WorldWideScience

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. 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

    for efficient power scaling of single-pass SHG beyond such limits using a cascade of nonlinear crystals, in which the first crystal is chosen for high nonlinear efficiency and the subsequent crystal(s) are chosen for power handling ability. Using this highly efficient singlepass concept, we generate 3...... the concept successfully combines the high efficiency of the first stage with the good power handling properties of the subsequent stages. The concept is generally applicable and can be expanded with more stages to obtain even higher efficiency, and extends also to other combinations of nonlinear......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...

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

    DEFF Research Database (Denmark)

    Bache, Morten; Bang, Ole; Krolikowski, Wieslaw; Moses, Jeffrey; Wise, Frank W.

    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....

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

    International Nuclear Information System (INIS)

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

    Energy Technology Data Exchange (ETDEWEB)

    Gajić, A. [School of Electrical Engineering, University of Belgrade, Bulevar kralja Aleksandra 73, 11120 Belgrade (Serbia); Telekom Srbija, a.d., Takovska 2, 11000 Belgrade (Serbia); Radovanović, J., E-mail: radovanovic@etf.bg.ac.rs; Milanović, V. [School of Electrical Engineering, University of Belgrade, Bulevar kralja Aleksandra 73, 11120 Belgrade (Serbia); Indjin, D.; Ikonić, Z. [School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT (United Kingdom)

    2014-02-07

    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 In{sub 0.53}Ga{sub 0.47}As/Al{sub 0.48}In{sub 0.52}As structure and presented its output characteristics.

  7. Walk off compensation, multicrystal, cascaded, single pass, second harmonic generation in LBO

    Science.gov (United States)

    Ji, B.; Zheng, X. S.; Cai, Z. P.; Xu, H. Y.; Jia, F. Q.

    2012-09-01

    Walk off compensation and multi crystal (MC) cascaded single pass second harmonic generation (SP-SHG) in LBO was combined to improve the SHG conversion efficiency. We report a simple and compact implementation for (SP-SHG) of radiation, based on a cascaded multicrystal (MC) scheme that can provide high conversion efficiency without other focusing device, the enhancement factor of 2.9 was realized. At an incident pump power of 20 W, the average power of 6.1 W and pulse width of 12 ns green laser was obtained at a repetition rate of 42.4 kHz, corresponding to a peak power of 12 kW and single pulse energy of 144 μJ. The optical to optical conversion efficiency from diode to green and from IR to green laser are about 30.5 and 67.8%, the whole length of this system is about 150 mm, the output fluctuation of this system is less than 5% in 2 h.

  8. Nonlinearly Driven Second Harmonics of Alfven Cascades

    International Nuclear Information System (INIS)

    In recent experiments on Alcator C-Mod, measurements of density fluctuations with Phase Contrast Imaging through the plasma core show a second harmonic of the basic Alfven Cascade (AC) signal. The present work describes the perturbation at the second harmonic as a nonlinear sideband produced by the Alfven Cascade eigenmode via quadratic terms in the MHD equations. (author)

  9. Second harmonic generation in the moving media

    OpenAIRE

    Ghalandari, Mahboubeh

    2015-01-01

    Because of the importance of second harmonic generation in some nonlinear media, in this paper, we investigated induced second harmonic generation in diamond where there is no intrinsic second order susceptibility, X(2). The electric field is proposed to introduce moving susceptibility of the second order and induce second harmonic generation. Then, spatiotemporal (QPM) is applied to optimize the induced second harmonic generation. Numerical results reveals that in this way, the induced secon...

  10. Organometallic Salts Generate Optical Second Harmonics

    Science.gov (United States)

    Marder, Seth R.; Perry, Joseph W.

    1991-01-01

    Series of organometallic salts exhibit large second-order dielectric susceptibilities, as evidenced by generation of second harmonics when illuminated at visible and near-infrared wavelengths. Investigations of these and related compounds continue with view toward development of materials for use as optical second-harmonic generators, electro-optical modulators, optical switches, piezoelectric sensors, and parametric crystals.

  11. Imaging with Second-Harmonic Generation Nanoparticles

    Science.gov (United States)

    Hsieh, Chia-Lung

    Second-harmonic generation nanoparticles show promise as imaging probes due to their coherent and stable signal with a broad flexibility in the choice of excitation wavelength. In this thesis, we developed and demonstrated barium titanate nanoparticles as second-harmonic radiation imaging probes. We studied the absolute second-harmonic generation efficiency of the nanoparticles on single-particle level. The polarization dependent second-harmonic signal of single nanoparticles was studied in detail. From the measured polar response, we were able to find the orientation of the nanoparticle. We developed a biochemical interface for using the second-harmonic nanoprobes as biomarkers, including in vitro cellular imaging and in vivo live animal imaging. The nanoparticles were surface functionalized with primary amine groups for stable colloidal dispersion. We achieved specific labeling of the second-harmonic nanoprobes via immunostaining where the antibodies were covalently conjugated onto the nanoparticles. We observed no toxicity of the functionalized nanoparticles to biological cells. The coherent second-harmonic signal radiated from the nanoparticles offers opportunities for new imaging techniques. Using interferometric detection, namely harmonic holography, both amplitude and phase of the second-harmonic field can be captured. Through digital beam propagation, three-dimensional field distribution, reflecting three-dimensional distribution of the nanoparticles, can be reconstructed. We achieved a scan-free three-dimensional imaging of nanoparticles in biological cells with sub-micron spatial resolution by using the harmonic holographic microscope. We further exploited the coherent second-harmonic signal for imaging through scattering media by performing optical phase conjugation of the second-harmonic signal. We demonstrated an all-digital optical phase conjugation of the second-harmonic signal originated from a nanoparticle by combining harmonic holography and

  12. AlGaAs guided-wave second-harmonic generation at 2.23  μm from a quantum cascade laser.

    Science.gov (United States)

    Ozanam, C; Savanier, M; Lemaître, A; Almuneau, G; Carras, M; Favero, I; Ducci, S; Leo, G

    2014-09-01

    We demonstrate the frequency doubling of a quantum cascade laser in a multilayered, partially oxidized GaAs/AlOx waveguide. Using the waveguide width to fulfill the phase-matching condition, the second harmonic is generated in the wavelength range between 2.2 and 2.4 μm, where not many semiconductor sources are commercially available to date. We discuss the impact of a few fabrication and experimental parameters on the conversion efficiency, an essential step toward the improvement and practical implementation of this proof-of-principle semiconductor microsystem. PMID:25321354

  13. Variable wave vector second harmonic generation in phenanthrene

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, C.K.; Small, G.J.

    1982-04-01

    Second harmonic generation is observed in phenanthrene crystals. The experimental set is used allowed the simultaneous detection of two proton excitation (TPE) and second harmonic generation. (SHG). (AIP)

  14. Second Harmonic X-wave Generation

    CERN Document Server

    Conti, C

    2002-01-01

    In the process of optical second-harmonic generation an X-wave, travelling at the group velocity of the fundamental frequency, spontaneously forms. Its parameters, as well as the angular spectrum, are directly correlated to the group velocity mismatch and to the wavevector mismatch between the two harmonics. A novel mechanism for spatio-temporal localized waves generation is thus proposed.

  15. Spatial mode discrimination using second harmonic generation

    DEFF Research Database (Denmark)

    Delaubert, Vincent; Lassen, Mikael Østergaard; Pulford, David; Bachor, Hans-A.; harb, Charles

    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...

  16. Phase matching in second harmonic generation

    International Nuclear Information System (INIS)

    Phase-matching of coupled modes is investigated for the intracavity second harmonic generation in the instability region. In the positive P-representation using numerical solution of Langevin stochastic equations for this system the joint phase distribution function of fundamental and second harmonic modes is calculated. It is shown that for large time and initial vacuum states of both modes the distribution function in the right from bifurcation point has a dip. A removing of the system to the right from the bifurcation point leads to dip's size enhancement.10 refs

  17. Resonance Thirring solitons in type II second-harmonic generation

    Science.gov (United States)

    Trillo, Stefano

    1996-11-01

    It is shown that second-harmonic generation in a grating allows one to cancel the group-velocity difference between two polarization components at fundamental by means of nonlinearly induced phase shifts. This occurs when a new type of cascading soliton propagates on resonance.

  18. CW fiber laser for second harmonic generation:

    OpenAIRE

    Podobnik, Boštjan; Petkovšek, Rok; Možina, Janez; Novak, Vid

    2011-01-01

    We report on a reduced-complexity laser-diode-seeded master-oscillator-power-amplifier setup of a continuous wave fiber laser, with a single-stage ytterbium doped photonic crystal fiber amplifier. The laser is capable of generating up to 7.5 W single-transverse-mode, narrow-linewidth, polarized output suitable for second harmonic generation. The approach used possesses a further power scaling potential.

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

    International Nuclear Information System (INIS)

    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. (paper)

  20. Enhanced Second Harmonic Generation from Coupled Asymmetric Plasmonic Metal Nanostructures

    OpenAIRE

    Yildiz, Bilge Can; Tasgin, Mehmet Emre; Abak, Musa Kurtulus; Coskun, Sahin; Unalan, Husnu Emrah; Bek, Alpan

    2014-01-01

    We show that second harmonic generation can be enhanced by Fano resonant coupling of asymmetric plasmonic metal nanostructures. We develop a theoretical model examining the effects of electromagnetic interaction between two metal nanostructures on the second harmonic generation. We compare the second harmonic generation efficiency of a single plasmonic metal nanostructure with that of two coupled ones. We show that second harmonic generation from a single metal nanostructure can be enhanced a...

  1. Arbitrary orbital angular momentum addition in second harmonic generation

    International Nuclear Information System (INIS)

    We demonstrate second harmonic generation performed with optical vortices with different topological charges imprinted on orthogonal polarizations. Besides the intuitive charge doubling, we implement arbitrary topological charge addition on the second harmonic field using polarization as an auxiliary parameter. (paper)

  2. 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.

  3. 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

  4. Powders Analysis by Second Harmonic Generation Microscopy.

    Science.gov (United States)

    Chowdhury, Azhad U; Zhang, Shijie; Simpson, Garth J

    2016-04-01

    A microscopy approach is developed for quantifying second harmonic generation (SHG) activity of powders that largely decouples linear and nonlinear optical interactions. Decoupling the linear and nonlinear optical effects provides a means to independently evaluate and optimize the role of each in crystal engineering efforts and facilitates direct comparisons between experimental and computational predictions of lattice hyperpolarizabilities. In this respect, the microscopy-based approach nicely complements well-established Kurtz-Perry ( J. Appl. Phys. 1968 , 39 , 3798 ) and related methods, in which collimated sources are used for powders analysis. Using a focused fundamental beam places a controllable upper bound on the interaction length, given by the depth of field. Because measurements are performed on a per-particle basis, crystal size-dependent trends can be recovered from a single powdered sample. An analytical model that includes scattering losses of a focused Gaussian beam reliably predicted several experimental observations. Specifically, the measured scattering length for SHG was in excellent agreement with the value predicted based on the particle size distribution. Additionally, histograms of the SHG intensities as functions of particle size and orientation agreed nicely with predictions from the model. PMID:26929984

  5. Second Harmonic Generation Imaging Microscopy: Applications to Diseases Diagnostics

    OpenAIRE

    Campagnola, Paul

    2011-01-01

    Second Harmonic Generation microscopy has emerged as a powerful new optical imaging modality. This Feature describes its chemical and physical principles and highlights current applications in disease diagnostics.

  6. Coloured conical emission via second-harmonic generation

    CERN Document Server

    Trillo, S; Trapani, P D; Jedrkiewicz, O; Trull, J; Valiulis, G; Bellanca, G

    2002-01-01

    We predict that the combination of space and time modulational instabilities occuring via parametric wave-mixing in quadratic media leads to coloured conical emission. This phenomenon should be observed under conditions usually employed in second-harmonic generation experiments.

  7. 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.

  8. 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.

  9. Theory of second-harmonic generation in silica nanowires

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper

    2010-01-01

    The possibility of second-harmonic generation based on surface dipole and bulk multipole nonlinearities in silica nanowires is investigated numerically. Both circular and microstructured nanowires are considered. Phase matching is provided by propagating the pump field in the fundamental mode......, while generating the second harmonic in one of the modes of the LP11 multiplet. This is shown to work in both circular and microstructured nanowires, although only one of the LP11 modes can be phase-matched in the microstructure. The prospect of obtaining large conversion efficiencies in silica......-based nanowires is critically discussed, based on simulations of second-harmonic generation in nanowires with a fluctuating phase-matching wavelength. It is concluded that efficient wavelength conversion will either require strong improvements in the nanowire uniformity, or an increase of the second...

  10. Theory of surface second-harmonic generation in silica nanowires

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper

    2010-01-01

    The possibility of second-harmonic generation based on surface dipole and bulk multipole nonlinearities in silica nanowires is investigated numerically. Both circular and microstructured nanowires are considered. Phase matching is provided by propagating the pump field in the fundamental mode......, while generating the second harmonic in one of the modes of the LP11 multiplet. This is shown to work in both circular and microstructured nanowires, although only one of the LP11 modes can be phase-matched in the microstructure. The prospect of obtaining large conversion efficiencies in silica...

  11. 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.

  12. Sensing with multipolar second harmonic generation from spherical metallic nanoparticles.

    Science.gov (United States)

    Butet, Jérémy; Russier-Antoine, Isabelle; Jonin, Christian; Lascoux, Noëlle; Benichou, Emmanuel; Brevet, Pierre-François

    2012-03-14

    We show that sensing in the nonlinear optical regime using multipolar surface plasmon resonances is more sensitive in comparison to sensing in the linear optical regime. Mie theory, and its extension to the second harmonic generation from a metallic nanosphere, is used to describe multipolar second harmonic generation from silver metallic nanoparticles. The standard figure of merit of a potential plasmonic sensor based on this principle is then calculated. We finally demonstrate that such a sensor is more sensitive to optical refraction index changes occurring in the vicinity of the metallic nanoparticle than its linear counterpart. PMID:22375818

  13. Confocal Imaging of Biological Tissues Using Second Harmonic Generation

    International Nuclear Information System (INIS)

    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

  14. Second Harmonic Generation in Deeply Sub-Wavelength Waveguides

    CERN Document Server

    Roppo, V; de Ceglia, D; Scalora, M

    2012-01-01

    We theoretically investigate second harmonic generation in extremely narrow, sub-wavelength semiconductor and dielectric waveguides. We discuss a novel guiding mechanism characterized by the inhibition of diffraction and the suppression of cut-off limits in the context of a light trapping phenomenon that sets in under conditions of general phase and group velocity mismatch between the fundamental and the generated harmonic.

  15. 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.)

  16. Second-harmonic generation using tailored whispering gallery modes

    International Nuclear Information System (INIS)

    It has been shown that whispering gallery modes can be used to obtain a combination of modal and geometrical quasi-phase-matching in second-harmonic generation. This could be achieved in isotropic, nonferroelectric, strongly dispersive and highly nonlinear materials such as III-V semiconductors. Unfortunately the poor overlap between the second-harmonic field and second order nonlinear polarization limits the conversion efficiency. In this paper we show that by engineering the refractive index it is possible to increase field overlap and to enhance effective second order nonlinear polarization of semiconductor microdisks

  17. 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.

  18. 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...

  19. 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.

  20. Surface structure enhanced second harmonic generation in organic nanofibers

    DEFF Research Database (Denmark)

    Fiutowski, Jacek; Maibohm, Christian; Kostiucenko, Oksana; Osadnik, Andreas; Lützen, Arne; Rubahn, Horst-Günter

    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...

  1. Digital Video Disc Recorder Using Second Harmonic Generation Green Laser

    Science.gov (United States)

    Seo, Joong Eon; Park, In Sik; Oh, Young Nam; Lee, Seung Hoon; Seong, Pyong Yong; Jang, Yoon Ki; Shin, Dong Ho

    1993-11-01

    A prototype of a digital video disc recorder (D-VDR) with laser-disc-quality video and compact-disc-quality audio is developed and demonstrated using a second harmonic generation (SHG) green laser, narrow-track magneto-optical disk (MOD), mark edge recording and data compression.

  2. Optimization of second harmonic generation and nonlinear phase shifts in the Cerenkov regime

    NARCIS (Netherlands)

    Krijnen, Gijs J.M.; Torruellas, William; Stegeman, George J.; Hoekstra, Hugo J.W.M.; Lambeck, Paul V.

    1996-01-01

    We present beam propagation method (BPM) studies of second harmonic generation (SHG) and nonlinear phaseshifts by cascading. The studies concentrate on SHG by means of radiation modes; the Cerenkov regime. The presented modeling does take into account both depletion and nonlinear phase shifts of the

  3. 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...

  4. Monitoring microstructural evolution in irradiated steel with second harmonic generation

    International Nuclear Information System (INIS)

    Material damage in structural components is driven by microstructural evolution that occurs at low length scales and begins early in component life. In metals, these microstructural features are known to cause measurable changes in the acoustic nonlinearity parameter. Physically, the interaction of a monochromatic ultrasonic wave with microstructural features such as dislocations, precipitates, and vacancies, generates a second harmonic wave that is proportional to the acoustic nonlinearity parameter. These nonlinear ultrasonic techniques thus have the capability to evaluate initial material damage, particularly before crack initiation and propagation occur. This paper discusses how the nonlinear ultrasonic technique of second harmonic generation can be used as a nondestructive evaluation tool to monitor microstructural changes in steel, focusing on characterizing neutron radiation embrittlement in nuclear reactor pressure vessel steels. Current experimental evidence and analytical models linking microstructural evolution with changes in the acoustic nonlinearity parameter are summarized

  5. Optical second harmonic generation probe of two-dimensional ferroelectricity

    CERN Document Server

    Aktsipetrov, O A; Murzina, T V; Blinov, L M; Fridkin, V M; Palto, S P

    1999-01-01

    Optical second harmonic generation (SHG) is used as a noninvasive probe of two-dimensional (2D) ferroelectricity in Langmuir-Blodgett (LB) films of copolymer vinylidene fluoride with trifluorethylene. The surface 2D ferroelectric-paraelectric phase transition in the topmost layer of LB films and a thickness independent (almost 2D) transition in the bulk of these films are observed in temperature studies of SHG.

  6. The structural origin of second harmonic generation in fascia

    OpenAIRE

    Rivard, Maxime; Laliberté, Mathieu; Bertrand-Grenier, Antony; Harnagea, Catalin; Pfeffer, Christian P.; Vallières, Martin; St-Pierre, Yves; Pignolet, Alain; El Khakani, My Ali; Légaré, François

    2010-01-01

    Fascia tissue is rich in collagen type I proteins and can be imaged by second harmonic generation (SHG) microscopy. While identifying the overall alignment of the collagen fibrils is evident from those images, the tridimensional structural origin for the observation of SHG signal is more complex than it apparently seems. Those images reveal that the noncentrosymmetric (piezoelectric) structures are distributed heterogeneously on spatial dimensions inferior to the resolution provided by the no...

  7. Enhanced second harmonic generation from coupled asymmetric plasmonic metal nanostructures

    Science.gov (United States)

    Yildiz, Bilge Can; Emre Tasgin, Mehmet; Kurtulus Abak, Musa; Coskun, Sahin; Emrah Unalan, Husnu; Bek, Alpan

    2015-12-01

    We experimentally demonstrate that two coupled metal nanostructures (MNSs), a silver nanowire and bipyramid, can produce ∼30 times enhanced second harmonic generation compared to the particles alone. We develop a simple theoretical model, presenting the path interference effects in the nonlinear response of coupled MNSs. We show that the reason for such an enhancement can be the occurrence of a Fano resonance due to the coupling of the converter MNS to the long-lived mode of the attached MNS.

  8. Enhanced second harmonic generation from coupled asymmetric plasmonic metal nanostructures

    International Nuclear Information System (INIS)

    We experimentally demonstrate that two coupled metal nanostructures (MNSs), a silver nanowire and bipyramid, can produce ∼30 times enhanced second harmonic generation compared to the particles alone. We develop a simple theoretical model, presenting the path interference effects in the nonlinear response of coupled MNSs. We show that the reason for such an enhancement can be the occurrence of a Fano resonance due to the coupling of the converter MNS to the long-lived mode of the attached MNS. (paper)

  9. Efficient second harmonic generation in internal asymmetric plasmonic slot waveguide.

    Science.gov (United States)

    Huang, Tianye; Tagne, Patrick Moteng; Fu, Songnian

    2016-05-01

    We theoretically propose an internal asymmetric plasmonic slot waveguide (IAPSW), containing two different materials in the slot region. The IAPSW is used for second harmonic generation (SHG) at a wavelength of 1.55 μm. The required phase matching condition is satisfied between the 0th-order mode at the fundamental frequency and the 1st-order mode at the second harmonic frequency. By choosing appropriate slot geometry and materials, the mode field distribution is engineered to enhance the nonlinear coupling coefficient for SHG. With an 11 μm long IAPSW, a conversion efficiency of 24% (1.8 × 105 W-1cm-2 normalized conversion efficiency) is predicted. Furthermore, the SHG efficiency is more pronounced in IAPSW with thinner slot. PMID:27137584

  10. Second harmonic generation of chemical oxygen-iodine laser

    Science.gov (United States)

    Miura, Noriaki; Mese, Norimichi; Yoshino, Satoru; Uchiyama, Taro

    1993-05-01

    Intracavity second harmonic generation of chemical oxygen iodine laser utilizing LiB3O5 crystal has been studied. A chemical oxygen iodine laser of which the fundamental maximum output power is 3 W in TEM00 mode with the Cl2 flow rate of 300 mmol/min is used. Obtained total second harmonic power is a maximum of about 6 W. Therefore, we could estimate that the effective extraction efficiency is 200%. It is thought that the latter is above 100% due to the condition that the output coupling for the fundamental beam is not optimum. And applying the result of a fundamental laser power measurement, the internal conversion efficiency is estimated at 0.29%.

  11. 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.

  12. 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.

  13. 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.

  14. Second Harmonic Generation Mediated by Aligned Water in Starch Granules.

    Science.gov (United States)

    Cisek, Richard; Tokarz, Danielle; Krouglov, Serguei; Steup, Martin; Emes, Michael J; Tetlow, Ian J; Barzda, Virginijus

    2014-12-26

    The origin of second harmonic generation (SHG) in starch granules was investigated using ab initio quantum mechanical modeling and experimentally examined using polarization-in, polarization-out (PIPO) second harmonic generation microscopy. Ab initio calculations revealed that the largest contribution to the SHG signal from A- and B-type allomorphs of starch originates from the anisotropic organization of hydroxide and hydrogen bonds mediated by aligned water found in the polymers. The hypothesis was experimentally tested by imaging maize starch granules under various hydration and heat treatment conditions that alter the hydrogen bond network. The highest SHG intensity was found in fully hydrated starch granules, and heat treatment diminished the SHG intensity. The PIPO SHG imaging showed that dried starch granules have a much higher nonlinear optical susceptibility component ratio than fully hydrated granules. In contrast, deuterated starch granules showed a smaller susceptibility component ratio demonstrating that SHG is highly sensitive to the organization of the hydroxyl and hydrogen bond network. The polarization SHG imaging results of potato starch granules, representing starch allomorph B, were compared to those of maize starch granules representing allomorph A. The results showed that the amount of aligned water was higher in the maize granules. Nonlinear microscopy of starch granules provides evidence that varying hydration conditions leads to significant changes in the nonlinear susceptibility ratio as well as the SHG intensity, supporting the hypothesis from ab initio calculations that the dominant contribution to SHG is due to the ordered hydroxide and hydrogen bond network. PMID:25427055

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

    Energy Technology Data Exchange (ETDEWEB)

    Davidson, Roderick B.; Ziegler, Jed I.; Vargas, Guillermo; Avanesyan, Sergey M.; Gong, Yu; Hess, Wayne P.; Haglund Jr., Richard F.

    2015-01-21

    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 noncentrosymmetric 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.

  16. Creation and doubling of vortices in intracavity second harmonic generation

    Science.gov (United States)

    Lim, Oo-Kaw; Boland, Brian; Saffman, Mark; Krolikowski, Wieslaw

    2004-05-01

    Optical vortices are topological objects whose transformation properties under propagation in linear and nonlinear optical media have been the subject of much recent interest. In this work we demonstrate generation and frequency doubling of unit charge vortices in a linear astigmatic resonator. By appropriate alignment of a near confocal cavity we couple a fundamental laser beam at 860nm to a vortical resonator mode. With a nonlinear crystal in the resonator a doubly charged vortex at the second harmonic frequency is generated. Topological instability of the double charge harmonic vortices leads to well separated vortex cores that are shown to rotate and become anisotropic, as the resonator is tuned across resonance. A simple theory that accounts for crystal induced astigmatism agrees well with the experimental measurements.

  17. Frequency comb formation in doubly resonant second-harmonic generation

    CERN Document Server

    Leo, F; Ricciardi, I; De Rosa, M; Coen, S; Wabnitz, S; Erkintalo, M

    2016-01-01

    We theoretically study the generation of optical frequency combs and corresponding pulse trains in doubly resonant intracavity second-harmonic generation (SHG). We find that, despite the large temporal walk-off characteristic of realistic cavity systems, the nonlinear dynamics can be accurately and efficiently modelled using a pair of coupled mean-field equations. Through rigorous stability analysis of the system's steady-state continuous wave solutions, we demonstrate that walk-off can give rise to a new, previously unexplored regime of temporal modulation instability (MI). Numerical simulations performed in this regime reveal rich dynamical behaviours, including the emergence of temporal patterns that correspond to coherent optical frequency combs. We also demonstrate that the two coupled equations that govern the doubly resonant cavity behaviour can, under typical conditions, be reduced to a single mean-field equation akin to that describing the dynamics of singly resonant cavity SHG [F. Leo et al., Phys. ...

  18. 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 ...

  19. 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

  20. 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.

  1. 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...

  2. Second Harmonic Generation in a Graphe Armchair Nanoribbon

    Science.gov (United States)

    Gumbs, Godfrey; Abranyos, Yonatan

    2013-03-01

    The second order nonlinear optical susceptibility χ (2) for second harmonic generation is calculated for the 11H transition of a graded double quantum well (DQW) structure of undoped- GaAs / Alx Ga1 - x As . These results are compared with the single quantum well (QW). Our results show that the values of χ (2) have optimal magnitudes dependent on the width, depth and separation between the QWs in a DQW structure. When the electric field increases, the dipole moment increases due to the increasing separation between the electron and hole wave functions. On the other hand, the oscillator strength of the 11H transition is reduced as a result of the decrease in the overlap of the electron and hole envelope functions. These two competing factors give rise to optimal conditions for the enhancement of the second order nonlinear susceptibility χ (2). It is demonstrated that χ (2) for the DQW structure is more enhanced than for the biased single QW.

  3. Relativistic plasma surfaces as an efficient second harmonic generator

    International Nuclear Information System (INIS)

    We report on the characterization of the specular reflection of 50 fs laser pulses in the intensity range 1017-1021 W cm-2 obliquely incident with p-polarization onto solid density plasmas. These measurements show that the absorbed energy fraction remains approximately constant and that second harmonic generation (SHG) achieves efficiencies of 22±8% for intensities approaching 1021 W cm-2. A simple model based on the relativistic oscillating mirror concept reproduces the observed intensity scaling, indicating that this is the dominant process involved for these conditions. This method may prove to be superior to SHG by sum frequency mixing in crystals as it is free from dispersion and retains high spatial coherence at high intensity.

  4. Balanced homodyne detection in second-harmonic generation microscopy

    CERN Document Server

    Le Xuan, L; Brasselet, S; Perruchas, S; Tard, C; Gacoin, T; Xuan, Loc Le; Chauvat, Dominique; Brasselet, Sophie; Perruchas, Sandrine; Gacoin, Thierry

    2006-01-01

    We demonstrate the association of two-photon nonlinear microscopy with balanced homodyne detection for investigating second harmonic radiation properties at nanoscale dimensions. Variation of the relative phase between second-harmonic and fundamental beams is retrieved, as a function of the absolute orientation of the nonlinear emitters. Sensitivity down to approximately 3.2 photon/s in the spatio-temporal mode of the local oscillator is obtained. This value is high enough to efficiently detect the coherent second-harmonic emission from a single KTiOPO4 crystal of sub-wavelength size.

  5. Large second-harmonic generation in thermally poled silica waveguides

    DEFF Research Database (Denmark)

    Arentoft, Jesper; Kristensen, Martin; Pedersen, K.;

    2001-01-01

    We report the observation of very large second-harmonic signals from thermally poled silica waveguide samples. Secondary ion mass spectrometry measurements show that significant amounts of silver ions are injected from the top electrode during poling.......We report the observation of very large second-harmonic signals from thermally poled silica waveguide samples. Secondary ion mass spectrometry measurements show that significant amounts of silver ions are injected from the top electrode during poling....

  6. 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...

  7. Second-harmonic generation in substoichiometric silicon nitride layers

    Science.gov (United States)

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

    2013-03-01

    Harmonic generation in optical circuits offers the possibility to integrate wavelength converters, light amplifiers, lasers, and multiple optical signal processing devices with electronic components. Bulk silicon has a negligible second-order nonlinear optical susceptibility owing to its crystal centrosymmetry. Silicon nitride has its place in the microelectronic industry as an insulator and chemical barrier. In this work, we propose to take advantage of silicon excess in silicon nitride to increase the Second Harmonic Generation (SHG) efficiency. Thin films have been grown by reactive magnetron sputtering and their nonlinear optical properties have been studied by femtosecond pumping over a wide range of excitation wavelengths, silicon nitride stoichiometry and thermal processes. We demonstrate SHG in the visible range (375 - 450 nm) using a tunable 150 fs Ti:sapphire laser, and we optimize the SH emission at a silicon excess of 46 at.% demonstrating a maximum SHG efficiency of 4x10-6 in optimized films. Polarization properties, generation efficiency, and the second order nonlinear optical susceptibility are measured for all the investigated samples and discussed in terms of an effective theoretical model. Our findings show that the large nonlinear optical response demonstrated in optimized Si-rich silicon nitride materials can be utilized for the engineering of nonlinear optical functions and devices on a Si chip.

  8. New Molecular Ferroelectrics Accompanied by Ultrahigh Second-Harmonic Generation.

    Science.gov (United States)

    Liu, Chuang; Gao, Kaige; Cui, Zepeng; Gao, Linsong; Fu, Da-Wei; Cai, Hong-Ling; Wu, X S

    2016-05-19

    Second-harmonic generation (SHG) is one of the outstanding properties for practical applications. However, the great majority of molecular ferroelectric materials have very low nonlinear optical coefficients, attenuating their attractive performance. Here we synthesized (4-amino-2-bromopyridinium)(4-amino-2-bromopyridine)tetrafluoroborate (1), whose second-order nonlinear optical coefficient reaches up to 2.56 pm V(-1), 2.67 times of that of KDP, and (4-amino-2-bromopyridinium)tetrafluoroborate (2), possessing a more incredible large second-order nonlinear optical coefficient as high as 10.24 pm V(-1), 10.67 times that of KDP. The compound 1 undergoes two reversible phase transitions at around T1 = 244.1 K and T2 = 154.6 K, caused by dramatic changes of the protonated cations and order-disorder of anions, which was disclosed by differential scanning calorimetry, heat capacity, dielectric anomalies, SHG, and single-crystal X-ray diffraction analysis. The pyroelectric measurements reveal that compound 1 is a Rochelle salt type ferroelectric, which has a large spontaneous polarization of about 3 μC/cm(2). PMID:27111056

  9. Nonlinear self-phase matching of optical second harmonic generation in lithium niobate

    OpenAIRE

    Orlov, Sergei; Yariv, Amnon; Segev, Mordechai

    1996-01-01

    We show that the nonlinear index perturbation due to light-induced photovoltaic space-charge field in LiNbO3 can give rise to self-phase matching of second harmonic generation. Increase of the conversion efficiency is accompanied by formation of stationary and nonstationary patterns in the spatial structure of the generated second harmonic. The space-charge field can be induced either by the initially non-phase-matched second harmonic or by an external seed.

  10. Defects and strain enhancements of second-harmonic generation in Si/Ge superlattices

    Science.gov (United States)

    Bertocchi, Matteo; Luppi, Eleonora; Degoli, Elena; Véniard, Valérie; Ossicini, Stefano

    2014-06-01

    Starting from experimental findings and interface growth problems in Si/Ge superlattices, we have investigated through ab initio methods the concurrent and competitive behavior of strain and defects in the second-harmonic generation process. Interpreting the second-harmonic intensities as a function of the different nature and percentage of defects together with the strain induced at the interface between Si and Ge, we found a way to tune and enhance the second-harmonic generation response of these systems.

  11. Transmission second harmonic generation in CdTe at 1.064 μm

    Science.gov (United States)

    Petrovic, M. S.; Suchocki, A.; Powell, R. C.; Cantwell, G.

    1991-12-01

    Transmission geometry measurements of the efficiency of second harmonic generation in various thicknesses of CdTe samples were made to determine the conversion efficiency dependence on material thickness. Neglecting pump depletion, it is found that for samples of well-defined symmetry, the second harmonic conversion efficiency scales with film thickness, with no observed enhancement owing to coherence length effects. The angular dependence of the observed second harmonic light in films of well-defined symmetry is consistent with second harmonic generation originating in the bulk.

  12. Phase matching in second-harmonic generation using artificial periodic structures.

    Science.gov (United States)

    Tang, C. L.; Bey, P. P.

    1973-01-01

    The use of artificial periodic structures, consisting of spatial modulations of the linear and nonlinear susceptibilities of a nonlinear optical medium, to achieve phase matching in second-harmonic generation is analyzed. Dispersion relations and approximate formulas for the second-harmonic fields generated under various conditions are obtained and used to evaluate the experimental situation.

  13. Vector treatment of second-harmonic generation produced by tightly focused vignetted Gaussian beams

    Science.gov (United States)

    Asatryan, Ara A.; Sheppard, Colin J. R.; de Sterke, C. Martijn

    2004-12-01

    We present a fast and accurate method to calculate the vector-field distribution of a focused Gaussian beam. This method is applied to calculate the second harmonic that is generated by such a beam from a sample in the undepleted pump approximation. These calculations can be used to model second-harmonic imaging in an optical microscope with a wide aperture.

  14. Second harmonic generation and two-photon luminescence from colloidal gold nanoparticles

    Science.gov (United States)

    Yashunin, D. A.; Korytin, A. I.; Smirnov, A. I.; Stepanov, A. N.

    2016-03-01

    Second harmonic generation and two-photon luminescence from colloidal gold nanoparticles in the 980-1300 nm wavelength range of exciting femtosecond radiation were investigated experimentally. The measured polarization and spectral characteristics of the second harmonic and two-photon luminescence demonstrate that the observed nonlinear optical signal is determined by the dimers constituting several percent of the total nanoparticle number.

  15. Cascaded second-harmonic generation, summation of the wave vectors of the bulk defect-deformation waves, and generation of multimode micro- and nanostructures by laser irradiation of solids

    International Nuclear Information System (INIS)

    We consider for the first time three-wave interactions of bulk quasi-static defect-deformation (DD) waves (generation of the second DD harmonic and summation of the wave vectors), similar to three-wave interactions in nonlinear optics and acoustics, leading to cascaded broadening of the spectrum of spatial DD harmonics. Based on the theory developed, we interpret the recently observed effect of laser-induced generation of the bulk periodic structure of silver nanoparticles with a discrete spatial spectrum, extending from micro- to nanometres. (nonlinear optical phenomena)

  16. Cascaded second-harmonic generation, summation of the wave vectors of the bulk defect-deformation waves, and generation of multimode micro- and nanostructures by laser irradiation of solids

    Science.gov (United States)

    Emel'yanov, Vladimir I.

    2011-02-01

    We consider for the first time three-wave interactions of bulk quasi-static defect-deformation (DD) waves (generation of the second DD harmonic and summation of the wave vectors), similar to three-wave interactions in nonlinear optics and acoustics, leading to cascaded broadening of the spectrum of spatial DD harmonics. Based on the theory developed, we interpret the recently observed effect of laser-induced generation of the bulk periodic structure of silver nanoparticles with a discrete spatial spectrum, extending from micro- to nanometres.

  17. A novel method for detecting second harmonic ultrasonic components generated from fastened bolts

    Science.gov (United States)

    Fukuda, Makoto; Imano, Kazuhiko

    2012-09-01

    This study examines the use of ultrasonic second harmonic components in the quality control of bolt-fastened structures. An improved method for detecting the second harmonic components, from a bolt fastened with a nut, using the transmission method is constructed. A hexagon head iron bolt (12-mm diameter and 25-mm long) was used in the experiments. The bolt was fastened using a digital torque wrench. The second harmonic component increased by approximately 20 dB before and after the bolt was fastened. The sources of second harmonic components were contact acoustic nonlinearity in the screw thread interfaces of the bolt-nut and were the plastic deformation in the bolt with fastening bolt. This result was improved by approximately 10 dB compared with previous our method. Consequently, usefulness of the novel method for detecting second harmonic ultrasonic components generated from fastened bolt was confirmed.

  18. Second harmonic generation in ZnO thin films fabricated by metalorganic chemical vapor deposition

    Science.gov (United States)

    Liu, C. Y.; Zhang, B. P.; Binh, N. T.; Segawa, Y.

    2004-07-01

    Second harmonic generation (SHG) from ZnO thin films fabricated by metalorganic chemical vapor deposition (MOCVD) technique was carried out. By comparing the second harmonic signal generated in a series of ZnO films with different deposition temperatures, we conclude that a significant part of second harmonic signal is generated at the film deposited with appropriate temperature. The second-order susceptibility tensor χ(2)zzz=9.2 pm/V was deduced for a film deposited at 250 °C.

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

    Science.gov (United States)

    Saravi, Sina; Quintero-Bermudez, Rafael; Setzpfandt, Frank; Asger Mortensen, N; Pertsch, Thomas

    2016-07-01

    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 maximally achievable efficiency reached for finite values of the group index at the point of phase-matching. Furthermore, we identify situations for which slow light, surprisingly, does not enhance the second-harmonic generation efficiency. Our results are corroborated by rigorous nonlinear simulations of second-harmonic generation in periodic nanobeam waveguides with loss. PMID:27367114

  20. 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.

  1. 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.

  2. 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. PMID:19838261

  3. Enhanced Transmission and Second Harmonic Generation from Subwavelength Slits on Metal Substrates

    CERN Document Server

    Vincenti, M A; Petruzzelli, V; D'Orazio, A; Prudenzano, F; De Ceglia, D; Akozbekb, N; Bloemerb, M J; Ashley, P; Scalora, M

    2008-01-01

    We theoretically investigate second harmonic generation that originates from the nonlinear, magnetic Lorentz force term from single and multiple apertures carved on thick, opaque metal substrates. The linear transmission properties of apertures on metal substrates have been previously studied in the context of the extraordinary transmission of light. The transmission process is driven by a number of physical mechanisms, whose characteristics and relative importance depend on the thickness of the metallic substrate, slit size, and slit separation. In this work we show that a combination of cavity effects and surface plasmon generation gives rise to enhanced second harmonic generation in the regime of extraordinary transmittance of the pump field. We have studied both forward and backward second harmonic generation conversion efficiencies as functions of the geometrical parameters, and how they relate to pump transmission efficiency. The resonance phenomenon is evident in the generated second harmonic signal, a...

  4. Tunable Second Harmonic Generation with High Conversion Efficiency in Periodically Poled Lithium Niobate Channel Waveguide

    Institute of Scientific and Technical Information of China (English)

    XU Rong-hui; CHEN Xian-feng; CHEN Yu-ping; YE Zhi-qing; XIA Yu-xing

    2007-01-01

    The experiment on quasi-phase-matched second harmonic generation (SHG) in a channel waveguide was reported.The waveguide was made by annealed proton exchange in the periodically poled lithium niobate (PPLN) with the period of PPLN of 14.9 μm, which was designed for cascading wavelength conversion in dense wavelength division multiplexer optical communications.The measurement results of SHG conversion efficiency as a function of fundamental wavelength at room temperature fit well to sinc2 shape.The peak of SHG conversion efficiency was 75% · W-1 · cm-2 as well as reported. The relationship between the center fundamental wavelength and tempera ture shows that SHG can be effectively tuned by the temperature in PPLN waveguide.

