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Sample records for changing refractive index

  1. Laser induced changes of refractive index of lead - silicate glasses

    International Nuclear Information System (INIS)

    The mechanisms of photoinduced changes of refractive index of the TΦ lead - silicate glasses (analogous with the SF glasses from Schott catalog) under the effect of high power laser radiation with quantum energy less bandgap have been studied. It is shown that the laser induced color centers results in increase of refractive index into the exposed bulk during the laser pulse action. This leads to considerable redistribution of irradiance and decrease of laser radiation brightness even in the case of optical elements less 1 mm thickness. The observed effect may be connected both with radiation induced dilatation of matter and heating of interaction region owing to absorption of radiation by color centers. Comparison the kinetics of refractive index change of the glass after exposure by laser pulse at 0.53 μm and the kinetics of color centers decay allowed to draw a conclusion about heat character of observed changes

  2. Measurements of photoinduced refractive index changes in bacteriorhodopsin films

    Indian Academy of Sciences (India)

    Ravinder Kumar Banyal; B Raghavendra Prasad

    2007-03-01

    We report the pump-probe measurements of nonlinear refractive index changes in photochromic bacteriorhodopsin films. The photoinduced absorption is caused by pump beam at 532 nm and the accompanying refractive index changes are studied using a probe beam at 633 nm. The proposed technique is based on a convenient and accurate determination of optical path difference using digital interferometry-based local fringe shift. The results are presented for the wild-type as well as genetically modified D96N variant of the bacteriorhodopsin.

  3. Measurements of photoinduced refractive index changes in bacteriorhodopsin films

    Science.gov (United States)

    Banyal, Ravinder Kumar; Raghavendra Prasad, B.

    2007-03-01

    We report the pump--probe measurements of nonlinear refractive index changes in photochromic bacteriorhodopsin films. The photoinduced absorption is caused by pump beam at 532 nm and the accompanying refractive index changes are studied using a probe beam at 633 nm. The proposed technique is based on a convenient and accurate determination of optical path difference using digital interferometry-based local fringe shift. The results are presented for the wild-type as well as genetically modified D96N variant of the bacteriorhodopsin.

  4. Refractive index change detection based on porous silicon microarray

    Science.gov (United States)

    Chen, Weirong; Jia, Zhenhong; Li, Peng; Lv, Guodong; Lv, Xiaoyi

    2016-05-01

    By combining photolithography with the electrochemical anodization method, a microarray device of porous silicon (PS) photonic crystal was fabricated on the crystalline silicon substrate. The optical properties of the microarray were analyzed with the transfer matrix method. The relationship between refractive index and reflectivity of each array element of the microarray at 633 nm was also studied, and the array surface reflectivity changes were observed through digital imaging. By means of the reflectivity measurement method, reflectivity changes below 10-3 can be observed based on PS microarray. The results of this study can be applied to the detection of biosensor arrays.

  5. Mechanisms of the refractive index change in DO11/PMMA due to photodegradation

    CERN Document Server

    Anderson, Benjamin R

    2014-01-01

    Using a white light interferometric microscope (WLIM) we measure the photodamage induced change in the complex index of refraction of disperse orange 11 (DO11) dye-doped (poly)methyl-methacrylate. We find that the change in the imaginary part of the refractive index is consistent with previous measurements of photodamage-induced absorbance change. Additionally, we find that the change in the real refractive index can be separated into a component due to damage to the dye molecules and a component due to irreversible damage to the polymer.

  6. Interferometer for Measuring Fast Changes of Refractive Index and Temperature in Transparent Liquids

    DEFF Research Database (Denmark)

    Miller, Arne; Hussmann, E. K.; McLaughlin, W. L.

    1975-01-01

    A double‐beam interferometer has been designed for detecting changes of refractive index in transparent liquids associated with the absorption of ionizing radiation energy, due to short electron beam pulses from an accelerator. The response time of the interferometer is less than 0.2 μsec, and...... refractive index changes of the order of 10−7 can be measured, corresponding to a temperature change of ∼10−3  °C and an absorbed dose in water of ∼350 rad. The interferometer can be used as either a real‐time or integrating radiation dosimeter, if the temperature coefficient of the refractive index (dn...

  7. Refractive Index Change and Color Center Formation in LiYF_4 Crystal Induced by a Femtosecond Laser

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The refractive index change and color centers formation in LiYF4 crystal at room temperature are induced by a femtosecond laser irradiation. A mechanism for refractive index change and color centers formation is proposed.

  8. Simulation of imperfections in plastic lenses - transferring local refractive index changes into surface shape modifications

    Science.gov (United States)

    Arasa, Josep; Pizarro, Carles; Blanco, Patricia

    2016-06-01

    Injection molded plastic lenses have continuously improved their performance regarding optical quality and nowadays are as usual as glass lenses in image forming devices. However, during the manufacturing process unavoidable fluctuations in material density occur, resulting in local changes in the distribution of refractive index, which degrade the imaging properties of the polymer lens. Such material density fluctuations correlate to phase delays, which opens a path for their mapping. However, it is difficult to transfer the measured variations in refractive index into conventional optical simulation tool. Thus, we propose a method to convert the local variations in refractive index into local changes of one surface of the lens, which can then be described as a free-form surface, easy to introduce in conventional simulation tools. The proposed method was tested on a commercial gradient index (GRIN) lens for a set of six different object positions, using the MTF sagittal and tangential cuts to compare the differences between the real lens and a lens with homogenous refractive index, and the last surface converted into a free-form shape containing the internal refractive index changes. The same procedure was used to reproduce the local refractive index changes of an injected plastic lens with local index changes measured using an in-house built polariscopic arrangement, showing the capability of the method to provide successful results.

  9. Photoinduced changes in refractive index of nanostructured shungite-containing polyimide systems

    Science.gov (United States)

    Kamanina, N. V.; Serov, S. V.; Shurpo, N. A.; Rozhkova, N. N.

    2011-10-01

    Photoinduced changes in the refractive index of a conjugate polyimide (PI) matrix sensitized by shungite carbon nanoparticles have been studied for the first time. The results are compared to the data of previous investigations of the photorefractive properties of PI matrices doped with fullerenes, carbon nanotubes, and quantum dots. The nonlinear refractive index of the proposed material has been determined using the dynamic holography techniques. The position of conjugate polymer materials of this type among the other nonlinear optical systems is considered.

  10. Fiber optic refractive index monitor

    Science.gov (United States)

    Weiss, Jonathan David

    2002-01-01

    A sensor for measuring the change in refractive index of a liquid uses the lowest critical angle of a normal fiber optic to achieve sensitivity when the index of the liquid is significantly less than the index of the fiber core. Another embodiment uses a liquid filled core to ensure that its index is approximately the same as the liquid being measured.

  11. Mechanisms of a change in the refractive index of an intensely pumped Yb:YAG crystal

    International Nuclear Information System (INIS)

    Mechanisms of a change in the refractive index appearing in an intensely diode-pumped Yb:YAG-laser disk element are studied with the help of polarisation interferometry and dynamic grating testing. It is found that changes in the electronic component of the refractive index arising upon changing the populations of electronic levels of Yb3+ ions (the ground 2F7/2 state and the upper 2F5/2 level of the laser transition) and caused by the difference in the polarisability of these levels are an order of magnitude greater than thermal changes in the refractive index. It is shown that the difference Δp in the polarisability at the probe wavelength of 633 nm is 1.9 x 10-26 cm3 and at the laser transition wavelength of 1029 nm is 1.6 x 10-26 cm3. (nonlinear optical phenomena)

  12. Spatial light modulation based on photoinduced change in the complex refractive index of bacteriorhodopsin

    Science.gov (United States)

    Takei, Hiroyuki; Shimizu, Norio

    1996-04-01

    Bacteriorhodopsin exhibits photoinduced changes in both absorption and refractive index at 633 nm. To explore the possibility of exploiting this property in constructing a photoaddressed spatial light modulator, we investigated the transmission property of a Fabry-Perot interferometer containing a bacteriorhodopsin thin film. Film was formed that had a phase shift of pi /4 and sufficient interference fringe contrast for spatial light modulation. This establishes the possibility of constructing a spatial light modulator that features nonlinear input-output characteristics and can operate at moderate light intensities of the order of tens of milliwatts per centimeter square. spatial light modulation, complex refractive index.

  13. Visualizations of Light-induced Refractive Index Changes in Photorefractive Crystals Employing Digital Holography

    Institute of Scientific and Technical Information of China (English)

    赵建林; 张鹏; 周俭波; 杨德兴; 杨东升; 李恩普

    2003-01-01

    We propose a novel approach to visualize the light-induced refractive index changes in photorefractive crystals employing digital holography. The holograms formed in a Mach-Zehnder interferometer are recorded by a twodimensional CCD camera. From these holograms, the phase differences, which contain the information of the index changes in photorefractive crystals, are determined by utilizing digital holographic interferometry. Then the two-dimensional visualizations of index changes in the crystals can be obtained. This method is successfully demonstrated in LiNbO3:Fe, KNSBN:Ce and SBN:Cr crystals.

