The expressions of the harmonic output intensity, transmitted or reflected, of this paper and from the conventional treatment, are compared. The deviation is noticeable in the case of the transmitted harmonic power, and may be considerable in the case of the reflected power. Last, measurements of the second-harmonic output intensity in GaSe and InSe are reported at a fundamental wavelength of 1.06 μm. The sample dependence is in good agreement with our theory, which in turn is applied to derive new values of the nonlinear optical susceptibilities in the layered-structured III-VI materials. The treatment is fully analytical and may be applied to a wealth of materials.

  20. Quantitative second-harmonic generation imaging to detect osteogenesis imperfecta in human skin samples

    Science.gov (United States)

    Adur, J.; Ferreira, A. E.; D'Souza-Li, L.; Pelegati, V. B.; de Thomaz, A. A.; Almeida, D. B.; Baratti, M. O.; Carvalho, H. F.; Cesar, C. L.

    2012-03-01

    Osteogenesis Imperfecta (OI) is a genetic disorder that leads to bone fractures due to mutations in the Col1A1 or Col1A2 genes that affect the primary structure of the collagen I chain with the ultimate outcome in collagen I fibrils that are either reduced in quantity or abnormally organized in the whole body. A quick test screening of the patients would largely reduce the sample number to be studied by the time consuming molecular genetics techniques. For this reason an assessment of the human skin collagen structure by Second Harmonic Generation (SHG) can be used as a screening technique to speed up the correlation of genetics/phenotype/OI types understanding. In the present work we have used quantitative second harmonic generation (SHG) imaging microscopy to investigate the collagen matrix organization of the OI human skin samples comparing with normal control patients. By comparing fibril collagen distribution and spatial organization, we calculated the anisotropy and texture patterns of this structural protein. The analysis of the anisotropy was performed by means of the two-dimensional Discrete Fourier Transform and image pattern analysis with Gray-Level Co-occurrence Matrix (GLCM). From these results, we show that statistically different results are obtained for the normal and disease states of OI.

  1. Second harmonic generation in nanoscale films of transition metal dichalcogenide: Accounting for multipath interference

    Directory of Open Access Journals (Sweden)

    A. V. Kudryavtsev

    2016-09-01

    Full Text Available The transfer matrix method has been widely used to calculate wave propagation through the layered structures consisting entirely of either linear or nonlinear optical materials. In the present work, we develop the transfer matrix method for structures consisting of alternating layers of linear and nonlinear optical materials. The result is presented in a form that allows one to directly substitute the values of material constants, refractive index and absorption coefficient, into the expressions describing the second harmonic generation (SHG field. The model is applied to the calculation of second harmonic (SH field generated in nano-thin layers of transition metal dichalcogenides exfoliated on top of silicon oxide/silicon Fabry-Perot cavity. These structures are intensively studied both in view of their unique properties and perspective applications. A good agreement between experimental and numerical results can be achieved by small modification of optical constants, which may arise in an experiment due to a strong electric field of an incident focused pump laser beam. By considering the SHG effect, this paper completes the series of works describing the role of Fabry-Perot cavity in different optical effects (optical reflection, photoluminescence and Raman scattering in 2D semiconductors that is extremely important for characterization of these unique materials.

  2. Second harmonic generation in nanoscale films of transition metal dichalcogenide: Accounting for multipath interference

    Science.gov (United States)

    Kudryavtsev, A. V.; Lavrov, S. D.; Shestakova, A. P.; Kulyuk, L. L.; Mishina, E. D.

    2016-09-01

    The transfer matrix method has been widely used to calculate wave propagation through the layered structures consisting entirely of either linear or nonlinear optical materials. In the present work, we develop the transfer matrix method for structures consisting of alternating layers of linear and nonlinear optical materials. The result is presented in a form that allows one to directly substitute the values of material constants, refractive index and absorption coefficient, into the expressions describing the second harmonic generation (SHG) field. The model is applied to the calculation of second harmonic (SH) field generated in nano-thin layers of transition metal dichalcogenides exfoliated on top of silicon oxide/silicon Fabry-Perot cavity. These structures are intensively studied both in view of their unique properties and perspective applications. A good agreement between experimental and numerical results can be achieved by small modification of optical constants, which may arise in an experiment due to a strong electric field of an incident focused pump laser beam. By considering the SHG effect, this paper completes the series of works describing the role of Fabry-Perot cavity in different optical effects (optical reflection, photoluminescence and Raman scattering) in 2D semiconductors that is extremely important for characterization of these unique materials.

  3. Second-harmonic generation in metallic nanoparticles: Clarification of the role of the surface

    Science.gov (United States)

    Ciracì, Cristian; Poutrina, Ekaterina; Scalora, Michael; Smith, David R.

    2012-09-01

    We present a numerical investigation of the second-order nonlinear optical properties of metal-based metamaterial nanoresonators. The nonlinear optical response of the metal is described by a hydrodynamic model, with the effects of electron pressure in the electron gas also taken into account. We show that as the pressure term tends to zero the amount of converted second-harmonic field tends to an asymptotic value. In this limit it becomes possible to rewrite the nonlinear surface contributions as functions of the value of the polarization vector inside the bulk region. Nonlocality thus can be incorporated into numerical simulations without actually utilizing the nonlocal equation of motion or solving for the rapidly varying fields that occur near the metal surface. We use our model to investigate the second-harmonic generation process with three-dimensional gold nanoparticle arrays and show that nanocrescents can easily attain conversion efficiencies of ˜6.0×10-8 for pumping peak intensities of a few tens of MW/cm2.

  4. Enhanced second harmonic generation of MoS2 layers on a thin gold film.

    Science.gov (United States)

    Zeng, Jianhua; Yuan, Maohui; Yuan, Weiguang; Dai, Qiaofeng; Fan, Haihua; Lan, Sheng; Tie, Shaolong

    2015-08-28

    The linear and nonlinear optical properties of thin MoS2 layers exfoliated on an Au/SiO2 substrate were investigated both numerically and experimentally. It was found that the MoS2 layers with different thicknesses exhibited different colors on the gold film. The reflection spectra of the MoS2 layers with different thicknesses were calculated by using the finite-difference time-domain technique and the corresponding chromaticity coordinates were derived. The electric field enhancement factors at both the fundamental light and the second harmonic were calculated and the enhancement factors for second harmonic generation (SHG) were estimated for the MoS2 layers with different thicknesses. Different from the MoS2 layers on a SiO2/Si substrate where the maximum SHG was observed in the single-layer MoS2, the maximum SHG was achieved in the 17 nm-thick MoS2 layer on the Au/SiO2 substrate. As compared with the MoS2 layers on the SiO2/Si substrate, a significant enhancement in SHG was found for the MoS2 layers on the Au/SiO2 substrate due to the strong localization of the electric field. More interestingly, it was demonstrated experimentally that optical data storage can be realized by modifying the SHG intensity of a MoS2 layer through thinning its thickness.

  5. Second harmonic generation polarization microscopy with tightly focused linearly and radially polarized beams

    Science.gov (United States)

    Yew, E. Y. S.; Sheppard, C. J. R.

    2007-07-01

    Second harmonic generation microscopy was conducted on rat-tail tendons with linearly and radially polarized beams. Transverse and axial field components were generated in the focal region through tight focusing of linearly and radially polarized. It was found that the generated SHG signals could not be qualitatively explained with a scalar approximation to the electric field at the focus. Only by accounting for the interactions of the axial and transverse components of the electric field interacting through the nonlinear susceptibility χ(2) tensor could the SHG images be explained. For the case of collagen we find that the SHG signal varies as a function of the analyzer angle with a cos2 or sin2 dependency for linearly polarized beams. For tightly focused radially polarized beams we find that the output SHG is radially polarized after collimation and is independent of the analyzer angle.

  6. Time-domain analysis of second-harmonic generation of primary Lamb wave propagation in an elastic plate

    Institute of Scientific and Technical Information of China (English)

    Deng Ming-Xi; Xiang Yan-Xun

    2010-01-01

    Within the second-order perturbation approximation,this paper investigates the physical process of generation of the time-domain second harmonic by a primary Lamb wave waveform in an elastic plate.The present work is performed based on the preconditions that the phase velocity matching is satisfied and that the transfer of energy from the primary Lamb wave to the double frequency Lamb wave is not zero.It investigates the influences of the difference between the group velocities of the primary Lamb wave and the double frequency Lamb wave,the propagation distance and the duration of the primary Lamb wave waveform on the envelope shape of the time-domain second harmonic.It finds that the maximum magnitude of the envelope of the second-harmonic waveform can grow within some propagation distance even if the condition of group velocity matching is not satisfied.Our analyses also indicate that the maximum magnitude of the envelope of the second-harmonic waveform is kept constant beyond a specific propagation distance.Furthermore,it concludes that the integration amplitude of the time-domain second-harmonic waveform always grows with propagation distance within the second-order perturbation.The present research yields new physical insight not previously available into the effect of generation of the time-domain second harmonic by propagation of a primary Lamb wave waveform.

  7. Integrated GaN photonic circuits on silicon (100) for second harmonic generation

    CERN Document Server

    Xiong, Chi; Ryu, Kevin K; Schuck, Carsten; Fong, King Y; Palacios, Tomas; Tang, Hong X

    2014-01-01

    We demonstrate second order optical nonlinearity in a silicon architecture through heterogeneous integration of single-crystalline gallium nitride (GaN) on silicon (100) substrates. By engineering GaN microrings for dual resonance around 1560 nm and 780 nm, we achieve efficient, tunable second harmonic generation at 780 nm. The \\{chi}(2) nonlinear susceptibility is measured to be as high as 16 plus minus 7 pm/V. Because GaN has a wideband transparency window covering ultraviolet, visible and infrared wavelengths, our platform provides a viable route for the on-chip generation of optical wavelengths in both the far infrared and near-UV through a combination of \\{chi}(2) enabled sum-/difference-frequency processes.

  8. Second-harmonic generation from bimetal composites doped with metal nanoparticles

    Science.gov (United States)

    Daneshfar, Nader

    2016-05-01

    In the present paper, we study the nonlinear optical response of the bimetal composites doped with metal nanoparticles in the framework of nonlinear Mie theory combined with the Maxwell-Garnett model. We concentrate on the second-order harmonic generation from bimetal nanocomposites including silver and gold particles, since sometimes the nonlinear optical response is sensitive to the more accurate of material structure than linear optical response. We show that optical second harmonic generation is strongly sensitive to temperature as an environmental parameter, interparticle plasmon coupling between Au and Ag nanoparticles (the filling factor of inclusions), the particle size and the surrounding medium. However, this work shows good potential of bimetal composites for nonlinear optics at the nanoscale.

  9. Second harmonic generation from metallo-dielectric multilayer photonic band gap structures

    CERN Document Server

    Larciprete, M C; Cappeddu, M G; De Ceglia, D; Centini, M; Fazio, E; Sibilia, C; Bloemer, M J; Scalora, M

    2008-01-01

    We experimentally and theoretically investigate the second order nonlinear optical response of metallo-dielectric multilayer structures composed of Ag and Ta2O5 layers, deposited by magnetron sputtering. Second harmonic generation measurements were performed in reflection mode as a function of incidence angle, using femtosecond pulses originating from a Ti:Sapphire laser system tuned at 800 nm. The dependence of the generated signal was investigated as a function of pump intensity and polarization state. Our experimental results show that the conversion efficiency from a periodic metallo-dielectric sample may be enhanced by at least a factor of 30 with respect to the conversion efficiency from a single metal layer, thanks in part to the increased number of active surfaces, pump field localization and penetration inside the metal layers. The conversion efficiency maximum shifts from 70 degrees for the single silver layer down to approximately 55 degrees for the stack. The experimental results are found to be i...

  10. Imaging theory of nonlinear second harmonic and third harmonic generations in confocal microscopy

    Institute of Scientific and Technical Information of China (English)

    TANG; Zhilie; XING; Da; LIU; Songhao

    2004-01-01

    The imaging theory of nonlinear second harmonic generation (SHG) and third harmonic generation (THG) in confocal microscopy is presented in this paper. The nonlinear effect of SHG and THG on the imaging properties of confocal microscopy has been analyzed in detail by the imaging theory. It is proved that the imaging process of SHG and THG in confocal microscopy, which is different from conventional coherent imaging or incoherent imaging, can be divided into two different processes of coherent imaging. The three-dimensional point spread functions (3D-PSF) of SHG and THG confocal microscopy are derived based on the nonlinear principles of SHG and THG. The imaging properties of SHG and THG confocal microscopy are discussed in detail according to its 3D-PSF. It is shown that the resolution of SHG and THG confocal microscopy is higher than that of single-and two-photon confocal microscopy.

  11. Second harmonic generation in nano-structured thin-film lithium niobate waveguides

    CERN Document Server

    Wang, Cheng; Andrade, Nicolas; Venkataraman, Vivek; Ren, Xi-Feng; Guo, Guang-Can; Lončar, Marko

    2016-01-01

    Lithium niobate is the most well-known optical material with a second-order \\c{hi}(2) nonlinearity that is widely employed in modern optical technology. Integrated lithium niobate platform has recently emerged as a promising candidate for next-generation, high-efficiency wavelength conversion systems that allow dense packaging and mass-production. Here we demonstrate efficient, phase-matched second harmonic generation in lithographically-defined thin-film lithium niobate waveguides with sub-micron dimensions. Both natural phase matching in fixed-width waveguides and quasi-phase matching in periodically-grooved waveguides are theoretically proposed and experimentally demonstrated. Our low-loss (~2.52 dB/cm) nanowaveguides possess normalized conversion efficiencies as high as 41% W-1cm-2, promising for future on-chip quantum wavelength conversion.

  12. Chirality study inside biological tissue by second harmonic generation circular dichroism

    Science.gov (United States)

    Hsu, Kuo-Jen; Lee, Hsuan; Zhuo, Guan-Yu; Chao, Pen-Hsiu; Chu, Shi-Wei

    2013-02-01

    Many biological systems are composed of chiral molecules and their functions depend strongly on their chirality. For example, most amino acids are of left-handed chirality while most polysaccharides are of right-handed chirality. Both of them are vital for human life, so it is important to perform chiral detection inside bio-tissues. Here we demonstrated second harmonic generation circular dichroism (SHG-CD) as a novel chiral imaging contrast in thick biotissue. Compared with conventional chiral detection, SHG-CD provides at least three orders higher contrast. In addition, due to the nonlinear nature of SHG, this technique provides optical sectioning capability, so the axial contrast is much better. The advantages of nonlinear optical microscopy are optical sectioning and deep penetration capabilities. The SHG-CD achieved 100% signal contrast with sub-micrometer spatial resolution. This method is expected to offer a novel contrast mechanism of imaging chirality inside complex bio-tissues.

  13. Imaging the noncentrosymmetric structural organisation of tissue with Interferometric Second Harmonic Generation microscopy

    CERN Document Server

    Rivard, Maxime; Laliberte, Mathieu; Bertrand-Grenier, Antony; Martin, Francois; Pepin, Henri; Pfeffer, Christian P; Brown, Cameron; Rammuno, Lora; Legare, Francois

    2012-01-01

    We report the imaging of tendon, a connective tissue rich in collagen type I proteins, with Interferometric Second Harmonic Generation (I-SHG) microscopy. We observed that the noncentrosymmetric structural organization can be maintained along the fibrillar axis over more than 150 {\\mu}m, while in the transverse direction it is ~1-15 {\\mu}m. Those results are explained by modeling tendon as a heterogeneous distribution of noncentrosymmetric nanocylinders (collagen fibrils) oriented along the fibrillar axis. The preservation of the noncentrosymmetric structural organization over multiple tens of microns reveals that tendon is made of domains in which the fraction occupied by fibrils oriented in one direction is larger than in the other.

  14. In situ observation of collagen thermal denaturation by second harmonic generation microscopy

    Science.gov (United States)

    Liao, C.-S.; Zhuo, Z.-Y.; Yu, J.-Y.; Chao, P.-H. G.; Chu, S.-W.

    2010-02-01

    Collagen denaturation is of fundamental importance for clinical treatment. Conventionally, the denaturation process is quantified by the shrinkage of collagen fibers, but the underlying molecular origin has not been fully understood. Since second harmonic generation (SHG) is related to the molecular packing of the triple helix in collagen fibers, this nonlinear signal provides an insight of molecular dynamics during thermal denaturation. With the aid of SHG microscopy, we found a new step in collagen thermal denaturation process, de-crimp. During the de-crimp step, the characteristic crimp pattern of collagen fascicles disappeared due to the breakage of interconnecting bonds between collagen fibrils, while SHG intensity remained unchanged, suggesting the intactness of the triple helical molecules. At higher temperature, shrinkage is observed with strongly reduced SHG intensity, indicating denaturation at the molecular level.

  15. Quantitative analysis of thermally-induced alterations of corneal stroma by second-harmonic generation imaging

    Science.gov (United States)

    Matteini, P.; Rossi, F.; Ratto, F.; Cicchi, R.; Kapsokalyvas, D.; Pavone, F. S.; Pini, R.

    2010-02-01

    Thermal modifications induced in the corneal stroma were investigated by means of second harmonic generation (SHG) imaging. Whole fresh cornea samples were heated in a water bath at temperatures in the 35-80 °C range for a 4-min time. SHG images of the structural modifications induced at each temperature were acquired from different areas of cross-sectioned corneal stroma by using an 880 nm linearly- and circularly-polarized excitation light emitted by a mode-locked Ti:Sapphire laser. The SHG images were then analyzed by means of both an empirical approach and a 2D-theoretical model. The proposed analyses provide a detailed description of the changes occurring in the structural architecture of the cornea during the thermal treatment. Our results allow us to depict a temperature-dependent biochemical model for the progressive destructuration occurring to collagen fibrils and nonfibrillar components of the stroma.

  16. Second-harmonic generation in asymmetric quantum dots in the presence of a static magnetic field

    Institute of Scientific and Technical Information of China (English)

    Li Xue-Chao; Wang An-Min; Wang Zhao-Liang; Yang Yang

    2012-01-01

    The second-harmonic generation (SHG) coefficient in an asymmetric quantum dot (QD) with a static magnetic field is theoretically investigated.Within the framework of the effective-mass approximation,we obtain the confined wave functions and energies of electrons in the QD.We also obtain the SHG coefficient by the compact-density-matrix approach and the iterative method.The numerical results for the typical GaAs/AlGaAs QD show that the SHG coefficient depends strongly on the magnitude of magnetic field,parameters of the asymmetric potential and the radius of the QD.The resonant peak shifts with the magnetic field or the radius of the QD changing.

  17. Theory of enhanced second-harmonic generation in some artificial materials

    Institute of Scientific and Technical Information of China (English)

    HUANG Ji-ping

    2007-01-01

    We review the recent theoretical investigation on enhanced second-harmonic generation (SHG) in soft nonlinear optical materials based on ferrofluids, graded metallic films, and graded metal-dielectric films of anisotropic particles. The SHG of soft ferrofluid-based nonlinear optical materials possess magnetic-field controllabilities, i.e., magnetic-field-controllable anisotropy, red-shift and enhancement, which are caused to appear by the shift of a resonant plasmon frequency due to the formation of the chains of the coated nanoparticles. Both graded metallic films and graded metal-dielectric films of anisotropic particles can serve as a novel optical material for producing a broad structure in both the linear and SHG response and an enhancement in the SHG signal, due to the local field effects.

  18. Observation of second-harmonic generation in silicon nitride waveguides through bulk nonlinearities

    CERN Document Server

    Puckett, Matthew W; Lin, Hung-Hsi; Yang, Muhan; Vallini, Felipe; Fainman, Yeshaiahu

    2016-01-01

    We present experimental results on the observation of a bulk second-order nonlinear susceptibility derived from both free-space and integrated measurements in silicon nitride. Phase-matching is achieved through dispersion engineering of the waveguide cross-section, independently revealing multiple components of the nonlinear susceptibility, namely X(2)yyy and X(2)xxy. Additionally, we show how the generated second-harmonic signal may be actively tuned through the application of bias voltages across silicon nitride. The nonlinear material properties measured here are anticipated to allow for the practical realization of new nanophotonic devices in CMOS-compatible silicon nitride waveguides, adding to their viability for telecommunication, data communication, and optical signal processing applications.

  19. Second harmonic generation studies in L-alanine single crystals grown from solution

    Science.gov (United States)

    Boomadevi, Shanmugam; Pandiyan, Krishnamoorthy

    2014-01-01

    Single crystals of L-alanine of dimensions 2×1.1×0.5 cm3 were grown by evaporation method using deionised water as a solvent. The morphology of the grown crystals had (1 2 0) and (0 1 1) as their prominent faces. UV-vis-near IR spectrum shows the transparency range of L-alanine crystal available for frequency doubling from 250 to 1400 nm. Phase-matched second harmonic generation was observed in L-alanine sample by using 7 ns Q-switched Nd:YAG laser with OPO set up. In the present work, phase matching was achieved by angle and wavelength tuning. The angular and spectral phase-matching bandwidths were determined experimentally for a 1.5 mm thick L-alanine crystal and the results have been compared with their theoretical results. Further the possible reasons for the broadening of SHG spectrum have been discussed.

  20. Second harmonic generation studies in L-alanine single crystals grown from solution

    Energy Technology Data Exchange (ETDEWEB)

    Boomadevi, Shanmugam, E-mail: sboomi@gmail.com [Department of Physics, Periyar Maniammai University, Thanjavur-613 403, Tamil Nadu (India); Pandiyan, Krishnamoorthy [School of Electrical and Electronics Engineering, SASTRA University, Thanjavur-613 401, Tamil Nadu (India)

    2014-01-01

    Single crystals of L-alanine of dimensions 2×1.1×0.5 cm{sup 3} were grown by evaporation method using deionised water as a solvent. The morphology of the grown crystals had (1 2 0) and (0 1 1) as their prominent faces. UV–vis-near IR spectrum shows the transparency range of L-alanine crystal available for frequency doubling from 250 to 1400 nm. Phase-matched second harmonic generation was observed in L-alanine sample by using 7 ns Q-switched Nd:YAG laser with OPO set up. In the present work, phase matching was achieved by angle and wavelength tuning. The angular and spectral phase-matching bandwidths were determined experimentally for a 1.5 mm thick L-alanine crystal and the results have been compared with their theoretical results. Further the possible reasons for the broadening of SHG spectrum have been discussed.

  1. Second harmonic generation of propagating collective excitations in Bose-Einstein condensates

    Institute of Scientific and Technical Information of China (English)

    Huang Guo-Xiang

    2004-01-01

    We consider a possible second harmonic generation (SHG) of propagating collective excitations in a two-component Bose-Einstein condensate (BEC) with repulsive atom-atom interactions. We show that the phase-matching condition for the SHG can be fulfilled if the wave vectors and frequencies of the excitations are chosen adequately from different dispersion branches. We solve the nonlinear amplitude equations for the SHG derived using a method of multiple-scales and provide SHG solutions similar to those obtained for a SHG in nonlinear optical media. A possible experimental realization of the SHG for the propagating collective modes in a cigar-shaped two-component BEC is also discussed.

  2. The Binding of Roxarsone at the Silica/Water Interface Studied with Second Harmonic Generation

    Science.gov (United States)

    Konek, Christopher; Ostrowski, David; Geiger, Franz

    2005-03-01

    Arsenic is a carcinogen that can also cause chronic poisoning when ingested via drinking water in quantities as low as 10 micrograms/L. In the US, organic arsenicals such as Roxarsone are commonly used as feed additives in the poultry industry. The use of poultry litter as fertilizer results in environmental arsenic deposition rates of up to 50 metric tons per year; the subsequent environmental fate of Roxarsone is unknown. We use second harmonic generation (SHG) to study the thermodynamics and kinetics of Roxarsone binding to environmentally relevant mineral oxide/water interfaces. Roxarsone binding to water/SiO2 interfaces is fully reversible, consistent with high Roxarsone mobility. Results from Langmuir isotherm measurements and surface SHG spectra are presented as well.

  3. Second Harmonic Generation Based on Strong Field Enhancement in Metallic Nanostructured Surface

    Directory of Open Access Journals (Sweden)

    Kitsakorn LOCHAROENRAT

    2014-12-01

    Full Text Available Although absorption is still the primary optical property of interest, other spectroscopic techniques including optical second harmonic generation (SHG are also used to understand anisotropic nature of nanomaterials. Benefit of SHG technique as compared with linear optical approach is that SH response is the most sensitive to surface potential changes and SH intensity mainly comes from surface/interface layers. This article reports that optical absorption spectra due to surface plasmon modes of metallic nanowires exhibit strong anisotropic absorption. Maxwell-Garnett simulation cannot fit with experimental results because of wire sizes much larger than wavelength of light, whereas finite-difference time-domain calculation can fit well with experimental findings in terms of position of photon energy of absorption peak with respect to polarization conditions. DOI: http://dx.doi.org/10.5755/j01.ms.20.4.6399

  4. Studies on the second-harmonic generations in cubical quantum dots with applied electric field

    Energy Technology Data Exchange (ETDEWEB)

    Shao Shuai [Department of Physics, College of Physics and Electronic Engineering, Guangzhou University, Guangzhou 510006 (China); Guo Kangxian, E-mail: axguo@sohu.co [Department of Physics, College of Physics and Electronic Engineering, Guangzhou University, Guangzhou 510006 (China); Zhang Zhihai; Li Ning; Peng Chao [Department of Physics, College of Physics and Electronic Engineering, Guangzhou University, Guangzhou 510006 (China)

    2011-02-01

    The second-harmonic generation (SHG) coefficient for cubical quantum dots (CQDs) with the applied electric field is theoretically investigated. Using the compact density-matrix approach and the iterative method, we get the analytical expression of the SHG coefficient. And the numerical calculations for the typical GaAs/AlAs CQDs are presented. The results show that the SHG coefficient can reach the magnitude of 10{sup -5} m/V, about two orders higher than that in spherical quantum dot system. More importantly, the SHG coefficient is not a monotonic function of the length L of CQDs as well as the applied field F. If we select suitable values of F and L, we will get a higher value of the SHG coefficient. In addition, the relaxation rate also affects the SHG coefficient obviously.

  5. Nanotwin Detection and Domain Polarity Determination via Optical Second Harmonic Generation Polarimetry.

    Science.gov (United States)

    Ren, Ming-Liang; Agarwal, Rahul; Nukala, Pavan; Liu, Wenjing; Agarwal, Ritesh

    2016-07-13

    We demonstrate that optical second harmonic generation (SHG) can be utilized to determine the exact nature of nanotwins in noncentrosymmetric crystals, which is challenging to resolve via conventional transmission electron or scanned probe microscopies. Using single-crystalline nanotwinned CdTe nanobelts and nanowires as a model system, we show that SHG polarimetry can distinguish between upright (Cd-Te bonds) and inverted (Cd-Cd or Te-Te bonds) twin boundaries in the system. Inverted twin boundaries are generally not reported in nanowires due to the lack of techniques and complexity associated with the study of the nature of such defects. Precise characterization of the nature of defects in nanocrystals is required for deeper understanding of their growth and physical properties to enable their application in future devices.

  6. Silicon photonic crystal cavity enhanced second-harmonic generation from monolayer WSe2

    Science.gov (United States)

    Fryett, Taylor K.; Seyler, Kyle L.; Zheng, Jiajiu; Liu, Chang-Hua; Xu, Xiaodong; Majumdar, Arka

    2017-03-01

    Nano-resonators integrated with two-dimensional materials (e.g. transition metal dichalcogenides) have recently emerged as a promising nano-optoelectronic platform. Here we demonstrate resonator-enhanced second-harmonic generation (SHG) in tungsten diselenide using a silicon photonic crystal cavity. By pumping the device with ultrafast laser pulses near the cavity mode at the telecommunication wavelength, we observe a near visible SHG with a narrow linewidth and near unity linear polarization, originated from the coupling of the pump photon to the cavity mode. The observed SHG is enhanced by factor of ∼200 compared to a bare monolayer on silicon. Our results imply the efficacy of cavity integrated monolayer materials for nonlinear optics and the potential of building a silicon-compatible second-order nonlinear integrated photonic platform.

  7. Laterally emitted surface second harmonic generation in a single ZnTe nanowire

    CERN Document Server

    Liu, Weiwei; Liu, Zhe; Shen, Guozhen; Lu, Peixiang

    2012-01-01

    We report a direct observation on the unique laterally emitted surface second harmonic generation (SHG) in a single ZnTe nanowire. The highly directional surface SHG signal that polarizes along the direction vertical to the nanowire growth axis, is significantly larger than the bulk SHG contribution, indicating a high efficiency of surface SHG. Two strong SHG peaks are observed on both sides of the nanowire surfaces in the far-field scanning images, which is further supported by FDTD simulations, demonstrating that the unique laterally emitted signal is ascribed to surface SHG in the ZnTe nanowire. The surface SHG in a single ZnTe nanowire with unique lateral emission and high conversion efficiency shows great potential applications in short-wavelength nanolasers, nonlinear microscopy and polarization dependent photonic integrating.

  8. Cavity-enhanced second harmonic generation via nonlinear-overlap optimization

    CERN Document Server

    Lin, Zin; Loncar, Marko; Johnson, Steven G; Rodriguez, Alejandro W

    2015-01-01

    We describe an approach based on topology optimization that enables automatic discovery of wavelength-scale photonic structures for achieving high-efficiency second-harmonic generation (SHG). A key distinction from previous formulation and designs that seek to maximize Purcell factors at individual frequencies is that our method not only aims to achieve frequency matching (across an entire octave) and large radiative lifetimes, but also optimizes the equally important nonlinear--coupling figure of merit $\\bar{\\beta}$, involving a complicated spatial overlap-integral between modes. We apply this method to the particular problem of optimizing micropost and grating-slab cavities (one-dimensional multilayered structures) and demonstrate that a variety of material platforms can support modes with the requisite frequencies, large lifetimes $Q \\gtrsim 10^3$, small modal volumes $\\sim (\\lambda/n)^3$, and extremely large $\\bar{\\beta} \\gtrsim 10^{-2}$, orders of magnitude larger than the state of the art.

  9. Enhancement of second-harmonic generation from silicon stripes under external cylindrical strain.

    Science.gov (United States)

    Zhao, Ji-Hong; Chen, Qi-Dai; Chen, Zhan-Guo; Jia, Gang; Su, Wen; Jiang, Ying; Yan, Zhao-Xu; Dolgova, T V; Aktsipetrov, O A; Sun, Hong-Bo

    2009-11-01

    The enhanced second-harmonic (SH) generation from Si (111) stripes induced by external cylindrical strain is investigated. The dependence of the intensity of the strain-induced SH on the sample azimuth shows that the Si under cylindrical strain has 3m symmetry, which is similar to that of the Si (111) surface. Further studies indicate that the intensity of the enhanced SH is a quadratic function of the cylindrical strain within the magnitude that the Si stripe can bear. For the p-polarized and s-polarized SH, the intensities are, respectively, enhanced by 47.9% and 13% at epsilon(0)=2.93x10(-4). The enhancement of SH is due to the contributions from the strain-induced second-order nonlinear susceptibility chi(strain)(2) to the bulk dipole.

  10. Polarization-resolved second-harmonic generation imaging for liver fibrosis assessment without labeling

    Science.gov (United States)

    Lin, Jian; Pan, Shiying; Zheng, Wei; Huang, Zhiwei

    2013-10-01

    We apply the polarization-resolved second-harmonic generation (PR-SHG) microscopy to investigate the changes of collagen typings (type I vs type III) and collagen fibril orientations of liver tissue in bile-duct-ligation (BDL) rat models. The PR-SHG results show that the second-order susceptibility tensor ratios (χ31/χ15 and χ33/χ15) of collagen fibers increase with liver fibrotic progression after BDL surgery, reflecting an increase of the type III collagen component with the severity of liver fibrosis; and the square root of the collagen type III to type I ratio linearly correlates (R2 = 0.98) with histopathological scores. Furthermore, the collagen fibril orientations become more random with liver fibrosis transformation as compared to normal liver tissue. This work demonstrates that PR-SHG microscopy has the potential for label-free diagnosis and characterization of liver fibrosis based on quantitative analysis of collagen typings and fibril orientations.

  11. Analysis of second-harmonic generation microscopy under refractive index mismatch

    Institute of Scientific and Technical Information of China (English)

    Wang Xiang-Hui; Lin Lie; Zhang Yang

    2007-01-01

    On the basis of the vector diffraction theory and Green's function method, this paper investigates the effects of refractive index mismatch on second-harmonic generation (SHG) microscopy. The polarization distribution and SHG intensity are calculated as functions of the sample radius and probe depth. The numerical results show that refractive index mismatch can result in peak intensity degradation, increase secondary lobes and extension of secondharmonic polarization distribution. Because of the attenuation of polarization intensity, the detected SHG intensity significantly decreases with increasing probe depth, which can limit the imaging depth of SHG microcopy inside thick samples. Forward SHG intensity decays slowly than backward SHG, due to the combination of extension secondharmonic polarization distribution and strong dependency of forward SHG on sample radius.

  12. Random laser action with coherent feedback via second-harmonic generation

    CERN Document Server

    Qiao, Yanqi; Cai, Zengyan; Chen, Xianfeng

    2016-01-01

    The random laser action with coherent feedback by second-harmonic generation (SHG) was experimentally demonstrated in this paper. Compared with the conventional random laser action based on photoluminescence effect, which needs strong photoresponse in the active medium and has a fixed response waveband due to the inherent energy level structure of the material, this random SHG laser action indicates a possible confinement of the nonlinear signal with ring cavities and widens the response waveband due to the flexible frequency conversion in nonlinear process. The combination of coherent random laser and nonlinear optics will provide us another possible way to break phase-matching limitations, with fiber or feedback-based wavefront shaping method to transmit the emission signal directionally. This work suggests potential applications in band-tunable random laser, phase-matching-free nonlinear optics and even brings in new consideration about random nonlinear optics (RNO).

  13. Resonantly enhanced second-harmonic generation using III-V semiconductor all-dielectric metasurfaces

    CERN Document Server

    Liu, Sheng; Keeler, Gordon A; Sinclair, Michael B; Yang, Yuanmu; Reno, John; Pertsch, Thomas; Brener, Igal

    2016-01-01

    Nonlinear optical phenomena in nanostructured materials have been challenging our perceptions of nonlinear optical processes that have been explored since the invention of lasers. For example, the ability to control optical field confinement, enhancement, and scattering almost independently, allows nonlinear frequency conversion efficiencies to be enhanced by many orders of magnitude compared to bulk materials. Also, the subwavelength length scales render phase matching issues irrelevant. Compared with plasmonic nanostructures, dielectric resonator metamaterials show great promise for enhanced nonlinear optical processes due to their larger mode volumes. Here, we present, for the first time, resonantly enhanced second-harmonic generation (SHG) using Gallium Arsenide (GaAs) based dielectric metasurfaces. Using arrays of cylindrical resonators we observe SHG enhancement factors as large as 104 relative to unpatterned GaAs. At the magnetic dipole resonance we measure an absolute nonlinear conversion efficiency o...

  14. Design, tests and results of a second harmonic filter for the ICRH generator of JET

    Energy Technology Data Exchange (ETDEWEB)

    Vervier, M. E-mail: michel.vervier@fusion.rma.ac.be; Durodie, F.; Messiaen, A.; Dumortier, P

    2003-09-01

    A resistive harmonic filter has been developed to damp the harmonic signals generated by the ICRH power amplifier for the JET ICRH system. This filter has to produce negligible reflection at the fundamental frequency (VSWR<1.1 on a matched load) and has to absorb more than 64% of the second harmonic signal with total reflection at any phase. The filter has been first tested at low power in the full operating frequency range (23-57 MHz) showing that its electrical characteristics correspond to the modelling and fulfil the requested specifications. Tests at high power have already been successfully done on TEXTOR at 2 MW level for pulses exceeding 10 s and will start on JET.

  15. Symmetry Analysis of ZnSe(100) Surface in Air By Second Harmonic Generation

    CERN Document Server

    Song, X; Maripuu, R; Siegbahn, Kai; Song, Xiangyang; Neumann, Arnold; Maripuu, Rein; Siegbahn, Kai

    2002-01-01

    Polarized and azimuthal dependencies of optical second harmonics generation (SHG) at the surface of noncentrosymmetric semiconductor crystals have been measured on polished surfaces of ZnSe(100), using a fundamental wavelength of 1.06$\\mu m$. The SHG intensity patterns were analyzed for all four combination of p- and s-polarized incidence and output, considering both the bulk and surface optical nonlinearities in the electric dipole approximation. We found that the measurement using $S_{in}-S_{out}$ is particularly useful in determining the symmetry of the oxdized layer interface, which would lower the effective symmetry of the surface from $C_{4v}$ to $C_{2v}.$ We also have shown that the [011] and [0$\\bar{1}$1] directions can be distinguished through the analysis of p-incident and p-output confugration.

  16. Monitoring process of human keloid formation based on second harmonic generation imaging

    Science.gov (United States)

    Jiang, X. S.; Chen, S.; Chen, J. X.; Zhu, X. Q.; Zheng, L. Q.; Zhuo, S. M.; Wang, D. J.

    2011-09-01

    In this paper, the morphological variation of collagen among the whole dermis from keloid tissue was investigated using second harmonic generation (SHG) microscopy. In the deep dermis of keloids, collagen bundles show apparently regular gap. In the middle dermis, the collagen bundles are randomly oriented and loosely arranged in the pattern of fine mesh while the collagen bundles are organized in a parallel manner in the superficial dermis near the epidermis. The developed parameters COI and BD can be used to further quantitatively describe these changes. Our results demonstrate the potential of SHG microscopy to understand the formation process of human keloid scar at the cellular level through imaging collagen variations in different depth of dermis.

  17. Tunable Room Temperature Second Harmonic Generation in Glasses Doped with CuCI Nanocrystalline Quantum Dots

    Energy Technology Data Exchange (ETDEWEB)

    Thantu, Napoleon; Schley, Robert Scott; B. L. Justus

    2003-05-01

    Two-photon excited emission centered at 379-426 nm in photodarkening borosilicate glass doped with CuCl nanocrystalline quantum dots at room temperature has been observed. The emission is detected in the direction of the fundamental near-infrared beam. Time- and frequency-resolved measurements at room temperature and 77 K indicate that the emission is largely coherent light characteristic of second harmonic generation (SHG). An average conversion efficiency of ~10-10 is obtained for a 2 mm thick sample. The observed SHG can originate in the individual noncentrosymmetric nanocrystals, leading to a bulk-like contribution, and at the nanocrystal-glass interface, leading to a surface contribution. The bulk-like conversion efficiency is estimated using previously reported values of coherence length (5m) and bulk nonlinear susceptibility. This bulk-like conversion efficiency estimate is found to be smaller than the measured value, suggesting a more prominent surface contribution.

  18. Silicon photonic crystal cavity enhanced second-harmonic generation from monolayer WSe2

    CERN Document Server

    Fryett, Taylor K; Zheng, Jiajiu; Liu, Chang-Hua; Xu, Xiaodong; Majumdar, Arka

    2016-01-01

    Nano-resonator integrated with two-dimensional materials (e.g. transition metal dichalcogenides) have recently emerged as a promising nano-optoelectronic platform. Here we demonstrate resonatorenhanced second-harmonic generation (SHG) in tungsten diselenide using a silicon photonic crystal cavity. By pumping the device with the ultrafast laser pulses near the cavity mode at the telecommunication wavelength, we observe a near visible SHG with a narrow linewidth and near unity linear polarization, originated from the coupling of the pump photon to the cavity mode. The observed SHG is enhanced by factor of ~200 compared to a bare monolayer on silicon. Our results imply the efficacy of cavity integrated monolayer materials for nonlinear optics and the potential of building a silicon-compatible second-order nonlinear integrated photonic platform.

  19. Tuning the mapping of second-harmonic generation in silver nanoshells

    Science.gov (United States)

    Li, Z. J.; Gao, S. Y.; Han, D.

    2011-10-01

    The distribution patterns of the second-harmonic generation (SHG) enhancement factor in the incident plane of silver nanoshell at resonance frequencies have been studied by using electrostatic approximation. The mapping feature of SHG corresponding to double frequency local field enhancement is different from that of fundamental case. At longer wavelength (SHG enhancement resulting from local field at double frequency), large SHG enhancements are only observed outside the shell. However, hot spots also take place inside the silver shell at shorter wavelength (SHG enhancement resulting from local field at fundamental frequency). The effect of outer surrounding media on the SHG corresponding to local field at fundamental frequency is also very different from that of double frequency. It has been found that the azimuth angle dependent SHG at shorter wavelength split into two maximums when the surrounding dielectric constant is increased, which is absent for SHG at longer wavelength.

  20. Monitoring the thermally induced structural transitions of collagen by use of second-harmonic generation microscopy

    Science.gov (United States)

    Lin, Sung-Jan; Hsiao, Chih-Yuan; Sun, Yen; Lo, Wen; Lin, Wei-Chou; Jan, Gwo-Jen; Jee, Shiou-Hwa; Dong, Chen-Yuan

    2005-03-01

    The thermal disruption of collagen I in rat tail tendon is investigated with second-harmonic generation (SHG) microscopy. We investigate its effects on SHG images and intensity in the temperature range 25°-60°C. We find that the SHG signal decreases rapidly starting at 45°C. However, SHG imaging reveals that breakage of collagen fibers is not evident until 57°C and worsens with increasing temperature. At 57°C, structures of both molten and fibrous collagen exist, and the disruption of collagen appears to be complete at 60°C. Our results suggest that, in addition to intensity measurement, SHG imaging is necessary for monitoring details of thermally induced changes in collagen structures in biomedical applications.

  1. Analysis of collagen fiber domain organization by Fourier second harmonic generation microscopy

    Science.gov (United States)

    Ghazaryan, Ara; Tsai, Halley F.; Hayrapetyan, Gor; Chen, Wei-Liang; Chen, Yang-Fang; Jeong, Myung Yung; Kim, Chang-Seok; Chen, Shean-Jen; Dong, Chen-Yuan

    2013-03-01

    We present an automated and systematic two-dimensional discrete Fourier transform (2D-FFT) approach to analyze collagen fiber organization through the use of second harmonic generation (SHG) microscopy. Average orientations of individual domains and Ising-like order parameters introduced to characterize the correlation between orientations of adjacent domains may be used to quantitatively characterize fibrous tissues. Our approach was applied to analyze tissues including rat tail tendon, mouse skin, bovine corneas, and human corneas. We also show that collagen fiber organization in normal and keratokonus human corneas may be distinguished. The current approach may be used for the quantitative differentiation of SHG collagen fiber morphology in different tissues and may be applied for diagnostic purposes.

  2. Dynamical centrosymmetry breaking - A novel mechanism for second harmonic generation in graphene

    Science.gov (United States)

    Carvalho, David N.; Marini, Andrea; Biancalana, Fabio

    2017-03-01

    We discover an unusual phenomenon that occurs when a graphene monolayer is illuminated by a short and intense pulse at normal incidence. Due to the pulse-induced oscillations of the Dirac cones, a dynamical breaking of the layer's centrosymmetry takes place, leading to the generation of second harmonic waves. We prove that this result can only be found by using the full Dirac equation and show that the widely used semiconductor Bloch equations fail to reproduce this and some other important physics of graphene. Our results open new windows in the understanding of nonlinear light-matter interactions in a wide variety of new 2D materials with a gapped or ungapped Dirac-like dispersion.

  3. Plasmon assisted enhanced second-harmonic generation in single hybrid Au/ZnS nanowires

    Science.gov (United States)

    Jassim, Nadia M.; Wang, Kai; Han, Xiaobo; Long, Hua; Wang, Bing; Lu, Peixiang

    2017-02-01

    We demonstrate the enhanced second-harmonic generation (SHG) in single ZnS nanowires (NWs) attached with gold nanoparticles (Au NPs). The hybrid Au/ZnS NWs with different densities of the attached Au NPs were prepared by a simple solution impregnation method. By comparing with bare ZnS NWs, ∼1.3, ∼6.6, ∼7 and ∼2 times enhancement of SH intensity was achieved in the hybrid Au/ZnS NWs with low, moderate, high and ultrahigh densities of the attached Au NPs, respectively. The enhanced SHG in the hybrid Au/ZnS NWs is attributed to the strong local-fields from the Au cluster under the near-resonant condition, which is supported by the related dark-field scattering spectra. This hybrid Au/ZnS NWs provide a simple platform for enhancing nonlinear optical responses, which have potential applications in nano-probing and nano-sensing.

  4. Texture analysis applied to second harmonic generation image data for disease classification and development of a multi-view second harmonic generation imaging platform

    Science.gov (United States)

    Wen, Lianggong

    Many diseases, e.g. ovarian cancer, breast cancer and pulmonary fibrosis, are commonly associated with drastic alterations in surrounding connective tissue, and changes in the extracellular matrix (ECM) are associated with the vast majority of cellular processes in disease progression and carcinogenesis: cell differentiation, proliferation, biosynthetic ability, polarity, and motility. We use second harmonic generation (SHG) microscopy for imaging the ECM because it is a non-invasive, non-linear laser scanning technique with high sensitivity and specificity for visualizing fibrillar collagen. In this thesis, we are interested in developing imaging techniques to understand how the ECM, especially the collagen architecture, is remodeled in diseases. To quantitate remodeling, we implement a 3D texture analysis to delineate the collagen fibrillar morphology observed in SHG microscopy images of human normal and high grade malignant ovarian tissues. In the learning stage, a dictionary of "textons"---frequently occurring texture features that are identified by measuring the image response to a filter bank of various shapes, sizes, and orientations---is created. By calculating a representative model based on the texton distribution for each tissue type using a training set of respective mages, we then perform classification between normal and high grade malignant ovarian tissues classification based on the area under receiver operating characteristic curves (true positives versus false positives). The local analysis algorithm is a more general method to probe rapidly changing fibrillar morphologies than global analyses such as FFT. It is also more versatile than other texture approaches as the filter bank can be highly tailored to specific applications (e.g., different disease states) by creating customized libraries based on common image features. Further, we describe the development of a multi-view 3D SHG imaging platform. Unlike fluorescence microscopy, SHG excites

  5. Self-Phase-Matched Second-Harmonic and White-Light Generation in a Biaxial Zinc Tungstate Single Crystal

    Science.gov (United States)

    Osewski, Pawel; Belardini, Alessandro; Petronijevic, Emilija; Centini, Marco; Leahu, Grigore; Diduszko, Ryszard; Pawlak, Dorota A.; Sibilia, Concita

    2017-01-01

    Second-order nonlinear optical materials are used to generate new frequencies by exploiting second-harmonic generation (SHG), a phenomenon where a nonlinear material generates light at double the optical frequency of the input beam. Maximum SHG is achieved when the pump and the generated waves are in phase, for example through birefringence in uniaxial crystals. However, applying these materials usually requires a complicated cutting procedure to yield a crystal with a particular orientation. Here we demonstrate the first example of phase matching under the normal incidence of SHG in a biaxial monoclinic single crystal of zinc tungstate. The crystal was grown by the micro-pulling-down method with the (102) plane perpendicular to the growth direction. Additionally, at the same time white light was generated as a result of stimulated Raman scattering and multiphoton luminescence induced by higher-order effects such as three-photon luminescence enhanced by cascaded third-harmonic generation. The annealed crystal offers SHG intensities approximately four times larger than the as grown one; optimized growth and annealing conditions may lead to much higher SHG intensities. PMID:28338074

  6. Self-Phase-Matched Second-Harmonic and White-Light Generation in a Biaxial Zinc Tungstate Single Crystal

    Science.gov (United States)

    Osewski, Pawel; Belardini, Alessandro; Petronijevic, Emilija; Centini, Marco; Leahu, Grigore; Diduszko, Ryszard; Pawlak, Dorota A.; Sibilia, Concita

    2017-03-01

    Second-order nonlinear optical materials are used to generate new frequencies by exploiting second-harmonic generation (SHG), a phenomenon where a nonlinear material generates light at double the optical frequency of the input beam. Maximum SHG is achieved when the pump and the generated waves are in phase, for example through birefringence in uniaxial crystals. However, applying these materials usually requires a complicated cutting procedure to yield a crystal with a particular orientation. Here we demonstrate the first example of phase matching under the normal incidence of SHG in a biaxial monoclinic single crystal of zinc tungstate. The crystal was grown by the micro-pulling-down method with the (102) plane perpendicular to the growth direction. Additionally, at the same time white light was generated as a result of stimulated Raman scattering and multiphoton luminescence induced by higher-order effects such as three-photon luminescence enhanced by cascaded third-harmonic generation. The annealed crystal offers SHG intensities approximately four times larger than the as grown one; optimized growth and annealing conditions may lead to much higher SHG intensities.