  5. Calculation of second-harmonic wave pattern generated by focused cylindrical vector beams

    Science.gov (United States)

    Ohtsu, A.; Kozawa, Y.; Sato, S.

    2010-03-01

    We calculated the second-harmonic wave pattern induced by focused cylindrically symmetric, polarized vector beams. The second-order nonlinear polarization was expressed for fundamental electric field components passed through a dielectric interface based on vector diffraction theory. Furthermore, the second-harmonic wave pattern was represented on the basis of the far-field approximate expression derived from the formulation of higher-order harmonic generation including a Green's function. For a (110) zinc selenide crystal, the calculated forward emission patterns of the second-harmonic wave were eight-figure shaped as observed in experiment.

  6. Second harmonic generation in anisotropic Langmuir-Blodgett films of N-docosyl-4-nitroaniline

    DEFF Research Database (Denmark)

    Geisler, T.; Rosenkilde, S.; Ramanujam, P.S.;

    1992-01-01

    Langmuir-Blodgett (LB) films of N-docosyl-4-nitroaniline have been made and their nonlinear optical properties studied by second harmonic generation (SHG) measurements. A significant enhancement of the intensity of the second harmonic of the 1.064-mu-m YAG was observed when a two layer Y-type film...... rather than a monolayer was used. Also, the dependence of the second harmonic signal on the polarization of the fundamental beam suggests that the nonlinear chromophores are lying nearly flat with respect to the substrate and are oriented along the dipping direction resulting in a noncentrosymmetric...

  7. NONLINEAR OPTICS PHENOMENA: Second harmonic generation from DF laser radiation in ZnGeP2

    Science.gov (United States)

    Andreev, Yu M.; Velikanov, S. D.; Yerutin, A. S.; Zapol'skiĭ, A. F.; Konkin, D. V.; Mishkin, S. N.; Smirnov, S. V.; Frolov, Yu N.; Shchurov, V. V.

    1992-11-01

    We have succeeded in generating the second harmonic of the radiation from a DF laser for the first time, using single crystals of ZnGeP2. For crystals with lengths of 10.1 and 13.6 mm, the overall external efficiencies of the entire oscillator system were 4 and 6.2%. The internal efficiencies of second-harmonic generation in the crystals were 7.6 and 11.8%, respectively.

  8. Second harmonic generation of a short laser pulse in a cold magnetized plasma

    International Nuclear Information System (INIS)

    In this paper we analyzed the Second Harmonic Generation of a short laser pulse, that linearly polarized, in a cold magnetized plasma by considering that the magnitude of magnetic field is constant. First the components of electric field and the pointing vector are obtained for the first and second harmonic generation, by using the second order perturbation theory. Finally we study the variations of pointing vector with respect to the angular of magnetic field of plasma.

  9. Nonlinear Fano Profiles in the Optical Second-Harmonic Generation from Silver Nanoparticles

    CERN Document Server

    Butet, J; Russier-Antoine, I; Bertorelle, F; Mosset, A; Lascoux, N; Jonin, C; Benichou, E; Brevet, P -F

    2012-01-01

    The resonance effects on the optical second harmonic generation from 140 nm silver nanoparticles is studied experimentally by hyper-Rayleigh scattering and numerically by finite element method calculations. We find that the interferences between the broad dipolar and narrow octupolar surface plasmon resonances leads to nonlinear Fano profiles that can be externally controlled by the incident polarization angle. These profiles are responsible for the nonlinear plasmon-induced transparency in the second harmonic generation.

  10. High Absorption and Second-Harmonic Generation in Split Ring Resonator Multilayer Nanostructure

    OpenAIRE

    Renlong Zhou; Mengxiong Wu; Hui Deng; Qiong Liu; Suxia Xie; Lingxi Wu; Guozheng Nie; Jie Zhan

    2014-01-01

    Second-harmonic generation in split ring resonator multilayer nanostructure is studied with the finite-difference time-domain (FDTD) method. The fundamental frequency wave and the second-harmonic generation at the resonant absorption wavelength are highly localized in the dielectric layer, and the absorption peak is sensitive to dielectric constant of the dielectric layer. Under the excitation of the plasmon resonances mode, the strong local field induces an expected increase of the second-ha...

  11. Pulse shaping via forward second harmonic generation in nonlinear photonic crystals

    International Nuclear Information System (INIS)

    We have theoretically designed a method for obtaining short laser pulses by second harmonic generation in periodically and aperiodically poled quadratic nonlinear photonic crystals. An efficient algorithm is developed to construct quasi-phase matching gratings which allow one to shape the required amplitude and phase of second-harmonic pulses considering energy exchange. Developed method could be applied for designing of nonlinear photonic crystals. (authors)

  12. Intracavity second harmonic generation of chemical oxygen iodine laser with a Brewster cut LBO crystal

    Science.gov (United States)

    Shimizu, Tomohiro; Tezuka, Takeo; Chen, Kuntetsu; Hashimoto, Katsuki; Uchiyama, Taro

    1997-04-01

    Second harmonic generation of chemical oxygen iodine laser was investigated with a Brewster cut LBO crystal. By utilizing a Brewster cut LBO crystal the loss in the resonator can be suppressed. Further, by reducing crystal absorption, the crystal can't be heated and go off phase match or even crack due to thermal stress. We could obtain 16.4 W of second harmonic power and keep out the crystal from being destroyed by the damage of thermal stress.

  13. 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. PMID:19365469

  14. 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. PMID:20420409

  15. Vector model for polarized second-harmonic generation microscopy under high numerical aperture

    Science.gov (United States)

    Wang, Xiang-Hui; Chang, Sheng-Jiang; Lin, Lie; Wang, Lin-Rui; Huo, Bing-Zhong; Hao, Shu-Jian

    2010-04-01

    Based on the vector diffraction theory and the generalized Jones matrix formalism, a vector model for polarized second-harmonic generation (SHG) microscopy is developed, which includes the roles of the axial component Pz, the weight factor and the cross-effect between the lateral components. The numerical results show that as the relative magnitude of Pz increases, the polarization response of the second-harmonic signal will vary from linear polarization to elliptical polarization and the polarization orientation of the second-harmonic signal is different from that under the paraxial approximation. In addition, it is interesting that the polarization response of the detected second-harmonic signal can change with the value of the collimator lens NA. Therefore, it is more advantageous to adopt the vector model to investigate the property of polarized SHG microscopy for a variety of cases.

  16. Vector model for polarized second-harmonic generation microscopy under high numerical aperture

    International Nuclear Information System (INIS)

    Based on the vector diffraction theory and the generalized Jones matrix formalism, a vector model for polarized second-harmonic generation (SHG) microscopy is developed, which includes the roles of the axial component Pz, the weight factor and the cross-effect between the lateral components. The numerical results show that as the relative magnitude of Pz increases, the polarization response of the second-harmonic signal will vary from linear polarization to elliptical polarization and the polarization orientation of the second-harmonic signal is different from that under the paraxial approximation. In addition, it is interesting that the polarization response of the detected second-harmonic signal can change with the value of the collimator lens NA. Therefore, it is more advantageous to adopt the vector model to investigate the property of polarized SHG microscopy for a variety of cases

  17. 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 frequency......, perfect. Under slight modifications of the operational conditions, the system is shown to produce efficient bright, squeezed light. Furthermore, we investigate the degree of polarization squeezing and find that three Stokes parameters can be squeezed simultaneously. Finally, we gauge the process for...

  18. Second-harmonic generation in mixed stilbazium salt/arachidic acid Langmuir-Blodgett films

    Science.gov (United States)

    Liu, Liying; Zheng, Jiabiao; Wang, Wencheng; Zhang, Zhiming; Tao, Fenggang; Xu, Linxiao; Hu, Jiacong

    1992-10-01

    A stilbazium salt was synthesized and its second-order molecular polarizability was deduced to be 1.2×10 -27 esu. Measurements of second-harmonic generation and small-angle X-ray diffraction on Langmuir-Blodgett films of the stilbazium salt/arachide acid mixtures showed that the mixed compounds with molar ratios of 1:2 and 1:5 could form multilayers with large second- order optical nonlinearity. Second harmonic generation study on the alternate multilayers of stilbazium salt/arachide acid and arachidic acid showed that the second-harmonic signals were increasing monotonously up to 80 bilayers, but the increment was lower than the value predicted theoretically by the quadratic law. Possible reasons are discussed.

  19. Structural light focusing phenomenon and enhanced second harmonic generation in NaNO2-infiltrated opal photonic crystal

    International Nuclear Information System (INIS)

    We report new experimental results on enhanced second harmonic generation using a structural light focusing phenomenon in photonic crystals (PCs). We use opal-based PC, infiltrated with NaNO2 and pumped with femtosecond laser pulses at various incidence angles, in order to examine the dependence of second harmonic generation efficiency on the pumping wavelength location toward the PC band-gap. We demonstrate one order enhancement of second harmonic generation in case of PC band-gap pumping in comparison to non-band- gap pumping. Second harmonic generation is performed in reflection mode with the maximum of generation in the direction of mirror reflection. We demonstrate that the spectrum of second harmonic does not narrow with the quasi-phase matching condition in case of band-gap generation, and second harmonic spectrum corresponding to non-band-gap generation undergoes 1.5 times narrowing due to the quasi-phase matching

  20. Four-pass quadrature arrangement for highly efficient second-harmonic generation

    International Nuclear Information System (INIS)

    A four-pass quadrature arrangement was developed to generate green output with high efficiency for pumping an ultrashort pulse laser system. With this scheme, an efficiency from fundamental energy into total second harmonic energy in excess of 80% was achieved for frequency doubling of 1064-nm in KTP with a low input fundamental laser intensity of 76 MW/cm2. A total second-harmonic output of 486 mJ was obtained with 607 mJ of the input 1064-nm fundamental laser at 10 Hz. (author)

  1. Ultrashort pulse chirp measurement via transverse second-harmonic generation in strontium barium niobate crystal

    International Nuclear Information System (INIS)

    Pulse compression in dispersive strontium barium niobate crystal with a random size and distribution of the anti-parallel orientated nonlinear domains is observed via transverse second harmonic generation. The dependence of the transverse width of the second harmonic trace along the propagation direction allows for the determination of the initial chirp and duration of pulses in the femtosecond regime. This technique permits a real-time analysis of the pulse evolution and facilitates fast in-situ correction of pulse chirp acquired in the propagation through an optical system

  2. Ultrashort pulse chirp measurement via transverse second-harmonic generation in strontium barium niobate crystal

    Energy Technology Data Exchange (ETDEWEB)

    Trull, J.; Wang, B.; Parra, A.; Vilaseca, R.; Cojocaru, C. [Departament de Física i Enginyeria Nuclear, Universitat Politècnica Catalunya, Terrassa 08222 (Spain); Sola, I. [Grupo de Investigación en Óptica Extrema (GIOE), Departamento de Física Aplicada, Universidad de Salamanca, Plaza de la Merced s/n, 37008 Salamanca (Spain); Krolikowski, W. [Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia); Science Program, Texas A and M University at Qatar, Doha (Qatar); Sheng, Y. [Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia)

    2015-06-01

    Pulse compression in dispersive strontium barium niobate crystal with a random size and distribution of the anti-parallel orientated nonlinear domains is observed via transverse second harmonic generation. The dependence of the transverse width of the second harmonic trace along the propagation direction allows for the determination of the initial chirp and duration of pulses in the femtosecond regime. This technique permits a real-time analysis of the pulse evolution and facilitates fast in-situ correction of pulse chirp acquired in the propagation through an optical system.

  3. Second-harmonic generation imaging of metal nano-objects with cylindrical vector beams.

    Science.gov (United States)

    Bautista, Godofredo; Huttunen, Mikko J; Mäkitalo, Jouni; Kontio, Juha M; Simonen, Janne; Kauranen, Martti

    2012-06-13

    We introduce an imaging technique based on second-harmonic generation with cylindrical vector beams that is extremely sensitive to three-dimensional orientation and nanoscale morphology of metal nano-objects. Our experiments and second-harmonic field calculations based on frequency-domain boundary element method are in very good agreement. The technique provides contrast for structural features that cannot be resolved by linear techniques or conventional states of polarization and shows great potential for simple and cost-effective far-field optical imaging in plasmonics. PMID:22587307

  4. Four-pass quadrature arrangement for highly efficient second-harmonic generation

    Energy Technology Data Exchange (ETDEWEB)

    Kiriyama, Hiromitsu; Arisawa, Takashi [Japan Atomic Energy Research Institute, Kansai Research Establishment, Kizu, Kyoto (Japan); Matsuoka, Shinichi [Hamamatsu Photonics K.K., Shizuoka (Japan)

    2001-05-01

    A four-pass quadrature arrangement was developed to generate green output with high efficiency for pumping an ultrashort pulse laser system. With this scheme, an efficiency from fundamental energy into total second harmonic energy in excess of 80% was achieved for frequency doubling of 1064-nm in KTP with a low input fundamental laser intensity of 76 MW/cm{sup 2}. A total second-harmonic output of 486 mJ was obtained with 607 mJ of the input 1064-nm fundamental laser at 10 Hz. (author)

  5. Theory of generation of second harmonics of nonlinear photoacoustic signal of two-layer semitransparent samples

    International Nuclear Information System (INIS)

    The theory of generation of second harmonics of nonlinear photoacoustic signal of two-layer semitransparent solid samples is presented in this work. The general expression for acoustic pressure fluctuation in gaseous medium is defined. The expressions for the amplitude and phase of the signal and the dependence of these values on frequency modulation of incident laser beam are found.

  6. Two-pass-internal second-harmonic generation using a prism coupler.

    Science.gov (United States)

    Gonzalez, D. G.; Nieh, S. T. K.; Steier, W. H.

    1973-01-01

    A dispersive quartz prism is used to couple the total second harmonic generated in both directions by an internal cavity frequency doubler. The study shows that the dispersion of air and mirror reflection phase shifts can be compensated for by a slight nonphase match condition in the doubler.

  7. Second harmonic generation and pulse shaping in positively and negatively spatially dispersive nanowaveguides: comparative analysis

    CERN Document Server

    Popov, Alexander K

    2015-01-01

    Comparative analysis of second harmonic generation in ordinary and backward-wave settings is presented. Extraordinary properties of frequency doubling nonlinear optical reflectivity and pulse shaping through phase matching of ordinary and backward electromagnetic waves in the nanowaveguides with mixed negative/positive spatial dispersion is demonstrated with numerical simulations.

  8. Second Harmonic Generation in CdTe Plate by Free Electron Laser

    Science.gov (United States)

    Yamauchi, Toshihiko; Kikuzawa, Nobuhiro; Minehara, Eisuke; Nagai, Ryoji; Nishimori, Nobuyuki; Sawamura, Masaru; Hajima, Ryoichi; Shizuma, Toshiyuki; Hayakawa, Takehito

    2000-10-01

    The second harmonic generation (SHG) signal converted from the 22 μm input wavelength of free electron laser (FEL) is observed using a non-birefringent CdTe crystal. The conversion efficiency of SHG is experimentally obtained to be ˜3× 10-5%/(MWcm-2).

  9. Second harmonic generation in CdTe plate by free electron laser

    Energy Technology Data Exchange (ETDEWEB)

    Yamauchi, Toshihiko; Kikuzawa, Nobuhiro; Minehara, Eisuke; Nagai, Ryoji; Nishimori, Nobuyuki; Sawamura, Masaru; Hajima, Ryoichi; Shizuma, Toshiyuki; Hayakawa, Takehito [Division of Advanced Photon Research, Japan Atomic Energy Research Institute, Tokai, Ibaraki (Japan)

    2000-10-01

    The second harmonic generation (SHG) signal converted from the 22 {mu}m input wavelength of free electron laser (FEL) is observed using a non-birefringent CdTe crystal. The conversion efficiency of SHG is experimentally obtained to be {approx}3 x 10{sup -5}% (MWcm{sup -2}). (author)

  10. Evidence of multipolar response of Bacteriorhodopsin by noncollinear second harmonic generation.

    Science.gov (United States)

    Bovino, F A; Larciprete, M C; Sibilia, C; Váró, G; Gergely, C

    2012-06-18

    Noncollinear second harmonic generation from a Bacteriorhodopsin (BR) oriented multilayer film was systematically investigated by varying the polarization state of both fundamental beams. Both experimental results and theoretical simulations, show that the resulting polarization mapping is an useful tool to put in evidence the optical chirality of the investigated film as well as the corresponding multipolar contributions to the nonlinear. PMID:22714524

  11. Measurement of the vector character of electric fields by optical second-harmonic generation.

    Science.gov (United States)

    Dadap, J I; Shan, J; Weling, A S; Misewich, J A; Nahata, A; Heinz, T F

    1999-08-01

    We present a scheme for the determination of the vector nature of an electric field by optical second-harmonic generation. We demonstrate the technique by mapping the two-dimensional electric-field vector of a biased transmission line structure on silicon with a spatial resolution of ~10mum . PMID:18073940

  12. Second harmonic generation by self-focusing of intense hollow Gaussian laser beam in collisionless plasma

    International Nuclear Information System (INIS)

    The effect of self focused hollow Gaussian laser beam (HGLB) (carrying null intensity in center) on the excitation of electron plasma wave (EPW) and second harmonic generation (SHG) has been investigated in collisionless plasma, where relativistic-ponderomotive and only relativistic nonlinearities are operative. The relativistic change of electron mass and the modification of the background electron density due to ponderomotive nonlinearity lead to self-focusing of HGLB in plasma. Paraxial ray theory has been used to derive coupled equations for the self focusing of HGLB in plasma, generation of EPW, and second harmonic. These coupled equations are solved analytically and numerically to study the laser intensity in the plasma, electric field associated with the excited EPW, and the power of SHG. Second harmonic emission is generated due to nonlinear coupling between incident HGLB and EPW satisfying the proper phase matching conditions. The results show that the effect of including the ponderomotive nonlinearity is significant on the generation of EPW and second harmonic. The electric field associated with EPW and the power of SHG are found to be highly sensitive to the order of the hollow Gaussian beam

  13. 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. PMID:25895003

  14. Multimodal two-photon imaging using a second harmonic generation-specific dye

    OpenAIRE

    Nuriya, Mutsuo; FUKUSHIMA, Shun; Momotake, Atsuya; Shinotsuka, Takanori; Yasui, Masato; Arai, Tatsuo

    2016-01-01

    Second harmonic generation (SHG) imaging can be used to visualize unique biological phenomena, but currently available dyes limit its application owing to the strong fluorescent signals that they generate together with SHG. Here we report the first non-fluorescent and membrane potential-sensitive SHG-active organic dye Ap3. Ap3 is photostable and generates SH signals at the plasma membrane with virtually no fluorescent signals, in sharp contrast to the previously used fluorescent dye FM4-64. ...

  15. 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.

  16. Efficient second harmonic generation in a metamaterial with two resonant modes coupled through two varactor diodes

    OpenAIRE

    Nakanishi, Toshihiro; Tamayama, Yasuhiro; Kitano, Masao

    2012-01-01

    We present an effective method to generate second harmonic (SH) waves using nonlinear metamaterial composed of coupled split ring resonators (CSRRs) with varactor (variable capacitance) diodes. The CSRR structure has two resonant modes: a symmetric mode that resonates at the fundamental frequency and an anti-symmetric mode that resonates at the SH frequency. Resonant fundamental waves in the symmetric mode generate resonant SH waves in the anti-symmetric mode. The double resonance contributes...

  17. Resonant second harmonic generation in a gallium nitride two-dimensional photonic crystal on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Y.; Roland, I.; Checoury, X.; Han, Z.; El Kurdi, M.; Sauvage, S.; Boucaud, P., E-mail: philippe.boucaud@ief.u-psud.fr [Institut d' Electronique Fondamentale, CNRS - Univ. Paris Sud 11, Bâtiment 220, F-91405 Orsay (France); Gayral, B. [Univ. Grenoble Alpes, INAC-SP2M, CEA-CNRS group Nanophysique et Semiconducteurs, F-38000 Grenoble (France); CEA, INAC-SP2M, CEA-CNRS group Nanophysique et Semiconducteurs, F-38000 Grenoble (France); Brimont, C.; Guillet, T. [Université Montpellier 2, Laboratoire Charles Coulomb UMR 5221, F-34905 Montpellier (France); Mexis, M.; Semond, F. [CRHEA-CNRS, Rue Bernard Grégory, F-06560 Valbonne (France)

    2015-02-23

    We demonstrate second harmonic generation in a gallium nitride photonic crystal cavity embedded in a two-dimensional free-standing photonic crystal platform on silicon. The photonic crystal nanocavity is optically pumped with a continuous-wave laser at telecom wavelengths in the transparency window of the nitride material. The harmonic generation is evidenced by the spectral range of the emitted signal, the quadratic power dependence vs. input power, and the spectral dependence of second harmonic signal. The harmonic emission pattern is correlated to the harmonic polarization generated by the second-order nonlinear susceptibilities χ{sub zxx}{sup (2)}, χ{sub zyy}{sup (2)} and the electric fields of the fundamental cavity mode.

  18. Resonant second harmonic generation in a gallium nitride two-dimensional photonic crystal on silicon

    International Nuclear Information System (INIS)

    We demonstrate second harmonic generation in a gallium nitride photonic crystal cavity embedded in a two-dimensional free-standing photonic crystal platform on silicon. The photonic crystal nanocavity is optically pumped with a continuous-wave laser at telecom wavelengths in the transparency window of the nitride material. The harmonic generation is evidenced by the spectral range of the emitted signal, the quadratic power dependence vs. input power, and the spectral dependence of second harmonic signal. The harmonic emission pattern is correlated to the harmonic polarization generated by the second-order nonlinear susceptibilities χzxx(2), χzyy(2) and the electric fields of the fundamental cavity mode

  19. Second harmonic generation by propagation of a p-polarized obliquely incident laser beam in underdense plasma

    International Nuclear Information System (INIS)

    An analytical study of second harmonic generation due to interaction an intense, p-polarized laser beam propagating obliquely in homogeneous underdense plasma, in the mildly relativistic regime, has been presented. The efficiency of the second harmonic radiation as well as its detuning length has been obtained and their variation with the angle of incidence is analyzed. It is shown that, for a given plasma electron density, the second harmonic efficiency increases with the angle of incidence while the detuning length decreases. The second harmonic amplitude vanishes at normal incidence of the laser beam

  20. Properties of periodic multicrystal configurations in walk-off-compensating second harmonic generation of ultrashort pulses

    Institute of Scientific and Technical Information of China (English)

    Huang Jin-Zhe; Zhang Liu-Yang; Shen Tao

    2011-01-01

    This work designs a four-platelet periodic multicrystal configuration in the second harmonic generation of ultrashort pulses as a new walk-off-compensating device. It theoretically investigates a proposed active and a typical passive compensating scheme with the undepleted-pump approximation. The result shows that the angular and spectral bandwidths are proportional to the number of crystal pairs as expected, but the temperature tunability is basically unaltered owing to inter-plate pulse interference. At the same time, an analysis reveals that a misuse of the phase mismatch factor is responsible for a historic controversy about pulse interference. A real design of an ultraviolet second harmonic generation(262.5 nm)is considered in a passive periodic(3-Barium Borate-calcite configuration, where the inter-plate pulse interference is found to form an azimuthal tuning restriction and to lower plate length tolerance. A subsequent numerical simulation with pump depletion is in good accordance with theoretical prediction.

  1. Quasi-phase-matched backward second-harmonic generation by complementary media in nonlinear metamaterials.

    Science.gov (United States)

    Quan, Li; Liu, Xiaozhou; Gong, Xiufen

    2012-10-01

    High efficiency of the second-harmonic and sum-frequency generation can be obtained in optical superlattice by using the conventional quasi-phase-matched (QPM) method. Although this trick can be played on the acoustic wave, the media with negative nonlinear parameters are not common in acoustics. Furthermore, the QPM method used in acoustic metamaterials has been less studied. In this work, a protocol is provided to realize the QPM method by using nonlinear complementary media in acoustic metamaterials in order to obtain large backward second-harmonic generation. Compared with the conventional method, the method gains a broader bandwidth and can be used in both acoustic and electromagnetic waves. PMID:23039551

  2. 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 frequency....... A simple model for the process using semiclassical theory is derived, and quadrature-squeezing spectra of the involved fundamental fields are deduced. The analysis shows that vacuum squeezing reminiscent of subthreshold optical parametric oscillator squeezing is present and, in the ideal case......, perfect. Under slight modifications of the operational conditions, the system is shown to produce efficient bright, squeezed light. Furthermore, we investigate the degree of polarization squeezing and find that three Stokes parameters can be squeezed simultaneously. Finally, we gauge the process for...

  3. Probing Ferroelectric Domain Engineering in BiFeO3 Thin Films by Second Harmonic Generation.

    Science.gov (United States)

    Trassin, Morgan; Luca, Gabriele De; Manz, Sebastian; Fiebig, Manfred

    2015-09-01

    An optical probe of the ferroelectric domain distribution and manipulation in BiFeO3 thin films is reported using optical second harmonic generation. A unique relation between the domain distribution and its integral symmetry is established. The ferroelectric signature is even resolved when the film is covered by a top electrode. The effect of voltage-induced ferroelectric switching is imaged. PMID:26175000

  4. Characterization of excitation beam on second-harmonic generation in fibrillous type I collagen

    OpenAIRE

    Chang, Ying; Deng, Xiaoyuan

    2010-01-01

    Following our established theoretical model to deal with the second-harmonic generation (SHG) excited by a linearly polarized focused beam in type I collagen, in this paper, we further quantitatively characterize the differences between SHG emissions in type I collagen excited by collimated and focused beams. The effects of the linear polarization angle (α) and the fibril polarity characterized by the hyperpolarizability ratio ρ on SHG emission has been compared under collimated and focused b...

  5. Second harmonic generation from nanocrystals under linearly and circularly polarized excitations

    OpenAIRE

    Hsieh, C.-L.; Pu, Y.; Grange, R.; Psaltis, D.

    2010-01-01

    We study second harmonic generation (SHG) from noncentrosymmetric nanocrystals under linearly polarized (LP) and circularly polarized (CP) excitations. Theoretical models are developed for SHG from nanocrystals under both plane-wave and focused excitations. We find that the focused excitation reduces the polarization dependency of the SHG signal. We show that the SHG response under CP excitation is generally inferior to the average of LP excitations over all orientations. We verify the theory...

  6. Whispering-gallery-mode analysis of phase-matched doubly resonant second-harmonic generation

    Science.gov (United States)

    Dumeige, Yannick; Féron, Patrice

    2006-12-01

    We propose a coupled modes analysis of second-harmonic generation in microdisk resonators. We demonstrate that whispering gallery modes can be used to obtain a combination of modal and geometrical quasi-phase-matching (without domain inversion) to obtain efficient conversion in isotropic and nonferroelectric materials such as III-V semiconductor compounds. Finally we use an analytical model to describe the coupling between a bus waveguide and the nonlinear microdisk to achieve an optimization scheme for practical configuration.

  7. Whispering-gallery-mode analysis of phase-matched doubly resonant second-harmonic generation

    International Nuclear Information System (INIS)

    We propose a coupled modes analysis of second-harmonic generation in microdisk resonators. We demonstrate that whispering gallery modes can be used to obtain a combination of modal and geometrical quasi-phase-matching (without domain inversion) to obtain efficient conversion in isotropic and nonferroelectric materials such as III-V semiconductor compounds. Finally we use an analytical model to describe the coupling between a bus waveguide and the nonlinear microdisk to achieve an optimization scheme for practical configuration

  8. Second harmonic generation in a quasi-phase matched structure containing a saturable absorber

    OpenAIRE

    Mel'nikov, I.V.; Kazansky, P. G.; Russell, P.St.J

    1995-01-01

    Quasi-phase matching has achieved wide recognition as a powerful and versatile tool for efficient second harmonic generation (SHG). In such media, for imperfect phase matching. the process of frequency up-conversion evolves periodically with distance because the residual pump nave is parametrically amplified is regions of high conversion efficiency. This results in frequency down-conversion. Even when perfect phase-matching is met, any noise power at the fundamental frequency will be strongly...

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

    OpenAIRE

    Latour, Gaël; Kowalczuk, Laura; Savoldelli, Michèle; Bourges, Jean-Louis; Plamann, Karsten; Behar-Cohen, Francine; Schanne-Klein, Marie-Claire

    2012-01-01

    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 a...

  10. 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.

  11. Imaging skeletal muscle using second harmonic generation and coherent anti-Stokes Raman scattering microscopy

    OpenAIRE

    Pfeffer, Christian P.; Olsen, Bjorn R.; Ganikhanov, Feruz; Légaré, François

    2011-01-01

    We describe experimental results on label free imaging of striated skeletal muscle using second harmonic generation (SHG) and coherent anti-Stokes Raman scattering (CARS) microscopy. The complementarity of the SHG and CARS data makes it possible to clearly identify the main sarcomere sub-structures such as actin, myosin, acto-myosin, and the intact T-tubular system as it emanates from the sarcolemma. Owing to sub-micron spatial resolution and the high sensitivity of the CARS microscopy techni...

  12. 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...... grains is used, effects of incoherent addition of contributions from the individual grains will be seen in the polarization dependence of the signal....

  13. Uniform polarity microtubule assemblies imaged in native brain tissue by second-harmonic generation microscopy

    OpenAIRE

    Dombeck, Daniel A.; Kasischke, Karl A.; Vishwasrao, Harshad D.; Ingelsson, Martin; Hyman, Bradley T.; Webb, Watt W.

    2003-01-01

    Microtubule (MT) ensemble polarity is a diagnostic determinant of the structure and function of neuronal processes. Here, polarized MT structures are selectively imaged with second-harmonic generation (SHG) microscopy in native brain tissue. This SHG is found to colocalize with axons in both brain slices and cultured neurons. Because SHG arises only from noninversion symmetric structures, the uniform polarity of axonal MTs leads to the observed signal, whereas the mixed polarity in dend...

  14. Estimating the helical pitch angle of amylopectin in starch using polarization second harmonic generation microscopy

    OpenAIRE

    Psilodimitrakopoulos S.; Amat-Roldan I.; Loza-Alvarez P.; Artigas D.

    2010-01-01

    Starch granules are among the brightest natural second harmonic generation (SHG) converters. They basically consist of amylose and amylopectin molecules and the source of the SHG signal is still undetermined. In the present study we perform polarization sensitive SHG (PSHG) imaging of wheat starch granules and we fit the SHG signal variation of each pixel of the PSHG images into a generalized biophysical model. By assuming that the SHG source molecule is a helix with cylindrica...

  15. Enabling Multiphoton and Second Harmonic Generation Imaging in Paraffin-Embedded and Histologically Stained Sections

    OpenAIRE

    Monaghan, Michael G.; Kroll, Sebastian; Brucker, Sara Y.; Schenke-Layland, Katja

    2016-01-01

    Nonlinear microscopy, namely multiphoton imaging and second harmonic generation (SHG), is an established noninvasive technique useful for the imaging of extracellular matrix (ECM). Typically, measurements are performed in vivo on freshly excised tissues or biopsies. In this article, we describe the effect of rehydrating paraffin-embedded sections on multiphoton and SHG emission signals and the acquisition of nonlinear images from hematoxylin and eosin (H&E)-stained sections before and after a...

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

    OpenAIRE

    Bovino, Fabio Antonio; Braccini, Matteo; 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 t...

  17. Second harmonic generation imaging of dermal collagen component in human keloid tissue

    Science.gov (United States)

    Yu, H. B.; Chen, S.; Zhu, X. Q.; Yang, H. Q.; Chen, J. X.

    2011-01-01

    In this paper, we report second harmonic generation (SHG) imaging of human keloid tissue. High resolution SHG images of collagen component were obtained in the superficial, medial and deep dermis of human keloid tissue, respectively. Our results show that this method has a capability to observe the structure of collagen component in human keloid tissue, which will help to better understand the formation process of human keloid scar at the molecular level.

  18. Nonlinear Fano Profiles in the Optical Second-Harmonic Generation from Silver Nanoparticles

    OpenAIRE

    Butet, J.; Bachelier, G.; Russier-Antoine, I.; Bertorelle, F.; Mosset, A.; Lascoux, N.; Jonin, C.; Benichou, E.; Brevet, P. -F.

    2012-01-01

    The resonance effects on the optical second harmonic generation from 140 nm silver nanoparticles is studied experimentally by hyper-Rayleigh scattering and numerically by finite element method calculations. We find that the interferences between the broad dipolar and narrow octupolar surface plasmon resonances leads to nonlinear Fano profiles that can be externally controlled by the incident polarization angle. These profiles are responsible for the nonlinear plasmon-induced transparency in t...

  19. Second Harmonic Generation in Neurons: Electro-Optic Mechanism of Membrane Potential Sensitivity

    OpenAIRE

    Jiang, Jiang; Eisenthal, Kenneth B.; Yuste, Rafael

    2007-01-01

    Second harmonic generation (SHG) from membrane-bound chromophores can be used to image membrane potential in neurons. We investigate the biophysical mechanism responsible for the SHG voltage sensitivity of the styryl dye FM 4-64 in pyramidal neurons from mouse neocortical slices. SHG signals are exquisitely sensitive to the polarization of the incident laser light. Using this polarization sensitivity in two complementary approaches, we estimate a ∼36° tilt angle of the chromophore to the memb...

  20. Detecting Subtle Plasma Membrane Perturbation in Living Cells Using Second Harmonic Generation Imaging

    OpenAIRE

    Moen, Erick K.; Ibey, Bennett L.; Beier, Hope T.

    2014-01-01

    The requirement of center asymmetry for the creation of second harmonic generation (SHG) signals makes it an attractive technique for visualizing changes in interfacial layers such as the plasma membrane of biological cells. In this article, we explore the use of lipophilic SHG probes to detect minute perturbations in the plasma membrane. Three candidate probes, Di-4-ANEPPDHQ (Di-4), FM4-64, and all-trans-retinol, were evaluated for SHG effectiveness in Jurkat cells. Di-4 proved superior with...

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

    International Nuclear Information System (INIS)

    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

  2. Note: auto-relock system for a bow-tie cavity for second harmonic generation.

    Science.gov (United States)

    Haze, Shinsuke; Hata, Sousuke; Fujinaga, Munekazu; Mukaiyama, Takashi

    2013-02-01

    This Note reports on the implementation of an automatic relocking system for a bow-tie cavity for second harmonic generation to produce an ultra-violet laser source. The system is based on a sample-and-hold technique for controlling the cavity length using simple servo electronics. Long-term stabilization of the cavity output power is successfully achieved, which makes this system suitable for designing stable atomic physics experiments. PMID:23464273

  3. 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.

  4. Background-free electric field-induced second harmonic generation with interdigitated combs of electrodes.

    Science.gov (United States)

    Jašinskas, Vidmantas; Gedvilas, Mindaugas; Račiukaitis, Gediminas; Gulbinas, Vidmantas

    2016-06-15

    The electric field-induced second harmonic (EFISH) generation is a powerful tool for the investigation of optical nonlinearities, material polarization, internal electric fields, and other properties of photonic materials and devices. A conventional generation of the second harmonics (SH) in materials with the disturbed centrosymmetry causes a field-independent background to EFISH and limits its applications. Here we suggest and analyze the application of the interdigitated combs of electrodes for EFISH generation in thin films. Interdigitated electrodes form an optical transmission amplitude diffraction grating. Phase matching of the EFISH radiation creates unusual diffraction fringes with the zero intensity along the zeroth order direction and with the diffraction angles different from diffraction angles of incident fundamental laser radiation and its second harmonics. It enables a simple geometrical separation of the EFISH signal from a conventional SH background, simplifies the sample preparation, and provides additional experimental possibilities. We demonstrate applicability of the suggested technique for characterization of submicrometer thickness organic films of transparent and resonantly interacting polymers and of their mixtures. PMID:27304282

  5. Cumulative Second Harmonic Generation in Lamb Waves for the Detection of Material Nonlinearities

    International Nuclear Information System (INIS)

    An understanding of the generation of higher harmonics in Lamb waves is of critical importance for applications such as remaining life prediction of plate-like structural components. The objective of this work is to use nonlinear Lamb waves to experimentally investigate inherent material nonlinearities in aluminum plates. These nonlinearities, e.g. lattice anharmonicities, precipitates or vacancies, cause higher harmonics to form in propagating Lamb waves. The amplitudes of the higher harmonics increase with increasing propagation distance due to the accumulation of nonlinearity while the Lamb wave travels along its path. Special focus is laid on the second harmonic, and a relative nonlinearity parameter is defined as a function of the fundamental and second harmonic amplitude. The experimental setup uses an ultrasonic transducer and a wedge for the Lamb wave generation, and laser interferometry for detection. The experimentally measured Lamb wave signals are processed with a short-time Fourier transformation (STFT), which yields the amplitudes at different frequencies as functions of time, allowing the observation of the nonlinear behavior of the material. The increase of the relative nonlinearity parameter with propagation distance as an indicator of cumulative second harmonic generation is shown in the results for the alloy aluminum 1100-H14

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

    DEFF Research Database (Denmark)

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

    2002-01-01

    transverse wave number, which are not identified in a linearized analysis, are also described. The intensity differences between opposite points of the far fields are shown to exhibit sub-Poissonian statistics, revealing the quantum nature of the correlations. We observe twin beam correlations in both the......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...... pattern formation, beams with opposite direction of the off-axis critical wave numbers are shown to be highly correlated. This is observed for the fundamental field, for the second-harmonic field, and also for the cross-correlation between the two fields. Nonlinear correlations involving the homogeneous...

  7. Second-harmonic generation in the relativistic laser-cluster interaction

    International Nuclear Information System (INIS)

    Full text: The model of coherent second-harmonic generation has been developed for irradiation of large atomic clusters by relativistic laser field. Second harmonic is produced by the magnetic part of the Lorentz force. The harmonic yield is proportional to the square of number of particles in the cluster and to the square of the laser intensity. The yield increases resonantly twice: when the Mie frequency is equal to 2ω, and when the Mie frequency is equal to ω. We found that the generation of second harmonic in clusters by the relativistic laser field is much more effective than in the continuous plasma medium. Induced oscillations of a free electron inside the irradiated cluster along the propagation of laser pulse are described by the Newton equation for the CM position of the spherical electron cloud. Analogous approach for the non-relativistic case was developed by Tajima et al. The calculations of the time-dependent dispersion of Ar clusters at high laser intensity in which the individual clusters are exploding on the time scale of the femtosecond laser pulse have been carried out. The barrier-suppression mechanism governs inner field ionization in this case, while collision ionization can be neglected. Outer ionization produces a static Coulomb field inside the ionized cluster. This field increases the charge multiplicity of the atomic ions produced inside the cluster approximately by a factor of 1.5. We derive the accumulated charge on the ionized cluster starting from the Bethe rule for outer electron barrier-suppression field ionization. The cluster expansion is determined by the Coulomb explosion and hydrodynamic expansion. The damping mechanism is the elastic collisions of inner electrons with the cluster surface. The absorption of laser energy is equal to the twice of the ponderomotive energy at each collision in the presence of laser field (analogously to induced inverse Bremsstrahlung at the collision with an atomic ion). In the typical experiment

  8. Phase-matched second harmonic generation and nonlinear phase shift in a Langmuir-Blodgett film waveguide

    Science.gov (United States)

    Schrader, Sigurd K.; Flueraru, Costel; Motschmann, Hubert; Brehmer, Ludwig

    2001-12-01

    Wave-guides have been prepared as y-type Langmuir-Blodgett multilayers from 2-docosylamino-5-nitropyridine (DCANP) on quartz glass substrates. The tensor elements of the LB-films as determined by polarization dependent second harmonic generation (SHG) are (Formula available in paper) The wave-guides were fabricated in a way that the second-order susceptibility changes sign at the nodal plane of the first-order wave-guide mode for s-polarization. In such wave-guides efficient second harmonic generation (SHG) was reached via mode conversion at a fundamental wavelength near 1064 nm. The conversion efficiency reached the extraordinary high value of 8%/W which corresponds to a normalized conversion efficiency of 3600 %/(W cm2). In addition, interferometric measurements have been carried out to study the non-linear phase-shift which the fundamental beam experiences due to non-linear interaction in the wave-guide. From these experiments an apparent intensity-dependent refractive index n2SHG of 2,6 10-13 cm2/W was calculated. This as about 400 times the intensity-dependent refractive as expected from third-order susceptibility of the isotropic material. From that it can be concluded that the main contribution of the intensity-dependent refractive index is connected to cascading of second-order processes.