  14. Determination of femtosecond-laser-induced refractive-index changes in an optical fiber from far-field measurements

    DEFF Research Database (Denmark)

    Savolainen, Juha-Matti; Grüner-Nielsen, Lars; Kristensen, Poul; Balling, Peter

    2014-01-01

    A new method for direct writing of localized, circularly symmetric refractive-index changes in optical fibers with a femtosecond laser is demonstrated. The refractive-index changes are characterized using a novel approach employing comparison of numerical simulations to the measured far...

  15. Intersubband transitions and refractive index changes in coupled double quantum well with different well shapes

    Science.gov (United States)

    Ozturk, Emine; Sokmen, Ismail

    2011-10-01

    In this study, both the linear intersubband transitions and the refractive index changes in coupled double quantum well (DQW) with different well shapes for different electric fields are theoretically calculated within framework of the effective mass approximation. Results obtained show that intersubband transitions and the energy levels in coupled DQW can importantly be modified and controlled by the electric field strength and direction. By considering the variation of the energy differences, it should point out that by varying electric field we can obtain a blue or red shift in the intersubband optical transitions. The modulation of the absorption coefficients and the refractive index changes which can be suitable for good performance optical modulators and various infrared optical device applications can be easy obtained by tuning applied electric field strength and direction.

  16. SOLITONS: Nonlinear dynamics of optical pulses in fibres with a travelling refractive-index-change wave

    Science.gov (United States)

    Adamova, M. S.; Zolotovskii, Igor'O.; Sementsov, Dmitrii I.

    2009-03-01

    Dynamics of soliton-like wave packets in fibres with a travelling refractive-index-change wave is studied. It is shown that both a soliton-like propagation regime of a pulse and a self-compression regime in the region of normal group velocity dispersion are possible. It is also shown that in the case of a copropagating or counterpropagating pulse and optically inhomogeneous wave nonreciprocal effects appear.

  17. Refractive index changes and absorption coefficients in a spherical quantum dot with parabolic potential

    International Nuclear Information System (INIS)

    In this study, we have calculated the linear, nonlinear and total refractive index changes and absorption coefficients for the transitions 1s–1p, 1p–1d and 1d–1f in a spherical quantum dot with parabolic potential. Quantum Genetic Algorithm (QGA) and Hartree–Fock–Roothaan (HFR) method have been employed to calculate the wavefuctions and energy eigenvalues. The results show that impurity, dot radius, stoichiometric ratio, incident optical intensity and carrier density of the system have important effects on the optical refractive index changes and absorption coefficients. Also, we find that as the transitions between orbitals with big l value move to lower energy region in case with parabolic potential, in case without parabolic potential these transitions move to higher energy region. - Highlights: ► A spherical quantum dot with parabolic potential has been considered. ► Quantum Genetic Algorithm and Hartree–Fock–Roothaan method have been used to calculate the wave functions and the total energy. ► The detailed refractive index changes and absorption coefficients of quantum dot have been investigated.

  18. A Comparison of Kretschmann-Raether Angular Regimes for Measuring Changes in Bulk Refractive Index

    Energy Technology Data Exchange (ETDEWEB)

    KASUNIC, K.J.

    1999-09-16

    We compare 2 angular regimes for the measurement of changes in the real refractive index of bulk fluid analytes. The measurements are based on the use of the Kretschmann-Raether configuration to sense a change in reflectivity with index. Specifically, we numerically simulate the relative sensitivities of the total internal reflection (TIR) and surface-plasmon resonance (SPR) regimes. For a fixed-angle apparatus, the method which gives the greatest change in reflectivity varies with metal film thickness. For films thicker than the skin depth, the SPR regime is the most sensitive to index changes. For thinner films, however, the TIR angle is then dominant, with increases in sensitivity on the order of 75% for 10 nm gold or silver media.

  19. Refractive index based measurements

    DEFF Research Database (Denmark)

    2014-01-01

    In a method for performing a refractive index based measurement of a property of a fluid such as chemical composition or temperature by observing an apparent angular shift in an interference fringe pattern produced by back or forward scattering interferometry, ambiguities in the measurement caused...... by the apparent shift being consistent with one of a number of numerical possibilities for the real shift which differ by 2n are resolved by combining measurements performed on the same sample using light paths therethrough of differing lengths....

  20. Negative refractive index metamaterials

    Directory of Open Access Journals (Sweden)

    Willie J. Padilla

    2006-07-01

    Full Text Available Engineered materials composed of designed inclusions can exhibit exotic and unique electromagnetic properties not inherent in the individual constituent components. These artificially structured composites, known as metamaterials, have the potential to fill critical voids in the electromagnetic spectrum where material response is limited and enable the construction of novel devices. Recently, metamaterials that display negative refractive index – a property not found in any known naturally occurring material – have drawn significant scientific interest, underscoring the remarkable potential of metamaterials to facilitate new developments in electromagnetism.

  1. Effect of hydrogenic impurity on linear and nonlinear optical absorption coefficients and refractive index changes in a quantum dot

    International Nuclear Information System (INIS)

    The analytical expressions of linear and nonlinear optical absorption coefficients and refractive index changes in a quantum dot with a hydrogenic impurity are obtained by using the compact-density-matrix approach and iterative method. The wave functions and the energy levels are obtained by using the variational method. Numerical results show that the optical absorption coefficients and refractive index changes are strongly affected by the hydrogenic impurity. (paper)

  2. Refractive-index changes in lithium niobate crystals by radiation damages; Brechungsindexaenderungen in Lithiumniobat-Kristallen durch Strahlenschaeden

    Energy Technology Data Exchange (ETDEWEB)

    Zamani Meymian, Mohammad Reza

    2007-12-18

    For the study in this thesis {sup 3}He{sup 2+} ions with the energy of about 40 MeV were applied. The results of these studies show a timely very stable anisotrope refractive-index change in the range of some 10{sup -3}. The radiation damages caused by ions cause a decreasement of the ordinary refractive index n{sub o} and an increasement of the extra-ordinary refractive index n{sub e}. While the absolute values for {delta}n{sub o} and {delta}n{sub e} are nearly equal the birefringence of the material (n{sub e}-n{sub o}) smaller. The generated refractive-index change is dose dependent and the curve {delta}n has at increasing dose a strongly nonlinear slope with a characteristic stage at the radiation dose of about 2 x 10{sup 20} ions/m{sup 2}.

  3. Refractive index modulation of Sb70Te30 phase-change thin films by multiple femtosecond laser pulses

    Science.gov (United States)

    Lei, Kai; Wang, Yang; Jiang, Minghui; Wu, Yiqun

    2016-05-01

    In this study, the controllable effective refractive index modulation of Sb70Te30 phase-change thin films between amorphous and crystalline states was achieved experimentally by multiple femtosecond laser pulses. The modulation mechanism was analyzed comprehensively by a spectral ellipsometer measurement, surface morphology observation, and two-temperature model calculations. We numerically demonstrate the application of the optically modulated refractive index of the phase-change thin films in a precisely adjustable color display. These results may provide further insights into ultrafast phase-transition mechanics and are useful in the design of programmable photonic and opto-electrical devices based on phase-change memory materials.

  4. Large refractive index changes in tunable-electron-density InGaAs/InAlAs quantum wells

    International Nuclear Information System (INIS)

    The authors present measurements of electrorefraction and electroabsorption in a novel multiple quantum well waveguide structure in which each InGaAs quantum well is provided with an individual electron reservoir. External bias transfers electrons into the wells, thus quenching the absorption and producing a refractive index change at wavelengths below the bandedge which is linear in the applied voltage. The authors demonstrate that in this type of structure both the change in refractive index per applied field and the ratio of optical phase to intensity modulation can be significantly enhanced over those found in the quantum confined Stark effect

  5. Response of long-period gratings fabricated in a graded-index optical fiber to refractive-index changes

    Czech Academy of Sciences Publication Activity Database

    Chomát, Miroslav; Berková, Daniela; Matějec, Vlastimil; Kašík, Ivan; Kaňka, Jiří; Slavík, Radan; Jančárek, A.; Bittner, P.