  7. Second harmonic generation at the probe tip for background-free near-field optical imaging.

    Science.gov (United States)

    Dong, Zhaogang; Soh, Yeng Chai

    2012-08-13

    Second harmonic generation (SHG) has been applied to reduce background signals in near-field optical imaging, but this technique is usually limited to samples with strong second-order nonlinear susceptibilities. To overcome this limitation, in this paper, we present a versatile background-free SHG configuration, where it utilizes the second-order nonlinear susceptibility of the probe which essentially functions as a near-field polarizer capable of filtering out the background signal component. In the theoretical analysis, we first model the probe-sample optical interactions at both the fundamental frequency and the second harmonic frequency by using the coupled dipole method. The theoretical model reveals that the proposed versatile background-free SHG configuration requires two conditions. The first condition is that the incident optical field must be s-polarized. The second condition is that the probe must be made of crystals from symmetry class 222, symmetry class 622, symmetry class 422, symmetry class 42m, symmetry class 43m or symmetry class 23. To demonstrate the effectiveness of the proposed versatile background-free SHG configuration, a probe made of deuterated potassium dideuterium phosphate (DKDP) crystal from symmetry class 42m is analyzed numerically. It is shown that when imaging samples with negligible second-order nonlinear susceptibilities, the proposed background-free SHG configuration improves the imaging contrast by more than one-order of magnitude as compared to all other imaging configurations. Moreover, we also investigate the dependence of its performance on other parameters, such as the probe-sample distance, the relative size between probe and sample, and the tilt angle of probe crystal. It is believed that the proposed configuration could be widely used to achieve high contrast near-field optical imaging.

  8. Electric-Field Switchable Second-Harmonic Generation in Bilayer MoS2 by Inversion Symmetry Breaking.

    Science.gov (United States)

    Klein, J; Wierzbowski, J; Steinhoff, A; Florian, M; Rösner, M; Heimbach, F; Müller, K; Jahnke, F; Wehling, T O; Finley, J J; Kaniber, M

    2017-01-11

    We demonstrate pronounced electric-field-induced second-harmonic generation in naturally inversion symmetric 2H stacked bilayer MoS2 embedded into microcapacitor devices. By applying strong external electric field perturbations (|F| = ±2.6 MV cm(-1)) perpendicular to the basal plane of the crystal, we control the inversion symmetry breaking and, hereby, tune the nonlinear conversion efficiency. Strong tunability of the nonlinear response is observed throughout the energy range (Eω ∼ 1.25-1.47 eV) probed by measuring the second-harmonic response at E2ω, spectrally detuned from both the A- and B-exciton resonances. A 60-fold enhancement of the second-order nonlinear signal is obtained for emission at E2ω = 2.49 eV, energetically detuned by ΔE = E2ω - EC = -0.26 eV from the C-resonance (EC = 2.75 eV). The pronounced spectral dependence of the electric-field-induced second-harmonic generation signal reflects the bandstructure and wave function admixture and exhibits particularly strong tunability below the C-resonance, in good agreement with density functional theory calculations. Moreover, we show that the field-induced second-harmonic generation relies on the interlayer coupling in the bilayer. Our findings strongly suggest that the strong tunability of the electric-field-induced second-harmonic generation signal in bilayer transition metal dichalcogenides may find applications in miniaturized electrically switchable nonlinear devices.

  9. Interference Effects in the Optical Second Harmonic Generation from Ultrathin Alkali Films

    DEFF Research Database (Denmark)

    Balzer, Frank; Rubahn, Horst-Günter

    2000-01-01

    second harmonic dependencies can be interpreted in terms of interference between frontside and rearside adsorbed islands or by taking into account the morphology of the adsorbed alkali islands. By the use of different polarization combinations of both pump and reflected second harmonic wave we obtain......Interference effects are shown to strongly modulate the transmission second harmonic signal (fundamental wavelength 1067 nm) from rough alkali island films grown on insulating substrates if one varies the angle of incidence. Depending on growth conditions and substrate thickness, the measured...

  10. Interaction between O{sub 2} and ZnO films probed by time-dependent second-harmonic generation

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, S. V., E-mail: sva@nano.aau.dk [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Department of Physics and Nanotechnology, Aalborg University, Skjernvej 4A, DK-9220 Aalborg Øst (Denmark); Vandalon, V.; Bosch, R. H. E. C.; Loo, B. W. H. van de; Kessels, W. M. M., E-mail: w.m.m.kessels@tue.nl [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Pedersen, K. [Department of Physics and Nanotechnology, Aalborg University, Skjernvej 4A, DK-9220 Aalborg Øst (Denmark)

    2014-02-03

    The interaction between O{sub 2} and ZnO thin films prepared by atomic layer deposition has been investigated by time-dependent second-harmonic generation, by probing the electric field induced by adsorbed oxygen molecules on the surface. The second-harmonic generated signal decays upon laser exposure due to two-photon assisted desorption of O{sub 2}. Blocking and unblocking the laser beam for different time intervals reveals the adsorption rate of O{sub 2} onto ZnO. The results demonstrate that electric field induced second-harmonic generation provides a versatile non-contact probe of the adsorption kinetics of molecules on ZnO thin films.

  11. Quasi-phase-matched second harmonic generation in silicon nitride ring resonators controlled by static electric field.

    Science.gov (United States)

    de Oliveira, Rafael E P; de Matos, Christiano J S

    2013-12-30

    Actively-controlled second harmonic generation in a silicon nitride ring resonator is proposed and simulated. The ring was designed to resonate at both pump and second harmonic wavelengths and quasi-phase-matched frequency conversion is induced by a periodic static electric field generated by voltage applied to electrodes arranged along the ring. Nonlinear propagation simulations were undertaken and an efficiency of -21.67 dB was calculated for 60 mW of pump power at 1550 nm and for a 30V applied voltage, which compares favorably with demonstrated all-optical second harmonic generation in integrated microresonators. Transient effects were also evaluated. The proposed design can be exploited for the construction of electro-optical devices based on nonlinear effects in CMOS compatible circuits.

  12. Second-harmonic generation from C{sub 60} thin films at 1.064 {mu}m

    Energy Technology Data Exchange (ETDEWEB)

    Wilk, D.; Johannsmann, D.; Stanners, C.; Shen, Y.R. [Department of Physics, University of California at Berkeley, Berkeley, California 94720 (United States)

    1995-04-15

    We have performed {ital in} {ital situ} optical second-harmonic-generation measurements using 1.064-{mu}m wavelength laser pulses on C{sub 60} during film growth. We present a complete theoretical description of second-harmonic generation from a thin-film system in terms of surface and bulk contributions as well as local and nonlocal contributions to the optical nonlinearities. The experimental results can be well described in terms of only nonlocal contributions to both surface and bulk nonlinear susceptibilities. We suggest that in our case the second-harmonic-generation process is resonantly enhanced by the {ital h}{sub {ital u}-}{ital t}{sub 1{ital u}} and {ital h}{sub {ital u}-}{ital t}{sub 1{ital g}} transitions in C{sub 60} and that electric-dipole and electric-quadrupole radiations in the output field are comparable in strength.

  13. Surface Integral Method for the Second Harmonic Generation in Metal Nanoparticles

    CERN Document Server

    Forestiere, Carlo; Miano, Giovanni

    2013-01-01

    Second harmonic (SH) radiation in metal nanoparticles is generated by both nonlocal-bulk and local-surface SH sources, induced by the electromagnetic field at the fundamental frequency. We propose a surface integral equation (SIE) method for evaluating the SH radiation generated by metal nanoparticles with arbitrary shapes, considering both the local-surface and nonlocal-bulk SH sources. We demonstrate that the contribution of the nonlocal-bulk SH source to the SH electromagnetic field can be rigorously taken into account through an equivalent surface magnetic current. We numerically solve the SIE problem by using the Galerkin method and the Rao-Wilton-Glisson basis functions in the framework of the distribution theory. The accuracy of the proposed method is verified by comparison with the SH-Mie formulation in the case of SH generation from a spherical nanoparticle. As an example of a complex-shaped particle, we investigate the SH radiation generated from a triangular nano-prism. The method paves the way for...

  14. Synchronous pumping of picosecond dye laser using high efficiency second harmonic generation from optical fibres

    Science.gov (United States)

    Lawandy, N. M.; Bernardin, J. P.; Macdonald, R. L.; Demouchy, G.

    1991-01-01

    The stable operation of a mode-locked dye laser synchronously pumped by the second harmonic of an Nd:YAG laser produced in an Nd codoped germanosilicate optical fiber is reported. The optical fiber preparation technique, which results in a second harmonic conversion efficiency of 2 percent, is described. This optical fiber SHG conversion efficiency is the highest reported to date using a continuous-wave mode-locked laser.

  15. Origin of optical second-harmonic generation in spherical gold nanoparticles: Local surface and nonlocal bulk contributions

    CERN Document Server

    Bachelier, Guillaume; Russier-Antoine, Isabelle; Jonin, Christian; Benichou, Emmanuel; Brevet, Pierre-François; 10.1103/PhysRevB.82.235403

    2011-01-01

    The second-harmonic generation of 150 nm spherical gold nanoparticles is investigated both experimentally and theoretically. We demonstrate that the interference effects between dipolar and octupolar plasmons can be used as a fingerprint to discriminate the local surface and non-local bulk contributions to the second-harmonic generation. By fitting the experimental data with the electric fields computed with finite-element method (FEM) simulations, the Rudnick and Stern parameters weighting the relative nonlinear sources efficiencies are evaluated and the validity of the hydrodynamic model and the local density approximation approaches are discussed.

  16. Efficient generation of highly squeezed light and second harmonic wave with periodically poled MgO:LiNbO_3

    CERN Document Server

    Masada, Genta; Satoh, Yasuhiro; Ishizuki, Hideki; Taira, Takunori; Furusawa, Akira

    2009-01-01

    We report on effective generation of continuous-wave squeezed light and second harmonics with a periodically poled MgO:LiNbO$_{\\mathrm{3}}$ (PPMgLN) crystal which enables us to utilize the large nonlinear optical coefficient $d_{\\mathrm{33}}$. We achieved the squeezing level of $-7.60 \\pm 0.15$dB at 860 nm by utilizing a subthreshol optical parametric oscillator with a PPMgLN crystal. We also generated 400 mW of second harmonics at 430 nm from 570 mW of fundamental waves with 70% of conversion efficiency by using a PPMgLN crystal inside an external cavity.

  17. Time-Domain Second-Harmonic Generation of Primary Lamb-Wave Propagation in an Elastic Plate

    Institute of Scientific and Technical Information of China (English)

    DENG Ming-Xi; XIANG Yan-Xun; LIU Liang-Bing

    2011-01-01

    We present an experimental observation of the generation of the time-domain second harmonic by propagation of the primary Lamb-wave tone-burst.For a case where the phase velocity matching between the primary and the double frequency Lamb waves is satisfied but the group velocity matching between them is not,our observation clearly shows that the duration of the time-domain second-harmonic tone-burst,as well as its integrated amplitude,increases with the increasing propagation distance.This experimental result is consistent with the theoretical prediction and demonstrates that group velocity matching is not absolutely necessary for the generation of the cumulative time-domain second harmonic by primary Lamb-wave propagation.

  18. Generation of cumulative second-harmonic ultrasonic guided waves with group velocity mismatching: Numerical analysis and experimental validation

    Science.gov (United States)

    Xiang, Yanxun; Zhu, Wujun; Deng, Mingxi; Xuan, Fu-Zhen; Liu, Chang-Jun

    2016-11-01

    The generation of second-harmonic Lamb waves in a homogeneous, isotropic, stress-free elastic plate is analytically and experimentally investigated. The numerical analyses show that whether the matching condition of the group velocity is satisfied or not, the integrated amplitude of a second-harmonic Lamb wave accumulates with the propagation distance when both the finite duration of the primary Lamb wave tone burst and the phase velocity matching are given. The theoretical analyses are validated by experimental measurements of an aluminium plate. Our conclusions are different from those of the previous works that reported that the group velocity matching is required for the generation of the cumulative second-harmonic Lamb waves with the finite duration of tone bursts.

  19. Pulsed second-harmonic generation in nonlinear, one-dimensional, periodic structures

    Science.gov (United States)

    Scalora, M.; Bloemer, M. J.; Manka, A. S.; Dowling, J. P.; Bowden, C. M.; Viswanathan, R.; Haus, J. W.

    1997-10-01

    We present a numerical study of second-harmonic (SH) generation in a one-dimensional, generic, photonic band-gap material that is doped with a nonlinear χ(2) medium. We show that a 20-period, 12-μm structure can generate short SH pulses (similar in duration to pump pulses) whose energy and power levels may be 2-3 orders of magnitude larger than the energy and power levels produced by an equivalent length of a phase-matched, bulk medium. This phenomenon comes about as a result of the combination of high electromagnetic mode density of states, low group velocity, and spatial phase locking of the fields near the photonic band edge. The structure is designed so that the pump pulse is tuned near the first-order photonic band edge, and the SH signal is generated near the band edge of the second-order gap. This maximizes the density of available field modes for both the pump and SH field. Our results show that the χ(2) response is effectively enhanced by several orders of magnitude. Therefore, mm- or cm-long, quasi-phase-matched devices could be replaced by these simple layered structures of only a few micrometers in length. This has important applications to high-energy lasers, Raman-type sources, and frequency up- and down-conversion schemes.

  20. Increasing efficiency of two-photon excited fluorescence and second harmonic generation using ultrashort pulses

    Science.gov (United States)

    Tang, Shuo; Krasieva, Tatiana B.; Chen, Zhongping; Tempea, Gabriel; Tromberg, Bruce J.

    2006-02-01

    Multiphoton microscopy (MPM) has become an important tool for high-resolution and non-invasive imaging in biological tissues. However, the efficiencies of two-photon excited fluorescence (TPEF) and second harmonic generation (SHG) are relatively low because of their nonlinear nature. Therefore, it is critical to optimize laser parameters for most efficient excitation of MPM. Reducing the pulse duration can increase the peak intensity of excitation and thus potentially increase the excitation efficiency. In this paper, a multiphoton microscopy system using a 12 fs Ti:Sapphire laser is reported. With adjustable dispersion pre-compensation, the pulse duration at the sample location can be varied from 400 fs to sub-20 fs. The efficiencies of TPEF and SHG are studied for the various pulse durations, respectively. Both TPEF and SHG are found to increase proportionally to the inverse of the pulse duration for the entire tested range. To transmit most of the SHG and TPEF signals, the spectral transmission widow of the detection optics needs to be carefully considered. Limitation from phase-matching in SHG generation is not significant because the effective interaction length for SHG is less than 10 μm at the focal depth of the objectives. These results are important in improving MPM excitation efficiency using ultrashort pulses. MPM images from human artery wall are also demonstrated.

  1. Structural dynamics of the skeletal muscle fiber by second harmonic generation

    Science.gov (United States)

    Nucciotti, V.; Stringari, C.; Sacconi, L.; Vanzi, F.; Linari, M.; Piazzesi, G.; Lombardi, V.; Pavone, F. S.

    2008-02-01

    The high degree of structural order in skeletal muscle allows imaging of this tissue by Second Harmonic Generation (SHG). As previously found (Vanzi et al., J. Muscle Cell Res. Motil. 2006) by fractional extraction of proteins, myosin is the source of SHG signal. A full characterization of the polarization-dependence of the SHG signal can provide very selective information on the orientation of the emitting proteins and their dynamics during contraction. We developed a line scan polarization method, allowing measurements of a full polarization curve in intact muscle fibers from skeletal muscle of the frog to characterize the SHG polarization dependence on different physiological states (resting, rigor and isometric tetanic contraction). The polarization data have been interpreted by means of a model in terms of the average orientation of SHG emitters.The different physiological states are characterized by distinct patterns of SHG polarization. The variation of the orientation of emitting molecules in relation to the physiological state of the muscle demonstrates that one part of SHG signal arises from the globular head of the myosin molecule that cross-links actin and myosin filaments. The dependence of the SHG modulation on the degree of overlap between actin and myosin filaments during an isometric contraction, provides the constraints to estimate the fraction of myosin heads generating the isometric force in the active muscle fiber.

  2. Structural and molecular conformation of myosin in intact muscle fibers by second harmonic generation

    Science.gov (United States)

    Nucciotti, V.; Stringari, C.; Sacconi, L.; Vanzi, F.; Linari, M.; Piazzesi, G.; Lombardi, V.; Pavone, F. S.

    2009-02-01

    Recently, the use of Second Harmonic Generation (SHG) for imaging biological samples has been explored with regard to intrinsic SHG in highly ordered biological samples. As shown by fractional extraction of proteins, myosin is the source of SHG signal in skeletal muscle. SHG is highly dependent on symmetries and provides selective information on the structural order and orientation of the emitting proteins and the dynamics of myosin molecules responsible for the mechano-chemical transduction during contraction. We characterise the polarization-dependence of SHG intensity in three different physiological states: resting, rigor and isometric tetanic contraction in a sarcomere length range between 2.0 μm and 4.0 μm. The orientation of motor domains of the myosin molecules is dependent on their physiological states and modulate the SHG signal. We can discriminate the orientation of the emitting dipoles in four different molecular conformations of myosin heads in intact fibers during isometric contraction, in resting and rigor. We estimate the contribution of the myosin motor domain to the total second order bulk susceptibility from its molecular structure and its functional conformation. We demonstrate that SHG is sensitive to the fraction of ordered myosin heads by disrupting the order of myosin heads in rigor with an ATP analog. We estimate the fraction of myosin motors generating the isometric force in the active muscle fiber from the dependence of the SHG modulation on the degree of overlap between actin and myosin filaments during an isometric contraction.

  3. Combined optical second harmonic generation/quartz crystal microbalance study of underpotential deposition processes: copper electrodeposition on polycrystalline gold.

    Science.gov (United States)

    Lakkaraju, S; Bennahmias, M J; Borges, G L; Gordon Ii, J G; Lazaga, M; Stone, B M; Ashley, K

    1990-11-20

    Optical second harmonic generation and quartz crystal microbalance techniques are used as in situ probes of copper underpotential deposition on polycrystalline gold surfaces in sulfuric acid electrolyte. The second harmonic signal from a polished bulk gold substrate is observed to decrease by >60% as a result of copper underpotential deposition on gold. Also, the mass of an underpotentially deposited copper adlayer is monitored in situ by an oscillating quartz crystal microbalance, yielding an estimated coverage of ~8.0 x 10(-10) mol cm(-2) and an electrosorption valency of 1.5 for a copper adlayer on the surface of vapor-deposited polycrystalline gold.

  4. Spectral properties of second-harmonic generation at 800 nm in a BiB(3)O(6) crystal.

    Science.gov (United States)

    Harimoto, Tetsuo; Takeuchi, Yasuki; Fujita, Masayuki

    2004-03-08

    We have investigated spectral distribution and walk-off effect of second-harmonic generation in a 3-mm-long type I BiB(3)O(6) crystal. Linearly turning ability of the BiB(3)O(6) crystal is confirmed for wavelengths around 800 nm. In addition, the walk-off effect of fundamental beams is quantitatively measured by introducing a little vertical polarization component into pumping fundamental pulses. A conversion efficiency of 28% from fundamental to second harmonic is achieved at a 3.2-GW/cm(2) fundamental intensity.

  5. Enhanced optical second harmonic generation in hybrid polymer nanoassemblies based on coupled surface plasmon resonance of a gold nanoparticle array

    Science.gov (United States)

    Ishifuji, Miki; Mitsuishi, Masaya; Miyashita, Tokuji

    2006-07-01

    Effective utilization of coupled surface plasmon resonance from gold nanoparticles was demonstrated experimentally for optoelectronic applications based on second-order nonlinear optics. Hybrid polymer nanoassemblies were constructed by manipulating gold nanoparticle arrays with nonlinear optical active polymer nanosheets to investigate the second harmonic generation. The gold nanoparticle arrays were assembled on heterodeposited polymer nanosheets. The second harmonic light intensity was enhanced by a factor of 8. The observed enhancement was attributed to coupling of surface plasmons between two adjacent gold nanoparticles, thereby enhancing the surface electromagnetic field around the nanoparticles at the fundamental light wavelength (1064nm).

  6. Quantification of collagen distributions in rat hyaline and fibro cartilages based on second harmonic generation imaging

    Science.gov (United States)

    Zhu, Xiaoqin; Liao, Chenxi; Wang, Zhenyu; Zhuo, Shuangmu; Liu, Wenge; Chen, Jianxin

    2016-10-01

    Hyaline cartilage is a semitransparent tissue composed of proteoglycan and thicker type II collagen fibers, while fibro cartilage large bundles of type I collagen besides other territorial matrix and chondrocytes. It is reported that the meniscus (fibro cartilage) has a greater capacity to regenerate and close a wound compared to articular cartilage (hyaline cartilage). And fibro cartilage often replaces the type II collagen-rich hyaline following trauma, leading to scar tissue that is composed of rigid type I collagen. The visualization and quantification of the collagen fibrillar meshwork is important for understanding the role of fibril reorganization during the healing process and how different types of cartilage contribute to wound closure. In this study, second harmonic generation (SHG) microscope was applied to image the articular and meniscus cartilage, and textural analysis were developed to quantify the collagen distribution. High-resolution images were achieved based on the SHG signal from collagen within fresh specimens, and detailed observations of tissue morphology and microstructural distribution were obtained without shrinkage or distortion. Textural analysis of SHG images was performed to confirm that collagen in fibrocartilage showed significantly coarser compared to collagen in hyaline cartilage (p < 0.01). Our results show that each type of cartilage has different structural features, which may significantly contribute to pathology when damaged. Our findings demonstrate that SHG microscopy holds potential as a clinically relevant diagnostic tool for imaging degenerative tissues or assessing wound repair following cartilage injury.

  7. Phase and Texture Characterizations of Scar Collagen Second-Harmonic Generation Images Varied with Scar Duration.

    Science.gov (United States)

    Chen, Guannan; Liu, Yao; Zhu, Xiaoqin; Huang, Zufang; Cai, Jianyong; Chen, Rong; Xiong, Shuyuan; Zeng, Haishan

    2015-08-01

    This work developed a phase congruency algorithm combined with texture analysis to quantitatively characterize collagen morphology in second-harmonic generation (SHG) images from human scars. The extracted phase and texture parameters of the SHG images quantified collagen directionality, homogeneity, and coarseness in scars and varied with scar duration. Phase parameters showed an increasing tendency of the mean of phase congruency with scar duration, indicating that collagen fibers are better oriented over time. Texture parameters calculated from local difference local binary pattern (LD-LBP) and Haar wavelet transform, demonstrated that the LD-LBP variance decreased and the energy of all subimages increased with scar duration. It implied that collagen has a more regular pattern and becomes coarser with scar duration. In addition, the random forest regression was used to predict scar duration, demonstrating reliable performance of the extracted phase and texture parameters in characterizing collagen morphology in scar SHG images. Results indicate that the extracted parameters using the proposed method can be used as quantitative indicators to monitor scar progression with time and can help understand the mechanism of scar progression.

  8. Second harmonic generation imaging as a potential tool for staging pregnancy and predicting preterm birth

    Science.gov (United States)

    Akins, Meredith L.; Luby-Phelps, Katherine; Mahendroo, Mala

    2010-03-01

    We use second harmonic generation (SHG) microscopy to assess changes in collagen structure of murine cervix during cervical remodeling of normal pregnancy and in a preterm birth model. Visual inspection of SHG images revealed substantial changes in collagen morphology throughout normal gestation. SHG images collected in both the forward and backward directions were analyzed quantitatively for changes in overall mean intensity, forward to backward intensity ratio, collagen fiber size, and porosity. Changes in mean SHG intensity and intensity ratio take place in early pregnancy, suggesting that submicroscopic changes in collagen fibril size and arrangement occur before macroscopic changes become evident. Fiber size progressively increased from early to late pregnancy, while pores between collagen fibers became larger and farther apart. Analysis of collagen features in premature cervical remodeling show that changes in collagen structure are dissimilar from normal remodeling. The ability to quantify multiple morphological features of collagen that characterize normal cervical remodeling and distinguish abnormal remodeling in preterm birth models supports future studies aimed at development of SHG endoscopic devices for clinical assessment of collagen changes during pregnancy in women and for predicting risk of preterm labor which occurs in 12.5% of all pregnancies.

  9. Crystal growth and second harmonic generation efficiency of a chalcone derivative

    Energy Technology Data Exchange (ETDEWEB)

    Meenatchi, V.; Muthu, K.; Rajasekar, M.; Meenakshisundaram, SP., E-mail: aumats2009@gmail.com

    2013-06-15

    Single crystals of (2E,6E)-2-(4-fluorobenzylidine)-6-(4-methoxybenzylidine)cyclohexanone (FBMBC) have been grown by a slow evaporation solution growth technique from ethanol at room temperature. The single crystal X-ray diffraction study reveals that the FBMBC belongs to triclinic system and the cell parameters are a=9.790(6) Å, b=12.08(7) Å, c=14.09(9) Å and V=1577 Å{sup 3}. The structure and the crystallinity of the material were further confirmed by powder X-ray diffraction analysis. The various functional groups present in the molecule are confirmed by Fourier transform infrared spectral analysis. The scanning electron microscopy study reveals the surface morphology of the as-grown crystal. Thermogravimetric/differential thermal analysis studies reveal the purity of the material and the crystals are transparent in the visible region having a low optical cut-off at ∼475 nm. The second harmonic generation efficiency of FBMBC is estimated by the Kurtz and Perry technique. Theoretical calculations were performed using the Hartree–Fock method with 6-31 G(d,p) as the basis set to derive the optimized geometry and the first-order molecular hyperpolarizability (β) values.

  10. Second harmonic generation microscopy is a novel technique for differential diagnosis of breast fibroepithelial lesions.

    Science.gov (United States)

    Tan, Wai Jin; Yan, Jie; Xu, Shuoyu; Thike, Aye Aye; Bay, Boon Huat; Yu, Hanry; Tan, Min-Han; Tan, Puay Hoon

    2015-12-01

    Breast fibroepithelial lesions, including fibroadenomas and phyllodes tumours, are commonly encountered in clinical practice. As histological differences between these two related entities may be subtle, resulting in a challenging differential diagnosis, pathological techniques to assist the differential diagnosis of these two entities are of high interest. An accurate diagnosis at biopsy is important given corresponding implications for clinical decision-making including surgical extent and monitoring. Second harmonic generation (SHG) microscopy is a recently developed optical imaging technique capable of robust, powerful and unbiased label-free direct detection of collagen fibril structure in tissue without the use of antibodies. We constructed tissue microarrays emulating limited materials on biopsy to investigate quantitative collagen signal in fibroepithelial lesions using SHG microscopy. Archived formalin-fixed paraffin-embedded materials of 47 fibroepithelial lesions (14 fibroadenomas and 33 phyllodes tumours) were evaluated. Higher collagen signal on SHG microscopy was observed in fibroadenomas than phyllodes tumours on SHG imaging (pmicroscopy for fibroadenoma classification was 71.4% and 84.4%, respectively. To corroborate these findings, we performed immunohistochemistry on tissue array sections using collagen I and III primary antibodies. Both collagen I and III immunohistochemical expressions were also significantly higher in fibroadenomas than in phyllodes tumours (pmicroscopy is a novel imaging approach that can aid the differential diagnosis of fibroepithelial lesions.

  11. Second-Harmonic Generation scanning microscopy of strain fields around Through-Silicon-Vias

    Science.gov (United States)

    Cho, Yujin; Shafiei, Farbod; Mendoza, Bernardo; Jiang, Tengfei; Ho, Paul; Downer, Michael

    Through-Silicon-Vias (TSVs) improve electrical performance of integrated circuits and reduce power consumption by interconnecting vertically stacked silicon layers. Cu has been commonly used for TSVs because of its good electrical and mechanical properties. However, mismatch in thermal expansion coefficient of Si and Cu induces strain fields on the surfaces, which can degrade the performance of nearby devices and crack the surfaces. In this work, using non-invasive Second Harmonic Generation (SHG) microscopy, we successfully characterized inhomogeneous distribution of the thermally induced strain fields. High strain gradients strengthen SHG intensity, since it breaks centrosymmetry in Si. In p-polarized incoming beam and s-polarized SHG configuration, we were able to see the strain effect directly, while in p-in/ p-out polarization, strain-induced SHG was coupled with background SHG from Si. We will present SHG micrographs compared with Raman measurement and the theory of strain-induced SHG, as well as wavelength and power dependence of SHG

  12. Field enhancement at silicon surfaces by gold ellipsoids probed by optical second-harmonic generation spectroscopy

    Science.gov (United States)

    Ulriksen, Hans Ulrik; Pedersen, Kjeld

    2016-12-01

    Optical second-harmonic generation (SHG) spectroscopy has been used to determine the field enhancements from Au nanoparticles on a silicon substrate. Au particles with diameters from 30 to 250 nm have been deposited on a Si substrate passivated by a 1 nm thick surface oxide. The linear optical spectra are dominated by a horizontal plasmon resonance near 1.0 eV, and the experimental spectra are modelled by the island film model in order to extract the linear properties of the metal particles. SHG spectroscopy from this system shows resonances from the metal particles and from the silicon/oxide substrate. By following the evolution of these Si resonances with the size of the Au particles, the field enhancement in the Si surface has been modelled. The effect of the Au particles on SHG at the Si E1 resonance is a combination of charge transfer through the thin oxide that changes the space charge region and an enhancement of the optical field in a thin surface layer of the Si substrate.

  13. Electric-field-induced optical second-harmonic generation in doped graphene

    Science.gov (United States)

    Margulis, Vl. A.; Muryumin, E. E.; Gaiduk, E. A.

    2016-11-01

    A graphene layer interacting with an incident electromagnetic wave of frequency ω will produce dipole radiation at frequency 2 ω in the presence of an in-plane electric field breaking the spatial inversion symmetry of the graphene. Here, we develop a theory that describes such electric-field-induced second-harmonic generation (EFISHG) from doped graphene. We derive an analytic expression for the relevant third-order nonlinear optical (NLO) susceptibility χ (3)(- 2 ω ; ω , ω , 0) and numerically evaluate the absolute magnitude of the χ (3) for various values of the system's parameters. We find that the |χ (3) | spectrum is dominated by the resonant peak structure located at the incident photon energy ℏω equal to the Fermi energy EF of charge carriers in the doped graphene. We also show that the possibility to tune the doping level of graphene by an external gate voltage allows one to maximize the radiated EFISHG power at ℏω =EF , which may be of practical interest for the designs of the NLO devices based on employing a SHG-signal.

  14. Probing the electric field in organic double layer-system by optical second harmonic generation

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Eunju; Shibata, Yoshinori; Manaka, Takaaki [Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552 (Japan); Iwamoto, Mitsumasa, E-mail: iwamoto@ome.pe.titech.ac.j [Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552 (Japan)

    2009-11-30

    Optical electric field induced second harmonic generation (EFISHG) measurements were employed to probe the electric field in the active layer of organic field effect transistors (OFETs) and organic light emitting diodes (OLEDs). The OFETs used were double-layered with an active layer of pentacene/poly (3-hexyl thiophene) P3HT on SiO{sub 2} gate insulator with Au source and drain electrodes. It was shown that SHG from the P3HT bottom layer could be selectively probed at a wavelength of 450 nm. Similarly, by using OLEDs comprised of a double layer of Tris(8-hydroxyquinolinato) aluminium (Alq{sub 3}) and N'-di(1-naphthyl)-N,N'-diphenylbenzidine ({alpha}-NPD) with a device structure of indium-zinc oxide (IZO)/{alpha}-NPD/Alq{sub 3}/Al, it was shown that EFISHG from the Alq{sub 3} layer could be selectively probed at a wavelength of 1000 nm by reflective laser beam irradiation from IZO-side. The results show that the spectroscopic nature of materials allows us to selectively probe the electric field distribution in each layer of multi-layer in organic devices.

  15. Functional imaging of skeletal muscle fiber in different physiological states by second harmonic generation

    Science.gov (United States)

    Nucciotti, V.; Stringari, C.; Sacconi, L.; Vanzi, F.; Tesi, C.; Piroddi, N.; Poggesi, C.; Castiglioni, C.; Milani, A.; Linari, M.; Piazzesi, G.; Lombardi, V.; Pavone, F. S.

    2007-07-01

    The intrinsically ordered arrays of proteins in skeletal muscle allows imaging of this tissue by Second Harmonic Generation (SHG). Biochemical and colocalization studies have gathered an increasing wealth of clues for the attribution of the molecular origin of the muscle SHG signal to the motor protein myosin. Thus, SHG represents a potentially very powerful tool in the investigation of structural dynamics occurring in muscle during active production of force. A full characterization of the polarization-dependence of the SHG signal represents a very selective information on the orientation of the emitting proteins and their dynamics during contraction, provided that different physiological states of muscle (relaxed, rigor and active) exhibit distinct patterns of SHG polarization dependence. Here polarization data are obtained from single frog muscle fibers at rest and during isometric contraction and interpreted, by means of a model, in terms of an average orientation of the SHG emitters which are structured with a cylindrical symmetry about the fiber axis. Optimizing the setup for accurate polarization measurements with SHG, we developed a line scan imaging method allowing measurement of SHG polarization curves in different physiological states. We demonstrate that muscle fiber displays a measurable variation of the orientation of SHG emitters with the transition from rest to isometric contraction.

  16. Study of skeletal muscle cross-bridge population dynamics by second harmonic generation

    Science.gov (United States)

    Nucciotti, V.; Stringari, C.; Sacconi, L.; Vanzi, F.; Tesi, C.; Pirrodi, N.; Poggesi, C.; Castiglioni, C.; Milani, A.; Linari, M.; Piazzesi, G.; Lombardi, V.; Pavone, F. S.

    2007-02-01

    The high degree of structural order in skeletal muscle allows imaging of this tissue by Second Harmonic Generation (SHG). Biochemical and colocalization studies have gathered an increasing wealth of clues for the attribution of the molecular origin of the muscle SHG signal to the motor protein myosin. Thus, SHG represents a potentially very powerful tool in the investigation of structural dynamics occurring in muscle during active production of force and/or shortening. A full characterization of the polarization-dependence of the SHG signal represents a very selective information on the orientation of the emitting proteins and their dynamics during contraction, provided that different physiological states of muscle (relaxed, rigor and active) exhibit distinct patterns of SHG polarization dependence. Here polarization data are obtained from single frog muscle fibers at rest and during isometric contraction and interpreted, by means of a model, in terms of an average orientation of the SHG emitters which are structured with a cylindrical symmetry about the fiber axis. The setup is optimized for accurate polarization measurements with SHG, combined with a line scan imaging method allowing acquisition of SHG polarization curves in different physiological states. We demonstrate that muscle fiber displays a measurable variation of the orientation of SHG emitters with the transition from rest to isometric contraction.

  17. Fully integrated reflection-mode photoacoustic, two-photon, and second harmonic generation microscopy in vivo

    Science.gov (United States)

    Song, Wei; Xu, Qiang; Zhang, Yang; Zhan, Yang; Zheng, Wei; Song, Liang

    2016-08-01

    The ability to obtain comprehensive structural and functional information from intact biological tissue in vivo is highly desirable for many important biomedical applications, including cancer and brain studies. Here, we developed a fully integrated multimodal microscopy that can provide photoacoustic (optical absorption), two-photon (fluorescence), and second harmonic generation (SHG) information from tissue in vivo, with intrinsically co-registered images. Moreover, using a delicately designed optical-acoustic coupling configuration, a high-frequency miniature ultrasonic transducer was integrated into a water-immersion optical objective, thus allowing all three imaging modalities to provide a high lateral resolution of ~290 nm with reflection-mode imaging capability, which is essential for studying intricate anatomy, such as that of the brain. Taking advantage of the complementary and comprehensive contrasts of the system, we demonstrated high-resolution imaging of various tissues in living mice, including microvasculature (by photoacoustics), epidermis cells, cortical neurons (by two-photon fluorescence), and extracellular collagen fibers (by SHG). The intrinsic image co-registration of the three modalities conveniently provided improved visualization and understanding of the tissue microarchitecture. The reported results suggest that, by revealing complementary tissue microstructures in vivo, this multimodal microscopy can potentially facilitate a broad range of biomedical studies, such as imaging of the tumor microenvironment and neurovascular coupling.

  18. Towards characterization and identification of solid state pharmaceutical mixtures through second harmonic generation.

    Science.gov (United States)

    Rawle, Chris B; Lee, Chris J; Strachan, Clare J; Payne, Keith; Manson, Peter J; Rades, Thomas

    2006-04-01

    In this paper, we report improvements to a previously developed method based on optical nonlinearity for characterizing polymorphism and concentration of pharmaceuticals in powdered and tablet form. An apparatus that measures the nonlinear optical response of a sample through second harmonic generation (SHG) is described. The response of several enalapril maleate-polyvinylpyrrolidone (PVP) tablets was measured, the results of which were used to determine the concentration of the drug. The current limit of detection of the apparatus was found to be approximately 1%-2%. Ranitidine hydrochloride (RN) polymorph forms I and II were also characterized using SHG. It was found that pure samples of forms I and II could be clearly and rapidly distinguished. Mixtures consisting of 50% form I and 50% form II were also distinguishable from the respective pure forms. An investigation was performed into the size dependence of the SHG response for crystalline lactose. It was found that the SHG response was a slowly decreasing monotonic function of particle size. Additional investigation into the angular dependence of the scattered SHG light was also undertaken for crystalline lactose. This new technique based on optical nonlinearity offers promise for application in monitoring of pharmaceutical manufacturing processes.

  19. Quantification of collagen I in airway tissues using second harmonic generation.

    Science.gov (United States)

    Tjin, Gavin; Xu, Paul; Kable, Scott H; Kable, Eleanor P W; Burgess, Janette K

    2014-03-01

    Extracellular matrix (ECM) remodeling contributes to the pathogenic changes in chronic obstructive pulmonary disease (COPD) and is both complex and not well understood. Collagen I, a component of the ECM altered in COPD airways, has second harmonic generation (SHG) properties. The SHG signal is coherent, propagating both forward (F) (primarily organized/mature collagen fibrils) and backward (B) (primarily disorganized/immature collagen fibrils) parallel to the incident light. The F/B SHG ratio was used to determine the proportion of organized to disorganized collagen, with lower variation in F/B ratio between sampling regions within the same patient and between patients in the same disease group compared with analyzing F and B data alone. The F/B ratio was independent of laser power drift, regions analyzed within a tissue and tissue orientation during analysis. Using this method, we identified a significant difference in collagen organization in airway tissue between COPD and non diseased. We have developed a robust optimization and calibration methodology that will allow direct comparison of data obtained at different times and from multiple microscopes, which is directly adaptable for use with other tissue types. We report a powerful new tool for advancing our understanding of pathological ECM remodeling that may uncover new therapeutic targets in the future.

  20. Automated biphasic morphological assessment of hepatitis B-related liver fibrosis using second harmonic generation microscopy

    Science.gov (United States)

    Wang, Tong-Hong; Chen, Tse-Ching; Teng, Xiao; Liang, Kung-Hao; Yeh, Chau-Ting

    2015-08-01

    Liver fibrosis assessment by biopsy and conventional staining scores is based on histopathological criteria. Variations in sample preparation and the use of semi-quantitative histopathological methods commonly result in discrepancies between medical centers. Thus, minor changes in liver fibrosis might be overlooked in multi-center clinical trials, leading to statistically non-significant data. Here, we developed a computer-assisted, fully automated, staining-free method for hepatitis B-related liver fibrosis assessment. In total, 175 liver biopsies were divided into training (n = 105) and verification (n = 70) cohorts. Collagen was observed using second harmonic generation (SHG) microscopy without prior staining, and hepatocyte morphology was recorded using two-photon excitation fluorescence (TPEF) microscopy. The training cohort was utilized to establish a quantification algorithm. Eleven of 19 computer-recognizable SHG/TPEF microscopic morphological features were significantly correlated with the ISHAK fibrosis stages (P 0.82 for liver cirrhosis detection. Since no subjective gradings are needed, interobserver discrepancies could be avoided using this fully automated method.

  1. Characterization of salt interferences in second-harmonic generation detection of protein crystals

    Science.gov (United States)

    Closser, R. G.; Gualtieri, E. J.; Newman, J. A.; Simpson, G. J.

    2013-01-01

    Studies were undertaken to assess the merits and limitations of second-harmonic generation (SHG) for the selective detection of protein and polypeptide crystal formation, focusing on the potential for false positives from SHG-active salts present in crystallization media. The SHG activities of salts commonly used in protein crystallization were measured and quantitatively compared with reference samples. Out of 19 salts investigated, six produced significant background SHG and 15 of the 96 wells of a sparse-matrix screen produced SHG upon solvent evaporation. SHG-active salts include phosphates, hydrated sulfates, formates and tartrates, while chlorides, acetates and anhydrous sulfates resulted in no detectable SHG activity. The identified SHG-active salts produced a range of signal intensities spanning nearly three orders of magnitude. However, even the weakest SHG-active salt produced signals that were several orders of magnitude greater than those produced by typical protein crystals. In general, SHG-active salts were identifiable through characteristically strong SHG and negligible two-photon-excited ultraviolet fluorescence (TPE-UVF). Exceptions included trials containing either potassium dihydrogen phosphate or ammonium formate, which produced particularly strong SHG, but with residual weak TPE-UVF signals that could potentially complicate discrimination in crystallization experiments using these precipitants. PMID:24282335

  2. Second harmonic generation microscopy differentiates collagen type I and type III in COPD

    Science.gov (United States)

    Suzuki, Masaru; Kayra, Damian; Elliott, W. Mark; Hogg, James C.; Abraham, Thomas

    2012-03-01

    The structural remodeling of extracellular matrix proteins in peripheral lung region is an important feature in chronic obstructive pulmonary disease (COPD). Multiphoton microscopy is capable of inducing specific second harmonic generation (SHG) signal from non-centrosymmetric structural proteins such as fibrillar collagens. In this study, SHG microscopy was used to examine structural remodeling of the fibrillar collagens in human lungs undergoing emphysematous destruction (n=2). The SHG signals originating from these diseased lung thin sections from base to apex (n=16) were captured simultaneously in both forward and backward directions. We found that the SHG images detected in the forward direction showed well-developed and well-structured thick collagen fibers while the SHG images detected in the backward direction showed striking different morphological features which included the diffused pattern of forward detected structures plus other forms of collagen structures. Comparison of these images with the wellestablished immunohistochemical staining indicated that the structures detected in the forward direction are primarily the thick collagen type I fibers and the structures identified in the backward direction are diffusive structures of forward detected collagen type I plus collagen type III. In conclusion, we here demonstrate the feasibility of SHG microscopy in differentiating fibrillar collagen subtypes and understanding their remodeling in diseased lung tissues.

  3. Giant second harmonic generation by engineering of double plasmonic resonances at nanoscale

    CERN Document Server

    Ren, Ming-Liang; Wang, Ben-Li; Chen, Bao-Qin; Li, Jiafang; Li, Zhi-Yuan

    2014-01-01

    We have investigated second harmonic generation (SHG) from Ag-coated LiNbO3 (LN) core-shell nanocuboids and found that giant SHG can occur via deliberately designed double plasmonic resonances. By controlling the aspect ratio, we can tune fundamental wave (FW) and SHG signal to match the longitudinal and transverse plasmonic modes simultaneously, and achieve giant enhancement of SHG by more than five orders of magnitude in comparison to a bare LN nanocuboid and by about one order of magnitude to the case adopting only single plasmonic resonance. The underlying key physics is that the double-resonance nanoparticle enables greatly enhanced trapping and harvesting of incident FW energy, efficient internal transfer of optical energy from FW to SHW, and much improved power to transport the SHG energy from the nanoparticle to the far-field region. The proposed double-resonance nanostructure can serve as an efficient subwavelength coherent light source through SHG and enable flexible engineering of light-matter inte...

  4. Optical second-harmonic generation measurements of porous low-k dielectric materials

    Science.gov (United States)

    Atkin, Joanna; Shaw, Thomas; Laibowitz, Robert; Heinz, Tony

    2009-03-01

    Low-k dielectric materials based on porous carbon-doped oxides, with relative dielectric constants as low as 2.1, are widely used as thin insulating films in the microelectronics industry. Knowledge of these materials' basic electronic properties, such as energy gaps, barrier heights, and trap states, is essential for modeling their electrical leakage and stability characteristics. We use femtosecond laser pulses to probe the dynamics of charge-carrier transfer processes across Si/LKD interfacial barriers by optical second harmonic generation (SHG). Larger electric fields from multiphoton injection can be developed in Si/LKD systems compared to Si/SiO2, indicating a significantly higher density of traps in the LKD. This is consistent with previously reported measurements of trap density by photoinjection techniques^*. We will also discuss results on the dynamics of discharging and on the dependence of charging phenomena on layer thickness. ^*J. M. Atkin, D. Song, T. M. Shaw, E. Cartier, R. B. Laibowitz, and T. F. Heinz, J. Appl. Phys. 103, 094104 (2008).

  5. 3D texture analysis for classification of second harmonic generation images of human ovarian cancer

    Science.gov (United States)

    Wen, Bruce; Campbell, Kirby R.; Tilbury, Karissa; Nadiarnykh, Oleg; Brewer, Molly A.; Patankar, Manish; Singh, Vikas; Eliceiri, Kevin. W.; Campagnola, Paul J.

    2016-10-01

    Remodeling of the collagen architecture in the extracellular matrix (ECM) has been implicated in ovarian cancer. To quantify these alterations we implemented a form of 3D texture analysis to delineate the fibrillar morphology observed in 3D Second Harmonic Generation (SHG) microscopy image data of normal (1) and high risk (2) ovarian stroma, benign ovarian tumors (3), low grade (4) and high grade (5) serous tumors, and endometrioid tumors (6). We developed a tailored set of 3D filters which extract textural features in the 3D image sets to build (or learn) statistical models of each tissue class. By applying k-nearest neighbor classification using these learned models, we achieved 83-91% accuracies for the six classes. The 3D method outperformed the analogous 2D classification on the same tissues, where we suggest this is due the increased information content. This classification based on ECM structural changes will complement conventional classification based on genetic profiles and can serve as an additional biomarker. Moreover, the texture analysis algorithm is quite general, as it does not rely on single morphological metrics such as fiber alignment, length, and width but their combined convolution with a customizable basis set.

  6. Analysis of second-harmonic-generation microscopy in a mouse model of ovarian carcinoma.

    Science.gov (United States)

    Watson, Jennifer M; Rice, Photini F; Marion, Samuel L; Brewer, Molly A; Davis, John R; Rodriguez, Jeffrey J; Utzinger, Urs; Hoyer, Patricia B; Barton, Jennifer K

    2012-07-01

    Second-harmonic-generation (SHG) imaging of mouse ovaries ex vivo was used to detect collagen structure changes accompanying ovarian cancer development. Dosing with 4-vinylcyclohexene diepoxide and 7,12-dimethylbenz[a]anthracene resulted in histologically confirmed cases of normal, benign abnormality, dysplasia, and carcinoma. Parameters for each SHG image were calculated using the Fourier transform matrix and gray-level co-occurrence matrix (GLCM). Cancer versus normal and cancer versus all other diagnoses showed the greatest separation using the parameters derived from power in the highest-frequency region and GLCM energy. Mixed effects models showed that these parameters were significantly different between cancer and normal (P<0.008). Images were classified with a support vector machine, using 25% of the data for training and 75% for testing. Utilizing all images with signal greater than the noise level, cancer versus not-cancer specimens were classified with 81.2% sensitivity and 80.0% specificity, and cancer versus normal specimens were classified with 77.8% sensitivity and 79.3% specificity. Utilizing only images with greater than of 75% of the field of view containing signal improved sensitivity and specificity for cancer versus normal to 81.5% and 81.1%. These results suggest that using SHG to visualize collagen structure in ovaries could help with early cancer detection.

  7. Second harmonic generation imaging of skin wound healing and scarring in a rabbit ear model

    Science.gov (United States)

    Tang, Yiyan; Zhu, Xiaoqin; Xiong, Shuyuan; Chen, Jianxin

    2012-12-01

    Skin wound healing and scarring in rabbit ears was examined by second harmonic generation (SHG) microscopy. Rabbit ear wound model was created by punching from the ventral surface with removal of epidermis, dermis and perichondrium. The samples were collected weekly, and cut into 100 μm thickness sections for SHG imaging. SHG imaging system was operated at 810 nm, producing SHG signals at half the excitation wavelength 405 nm. A Plan-Neofluar objective (x40 and NA=0.75) was employed for focusing the excitation beam into tissue samples and was also used to collect the backscattered intrinsic SHG signals. Our results showed apparent difference in collagen content and microstructure at various wound healing and scarring time points. It suggested that SHG signals from collagen can serve as a good indicator for characterization of wound status. With the advancement on miniaturization, microscopy based on SHG will become a valuable tool for monitoring the wound healing and scarring in vivo, and help to guide the improvement of scar appearance with appropriate and subtle modulation during wound healing based on better understanding of scarring response mechanism.