  9. Second harmonic generation in inhomogeneous MgO:LiNbO3 waveguides

    Institute of Scientific and Technical Information of China (English)

    Li Guo-Hui; Jiang Hai-Ling; Xu Xin-Ye

    2011-01-01

    A fibre laser at 1111.6 nm is frequency doubled by two inhomogeneous MgO:LiNbO3 waveguides and the output powers of 85 mW and 49 mW at 555.8 nm have been generated with the conversion efficiencies of 47% and 27% respectively. By analysing the second harmonic generation temperature tuning curves, we investigate the influence of the optical inhomogeneities upon the conversion efficiency. The final result shows that the efficiency difference is mainly affected by the optical inhomogeneities in our case.

  10. Efficient second harmonic generation in a metamaterial with two resonant modes coupled through two varactor diodes

    Science.gov (United States)

    Nakanishi, Toshihiro; Tamayama, Yasuhiro; Kitano, Masao

    2012-01-01

    We present an effective method to generate second harmonic (SH) waves using nonlinear metamaterial composed of coupled split ring resonators (CSRRs) with varactor (variable capacitance) diodes. The CSRR structure has two resonant modes: a symmetric mode that resonates at the fundamental frequency and an anti-symmetric mode that resonates at the SH frequency. Resonant fundamental waves in the symmetric mode generate resonant SH waves in the anti-symmetric mode. The double resonance contributes to effective SH radiation. In the experiment, we observe 19.6 dB enhancement in the SH radiation in comparison with the nonlinear metamaterial that resonates only for the fundamental waves.

  11. Second harmonic generation spectroscopy of p-cresol and carbazole on SiO 2 surfaces

    Science.gov (United States)

    van Wyck, N. E.; Koenig, E. W.; Byers, J. D.; Hetherington, W. M., III

    1985-11-01

    Surface second harmonic generation (SHG) has been developed as a surface specific type of electronic spectroscopy. The surface second-order susceptibility χ (2) is enhanced by the adsorption of molecules, and an electronic spectrum can be generated by scanning the dye laser through the two-photon resonances of the adsorbate. The spectra of p-cresol ionically and covalently bound to SiO 2 and of carbazole covalently bound to SiO 2 have been obtained. Weakly bound molecules such as hydrogen-bonded cresol, phenol and aniline as well as pyridine are rapidly desorbed by the competitive process of two-photon absorption.

  12. Spatial and spectral properties of second harmonic generation in a periodically poled KTP waveguide

    Czech Academy of Sciences Publication Activity Database

    Machulka, R.; Svozilík, J.; Soubusta, Jan; Peřina ml., Jan; Haderka, O.

    Bellingham : SPIE, 2012 - (Peřina jr., J.; Nožka, L.; Hrabovský, M.; Senderáková, D.; Urbańczyk, W.) ISBN 978-0-8194-9481-8. ISSN 0277-786X. - (Proceedings of SPIE. 8697). [Czech-Polish-Slovak optical conference on wave and quantum aspects of contemporary optics /18./. Ostravice (CZ), 03.09.2012-07.09.2012] R&D Projects: GA AV ČR IAA100100713 Grant ostatní: GA MŠk(CZ) OC09026 Institutional research plan: CEZ:AV0Z10100522 Keywords : waveguide * second harmonic generation * periodic poling Subject RIV: BH - Optics, Masers, Lasers

  13. Spectral phase correlation of coded femtosecond pulses by second-harmonic generation in thick nonlinear crystals.

    Science.gov (United States)

    Zheng, Z; Weiner, A M

    2000-07-01

    We demonstrate a novel all-optical scheme for measuring the correlation of spectrally phase-coded ultrashort optical waveforms that uses second-harmonic generation (SHG) in long, periodically poled lithium niobate crystals. The SHG yield can be controlled over a range of ~30 dB, depending on the correlation of the applied phase codes. Such a spectral phase correlator has applications for ultrashort-pulse optical code-division multiple-access networking and could serve as a nonlinear optical but classical analog for certain schemes for coherent quantum control of multiphoton processes. PMID:18064248

  14. Second harmonic generation in a high-Q lithium niobate microresonator fabricated by femtosecond laser micromachining

    CERN Document Server

    Lin, Jintian; Fang, Zhiwei; Song, Jiangxin; Wang, Nengwen; Qiao, Lingling; Fang, Wei; Cheng, Ya

    2014-01-01

    We report on fabrication of high Q lithium niobate (LN) whispering-gallery-mode (WGM) microresonators suspended on silica pedestals by femtosecond laser microfabrication. The micrometer-scale (diameter ~82 {\\mu}m) LN resonator possesses a Q factor of 2.5x10^5 around 1550 nm wavelength range. Moreover, second harmonic generation with a continuous-wave tunable single-longitudinal-mode pump laser in the on-chip LN microresonator is demonstrated in the on-chip LN microresonator. A fiber taper is employed to couple the pump laser into the microresonator, showing a normalized conversion efficiency of 1.35x10^-5/mW.

  15. Broadband second harmonic generation in an imperfect nonlinear photonic crystal with random defects

    Science.gov (United States)

    Ren, Kun; Liu, Yali; Ren, Xiaobin; Fan, Jingyang

    2016-09-01

    In this paper, we study broadband second harmonic generation (SHG) in an imperfect nonlinear photonic crystal in which defects are introduced with random lengths. We show that the efficient SHG output is obtained when the length of each defect varies near certain specialized values. The bandwidth of the SHG output broadens with the increasing randomness of defect length. Moreover, the SHG bandwidth is nearly unaffected only when the total length of the whole structure is long enough. The disordered structure also exhibits good tolerance to the fabrication error, which provides a way to control SHG intensity and bandwidth separately.

  16. Imaging molecular structure with Stokes-polarimeter based second harmonic generation microscopy

    Science.gov (United States)

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

    2013-02-01

    We analyzed the polarization states of second harmonic generation (SHG) signals from starch granules and type I collagen through a four-channel photon counting based Stokes-polarimeter. The 2D SHG images of samples are reconstructed using various polarization parameters, such as the degree of polarization (DOP), the degree of linear polarization (DOLP), the degree of circular polarization (DOCP), as well as the anisotropy from the acquired Stokes parameters. Furthermore, we have demonstrated that the polarization parameters are changes at different input polarizations and focusing depths.

  17. Second harmonic generation of a new nonlinear optical material:urea L-malic acid

    Institute of Scientific and Technical Information of China (English)

    CHEN Ding-an; ZHU Li; HU Yong-hong; XU Ling-ling; CUI Yi-ping

    2006-01-01

    Second harmonic generation (SHG) of a new organic optical crystal-urea L-malic acid (ULMA) was studied.A comparison of SHG efficiency of ULMA and KDP at a fundamental wavelength of 1 064 nm using the Kurtz powder method demonstrated that the second order nonlinear coefficient of ULMA is 1.57 times of that of KDP,and the damage threshold of ULMA is relatively higher.Finally,both Type I and Type II phase match angles of the biaxial crystal ULMA were calculated.

  18. 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.

  19. Observation of self-pulsing in singly resonant optical second-harmonic generation with competing nonlinearities

    DEFF Research Database (Denmark)

    Bache, Morten; Lodahl, Peter; Mamaev, Alexander V.;

    2002-01-01

    We predict and experimentally observe temporal self-pulsing in singly resonant intracavity second-harmonic generation under conditions of simultaneous parametric oscillation. The threshold for self-pulsing as a function of cavity tuning and phase mismatch are found from analysis of a three-compon......-component mean-field model. Analytical mean-field calculations of the self-pulsing frequency as well as numerical simulations including the effects of a time-dependent pump pulse agree with the experimentally observed frequencies....

  20. Enhancing second harmonic generation in gold nanoring resonators filled with lithium niobate.

    Science.gov (United States)

    Lehr, Dennis; Reinhold, Jörg; Thiele, Illia; Hartung, Holger; Dietrich, Kay; Menzel, Christoph; Pertsch, Thomas; Kley, Ernst-B; Tünnermann, Andreas

    2015-02-11

    Plasmonic nanorings provide the unique advantage of a pronounced plasmonic field enhancement inside their core. If filled with a polarizable medium, it may significantly enhance its optical effects. Here, we demonstrate this proposition by filling gold nanorings with lithium niobate. The generated second harmonic signal is compared to the signal originating from an unpatterned lithium niobate surface. Measurements and simulation confirm an enhancement of about 20. Applications requiring nanoscopic localized light sources like fluorescence spectroscopy or quantum communication will benefit from our findings. PMID:25584636

  1. Second-Harmonic Generation Imaging of Membrane Potential with Retinal Analogues

    OpenAIRE

    Theer, Patrick; Denk, Winfried; Sheves, Mordechai; Lewis, Aaron; Detwiler, Peter B.

    2011-01-01

    Second-harmonic generation (SHG) by membrane-incorporated probes is a nonlinear optical signal that is voltage-sensitive and the basis of a sensitive method for imaging membrane potential. The voltage dependence of SHG by four different probes, three retinoids (all-trans retinal), and two new retinal analogs, 3-methyl-7-(4′-dimethylamino-phenyl)-2,4,6-heptatrienal (AR-3) and 3,7-dimethyl-9-(4′-dimethylamino-phenyl)-2,4,6,8-nonatetraenal (AR-4), and a styryl dye (FM4-64), were compared in HEK-...

  2. Inner surface enhanced femtosecond second harmonic generation in thin ZnO crystal tubes

    OpenAIRE

    Xu, SJ; Ning, JQ; Che, CM; Zheng, CC; Zhang, SF; Wang, JY; Hao, JH

    2011-01-01

    At room temperature, efficient second harmonic generation (SHG) emission is observed in thin ZnO crystal hollow rods (tubes) with diameter∼0.2 mm under the excitation of femtosecond laser from 700 to 860 nm. Power and polarization dependence of the SHG signal on the primary excitation beam is also measured. The multiple total reflections between the outer and inner surfaces of the sample are analyzed to be responsible for the efficient SHG. Ninefold amplification of SHG signal in the tube str...

  3. Quadrupole second harmonic generation and sum-frequency generation in ZnO quantum dots

    International Nuclear Information System (INIS)

    The second harmonic generation (SHG) and the sum frequency generation (SFG) processes are investigated in the conduction band states of the singly charged ZnO quantum dot (QD) embedded in the HfO2, and the AlN matrices. With two optical fields of frequency ωp and ωq incident on the dot, we study the variation with frequency of the second order nonlinear polarization resulting in SHG and SFG, through the electric dipole and the electric quadrupole interactions of the pump fields with the electron in the dot. We obtain enhanced value of the second order nonlinear susceptibility in the dot compared to the bulk. The effective mass approximation with the finite confining barrier is used for obtaining the energy and wavefunctions of the quantized confined states of the electron in the conduction band of the dot. Our results show that both the SHG and SFG processes depend on the dot size, the surrounding matrix and the polarization states of the pump beams

  4. Quadrupole second harmonic generation and sum-frequency generation in ZnO quantum dots

    Directory of Open Access Journals (Sweden)

    Deepti Maikhuri

    2015-04-01

    Full Text Available The second harmonic generation (SHG and the sum frequency generation (SFG processes are investigated in the conduction band states of the singly charged ZnO quantum dot (QD embedded in the HfO2, and the AlN matrices. With two optical fields of frequency ωp and ωq incident on the dot, we study the variation with frequency of the second order nonlinear polarization resulting in SHG and SFG, through the electric dipole and the electric quadrupole interactions of the pump fields with the electron in the dot. We obtain enhanced value of the second order nonlinear susceptibility in the dot compared to the bulk. The effective mass approximation with the finite confining barrier is used for obtaining the energy and wavefunctions of the quantized confined states of the electron in the conduction band of the dot. Our results show that both the SHG and SFG processes depend on the dot size, the surrounding matrix and the polarization states of the pump beams.

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

    DEFF Research Database (Denmark)

    Bache, Morten; Bang, Ole; Zhou, Binbin;

    2010-01-01

    -transform-limited ultrashort mid-IR pulses with pulse durations much shorter than the input near-IR pulse. The Cherenkov radiation for the crystal considered (β-barium borate) is found for pump wavelengths in the range λ = 0.95–1.45 μm, and is located in the regime λ = 1.5–3.5 μm. For shorter pump wavelengths, the phase...

  6. Effective nonlinearities and multi-wavelength second-harmonic generation in modulated quasi-phase-matching gratings

    OpenAIRE

    Bang, Ole; Graversen, T. W.; Clausen, Carl A. Balslev

    2000-01-01

    Quasi-phase-matching gratings induces Kerr effects in quadratic nonlinear materials. We show analytically and confirm numerically how modulating the grating changes the effective quadratic and cubic nonlinearities and allows for multi-wavelength second-harmonic generation.

  7. Highly efficient second harmonic generation of a light carrying orbital angular momentum in an external cavity.

    Science.gov (United States)

    Zhou, Zhi-Yuan; Li, Yan; Ding, Dong-Sheng; Zhang, Wei; Shi, Shuai; Shi, Bao-Sen; Guo, Guang-Can

    2014-09-22

    Traditional methods for generating a light carrying orbital angular momentum (OAM) include the use of holographic diffraction gratings, vortex phase plates and spatial light modulators. Here we report a new method for highly efficient second-harmonic generation (SHG) of a light with OAM. By properly aligning an external cavity that contains a quasi-phase matching nonlinear crystal and pumping it with a light carrying OAM, mode matching between the pump light and the cavity's higher order Laguerre-Gaussian (LG) mode is achieved, SHG with a conversion efficiency of up to 10.3% is obtained. We have demonstrated for the first time that the cavity can stably operate at its higher order LG mode similar to that of a Gaussian mode. The second harmonic generated light has an OAM value that is double with respected to the OAM value of the pump light. The parameters that affect the beam quality and conversion efficiency are discussed in detail. Our work opens a brand new field in laser optics and makes the first step toward high efficiency processing using a light carrying OAM. PMID:25321833

  8. Sum frequency and second harmonics generation of copper vapor laser by nonlinear crystals

    International Nuclear Information System (INIS)

    We have demonstrated sum frequency and second harmonic generation using green (510 nm) and yellow (578 nm) laser light of copper vapor lasers (CVL) by nonlinear crystals of KDP and BBO. The beam patterns of the converted UV laser light become stripe due to the restriction of the acceptance angle of KDP crystal which is estimated to be 1.58 mrad. · cm. Conversion efficiency depends on effective crystal length and focusing condition of fundamental laser beam, and is maximized by a convex lens with the focal length of 555 nm. In sum frequency generation, the temporal delay and the pulse shape of 578 nm laser pulse limit the conversion efficiency. In first second harmonic generation using injection locking CVL oscillator system which can produce low beam divergence fundamental laser beam, the maximum conversion efficiency is 11.2% at the incident power of 75 MW/cm2. The BBO crystal is damaged by the higher incident laser power of over 100 MW/cm2. (author)

  9. 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

    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...

  10. Effective nonlinearities and multi-wavelength second-harmonic generation in modulated quasi-phase-matching gratings

    DEFF Research Database (Denmark)

    Bang, Ole; Graversen, T. W.; Clausen, Carl A. Balslev

    2000-01-01

    Quasi-phase-matching gratings induces Kerr effects in quadratic nonlinear materials. We show analytically and confirm numerically how modulating the grating changes the effective quadratic and cubic nonlinearities and allows for multi-wavelength second-harmonic generation.......Quasi-phase-matching gratings induces Kerr effects in quadratic nonlinear materials. We show analytically and confirm numerically how modulating the grating changes the effective quadratic and cubic nonlinearities and allows for multi-wavelength second-harmonic generation....

  11. Characterization of LiB(3)O(5) crystal for second-harmonic generation.

    Science.gov (United States)

    Xie, F; Wu, B; You, G; Chen, C

    1991-08-15

    We present second-harmonic generation characteristics of LiB(3)O(5) (LBO) crystal with different phase-matching lengths and comparison with those of beta-BaB(2)O(4) crystal. A computer program of the numerical interaction method was adopted to make the theoretical calculation of second-harmonic generation conversion efficiencies of LBO with different phase-matching lengths and power densities of the fundamental beam of a Nd:YAG laser, and the calculated result was compared with the experimental one. It is seen from the calculated and experimental results that for certain power densities of the fundamental laser beam, so long as the length of the LBO crystal is selected appropriately, a high energy conversion efficiency could be obtained. For example, an optimal external energy conversion efficiency of LBO crystal of more than 70% has been attained for several 100-MW/cm(2) fundamental laser beams. Experiments also showed that the crystal could be used under high power densities without any damage to the surface and the interior. PMID:19776930

  12. Texture analysis applied to second harmonic generation image data for ovarian cancer classification

    Science.gov (United States)

    Wen, Bruce L.; Brewer, Molly A.; Nadiarnykh, Oleg; Hocker, James; Singh, Vikas; Mackie, Thomas R.; Campagnola, Paul J.

    2014-09-01

    Remodeling of the extracellular matrix has been implicated in ovarian cancer. To quantitate the remodeling, we implement a form of texture analysis to delineate the collagen fibrillar morphology observed in second harmonic generation 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 second harmonic generation images, we then perform classification between images of normal and high grade malignant ovarian tissues. By optimizing the number of textons and nearest neighbors, we achieved classification accuracy up to 97% 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.

  13. Towards protein-crystal centering using second-harmonic generation (SHG) microscopy

    International Nuclear Information System (INIS)

    The potential of second-harmonic generation (SHG) microscopy for automated crystal centering to guide synchrotron X-ray diffraction of protein crystals has been explored. The potential of second-harmonic generation (SHG) microscopy for automated crystal centering to guide synchrotron X-ray diffraction of protein crystals was explored. These studies included (i) comparison of microcrystal positions in cryoloops as determined by SHG imaging and by X-ray diffraction rastering and (ii) X-ray structure determinations of selected proteins to investigate the potential for laser-induced damage from SHG imaging. In studies using β2 adrenergic receptor membrane-protein crystals prepared in lipidic mesophase, the crystal locations identified by SHG images obtained in transmission mode were found to correlate well with the crystal locations identified by raster scanning using an X-ray minibeam. SHG imaging was found to provide about 2 µm spatial resolution and shorter image-acquisition times. The general insensitivity of SHG images to optical scatter enabled the reliable identification of microcrystals within opaque cryocooled lipidic mesophases that were not identified by conventional bright-field imaging. The potential impact of extended exposure of protein crystals to five times a typical imaging dose from an ultrafast laser source was also assessed. Measurements of myoglobin and thaumatin crystals resulted in no statistically significant differences between structures obtained from diffraction data acquired from exposed and unexposed regions of single crystals. Practical constraints for integrating SHG imaging into an active beamline for routine automated crystal centering are discussed

  14. Analysis of second harmonic generation in photonic-crystal-assisted waveguides

    CERN Document Server

    D'Orazio, A; De Ceglia, D; De Sario, M; Prudenzano, F; Scalora, M; Bloemer, Mark J.; Ceglia, Domenico de; Orazio, Antonella D'; Prudenzano, Francesco; Sario, Marco De; Scalora, Michael

    2006-01-01

    We study second harmonic generation in a planar dielectric waveguide having a low-index, polymer core layer, bounded by two multilayer stacks. This geometry allows exceptionally strong confinement of the light at the fundamental wavelength inside the core region with virtually zero net propagation losses for distances that exceed several centimeters, provided material and scattering losses are neglected. A phase-matched configuration of the waveguide is reported in which the pump signal is the lowest-order mode of the waveguide, and the generated second harmonic signal corresponds to the third propagation mode of the waveguide. Using a polymer waveguide core, having chi(2)=100 pm/V, we predict a conversion efficiency of approximately 90% after a propagation distance of 2 mm, using peak pump intensities inside the core of the waveguide of 1.35 GW/cm^2. If the waveguide core contains polymer layers with different glass transition temperatures, the layers can be poled independently to maximize the overlap integr...

  15. 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. PMID:26204257

  16. Second Harmonic Generation as a Nondestructive Readout of Optical (Photo(electro)chromic and Magnetic) Memories

    Science.gov (United States)

    Aktsipetrov, O.; Fedyanin, A.; Melnikov, A.; Mishina, E.; Murzina, T.

    1998-01-01

    Optical second harmonic generation (SHG) is suggested as a nonlinear-optical nondestructive readout of (thin) film-based optical memories. Systematic studies of photoinduced, electroinduced, and magnetoinduced variations in the anisotropic SHG intensity in (i) thin solid photo(electro)chromic films of bacteriorhodopsin, (ii) photosensitive Langmuir-Blodgett films of 4-nitro-4'-N-octadecylazobenzene, and (iii) rare-earth iron garnet films show sufficient modification of their nonlinear-optical properties by these external factors. These photo-, electro- and magnetomodified nonlinear-optical properties of thin films being used for recording the information can be easily distinguished by the SHG readout. The IR fundamental radiation used for the excitation of the SHG is shown not to disturb the information recorded in photo(electro)chromic memories. For, what is to our knowledge, the first time, the surface-bulk crossterms in the SHG intensity originating from the interference of the crystalline and magnetization induced second harmonic fields are observed in magnetic iron garnet films.

  17. Multimodal two-photon imaging using a second harmonic generation-specific dye

    Science.gov (United States)

    Nuriya, Mutsuo; Fukushima, Shun; Momotake, Atsuya; Shinotsuka, Takanori; Yasui, Masato; Arai, Tatsuo

    2016-01-01

    Second harmonic generation (SHG) imaging can be used to visualize unique biological phenomena, but currently available dyes limit its application owing to the strong fluorescent signals that they generate together with SHG. Here we report the first non-fluorescent and membrane potential-sensitive SHG-active organic dye Ap3. Ap3 is photostable and generates SH signals at the plasma membrane with virtually no fluorescent signals, in sharp contrast to the previously used fluorescent dye FM4-64. When tested in neurons, Ap3-SHG shows linear membrane potential sensitivity and fast responses to action potentials, and also shows significantly reduced photodamage compared with FM4-64. The SHG-specific nature of Ap3 allows simultaneous and completely independent imaging of SHG signals and fluorescent signals from various reporter molecules, including markers of cellular organelles and intracellular calcium. Therefore, this SHG-specific dye enables true multimodal two-photon imaging in biological samples. PMID:27156702

  18. Multimodal two-photon imaging using a second harmonic generation-specific dye.

    Science.gov (United States)

    Nuriya, Mutsuo; Fukushima, Shun; Momotake, Atsuya; Shinotsuka, Takanori; Yasui, Masato; Arai, Tatsuo

    2016-01-01

    Second harmonic generation (SHG) imaging can be used to visualize unique biological phenomena, but currently available dyes limit its application owing to the strong fluorescent signals that they generate together with SHG. Here we report the first non-fluorescent and membrane potential-sensitive SHG-active organic dye Ap3. Ap3 is photostable and generates SH signals at the plasma membrane with virtually no fluorescent signals, in sharp contrast to the previously used fluorescent dye FM4-64. When tested in neurons, Ap3-SHG shows linear membrane potential sensitivity and fast responses to action potentials, and also shows significantly reduced photodamage compared with FM4-64. The SHG-specific nature of Ap3 allows simultaneous and completely independent imaging of SHG signals and fluorescent signals from various reporter molecules, including markers of cellular organelles and intracellular calcium. Therefore, this SHG-specific dye enables true multimodal two-photon imaging in biological samples. PMID:27156702

  19. 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.

  20. 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.

  1. Membrane potential dynamics of axons in cultured hippocampal neurons probed by second-harmonic-generation imaging

    Science.gov (United States)

    Nuriya, Mutsuo; Yasui, Masato

    2010-03-01

    The electrical properties of axons critically influence the nature of communication between neurons. However, due to their small size, direct measurement of membrane potential dynamics in intact and complex mammalian axons has been a challenge. Furthermore, quantitative optical measurements of axonal membrane potential dynamics have not been available. To characterize the basic principles of somatic voltage signal propagation in intact axonal arbors, second-harmonic-generation (SHG) imaging is applied to cultured mouse hippocampal neurons. When FM4-64 is applied extracellularly to dissociated neurons, whole axonal arbors are visualized by SHG imaging. Upon action potential generation by somatic current injection, nonattenuating action potentials are recorded in intact axonal arbors. Interestingly, however, both current- and voltage-clamp recordings suggest that nonregenerative subthreshold somatic voltage changes at the soma are poorly conveyed to these axonal sites. These results reveal the nature of membrane potential dynamics of cultured hippocampal neurons, and further show the possibility of SHG imaging in physiological investigations of axons.

  2. Study of second harmonic generation by high power laser beam in magneto plasma

    International Nuclear Information System (INIS)

    This paper examines the problem of nonlinear generation of second harmonic of a high power laser pulse propagating in magnetized plasma. The propagation of strong laser beam is proposed in the direction perpendicular to a relatively weak static magnetic field. The laser pulse is taken to be linearly polarized, with the orientation of its electric field that corresponds to an ordinary electromagnetic wave. Besides the standard ponderomotive nonlinearity, the appropriate wave equation also contains the nonlinearity that arises from the relativistic electron jitter velocities. During its propagation, the laser beam gets filamented on account of relativistic and pondermotive nonlinearities present in the plasma. The generated plasma wave gets coupled into the filamentary structures of the pump beam. Due to the expected presence of the beam filamentation, the work has been carried out by considering modified paraxial approximation (i.e., beyond the standard paraxial approximation of a very broad beam). It is found that the power of the plasma wave is significantly affected by the magnetic field strength in the presence of both relativistic and pondermotive nonlinearities. It is investigated that the second harmonic generation is also considerably modified by altering the strength of magnetic field. To see the effect of static magnetic field on the harmonic generation, a key parameter, i.e., the ratio of the cyclotron frequency ωc=eB0/mc over the laser frequency ω0 has been used, where c is the velocity of light, m and e are the mass and charge of the electron and B0 is the externally applied magnetic field.

  3. 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...

  4. Second harmonic generation with plasmonic metasurfaces: direct comparison of electric and magnetic resonances

    CERN Document Server

    Chandrasekar, Rohith; Lagutchev, Alexei; Shalaev, Vladimir M; Ciraci, Cristian; Smith, David R; Kildishev, Alexander V

    2015-01-01

    Plasmonic resonances in metallic nanostructures have been shown to drastically enhance local electromagnetic fields, and thereby increase the efficiency of nonlinear optical phenomena, such as second harmonic generation (SHG). While it has been experimentally observed that enhanced fields can significantly boost SHG, to date it proved difficult to probe electrical and magnetic resonances in one and the same nanostructure. This however is necessary to directly compare relative contributions of electrical and magnetic components of SHG enhancement. In this paper we report an experimental study of a metasurface capable of providing electrical and magnetic resonant SHG enhancement for TM polarization. Our metasurface could be engineered such that the peak frequencies of electrical and magnetic resonances could be adjusted independently. We used this feature to distinguish their relative contributions. Experimentally it was observed that the magnetic resonance provides only 50% as much enhancement to SHG as compar...

  5. 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.

  6. Second harmonic generation (SHG) and two-photon fluorescence (TPF) contrast imaging in biomaterial analysis

    Science.gov (United States)

    Lang, Xuye; Lyubovitsky, Julia

    2015-07-01

    Collagen hydrogels are natural biomaterials that comprise 3D networks of high water content and have viscoelastic properties and biocompatibility similar to native tissues. Consequently, these materials play an important role in tissue engineering and regenerative medicine for quite some time. Second harmonic generation (SHG) and two-photon fluorescence (TPF) contrasts transpire as valuable label-free spectroscopic probes for analysis of these biomaterials and this presentation will report the structural, mechanical and physicochemical parameters leading to the observed optical SHG and TPF effects in synthesized 3D collagen hydrogels. We will present results regarding understanding the dependency of collagen fiber formation on ion types, new results regarding strengthening of these biomaterials with a nontoxic chemical cross-linker genipin and polarization selection of collagen fibers' orientations.

  7. Low-temperature anomalies of photoinduced second harmonic generation in skutterudites

    International Nuclear Information System (INIS)

    Photoinduced second harmonic generation (PISHG) was found in skutterudite compounds of CeFe4Sb12 and Ce0.7Fe3.5Ni0.5 Sb12. Measurements versus temperature, pump-probe delaying time and external magnetic field were performed. The studied compounds belong to moderate heavy fermion compounds (HFC) in the ground state. The PISHG signals appear at 6.8 and 4.9 K for CeFe4Sb12 and Ce0.7Fe3.5Ni0.5Sb12, respectively. We suspect that these signals are due to anharmonic electron-phonon interactions creating a charge density non-centrosymmetry. The observed effects are caused either by a possible phase transition or by drastic changes in the electron structure of the HFC with decreasing temperature

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

    International Nuclear Information System (INIS)

    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

  9. 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.

  10. 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.

  11. Second-harmonic generation imaging of collagen fibers in myocardium for atrial fibrillation diagnosis

    Science.gov (United States)

    Tsai, Ming-Rung; Chiu, Yu-Wei; Lo, Men Tzung; Sun, Chi-Kuang

    2010-03-01

    Atrial fibrillation (AF) is the most common irregular heart rhythm and the mortality rate for patients with AF is approximately twice the mortality rate for patients with normal sinus rhythm (NSR). Some research has indicated that myocardial fibrosis plays an important role in predisposing patients to AF. Therefore, realizing the relationship between myocardial collagen fibrosis and AF is significant. Second-harmonic generation (SHG) is an optically nonlinear coherent process to image the collagen network. We perform SHG microscopic imaging of the collagen fibers in the human atrial myocardium. Utilizing the SHG images, we can identify the differences in morphology and the arrangement of collagen fibers between NSR and AF tissues. We also quantify the arrangement of the collagen fibers using Fourier transform images and calculating the values of angle entropy. We indicate that SHG imaging, a nondestructive and reproducible method to analyze the arrangement of collagen fibers, can provide explicit information about the relationship between myocardial fibrosis and AF.

  12. Second harmonic generation imaging of the collagen in myocardium for atrial fibrillation diagnosis

    Science.gov (United States)

    Tsai, Ming-Rung; Chiou, Yu-We; Sun, Chi-Kuang

    2009-02-01

    Myocardial fibrosis, a common sequela of cardiac hypertrophy, has been shown to be associated with arrhythmias in experimental models. Some research has indicated that myocardial fibrosis plays an important role in predisposing patients to atrial fibrillation. Second harmonic generation (SHG) is an optically nonlinear coherent process to image the collagen network. In this presentation, we observe the SHG images of the collagen matrix in atrial myocardium and we analyzed of collagen fibers arrangement by using Fourier-transform analysis. Moreover, comparing the SHG images of the collagen fibers in atrial myocardium between normal sinus rhythm (NSR) and atrial fibrillation (AF), our result indicated that it is possible to realize the relation between myocardial fibrosis and AF.

  13. 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.

  14. Optically induced second-harmonic generation in CdI sub 2 -Cu layered nanocrystals

    CERN Document Server

    Voolless, F; Hydaradjan, W

    2003-01-01

    A large enhancement (up to 0.40 pm V sup - sup 1) of the second-order optical susceptibility was observed in CdI sub 2 -Cu single-layered nanocrystals for the Nd:YAG fundamental laser beam lambda = 1.06 mu m. The Cu impurity content and nanolayer thickness of the cleaved layers (about several nanometres) play a crucial role in the observed effect. The temperature dependence of the optical second-harmonic generation (SHG) together with its correlation with Raman spectra of low-frequency modes indicate a key role for the UV-induced anharmonic electron-phonon interactions in the observed effect. The maximal output UV-induced SHG was achieved for a Cu content of about 0.5% and at liquid helium temperatures.

  15. Acoustically induced optical second harmonic generation in hydrogenated amorphous silicon films

    CERN Document Server

    Ebothe, J; Cabarrocas, P R I; Godet, C; Equer, B

    2003-01-01

    Acoustically induced second harmonic generation (AISHG) in hydrogenated amorphous silicon (a-Si : H) films of different morphology has been observed. We have found that with increasing acoustical power, the optical SHG of Gd : YAB laser light (lambda = 2.03 mu m) increases and reaches its maximum value at an acoustical power density of about 2.10 W cm sup - sup 2. With decreasing temperature, the AISHG signal strongly increases below 48 K and correlates well with the temperature behaviour of differential scanning calorimetry indicating near-surface temperature phase transition. The AISHG maxima were observed at acoustical frequencies of 10-11, 14-16, 20-22 and 23-26 kHz. The independently performed measurements of the acoustically induced IR spectra have shown that the origin of the observed phenomenon is the acoustically induced electron-phonon anharmonicity in samples of different morphology.

  16. Surface second harmonic generation from silicon pillar arrays with strong geometrical dependence.

    Science.gov (United States)

    Choudhury, B Dev; Sahoo, Pankaj K; Sanatinia, R; Andler, Guillermo; Anand, S; Swillo, M

    2015-05-01

    We present experimental demonstration and analysis of enhanced surface second harmonic generation (SHG) from hexagonal arrays of silicon pillars. Three sets of Si pillar samples with truncated cone-shaped pillar arrays having periods of 500, 1000, and 2000 nm, and corresponding average diameters of 200, 585 and 1550 nm, respectively, are fabricated by colloidal lithography and plasma dry etching. We have observed strong dependence of SHG intensity on the pillar geometry. Pillar arrays with a 1000 nm period and a 585 nm average diameter give more than a one order of magnitude higher SHG signal compared to the other two samples. We theoretically verified the dependence of SHG intensity on pillar geometry by finite difference time domain simulations in terms of the surface normal E-field component. The enhanced surface SHG light can be useful for nonlinear silicon photonics, surface/interface characterization, and optical biosensing. PMID:25927787

  17. Plasmonically Enhanced Second-Harmonic Generation from Metallic/Organic Hybrid Self-Assembled Films

    Science.gov (United States)

    Chen, Kai; Durak, Cemil; Heflin, Randy; Robinson, Hans

    2007-03-01

    We have fabricated a new class of second order nonlinear optical materials by combining ionic self-assembled multilayer (ISAM) films with silver nanoparticle arrays in a non-centrosymmetric geometry. These hybrid films exhibit second-harmonic generation (SHG) efficiencies as much as 1600 times larger than unmodified, conventional ISAM films, which makes a three bilayer hybrid film perform at the same level as a micron thick, 700-1000 bilayer film. This was accomplished by using nanosphere lithography to deposit silver nanoparticles on the ISAM film, tuning the geometry of the particles to make their plasmonic resonances overlap the frequency of optical excitation. Even though the enhancement is already large, we suggest that further refinements of the techniques are expected to lead to additional enhancements of similar or larger magnitude.

  18. Plasmon-enhanced second-harmonic generation from ionic self-assembled multilayer films.

    Science.gov (United States)

    Chen, Kai; Durak, Cemil; Heflin, J R; Robinson, Hans D

    2007-02-01

    We have demonstrated large enhancements of the effective second-order nonlinear susceptibility (chi(2)) of ionic self-assembled multilayer (ISAM) films, causing a film with just 3 bilayers to be optically equivalent to a 700-1000 bilayer film. This was accomplished by using nanosphere lithography to deposit silver nanoparticles on the ISAM film, tuning the geometry of the particles to make their plasmonic resonances overlap the frequency of optical excitation. An enhancement in the efficiency of second harmonic generation (SHG) by as much as 1600 times was observed. Even though this is already a large value, we suggest that further refinements of the techniques are expected to lead to additional enhancements of similar or larger magnitude. PMID:17297986

  19. Bound electronic Kerr effect and self-focusing induced damage in second-harmonic-generation crystals

    Science.gov (United States)

    Li, Heping; Zhou, Feng; Zhang, Xuejun; Ji, Wei

    1997-02-01

    We present an investigation of third-order electronic nonlinearities in second-harmonic-generation (SHG) crystals using a picosecond 532 nm wavelength beam. The crystals studied include KTP, KTA, BBO, LBO and LiNbO 3. Using the Z-scan technique the nonlinear refractive indexes and two-photon absorption coefficients in the z-cut crystals are measured, as well as in KTP, BBO and LBO along the phase-matching angles for the SHG of 1064 nm radiation. The microscopic origin of the measured refractive nonlinearity can be understood in terms of bound electronic effects, and the theoretical predictions are in agreement with our measurements. Finally, we perform an experimental study on the self-focusing induced damage in these crystals by extending the Z-scan method. The measured damage threshold is inversely proportional to the nonlinear refractive index and the thickness of a crystal.

  20. 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.

  1. 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.

  2. Second harmonic generation in an asymmetric rectangular quantum well under hydrostatic pressure

    International Nuclear Information System (INIS)

    The effects of structure parameters and hydrostatic pressure on the electronic states and the second harmonic generation (SHG) susceptibility of asymmetric rectangular quantum well (ARQW) are studied. The asymmetry of the potential can be controlled by changing the structural parameters and this adjustable asymmetry is important for optimizing the SHG susceptibility. We have calculated analytically the electronic states in ARQW within the framework of the envelope function approach. Numerical results for Al xl Ga1-xl As/GaAs/Al xr Ga1-xr As quantum well are presented. The results obtained show that the hydrostatic pressure and the structure parameters of ARQW significantly influence the SHG susceptibility. This behavior in the SHG susceptibility gives a new degree of freedom in regions of interest for device applications

  3. Optical second harmonic generation phase measurement at interfaces of some organic layers with indium tin oxide

    International Nuclear Information System (INIS)

    Highlights: • SHG phase from the interfaces of ITO/CuPc and ITO/pentacene was observed. • Optical dispersion of the organic thin film was taken into account. • Phase shift from bare ITO was 140° for ITO/CuPc and 160° for ITO/pentacene. - Abstract: We observed phase shift in optical second harmonic generation (SHG) from interfaces of indium tin oxide (ITO)/copper phthalocyanine (CuPc) and ITO/pentacene. Phase correction due to Fresnel factors of the sample was taken into account. The phase of SHG electric field at the ITO/pentacene interface, ϕinterface with respect to the phase of SHG of bare substrate ITO was 160°, while the interface of ITO/CuPc had a phase of 140°

  4. 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.

  5. Optical Second Harmonic Generation in Plasmonic Nanostructures: From Fundamental Principles to Advanced Applications.

    Science.gov (United States)

    Butet, Jérémy; Brevet, Pierre-François; Martin, Olivier J F

    2015-11-24

    Plasmonics has emerged as an important research field in nanoscience and nanotechnology. Recently, significant attention has been devoted to the observation and the understanding of nonlinear optical processes in plasmonic nanostructures, giving rise to the new research field called nonlinear plasmonics. This review provides a comprehensive insight into the physical mechanisms of one of these nonlinear optical processes, namely, second harmonic generation (SHG), with an emphasis on the main differences with the linear response of plasmonic nanostructures. The main applications, ranging from the nonlinear optical characterization of nanostructure shapes to the optimization of laser beams at the nanoscale, are summarized and discussed. Future directions and developments, made possible by the unique combination of SHG surface sensitivity and field enhancements associated with surface plasmon resonances, are also addressed. PMID:26474346

  6. 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...