    [Monastir] : [Faculté des Sciences de Monastir], 2004. s. 88. [Journees Maghreb-Europe sur les Materiaux et Leurs Applications aux Dispositifs et Capteurs MADICA 2004 /4./. 29.11.2004-01.12.2004, Tunis] R&D Projects: GA ČR GA102/03/0475 Institutional research plan: CEZ:AV0Z2067918 Keywords : optical fibres * fibre optic sensors * refractive index Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  6. Applications of Optical Interferometer Techniques for Precision Measurements of Changes in Temperature, Growth and Refractive Index of Materials

    Directory of Open Access Journals (Sweden)

    Rami Reddy Bommareddi

    2014-05-01

    Full Text Available Optical metrology techniques used to measure changes in thickness; temperature and refractive index are surveyed. Optical heterodyne detection principle and its applications for precision measurements of changes in thickness and temperature are discussed. Theoretical formulations are developed to estimate crystal growth rate, surface roughness and laser cooling/heating of solids. Applications of Michelson and Mach-Zehnder interferometers to measure temperature changes in laser heating of solids are described. A Mach-Zehnder interferometer is used to measure refractive index and concentration variations of solutions in crystal growth experiments. Additionally, fluorescence lifetime sensing and fluorescence ratio method are described for temperature measurement. For all the above techniques, uncertainty calculations are included.

  7. Polymers for refractive index change in intraocular lenses: a novel approach for photoinduced tuning of focal length

    Science.gov (United States)

    Träger, Jens; Kim, Hee-Cheol; Hampp, Norbert

    2006-02-01

    Before an intraocular lens (IOL) is implanted during cataract surgery, biometric data of the patient's eye have to be determined to calculate the thickness and shape of the IOL. In particular the postoperative anterior chamber depth is an important parameter to predict the correct shape of the IOL. This value, however, cannot be measured without significant uncertainities. We present a solution to this problem, describe novel polymers suitable for IOLs which refractive indices can be changed non-invasively in a photo-induced process. The focal length can be modified by about 2 D, which is sufficient to achive ideal acuteness of vision for almost all patients with implanted IOLs. The change in refractive index is accomplished by linking or cleaving bonds between a sufficiently large number of side groups of the polymer main chain in a photoinduced cyloaddition or cycloreversion, respectively. The photochemical reaction can also be triggered by a two-photon process (TPA) using a pulsed laser system, i.e. the energy required for bond breaking is provided by two photons in the visible range. Light in the UV as well as the visible range of the spectrum cannot induce undesired changes of the refractive index owing to the strong UV-absorption of the cornea and photon densities much too low for TPA, respectively. Due to the excellent spatial resolution that can be achieved with two-photon processes not only modification of the refractive index of the entire lens but also selectively in well defined areas is possible enabling the correction for aberrations such as astigmatism.

  8. Modification of Low Refractive Index Polycarbonate for High Refractive Index Applications

    Directory of Open Access Journals (Sweden)

    Rakesh Kumar Khandal

    2009-01-01

    Full Text Available Polycarbonates and polythiourethanes are the most popular materials in use today, for optical applications. Polycarbonates are of two types which fall in the category of low refractive index and medium refractive index. The present paper describes the conversion of low refractive index polycarbonates into high refractive index material by the use of a high refractive index monomer, polythiol, as an additive. Novel polycarbonates, where the properties of refractive index and Abbe number can be tailor made, have been obtained. Thermal studies and refractive index determination indicate the formation of a new polymer with improved properties and suitable for optical applications.

  9. Variable refractive index in environment matte

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ming-tian; XIAO Shuang-jiu; YANG Xu-bo; MA Li-zhuang

    2006-01-01

    Environment matting and compositing is a technique to extract a foreground object, including color, opacity, reflective and refractive properties, from a real-world scene, and synthesize new images by placing it into new environments. The description of the captured object is named environment matte. Recent matting and compositing techniques can produce quite realistic images for objects with complex optical properties. This paper presents an approximate method to transform the matte by simulating variation of the foreground object's refractive index. Our algorithms can deal with achromatous-and-transparent objects and the experimental results are visually acceptable. Our idea and method can be applied to produce some special video effects, which could be very useful in film making, compared with the extreme difficulty of physically changing an object's refractive index.

  10. Effect of dextran-induced changes in refractive index and aggregation on optical properties of whole blood

    Energy Technology Data Exchange (ETDEWEB)

    Xu Xiangqun [Institute of Bioscience and Technology, Cranfield University, Silsoe, Bedfordshire MK45 4DT (United Kingdom); Wang, Ruikang K [Institute of Bioscience and Technology, Cranfield University, Silsoe, Bedfordshire MK45 4DT (United Kingdom); Elder, James B [School of Medicine, Keele University, Stoke-on-Trent, ST4 7QB (United Kingdom); Tuchin, Valery V [Department of Optics, Saratov State University, 155 Moskovskaya Str., 410026 Saratov (Russian Federation)

    2003-05-07

    The purpose of the present study is to investigate systematically the mechanisms of alterations in the optical properties of whole blood immersed in the biocompatible agent dextran, and to define the optimal concentration of dextrans required for blood optical clearing in order to enhance the capability of light penetration depth for optical imaging applications. In the experiments, dextrans with different molecular weights and various concentrations were employed and investigated by the use of the optical coherence tomography technique. Changes in light attenuation, refractive index and aggregation properties of blood immersed in dextrans were studied. It was concluded from the results that the mechanisms for blood optical clearing are characteristic of the types of dextrans employed, their concentrations and the application stages. Among the substances applied, Dx500 at a concentration at 0.5 g dl{sup -1} gives the best result in improving light penetration depth through the blood. The increase of light transmission at the beginning of the addition of dextrans is mainly attributed to refractive index matching between the scattering centres and the ground matter. Thereafter, the transmission change is probably due to a dextran-induced aggregation-disaggregation effect. Overall, light scattering in the blood could be effectively reduced by the application of dextrans. It represents a promising approach to increasing the imaging depth for in vivo optical imaging of biological tissue, for example optical coherence tomography.

  11. Effect of dextran-induced changes in refractive index and aggregation on optical properties of whole blood

    International Nuclear Information System (INIS)

    The purpose of the present study is to investigate systematically the mechanisms of alterations in the optical properties of whole blood immersed in the biocompatible agent dextran, and to define the optimal concentration of dextrans required for blood optical clearing in order to enhance the capability of light penetration depth for optical imaging applications. In the experiments, dextrans with different molecular weights and various concentrations were employed and investigated by the use of the optical coherence tomography technique. Changes in light attenuation, refractive index and aggregation properties of blood immersed in dextrans were studied. It was concluded from the results that the mechanisms for blood optical clearing are characteristic of the types of dextrans employed, their concentrations and the application stages. Among the substances applied, Dx500 at a concentration at 0.5 g dl-1 gives the best result in improving light penetration depth through the blood. The increase of light transmission at the beginning of the addition of dextrans is mainly attributed to refractive index matching between the scattering centres and the ground matter. Thereafter, the transmission change is probably due to a dextran-induced aggregation-disaggregation effect. Overall, light scattering in the blood could be effectively reduced by the application of dextrans. It represents a promising approach to increasing the imaging depth for in vivo optical imaging of biological tissue, for example optical coherence tomography

  12. Threshold pump intensity effect on the refractive index changes in InGaN SQD: Internal constitution and size effects

    International Nuclear Information System (INIS)

    In the present paper, internal composition and size-dependent threshold pump intensity effects on on-center impurity-related linear, third-order nonlinear and total refractive index changes are investigated in wurtzite (In,Ga)N/GaN unstrained spherical quantum dot. The calculation is performed within the framework of parabolic band and single band effective-mass approximations using a combination of Quantum Genetic Algorithm (QGA) and Hartree–Fock–Roothaan (HFR) method. According to the results obtained, (i) a significant red-shift (blue shift) is obtained as the dot size (potential barrier) increases and (ii) a threshold optical pump intensity depending strongly on the size and the internal composition is obtained which constitutes the limit between two behaviors

  13. Threshold pump intensity effect on the refractive index changes in InGaN SQD: Internal constitution and size effects

    Energy Technology Data Exchange (ETDEWEB)

    El Ghazi, Haddou, E-mail: hadghazi@gmail.com [Special Mathematics, CPGE Rabat (Morocco); LPS, Faculty of Science, Dhar El Mehrez, BP 1796 Fes-Atlas (Morocco); A John Peter [P.G. & Research Department of Physics, Goverment Arts and Science College, Melur 625106, Madurai (India)

    2015-04-01

    In the present paper, internal composition and size-dependent threshold pump intensity effects on on-center impurity-related linear, third-order nonlinear and total refractive index changes are investigated in wurtzite (In,Ga)N/GaN unstrained spherical quantum dot. The calculation is performed within the framework of parabolic band and single band effective-mass approximations using a combination of Quantum Genetic Algorithm (QGA) and Hartree–Fock–Roothaan (HFR) method. According to the results obtained, (i) a significant red-shift (blue shift) is obtained as the dot size (potential barrier) increases and (ii) a threshold optical pump intensity depending strongly on the size and the internal composition is obtained which constitutes the limit between two behaviors.