  8. Observation of tendon repair in animal model using second-harmonic-generation microscopy

    Science.gov (United States)

    Hase, Eiji; Minamikawa, Takeo; Sato, Katsuya; Takahashi, Mitsuhiko; Yasui, Takashi

    2016-03-01

    Tendon rupture is a trauma difficult to recover the condition before injury. In previous researches, tensile test and staining method have been widely used to elucidate the mechanism of the repair process from the viewpoints of the mechanical property and the histological findings. However, since both methods are destructive and invasive, it is difficult to obtain both of them for the same sample. If both the mechanical property and the histological findings can be obtained from the same sample, one may obtain new findings regarding mechanisms of tendon repairing process. In this paper, we used second-harmonic-generation (SHG) microscopy, showing high selectivity and good image contrast to collagen molecules as well as high spatial resolution, optical three-dimensional sectioning, deep penetration, and without additional staining. Since SHG light intensity sensitively reflects the structural maturity of collagen molecule and its aggregates, it will be a good indicator for the repairing degree of the ruptured tendon. From comparison of SHG images between the 4-weeks-repaired tendon and the sound tendon in the animal model, we confirmed that SHG light intensity of the repaired tendon was significantly lower than that of the sound tendon, indicating that the collagen structure in the repaired tendon is still immature. Furthermore, we performed both SHG imaging and the tensile test for the same sample, and confirmed a correlation between them. This result shows a potential of SHG light for an indicator of the histological and mechanical recovery of the ruptured tendon.

  9. Multipolar Effects in the Optical Active Second Harmonic Generation from Sawtooth Chiral Metamaterials.

    Science.gov (United States)

    Su, Huimin; Guo, Yuxiang; Gao, Wensheng; Ma, Jie; Zhong, Yongchun; Tam, Wing Yim; Chan, C T; Wong, Kam Sing

    2016-02-25

    Based on the facts that chiral molecules response differently to left- and right-handed circular polarized light, chiroptical effects are widely employed for determining structure chirality, detecting enantiomeric excess, or controlling chemical reactions of molecules. Compared to those in natural materials, chiroptical behaviors can be significantly amplified in chiral plasmonic metamaterials due to the concentrated local fields in the structure. The on-going research towards giant chiroptical effects in metamaterial generally focus on optimizing the field-enhancement effects. However, the observed chiroptical effects in metamaterials rely on more complicated factors and various possibilities towards giant chiroptical effects remains unexplored. Here we study the optical-active second harmonic generation (SHG) behaviors in a pair of planar sawtooth gratings with mirror-imaged patterns. Significant multipolar effects were observed in the polarization-dependent SHG curves. We show that the chirality of the nanostructure not only give rise to nonzero chiral susceptibility tensor components within the electric-dipole approximation, but also lead to different levels of multipolar interactions for the two orthogonal circular polarizations that further enhance the nonlinear optical activity of the material. Our results thus indicate novel ways to optimize nonlinear plasmonic structures and achieve giant chiroptical response via multipolar interactions.

  10. Fully integrated reflection-mode photoacoustic, two-photon, and second harmonic generation microscopy in vivo

    Science.gov (United States)

    Song, Wei; Xu, Qiang; Zhang, Yang; Zhan, Yang; Zheng, Wei; Song, Liang

    2016-01-01

    The ability to obtain comprehensive structural and functional information from intact biological tissue in vivo is highly desirable for many important biomedical applications, including cancer and brain studies. Here, we developed a fully integrated multimodal microscopy that can provide photoacoustic (optical absorption), two-photon (fluorescence), and second harmonic generation (SHG) information from tissue in vivo, with intrinsically co-registered images. Moreover, using a delicately designed optical-acoustic coupling configuration, a high-frequency miniature ultrasonic transducer was integrated into a water-immersion optical objective, thus allowing all three imaging modalities to provide a high lateral resolution of ~290 nm with reflection-mode imaging capability, which is essential for studying intricate anatomy, such as that of the brain. Taking advantage of the complementary and comprehensive contrasts of the system, we demonstrated high-resolution imaging of various tissues in living mice, including microvasculature (by photoacoustics), epidermis cells, cortical neurons (by two-photon fluorescence), and extracellular collagen fibers (by SHG). The intrinsic image co-registration of the three modalities conveniently provided improved visualization and understanding of the tissue microarchitecture. The reported results suggest that, by revealing complementary tissue microstructures in vivo, this multimodal microscopy can potentially facilitate a broad range of biomedical studies, such as imaging of the tumor microenvironment and neurovascular coupling. PMID:27576922

  11. In vivo multiphoton imaging of the cornea: polarization-resolved second harmonic generation from stromal collagen

    Science.gov (United States)

    Latour, G.; Gusachenko, I.; Kowalczuk, L.; Lamarre, I.; Schanne-Klein, M.-C.

    2012-03-01

    Multiphoton microscopy provides specific and contrasted images of unstained collagenous tissues such as tendons or corneas. Polarization-resolved second harmonic generation (SHG) measurements have been implemented in a laserscanning multiphoton microscope. Distortion of the polarimetric response due to birefringence and diattenuation during propagation of the laser excitation has been shown in rat-tail tendons. A model has been developed to account for these effects and correct polarization-resolved SHG images in thick tissues. This new modality is then used in unstained human corneas to access two quantitative parameters: the fibrils orientation within the collagen lamellae and the ratio of the main second-order nonlinear tensorial components. Orientation maps obtained from polarization resolution of the trans-detected SHG images are in good agreement with the striated features observed in the raw images. Most importantly, polarization analysis of the epi-detected SHG images also enables to map the fibrils orientation within the collagen lamellae while epi-detected SHG images of corneal stroma are spatially homogenous and do not enable direct visualization of the fibrils orientation. Depth profiles of the polarimetric SHG response are also measured and compared to models accounting for orientation changes of the collagen lamellae within the focal volume. Finally, in vivo polarization-resolved SHG is performed in rat corneas and structural organization of corneal stroma is determined using epi-detected signals.

  12. Quantitative analysis of biological tissues using Fourier transform-second-harmonic generation imaging

    Science.gov (United States)

    Ambekar Ramachandra Rao, Raghu; Mehta, Monal R.; Toussaint, Kimani C., Jr.

    2010-02-01

    We demonstrate the use of Fourier transform-second-harmonic generation (FT-SHG) imaging of collagen fibers as a means of performing quantitative analysis of obtained images of selected spatial regions in porcine trachea, ear, and cornea. Two quantitative markers, preferred orientation and maximum spatial frequency are proposed for differentiating structural information between various spatial regions of interest in the specimens. The ear shows consistent maximum spatial frequency and orientation as also observed in its real-space image. However, there are observable changes in the orientation and minimum feature size of fibers in the trachea indicating a more random organization. Finally, the analysis is applied to a 3D image stack of the cornea. It is shown that the standard deviation of the orientation is sensitive to the randomness in fiber orientation. Regions with variations in the maximum spatial frequency, but with relatively constant orientation, suggest that maximum spatial frequency is useful as an independent quantitative marker. We emphasize that FT-SHG is a simple, yet powerful, tool for extracting information from images that is not obvious in real space. This technique can be used as a quantitative biomarker to assess the structure of collagen fibers that may change due to damage from disease or physical injury.

  13. Analysis of human knee osteoarthritic cartilage using polarization sensitive second harmonic generation microscopy

    Science.gov (United States)

    Kumar, Rajesh; Grønhaug, Kirsten M.; Romijn, Elisabeth I.; Drogset, Jon O.; Lilledahl, Magnus B.

    2014-05-01

    Osteoarthritis is one of the most prevalent joint diseases in the world. Although the cause of osteoarthritis is not exactly clear, the disease results in a degradation of the quality of the articular cartilage including collagen and other extracellular matrix components. We have investigated alterations in the structure of collagen fibers in the cartilage tissue of the human knee using mulitphoton microscopy. Due to inherent high nonlinear susceptibility, ordered collagen fibers present in the cartilage tissue matrix produces strong second harmonic generation (SHG) signals. Significant morphological differences are found in different Osteoarthritic grades of cartilage by SHG microscopy. Based on the polarization analysis of the SHG signal, we find that a few locations of hyaline cartilage (mainly type II collagen) is being replaced by fibrocartilage (mainly type I cartilage), in agreement with earlier literature. To locate the different types and quantify the alteration in the structure of collagen fiber, we employ polarization-SHG microscopic analysis, also referred to as _-tensor imaging. The image analysis of p-SHG image obtained by excitation polarization measurements would represent different tissue constituents with different numerical values at pixel level resolution.

  14. Quantitative evaluation of skeletal muscle defects in second harmonic generation images

    Science.gov (United States)

    Liu, Wenhua; Raben, Nina; Ralston, Evelyn

    2013-02-01

    Skeletal muscle pathologies cause irregularities in the normally periodic organization of the myofibrils. Objective grading of muscle morphology is necessary to assess muscle health, compare biopsies, and evaluate treatments and the evolution of disease. To facilitate such quantitation, we have developed a fast, sensitive, automatic imaging analysis software. It detects major and minor morphological changes by combining texture features and Fourier transform (FT) techniques. We apply this tool to second harmonic generation (SHG) images of muscle fibers which visualize the repeating myosin bands. Texture features are then calculated by using a Haralick gray-level cooccurrence matrix in MATLAB. Two scores are retrieved from the texture correlation plot by using FT and curve-fitting methods. The sensitivity of the technique was tested on SHG images of human adult and infant muscle biopsies and of mouse muscle samples. The scores are strongly correlated to muscle fiber condition. We named the software MARS (muscle assessment and rating scores). It is executed automatically and is highly sensitive even to subtle defects. We propose MARS as a powerful and unbiased tool to assess muscle health.

  15. The application of the symmetry properties of optical second harmonic generation to studies of interfaces and gases

    Energy Technology Data Exchange (ETDEWEB)

    Feller, M.B.

    1991-11-01

    Optical second harmonic generation has proven to be a powerful tool for studying interfaces. The symmetry properties of the process allow for surface sensitivity not available with other optical methods. In this thesis, we take advantage of these symmetry properties SHG to study a variety of interesting systems not previously studied with this technique. We show that optical second harmonic generation is an effective surface probe with a submonolayer sensitivity for media without inversion symmetry. We demonstrate the technique at a gallium arsenide surface, exploiting the different symmetry properties of the bulk and surface of the crystal to isolate the surface contribution. We also demonstrate that optical second harmonic generation can be used to determine the anisotropic orientational distribution of a surface monolayer of molecules. We apply the technique to study homogeneously aligned liquid crystal cells. To further explore the LC-polymer interface, we used SHG to study the surface memory effect. The surface memory effect is the rendering of an isotropic interface anisotropic by putting it in contact with an anisotropic bulk. Last, we describe some preliminary measurements of a time-resolved spectroscopic study of the phenomenon of second harmonic generation in a gas. The construction of a 500 microjoule pulsed, tunable laser source is described.

  16. Second-harmonic generation from thin films of mixtures of an aggregated chiral 4-nitroazobenzene dye and amylose acetate

    NARCIS (Netherlands)

    Schoondorp, Monique A.; Schouten, Arend Jan; Hulshof, Johannes; Schudde, Ebe P.; Feringa, Ben L.

    1994-01-01

    Second-harmonic generation (SHG) from both Langmuir-Blodgett (LB) films and solvent-cast films of mixtures of a chiral nonlinear optical (NLO) dye, an ester of palmitic acid and 4-nitro-4'-[(3R)-hydroxypyrrolidinyl]azobenzene (KMES16) and amylose acetate is investigated. Results are discussed concer

  17. Influences of interfacial properties on second-harmonic generation of Lamb waves propagating in layered planar structures

    Energy Technology Data Exchange (ETDEWEB)

    Deng Mingxi [College of Automation, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); Wang Ping [College of Automation, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); Lv Xiafu [College of Automation, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China)

    2006-07-21

    This paper describes influences of interfacial properties on second-harmonic generation of Lamb waves propagating in layered planar structures. The nonlinearity in the elastic wave propagation is treated as a second-order perturbation of the linear elastic response. Due to the kinematic nonlinearity and the elastic nonlinearity of materials, there are second-order bulk and surface/interface driving sources in layered planar structures through which Lamb waves propagate. These driving sources can be thought of as forcing functions of a series of double frequency lamb waves (DFLWs) in terms of the approach of modal expansion analysis for waveguide excitation. The total second-harmonic fields consist of a summation of DFLWs in the corresponding stress-free layered planar structures. The interfacial properties of layered planar structures can be described by the well-known finite interfacial stiffness technique. The normal and tangential interfacial stiffness constants can be coupled with the equation governing the expansion coefficient of each DFLW component. On the other hand, the normal and tangential interfacial stiffness constants are associated with the degree of dispersion between Lamb waves and DFLWs. Theoretical analyses and numerical simulations indicate that the efficiency of second-harmonic generation by Lamb wave propagation is closely dependent on the interfacial properties of layered structures. The potential of using the effect of second-harmonic generation by Lamb wave propagation to characterize the interfacial properties of layered structures are considered. Some experimental results are presented.

  18. High-power green light generation by second harmonic generation of single-frequency tapered diode lasers

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Andersen, Peter E.; Sumpf, Bernd;

    2010-01-01

    laser emits in excess of 9 W single-frequency output power with a good beam quality. The output from the tapered diode laser is frequency doubled using periodically poled MgO:LiNbO3. We investigate the modulation potential of the green light and improve the modulation depth from 1:4 to 1:50.......We demonstrate the generation of high power (>1.5W) and single-frequency green light by single-pass second harmonic generation of a high power tapered diode laser. The tapered diode laser consists of a DBR grating for wavelength selectivity, a ridge section and a tapered section. The DBR tapered...

  19. Derivation of the three-layer model for surface second-harmonic generation

    CERN Document Server

    Anderson, Sean M

    2016-01-01

    We develop explicit expressions for the surface second-harmonic radiation yield using the three layer model. We derive expressions that can be applied to systems without and symmetry considerations, and then reduce them for the (111), (110), and (100) surface symmetries.

  20. Second-harmonic generation reveals a relationship between metastatic potential and collagen fiber structure

    Science.gov (United States)

    Burke, Kathleen A.; Dawes, Ryan P.; Cheema, Mehar K.; Perry, Seth; Brown, Edward

    2014-02-01

    Second Harmonic Generation (SHG) of collagen signals allows for the analysis of collagen structural changes throughout metastatic progression. The directionality of coherent SHG signals, measured through the ratio of the forward-propagating to backward propagating signal (F/B ratio), is affected by fibril diameter, spacing, and order versus disorder of fibril packing within a fiber. As tumors interact with their microenvironment and metastasize, it causes changes in these parameters, and concurrent changes in the F/B ratio. Specifically, the F/B ratio of breast tumors that are highly metastatic to the lymph nodes is significantly higher than those in tumors with restricted lymph node involvement. We utilized in vitro analysis of tumor cell motility through collagen gels of different microstructures, and hence different F/B ratios, to explore the relationship between collagen microstructures and metastatic capabilities of the tumor. By manipulating environmental factors of fibrillogenesis and biochemical factors of fiber composition we created methods of varying the average F/B ratio of the gel, with significant changes in fiber structure occurring as a result of alterations in incubation temperature and increasing type III collagen presence. A migration assay was performed using simultaneous SHG and fluorescent imaging to measure average penetration depth of human tumor cells into the gels of significantly different F/B ratios, with preliminary data demonstrating that cells penetrate deeper into gels of higher F/B ratio caused by lower type III collagen concentration. Determining the role of collagen structure in tumor cell motility will aid in the future prediction metastatic capabilities of a primary tumor.

  1. Hyperglycemia-induced abnormalities in rat and human corneas: the potential of second harmonic generation microscopy.

    Directory of Open Access Journals (Sweden)

    Gaël Latour

    Full Text Available BACKGROUND: Second Harmonic Generation (SHG microscopy recently appeared as an efficient optical imaging technique to probe unstained collagen-rich tissues like cornea. Moreover, corneal remodeling occurs in many diseases and precise characterization requires overcoming the limitations of conventional techniques. In this work, we focus on diabetes, which affects hundreds of million people worldwide and most often leads to diabetic retinopathy, with no early diagnostic tool. This study then aims to establish the potential of SHG microscopy for in situ detection and characterization of hyperglycemia-induced abnormalities in the Descemet's membrane, in the posterior cornea. METHODOLOGY/PRINCIPAL FINDINGS: We studied corneas from age-matched control and Goto-Kakizaki rats, a spontaneous model of type 2 diabetes, and corneas from human donors with type 2 diabetes and without any diabetes. SHG imaging was compared to confocal microscopy, to histology characterization using conventional staining and transmitted light microscopy and to transmission electron microscopy. SHG imaging revealed collagen deposits in the Descemet's membrane of unstained corneas in a unique way compared to these gold standard techniques in ophthalmology. It provided background-free images of the three-dimensional interwoven distribution of the collagen deposits, with improved contrast compared to confocal microscopy. It also provided structural capability in intact corneas because of its high specificity to fibrillar collagen, with substantially larger field of view than transmission electron microscopy. Moreover, in vivo SHG imaging was demonstrated in Goto-Kakizaki rats. CONCLUSIONS/SIGNIFICANCE: Our study shows unambiguously the high potential of SHG microscopy for three-dimensional characterization of structural abnormalities in unstained corneas. Furthermore, our demonstration of in vivo SHG imaging opens the way to long-term dynamical studies. This method should be easily

  2. Investigating membrane nanoporation induced by bipolar pulsed electric fields via second harmonic generation

    Science.gov (United States)

    Moen, E. K.; Ibey, B. L.; Beier, H. T.; Armani, A. M.

    2016-09-01

    Electric pulses have become an effective tool for transporting cargo (DNA, drugs, etc.) across cell membranes. This enhanced transport is believed to occur through temporary pores formed in the plasma membrane. Traditionally, millisecond duration, monopolar (MP) pulses are used for electroporation, but bipolar (BP) pulses have proven equally effective as MP pulses with the added advantage of less cytotoxicity. With the goal of further reducing cytotoxic effects and inducing non-thermal, intra-cellular effects, researchers began investigating reduced pulse durations, pushing into the nanosecond regime. Cells exposed to these MP, nanosecond pulsed electric fields (nsPEFs) have shown increased repairable membrane permeability and selective channel activation. However, attempts to improve this further by moving to the BP pulse regime has proven unsuccessful. In the present work, we use second harmonic generation imaging to explore the structural effects of bipolar nsPEFs on the plasma membrane. By varying the temporal spacing between the pulse phases over several orders of magnitude and comparing the response to a single MP case, we systematically examine the disparity in cellular response. Our circuit-based model predicts that, as the temporal spacing increases several orders of magnitude, nanoporation increases and eventually exceeds the MP case. On the whole, our experimental data agree with this assertion; however, a detailed analysis of the data sets demonstrates that biological processes may play a larger role in the observed response than previously thought, dominating the effect for temporal spacing up to 5 μs. These findings could ultimately lead to understanding the biophysical mechanism underlying all electroporation.

  3. Investigation of thermally-induced phase mismatching in continuous-wave second harmonic generation: a theoretical model.

    Science.gov (United States)

    Sabaeian, Mohammad; Mousave, Laleh; Nadgaran, Hamid

    2010-08-30

    A fraction of the fundamental beam energy deposited into nonlinear crystals to generate second harmonic waves (SHW) causes a temperature gradient within the crystal. This temperature inhomogeneity can alter the refractive index of the medium leading to a well-known effect called thermal dispersion. Therefore, the generated SHW suffers from thermal lensing and a longitudinal thermal phase mismatching. In this work by coupling the heat equation with second harmonic generation (SHG) formalism applied to type-II configuration along with walk-off effect, we investigate the continuous wave (CW) SHW beam profile and conversion efficiency when a non-linear KTP crystal is under induced thermal load. We have demonstrated for average and high powers, the thermal de-phasing lead to considerable reduction in SHG compared to an ideal case in which induced heat is neglected.

  4. Phase matched backward-wave second harmonic generation in a hyperbolic carbon nanoforest

    CERN Document Server

    Popov, A K; Myslivets, S A

    2016-01-01

    We show that deliberately engineered spatially dispersive metamaterial slab can enable co-existence and phase matching of contra-propagating ordinary fundamental and backward second harmonic electromagnetic modes. Energy flux and phase velocity are contra-directed in backward waves which determines extraordinary nonlinear-optical propagation processes. Frequencies, phase and group velocities, as well as nanowavequide losses inherent to the electromagnetic modes supported by the metamaterial can be tailored to optimize nonlinear-optical conversion of frequencies and propagation directions of the coupled waves. Such a possibility, which is of paramount importance for nonlinear photonics, is proved with numerical model of the hyperbolic metamaterial made of carbon nanotubes standing on metal surface. Extraordinary properties of backward-wave second harmonic in the THz and IR propagating in the reflection direction are investigated with focus on pulsed regime.

  5. High efficiency second-harmonic generation in multi-pass quadrature arrangement

    Energy Technology Data Exchange (ETDEWEB)

    Kiriyama, Hiromitsu; Nakano, Fumihiko; Yamakawa, Koichi [Japan Atomic Energy Research Institute, Kansai Research Establishment, Kizu, Kyoto (Japan)

    2001-05-01

    We report on multi-pass quadrature frequency conversion of high-energy and high-average-power lasers with high conversion efficiency for pumping high peak power, ultrashort pulse Ti:sapphire laser amplifiers. Using a four-pass quadrature second harmonic scheme with KTiOPO{sub 4} (KTP) crystals, we obtained an efficiency from a fundamental laser energy into a total second-harmonic laser energy in excess of 80% of a commercial Q-Switched 1064-nm Nd:YAG laser at a low input fundamental laser intensity of 76 MW/cm{sup 2}. For higher power operation, we employed a two-pass quadrature scheme with CsLiB{sub 6}O{sub 10} (CLBO) crystals. We obtained a total second-harmonic output pulse energy of 2.73 J from an input 1064-nm fundamental pulse energy of 3.27 J of a custom-built Q-switched 1064-nm Nd:YAG laser system at a fundamental laser intensity of 330 MW/cm{sup 2} at 10 Hz, corresponding to energy conversion efficiency of 83%. We discuss the details of the design and performance of this frequency conversion scheme in terms of output energy, conversion efficiency and scalability. (author)

  6. Organic salts of biguanide - An attempt to crystal engineering of novel materials for second harmonic generation

    Science.gov (United States)

    Matulková, Irena; Němec, Ivan; Císařová, Ivana; Němec, Petr; Vaněk, Přemysl

    2010-03-01

    Three organic salts of biguanide with oxalic, succinic and L-tartaric acids have been prepared and X-ray structural analysis has been performed. Biguanidium(1+) oxalate hemihydrate ( a = 6.8330(2) Å, b = 10.0430(2) Å, c = 14.6230(4) Å, α = 90.236(1) , β = 90.333(1) , γ = 105.605(2) , V = 966.46(4) Å 3, Z = 1, R = 0.0393 for 3704 observed reflections) and biguanidium(1+) hydrogen succinate ( a = 6.4600(1) Å, b = 6.7670(2) Å, c = 11.4150(3) Å, α = 91.822(1) , β = 105.312(1) , γ = 90.922(1) , V = 480.89(2) Å 3, Z = 2, R = 0.0357 for 1880 observed reflections) belong to the triclinic space group P 1¯. Their crystal structures are based on biguanidium(1+) pairs connected by intermolecular N-H⋯N hydrogen bonds. The remaining ions (eventually water molecules) form a 3D structural network with these pairs. Furthermore, the formation of the cationic and anionic layers interconnected by intermolecular N-H⋯O hydrogen bonds was observed in the crystal structure of biguanidium(1+) hydrogen succinate. Biguanidium(2+) L-tartrate crystallizes in the orthorhombic space group P 2 12 12 1 ( a = 6.7170(2) Å, b = 9.2740(2) Å, c = 16.1500(4) Å, V = 1006.04(4) Å 3, Z = 4, R = 0.0432 for 2193 observed reflections). The crystal structure is based on L-tartrate chains, which are interconnected by isolated biguanidium(2+) cations via several types of N-H⋯O hydrogen bonds. The formation of L-tartrate chains is mediated by two types of intermolecular O-H⋯O hydrogen bonds connecting the hydroxyl and carboxylate groups. The FTIR and FT Raman spectra of all the compounds were recorded and discussed. The theoretical values of the first hyperpolarizability components were calculated for biguanidium(1+) and biguanidium(2+) cations at the B3LYP level with the 6-311G(d,p) basis set. Quantitative measurements of the second harmonic generation of powdered biguanidium(2+) L-tartrate at 800 nm were performed and a relative efficiency of 2% (compared to KDP) was

  7. Polarization Second Harmonic Generation Discriminates Between Fresh and Aged Starch-Based Adhesives Used in Cultural Heritage.

    Science.gov (United States)

    Psilodimitrakopoulos, Sotiris; Gavgiotaki, Evaggelia; Melessanaki, Kristallia; Tsafas, Vassilis; Filippidis, George

    2016-10-01

    In this work, we report that polarization second harmonic generation (PSHG) microscopy, commonly used in biomedical imaging, can quantitatively discriminate naturally aged from fresh starch-based glues used for conservation or restoration of paintings, works of art on paper, and books. Several samples of fresh and aged (7 years) flour and starch pastes were investigated by use of PSHG. In these types of adhesives, widely used in cultural heritage conservation, second harmonic generation (SHG) contrast originates primarily from the starch granules. It was found that in aged glues, the starch SHG effective orientation (SHG angle, θ) shifts to significantly higher values in comparison to the fresh granules. This shift is attributed to the different degree of granule hydration between fresh and aged adhesives. Thus noninvasive high-resolution nonlinear scattering can be employed to detect and quantify the degree of deterioration of restoration adhesives and to provide guidance toward future conservation treatments.

  8. Synthesis and Study of Second Harmonic Generation in 4,4'-DINITROPHENYL 1,1'-ADIPAMIDE (dnpa)

    Science.gov (United States)

    Trivedi, Rashmi; Sen, Pratima; Sen, Pranay K.

    We synthesized 4,4'-dinitrophenyl 1,1'-adipamide (DNPA) and studied optical second harmonic generation (SHG) in this organic material using the Kurtz method. The experimental analysis of SHG was made for a range of particle size of DNPA. It was observed that DNPA is nearly three times more SHG active than urea. It was also found that the compound is non-phasematchable and did not show any optical degradation for about an year when kept in ambient atmosphere.

  9. LiNbO3 ridge waveguides realized by precision dicing on silicon for high efficiency second harmonic generation

    CERN Document Server

    Chauvet, Mathieu; Bassignot, Florent; Devaux, Fabrice; Gauthier-Manuel, Ludovic; Pêcheur, Vincent; Maillotte, Hervé; Dahmani, Brahim

    2016-01-01

    Nonlinear periodically poled ridge LiNbO3 waveguides have been fabricated on silicon substrates. Components are carved with only use of a precision dicing machine without need for grinding or polishing steps. They show efficient second harmonic generation at telecommunication wavelengths with normalized conversion reaching 204%/W in a 15 mm long device. Influence of geometrical non uniformities of waveguides due to fabrication process is asserted. Components characteristics are studied notably their robustness and tunability versus temperature.

  10. Controlling second-harmonic generation at the nanoscale with monolithic AlGaAs-on-AlOx antennas

    Science.gov (United States)

    Carletti, L.; Rocco, D.; Locatelli, A.; De Angelis, C.; Gili, V. F.; Ravaro, M.; Favero, I.; Leo, G.; Finazzi, M.; Ghirardini, L.; Celebrano, M.; Marino, G.; Zayats, A. V.

    2017-03-01

    We review recent achievements in the field of nanoscale nonlinear AlGaAs photonics based on all-dielectric optical antennas. After discussing the motivation and main technological challenges for the development of an AlGaAs monolithic platform for χ (2) nonlinear nanophotonics, we present numerical and experimental investigations of the second-order nonlinear response and physical reasons for high efficiency of second-order nonlinear interactions in the AlGaAs nano-antennas. In particular, we emphasize the role of the dipolar resonances at the fundamental frequency and the multipolar resonances at the second harmonic wavelength. We also discuss second-harmonic generation directionality and show possible strategies to engineer the radiation pattern of nonlinear antennas.

  11. Phase matched second harmonic generation in an on-chip lithium niobate microresonator fabricated by femtosecond laser

    CERN Document Server

    Lin, Jintian; Ni, Jielei; Wang, Min; Fang, Zhiwei; Qiao, Lingling; Fang, Wei; Cheng, Ya

    2015-01-01

    Nonlinear optical processes in whispering gallery mode (WGM) microresonators have attracted much attention. Owing to the strong confinement of light in a small volume, a WGM microresonator can dramatically boost the strength of light field, thereby promoting the nonlinear interaction between the light and the resonator material. However, realization of efficient nonlinear parametric process in microresonators is a challenging issue. The major difficulty is to simultaneously ensure the phase matching condition and a coherent multiple resonance condition for all the waves participating in the nonlinear conversion process. Here, we demonstrate highly efficient second harmonic generation (SHG) in an on-chip lithium niobate microresonator fabricated by femtosecond laser direct writing. We overcome the difficulty of double resonance for the phase matched pump and second harmonic waves by selectively exciting high order modes in the fabricated thin-disk microresonator. Our technique opens opportunities for integrate...

  12. Second harmonic generation of q-Gaussian laser beam in preformed collisional plasma channel with nonlinear absorption

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Naveen, E-mail: naveens222@rediffmail.com; Singh, Arvinder, E-mail: arvinder6@lycos.com [Department of Physics, National Institute of Technology Jalandhar (India); Singh, Navpreet, E-mail: navpreet.nit@gmail.com [Guru Nanak Dev University College, Kapurthala, Punjab (India)

    2015-11-15

    This paper presents a scheme for second harmonic generation of an intense q-Gaussian laser beam in a preformed parabolic plasma channel, where collisional nonlinearity is operative with nonlinear absorption. Due to nonuniform irradiance of intensity along the wavefront of the laser beam, nonuniform Ohmic heating of plasma electrons takes place. Due to this nonuniform heating of plasma, the laser beam gets self-focused and produces strong density gradients in the transverse direction. The generated density gradients excite an electron plasma wave at pump frequency that interacts with the pump beam to produce its second harmonics. The formulation is based on a numerical solution of the nonlinear Schrodinger wave equation in WKB approximation followed by moment theory approach. A second order nonlinear differential equation governing the propagation dynamics of the laser beam with distance of propagation has been obtained and is solved numerically by Runge Kutta fourth order technique. The effect of nonlinear absorption on self-focusing of the laser beam and conversion efficiency of its second harmonics has been investigated.

  13. Surface second harmonic generation of chiral molecules using three-coupled-oscillator model

    Institute of Scientific and Technical Information of China (English)

    Wang Xiao-Ou; Li Chun-Fei; Li Jun-Qing

    2006-01-01

    Based on the three-coupled-oscillator molecular model we proposed, the relation between the second-order susceptibilities of a chiral film and the molecular hyperpolarizabilities is given. The effect of microscopic parameters on the second-order susceptibilities is simulated numerically and the difference between the efficiencies of s-polarized second-harmonic fields induced by the left- and the right-handed circularly-polarized fundamental beams is discussed. The theoretical basis for studying second-order nonlinear optical properties of the chiral molecular media with a tripod-like structure is provided in this paper.

  14. Second harmonic generation in a KNbO3 nanorod and its detection by using a near-field scanning optical microscope

    Science.gov (United States)

    Park, D. J.; Kang, P. G.; Jung, J. H.; Lee, H. H.; Choi, S. B.

    2016-04-01

    We report on an observation of second harmonic generation in an individual KNbO3 nanorod by using a near-field scanning optical microscope. The second harmonic is successfully generated by irradiating with a femtosecond laser having center wavelengths of 1200, 1100, and 972 nm. Such a second harmonic yield shows a clear dependence on the incident laser polarization, where maximum yield is obtained when the incident laser polarization is parallel to the long axis of an individual nanorod. A spatially-resolved second harmonic image shows a bright spot at the edge of the nanorod, which is attributed to the elaborated intensity of both fundamental laser light and second harmonic light inside the nanowire owing to cavity-mode formation.

  15. All-prism achromatic phase matching for tunable second-harmonic generation.

    Science.gov (United States)

    Richman, B A; Bisson, S E; Trebino, R; Sidick, E; Jacobson, A

    1999-05-20

    Achromatic phase matching (APM) involves dispersing the light entering a nonlinear optical crystal so that a wide range of wavelengths is simultaneously phase matched. We constructed an APM apparatus consisting of six prisms, the final dispersion angle of which was optimized to match to second order in wavelength the type I phase-matching angle of beta barium borate (BBO). With this apparatus, we doubled tunable fundamental light from 620 to 700 nm in wavelength using a 4-mm-long BBO crystal. An analogous set of six prisms after the BBO crystal, optimized to second order in second-harmonic wavelength, realigned the output second-harmonic beams. Computer simulations predict that adjustment of a single prism can compensate angular misalignment of any or all the prisms before the crystal, and similarly for the prisms after the crystal. We demonstrated such compensation with the experimental device. The simulations also indicate that the phase-matching wavelength band can be shifted and optimized for different crystal lengths.

  16. Plasmon-enhanced second harmonic generation in semiconductor quantum dots close to metal nanoparticles

    Directory of Open Access Journals (Sweden)

    Andrea V. Bragas

    2011-03-01

    Full Text Available We report the enhancement of the optical second harmonic signal in non-centrosymmetric semiconductor CdS quantum dots, when they are placed in close contact with isolated silver nanoparticles. The intensity enhancement is about 1000. We also show that the enhancement increases when the incoming laser frequency $omega$ is tuned toward the spectral position of the silver plasmon at $2omega$, proving that the silver nanoparticle modifies the nonlinear emission.Received: 8 March 2011, Accepted: 30 May 2011; Edited by: L. Viña; Reviewed by: R. Gordon, Department of Electrical and Computer Engineering, University of Victoria, British Columbia, Canada; DOI: 10.4279/PIP.030002Cite as: P. M. Jais, C. von Bilderling, A. V. Bragas, Papers in Physics 3, 030002 (2011

  17. Nuclear Wavepacket Dynamics of Alkali Adsorbates on Metal Surfaces Studied by Time-Resolved Second Harmonic Generation

    Directory of Open Access Journals (Sweden)

    Kazuya Watanabe

    2012-01-01

    Full Text Available This paper reviews recent efforts to understand the dynamics of coherent surface vibrations of alkali atoms adsorbed on metal surfaces. Time-resolved second harmonic generation is used for the coherent excitation and detection of the nuclear wavepacket dynamics of the surface modes. The principles of the measurement and the experimental details are described. The main focus is on coverage and excitation photon energy dependences of the coherent phonon dynamics for Na-, K-, and Cs-covered Cu(111. The excitation mechanism of the coherent phonon has been revealed by the ultrafast time-domain technique and theoretical modelings.

  18. Addressable, large-field second harmonic generation microscopy based on 2D acousto-optical deflector and spatial light modulator.

    Science.gov (United States)

    Shao, Yonghong; Liu, Honghai; Qin, Wan; Qu, Junle; Peng, Xiang; Niu, Hanben; Gao, Bruce Z

    2012-09-01

    We present an addressable, large-field second harmonic generation microscope by combining a 2D acousto-optical deflector with a spatial light modulator. The SLM shapes an incoming mode-locked, near-infrared Ti:Sapphire laser beam into a multifocus array, which can be rapidly scanned by changing the incident angle of the laser beam using a 2D acousto-optical deflector. Compared to the single-beam-scan technique, the multifocus array scan can increase the scanning rate and the field-of-view size with the multi-region imaging ability.

  19. Direct observation of bulk second-harmonic generation inside a glass slide with tightly focused optical fields

    Science.gov (United States)

    Wang, Xianghui; Fardad, Shima; Das, Susobhan; Salandrino, Alessandro; Hui, Rongqing

    2016-04-01

    Bulk second-harmonic generation (SHG) inside glass slides is directly detected unambiguously without interference from surface contributions. This is enabled by tightly focused and highly localized ultrashort laser pulses. The theoretical calculations based on vector diffraction theory and the phenomenological model of SHG inside centrosymmetric materials agree well with the measured far-field SHG radiation patterns for different polarization states of the fundamental beam. The results indicate that the observed bulk SHG is predominantly related to the bulk parameter δ' and originates from the three-dimensional field gradient in the focal region.

  20. Absorption, fluorescence and second harmonic generation in Cr3+-doped BiB3O6 glasses

    Science.gov (United States)

    Kuznik, W.; Fuks-Janczarek, I.; Wojciechowski, A.; Kityk, I. V.; Kiisk, V.; Majchrowski, A.; Jaroszewicz, L. R.; Brik, M. G.; Nagy, G. U. L.

    2015-06-01

    Synthesis, spectral properties and photoinduced nonlinear optical effects of chromium-doped BiB3O6 glass are studied in the present paper. Absorption, excitation and time resolved luminescence spectra are presented and luminescence decay behavior is discussed. Detailed analysis of the obtained spectra (assignment of the most prominent spectral features in terms of the corresponding Cr3+ energy levels, crystal field strength Dq, Racah parameters B and C) was performed. A weak photostimulated second harmonic generation signal was found to increase drastically due to poling by proton implantation in the investigated sample.

  1. Femtosecond-Laser-Inscribed BiB3O6 Nonlinear Cladding Waveguide for Second-Harmonic Generation

    Science.gov (United States)

    Jia, Yuechen; Vázquez de Aldana, Javier R.; Romero, Carolina; Ren, Yingying; Lu, Qingming; Chen, Feng

    2012-07-01

    We report on the fabrication of a nonlinear cladding waveguide in BiB3O6 crystal by using femtosecond laser inscription. The waveguide (with a nearly circular cross section of 150 µm diameter) shows good guiding properties in two transverse polarizations. The guided-wave second-harmonic generation (SHG) at 532 nm green light has been realized under CW and pulsed wave pump at 1064 nm, based on the Type I birefringent phase matching configuration. The conversion efficiencies for CW and pulsed green laser SHG are 0.083 and 25%, respectively.

  2. First and second harmonic generation of the XAl2Se4 (X=Zn,Cd,Hg) defect chalcopyrite compounds

    OpenAIRE

    Ouahrani, Tank; Khenata, R.; Lasri, B; Reshak, Ali H.; Bouhemadou, A.; Bin-Omran, S

    2012-01-01

    The chemical bonding of the ZnAl2Se4, CdAl2Se4 and HgAl2Se4 defect chalcopyrites has been studied in the framework of the quantum theory of atoms in molecules (AIM). The GW quasi-particle approximation is used to correct the DFT-underestimation of energy gap, and as a consequence the linear and nonlinear optical properties are significantly enhanced. The second harmonic generation (SHG) displays certain dependence with the ionicity degree decrease through the dependency of the SHG on the band...

  3. Decrimping: The first stage of collagen thermal denaturation unraveled by in situ second-harmonic-generation imaging

    Science.gov (United States)

    Liao, Chien-Sheng; Zhuo, Zong-Yan; Yu, Jiun-Yann; Tzeng, Yu-Yi; Chu, Shi-Wei; Yu, Shih-Fan; Chao, Pen-Hsiu Grace

    2011-04-01

    With polarized and time-lapsed second-harmonic-generation (SHG) imaging, three distinct thermodynamic stages are revealed during heating of collagenous tissue. In the first "decrimping" stage, SHG intensity remains unchanged while the characteristic crimp pattern of collagen fiber disappears. The intactness of underlying fibrils is confirmed by unaffected second-order susceptibility, suggesting decrimping is related to the breakage of cross-linking between collagen fibrils. In the latter stages, significant SHG decrease is observed, providing quantification to collagen thermal denaturation. This study manifests the benefits of adopting SHG for understanding the thermal response of collagen, and will be useful toward better thermal therapy design.

  4. Second harmonic generation from corona-poled polymer thin films of Y-shape chromophore with different isolation groups

    Indian Academy of Sciences (India)

    Mukesh P Joshi; S Raj Mohan; Balakrishna Kolli; Sarada P Mishra; Akshaya K Palai; Tapan Kanai; T S Dhami; L M Kukreja; A B Samui

    2014-02-01

    We characterize thermal stability of second harmonic generation (SHG) properties of four different Y-type polymers poled using corona poling method. These polymers are based on donor–acceptor–donor-type repeating unit with different aromatic moieties acting as donors and dicyanomethylene acting as an acceptor through conjugated bridge. The donor varies from different substituted benzene to phenothiazine. Polymer containing phenothiazine as donor showed higher SHG intensity and high temperature stability due to rigid repeating unit of phenothiazine compared to others with benzene in the main chain.

  5. Direct measurement of wave-front distortion induced during second-harmonic generation: application to breakup-integral compensation.

    Science.gov (United States)

    Caumes, Jean Pascal; Videau, Laurent; Rouyer, Claude; Freysz, Eric

    2004-04-15

    The wave-front distortion of femtosecond laser pulses recorded with a Shack-Hartmann analyzer makes it possible to retrieve the nonlinear index of refraction of different glasses and the nonlinear phase shift induced during second-harmonic generation in beta-barium borate (BBO) crystal versus the phase mismatch. It is shown that the nonlinear phase shift induced in a 2-mm-thick BBO crystal allows compensation for up to a 2pi breakup-integral induced in a 4-cm fused-silica glass. The stability of the compensation is reported to be from 10 to 100 GW cm(-2).

  6. Wave-front phase-modulation control and focusing of second-harmonic light generated in transparent nonlinear random structures

    Science.gov (United States)

    Yao, Can; Rodriguez, Francisco J.; Bravo-Abad, Jorge; Martorell, Jordi

    2013-06-01

    We theoretically investigate how phase-only spatial light modulation can enable controlling and focusing the second-harmonic light generated in transparent nonlinear random structures. The studied structures are composed of domains with random sizes and antiparallel polarization, which accurately model widely used ferroelectric crystals such as strontium barium niobate. Using a first-principles Green-function formalism, we account for the effect that spatial light modulation of the fundamental beam introduces into the second-order nonlinear frequency conversion occurring in the considered class of structures. This approach provides a complete description of the physical origin of the second-harmonic light generation in the system, as well as the optimization of the light intensity in any arbitrary direction. Our numerical results show how the second-harmonic light is influenced by both the disorder in the structure and the boundaries of the crystal. Particularly, we find that the net result from the interplay between disorder and boundary effects is strongly dependent on the dimensions of the crystal and the observation direction. Remarkably, our calculations also show that although in general the maximum possible enhancement of the second-order light is the same as the one corresponding to linear light scattering in turbid media, in the Cerenkov phase matching direction the enhancement can exceed the linear limit. The theoretical analysis presented in this work expands the current understanding of light control in complex media and could contribute to the development of a new class of imaging and focusing techniques based on nonlinear frequency mixing in random optical materials.

  7. Diffusion voltage in polymer light emitting diodes measured with electric field induced second harmonic generation

    Energy Technology Data Exchange (ETDEWEB)

    Kristensen, P.K.; Rafaelsen, J.; Pedersen, T.G.; Pedersen, K. [Department of Physics and Nanotechnology, Aalborg University, Pontoppidanstraede 103, 9220 Aalborg East (Denmark)

    2005-12-01

    We apply electric field induced second harmonic (EFISH) to polymer light emitting diodes (PLEDs) and demonstrate the ability to determine the diffusion voltage in PLED devices. The EFISH signal is proportional to the square of the effective field, which is the sum of the diffusion voltage and the applied voltage. By minimizing the EFISH-signal as a function of the applied voltage, the diffusion voltage is determined by measuring the applied voltage that cancels out the diffusion voltage. The PLEDs are fabricated with indium tin oxide (ITO) as the hole injecting contact and two different electron injecting contacts, namely aluminum and calcium. The diffusion voltage originates from the rearranged charges caused by the difference in Fermi levels in the materials in the PLEDs. Different contacts will thus cause different diffusion voltages. We demonstrate here that the EFISH signal is proportional to the square of the effective field in both reverse and forward bias, and discuss the dependence on contact materials. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Inspecting the surface of implanted Si(111) during annealing by reflective second harmonic generation: The influence of chamber pressure

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chung-Wei; Chang, Shoou-Jinn [Institute of Microelectronics and Department of Electrical Engineering and Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 701, Taiwan (China); Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 701, Taiwan (China); Liu, Chun-Chu [Department of Electrophysics, National Chia Yi University, Chia Yi 600, Taiwan (China); Lo, Kuang-Yao, E-mail: kuanglo@mail.ncyu.edu.tw [Department of Electrophysics, National Chia Yi University, Chia Yi 600, Taiwan (China); Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 701, Taiwan (China)

    2013-02-01

    The present study used the reflective second harmonic generation (RSHG) method to analyze the quality of the surface layer of implanted Si(111) and to discuss the influence of chamber pressure during rapid thermal annealing. Under a lower chamber pressure, the recrystallization is better, and the defects are eliminated for a higher implanted dose because dopant phosphorus (P) atoms on the surface region more easily out-diffuse at lower chamber pressures. Thus, the occurrence of less out-diffusion makes more P atoms remain on the surface layer and causes larger defects, especially for higher implanted doses. Defects on the surface region are influenced by chamber pressure. In the current work, the RSHG results showed more detailed information by linking secondary ion mass spectrometry and sheet resistance measurement. - Highlights: ► Rapid thermal annealing (RTA) with different chamber pressures was performed. ► The quality of implanted Si was analyzed by reflective second harmonic generation. ► High-dose implanted Si is obviously influenced by the pressure in the RTA chamber. ► Pressure in the RTA chamber affects the generation of defects. ► Defect suppression is obvious at relatively low chamber pressure.

  9. Plasmonic enhancement of second harmonic generation from nonlinear RbTiOPO4 crystals by aggregates of silver nanostructures

    DEFF Research Database (Denmark)

    Sánchez-García, Laura; Tserkezis, Christos; Ramírez, Mariola O;

    2016-01-01

    We demonstrate a 60–fold enhancement of the second harmonic generation (SHG) response at the nanoscale in a hybrid metal-dielectric system. By using complex silver nanostructures photochemically deposited on the polar surface of a ferroelectric crystal, we tune the plasmonic resonances from the v...... the potential of aggregates of silver nanostructures for enhancing optical nonlinearities at the nanoscale and provides an alternative approach for the development of nanometric nonlinear photonic devices in a scalable way.......We demonstrate a 60–fold enhancement of the second harmonic generation (SHG) response at the nanoscale in a hybrid metal-dielectric system. By using complex silver nanostructures photochemically deposited on the polar surface of a ferroelectric crystal, we tune the plasmonic resonances from...... or up to 60 times when it matches the fundamental NIR radiation. The results are consistent with the more spatially-extended near-field response of complex metallic nanostructures and can be well explained by taking into account the quadratic character of the SHG process. The work points out...

  10. Thermally induced dephasing of high power second harmonic generation in MgO: LiNbO3 waveguides

    Institute of Scientific and Technical Information of China (English)

    Guohui Li; Xinye Xu

    2011-01-01

    High power second harmonic generation (SHG) in MgO-doped LiNbO3 waveguides is investigated using a three-dimensional (3D) coupled thermo-optical model. Simulations performed for a 1111.6-nm fundamental laser show the influence of the absorptions and the thermally induced dephasing on the conversion efficiencies of the different waveguides. The onset of the thermally induced dephasing effect for each waveguide is also indicated. As a result of high light intensity in the waveguide, nonlinear absorptions are identified as the possible main factors in efficiency losses in specific cases.%High power second harmonic generation (SHG) in MgO-doped LiNbO3 waveguides is investigated using a three-dimensional (3D) coupled thermo-optical model.Simulations performed for a 1111.6-nm fundamental laser show the influence of the absorptions and the thermally induced dephasing on the conversion efficiencies of the different waveguides.The onset of the thermally induced dephasing effect for each waveguide is also indicated.As a result of high light intensity in the waveguide,nonlinear absorptions are identified as the possible main factors in efficiency losses in specific cases.

  11. Volume electric dipole origin of second-harmonic generation from metallic membrane with non-centrosymmetry patterns

    CERN Document Server

    Zeng, Yong

    2009-01-01

    In this article, we analytically study second harmonic (SH) generation from thin metallic films with subwavelength, non-centrosymmetry patterns. Because the thickness of the film is much smaller than the SH wavelength, retardation effects are negligible. The far-field SH intensities are thus dominated by an effective electric dipole. These analytical observations are further justified numerically by studying the effect of polarization of the fundamental field on both the SH signal and the electric dipole. It is demonstrated that bulk SH polarization density is comparable with its surface counterpart. The electric dipole, consequently, originates from the entire {volume of the metallic membrane, in contrast to the fact that SH generation from metal surface is generally dominated by a surface dipole.

  12. Using Second Harmonic Generation Microscopy to Study the Three-Dimensional Structure of Collagen and its Degradation Mechanism

    Science.gov (United States)

    Mega, Yair

    Collagen is one of the most abundant proteins found in the human body. Its crystalline structure possesses no centrosymmetry, allowing it to emit second-harmonic waves. Second harmonic generation (SHG) microscopy utilizes the latter quality to produce high-resolution images of collagen rich tissues and therefore become a key research tool in the biomedical field. We developed a new model, intended to be used together with second harmonic generation (SHG) microscopy, to thoroughly investigate collagen-based tissues. We use our SHG model to reveal information in real time from enzymatic biochemical processes. We also present a novel method used to measure quantitatively the direction of the fibers within the tissue, from SHG images. Using this method, we were able to reconstruct an angular map of the orientation of collagen fibers from multiple sections across the entire area of a human cornea. The structure we obtained demonstrates the criss-crossing structure of the human cornea, previously suggested in the literature. In addition, we also report work on a unique step-wise three-photon fluorescence excitation discovered in melanin. This unique fluorescence mechanism was exploited to discriminate melanin on a small-size, low-cost and low laser power setup which was used as a prototype for a handheld device. The latter study is a part of a larger on-going effort in our group to explore new diagnosis methods to be used for early skin cancer screening. Finally, this work demonstrates a spectroscopy-based method to correct for blood vessel thickness effect. The method analyzes spectral shift from a molecular imaging agent and correlate the shifts to the length of the optical path in blood. The correction method described in this work is intended to be implemented on a guided catheter near infrared fluorescence (NIRF) intra-vascular imaging system. In this imaging system, this study's results will used to correct for the radial distance between the imaging tip of the

  13. Negative charge and charging dynamics in Al2O3 films on Si characterized by second-harmonic generation

    Science.gov (United States)

    Gielis, J. J. H.; Hoex, B.; van de Sanden, M. C. M.; Kessels, W. M. M.