  7. Bulk quadrupole and interface dipole contribution for second harmonic generation in Si(111)

    International Nuclear Information System (INIS)

    The second harmonic generation (SHG) response was measured for arbitrarily oriented linear input polarization on Si(111) surfaces in rotational anisotropy experiments. We show for the first time, using the simplified bond hyperpolarizability model (SBHM), that the observed angular shifts of the nonlinear peaks and symmetry features—related to changes in the input polarization—help to identify the corresponding interface dipolar and bulk quadrupolar SHG sources, yielding excellent agreement with the experiment. Additionally, we evaluate for the s-in/p-out (sp) and p-in/p-out (pp)-polarization SHG intensities the contributions from the individual Si bonds. Furthermore, a relation between the four parameters arising from SBHM and six coefficients of the phenomenological SHG theory needed to reproduce experimental data is established. (paper)

  8. 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.

  9. Study of van Gieson's picrofuchsin staining on second-harmonic generation in type I collagen

    Institute of Scientific and Technical Information of China (English)

    Hanping Liu; Zhengfei Zhuang; Lingling Zhao; Junle Qu; Xiaoyuan Deng

    2008-01-01

    Second-harmonic generation (SHG) microscopy is a recently developed nonlinear optical imaging modality for imaging tissue structures with submicron resolution and is a potent tool for visualizing pathological effects of diseases. In this letter, we present our investigation on the influence of van Gieson's (VG) alcoholic picrofuchsin staining on SHG in type I collagen (from tendon-rich C57BL/6). Multi-channel imaging and spectra analysis show that the strong SHG signal produced in fresh collagen type I fiber has been greatly suppressed after VG staining, which indicates that staining may induce the structural or characteristic changes of SHG-dependent crystal formed by collagen constituents, such as glycine, proline, and hydroxyproline.

  10. 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.

  11. 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.

  12. Second Harmonic Generation in h-BN and MoS$_2$ monolayers: the role of electron-hole interaction

    OpenAIRE

    Grüning, M; Attaccalite, C.

    2013-01-01

    We study second-harmonic generation in h-BN and MoS$_2$ monolayers using a novel \\emph{ab initio} approach based on Many-body theory. We show that electron-hole interaction doubles the signal intensity at the excitonic resonances with respect to the contribution from independent electronic transitions. This implies that electron-hole interaction is essential to describe second-harmonic generation in those materials. We argue that this finding is general for nonlinear optical properties in nan...

  13. Phase-matched second-harmonic generation due to thermal expansion of TlGaSe2 layered crystal

    International Nuclear Information System (INIS)

    Second-harmonic generation effects have been investigated in TlGaSe2 layered crystal over a temperature range where ferroelectric phase exists. Pronounced periodical changes of the second-harmonic signal with temperature have been discovered. The observed effect is explained within the phase synchronism condition which changes with the temperature. The main mechanism of the thermal expansion of the sample in the observed phenomenon is explained. -- Highlights: ► Second-harmonic generation was investigated in TlGaSe2 layered crystal. ► Periodical changes of the SH signal with temperature are found for the first time. ► Conditions for temperature phase-matched SHG were proposed.

  14. Direct probing of contact electrification by using optical second harmonic generation technique

    Science.gov (United States)

    Chen, Xiangyu; Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa; Wang, Zhong Lin

    2015-08-01

    Contact electrification between two different materials is one of the oldest fields of study in solid-state physics. Here, we introduced an innovative system based on optical electric-field-induced second harmonic generation (EFI-SHG) technique that can directly monitor the dynamic performance of the contact electrification on the surface of polyimide film. After the contact, the EFI-SHG system visualized briefly three relaxations of the tribo-induced charges on the surface of a polyimide film, a fast relaxation within 3 min followed by two much slower relaxations, which were possibly related to different charge diffusion routes. The contact electrification under several special experimental conditions (wind, water and steam) was studied to demonstrate the high flexibility and material selectivity of the EFI-SHG. The EFI-SHG studies confirmed the motion of the water can remove the surface charge, while the appearance and the evaporation of a thin water layer cannot enhance the charge diffusion. We anticipate that this experimental technique will find a variety of applications in the field of contact electrification and the development of the recently invented triboelectric nano generator.

  15. A novel approach for assessing cardiac fibrosis using label-free second harmonic generation.

    Science.gov (United States)

    Martin, Tamara P; Norris, Greg; McConnell, Gail; Currie, Susan

    2013-12-01

    To determine whether second harmonic generation (SHG) can be used as a novel and improved label-free technique for detection of collagen deposition in the heart. To verify whether SHG will allow accurate quantification of altered collagen deposition in diseased hearts following hypertrophic remodelling. Minimally invasive transverse aortic banding (MTAB) of mouse hearts was used to generate a reproducible model of cardiac hypertrophy. Physiological and functional assessment of hypertrophic development was performed using echocardiography and post-mortem analysis of remodelled hearts. Cardiac fibroblasts were isolated from sham-operated and hypertrophied hearts and proliferation rates compared. Multi-photon laser scanning microscopy was used to capture both two-photon excited autofluorescence (TPEF) and SHG images simultaneously in two channels. TPEF images were subtracted from SHG images and the resulting signal intensities from ventricular tissue sections were calculated. Traditional picrosirius red staining was used to verify the suitability of the SHG application. MTAB surgery induced significant hypertrophic remodelling and increased cardiac fibroblast proliferation. A significant increase in the density of collagen fibres between hypertrophic and control tissues (p < 0.05) was evident using SHG. Similar increases and patterns of staining were observed using parallel traditional picrosirius red staining of collagen. Label-free SHG microscopy provides a new alternative method for quantifying collagen deposition in fibrotic hearts. PMID:23921804

  16. Frequency-comb formation in doubly resonant second-harmonic generation

    Science.gov (United States)

    Leo, F.; Hansson, T.; Ricciardi, I.; De Rosa, M.; Coen, S.; Wabnitz, S.; Erkintalo, M.

    2016-04-01

    We theoretically study the generation of optical frequency combs and corresponding pulse trains in doubly resonant intracavity second-harmonic generation (SHG). We find that, despite the large temporal walk-off characteristic of realistic cavity systems, the nonlinear dynamics can be accurately and efficiently modeled using a pair of coupled mean-field equations. Through rigorous stability analysis of the system's steady-state continuous-wave solutions, we demonstrate that walk-off can give rise to an unexplored regime of temporal modulation instability. Numerical simulations performed in this regime reveal rich dynamical behaviors, including the emergence of temporal patterns that correspond to coherent optical frequency combs. We also demonstrate that the two coupled equations that govern the doubly resonant cavity behavior can, under typical conditions, be reduced to a single mean-field equation akin to that describing the dynamics of singly-resonant-cavity SHG [F. Leo et al., Phys. Rev. Lett. 116, 033901 (2016), 10.1103/PhysRevLett.116.033901]. This reduced approach allows us to derive a simple expression for the modulation instability gain, thus permitting us to acquire significant insight into the underlying physics. We anticipate that our work will have a wide impact on the study of frequency combs in emerging doubly resonant cavity SHG platforms, including quadratically nonlinear microresonators.

  17. Efficient second-harmonic generation of continuous-wave Yb fiber lasers coupled with an external resonant cavity

    Science.gov (United States)

    Kim, J. W.; Jeong, J.; Lee, K.; Lee, S. B.

    2012-09-01

    Efficient second-harmonic generation of continuous-wave Yb fiber lasers is reported. A simple bow-tie external resonant cavity incorporating a type I LBO nonlinear optical crystal was employed for second harmonic frequency conversion of a multi-longitudinal-mode Yb fiber laser. It is shown that strong coupling was formed between the Yb fiber laser and the external cavity and, as a result, the laser produced 9.1 W of green output at 535 nm for 43 W of absorbed diode pump power at 975 nm corresponding to an optical conversion efficiency of 21 % with respect to absorbed diode pump power. The prospects for further improvement are discussed.

  18. Broadband Response of Second Harmonic Generation in a Two-Dimensional Quasi-Random Quasi-Phase-Matching Structure

    International Nuclear Information System (INIS)

    The broadband response of second harmonic generation (SHG) is experimentally observed in a two-dimensional (2D) quasi-random quasi-phase-matching (QPM) structure. A nonlinear conversion efficiency of more than 50% is obtained. Due to the line-type distribution of the reciprocal vector, the second harmonic wave (SHW) covering a broad frequency band is efficiently radiated in the shape of one single spot or three spots instead of a stripe. This is believed to be favorable for its practical application and paves the way for the use of ultrahigh-bandwidth light sources and devices in modern optical technologies. (fundamental areas of phenomenology(including applications))

  19. Three-dimensional mapping of single gold nanoparticles embedded in a homogeneous transparent matrix using optical second-harmonic generation.

    Science.gov (United States)

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

    2010-10-11

    We report the three-dimensional mapping of 150 nm gold metallic nanoparticles dispersed in a homogeneous transparent polyacrylamide matrix using second-harmonic generation. We demonstrate that the position of single nanoparticles can be well defined using only one incident fundamental beam and the harmonic photon detection performed at right angle. The fundamental laser beam properties are determined using its spatial autocorrelation function and used to prove that single nanoparticles are observed. Polarization resolved measurements are also performed allowing for a clear separation of the second-harmonic response of the single gold metallic nanoparticles from that of aggregates of such nanoparticles. PMID:20941132

  20. Interference between selected dipoles and octupoles in the optical second-harmonic generation from spherical gold nanoparticles.

    Science.gov (United States)

    Butet, J; Bachelier, G; Russier-Antoine, I; Jonin, C; Benichou, E; Brevet, P-F

    2010-08-13

    Optical second-harmonic generation from gold nanoparticles is investigated both experimentally and theoretically. The contribution of octupoles is reported for the first time in the second-harmonic emission pattern, by using an harmonic polarization in the scattering plane. The experimental results presented here for particle sizes up to 100 nm are in excellent agreement with finite element method simulations involving the normal surface term only in the nonlinear polarization source. In addition, analytical calculations based on nonlinear Mie scattering theory clearly evidence the constructive and destructive interferences occurring between the dipolar and octupolar responses selected with this polarization configuration. PMID:20868074

  1. VECSELs emitting at 976nm designed for second harmonic generation in the blue wavelength region

    Science.gov (United States)

    Muszalski, Jan; Broda, Artur; Jasik, Agata; Wójcik-Jedlińska, Anna; Trajnerowicz, Artur; Kubacka-Traczyk, Justyna; Sankowskaa, Iwona

    2013-01-01

    Using a Vertical Cavity Surface Emitting Laser (VECSEL) "as-grown" heterostructure we set-up a laser emitting at 488 nm with the output power approaching 20mW. The short wavelength emission was due to the conversion of the 976nm emission by a second harmonic generation process in a type-I lithum triborate (LBO). The V-type external cavity permitted efficient focusing of the laser beam on both the VECSEL heterostructure and the non linear crystal. A small diameter focused spot on the gain mirror is required when "as-grown" heterostructures are used. No birefringent filter was used in the resonator. In the case of our heterostructure we observed that the light was spontaneously polarized along the one of the crystallographic direction. The polarization ratio was 1000:1. The VECSEL heterostructure was of the resonant type strongly enhancing a single wavelength emission. The wavelength fine tuning was performed by heatsink temperature adjustment. The heterostructure was grown by molecular beam epitaxy. It consisted of 12 InGaAs quantum wells enclosed by GaAs barriers and a AlAs/GaAs DBR.

  2. The Interferometric Measurement of Phase Mismatch in Potential Second Harmonic Generators.

    Science.gov (United States)

    Sinofsky, Edward Lawrence

    This dissertation combines aspects of lasers, nonlinear optics and interferometry to measure the linear optical properties involved in phase matched second harmonic generation, (SHG). A new measuring technique has been developed to rapidly analyze the phase matching performance of potential SHGs. The data taken is in the form of interferograms produced by the self referencing nonlinear Fizeau interferometer (NLF), and correctly predicts when phase matched SHG will occur in the sample wedge. Data extracted from the interferograms produced by the NLF, allows us to predict both phase matching temperatures for noncritically phase matchable crystals and crystal orientation for angle tuned crystals. Phase matching measurements can be made for both Type I and Type II configurations. Phase mismatch measurements were made at the fundamental wavelength of 1.32 (mu)m, for: calcite, lithium niobate, and gadolinium molybdate (GMO). Similar measurements were made at 1.06 (mu)m. for calcite. Phase matched SHG was demonstrated in calcite, lithium niobate and KTP, while phase matching by temperature tuning is ruled out for GMO.

  3. 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.

  4. Second-harmonic generation scattering directionality predicts tumor cell motility in collagen gels

    Science.gov (United States)

    Burke, Kathleen A.; Dawes, Ryan P.; Cheema, Mehar K.; Van Hove, Amy; Benoit, Danielle S. W.; Perry, Seth W.; Brown, Edward

    2015-05-01

    Second-harmonic generation (SHG) allows for the analysis of tumor collagen structural changes throughout metastatic progression. SHG directionality, measured through the ratio of the forward-propagating to backward-propagating signal (F/B ratio), is affected by collagen fibril diameter, spacing, and disorder of fibril packing within a fiber. As tumors progress, these parameters evolve, producing concurrent changes in F/B. It has been recently shown that the F/B of highly metastatic invasive ductal carcinoma (IDC) breast tumors is significantly different from less metastatic tumors. This suggests a possible relationship between the microstructure of collagen, as measured by the F/B, and the ability of tumor cells to locomote through that collagen. Utilizing in vitro collagen gels of different F/B ratios, we explored the relationship between collagen microstructure and motility of tumor cells in a "clean" environment, free of the myriad cells, and signals found in in vivo. We found a significant relationship between F/B and the total distance traveled by the tumor cell, as well as both the average and maximum velocities of the cells. Consequently, one possible mechanism underlying the observed relationship between tumor F/B and metastatic output in IDC patient samples is a direct influence of collagen structure on tumor cell motility.

  5. Experimental intensity analysis of second harmonic generation at the Cu(110) surface

    Science.gov (United States)

    Schwab, C.; Meister, G.; Woll, J.; Gerlach, A.; Goldmann, A.

    2000-06-01

    We have analyzed second harmonic generation (SHG) intensities from Cu(110) at fundamental wavelengths λ=1064 nm and between λ=650 and 540 nm. Experimentally the light incidence direction was chosen along the two inequivalent mirror planes of the surface lattice unit cell, and the linear polarizations of both input (fundamental) and output (frequency-doubled) radiation could be varied independently. At λ=1064 nm the relative sizes of the different components of the second-order susceptibility tensor are as follows: | χ zzz|=2490, | χ yzy|=139 and | χ zyy|=33.7. The remaining elements are below detection threshold: | χ xzx|zzz, while again | χ zxx| and | χ xzx| are negligible. All available data, including temperature-dependent SHG studies of different authors, clearly show that contributions of electronic surface states to SHG intensities may be significant or even dominant. Therefore, a detailed quantitative understanding is a necessary condition for any analysis of adsorbate-induced SHG signals, since adsorbates can modify the surface electronic properties considerably. Our results furthermore indicate that the use of isotropic Fresnel coefficients to model the SHG-active electric fields is inadequate for a complete quantitative analysis.

  6. Nonlinear optical properties of type I collagen fibers studied by polarization dependent second harmonic generation microscopy.

    Science.gov (United States)

    Tuer, Adam E; Krouglov, Serguei; Prent, Nicole; Cisek, Richard; Sandkuijl, Daaf; Yasufuku, Kazuhiro; Wilson, Brian C; Barzda, Virginijus

    2011-11-10

    Collagen (type I) fibers are readily visualized with second harmonic generation (SHG) microscopy though the molecular origin of the signal has not yet been elucidated. In this study, the molecular origin of SHG from type I collagen is investigated using the time-dependent coupled perturbed Hartree-Fock calculations of the hyperpolarizibilities of glycine, proline, and hydroxyproline. Two effective nonlinear dipoles are found to orient in-the-plane of the amino acids, with one of the dipoles aligning close to the pitch orientation in the triple-helix, which provides the dominant contribution to the SHG polarization properties. The calculated hyperpolarizability tensor element ratios for the collagen triple-helix models: [(Gly3)n]3, [(Gly-Pro2)n]3, and [(Gly-Pro-Hyp)n]3, are used to predict the second-order nonlinear susceptibility ratios, χ(zzz)(2)/χ(iiz)(2) and χ(zii)(2)/χ(iiz)(2) of collagen fibers. From SHG microscopy polarization in, polarization out (PIPO) measurements of type I collagen in human lung tissue, a theoretical method is used to extract the triple-helix orientation angle with respect to the collagen fiber. The study shows the dominant role of amino acid orientation in the triple-helix for determining the polarization properties of SHG and provides a method for determining the triple-helix orientation angle in the collagen fibers. PMID:21970315

  7. Tumor tissue characterization using polarization-sensitive second harmonic generation microscopy

    Science.gov (United States)

    Tokarz, Danielle; Cisek, Richard; Golaraei, Ahmad; Krouglov, Serguei; Navab, Roya; Niu, Carolyn; Sakashita, Shingo; Yasufuku, Kazuhiro; Tsao, Ming-Sound; Asa, Sylvia L.; Barzda, Virginijus; Wilson, Brian C.

    2015-06-01

    Changes in the ultrastructure of collagen in various tumor and non-tumor human tissues including lung, pancreas and thyroid were investigated ex vivo by a polarization-sensitive second harmonic generation (SHG) microscopy technique referred to as polarization-in, polarization-out (PIPO) SHG. This involves measuring the orientation of the linear polarization of outgoing SHG as a function of the linear polarization orientation of incident laser radiation. From the PIPO SHG data, the second-order nonlinear optical susceptibility tensor component ratio, χ(2) ZZZ'/χ(2) ZXX', for each pixel of the SHG image was obtained and presented as color-coded maps. Further, the orientation of collagen fibers in the tissue was deduced. Since the χ(2) ZZZ'/χ(2) ZXX' values represent the organization of collagen in the tissue, theses maps revealed areas of altered collagen structure (not simply concentration) within tissue sections. Statistically-significant differences in χ(2) ZZZ'/χ(2) ZXX' were found between tumor and non-tumor tissues, which varied from organ to organ. Hence, PIPO SHG microscopy could potentially be used to aid pathologists in diagnosing cancer. Additionally, PIPO SHG microscopy could aid in characterizing the structure of collagen in other collagen-related biological processes such as wound repair.

  8. Crystalline phase responsible for the permanent second-harmonic generation in chalcogenide glass-ceramics

    Science.gov (United States)

    Guignard, Marie; Nazabal, Virginie; Zhang, Xiang-Hua; Smektala, Frédéric; Moréac, Alain; Pechev, Stanislas; Zeghlache, Hassina; Kudlinski, Alexandre; Martinelli, Gilbert; Quiquempois, Yves

    2007-10-01

    Permanent second-harmonic generation (SHG) has been demonstrated in chalcogenide based glass-ceramics containing non-linear micro-crystals with a size of a few micrometers. A glass composition from the Ge-Sb-S system was chosen as the reference glass for its stability against crystallization and atmospheric corrosion. Metallic cadmium was introduced in this matrix to promote crystallite formation resulting in infrared transparent glass-ceramics. A volume crystallization of β-GeS2 phase was obtained within the glass media by heating the glass samples at 370 °C for different durations. The glass-ceramics were then investigated by Raman spectroscopy, X-ray diffraction and NanoSIMS. The second-order non-linear signals were recorded by using Maker fringes experiment and were studied as a function of the crystallized volume fraction. The results indicated a non-linearity in chalcogenide glass-ceramics about one hundred times lower than α-quartz for a 1 mm thick sample heat treated 144 h.

  9. Fully automated muscle quality assessment by Gabor filtering of second harmonic generation images

    Science.gov (United States)

    Paesen, Rik; Smolders, Sophie; Vega, José Manolo de Hoyos; Eijnde, Bert O.; Hansen, Dominique; Ameloot, Marcel

    2016-02-01

    Although structural changes on the sarcomere level of skeletal muscle are known to occur due to various pathologies, rigorous studies of the reduced sarcomere quality remain scarce. This can possibly be explained by the lack of an objective tool for analyzing and comparing sarcomere images across biological conditions. Recent developments in second harmonic generation (SHG) microscopy and increasing insight into the interpretation of sarcomere SHG intensity profiles have made SHG microscopy a valuable tool to study microstructural properties of sarcomeres. Typically, sarcomere integrity is analyzed by fitting a set of manually selected, one-dimensional SHG intensity profiles with a supramolecular SHG model. To circumvent this tedious manual selection step, we developed a fully automated image analysis procedure to map the sarcomere disorder for the entire image at once. The algorithm relies on a single-frequency wavelet-based Gabor approach and includes a newly developed normalization procedure allowing for unambiguous data interpretation. The method was validated by showing the correlation between the sarcomere disorder, quantified by the M-band size obtained from manually selected profiles, and the normalized Gabor value ranging from 0 to 1 for decreasing disorder. Finally, to elucidate the applicability of our newly developed protocol, Gabor analysis was used to study the effect of experimental autoimmune encephalomyelitis on the sarcomere regularity. We believe that the technique developed in this work holds great promise for high-throughput, unbiased, and automated image analysis to study sarcomere integrity by SHG microscopy.

  10. 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.

  11. Estimating the helical pitch angle of amylopectin in starch using polarization second harmonic generation microscopy

    International Nuclear Information System (INIS)

    Starch granules are among the brightest natural second harmonic generation (SHG) converters. They basically consist of amylose and amylopectin molecules and the source of the SHG signal is still undetermined. In the present study we perform polarization sensitive SHG (PSHG) imaging of wheat starch granules and we fit the SHG signal variation of each pixel of the PSHG images into a generalized biophysical model. By assuming that the SHG source molecule is a helix with cylindrical symmetry along its long axis, the model extracts the helical pitch angle of the SHG source for every pixel of the image. By displaying the pixel histogram representing this helical pitch angle we found a highly peaked histogram with maximum at θe = 36.1° and a width of Δθe = 9.3°. This pitch angle corresponds to the strand of the parallel double helical structure, called amylopectin (as measured by a small angle x-ray scattering technique). This demonstrates amylopectin (and not amylose) as the source of SHG in starch. According to our knowledge, this is the first estimation of the amylopectin's pitch angle in starch using PSHG

  12. 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.

  13. Size dependent competition between second harmonic generation and two-photon luminescence observed in gold nanoparticles

    International Nuclear Information System (INIS)

    We investigate systematically the competition between the second harmonic generation (SHG) and two-photon-induced luminescence (TPL) that are simultaneously present in Au nanoparticles excited by using a femtosecond (fs) laser. For a large-sized (length ∼ 800 nm, diameter ∼ 200 nm) Au nanorod, the SHG appears to be much stronger than the TPL. However, the situation is completely reversed when the Au nanorod is fragmented into many Au nanoparticles by the fs laser. In sharp contrast, only the TPL is observed in small-sized (length ∼ 40 nm, diameter ∼ 10 nm) Au nanorods. When a number of the small-sized Au nanorods are optically trapped and fused into a large-sized Au cluster by focused fs laser light, the strong TPL is reduced while the weak SHG increases significantly. In both cases, the morphology change is characterized by scanning electron microscope. In addition, the modification of the scattering and absorption cross sections due to the morphology change is calculated by using the discrete dipole approximation method. It is revealed that SHG is dominant in the case when the scattering is much larger than the absorption. When the absorption becomes comparable to or larger than the scattering, the TPL increases dramatically and will eventually become dominant. Since the relative strengths of scattering and absorption depend strongly on the size of the Au nanoparticles, the competition between SHG and TPL is found to be size dependent. (paper)

  14. Estimating the helical pitch angle of amylopectin in starch using polarization second harmonic generation microscopy

    Science.gov (United States)

    Psilodimitrakopoulos, Sotiris; Amat-Roldan, Ivan; Loza-Alvarez, Pablo; Artigas, David

    2010-08-01

    Starch granules are among the brightest natural second harmonic generation (SHG) converters. They basically consist of amylose and amylopectin molecules and the source of the SHG signal is still undetermined. In the present study we perform polarization sensitive SHG (PSHG) imaging of wheat starch granules and we fit the SHG signal variation of each pixel of the PSHG images into a generalized biophysical model. By assuming that the SHG source molecule is a helix with cylindrical symmetry along its long axis, the model extracts the helical pitch angle of the SHG source for every pixel of the image. By displaying the pixel histogram representing this helical pitch angle we found a highly peaked histogram with maximum at θe = 36.1° and a width of Δθe = 9.3°. This pitch angle corresponds to the strand of the parallel double helical structure, called amylopectin (as measured by a small angle x-ray scattering technique). This demonstrates amylopectin (and not amylose) as the source of SHG in starch. According to our knowledge, this is the first estimation of the amylopectin's pitch angle in starch using PSHG.

  15. Probing ice-nucleation processes on the molecular level using second harmonic generation spectroscopy

    Directory of Open Access Journals (Sweden)

    A. Abdelmonem

    2015-05-01

    Full Text Available We present and characterize a novel setup to apply Second Harmonic Generation (SHG spectroscopy in total internal reflection geometry (TIR to heterogeneous freezing research. It allows to monitor the evolution of water structuring at solid surfaces at low temperatures prior to heterogeneous ice nucleation. Apart from the possibility of investigating temperature dependence, a major novelty in our setup is the ability of measuring sheet-like samples in TIR geometry in a direct way. As a main experimental result, we find that our method can discriminate between good and poor ice nucleating surfaces. While at the sapphire basal plane, which is known to be a poor ice nucleator, no structural rearrangement of the water molecules is found prior to freezing, the basal plane surface of mica, an analogue to ice active mineral dust surfaces, exhibits a strong change in the nonlinear optical properties at temperatures well above the freezing transition. This is interpreted as a pre-activation, i.e. an increase in the local ordering of the interfacial water which is expected to facilitate the crystallization of ice at the surface. The results are in line with recent predictions by Molecular Dynamics simulations on a similar system.

  16. Vector method for studying the second-harmonic-generation light derived from complex periodic ferroelectric domains

    Energy Technology Data Exchange (ETDEWEB)

    He Zhihong [MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, South China Normal University, Guangzhou 510631 (China); Yang Xiangbo, E-mail: xbyang@scnu.edu.c [MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, South China Normal University, Guangzhou 510631 (China); Wang Zhenyu [MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, South China Normal University, Guangzhou 510631 (China)

    2010-05-17

    In this Letter, in order to overcome the disadvantages of controlling the second-harmonic-generation (SHG) light derived from the traditional one-dimensional (1D) periodic ferroelectric domains we propose a kind of so-called complex periodic ferroelectric structure (CPFS), which unit cell is composed of even layers of positive and negative domains arranged alternatively following aperiodic sequence. It is found that comparing with the traditional periodic structure, CPFS cannot offer more reciprocal vector compensations for the mismatching phase, but CPFS may provide larger effective nonlinear coefficients (ENCs) in high-order quasi-phase-matching (QPM) and possesses advantages of the amplitude modulation for SHG peaks. In this Letter we study CPFS by use of vector method (VM), where the contribution to ENC for each domain or each unit cell will be treated as a vector and the QPM condition for CPFS and the modulation effect of aperiodic unit cells have been obtained. Without any Fourier transformation VM treats the grating function in real space and will be very convenient and intuitive. Both VM and CPFS would possess potential applications in the field of SHG investigations.

  17. Vector method for studying the second-harmonic-generation light derived from complex periodic ferroelectric domains

    International Nuclear Information System (INIS)

    In this Letter, in order to overcome the disadvantages of controlling the second-harmonic-generation (SHG) light derived from the traditional one-dimensional (1D) periodic ferroelectric domains we propose a kind of so-called complex periodic ferroelectric structure (CPFS), which unit cell is composed of even layers of positive and negative domains arranged alternatively following aperiodic sequence. It is found that comparing with the traditional periodic structure, CPFS cannot offer more reciprocal vector compensations for the mismatching phase, but CPFS may provide larger effective nonlinear coefficients (ENCs) in high-order quasi-phase-matching (QPM) and possesses advantages of the amplitude modulation for SHG peaks. In this Letter we study CPFS by use of vector method (VM), where the contribution to ENC for each domain or each unit cell will be treated as a vector and the QPM condition for CPFS and the modulation effect of aperiodic unit cells have been obtained. Without any Fourier transformation VM treats the grating function in real space and will be very convenient and intuitive. Both VM and CPFS would possess potential applications in the field of SHG investigations.

  18. Vector method for studying the second-harmonic-generation light derived from complex periodic ferroelectric domains

    Science.gov (United States)

    He, Zhihong; Yang, Xiangbo; Wang, Zhenyu

    2010-05-01

    In this Letter, in order to overcome the disadvantages of controlling the second-harmonic-generation (SHG) light derived from the traditional one-dimensional (1D) periodic ferroelectric domains we propose a kind of so-called complex periodic ferroelectric structure (CPFS), which unit cell is composed of even layers of positive and negative domains arranged alternatively following aperiodic sequence. It is found that comparing with the traditional periodic structure, CPFS cannot offer more reciprocal vector compensations for the mismatching phase, but CPFS may provide larger effective nonlinear coefficients (ENCs) in high-order quasi-phase-matching (QPM) and possesses advantages of the amplitude modulation for SHG peaks. In this Letter we study CPFS by use of vector method (VM), where the contribution to ENC for each domain or each unit cell will be treated as a vector and the QPM condition for CPFS and the modulation effect of aperiodic unit cells have been obtained. Without any Fourier transformation VM treats the grating function in real space and will be very convenient and intuitive. Both VM and CPFS would possess potential applications in the field of SHG investigations.

  19. 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.

  20. Detecting subtle plasma membrane perturbation in living cells using second harmonic generation imaging.

    Science.gov (United States)

    Moen, Erick K; Ibey, Bennett L; Beier, Hope T

    2014-05-20

    The requirement of center asymmetry for the creation of second harmonic generation (SHG) signals makes it an attractive technique for visualizing changes in interfacial layers such as the plasma membrane of biological cells. In this article, we explore the use of lipophilic SHG probes to detect minute perturbations in the plasma membrane. Three candidate probes, Di-4-ANEPPDHQ (Di-4), FM4-64, and all-trans-retinol, were evaluated for SHG effectiveness in Jurkat cells. Di-4 proved superior with both strong SHG signal and limited bleaching artifacts. To test whether rapid changes in membrane symmetry could be detected using SHG, we exposed cells to nanosecond-pulsed electric fields, which are believed to cause formation of nanopores in the plasma membrane. Upon nanosecond-pulsed electric fields exposure, we observed an instantaneous drop of ~50% in SHG signal from the anodic pole of the cell. When compared to the simultaneously acquired fluorescence signals, it appears that the signal change was not due to the probe diffusing out of the membrane or changes in membrane potential or fluidity. We hypothesize that this loss in SHG signal is due to disruption in the interfacial nature of the membrane. The results show that SHG imaging has great potential as a tool for measuring rapid and subtle plasma membrane disturbance in living cells. PMID:24853757

  1. The origin of inhibition of high power second harmonic generation in periodically poled lithium niobate crystal

    International Nuclear Information System (INIS)

    This paper investigates the origin of the inhibition of the second harmonic generation (SHG) in a periodically poled lithium niobate (PPLN) crystal by using coupled-mode equations in which both absorption and photorefractive properties of the crystal were taken into account. SHG, using fundamental laser beams with radii of 150, 33, and 25 μm, respectively, were calculated. The calculated results showed that the changes of refractive index difference resulting from the photorefractive effect were ∼300 times smaller than that from absorption-induced heating in SHG using a fundamental laser beam with a radius of 150 μm. However, in SHG using a fundamental laser beam with a radius smaller than 33 μm, the changes of refractive index difference resulting from the photorefractive effect were comparable to those resulting from absorption-induced heating. It revealed that the photorefractive effect is one of the main factors that inhibits the SHG using a fundamental laser beam with a radius smaller than 33 μm at high pump powers. (paper)

  2. The Impact of Collagen Fibril Polarity on Second Harmonic Generation Microscopy.

    Science.gov (United States)

    Couture, Charles-André; Bancelin, Stéphane; Van der Kolk, Jarno; Popov, Konstantin; Rivard, Maxime; Légaré, Katherine; Martel, Gabrielle; Richard, Hélène; Brown, Cameron; Laverty, Sheila; Ramunno, Lora; Légaré, François

    2015-12-15

    In this work, we report the implementation of interferometric second harmonic generation (SHG) microscopy with femtosecond pulses. As a proof of concept, we imaged the phase distribution of SHG signal from the complex collagen architecture of juvenile equine growth cartilage. The results are analyzed in respect to numerical simulations to extract the relative orientation of collagen fibrils within the tissue. Our results reveal large domains of constant phase together with regions of quasi-random phase, which are correlated to respectively high- and low-intensity regions in the standard SHG images. A comparison with polarization-resolved SHG highlights the crucial role of relative fibril polarity in determining the SHG signal intensity. Indeed, it appears that even a well-organized noncentrosymmetric structure emits low SHG signal intensity if it has no predominant local polarity. This work illustrates how the complex architecture of noncentrosymmetric scatterers at the nanoscale governs the coherent building of SHG signal within the focal volume and is a key advance toward a complete understanding of the structural origin of SHG signals from tissues. PMID:26682809

  3. First-principles calculation of the second-harmonic-generation coefficients of borate crystals

    Science.gov (United States)

    Duan, Chun-Gang; Li, Jun; Gu, Zong-Quan; Wang, Ding-Sheng

    1999-10-01

    We report the calculation of the second-harmonic-generation (SHG) coefficients of LiB3O5 (LBO), CsB3O5 (CBO), and BaB2O4 (BBO) using the linearized augmented plane-wave band method in the local-density approximation with a scissors operator that includes the renormalization of the momentum operator. The analysis that is based on the spectral and spatial decomposition of the calculated results reveals that, for the large component of SHG coefficients, the dominant source of the optical nonlinearities for these borate crystals is the nonlinear response of the high-lying 2p electrons of oxygen atoms, while the cations play a minor role even in the heavier Cs and Ba cases, though they dominate the conduction-band minimum. But for the small SHG component, the role of the cation became important, particularly when the isolated anionic group has little contribution due to the restriction of the symmetry. In the case of LBO and CBO, due to the linkage of anionic groups, the contributions of off-ring O atoms are almost the same as those of in-ring O atoms. Yet for BBO where there is no such linkage, the off-ring O atom plays a much more important role than the in-ring O atom does. We also find that the contribution of the virtual-hole process cannot be ignored as is usually done in the semiconductors case.

  4. Fluorescent DNA probes at liquid/liquid interfaces studied by surface second harmonic generation.

    Science.gov (United States)

    Licari, Giuseppe; Brevet, Pierre-François; Vauthey, Eric

    2016-01-28

    The properties of a series of oxazole yellow dyes, including the dicationic YOPRO-1 and its homodimeric parent YOYO-1 and two monocationic dyes (YOSAC-1 and YOSAC-3), have been investigated at the dodecane/water interface using stationary and time-resolved surface second harmonic generation (SSHG) combined with quantum chemical calculations. Whereas YOYO-1 exists predominantly as a H-dimer in aqueous solution, the stationary SSHG spectra reveal that such dimers are not formed at the interface. No significant H-aggregation was observed with YOPRO-1, neither in solution nor at the interface. In the case of the monocationic YOSAC dyes, a distinct SSHG band due to H-aggregates was measured at the interface, whereas only weak aggregation was found in solution. These distinct aggregation behaviors can be explained by the different orientations of the dyes at the interface, as revealed from the analysis of polarization-resolved experiments, the doubly-charged dyes lying more flat on the interface than the singly charged ones. Although YOYO-1 and YOPRO-1 do not form H-dimer/aggregates at the interface, time-resolved SSHG measurements point to the occurrence of intra- and intermolecular interactions, respectively, which inhibit the ultrafast non-radiative decay of the excited dyes via large amplitude motion, and lead to a nanosecond excited-state lifetime. The distinct behavior evidenced here for YOYO-1 and YOSAC dyes points to their potential use as fluorescent or SHG interfacial probes. PMID:26740332

  5. Broadband quasi-phase-matched second-harmonic generation in MgO: LiNbO3 waveguide

    Institute of Scientific and Technical Information of China (English)

    LIU Gui-hua; GUO Hai-run; FU Xing-hu; ZENG Xiang-long

    2011-01-01

    The quasi-phase-matched (QPM) condition of broadband second harmonic generation (SHG) in Ti-diffused MgO:LiNbOwaveguide is theoretically simulated. The results show that the center wavelength of broadband SHG dependent on the waveguide width is around 1550 nm and the bandwidth is 50 nm.

  6. 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.

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

    International Nuclear Information System (INIS)

    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

  8. Efficient broadband second-harmonic generation by dispersive achromatic nonlinear conversion using only prisms

    Energy Technology Data Exchange (ETDEWEB)

    Richman, B.A.; Bisson, S.E.; Trebino, R.

    1997-12-01

    Using a lossless dispersive apparatus consisting of six prisms, optimized to match a second-harmonic crystal phase-matching angle vs. wavelength to second order, we efficiently doubled tunable fundamental light near 660 nm over a range of 80 nm using a 4-mm-long type-I {beta}-Barium Borate (BBO) crystal. Another lossless set of six prisms after the crystal realigned the propagation directions of the various second-harmonic frequencies to be collinear to within 1/4 spot diameter in position and 200 {mu}rad in angle. The measured conversion efficiency of a 40-mJ, 5-ns fundamental pulse was 10%.

  9. Pattern formation in singly resonant second-harmonic generation with competing parametric oscillation

    DEFF Research Database (Denmark)

    Lodahl, P.; Saffman, M.

    1999-01-01

    fundamental field, and its coupling to a pair of nondegenerate parametric fields. The parametric fields are driven by the nonresonant second-harmonic field. Analysis indicates the existence of transverse instability of the pump field alone, as well as the possibility of simultaneous instability of the pump...

  10. 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

    We demonstrate the nonlinear optical activity of large Na and K clusters, grown on Au metal film-supported alkane thiol monolayers of different chain lengths. Both the total optical second-harmonic signal intensity as well as its dependence on the angle of incidence depend on the surface coverage...

  11. 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.

  12. 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

  13. Myosin rods are a source of second harmonic generation signals in skeletal muscle

    Science.gov (United States)

    Schürmann, Sebastian; Weber, Cornelia; Fink, Rainer H. A.; Vogel, Martin

    2007-02-01

    Intrinsic second harmonic generation (SHG) signals can be used to visualize the three-dimensional structure of cardiac and skeletal muscle with high spatial resolution. Fluorescence labeling of complementary sarcomeric proteins, e.g. actin, indicates that the observed SHG signals arise from the myosin filaments. Recently, the myosin rod domain or LMM - light meromyosin - has been reported to be the dominant source of this SHG signal. However, to date, mostly negative and indirect evidence has been presented to support this assumption. Here, we show, to our knowledge, the first direct evidences that strong SHG signals can be obtained from synthetic paracrystals. These rod shaped filaments are formed from purified LMM. SDS-PAGE protein analysis confirmed that the LMM crystals lack myosin head domains. Some regions of the LMM paracrystals produce a strong SHG signal whereas others did not. The SHG signals were recorded with a laser-scanning microscope (Leica SP2). A ps laser tuned to 880 nm was used to excite the sample through an 63x objective of 1.2 NA. In order to visualize the synthetic filaments - in addition to SHG imaging -, the LMM was labeled with the fluorescent marker 5-IAF. We were able to observe filaments of 1 to 50 μm in length and of up to 5 μm in diameter. In conclusion, we can show that the myosin rod domain (LMM) is a dominant source for intrinsic SHG signals. There seems, however, a signal dependence on the paracrystals' morphology. This dependence is being investigated.