  14. In situ visualizing the evolution of the light-induced refractive index change of Mn:KLTN crystal with digital holographic interferometry

    Directory of Open Access Journals (Sweden)

    Jinxin Han

    2015-04-01

    Full Text Available The light-induced refractive index change in Mn:KLTN crystal, illuminated by focused light sheet, is visualized in situ and quantified by digital holographic interferometry. By numerically retrieving a series of sequential phase maps from recording digital holograms, the spatial distribution of the induced refractive index change can be visualized and estimated readily. This technique enables the observation of the temporal evolution of the refractive index change under different recording situations such as writing laser power, applied voltage, and temperature, and the photoconductivity of Mn:KLTN crystal can be calculated as well, the experimental results are in good agreement with the theory. The research results suggest that the presented method is successful and feasible.

  15. Microstructured optical fiber refractive index sensor

    DEFF Research Database (Denmark)

    Town, Graham E.; McCosker, Ravi; Yuan, Scott Wu;

    2010-01-01

    We describe a dual-core microstructured optical fiber designed for refractive index sensing of fluids. We show that by using the exponential dependence of intercore coupling on analyte refractive index, both large range and high sensitivity can be achieved in the one device. We also show that sel...

  16. External electric and magnetic field effects on the optical absorption coefficients and refractive index changes of a hydrogenic impurity confined in a cylindrical quantum wire with convex bottom

    International Nuclear Information System (INIS)

    In this paper, we have studied the simultaneous effects of external electric and magnetic fields on the optical absorption coefficients and refractive index changes of a hydrogenic impurity confined in a cylindrical quantum wire with convex bottom. Energy eigenvalues and eigenvectors are calculated using the direct matrix diagonalization method and optical properties are obtained using the compact density matrix approach. Our results indicate that, the wire radius, convexity parameter, hydrogenic impurity and external electric and magnetic fields have a great influence on the linear and the third-order nonlinear optical absorption coefficients as well as the refractive index changes of the system

  17. Refractive index of plant cell walls

    Science.gov (United States)

    Gausman, H. W.; Allen, W. A.; Escobar, D. E.

    1974-01-01

    Air was replaced with media of higher refractive indices by vacuum infiltration in leaves of cucumber, blackeye pea, tomato, and string bean plants, and reflectance of noninfiltrated and infiltrated leaves was spectrophotometrically measured. Infiltrated leaves reflected less light than noninfiltrated leaves over the 500-2500-nm wavelength interval because cell wall-air interfaces were partly eliminated. Minimal reflectance should occur when the average refractive index of plant cell walls was matched by the infiltrating fluid. Although refractive indices that resulted in minimal reflectance differed among the four plant genera, an average value of 1.425 approximates the refractive index of plant cell walls for the four plant genera.

  18. The refractive index of relic gravitons

    Science.gov (United States)

    Giovannini, Massimo

    2016-06-01

    The dynamical evolution of the refractive index of the tensor modes of the geometry produces a specific class of power spectra characterized by a blue (i.e. slightly increasing) slope which is directly determined by the competition of the slow-roll parameter and of the rate of variation of the refractive index. Throughout the conventional stages of the inflationary and post-inflationary evolution, the microwave background anisotropies measurements, the pulsar timing limits and the big-bang nucleosynthesis constraints set stringent bounds on the refractive index and on its rate of variation. Within the physically allowed region of the parameter space the cosmic background of relic gravitons leads to a potentially large signal for the ground-based detectors (in their advanced version) and for the proposed space-borne interferometers. Conversely, the lack of direct detection of the signal will set a qualitatively new bound on the dynamical variation of the refractive index.

  19. The refractive index of relic gravitons

    CERN Document Server

    Giovannini, Massimo

    2016-01-01

    The dynamical evolution of the refractive index of the tensor modes of the geometry produces a specific class of power spectra characterized by a blue (i.e. slightly increasing) slope which is directly determined by the competition of the slow-roll parameter and of the rate of variation of the refractive index. Throughout the conventional stages of the inflationary and post-inflationary evolution, the microwave background anisotropies measurements, the pulsar timing limits and the big-bang nucleosythesis constraints set stringent bounds on the refractive index and on its rate of variation. Within the physically allowed region of the parameter space the cosmic background of relic gravitons leads to a potentially large signal for the ground based detectors (in their advanced version) and for the proposed space-borne interferometers. Conversely, the lack of direct detection of the signal will set a qualitatively new bound on the dynamical variation of the refractive index.

  20. Refractive index contrast in porous silicon multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Nava, R.; Mora, M.B. de la; Tagueena-Martinez, J. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Temixco, Morelos (Mexico); Rio, J.A. del [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Temixco, Morelos (Mexico); Centro Morelense de Innovacion y Transferencia Tecnologica, Consejo de Ciencia y Tecnologia del Estado de Morelos (Mexico)

    2009-07-15

    Two of the most important properties of a porous silicon multilayer for photonic applications are flat interfaces and a relative large refractive index contrast between layers in the optical wavelength range. In this work, we studied the effect of the current density and HF electrolyte concentration on the refractive index of porous silicon. With the purpose of increasing the refractive index contrast in a multilayer, the refractive index of porous silicon produced at low current was studied in detail. The current density applied to produce the low porosity layers was limited in order to keep the electrolyte flow through the multilayer structure and to avoid deformation of layer interfaces. We found that an electrolyte composed of hydrofluoric acid, ethanol and glycerin in a ratio of 3:7:1 gives a refractive index contrast around 1.3/2.8 at 600 nm. Several multilayer structures with this refractive index contrast were fabricated, such as dielectric Bragg mirrors and microcavities. Reflectance spectra of the structures show the photonic quality of porous silicon multilayers produced under these electrochemical conditions. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Exciton-related nonlinear optical absorption and refractive index change in GaAs-Ga{sub 1-x}Al{sub x}As double quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, Guillermo L. [Fisica Teorica y Aplicada, Escuela de Ingenieria de Antioquia, A.A. 7516 Medellin (Colombia); Instituto de Fisica, Universidad de Antioquia, AA 1226 Medellin (Colombia); Mora-Ramos, Miguel E., E-mail: memora@uaem.mx [Fisica Teorica y Aplicada, Escuela de Ingenieria de Antioquia, A.A. 7516 Medellin (Colombia); Facultad de Ciencias, Universidad Autonoma del Estado de Morelos, Av. Universidad 1001, C.P. 62209 Cuernavaca, Morelos (Mexico); Instituto de Fisica, Universidad de Antioquia, AA 1226 Medellin (Colombia); Duque, Carlos A. [Instituto de Fisica, Universidad de Antioquia, AA 1226 Medellin (Colombia)

    2013-01-15

    In this work the variations of the exciton-related optical absorption and the change of the refractive index in a GaAs-(Ga,Al)As double quantum well as functions of the geometric parameters of the heterostructure are investigated. The variational method is applied within the framework of the parabolic band and effective mass approximations, in order to obtain the 1s-like exciton energy spectrum. The outcome for the related optical coefficients shows a quenched and redshifted light absorption as a result of the increment in the inner barrier and right-hand well widths, with the possibility of an enhancement of the excitonic contribution to the relative change in the refractive index.

  2. Integrated Microfibre Device for Refractive Index and Temperature Sensing

    Directory of Open Access Journals (Sweden)

    Sulaiman W. Harun

    2012-08-01

    Full Text Available A microfibre device integrating a microfibre knot resonator in a Sagnac loop reflector is proposed for refractive index and temperature sensing. The reflective configuration of this optical structure offers the advantages of simple fabrication and ease of sensing. To achieve a balance between responsiveness and robustness, the entire microfibre structure is embedded in low index Teflon, except for the 0.5–2 mm diameter microfibre knot resonator sensing region. The proposed sensor has exhibited a linear spectral response with temperature and refractive index. A small change in free spectral range is observed when the microfibre device experiences a large refractive index change in the surrounding medium. The change is found to be in agreement with calculated results based on dispersion relationships.

  3. Comment on "Linear and nonlinear optical absorption coefficients and refractive index changes in asymmetrical Gaussian potential quantum wells with applied electric field"

    Science.gov (United States)

    Yuan, Jian-Hui; Zhang, Zhi-Hai

    2015-12-01

    Guo and Du (2013) reported theirs result for the linear and nonlinear optical absorption coefficients and refractive index changes in asymmetrical Gaussian potential quantum wells with applied electric field. We find both the energy and the corresponding wavefunction for the low-lying state are wrong to applied in their works. For the same set of parameters studied by Guo and Du, we obtain new and reliable results via the differential method.

  4. A Liquid Prism for Refractive Index Studies

    Science.gov (United States)

    Edmiston, Michael D.

    2001-11-01

    A hollow glass prism filled with liquid becomes a "liquid prism". A simple method for constructing hollow glass prisms is presented. A method is given for a demonstration that uses the liquid prism with a laser or laser pointer so the audience can observe differences in refractive index for various liquids. The demonstration provides a quick and easy determination of the sugar content of soft drinks and juices. The prism makes it easy to determine a numerical value for the refractive index of a liquid.