    2008-10-01

    Thin films of Al2O3 synthesized by atomic layer deposition provide an excellent level of interface passivation of crystalline silicon (c-Si) after a postdeposition anneal. The Al2O3 passivation mechanism has been elucidated by contactless characterization of c-Si/Al2O3 interfaces by optical second-harmonic generation (SHG). SHG has revealed a negative fixed charge density in as-deposited Al2O3 on the order of 1011 cm-2 that increased to 1012-1013 cm-2 upon anneal, causing effective field-effect passivation. In addition, multiple photon induced charge trapping dynamics suggest a reduction in recombination channels after anneal and indicate a c-Si/Al2O3 conduction band offset of 2.02±0.04 eV.

  14. Second harmonic generation at the interface of copper tetra-tert-butyl phthalocyanine Langmuir-Blodgett film/metal

    Institute of Scientific and Technical Information of China (English)

    程晓曼; 姚素薇; 李成全; 间中孝彰; 岩本光正

    2003-01-01

    Optical second harmonic generation (SHG) from the copper tetra-tert-butyl phthalocyanine (CuttbPc) Langmuir-Blodgett (LB) film deposited on a metal-coated glass slide substrate has been investigated. It is considered that the symmetry of the CuttbPc molecule may be broken by the space charge-induced electric field (SCIEF) due to the exchanged charges at the CuttbPc LB film/metal interface. A four-layer model is used to explain the nonlinear optical process in the CuttbPc LB film. The thickness dependence, polarized and incident angle dependence of SHG signal from CuttbPc LB films are calculated. The results of calculation show a good agreement with the experimental data. It is shown that electrostatic phenomena at the interface is correlated closely with SHG signal, and the SHG measurement is also a helpful tool for the detection of the space charge field at the interface.

  15. Second-harmonic generation in quaternary atomically thin layered AgInP2S6 crystals

    Science.gov (United States)

    Wang, Xingzhi; Du, Kezhao; Liu, Weiwei; Hu, Peng; Lu, Xin; Xu, Weigao; Kloc, Christian; Xiong, Qihua

    2016-09-01

    Nonlinear effects in two-dimensional (2D) atomic layered materials have attracted increasing interest. Here, we report the observation of optical second-harmonic generation (SHG) in two-dimensional atomically thin silver indium phosphorus sulfide (AgInP2S6) crystals, with odd layer thickness. The nonlinear signal facilitates the use of thickness-dependent SHG intensity to investigate the stacking type of this material, while the crystal-orientation dependent SHG intensity of the monolayer sample reveals the rotational symmetry of the AgInP2S6 lattice in plane. Our studies expand the 2D crystal family in nonlinear effect field, which opened considerable promise to the functionalities and potential applications of 2D materials.

  16. Surface behaviour and undercooling in the liquid Ga-Bi binary system detected by optical second harmonic generation

    Institute of Scientific and Technical Information of China (English)

    王聪; 王天民

    2003-01-01

    We employ an optical second harmonic generation(SHG) technique to investigate the surfeace behaviours at the liquid(solid)/vapour interface of the Ga-Bi binary metallic system. In a heating and cooling cycle between 280℃ and room temperature, there is no change of the SH-intensity in the heating process, whereas there exists an abrupt and abnormal change of the SH-intensity in the cooling process. It is interesting to find that a macroscopic Bi-rich solid layer is floating on the surface of the Ga-rich liquid phase just below the monotectic temperature (222℃±2℃) in the cooling process, in spite of the Bi-rich phase being heavier than the Ga-rich phase. On the other hand, different undercooling behaviours are observed at the surface and in the bulk. The behaviours of surface solidification and surface melting are different from those in the bulk.

  17. Second harmonic generation via femtosecond laser fabrication of poled, quasi-phase-matched waveguides in fused silica.

    Science.gov (United States)

    Ng, Jason C; Herman, Peter R; Qian, Li

    2017-01-15

    Second harmonic generation (SHG) is demonstrated in femtosecond laser written waveguides in fused silica through a combination of thermal poling and laser-based quasi-phase-matching (QPM) techniques. Quasi-phase-matching was controlled by the periodic erasure of induced nonlinearity through femtosecond laser erasure. A maximum SHG conversion efficiency of 6.6±0.5×10-5%/W is reported for the fundamental wavelength of 1552.8 nm with a phase-matching bandwidth of 4.4 nm for a 10.0 mm long waveguide. For a shorter sample, an effective second-order nonlinearity of χ(2)=0.012±0.001  pm/V was measured. Chirped QPM structures for wider SHG bandwidths also were demonstrated. Such periodically poled waveguides are promising for introducing nonlinear optical components within the 3D passive optical circuits that can be flexibly formed in fused silica by femtosecond laser writing.

  18. On second harmonic generation and multiphoton-absorption induced luminescence from laser-reshaped silver nanoparticles embedded in glass

    Science.gov (United States)

    Zolotovskaya, S. A.; Tyrk, M. A.; Stalmashonak, A.; Gillespie, W. A.; Abdolvand, A.

    2016-10-01

    Spherical silver nanoparticles (NPs) of 30 nm diameter embedded in soda-lime glass were uniformly reshaped (elongated) after irradiation by a linearly polarised 250 fs pulsed laser operating within the NPs’ surface plasmon resonance band. We observed second harmonic generation (SHG) and multiphoton-absorption-induced luminescence (MAIL) in the embedded laser-reshaped NPs upon picosecond (10 ps) pulsed laser excitation at 1064 nm. A complementary study of SHG and MAIL was conducted in soda-lime glass containing embedded, mechanically-reshaped silver NPs of a similar elongation ratio (aspect ratio) to the laser-reshaped NPs. This supports the notion that the observed difference in SHG and MAIL in the studied nanocomposite systems is due to the shape modification mechanism. The discrete dipole approximation method was used to assess the absorption and scattering cross-sections of the reshaped NPs with different elongation ratios.

  19. Monitoring the effect of low-level laser therapy in healing process of skin with second harmonic generation imaging techniques

    Science.gov (United States)

    Zhang, Xiaoman; Yu, Biying; Weng, Cuncheng; Li, Hui

    2014-11-01

    The 632nm wavelength low intensity He-Ne laser was used to irradiated on 15 mice which had skin wound. The dynamic changes and wound healing processes were observed with nonlinear spectral imaging technology. We observed that:(1)The wound healing process was accelerated by the low-level laser therapy(LLLT);(2)The new tissues produced second harmonic generation (SHG) signals. Collagen content and microstructure differed dramatically at different time pointed along the wound healing. Our observation shows that the low intensity He-Ne laser irradiation can accelerate the healing process of skin wound in mice, and SHG imaging technique can be used to observe wound healing process, which is useful for quantitative characterization of wound status during wound healing process.

  20. Second harmonic generation in NLO polymers excited by Surface Plasmon enhanced electric field induced by femtosecond optical pulses

    Directory of Open Access Journals (Sweden)

    Kawata Y.

    2013-03-01

    Full Text Available We will report second harmonic generation (SHG in nonlinear optical (NLO polymers excited by surface plasmon enhanced optical fields. The surface plasmon (SP polariton was excited in an attenuated total reflection geometry having the Kretchmann configuration. The NLO polymers, consisting of Disperse Red1 as guest chromophores and poly (methyl methacrylate as host materials, were coated upon the Ag layers. Our experimental results indicated that the SHG signal intensity from the polymer coated Ag films was more than 10 times higher than that from the non-coated Ag films. The SHG autocorrelation traces excited by SP-enhanced fields were also studied and the correlation time was shorter than 150 fs, the temporal resolutions of the present spectrometer.

  1. Enhancement of second harmonic generation in NaNO2-infiltrated opal photonic crystal using structural light focusing

    Science.gov (United States)

    Zaytsev, Kirill I.; Yurchenko, Stanislav O.

    2014-08-01

    Experimental and numerical results for second harmonic generation (SHG) in photonic crystal (PC) based on NaNO2-infiltrated opal matrix are presented. SHG is performed in reflection mode; thus, the direction of the SHG maximum is equal to the angle of mirror reflection. The PC was pumped with femtosecond optical pulses at different angles of incidence, allowing the dependence of the SHG efficiency on the location of the fundamental wavelength toward the PC band gap (BG) to be examined. The most efficient SHG was observed when pumping the BG of the PC. To interpret the experimental results, finite-difference time-domain numerical simulations of the light interaction with the PC were conducted. The observed effect of highly efficient SHG is associated with structural light focusing, and, as a consequence, with strong optical field localization within certain near-surface PC regions. Thus, SHG enhancement based on structural light focusing in PC was demonstrated.

  2. Boron induced charge traps near the interface of Si/SiO{sub 2} probed by second harmonic generation

    Energy Technology Data Exchange (ETDEWEB)

    Park, Heungman; Varga, Kalman; Tolk, Norman [Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States); Qi, Jingbo [Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States); National High Magnetic Field Laboratory, Tallahassee, Florida 32310 (United States); Xu, Ying [Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States); Zomega Terahertz Corporation, Troy, New York 12180 (United States); Weiss, Sharon M. [Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States); Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, Tennessee 37235 (United States); Rogers, Bridget R. [Department of Chemical and Biomolecular Engineering, Nashville, Vanderbilt University, Tennessee 37235 (United States); Luepke, Gunter [Department of Applied Science, College of William and Mary, Williamsburg, Virginia 23187 (United States)

    2010-08-15

    We review recent second harmonic generation (SHG) measurements for highly boron-doped Si/SiO{sub 2} systems. Using electric field sensitive time-dependent SHG (TD-SHG), we determined that the direction of the initial DC electric field at the interface induced by boron induced charge traps is from oxide to silicon thus demonstrating that the boron induced charge traps in the oxide are positively charged. For a thin oxide ({proportional_to}2 nm) both boron traps and O{sub 2} surface oxide traps contribute. However, for a highly boron-doped Si/SiO{sub 2} sample with a thick thermally grown oxide (thickness: 12 nm), the TD-SHG signal exhibits a monotonic decrease arising from filling only the boron charge traps. By fitting our data, we show that the interface effective susceptibility vertical stroke {chi}{sup (2)} vertical stroke is heavily dependent on doping concentration. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  3. Fabrication of Ion-Shaped Anisotropic Nanoparticles and their Orientational Imaging by Second-Harmonic Generation Microscopy

    Science.gov (United States)

    Slablab, Abdallah; Isotalo, Tero J.; Mäkitalo, Jouni; Turquet, Léo; Coulon, Pierre-Eugène; Niemi, Tapio; Ulysse, Christian; Kociak, Mathieu; Mailly, Dominique; Rizza, Giancarlo; Kauranen, Martti

    2016-11-01

    Ion beam shaping is a novel and powerful tool to engineer nanocomposites with effective three-dimensional (3D) architectures. In particular, this technique offers the possibility to precisely control the size, shape and 3D orientation of metallic nanoparticles at the nanometer scale while keeping the particle volume constant. Here, we use swift heavy ions of xenon for irradiation in order to successfully fabricate nanocomposites consisting of anisotropic gold nanoparticle that are oriented in 3D and embedded in silica matrix. Furthermore, we investigate individual nanorods using a nonlinear optical microscope based on second-harmonic generation (SHG). A tightly focused linearly or radially-polarized laser beam is used to excite nanorods with different orientations. We demonstrate high sensitivity of the SHG response for these polarizations to the orientation of the nanorods. The SHG measurements are in excellent agreement with the results of numerical modeling based on the boundary element method.

  4. Observation of two polytypes of MoS2 ultrathin layers studied by second harmonic generation microscopy and photoluminescence

    Science.gov (United States)

    Mishina, E.; Sherstyuk, N.; Lavrov, S.; Sigov, A.; Mitioglu, A.; Anghel, S.; Kulyuk, L.

    2015-03-01

    Second harmonic generation (SHG) of a high intensity was found in MoS2 flakes of different thicknesses exfoliated on a silicon substrate. Reduction of the SHG intensity was observed only for a small portion of flakes, for both very thin and quite thick ones. This was attributed to the presence of polytypism, i.e., of 3R non-centrosymmetric and 2H centrosymmetric polytypes, in a source bulk crystal grown by the chemical vapor transport technique. The presence of two polytypes in the sample was confirmed by the spectral structure of the photoluminescence of bound excitons observed in flakes at low temperature. Absolute values of nonlinear susceptibility of MoS2 flakes of different thicknesses were estimated.

  5. Phase-Matched Second-Harmonic Generation in an On-Chip Li NbO 3 Microresonator

    Science.gov (United States)

    Lin, Jintian; Xu, Yingxin; Ni, Jielei; Wang, Min; Fang, Zhiwei; Qiao, Lingling; Fang, Wei; Cheng, Ya

    2016-07-01

    The realization of an efficient nonlinear parametric process in microresonators is a challenging issue largely because of an inherent difficulty in simultaneously ensuring the phase-matching condition and a coherent multiple-resonance condition for all the waves participating in the nonlinear conversion process. Here, we demonstrate highly efficient second-harmonic generation in an on-chip LiNbO3 microresonator fabricated by femtosecond-laser direct writing. We overcome the above difficulty by selectively exciting high-order modes in the fabricated thin-disk microresonator. Thanks to the low optical absorption and high nonlinear optical coefficient of LiNbO3 crystal, we achieve a normalized conversion efficiency of 1.106 ×10-3/mW in the on-chip LiNbO3 microdisk with a diameter of approximately 102 μ m .

  6. Second harmonic generation and two-photon luminescence upconversion in glasses doped with ZnSe nanocrystalline quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Thantu, Napoleon [Idaho National Engineering and Environmental Laboratory, 2525 Fremont Avenue, Idaho Falls, ID 83415 (United States)]. E-mail: Napoleon.Thantu@ngc.com

    2005-01-01

    We report two-photon excited emission in borosilicate glasses doped with ZnSe nanocrystalline quantum dots. The emission, predominantly near the two-photon energy and detected in the direction of the excitation beam, is in the visible, and the fundamental excitation is the near-infrared output of a tunable femtosecond laser. Depending on the two-photon energy, time- and frequency-resolved measurements at room temperature reveal that the emission largely consists of second harmonic generation (SHG) and two-photon luminescence upconversion, and a much smaller luminescence from redshifted, low-lying trap states and other trap levels residing near the semiconductor band edge. We discuss the SHG origin in terms of bulk-like and surface contributions from the nanocrystals and the two-photon resonant enhancement near the excitonic absorption.

  7. Enhancement of second harmonic generation in NaNO{sub 2}-infiltrated opal photonic crystal using structural light focusing

    Energy Technology Data Exchange (ETDEWEB)

    Zaytsev, Kirill I., E-mail: kirzay@gmail.com; Yurchenko, Stanislav O., E-mail: st.yurchenko@mail.ru [Bauman Moscow State Technical University, 105005, 2nd Baumanskaya str. 5, Moscow (Russian Federation)

    2014-08-04

    Experimental and numerical results for second harmonic generation (SHG) in photonic crystal (PC) based on NaNO{sub 2}-infiltrated opal matrix are presented. SHG is performed in reflection mode; thus, the direction of the SHG maximum is equal to the angle of mirror reflection. The PC was pumped with femtosecond optical pulses at different angles of incidence, allowing the dependence of the SHG efficiency on the location of the fundamental wavelength toward the PC band gap (BG) to be examined. The most efficient SHG was observed when pumping the BG of the PC. To interpret the experimental results, finite-difference time-domain numerical simulations of the light interaction with the PC were conducted. The observed effect of highly efficient SHG is associated with structural light focusing, and, as a consequence, with strong optical field localization within certain near-surface PC regions. Thus, SHG enhancement based on structural light focusing in PC was demonstrated.

  8. Microscopic imaging of glyceraldehyde-induced tissue glycation with intrinsic second harmonic generation and two-photon fluorescence contrasts

    Science.gov (United States)

    Hwang, Yu Jer; Granelli, Joseph; Tirumalasetty, Manasa; Lyubovitsky, Julia

    2013-02-01

    The bioinspired approaches to tissue strengthening and preservation rely on non-toxic cross-linking agents one of which is glyceraldehyde. In this study we used multiphoton microscopy that employs second harmonic generation (SHG) contrast to evaluate collagen microstructures and two-photon fluorescence (TPF) contrast to monitor progression of cross-linking upon treatment of tissues with glyceraldehyde. We examined collagen hydrogels assembled at 37 °C and 27 °C, bovine scleral and corneal tissues, skin as well as rat tail tendons. The results show a different effect of glyceraldehyde on collagen microstructures within the above tissues. This effect depends on the original microstructural assembly of collagen within a specific tissue. Our data suggests that epidermis (in skin and cornea) will protect collagen from cross-linking with glyceraldehyde. The work highlights benefits of monitoring progression of collagen cross-linking and effects of cross-linking on fiber microstructures as imaged with SHG and TPF signals.

  9. Second-harmonic generation in periodically-poled thin film lithium niobate wafer-bonded on silicon

    CERN Document Server

    Rao, Ashutosh; Honardoost, Amirmahdi; Talukder, Javed Rouf; Rabiei, Rayam; Delfyett, Peter; Fathpour, Sasan

    2016-01-01

    Second-order optical nonlinear effects (second-harmonic and sum-frequency generation) are demonstrated in the telecommunication band by periodic poling of thin films of lithium niobate wafer-bonded on silicon substrates and rib-loaded with silicon nitride channels to attain ridge waveguide with cross-sections of ~ 2 {\\mu}m2. The compactness of the waveguides results in efficient second-order nonlinear devices. A nonlinear conversion of 8% is obtained with a pulsed input in 4 mm long waveguides. The choice of silicon substrate makes the platform potentially compatible with silicon photonics, and therefore may pave the path towards on-chip nonlinear and quantum-optic applications.

  10. On second harmonic generation and multiphoton-absorption induced luminescence from laser-reshaped silver nanoparticles embedded in glass.

    Science.gov (United States)

    Zolotovskaya, S A; Tyrk, M A; Stalmashonak, A; Gillespie, W A; Abdolvand, A

    2016-10-28

    Spherical silver nanoparticles (NPs) of 30 nm diameter embedded in soda-lime glass were uniformly reshaped (elongated) after irradiation by a linearly polarised 250 fs pulsed laser operating within the NPs' surface plasmon resonance band. We observed second harmonic generation (SHG) and multiphoton-absorption-induced luminescence (MAIL) in the embedded laser-reshaped NPs upon picosecond (10 ps) pulsed laser excitation at 1064 nm. A complementary study of SHG and MAIL was conducted in soda-lime glass containing embedded, mechanically-reshaped silver NPs of a similar elongation ratio (aspect ratio) to the laser-reshaped NPs. This supports the notion that the observed difference in SHG and MAIL in the studied nanocomposite systems is due to the shape modification mechanism. The discrete dipole approximation method was used to assess the absorption and scattering cross-sections of the reshaped NPs with different elongation ratios.

  11. Polarization dependant in vivo second harmonic generation imaging of Caenorhabditis elegans vulval, pharynx, and body wall muscles

    Science.gov (United States)

    Psilodimitrakopoulos, Sotiris; Santos, Susana; Amat-Roldan, Ivan; Mathew, Manoj; Thayil K. N., Anisha; Artigas, David; Loza-Alvarez, Pablo

    2008-02-01

    Second harmonic generation (SHG) imaging has emerged in recent years as an important laboratory imaging technique since it can provide unique structural information with submicron resolution. It enjoys the benefits of non-invasive interaction establishing this imaging modality as ideal for in vivo investigation of tissue architectures. In this study we present, polarization dependant high resolution SHG images of Caenorhabditis elegans muscles in vivo. We imaged a variety of muscular structures such as body walls, pharynx and vulva. By fitting the experimental data into a cylindrical symmetry spatial model we mapped the corresponding signal distribution of the χ (2) tensor and identified its main axis orientation for different sarcomeres of the earth worm. The cylindrical symmetry was considered to arise from the thick filaments architecture of the inside active volume. Moreover, our theoretical analysis allowed calculating the mean orientation of harmonophores (myosin helical pitch). Ultimately, we recorded and analysed vulvae muscle dynamics, where SHG signal decreased during in vivo contraction.

  12. Enhanced optical second-harmonic generation from the current-biased graphene/SiO2/Si(001) structure.

    Science.gov (United States)

    An, Yong Q; Nelson, Florence; Lee, Ji Ung; Diebold, Alain C

    2013-05-08

    We find that optical second-harmonic generation (SHG) in reflection from a chemical-vapor-deposition graphene monolayer transferred onto a SiO2/Si(001) substrate is enhanced about 3 times by the flow of direct current electric current in graphene. Measurements of rotational-anisotropy SHG revealed that the current-induced SHG from the current-biased graphene/SiO2/Si(001) structure undergoes a phase inversion as the measurement location on graphene is shifted laterally along the current flow direction. The enhancement is due to current-associated charge trapping at the graphene/SiO2 interface, which introduces a vertical electric field across the SiO2/Si interface that produces electric field-induced SHG. The phase inversion is due to the positive-to-negative polarity switch in the current direction of the trapped charges at the current-biased graphene/SiO2 interface.

  13. Pb2 BO3 Cl: A Tailor-Made Polar Lead Borate Chloride with Very Strong Second Harmonic Generation.

    Science.gov (United States)

    Zou, Guohong; Lin, Chensheng; Jo, Hongil; Nam, Gnu; You, Tae-Soo; Ok, Kang Min

    2016-09-19

    A meticulously designed, polar, non-centrosymmetric lead borate chloride, Pb2 BO3 Cl, was synthesized using KBe2 BO3 F2 (KBBF) as a model. Single-crystal X-ray diffraction revealed that the structure of Pb2 BO3 Cl consists of cationic [Pb2 (BO3 )](+) honeycomb layers and Cl(-) anions. Powder second harmonic generation (SHG) measurements on graded polycrystalline Pb2 BO3 Cl indicated that the title compound is phase-matchable (type I) and exhibits a remarkably strong SHG response, which is approximately nine times stronger than that of potassium dihydrogen phosphate, and the largest efficiency observed in materials with structures similar to KBBF. Further characterization suggested that the compound melts congruently at high temperature and has a wide transparency window from the near-UV to the mid-IR region.

  14. Chiral crystal of a C2v-symmetric 1,3-diazaaulene derivative showing efficient optical second harmonic generation

    KAUST Repository

    Ma, Xiaohua

    2011-03-01

    Achiral nonlinear optical (NLO) chromophores 1,3-diazaazulene derivatives, 2-(4â€-aminophenyl)-6-nitro-1,3-diazaazulene (APNA) and 2-(4â€-N,N-diphenylaminophenyl)-6-nitro-1,3-diazaazulene (DPAPNA), were synthesized with high yield. Despite the moderate static first hyperpolarizabilities (β0) for both APNA [(136 ± 5) à - 10-30 esu] and DPAPNA [(263 ± 20) à - 10-30 esu], only APNA crystal shows a powder efficiency of second harmonic generation (SHG) of 23 times that of urea. It is shown that the APNA crystallization driven cooperatively by the strong H-bonding network and the dipolar electrostatic interactions falls into the noncentrosymmetric P2 12121 space group, and that the helical supramolecular assembly is solely responsible for the efficient SHG response. To the contrary, the DPAPNA crystal with centrosymmetric P-1 space group is packed with antiparalleling dimmers, and is therefore completely SHG-inactive. 1,3-Diazaazulene derivatives are suggested to be potent building blocks for SHG-active chiral crystals, which are advantageous in high thermal stability, excellent near-infrared transparency and high degree of designing flexibility. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011 Optical crystals based on 1,3-diazaazulene derivatives are reported as the first example of organic nonlinear optical crystal whose second harmonic generation activity is found to originate solely from the chirality of their helical supramolecular orientation. The strong H-bond network forming between adjacent choromophores is found to act cooperatively with dipolar electrostatic interactions in driving the chiral crystallization of this material. Copyright © 2011 Wiley Periodicals, Inc.

  15. Efficient Second Harmonic Generation in 3D Nonlinear Optical-Lattice-Like Cladding Waveguide Splitters by Femtosecond Laser Inscription.

    Science.gov (United States)

    Nie, Weijie; Jia, Yuechen; Vázquez de Aldana, Javier R; Chen, Feng

    2016-02-29

    Integrated photonic devices with beam splitting function are intriguing for a broad range of photonic applications. Through optical-lattice-like cladding waveguide structures fabricated by direct femtosecond laser writing, the light propagation can be engineered via the track-confined refractive index profiles, achieving tailored output beam distributions. In this work, we report on the fabrication of 3D laser-written optical-lattice-like structures in a nonlinear KTP crystal to implement 1 × 4 beam splitting. Second harmonic generation (SHG) of green light through these nonlinear waveguide beam splitter structures provides the capability for the compact visible laser emitting devices. With Type II phase matching of the fundamental wavelength (@ 1064 nm) to second harmonic waves (@ 532 nm), the frequency doubling has been achieved through this three-dimensional beam splitter. Under 1064-nm continuous-wave fundamental-wavelength pump beam, guided-wave SHG at 532 nm are measured with the maximum power of 0.65 mW and 0.48 mW for waveguide splitters (0.67 mW and 0.51 mW for corresponding straight channel waveguides), corresponding to a SH conversion efficiency of approximately ~14.3%/W and 13.9%/W (11.2%/W, 11.3%/W for corresponding straight channel waveguides), respectively. This work paves a way to fabricate compact integrated nonlinear photonic devices in a single chip with beam dividing functions.

  16. Optimized Second Harmonic Generation of Femtosecond Pulse by Phase-Blanking Effect in Aperiodically Optical Superlattice

    Institute of Scientific and Technical Information of China (English)

    KONG Yan; CHEN Xian-Feng; XIA Yu-Xing

    2008-01-01

    @@ In order to minimize the effect of the unconsidered frequency components on the generated compression pulse,the phasing-blanking effect is taken into account of designing the one-dimensional aperiodic domain reversal structure. Hierarchic genetic algorithm for the design of a domain reversal grating to modulate the spectrum and phase of the generated SH pulse simultaneously are presented. Our simulation shows that the quality of an output pulse is fairly improved.

  17. Second harmonic generation in metal nano-spheres: full-wave analytical solution with both local-surface and nonlocal-bulk nonlinear sources

    CERN Document Server

    Capretti, Antonio; Negro, Luca Dal; Miano, Giovanni

    2013-01-01

    We present a full-wave analytical solution for the problem of second-harmonic generation from spherical particles made of lossy centrosymmetric materials. Both the local-surface and nonlocalbulk nonlinear sources are included in the generation process, under the undepleted-pump approximation. The solution is derived in the framework of the Mie theory by expanding the pump field, the non-linear sources and the second-harmonic fields in series of spherical vector wave functions. We apply the proposed solution to the second-harmonic generation properties of noble metal nano-spheres as function of the polarization, the pump wavelength and the particle size. This approach provides a rigorous methodology to understand second-order optical processes in metal nanoparticles, and to design novel nanoplasmonic devices in the nonlinear regime.

  18. Second harmonic wave generation from a nonlinear combination of volume wave and overdense plasma in negative permeability space

    Science.gov (United States)

    Iwai, Akinori; Nakamura, Yoshihiro; Sakai, Osamu

    2016-09-01

    We clarify the relation between second harmonic wave (SH wave) and plasma generation in various experimental conditions by detecting properties of propagating electromagnetic waves (EM waves). Plasma has a nonlinear reaction against EM wave, generating harmonic waves which depends on electron density ne. In the case with increased ne, EM wave comes to be prevented from going into plasma with negative permittivity ɛp. Double-split-ring resonators (DSRRs), one of metamaterials, make permeability μD negative. We have shown that EM wave being volume wave can propagate into the combination of overdense plasma and DSRRs because of real negative value refractive index N. In our previous paper, we have confirmed enhanced SH wave (4.9 GHz) generation in the composite with 2.45-GHz input. In this report, we show the dependence of the SH wave emission with plasma generation on plasma parameters and gas conditions of plasma. Furthermore, we show the phase change with N variation of the composite space in the case with various input power as the proof of the negative index state.

  19. Second harmonic pico-second pulse generation with mode-locked 1064nm DBR laser diodes

    Science.gov (United States)

    Klehr, A.; Prziwarka, T.; Jedrzejczyk, D.; Brox, O.; Bugge, F.; Wenzel, H.; Paschke, K.; Erbert, G.; Tränkle, G.

    2014-02-01

    Detailed experimental investigations of the generation of high-energy short infrared and green pulses with a mode-locked multi-section distributed Bragg reflector (DBR) laser in dependence on the lengths of the gain section and the saturableabsorber (SA) section as well the corresponding input currents and reverse voltages, respectively, are presented. The laser under investigation is 3.5 mm long and has a 500 μm long DBR section. The remaining cavity was divided into four 50 μm, four 100 μm, two 200 μm and eight 250 μm long electrically separated segments so that the lengths of the gain and SA sections can be simply varied by bonding. Thus, the dependence of the mode-locking behavior on the lengths of the gain and SA sections can be investigated on the same device. Optimal mode-locking was obtained for absorber lengths between LAbs = 200 μm and 300 μm and absorber voltages between UAbs= -2 V and -3 V. A pulse length of τ ≍ 10 ps, a repetition frequency of 13 GHz and a RF line width of less than 100 kHz were measured. An infrared peak pulse power of 900 mW was reached. The FWHM of the optical spectrum was about 150 pm. With an 11.5 mm long periodically poled MgO doped LiNbO3 crystal having a ridge geometry of 5 μm width and 4 μm height green light pulses were generated. With an infrared pump peak power of 900 mW a green pulse energy of 3.15 pJ was reached. The opto-optical conversion efficiency was about 31%.

  20. Quantitative Characterization of Collagen in the Fibrotic Capsule Surrounding Implanted Polymeric Microparticles through Second Harmonic Generation Imaging.

    Directory of Open Access Journals (Sweden)

    Dana Akilbekova

    Full Text Available The collagenous capsule formed around an implant will ultimately determine the nature of its in vivo fate. To provide a better understanding of how surface modifications can alter the collagen orientation and composition in the fibrotic capsule, we used second harmonic generation (SHG microscopy to evaluate collagen organization and structure generated in mice subcutaneously injected with chemically functionalized polystyrene particles. SHG is sensitive to the orientation of a molecule, making it a powerful tool for measuring the alignment of collagen fibers. Additionally, SHG arises from the second order susceptibility of the interrogated molecule in response to the electric field. Variation in these tensor components distinguishes different molecular sources of SHG, providing collagen type specificity. Here, we demonstrated the ability of SHG to differentiate collagen type I and type III quantitatively and used this method to examine fibrous capsules of implanted polystyrene particles. Data presented in this work shows a wide range of collagen fiber orientations and collagen compositions in response to surface functionalized polystyrene particles. Dimethylamino functionalized particles were able to form a thin collagenous matrix resembling healthy skin. These findings have the potential to improve the fundamental understanding of how material properties influence collagen organization and composition quantitatively.

  1. High-speed observation of bubble cloud generation near a rigid wall by second-harmonic superimposed ultrasound.

    Science.gov (United States)

    Yoshizawa, Shin; Yasuda, Jun; Umemura, Shin-ichiro

    2013-08-01

    Cavitation bubbles are known to accelerate therapeutic effects of ultrasound. Although negative acoustic pressure is the principle factor of cavitation, positive acoustic pressure has a role for bubble cloud formation at a high intensity of focused ultrasound when cavitation bubbles provide pressure release surfaces converting the pressure from highly positive to negative. In this study, the second-harmonic was superimposed onto the fundamental acoustic pressure to emphasize either peak positive or negative pressure. The peak negative and positive pressure emphasized waves were focused on a surface of an aluminum block. Cavitation bubbles induced near the block were observed with a high-speed camera by backlight and the size of the cavitation generation region was measured from the high-speed images. The negative pressure emphasized waves showed an advantage in cavitation inception over the positive pressure emphasized waves. In the sequence of the negative pressure emphasized waves immediately followed by the positive pressure emphasized waves, cavitation bubbles were generated on the block by the former waves and the cavitation region were expanded toward the transducer in the latter waves with high reproducibility. The sequence demonstrated its potential usefulness in enhancing the effects of therapeutic ultrasound at a high acoustic intensity.

  2. Isotropic octupolar second harmonic generation response in LaBGeO{sub 5} glass-ceramic with spherulitic precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Truong, Lo Nhat; Fargin, Evelyne, E-mail: marc.dussauze@u-bordeaux.fr, E-mail: fargin@icmcb-bordeaux.cnrs.fr, E-mail: vincent.rodriguez@u-bordeaux.fr; Vigouroux, Hélène; Fargues, Alexandre [Univ. Bordeaux, ICMCB, CNRS UPR 9048, F-33600 Pessac (France); Dussauze, Marc, E-mail: marc.dussauze@u-bordeaux.fr, E-mail: fargin@icmcb-bordeaux.cnrs.fr, E-mail: vincent.rodriguez@u-bordeaux.fr; Adamietz, Frédéric; Rodriguez, Vincent, E-mail: marc.dussauze@u-bordeaux.fr, E-mail: fargin@icmcb-bordeaux.cnrs.fr, E-mail: vincent.rodriguez@u-bordeaux.fr [Univ. Bordeaux, ISM, CNRS UMR 5255, F-33405 Talence (France); Santos, Luis [Centro de Química Estrutural and Departamento de Engenharia Química, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, no. 1, Lisboa (Portugal)

    2015-04-20

    A spherulitic crystallization of the crystalline phase LaBGeO{sub 5} is generated in the 25La{sub 2}O{sub 3}-25B{sub 2}O{sub 3}-50 GeO{sub 2} glass system. Linear and nonlinear optical properties of lanthanum borogermanate glass-ceramic have been investigated at both macroscopic and microscopic scales. Polarized μ-Raman analysis has evidenced a radial distribution of the crystallites along the c-axis inside spherulites, whereas polarized μ-Second Harmonic Generation (SHG) analysis revealed intensity maxima perpendicularly to the c-axis crystallites orientation. Polarized SHG mapping of a spherulite indicate that no dipolar response along the c-axis oriented crystallites occurs despite the individual dipolar symmetry C{sub 3} of the crystallites. At a larger mm scale, the isotropic scattering of spherulites recorded from macroscopic SHG experiment in the forward direction is consistent with an average coherent octupolar response per spherulite. These SHG analyses at different scale are both in accordance with radial antiferroelectric orientation along the c-axis of crystallites inside each spherulite.

  3. Multimodal second harmonic generation and two photon fluorescence imaging of microdomain calcium contraction coupling in single cardiomyocytes

    Science.gov (United States)

    Chan, James; Awasthi, Samir; Izu, Leighton; Mao, Ziliang; Jian, Zhong; Landas, Trevor; Lerner, Aaron; Shimkunas, Rafael; Woldeyesus, Rahwa; Bossuyt, Julie; Wood, Brittani; Chen, Yi-Je; Matthews, Dennis; Lieu, Deborah; Chiamvimonvat, Nipavan; Lam, Kit; Chen-Izu, Ye

    2016-11-01

    The objective of this study was to develop a method for simultaneously measuring the calcium and contraction dynamics of single, live cardiomyocytes at high spatial resolutions. Such measurements are important to investigate local calcium release and the mechanical response at the sarcomere level (i.e. the basic unit of contraction), which have important implications in cardiac dysfunction and arrhythmias in conditions such as hypertension, atrial fibrillation, and myocardial infarction. Here, we describe a multimodal second harmonic generation (SHG) and two photon fluorescence (2PF) microscopy technique that is used to simultaneously measure subsarcomere calcium and contraction events at high spatial and temporal resolutions. The method takes advantage of the label-free nature of SHG for imaging the sarcomeres and the high spatial colocalization of the SHG signal and the fluorescence signal excited from calcium indicators. This microscope was used to measure calcium sparks and waves and associated contractions in subcellular microdomains, leading to the generation of subcellular strain. We anticipate this new imaging tool will play an important role in studying mechanical stress-induced heart disease.

  4. Investigation of the effect of hydration on dermal collagen in ex vivo human skin tissue using second harmonic generation microscopy

    Science.gov (United States)

    Samatham, Ravikant; Wang, Nicholas K.; Jacques, Steven L.

    2016-02-01

    Effect of hydration on the dermal collagen structure in human skin was investigated using second harmonic generation microscopy. Dog ears from the Mohs micrographic surgery department were procured for the study. Skin samples with subject aged between 58-90 years old were used in the study. Three dimensional Multiphoton (Two-photon and backward SHG) control data was acquired from the skin samples. After the control measurement, the skin tissue was either soaked in deionized water for 2 hours (Hydration) or kept at room temperature for 2 hours (Desiccation), and SHG data was acquired. The data was normalized for changes in laser power and detector gain. The collagen signal per unit volume from the dermis was calculated. The desiccated skin tissue gave higher backward SHG compared to respective control tissue, while hydration sample gave a lower backward SHG. The collagen signal decreased with increase in hydration of the dermal collagen. Hydration affected the packing of the collagen fibrils causing a change in the backward SHG signal. In this study, the use of multiphoton microscopy to study the effect of hydration on dermal structure was demonstrated in ex vivo tissue.

  5. Study of interface layer effect in organic solar cells by electric-field-induced optical second-harmonic generation measurement

    Energy Technology Data Exchange (ETDEWEB)

    Taguchi, Dai; Sumiyoshi, Ryota; Chen, Xiangyu; Manaka, Takaaki; Iwamoto, Mitsumasa, E-mail: iwamoto@pe.titech.ac.jp

    2014-03-03

    By using electric-field-induced optical second-harmonic generation (EFISHG) measurement, we studied the effect of the use of bathocuproine (BCP) interface layer. The EFISHG measurements of indium–zinc–oxide (IZO)/C{sub 60}/Al diodes showed that the BCP layer inserted between C{sub 60} and Al formed an electrostatic field |E{sub i}| = 2.5 × 10{sup 4} V/cm in the C{sub 60} layer, pointing in a direction from the Al to the IZO. Accordingly, in the IZO/pentacene/C{sub 60}/BCP/Al organic solar cells (OSCs), holes (electrons) move to the IZO (Al) electrode, enhancing the short-circuit current. The EFISHG measurement is capable of directly probing internal fields in the layers used for OSCs, and is helpful for studying the contribution of the interface layer in OSCs. - Highlights: • Internal field in organic solar cells (OSCs) were directly probed. • Interface layer formed internal electric field, enhancing the OSC performance. • Maxwell–Wagner effect accounts for the internal electric field formation.

  6. Evolution of structural distortion in BiFeO3 thin films probed by second-harmonic generation

    Science.gov (United States)

    Wang, Jie-Su; Jin, Kui-Juan; Guo, Hai-Zhong; Gu, Jun-Xing; Wan, Qian; He, Xu; Li, Xiao-Long; Xu, Xiu-Lai; Yang, Guo-Zhen

    2016-12-01

    BiFeO3 thin films have drawn much attention due to its potential applications for novel magnetoelectric devices and fundamental physics in magnetoelectric coupling. However, the structural evolution of BiFeO3 films with thickness remains controversial. Here we use an optical second-harmonic generation technique to explore the phase-related symmetry evolution of BiFeO3 thin films with the variation of thickness. The crystalline structures for 60 and 180-nm-thick BiFeO3 thin films were characterized by high-resolution X-ray diffractometry reciprocal space mapping and the local piezoelectric response for 60-nm-thick BiFeO3 thin films was characterized by piezoresponse force microscopy. The present results show that the symmetry of BiFeO3 thin films with a thickness below 60 nm belongs to the point group 4 mm. We conclude that the disappearance of fourfold rotational symmetry in SHG s-out pattern implies for the appearance of R-phase. The fact that the thinner the film is, the closer to 1 the tensor element ratio χ31/χ15 tends, indicates an increase of symmetry with the decrease of thickness for BiFeO3 thin films.

  7. Ab initio study of the enantio-selective magnetic-field-induced second harmonic generation in chiral molecules.

    Science.gov (United States)

    Rizzo, Antonio; Rikken, G L J A; Mathevet, R

    2016-01-21

    We present a systematic ab initio study of enantio-selective magnetic-field-induced second harmonic generation (MFISHG) on a set of chiral systems ((l)-alanine, (l)-arginine and (l)-cysteine; 3,4-dehydro-(l)-proline; (S)-α-phellandrene; (R,S)- and (S,S)-cystine disulphide; N-(4-nitrophenyl)-(S)-prolinol, N-(4-(2-nitrovinyl)-phenyl)-(S)-prolinol, N-(4-tricyanovinyl-phenyl)-(S)-prolinol, (R)-BINOL, (S)-BINAM and 6-(M)-helicene). The needed electronic frequency dependent cubic response calculations are performed within a density functional theory (DFT) approach. A study of the dependence of the property on the choice of electron correlation, on one-electron basis set extension and on the choice of magnetic gauge origin is carried out on a prototype system (twisted oxygen peroxide). The magnetic gauge dependence analysis is extended also to the molecules of the set. An attempt to analyze the structure-property relationships is also made, based on the results obtained for biphenyl (in a frozen twisted conformation), for prolinol and for some of their derivatives. The strength of the effect is discussed, in order to establish its measurability with a proposed experimental setup.

  8. Study of all-polymer-based waveguide resonant gratings and their applications for optimization of second-harmonic generation

    Science.gov (United States)

    Hoang Luong, Mai; Thanh Ngan Nguyen, Thi; Thanh Nguyen, Chi; Ledoux-Rak, Isabelle; Diep Lai, Ngoc

    2015-09-01

    We investigated theoretically and experimentally the optical properties of all-polymer-based one-dimensional waveguide resonant gratings (WRGs) and their important applications for the optimization of second-harmonic generation (SHG). We first studied the basic theory of the resonant modes of a simple grating-coupled waveguide realized on a material possessing a low refractive index contrast. The optical properties of any WRG were numerically simulated by using the finite-difference time domain method, performed by commercial Lumerical software. The polymer-based surface relief gratings were fabricated on azopolymer Disperse Red 1-Poly-Methyl-Methacrylate (DR1-PMMA) thin films by using the two-beam interference method and mass transport effect. Their experimental reflection spectra measured as a function of incident light wavelength are in good agreement with the theoretical predictions. We then demonstrated a first application of such a polymer-based WRG for nonlinear optics. Thanks to the strong local electrical field in the WRG, due to a guided-mode resonance condition, the SHG signal of an infrared light beam was strongly enhanced by a factor of 25 as compared to the result obtained in a sample without a grating.

  9. Optical second harmonic generation in TlMeX{sub 2} (Me=In,Ga,X=S,Se,Te)

    Energy Technology Data Exchange (ETDEWEB)

    Araki, Yoshito; Asaba, Ryo; Wakita, Kazuki [Faculty of Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016 (Japan); Shim, YongGu; Mimura, Kojiro [Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuencho, Sakai, Osaka 599-8531 (Japan); Mamedov, Nazim [Institute of Physics, National Academy of Sciences of Azerbaijan, H. Javid ave. 33, Baku 1143 (Azerbaijan)

    2013-08-15

    Optical second harmonic generation (SHG) has been studied in TlMeX{sub 2} (Me=In,Ga, X=S,Se,Te) compounds with layered and chain crystalline structures. For layered TlInS{sub 2} and TlGaSe{sub 2}, SHG signal has been observed in a range of temperatures below the point of phase transition into ferroelectric phase for which asymmetry is prominent. On the other hand, the chain TlInSe{sub 2} and TlGaTe{sub 2} have shown SHG signal at a temperature above 270 and 293K, respectively. Both the TlInSe{sub 2} and TlGaTe{sub 2} have symmetry centre at room temperature and second order optical non-linearity is an artefact incompatible with their bulk structure. Surface structure is speculated to be responsible for SHG signal observed in these materials for the first time to our knowledge. The details of temperature behaviour of SHG in TlInSe{sub 2} and TlGaTe{sub 2}lead to a phase-transition based model for explanation of the observed phenomenon. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. In situ quantitative evaluation of osteoblastic collagen synthesis under cyclic strain by using second-harmonic-generation microscope

    Science.gov (United States)

    Matsubara, Oki; Hase, Eiji; Minamikawa, Takeo; Yasui, Takeshi; Sato, Katsuya

    2016-03-01

    Osteoblast-produced collagen matrix in bone is influenced by the mechanical stimulus from their surroundings. However, it has been still unclear how mechanical stimulus affects collagen production by osteoblasts. Therefore, it is strongly required to investigate the characteristics of osteoblastic bone regenerative tissue engineering. Recently, second-harmonic-generation (SHG) microscope has attracted attention for in situ visualization of collagen fiber because of less invasiveness, unstaining and no fixation, as well as high spatial resolution and 3D imaging. Using SHG microscopy, one can track the temporal dynamics of collagen fiber during the cultured period of the sample. We applied cyclic stretch strain to osteoblasts (MC3T3-E1) by using originally developed cell stretching device. The stimulation time was set to 5min or 3hours with same strain 5% and same frequency 0.5Hz. Cells were seeded onto the PDMS (polydimethylsiloxane) rubber chamber at a density of 50,000 cells/cm2 and cultured in α-MEM with 10% FBS, 1% P/S, 1% Ascorbic acid, 0.2% hydrocortisone and 2% β-Glycerophosphate. SHG imaging was carried out every 7 days. As a result, we confirmed from SHG image that the collagen production was enhanced by the cyclic stretch strain, stretch stimulation time and stretch application term.

  11. Novel material for second harmonic generation: 3-Amino-1,2,4-triazolinium(1+) hydrogen L-tartrate

    Science.gov (United States)

    Matulková, Irena; Němec, Ivan; Císařová, Ivana; Němec, Petr; Mička, Zdeněk

    2007-05-01

    The X-ray structural analysis of 3-amino-1,2,4-triazolinium(1+) hydrogen L-tartrate has been carried out. This organic salt crystallises in the monoclinic space group P2 1, a = 7.7130(2) Å, b = 6.7690(2) Å, c = 9.2170(3) Å, β = 95.726(2)°, V = 478.81(2) Å 3, Z = 2, R = 0.0255 for 5922 observed reflections. The crystal structure is formed by a 3D network of hydrogen L-tartrate anions (interconnected by O-H ⋯O hydrogen bonds) with 3-amino-1,2,4-triazolinium(1+) cations located in the cavities of this network and connected with anions via N-H ⋯O and O-H ⋯N hydrogen bonds. The FTIR and FT Raman spectra were recorded, calculated and discussed. Quantitative measurements of second harmonic generation of powdered 3-amino-1,2,4-triazol-4-ium hydrogen L-tartrate at 800 nm were performed and a relative efficiency of 50% (compared to KDP) was observed.

  12. The crystal structure, vibrational spectra, thermal behaviour and second harmonic generation of aminoguanidinium(1+) hydrogen L-tartrate monohydrate

    Science.gov (United States)

    Macháčková, Zorka; Němec, Ivan; Teubner, Karel; Němec, Petr; Vaněk, Přemysl; Mička, Zdeněk

    2007-04-01

    Aminoguanidinium(1+) hydrogen L-tartrate monohydrate was prepared by crystallisation from aqueous solution and X-ray structural analysis was carried out. The substance crystallises in the orthorhombic system in space group P2 12 12 1, a = 7.1380(2) Å, b = 9.9700(4) Å, c = 14.0790(6) Å, V = 1001.94(7) Å 3, Z = 4, R = 0.0271 for 2272 observed reflections. The crystal structure consists of a 3D framework formed by hydrogen tartrate anions and water molecules with incorporated aminoguanidinium(1+) cations connected by a system of hydrogen bonds. The FTIR and FT Raman spectra of natural and N,O-deuterated compounds were measured and discussed at laboratory temperature. DSC measurements were carried out in the temperature range from 95 to 380 K. A weak anomaly was observed at a temperature of 268 K. Quantitative measurements of second harmonic generation of powdered aminoguanidinium(1+) hydrogen tartrate monohydrate at 800 nm were performed relative to KDP and a relative efficiency of 14% was observed.