  14. Alterations of the extracellular matrix in ovarian cancer studied by Second Harmonic Generation imaging microscopy

    Directory of Open Access Journals (Sweden)

    Campagnola Paul J

    2010-03-01

    Full Text Available Abstract Background Remodeling of the extracellular matrix (ECM has been implicated in ovarian cancer, and we hypothesize that these alterations may provide a better optical marker of early disease than currently available imaging/screening methods and that understanding their physical manifestations will provide insight into invasion. Methods For this investigation we use Second Harmonic Generation (SHG imaging microcopy to study changes in the structure of the ovarian ECM in human normal and malignant ex vivo biopsies. This method directly visualizes the type I collagen in the ECM and provides quantitative metrics of the fibrillar assembly. To quantify these changes in collagen morphology we utilized an integrated approach combining 3D SHG imaging measurements and bulk optical parameter measurements in conjunction with Monte Carlo simulations of the experimental data to extract tissue structural properties. Results We find the SHG emission attributes (directionality and relative intensity and bulk optical parameters, both of which are related to the tissue structure, are significantly different in the tumors in a manner that is consistent with the change in collagen assembly. The normal and malignant tissues have highly different collagen fiber assemblies, where collectively, our findings show that the malignant ovaries are characterized by lower cell density, denser collagen, as well as higher regularity at both the fibril and fiber levels. This further suggests that the assembly in cancer may be comprised of newly synthesized collagen as opposed to modification of existing collagen. Conclusions Due to the large structural changes in tissue assembly and the SHG sensitivity to these collagen alterations, quantitative discrimination is achieved using small patient data sets. Ultimately these measurements may be developed as intrinsic biomarkers for use in clinical applications.

  15. Second harmonic optical coherence tomography

    CERN Document Server

    Jiang, Y; Wang, Y; Chen, Z; Jiang, Yi; Tomov, Ivan; Wang, Yimin; Chen, Zhongping

    2004-01-01

    Second harmonic optical coherence tomography, which uses coherence gating of second-order nonlinear optical response 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 offers contrast and resolution enhancement to conventional optical coherence tomography.

  16. Precise, motion-free polarization control in Second Harmonic Generation microscopy using a liquid crystal modulator in the infinity space

    OpenAIRE

    Lien, Chi-Hsiang; Tilbury, Karissa; Chen, Shean-Jen; Campagnola, Paul J.

    2013-01-01

    Second Harmonic Generation (SHG) microscopy coupled with polarization analysis has great potential for use in tissue characterization, as molecular and supramolecular structural details can be extracted. Such measurements are difficult to perform quickly and accurately. Here we present a new method that uses a liquid crystal modulator (LCM) located in the infinity space of a SHG laser scanning microscope that allows the generation of any desired linear or circular polarization state. As the d...

  17. 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.

  18. Efficient broadband second-harmonic generation by dispersive achromatic nonlinear conversion using only prisms

    International Nuclear Information System (INIS)

    Using a lossless dispersive apparatus consisting of six prisms, optimized to match a second-harmonic crystal phase-matching angle versus wavelength to second order, we efficiently doubled tunable fundamental light near 660nm over a range of 80nm, using a 4-mm-long type I β-barium borate crystal without tuning the crystal angle. Another set of six prisms after the crystal realigned the propagation directions of the various second-harmonic frequencies to be collinear to within 1/4 spot diameter in position and 200 μrad in angle. The measured conversion efficiency of a 40-mJ, 5-ns fundamental pulse was 10%. copyright 1998 Optical Society of America

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

    OpenAIRE

    Popov, A. K.; Nefedov, I.S.; 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 c...

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

    International Nuclear Information System (INIS)

    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 KTiOPO4 (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/cm2. For higher power operation, we employed a two-pass quadrature scheme with CsLiB6O10 (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/cm2 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)

  1. 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)

  2. Quasi-phase-matching and second-harmonic generation enhancement in a semiconductor microresonator array using slow-light effects

    International Nuclear Information System (INIS)

    We theoretically analyze the second-harmonic generation process in a sequence of unidirectionnaly coupled doubly resonant whispering gallery mode semiconductor resonators. By using a convenient design, it is possible to coherently sum the second-harmonic fields generated inside each resonator. We show that resonator coupling allows the bandwidth of the phase-matching curve to be increased with respect to single-resonator configurations simultaneously taking advantage of the resonant feature of the resonators. This quasi-phase-matching technique could be applied to obtain small-footprint nonlinear devices with large bandwidth and limited nonlinear losses. The results are discussed in the framework of the slow-light-effect enhancement of second-order optical nonlinearities.

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

    International Nuclear Information System (INIS)

    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 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.

  4. Large scale micro-structured optical second harmonic generation response imprinted on glass surface by thermal poling

    Science.gov (United States)

    Yang, G.; Dussauze, M.; Rodriguez, V.; Adamietz, F.; Marquestaut, N.; Deepak, K. L. N.; Grojo, D.; Uteza, O.; Delaporte, P.; Cardinal, T.; Fargin, E.

    2015-07-01

    Micro-structured second harmonic generation responses have been achieved on borophosphate niobium glasses by thermal poling using micro-patterned silicon substrates. The poling imprinting process has created sub-micrometer sized patterns of both surface relief and second order optical responses on the anode glass surface. Field enhancement effects within the micro structured electrode are believed to govern the charge density on the glass surface during the process and thus amplitudes of both implemented electric field and Maxwell stresses.

  5. Efficient second-harmonic generation of a broadband radiation by control of the temperature distribution along a nonlinear crystal.

    Science.gov (United States)

    Regelskis, K; Želudevičius, J; Gavrilin, N; Račiukaitis, G

    2012-12-17

    We demonstrate an efficient technique for the second harmonic generation (SHG) of the broadband radiation based on the temperature gradient along a nonlinear crystal. The characteristics of Type I non-critical phase-matched SHG of broadband radiation in the LiB(3)O(5) (LBO) crystal with the temperature gradient imposed along the crystal were investigated both numerically and experimentally. The frequency doubling efficiency of the broadband pulsed fiber laser radiation as high as 68% has been demonstrated. PMID:23263092

  6. Comparison of reflectance confocal microscopy and two-photon second harmonic generation microscopy in fungal keratitis rabbit model ex vivo

    OpenAIRE

    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 keratiti...

  7. 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.

  8. Second harmonic generation microscopy investigation of the crystalline ultrastructure of three barley starch lines affected by hydration

    OpenAIRE

    Cicek, Richard; Tokarz, Danielle; Steup, Martin; Tetlow, Ian J.; Emes, Michael J.; Hebelstrup, Kim H.; Blennow, Andreas; Barzda, Virginijus

    2015-01-01

    Second harmonic generation (SHG) microscopy is employed to study changes in crystalline organization due to altered gene expression and hydration in barley starch granules. SHG intensity and susceptibility ratio values (R’SHG) are obtained using reduced Stokes-Mueller polarimetric microscopy. The maximum R’SHG values occur at moderate moisture indicating the narrowest orientation distribution of nonlinear dipoles from the cylindrical axis of glucan helices. The maximum SHG i...

  9. Large-angle magnetization dynamics investigated by vector-resolved magnetization-induced optical second-harmonic generation

    OpenAIRE

    Gerrits, T.; Silva, T. J.; Nibarger, J. P.; Rasing, T.H.M.

    2004-01-01

    We examine the relationship between nonlinear magnetic responses and the change in the Gilbert damping parameter alpha for patterned and unpatterned thin Permalloy films when subjected to pulsed magnetic fields. An improved magnetization-vector-resolved technique utilizing magnetization-induced optical second-harmonic generation was used to measure magnetization dynamics after pulsed-field excitation. The magnetization excitations were achieved with pulsed fields aligned parallel to the hard ...

  10. Polynomial Lie algebra methods in solving the second-harmonic generation model: some exact and approximate calculations

    OpenAIRE

    Karassiov, V. P.; A. A. Gusev; Vinitsky, S. I.

    2001-01-01

    We compare exact and SU(2)-cluster approximate calculation schemes to determine dynamics of the second-harmonic generation model using its reformulation in terms of a polynomial Lie algebra $su_{pd}(2)$ and related spectral representations of the model evolution operator realized in algorithmic forms. It enabled us to implement computer experiments exhibiting a satisfactory accuracy of the cluster approximations in a large range of characteristic model parameters.

  11. Second harmonic generation response by gold nanoparticles at the polarized water/2-octanone interface: from dispersed to aggregated particles

    Energy Technology Data Exchange (ETDEWEB)

    Galletto, P [Laboratoire d' Electrochimie Physique et Analytique, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland); Girault, H H [Laboratoire d' Electrochimie Physique et Analytique, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland); Gomis-Bas, C [Centre for Nanoscale Science, Department of Chemistry, University of Liverpool, Liverpool L69 3BX (United Kingdom); Schiffrin, D J [Centre for Nanoscale Science, Department of Chemistry, University of Liverpool, Liverpool L69 3BX (United Kingdom); Antoine, R [Universite Lyon 1, Laboratoire de Spectrometrie Ionique et Moleculaire, UMR CNRS 5579, 43 boulevard du 11 Novembre 1918, F-69622 Villeurbanne Cedex (France); Broyer, M [Universite Lyon 1, Laboratoire de Spectrometrie Ionique et Moleculaire, UMR CNRS 5579, 43 boulevard du 11 Novembre 1918, F-69622 Villeurbanne Cedex (France); Brevet, P F [Universite Lyon 1, Laboratoire de Spectrometrie Ionique et Moleculaire, UMR CNRS 5579, 43 boulevard du 11 Novembre 1918, F-69622 Villeurbanne Cedex (France)

    2007-09-19

    Gold nanoparticles with a diameter of approximately 20 nm have been observed at the polarized water/2-octanone interface by the nonlinear optical technique of second harmonic generation. Electric field induced adsorption of the gold particles at this liquid/liquid interface is clearly observed and confirms that these are negatively charged. The process is quasi-reversible at high potential sweep rates, but aggregation at the interface is observed at slower sweep rates through the loss of the nonlinear optical signal. The time evolution of the second harmonic signal is also reported during potential step experiments. After a rapid increase due to adsorption, a continuous decrease in the nonlinear optical signal intensity is observed due to aggregation of the particles into large islands at the interface. Diffusion of these large islands at the interface was observed for a longer timescale through large signal fluctuations.

  12. 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.

  13. 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.

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

    International Nuclear Information System (INIS)

    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

  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. PMID:18319927

  16. Second harmonic generation of off axial vortex beam in the case of walk-off effect

    Science.gov (United States)

    Chen, Shunyi; Ding, Panfeng; Pu, Jixiong

    2016-07-01

    Process of off axial vortex beam propagating in negative uniaxial crystal is investigated in this work. Firstly, we get the formulae of the normalized electric field and calculate the location of vortices for second harmonic beam in two type of phase matching. Then, numerical analysis verifies that the intensity distribution and location of vortices of the first order original vortex beam depend on the walk-off angle and off axial magnitude. It is shown that, in type I phase matching, the distribution of vortices is symmetrical about the horizontal axis, the separation distance increases as the off axial magnitude increases or the off axial magnitude deceases. However, in type II phase matching, the vortices are symmetrical along with some vertical axis, and increase of the walk-off angle or off axial magnitude leads to larger separation distance. Finally, the case of high order original off axial vortex beam is also investigated.

  17. 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

  18. In pixel analysis of molecular structure with Stokes vector resolved second harmonic generation microscopy

    Science.gov (United States)

    Mazumder, Nirmal; Xiang, Lu Yun; Qiu, Jianjun; Kao, Fu-Jen

    2014-02-01

    We report on measurements and characterization of polarization properties of Second Harmonic (SH) signals using a four-channel photon counting based Stokes polarimeter from type I collagen and starch granules. In this way, the critical polarization parameters including the degree of polarization (DOP), the degree of linear polarization (DOLP), and the degree of circular polarization (DOCP), are extracted from the reconstructed Stokes vector based SH images in a pixel-by-pixel manner. The measurements are further extended to determine the molecular structure and orientation of the samples by varying the polarization states of the incident light and recording the resulting Stokes parameters of the SH signal. The combination of SHG microscopy and Stokes polarimeter hence makes a powerful tool to investigate the structural order of starch granules under water and heating environment.

  19. Nonlinear generalized source method for modeling second-harmonic generation in diffraction gratings

    CERN Document Server

    Weismann, Martin; Panoiu, Nicolae C

    2015-01-01

    We introduce a versatile numerical method for modeling light diffraction in periodically patterned photonic structures containing quadratically nonlinear non-centrosymmetric optical materials. Our approach extends the generalized source method to nonlinear optical interactions by incorporating the contribution of nonlinear polarization sources to the diffracted field in the algorithm. We derive the mathematical formalism underlying the numerical method and introduce the Fourier-factorization suitable for nonlinear calculations. The numerical efficiency and runtime characteristics of the method are investigated in a set of benchmark calculations: the results corresponding to the fundamental frequency are compared to those obtained from a reference method and the beneficial effects of the modified Fourier-factorization rule on the accuracy of the nonlinear computations is demonstrated. In order to illustrate the capabilities of our method, we employ it to demonstrate strong enhancement of second-harmonic genera...

  20. Diode-pumped efficient slab laser with two Nd:YLF crystals and second-harmonic generation by slab LBO.

    Science.gov (United States)

    Li, Daijun; Ma, Zhe; Haas, Rüdiger; Schell, Alexander; Simon, Janosch; Diart, Robert; Shi, Peng; Hu, Peixin; Loosen, Peter; Du, Keming

    2007-05-15

    We demonstrate a diode-pumped electro-optical Q-switched slab laser with a high optical efficiency, high pulse energy, and short pulse width with two Nd:YLF crystals inside one resonator. The single compact slab resonator can generate a 1D top-hat beam at both the far field and the near field. With a slab-geometry-design lithium triborate (LBO) crystal, efficient critical phase-matching second-harmonic generation for a 1D top-hat beam with multiple transverse modes is achieved. PMID:17440558

  1. Dispersion of the second harmonic generation from CdGa2X4 (X = S, Se) defect chalcopyrite: DFT calculations

    International Nuclear Information System (INIS)

    Highlights: • Nonlinear optical properties of CdGa2X4 (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. • CdGa2Se4 posses huge second harmonic generation. - Abstract: All electron full potential linear augmented plane wave method was used for calculating the nonlinear optical susceptibilities of CdGa2X4 (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 CdGa2S4 and CdGa2Se4 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 |χijk(2)(ω)| and microscopic first hyperpolarizability βijk(ω) were calculated. The calculated |χ123(2)(ω)| and |χ312(2)(ω)| static values for the dominant components found to be 18.36 pm/V and 22.23 pm/V for CdGa2S4 and CdGa2Se4. Both values shifted to be 60.12 pm/V and 108.86 pm/V at λ = 1064 nm. The calculated values of β123(ω) is 6.47 × 10−30 esu at static limit and 12.42 × 10−30 esu at λ = 1064 nm for CdGa2S4, whereas it is 8.82 × 10−30 esu at static limit and 20.51 × 10−30 esu at λ = 1064 nm for CdGa2Se4. The evaluation of second order susceptibilities and first hyperpolarizabilties suggest that CdGa2X4 possess huge second harmonic generation

  2. 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.

  3. Theoretical study on the Cerenkov-type second-harmonic generation in optical superlattices without paraxial approximation.

    Science.gov (United States)

    Yue, Yang-Yang; Xiao, Han; Yang, Bo; Lu, Rong-Er; Hong, Xu-Hao; Zhang, Chao; Qin, Yi-Qiang; Zhu, Yong-Yuan

    2016-05-30

    In this paper, the Cerenkov-type second-harmonic generation in bulk optical superlattices has been studied theoretically with the non-paraxial wave equations, where the paraxial approximation is avoided. The corresponding phase-matching condition is determined strictly by solving the non-paraxial wave equations under proper boundary conditions, and the result coincides well with the traditional Cerenkov phase-matching condition. In addition, a backward Cerenkov phase-matching condition is deduced from the wave equations as well, and the physical requirement of this condition is clarified. PMID:27410081

  4. 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; Molina, Pablo; Carvajal, Joan J.; Aguiló, Magdalena; Díaz, Francesc; Aizpurua, Javier; Bausá, Luisa E.

    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...... 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 the...

  5. 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.

  6. Nonlinear optical method for the investigation of spectral properties of biomolecular complexes: second harmonic generation in ordered structures of bacteriorhodopsin

    Science.gov (United States)

    Aktsipetrov, Oleg A.; Fedyanin, Andrew A.; Murzina, Tatyana V.; Borisevich, G. P.; Kononenko, A. A.

    1995-02-01

    For the first time the method of the second harmonic generation was used to study the photo- and electrically induced nonlinear optical transformations in thin oriented films of purple membranes (PM). Variations of the film nonlinear susceptibility were investigated as the bacteriorhodopsin (bR) molecule underwent the cycle of photoinduced transformations for both dry electrically oriented films and bR molecules embedded into poly(vinyl alcohol) matrix. The electrically induced changes of the nonlinear optical properties were studied for the electrostatic field strength up to the values 4 (DOT) 104 V/cm. Nonlinear susceptibilities of oriented and nonoriented dried PM films are compared.

  7. 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). PMID:15119415

  8. Second harmonic generation microscopy investigation of the crystalline ultrastructure of three barley starch lines affected by hydration

    DEFF Research Database (Denmark)

    Cicek, Richard; Tokarz, Danielle; Steup, Martin;

    2015-01-01

    maximum R’SHG values occur at moderate moisture indicating the narrowest orientation distribution of nonlinear dipoles from the cylindrical axis of glucan helices. The maximum SHG intensity occurs at the highest moisture and amylopectin content. These results support the hypothesis that SHG is caused by......Second harmonic generation (SHG) microscopy is employed to study changes in crystalline organization due to altered gene expression and hydration in barley starch granules. SHG intensity and susceptibility ratio values (R’SHG) are obtained using reduced Stokes-Mueller polarimetric microscopy. The...

  9. 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.

  10. Revealing molecular structure and orientation with Stokes vector resolved second harmonic generation microscopy.

    Science.gov (United States)

    Mazumder, Nirmal; Hu, Chih-Wei; Qiu, Jianjun; Foreman, Matthew R; Romero, Carlos Macías; Török, Peter; Kao, Fu-Jen

    2014-03-15

    We report on measurements and characterization of polarization properties of Second Harmonic (SH) signals using a four-channel photon counting based Stokes polarimeter. In this way, the critical polarization parameters can be obtained concurrently without the need of repeated image acquisition. The critical polarization parameters, including the degree of polarization (DOP), the degree of linear polarization (DOLP), and the degree of circular polarization (DOCP), are extracted from the reconstructed Stokes vector based SH images in a pixel-by-pixel manner. The measurements are further extended by varying the polarization states of the incident light and recording the resulting Stokes parameters of the SH signal. In turn this allows the molecular structure and orientation of the samples to be determined. Use of Stokes polarimetry is critical in determination of the full polarization state of light, and enables discrimination of material properties not possible with conventional crossed-polarized detection schemes. The combination of SHG microscopy and Stokes polarimeter hence makes a powerful tool to investigate the structural order of targeted specimens. PMID:23891802

  11. Second harmonic generation from small gold metallic particles: from the dipolar to the quadrupolar response.

    Science.gov (United States)

    Nappa, J; Russier-Antoine, I; Benichou, E; Jonin, Ch; Brevet, P F

    2006-11-14

    Hyper Raleigh scattering, a common technique to investigate the second harmonic light scattered from a liquid suspension of molecular compounds and to determine their quadratic hyperpolarizability, has been used for aqueous suspensions of gold nanoparticles, the diameter of which ranges from 20 up to 150 nm. The hyper Rayleigh signal intensity was recorded as a function of the angle of polarization of the incident fundamental wave. For the particles with a diameter smaller than 50 nm, the response is dominated by the dipolar contribution arising from the deviation of the particle shape from that of a perfect sphere. For larger diameter particles, retardation effects in the interaction of the electromagnetic fields with the particles cannot be neglected any longer and the response deviates from the pure dipolar response, exhibiting a strong quadrupolar contribution. It is then shown that in order to quantify the relative magnitude of these two dipolar and quadrupolar contributions, a weighting parameter zeta(V) which equals unity for a pure quadrupolar contribution and vanishes for a pure dipolar response, can be introduced. PMID:17115784

  12. Walk-off-induced modulation instability, temporal pattern formation, and frequency comb generation in cavity-enhanced second-harmonic generation

    CERN Document Server

    Leo, F; Ricciardi, I; De Rosa, M; Coen, S; Wabnitz, S; Erkintalo, M

    2016-01-01

    We derive a time-domain mean-field equation to model the full temporal and spectral dynamics of light in singly resonant cavity-enhanced second-harmonic generation systems. We show that the temporal walk-off between the fundamental and the second-harmonic fields plays a decisive role under realistic conditions, giving rise to rich, previously unidentified nonlinear behaviour. Through linear stability analysis and numerical simulations, we discover a new kind of quadratic modulation instability which leads to the formation of optical frequency combs and associated time-domain dissipative structures. Our numerical simulations show excellent agreement with recent experimental observations of frequency combs in quadratic nonlinear media [Phys. Rev. A 91, 063839 (2015)]. Thus, in addition to unveiling a new, experimentally accessible regime of nonlinear dynamics, our work enables predictive modeling of frequency comb generation in cavity-enhanced second-harmonic generation systems.

  13. 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.

  14. Direct optical detection of current induced spin accumulation in metals by magnetization-induced second harmonic generation

    International Nuclear Information System (INIS)

    Strong spin-orbit coupling in non-magnetic heavy metals has been shown to lead to large spin currents flowing transverse to a charge current in such a metal wire. This in turn leads to the buildup of a net spin accumulation at the lateral surfaces of the wire. Spin-orbit torque effects enable the use of the accumulated spins to exert useful magnetic torques on adjacent magnetic layers in spintronic devices. We report the direct detection of spin accumulation at the free surface of nonmagnetic metal films using magnetization-induced optical surface second harmonic generation. The technique is applied to probe the current induced surface spin accumulation in various heavy metals such as Pt, β-Ta, and Au with high sensitivity. The sensitivity of the technique enables us to measure the time dynamics on a sub-ns time scale of the spin accumulation arising from a short current pulse. The ability of optical surface second harmonic generation to probe interfaces suggests that this technique will also be useful for studying the dynamics of spin accumulation and transport across interfaces between non-magnetic and ferromagnetic materials, where spin-orbit torque effects are of considerable interest

  15. Direct optical detection of current induced spin accumulation in metals by magnetization-induced second harmonic generation

    Energy Technology Data Exchange (ETDEWEB)

    Pattabi, A., E-mail: akshaypattabi@berkeley.edu; Gu, Z.; Yang, Y.; Finley, J.; Lee, O. J.; Raziq, H. A. [Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720 (United States); Gorchon, J.; Salahuddin, S.; Bokor, J. [Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720 (United States); Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, California 94720 (United States)

    2015-10-12

    Strong spin-orbit coupling in non-magnetic heavy metals has been shown to lead to large spin currents flowing transverse to a charge current in such a metal wire. This in turn leads to the buildup of a net spin accumulation at the lateral surfaces of the wire. Spin-orbit torque effects enable the use of the accumulated spins to exert useful magnetic torques on adjacent magnetic layers in spintronic devices. We report the direct detection of spin accumulation at the free surface of nonmagnetic metal films using magnetization-induced optical surface second harmonic generation. The technique is applied to probe the current induced surface spin accumulation in various heavy metals such as Pt, β-Ta, and Au with high sensitivity. The sensitivity of the technique enables us to measure the time dynamics on a sub-ns time scale of the spin accumulation arising from a short current pulse. The ability of optical surface second harmonic generation to probe interfaces suggests that this technique will also be useful for studying the dynamics of spin accumulation and transport across interfaces between non-magnetic and ferromagnetic materials, where spin-orbit torque effects are of considerable interest.

  16. 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; Hasler, Karl-Heinz; Erbert, Goetz; Petersen, Paul Michael

    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...

  17. Laue diffraction in one-dimensional photonic crystals: The way for phase-matched second-harmonic generation

    Science.gov (United States)

    Novikov, V. B.; Maydykovskiy, A. I.; Mantsyzov, B. I.; Murzina, T. V.

    2016-06-01

    Phase-matched second-harmonic generation (SHG) under the Bragg diffraction in the Laue geometry in one-dimensional photonic crystal (PhC) is studied theoretically and experimentally. We demonstrate that the phase-matched SHG can be realized in a PhC by compensation of the material dispersion of the PhC constituent layers of adjustable thickness. The second-order nonlinear susceptibility is introduced in the porous quartz-based PhC by its infiltration by sodium nitrite. We observed that two second-harmonic (SH) beams appear after passing through the PhC under the phase-matched process, which correspond to the transmission and diffraction angular directions. The appearance of the phase-matched SHG is confirmed by a pronounced SH spectral dependence and a narrow SH angular distribution, with the FWHM of the SH peak of approximately 3.5 times smaller as compared to the case of non-phase-matched SHG.

  18. Precise, motion-free polarization control in Second Harmonic Generation microscopy using a liquid crystal modulator in the infinity space.

    Science.gov (United States)

    Lien, Chi-Hsiang; Tilbury, Karissa; Chen, Shean-Jen; Campagnola, Paul J

    2013-01-01

    Second Harmonic Generation (SHG) microscopy coupled with polarization analysis has great potential for use in tissue characterization, as molecular and supramolecular structural details can be extracted. Such measurements are difficult to perform quickly and accurately. Here we present a new method that uses a liquid crystal modulator (LCM) located in the infinity space of a SHG laser scanning microscope that allows the generation of any desired linear or circular polarization state. As the device contains no moving parts, polarization can be rotated accurately and faster than by manual or motorized control. The performance in terms of polarization purity was validated using Stokes vector polarimetry, and found to have minimal residual polarization ellipticity. SHG polarization imaging characteristics were validated against well-characterized specimens having cylindrical and/or linear symmetries. The LCM has a small footprint and can be implemented easily in any standard microscope and is cost effective relative to other technologies. PMID:24156059

  19. Efficient sum-frequency and second harmonic generation in a two-pass copper vapour laser amplifier

    International Nuclear Information System (INIS)

    New results are presented on the efficient generation of UV radiation by using nonlinear DKDP and BBO crystals and a two-pass copper vapour laser amplifier with the enhanced peak power. The average power (average optical efficiency) of laser radiation at the sum frequency (λ=0.271 μm) was 3.6 W (24%) for the BBO crystal and 2.1 W (14%) for the DKDP crystal. The maximum average second-harmonic power generated by using the BBO crystal was 3.4 W (44%) at 0.289 μm and 2.1 W (27%) at 0.255 μm. (nonlinear optical phenomena)

  20. High-peak-power second-harmonic generation of single-stage Yb-doped fiber amplifiers

    Science.gov (United States)

    Horiuchi, Ryusuke; Saiki, Koichi; Adachi, Koji; Tei, Kazuyoku; Yamaguchi, Shigeru

    2008-05-01

    A high-peak-power and high-repetition-rate fiber laser architecture is successfully demonstrated using a single-stage fiber amplifier. Nonlinear optical effects in a fiber amplifier degrade the monochromaticity of amplified laser pulses. In general, it is difficult for a non-monochromatic laser pulse to realize high-order harmonic generation with bulk nonlinear optical crystals. To overcome this problem, a single-stage amplifier architecture and a gain fiber with a high cladding absorption coefficient are employed. Furthermore, single-stage amplification enables the use of a multi-longitudinal mode electro-optically (EO) Q-switched micro seed laser. This architecture can generate a peak power of 100 kW at 50 kHz and an average power of 10 W. A second-harmonic conversion efficiency of 51% is obtained using this architecture and a LiB3O5 (LBO) crystal.

  1. 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.

  2. 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. PMID:27555114

  3. Numerical analysis of second harmonic generation for THz-wave in a photonic crystal waveguide using a nonlinear FDTD algorithm

    Science.gov (United States)

    Saito, Kyosuke; Tanabe, Tadao; Oyama, Yutaka

    2016-04-01

    We have presented a numerical analysis to describe the behavior of a second harmonic generation (SHG) in THz regime by taking into account for both linear and nonlinear optical susceptibility. We employed a nonlinear finite-difference-time-domain (nonlinear FDTD) method to simulate SHG output characteristics in THz photonic crystal waveguide based on semi insulating gallium phosphide crystal. Unique phase matching conditions originated from photonic band dispersions with low group velocity are appeared, resulting in SHG output characteristics. This numerical study provides spectral information of SHG output in THz PC waveguide. THz PC waveguides is one of the active nonlinear optical devices in THz regime, and nonlinear FDTD method is a powerful tool to design photonic nonlinear THz devices.

  4. Second-harmonic generation from sub-monolayer molecular adsorbates using a c-w diode laser: Maui surface experiment

    International Nuclear Information System (INIS)

    Optical second-harmonic generation (SHG) can be an extremely sensitive tool for surface studies. The technique is capable of probing adsorbed molecules at various interfaces. It is based on the idea that SHG is forbidden in a medium with inversion symmetry, but necessarily allowed at a surface. To see such a surface nonlinear optical effect, high laser intensity is often needed. Thus, in the experiments reported so far, pulsed lasers were used exclusively. From the consideration for practical applications, however, the technique would look much more attractive if the bulky pulsed laser can be replaced by a simple inexpensive c-w diode laser. This paper describes the first demonstration of surface SHG with a c-w laser. 3 refs., 1 fig

  5. Second harmonic generation spectroscopy in the Reststrahl band of SiC using an infrared free-electron laser

    Science.gov (United States)

    Paarmann, Alexander; Razdolski, Ilya; Melnikov, Alexey; Gewinner, Sandy; Schöllkopf, Wieland; Wolf, Martin

    2015-08-01

    The Reststrahl spectral region of silicon carbide has recently attracted much attention owing to its potential for mid-infrared nanophotonic applications based on surface phonon polaritons (SPhPs). Studies of optical phonon resonances responsible for surface polariton formation, however, have so far been limited to linear optics. In this Letter, we report the first nonlinear optical investigation of the Reststrahl region of SiC, employing an infrared free-electron laser to perform second harmonic generation (SHG) spectroscopy. We observe two distinct resonance features in the SHG spectra, one attributed to resonant enhancement of the nonlinear susceptibility χ(2) and the other due to a resonance in the Fresnel transmission. Our work clearly demonstrates high sensitivity of mid-infrared SHG to phonon-driven phenomena and opens a route to studying nonlinear effects in nanophotonic structures based on SPhPs.

  6. Second harmonic generation spectroscopy in the Reststrahl band of SiC using an infrared free-electron laser

    Energy Technology Data Exchange (ETDEWEB)

    Paarmann, Alexander, E-mail: alexander.paarmann@fhi-berlin.mpg.de; Razdolski, Ilya; Melnikov, Alexey; Gewinner, Sandy; Schöllkopf, Wieland; Wolf, Martin [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin (Germany)

    2015-08-24

    The Reststrahl spectral region of silicon carbide has recently attracted much attention owing to its potential for mid-infrared nanophotonic applications based on surface phonon polaritons (SPhPs). Studies of optical phonon resonances responsible for surface polariton formation, however, have so far been limited to linear optics. In this Letter, we report the first nonlinear optical investigation of the Reststrahl region of SiC, employing an infrared free-electron laser to perform second harmonic generation (SHG) spectroscopy. We observe two distinct resonance features in the SHG spectra, one attributed to resonant enhancement of the nonlinear susceptibility χ{sup (2)} and the other due to a resonance in the Fresnel transmission. Our work clearly demonstrates high sensitivity of mid-infrared SHG to phonon-driven phenomena and opens a route to studying nonlinear effects in nanophotonic structures based on SPhPs.

  7. Molecular interactions at the hexadecane/water interface in the presence of surfactants studied with second harmonic generation

    Science.gov (United States)

    Sang, Yajun; Yang, Fangyuan; Chen, Shunli; Xu, Hongbo; Zhang, Si; Yuan, Qunhui; Gan, Wei

    2015-06-01

    It is important to investigate the influence of surfactants on structures and physical/chemical properties of oil/water interfaces. This work reports a second harmonic generation study of the adsorption of malachite green (MG) on the surfaces of oil droplets in a hexadecane/water emulsion in the presence of surfactants including sodium dodecyl sulfate, polyoxyethylene-sorbitan monooleate (Tween80), and cetyltrimethyl ammonium bromide. It is revealed that surfactants with micromolar concentrations notably influence the adsorption of MG at the oil/water interface. Both competition adsorption and charge-charge interactions played very important roles in affecting the adsorption free energy and the surface density of MG at the oil/water interface. The sensitive detection of the changing oil/water interface with the adsorption of surfactants at such low concentrations provides more information for understanding the behavior of these surfactants at the oil/water interface.

  8. Observation of optical second-harmonic generation in porous-silicon-based photonic crystals in the Laue diffraction scheme

    Science.gov (United States)

    Kopylov, D. A.; Svyakhovskiy, S. E.; Dergacheva, L. V.; Bushuev, V. A.; Mantsyzov, B. I.; Murzina, T. V.

    2016-05-01

    Second-harmonic generation (SHG) in the Laue scheme of the dynamical Bragg diffraction in one-dimensional photonic crystal (PhC) is studied. The experiments are performed for partially annealed porous-silicon PhC containing 250 periods of the structure. Our measurements confirm that the phase-matched optical SHG is observed under the Bragg conditions, which is evidenced by a narrow angular and spectral distribution of the diffracted SHG outgoing the PhC. This is confirmed by both the analytical description of the SHG process performed in the two-wave approximation, and by direct calculations of the PhC dispersion curves for the fundamental and SHG wavelengths by the revised plane wave method. Possible types of phase- and quasi-phase-matching realized in the studied PhC under the Laue diffraction scheme are discussed.

  9. Second Harmonic Generation Microscopy: A Tool for Spatially and Temporally Resolved Studies of Heat Induced Structural Changes in Meat

    DEFF Research Database (Denmark)

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

    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...... scattered SHG light reveal complementary features of the structures of myofibers and collagen fibers. Upon heating the myofibers show no structural changes before reaching a temperature of 53 °C. At this temperature the SHG signal becomes extinct. The extinction of the SHG at 53 °C coincides with a low......-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...

  10. 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 .

  11. Development of blue lasers, from second harmonic generation using a Nd:YAG laser emitting at 946 nm

    International Nuclear Information System (INIS)

    Blue lasers have attracted much attention for applications such as blue-ray, displays and as pumped source for the Ti:sapphire laser. A Nd:YAG crystal with diffusion bonded end-caps was used together with a pump wavelength of 802,3 nm, detuned from the absorption peak at 808 nm in order to minimize the thermal lens effect by providing for a better temperature distribution inside the crystal. Using different input mirror radii, the best relation between pump waist and laser was achieved in a linear cavity and resulted in 6.75W cw (continuous wave) laser power at 946 nm and slope efficiency of 48%. In a second step, a second harmonic generation crystal for blue emission at 473 nm was inserted into different types of resonators, and the blue output power at 473 nm was measured as a function of absorbed pump power. (author)

  12. Nitric acid extraction with monoamide and diamide monitored by second harmonic generation at the water/dodecane interface

    International Nuclear Information System (INIS)

    The interfacial properties of the DEHiBA and DMDBTDMA extractant molecules used in the nuclear industry are examined to obtain a better understanding of ion transfer across the water/oil interface. Optical second harmonic generation (SHG) is used in combination with bulk nitric acid titration and interfacial tension (IFT) measurements. First, the amphiphilic properties of both extractant molecules are characterized by static IFT. Second, real time SHG experiments and titration are carried out to follow the kinetics of nitric acid extraction. The SHG intensity evolution is strongly dependant on the extractant concentration in the organic phase and the SHG intensity fluctuations are correlated with the nitric acid flux across the interface. It suggests that these intensity fluctuations are the signature of a strong modification of extractant concentration at the interface that is maximal close to a critical aggregation concentration of extractant in the organic phase. (authors)

  13. 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.

  14. Second harmonic generation monitoring of nitric acid extraction by a monoamide at the water-dodecane interface.

    Science.gov (United States)

    Martin-Gassin, G; Gassin, P M; Couston, L; Diat, O; Benichou, E; Brevet, P F

    2011-11-21

    The interface dynamic properties of a monoamide extractant with potential for application to the front end of the nuclear cycle and to waste treatment are examined by second harmonic generation. The results are compared with bulk nitric ion titration and surface pressure measurements. SH static studies show the extractant reaching the interface and accurately match the IFT measurements. The main feature of the SH dynamic studies is a chaotic fluctuation period, strongly related to intense extraction. Fluctuations are a signature of the interface behaviour during the extraction process. Vertical development of the interface, often called protrusion, remains the most probable origin of the measured fluctuation. Additionally, interfacial measurements show a non-monotonic lag time during extraction, probably related to cooperative effects not observed in the bulk at the working concentration. Such mutual behaviour could be a supplementary prerequisite for the ion transfer across this liquid-liquid interface. PMID:21952270

  15. Two-wavelength interferometer based on sinusoidal phase modulation with an acetylene stabilized laser and a second harmonic generation.

    Science.gov (United States)

    Kawata, Yoshiyuki; Hyashi, Kyohei; Aoto, Tomohiro

    2015-06-15

    A two-wavelength interferometer (TWI) based on a sinusoidal-phase-modulation method with an acetylene stabilized laser and a second harmonic generation (SHG) was developed. The periodic non-linearity error for the TWI was estimated to be ± 0.1 µm at a dead path of 0.32 m. A long-term measurement showed that the TWI stability was ± 3 × 10(-7) at a dead path of 1.00 m for 12 hours with an ambient pressure variation of 3 hPa under controlled conditions of ambient temperature and humidity. Finally, we confirmed that the TWI has substantially better stability than a single-wavelength interferometer by comparing both interferometers with large temporal and spatial temperature variations. PMID:26193576

  16. Second harmonic generation spectroscopy in the Reststrahl band of SiC using an infrared free-electron laser

    International Nuclear Information System (INIS)

    The Reststrahl spectral region of silicon carbide has recently attracted much attention owing to its potential for mid-infrared nanophotonic applications based on surface phonon polaritons (SPhPs). Studies of optical phonon resonances responsible for surface polariton formation, however, have so far been limited to linear optics. In this Letter, we report the first nonlinear optical investigation of the Reststrahl region of SiC, employing an infrared free-electron laser to perform second harmonic generation (SHG) spectroscopy. We observe two distinct resonance features in the SHG spectra, one attributed to resonant enhancement of the nonlinear susceptibility χ(2) and the other due to a resonance in the Fresnel transmission. Our work clearly demonstrates high sensitivity of mid-infrared SHG to phonon-driven phenomena and opens a route to studying nonlinear effects in nanophotonic structures based on SPhPs

  17. Analysis of forward and backward Second Harmonic Generation images to probe the nanoscale structure of collagen within bone and cartilage.

    Science.gov (United States)

    Houle, Marie-Andrée; Couture, Charles-André; Bancelin, Stéphane; Van der Kolk, Jarno; Auger, Etienne; Brown, Cameron; Popov, Konstantin; Ramunno, Lora; Légaré, François

    2015-11-01

    Collagen ultrastructure plays a central role in the function of a wide range of connective tissues. Studying collagen structure at the microscopic scale is therefore of considerable interest to understand the mechanisms of tissue pathologies. Here, we use second harmonic generation microscopy to characterize collagen structure within bone and articular cartilage in human knees. We analyze the intensity dependence on polarization and discuss the differences between Forward and Backward images in both tissues. Focusing on articular cartilage, we observe an increase in Forward/Backward ratio from the cartilage surface to the bone. Coupling these results to numerical simulations reveals the evolution of collagen fibril diameter and spatial organization as a function of depth within cartilage. PMID:26349534

  18. Character of skin on photo-thermal response and its regeneration process using second-harmonic generation microscopy.

    Science.gov (United States)

    Wu, Shu-lian; Li, Hui; Zhang, Xiao-man; Chen, Wei R; Wang, Yun-Xia

    2014-01-01

    Quantitative characterization of skin collagen on photo-thermal response and its regeneration process is an important but difficult task. In this study, morphology and spectrum characteristics of collagen during photo-thermal response and its light-induced remodeling process were obtained by second-harmonic generation microscope in vivo. The texture feature of collagen orientation index and fractal dimension was extracted by image processing. The aim of this study is to detect the information hidden in skin texture during the process of photo-thermal response and its regeneration. The quantitative relations between injured collagen and texture feature were established for further analysis of the injured characteristics. Our results show that it is feasible to determine the main impacts of phototherapy on the skin. It is important to understand the process of collagen remodeling after photo-thermal injuries from texture feature. PMID:23508280

  19. 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.