  5. As2S8 planar waveguide: refractive index changes following an annealing and irradiation and annealing cycle, and light propagation features

    Institute of Scientific and Technical Information of China (English)

    Zou Liner; Wang Gouri; Shen Yun; Chen Baoxue; Mamoru Iso

    2011-01-01

    The refractive index of as-evaporated amorphous semiconductor As2S8 film upon an annealing and saturation irradiation and annealing cycle is reversible.Upon successive treatment with annealing and non-saturation irradiation and further annealing,the refractive index of the as-evaporated amorphous semiconductor As2 S8 film reaches a maximum value and then its reversibility occurs upon annealing.The annealing of the amorphous semiconductor As2S8 films results in the stabilization of the structure through changes of the S-S bonds in the nearest environment,accompanied by a decrease of film thickness.The As2S8 planar waveguide after annealing (130 ℃)and saturation irradiation and annealing (130 ℃) shows a good propagation characteristic with ca.0.27 dB/cm low propagation loss of the 632.8 nm guided mode.

  6. Refractive index dispersion law of silica aerogel

    International Nuclear Information System (INIS)

    This paper presents measurements of the refractive index of a hygroscopic silica aerogel block at several wavelengths. The measurements, performed with a monochromator, have been compared with different parameterisations for n(λ), in order to determine the best chromaticity law for the aerogel. This is an important input for design and operation of RICH detectors with silica aerogel radiator. (orig.)

  7. Refractive index dependence of Papilio Ulysses butterfly wings reflectance spectra

    Science.gov (United States)

    Isnaeni, Muslimin, Ahmad Novi; Birowosuto, Muhammad Danang

    2016-02-01

    We have observed and utilized butterfly wings of Papilio Ulysses for refractive index sensor. We noticed this butterfly wings have photonic crystal structure, which causes blue color appearance on the wings. The photonic crystal structure, which consists of cuticle and air void, is approximated as one dimensional photonic crystal structure. This photonic crystal structure opens potential to several optical devices application, such as refractive index sensor. We have utilized small piece of Papilio Ulysses butterfly wings to characterize refractive index of several liquid base on reflectance spectrum of butterfly wings in the presence of sample liquid. For comparison, we simulated reflectance spectrum of one dimensional photonic crystal structure having material parameter based on real structure of butterfly wings. We found that reflectance spectrum peaks shifted as refractive index of sample changes. Although there is a slight difference in reflectance spectrum peaks between measured spectrum and calculated spectrum, the trend of reflectance spectrum peaks as function of sample's refractive index is the similar. We assume that during the measurement, the air void that filled by sample liquid is expanded due to liquid pressure. This change of void shape causes non-similarity between measured spectrum and calculated spectrum.

  8. Enhanced nonlinear refractive index in epsilon-near-zero materials

    CERN Document Server

    Caspani, L; Clerici, M; Ferrera, M; Roger, T; Di Falco, A; Kim, J; Kinsey, N; Shalaev, V M; Boltasseva, A; Faccio, D

    2016-01-01

    New propagation regimes for light arise from the ability to tune the dielectric permittivity to extremely low values. Here we demonstrate a universal approach based on the low linear permittivity values attained in the epsilon-near-zero (ENZ) regime for enhancing the nonlinear refractive index, which enables remarkable light-induced changes of the material properties. Experiments performed on Al-doped ZnO (AZO) thin films show a six-fold increase of the Kerr nonlinear refractive index ($n_2$) at the ENZ wavelength, located in the 1300 nm region. This in turn leads to light-induced refractive index changes of the order of unity, thus representing a new paradigm for nonlinear optics.

  9. Enhanced Nonlinear Refractive Index in ε-Near-Zero Materials.

    Science.gov (United States)

    Caspani, L; Kaipurath, R P M; Clerici, M; Ferrera, M; Roger, T; Kim, J; Kinsey, N; Pietrzyk, M; Di Falco, A; Shalaev, V M; Boltasseva, A; Faccio, D

    2016-06-10

    New propagation regimes for light arise from the ability to tune the dielectric permittivity to extremely low values. Here, we demonstrate a universal approach based on the low linear permittivity values attained in the ε-near-zero (ENZ) regime for enhancing the nonlinear refractive index, which enables remarkable light-induced changes of the material properties. Experiments performed on Al-doped ZnO (AZO) thin films show a sixfold increase of the Kerr nonlinear refractive index (n_{2}) at the ENZ wavelength, located in the 1300 nm region. This in turn leads to ultrafast light-induced refractive index changes of the order of unity, thus representing a new paradigm for nonlinear optics. PMID:27341234

  10. Refractive index determination by coherence scanning interferometry.

    Science.gov (United States)

    Yoshino, H; Kaminski, P M; Smith, R; Walls, J M; Mansfield, D

    2016-05-20

    Coherence scanning interferometry is established as a powerful noncontact, three-dimensional, metrology technique used to determine accurate surface roughness and topography measurements with subnanometer precision. The helical complex field (HCF) function is a topographically defined helix modulated by the electrical field reflectance, originally developed for the measurement of thin films. An approach to extend the capability of the HCF function to determine the spectral refractive index of a substrate or absorbing film has recently been proposed. In this paper, we confirm this new capability, demonstrating it on surfaces of silicon, gold, and a gold/palladium alloy using silica and zirconia oxide thin films. These refractive index dispersion measurements show good agreement with those obtained by spectroscopic ellipsometry. PMID:27411157

  11. Negative Refractive Index Metasurfaces for Enhanced Biosensing

    Directory of Open Access Journals (Sweden)

    Dragan Tanasković

    2010-12-01

    Full Text Available In this paper we review some metasurfaces with negative values of effective refractive index, as scaffolds for a new generation of surface plasmon polariton-based biological or chemical sensors. The electromagnetic properties of a metasurface may be tuned by its full immersion into analyte, or by the adsorption of a thin layer on it, both of which change its properties as a plasmonic guide. We consider various simple forms of plasmonic crystals suitable for this purpose. We start with the basic case of a freestanding, electromagnetically symmetrical plasmonic slab and analyze different ultrathin, multilayer structures, to finally consider some two-dimensional “wallpaper” geometries like split ring resonator arrays and fishnet structures. A part of the text is dedicated to the possibility of multifunctionalization where a metasurface structure is simultaneously utilized both for sensing and for selectivity enhancement. Finally we give an overview of surface-bound intrinsic electromagnetic noise phenomena that limits the ultimate performance of a metasurfaces sensor.

  12. Comparative study on the change in index of refraction in ion-exchange interdiffusion in alkali-silicate glasses containing calcium, strontium, barium and titanium oxides

    International Nuclear Information System (INIS)

    Different ability to ion exchange from the salts of lithium-sodium-silicate glass melt containing calcium (or strontium, or barium) and titanium oxides in addition has been shown. CaO, SrO and BaO have negative effect, but TiO2 -positive one on the fullness of ion exchange of lithium-sodium and on the rate of interdiffusion in alkali-silicate glass. The value of change in index of refraction of glass with TiO2 is twice higher than glass with calcium oxide (or strontium, or barium) as the fourth component

  13. Diffraction tomography for plasma refractive index measurements

    International Nuclear Information System (INIS)

    Measurement of the properties of probing beams of coherent electromagnetic radiation yields essential information about the line of sight integrated plasma refractive index. Presented is a scalar diffraction treatment of forward angle scattering plasma diagnostics based on the diffraction projection theorem first presented by E. Wolf in 1969. New results are obtained for near field scattering from probing Gaussian beams and it is demonstrated that the effects of diffraction need to be addressed for tomographic inversion of near field scattering and interferometry data. 33 refs., 10 figs

  14. The refractive index of reciprocal electromagnetic media

    Science.gov (United States)

    McCall, Martin W.; Kinsler, Paul; Topf, Renè D. M.

    2016-04-01

    We study the electromagnetics of media described by identical inhomogeneous relative dielectric and magnetic tensors, {\\boldsymbol{ε }}={\\boldsymbol{μ }}. Such media occur generically as spatial transformation media, i.e. electromagnetic media that are defined by a deformation of space. We show that such media are completely described by a refractive index n({r},\\hat{{s}}) that depends on position {r} and direction \\hat{{s}}, but is independent of polarization. The phase surface is always ellipsoidal, and n({r},\\hat{{s}}) is therefore represented by the radius vector to the surface of the ellipsoid. We apply our method to calculate the angular dependence of the refractive index in the well-studied cylindrical cloak and to a new kind of structurally chiral medium induced by a twist deformation. By way of a simple example we also show that media for which {\\boldsymbol{ε }}={\\boldsymbol{μ }} do not in general preserve the impedance properties of vacuum. The implications of this somewhat surprising conclusion for the field of transformation optics are discussed.