  13. Precise Determination of the Crystallographic Orientations in Single ZnS Nanowires by Second-Harmonic Generation Microscopy

    CERN Document Server

    Hongbo, Hu; Hua, Long; Weiwei, Liu; Bing, Wang; Peixiang, Lu

    2015-01-01

    We report on the systematical study of the second-harmonic generation (SHG) in single zinc sulfide nanowires (ZnS NWs). The high quality ZnS NWs with round cross-section were fabricated by chemical vapor deposition method. The transmission electron microscopy images show that the actual growth-axis has a deviation angle of 0o~20o with the preferential growth direction [120], which leads to the various polarization-dependent SHG response patterns in different individual ZnS NWs. The SHG response is quite sensitive to the orientations of c-axis as well as the (100) and (010) crystal-axis of ZnS NWs, thus all the three crystal-axis orientations of ZnS NWs are precisely determined by the SHG method. A high SHG conversion efficiency of 7*10^(-6) is obtained in single ZnS NWs, which shows potential applications in nanoscale ultraviolet light source, nonlinear optical microscopy and nanophotonic devices.

  14. Comparison of reflectance confocal microscopy and two-photon second harmonic generation microscopy in fungal keratitis rabbit model ex vivo

    Science.gov (United States)

    Lee, Jun Ho; Lee, Seunghun; Yoon, Calvin J.; Park, Jin Hyoung; Tchah, Hungwon; Kim, Myoung Joon; Kim, Ki Hean

    2016-01-01

    Fungal keratitis is an infection of the cornea by fungal pathogens. Diagnosis methods based on optical microscopy could be beneficial over the conventional microbiology method by allowing rapid and non-invasive examination. Reflectance confocal microscopy (RCM) and two-photon second harmonic generation microscopy (TPSHGM) have been applied to pre-clinical or clinical studies of fungal keratitis. In this report, RCM and TPSHGM were characterized and compared in the imaging of a fungal keratitis rabbit model ex vivo. Fungal infection was induced by using two strains of fungi: aspergillus fumigatus and candida albicans. The infected corneas were imaged in fresh condition by both modalities sequentially and their images were analyzed. Both RCM and TPSHGM could detect both fungal strains within the cornea based on morphology: aspergillus fumigatus had distinctive filamentous structures, and candida albicans had round structures superficially and elongated structures in the corneal stroma. These imaging results were confirmed by histology. Comparison between RCM and TPSHGM showed several characteristics. Although RCM and TPSHGM images had good correlation each other, their images were slightly different due to difference in contrast mechanism. RCM had relatively low image contrast with the infected turbid corneas due to high background signal. TPSHGM visualized cells and collagen in the cornea clearly compared to RCM, but used higher laser power to compensate low autofluorescence. Since these two modalities provide complementary information, combination of RCM and TPSHGM would be useful for fungal keratitis detection by compensating their weaknesses each other. PMID:26977371

  15. Evolution of structural distortion in BiFeO3 thin films probed by second-harmonic generation.

    Science.gov (United States)

    Wang, Jie-Su; Jin, Kui-Juan; Guo, Hai-Zhong; Gu, Jun-Xing; Wan, Qian; He, Xu; Li, Xiao-Long; Xu, Xiu-Lai; Yang, Guo-Zhen

    2016-12-01

    BiFeO3 thin films have drawn much attention due to its potential applications for novel magnetoelectric devices and fundamental physics in magnetoelectric coupling. However, the structural evolution of BiFeO3 films with thickness remains controversial. Here we use an optical second-harmonic generation technique to explore the phase-related symmetry evolution of BiFeO3 thin films with the variation of thickness. The crystalline structures for 60 and 180-nm-thick BiFeO3 thin films were characterized by high-resolution X-ray diffractometry reciprocal space mapping and the local piezoelectric response for 60-nm-thick BiFeO3 thin films was characterized by piezoresponse force microscopy. The present results show that the symmetry of BiFeO3 thin films with a thickness below 60 nm belongs to the point group 4 mm. We conclude that the disappearance of fourfold rotational symmetry in SHG s-out pattern implies for the appearance of R-phase. The fact that the thinner the film is, the closer to 1 the tensor element ratio χ31/χ15 tends, indicates an increase of symmetry with the decrease of thickness for BiFeO3 thin films.

  16. Evolution of structural distortion in BiFeO3 thin films probed by second-harmonic generation

    Science.gov (United States)

    Wang, Jie-su; Jin, Kui-juan; Guo, Hai-zhong; Gu, Jun-xing; Wan, Qian; He, Xu; Li, Xiao-long; Xu, Xiu-lai; Yang, Guo-zhen

    2016-01-01

    BiFeO3 thin films have drawn much attention due to its potential applications for novel magnetoelectric devices and fundamental physics in magnetoelectric coupling. However, the structural evolution of BiFeO3 films with thickness remains controversial. Here we use an optical second-harmonic generation technique to explore the phase-related symmetry evolution of BiFeO3 thin films with the variation of thickness. The crystalline structures for 60 and 180-nm-thick BiFeO3 thin films were characterized by high-resolution X-ray diffractometry reciprocal space mapping and the local piezoelectric response for 60-nm-thick BiFeO3 thin films was characterized by piezoresponse force microscopy. The present results show that the symmetry of BiFeO3 thin films with a thickness below 60 nm belongs to the point group 4 mm. We conclude that the disappearance of fourfold rotational symmetry in SHG s-out pattern implies for the appearance of R-phase. The fact that the thinner the film is, the closer to 1 the tensor element ratio χ31/χ15 tends, indicates an increase of symmetry with the decrease of thickness for BiFeO3 thin films. PMID:27905565

  17. Plasmon-enhanced second-harmonic generation from hybrid ZnO-covered silver-bowl array

    Science.gov (United States)

    Yang, Mingming; Shen, Shaoxin; Wang, Xiangjie; Yu, Binbin; Huang, Shengli; Xu, Die; Hu, Jiawen; Yang, Zhilin

    2016-06-01

    High-efficient, plasmon-enhanced nonlinear phenomena based on hybrid nanostructures, which combine nonlinear dielectrics with plasmonic metals, are of fundamental importance for various applications ranging from all-optical switching to imaging or bio-sensing. However, the high loss of the excitation energy in nanostructures and the poor spatial overlap between the plasmon enhancement and the bulk of nonlinear materials largely limit the operation of plasmon-enhanced nonlinear effects, resulting in low nonlinear conversion efficiency. Here, we design and fabricate a ZnO-covered, 2D silver-bowl array, which can serve as an efficient platform for plasmon-enhanced second-harmonic generation (PESHG). Validated by experiments and simulations, we demonstrate that the high spatial overlap between the near-field enhancement and the ZnO film plays the key role for this nanostructure-based PESHG process. The enhancement mainly originates from the fundamental wavelength-derived plasmon resonance, providing an enhancement factor of approximately 33 times. These results achieved pave the way for future applications, which require localized light sources at nanoscale.

  18. Novel D-π-A-π-D type organic chromophores for second harmonic generation and multi-photon absorption applications

    Science.gov (United States)

    Aditya, Pusala; Kumar, Hari; Kumar, Sunil; Rajashekar, Muralikrishna, M.; Muthukumar, V. Sai; Kumar, B. Siva; Sai, S. Siva Sankara; Rao, G. Nageshwar

    2013-06-01

    We report here the optical and non-linear optical properties of six different novel bis-chalcones of D-π-A-π-D derivatives of diarylideneacetone (DBA). These derivatives have been synthesized by Claisen-Schmidt condensation reaction and were well characterized by using FTIR, 1HNMR, 13CNMR, UV-Visible absorption and mass spectroscopic techniques. The optical bandgap for each of the DBA derivatives were determined both experimentally (UV-Visible spectra & Tauc Plot) and theoretically by ab intio DFT calculations using SIESTA software package. They were found to be in close agreement with each other. The Second Harmonic Generation from these organic chromophores were studied by standard Kurtz and Perry Powder SHG method at 1064 nm. They were found to have superior SHG conversion efficiency when compared to urea (standard sample). Further, we investigated the Multi-Photon absorption properties were using conventional open aperture z-scan technique. These DBA derivatives exhibited strong two photon absorption in the order of 1e-11m/W. Hence, these are potential candidate for various photonic applications like optical power limiting, photonic switching and frequency conversion.

  19. Second-harmonic optical coherence tomography

    Science.gov (United States)

    Jiang, Yi; Tomov, Ivan; Wang, Yimin; Chen, Zhongping

    2004-05-01

    Second-harmonic optical coherence tomography, which uses coherence gating of second-order nonlinear optical responses of biological tissues for imaging, is described and demonstrated. Femtosecond laser pulses were used to excite second-harmonic waves from collagen harvested from rat tail tendon and a reference nonlinear crystal. Second-harmonic interference fringe signals were detected and used for image construction. Because of the strong dependence of second-harmonic generation on molecular and tissue structures, this technique imparts contrast and resolution enhancement to conventional optical coherence tomography.

  20. Influence of the intracavity second harmonic generation on the mode competition in a double-mode diode-pumped Nd : YAG laser

    NARCIS (Netherlands)

    Yermachenko, VM; Karle, RA; Petrovskiy, VN; Protsenko, ED

    2005-01-01

    The influence of intracavity second harmonic generation on the mode competition in a double-mode diode-pumped Nd:YAG laser is studied theoretically and experimentally. Various configurations of the optical cavity with II-type phase-matching frequency-doubling crystals are considered. The conditions

  1. A Simple Calculation Approach for the Second-Harmonic Sound Beam Generated by an Arbitrary Distribution Source

    Institute of Scientific and Technical Information of China (English)

    DING De-Sheng; ZHANG Yu

    2004-01-01

    @@ We present a simple calculation approach for the fundamental and second-harmonic sound beams with an arbitrary distribution source in the quasilinear approximation. The analysis is based on the assumption that the source function with an arbitrary geometry and distribution is expanded into the sum of a set of two-dimensional Gaussian functions. The two- and five-dimensional integral solutions for the fundamental and second-harmonic fields are, respectively, reduced in terms of Gaussian functions and simple one-dimensional integrals. The numerical evaluation of field distributions is then greatly simplified.

  2. Quantification of collagen fiber organization in biological tissues at cellular and molecular scales using second-harmonic generation imaging

    Science.gov (United States)

    Ambekar Ramachandra Rao, Raghu

    Collagen is the most abundant structural protein found in the human body, and is responsible for providing structure and function to tissues. Collagen molecules organize naturally into structures called fibers on the scale of the wavelength of light and lack inversion symmetry, thus allowing for the process of second harmonic generation (SHG) when exposed to intense incident light. We have developed two quantitative techniques: Fourier transform-second-harmonic generation (FT-SHG) imaging and generalized chi2 second-harmonic generation (chi2-SHG) imaging. In order to show that FT-SHG imaging can be used as a valuable diagnostic tool for real-world biological problems, we first investigate collagenase-induced injury in horse tendons. Clear differences in collagen fiber organization between normal and injured tendon are quantified. In particular, we observe that the regularly oriented organization of collagen fibers in normal tendons is disrupted in injured tendons leading to a more random organization. We also observe that FT-SHG microscopy is more sensitive in assessing tendon injury compared to the conventional polarized light microscopy. The second study includes quantifying collagen fibers in cortical bone using FT-SHG imaging and comparing it with scanning electron microscopy (SEM). Further, as an example study, we show how FT-SHG imaging could be used to quantify changes in bone structure as a function of age. Some initial work and future directions for extending FT-SHG to 3D are also discussed. The second technique, chi2-SHG imaging, takes advantage of the coherent nature of SHG and utilizes polarization to extract the second-order susceptibility (d elements) which provides information on molecular organization, i.e., it provides access to sub-diffractional changes "optically". We use chi2-SHG in combination with FT-SHG imaging to investigate a couple of biological problems. First, we quantify differences in collagen fiber organization between cornea and

  3. 1.5 W green light generation by single-pass second harmonic generation of a single-frequency tapered diode laser

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Andersen, Peter E.; Sumpf, Bernd;

    2009-01-01

    More than 1.5 W of green light at 531 nm is generated by singlepass second harmonic generation in periodically poled MgO:LiNbO3. The pump laser is a high power tapered laser with a distributed Bragg reflector etched in the ridge section of the laser to provide wavelength selectivity. The output...... power of the single-frequency tapered laser is 9.3 W in continuous wave operation. A conversion efficiency of 18.5 % was achieved in the experiments....

  4. Study of Electrical Conduction Mechanism of Organic Double-Layer Diode Using Electric Field Induced Optical Second Harmonic Generation Measurement.

    Science.gov (United States)

    Nishi, Shohei; Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa

    2016-04-01

    By using electric field induced optical second harmonic generation (EFISHG) and current voltage (I-V) measurements, we studied the electrical transport mechanism of organic double-layer diodes with a structure of Au/N, N'-di-[(1-naphthyl)-N, N'-diphenyl]-(1,1'-biphenyl)-4,4'-diamine (a-NPD)/poly(methyl methacrylate) (PMMA)/indium zinc oxide (IZO). Here the α-NPD is a carrier transport layer and the PMMA is an electrical insulating layer. The current level was very low, but the I-V characteristics showed a rectifying behavior. The EFISHG measurement selectively and directly probed the electric field across the α-NPD layer, and showed that the electric field across the a-NPD layer is completely relaxed owing to the charge accumulation at the a-NPD/PMMA interface in the region V > 0, whereas the carrier accumulation was not significant in the region V < 0. On the basis of these experimental results, we proposed a model of the rectification. Further, by coupling the I-V characteristics with the EFISHG measurement, the I-V characteristics of the diodes were well converted into the current-electric field (I-E) characteristics of the α-NPD layer and the PMMA layer. The I-E characteristics suggested the Schottky-type conduction governs the carrier transport. We conclude that the I-V measurement coupled with the EFISHG measurement is very useful to study carrier transport mechanism of the organic double-layer diodes.

  5. Thermal Expansion and Second Harmonic Generation Response of the Tungsten Bronze Pb2AgNb5O15.

    Science.gov (United States)

    Lin, Kun; Gong, Pifu; Sun, Jing; Ma, Hongqiang; Wang, You; You, Li; Deng, Jinxia; Chen, Jun; Lin, Zheshuai; Kato, Kenichi; Wu, Hui; Huang, Qingzhen; Xing, Xianran

    2016-03-21

    The incorporation of transition metal element Ag was performed to explore negative thermal expansion (NTE) materials with tetragonal tungsten bronze (TTB) structures. In this study, the structure and thermal expansion behaviors of a polar TTB oxide, Pb2AgNb5O15 (PAN), were systematically investigated by high-resolution synchrotron powder diffraction, high-resolution neutron powder diffraction, transmission electron microscope (TEM), and high-temperature X-ray diffractions. The TEM and Rietveld refinements revealed that the compound PAN displays (√2a(TTB), √2b(TTB), 2c(TTB))-type superstructure. This superstructure within the a-b plane is caused by the ordering of A-site cations, while the doubling of the c axis is mainly induced by a slight tilt distortion of the NbO6 octahedra. The transition metal Ag has larger spontaneous polarization displacements than Pb, but the Pb-O covalence seems to be weakened compared to the potassium counterpart Pb2KNb5O15 (PKN), which may account for the similar Curie temperature and uniaxial NTE behavior for PAN and PKN. Powder second harmonic generation (SHG) measurement indicates that PAN displays a moderate SHG response of ∼0.2 × LiNbO3 (or ∼100 × α-SiO2) under 1064 nm laser radiation. The magnitudes of the local dipole moments in NbO6 and PbOx polyhedra were quantified using bond-valence approach. We show that the SHG response stems from the superposition of dipole moments of both the PbO(x) and NbO6 polyhedra.

  6. Integrated quasi-phase-matched second-harmonic generator and electro-optic phase modulator for low-noise phase-sensitive amplification.

    Science.gov (United States)

    Enbutsu, Koji; Umeki, Takeshi; Tadanaga, Osamu; Asobe, Masaki; Takenouchi, Hirokazu

    2015-07-15

    We propose a quasi-phase-matched second-harmonic generator integrated with an electro-optic phase modulator in a directly bonded LiNbO3 (DB-LN) waveguide to obtain high signal-to-noise ratio (SNR) pump light for a phase-sensitive amplifier (PSA). This integrated device exhibits 1-MHz modulation and 1-W second-harmonic-generation properties sufficient for phase-locking between the signal and pump and for PSA gain, respectively. A novel PSA configuration based on the high-input-power tolerance of the device helps to suppress the noise from the erbium-doped fiber amplifier used for pump-light generation and leads to an improvement of the SNR of the pump light. The SNR improvement was confirmed by comparing the noise figure of a PSA employing the DB-LN waveguide with that of a PSA using a Ti-diffused LN waveguide modulator.

  7. Numerical analysis of near and far field patterns of second-harmonic generation with tiling nonlinear optical crystals

    Energy Technology Data Exchange (ETDEWEB)

    Harimoto, T [Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 4-3-11 Kofu, Yamanashi 400-8511 (Japan); Shiraga, H [Institute of Laser Engineering, Osaka University, Suita, Osaka (Japan)], E-mail: harimoto@yamanashi.ac.jp

    2008-05-01

    We report numerical analysis of near- and far-field patterns of the second-harmonic wave in a large-scale high-power laser used in the laser fusion with type I KDP crystals arranged in a tiling style. The thickness and phase-matching angle of the tiling crystals are designed based on the near-field pattern of the second-harmonic wave. The tilting angle error and thickness difference of the tiling crystals are evaluated by the energy distribution included in the Airy spot of the far-field pattern at the focal point. The parallelism and flatness of the tiling crystals can also be estimated with the same method.

  8. Effects of applied electric and magnetic fields on the nonlinear optical rectification and second-harmonic generation in a graded quantum well under intense laser field

    Science.gov (United States)

    Ungan, Fatih

    2017-01-01

    In this present study, the effects of electric and magnetic fields on the nonlinear optical rectification and second-harmonic generation in a graded quantum well under intense laser field have been investigated theoretically. The energy eigenvalues and their corresponding eigenfunctions are obtained by solving Schrödinger equation within the framework of effective mass approximation. The analytic expressions for the optical properties are calculated by the compact-density-matrix approach and iterative method. The numerical results are presented for a typical GaAs/Ga1- x Al x As quantum well. The results show that the nonlinear optical rectification and second-harmonic generation coefficients are considerably affected by the electromagnetic fields and intense laser field.

  9. Effect of lamellar nanostructures on the second harmonic generation of polymethylmethacrylate films doped with 4-(4-nitrophenylazo)aniline chromophores

    CERN Document Server

    Franco, Alfredo; Valverde-Aguilar, Guadalupe; García-Macedo, Jorge; Brusatin, Giovanna; Guglielmi, Massimo

    2011-01-01

    The kinetics of the orientation of Disperse Orange 3 molecules embedded in amorphous and nanostructured Polymethylmethacrylate films was studied under the effect of an intense electrostatic poling field. Non-centrosymmetric chromophore distributions were obtained in Polymethylmethacrylate films by Corona poling technique. These distributions depends on the Corona poling time. The changes in the orientation of the Disperse Orange 3 molecules were followed by in-situ transmitted Second Harmonic Generation measurements. The Second Harmonic Generation signal was recorded as function of time at several temperatures; it was fitted as function of the Corona poling time, considering matrix-chromophore interactions. The Polymethylmethacrylate films were nanostructured by the incorporation of an anionic surfactant, the Sodium Dodecyl Sulfate. The lamellar nanostructures in the films were identified by X-ray diffraction measurements.

  10. First and second harmonic generation of the XAl{sub 2}Se{sub 4} (X=Zn,Cd,Hg) defect chalcopyrite compounds

    Energy Technology Data Exchange (ETDEWEB)

    Ouahrani, Tarik, E-mail: tarik_ouahrani@yahoo.fr [Laboratoire de Physique Theorique, Universite de Tlemcen, B.P.230,13000 Tlemcen (Algeria); Ecole Preparatoire en Sciences et Techniques, Depertement de Physique EPST-T, Tlemcen 13000 (Algeria); Khenata, R. [Laboratoire de Physique Quantique et de Modelisation Mathematique (LPQ3M), Universite de Mascara, 29000 Mascara (Algeria); Lasri, B. [Laboratoire de Physique Theorique, Universite de Tlemcen, B.P.230,13000 Tlemcen (Algeria); Universite Dr Tahar Moulay de Saida, B.P. 138, Cite el Nasr, Saida 20000 (Algeria); Reshak, Ali H. [School of Complex systems, FFPW- South Bohemia University, Nove Hrady 37333 (Czech Republic); School of Material Engineering, Malaysia University of Perlis, P.O Box 77, d/a Pejabat Pos Besar, 01007 Kangar, Perlis (Malaysia); Bouhemadou, A. [Department of Physics, Faculty of Sciences, University of Setif, 19000 Setif (Algeria); Bin-Omran, S. [Department of Physics and Astronomy, Faculty of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia)

    2012-09-15

    The chemical bonding of the ZnAl{sub 2}Se{sub 4}, CdAl{sub 2}Se{sub 4} and HgAl{sub 2}Se{sub 4} defect chalcopyrites has been studied in the framework of the quantum theory of atoms in molecules (AIM). The GW quasi-particle approximation is used to correct the DFT-underestimation of energy gap, and as a consequence the linear and nonlinear optical properties are significantly enhanced. The second harmonic generation (SHG) displays certain dependence with the ionicity degree decrease through the dependency of the SHG on the band gap. The occurrence of the AIM saddle point is characterized and some clarifying features in relationship with the density topology are exposed, which enable to understand the relation with the second harmonic generation effect.

  11. Spectral characterization of some second harmonic generation materials from the amino acid family: L-Threonine and L-prolinium tartrate

    Science.gov (United States)

    Moovendaran, K.; Natarajan, S.

    2014-08-01

    Single crystals of the organic non-linear optical materials L-threonine (I) and L-prolinium tartrate (II) were grown using a home-made crystal growth setup (MKN setup). The grown crystals were characterized using X-ray diffraction, Infrared (IR), UV-vis-NIR and Circular dichroism (CD) spectroscopy. Measurements of Vicker’s microhardness, laser damage threshold (LDT) values and second harmonic generation (SHG) efficiencies are reported. Thermal and dielectric studies were also carried out.

  12. Detailed study of an efficient blue laser source by second-harmonic generation in a semimonolithic cavity for the cooling of strontium atoms.

    Science.gov (United States)

    Klappauf, Bruce G; Bidel, Yannick; Wilkowski, David; Chanelière, Thierry; Kaiser, Robin

    2004-04-20

    We have constructed a blue laser source consisting of an amplified, grating tuned diode laser that is frequency doubled by a KNbO3 crystal in a compact standing wave cavity and produces as much as 200 mW of internal second-harmonic power. We have analyzed the unusual characteristics of this standing wave cavity to clarify the advantages and disadvantages of this configuration as an alternative to a ring cavity for second-harmonic generation. We emphasize its efficiency and stability and the fact that it has an inherent walk-off compensation, similar to twin crystal configurations. We demonstrate its utility for laser cooling and trapping of earth alkalis by stabilizing the laser to the 461-nm transition of strontium, using a heat pipe, and then forming a magneto-optic trap of strontium from a Zeeman-slowed atomic beam.

  13. Current collapse imaging of Schottky gate AlGaN/GaN high electron mobility transistors by electric field-induced optical second-harmonic generation measurement

    Energy Technology Data Exchange (ETDEWEB)

    Katsuno, Takashi, E-mail: e1417@mosk.tytlabs.co.jp; Ishikawa, Tsuyoshi; Ueda, Hiroyuki; Uesugi, Tsutomu [Toyota Central R and D Laboratories Inc., Nagakute, Aichi 480-1192 (Japan); Manaka, Takaaki; Iwamoto, Mitsumasa [Department of Physical Electronics, Tokyo Institute of Technology, Meguro, Tokyo 152-8552 (Japan)

    2014-06-23

    Two-dimensional current collapse imaging of a Schottky gate AlGaN/GaN high electron mobility transistor device was achieved by optical electric field-induced second-harmonic generation (EFISHG) measurements. EFISHG measurements can detect the electric field produced by carriers trapped in the on-state of the device, which leads to current collapse. Immediately after (e.g., 1, 100, or 800 μs) the completion of drain-stress voltage (200 V) in the off-state, the second-harmonic (SH) signals appeared within 2 μm from the gate edge on the drain electrode. The SH signal intensity became weak with time, which suggests that the trapped carriers are emitted from the trap sites. The SH signal location supports the well-known virtual gate model for current collapse.

  14. Detailed Study of an Efficient Blue Laser Source by Second-Harmonic Generation in a Semimonolithic Cavity for the Cooling of Strontium Atoms

    Science.gov (United States)

    Klappauf, Bruce G.; Bidel, Yannick; Wilkowski, David; Chanelière, Thierry; Kaiser, Robin

    2004-04-01

    We have constructed a blue laser source consisting of an amplified, grating tuned diode laser that is frequency doubled by a KNbO3 crystal in a compact standing wave cavity and produces as much as 200 mW of internal second-harmonic power. We have analyzed the unusual characteristics of this standing wave cavity to clarify the advantages and disadvantages of this configuration as an alternative to a ring cavity for second-harmonic generation. We emphasize its efficiency and stability and the fact that it has an inherent walk-off compensation, similar to twin crystal configurations. We demonstrate its utility for laser cooling and trapping of earth alkalis by stabilizing the laser to the 461-nm transition of strontium, using a heat pipe, and then forming a magneto-optic trap of strontium from a Zeeman-slowed atomic beam.

  15. Surface and interface states of Bi{sub 2}Se{sub 3} thin films investigated by optical second-harmonic generation and terahertz emission

    Energy Technology Data Exchange (ETDEWEB)

    Hamh, S. Y.; Park, S.-H.; Lee, J. S., E-mail: jsl@gist.ac.kr [Department of Physics and Photon Science, School of Physics and Chemistry, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Jerng, S.-K.; Jeon, J. H.; Chun, S. H. [Department of Physics and Graphene Research Institute, Sejong University, Seoul 143-747 (Korea, Republic of); Jeon, J. H.; Kahng, S. J. [Department of Physics, Korea University, Seoul 136-701 (Korea, Republic of); Yu, K.; Choi, E. J. [Department of Physics, University or Seoul, Seoul 130-743 (Korea, Republic of); Kim, S.; Choi, S.-H. [Department of Applied Physics, College of Applied Science, Kyung Hee University, Yongin 446-701 (Korea, Republic of); Bansal, N. [Department of Electrical and Computer Engineering, Rutgers, The state University of New Jersey, Piscataway, New Jersey 08854 (United States); Oh, S. [Department of Physics and Astronomy, Rutgers, The state University of New Jersey, Piscataway, New Jersey 08854 (United States); Park, Joonbum; Kho, Byung-Woo; Kim, Jun Sung [Department of Physics, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)

    2016-02-01

    We investigate the surface and interface states of Bi{sub 2}Se{sub 3} thin films by using the second-harmonic generation technique. Distinct from the surface of bulk crystals, the film surface and interface show the isotropic azimuth dependence of second-harmonic intensity, which is attributed to the formation of randomly oriented domains on the in-plane. Based on the nonlinear susceptibility deduced from the model fitting, we determine that the surface band bending induced in a space charge region occurs more strongly at the film interface facing the Al{sub 2}O{sub 3} substrate or capping layer compared with the interface facing the air. We demonstrate that distinct behavior of the terahertz electric field emitted from the samples can provide further information about the surface electronic state of Bi{sub 2}Se{sub 3}.

  16. Reversible phase transition in semi-organic compound p-Nitroanilinium sulfate detected using second harmonic generation as a tool

    Science.gov (United States)

    Bouchouit, K.; Bougharraf, H.; Derkowska-Zielinska, B.; Benali-cherif, N.; Sahraoui, B.

    2015-10-01

    Crystals structure of p-Nitroanilinium sulfate, (C6H7N2O2+, HSO4-) grown from aqueous solution were characterized by single crystal X-ray diffraction at 298 K. This compound crystallizes in P212121 space group of orthorhombic system. The structure is built by chains formed by (NH3C6H4NO2+) organic cations between which are situated the sulfate mineral anions (HSO4-). The thermal analyses were realized by differential scanning calorimetry (DSC) technique which indicated that the p-Nitroanilinium sulfate present a reversible phase transition at Tc = 338(2) K. The SHG measurements were realized at room temperature as well as with temperature depending. During heating and cooling processes the second harmonic signals show a reversible phase transition at 57 °C. These results are in good agreement with the results obtained from DSC measurements.

  17. Mode-locking of a high power, 888 nm pumped Nd:YVO4 laser using nonlinear polarization rotation via Type I second harmonic generation.

    Science.gov (United States)

    Schäfer, Christoph; Fries, Christian; Theobald, Christian; L'huillier, Johannes A

    2013-01-15

    Continuous-wave mode-locking of a laser exploiting the nonlinear polarization rotation (NPR) technique via Type I second harmonic generation is demonstrated for the first time. The NPR is generated by a lithium triborate crystal and transformed into nonlinear cavity losses of a 888 nm pumped Nd:YVO4 laser. Self-starting, reliable mode-locking has been achieved at a high average output power of 20.6 W and a pulse duration of 7.3 ps. Furthermore, transform limited pulses down to 2.7 ps have been demonstrated at 9.9 W.

  18. Study of carrier blocking property of poly-linalyl acetate thin layer by electric-field-induced optical second-harmonic generation measurement

    Science.gov (United States)

    Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa; Anderson, Liam J.; Jacob, Mohan V.

    2014-02-01

    By using electric-field-induced optical second-harmonic generation (EFISHG) measurement, we studied the carrier-blocking property of poly-linalyl acetate (PLA) thin layers sandwiched in indium-zinc-oxide (IZO)/PLA/C60/Al double-layer diodes. Results showed that the PLA layer totally blocks electrons crossing the C60 layer, and also blocks holes entering from the IZO layer. The EFISHG measurement effectively substantiates the hole-blocking electron-blocking property of the PLA layer sandwiched in double layer diodes.

  19. Crystal-field theoretical approach to second harmonic generation on antiferromagnetic NiO(001), CoO(001), and FeO(001) surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ney, O [Department of Physics, Kaiserslautern University of Technology, Box 3049, D-67653 Kaiserslautern (Germany); Trzeciecki, M [Hans Guentner GmbH, Industriestrasse 14, D-82256 Fuerstenfeldbruck (Germany); Huebner, W [Department of Physics, Kaiserslautern University of Technology, Box 3049, D-67653 Kaiserslautern (Germany)

    2005-12-07

    Using an extended Hubbard model, we calculate the many-body states of various transition-metal (TM) ions in the full spherical symmetry, thus accounting for the electronic correlations in TM oxides (TMOs). The influence of the symmetry of the bulk (cubic) crystal and of an (001) surface is described by a ligand-field procedure. The Slater integrals are fitted to gas phase data, EELS experiments, and low-lying states from ab initio theory. We present spectra of second harmonic generation from the bulk states and from the (001) surfaces.

  20. Efficient second harmonic generation of a diode-laser-pumped CW Nd:YAG laser using monolithic MgO:LiNbO3 external resonant cavities

    Science.gov (United States)

    Kozlovsky, William J.; Nabors, C. D.; Byer, Robert L.

    1988-01-01

    56-percent efficient external-cavity-resonant second-harmonic generation of a diode-laser pumped, CW single-axial-mode Nd:YAG laser is reported. A theory of external doubling with a resonant fundamental is presented and compared to experimental results for three monolithic cavities of nonlinear MgO:LiNbO3. The best conversion efficiency was obtained with a 12.5-mm-long monolithic ring cavity doubler, which produced 29.7 mW of CW, single-axial model 532-nm radiation from an input of 52.5 mW.

  1. Two-photon spectral fluorescence lifetime and second-harmonic generation imaging of the porcine cornea with a 12-femtosecond laser microscope

    Science.gov (United States)

    Batista, Ana; Breunig, Hans Georg; Uchugonova, Aisada; Morgado, António Miguel; König, Karsten

    2016-03-01

    Five dimensional microscopy with a 12-fs laser scanning microscope based on spectrally resolved two-photon autofluorescence lifetime and second-harmonic generation (SHG) imaging was used to characterize all layers of the porcine cornea. This setup allowed the simultaneous excitation of both metabolic cofactors, NAD(P)H and flavins, and their discrimination based on their spectral emission properties and fluorescence decay characteristics. Furthermore, the architecture of the stromal collagen fibrils was assessed by SHG imaging in both forward and backward directions. Information on the metabolic state and the tissue architecture of the porcine cornea were obtained with subcellular resolution, and high temporal and spectral resolutions.

  2. Three-dimensional current collapse imaging of AlGaN/GaN high electron mobility transistors by electric field-induced optical second-harmonic generation

    Science.gov (United States)

    Katsuno, Takashi; Manaka, Takaaki; Ishikawa, Tsuyoshi; Soejima, Narumasa; Uesugi, Tsutomu; Iwamoto, Mitsumasa

    2016-11-01

    Three-dimensional (3D) current collapse imaging of Schottky gate AlGaN/GaN high electron mobility transistor devices was achieved by a combination of two-dimensional (2D) and depth directional electric field-induced optical second-harmonic generation (EFISHG) measurements. EFISHG can detect the electric field produced by trapped carriers, which causes the current collapse. In the 2D measurement, the strong second-harmonic (SH) signals appeared within 1 μm from the gate edge on the drain side at 0.8 μs after the transition from the off- to no bias- state in both unpassivated and passivated samples. In the depth measurement, the SH signals were generated mainly from the AlGaN surface region of the unpassivated sample due to the presence of high-density trap sites in the AlGaN layer, and SH signals from bulk GaN region were also detected at 50 μs after the transition from the off- to no bias- state in the passivated sample. The origin of the traps is presumably the nitrogen vacancies in the GaN buffer layer.

  3. Effect of field modulation on the quasi-phase-matching for second harmonic generation in a two-dimensional nonlinear photonic crystal

    Science.gov (United States)

    Zhao, Li-Ming; Zhou, Yun-Song; Wang, Ai-Hua

    2017-02-01

    Second harmonic generation (SHG) in a two-dimensional (2D) nonlinear photonic crystal (NPC) with finite width along z-direction that is embedded in air is investigated, without adopting the traditional approximations such as a plane-wave approximation (PWA) and slowly varying amplitude approximation (SVAA). The so-called quasi-phase-matching (QPM) and the corresponding SHG conversion efficiency can be modulated significantly by the field of fundamental wave (FW). It is assumed that the incident light, along z-direction, is normally launched upon the surface of the sample, and QPM for different directions is investigated. It is found that the QPM shows significant differences, compared with the traditional QPM along the two different directions: in the direction of finite width of the sample, the peak value of SHG conversion efficiency is deviated from the traditional case and it gets to its peak values when the transmittance resonance occurs. However, in the other direction, the deviation from the traditional QPM arises from the field modulation of the second harmonic wave (SHW) and in this direction, it is investigated that the full width at half maximum of QPM is much wider than that in the direction of finite width of the sample. These results can be used to provide a theoretical guidance for achieving QPM SHG.

  4. Octave-Spanning Mid-IR Supercontinuum Generation with Ultrafast Cascaded Nonlinearities

    DEFF Research Database (Denmark)

    Zhou, Binbin; Guo, Hairun; Liu, Xing;

    2014-01-01

    An octave-spanning mid-IR supercontinuum is observed experimentally using ultrafast cascaded nonlinearities in an LiInS2 quadratic nonlinear crystal pumped with 70 fs energetic mid-IR pulses and cut for strongly phase-mismatched second-harmonic generation.......An octave-spanning mid-IR supercontinuum is observed experimentally using ultrafast cascaded nonlinearities in an LiInS2 quadratic nonlinear crystal pumped with 70 fs energetic mid-IR pulses and cut for strongly phase-mismatched second-harmonic generation....

  5. Generation of 9 MeV γ-rays by all-laser-driven Compton scattering with second-harmonic laser light.

    Science.gov (United States)

    Liu, Cheng; Golovin, Grigory; Chen, Shouyuan; Zhang, Jun; Zhao, Baozhen; Haden, Daniel; Banerjee, Sudeep; Silano, Jack; Karwowski, Hugon; Umstadter, Donald

    2014-07-15

    Gamma-ray photons with energy >9  MeV were produced when second-harmonic-generated laser light (3 eV) inverse-Compton-scattered from a counterpropagating relativistic (~450  MeV) laser-wakefield-accelerated electron beam. Two laser pulses from the same laser system were used: one to accelerate electrons and one to scatter. Since the two pulses play very different roles in the γ-ray generation process, and thus have different requirements, a novel laser system was developed. It separately and independently optimized the optical properties of the two pulses. This approach also mitigated the deleterious effects on beam focusing that generally accompany nonlinear optics at high peak-power levels.

  6. Dispersion of the second harmonic generation from CdGa{sub 2}X{sub 4} (X = S, Se) defect chalcopyrite: DFT calculations

    Energy Technology Data Exchange (ETDEWEB)

    Reshak, A.H. [New Technologies – Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Khan, Saleem Ayaz, E-mail: sayaz_usb@yahoo.com [New Technologies – Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic)

    2014-05-15

    Highlights: • Nonlinear optical properties of CdGa{sub 2}X{sub 4} (X = S, Se) were investigated. • The compounds have large uniaxial anisotropy and large negative birefringence. • The second order susceptibility and the first hyperpolarizability were calculated. • CdGa{sub 2}Se{sub 4} posses huge second harmonic generation. - Abstract: All electron full potential linear augmented plane wave method was used for calculating the nonlinear optical susceptibilities of CdGa{sub 2}X{sub 4} (X = S, Se) within the framework of density functional theory. The exchange correlation potential was solved by recently developed modified Becke and Johnson (mBJ) approximation. The crystal structure of CdGa{sub 2}S{sub 4} and CdGa{sub 2}Se{sub 4} reveals a large uniaxial dielectric anisotropy ensuing the birefringence of −0.036 and −0.066 which make it suitable for second harmonic generation. The second order susceptibility |χ{sub ijk}{sup (2)}(ω)| and microscopic first hyperpolarizability β{sub ijk}(ω) were calculated. The calculated |χ{sub 123}{sup (2)}(ω)| and |χ{sub 312}{sup (2)}(ω)| static values for the dominant components found to be 18.36 pm/V and 22.23 pm/V for CdGa{sub 2}S{sub 4} and CdGa{sub 2}Se{sub 4}. Both values shifted to be 60.12 pm/V and 108.86 pm/V at λ = 1064 nm. The calculated values of β{sub 123}(ω) is 6.47 × 10{sup −30} esu at static limit and 12.42 × 10{sup −30} esu at λ = 1064 nm for CdGa{sub 2}S{sub 4}, whereas it is 8.82 × 10{sup −30} esu at static limit and 20.51 × 10{sup −30} esu at λ = 1064 nm for CdGa{sub 2}Se{sub 4}. The evaluation of second order susceptibilities and first hyperpolarizabilties suggest that CdGa{sub 2}X{sub 4} possess huge second harmonic generation.

  7. Second-harmonic generation of solvated molecules using multiconfigurational self-consistent-field quadratic response theory and the polarizable continuum model

    Science.gov (United States)

    Frediani, Luca; Ågren, Hans; Ferrighi, Lara; Ruud, Kenneth

    2005-10-01

    We present the first implementation of the quadratic response function for multiconfigurational self-consistent-field wave functions of solvated molecules described by a polarizable continuum model employing a molecule-shaped cavity. We apply the methodology to the first hyperpolarizability β and, in particular, the second-harmonic generation process for a series of conjugated push-pull oligomers, as well as for para-nitroaniline. The effect of solvation on the dispersion of the hyperpolarizability and the change in the hyperpolarizability for increasing chain length of the oligomers in vacuum and in solution is considered. The effect of a correlated description is analyzed by comparing the Hartree-Fock hyperpolarizabilities to the multiconfigurational self-consistent-field hyperpolarizabilities. The effect of geometry relaxation in the solvent on the properties of the solvated molecules are also investigated.

  8. Manifestation of electron-phonon interactions in IR-induced second harmonic generation in a sulphide glass-ceramic with {beta}-GeS{sub 2} microcrystallites

    Energy Technology Data Exchange (ETDEWEB)

    Kityk, I.V. [Institute of Physics, J. Dlugosz University Czestochowa, Al. Armii Krajowej 13/15, Czestochowa (Poland)]. E-mail: i.kityk@ajd.czest.pl; Guignard, M. [UMR CNRS 6226 Sciences Chimiques de Rennes, Universite de Rennes 1, 35000 Rennes (France); Nazabal, V. [UMR CNRS 6226 Sciences Chimiques de Rennes, Universite de Rennes 1, 35000 Rennes (France); Zhang, X.H. [UMR CNRS 6226 Sciences Chimiques de Rennes, Universite de Rennes 1, 35000 Rennes (France); Troles, J. [UMR CNRS 6226 Sciences Chimiques de Rennes, Universite de Rennes 1, 35000 Rennes (France); Smektala, F. [UMR CNRS 6226 Sciences Chimiques de Rennes, Universite de Rennes 1, 35000 Rennes (France); Sahraoui, B. [Laboratoire POMA, Universite d' Angers Bld. Lavouisier 2, Angers, UMR CNRS 6136 (France); Boudebs, G. [Laboratoire POMA, Universite d' Angers Bld. Lavouisier 2, Angers, UMR CNRS 6136 (France)

    2007-04-01

    The non-linear optical response of sulphide glass-containing {beta}-GeS{sub 2} microcrystallites, has been studied at a fundamental wavelength of {lambda}=5.5 {mu}m under additional irradiation by IR-pulses of {lambda}=3.7 {mu}m. A substantial increase of the non-linear susceptibility with IR-power and size of the microcrystallites has been found. Molecular dynamics calculations linked to quantum chemical calculations show that this effect could be explained by substantial contributions of the microcrystallite interfaces and due to the phonon sub-system. The role of anharmonic electron-phonon effects is experimentally confirmed by the observation of an optimal delay of 8 ps between the pump laser pulses at 3.7 {mu}m and the probing laser pulses at 5.5 {mu}m, which generate the observed second harmonic signal.

  9. Enhancement in second harmonic generation efficiency, laser damage threshold and optical transparency of Mn 2+ doped L-alanine crystals: A correlation with crystalline perfection

    Science.gov (United States)

    Kushwaha, S. K.; Rathee, S. P.; Maurya, K. K.; Bhagavannarayana, G.

    2011-08-01

    Effect on crystalline perfection, second harmonic generation (SHG) efficiency, laser damage threshold (LDT) and optical transparency due to Mn 2+ doping in L-alanine crystals has been investigated. The crystalline perfection of pure and doped crystals was evaluated by high-resolution X-ray diffractometry, which revealed the improvement in the crystalline perfection at low and moderate doping concentrations. At moderate and high concentrations, the Mn 2+ ions were found to be incorporated predominantly at the interstitial sites of the crystalline matrix. The actual incorporated amount of dopants in the crystals was analyzed by atomic absorption spectroscopy. The optical transparency, SHG efficiency, and laser damage threshold of the grown crystals with different concentrations of Mn 2+ were investigated. From these studies it is revealed that Mn 2+ doping lead to a considerable enhancement in the measured nonlinear optical properties with a correlation on crystalline perfection.

  10. Second Harmonic Generation Using an All-Fiber Q-Switched Yb-Doped Fiber Laser and MgO:c-PPLN

    Directory of Open Access Journals (Sweden)

    Chang-qing Xu

    2008-10-01

    Full Text Available We have experimentally demonstrated an efficient all-fiber passively Q-switched Yb-doped fiber laser with Samarium doped fiber as a saturable absorber. Average output power of 3.4 W at a repetition rate of 250 kHz and a pulse width of 1.1 microseconds was obtained at a pump power of 9.0 W. By using this fiber laser system and an MgO-doped congruent periodically poled lithium niobate (MgO:c-PPLN, second harmonic generation (SHG output at 532 nm was achieved at room temperature. The conversion efficiency is around 4.2% which agrees well with the theoretical simulation.

  11. Residual thermal stress of a mounted KDP crystal after cooling and its effects on second harmonic generation of a high-average-power laser

    Science.gov (United States)

    Su, Ruifeng; Liu, Haitao; Liang, Yingchun; Yu, Fuli

    2017-01-01

    Thermal problems are huge challenges for solid state lasers that are interested in high output power, cooling of the nonlinear optics is insufficient to completely solve the problem of thermally induced stress, as residual thermal stress remains after cooling, which is first proposed, to the best of our knowledge. In this paper a comprehensive model incorporating principles of thermodynamics, mechanics and optics is proposed, and it is used to study the residual thermal stress of a mounted KDP crystal after cooling process from mechanical perspective, along with the effects of the residual thermal stress on the second harmonic generation (SHG) efficiency of a high-average-power laser. Effects of the structural parameters of the mounting configuration of the KDP crystal on the residual thermal stress are characterized, as well as the SHG efficiency. The numerical results demonstrate the feasibility of solving the problems of residual thermal stress from the perspective on structural design of mounting configuration.

  12. Optical second harmonic generation measurements for investigating electron injection into a pentacene field effect transistor with Au source and drain electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Eunju; Manaka, Takaaki; Tamura, Ryosuke [Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1, O-okayama, Meguro-ku, Tokyo 152-8552 (Japan); Iwamoto, Mitsumasa [Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1, O-okayama, Meguro-ku, Tokyo 152-8552 (Japan)], E-mail: iwamoto@pe.titech.ac.jp

    2008-03-03

    The pentacene field effect transistors (FETs)' operation for the injection carrier was revealed by means of the drain current-elapsed time (I{sub ds}-t) and optical second harmonic generation (SHG) measurements. The charge carriers forming the conducting channel of pentacene FETs were mainly holes injected from the Au source electrode. Carrier injection from source and drain electrodes was followed by the carrier trapping, and the SHG signal modulated by the change in the electric field distribution between Au the source and drain electrodes was shown. In particular, at the off state of the FET, electron injection and succeeding trapping were suggested. Furthermore, hole injection assisted by trapped electrons was also suggested.

  13. Nonlinear optical rectification and second-harmonic generation in a semi-parabolic quantum well under intense laser field: Effects of electric and magnetic fields

    Science.gov (United States)

    Ungan, F.; Martínez-Orozco, J. C.; Restrepo, R. L.; Mora-Ramos, M. E.; Kasapoglu, E.; Duque, C. A.

    2015-05-01

    The effects of electric and magnetic fields on the nonlinear optical rectification and second harmonic generation coefficients related with intersubband transitions in a semi-parabolic quantum well under intense laser field are theoretically studied. The energy levels and corresponding wave functions are obtained by solving the conduction band Schrödinger-like equation in the parabolic approximation and the envelope function approach. Numerical calculations are presented for a typical GaAs/Ga1-xAlxAs quantum well. The results show that both the non-resonant intense laser field and the static external fields have significant influences on the magnitude and resonant peak energy positions of the coefficients under study.

  14. Ab initio study of the circular intensity difference in electric-field-induced second harmonic generation of chiral natural amino acids.

    Science.gov (United States)

    Rizzo, Antonio; Agren, Hans

    2013-01-28

    We present a systematic computational study of circular intensity difference (CID) in electric-field-induced second harmonic generation (EFISHG) of some representative chiral natural amino acids (Alanine, Arginine, Aspartic Acid, Cysteine and Tryptophan), taking into account the electric-dipole, electric-quadrupole and magnetic-dipole interactions. The calculations are performed by applying cubic response theory at both Hartree-Fock and Density Functional theory levels, the latter with the popular Becke-three parameters, Lee, Yang and Parr (B3LYP) functional. Special focus is given to the basis set, electron correlation and origin dependence of the properties. The full set of molecular parameters defined by Lam and Thirunamachandran in their reference theoretical paper published in 1982 [J. Chem. Phys., 1982, 77, 3810] is obtained and discussed. This permits the prediction of the CID observable for different possible experimental setups.

  15. The nonlinear optical rectification and second harmonic generation in asymmetrical Gaussian potential quantum well: Effects of hydrostatic pressure, temperature and magnetic field

    Science.gov (United States)

    Liu, Xin; Zou, LiLi; Liu, Chenglin; Zhang, Zhi-Hai; Yuan, Jian-Hui

    2016-03-01

    In the present work, the effects of hydrostatic pressure, temperature, and magnetic field on the nonlinear optical rectification (OR) and second-harmonic generation (SHG) in asymmetrical Gaussian potential quantum well (QW) have been investigated theoretically. Here, the expressions for the optical properties are calculated by the compact-density-matrix approach and iterative method. Simultaneously, the energy eigenvalues and their corresponding eigenfunctions have been obtained by using the finite difference method. The energy eigenvalues and the shape of the confined potential are modulated by the hydrostatic pressure, temperature, and magnetic field. So the results of a number of numerical experiments indicate that the nonlinear OR and SHG strongly depends on the hydrostatic pressure, temperature, and magnetic field. This gives a new degree of freedom in various device applications based on the intersubband transitions of electrons.

  16. Nonlinear spectral imaging of human normal skin, basal cell carcinoma and squamous cell carcinoma based on two-photon excited fluorescence and second-harmonic generation

    Science.gov (United States)

    Xiong, S. Y.; Yang, J. G.; Zhuang, J.

    2011-10-01

    In this work, we use nonlinear spectral imaging based on two-photon excited fluorescence (TPEF) and second harmonic generation (SHG) for analyzing the morphology of collagen and elastin and their biochemical variations in basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and normal skin tissue. It was found in this work that there existed apparent differences among BCC, SCC and normal skin in terms of their thickness of the keratin and epithelial layers, their size of elastic fibers, as well as their distribution and spectral characteristics of collagen. These differences can potentially be used to distinguish BCC and SCC from normal skin, and to discriminate between BCC and SCC, as well as to evaluate treatment responses.