  20. Role of phase matching in pulsed second-harmonic generation: Walk-off and phase-locked twin pulses in negative-index media

    International Nuclear Information System (INIS)

    The present investigation is concerned with the study of pulsed second-harmonic generation under conditions of phase and group velocity mismatch, and generally low conversion efficiencies and pump intensities. In positive-index, nonmetallic materials, we generally find qualitative agreement with previous reports regarding the presence of a double-peaked second harmonic signal, which comprises a pulse that walks off and propagates at the nominal group velocity one expects at the second-harmonic frequency, and a second pulse that is 'captured' and propagates under the pump pulse. We find that the origin of the double-peaked structure resides in a phase-locking mechanism that characterizes not only second-harmonic generation, but also χ(3) processes and third-harmonic generation. The phase-locking mechanism that we describe occurs for arbitrarily small pump intensities, and so it is not a soliton effect, which usually relies on a threshold mechanism, although multicolor solitons display similar phase locking characteristics. Thus, in second harmonic generation a phase-matched component is always generated, even under conditions of material phase mismatch: This component is anomalous, because the material does not allow energy exchange between the pump and the second-harmonic beam. On the other hand, if the material is phase matched, phase locking and phase matching are indistinguishable, and the conversion process becomes efficient. We also report a similar phase-locking phenomenon in negative index materials. A spectral analysis of the pump and the generated signals reveals that the phase-locking phenomenon causes the forward moving, phase-locked second-harmonic pulse to experience the same negative index as the pump pulse, even though the index of refraction at the second-harmonic frequency is positive. Our analysis further shows that the reflected second-harmonic pulse generated at the interface and the forward-moving, phase-locked pulse appear to be part of the

  1. 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

    2016-02-01

    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.

  2. 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

    2016-01-01

    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. PMID:26924255

  3. A comparative study of second-harmonic generation in plasmonic and dielectric gratings made of centrosymmetric materials (Presentation Recording)

    Science.gov (United States)

    Weismann, Martin; Gallagher, Dominic F. G.; Panoiu, Nicolae-Coriolan

    2015-09-01

    We present a new numerical method for the analysis of second-harmonic generation (SHG) in one- and two-dimensional (1D, 2D) diffraction gratings containing centrosymmetric quadratically nonlinear materials. Thus, the nonlinear optical properties of a material are determined by its symmetry properties: non-centrosymmetric materials lack inversion symmetry and therefore allow local even-order SHG in the bulk of the material, whereas this process is forbidden in centrosymmetric materials. The inversion symmetry of centrosymmetric materials is broken at their surface whence they allow local surface SHG. Additionally, centrosymmetric materials give rise to nonlocal (bulk) SHG. Our numerical method extends the linear generalized source method (GSM), which is an efficient numerical method for solving the problem of linear diffraction in periodic structures of arbitrary geometry. The nonlinear GSM is a three-step algorithm: for a given excitation at the fundamental frequency the linear field is computed using the linear GSM. This field gives rise to a nonlinear source polarization at the second harmonic (SH) frequency. This nonlinear polarization comprises surface and bulk polarizations as additional source terms and is subsequently used to compute the nonlinear near- and far-field optical response at the SH. We study the convergence characteristics of the nonlinear GSM for 1D and 2D periodic structures and emphasize the numerical intricacies caused by the surface SH polarization term specific to centrosymmetric materials. In order to illustrate the practical significance of our numerical method, we apply it to metallic gratings made of Au and Ag as well as dielectric grating structures made of silicon and investigate the relative contribution of the bulk and surface nonlinearity to the nonlinear optical response at the SH. Particular attention is paid to optical effects that have a competing influence to the nonlinear optical response of the grating structures, namely the

  4. High power second-harmonic generation of Nd:glass laser with CLBO crystals

    International Nuclear Information System (INIS)

    We have demonstrated the generation of a high-energy green laser pulse using large aperture CsLiB6O10 (CLBO) crystals for the first time to our knowledge. A pulsed energy of 25 J at 532-nm was generated using the 1064-nm incident Nd:glass laser radiation with an energy of 34 J. High conversion efficiency of 74% at intensities of only 370 MW/cm2 was obtained using a two-stage crystal architecture. This result represents the highest green pulse energy ever reported using the CLBO crystals. (author)

  5. Creation, doubling, and splitting, of vortices in intracavity second harmonic generation

    CERN Document Server

    Lim, O K; Saffman, M; Królikowski, W

    2003-01-01

    We demonstrate generation and frequency doubling of unit charge vortices in a linear astigmatic resonator. Topological instability of the double charge harmonic vortices leads to well separated vortex cores that are shown to rotate, and become anisotropic, as the resonator is tuned across resonance.

  6. Organic salts of guanazole - Seeking for new materials for second harmonic generation

    Czech Academy of Sciences Publication Activity Database

    Matulková, Irena; Císařová, I.; Němec, P.; Kroupa, Jan; Vaněk, Přemysl; Tesařová, N.; Němec, I.

    2013-01-01

    Roč. 1044, SI (2013), s. 239-247. ISSN 0022-2860. [31st European Congress on Molecular Spectroscopy (EUCMOS). Cluj Napoca, 26.08.2012-31.08.2012] Institutional research plan: CEZ:AV0Z10100520 Keywords : 3,5-diamino-1,2,4-triazole * crystal structure * vibrational spectroscopy * second hamonic generation Subject RIV: CA - Inorganic Chemistry Impact factor: 1.599, year: 2013 http://dx.doi.org/10.1016/j.molstruc.2012.11.011

  7. Large-angle magnetization dynamics investigated by vector-resolved magnetization-induced optical second-harmonic generation

    Science.gov (United States)

    Gerrits, Th.; Silva, T. J.; Nibarger, J. P.; Rasing, Th.

    2004-12-01

    We examine the relationship between nonlinear magnetic responses and the change in the Gilbert damping parameter α for patterned and unpatterned thin Permalloy films when subjected to pulsed magnetic fields. An improved magnetization-vector-resolved technique utilizing magnetization-induced optical second-harmonic generation was used to measure magnetization dynamics after pulsed-field excitation. The magnetization excitations were achieved with pulsed fields aligned parallel to the hard axis of thin permalloy (Ni80Fe20) films while a dc bias field is applied along the easy axis. At low bias fields, α was inversely related to the bias field, but there was no significant reduction in the absolute value of the magnetization, as might be expected if there was significant spin-wave generation during the damping process. We discuss the discrepancies between data obtained by ferromagnetic resonance, whereby spin-wave generation is prevalent, and pulsed-field studies, with the conclusion that fundamental differences between the two techniques for the excitation of the ferromagnetic spin system might explain the different proclivities toward spin-wave generation manifest in these two experimental methods.

  8. Spatial and spectral properties of fields generated by pulsed second-harmonic generation in a periodically poled potassium-titanyl-phosphate waveguide

    Czech Academy of Sciences Publication Activity Database

    Machulka, R.; Svozilík, J.; Soubusta, Jan; Peřina ml., Jan; Haderka, O.

    2013-01-01

    Roč. 87, č. 1 (2013), "013836-p1"-"013836-p9". ISSN 1050-2947 R&D Projects: GA AV ČR IAA100100713 Grant ostatní: GA MŠk(CZ) OC09026 Institutional research plan: CEZ:AV0Z10100520 Keywords : spatial and spectral properties * pulsed second-harmonic generation * periodically poled potassium -titanyl-phosphate waveguide Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.991, year: 2013

  9. Theoretical and experimental investigations of nanosecond 177.3 nm deep-ultraviolet light by second harmonic generation in KBBF

    Science.gov (United States)

    Yang, F.; Wang, Z.; Zhou, Y.; Li, F.; Xu, J.; Xu, Y.; Cheng, X.; Lu, Y.; Bo, Y.; Peng, Q.; Cui, D.; Zhang, X.; Wang, X.; Zhu, Y.; Xu, Z.

    2009-08-01

    We have presented theoretical and experimental investigations of nanosecond (ns) deep-ultraviolet (DUV) 177.3 nm radiation by means of second harmonic generation (SHG) from a frequency-tripled Nd:YAG laser (355 nm, 49 ns and 10 kHz) in KBe2BO3F2 (KBBF) nonlinear crystal for the first time. A DUV KBBF-SHG numerical model, accounting for linear absorption, pump depletion, beam spatial birefringent walk-off and diffraction, is performed in the Gaussian approximation of spatial and temporal profiles. In the experiment, a maximum average output power of 14.1 mW at 177.3 nm was obtained. The dependence of 177.3 nm output power on the 355 nm pump power was simulated. The calculated results are in good agreement with the measured data. We used the model further to investigate the optical conversion efficiency, pulse width, beam spatial intensity profile and beam quality factor of the generated 177.3 nm light, in particular the effect of beam birefringent walk-off.

  10. Walk-Off-Induced Modulation Instability, Temporal Pattern Formation, and Frequency Comb Generation in Cavity-Enhanced Second-Harmonic Generation

    Science.gov (United States)

    Leo, F.; Hansson, T.; Ricciardi, I.; De Rosa, M.; Coen, S.; Wabnitz, S.; Erkintalo, M.

    2016-01-01

    We derive a time-domain mean-field equation to model the full temporal and spectral dynamics of light in singly resonant cavity-enhanced second-harmonic generation systems. We show that the temporal walk-off between the fundamental and the second-harmonic fields plays a decisive role under realistic conditions, giving rise to rich, previously unidentified nonlinear behavior. Through linear stability analysis and numerical simulations, we discover a new kind of quadratic modulation instability which leads to the formation of optical frequency combs and associated time-domain dissipative structures. Our numerical simulations show excellent agreement with recent experimental observations of frequency combs in quadratic nonlinear media [Phys. Rev. A 91, 063839 (2015)]. Thus, in addition to unveiling a new, experimentally accessible regime of nonlinear dynamics, our work enables predictive modeling of frequency comb generation in cavity-enhanced second-harmonic generation systems. We expect our findings to have wide impact on the study of temporal and spectral dynamics in a diverse range of dispersive, quadratically nonlinear resonators.

  11. Effect of axonal micro-tubules on the morphology of retinal nerve fibers studied by second-harmonic generation

    Science.gov (United States)

    Lim, Hyungsik; Danias, John

    2012-11-01

    Many studies suggest that the degradation of microtubules in the retinal ganglion cells may be an early event in the progression of glaucoma. Because reflectance and birefringence of the retinal nerve fibers arise primarily from microtubules, the optical properties have been intensively studied for early detection of the disease. We previously reported a novel nonlinear optical signal from axonal microtubules for visualizing the retinal nerve fibers, namely second-harmonic generation (SHG). We demonstrate the use of axonal SHG to investigate the effect of microtubules on the morphology of the retinal nerve fiber bundles. Time-lapse SHG imaging of ex vivo rat retinal flat mounts was performed during pharmacological treatment of nocodazole, and the intensity of axonal SHG and the changes in nerve fiber bundle morphology were monitored. We found that the microtubule disruption does not lead to immediate modification in the morphology of the nerve fibers. Our results indicate that microtubular SHG may provide a useful means for sensitive detection of axonal injuries. Since the intrinsic radiation depends on the regular architecture of the cytoskeleton element as maintained by active cellular regulations, the intensity of signal reflects the health of the retinal ganglion cell axons.

  12. Remarkable effect of Ni2+doping on structural, second harmonic generation, optical, mechanical and dielectric properties of KDP single crystals

    Science.gov (United States)

    Ganesh, V.; Shkir, Mohd.; AlFaify, S.; Algarni, H.; Abutalib, M. M.; Yahia, I. S.

    2016-06-01

    The nonlinear optical single crystals of pure and Ni2+ doped potassium dihydrogen phosphate (KDP) were successfully grown by slow evaporation solution growth technique. The effects of the addition of Ni2+ 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.

  13. Multi-view second-harmonic generation imaging of mouse tail tendon via reflective micro-prisms

    Science.gov (United States)

    Wen, Bruce; Campbell, Kirby R.; Cox, Benjamin L.; Eliceiri, Kevin W.; Superfine, Richard; Campagnola, Paul J.

    2016-01-01

    Here we experimentally show that second-harmonic generation (SHG) imaging is not sensitive to collagen fibers oriented parallel to the direction of laser propagation and, as a consequence, can potentially miss important structural information. As an alternative approach, we demonstrate the use of reflective micro-prisms to enable multi-view SHG imaging of mouse tail tendon by redirecting the focused excitation and collection of subsequent emission. Our approach data corroborates the theoretical treatment on vanishing and nonvanishing orientations, where fibers along the laser direction are largely transparent by SHG. In strong contrast, the two-photon excited fluorescence of dye-labeled collagen fibers is isotropic and is not subject to this constraint. We utilized Pearson correlation to quantify differences in fluorescent and backward detected SHG images of the tendon fiber structure, where the SHG and TPEF were highly statistically correlated (0.6–0.8) for perpendicular excitation but were uncorrelated for excitation parallel to the fiber axis. The results suggest that improved imaging of 3D collagen structure is possible with multi-view SHG microscopy. PMID:26125402

  14. Study of interface layer effect in organic solar cells by electric-field-induced optical second-harmonic generation measurement

    International Nuclear Information System (INIS)

    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)/C60/Al diodes showed that the BCP layer inserted between C60 and Al formed an electrostatic field |Ei| = 2.5 × 104 V/cm in the C60 layer, pointing in a direction from the Al to the IZO. Accordingly, in the IZO/pentacene/C60/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

  15. Palmitate Luciferin: A molecular design for the second harmonic generation study of ion complexation at the air-water interface

    International Nuclear Information System (INIS)

    A molecular organic chromophore, Palmitate-Luciferin, has been synthesized for studying ion complexation at the air-water interface using second harmonic generation (SHG). This molecule was designed through the addition of a long hydrophobic palmitoyl alkyl chain to the aromatic π-electron system of Luciferin. We first demonstrate that this organic chromophore is a potential candidate for SHG studies of ion complexation with the measurement of its first hyper-polarizability in aqueous solutions by hyper Rayleigh scattering (HRS) with and without calcium ions. Then, we characterize the Palmitate-Luciferin surfactant properties at the air-water interface combining surface tension measurements with a surface SHG study and Brewster angle imaging. These results allow us to build a molecular description of the chromophore at the interface and observe its molecular reorganization during the monolayer compression leading to the formation of aggregates. Finally, we show that the initial goal of the designing work is achieved since Palmitate-Luciferin indeed exhibits a higher SHG response in the presence of calcium ions in the aqueous sub-phase as expected. (authors)

  16. Multi-scale modeling of mycosubtilin lipopeptides at the air/water interface: structure and optical second harmonic generation.

    Science.gov (United States)

    Loison, Claire; Nasir, Mehmet Nail; Benichou, Emmanuel; Besson, Françoise; Brevet, Pierre-François

    2014-02-01

    Monolayers of the lipopeptide mycosubtilin are studied at the air/water interface. Their structure is investigated using molecular dynamics simulations. All-atom models suggest that the lipopeptide is flexible and aggregates at the interface. To achieve simulation times of several microseconds, a coarse-grained (CG) model based on the MARTINI force field was also used. These CG simulations describe the formation of half-micelles at the interface for surface densities up to 1 lipopeptide per nm(2). In these aggregates, the tyrosine side chain orientation is found to be constrained: on average, its main axis, as defined along the C-OH bond, aligns along the interface normal and points towards the air side. The origin of the optical second harmonic generation (SHG) from mycosubtilin monolayers at the air/water interface is also investigated. The molecular hyperpolarizability of the lipopeptide is obtained from quantum chemistry calculations. The tyrosine side chain contribution to the hyperpolarizability is found to be dominant. The orientation distribution of tyrosine, associated with a dominant hyperpolarizability component along the C-OH bond of the tyrosine, yields a ratio of the susceptibility elements χ((2))(ZZZ)/χ((2))(ZXX) consistent with the experimental measurements recently reported by M. N. Nasir et al. [Phys. Chem. Chem. Phys., 2013, 15, 19919]. PMID:24346061

  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. PMID:27145724

  18. “Triggering” effect of second harmonic generation in centrosymmetric α-BaB2O4 crystals

    Science.gov (United States)

    Adamiv, V. T.; Ebothe, J.; Piasecki, M.; Burak, Ya. V.; Teslyuk, I. M.; Plucinski, K. J.; Reshak, Ali H.; Kityk, I. V.

    2009-02-01

    We have discovered an occurrence of optical second harmonic generation at 1064 nm fundamental wavelength for the α-BaB 2O 4 (ABO) crystal illuminated by 7 ns nanosecond nitrogen laser of 337 nm. The effect is observed only during illumination and achieves the maximum SHG output after 15-20 min of treatment. After switching off of the UV laser treatment the SHG decreases during about 5 min. The maximum second order susceptibility achieved was equal to about 2.1 pm/V at 1064 nm after about 20 min of UV laser treatment. The observed SHG is explained by local photothermal heating of the crystals and photo stimulated photothermal anisotropy that favors an occurrence non-centrosymmetry of the local charge density. An additional investigations of the low-power (cw) He-Ne laser light indicate the absence of additional light scattering, which unambiguously indicates an absence of any additional microcrystalline states including non-cenrosymmetrical β-BaB 2O 4 phases. Probably photostimulated enhancement of thermal expansion anisotropy the main reason for the observed non-centrosymmetry.

  19. 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

    2016-02-01

    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

  20. Influence of the tyrosine environment on the second harmonic generation of iturinic antimicrobial lipopeptides at the air-water interface.

    Science.gov (United States)

    Nasir, Mehmet Nail; Benichou, Emmanuel; Loison, Claire; Russier-Antoine, Isabelle; Besson, Françoise; Brevet, Pierre-François

    2013-12-01

    The second harmonic generation (SHG) response at the air-water interface from the tyrosine-containing natural iturinic cyclo-lipopeptides mycosubtilin, iturin A and bacillomycin D is reported. It is shown that this response is dominated by the single tyrosine residue present in these molecules owing to the large first hyperpolarizability arising from the non-centrosymmetric aromatic ring structure of this amino acid. The SHG response of these iturinic antibiotics is also compared to the response of surfactin, a cyclo-lipopeptide with a similar l,d-amino acid sequence but lacking a tyrosine residue, and PalmATA, a synthetic linear lipopeptide possessing a single tyrosine residue but lacking the amino acid sequence structuring the cycle of the iturinic antibiotics. From the light polarization analysis of the SHG response, it is shown that the tyrosine local environment is critical in defining the SHG response of these peptides at the air-water interface. Our results demonstrate that tyrosine, similar to tryptophan, can be used as an endogenous molecular probe of peptides and proteins for SHG at the air-water interface, paving the way for SHG studies of other tyrosine-containing bioactive molecules. PMID:24149982

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. Study of all-polymer-based waveguide resonant gratings and their applications for optimization of second-harmonic generation

    International Nuclear Information System (INIS)

    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. (paper)

  6. Ambient-condition growth of high-pressure phase centrosymmetric crystalline KDP microstructures for optical second harmonic generation.

    Science.gov (United States)

    Ren, Yan; Zhao, Xian; Hagley, Edward W; Deng, Lu

    2016-08-01

    Noncentrosymmetric potassium dihydrogen phosphate (KH2PO4 or KDP) in the tetragonal crystal phase is arguably the most extensively studied nonlinear optical crystal in history. It has prolific applications ranging from simple laser pointers to laser inertial confinement fusion systems. Recently, type IV high-pressure KDP crystal sheets with a monoclinic crystal phase having centrosymmetric properties have been observed. However, it was found that this new crystal phase is highly unstable under ambient conditions. We report ambient-condition growth of one-dimensional, self-assembled, single-crystalline KDP hexagonal hollow/solid-core microstructures that have a molecular structure and symmetry identical to the type IV KDP monoclinic crystal that was previously found to exist only at extremely high pressures (>1.6 GPa). Furthermore, we report highly efficient bulk optical second harmonic generation (SHG) from these ambient condition-grown single-crystalline microstructures, even though they have a highly centrosymmetric crystal phase. However, fundamental physics dictates that a bulk optical medium with a significant second-order nonlinear susceptibility supporting SHG must have noncentrosymmetric properties. Laue diffraction analysis reveals a weak symmetry-breaking twin-crystal lattice that, in conjunction with tight confinement of the light field by the tubular structure, is attributed to the significant SHG even with sample volumes <0.001 mm(3). A robust polarization-preserving effect is also observed, raising the possibility of advanced optical technological applications. PMID:27574703

  7. Calcite microcrystals in the pineal gland of the human brain: second harmonic generators and possible piezoelectric transducers

    International Nuclear Information System (INIS)

    Full text: A new form of biomineralization in the pineal gland of the human brain has been studied. It consists of small crystals that are less than 20 μm in length and that are completely distinct from the often-observed mulberry-type hydroxyapatite concretions. Cubic, hexagonal and cylindrical morphologies have been identified using scanning electron microscopy. Energy dispersive spectroscopy, selected-area electron diffraction and near infrared Raman spectroscopy established that the crystals were calcite. Experiments at the European Synchrotron Radiation Facility (ESRF) to study the biomineralization showed the presence of sulfur originating from both sugars and proteins. Other studies at the ESRF furnished information on the complex texture crystallization of the calcite. With the exception of the otoconia structure of the inner ear, this is the only known non-pathological occurrence of calcite in the human body. The calcite microcrystals are believed to be responsible for the previously observed second harmonic generation (SHG) in pineal tissue sections. There is a strong possibility that the complex twinned structure of the crystals may lower their symmetry and permit the existence of a piezoelectric effect

  8. Femtosecond laser corneal surgery with in situ determination of the laser attenuation and ablation threshold by second harmonic generation

    Science.gov (United States)

    Plamann, Karsten; Nuzzo, Valeria; Albert, Olivier; Mourou, Gérard A.; Savoldelli, Michèle; Dagonet, Françoise; Donate, David; Legeais, Jean-Marc

    2007-02-01

    Femtosecond lasers start to be routinely used in refractive eye surgery. Current research focuses on their application to glaucoma and cataract surgery as well as cornea transplant procedures. To avoid unwanted tissue damage during the surgical intervention it is of utmost importance to maintain a working energy just above the ablation threshold and maintain the laser energy at this working point independently of the local and global tissue properties. To quantify the attenuation of the laser power density in the tissue by absorption, scattering and modification of the point spread function we monitor the second harmonic radiation generated in the collagen matrix of the cornea when exposed to ultrashort laser pulses. We use a CPA system with a regenerative amplifier delivering pulses at a wavelength of 1.06 μm, pulse durations of 400 fs and a maximum energy of 60 μJ. The repetition rate is adjustable from single shot up to 10 kHz. The experiments are performed on human corneas provided by the French Eye bank. To capture the SHG radiation we use a photomultiplier tube connected to a lockin amplifier tuned to the laser repetition rate. The measured data indicates an exponential decay of the laser beam intensity in the volume of the sample and allows for the quantification of the attenuation coefficient and its correlation with the optical properties of the cornea. Complementary analyses were performed on the samples by ultrastructural histology.

  9. 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

  10. 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. PMID:27451633

  11. 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. PMID:26928907

  12. Imaging of zebrafish in vivo with second-harmonic generation reveals shortened sarcomeres associated with myopathy induced by statin.

    Directory of Open Access Journals (Sweden)

    Shih-Hao Huang

    Full Text Available We employed second-harmonic generation (SHG imaging and the zebrafish model to investigate the myopathy caused by statin in vivo with emphasis on the altered microstructures of the muscle sarcomere, the fundamental contractile element of muscles. This approach derives an advantage of SHG imaging to observe the striated skeletal muscle of living zebrafish based on signals produced mainly from the thick myosin filament of sarcomeres without employing exogenous labels, and eliminates concern about the distortion of muscle structures caused by sample preparation in conventional histological examination. The treatment with statin caused a significantly shortened sarcomere relative to an untreated control (1.73±0.09 µm vs 1.91±0.08 µm, P<0.05 while the morphological integrity of the muscle fibers remained largely intact. Mechanistic tests indicated that this microstructural disorder was associated with the biosynthetic pathway of cholesterol, or, specifically, with the impaired production of mevalonate by statins. This microstructural disorder exhibited a strong dependence on both the dosage and the duration of treatment, indicating a possibility to assess the severity of muscle injury according to the altered length of the sarcomeres. In contrast to a conventional assessment of muscle injury using clinical biomarkers in blood, such as creatine kinase that is released from only disrupted myocytes, the ability to determine microstructural modification of sarcomeres allows diagnosis of muscle injury before an onset of conventional clinical symptoms. In light of the increasing prevalence of the incidence of muscle injuries caused by new therapies, our work consolidates the combined use of the zebrafish and SHG imaging as an effective and sensitive means to evaluate the safety profile of new therapeutic targets in vivo.

  13. Enhancement in the structure quality of ZnO nanorods by diluted Co dopants: Analyses via optical second harmonic generation

    International Nuclear Information System (INIS)

    We report a systematic study about the effect of cobalt concentration in the growth solution over the crystallization, growth, and optical properties of hydrothermally synthesized Zn1−xCoxO [0 ≤ x ≤ 0.40, x is the weight (wt.) % of Co in the growth solution] nanorods. Dilute Co concentration of 1 wt. % in the growth solution enhances the bulk crystal quality of ZnO nanorods, and high wt. % leads to distortion in the ZnO lattice that depresses the crystallization, growth as well as the surface structure quality of ZnO. Although, Co concentration in the growth solution varies from 1 to 40 wt. %, the real doping concentration is limited to 0.28 at. % that is due to the low growth temperature of 80 °C. The enhancement in the crystal quality of ZnO nanorods at dilute Co concentration in the solution is due to the strain relaxation that is significantly higher for ZnO nanorods prepared without, and with high wt. % of Co in the growth solution. Second harmonic generation is used to investigate the net dipole distribution from these coatings, which provides detailed information about bulk and surface structure quality of ZnO nanorods at the same time. High quality ZnO nanorods are fabricated by a low-temperature (80 °C) hydrothermal synthesis method, and no post synthesis treatment is needed for further crystallization. Therefore, this method is advantageous for the growth of high quality ZnO coatings on plastic substrates that may lead toward its application in flexible electronics

  14. Thickness dependence of second-harmonic generation in thin films fabricated from ionically self-assembled monolayers

    OpenAIRE

    Heflin, James R.; Figura, C.; Marciu, D.; Liu, Y.; Claus, Richard O.

    1999-01-01

    An ionically self-assembled monolayer (ISAM) technique for thin-film deposition has been employed to fabricate materials possessing the noncentrosymmetry that is requisite for a second-order, chi((2)), nonlinear optical response. As a result of the ionic attraction between successive layers, the ISAM chi((2)) films self-assemble into a noncentrosymmetric structure that has exhibited no measurable decay of chi((2)) at room temperature over a period of more than one year. The second-harmonic in...

  15. Modeling and visualization of carrier motion in organic films by optical second harmonic generation and Maxwell-displacement current

    Science.gov (United States)

    Iwamoto, Mitsumasa; Manaka, Takaaki; Taguchi, Dai

    2015-09-01

    The probing and modeling of carrier motions in materials as well as in electronic devices is a fundamental research subject in science and electronics. According to the Maxwell electromagnetic field theory, carriers are a source of electric field. Therefore, by probing the dielectric polarization caused by the electric field arising from moving carriers and dipoles, we can find a way to visualize the carrier motions in materials and in devices. The techniques used here are an electrical Maxwell-displacement current (MDC) measurement and a novel optical method based on the electric field induced optical second harmonic generation (EFISHG) measurement. The MDC measurement probes changes of induced charge on electrodes, while the EFISHG probes nonlinear polarization induced in organic active layers due to the coupling of electron clouds of molecules and electro-magnetic waves of an incident laser beam in the presence of a DC field caused by electrons and holes. Both measurements allow us to probe dynamical carrier motions in solids through the detection of dielectric polarization phenomena originated from dipolar motions and electron transport. In this topical review, on the basis of Maxwell’s electro-magnetism theory of 1873, which stems from Faraday’s idea, the concept for probing electron and hole transport in solids by using the EFISHG is discussed in comparison with the conventional time of flight (TOF) measurement. We then visualize carrier transit in organic devices, i.e. organic field effect transistors, organic light emitting diodes, organic solar cells, and others. We also show that visualizing an EFISHG microscopic image is a novel way for characterizing anisotropic carrier transport in organic thin films. We also discuss the concept of the detection of rotational dipolar motions in monolayers by means of the MDC measurement, which is capable of probing the change of dielectric spontaneous polarization formed by dipoles in organic monolayers. Finally we

  16. Modeling and visualization of carrier motion in organic films by optical second harmonic generation and Maxwell-displacement current

    International Nuclear Information System (INIS)

    The probing and modeling of carrier motions in materials as well as in electronic devices is a fundamental research subject in science and electronics. According to the Maxwell electromagnetic field theory, carriers are a source of electric field. Therefore, by probing the dielectric polarization caused by the electric field arising from moving carriers and dipoles, we can find a way to visualize the carrier motions in materials and in devices. The techniques used here are an electrical Maxwell-displacement current (MDC) measurement and a novel optical method based on the electric field induced optical second harmonic generation (EFISHG) measurement. The MDC measurement probes changes of induced charge on electrodes, while the EFISHG probes nonlinear polarization induced in organic active layers due to the coupling of electron clouds of molecules and electro-magnetic waves of an incident laser beam in the presence of a DC field caused by electrons and holes. Both measurements allow us to probe dynamical carrier motions in solids through the detection of dielectric polarization phenomena originated from dipolar motions and electron transport. In this topical review, on the basis of Maxwell’s electro-magnetism theory of 1873, which stems from Faraday’s idea, the concept for probing electron and hole transport in solids by using the EFISHG is discussed in comparison with the conventional time of flight (TOF) measurement. We then visualize carrier transit in organic devices, i.e. organic field effect transistors, organic light emitting diodes, organic solar cells, and others. We also show that visualizing an EFISHG microscopic image is a novel way for characterizing anisotropic carrier transport in organic thin films. We also discuss the concept of the detection of rotational dipolar motions in monolayers by means of the MDC measurement, which is capable of probing the change of dielectric spontaneous polarization formed by dipoles in organic monolayers. Finally we

  17. 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.

  18. 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.

  19. Noncritically phase-matched second harmonic generation of blue light in Si[O]N-calix[4] arene slab type waveguides

    NARCIS (Netherlands)

    Wörhoff, K.; Noordman, O.F.J.; Lambeck, P.V.; Hulst, van N.F.; Albers, H.

    1996-01-01

    Phase-matching (TM(0)(omega) --> TM(1)(2 omega)) devices for generation of blue light using Si[0]N and optically nonlinear calix[4]arene layers are designed, fabricated and tested. The devices show second harmonic peak power of 17 mW at 472.9 nm and 4.5 W at 481.6 nm after 10 mm propagation length o

  20. In-vitro visualization of corneal wound healing in an organ culture model using multiphoton autofluorescence and second harmonic generation microscopy

    Science.gov (United States)

    Lo, Wen; Chang, Yuh-Ling; Sun, Yen; Lin, Sung-Jan; Jee, Shiou-Hwa; Tan, Hsin-Yuan; Dong, Chen-Yuan

    2007-02-01

    The aim of this work is to image the wound healing process of cornea in an in vitro organ culture model with noninvasive multiphoton imaging modality. Autofluorescence and second harmonic generation (SHG) were respectively used to monitor the alterations of cellular and collagenous components during wound healing processes. Within additional developments, this approach may be applied to in vivo visualization of corneal structural destruction and the subsequent regeneration.

  1. Local viscosity of binary water+glycerol mixtures at liquid/liquid interfaces probed by time-resolved surface second harmonic generation

    OpenAIRE

    Fita, Piotr; Punzi, Angela; Vauthey, Eric

    2009-01-01

    The excited-state relaxation of malachite green and brilliant green in solvents of various viscosity has been investigated at liquid/liquid interfaces and in bulk solutions by surface second harmonic generation and transient absorption spectroscopy. Mixtures of water and glycerol in various proportions have been used as solvents of variable viscosity. Transient absorption measurements in bulk revealed that both dyes are suitable as a probe of local viscosity for water+glycerol mixtures and th...

  2. 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}.

  3. Surface and interface states of Bi2Se3 thin films investigated by optical second-harmonic generation and terahertz emission

    International Nuclear Information System (INIS)

    We investigate the surface and interface states of Bi2Se3 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 Al2O3 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 Bi2Se3

  4. Possibility of generating a sequence of attosecond subpulses upon second harmonic generation of high-intensity femtosecond pulses in an optically extended medium

    Science.gov (United States)

    Lysak, T. M.; Trofimov, V. A.

    2009-06-01

    Based on numerical simulation, we demonstrate the possibility of forming a sequence of equalintensity coupled subpulses upon second harmonic generation (SHG) of a high-intensity femtosecond pulse in an optically extended medium whose length is much smaller than the diffraction length of the incident optical radiation. The duration of individual subpulses can be ten (or more) times shorter than the duration of the initial femtosecond pulse. With respect to the spatial coordinate, the breakup of the initial Gaussian or hyper-Gaussian beam into a regular structure of subbeams, whose size can be from two to ten times smaller than the initial beam radius, also takes place. The SHG is shown to result in a limitation of the intensity of axially symmetric beams in a nonlinear focus. The subpulses being formed can propagate with velocities that differ substantially from the velocities of their propagation in the linear medium. The shape of the subpulses is close to a soliton shape, whereas the spatial distribution of the beam has a profile that can be approximated by a set of Gaussian and hyper-Gaussian distributions. The radiation at the double frequency leads to a phase modulation of the optical radiation at the fundamental frequency, which is necessary for the formation of subpulses and subbeams and is the cause of formation of these structures. The formation of subpulses occurs at the fundamental frequency at a small efficiency (≤8%) of energy conversion into the second harmonic.

  5. Magnetic second harmonic generation in centrosymmetric CoO, NiO, and KNiF3

    Science.gov (United States)

    Fiebig, M.; Lottermoser, Th.; Pavlov, V. V.; Pisarev, R. V.

    2003-05-01

    Optical second harmonic (SH) spectroscopy in the centrosymmetric antiferromagnets CoO, NiO, and KNiF3 reveals pronounced signals below the Néel temperature which couple quadratically to the magnetic order parameter. The SH process roots in resonance enhanced magnetic-dipole and electric-dipole excitations between the 3d levels of the transition-metal ions in the crystal field. Different magnetic structures and differently oriented T and S domains are distinguished with a high degree of discrimination, thus demonstrating the feasibility of nonlinear optical techniques for a spatially resolved investigation of antiferromagnetic crystals and thin films.

  6. Polar asymmetry of La(1−δ)Al(1+δ)O3/SrTiO3 heterostructures probed by optical second harmonic generation

    International Nuclear Information System (INIS)

    By combining transport measurements and optical second harmonic generation, we have investigated heterostructures formed between crystalline thin films of LaAlO3, with varying stoichiometry and TiO2-terminated SrTiO3(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 LaAlO3 film caused by the off-centering of excess Al atoms in agreement with the theory

  7. Second harmonic FEL oscillation

    Science.gov (United States)

    Neil, George R.; Benson, S. V.; Biallas, G.; Freund, H. P.; Gubeli, J.; Jordan, K.; Myers, S.; Shinn, M. D.

    2002-05-01

    We have produced and measured for the first time second harmonic oscillation in the infrared region by the high-average-power Jefferson Lab Infrared Free Electron Laser. The finite geometry and beam emittance allows sufficient gain for lasing to occur. We were able to lase at pulse rates up to 74.85 MHz and could produce over 4.5 W average and 40 kW peak of IR power in a 40 nm FWHM bandwidth at 2925 nm. In agreement with predictions, the source preferentially lased in a TEM 01 mode. We present results of initial source performance measurements and comparisons with theory and simulation.

  8. Second-harmonic generation by a Gaussian beam on a fourth-order optical nonlinearity in the interior of an isotropic and gyrotropic medium

    International Nuclear Information System (INIS)

    A theoretical investigation is made of second- harmonic generation in the interior of an isotropic and gyrotropic medium on a fourth-order optical nonlinearity. It is shown that a correct description of this experimentally detected effect requires taking into account the spatially finite nature of the fundamental-frequency wave, giving rise to a small longitudinal (directed along the beam axis) component of the electric field. Quadrature formulas are derived for the transverse distribution of the second harmonic field and for the total power of the harmonic. A detailed study is made of the special cases of tight focusing of the pump (fundamental-frequency) wave at the centre of a long medium and of exact phase matching. In these cases the quadrature expressions can be reduced to an analytic form. A study is reported of the characteristic features of the transverse profile of the second-harmonic intensity and of the dependence of the harmonic power on the state of polarisation of the pump wave. (nonlinear optical phenomena)

  9. Potential-well depth at amorphous-LaAlO{sub 3}/crystalline-SrTiO{sub 3} interfaces measured by optical second harmonic generation

    Energy Technology Data Exchange (ETDEWEB)

    De Luca, Gabriele; Rubano, Andrea; Gennaro, Emiliano di; Khare, Amit; Granozio, Fabio Miletto; Uccio, Umberto Scotti di; Marrucci, Lorenzo; Paparo, Domenico, E-mail: domenico.paparo@spin.cnr.it [CNR-SPIN and Dipartimento di Fisica, Università di Napoli “Federico II,” Compl. Univ. di Monte S. Angelo, v. Cintia, 80126 Napoli (Italy)

    2014-06-30

    By a combination of optical second harmonic generation and transport measurements, we have investigated interfaces formed by either crystalline or amorphous thin films of LaAlO{sub 3} grown on TiO{sub 2}-terminated SrTiO{sub 3}(001) substrates. Our approach aims at disentangling the relative role of intrinsic and extrinsic doping mechanisms in the formation of the two-dimensional electron gas. The different nature of the two mechanisms is revealed when comparing the sample response variation as a function of temperature during annealing in air. However, before the thermal treatment, the two types of interfaces show almost the same intensity of the second harmonic signal, provided the overlayer thickness is the same. As we will show, the second harmonic signal is proportional to the depth of the potential well confining the charges at the interface. Therefore, our result demonstrates that this depth is about the same for the two different material systems. This conclusion supports the idea that the electronic properties of the two-dimensional electron gas are almost independent of the doping mechanism of the quantum well.

  10. Treatment of Linear and Nonlinear Dielectric Property of Molecular Monolayer and Submonolayer with Microscopic Dipole Lattice Model: I. Second Harmonic Generation and Sum-Frequency Generation

    CERN Document Server

    Zheng, De-sheng; Liu, An-an; Wang, Hong-fei

    2007-01-01

    In the currently accepted models of the nonlinear optics, the nonlinear radiation was treated as the result of an infinitesimally thin polarization sheet layer, and a three layer model was generally employed. The direct consequence of this approach is that an apriori dielectric constant, which still does not have a clear definition, has to be assigned to this polarization layer. Because the Second Harmonic Generation (SHG) and the Sum-Frequency Generation vibrational Spectroscopy (SFG-VS) have been proven as the sensitive probes for interfaces with the submonolayer coverage, the treatment based on the more realistic discrete induced dipole model needs to be developed. Here we show that following the molecular optics theory approach the SHG, as well as the SFG-VS, radiation from the monolayer or submonolayer at an interface can be rigorously treated as the radiation from an induced dipole lattice at the interface. In this approach, the introduction of the polarization sheet is no longer necessary. Therefore, t...