  15. Refractive index changes induced by sheet beams with various intensity distributions in LiNbO3:Fe crystal

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Peng; ZHAO; Jianlin; XU; Honglai; SUN; Yidong; YANG

    2005-01-01

    According to the Kukhtarev equations and a simplified model based on the photovoltaic charge carriers transport mechanism, the distributions of the index changes (DICs) in LiNbO3:Fe crystals induced by sheet beams with various intensity profiles are theoretically analyzed. The numerically simulated results coincide with the analytic expressions deduced from the simplified model. The DICs in a LiNbO3:Fe crystal induced by sheet beams with rectangular, Gaussian and square law profiles are measured by using the interferometric method. By employing the analytic expressions, the experimental data points are well fitted. By utilizing the angular spectrum theory and the ray equation, the uniformities of the intensity profiles of the writing beams along the propagation directions and the influences of the self-defocusing effect of the crystal are numerically simulated, respectively. The results show that the experimental results are reliable. The numerically simulated method and the analytic expressions can be both employed to predict the DICs induced by sheet beams with various light intensity profiles. Furthermore, utilizing writing beams with proper intensity profiles, any desired index distributions could be obtained.

  16. Negative refractive index of layered nonmagnetic/magnetic composites

    International Nuclear Information System (INIS)

    We investigate the possibility of preparing left-handed material in a layered alternated nonmagnetic/magnetic composite under different direction of incident electromagnetic wave at the microwave region. We calculate the effective refractive index of the layered composites and find that the effective refractive index varies as a function of the volume fraction of one component of the composite. Especially, within the certain volume fraction of component 1 (or 2) the effective refractive index can be negative at a finite frequency region. Moreover, we find that the direction of the incident electromagnetic wave affects the effective refractive index greatly. When the incident electric field is parallel to the laminations and the magnetic field is perpendicular to the laminations, the volume fraction of component 1 (or 2) range, which causes the effective refractive index to be negative, is relatively wider than that of the opposite case, but the absolute values of the negative refractive index are smaller than that of the opposite case

  17. The refractive index of human hemoglobin in the visible range

    International Nuclear Information System (INIS)

    Because the refractive index of hemoglobin in the visible range is sensitive to the hemoglobin concentration, optical investigations of hemoglobin are important for medical diagnostics and treatment. Direct measurements of the refractive index are, however, challenging; few such measurements have previously been reported, especially in a wide wavelength range. We directly measured the refractive index of human deoxygenated and oxygenated hemoglobin for nine wavelengths between 400 and 700 nm for the hemoglobin concentrations up to 140 g l-1. This paper analyzes the results and suggests a set of model functions to calculate the refractive index depending on the concentration. At all wavelengths, the measured values of the refractive index depended on the concentration linearly. Analyzing the slope of the lines, we determined the specific refraction increments, derived a set of model functions for the refractive index depending on the concentration, and compared our results with those available in the literature. Based on the model functions, we further calculated the refractive index at the physiological concentration within the erythrocytes of 320 g l-1. The results can be used to calculate the refractive index in the visible range for arbitrary concentrations provided that the refractive indices depend on the concentration linearly.

  18. The refractive index of human hemoglobin in the visible range

    Energy Technology Data Exchange (ETDEWEB)

    Zhernovaya, O; Tuchin, V [International Research-Educational Center of Optical Technologies for Industry and Medicine ' Photonics' , Saratov State University, 83 Astrakhanskaya str., 410012 Saratov (Russian Federation); Sydoruk, O [Optical and Semiconductor Devices Group, Department of Electrical and Electronic Engineering, South Kensington Campus, Imperial College London, London SW7 2AZ (United Kingdom); Douplik, A, E-mail: alexandre.douplik@aot.uni-erlangen.de [Medical Photonics Engineering Group, Chair of Photonic Technologies, Friedrich-Alexander University Erlangen-Nuremberg, Paul-Gordan-Strasse 3, 91052 Erlangen (Germany)

    2011-07-07

    Because the refractive index of hemoglobin in the visible range is sensitive to the hemoglobin concentration, optical investigations of hemoglobin are important for medical diagnostics and treatment. Direct measurements of the refractive index are, however, challenging; few such measurements have previously been reported, especially in a wide wavelength range. We directly measured the refractive index of human deoxygenated and oxygenated hemoglobin for nine wavelengths between 400 and 700 nm for the hemoglobin concentrations up to 140 g l{sup -1}. This paper analyzes the results and suggests a set of model functions to calculate the refractive index depending on the concentration. At all wavelengths, the measured values of the refractive index depended on the concentration linearly. Analyzing the slope of the lines, we determined the specific refraction increments, derived a set of model functions for the refractive index depending on the concentration, and compared our results with those available in the literature. Based on the model functions, we further calculated the refractive index at the physiological concentration within the erythrocytes of 320 g l{sup -1}. The results can be used to calculate the refractive index in the visible range for arbitrary concentrations provided that the refractive indices depend on the concentration linearly.

  19. Nonlinear absorption coefficient and relative refraction index change for an asymmetrical double δ-doped quantum well in GaAs with a Schottky barrier potential

    International Nuclear Information System (INIS)

    In this work we are reporting the energy level spectrum for a quantum system consisting of an n-type double δ-doped quantum well with a Schottky barrier potential in a Gallium Arsenide matrix. The calculated states are taken as the basis for the evaluation of the linear and third-order nonlinear contributions to the optical absorption coefficient and to the relative refractive index change, making particular use of the asymmetry of the potential profile. These optical properties are then reported as a function of the Schottky barrier height (SBH) and the separation distance between the δ-doped quantum wells. Also, the effects of the application of hydrostatic pressure are studied. The results show that the amplitudes of the resonant peaks are of the same order of magnitude of those obtained in the case of single δ-doped field effect transistors; but tailoring the asymmetry of the confining potential profile allows the control the resonant peak positions

  20. Nonlinear absorption coefficient and relative refraction index change for an asymmetrical double δ-doped quantum well in GaAs with a Schottky barrier potential

    Energy Technology Data Exchange (ETDEWEB)

    Rojas-Briseño, J.G.; Martínez-Orozco, J.C.; Rodríguez-Vargas, I. [Unidad Académica de Física, Universidad Autónoma de Zacatecas, Calzada Solidaridad esquina con Paseo la Bufa S/N, C.P. 98060, Zacatecas, Zac. (Mexico); Mora-Ramos, M.E. [Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, CP 62209, Cuernavaca, Morelos (Mexico); Instituto de Física, Universidad de Antioquia, AA 1226, Medellín (Colombia); Duque, C.A., E-mail: cduque@fisica.udea.edu.co [Instituto de Física, Universidad de Antioquia, AA 1226, Medellín (Colombia)

    2013-09-01

    In this work we are reporting the energy level spectrum for a quantum system consisting of an n-type double δ-doped quantum well with a Schottky barrier potential in a Gallium Arsenide matrix. The calculated states are taken as the basis for the evaluation of the linear and third-order nonlinear contributions to the optical absorption coefficient and to the relative refractive index change, making particular use of the asymmetry of the potential profile. These optical properties are then reported as a function of the Schottky barrier height (SBH) and the separation distance between the δ-doped quantum wells. Also, the effects of the application of hydrostatic pressure are studied. The results show that the amplitudes of the resonant peaks are of the same order of magnitude of those obtained in the case of single δ-doped field effect transistors; but tailoring the asymmetry of the confining potential profile allows the control the resonant peak positions.

  1. Investigation of the change in the refractive index of the active medium of a laser by the optical delay method utilizing emitted radiation. [Iodine

    Energy Technology Data Exchange (ETDEWEB)

    Zuev, V.S.; Korol' kov, K.S.; Netemin, V.N.; Nosach, O.Y.; Orlov, E.P.

    1976-11-01

    An optical delay method is proposed for investigation of the change in the refractive index of the active medium of a laser at the wavelength of its stimulated emission. Criteria of the validity of this method are obtained and an analysis is made of the errors in the measurement of ..delta..n. A specific optical delay system is described and tested in an experimental determination of the distribution of ..delta..n in an iodine laser pumped by an open discharge. The results of simultaneous measurements of ..delta..n in the light of a ruby laser are also reported. The distributions of ..delta..n at the emission wavelength of the iodine laser (1.315 ..mu..) and at the ruby laser wavelength (0.6943 ..mu..) are identical. The experimental results are used in an estimate of the characteristics of the wave front of the radiation emitted from the iodine laser.

  2. Characterization of refractive index distribution of polymer optical fiber

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A focusing method is developed to characterize the refractive index profile of polymer optical fiber (POF). Based on the refractive index profile the theoretical bandwidth and the core index exponentα (α > 0) of POF are calculated. The results show that the value of theoretical bandwidth agrees well with the experimental data.