  17. Efficient broadband 400  nm noncollinear second-harmonic generation of chirped femtosecond laser pulses in BBO and LBO.

    Science.gov (United States)

    Gobert, O; Mennerat, G; Maksimenka, R; Fedorov, N; Perdrix, M; Guillaumet, D; Ramond, C; Habib, J; Prigent, C; Vernhet, D; Oksenhendler, T; Comte, M

    2014-04-20

    We report on 400 nm broadband type I frequency doubling in a noncollinear geometry with pulse-front-tilted and chirped femtosecond pulses (λ =800  nm; Fourier transform limited pulse duration, 45 fs). With moderate power densities (2 to 10  GW/cm2) thus avoiding higher-order nonlinear phenomena, the energy conversion efficiency was up to 65%. Second-harmonic pulses of Fourier transform limited pulse duration shorter than the fundamental wave were generated, exhibiting good beam quality and no pulse-front tilt. High energy (20 mJ/pulse) was produced in a 40 mm diameter and 6 mm thick LBO crystal. To the best of our knowledge, this is the first demonstration of this optical configuration with sub-100-fs pulses. Good agreement between experimental results and simulations is obtained.

  18. Growth and Second-Harmonic Generation Properties of Tm3+, Yb3+, Bi3+ and Li+ Doped GdCa4O(BO3)3 Crystals

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shu-Jun; CHENG Zhen-Xiang; ZHANG Shao-Jun; LIU Jun-Hai; HAN Jian-Ru; WANG Ji-Yang; CHEN Huan-Chu

    2001-01-01

    The rare-earth ions (Yb3+, Tm3+) and Li+, Bi3+ ions doped GdCa4O(BO3)3 crystals were grown using the Czochralski pulling method. The second-harmonic generation conversion efficiencies of the GdCOB:Yb and GdCOB:Tm crystals are 31.3% and 33.3%, respectively, while the undoped GdCOB crystal is 27.9%. The conversion efficiencies of Yb3+, Tm3+ doped GdCOB are improved by 12% and 19%, respectively, compared to that of the undoped one. The conversion efficiencies of Li+, Bi3+ doped GdCOB crystals are 33% and 38.3%,which are improved by 15% and 37% as compared to that of the undoped crystal. The results are discussed using the anion group theory.

  19. Second-harmonic imaging of semiconductor quantum dots

    DEFF Research Database (Denmark)

    Østergaard, John Erland; Bozhevolnyi, Sergey I.; Pedersen, Kjeld;

    2000-01-01

    Resonant second-harmonic generation is observed at room temperature in reflection from self-assembled InAlGaAs quantum dots grown on a GaAs (001) substrate. The detected second-harmonic signal peaks at a pump wavelength of similar to 885 nm corresponding to the quantum-dot photoluminescence maximum....... In addition, the second-harmonic spectrum exhibits another smaller but well-pronounced peak at 765 nm not found in the linear experiments. We attribute this peak to the generation of second-harmonic radiation in the AlGaAs spacer layer enhanced by the local symmetry at the quantum-dot interface. We further...... observe that second-harmonic images of the quantum-dot surface structure show wavelength-dependent spatial variations. Imaging at different wavelength is used to demonstrate second-harmonic generation from the semiconductor quantum dots. (C) 2000 American Institute of Physics....

  20. Image Formation in Second-Harmonic Near-Field Microscopy

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.; Lozovski, Valeri Z.; Pedersen, Kjeld;

    1999-01-01

    A macroscopic self-consistent approach that enables one to rigorously describe image formation in scanning near-field optical second-harmonic generation microscopy is developed. The self-consistent second-harmonic field is determined by taking into account both the linear and nonlinear contributi......A macroscopic self-consistent approach that enables one to rigorously describe image formation in scanning near-field optical second-harmonic generation microscopy is developed. The self-consistent second-harmonic field is determined by taking into account both the linear and nonlinear...

  1. Ultraviolet absorption spectroscopy in optically dense fireballs using broadband second-harmonic generation of a pulsed modeless dye laser.

    Science.gov (United States)

    Soo, Michael; Glumac, Nick

    2014-01-01

    Broadband frequency doubling of a modeless dye laser pulse is used to enable single-shot absorption spectroscopy in the ultraviolet for optically dense, energetic-materials fireball applications. Band widths of approximately 1-3 nm are generated in the 226 and 268 nm regions using a doubling crystal. Strong focusing of the fundamental beam onto the crystal is found to be sufficient to achieve 1-5% conversion efficiency with a pulse intensity sufficient to saturate the array detector even after 75% attenuation through the fireball. The technique is demonstrated with nitric oxide (NO) absorption in a gas cell and is then used to perform the first detection and temperature fitting of aluminum monofluoride (AlF) and magnesium monofluoride (MgF) in a fireball environment.

  2. Rb2Na(NO33: A Congruently Melting UV-NLO Crystal with a Very Strong Second-Harmonic Generation Response

    Directory of Open Access Journals (Sweden)

    Guohong Zou

    2016-04-01

    Full Text Available Crystals of congruently melting noncentrosymmetric (NCS mixed alkali metal nitrate, Rb2Na(NO33, have been grown through solid state reactions. The material possesses layers with NaO8 hexagonal bipyramids and NO3 triangular units. Rb+ cations are residing in the interlayer space. Each NaO8 hexagonal bipyramid shares its corners and edges with two and three NO3 units, respectively, in order to fulfill a highly dense stacking in the unit cell. The NaO8 groups share their six oxygen atoms in equatorial positions with three different NO3 groups to generate a NaO6-NO3 layer with a parallel alignment. The optimized arrangement of the NO3 groups and their high density in the structure together produce a strong second-harmonic generation (SHG response. Powder SHG measurements indicate that Rb2Na(NO33 has a strong SHG efficiency of five times that of KH2PO4 (KDP and is type I phase-matchable. The calculated average nonlinear optical (NLO susceptibility of Rb2Na(NO33 turns out to be the largest value among the NLO materials composed of only [NO3]− anion. In addition, Rb2Na(NO33 exhibits a wide transparency region ranging from UV to near IR, which suggests that the compound is a promising NLO material.

  3. Analysis of current-voltage characteristics of Au/pentacene/fluorine polymer/indium zinc oxide diodes by electric-field-induced optical second-harmonic generation

    Energy Technology Data Exchange (ETDEWEB)

    Nishi, Shohei; Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa, E-mail: iwamoto@pe.titech.ac.jp [Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 S3-33, O-okayama, Meguro-ku, Tokyo 152-8552 (Japan)

    2015-06-28

    By using electric-field-induced optical second-harmonic generation measurement coupled with the conventional current-voltage (I-V) measurement, we studied the carrier transport of organic double-layer diodes with a Au/pentacene/fluorine polymer (FP)/indium zinc oxide (IZO) structure. The rectifying I-V characteristics were converted into the I-E characteristics of the FP and pentacene layers. Results suggest a model in which Schottky-type electron injection from the IZO electrode to the FP layer governs the forward electrical conduction (V > 0), where the space charge electric field produced in the FP layer by accumulated holes at the pentacene/FP interface makes a significant contribution. On the other hand, Schottky-type injection by accumulated interface electrons from the pentacene layer to the FP layer governs the backward electrical conduction (V < 0). The electroluminescence generated from the pentacene layer in the region V > 0 verifies the electron transport across the FP layer, and supports the above suggested model.

  4. Broadband electric-field-induced LP01 and LP02 second harmonic generation in Xe-filled hollow-core PCF.

    Science.gov (United States)

    Ménard, Jean-Michel; Köttig, Felix; St J Russell, Philip

    2016-08-15

    Second harmonic (SH) generation with 300 fs pump pulses is reported in a xenon-filled hollow-core photonic crystal fiber (PCF) across which an external bias voltage is applied. Phase-matched intermodal conversion from a pump light in the LP01 mode to SH light in the LP02 mode is achieved at a particular gas pressure. Using periodic electrodes, quasi-phase-matched SH generation into the low-loss LP01 mode is achieved at a different pressure. The low linear dispersion of the gas enables phase-matching over a broad spectral window, resulting in a measured bandwidth of ∼10  nm at high pump energies. A conversion efficiency of ∼18%/mJ is obtained. Gas-filled anti-resonant-reflecting hollow-core PCF uniquely offers pressure-tunable phase-matching, ultra-broadband guidance, and a very high optical damage threshold, which hold great promise for efficient three-wave mixing, especially in difficult-to-access regions of the electromagnetic spectrum.

  5. ZnIO3(OH): a new layered noncentrosymmetric polar iodate--hydrothermal synthesis, crystal structure, and second-harmonic generating (SHG) properties.

    Science.gov (United States)

    Lee, Dong Woo; Kim, Saet Byeol; Ok, Kang Min

    2012-07-21

    A new noncentrosymmetric polar iodate material, ZnIO(3)(OH), has been hydrothermally synthesized as crystals and pure powders by using ZnO (or Zn(CH(3)CO(2))(2)·2H(2)O), HIO(3), and water. Single crystal X-ray diffraction was used to determine the crystal structure of the reported material. ZnIO(3)(OH) exhibits a layered structure that is composed of ZnO(6) and IO(3) polyhedra. Powder nonlinear optical (NLO) properties measurements on ZnIO(3)(OH) using 1064 nm radiation indicate the material has a second-harmonic generating (SHG) efficiency of approximately 20 times that of α-SiO(2). Additional SHG measurements reveal that the material is not phase-matchable (type 1). Infrared spectroscopy, elemental analysis, and thermogravimetric analysis for the reported compound are also presented. Crystal data: ZnIO(3)(OH), monoclinic, space group Cc (no. 9) with a = 4.67670(10) Å, b = 11.2392(4) Å, c = 6.3308(2) Å, β = 90.019(2)°, and Z = 4.

  6. Highly-sensitive detection of the lattice distortion in single bent ZnO nanowires by second-harmonic generation microscopy

    CERN Document Server

    Han, Xiaobo; Long, Hua; Hu, Hongbo; Chen, Jiawei; Wang, Bing; Lu, Peixiang

    2015-01-01

    Nanogenerators based on ZnO nanowires (NWs) realize the energy conversion at nanoscale, which are ascribed to the piezoelectric property caused by the lattice distortion of the ZnO NWs. The lattice distortion can significantly tune the electronic and optical properties, and requires a sensitive and convenient measurement. However, high-resolution transmission electron microscopy (HRTEM) technique provides a limited sensitivity of 0.01 nm on the variation of the lattice spacing and requires vacuum conditions. Here we demonstrate a highly-sensitive detection of the lattice distortion in single bent ZnO NWs by second-harmonic generation (SHG) microscopy. As the curvature of the single bent ZnO NW increases to 21 mm-1 (<4% bending distortion), it shows a significant decrease (~70%) in the SHG intensity ratio between perpendicular and parallel excitation polarization with respect to c-axis of ZnO NWs. Importantly, the extraordinary non-axisymmetrical SHG polarimetric patterns are also observed, indicating the t...

  7. Wavelength-Dependent Second Harmonic Generation Circular Dichroism for Differentiation of Col I and Col III Isoforms in Stromal Models of Ovarian Cancer Based on Intrinsic Chirality Differences.

    Science.gov (United States)

    Campbell, Kirby R; Campagnola, Paul J

    2017-03-02

    Extensive remodeling of the extracellular matrix (ECM) occurs in many epithelial cancers. For example, in ovarian cancer, upregulation of collagen isoform type III has been linked to invasive forms of the disease, and this change may be a potential biomarker. To examine this possibility, we implemented wavelength-dependent second harmonic generation circular dichroism (SHG-CD) imaging microscopy to quantitatively determine changes in chirality in ECM models comprised of different Col I/Col III composition. In these models, Col III was varied between 0 and 40%, and we found increasing Col III results in reduced net chirality, consistent with structural biology studies of Col I and III in tissues where the isoforms comingle in the same fibrils. We further examined the wavelength dependence of the SHG-CD to both optimize the response and gain insight into the underlying mechanism. We found using shorter SHG excitation wavelengths resulted in increased SHG-CD sensitivity, where this is consistent with the electric-dipole-coupled oscillator model suggested previously for the nonlinear chirality response from thin films. Moreover, the sensitivity is further consistent with the wavelength dependency of SHG intensity fit to a two-state model of the two-photon absorption in collagen. We also provide experimental calibration protocols to implement the SHG-CD modality on a laser scanning microscope. We last suggest that the technique has broad applicability in probing a wide range of diseased states with changes in collagen molecular structure.

  8. Analysis of interfacial energy states in Au/pentacene/polyimide/indium-zinc-oxide diodes by electroluminescence spectroscopy and electric-field-induced optical second-harmonic generation measurement

    Science.gov (United States)

    Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa

    2016-03-01

    By using electroluminescence (EL) spectroscopy and electric-field-induced optical second-harmonic generation (EFISHG) measurement, we analyzed interfacial energy states in Au/pentacene/polyimide/indium-zinc-oxide (IZO) diodes, to characterize the pentacene/polyimide interface. Under positive voltage application to the Au electrode with reference to the IZO electrode, the EFISHG showed that holes are injected from Au electrode, and accumulate at the pentacene/polyimide interface with the surface charge density of Qs = 3.8 × 10-7 C/cm2. The EL spectra suggested that the accumulated holes are not merely located in the pentacene but they are transferred to the interface states of polyimide. These accumulated holes distribute with the interface state density greater than 1012 cm-2 eV-1 in the range E = 1.5-1.8 and 1.7-2.4 eV in pentacene and in polyimide, respectively, under assumption that accumulated holes govern recombination radiation. The EL-EFISHG measurement is helpful to characterize organic-organic layer interfaces in organic devices and provides a way to analyze interface energy states.

  9. Efficient second harmonic generation of double-end diffusion-bonded Nd:YVO4 self-Raman laser producing 7.9 W yellow light.

    Science.gov (United States)

    Zhu, Haiyong; Duan, Yanmin; Zhang, Ge; Huang, Chenghui; Wei, Yong; Shen, Hongyuan; Zheng, Yiqun; Huang, Lingxiong; Chen, Zhenqiang

    2009-11-23

    A high power and efficient 588 nm yellow light is demonstrated through intracavity frequency doubling of an acousto-optic Q-switched self-frequency Raman laser. A 30-mm-length double-end diffusion-bonded Nd:YVO(4) crystal was utilized for efficient self-Raman laser operation by reducing the thermal effects and increasing the interaction length for the stimulated Raman scattering. A 15-mm-length LBO with non-critical phase matching (theta = 90 degrees, phi = 0 degrees) cut was adopted for efficient second-harmonic generation. The focus position of incident pump light and both the repetition rate and the duty cycle of the Q-switch have been optimized. At a repetition rate of 110 kHz and a duty cycle of 5%, the average power of 588 nm light is up to 7.93 W while the incident pump power is 26.5 W, corresponding to an overall diode-yellow conversion efficiency of 30% and a slope efficiency of 43%.

  10. Remarkable effect of Ni{sup 2+}doping on structural, second harmonic generation, optical, mechanical and dielectric properties of KDP single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Ganesh, V. [Department of Physics, Faculty of Science, King Khalid University, P.O. Box 9004, Abha 61413 (Saudi Arabia); Shkir, Mohd, E-mail: shkirphysics@gmail.com [Department of Physics, Faculty of Science, King Khalid University, P.O. Box 9004, Abha 61413 (Saudi Arabia); AlFaify, S.; Algarni, H. [Department of Physics, Faculty of Science, King Khalid University, P.O. Box 9004, Abha 61413 (Saudi Arabia); Abutalib, M.M. [Faculty of Science-AL Faisaliah, Campus, King Abdulaziz University, P.O. Box 80200, Jeddah 21589 (Saudi Arabia); Yahia, I.S. [Department of Physics, Faculty of Science, King Khalid University, P.O. Box 9004, Abha 61413 (Saudi Arabia); Nano-Science & Semiconductor Labs., Thin Film Lab., Department of Physics, Faculty of Education, Ain Shams University, Roxy, Cairo (Egypt)

    2016-06-15

    The nonlinear optical single crystals of pure and Ni{sup 2+} doped potassium dihydrogen phosphate (KDP) were successfully grown by slow evaporation solution growth technique. The effects of the addition of Ni{sup 2+} with different molar concentration have been studied by powder X-ray diffraction, FT-Raman, second harmonic generation, microscopic and dielectric studies. Its crystallinity was assessed by the FT-Raman technique and its surface, structural imperfections were recorded using high resolution microscope, which clearly reveals that the doping is showing considerable effect on the samples. The SHG measurements also carried out on pure and doped samples, which reveal the relative SHG efficiency has been enhanced due to doping. The optical activities were studied by UV–vis-NIR technique and reveals high optical transparency in doped samples. The remarkable enhancement in mechanical strength was observed due to doping. The enhanced dielectric constant and low dielectric loss confirms that the grown crystals with doping are superior to pure crystals and may be used in optoelectronic devices.

  11. Analysis of carrier behavior in C60/P(VDF-TrFE) double-layer capacitor by using electric-field-induced optical second-harmonic generation measurement

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Xiaojin [Department of Physical Electronics, Tokyo Institute of Technology 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552 (Japan); State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa, E-mail: iwamoto@pe.titech.ac.jp [Department of Physical Electronics, Tokyo Institute of Technology 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552 (Japan)

    2013-12-21

    By using displacement current measurement (DCM) and electric-field-induced optical second-harmonic generation (EFISHG) measurement, we studied the carrier behavior in the indium-tin oxide (ITO)/Poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE))/C60/Au(or Al) capacitors. Two DCM peaks appeared asymmetrically at around −35.5 V and +30.0 V in the dark. Correspondingly, the EFISHG response from the C60 layer was observed, but the peak positions were different with respect to DCM ones. The results show that the spontaneous polarization of the ferroelectric P(VDF-TrFE) polymeric layer directly affects the electric field in the C60 layer, and thus governs the carrier motion in this layer. As a result, the C60 layer serves like an insulator in the dark, while electrons and holes are captured and released at the interface in response to the turn-over of spontaneous polarization of ferroelectric layer. On the other hand, under white light illumination, C60 layer serves like a conductor due to the increase of photogenerated mobile carriers, and these carriers dominate the carrier motions therein. Our findings here will be helpful for analyzing carrier behaviors in organic electronic devices using ferroelectric polymers.

  12. Investigation of Electric Field–Induced Structural Changes at Fe-Doped SrTiO3 Anode Interfaces by Second Harmonic Generation

    Directory of Open Access Journals (Sweden)

    David Ascienzo

    2016-10-01

    Full Text Available We report on the detection of electric field–induced second harmonic generation (EFISHG from the anode interfaces of reduced and oxidized Fe-doped SrTiO3 (Fe:STO single crystals. For the reduced crystal, we observe steady enhancements of the susceptibility components as the imposed dc-voltage increases. The enhancements are attributed to a field-stabilized electrostriction, leading to Fe:Ti-O bond stretching and bending in Fe:Ti-O6 octahedra. For the oxidized crystal, no obvious structural changes are observed below 16 kV/cm. Above 16 kV/cm, a sharp enhancement of the susceptibilities occurs due to local electrostrictive deformations in response to oxygen vacancy migrations away from the anode. Differences between the reduced and oxidized crystals are explained by their relative oxygen vacancy and free carrier concentrations which alter internal electric fields present at the Pt/Fe:STO interfaces. Our results show that the optical SHG technique is a powerful tool for detecting structural changes near perovskite-based oxide interfaces due to field-driven oxygen vacancy migration.

  13. Characterization of Si(1 1 1){radical}(3) Multiplication-Sign {radical}(3)-(Au,In) surface by optical second-harmonic generation

    Energy Technology Data Exchange (ETDEWEB)

    Ignatovich, K.V. [Institute of Automation and Control Processes, 5 Radio Street, 690041 Vladivostok (Russian Federation); Zotov, A.V. [Institute of Automation and Control Processes, 5 Radio Street, 690041 Vladivostok (Russian Federation); School of Natural Sciences, Far Eastern Federal University, 690950 Vladivostok (Russian Federation); Department of Electronics, Vladivostok State University of Economics and Service, 690600 Vladivostok (Russian Federation); Saranin, A.A. [Institute of Automation and Control Processes, 5 Radio Street, 690041 Vladivostok (Russian Federation); School of Natural Sciences, Far Eastern Federal University, 690950 Vladivostok (Russian Federation)

    2012-03-01

    We investigated the change of optical second harmonic generation (SHG) intensity in the course of Si(1 1 1){radical}(3) Multiplication-Sign {radical}(3)-(Au,In) surface formation and during subsequent In island growth on this surface. The Si(1 1 1){radical}(3) Multiplication-Sign {radical}(3)-(Au,In) surface is essentially a modified Si(1 1 1)-{alpha}-{radical}(3) Multiplication-Sign {radical}(3)-Au surface in which the domain-wall network (characteristic of the original surface) is completely eliminated due to In adsorption. This surface shows up as the one having homogeneous highly ordered atomic structure. Its formation is accompanied by the extremely high (namely, tenfold) increase of the SHG signal. It was recognized that this increase is associated with an extraordinary high long-range atomic ordering of the Si(1 1 1){radical}(3) Multiplication-Sign {radical}(3)-(Au,In) surface, while its other peculiar features, developing the 2D electron gas system and occurrence of the 2D gas of mobile adatoms on it, produce minor effects. Growth of random In islands on Si(1 1 1){radical}(3) Multiplication-Sign {radical}(3)-(Au,In) at RT In deposition leads to the decrease of SHG signal indicating its sensitivity to the surface inhomogeneity not only in atomic scale but in the mesascopic scale also.

  14. Second-harmonic generation microscopy used to evaluate the effect of the dimethyl sulfoxide in the cryopreservation process in collagen fibers of differentiated chondrocytes

    Science.gov (United States)

    Andreoli-Risso, M. F.; Duarte, A. S. S.; Ribeiro, T. B.; Bordeaux-Rego, P.; Luzo, A.; Baratti, M. O.; Adur, J.; de Thomaz, A. A.; Pelegati, V. B.; Carvalho, H. F.; Cesar, C. L.; Kharmadayan, P.; Costa, F. F.; Olalla-Saad, S. T.

    2012-03-01

    Cartilaginous lesions are a significant public health problem and the use of adult stem cells represents a promising therapy for this condition. Cryopreservation confers many advantages for practitioners engaged in cell-based therapies. However, conventional slow freezing has always been associated with damage and mortality due to intracellular ice formation, cryoprotectant toxicity, and dehydration. The aim of this work is to observe the effect of the usual Dimethyl Sulfoxide (DMSO) cryopreservation process on the architecture of the collagen fiber network of chondrogenic cells from mesenchymal stem cells by Second Harmonic Generation (SHG) microscopy. To perform this study we used Mesenchymal Stem Cells (MSC) derived from adipose tissue which presents the capacity to differentiate into other lineages such as osteogenic, adipogenic and chondrogenic lineages. Mesenchymal stem cells obtained after liposuction were isolated digested by collagenase type I and characterization was carried out by differentiation of mesodermic lineages, and flow cytometry using specific markers. The isolated MSCs were cryopreserved by the DMSO technique and the chondrogenic differentiation was carried out using the micromass technique. We then compared the cryopreserved vs non-cryopreserved collagen fibers which are naturally formed during the differentiation process. We observed that noncryopreserved MSCs presented a directional trend in the collagen fibers formed which was absent in the cryopreserved MSCs. We confirmed this trend quantitatively by the aspect ratio obtained by Fast Fourier Transform which was 0.76 for cryopreserved and 0.52 for non-cryopreserved MSCs, a statistical significant difference.

  15. Determination of the spectral dependence of reduced scattering and quantitative second-harmonic generation imaging for detection of fibrillary changes in ovarian cancer

    Science.gov (United States)

    Campbell, Kirby R.; Tilbury, Karissa B.; Campagnola, Paul J.

    2015-03-01

    Here, we examine ovarian cancer extracellular matrix (ECM) modification by measuring the wavelength dependence of optical scattering measurements and quantitative second-harmonic generation (SHG) imaging metrics in the range of 800-1100 nm in order to determine fibrillary changes in ex vivo normal ovary, type I, and type II ovarian cancer. Mass fractals of the collagen fiber structure is analyzed based on a power law correlation function using spectral dependence measurements of the reduced scattering coefficient μs' where the mass fractal dimension is related to the power. Values of μs' are measured using independent methods of determining the values of μs and g by on-axis attenuation measurements using the Beer-Lambert Law and by fitting the angular distribution of scattering to the Henyey-Greenstein phase function, respectively. Quantitativespectral SHG imaging on the same tissues determines FSHG/BSHG creation ratios related to size and harmonophore distributions. Both techniques probe fibril packing order, but the optical scattering probes structures of sizes from about 50-2000 nm where SHG imaging - although only able to resolve individual fibers - builds contrast from the assembly of fibrils. Our findings suggest that type I ovarian tumor structure has the most ordered collagen fibers followed by normal ovary then type II tumors showing the least order.

  16. Characterization of collagen fibers by means of texture analysis of second harmonic generation images using orientation-dependent gray level co-occurrence matrix method.

    Science.gov (United States)

    Hu, Wenyan; Li, Hui; Wang, Chunyou; Gou, Shanmiao; Fu, Ling

    2012-02-01

    Collagen is the most prominent protein in the human body, making up 30% of the total protein content. Quantitative studies have shown structural differences between collagen fibers of the normal and diseased tissues, due to the remodeling of the extracellular matrix during the pathological process. The dominant orientation, which is an important characteristic of collagen fibers, has not been taken into consideration for quantitative collagen analysis. Based on the conventional gray level co-occurrence matrix (GLCM) method, the authors proposed the orientation-dependent GLCM (OD-GLCM) method by estimating the dominant orientation of collagen fibers. The authors validated the utility of the OD-GLCM method on second harmonic generation (SHG) microscopic images of tendons from rats with different ages. Compared with conventional GLCM method, the authors' method has not only improved the discrimination between different tissues but also provided additional texture information of the orderliness of collagen fibers and the fiber size. The OD-GLCM method was further applied to the differentiation of the preliminary SHG images of normal and cancerous human pancreatic tissues. The combination of SHG microscopy and the OD-GLCM method might be helpful for the evaluation of diseases marked with abnormal collagen morphology.

  17. Characterization of collagen fibers by means of texture analysis of second harmonic generation images using orientation-dependent gray level co-occurrence matrix method

    Science.gov (United States)

    Hu, Wenyan; Li, Hui; Wang, Chunyou; Gou, Shanmiao; Fu, Ling

    2012-02-01

    Collagen is the most prominent protein in the human body, making up 30% of the total protein content. Quantitative studies have shown structural differences between collagen fibers of the normal and diseased tissues, due to the remodeling of the extracellular matrix during the pathological process. The dominant orientation, which is an important characteristic of collagen fibers, has not been taken into consideration for quantitative collagen analysis. Based on the conventional gray level co-occurrence matrix (GLCM) method, the authors proposed the orientation-dependent GLCM (OD-GLCM) method by estimating the dominant orientation of collagen fibers. The authors validated the utility of the OD-GLCM method on second harmonic generation (SHG) microscopic images of tendons from rats with different ages. Compared with conventional GLCM method, the authors' method has not only improved the discrimination between different tissues but also provided additional texture information of the orderliness of collagen fibers and the fiber size. The OD-GLCM method was further applied to the differentiation of the preliminary SHG images of normal and cancerous human pancreatic tissues. The combination of SHG microscopy and the OD-GLCM method might be helpful for the evaluation of diseases marked with abnormal collagen morphology.

  18. Specific Na+ and K+ Cation Effects on the Interfacial Water Molecules at the Air/Aqueous Salt Solution Interfaces Probed with Non-resonant Second Harmonic Generation (SHG)

    CERN Document Server

    Bian, Hong-tao; Guo, Yuan; Wang, Hong-fei

    2008-01-01

    Here we report the polarization dependent non-resonant second harmonic generation (SHG) measurement of the interfacial water molecules at the aqueous solution of the following salts: NaF, NaCl, NaBr, KF, KCl, and KBr. Through quantitative polarization analysis of the SHG data,the orientational parameter D value and the relative surface density of the interfacial water molecules at these aqueous solution surfaces were determined. From these results we found that addition of each of the six salts caused increase of the thickness of the interfacial water layer at the surfaces to a certain extent. Noticeably, both the cations and the anions contributed to the changes, and the abilities to increase the thickness of the interfacial water layer were in the following order: KBr > NaBr > KCl > NaCl ~ NaF > KF. Since these changes can not be factorized into individual anion and cation contributions, there are possible ion pairing or association effects, especially for the NaF case. We also found that the orientational ...

  19. Effect of Strontium Ion on the Growth and Second-Harmonic Generation Properties of GdCa4O(BO3)3 Crystal

    Institute of Scientific and Technical Information of China (English)

    张树君; 程振祥; 刘均海; 韩建儒; 王继扬; 邵宗书; 陈焕矗

    2001-01-01

    Large sized and optical quality GdCa4O(BO3)3 (GdCOB) crystal with calcium partially substituted by strontium (Sr) ions was grown for the first time. The x-ray powder diffraction shows that the Sr ion has an effect on the cell parameters of the GdCOB crystal Second-harmonic generation (SHG) experiments were performed on the Sr:GdCOB and GdCOB crystals along the spatial phase-matching direction. The results show that the cw green laser output power is 1.04 W when the laser diode pump power is 10 W in the Nd:YVO4/Sr:GdCOB intracavity laser. Considering the slope efficiency of Nd:YVO4 and the fundamental laser in cavity, the intracavity SHG conversion efficiency of the GdCOB crystal is 21% while it is 24% for the Sr:GdCOB crystal, the SHG conversion efficiency is improved by 14%. The effect of the Sr ions on the nonlinearity of the GdCOB crystal is also discussed by using the anion group theory.

  20. Two-photon-excited autofluorescence and second-harmonic generation microscopy for the visualization of penetration of TiO2 and ZnO nanoparticles into human tooth tissue ex vivo

    Science.gov (United States)

    Trunina, Natalia A.; Popov, Alexey P.; Lademann, Jürgen; Tuchin, Valery V.; Myllylä, Risto; Darvin, Maxim E.

    2012-06-01

    Penetration of nanoparticles into tooth tissues is of significant interest in solving problems related to reduction of tooth sensitivity, enamel strengthening and restoration and cosmetic bleaching. In this work we demonstrate two-photonexcited autofluorescence and second-harmonic generation microscopy for visualization of penetration of TiO2 and ZnO nanoparticles into tooth tissues.

  1. Optical system design of a speckle-free ultrafast Red-Green-Blue (RGB) source based on angularly multiplexed second harmonic generation from a TZDW source

    Science.gov (United States)

    Yao, Yuhong; Knox, Wayne H.

    2015-03-01

    We report the optical system design of a novel speckle-free ultrafast Red-Green-Blue (RGB) source based on angularly multiplexed simultaneous second harmonic generation from the efficiently generated Stokes and anti-Stokes pulses from a commercially available photonic crystal fiber (PCF) with two zero dispersion wavelengths (TZDW). We describe the optimized configuration of the TZDW fiber source which supports excitations of dual narrow-band pulses with peak wavelengths at 850 nm, 1260 nm and spectral bandwidths of 23 nm, 26 nm, respectively within 12 cm of commercially available TZDW PCF. The conversion efficiencies are as high as 44% and 33% from the pump source (a custom-built Yb:fiber master-oscillator-power-amplifier). As a result of the nonlinear dynamics of propagation, the dual pulses preserve their ultrashort pulse width (with measured autocorrelation traces of 200 fs and 227 fs,) which eliminates the need for dispersion compensation before harmonic generation. With proper optical design of the free-space harmonic generation system, we achieve milli-Watt power level red, green and blue pulses at 630 nm, 517 nm and 425 nm. Having much broader spectral bandwidths compared to picosecond RGB laser sources, the source is inherently speckle-free due to the ultra-short coherence length (99.4% excitation purities of the three primaries, leading to the coverage of 192% NTSC color gamut (CIE 1976). The reported RGB source features a very simple system geometry, its potential for power scaling is discussed with currently available technologies.

  2. Second Harmonic Generation, Electrooptical Pockels Effect, and Static First-Order Hyperpolarizabilities of 2,2′-Bithiophene Conformers: An HF, MP2, and DFT Theoretical Investigation

    Directory of Open Access Journals (Sweden)

    Andrea Alparone

    2013-01-01

    Full Text Available The static and dynamic electronic (hyperpolarizabilities of the equilibrium conformations of 2,2′-bithiophene (anti-gauche and syn-gauche were computed in the gas phase. The calculations were carried out using Hartree-Fock (HF, Møller-Plesset second-order perturbation theory (MP2, and density functional theory methods. The properties were evaluated for the second harmonic generation (SHG, and electrooptical Pockels effect (EOPE nonlinear optical processes at the typical λ=1064 nm of the Nd:YAG laser. The anti-gauche form characterized by the S–C2–C2′–S dihedral angle of 137° (MP2/6-311G** is the global minimum on the potential energy surface, whereas the syn-gauche rotamer (S–C2–C2′–S = 48°, MP2/6-311G** lies ca. 0.5 kcal/mol above the anti-gauche form. The structural properties of the gauche structures are rather similar to each other. The MP2 electron correlation effects are dramatic for the first-order hyperpolarizabilities of the 2,2′-bithiophenes, decreasing the HF values by ca. a factor of three. When passing from the anti-gauche to the syn-gauche conformer, the static and frequency-dependent first-order hyperpolarizabilities increase by ca. a factor of two. Differently, the electronic polarizabilities and second-order hyperpolarizabilities of these rotamers are rather close to each other. The syn-gauche structure could be discriminated from the anti-gauche one through its much more intense SHG and EOPE signals.

  3. Second-Harmonic Generation in Vertically Coupled InAs/GaAs Quantum Dots with a Gaussian Potential Distribution: Combined Effects of Electromagnetic Fields, Pressure, and Temperature

    Science.gov (United States)

    Ben Mahrsia, R.; Choubani, M.; Bouzaiene, L.; Maaref, H.

    2015-08-01

    Simulation of quantum dots (QD) is usually performed on the basis of abrupt changes between neighboring materials. In practice, it is not possible to construct such QD because in a real structure the interface between two adjacent materials is not a step. In the work discussed in this paper, vertically coupled InAs/GaAs quantum dots (VCQD) with a non-abrupt change between two neighboring materials are considered. A potential function in the form of a Gaussian distribution was used to show this effect. We also focused on studying the effect of structure, applied electric ( F) and magnetic ( B) fields, pressure ( P), and temperature ( T) on second-harmonic generation (SHG). The analytical expression for SHG was investigated theoretically by use of the density matrix approach, the effective mass, and the finite-difference method (FDM). It was found that the major resonant peak value of SHG is a non-monotonic function of the barrier width ( L B). Moreover, the major resonant peak of SHG is blue-shifted (red-shifted) and its magnitude increases (decreases) monotonically with increasing temperature (pressure). The results obtained also show that the magnitude and position of the resonant peaks of SHG are affected by changes in external conditions, for example applied electric and magnetic fields, structural dimensions of the coupled QD system, and relaxation time ( T 0). Calculations also show that SHG in a VCQD structure with a non-abrupt potential change can be controlled and optimized by appropriate choice of structural dimensions and the external conditions mentioned above.

  4. Differentiation of Col I and Col III isoforms in stromal models of ovarian cancer by analysis of second harmonic generation polarization and emission directionality.

    Science.gov (United States)

    Tilbury, Karissa; Lien, Chi-Hsiang; Chen, Shean-Jen; Campagnola, Paul J

    2014-01-21

    A profound remodeling of the extracellular matrix occurs in many epithelial cancers. In ovarian cancer, the minor collagen isoform of Col III becomes upregulated in invasive disease. Here we use second harmonic generation (SHG) imaging microscopy to probe structural differences in fibrillar models of the ovarian stroma comprised of mixtures of Col I and III. The SHG intensity and forward-backward ratios decrease with increasing Col III content, consistent with decreased phasematching due to more randomized structures. We further probe the net collagen α-helix pitch angle within the gel mixtures using what is believed to be a new pixel-based polarization-resolved approach that combines and extends previous analyses. The extracted pitch angles are consistent with those of peptide models and the method has sufficient sensitivity to differentiate Col I from the Col I/Col III mixtures. We further developed the pixel-based approach to extract the SHG signal polarization anisotropy from the same polarization-resolved image matrix. Using this approach, we found that increased Col III results in decreased alignment of the dipole moments within the focal volume. Collectively, the SHG measurements and analysis all indicate that incorporation of Col III results in decreased organization across several levels of collagen organization. Furthermore, the findings suggest that the collagen isoforms comingle within the same fibrils, in good agreement with ultrastructural data. The pixel-based polarization analyses (both excitation and emission) afford determination of structural properties without the previous requirement of having well-aligned fibers, and the approaches should be generally applicable in tissue.

  5. Molecular ordering of PAH/MA-co-DR13 azopolymer layer-by-layer films probed by second-harmonic generation

    Science.gov (United States)

    Silva, Heurison S.; Lopes, Fábio J. S.; Miranda, Paulo B.

    2016-09-01

    Molecular orientation within azopolymer thin films is important for their nonlinear optical properties and photonic applications. We have used optical second-harmonic generation (SHG) to study the molecular orientation of Layer-by-Layer (LbL) films of a cationic polyelectrolyte (poly(allylamine hydrochloride)) and an anionic polyelectrolyte containing azochromophore side groups (MA-co-DR13) on a glass substrate. The SHG measurements indicate that there is a preferential orientation of the azochromophores in the film, leading to a significant optical nonlinearity. However, both the signal strength and its anisotropy are not homogeneous throughout the sample, indicating the presence of large orientational domains. This is corroborated with Brewster angle microscopy. The average SHG signal does not increase with film thickness, in contrast to some reports in the literature, indicating an independent orientational order for successive bilayers. Analyzing the SHG signal as a function of the input and output polarizations, a few parameters of the azochromophore orientational distribution can be deduced. Fitting the SHG signal to a simple model distribution, we have concluded that the chromophores have an angular distribution with a slight in-plane anisotropy and a mean polar angle ranging from 45° to 80° with respect to substrate normal direction, with a relatively large width of about 25°. These results show that SHG is a powerful technique for a detailed investigation of the molecular orientation in azopolymer LbL films, allowing a deeper understanding of their self-assembling mechanism and nonlinear optical properties. The inhomogeneity and anisotropy of these films may have important consequences for their applications in nonlinear optical devices.

  6. Resonant plasmonic nanoparticles for multicolor second harmonic imaging

    Science.gov (United States)

    Accanto, Nicolò; Piatkowski, Lukasz; Hancu, Ion M.; Renger, Jan; van Hulst, Niek F.

    2016-02-01

    Nanoparticles capable of efficiently generating nonlinear optical signals, like second harmonic generation, are attracting a lot of attention as potential background-free and stable nano-probes for biological imaging. However, second harmonic nanoparticles of different species do not produce readily distinguishable optical signals, as the excitation laser mainly defines their second harmonic spectrum. This is in marked contrast to other fluorescent nano-probes like quantum dots that emit light at different colors depending on their sizes and materials. Here, we present the use of resonant plasmonic nanoparticles, combined with broadband phase-controlled laser pulses, as tunable sources of multicolor second harmonic generation. The resonant plasmonic nanoparticles strongly interact with the electromagnetic field of the incident light, enhancing the efficiency of nonlinear optical processes. Because the plasmon resonance in these structures is spectrally narrower than the laser bandwidth, the plasmonic nanoparticles imprint their fingerprints on the second harmonic spectrum. We show how nanoparticles of different sizes produce different colors in the second harmonic spectra even when excited with the same laser pulse. Using these resonant plasmonic nanoparticles as nano-probes is promising for multicolor second harmonic imaging while keeping all the advantages of nonlinear optical microscopy.

  7. Sub-20 fs energetic near-IR pulses generated with cascaded soliton compression in short lithium niobate crystals

    DEFF Research Database (Denmark)

    Zhou, Binbin; Chong, Andy; Wise, Frank W.;

    2011-01-01

    We show experimentally that sub-20 fs near-infrared pulses can be generated through soliton compression of energetic femtosecond pulses.e compression relies on cascaded type-0 second-harmonic generation in a just 1 mm long lithium niobate crystal....

  8. Three-color entanglement generated by single-pass cascaded sum-frequency processes

    Science.gov (United States)

    Yu, Youbin; Ji, Fengmin; Shi, Zhongtao; Wang, HuaiJun; Zhao, Junwei; Wang, Yajuan

    2017-03-01

    Three-color continuous-variable (CV) entangled beams can be produced by single-pass cascaded sum-frequency processes of third-harmonic generation by quasi-phase-matching technique in only one optical superlattice. Firstly, second-harmonic field is generated by the first double-frequency process of the fundamental field. Then, the third-harmonic field can be generated by the second cascaded sum-frequency process between the second-harmonic and the fundamental fields by quasi-phase-matching technique in the same optical superlattice. By using the quantum stochastic method, we investigated the conversion dynamics of the cascaded sum-frequency processes and the quantum correlation nature among the fundamental, second-harmonic, and third-harmonic fields. The results show that the higher conversion efficiency of third-harmonic generation can be achieved with the larger nonlinear coupling parameter of the second cascaded sum-frequency process. We also show that the fundamental, second-, and third-harmonic beams are CV entangled with each other according to the necessary and sufficient CV entanglement criterion. This scheme of three-color entanglement generation without involving optical cavity is easy to realize in experiment. Moreover, the three-color entangled beams are separated by an octave in frequency which has potential applications in quantum communication and computation networks.

  9. High-resolution second harmonic optical coherence tomography

    Science.gov (United States)

    Jiang, Yi; Tomov, Ivan V.; Wang, Yimin; Chen, Zhongping

    2005-04-01

    A high-resolution Second Harmonic Optical Coherence Tomography (SH-OCT) system is demonstrated using a spectrum broadened femtosecond Ti:sapphire laser. An axial resolution of 4.2 μm at the second harmonic wave center wavelength of 400 nm has been achieved. Because the SH-OCT system uses the second harmonic generation signals that strongly depend on the orientation, polarization and local symmetry properties of chiral molecules, this technique provides unique contrast enhancement to conventional optical coherence tomography. The system is applied to image biological tissues like the rat-tail tendon. Images of highly organized collagen fibrils in the rat-tail tendon have been demonstrated.

  10. Generation of more than 300 mW diffraction-limited light at 405 nm by second-harmonic generation of a tapered diode laser with external cavity feedback

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Holm, J.; Sumpf, B.;

    2007-01-01

    We have constructed a blue laser source consisting of a single-frequency tapered diode laser with external cavity feedback that is frequency doubled by a quasi-phase matched KTP (PPKTP) in a bowtie ring cavity and extract more than 360 mW of power at 405 nm. The conversion efficiency from fundame...... fundamental laser power to second harmonic power is 35 %, while it is 64 % from coupled fundamental power to extracted blue light. Thermal effects and gray tracking set an upper limit on the amount of generated blue light....

  11. Generating energetic few-cycle pulses at 800 nm using soliton compression with type 0 cascaded quadratic interaction in lithium niobate

    DEFF Research Database (Denmark)

    Bache, Morten; Zhou, Binbin; Chong, A.

    2010-01-01

    We show that ultra-short few-cycle pulses can be generated through soliton compression of energetic femtosecond pulses from a Ti:Sapphire regenerative amplifier. The compression relies on cascaded type 0 second-harmonic generation in mm-length lithium niobate crystals.......We show that ultra-short few-cycle pulses can be generated through soliton compression of energetic femtosecond pulses from a Ti:Sapphire regenerative amplifier. The compression relies on cascaded type 0 second-harmonic generation in mm-length lithium niobate crystals....

  12. Polar asymmetry of La{sub (1−δ)}Al{sub (1+δ)}O{sub 3}/SrTiO{sub 3} heterostructures probed by optical second harmonic generation

    Energy Technology Data Exchange (ETDEWEB)

    Rubano, Andrea; De Luca, Gabriele; Marrucci, Lorenzo; Paparo, Domenico, E-mail: domenico.paparo@spin.cnr.it [CNR-SPIN and Università Federico II, Monte S. Angelo, via Cintia, Napoli 80126 (Italy); Schubert, Jürgen [Peter Grünberg Institute (PGI9-IT), JARA- Fundamentals of Future Information Technology, Research Centre Jülich, Jülich D-52425 (Germany); Wang, Zhe; Zhu, Shaobo [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States); Schlom, Darrell G. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States); Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853 (United States)

    2015-09-07

    By combining transport measurements and optical second harmonic generation, we have investigated heterostructures formed between crystalline thin films of LaAlO{sub 3}, with varying stoichiometry and TiO{sub 2}-terminated SrTiO{sub 3}(001) substrates. Optical second harmonic generation directly probes the polarity of these heterostructures, thus complementing the transport data. The stoichiometry and the growth temperature are found to be critical parameters for controlling both the interfacial conductivity and the heterostructure polarity. In agreement with the previous work, all of the samples display an insulator-to-metal transition in the Al-reach region, with the conductivity first increasing and then saturating at the highest Al/La ratios. The second harmonic signal also increases as a function of the Al/La ratio, but, at the highest growth temperature, it does not saturate. This unusual behavior is consistent with the formation of an ordered structure of defect dipoles in the LaAlO{sub 3} film caused by the off-centering of excess Al atoms in agreement with the theory.

  13. Efficient second harmonics generation of a laser-diode-pumped Nd:YAG laser and its applications. Laser diode reiki Nd:YAG laser no kokoritsu daini kochoha hassei to sono oyo

    Energy Technology Data Exchange (ETDEWEB)

    Kubota, S.; Oka, M. (Sony Corp., Tokyo (Japan))

    1991-08-10

    Stabilization of the second harmonics in a laser-diode-pumped Nd:YAG laser and its application are described. The laser is a quantum noise limiting laser, in which a mode competing noise is generated from an interaction between the laser medium Nd:YAG and the type II nonlinear optical crystal KTiOPO{sub 4} when generating a second harmonics in the resonator. However, the quantum noise limiting second harmonics was obtained by means of inserting (1/4) wave length plate in the resonator to release the bond between two intersecting inherent polarization modes. This stabilized green laser is of a single lateral mode is nearly free of aberration. Therefore, an optical disc prototype having three times as much of the currently used density was made using an objective lens having high number of openings to collect lights, which was verified capable of regeneration at a high signal to noise ratio. In addition, higher output is possible by means of parallelizing the excitation, and high output is realized from edge excitation at a fiber bundle. 18 refs., 3 figs.

  14. Precise calculation of the KTP crystal used as both an intracavity electro-optic Q-switch and a second harmonic generator

    Institute of Scientific and Technical Information of China (English)

    Yuye Wang; Jianquan Yao; Degang Xu; Pu Zhao; Peng Wang

    2006-01-01

    @@ A method of precisely calculating the external applied voltage and the optimum type-Ⅱ phase matching angles for KTP crystal, which is used as both an intracavity electro-optic (EO) Q-switch and a frequency doubler, is presented. The effective EO coefficient along the phase-matching direction is defined to calculate the half-wave voltage and the quarter-wave voltage, and the precise calculation for the phase matching angles in the condition of KTP crystal optimum second harmonic phase matching is theoretically realized.

  15. Generation of large fifth-order nonlinear phase shifts by use of lossless χ(2) cascaded nonlinear processes

    Institute of Scientific and Technical Information of China (English)

    XU Guang; QIAN Liejia; WANG Tao; FAN Dianyuan; LI Fuming

    2004-01-01

    It is shown that the cascaded fifth-order nonlinear phase shifts will increase with energy loss in the cascaded processes. Essentially different from the multi-photon absorption accompanied with inherent material nonlinearities, the loss of fundamental wave in a cascaded process is controllable and suppressible. By introducing difference frequencies generated from the reaction between the fundamental and its second harmonic after the cascaded processes, the fundamental wave can be free of energy loss, while the large cascaded fifth-order nonlinear phase shift is maintained.

  16. Second-harmonic imaging of ferroelectric domain walls

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.; Hvam, Jørn Märcher; Pedersen, Kjeld;

    1998-01-01

    Domain walls in periodically poled ferroelectric KTiOPO4 and LiNbO3 crystals are observed by making use of second-harmonic (SH) generation enhancement in the transition regions between neighboring domains. SH images of domain walls obtained with various samples for different polarization...

  17. Absolute and relative nonlinear optical coefficients of KDP, KD(asterisk)P, BaB2O4, LiIO3, MgO:LiNbO3, and KTP measured by phase-matched second-harmonic generation

    Science.gov (United States)

    Eckardt, Robert C.; Byer, Robert L.; Masuda, Hisashi; Fan, Yuan Xuan

    1990-01-01

    Both absolute and relative nonlinear optical coefficients of six nonlinear materials measured by second-harmonic generation are discussed. A single-mode, injection-seeded, Q-switched Nd:YAG laser with spatially filtered output was used to generate the 1.064-micron fundamental radiation. The following results were obtained: d36(KDP) = 0.38 pm/V, d36(KD/asterisk/P) = 0.37 pm/V, (parallel)d22(BaB2O4)(parallel) = 2.2 pm/V, d31(LiIO3) = -4.1 pm/V, d31(5 percentMgO:MgO LiNbO3) = -4.7 pm/V, and d(eff)(KTP) = 3.2 pm/V. The accuracy of these measurements is estimated to be better than 10 percent.