  11. Theoretical investigation for Li2CuSb as multifunctional materials: Electrode for high capacity rechargeable batteries and novel materials for second harmonic generation

    International Nuclear Information System (INIS)

    Highlights: → We predict that Li2CuSb should be good electrode materials for high capacity rechargeable batteries and novel materials for SHG. → We found that intercalation of lithium leads to phase transitions, which agrees well with the experiment. → Intercalation of Li leads to increase the conductivity and break the symmetry along optical axis make the material useful for SHG application. → The microscopic second order hyperpolarizability, the vector component along the dipole moment direction is about 31.01x10-30 esu. - Abstract: Based on the first-principles electronic structure calculations, we predict that Li2CuSb should be good electrode materials for high capacity rechargeable batteries and novel materials for second harmonic generation. This prediction is based on the experimental measurements of Fransson et al. , and as step forward to do deep investigation on these materials we addressed ourselves for performing theoretical calculation. We found that intercalation of lithium leads to phase transitions, which agrees well with the experiment, increasing the conductivity of the material, and break the symmetry along the optical axis making the material useful for second harmonic generation (SHG) applications. We should emphasize that lithiated compound show very high second order optical susceptibility. We present the total charge densities in the (1 1 0) and (1 0 0) planes for the parent and lithiated phases and it was found that the parent compound shows a considerable anisotropy between the two planes in consistence with our calculated optical properties. We found that Li2CuSb possesses high second harmonic generation and its second order optical susceptibility of the total absolute value at zero frequency is equal to 142 pm/V. Based on the value of the second order optical susceptibility the microscopic second order hyperpolarizability, βijk, the vector component along the dipole moment direction is about 31.01 x 10-30 esu.

  12. 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.

  13. 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.

  14. Blue laser emission by intracavity second harmonic generation in Nd:ASL pumped by a tapered amplifier laser diode stabilized by a volume Bragg grating

    OpenAIRE

    Pabœuf, David; Lucas-Leclin, Gaëlle; Georges, Patrick; Sumpf, Bernd; Ebert, Götz; Varona, Cyrille; Loiseau, Pascal; Aka, Gérard; Ferrand, Bernard

    2008-01-01

    International audience We present the diode pumping of a Nd:ASL (Sr1-xLax-yNdyMgxAl12-x O19) crystal for second harmonic generation at 453 nm. We have developed a high-brightness pump source based on a tapered amplifier in an extended cavity with a volume Bragg grating for wavelength stabilization. A pump brightness of 110 MW.cm-2sr-1 is obtained with a linewidth lower than 80 pm at 798 nm. This laser source is used to pump a Nd:ASL crystal to obtain 300 mW at 906 nm and 53 mW at 453 nm by...

  15. 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)

    OpenAIRE

    Bian, Hong-tao; Feng, Ran-Ran; 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 sal...

  16. Properties of second harmonic generation in nonlinear optical crystals CsLiB6O10 and K2Al2B2O7

    Institute of Scientific and Technical Information of China (English)

    SONG Chun-rong; ZHAO Jian-jun; LIU Jin

    2006-01-01

    The phase-matching for nonlinear optical crystal,the nonlinear phase matching angle, effective nonlinear coefficient, walk-off angles, permitted angle, and permitted wavelength are obtained in type-Ⅰ and type-Ⅱ phase matching in ultraviolet (UV) nonlinear optical crystals CsLiB6O10(CLBO) and K2Al2B2O7 (KABO) by detailed theoretical simulation. Through analysis and comparison, the phase matching characteristics of the second harmonic generation in the crystals are discussed when the wavelengths of the basic frequency lights turn continually.

  17. Cascaded third harmonic generation in hybrid graphene-semiconductor waveguides

    CERN Document Server

    Smirnova, Daria A

    2015-01-01

    We study cascaded harmonic generation of hybrid surface plasmons in integrated planar waveguides composed of a graphene layer and a doped-semiconductor slab. We derive a comprehensive model of cascaded third harmonic generation through phase-matched nonlinear interaction of fundamental, second harmonic and third harmonic plasmonic modes supported by the structure. We show that hybrid graphene-semiconductor waveguides can simultaneously phase-match these three interacting harmonics, increasing the total third-harmonic output by a factor of 5 compared to the non-cascaded regime.

  18. DC-electric-field-induced and low-frequency electromodulation second-harmonic generation spectroscopy of $Si(001)-SiO_2$ interfaces

    CERN Document Server

    Aktsipetrov, O A; Melnikov, A V; Mishina, E D; Rubtsov, A N; Anderson, M H; Wilson, P T; Beek, M; Hu, X F; Dadap, J I; Downer, M C

    1998-01-01

    The mechanism of DC-Electric-Field-Induced Second-Harmonic (EFISH) generation at weakly nonlinear buried Si(001)-SiO$_2$ interfaces is studied experimentally in planar Si(001)-SiO$_2$-Cr MOS structures by optical second-harmonic generation (SHG) spectroscopy with a tunable Ti:sapphire femtosecond laser. The spectral dependence of the EFISH contribution near the direct two-photon $E_1$ transition of silicon is extracted. A systematic phenomenological model of the EFISH phenomenon, including a detailed description of the space charge region (SCR) at the semiconductor-dielectric interface in accumulation, depletion, and inversion regimes, has been developed. The influence of surface quantization effects, interface states, charge traps in the oxide layer, doping concentration and oxide thickness on nonlocal screening of the DC-electric field and on breaking of inversion symmetry in the SCR is considered. The model describes EFISH generation in the SCR using a Green function formalism which takes into account all ...

  19. Second-harmonic generation of the Bessel sound beam of several lobes%小瓣数贝塞尔声束的二次谐波

    Institute of Scientific and Technical Information of China (English)

    戴玉蓉; 丁德胜

    2011-01-01

    采用高斯展开法,研究了具有三个瓣的小瓣数贝塞尔声束的基波和二次谐波的传播性质.根据准线性近似下Khokhlov-Zabolotskaya-Kuznetsov方程的积分形式解,分析了媒质的声吸收(声衰减)对波束形状的影响.结果表明:吸收参量对二次谐波径向分布有很大的影响.当瓣数较少时,实际的有限孔径贝塞尔声束二次谐波仍然具有理想无限大孔径贝塞尔声束的主要特征,在近场无衍射区,径向几乎无衍射.%By the Gaussian expansion approach we investigate fundamental-and second-harmonic generation in practical Bessel beams of several lobes.The analysis is based on the integral solutions of the Khokhlov-Zabolotskaya-Kuznetsov equation under the quasilinear approximation.The influence of the medium attenuation on beam profile is considered.Numerical results show that the absorption parameter has a significant effect on the beam profile of the second harmonic.Under certain circumstances,the second harmonic of a practical Bessel beam with several lobes still has the main properties of an ideal Bessel beam of infinite aperture when it propagates within its depth of field.

  20. The effect of aggregation and orientation of amphiphilic molecules on second-harmonic generation within Langmuir-Blodgett films

    International Nuclear Information System (INIS)

    A number of Langmuir-Blodgett (LB) film forming materials have been investigated, primarily to see how the linear and nonlinear optical properties are affected by the molecular orientation and packing. LB films of hemicyanine dyes, all with the same chromophore moiety were studied. The E-N-alkyl-4-(2-(4-(N-ethyl-N-octadecylaminophenyl))ethenyl)pyridinium halide {n-PXA-18 (2)} series and the E-N-alkyl-4-(2-(4-octadecylaininophenyl)ethenyl) pyridinium halide {n-PXA 18} series, which all have two alkyl moieties (two-legged) attached to the hemicyanine chromophore. Also studied were, E-N-methyl-4-(2-(4-(N-methyl-N-octadecylaminophenyl))ethenyl)pyridinium iodide {1 PIA 18 (1)} and E-Noctadecyl-4-(2-(4-(N-dimethylaminophenyl))ethenyl)pyridinium iodide {18 PIA 1 (1)}, which both have a single 18 carbon alkyl chain. The molecular orientation and packing were found to be influenced by the number, lengths and positions of the attached alkyl moieties, and this was reflected in the nonlinear optical properties of their deposited LB films. A centrosymmetric pyrrole squaraine dye, bis (3,5-dimethyl-1-octadecyl pyrrol-2-yl) squaraine {III}, and the non-centrosymmetric oligomeric 1-octadecyl- pyrrole-2-yl squaraine dye derivatives {I} and {II}, are shown to have weak second-harmonic intensities relative to the LB films of the centrosymmetric anilinosquaraine dyes. Two component (or binary) LB films were also studied: 2-(4-dicyanomethylene-cyclohexa-2,5-dienylidene) -4,5-octadecylthio-1,3-dithiol= e (DCDOD) mixed with 2,4-bis[4-(N-methyl-N-dodecylamino)phenyl]squaraine (MDPSQ), and 7,7,8,8-tetracyanoquinodimethane (TCNQ) also mixed with MDPSQ. The DCDOD:MDPSQ mixture is miscible at the air-water interface, and it is shown that the SH intensity of MDPSQ is diminished when DCDOD is also present in the LB film. TCNQ:MDPSQ are not fully miscible and it is thought that TCNQ forms a 3-D aggregate film at the air-water interface with a principally squaraine Langmuir film above it. The SH

  1. Multiple copies of orbital angular momentum states through second-harmonic generation in a two-dimensional periodically poled LiTaO{sub 3} crystal

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Xinyuan; Wei, Dunzhao; Liu, Dongmei; Zhong, Weihao; Ni, Rui; Chen, Zhenhua; Hu, Xiaopeng; Zhang, Yong, E-mail: zhangyong@nju.edu.cn; Zhu, S. N. [National Laboratory of Solid State Microstructures, College of Engineering and Applied Sciences and School of Physics, Nanjing University, Nanjing 210093 (China); Xiao, Min, E-mail: mxiao@uark.edu [National Laboratory of Solid State Microstructures, College of Engineering and Applied Sciences and School of Physics, Nanjing University, Nanjing 210093 (China); Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701 (United States)

    2015-10-19

    We experimentally demonstrate multiple copies of optical orbital angular momentum (OAM) states through quasi-phase-matched (QPM) second-harmonic (SH) generation in a 2D periodically poled LiTaO{sub 3} (PPLT) crystal. Since the QPM condition is satisfied by involving different reciprocal vectors in the 2D PPLT crystal, collinear and noncollinear SH beams carrying OAMs of l{sub 2} are simultaneously generated by the input fundamental beam with an OAM of l{sub 1}. The OAM conservation law (i.e., l{sub 2} = 2l{sub 1}) holds well in the experiment, which can tolerate certain phase-mismatch between the interacting waves. Our results provide an efficient way to obtain multiple copies of the wavelength-converted OAM states, which can be used to enhance the capacity in optical communications.

  2. Multiple copies of orbital angular momentum states through second-harmonic generation in a two-dimensional periodically poled LiTaO3 crystal

    International Nuclear Information System (INIS)

    We experimentally demonstrate multiple copies of optical orbital angular momentum (OAM) states through quasi-phase-matched (QPM) second-harmonic (SH) generation in a 2D periodically poled LiTaO3 (PPLT) crystal. Since the QPM condition is satisfied by involving different reciprocal vectors in the 2D PPLT crystal, collinear and noncollinear SH beams carrying OAMs of l2 are simultaneously generated by the input fundamental beam with an OAM of l1. The OAM conservation law (i.e., l2 = 2l1) holds well in the experiment, which can tolerate certain phase-mismatch between the interacting waves. Our results provide an efficient way to obtain multiple copies of the wavelength-converted OAM states, which can be used to enhance the capacity in optical communications

  3. Multiple copies of orbital angular momentum states through second-harmonic generation in a two-dimensional periodically poled LiTaO3 crystal

    Science.gov (United States)

    Fang, Xinyuan; Wei, Dunzhao; Liu, Dongmei; Zhong, Weihao; Ni, Rui; Chen, Zhenhua; Hu, Xiaopeng; Zhang, Yong; Zhu, S. N.; Xiao, Min

    2015-10-01

    We experimentally demonstrate multiple copies of optical orbital angular momentum (OAM) states through quasi-phase-matched (QPM) second-harmonic (SH) generation in a 2D periodically poled LiTaO3 (PPLT) crystal. Since the QPM condition is satisfied by involving different reciprocal vectors in the 2D PPLT crystal, collinear and noncollinear SH beams carrying OAMs of l2 are simultaneously generated by the input fundamental beam with an OAM of l1. The OAM conservation law (i.e., l2 = 2l1) holds well in the experiment, which can tolerate certain phase-mismatch between the interacting waves. Our results provide an efficient way to obtain multiple copies of the wavelength-converted OAM states, which can be used to enhance the capacity in optical communications.

  4. Experimental investigation and theoretical analysis of pulse repetition rate adjustable deep ultraviolet picosecond radiation by second harmonic generation in KBe2BO3F2

    Science.gov (United States)

    Xu, Zhi; Zhang, Fengfeng; Zhang, Shenjin; Wang, Zhimin; Yang, Feng; Xu, Fengliang; Peng, Qinjun; Cui, Dafu; Zhang, Jingyuan; Wang, Xiaoyang; Chen, Chuangtian; Xu, Zuyan

    2014-06-01

    We reported on an experimental investigation and theoretical analysis of pulse repetition rate (PRR) adjustable deep ultraviolet (DUV) picosecond (ps) radiation by second harmonic generation (SHG) in KBe2BO3F2 (KBBF) crystal. Third harmonic radiation at 355 nm of a ps Nd:YVO4 laser output with PRR of 200 kHz-1 MHz was employed as the pump source. The dependence of the 177.3 nm output power on the 355 nm pump power was measured at different PRRs, and the maximum 177.3 nm average output power of 695 μW was obtained at the PRR of 200 kHz. The measured data agreed well with the results of the ps KBBF SHG theoretical simulations. Using simulations, the pulse width and the spectral bandwidth of the generated radiation at 177.3 nm were estimated to be 5.88 ps and 7.84 pm, respectively.

  5. 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....

  6. In-situ second harmonic generation by cancer cell targeting ZnO nanocrystals to effect photodynamic action in subcellular space.

    Science.gov (United States)

    Gu, Bobo; Pliss, Artem; Kuzmin, Andrey N; Baev, Alexander; Ohulchanskyy, Tymish Y; Damasco, Jossana A; Yong, Ken-Tye; Wen, Shuangchun; Prasad, Paras N

    2016-10-01

    This paper introduces the concept of in-situ upconversion of deep penetrating near infrared light via second harmonic generation from ZnO nanocrystals delivered into cells to effect photo activated therapies, such as photodynamic therapy, which usually require activation by visible light with limited penetration through biological tissues. We demonstrated this concept by subcellular activation of a photodynamic therapy drug, Chlorin e6, excited within its strong absorption Soret band by the second harmonic (SH) light, generated at 409 nm by ZnO nanocrystals, which were targeted to cancer cells and internalized through the folate-receptor mediated endocytosis. By a combination of theoretical modeling and experimental measurements, we show that SH light, generated in-situ by ZnO nanocrystals significantly contributes to activation of photosensitizer, leading to cell death through both apoptotic and necrotic pathways initiated in the cytoplasm. This targeted photodynamic action was studied using label-free Coherent Anti-Stokes Raman Scattering imaging of the treated cells to monitor changes in the distribution of native cellular proteins and lipids. We found that initiation of photodynamic therapy with upconverted light led to global reduction in the intracellular concentration of macromolecules, likely due to suppression of proteins and lipids synthesis, which could be considered as a real-time indicator of cellular damage from photodynamic treatment. In prospective applications this in-situ photon upconversion could be further extended using ZnO nanocrystals surface functionalized with a specific organelle targeting group, provided a powerful approach to identify and consequently maximize a cellular response to phototherapy, selectively initiated in a specific cellular organelle. PMID:27442221

  7. Ion-selective charge separation at the phase boundary of ionophore-incorporated liquid membranes as studied by optical second-harmonic generation

    Science.gov (United States)

    Tohda, Koji; Yoshiyagawa, Shinji; Umezawa, Yoshio

    1997-06-01

    Optical second-harmonic generation (SHG) in various plasticized poly(vinyl chloride) (PVC)-based ion-selective membranes was observed. The SHG signal from the ionophore-incorporated membranes in contact with an aqueous solution of selective cation chloride salts generally increased with increase of the cation concentration and then levelled off. This result was explained by the formation of oriented and therefore SHG-active cation-ionophore complexes at the membrane surface. The fact that the membrane potential and SHG signal changed in parallel revealed that the observed membrane potentials were primarily governed by SHG-active oriented complex cations at the membrane surface. The effect of the ionophore structures and their cation selectivities on the SHG responses was also examined and discussed.

  8. Room-temperature 1.06-0.53-microm second-harmonic generation with MgO:LiNbO(3).

    Science.gov (United States)

    Yao, J Q; Shi, W Q; Millerd, J E; Xu, G F; Garmire, E; Birnbaum, M

    1990-12-01

    Room-temperature 1.06-0.53-microm second-harmonic generation (SHG) achieved with LiNbO(3) doped with 7 mol. % MgO has been studied. Phase matching was achieved with angle tuning. SHG conversion efficiency of 45% was obtained with a 12-mm-long crystal and a fundamental peak-power density of 140 MW/cm (2). SHG performance of MgO:LiNbO(3) is compared with that of KTP and LBO crystals. Various phase-matching parameters of MgO:LiNbO(3) were calculated as functions of the fundamental wavelength, using the experimentally determined Sellmeier equations. It was found that room-temperature, noncritically-phase-matched Type I SHG can be achieved in this crystal at 1.053 microm, where Nd:YLF lasers operate. PMID:19771083

  9. Diode-end-pumped, electro-optically Q-switched Nd:YVO4 slab laser and its second-harmonic generation.

    Science.gov (United States)

    Zhang, Hengli; Shi, Peng; Li, Daijun; Du, Keming

    2003-03-20

    We describe the operation of a near-diffraction-limited, 1,064-nm electro-optically Q-switched Nd:YVO4 slab laser that is end pumped by laser-diode stacks and its efficient second-harmonic generation by using a lithium triborate (LBO) crystal. The energy per pulse of 3.6 and 0.8 mJ and pulse widths of 5 and 13.5 ns were obtained at repetition of 5 and 40 kHz, respectively. With a LBO crystal, a maximum output power of 15.6 W at 532 nm was obtained at the repetition rate of 40 kHz, the corresponding conversion efficiency was 60%, and the pulse width was 11.3 ns. At 10 kHz, the pulse energy of 532 nm was 1.2 mJ, and the pulse width was 5 ns. PMID:12665098

  10. The second harmonic generation and the photoelectric property studies on a new dye, (E)- N-octadecyl-4-[2-(4-dimethylaminophenyl) enamine] pyridinium iodide

    Science.gov (United States)

    Zhai, Jin; Huang, Chun-Hui; Wei, Tian-Xin; Yu, An-Chi; Zhao, Xin-Sheng

    1999-03-01

    According to quantum chemistry calculation, a Schiff-base (E)- N-octadecyl-4-[2-(4-dimethylaminophenyl) enamine] pyridinium iodide with a large dipole moment difference between the excited state and the ground state (Δ μ), is designed and synthesized as a second-order non-linear optical material. Its second-order susceptibility ( χ(2)zzz) is evaluated to be 279.4 pm V -1, which is larger than that of the hemicyanine which is known as one of the best dyes in the second harmonic generation (SHG) behavior. Its LB film formation properties were studied. The photoelectric conversion property is not as good as expected. According to the experiments and the results of the quantum chemistry calculation, an explanation of this phenomenon is proposed.

  11. Probing bacteriorhodopsin photochemistry with nonlinear optics. Comparing the second harmonic generation of bR and the photochemically induced intermediate K

    Energy Technology Data Exchange (ETDEWEB)

    Bouevitch, O.; Lewis, A. [Hebrew Univ., Jerusalem (Israel); Sheves, M. [Weizmann Inst. of Science, Rehevot (Israel)

    1995-06-29

    The nonlinear optical properties of the bacteriorhodopsin chromophore in the bR568 and K states are investigated by second harmonic generation. The comparison of amplitudes and phases of the second-order nonlinear optical polarizabilities of the retinal chromophore in the two states has revealed a noticeable increase of the induced dipole of the retinal as a result of the bR568 $YLD K transition. The results have been explained in terms of recent theoretical understandings of the nonlinear optical properties of polyenes. Within the context of these understandings we have discussed the molecular origins of the light-induced color changes and the possible mechanism of photon energy storage observed in this protein. 54 refs., 8 figs., 3 tabs.

  12. 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. PMID:24787591

  13. Second-harmonic generation and theoretical studies of protonation at the water/α-TiO 2 (1 1 0) interface

    Science.gov (United States)

    Fitts, Jeffrey P.; Machesky, Michael L.; Wesolowski, David J.; Shang, Xiaoming; Kubicki, James D.; Flynn, George W.; Heinz, Tony F.; Eisenthal, Kenneth B.

    2005-08-01

    The pH of zero net surface charge (pH pzc) of the α-TiO 2 (1 1 0) surface was characterized using second-harmonic generation (SHG) spectroscopy. The SHG response was monitored during a series of pH titrations conducted at three NaNO 3 concentrations. The measured pH pzc is compared with a pH pzc value calculated using the revised MUltiSIte Complexation (MUSIC) model of surface oxygen protonation. MUSIC model input parameters were independently derived from ab initio calculations of relaxed surface bond lengths for a hydrated surface. Model (pH pzc 4.76) and experiment (pH pzc 4.8 ± 0.3) agreement establishes the incorporation of independently derived structural parameters into predictive models of oxide surface reactivity.

  14. Depth-resolved spectral imaging of rabbit oesophageal tissue based on two-photon excited fluorescence and second-harmonic generation

    Energy Technology Data Exchange (ETDEWEB)

    Chen Jianxin [Key Laboratory of Optoelectronic Science and Technology for Medicine (Fujian Normal University), Ministry of Education, Fuzhou 350007 (China); Zhuo Shuangmu [Key Laboratory of Optoelectronic Science and Technology for Medicine (Fujian Normal University), Ministry of Education, Fuzhou 350007 (China); Chen Rong [Key Laboratory of Optoelectronic Science and Technology for Medicine (Fujian Normal University), Ministry of Education, Fuzhou 350007 (China); Jiang Xingshan [Key Laboratory of Optoelectronic Science and Technology for Medicine (Fujian Normal University), Ministry of Education, Fuzhou 350007 (China); Xie Shusen [Key Laboratory of Optoelectronic Science and Technology for Medicine (Fujian Normal University), Ministry of Education, Fuzhou 350007 (China); Zou Qilian [Division of Cell Biology and Genetics, Fujian Medical University, Fuzhou 350004 (China)

    2007-07-15

    A novel depth-resolved spectral imaging based on two-photon excited fluorescence (TPEF) and second-harmonic generation (SHG) is developed for simultaneously investigating images and spectra at different depths within rabbit oesophageal tissues in backscattering geometry. Our results show that this method has a capability to identify the layered structures of oesophageal tissue including the keratinizing layer, epithelial cell layer and stromal layer, which are strongly correlated to tissue pathology. By integrating several system analysing tools, morphology and spectroscopy in different layers can be quantitatively obtained. Our findings demonstrate that this technique has the potential to provide more accurate and comprehensive information for the pathological diagnosis of tissues with stratified squamous epithelia.

  15. Synthesis of Novel Y-type Nonlinear Optical Polyester with Enhanced Thermal Stability of Second Harmonic Generation for Electro-Optic Applications

    Energy Technology Data Exchange (ETDEWEB)

    Cho, You Jin; Lee, Ju Suk; Lee, Ju Yeon [Inje University, Gimhae (Korea, Republic of)

    2010-06-15

    Methyl 3,4-di-(2'-hydroxyethoxy)benzylidenecyanoacetate was prepared and condensed with terephthaloyl chloride to yield novel Y-type polyester containing 3,4-dioxybenzylidenecyanoacetate groups as NLO-chromophores, which constituted parts of the polymer main chains. The resulting polymer 4 is soluble in common organic solvents such as acetone and N,N-dimethylformamide. Polymer 4 shows thermal stability up to 280 .deg. C in thermogravimetric analysis with glass-transition temperature obtained from differential scanning calorimetry near 105 .deg. C. The second harmonic generation (SHG) coefficient (d{sub 33}) of poled polymer films at the 1064 nm fundamental wavelength is around 2.42 pm/V. The dipole alignment exhibits high thermal stability up to near T{sub g}, and there is no SHG decay below 100 .deg. C due to the partial main-chain character of polymer structure, which is acceptable for NLO device applications.

  16. Transition from out-of-plane to in-plane contribution for the optical second harmonic generation response from a silver metallic nanoparticle film

    Energy Technology Data Exchange (ETDEWEB)

    El Harfouch, Yara; Benichou, Emmanuel; Pu, Lin; Bachelier, Guillaume; Russier-Antoine, Isabelle; Jonin, Christian; Brevet, Pierre-Francois, E-mail: Emmanuel.Benichou@lasim.univ-lyon1.fr [Laboratoire de Spectrometrie Ionique et Moleculaire, Universite Claude Bernard Lyon 1-CNRS (UMR 5579), Batiment Alfred Kastler, 43 boulevard du 11 Novembre 1918, F-69622 Villeurbanne Cedex (France)

    2011-06-29

    The time evolution of the second harmonic generation (SHG) intensity during the formation of a silver spherical nanoparticle film at the water/1,2-dichloroethane interface is reported. The 5 nm diameter silver nanoparticles were initially dispersed in the water phase and their precipitation at the interface was triggered with the addition of sodium chloride. The time evolution of the SHG intensity exhibited two distinct regimes. First, an intensity increase was observed during the film formation with the deposition and the reorganization of the nanoparticles at the interface. Then, a slow decrease of the intensity due to rearrangements within the film was observed. Polarization-resolved experiments were also performed and showed that the initial dominant out-of-plane contribution of the quadratic nonlinearity underwent a reorientational change towards a dominant in-plane contribution associated with a smoother but still discontinuous metallic film.

  17. Synthesis of Novel Y-type Nonlinear Optical Polyester with Enhanced Thermal Stability of Second Harmonic Generation for Electro-Optic Applications

    International Nuclear Information System (INIS)

    Methyl 3,4-di-(2'-hydroxyethoxy)benzylidenecyanoacetate was prepared and condensed with terephthaloyl chloride to yield novel Y-type polyester containing 3,4-dioxybenzylidenecyanoacetate groups as NLO-chromophores, which constituted parts of the polymer main chains. The resulting polymer 4 is soluble in common organic solvents such as acetone and N,N-dimethylformamide. Polymer 4 shows thermal stability up to 280 .deg. C in thermogravimetric analysis with glass-transition temperature obtained from differential scanning calorimetry near 105 .deg. C. The second harmonic generation (SHG) coefficient (d33) of poled polymer films at the 1064 nm fundamental wavelength is around 2.42 pm/V. The dipole alignment exhibits high thermal stability up to near Tg, and there is no SHG decay below 100 .deg. C due to the partial main-chain character of polymer structure, which is acceptable for NLO device applications

  18. Polarization-sensitive second harmonic generation microscopy of α-quartz like GeO2 (α-GeO2) polycrystal

    International Nuclear Information System (INIS)

    The usefulness of polarized second harmonic generation (SHG) microscopy to determine crystallographic orientations of domains in polycrystalline films was demonstrated. Orientation of α-quartz like GeO2 (α-GeO2) domains in polycrystalline films were investigated by using polarized SHG and Raman microscopy. It was found that the SHG intensity of a α-GeO2 polycrystalline film depends strongly on measurement points and excitation and detection polarizations, while the Raman intensity was almost uniform in the whole mapping area. Analyses of the SHG mappings in different polarization conditions allowed us to determine not only the size and shape of crystalline domains, but also the crystallographic orientations. (paper)

  19. Second Harmonic Generation Using an All-Fiber Q-Switched Yb-Doped Fiber Laser and MgO:c-PPLN

    Directory of Open Access Journals (Sweden)

    Yi Gan

    2008-01-01

    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.

  20. Studies of sub-millisecond domain dynamics in periodically poled Rb-doped KTiOPO(4), using online in situ second harmonic generation.

    Science.gov (United States)

    Lindgren, Gustav; Zukauskas, Andrius; Pasiskevicius, Valdas; Laurell, Fredrik; Canalias, Carlota

    2015-08-10

    The temporal evolution of in situ second-harmonic generation was employed to study domain dynamics during periodic poling in Rb-doped KTP. With this method we investigated the influence of various poling parameters, including electric-field pulse shape, pulse magnitude, and number of pulses, on the quality of the QPM structure. It was found that the grating formation can be a sub-millisecond process and the benefits of using symmetric triangular electric-field pulse shape over square pulse shape in the single-pulse poling regime were demonstrated. Multiple-pulse poling with triangular pulses was shown to have a detrimental effect on the QPM structure quality, while multiple square pulses can provide additional flexibility to the structuring process. PMID:26367888

  1. Second-harmonic generation in periodically poled bulk Rb-doped KTiOPO₄ below 400 nm at high peak-intensities.

    Science.gov (United States)

    Zukauskas, Andrius; Pasiskevicius, Valdas; Canalias, Carlota

    2013-01-28

    We demonstrate that bulk Rb-doped KTiOPO₄ (RKTP) shows improved susceptibility to gray-tracking compared to flux-grown KTiOPO₄ . We show high-fidelity periodic poling of 1 mm thick RKTP with a period of 3.18 µm for second harmonic generation at 398 nm with a normalized conversion efficiency of 1.79%/Wcm. The crystal is used to frequency-double 138 fs-long pulses with an efficiency of 20% and a peak intensity of 560 MW/cm² without visible gray-tracking signs. We demonstrate that two-photon absorption is the predominant mechanism limiting the SHG efficiency in this spectral range at high peak powers and high repetition rates. PMID:23389121

  2. 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.

  3. Synthesis and Characterization of Electroresponsive Materials with Applications In: Part I. Second Harmonic Generation. Part II. Organic-Lanthanide Ion Complexes for Electroluminescence and Optical Amplifiers.

    Science.gov (United States)

    Claude, Charles

    1995-01-01

    Materials for optical waveguides were developed from two different approaches, inorganic-organic composites and soft gel polymers. Inorganic-organic composites were developed from alkoxysilane and organically modified silanes based on nonlinear optical chromophores. Organically modified silanes based on N-((3^' -trialkoxysilyl)propyl)-4-nitroaniline were synthesized and sol-gelled with trimethoxysilane. After a densification process at 190^circC with a corona discharge, the second harmonic of the film was measured with a Nd:YAG laser with a fundamental wavelength of 1064nm, d_{33} = 13pm/V. The decay of the second harmonic was expressed by a stretched bi-exponential equation. The decay time (tau _2) was equal to 3374 hours, and was comparable to nonlinear optical systems based on epoxy/Disperse Orange 1. The processing temperature of the organically modified silane was limited to 200^circC due to the decomposition of the organic chromophore. Soft gel polymers were synthesized and characterized for the development of optical waveguides with dc-electrical field assisted phase-matching. Polymers based on 4-nitroaniline terminated poly(ethylene oxide-co-propylene oxide) were shown to exhibit second harmonic generation that were optically phase-matched in an electrical field. The optical signals were stable and reproducible. Siloxane polymers modified with 1-mercapto-4-nitrobenzene and 1-mercapto-4-methylsulfonylstilbene nonlinear optical chromophores were synthesized. The physical and the linear and nonlinear optical properties of the polymers were characterized. Waveguides were developed from the polymers which were optically phase -matched and had an efficiency of 8.1%. The siloxane polymers exhibited optical phase-matching in an applied electrical field and can be used with a semiconductor laser. Organic lanthanide ion complexes for electroluminescence and optical amplifiers were synthesized and characterized. The complexes were characterized for their thermal and

  4. Second-harmonic generation of biological interfaces: probing the membrane protein bacteriorhodopsin and imaging membrane potential around GFP molecules at specific sites in neuronal cells of C. elegans

    Science.gov (United States)

    Lewis, Aaron; Khatchatouriants, Artium; Treinin, Millet; Chen, Zhongping; Peleg, Gadi; Friedman, Noga; Bouevitch, Oleg; Rothman, Zvi; Loew, Leslie; Sheres, Mordechai

    1999-07-01

    Second-harmonic generation (SHG) is applied to problems of probing membrane proteins and functionally imaging around selective sites and at single molecules in biological membranes. The membrane protein bacteriorhodopsin (bR) has been shown to have large second-harmonic (SH) intensities that are modulated by protein/retinylidene chromophore interactions. The nonlinear optical properties of model compounds, which simulate these protein chromophore interactions in retinal proteins, are studied in this work by surface SHG and by hyper-Rayleigh scattering. Our results indicate that non-conjugated charges and hydrogen bonding effects have a large effect on the molecular hyperpolarizability of the retinal chromophore. However, mbR, the model system studies suggest that polarizable amino acids strongly affect the vertically excited state of the retinylidene chromophore and appear to play the major role in the observed protein enhancement (>50%) of the retinylidene chromophore molecular hyperpolarizability and associated induced dipole. Furthermore, the data provide insights on emulating these interactions for the design of organic nonlinear optical materials. Our studies have also led to the development of dyes with large SH intensities that can be embedded in cell membranes and can functionally image membrane potential. Single molecules of such dyes in selected single molecular regions of a cell membrane have been detected. SHG from green fluorescent protein (GFP) selectively expressed in concert with a specific protein in neuronal cells in a transgenic form of the worm C. elegans is also reported. The membrane potential around the GFP molecules expressed in these cells has been imaged with SHG in live animals.

  5. 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 maxim...... 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....

  6. Few-cycle nonlinear mid-IR pulse generated with cascaded quadratic nonlinearities

    DEFF Research Database (Denmark)

    Bache, Morten; Liu, Xing; Zhou, Binbin

    Generating few-cycle energetic and broadband mid-IR pulses is an urgent current challenge in nonlinear optics. Cascaded second-harmonic generation (SHG) gives access to an ultrafast and octave-spanning self-defocusing nonlinearity: when ΔkL >> 2π the pump experiences a Kerr-like nonlinear index...

  7. Efficient Ultraviolet Second-Harmonic Generation from a Walk-Off-Compensating β-BaB2O4 Device with a New Structure Fabricated by Room-Temperature Bonding

    Science.gov (United States)

    Hara, Kenjiro; Matsumoto, Shinnosuke; Onda, Tomomi; Nagashima, Wataru; Shoji, Ichiro

    2012-05-01

    We have fabricated a second-harmonic-generation device with a new walk-off-compensating structure of β-BaB2O4 (BBO) by room-temperature bonding. The 5-mm-long device, which consists of four 1-mm-thick plates and additional input and output plates of 0.5 mm thickness, generated nearly twice the UV second-harmonic power compared with a bulk BBO crystal. Moreover, we found that the device can improve the beam shape of the output UV light, which is otherwise degraded in a bulk crystal due to the walk-off effect.

  8. Analysis of current-voltage characteristics of Au/pentacene/fluorine polymer/indium zinc oxide diodes by electric-field-induced optical second-harmonic generation

    International Nuclear Information System (INIS)

    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

  9. 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.

  10. 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.; Bache, Morten

    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.......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....

  11. 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...

  12. 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%. PMID:19997395

  13. 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 ...

  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. 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.

  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. Resonant enhancement of second harmonic generation in the mid-infrared using localized surface phonon polaritons in sub-diffractional nanostructures

    CERN Document Server

    Razdolski, Ilya; Giles, Alexander J; Gewinner, Sandy; Schöllkopf, Wieland; Minghui, Hong; Wolf, Martin; Giannini, Vincenzo; Caldwell, Joshua D; Maier, Stefan A; Paarmann, Alexander

    2016-01-01

    We report on strong enhancement of mid-infrared second harmonic generation (SHG) from SiC nanopillars due to the resonant excitation of localized surface phonon-polaritons within the Reststrahlen band. The magnitude of the SHG peak at the monopole mode experiences a strong dependence on the resonant frequency beyond that described by the field localization degree and the dispersion of linear and nonlinear-optical SiC properties. Comparing the results for the identical nanostructures made of 4H and 6H SiC polytypes, we demonstrate the interplay of localized surface phonon polaritons with zone-folded weak phonon modes of the anisotropic crystal. Tuning the monopole mode in and out of the region where the zone-folded phonon is excited in 6H-SiC, we observe a prominent increase of the already monopole-enhanced SHG output when the two modes are coupled. Envisioning this interplay as one of the showcase features of mid-infrared nonlinear nanophononics, we discuss its prospects for the effective engineering of nonli...

  18. Intramolecular electron density redistribution upon hydrogen bond formation in the anion methyl orange at the water/1,2-dichloroethane interface probed by phase interference second harmonic generation

    Science.gov (United States)

    Rinuy; Piron; Brevet; Blanchard-Desce; Girault

    2000-09-15

    Surface second harmonic generation (SSHG) studies of the azobenzene derivative p-dimethylaminoazobenzene sulfonate, often referred as Methyl Orange (MO), at the neat water/1,2-dichloroethane (DCE) interface is reported. The two forms of the anionic MO dye, which are usually observed in bulk solution, with one form being hydrogen bonded to a water molecule through the azo nitrogens (MO/H2O) and the other form not being hydrogen bonded (MO) have also been observed at the water/DCE interface. Their equilibrium constant has been compared with the corresponding bulk solution and found to be identical. The adsorption equilibrium of the two forms has been determined and the Gibbs energy of adsorption measured to be -30 kJmol(-1) for both forms. From a light polarisation analysis of the SH signal, the angle of orientation of the MO transition dipole moment was found to be 34 +/- 2 degrees for MO and 43 +/- 2 degrees for MO/H2O under the assumption of a Dirac delta function for the angle distribution, a difference explained by the different solvation properties of the two forms. Furthermore, the wavelength dependence analysis of these data revealed an interference pattern resulting from the electronic density redistribution within the hydrated anionic form occurring upon the formation of the hydrogen bond with a water molecule. This interference pattern was clearly evidenced with the use of another dye at the interface in order to define a phase reference to both forms of Methyl Orange. PMID:11039537

  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. 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.

  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. 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.

  5. 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.

  6. 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.

  7. 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.; Wise, F.W.

    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....

  8. Study on heavy matching layer transducer towards producing second harmonics

    Science.gov (United States)

    Zaini, Zulfadhli; Osuga, Masamizu; Jimbo, Hayato; Yasuda, Jun; Takagi, Ryo; Yoshizawa, Shin; Umemura, Shin-ichiro

    2016-07-01

    Cavitation bubbles are microbubbles which can be incepted by highly negative pressure. Producing such highly negative pressure exceeding the cavitation threshold is difficult to accomplish due to nonlinear propagation followed by focal phase shift. By superimposing the second harmonic to fundamental is a way to significantly reduce the problem. However, the conventional design for an air-backed transducer is not suitable to generate both the second harmonic and fundamental at the same time. In order to overcome this problem, we propose a high impedance matching layer approach. Furthermore, we also construct a study to foresee the impact by adjusting the thickness ratio towards fundamental and second harmonic. Numerical simulation and experimental measurement have shown that by using a high impedance matching layer, efficiently generation of both the second harmonic (2 MHz) and fundamental (1 MHz) at the same time is possible. Besides, by adjusting the thickness ratio between piezocomposite and heavy matching layer will influence the amplitude of acoustic power over squared of voltage of the fundamental and second harmonic.

  9. Second harmonic interference patterns of ion-acoustic waves

    International Nuclear Information System (INIS)

    The interaction of two weakly nonlinear sinusoidal ion-acoustic waves produces mainly a fundamental and a second harmonic diffraction pattern. The former is similar to the double slit pattern well known from physical optics, while it is found that the latter resembles a linear pattern generated by the superposition of three waves. The third wave is formed by mutual nonlinear interaction of the two fundamental waves. The intensity of the second harmonic pattern is modulated by the recurrence effect and it depends also on the angle between the local wave vectors. (author)

  10. Second-harmonic imaging of ferroelectric domain walls

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.; Hvam, Jørn Märcher; Pedersen, Kjeld; Laurell, Fredrik; Karlsson, Håkan; Skettrup, Torben; Belmonte, Michele

    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 configur...

  11. Second-harmonic imaging of poled silica waveguides

    DEFF Research Database (Denmark)

    Arentoft, Jesper; Pedersen, Kjeld; Bozhevolnyi, Sergey I.;

    2000-01-01

    Electric-field poled silica-based waveguides are characterized by measurements of second-harmonic generation (SHG) and of the linear electro-optic effect (LEO). A SHG scanning technique allowing for high-resolution imaging of poled devices is demonstrated. Scans along the direction of the poling...