  3. Calculation of electron wave functions and refractive index of Ne

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The radial wave functions of inner electron shell and outer electron shell of a Ne atom were obtained by the approximate analytical method and tested by calculating the ground state energy of the Ne atom. The equivalent volume of electron cloud and the refractive index of Ne were calculated. The calculated refractive index agrees well with the experimental result. Relationship between the refractive index and the wave function of Ne was discovered.

  4. The preparation and refractive index of BST thin films

    International Nuclear Information System (INIS)

    Radio-frequency magnetron sputtering technique is used to deposit Ba0.65Sr0.35TiO3 (BST) thin films on fused quartz substrates. In order to prepare the high-quality BST thin films, the crystallization and microstructure of the films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). More intense characteristic diffraction peaks and better crystallization can be observed in BST thin films deposited at 600 deg. C and subsequently annealed at 700 deg. C. The refractive index of the films is determined from the measured transmission spectra. The dependences of the refractive index on the deposition parameters of BST thin films are different. The refractive index of the films increases with the substrate temperature. At lower sputtering pressure, the refractive index increases from 1.797 to 2.197 with pressure increase. However, when the pressure increases up to 3.9 Pa, the refractive index reduces to 1.86. The oxygen to argon ratio also plays an important effect on the refractive index of the films. It has been found that the refractive index increases with increase in the ratio of oxygen to argon. The refractive index of BST thin films is strongly dependent on the annealing temperature, which also increases as the annealing temperature ascends. In a word, the refractive index of BST thin films is finally affected by the films' microstructure and texture

  5. Empirical formula for the refractive index of freezing brine

    DEFF Research Database (Denmark)

    Frisvad, Jeppe Revall

    2009-01-01

    The refractive index of freezing brine is important for example in order to estimate oceanic scattering as sea ice develops. Previously, no simple continuous expression was available for estimating the refractive index of brine at subzero temperatures. I show that extrapolation of the empirical f...... formula for the refractive index of seawater by Quan and Fry [Appl. Opt. 34(18), 3477-3480 (1995)] provides a good fit to the refractive index of freezing brine for temperatures above -24 degrees celsius and salinities below 180 parts per thousand....

  6. A simple optical probing technique for nonlinearly induced refractive index

    Science.gov (United States)

    Banerjee, Partha; Abeywickrema, Ujitha

    2013-09-01

    Self phase modulation is a nonlinear effect that is observed when a laser beam is focused on to a high-absorbing thermal medium. A regular tea sample in a plastic cuvette is used as the nonlinear absorbing sample. The change in the refractive index of the medium occurs due to the heat generated by the focused pump beam, which in turn changes the refractive index. In this paper, self phase modulation is investigated in different ways. An Ar-Ion laser of 514 nm is used as the pump beam and a 632 nm He-Ne laser is used as the probe beam. The probe beam is introduced from the opposite side of the pump beam. Ring patterns are observed from the each side of the sample. Regular far field ring patterns are observed from the pump beam, and two sets of rings are observed with the probe beam. The behaviors of these inner and outer rings are monitored for different pump powers. The steady state heat equation is solved to obtain an exact solution for the radial heat distribution and far field ring patterns are simulated using the Fresnel-Kirchhoff diffraction integral. Ring patterns are theoretically explained using simulations results, and compared with experimental observations. Finally, an interferometric setup using the low power He-Ne laser is also used to determine the induced change in refractive index. Results are compared with those obtained directly from self-phase modulation and from the probe beam method.

  7. Atmospheric stability index using radio occultation refractivity profiles

    Indian Academy of Sciences (India)

    D Jagadheesha; B Manikiam; Neerja Sharma; P K Pal

    2011-04-01

    A new stability index based on atmospheric refractivity at ∼500 hPa level and surface measurements of temperature, pressure and humidity is formulated. The new index named here as refractivity based lifted index (RLI) is designed to give similar results as traditionally used lifted index derived from radiosonde profiles of temperature, pressure and humidity. The formulation of the stability index and its comparison with the traditional temperature profile based lifted index (LI) is discussed. The index is tested on COSMIC radio occultation derived refractivity profiles over Indian region. The forecast potential of the new index for rainfall on 2° × 2° latitude–longitude spatial scale with lead time of 3–24 hours indicate that the refractivity based lifted index works better than the traditional temperature based lifted index for the Indian monsoon region. Decreasing values of RLI tend to give increasing rainfall probabilities.

  8. Refractive Index Compensation in Over-Determined Interferometric Systems

    Directory of Open Access Journals (Sweden)

    Zdeněk Buchta

    2012-10-01

    Full Text Available We present an interferometric technique based on a differential interferometry setup for measurement under atmospheric conditions. The key limiting factor in any interferometric dimensional measurement are fluctuations of the refractive index of air representing a dominating source of uncertainty when evaluated indirectly from the physical parameters of the atmosphere. Our proposal is based on the concept of an over-determined interferometric setup where a reference length is derived from a mechanical frame made from a material with a very low thermal coefficient. The technique allows one to track the variations of the refractive index of air on-line directly in the line of the measuring beam and to compensate for the fluctuations. The optical setup consists of three interferometers sharing the same beam path where two measure differentially the displacement while the third evaluates the changes in the measuring range, acting as a tracking refractometer. The principle is demonstrated in an experimental setup.

  9. Ultraviolet light induced refractive index structures in germanosilica

    DEFF Research Database (Denmark)

    Svalgaard, Mikael

    1997-01-01

    bulk optics. Finally, I have developed a new method for direct UV writing of planar waveguide devices using a focussed continuous wave UV laser beam which is scanned across a photosensitive thin film deposited on a silicon wafer. Contrary to other waveguide fabrication techniques this method requires...... application of a scanning near-field optical microscope to obtain high resolution images of UV induced refractive index structures and by monitoring the dynamics of UV induced index changes and luminescence. During part of my ph.d. project I have worked at the National Institute of Standards and Technolgy in...

  10. Targeted alteration of real and imaginary refractive index of biological cells by histological staining

    OpenAIRE

    Cherkezyan, Lusik; Subramanian, Hariharan; Stoyneva, Valentina; Rogers, Jeremy D.; Yang, Seungmoo; Damania, Dhwanil; Taflove, Allen; Backman, Vadim

    2012-01-01

    Various staining techniques are commonly used in biomedical research to investigate cellular morphology. By inducing absorption of light, staining dyes change the intracellular refractive index due to the Kramers-Kronig relationship. We present a method for creating 2-D maps of real and imaginary refractive indices of stained biological cells using their thickness and absorptance. We validate our technique on dyed polystyrene microspheres and quantify the alteration in refractive index of sta...

  11. Determination of changes in refractive index and thickness of SiO2 thin film on polycarbonate created by Vis-IR laser irradiation

    International Nuclear Information System (INIS)

    Complete text of publication follows. The effect of Vis-IR laser irradiation at various energy densities on refractive index and thickness of SiO2 thin film onto polycarbonate was reported in this paper. Transmittance spectra were used for determination the above characteristics of these films by application of analytical formulas was to the interference extrema. (Swanepoel method). It has been found that the thickness of films decrease by increasing the photon energy of laser and its energy density. It has been observed that the transmittance decreases with the increase of film thickness. From transmittance data, the dispersion of refractive index of sample has been studied. It was found that at high energy density (50 .35 J/cm2), the refractive index of sample was more increased. The highest increased in refractive index (Δn ∼ 0.1) was found for sample which irradiated by 532 nm laser beam with 50.35 J/cm2 energy density.

  12. Why is the refractive index cannot be negative

    CERN Document Server

    Davidovich, Michael V

    2014-01-01

    It has been shown that for left-handed metamaterials and generally for negative refraction media the refraction index cannot be entered unequivocally and cannot be considered as real, and especially as negative. This index for above referred media is not expedient

  13. Determination of the complex refractive index of cell cultures by reflectance spectrometry

    Science.gov (United States)

    Calin, Mihaela Antonina; Calin, Marian Romeo; Munteanu, Constantin

    2014-06-01

    In this paper we propose a new approach to using reflectance spectrometry in connection with the Kramers-Kronig analysis for the determination of the complex refractive index of biological cells. Applying this procedure, the real and imaginary parts of the refractive index (refractive index and extinction coefficient) can be simultaneously determined. The accuracy of this procedure in the determination of the refractive index and extinction coefficient of culture media proved to be comparable with spectroscopic ellipsometry. Applying this procedure on the human umbilical vein endothelial cells (HUVEC), the results obtained from time-series measurements showed significant changes in the complex refractive index of cell cultures within 72h, the most important increases for both real and imaginary parts of the refractive index being recorded in the first 24h, when synthesis processes are happening. Thus, the analysis of the time-dependent changes in the complex refractive index provides information about the frequencies of the modifications that occur on both organizational structure and cells composition during the cell cycle. In conclusion, the combination of reflectance spectrometry with the Kramers-Kronig analysis is a feasible way to determine the complex refractive index of biological cells and to assess the events taking place during the cell cycle.