  18. Theory of anomalous backscattering in second harmonic X-mode ECRH experiments

    Science.gov (United States)

    Gusakov, E. Z.; Popov, A. Yu.

    2016-08-01

    A quantitative model explaining generation of the anomalous backscattering signal in the second harmonic X-mode electron cyclotron resonance heating (ECRH) experiments at TEXTOR tokamak as a secondary nonlinear process which accompanies a primary low-threshold parametric decay instability (PDI) leading to excitation of two—upper hybrid (UH)—plasmons trapped in plasma is developed. The primary absolute PDI enhancing the UH wave fluctuations from the thermal noise level is supposed to be saturated due to a cascade of secondary low-threshold decays of the daughter UH wave leading to excitation of the secondary UH waves down-shifted in frequency and the ion Bernstein wave. A set of equations describing the cascade is derived and solved numerically. The results of numerical modelling are shown to be in agreement with the analytical estimations of the growth rate of the initial and secondary parametric decays and the saturation level. The generation of backscattering signal is explained by coupling of the daughter UH waves. The fine details of the frequency spectrum of the anomalously reflected extraordinary wave and the absolute value of the observed backscattering signal in the second harmonic X-mode ECRH experiments at TEXTOR are reproduced.

  19. Far- and near-field second harmonic imaging of ferroelectric domain walls

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.; Pedersen, Kjeld; Skettrup, Torben;

    1998-01-01

    Domain walls in periodically poled ferroelectric LiNbO3 crystals are observed with both far- and near-field imaging techniques that make use of second harmonic generation in the transition regions between neighbouring domains. Second harmonic images of domain walls represent bright lines of about 0.......5 micrometers in width (as measured with the near-field microscope) for the polarization of the second harmonic radiation perpendicular to the domain walls. Origin and selection rules for the constrast in second harmonic images of domain walls are discussed....

  20. Analysis of carrier transport and carrier trapping in organic diodes with polyimide-6,13-Bis(triisopropylsilylethynyl)pentacene double-layer by charge modulation spectroscopy and optical second harmonic generation measurement

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Eunju, E-mail: elim@dankook.ac.kr, E-mail: taguchi.d.aa@m.titech.ac.jp, E-mail: iwamoto@pe.titech.ac.jp [Department of Applied Physics, Institute of Nanosensor and Biotechnology, Dankook University, Jukjeon-dong, Gyeonggi-do 448-701 (Korea, Republic of); Taguchi, Dai, E-mail: elim@dankook.ac.kr, E-mail: taguchi.d.aa@m.titech.ac.jp, E-mail: iwamoto@pe.titech.ac.jp; Iwamoto, Mitsumasa, E-mail: elim@dankook.ac.kr, E-mail: taguchi.d.aa@m.titech.ac.jp, E-mail: iwamoto@pe.titech.ac.jp [Department of Physical Electronics, Tokyo Institute of Technology 2-12-1, O-okayama, Meguro-ku, Tokyo 152-8552 (Japan)

    2014-08-18

    We studied the carrier transport and carrier trapping in indium tin oxide/polyimide (PI)/6,13-Bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene)/Au diodes by using charge modulation spectroscopy (CMS) and time-resolved electric field induced optical second harmonic generation (TR-EFISHG) measurements. TR-EFISHG directly probes the spatial carrier behaviors in the diodes, and CMS is useful in explaining the carrier motion with respect to energy. The results clearly indicate that the injected carriers move across TIPS-pentacene thorough the molecular energy states of TIPS-pentacene and accumulate at the PI/TIPS-pentacene interface. However, some carriers are trapped in the PI layers. These findings take into account the capacitance-voltage and current-voltage characteristics of the diodes.

  1. Spontaneous and field-induced mesomorphism of a silyl-terminated bent-core liquid crystal as determined from second-harmonic generation and resonant X-ray scattering.

    Science.gov (United States)

    Folcia, C L; Ortega, J; Etxebarria, J; Rodríguez-Conde, S; Sanz-Enguita, G; Geese, K; Tschierske, C; Ponsinet, V; Barois, P; Pindak, R; Pan, LiDong; Liu, Z Q; McCoy, B K; Huang, C C

    2014-01-07

    The polarity and structure of the phases of a liquid crystal constituted by thiophene-based bent-core molecules is investigated by means of optical second-harmonic generation (SHG), and resonant and conventional X-ray diffraction. The material studied is representative of a wide family of mesogens that contain silyl groups at the ends of the chains. These bulky terminal groups have been reported to give rise to smectic phases showing ferroelectric switching. However, the analysis of the SHG signal before and after application of electric fields has allowed us to establish unambiguously that the reported ferroelectricity is not intrinsic to the material but stabilized by the cell substrates once an electric field has been applied. In addition, the results obtained from resonant X-ray diffraction indicate that virgin samples have antiferroelectric undulated synclinic smectic structures.

  2. Second Harmonic Light Scattering from Macromolecules: Collagen.

    Science.gov (United States)

    Roth, Shmuel

    In this work we present the theory and practice of optical second harmonic generation (SHG) as applied to rat-tail tendon collagen. Our work is the first quantitative application of SHG to biological systems. The angular dependence of SHG is found to display a sharp, intense, forward peak superimposed on a broad background. The sharp peak is shown to imply long-range polar order, while the broad background corresponds to that predicted for the random "up"/"down" array of collagen fibrils seen with the electron microscope. The dependence of fibril diameter distribution on age and state of hydration is measured. Our experiments also reveal information concerning the structure of the fibrils and their arrangement in the tendon. The degree of polar order, the coherence length of tendon for harmonic generation and the absolute magnitude of the nonlinear susceptibility of the collagen fibril are also determined. The biological significance of these findings and the many advantages of SHG for the structural study of biological macromolecules and tissues are discussed.

  3. Probing the Near-Field of Second-Harmonic Light around Plasmonic Nanoantennas.

    Science.gov (United States)

    Metzger, Bernd; Hentschel, Mario; Giessen, Harald

    2017-03-08

    We introduce a new concept that enables subwavelength polarization-resolved probing of the second-harmonic near-field distribution of plasmonic nanostructures. As a local sensor, this method utilizes aluminum nanoantennas, which are resonant to the second-harmonic wavelength and which allow to efficiently scatter the local second-harmonic light to the far-field. We place these sensors into the second-harmonic near-field generated by plasmonic nanostructures and carefully vary their position and orientation. Observing the second-harmonic light resonantly scattered by the aluminum nanoantennas provides polarization-resolved information about the local second-harmonic near-field distribution. We then investigate the polarization-resolved second-harmonic near-field of inversion symmetric gold dipole nanoantennas. Interestingly, we find strong evidence that the second-harmonic dipole is predominantly oriented perpendicular to the gold nanoantenna long axis, although the excitation laser is polarized parallel to the nanoantennas. We believe that our investigations will help to disentangle the highly debated origin of the second-harmonic response of inversion symmetric plasmonic structures. Furthermore, we believe that our new method, which enables the measurement of local nonlinear electric fields, will find widespread implementation and applications in nonlinear near-field optical microscopy.

  4. Cascaded Soliton Compression of Energetic Femtosecond Pulses at 1030 nm

    DEFF Research Database (Denmark)

    Bache, Morten; Zhou, Binbin

    2012-01-01

    We discuss soliton compression with cascaded second-harmonic generation of energetic femtosecond pulses at 1030 nm. We discuss problems encountered with soliton compression of long pulses and show that sub-10 fs compressed pulses can be achieved.......We discuss soliton compression with cascaded second-harmonic generation of energetic femtosecond pulses at 1030 nm. We discuss problems encountered with soliton compression of long pulses and show that sub-10 fs compressed pulses can be achieved....

  5. Effect of laser polarization and pulse energy on therapeutic, femtosecond laser-induced second harmonic generation in corneal tissue (Conference Presentation)

    Science.gov (United States)

    Calhoun, William R.; Ilev, Ilko K.

    2016-03-01

    Some of the most commonly performed surgical operations in the world, including laser-assisted in-situ keratomileusis (LASIK), lens replacement (e.g. cataract surgery), and keratoplasty (cornea transplant), now employ therapeutic infrared femtosecond lasers (FSLs) for their extreme precision, low energy delivered into tissue and advanced ablation characteristics. Although the widely exploited applications of FSLs in medical therapeutics offer significant benefits, FSLs must generate very high intensities in order to achieve optical breakdown, the predominant tissue ablative mechanism, which can also stimulate nonlinear optical effects such as harmonic generation, an effect that generates coherent visible and UV light in the case of second- (SHG) and third-harmonic generation (THG), respectively. In order to improve the understanding of HG in corneal tissue, the effect of FSL polarization and pulse energy were investigated. FSL stimulated SHG intensity in corneal tissue was measured as the laser polarization was rotated 360 degrees. Further, the pulse energy at the SHG wavelength were measured for single FSL pulses as the pulse energy at the fundamental wavelength was varied through a range of clinically relevant values. The results of this study revealed SHG intensity oscillated with laser polarization, having a variation greater than 20%. This relationship seems to due to the intrinsic anisotropy of collagen fibril hyperpolarizability, not related to tissue birefringence. SHG pulse energy measurements showed an increase in SHG pulse energy with increasing FSL pulse energy, however conversion efficiency decreased. This may be related to the dynamic relationship between optical breakdown leading to tissue destruction and HG evolution.

  6. Broadband Asymmetric Conical Emission via Cascaded Second-Order Nonlinear Polarization during the Propagation of Femtosecond Laser Pulses in a BBO Crystal

    Institute of Scientific and Technical Information of China (English)

    WEN Jing; JIANG Hong-Bing; YU Jing; YANG Hong; GONG Qi-Huang

    2011-01-01

    @@ We investigate the propagation of femtosecond laser pulses in a 5-mm-thick BBO crystal along the direction of type-Ⅰ phase-matched second-harmonic generation.An intensity-asymmetric broadband conical emission (500- 2000 nm) is demonstrated when a suitable chirp is introduced.It is generated by optical parametric amplification pumped by the second-harmonic light and seeded by the fundamental light which is broadened by cascaded nonlinear processes during second-harmonic generation.

  7. A Spatially Resolved Optical Second Harmonic Generation (SHG) Study of the Perovskite Iridate Sr2IrO4 with Bulk Sensitivity

    Science.gov (United States)

    Zhao, Liuyan; Chu, Hao; Torchinsky, Darius; Qi, Tongfei; Cao, Gang; Hsieh, David

    2014-03-01

    There has been a lot of recent interest in the layered perovskite iridate, Sr2IrO4, owing to its novel spin-orbital entangled Mott insulator ground state and its potential to realize high-Tc superconductivity upon doping. Although its bulk structural and magnetic point group symmetries have been characterized by resonant x-ray and neutron diffraction, these measurements provide spatially integrated information. In fact, recent neutron diffraction studies on Sr2IrO4 suggest that such measurements may be averaging over crystallographic domains of reduced symmetry that in turn generate distinct magnetic domains. Therefore, spatial resolution is desirable in order to gain full understanding of the point group symmetries of Sr2IrO4. Here, we show that optical SHG can provide a bulk sensitive measurement of the point group symmetries. By performing such SHG measurements in an imaging mode, we study the possible microscopic domain structures recently suggested. More generally, our SHG imaging technique provides an alternative way to probe the point group symmetries of iridate crystals, which are not always amenable to neutron scattering due to their small sample sizes and strong neutron absorption cross section. This work is supported by Army Research Office Grant Nos. W911NF-13-0059 and (ARO-DURIP) W911NF-13-1-0293.

  8. Controlling Second Harmonic Efficiency of Laser Beam Interactions

    Science.gov (United States)

    Barnes, Norman P. (Inventor); Walsh, Brian M. (Inventor); Reichle, Donald J. (Inventor)

    2011-01-01

    A method is provided for controlling second harmonic efficiency of laser beam interactions. A laser system generates two laser beams (e.g., a laser beam with two polarizations) for incidence on a nonlinear crystal having a preferred direction of propagation. Prior to incidence on the crystal, the beams are optically processed based on the crystal's beam separation characteristics to thereby control a position in the crystal along the preferred direction of propagation at which the beams interact.

  9. Cascaded four-wave mixing for broadband tunable laser sideband generation.

    Science.gov (United States)

    Liu, Weimin; Zhu, Liangdong; Wang, Liang; Fang, Chong

    2013-06-01

    We demonstrate the versatile broadband wavelength tunability of frequency upconverted multicolor cascaded four-wave-mixing (CFWM) signals spanning the continuous wavelength range from UV to near IR in a thin type-I BBO crystal using 35 fs, 800 nm fundamental and chirped IR supercontinuum white light pulses. Two sets of spatially dispersed CFWM laser sidebands are concomitantly generated from two incident pulses as well as their second-harmonic-generation and sum-frequency-generation pulses in a crossing geometry. The tunable cascaded signals with ultrabroad bandwidth can be readily achieved via spatially rotating the BBO crystal to different phase-matching conditions and temporally varying the time delay between the two incident near-IR pulses.

  10. Domain structure analysis of Pb(Zn1/3Nb2/3)O3-9%PbTiO3 single crystals using optical second harmonic generation microscopy

    Science.gov (United States)

    Kaneshiro, Junichi; Uesu, Yoshiaki

    2010-11-01

    The domain structures of relaxor-ferroelectric Pb(Zn1/3Nb2/3)O3-9%PbTiO3 (PZN-9PT) single crystals with a morphotropic phase boundary (MPB) composition are observed with a scanning second harmonic generation (SHG) microscope. Three-dimensional domain structures are obtained from sectional SH images along the axial direction. The domain structures are explained well by the strain compatibility theory that is based on the ferroelectric/ferroelastic phase transition of m3¯mFm(p) with the monoclinic space group Pm . The SHG images are divided into several parts, and the light-polarization dependence (PolD) at each site is calculated by minimizing the least-squares errors of the nonlinear susceptibilities. The PolDs are fitted well by theoretical formulas of the SH intensities for the Pm symmetry, and the two-dimensional map of the PolD coincides well with the corresponding SHG image of the domain structures. The monoclinic Pm symmetry at the MPB of PZN-9PT is determined at the optical diffraction limit of 460 nm.

  11. A way for studying the impact of PEDOT:PSS interface layer on carrier transport in PCDTBT:PC{sub 71}BM bulk hetero junction solar cells by electric field induced optical second harmonic generation measurement

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Zubair, E-mail: zubairtarar@um.edu.my; Abdullah, Shahino Mah; Sulaiman, Khaulah [Low Dimensional Materials Research Centre (LDMRC), Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Taguchi, Dai; Iwamoto, Mitsumasa [Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 O-Okayama, Meguro-ku, Tokyo 152-8552 (Japan)

    2015-04-28

    Electric-field-induced optical second-harmonic generation (EFISHG) measurement was employed to study the impact of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) interface layer on the carrier transport mechanism of the PCDTBT:PC{sub 71}BM bulk heterojunction (BHJ) organic solar cells (OSCs). We revealed that the electric fields in the PCDTBT and PC{sub 71}BM were allowed to be measured individually by choosing fundamental laser wavelengths of 1000 nm and 1060 nm, respectively, in dark and under illumination. The results showed that the direction of the internal electric fields in the PCDTBT:PC{sub 71}BM BHJ layer is reversed by introducing the PEDOT:PSS layer, and this results in longer electron transport time in the BHJ layer. We conclude that TR-EFISHG can be used as a novel way for studying the impact of interfacial layer on the transport of electrons and holes in the bulk-heterojunction OSCs.

  12. Dispersion of the second harmonic generation in GaN{sub x}As{sub 1−x} (x = 0.25, 0.5, 0.75) alloys

    Energy Technology Data Exchange (ETDEWEB)

    Reshak, A.H., E-mail: maalidph@yahoo.co.uk [New Technologies – Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia)

    2014-03-15

    Highlights: • Ab initio study the effect of vary the concentration of N on SHG of GaN{sub x}As{sub 1−x} alloys. • Reducing N content increase the effective second-order susceptibility coefficients. • We found significant enhance in the properties of the new alloys. -- Abstract: The all-electron full-potential linearized augmented plane wave method has been used for an ab initio theoretical study to investigate the effect of vary the concentration of nitrogen on the second harmonic generation (SHG) of GaN{sub x}As{sub 1−x} (x = 0.25, 0.5, 0.75) alloys. Based on the density functional theory the nonlinear optical susceptibilities (NLO) namely the SHG are calculated and their spectra are analyzed. We find that reducing N concentration leads to reduce the energy band gap resulting in enhancing the functionality of GaN{sub x}As{sub 1−x} alloys and hence increasing the second-order susceptibility. A surprising finding is a nonlinear relationship between the composition and the absorption/emission energies, leading to significantly enhancing the properties not obtainable from the parent GaAs and GaN binary systems.

  13. Influence of Pentacene Interface Layer in ITO/α-NPD/Alq3/Al Organic Light Emitting Diodes by Time-Resolved Electric-Field-Induced Optical Second-Harmonic Generation Measurement.

    Science.gov (United States)

    Oda, Yoshiaki; Sadakata, Atsuo; Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa

    2016-04-01

    By using I-V, EL-V, displacement current measurement (DCM) and time-resolved electric-field-induced optical second-harmonic generation (TR-EFISHG) measurement, we studied the influence of interface pentacene layer inserted between ITO and a-NPD layers in ITO/α-NPD/Alq3/Al OLEDs. All experiments were carried out for the OLEDs with and without a pentacene interface layer. The I-V and EL-V measurements showed the decrease of operating voltage of EL, the DCM showed the lowering of inception voltage of carrier injection by inserting a pentacene interface layer. The TR-EFISHG measurement showed the faster accumulation of holes at the interface between the a-NPD and Alq3 layers, which resulted in the relaxation of electric field of a-NPD layer accomplished by the increase of the conductivity and the increase of the electric field in the Alq3 layer. We conclude that TR-EFISHG measurement is helpful for understanding I-V and EL-V characteristics, and can be combined with other methods to give significant information which are impacted by the interface layer.

  14. Study of carrier energetics in ITO/P(VDF-TrFE)/pentacene/Au diode by using electric-field-induced optical second harmonic generation measurement and charge modulation spectroscopy

    Science.gov (United States)

    Otsuka, Takako; Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa

    2017-02-01

    By using electric-field-induced optical second harmonic generation (EFISHG) measurement and charge modulation spectroscopy (CMS), we studied carrier behavior and polarization reversal in ITO/ poly(vinylidene fluoride trifluoroethylene) (P(VDF-TrFE))/pentacene/Au diodes with a ferroelectric P(VDF-TrFE) layer in terms of carrier energetics. The current-voltage (I-V) characteristics of the diodes showed three-step polarization reversal in the dark. However, the I-V was totally different under illumination and exhibited two-step behavior. EFISHG probed the internal electric field in the pentacene layer and accounted for the polarization reversal change due to charge accumulation at the pentacene/P(VDF-TrFE) interface. CMS probed the related carrier energetics and indicated that exciton dissociation in pentacene molecular states governed carrier accumulation at the pentacene/ferroelectric interface, leading to different polarization reversal processes in the dark and under light illumination. Combining EFISHG measurement and CMS provides us a way to study carrier energetics that govern polarization reversal in ferroelectric P(VDF-TrFE)/pentacene diodes.

  15. Second harmonic generation and electro-optical Pockels effect of 1-and 3-nitro-6-azabenzo[]pyrene N-oxide isomers: A Hartree-Fock and Coulomb-attenuating density functional theory investigation

    Indian Academy of Sciences (India)

    Andrea Alparone

    2014-05-01

    Structural, energetic, spectroscopic, linear and nonlinear optical (NLO) properties of the environmental mutagens 1- and 3-nitro-6-azabenzo[]pyrene -oxides were characterized by means of Hartree-Fock as well as B3LYP and CAM-B3LYP density functional theory computations. The NLO investigations were performed for the second harmonic generation (SHG) and electro-optical Pockels effect (EOPE) at the incident wavelength of 1064 nm. The results show that, the predicted structures, vibrational spectra, nucleus independent chemical shifts, ionization energy, electron affinity as well as electronic polarizabilities are little influenced by the position of the nitro substituent. Differently, the dipole moment () and the first-order hyperpolarizabilities () are significantly dependent on the isomerization. The rather different mutagenic activity of the investigated isomers could be related to their diverse polarity. At the CAM-B3LYP level, when passing from the 1- to the 3-nitro-6-azabenzo[a]pyrene -oxide isomer, the datum increases by about 5 D (a factor of three), whereas the static and dynamic values decrease by ca. 50%. Dipole moment measurement and SHG and EOPE NLO techniques are potentially useful to distinguish these important environmental mutagens.

  16. Growth and characterization of crystals for IR detectors and second harmonic gereration devices

    Science.gov (United States)

    Lal, Ravi B.; Batra, Ashok K.; Rao, Sistla M.; Bhatia, S. S.; Chunduru, Kunar P.; Paulson, Ron; Moorkherji, Tripty K.

    1989-01-01

    Two types of materials, L-arginine phosphate (LAP) and doped triglycine sulfate (TGS), are examined for their growth characteristics and relevant properties for second harmonic generation and IR detector applications, respectively.

  17. General solution of cumulative second harmonic by Lamb wave propagation in a solid plate

    Institute of Scientific and Technical Information of China (English)

    Deng Mingxi

    2008-01-01

    A straightforward approach has been developed for the general solution of cumulative second harmonic by Lamb wave propagation in a solid plate. The present analyses of second-harmonic generation by Lamb waves focus on the cases where the phase velocity of the fundamental Lamb wave is exactly or approximately equal to that of the double frequency Lamb wave (DFLW). Based on the general solution obtained, the numerical analyses show that the cumulative second-harmonic fields are associated with the position of excitation source and the difference between the phase velocity of the fundamental Lamb wave and that of the dominant DFLW component.

  18. Isolated Attosecond Pulses using a Detuned Second-harmonic Field

    Energy Technology Data Exchange (ETDEWEB)

    Merdji, Hamed; /Saclay /SLAC, PULSE; Auguste, Thierry; Boutu, Willem; Caumes, J.-Pascal; Carre, Bertrand; /Saclay; Pfeifer, Thomas; Jullien, Aurelie; Neumark, Daniel M.; Leone, Stephen R.; /UC, Berkeley /LBL, Berkeley

    2007-11-07

    Calculations are presented for the generation of an isolated attosecond pulse in a multicycle two-color strong-field regime. We show that the recollision of the electron wave packet can be confined to half an optical cycle using pulses of up to 40 fs in duration. The scheme is proven to be efficient using two intense beams, one producing a strong field at {omega} and the other a strong field detuned from 2{omega}. The slight detuning {delta}{omega} of the second harmonic is used to break the symmetry of the electric field over many optical cycles and provides a coherent control for the formation of an isolated attosecond pulse.

  19. Second-harmonic illumination to enhance multispectral digital lensless holographic microscopy.

    Science.gov (United States)

    Mendoza-Yero, Omel; Carbonell-Leal, Miguel; Lancis, Jesús; Garcia-Sucerquia, Jorge

    2016-03-01

    Multispectral digital lensless holographic microscopy (MDLHM) operating with second-harmonic illumination is shown. Added to the improvement of the spatial resolution of the previously reported MDLHM operating with near-infrared illumination, this second-harmonic MDLHM shows promise as a tool to study the behavior of biological samples under a broad spectral illumination. This illumination is generated by focusing a highly spatially coherent ultrashort pulsed radiation into an uncoated Type 1 β-BaB2O4 (BBO) nonlinear crystal. The second-harmonic MDLHM allows achieving multispectral images of biological samples with enhanced micrometer spatial resolution. The illumination wavelength of the second-harmonic MDLHM can be tuned by displacing a focusing optics with respect to a pinhole; spatially resolved information at different wavelengths of the sample can then be retrieved.

  20. Highly efficient single-pass sum frequency generation by cascaded nonlinear crystals

    DEFF Research Database (Denmark)

    Hansen, Anders Kragh; Andersen, Peter E.; Jensen, Ole Bjarlin;

    2015-01-01

    , despite differences in the phase relations of the involved fields. An unprecedented 5.5 W of continuous-wave diffraction-limited green light is generated from the single-pass sum frequency mixing of two diode lasers in two periodically poled nonlinear crystals (conversion efficiency 50%). The technique......The cascading of nonlinear crystals has been established as a simple method to greatly increase the conversion efficiency of single-pass second-harmonic generation compared to a single-crystal scheme. Here, we show for the first time that the technique can be extended to sum frequency generation...... is generally applicable and can be applied to any combination of fundamental wavelengths and nonlinear crystals....

  1. P(o)schl-Teller势阱中二次谐波产生系数的计算%Optical Second-Harmonic Generation in the P(o)schl-Teller Well

    Institute of Scientific and Technical Information of China (English)

    谭鹏; 李斌; 路洪; 郭康贤

    2003-01-01

    二阶非线性光学效应是非线性光学中人们发现最早,研究最多,应用最广的一个课题.在非对称性势阱中,二次谐波产生系数与势阱的形状及其非对称性程度有很大的关系.本文用量子力学中密度矩阵算符理论导出了P(o)schl-Teller势阱中二次谐波产生系数和解析表达式.考虑到在P(o)schl-Teller势阱中有两个可调参数κ和λ,并且势阱的形状与对称性随κ和λ取值的不同而明显不同,因此我们可以通过调节κ和λ的取值而获得P(o)schl-Teller势阱中的二次谐波产生系数的变化规律,并找到其最大值,从而为实验提供必要的研究方向与理论依据.%Nonlinear optics of low-dimensional semiconductor structures has recently attracted considerable attention. The problem is very important to the development of superlattice devices such as fast infrared detectors and modulators because one needs to know the range of input optical intensities for which linear operation is possible. Analytical expression of the second-harmonic generation (SHG) coefficients is obtained in the Poschl-Teller well using the density matrix formalism taking into account the intrasubband relaxation. Since there are two adjustable parameters κ and λ in the Poschl-Teller well, the shape of the well will change with the change of the parameters κ and λ, accordingly the SHG coeffcient will change with the parameters κ and λ. It is shown that the SHG coefficient depends on the parameter κ、λ and the tunnel bandwith. Numerical results are presented for a typical AlGaAs/GaAs Poschl-Teller well.

  2. Low Noise Second Harmonic Oscillator Using Mutually Synchronized Gunn Diodes

    Science.gov (United States)

    Kawasaki, Kengo; Tanaka, Takayuki; Aikawa, Masayoshi

    This paper represents a low noise second harmonic oscillator using mutually synchronized Gunn diodes. A multi-layer MIC technology is adopted to reduce the circuit size of the oscillator. The oscillator consists of Gunn diodes, slot line resonators and strip lines. By embedding Gunn diodes in the slot line resonators, a harmonic RF signal can be generated very easily. The strip lines are used for the power combining output circuit. The shape of slot line resonator is square in order to achieve the low phase noise and the suppression of undesired harmonics. The second harmonic oscillator is designed and fabricated in K band. The output power is +8.89dBm at the design frequency of 18.75GHz (2f0) with the phase noise of -116.2dBc/Hz at the offset frequency of 1MHz. Excellent suppression of the undesired fundamental frequency signal (f0) of -33dBc is achieved. Also, the circuit size is reduced by three-tenths relative to that of the previously proposed circuit.

  3. Generating ultra-short energetic pulses with cascaded soliton compression in lithium niobate crystals

    DEFF Research Database (Denmark)

    Zhou, Binbin; Bache, Morten; Chong, A.;

    2010-01-01

    By launching energetic femtosecond pulses in a lithium niobate crystal, the phase mismatched second-harmonic generation process compresses the 50 fs input pulse at 1250 nm to 30 fs through a soliton effect.......By launching energetic femtosecond pulses in a lithium niobate crystal, the phase mismatched second-harmonic generation process compresses the 50 fs input pulse at 1250 nm to 30 fs through a soliton effect....

  4. 2D magnetic nanoparticle imaging using magnetization response second harmonic

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Saburo, E-mail: tanakas@ens.tut.ac.jp [Toyohashi University of Technology, 1-1 Tempaku-cho, Toyohashi, Aichi 441-8580 (Japan); Murata, Hayaki; Oishi, Tomoya; Suzuki, Toshifumi [Toyohashi University of Technology, 1-1 Tempaku-cho, Toyohashi, Aichi 441-8580 (Japan); Zhang, Yi [Peter Gruenberg Institute, Forschungszentrum Juelich, Juelich D-52425 (Germany)

    2015-06-01

    A detection method and an imaging technique for magnetic nanoparticles (MNPs) have been investigated. In MNP detection and in magnetic particle imaging (MPI), the most commonly employed method is the detection of the odd harmonics of the magnetization response. We examined the advantage of using the second harmonic response when applying an AC magnetic modulation field and a DC bias field. If the magnetization response is detected by a Cu-wound-coil detection system, the output voltage from the coil is proportional to the change in the flux, dϕ/dt. Thus, the dependence of the derivative of the magnetization, M, on an AC magnetic modulation field and a DC bias field were calculated and investigated. The calculations were in good agreement with the experimental results. We demonstrated that the use of the second harmonic response for the detection of MNPs has an advantage compared with the usage of the third harmonic response, when the Cu-wound-coil detection system is employed and the amplitude of the ratio of the AC modulation field and a knee field H{sub ac}/H{sub k} is less than 2. We also constructed a 2D MPI scanner using a pair of permanent ring magnets with a bore of ϕ80 mm separated by 90 mm. The magnets generated a gradient of G{sub z}=3.17 T/m transverse to the imaging bore and G{sub x}=1.33 T/m along the longitudinal axis. An original concentrated 10 μl Resovist solution in a ϕ2×3 mm{sup 2} vessel was used as a sample, and it was imaged by the scanner. As a result, a 2D contour map image could be successfully generated using the method with a lock-in amplifier.

  5. Parameters for efficient growth of second harmonic field in nonlinear photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Joseph, Shereena, E-mail: sherin5462@gmail.com; Khan, Mohd. Shahid; Hafiz, Aurangzeb Khurram

    2014-03-01

    The ultrashort pulse propagation and nonlinear second harmonic generation under the undepleted pump approximation in a quadratic nonlinear photonic crystal (NPC) structure is theoretically investigated and the optimized parameters for high second harmonic generation conversion efficiency are extracted. The transfer matrix method is used for the numerical formulation for oblique angle of incidence. A unique set of material combination GaInP/InAlP is selected as alternating nonlinear and linear layers. The NPC parameters like incident angle and layer thickness are manipulated to obtain the exact phase matching using double resonance condition for a fixed number of layers with known experimental material parameters.

  6. Characterization of the second-harmonic response of a silver-air interface

    Energy Technology Data Exchange (ETDEWEB)

    O' Donnell, K A [Division de FIsica Aplicada, Centro de Investigacion CientIfica y de Educacion Superior de Ensenada, Apartado Postal 2732, Ensenada, Baja California, 22800 (Mexico); Torre, R [Dipartimento di Fisica and European Laboratory for Non-linear Spectroscopy (LENS), Polo Scientifico, Universita di Firenze, Via Carrara n.1, Sesto Fiorentino, 50019 (Italy); INFM CRS-SOFT, Universita La Sapienza, Rome (Italy)

    2005-07-01

    We present an experimental study of second-harmonic generation in the light reflected from a flat silver surface. It is discussed that the harmonic generation from such a surface may be expressed in terms of the three unique elements of its effective surface susceptibility tensor. A method is proposed to determine the susceptibilities by measuring the second-harmonic power with different polarization conditions. By employing a picosecond light source and photon-counting techniques, we determine the susceptibilities and compare our results with previous work.

  7. Investigation of KTiOPO4 nanocrystals by means of second-harmonic light emission

    Institute of Scientific and Technical Information of China (English)

    Chunyuan Zhou; Loc Le Xuan; Abdallah Slablab; Nicolas Sandeau; Sophie Brasselet; Dominique Chauvat; Jean-Fran(c)ois Roch

    2008-01-01

    The finding of nonlinear nanometric-sized probes is of key importance for the development of nonlinear microscopy in physical as well as biological sciences. We isolate nonlinear KTiOPO4 nanocrystals and study them by second-harmonic generation microscopy (SHGM) and atomic force microscopy (AFM) independently. With both polarization analysis and defocused imaging of the emitted second harmonic field, we extract the Euler angles of the crystalline axes of a single nanocrystal. A balanced coherent optical homodyne detection shows the coherent nature of the nanocrystal nonlinear emission and allows a phase measurement of the emitted second-harmonic field. These features make the KTiOPO4 nanocrystal a good candidate for a vectorial probe of electromagnetic near fields.

  8. High-resolution second-harmonic optical coherence tomography of collagen in rat-tail tendon

    Science.gov (United States)

    Jiang, Yi; Tomov, Ivan V.; Wang, Yimin; Chen, Zhongping

    2005-03-01

    A high-resolution second-harmonic optical coherence tomography (SH-OCT) system is demonstrated using a spectrum broadened femtosecond Ti :sapphire laser. An axial resolution of 4.2μm at the second-harmonic wave center wavelength of 400 nm has been achieved. Because the SH-OCT system uses the second-harmonic generation signals that strongly depend on the orientation, polarization, and local symmetry properties of chiral molecules, this technique provides unique contrast enhancement to conventional optical coherence tomography. The system is applied to image biological tissues of the rat-tail tendon. Highly organized collagen fibrils in the rat-tail tendon can be visualized in recorded images.

  9. Focusing of Second-Harmonic Signals with Nonlinear Metamaterial Lenses: A Biphotonic Microscopy Approach

    Science.gov (United States)

    Ciracì, Cristian; Centeno, Emmanuel

    2009-08-01

    Recent research on second-harmonic generation in left-handed materials has shown a light localization mechanism that originates from an all-angle phase-matching condition between counterpropagating electromagnetic modes at fundamental and double frequencies. By combining these properties with negative refraction, we propose in this Letter an original approach to the design of a second-harmonic lens. Numerical simulations demonstrate that feasible metamaterials can be tailored to operate in the visible range of frequency. These nonlinear lenses open an attractive solution for the biphotonic microscopy technique by imaging passive biological structures.

  10. Theoretical Development of Nonlinear Spring Models for the Second Harmonics on an Interface between Two Solids

    Institute of Scientific and Technical Information of China (English)

    AN Zhi-Wu; WANG Xiao-Min; LI Ming-Xuan; DENG Ming-Xi; MAO Jie

    2009-01-01

    Based on the exact solutions for the second-harmonic generations of the fundamental longitudinal and transverse waves propagating normally through a thin elastic layer between two solids, the approximate representations termed as 'nonlinear spring models' relating the stresses and displacements on both sides of the interface are rigorously developed by asymptotic expansions of the wave fields for an elastic layer in the limit of small thickness to wavelength ratio. The applicability for the so-called nonlinear spring models is numerically analyzed by comparison with exact solutions for the second harmonic wave reflections. The present nonlinear spring models lay a theoretical foundation to evaluate the interracial properties by nonlinear acoustic waves.

  11. Study of the emission spectra of a 1320-nm semiconductor disk laser and its second harmonic

    Science.gov (United States)

    Gochelashvili, K. S.; Derzhavin, S. I.; Evdokimova, O. N.; Zolotovskii, I. O.; Podmazov, S. V.

    2016-03-01

    The spectral characteristics of an optically pumped external-cavity semiconductor disk laser near λ = 1320 nm are studied experimentally. Intracavity second harmonic generation is obtained using an LBO nonlinear crystal. The output power at a wavelength of 660 nm in the cw regime was 620 mW, and the peak power in the pulsed regime was 795 mW.

  12. Probing space charge effect on electroluminescence of indium tin oxide (ITO)/N,N′-di-[(1-naphthyl)-N,N′-diphenyl]-(1,1′-biphenyl)-4, 4′-diamine (α-NPD)/tris(8-hydroxy-quinolinato) aluminum (III) (Alq{sub 3})/Al diodes by time-resolved electric-field-induced optical second-harmonic generation measurement

    Energy Technology Data Exchange (ETDEWEB)

    Sadakata, Atsuo; Osada, Kenshiro; Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa, E-mail: iwamoto@pe.titech.ac.jp

    2014-03-03

    By using time-resolved electric-field-induced optical second-harmonic generation measurement, we studied the electroluminescence (EL) mechanism which is activated in double-layer organic light-emitting diodes (indium tin oxide/N,N′-di-[(1-naphthyl)-N,N′-diphenyl]-(1,1′-biphenyl)-4,4′-diamine (α-NPD)/tris(8-hydroxy-quinolinato) aluminum (III) (Alq{sub 3})/Al) in the high frequency region with application of AC square voltages at various duty-ratios. Results showed that holes were accumulated at the α-NPD/Alq{sub 3} interface in proportion to the duty-ratio, and corresponded well to the increasing EL enhancement at the high frequency. Our previous proposed model on the EL enhancement assisted by electron injection from the Al electrode in the presence of the space charge field was well confirmed. - Highlights: • We studied space charge (SC) effects in double-layer organic light emitting diodes. • The second-harmonic generation measurement was used to directly probe the SC field. • Space charge fields due to interfacial accumulated charge were verified. • We showed that SC electric fields contribute to electroluminescence emissions.

  13. Quadratic solitons for negative effective second-harmonic diffraction as nonlocal solitons with periodic nonlocal response function

    DEFF Research Database (Denmark)

    Esbensen, B.K.; Bache, Morten; Krolikowski, W.;

    2012-01-01

    We employ the formal analogy between quadratic and nonlocal solitons to investigate analytically the properties of solitons and soliton bound states in second-harmonic generation in the regime of negative diffraction or dispersion of the second harmonic. We show that in the nonlocal description t...... this regime corresponds to a periodic nonlocal response function. We then use the strongly nonlocal approximation to find analytical solutions of the families of single bright solitons and their bound states in terms of Mathieu functions....

  14. Polarization-dependent optical second-harmonic imaging of a rat-tail tendon.

    Science.gov (United States)

    Stoller, Patrick; Kim, Beop-Min; Rubenchik, Alexander M; Reiser, Karen M; Da Silva, Luiz B

    2002-04-01

    Using scanning confocal microscopy, we measure the backscattered second harmonic signal generated by a 100 fs laser in rat-tail tendon collagen. Damage to the sample is avoided by using a continuous scanning technique, rather than measuring the signal at discrete points. The second harmonic signal varies by about a factor of 2 across a single cross section of the rat-tail tendon fascicle. The signal intensity depends both on the collagen organization and the backscattering efficiency. This implies that we cannot use intensity measurements alone to characterize collagen structure. However, we can infer structural information from the polarization dependence of the second harmonic signal. Axial and transverse scans for different linear polarization angles of the input beam show that second harmonic generation (SHG) in the rat-tail tendon depends strongly on the polarization of the input laser beam. We develop an analytical model for the SHG as a function of the polarization angle in the rat-tail tendon. We apply this model in determining the orientation of collagen fibrils in the fascicle and the ratio gamma between the two independent elements of the second-order nonlinear susceptibility tensor. There is a good fit between our model and the measured data.

  15. Observation of an octave-spanning supercontinuum in the mid-infrared using ultrafast cascaded nonlinearities

    DEFF Research Database (Denmark)

    Bache, Morten; Liu, Xing; Zhou, Binbin

    2014-01-01

    An octave-spanning mid-IR supercontinuum is observed experimentally using ultrafast cascaded nonlinearities in an LiInS2 quadratic nonlinear crystal pumped with 70 fs energetic mid-IR pulses and cut for strongly phase-mismatched second-harmonic generation. ©OSA 2014.......An octave-spanning mid-IR supercontinuum is observed experimentally using ultrafast cascaded nonlinearities in an LiInS2 quadratic nonlinear crystal pumped with 70 fs energetic mid-IR pulses and cut for strongly phase-mismatched second-harmonic generation. ©OSA 2014....

  16. Second-harmonic scanning optical microscopy of semiconductor quantum dots

    DEFF Research Database (Denmark)

    Vohnsen, B.; Bozhevolnyi, S.I.; Pedersen, K.;

    2001-01-01

    Second-harmonic (SH) optical imaging of self-assembled InAlGaAs quantum dots (QD's) grown on a GaAs(0 0 1) substrate has been accomplished at room temperature by use of respectively a scanning far-field optical microscope in reflection mode and a scanning near-field optical microscope...

  17. Characterization of quasi-phase-matching gratings in quadratic media through double-pass second-harmonic power measurements

    DEFF Research Database (Denmark)

    Johansen, Steffen Kjær; Baldi, Pascal

    2004-01-01

    A new scheme for nondestructive characterization of quasi-phase-matching grating structures and temperature gradients through inverse Fourier theory using second-harmonic-generation experiments is proposed. By inserting a mirror to reflect the signals back through the sample, we show how it is po......A new scheme for nondestructive characterization of quasi-phase-matching grating structures and temperature gradients through inverse Fourier theory using second-harmonic-generation experiments is proposed. By inserting a mirror to reflect the signals back through the sample, we show how...... it is possible to retrieve the relevant information by measuring only the generated second-harmonic power, avoiding more complicated phase measurements. The potential of the scheme is emphasized through theoretical and numerical investigations in the case of periodically poled lithium niobate bulk crystals...

  18. Detection of collagen by second harmonic microscopy as a diagnostic tool for liver fibrosis

    Science.gov (United States)

    Banavar, Maruth; Kable, Eleanor P. W.; Braet, Filip; Wang, X. M.; Gorrell, M. D.; Cox, Guy

    2006-02-01

    Liver fibrosis has many causes, including hepatitis C, alcohol abuse, and non-alcoholic steatohepatitis. It is characterized by abnormal deposition of extracellular matrix proteins, mainly collagen. The deposition of these proteins results in impaired liver function caused by distortion of the hepatic architecture by fibrous scar tissue. The unique triple helix structure of collagen and high level of crystallinity make it very efficient for generating second harmonic signals. In this study we have set out to see if second harmonic imaging of collagen can be used as a non-biased quantitative tool for classification of fibrosis levels in liver biopsies and if it can detect early fibrosis formation not detected by current methods.

  19. High throughput second harmonic imaging for label-free biological applications

    KAUST Repository

    Macias Romero, Carlos

    2014-01-01

    Second harmonic generation (SHG) is inherently sensitive to the absence of spatial centrosymmetry, which can render it intrinsically sensitive to interfacial processes, chemical changes and electrochemical responses. Here, we seek to improve the imaging throughput of SHG microscopy by using a wide-field imaging scheme in combination with a medium-range repetition rate amplified near infrared femtosecond laser source and gated detection. The imaging throughput of this configuration is tested by measuring the optical image contrast for different image acquisition times of BaTiO3 nanoparticles in two different wide-field setups and one commercial point-scanning configuration. We find that the second harmonic imaging throughput is improved by 2-3 orders of magnitude compared to point-scan imaging. Capitalizing on this result, we perform low fluence imaging of (parts of) living mammalian neurons in culture.

  20. The CCFM Monte Carlo generator CASCADE 2.2.0

    CERN Document Server

    Jung, H; Deak, M; Grebenyuk, A; Hautmann, F; Hentschinski, M; Knutsson, A; Kraemer, M; Kutak, K; Lipatov, A; Zotov, N

    2010-01-01

    CASCADE is a full hadron level Monte Carlo event generator for ep, \\gamma p and p\\bar{p} and pp processes, which uses the CCFM evolution equation for the initial state cascade in a backward evolution approach supplemented with off - shell matrix elements for the hard scattering. A detailed program description is given, with emphasis on parameters the user wants to change and variables which completely specify the generated events.

  1. Organic materials for second harmonic generation. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Twieg, R.J. (comp.)

    1985-03-31

    Materials were chosen by screening the Cambridge Crystallographic Index for new noncentrosymmetric crystalline compounds, by screening commercially available materials or by synthesis of unique new substances. Measurements were then made on the powder form of these materials. Langmuir-Blodgett films were deposited and studied. In addition to the above studies, a computer program was developed to calculate (hyper) polarizabilities of organic molecules and thus aid in the selection of materials for testing. The nonlinear molecules have been divided into three classes according to absorption cutoff: 400 to 500 nm, 300 to 400 nm, and 200 to 300 nm. 108 refs., 7 tabs. (WRF)

  2. Surface area-dependent second harmonic generation from silver nanorods.

    Science.gov (United States)

    Ngo, Hoang Minh; Luong, Thanh Tuyen; Ledoux-Rak, Isabelle

    2016-08-17

    The nonlinear optical (NLO) properties of metallic nanoparticles strongly depend on their size and shape. Metallic gold nanorods have already been widely investigated, but other noble metals could also be used for nanorod fabrication towards applications in photonics. Here we report on the synthesis and NLO characterization of silver nanorods (AgNRs) with controllable localized surface plasmon resonance. We have implemented an original, one-step and seedless synthesis method, based on a spontaneous particle growth technique in the presence of polyvinylpyrrolidone (PVP) as a capping agent. Colloidal solutions of AgNRs with various aspect ratios (5.0; 6.3; 7.5; 8.2 and 9.7) have been obtained and characterized using Harmonic light scattering (HLS) at 1064 nm, in order to investigate their quadratic NLO properties. From HLS experiments, we demonstrate that hyperpolarizability (β) values of AgNRs display a strong dependence on their surface area.

  3. Second harmonic generation imaging of fascia within thick tissue block

    Science.gov (United States)

    Pfeffer, Christian P.; Olsen, Bjorn R.; Légaré, François

    2007-06-01

    Comparing the SHG image formation for thin sections of tail tendon fascia and skeletal muscle fascia, we demonstrate that the forward (F) and backward (B) SHG images are vastly different. In addition, despite the different arrangement of the collagen Type I fibrillar architecture forming these two fascias, their ratios of forward over backward signal (F/B) are nearly equal. SHG images of thick tissue blocks of the fascia-muscle unit show only backward features, as opposed to SHG images of tissue blocks of the fascia-tendon unit. These images are an amalgamation of forward and backward features due to the backscattering of forward components within tendon. These forward features disappear when this tissue block is immersed in glycerol as backscattering is hereby suppressed.

  4. Spectral imaging of breast fibroadenoma using second-harmonic generation

    Science.gov (United States)

    Zheng, Liqin; Wang, Yuhua

    2014-09-01

    Fibroadenoma (FA), typically composed of stroma and epithelial cells, is a very common benign breast disease. Women with FA are associated with an increased risk of future breast cancer. The objective of this study was to demonstrate the potential of multiphoton laser scanning microscopy (MPLSM) for characterizing the morphology of collagen in the human breast fibroadenomas. In the study, high-contrast SHG images of human normal breast tissues and fibroadenoma tissues were obtained for comparison. The morphology of collagen was different between normal breast tissue and fibroadenoma. This study shows that MPLSM has the ability to distinguish fibroadenoma tissues from the normal breast tissues based on the noninvasive SHG imaging. With the advent of the clinical portability of miniature MPLSM, we believe that the technique has great potential to be used in vivo studies and for monitoring the treatment responses of fibroadenomas in clinical.

  5. Second Harmonic Generation of Lamb Wave in Numerical Perspective

    Science.gov (United States)

    Zhu, Wu-Jun; Deng, Ming-Xi; Xiang, Yan-Xun; Xuan, Fu-Zhen; Liu, Chang-Jun

    2016-10-01

    Not Available Supported by the National Natural Science Foundation of China under Grant Nos 51325504, 11474093, 11622430 and 11474361, the National Key Research and Development Program of China (2016YFC0801903-02), and the Fundamental Research Funds for the Central Universities.

  6. Local field enhanced second-harmonic response of organic nanofibers

    DEFF Research Database (Denmark)

    Leißner, Till; Kostiučenko, Oksana; Fiutowski, Jacek

    Organic CNHP4 nanofibers showing a strong second-harmonic (SH) response have been successfully implemented as active components in a metal-organic hybrid system. Using nondestructive roll-on transfer technique nanofibers were transferred from the growing mica substrates onto electron......-beam lithography-defined regular arrays of gold, titanium and silicon oxide. As shown in a femtosecond laser scanning microscopy study the fiber-substrate interplay leads (only) on gold to a significantly enhanced SH signal. We suggest that this effect is driven by the local field enhancement i.e. the excitation...

  7. Cascading nonlinearities in an organic single crystal core fiber: The Cerenkov regime

    NARCIS (Netherlands)

    Torruellas, William E.; Krijnen, Gijs; Kim, Dug Y.; Schiek, Roland; Stegeman, George J.; Vidakovic, Petar; Zyss, Joseph

    1994-01-01

    The large nonlinear phase shifts imparted to the fundamental beam during Cerenkov second harmonic generation (SHG) in a DAN, 4-(N,N-dimethylamino)-3-acetamidonitrobenzene, single crystal core fiber are explained and modelled numerically. Cascading upconversion and downconversion processes leads to n

  8. Multipole interference in the second-harmonic optical radiation from gold nanoparticles.

    Science.gov (United States)

    Kujala, Sami; Canfield, Brian K; Kauranen, Martti; Svirko, Yuri; Turunen, Jari

    2007-04-20

    We provide experimental evidence of higher multipole (magnetic dipole and electric quadrupole) radiation in second-harmonic (SH) generation from arrays of metal nanoparticles. Fundamental differences in the radiative properties of electric dipoles and higher multipoles yield opposite interference effects observed in the SH intensities measured in the reflected and transmitted directions. These interference effects clearly depend on the polarization of the fundamental field, directly indicating the importance of multipole effects in the nonlinear response. We estimate that higher multipoles contribute up to 20% of the total emitted SH field amplitude for certain polarization configurations.