  12. Second harmonic generation at 399 nm resonant on the $^{1}S_{0}-^{1}P_{1}$ transition of ytterbium using a periodically poled LiNbO$_{3}$ waveguide

    CERN Document Server

    Kobayashi, Takumi; Nishida, Yoshiki; Tanabe, Takehiko; Yasuda, Masami; Hong, Feng-Lei; Hosaka, Kazumoto

    2016-01-01

    We demonstrate a compact and robust method for generating a 399-nm light resonant on the $^{1}S_{0}-^{1}P_{1}$ transition in ytterbium using a single-pass periodically poled LiNbO$_{3}$ waveguide for second harmonic generation (SHG). The obtained output power at 399 nm was 25 mW when a 798-nm fundamental power of 380 mW was coupled to the waveguide. We observed no degradation of the SHG power for 13 hours with a low power of 6 mW. The obtained SHG light has been used as a seed light for injection locking, which provides sufficient power for laser cooling ytterbium.

  13. 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.

  14. 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.

  15. Observation of turnover of spontaneous polarization in ferroelectric layer of pentacene/poly-(vinylidene-trifluoroethylene) double-layer capacitor under photo illumination by optical second-harmonic generation measurement

    Science.gov (United States)

    Shi, Zhemin; Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa

    2016-04-01

    The details of turnover process of spontaneous polarization and associated carrier motions in indium-tin oxide/poly-(vinylidene-trifluoroethylene)/pentacene/Au capacitor were analyzed by coupling displacement current measurement (DCM) and electric-field-induced optical second-harmonic generation (EFISHG) measurement. A model was set up from DCM results to depict the relationship between electric field in semiconductor layer and applied external voltage, proving that photo illumination effect on the spontaneous polarization process lied in variation of semiconductor conductivity. The EFISHG measurement directly and selectively probed the electric field distribution in semiconductor layer, modifying the model and revealing detailed carrier behaviors involving photo illumination effect, dipole reversal, and interfacial charging in the device. A further decrease of DCM current in the low voltage region under illumination was found as the result of illumination effect, and the result was argued based on the changing of the total capacitance of the double-layer capacitors.

  16. Thermo-optic dispersion formula for the ordinary wave in 5 mol% MgO doped LiNbO3 and its application to temperature insensitive second-harmonic generation

    Science.gov (United States)

    Umemura, Nobuhiro; Matsuda, Daisuke

    2016-05-01

    We report the high accuracy thermo-optic dispersion formula for the ordinary wave of 5 mol% MgO doped congruent LiNbO3 (MgO:LiNbO3), which reproduces well our experimental data for the temperature-dependent birefringent phase-matching (BPM) and quasi-phase-matching (QPM) conditions with the oo-e, oo-o, and oe-o interactions in the 0.41-3.7 μm range. In addition, we found the temperature insensitive quasi-phase-matched second-harmonic generation (QPM/SHG) points exist in periodically poled MgO:LiNbO3 (MgO:PPLN) with the oo-o and oe-o interactions for the first time.

  17. Watt-level second-harmonic generation at 589  nm with a PPMgO:LN ridge waveguide crystal pumped by a DBR tapered diode laser.

    Science.gov (United States)

    Bege, R; Jedrzejczyk, D; Blume, G; Hofmann, J; Feise, D; Paschke, K; Tränkle, G

    2016-04-01

    A DBR tapered diode laser in continuous wave operation was used to generate second-harmonic radiation at 589 nm in a PPMgO:LN ridge waveguide crystal. An optical output power of 0.86 W at an optical-to-optical and an electrical-to-optical efficiency of 42% and 11%, respectively, was achieved. The visible radiation was characterized by a spectral bandwidth ΔνFWHM of 230 MHz and a beam propagation parameter M1/e22 better than 1.1. The integration of such a system into a housing of a small footprint will enable a portable and highly efficient module featuring a visible output power in the watt-level range. PMID:27192279

  18. 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.

  19. Electronic properties of the n-type PDI8-CN2 organic semiconductor at the interface with SiO2: addressing the role of adsorbed water molecules by means of optical second-harmonic generation

    International Nuclear Information System (INIS)

    We investigate the interfacial electronic properties of N,N’-bis(n-octyl)-(1,7 and 1,6)-dicyanoperylene-3,4:9,10-bisdicarboximide (PDI8-CN2) organic semiconductor films grown on silicon dioxide (SiO2) by polarization-resolved second harmonic generation optical spectroscopy. The analysis shows a non-uniform distribution of charge carriers in PDI8-CN2, whose spatial profile is affected by hydrophobic passivation of SiO2 surfaces by hexamethyldisilazane. An interpretation model strengthened by photoluminescence analysis is developed, based on the presence of the net charge localized at the SiO2 surface and on consequent charge redistribution in the organic semiconductor. Considerations are expounded suggesting a common and ‘universal’ mechanism for the bias stress effect in p-channel and n-channel organic field-effect transistors, related to proton migration toward SiO2 gate dielectrics. (paper)

  20. Digital holography for second harmonic microscopy

    Science.gov (United States)

    Shaffer, E.; Depeursinge, C.

    2010-02-01

    Quantitative phase images make digital holographic microscopy (DHM) an excellent instrument for metrological, but also for biological applications, where it can reveal deformations and morphological details at ultrahigh resolution in the order of a few nanometers only, while also precisely determining the refractive index across a sample (e.g. cell or neuron). On the other hand, non-linear light-matter interactions have also proved very useful in microscopy. For instance, second harmonic generation (SHG) allows marker-free identification of cell structures, tubulin or membranes and, because of its coherent nature, SHG is very sensitive to the local sample structure and to the direction of the laser polarization. In addition, since SHG does not result from light absorption and subsequent re-emission, in opposition to fluorescence, photo-bleaching of the studied material can be avoided by a judicious selection of the laser wavelength. These characteristics make SHG very interesting for biomedical imaging. We have designed and built a microscope that combines the fast and precise DHM imaging with tagging capabilities of non-linear light-matter interactions. Here, we present the technique and look into its possible applications to biological and life sciences. Among promising applications is the 3D tracking of colloidal gold nanoparticles.

  1. High-average-power (15-W) 255-nm source based on second-harmonic generation of a copper laser master oscillator power amplifier system in cesium lithium borate

    Science.gov (United States)

    Brown, Daniel J. W.; Withford, Michael J.

    2001-12-01

    We have generated 15 W of UV (255-nm) radiation with an optical conversion efficiency of 28% by frequency doubling the 510.6-nm output of a high-beam-quality, high-power copper laser system in cesium borate lithium (CLBO). We found that the superior performance of CLBO relative to β-barium borate is attributable largely to the small UV absorption and wide temperature acceptance bandwidth of CLBO, which reduces thermal dephasing during high-power UV generation.

  2. High efficiency, high energy second-harmonic generation of Nd:glass laser radiation in large aperture CsLiB6O10 crystals

    International Nuclear Information System (INIS)

    We have demonstrated the generation of a high-energy green laser pulse using large aperture CsLiB6O10 (CLBO) crystals. A pulsed energy of 25 J at 532-nm was generated using the 1064-nm incident Nd:glass laser radiation with an energy of 34 J. High conversion efficiency of 74% at intensities of only 370 MW/cm2 was obtained using a two-stage crystal architecture. This result represents the highest green pulse energy ever reported using the CLBO crystals. We discuss in detail the design and performance of SHG using CLBO crystals. (author)

  3. 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....

  4. 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.

  5. 4.7-W, 255-nm source based on second-harmonic generation of a copper-vapor laser in cesium lithium borate.

    Science.gov (United States)

    Trickett, R I; Withford, M J; Brown, D J

    1998-02-01

    We have generated 4.7 W of UV (255-nm) radiation with wall plug efficiency of 0.12% by frequency doubling the green (511-nm) output of a kinetically enhanced medium-scale copper-vapor laser (CVL) in cesium lithium borate (CLBO). Frequency doubling in beta -barium borate produced 3.9 W of UV radiation with wall plug efficiency of 0.1%. We found that conversion was better with CLBO because of the reduced constraints on CVL beam quality, less UV absorption, and smaller UV walk-off. PMID:18084455

  6. Multi-beam second-harmonic generation in beta barium borate with a spatial light modulator and application to internal structuring in poly(methyl methacrylate)

    Science.gov (United States)

    Liu, D.; Perrie, W.; Kuang, Z.; Scully, P. J.; Baum, A.; Liang, S.; Edwardson, S. P.; Fearon, E.; Dearden, G.; Watkins, K. G.

    2012-06-01

    Parallel beam frequency doubling of 170 fs, NIR pulses is demonstrated by placing a thin beta barium borate (BBO) nonlinear crystal after a spatial light modulator. Computer-generated holograms applied to the spatial light modulator create 18 parallel diffracted beams at the fundamental wavelength λ=775 nm, then frequency doubled to λ=387 nm and focussed inside the poly(methyl methacrylate) (PMMA) substrate for refractive index structuring. This procedure, demonstrated for the first time in PMMA, requires careful attention to phase matching of multiple beams and opens up dynamic parallel processing at UV wavelengths where nematic liquid crystal devices are more sensitive to optical damage. By overlapping filamentary modifications, an efficient, stable volume phase grating with dimensions 5×5×2.0 mm3 and pitch Λ=15 μm was fabricated in 18 minutes and reached a first-order diffraction efficiency of 70 % at the Bragg angle.

  7. Broadband asymmetric conical emission via cascaded second-order nonlinear polarization during the propagation of femtosecond laser pulses in a BBO crystal

    International Nuclear Information System (INIS)

    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. (authors)

  8. Monolithic AlGaAs second-harmonic nanoantennas

    CERN Document Server

    Gili, V F; Locatelli, A; Rocco, D; Finazzi, M; Ghirardini, L; Favero, I; Gomez, C; Lemaître, A; Celebrano, M; De Angelis, C; Leo, G

    2016-01-01

    We demonstrate monolithic aluminum gallium arsenide (AlGaAs) optical anoantennas. Using a selective oxidation technique, we fabricate such epitaxial semiconductor nanoparticles on an aluminum oxide substrate. Second harmonic generation from an AlGaAs nanocylinder of height h=400 nm and varying radius pumped with femtosecond pulses delivered at 1554-nm wavelength has been measured, revealing a peak conversion efficiency exceeding 10-5 for nanocylinders with an otpimized geometry.

  9. 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.

  10. Spontaneous noncollinear second harmonic generation in GUHP

    Czech Academy of Sciences Publication Activity Database

    Kroupa, Jan; Fridrichová, M.

    2011-01-01

    Roč. 13, č. 3 (2011), s. 1-7. ISSN 2040-8978 R&D Projects: GA ČR GA203/09/0878 Institutional research plan: CEZ:AV0Z10100520 Keywords : nonlinear optics * scattering, polarization * nterference * crystal optics Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.573, year: 2011 http://iopscience.iop.org/2040-8986

  11. Simulation of Second Harmonic Ultrasound Fields

    OpenAIRE

    Du, Yigang; Jensen, Henrik; Jensen, Jørgen Arendt

    2010-01-01

    A non-linear ultrasound imaging simulation software should be capable of simulating the non-linear fields for any kind of transducer, focusing, apodization, and attenuation. At present, a major issue is the overlong simulation time of the non-linear software. An Angular Spectrum Approach (ASA) using a quasi-linear approximation for solving the Westervelt equation can simulate the second harmonic pressure at any distance. Therefore, it shortens the execution time compared with the operator spl...

  12. A way for studying the impact of PEDOT:PSS interface layer on carrier transport in PCDTBT:PC71BM bulk hetero junction solar cells by electric field induced optical second harmonic generation measurement

    International Nuclear Information System (INIS)

    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:PC71BM bulk heterojunction (BHJ) organic solar cells (OSCs). We revealed that the electric fields in the PCDTBT and PC71BM 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:PC71BM 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

  13. 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.

  14. 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.

  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. 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. PMID:23722739

  17. Characterization of the second-harmonic response of a silver–air interface

    OpenAIRE

    K.A. O'DONNELL; Torre, R.

    2005-01-01

    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 determi...

  18. Stokes vector based polarization resolved second harmonic microscopy of starch granules

    OpenAIRE

    Mazumder, Nirmal; Qiu, Jianjun; Foreman, Matthew R.; Romero, Carlos Macías; Török, Peter; Kao, Fu-Jen

    2013-01-01

    We report on the measurement and analysis of the polarization state of second harmonic signals generated by starch granules, using a four-channel photon counting based Stokes-polarimeter. Various polarization parameters, such as the degree of polarization (DOP), the degree of linear polarization (DOLP), the degree of circular polarization (DOCP), and anisotropy are extracted from the 2D second harmonic Stokes images of starch granules. The concentric shell structure of a starch granule forms ...

  19. Second-harmonic illumination to enhance multispectral digital lensless holographic microscopy

    OpenAIRE

    Mendoza Yero, Omel; Carbonell Leal, Miguel; Lancis Sáez, Jesús; García Sucerquia, Jorge

    2016-01-01

    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...

  20. 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. PMID:26974116

  1. Theoretical analysis of Cherenkov third harmonic generation via two cascaded χ(2) processes in a waveguide

    International Nuclear Information System (INIS)

    We report a comprehensive numerical study of a type of quasi-phase-matched Cherenkov third harmonic generation in a nonlinear waveguide, and this Cherenkov third harmonic generation consists of a guided-to-guided second harmonic generation cascaded with a guided-to-radiated sum-frequency generation. Following the coupled-mode theory, the temperature-detuning characteristics of third harmonic (TH) radiation under different pumping-power densities were studied. TH power dependences on interaction length have been discussed as well, which includes three situations: without reciprocal vector participating, and forward and backward reciprocal vector participating. In addition, we demonstrate that the Cherenkov angle of each TH radiation is not sensitive to the temperature variation. (paper)

  2. CW Second Harmonic Generation of 507 nm with Waveguide PPLN%用波导结构的周期极化铌酸锂产生507nm的连续倍频输出

    Institute of Scientific and Technical Information of China (English)

    肖辉星; 贺凌翔

    2012-01-01

    稀土金属镱原子的3P2态是镱原子的一个很重要的长寿命亚稳态,为了研究将跃迁1S0→3 P2作为镱原子钟跃迁的可能性,通过507nm的激光场进行激发而实现态制备.实验中利用波导型周期极化铌酸锂作为倍频晶体的单次倍频方式,采用了一种简单的短焦距单透镜耦合方式,获得了507nm的连续光输出.结果表明,采用焦距为20mm的单透镜将58mW的1 014nm基频光直接耦合到波导结构的周期极化铌酸锂,得到了86.5μW的507nm倍频光.同时,给出了倍频输出光的输出功率与温度的关系曲线.对比传统的裸光纤直接耦合方式,单透镜直接耦合方式优于光纤耦合的倍频效率.%3P2 state of rare-earth-metal ytterbium atoms is a very important meta-stable state with long lifetime. In order to study probability of 11S0→3 P2transition as a clock transition for ytterbium atoms, state preparation has to be realized with help of 507 nm light field. In order to obtain second harmonic generation(SHG) of 507 nm with a waveguide periodically poled lithium niobate nonlinear crystal (WG PPLN), a simple coupling method with single short-focus lens was adopted. Experimental results show that we can get output power of 86.5/~W at 507nm with single lens(f=20 mm) coupling scheme, the input power of fundamental laser at t 014 nm is around 58.2 mW. With the method of lens coupling, the relation between the output power and phase matching temperature was given. By contrast, we conducted the coupling of the WG PPLN with bare fiber, as the usual way used by other groups. It shows that the higher doubling efficiency with single lens is obtained compared with that with a fiber case.

  3. Kolakoski sequence as an element to radiate giant forward and backward second harmonic signals

    Energy Technology Data Exchange (ETDEWEB)

    Parvini, T. S. [Physics Department, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Tehranchi, M. M., E-mail: m-hamidi@sbu.ac.ir, E-mail: teranchi@sbu.ac.ir [Physics Department, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Laser and Plasma Research Institute, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Hamidi, S. M., E-mail: m-hamidi@sbu.ac.ir, E-mail: teranchi@sbu.ac.ir; Sarkarati, S. [Laser and Plasma Research Institute, Shahid Beheshti University, Tehran (Iran, Islamic Republic of)

    2015-11-14

    We propose a novel type of aperiodic one-dimensional photonic crystal structures which can be used for generating giant forward and backward second harmonic signals. The studied structure is formed by stacking together the air and nonlinear layers according to the Kolakoski self-generation scheme in which each nonlinear layer contains a pair of antiparallel 180° poled LiNbO{sub 3} crystal layers. For different generation stages of the structure, conversion efficiencies of forward and backward second harmonic waves have been calculated by nonlinear transfer matrix method. Numerical simulations show that conversion efficiencies in the Kolakoski-based multilayer are larger than the perfect ones for at least one order of magnitude. Especially for 33rd and 39th generation stages, forward second harmonic wave are 42 and 19 times larger, respectively. In this paper, we validate the strong fundamental field enhancement and localization within Kolakoski-based multilayer due to periodicity breaking which consequently leads to very strong radiation of backward and forward second harmonic signals. Following the applications of analogous aperiodic structures, we expect that Kolakosi-based multilayer can play a role in optical parametric devices such as multicolor second harmonic generators with high efficiency.

  4. Kolakoski sequence as an element to radiate giant forward and backward second harmonic signals

    International Nuclear Information System (INIS)

    We propose a novel type of aperiodic one-dimensional photonic crystal structures which can be used for generating giant forward and backward second harmonic signals. The studied structure is formed by stacking together the air and nonlinear layers according to the Kolakoski self-generation scheme in which each nonlinear layer contains a pair of antiparallel 180° poled LiNbO3 crystal layers. For different generation stages of the structure, conversion efficiencies of forward and backward second harmonic waves have been calculated by nonlinear transfer matrix method. Numerical simulations show that conversion efficiencies in the Kolakoski-based multilayer are larger than the perfect ones for at least one order of magnitude. Especially for 33rd and 39th generation stages, forward second harmonic wave are 42 and 19 times larger, respectively. In this paper, we validate the strong fundamental field enhancement and localization within Kolakoski-based multilayer due to periodicity breaking which consequently leads to very strong radiation of backward and forward second harmonic signals. Following the applications of analogous aperiodic structures, we expect that Kolakosi-based multilayer can play a role in optical parametric devices such as multicolor second harmonic generators with high efficiency

  5. Third Generation in Cascade Decays

    CERN Document Server

    Dutta, Bhaskar; Maxin, James A; Nanopoulos, Dimitri V; Sinha, Kuver; Walker, Joel W

    2014-01-01

    In supersymmetric models with gluinos around 1000-2000 GeV, new physics searches based on cascade decay products of the gluino are viable at the next run of the LHC. We investigate a scenario where the light stop is lighter than the gluino and both are lighter than all other squarks, and show that its signal can be established using multi b-jet, multi W and/or multi lepton final state topologies. We then utilize both boosted and conventional jet topologies in the final state in conjunction with di-tau production as a probe of the stau-neutralino co-annihilation region responsible for the model's dark matter content. This study is performed in the specific context of one such phenomenologically viable model named No-Scale F-SU(5).

  6. Second-harmonic generation from Z-type Langmuir-Blodgett films of a transparent dye and a comparison of the properties when the layers are interleaved with poly(t-butyl methacrylate)

    Science.gov (United States)

    Ashwell, Geoffrey J.; Ranjan, Rakesh

    1998-10-01

    The Langmuir-Blodgett (LB) film structure of E-4-[(N- octadecyl-6,7,8-trihydro-5-isoquinolylidene)methyl]-N,N- dibutylaniline octadecylsulfate is non-centrosymmetric when the dye is deposited on the up-stroke (Z-type) and when the layers are interleaved with poly(t-butyl methacrylate). The second-harmonic intensity increases as I(N)2(omega ) equals I(1)2(omega )N2, where N is the number of active layers, and the intensity is further enhanced when the dye is mixed in a 1 to 1 ratio with octadecanoic acid. The second-order susceptibility and repeat lattice spacing of the mixed LB films are as follows: (chi) zzz(2) equals 76 pm V-1 at 1.064 micrometers and l equals 3.15 nm layer-1 when Z-type; (chi) zzz(2) equals 52 pm V-1 and l equals 4.13 nm bilayer-1 when interleaved. The films are transparent at the fundamental wavelength and have a slight absorbance of ca. 5 X 10-4 per dye layer at 532 nm. The second-harmonic intensity is the strongest to date from such a weakly absorbing LB film and this is attributed to the close proximity of the charge-transfer band and to an optimized packing arrangement.

  7. Second harmonic chalcone crystal: Synthesis, growth and characterization

    Energy Technology Data Exchange (ETDEWEB)

    D' Silva, E.D., E-mail: deepak.dsilva@gmail.co [Department of studies in Physics, Mangalore University, Mangalagangotri, Mangalore 574199 (India); Narayan Rao, D. [School of Physics, University of Hyderabad, Hyderabad 500046 (India); Philip, Reji [Light and Matter Physics Group, Raman Research Institute, Bangalore 560080 (India); Butcher, Ray J. [Department of Chemistry, Howard University, Washington, DC 20059 (United States); Rajnikant [Department of Physics and Electronics, University of Jammu, Jammu Tawi 180006 (India); Dharmaprakash, S.M. [Department of studies in Physics, Mangalore University, Mangalagangotri, Mangalore 574199 (India)

    2011-05-15

    The novel nonlinear optical chalcone derivative (2E)-3-[4-(methylsulfanyl)phenyl]-1-(3-bromophenyl)prop-2-en-1-one (3Br4MSP) crystals have been grown by slow evaporation technique at ambient temperature. The crystal was subjected to different types of characterization method in order to study its possible application in nonlinear optics. The structure determination of the grown crystal was done by single crystal X-ray diffraction study. The morphology of the crystal is studied. The crystal was subjected to thermal analysis to find its thermal stability. The grown crystals were characterized for their optical transmission and mechanical hardness. The second harmonic generation (SHG) efficiency of the crystal is obtained by classical powdered technique. The laser damage threshold for 3Br4MSP crystal was determined using Q-switched Nd:YAG laser.

  8. Second harmonic chalcone crystal: Synthesis, growth and characterization

    Science.gov (United States)

    D'silva, E. D.; Narayan Rao, D.; Philip, Reji; Butcher, Ray J.; Rajnikant; Dharmaprakash, S. M.

    2011-05-01

    The novel nonlinear optical chalcone derivative (2 E)-3-[4-(methylsulfanyl)phenyl]-1-(3-bromophenyl)prop-2-en-1-one (3Br4MSP) crystals have been grown by slow evaporation technique at ambient temperature. The crystal was subjected to different types of characterization method in order to study its possible application in nonlinear optics. The structure determination of the grown crystal was done by single crystal X-ray diffraction study. The morphology of the crystal is studied. The crystal was subjected to thermal analysis to find its thermal stability. The grown crystals were characterized for their optical transmission and mechanical hardness. The second harmonic generation (SHG) efficiency of the crystal is obtained by classical powdered technique. The laser damage threshold for 3Br4MSP crystal was determined using Q-switched Nd:YAG laser.

  9. 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.

  10. 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.

  11. Characterization of the second-harmonic response of a silver-air interface

    International Nuclear Information System (INIS)

    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

  12. 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.

  13. Nanostructure induced changes in lifetime and enhanced second-harmonic response of organic-plasmonic hybrids

    DEFF Research Database (Denmark)

    Leißner, Till; Kostiučenko, Oksana; Brewer, Jonathan R.;

    2015-01-01

    enhanced second harmonic response. At the same time, the fluorescence lifetime of the nanofibers is reduced from 0.32 ns for unstructured goldfilms to 0.22 ns for gold nanosquare arrays, demonstrating efficient organic–plasmonic interaction. To study the origin of these effects, we applied two-photon laser...... scanning microscopy and fluorescence lifetime imaging microscopy. These findings provide an effective approach for plasmon-enhanced second-harmonic generation at the nanoscale, which is attractive for nanophotonic circuitry....

  14. Control of the orientational order and nonlinear optical response of the "push-pull" chromophore RuPZn via specific incorporation into densely packed monolayer ensembles of an amphiphilic 4-helix bundle peptide: second harmonic generation at high chromophore densities.

    Science.gov (United States)

    Gonella, Grazia; Dai, Hai-Lung; Fry, H Christopher; Therien, Michael J; Krishnan, Venkata; Tronin, Andrey; Blasie, J Kent

    2010-07-21

    The macroscopic nonlinear optical response of the "push-pull" chromophore RuPZn incorporated into a single monolayer of the amphiphilic 4-helix bundle peptide (AP0) covalently attached to a solid substrate at high in-plane density has been measured. The second-order susceptibility, chi(zzz), was found to be in the range of approximately 15 x 10(-9) esu, consistent with a coherent sum of the nonlinear contributions from the individual chromophores (beta) as previously measured in isotropic solution through hyper-Rayleigh scattering as well as estimated from theoretical calculations. The microscopic hyperpolarizability of the RuPZn chromophore is preserved upon incorporation into the peptide monolayer, suggesting that the chromophore-chromophore interactions in the densely packed ensemble do not substantially affect the first-order molecular hyperpolarizability. The polarization angle dependence of the second harmonic signal reveals that the chromophore is vectorially oriented in the two-dimensional ensemble. Analysis of the order parameter together with information obtained from grazing incidence X-ray diffraction help in determining the chromophore orientation within the AP0-RuPZn monolayer. Taking into account an average pitch angle of approximately 20 degrees characterizing the coiled-coil structure of the peptide bundle, the width of the bundle's tilt angle distribution should be sigma < or = 20 degrees, resulting in a mean value of the tilt angle 23 degrees < or = theta(0) < or = 37 degrees. PMID:20578696

  15. 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.

  16. Soliton-induced nonlocal resonances observed through high-intensity tunable spectrally compressed second-harmonic peaks

    DEFF Research Database (Denmark)

    Zhou, Binbin; Guo, Hairun; Bache, Morten

    2014-01-01

    explains this as phase matching between a sideband in the broadband pump to its second harmonic. However, our experiment is conducted under high input intensities and instead shows excellent quantitative agreement with a nonlocal theory describing cascaded quadratic nonlinearities. This theory explains the...... detuned peak as a nonlocal resonance that arises due to phase matching between the pump and a detuned second-harmonic frequency, but where in contrast to the traditional theory the pump is assumed dispersion free. As a soliton is inherently dispersion free, the agreement between our experiment and the...

  17. 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) (Alq3)/Al diodes by time-resolved electric-field-induced optical second-harmonic generation measurement

    International Nuclear Information System (INIS)

    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) (Alq3)/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/Alq3 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

  18. 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.

  19. Synthesis of Core/Shell CuO-Zno Nanoparticles and Their Second-Harmonic Generation Performance / Kodols/Čaula Cuo-Zno Nanodaļiņu Sintēze Un To Spēja Ģenerēt Otrās Harmonikas Signālu

    Science.gov (United States)

    Tamanis, E.; Sledevskis, E.; Ogurcovs, A.; Gerbreders, V.; Paskevics, V.

    2015-10-01

    The present paper presents the method for obtaining core/shell CuO-ZnO nanoparticles and nanocoatings by using a commercially available vacuum coating system. Initially generated Cu-Zn core/shell nanoparticles have been oxidised with a highly reactive atomic oxygen beam. Second-harmonic generation has been observed in the obtained samples. The dependence of second- harmonic intensity on the wavelength of the exciting radiation is shown in the paper. Darbā tiek demonstrēta metode kodols/čaula CuO-ZnO nanodaļiņu un nanopārklājumu sintēzei, izmantojot komerciāli pieejamu vakuuma pārklājumu sistēmu. Sākotnēji sintezētās Cu-Zn kodolš/čaula nanodaļiņas tika oksidētas ar aktīva skābekļa plūsmu. Iegūtajos paraugos tika novērota otrās harmonikas signāla ģenerēšanās. Ir parādīta otrās harmonikas signāla intensitātes atkarība no ierosinošā starojuma viļņa garuma.

  20. 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...... 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....

  1. Cascaded generation of coherent Raman dissipative solitons.

    Science.gov (United States)

    Kharenko, Denis S; Bednyakova, Anastasia E; Podivilov, Evgeniy V; Fedoruk, Mikhail P; Apolonski, Alexander; Babin, Sergey A

    2016-01-01

    The cascaded generation of a conventional dissipative soliton (at 1020 nm) together with Raman dissipative solitons of the first (1065 nm) and second (1115 nm) orders inside a common fiber laser cavity is demonstrated experimentally and numerically. With sinusoidal (soft) spectral filtering, the generated solitons are mutually coherent at a high degree and compressible down to 300 fs. Numerical simulation shows that an even higher degree of coherence and shorter pulses could be achieved with step-like (hard) spectral filtering. The approach can be extended toward a high-order coherent Raman dissipative soliton source offering numerous applications such as frequency comb generation, pulse synthesis, biomedical imaging, and the generation of a coherent mid-infrared supercontinuum. PMID:26696187

  2. Optical chirality of bacteriorhodopsin films via second harmonic Maker's fringes measurements

    Science.gov (United States)

    Larciprete, M. C.; Belardini, A.; Sibilia, C.; Saab, M.-b.; Váró, G.; Gergely, C.

    2010-05-01

    We experimentally investigated second harmonic generation from an oriented multilayer film of bacteriorhodopsin protein, deposited onto a charged surface. The generated signal is obtained as a function of incidence angle, at different polarization state of both fundamental and generated beams. We show that the measurements, together with the analytical curves, allow to retrieve the nonvanishing elements of the nonlinear optical tensor, including the ones introduced by optical chirality.

  3. Broadband Asymmetric Conical Emission via Cascaded Second-Order Nonlinear Polarization during the Propagation of Femtosecond Laser Pulses in a BBO Crystal

    International Nuclear Information System (INIS)

    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. (fundamental areas of phenomenology(including applications))

  4. Solitons and second harmonic radiation in type III bursts

    Science.gov (United States)

    Papadopoulos, K.; Freund, H. P.

    1978-01-01

    The emission at the second harmonic of the plasma frequency from self-consistent Langmuir solitons is calculated. The theory predicts, in a natural way, the observed transition from the region where the intensity is linearly proportional to the electron flux to the region where the radio intensity is proportional to the square of the electron flux. A detailed comparison of the radiation observed at the second harmonic for the burst of 18:10 UT March 31, 1976, with the one expected on the assumption of radiation from solitons, using the correlated in situ measurements of the electric fields at the second harmonic, and their spatial structure, provides strong evidence that, for the first time, Langmuir solitons have been observed in space.

  5. Second-harmonic scanning optical microscopy of poled silica waveguides

    DEFF Research Database (Denmark)

    Pedersen, Kjeld; Bozhevolnyi, Sergey I.; Arentoft, Jesper;

    2000-01-01

    Second-harmonic scanning optical microscopy (SHSOM) is performed on electric-field poled silica-based waveguides. Two operation modes of SHSOM are considered. Oblique transmission reflection and normal reflection modes are used to image the spatial distribution of nonlinear susceptibilities in the...... limitations of the two operation modes when used for SHSOM studies of poled silica-based waveguides are discussed. The influence of surface defects on the resulting second-harmonic images is also considered. ©2000 American Institute of Physics....

  6. Results from a Ku-band second harmonic coaxial gyroklystron

    Energy Technology Data Exchange (ETDEWEB)

    Castle, M.; Lawson, W.; Hogan, B.; Yovchev, I.; Granatstein, V.L.; Reiser, M.

    1999-07-01

    Investigations into the performance of high-powered gyroklystrons have been pursued for over 14 years at the University of Maryland. Recent results culminated in an 80 MW TC{sub 01} output signal at 8.57 GHz for 1.3 {micro}s. The efficiency of this tube was 32% and the saturated gain was 31 dB. This was the first of a proposed series of coaxial circuits whose powers are to be on the order of 100 MW. Testing of a second harmonic circuit is currently being undertaken. The designed output is a TE{sub 02} signal at 17.11 GHz (detuned from ideal second harmonic to optimize efficiency) driven by a 500--700 A,m 460 kV beam. An X-Band coaxial magnetron (8.5--9.6 GHz, 2 {micro}s) provides an input signal of up to 150 kW. The circuit consists of three cavities, an input, which operates at the fundamental, and a bunching and output, which operates at the second harmonic. The theoretical gain and efficiency at 49 dB and 40% respectively. This presentation will describe in detail the experimental results and the outcome of this work. It will also detail any planned and completed efforts to improve performance from this initial second harmonic tube. In addition, experimental work intended on customizing the system to power a small accelerator will be presented.

  7. Second harmonic imaging using synthetic aperture sequential beamforming

    DEFF Research Database (Denmark)

    Du, Yigang; Rasmussen, Joachim; Jensen, Henrik;

    2011-01-01

    The paper investigates Second Harmonic Imaging (SHI) using Synthetic Aperture Sequential Beamforming (SASB). The investigation is made by an experimental Synthetic Aperture Real-time Ultrasound System (SARUS). A linear array transducer is used to scan 4 wires at the image depths of f22.5, 47.5, 72...

  8. Development of blue lasers, from second harmonic generation using a Nd:YAG laser emitting at 946 nm; Desenvolvimento de lasers no azul, a partir da geracao de segundo harmonico de um laser de Nd:YAG operando em 946 nm

    Energy Technology Data Exchange (ETDEWEB)

    Nogueira, Gustavo Bernardes

    2010-07-01

    Blue lasers have attracted much attention for applications such as blue-ray, displays and as pumped source for the Ti:sapphire laser. A Nd:YAG crystal with diffusion bonded end-caps was used together with a pump wavelength of 802,3 nm, detuned from the absorption peak at 808 nm in order to minimize the thermal lens effect by providing for a better temperature distribution inside the crystal. Using different input mirror radii, the best relation between pump waist and laser was achieved in a linear cavity and resulted in 6.75W cw (continuous wave) laser power at 946 nm and slope efficiency of 48%. In a second step, a second harmonic generation crystal for blue emission at 473 nm was inserted into different types of resonators, and the blue output power at 473 nm was measured as a function of absorbed pump power. (author)

  9. Optical second harmonic imaging as a diagnostic tool for monitoring epitaxial oxide thin-film growth

    International Nuclear Information System (INIS)

    Optical second harmonic generation is proposed as a tool for non-invasive, non-destructive, real-time, in-situ imaging of oxide epitaxial film growth. The films can be monitored by surface imaging with a lateral resolution of ≤1 μm on an area of size up to 1 cm2. We demonstrate the potential of the proposed technique by an ex-situ analysis of thin epitaxial SrTiO3 films grown on (1 1 0) NdGaO3 single crystals. Our data show that second harmonic generation provides complementary information to established in-situ monitoring techniques such as reflection high-energy electron diffraction. We demonstrate that this technique can reveal otherwise elusive in-plane inhomogeneities of electrostatic, chemical or structural nature. The presence of such inhomogeneities is independently confirmed by scanning probe microscopy

  10. 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....

  11. Nanostructure induced changes in lifetime and enhanced second-harmonic response of organic-plasmonic hybrids

    Energy Technology Data Exchange (ETDEWEB)

    Leißner, Till [NanoSYD, Mads Clausen Institute, University of Southern Denmark, Alsion 2, 6400 Sønderborg (Denmark); Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, 5230 Odense (Denmark); Kostiučenko, Oksana; Rubahn, Horst-Günter; Fiutowski, Jacek, E-mail: fiutowski@mci.sdu.dk [NanoSYD, Mads Clausen Institute, University of Southern Denmark, Alsion 2, 6400 Sønderborg (Denmark); Brewer, Jonathan R. [Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, 5230 Odense (Denmark)

    2015-12-21

    In this letter we show that the optical response of organic nanofibers, grown from functionalized para-quaterphenylene molecules, can be controlled by forming organic-plasmonic hybrid systems. The interaction between nanofibers and supporting regular arrays of nanostructures leads to a strongly enhanced second harmonic response. At the same time, the fluorescence lifetime of the nanofibers is reduced from 0.32 ns for unstructured gold films to 0.22 ns for gold nanosquare arrays, demonstrating efficient organic–plasmonic interaction. To study the origin of these effects, we applied two-photon laser scanning microscopy and fluorescence lifetime imaging microscopy. These findings provide an effective approach for plasmon-enhanced second-harmonic generation at the nanoscale, which is attractive for nanophotonic circuitry.

  12. Stokes vector based polarization resolved second harmonic microscopy of starch granules.

    Science.gov (United States)

    Mazumder, Nirmal; Qiu, Jianjun; Foreman, Matthew R; Romero, Carlos Macías; Török, Peter; Kao, Fu-Jen

    2013-04-01

    We report on the measurement and analysis of the polarization state of second harmonic signals generated by starch granules, using a four-channel photon counting based Stokes-polarimeter. Various polarization parameters, such as the degree of polarization (DOP), the degree of linear polarization (DOLP), the degree of circular polarization (DOCP), and anisotropy are extracted from the 2D second harmonic Stokes images of starch granules. The concentric shell structure of a starch granule forms a natural photonic crystal structure. By integration over all the solid angle, it will allow very similar SHG quantum efficiency regardless of the angle or the states of incident polarization. Given type I phase matching and the concentric shell structure of a starch granule, one can easily infer the polarization states of the input beam from the resulting SH micrograph. PMID:23577289

  13. 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.

  14. Development of high efficiency second harmonic frequency converter

    International Nuclear Information System (INIS)

    An efficient four-pass quadrature frequency conversion scheme was developed. A high conversion efficiency in excess of 80% has been achieved for frequency doubling of 1064-nm in KTP with a low input fundamental laser intensity of 76 MW/cm2. A second-harmonic output of 486 mJ has been obtained with 607 mJ of the input 1064-nm fundamental laser at 10 Hz. (author)

  15. Development of high efficiency second harmonic frequency converter

    Energy Technology Data Exchange (ETDEWEB)

    Kiriyama, Hiromitsu; Matsuoka, Shinichi; Maruyama, Yoichiro; Arisawa, Takashi [Advanced Photon Research Center, Kansai Research Establishment, Japan Atomic Energy Research Inst., Kizu, Kyoto (Japan)

    2000-03-01

    An efficient four-pass quadrature frequency conversion scheme was developed. A high conversion efficiency in excess of 80% has been achieved for frequency doubling of 1064-nm in KTP with a low input fundamental laser intensity of 76 MW/cm{sup 2}. A second-harmonic output of 486 mJ has been obtained with 607 mJ of the input 1064-nm fundamental laser at 10 Hz. (author)

  16. 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...... 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...

  17. Second Harmonics of Reversed Shear TAE in Alcator C-Mod Geometry

    Science.gov (United States)

    Chen, Eugene; Berk, Herbert; Breizman, Boris; Zheng, Linjin

    2009-11-01

    Experiments on Alcator C-Mod, operating with reversed magnetic shear, reveal Toroidal Alfven Eigenmodes (TAE) together with signals at twice the mode frequency. The double frequency signals can be viewed as second harmonic sidebands driven by quadratic non-linear terms in the MHD equations, in analogy with a corresponding theory for Alfven Cascades [1]. However, these nonlinear sidebands have not yet been quantified by any of the existing codes. In this work, we extend AEGIS code [2] to capture nonlinear effects iteratively by treating the nonlinear terms as a driving source in the linear MHD solver. We first compute the TAE mode structure for realistic geometry and q-profile and then use it to find the spatial structure of the second harmonic density perturbation, which can be directly compared with PCI measurements at Alcator C-Mod. [1] H. Smith, B. N. Breizman, M. Lisak and D. Anderson, Physics of Plasmas 13 042504 (2006) [2] L. J. Zheng and M. Kotschenreuther, Journal of Computational Physics 211 (2006) 748-766

  18. 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.

  19. 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)

  20. Organic materials for second harmonic generation. Final report

    International Nuclear Information System (INIS)

    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