  9. Optical Pulse Generation with Self-Cascaded Electroabsorption Modulator

    Institute of Scientific and Technical Information of China (English)

    WU Jian; QiU Ji-Fang; ZHOU Guang-Tao; XU Kun; LIN Jin-Tong

    2007-01-01

    A novel scheme for pulse generation with a self-cascaded electroabsorption modulator is presented and experi mentally demonstrated at 10 GHz.In the case of optimal tuning of time delay in the fibre loop,the improvement of 50% on pulsewidth with improved extinction ratio is obtained and the narrowest pulse generated with this method is about 11 ps.

  10. Cascaded Parametric Amplification for Highly Efficient Terahertz Generation

    CERN Document Server

    Ravi, Koustuban; Cirmi, Giovanni; Reichert, Fabian; Schimpf, Damian N; Muecke, Oliver D; Kaertner, Franz X

    2016-01-01

    A highly efficient, practical approach to high-energy terahertz (THz) generation based on spectrally cascaded optical parametric amplification (THz-COPA) is introduced. The THz wave initially generated by difference frequency generation between a strong narrowband optical pump and optical seed (0.1-10% of pump energy) kick-starts a repeated or cascaded energy down-conversion of pump photons. This helps to greatly surpass the quantum-defect efficiency and results in exponential growth of THz energy over crystal length. In cryogenically cooled periodically poled lithium niobate, energy conversion efficiencies >8% for 100 ps pulses are predicted. The calculations account for cascading effects, absorption, dispersion and laser-induced damage. Due to the coupled nonlinear interaction of multiple triplets of waves, THz-COPA exhibits physics distinct from conventional three-wave mixing parametric amplifiers. This in turn governs optimal phase-matching conditions, evolution of optical spectra as well as limitations o...

  11. Second harmonic plasma emission involving ion sound waves

    Science.gov (United States)

    Cairns, Iver H.

    1987-01-01

    The theory for second harmonic plasma emission by the weak turbulence (or random phase) processes L + L + or - S to T, proceeding in two three-wave steps, L + or - S to L prime and L + L prime to T, where L, S and T denote Langmuir, ion sound and electromagnetic waves, respectively, is developed. Kinematic constraints on the characteristics and growth lengths of waves participating in the wave processes, and constraints on the characteristics of the source plasma, are derived. Limits on the brightness temperature of the radiation and the levels of the L prime and S waves are determined. Expressions for the growth rates and path-integrated wave temperatures are derived for simple models of the wave spectra and source plasma.

  12. Phononic High Harmonic Generation

    CERN Document Server

    Ganesan, Adarsh; Seshia, Ashwin A

    2016-01-01

    This paper reports the first experimental evidence for phononic low-order to high-order harmonic conversion leading to high harmonic generation. Similar to parametric resonance, phononic high harmonic generation is also mediated by a threshold dependent instability of a driven phonon mode. Once the threshold for instability is met, a cascade of harmonic generation processes is triggered. Firstly, the up-conversion of first harmonic phonons into second harmonic phonons is established. Subsequently, the down-conversion of second harmonic phonons into first harmonic phonons and conversion of first and second harmonic phonons into third harmonic phonons occur. On the similar lines, an eventual conversion of third harmonic phonons to high orders is also observed to commence. This surprising physical pathway for phononic low-order to high-order harmonic conversion may find general relevance to other physical systems.

  13. An electrostatic analog for generating cascade grids

    Science.gov (United States)

    Adamczyk, J. J.

    1980-01-01

    Accurate and efficient numerical simulation of flows through turbomachinery blade rows depends on the topology of the computational grids. These grids must reflect the periodic nature of turbomachinery blade row geometries and conform to the blade shapes. Three types of grids can be generated that meet these minimal requirements: through-flow grids, O-type grids, and C-type grids. A procedure which can be used to generate all three types of grids is presented. The resulting grids are orthogonal and can be stretched to capture the essential physics of the flow. A discussion is also presented detailing the extension of the generation procedure to three dimensional geometries.

  14. Characterization of the correlation between collagen fibril thickness and forward and backward second harmonic signal

    Science.gov (United States)

    Hsueh, Chiu-Mei; Hovhannisyan, Vladimir A.; Dong, Chen-Yuan

    2011-07-01

    Optical-based microscopy plays an important role in various scientific fields such as physics, chemistry and biology. Second harmonic generation (SHG) microscopy has become one of the indispensable tools for biomedical imaging for the last decade because the signal generated from SHG is sensitive to the objective structure and this amazing non-invasive method can also directly observe the objective without using extra fluorescent labels, especially for collagen molecules. As the most abundant protein in animals, collagen is responsible for a number of important structural and functional roles in vertebrates. For certain diseases, it has been shown that collagen fiber diameter has a significant variation and thus as a vital symptom for diagnosis. Moreover, collagen diameter is also a key parameter for fibrogenesis studying. Therefore, the determination of collagen fiber diameter is important for studying biophysical processes and identifying bioengineering applications. In this study, we investigated various collagen fibril thicknesses and the corresponding forward (FSHG) and backward (BSHG) second harmonic signal intensity variation. Our result exhibits that SHG intensity can quantify describe the relative collagen fibril thickness alteration, which also indicates the coherent effect difference between FSHG and BSHG. This approach demonstrates the capability of SHG imaging in providing collagen mechanical information and that may be applied in the evaluation of advancing collagen issues in vivo.

  15. Tunable All-Optical Wavelength Conversion Based on Cascaded SHG/DFG in a Ti:PPLN Waveguide Using a Single CW Control Laser

    DEFF Research Database (Denmark)

    Hu, Hao; Nouroozi, Rahman; Wang, Wenrui

    2012-01-01

    Tunable all-optical wavelength conversion (AOWC) of a 40-Gb/s RZ-OOK data signal based on cascaded second-harmonic generation (SHG) and difference-frequency generation (DFG) in a Ti:PPLN waveguide is demonstrated. Error-free performances with negligible power penalty are achieved for the waveleng...

  16. A 0.33-THz second-harmonic frequency-tunable gyrotron

    Science.gov (United States)

    Zheng-Di, Li; Chao-Hai, Du; Xiang-Bo, Qi; Li, Luo; Pu-Kun, Liu

    2016-02-01

    Dynamics of the axial mode transition process in a 0.33-THz second-harmonic gyrotron is investigated to reveal the physical mechanism of realizing broadband frequency tuning in an open cavity circuit. A new interaction mechanism about propagating waves, featured by wave competition and wave cooperation, is presented and provides a new insight into the beam-wave interaction. The two different features revealed in the two different operation regions of low-order axial modes (LOAMs) and high-order axial modes (HOAMs) respectively determine the characteristic of the overall performance of the device essentially. The device performance is obtained by the simulation based on the time-domain nonlinear theory and shows that using a 12-kV/150-mA electron beam and TE-3,4 mode, the second harmonic gyrotron can generate terahertz radiations with frequency-tuning ranges of about 0.85 GHz and 0.60 GHz via magnetic field and beam voltage tuning, respectively. Additionally, some non-stationary phenomena in the mode startup process are also analyzed. The investigation in this paper presents guidance for future developing high-performance frequency-tunable gyrotrons toward terahertz applications. Project supported by the National Natural Science Foundation of China (Grant Nos. 61471007, 61531002, 61522101, and 11275206) and the Seeding Grant for Medicine and Information Science of Peking University, China (Grant No. 2014-MI-01).

  17. One-dimensional hydrodynamic model generating a turbulent cascade

    Science.gov (United States)

    Matsumoto, Takeshi; Sakajo, Takashi

    2016-05-01

    As a minimal mathematical model generating cascade analogous to that of the Navier-Stokes turbulence in the inertial range, we propose a one-dimensional partial-differential-equation model that conserves the integral of the squared vorticity analog (enstrophy) in the inviscid case. With a large-scale random forcing and small viscosity, we find numerically that the model exhibits the enstrophy cascade, the broad energy spectrum with a sizable correction to the dimensional-analysis prediction, peculiar intermittency, and self-similarity in the dynamical system structure.

  18. One-dimensional hydrodynamic model generating turbulent cascade

    CERN Document Server

    Matsumoto, Takeshi

    2016-01-01

    As a minimal mathematical model generating cascade analogous to that of the Navier-Stokes turbulence in the inertial range, we propose a one-dimensional partial-differential-equation model that conserves the integral of the squared vorticity analogue (enstrophy) in the inviscid case. With a large-scale forcing and small viscosity, we find numerically that the model exhibits the enstrophy cascade, the broad energy spectrum with a sizable correction to the dimensional-analysis prediction, peculiar intermittency and self-similarity in the dynamical system structure.

  19. Acceleration of lithotripsy using cavitation bubbles induced by second-harmonic superimposition

    Science.gov (United States)

    Osuga, Masamizu; Yasuda, Jun; Jimbo, Hayato; Yoshizawa, Shin; Umemura, Shin-ichiro

    2016-07-01

    Shock wave lithotripsy potentially produces residual stone fragments too large to pass through ureters and significant injury to the normal tissue surrounding the stone. Previous works have shown that the collapse of cavitation bubbles induced by high-intensity focused ultrasound can produce small stone fragments via cavitation erosion. However, the erosion rate is hypothesized to be reduced by ultrasound attenuation by excessively generated bubble clouds. If so, it is important to generate the bubbles only on the stone surface. The effects of peak-negative-enhanced (PNE) and peak-positive-enhanced (PPE) waves obtained by second-harmonic superimposition were investigated to control cavitation bubbles. With the PNE waves, the bubbles were generated only on the stone surface and the maximum erosion rate was 232 ± 32 mg/min. All the fragments were smaller than 2 mm, which makes them pass through ureters naturally. The proposed method shows the potential to significantly improve the speed of lithotripsy.

  20. 3TiO_2-45.7BaO-51.3B_2O_3微晶玻璃的SHG%Second Harmonic Generation of the 3TiO_2-45.7BaO-51.3B_2O_3 Transparent Crystallized Glasses

    Institute of Scientific and Technical Information of China (English)

    曹艳丽; 陈静; 顾少轩; 郑玲江

    2009-01-01

    The crystallized glasses of 3TiO_2-45.7BaO-51.3B_2O_3 system were prepared by heat treatment method.The resuits of XRD and transmittance spectrurn show that transparent crystallized glass containing β-BBO is obtained.The second harmonic generation(SHG) effect of the crystallized glasses is researched by utilizing Maker-fringe technique.It is found that the inversion symmetry of the glass cannot be broken by small grain size and quantity microcystal when calcining at 580~620℃ for 4 h,and the SHG effect can notbeobserved.Theinversion symmetry of the glass was broken by β-BBO in the glass when cal cining at 620℃ for 8 h,which induces the occurrence of SHG effect.The SHG intensity gradually decreases after polishing The results indicate that β-BBO in the glass induced the SHG effect.%采用热处理的方法,制备3TiO_2-45.7BaO-51.3B_2O_3微晶玻璃,利用XRD、透射光谱研究表明,获得了含β-BBO微晶的透明微晶玻璃.采用Maker条纹法研究了微晶玻璃的二阶非线性光学效应,结果表明,当580~620℃热处理4 h时,微晶尺寸小、数量少,不足以破坏玻璃的各向同性,观测不到二次谐波信号;当620℃热处理8 h时,玻璃的β-BBO微晶破坏了玻璃的各向同性,诱导了二次谐波的产生;对该样品进行抛光后,二次谐波信号减弱直至消失,进一步表明玻璃表面的β-BBO微晶是导致玻璃产生二次谐波信号的原因.

  1. Polarization response of second-harmonic images for different collagen spatial distributions

    Science.gov (United States)

    Ávila, Francisco J.; del Barco, Oscar; Bueno, Juan M.

    2016-06-01

    The response to polarization of second-harmonic generation (SHG) microscopy images of samples with different collagen distributions (quasialigned, partially organized, and nonorganized) has been analyzed. A linear decay relationship between the external arrangement and polarization sensitivity was found. SHG signal from nonorganized samples presented a large structural dispersion and a weak dependence with incident polarization. Polarization dependence is also associated with the internal organization of the collagen fibers, directly related to the ratio of hyperpolarizabilities ρ. This parameter can experimentally be computed from the modulation of the SHG signal. The results show that both external and internal collagen structures are closely related. This provides a tool to obtain information of internal properties from the polarimetric response of the external spatial distribution of collagen, which might be useful in clinical diagnosis of pathologies related to changes in collagen structure.

  2. Second-harmonic microscopy of strain fields around through-silicon-vias

    Science.gov (United States)

    Cho, Yujin; Shafiei, Farbod; Mendoza, B. S.; Lei, Ming; Jiang, Tengfei; Ho, P. S.; Downer, M. C.

    2016-04-01

    Through-Silicon-Vias (TSVs)—10 μm-diameter conducting rods that connect vertically stacked silicon layers—provide three dimensional circuit integration, but introduce strain in the surrounding silicon when thermally cycled. Here, we noninvasively probe strain fields around Cu TSVs in Si(001) using optical second-harmonic generation (SHG) microscopy. Results are compared with micro-Raman spectra of the strained regions. We find that SHG probes strain fields more quickly than Raman spectroscopy, while maintaining comparable sensitivity and spatial resolution, and avoiding the need for spectral analysis. Moreover, SHG is selectively sensitive to axial shear components uiz (i = x, y) of the strain tensor that are often neglected in Raman analysis. Thus, SHG complements Raman spectroscopy.

  3. Enhanced Kerr electro-optic nonlinearity through cascaded Pockels effects

    CERN Document Server

    Li, Guang-Zhen; Jiang, Hao-Wei; Chen, Xian-Feng

    2015-01-01

    We demonstrated a large enhancement of Kerr electro-optic nonlinearity through cascaded Pockels effects in a domain inversion ferroelectric crystal. We designed a structure that can implement the cascaded Pockels effects and second-harmonic generation simultaneously. The energy coupling between the fundamental lights of different polarizations led to a large nonlinear phase shift, and thus an effective electro-optic nonlinear refractive index. The effective nonlinearity can be either positive or negative, causing the second-harmonic spectra to move towards the coupling center, which in turn, offered us a way to measure the effective electro-optic nonlinear refractive index. The corresponding enhanced Kerr electro-optic nonlinearity is more than three orders of magnitude higher than the intrinsic value. These results open a door to manipulate the nonlinear phase by applying external electric field instead of light intensity in noncentrosymmetric crystals.

  4. Ultralow-threshold cascaded Brillouin microlaser for tunable microwave generation.

    Science.gov (United States)

    Guo, Changlei; Che, Kaijun; Cai, Zhiping; Liu, Shuai; Gu, Guoqiang; Chu, Chengxu; Zhang, Pan; Fu, Hongyan; Luo, Zhengqian; Xu, Huiying

    2015-11-01

    We experimentally demonstrate an ultralow-threshold cascaded Brillouin microlaser for tunable microwave generation in a high-Q silica microsphere resonator. The threshold of the Brillouin microlaser is as low as 8 μW, which is close to the theoretical prediction. Moreover, the fifth-order Stokes line with a frequency shift up to 55 GHz is achieved with a coupled pump power of less than 0.6 mW. Benefiting from resonant wavelength shifts driven by thermal dynamics in the microsphere, we further realized tunable microwave signals with tuning ranges of 40 MHz at an 11 GHz band and 20 MHz at a 22 GHz band. To the best of our knowledge, it was the first attempt for tunable microwave source based on the whispering-gallery-mode Brillouin microlaser. Such a tunable microwave source from a cascaded Brillouin microlaser could find significant applications in aerospace, communication engineering, and metrology.

  5. Nonlinear optical response induced by a second-harmonic electric-field component concomitant with optical near-field excitation

    Science.gov (United States)

    Yamaguchi, Maiku; Nobusada, Katsuyuki; Yatsui, Takashi

    2015-10-01

    Electron dynamics excited by an optical near field (ONF) in a two-dimensional quantum dot model was investigated by solving a time-dependent Schrödinger equation. It was found that the ONF excitation of the electron caused two characteristic phenomena: a two-photon absorption and an induction of a magnetic dipole moment with a strong third-harmonic component. By analyzing the interaction dynamics of the ONF and the electron, we explained that the physical mechanism underlying these phenomena was the second-harmonic electric-field component concomitant with the near-field excitation originating from the nonuniformity of the ONF. Despite a y -polarized ONF source, the second-harmonic component of an x -polarized electric field was inherently generated. The effect of the second-harmonic electric-field component is not due to usual second-order nonlinear response but appears only when we explicitly consider the electron dynamics interacting with the ONF beyond the conventional optical response assuming the dipole approximation.

  6. Generation of femtosecond laser pulses tunable from 380 nm to 465 nm via cascaded nonlinear optical mixing in a noncollinear optical parametric amplifier with a type-I phase matched BBO crystal.

    Science.gov (United States)

    Lee, Chao-Kuei; Zhang, Jing-Yuan; Huang, J; Pan, Ci-Ling

    2003-07-14

    We report the generation of tunable femtosecond pulses from 380nm to 465nm near the degenerate point of a 405-nm pumped type-I BBO noncollinearly phase-matched optical parametric amplifier (NOPA). The tunable UV/blue radiation is obtained from sum frequency generation (SFG) between the OPA output and the residual fundamental beam at 810-nm and cascaded second harmonic generation (SHG) of OPA. With a fixed seeding angle, the generated SFG and SHG covers from 385 nm to 465-nm. With a pumping energy of 75 J at 405 nm, the optical conversion efficiency from the pump to the tunable SFG is more than 5% and the efficiency of SHG of the OPA is about 2%.

  7. Optical Cherenkov radiation by cascaded nonlinear interaction: an efficient source of few-cycle energetic near- to mid-IR pulses

    DEFF Research Database (Denmark)

    Bache, Morten; Bang, Ole; Zhou, Binbin;

    2011-01-01

    When ultrafast noncritical cascaded second-harmonic generation of energetic femtosecond pulses occur in a bulk lithium niobate crystal optical Cherenkov waves are formed in the near- to mid-IR. Numerical simulations show that the few-cycle solitons radiate Cherenkov (dispersive) waves in the λ = 2...... efficiency is up to 25%. Thus, optical Cherenkov waves formed with cascaded nonlinearities could become an efficient source of energetic near- to mid-IR few-cycle pulses....

  8. Slab melting and magma generation beneath the southern Cascade Arc

    Science.gov (United States)

    Walowski, K. J.; Wallace, P. J.; Clynne, M. A.

    2014-12-01

    Magma formation in subduction zones is interpreted to be caused by flux melting of the mantle wedge by fluids derived from dehydration of the downgoing oceanic lithosphere. In the Cascade Arc and other hot-slab subduction zones, however, most dehydration reactions occur beneath the forearc, necessitating a closer investigation of magma generation processes in this setting. Recent work combining 2-D steady state thermal models and the hydrogen isotope composition of olivine-hosted melt inclusions from the Lassen segment of the Cascades (Walowski et al., 2014; in review) has shown that partial melting of the subducted basaltic crust may be a key part of the subduction component in hot arcs. In this model, fluids from the slab interior (hydrated upper mantle) rise through the slab and cause flux-melting of the already dehydrated MORB volcanics in the upper oceanic crust. In the Shasta and Lassen segments of the southern Cascades, support for this interpretation comes from primitive magmas that have MORB-like Sr isotope compositions that correlate with subduction component tracers (H2O/Ce, Sr/P) (Grove et al. 2002, Borg et al. 2002). In addition, mass balance calculations of the composition of subduction components show ratios of trace elements to H2O that are at the high end of the global arc array (Ruscitto et al. 2012), consistent with the role of a slab-derived melt. Melting of the subducted basaltic crust should contribute a hydrous dacitic or rhyolitic melt (e.g. Jego and Dasgupta, 2013) to the mantle wedge rather than an H2O-rich aqueous fluid. We are using pHMELTS and pMELTS to model the reaction of hydrous slab melts with mantle peridotite as the melts rise through the inverted thermal gradient in the mantle wedge. The results of the modeling will be useful for understanding magma generation processes in arcs that are associated with subduction of relatively young oceanic lithosphere.

  9. TEMPORAL OPTICAL SOLITONS VIA MULTISTEP x(2) CASCADING

    Institute of Scientific and Technical Information of China (English)

    HUANG GUO-XIANG

    2001-01-01

    We consider a multistep X(2) cascading for light pulses with the dispersion of the system taken into account. Using the method of multiple scales we derive a set of coupled envelope equations governing the nonlinear evolution of the fundamental, second and third harmonic waves involved simultaneously in two nonlinear optical processes, i.e. second harmonic generation and sum frequency mixing. We show that three-wave temporal optical solitons are possible in three- and four-step cascading in the presence of a group-velocity mismatch between different pulses.

  10. Diagnostics of Femtosecond Laser-Plasmas Using Fundamental and Second Harmonic Emission

    Institute of Scientific and Technical Information of China (English)

    ZHAO Li-Zeng; ZHANG Ping; FENG Bao-Hua; WEI Zhi-Yi; ZHANG Jie

    2000-01-01

    By observing the fundamental and second harmonic emission from a plasma produced by a 150 fs, 5 mJ laser at 800nm, the electron temperature, the expansion speed and the scalelength of the plasma have been diagnosed. Moreover the polarization of the fundamental and second harmonic emission has been studied. This could be a useful diagnostic for modulation at the critical surface of the plasma.

  11. Cascaded H-bridge multilevel inverter for renewable energy generation

    Science.gov (United States)

    Pandey, Ravikant; Nath Tripathi, Ravi; Hanamoto, Tsuyoshi

    2016-04-01

    In this paper cascaded H-bridge multilevel inverter (CHBMLI) has been investigated for the application of renewable energy generation. Energy sources like solar, wind, hydro, biomass or combination of these can be manipulated to obtain alternative sources for renewable energy generation. These renewable energy sources have different electrical characteristics like DC or AC level so it is challenging to use generated power by connecting to grid or load directly. The renewable energy source require specific power electronics converter as an interface for conditioning generated power .The multilevel inverter can be utilized for renewable energy sources in two different modes, the power generation mode (stand-alone mode), and compensator mode (statcom). The performance of the multilevel inverter has been compared with two level inverter. In power generation mode CHBMLI supplies the active and reactive power required by the different loads. For operation in compensator mode the indirect current control based on synchronous reference frame theory (SRFT) ensures the grid operating in unity power factor and compensate harmonics and reactive power.

  12. Scanning second-harmonic optical microscopy of self-assembled InAlGaAs quantum dots

    DEFF Research Database (Denmark)

    Vohnsen, B.; Bozhevolnyi, S. I.; Pedersen, K.

    2001-01-01

    or in the illumination itself. Thus, a combination of scanning microscopy with SH detection may be a highly suitable candidate to reveal the presence of QD's embedded in an otherwise isotropic material. We have used scanning far-field (SFOM) and scanning near field optical microscopy (SNOM) techniques to locally probe......Microscopy provides a suitable technique for local probing of small ensembles of (or even individual) QD's, and when combined with the detection of second-harmonic (SH) generation the technique becomes suitable to reveal tiny changes of symmetry originating either in the material structures...

  13. Cross-polarized wave generation by effective cubic nonlinear optical interaction.

    Science.gov (United States)

    Petrov, G I; Albert, O; Etchepare, J; Saltiel, S M

    2001-03-15

    A new cubic nonlinear optical effect in which a linearly polarized wave propagating in a single quadratic medium is converted into a wave that is cross polarized to the input wave is observed in BBO crystal. The effect is explained by cascading of two different second-order processes: second-harmonic generation and difference frequency mixing.

  14. Cascaded third-harmonic generation in a single short-range-ordered nonlinear photonic crystal.

    Science.gov (United States)

    Sheng, Yan; Saltiel, Solomon M; Koynov, Kaloian

    2009-03-01

    Collinear third-harmonic generation at 526.7 nm was realized by the simultaneous phase matching of two second-order processes in a single quadratic crystal: second-harmonic generation (SHG) and sum-frequency mixing (SFM). The measured conversion efficiency was 12%. As a nonlinear medium a LiNbO(3) nonlinear photonic crystal with short-range order was used that allowed simultaneous phase matching by use of discrete reciprocal vector (for the SHG process) and continuous reciprocal vectors (for the SFM process). It was demonstrated that the third harmonic could be generated efficiently in such a crystal even if the intermediate process of SHG was not perfectly phase matched.

  15. Effect of annealing on the second harmonic amplitude of Giant Magneto-Impedance (GMI) voltage of a Co-Fe-Si-B amorphous wire

    Science.gov (United States)

    Pal, S. K.; Panda, A. K.; Mitra, A.

    Second harmonic amplitude ( V2f) of Giant Magneto-Impedance (GMI) voltage of (Fe 6Co 94) 72.5Si 12.5B 15 amorphous wires has been studied systematically for as-cast and Joule-heated states. Joule heating was carried out at current densities ( J) of 20-40 A/mm 2 for a period of 1-300 min. The amplitude of the second harmonic voltage ( V2f) initially increased with J, attained maximum and then decreased. The maximum amplitude of V2f was observed for the sample annealed at J=25 A/mm 2 for 5 min. The second harmonic peak shifted towards the higher field side with the increase of annealing current density and annealing period ( tp). Few-fold increase in the amplitude of the second harmonic voltage ( V2f) was observed due to the presence of a small dc bias current ( Ib) of amplitude 1 mA. The asymmetry in V2f was also observed in a Joule-heated sample. The observed asymmetry has been correlated with the bias field generated between the surface crystallized layer and the amorphous core. A small bias current of amplitude of 1 mA was applied along the direction of the applied field to minimize the asymmetry.

  16. Blue-shift of E{sub 2} critical point resonance in optical second-harmonic spectrum of Si nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Mendoza, Bernardo S. [Department of Photonics, Centro de Investigaciones en Optica, A. C. Leon, Guanajuato (Mexico); Wei, Junwei; Downer, Michael C. [Department of Physics, The University of Texas at Austin, Austin, Texas 78712-1081 (United States)

    2012-06-15

    The E{sub 2} critical point (CP) resonance in the second-harmonic spectrum of silica-embedded Si nanocrystals (NCs) of 3 and 5 nm average diameter is observed to be blue-shifted by 0.5 eV from its energy (4.4 eV) in the linear dielectric response {epsilon}({omega}) of the same samples. In contrast, the E{sub 1} CP resonance (3.4 eV) and a third resonance intermediate in energy (3.8 eV) between E{sub 1} and E{sub 2} occur at nearly the same energy in both linear and nonlinear spectra. We explain the anomalous E{sub 2} blue-shift by calculating the second-harmonic response function {delta}({omega}) of the NCs analytically from the measured {epsilon}({omega}) using a dipolium model. The analysis shows that the E{sub 2} blue-shift originates from the screening factors of the form [{epsilon}(2{omega})+2]{sup -1} and [2{epsilon}(2{omega})+3]{sup -1} that are unique to second-harmonic generation (SHG) from nanospheres. Strong interaction between E{sub 2} and E'{sub 1} (5.3 eV in bulk c-Si) resonant contributions to this factor pulls the E{sub 2} peak response toward the higher E'{sub 1} energy while negligibly influencing lower energy resonances. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Experimental and modelling investigations into the laser ablation with picosecond pulses at second harmonics

    Science.gov (United States)

    Boerner, Paul; Zandonadi, Germana; Eberle, Gregory; Wegener, Konrad

    2015-03-01

    Ablation threshold experiments on various materials are carried out using a picosecond laser generating second harmonic radiation in air at atmospheric pressure. Various materials are investigated which vary according to their different electronic band gap structure and include: silicon, fine grain polycrystalline diamond, copper, steel and tungsten carbide. Through the use of scanning electron microscopy and 3D confocal microscopy, the crater depth and diameter are determined and a correlation is found. The ablation thresholds are given for the aforementioned materials and compared with recent literature results. Picosecond laser-material interactions are modelled using the two-temperature model, simulated and compared with experimental results for metallic materials. An extension of the two-temperature model to semiconducting and insulating materials is discussed. This alternative model uses multiple rate equations to describe the transient free electron density. Additionally, a set of coupled ordinary differential equations describes the processes of multiphoton excitation, inverse bremsstrahlung, and collisional excitation. The resulting electron density distribution can be used as an input for an electron density dependent twotemperature model. This multiple rate equation model is a generic and fast model, which provides important information like ablation threshold, ablation depth and optical properties.

  18. Efficient second-harmonic imaging of collagen in histological slides using Bessel beam excitation

    Science.gov (United States)

    Vuillemin, Nelly; Mahou, Pierre; Débarre, Delphine; Gacoin, Thierry; Tharaux, Pierre-Louis; Schanne-Klein, Marie-Claire; Supatto, Willy; Beaurepaire, Emmanuel

    2016-07-01

    Second-harmonic generation (SHG) is the most specific label-free indicator of collagen accumulation in widespread pathologies such as fibrosis, and SHG-based measurements hold important potential for biomedical analyses. However, efficient collagen SHG scoring in histological slides is hampered by the limited depth-of-field of usual nonlinear microscopes relying on focused Gaussian beam excitation. In this work we analyze theoretically and experimentally the use of Bessel beam excitation to address this issue. Focused Bessel beams can provide an axially extended excitation volume for nonlinear microscopy while preserving lateral resolution. We show that shaping the focal volume has consequences on signal level and scattering directionality in the case of coherent signals (such as SHG) which significantly differ from the case of incoherent signals (two-photon excited fluorescence, 2PEF). We demonstrate extended-depth SHG-2PEF imaging of fibrotic mouse kidney histological slides. Finally, we show that Bessel beam excitation combined with spatial filtering of the harmonic light in wave vector space can be used to probe collagen accumulation more efficiently than the usual Gaussian excitation scheme. These results open the way to SHG-based histological diagnoses.

  19. Nonlinear optical response of the collagen triple helix and second harmonic microscopy of collagen liquid crystals

    Science.gov (United States)

    Deniset-Besseau, A.; De Sa Peixoto, P.; Duboisset, J.; Loison, C.; Hache, F.; Benichou, E.; Brevet, P.-F.; Mosser, G.; Schanne-Klein, M.-C.

    2010-02-01

    Collagen is characterized by triple helical domains and plays a central role in the formation of fibrillar and microfibrillar networks, basement membranes, as well as other structures of the connective tissue. Remarkably, fibrillar collagen exhibits efficient Second Harmonic Generation (SHG) and SHG microscopy proved to be a sensitive tool to score fibrotic pathologies. However, the nonlinear optical response of fibrillar collagen is not fully characterized yet and quantitative data are required to further process SHG images. We therefore performed Hyper-Rayleigh Scattering (HRS) experiments and measured a second order hyperpolarisability of 1.25 10-27 esu for rat-tail type I collagen. This value is surprisingly large considering that collagen presents no strong harmonophore in its amino-acid sequence. In order to get insight into the physical origin of this nonlinear process, we performed HRS measurements after denaturation of the collagen triple helix and for a collagen-like short model peptide [(Pro-Pro-Gly)10]3. It showed that the collagen large nonlinear response originates in the tight alignment of a large number of weakly efficient harmonophores, presumably the peptide bonds, resulting in a coherent amplification of the nonlinear signal along the triple helix. To illustrate this mechanism, we successfully recorded SHG images in collagen liquid solutions by achieving liquid crystalline ordering of the collagen triple helices.

  20. In vivo wound healing diagnosis with second harmonic and fluorescence lifetime imaging

    Science.gov (United States)

    Deka, Gitanjal; Wu, Wei-Wen; Kao, Fu-Jen

    2013-06-01

    Skin wounds heal when a series of cell lineages are triggered, followed by collagen deposition, to reconstruct damaged tissues. This study evaluates the regeneration of collagen and change in cellular metabolic rate in vivo during wound healing in rats, with second harmonic generation (SHG) and fluorescence lifetime imaging microscopy respectively. The metabolic rate of cells is reflected through the lifetime of the autofluorescence from the co-enzyme protein, reduced nicotinamide adenine dinucleotide, due to its change in the relative concentration of bound and free forms. A higher than normal cellular metabolic rate is observed during the first week of healing, which decreases gradually after eight days of wound formation. SHG signal intensity change indicates the net degradation of collagen during the inflammatory phase, and net regeneration begins on day five. Eventually, the quantity of collagen increases gradually to form a scar tissue as the final product. Importantly, this work demonstrates the feasibility of an in vivo imaging approach for a normal wound on rat skin, which has the potential to supplement the noninvasive clinical diagnosis of wounds.

  1. Second-Harmonic Scattering as a Probe of Structural Correlations in Liquids

    CERN Document Server

    Tocci, Gabriele; Wilkins, David M; Roke, Sylvie; Ceriotti, Michele

    2016-01-01

    Second-harmonic scattering experiments of water and other bulk molecular liquids have long been assumed to be insensitive to interactions between the molecules. The measured intensity is generally thought to arise from incoherent scattering due to individual molecules. We introduce a method to compute the second-harmonic scattering pattern of molecular liquids directly from atomistic computer simulations, which takes into account the coherent terms. We apply this approach to large-scale molecular dynamics simulations of liquid water, where we show that nanosecond second-harmonic scattering experiments contain a coherent contribution arising from radial and angular correlations on a length scale of < 1 nm, much shorter than had been recently hypothesized (Shelton, D. P. J. Chem. Phys. 2014, 141). By combining structural correlations from simulations with experimental data (Shelton, D. P. J. Chem. Phys. 2014, 141), we can also extract an effective molecular hyperpolarizability in the liquid phase. This work ...

  2. Local field enhanced second-harmonic response of organic nanofibers deposited on encapsulated plasmonic substrates

    Science.gov (United States)

    Kostiučenko, Oksana; Leißner, Till; Brewer, Jonathan R.; Tamulevičius, Tomas; Tamulevičius, Sigitas; Fiutowski, Jacek; Rubahn, Horst-Günter

    2015-08-01

    In this work, enhancement of the second harmonic response of organic nanofibers deposited on encapsulated and robust plasmonic active substrate is experimentally demonstrated. Organic nanofibers grown from functionalized paraquaterphenylene (CNHP4) molecules have been transferred on lithographically defined regular arrays of gold nanostructures, which subsequently have been coated with thin films of diamond-like carbon with 25, 55 and 100 nm thickness. Femtosecond laser scanning microscopy enables us to identify enhancement of the second harmonic response of the fibers. This is facilitated by a preservation of the field enhancement effects, which appear on the nanostructures and remain significant on top of the coating layer.

  3. Influence of Josephson current second harmonic on stability of magnetic flux in long junctions

    Science.gov (United States)

    Atanasova, P. K. H.; Boyadjiev, T. L.; Shukrinov, Y. U. M.; Zemlyanaya, E. V.; Seidel, P.

    2010-11-01

    We study the long Josephson junction (LJJ) model which takes into account the second harmonic of the Fourier expansion of Josephson current. The dependence of the static magnetic flux distributions on parameters of the model are investigated numerically. Stability of the static solutions is checked by the sign of the smallest eigenvalue of the associated Sturm-Liouville problem. New solutions which do not exist in the traditional model, have been found. Investigation of the influence of second harmonic on the stability of magnetic flux distributions for main solutions is performed.

  4. High-resolution second-harmonic microscopy of poled silica waveguides

    DEFF Research Database (Denmark)

    Beermann, Jonas; Bozhevolnyi, Sergey I.; Pedersen, Kjeld;

    2003-01-01

    A second-harmonic scanning optical microscopy (SHSOM) apparatus operating in reflection is used for high-resolution imaging of second-order optical non-linearities (SONs) in electric-field poled silica-based waveguides. SHSOM of domain walls in a periodically poled KTiOPO4 crystal is performed......, and the spatial resolution at the pump wavelength of 790 nm is determined to be better than 0.7 m. SHSOM images of positively poled silica waveguides were obtained for different polarization combinations of the incident pump beam and the detected second-harmonic radiation. Calibration of the SHSOM with a Ga...

  5. Second-harmonic ion cyclotron resonance heating scenarios of Aditya tokamak plasma

    Indian Academy of Sciences (India)

    Asim Kumar Chattopadhyay; S V Kulkarni; R Srinivasan; Aditya Team

    2015-10-01

    Plasma heating with the fast magnetosonic waves in the ion cyclotron range of frequencies (ICRF) is one of the auxiliary heating schemes of Aditya tokamak. Numerical simulation of second-harmonic resonance heating scenarios in low-temperature, low-density Aditya plasma has been carried out for fast magnetosonic wave absorption in ICRF range, using full-wave ion cyclotron heating code TORIC combined with Fokker–Planck quasilinear solver SSFPQL and the results are explained. In such low-temperature, low-density plasma, ion absorption for second-harmonic resonance heating is less but significant amount of direct electron heating is observed.

  6. Comparison of fundamental, second harmonic, and superharmonic imaging: A simulation study

    NARCIS (Netherlands)

    Van Neer, P.L.M.J.; Danilouchkine, M.G.; Verweij, M.D.; Demi, L.; Voormolen, M.M.; Van der Steen, A.F.W.; De Jong, N.

    2011-01-01

    In medical ultrasound, fundamental imaging (FI) uses the reflected echoes from the same spectral band as that of the emitted pulse. The transmission frequency determines the trade-off between penetration depth and spatial resolution. Tissue harmonic imaging (THI) employs the second harmonic of the e

  7. Local field enhanced second-harmonic response of organic nanofibers deposited on encapsulated plasmonic substrates

    DEFF Research Database (Denmark)

    Kostiučenko, Oksana; Leißner, Till; Brewer, Jonathan R.

    2015-01-01

    on lithographically defined regular arrays of gold nanostructures, which subsequently have been coated with thin films of diamond-like carbon with 25, 55 and 100 nm thickness. Femtosecond laser scanning microscopy enables us to identify enhancement of the second harmonic response of the fibers. This is facilitated...

  8. INFLUENCE OF CHROMATIC DISPERSION, DISPERSION SLOPE, DISPERSION CURVATURE ON MICROWAVE GENERATION USING TWO CASCADE MODULATORS

    OpenAIRE

    Mandeep Singh; S.K. Raghuwanshi

    2013-01-01

    This work presents a theoretical study of harmonic generation of microwave signals after detection of a modulated optical carrier in cascaded two electro-optic modulators. Dispersion is one of the major limiting factors for microwave generation in microwave photonics. In this paper, we analyze influence of chromatic dispersion, dispersion slope, dispersion curvature on microwave generation using two cascaded MZMs and it has been found that output intensity of photodetector reduces when disper...

  9. Near-field optical second-harmonic technique for detection and characterization of semiconductor thin film electron-scattering domain boundaries

    Science.gov (United States)

    Shafiei, Farbod; Orzali, Tommaso; Bersuker, Gennadi; Michael, Downer

    2015-03-01

    Understanding electron transport in epitaxial semiconductor thin films and low dimension systems is crucial for new electro-optic devices. III-V films grown on Si integrate high carrier mobility into the established Si platform, but are susceptible to formation of sub-micron anti-phase domains that possess unwanted Ga-Ga or As-As electron-scattering defects at their boundaries. Optical second-harmonic generation provides sensitive, specific and noninvasive but so far only spatially-integrated characterization for these defects. We introduce a fiber based nearfield scanning optical second harmonic microscopy for the first time to fully resolve the electron scattering boundaries on III-V/Si films. This technique reveal variations in electron scattering boundaries structure as growth conditions, epitaxial film composition, and substrate vary, and are compared with surface topography, darkfield transmission electron microscopy and electron back scatter diffraction. Suppression of the electron-scattering boundaries has been explored.

  10. Strongly Enhanced and Directionally Tunable Second-Harmonic Radiation by a Plasmonic Particle-in-Cavity Nanoantenna

    CERN Document Server

    Xiong, Xiaoyan Y Z; Sha, Wei E I; Lo, Yat Hei; Chew, Weng Cho

    2016-01-01

    Second-harmonic (SH) generation is tremendously important for nonlinear sensing, microscopy and communication system. One of the great challenges of current designs is to enhance the SH signal and simultaneously tune its radiation direction with a high directivity. In contrast to the linear plasmonic scattering dominated by a bulk dipolar mode, a complex surface-induced multipolar interaction sets a fundamental limit to control the SH radiation from metallic nanostructures. In this work, we harness plasmonic hybridization mechanism together with a special selection rule governing the SH radiation to achieve the high-intensity and tunable-direction emission by a metallic particle-in-cavity nanoantenna (PIC-NA). The nanoantenna is modelled with a first-principle, self-consistent boundary element method, which considers the depletion of pump waves. The giant SH enhancement arises from a hybridized gap plasmon resonance between the small particle and the large cavity that functions as a concentrator and reflector...

  11. Second harmonic and subharmonic for non-linear wideband contrast imaging using a capacitive micromachined ultrasonic transducer array.

    Science.gov (United States)

    Novell, Anthony; Escoffre, Jean-Michel; Bouakaz, Ayache

    2013-08-01

    When insonified with suitable ultrasound excitation, contrast microbubbles generate various non-linear scattered components, such as the second harmonic (2H) and the subharmonic (SH). In this study, we exploit the wide frequency bandwidth of capacitive micromachined ultrasonic transducers (CMUTs) to enhance the response from ultrasound contrast agents by selective imaging of both the 2H and SH components simultaneously. To this end, contrast images using the pulse inversion method were recorded with a 64-element CMUT linear array connected to an open scanner. In comparison to imaging at 2H alone, the wideband imaging including both the 2H and SH contributions provided up to 130% and 180% increases in the signal-to-noise and contrast-to-tissue ratios, respectively. The wide-frequency band of CMUTs offers new opportunities for improved ultrasound contrast agent imaging.

  12. Finite-size scaling of two-point statistics and the turbulent energy cascade generators.

    Science.gov (United States)

    Cleve, Jochen; Dziekan, Thomas; Schmiegel, Jürgen; Barndorff-Nielsen, Ole E; Pearson, Bruce R; Sreenivasan, Katepalli R; Greiner, Martin

    2005-02-01

    Within the framework of random multiplicative energy cascade models of fully developed turbulence, finite-size-scaling expressions for two-point correlators and cumulants are derived, taking into account the observationally unavoidable conversion from an ultrametric to an Euclidean two-point distance. The comparison with two-point statistics of the surrogate energy dissipation, extracted from various wind tunnel and atmospheric boundary layer records, allows an accurate deduction of multiscaling exponents and cumulants, even at moderate Reynolds numbers for which simple power-law fits are not feasible. The extracted exponents serve as input for parametric estimates of the probabilistic cascade generator. Various cascade generators are evaluated.

  13. The CCFM Monte Carlo generator CASCADE Version 2.2.03

    Energy Technology Data Exchange (ETDEWEB)

    Jung, H. [DESY, Hamburg (Germany); University of Antwerp, Antwerp (Belgium); Baranov, S. [Lebedev Physics Institute, Moscow (Russian Federation); Deak, M. [University of Madrid, Instituto de Fisica Teorica UAM/CSIC, Madrid (Spain); Grebenyuk, A.; Hentschinski, M.; Knutsson, A.; Kraemer, M. [DESY, Hamburg (Germany); Hautmann, F. [University of Oxford, Oxford (United Kingdom); Kutak, K. [University of Antwerp, Antwerp (Belgium); Lipatov, A.; Zotov, N. [Moscow State University, SINP, Moscow (Russian Federation)

    2010-12-15

    Cascade is a full hadron level Monte Carlo event generator for ep, {gamma}p and p anti p and pp processes, which uses the CCFM evolution equation for the initial state cascade in a backward evolution approach supplemented with off-shell matrix elements for the hard scattering. A detailed program description is given, with emphasis on parameters the user wants to change and common block variables which completely specify the generated events. (orig.)

  14. Detection of second harmonic of phase dependence of superconducting current in Nb/Au/YBCO heterojunctions

    CERN Document Server

    Komissinskij, F V; Ilichev, E V; Ivanov, Z G

    2001-01-01

    The results of the experimental study on the current phase dependence (CPD) of the heterotransitions, consisting of the niobium and the YBa sub 2 Cu sub 3 O sub x (YBCO) film with an additional interlayer from gold (Nb/Au/YBCO) are presented. The CPD measurement is carried out through the radiofrequency superconducting quantum interferometer. The CPD second harmonic is determined in the Nb/Au/YBCO heterotransitions. Possible causes of its appearance are discussed within the frames of the d +- s combined symmetry of the YBCO order parameter. One of the causes of the CPD second harmonic appearance is the twinning of the YBCO films (001). The second cause of existing the anomalously high critical current consists in the availability of the Nb/Au boundary with the transparence of approx 10 sup - sup 1 in the Nb/Au/YBCO

  15. A nonlinear acoustic metamaterial: Realization of a backwards-traveling second-harmonic sound wave.

    Science.gov (United States)

    Quan, Li; Qian, Feng; Liu, Xiaozhou; Gong, Xiufen

    2016-06-01

    An ordinary waveguide with periodic vibration plates and side holes can realize an acoustic metamaterial that simultaneously possesses a negative bulk modulus and a negative mass density. The study is further extended to a nonlinear case and it is predicted that a backwards-traveling second-harmonic sound wave can be obtained through the nonlinear propagation of a sound wave in such a metamaterial.

  16. Measurement of reflected second harmonics and nonlinearity parameter using a transducer with complex structure

    Institute of Scientific and Technical Information of China (English)

    MA Qingyu; LU Rongrong; ZHANG Dong; GONG Xiufen; LIU Xiaozhou

    2003-01-01

    Measurement of nonlinearity parameter using the second-harmonic reflective model is studied. A new kind of compound transducer is designed and fabricated for this purpose. With this transducer and the finite amplitude insert-substitution method, an experimental system to measure the nonlinearity parameter using reflective model is developed. B/A values of some liquids and biological tissues are obtained and results coincide well with those presented in the literatures.

  17. Entropy generation minimization: A practical approach for performance evaluation of temperature cascaded co-generation plants

    KAUST Repository

    Myat, Aung

    2012-10-01

    We present a practical tool that employs entropy generation minimization (EGM) approach for an in-depth performance evaluation of a co-generation plant with a temperature-cascaded concept. Co-generation plant produces useful effect production sequentially, i.e., (i) electricity from the micro-turbines, (ii) low pressure steam at 250 °C or about 8-10 bars, (iii) cooling capacity of 4 refrigeration tones (Rtons) and (iv) dehumidification of outdoor air for air conditioned space. The main objective is to configure the most efficient configuration of producing power and heat. We employed entropy generation minimization (EGM) which reflects to minimize the dissipative losses and maximize the cycle efficiency of the individual thermally activated systems. The minimization of dissipative losses or EGM is performed in two steps namely, (i) adjusting heat source temperatures for the heat-fired cycles and (ii) the use of Genetic Algorithm (GA), to seek out the sensitivity of heat transfer areas, flow rates of working fluids, inlet temperatures of heat sources and coolant, etc., over the anticipated range of operation to achieve maximum efficiency. With EGM equipped with GA, we verified that the local minimization of entropy generation individually at each of the heat-activated processes would lead to the maximum efficiency of the system. © 2012.

  18. Energy spectrum of cascades generated by muons in Baksan underground scintillation telescope

    Science.gov (United States)

    Bakatanov, V. N.; Chudakov, A. E.; Novoseltsev, Y. F.; Novoseltseva, M. V.; Achkasov, V. M.; Semenov, A. M.; Stenkin, Y. V.

    1985-01-01

    Spectrum of cascades generated by cosmic ray muons underground is presented. The mean zenith angle of the muon arrival is theta=35 deg the depth approx. 1000 hg/sq cm. In cascades energy range 700 GeV the measured spectrum is in agreement with the sea-level integral muon spectrum index gamma=3.0. Some decrease of this exponent has been found in the range 4000 Gev.

  19. Experimental investigation of a vibrating axial turbine cascade in presence of upstream generated aerodynamic gusts

    OpenAIRE

    Rottmeier, Fabrice; Bölcs, Albin

    2005-01-01

    An experimental investigation has been conducted in the non-rotating annular test facility of the "Laboratoire de Thermique Appliquée et de Turbomachines" (LTT), "École Polytechnique Fédérale de Lausanne" (EPFL). During this investigation, the unsteady aerodynamic response of a turbine cascade was investigated for three different cases: (1) the clamped blades subjected to periodic, upstream generated aerodynamic gusts, (2) the cascade forced to vibrate in the travelling wave mode in a uniform...

  20. Experimental investigation of a vibrating axial turbine cascade in presence of upstream generated aerodynamic gusts

    OpenAIRE

    Rottmeier, Fabrice

    2003-01-01

    An experimental investigation has been conducted in the non-rotating annular test facility of the "Laboratoire de Thermique Appliquée et de Turbomachines" (LTT), "École Polytechnique Fédérale de Lausanne" (EPFL). During this investigation, the unsteady aerodynamic response of a turbine cascade was investigated for three different cases: (1) the clamped blades subjected to periodic, upstream generated aerodynamic gusts, (2) the cascade forced to vibrate in the travelling wave mode in a uniform...