  14. Intersubband optical absorption coefficients and refractive index changes in a graded quantum well under intense laser field: Effects of hydrostatic pressure, temperature and electric field

    Energy Technology Data Exchange (ETDEWEB)

    Ungan, F., E-mail: fungan@cumhuriyet.edu.tr [Department of Physics, Cumhuriyet University, 58140 Sivas (Turkey); Grupo de Materia Condensade-UdeA, Instituto de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Restrepo, R.L. [Grupo de Materia Condensade-UdeA, Instituto de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Escuela de Ingeniería de Antioquia AA 7516, Medellín (Colombia); Mora-Ramos, M.E. [Grupo de Materia Condensade-UdeA, Instituto de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Facultad de Ciencias, Universidad Autonoma del Estado de Morelos, Ave. Universidad 1001, CP 62209, Cuernavaca, Morelos (Mexico); Morales, A.L.; Duque, C.A. [Grupo de Materia Condensade-UdeA, Instituto de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia)

    2014-02-01

    The effects of hydrostatic pressure, temperature, and electric field on the optical absorption coefficients and refractive index changes associated with intersubband transition in a typical GaAs/Ga{sub 0.7}Al{sub 0.3}As graded quantum well under intense laser field have been investigated theoretically. The electron energy eigenvalues and the corresponding eigenfunctions of the graded quantum well are calculated within the effective mass approximation and envelope wave function approach. The analytical expressions of the optical properties are obtained using the compact density-matrix approach and the iterative method. The numerical results show that the linear and nonlinear optical properties depend strongly on the intense laser field and electric field but weakly on the hydrostatic pressure and temperature. Additionally, it has been found that the electronic and optical properties in a GaAs/Ga{sub 0.7}Al{sub 0.3}As graded quantum well under the intense laser field can be tuned by changing these external inputs. Thus, these results give a new degree of freedom in the devices applications.

  15. Intersubband optical absorption coefficients and refractive index changes in a graded quantum well under intense laser field: Effects of hydrostatic pressure, temperature and electric field

    International Nuclear Information System (INIS)

    The effects of hydrostatic pressure, temperature, and electric field on the optical absorption coefficients and refractive index changes associated with intersubband transition in a typical GaAs/Ga0.7Al0.3As graded quantum well under intense laser field have been investigated theoretically. The electron energy eigenvalues and the corresponding eigenfunctions of the graded quantum well are calculated within the effective mass approximation and envelope wave function approach. The analytical expressions of the optical properties are obtained using the compact density-matrix approach and the iterative method. The numerical results show that the linear and nonlinear optical properties depend strongly on the intense laser field and electric field but weakly on the hydrostatic pressure and temperature. Additionally, it has been found that the electronic and optical properties in a GaAs/Ga0.7Al0.3As graded quantum well under the intense laser field can be tuned by changing these external inputs. Thus, these results give a new degree of freedom in the devices applications

  16. Effect of magnetic field of light on refractive index

    Institute of Scientific and Technical Information of China (English)

    Zhang Tao

    2004-01-01

    Light refraction in a medium results from energy exchange between the medium and the magnetic field of the light. Formulas of refractive index, that is, the ratio of light speed in vacuum to light speed in the medium, were derived with the inductor model of electron cloud and the law of energy conservation. Refractive indices of several media were calculated using the formulas derived, and the calculated results are in agreement with the results measured. The anisotropy and the nonlinearity of the refractive index are explained with the theory described in this work.

  17. Measurement of air refractive index fluctuation based on a laser synthetic wavelength interferometer

    International Nuclear Information System (INIS)

    A novel method for measuring air refractive index fluctuation based on a laser synthetic wavelength interferometer is proposed. The change of air refractive index is regarded as an equivalent measured displacement in the measurement arm, which can be realized by tracking a large compensative displacement of the reference mirror in the reference arm of the laser synthetic wavelength interferometer. The merit of the proposed method is that the slight air refractive index fluctuation is magnified to a large displacement on the order of millimeters or micrometers. To verify the feasibility of the proposed method, the correlation experiment between the displacement of the reference mirror and the air refractive index fluctuation and the comparison experiments with Edlén equations both in short time and long time were performed. Experimental results show that the measurement accuracy of the air refractive index fluctuation is better than 3.7 × 10–8. (paper)

  18. Sensing of refractive index based on mode interference in a five-layer slab waveguide

    Science.gov (United States)

    Tang, Tingting; Ma, Wenying; Liu, Wenli; He, Xiujun

    2015-01-01

    We propose a refractive index sensor based on the mode interference in a five-layer waveguide. The propagation properties are analyzed by the coupled mode theory, and the function of the waveguide as a refractive index sensor is also explored based on simulation results. Taking into consideration a trade-off between the sensitivity and the size of the proposed sensor, we can get a very compact device of 10.8 μm×1 μm, and the sensing resolution of the proposed refractive index can reach 2.25×10-5 RIU for index change at around 1.455.

  19. Study of the refractive index change in a-Si:H thin films patterned by 532 nm laser radiation for photovoltaic applications

    Energy Technology Data Exchange (ETDEWEB)

    Colina, M., E-mail: monica.colina.brito@upm.e [Centro Laser UPM, Univ. Politecnica de Madrid, Ctra. de Valencia Km 7.3, 28031 Madrid (Spain); Molpeceres, C.; Holgado, M. [Centro Laser UPM, Univ. Politecnica de Madrid, Ctra. de Valencia Km 7.3, 28031 Madrid (Spain); Gandia, J. [Dept. de Energias Renovables, Energia Solar Fotovoltaica, CIEMAT, Avda, Complutense 22, 28040 Madrid (Spain); Nos, O. [CeRMAE Dept. Fisica Aplicada i Optica, Universitat de Barcelona, Av. Diagonal 647, 08028 Barcelona (Spain); Ocana, J.L. [Centro Laser UPM, Univ. Politecnica de Madrid, Ctra. de Valencia Km 7.3, 28031 Madrid (Spain)

    2010-07-01

    Laser scribing of hydrogenated amorphous silicon (a-Si:H) is a crucial step in the fabrication of thin film photovoltaic modules. During such process, inherent thermo-mechanical effects associated to laser ablation mechanisms lead to thermal damages. In that sense, the state of the material remaining in the vicinity of the ablated area has a critical influence on the electrical properties of the final devices. In this work, a comprehensive analysis of refractive index variations for the material surrounding the ablated area by means of Infrared-Visible Fourier transform spectrometry is proposed. Besides, in order to evaluate the material microstructure, Raman spectroscopy is employed as a complimentary technique. It was seen that the refractive index variation decreased as the distance from the center of the ablated groove was increased. Likewise, a clear transition from highly crystalline to amorphous material could be also observed as a function of the distance from the groove.

  20. The influence of refractive index change and initial bending of cantilevers on the optical lever readout method

    DEFF Research Database (Denmark)

    Dohn, Søren; Greve, Anders; Svendsen, Winnie Edith;

    2010-01-01

    It has been speculated that the initial bending of cantilevers has a major influence on the detector signal in a cantilever-based sensor using the optical lever readout method. We have investigated theoretically as well as experimentally the changes induced in the detector signal when the optical...... experimentally using an environmental chamber and varying the pressure. We sketch routes to circumvent the problem and formulas suitable for data treatment are given....

  1. Pump-induced refractive index modulation and dispersions in Er3+-doped fibers

    DEFF Research Database (Denmark)

    Thirstrup, Carsten; Shi, Yuan

    1996-01-01

    A novel measurement system provides determination of pump induced phase shifts in erbium doped fibers with an accuracy of ~π/20. Using this system, a systematical analysis of the pump induced modulation of the refractive index and dispersions for a signal at 1550 nm and a pump at 980 nm is reported....... The analysis contains measurements of pump induced refractive index changes as function of wavelength, pump power, and doping concentration. A model taking account of the contribution to the refractive index changes from optical transitions between 4 I15/2 states and 4I13/2 states in Er3+ yields good...

  2. Refractive index and temperature nanosensor with plasmonic waveguide system

    Science.gov (United States)

    Kong, Yan; Qiu, Peng; Wei, Qi; Quan, Wei; Wang, Shouyu; Qian, Weiying

    2016-07-01

    A surface plasmon polariton sensor consisting of two metal-insulator-metal waveguides and a transverse rectangular resonator is proposed. Both refractive index and temperature sensing characteristics are analyzed by investigating the transmission spectra which demonstrates that the transmission peak wavelength shifting satisfies linear relation with environmental refractive index and temperature, respectively. The proposed design provides high refractive index and temperature sensitivity as 3.38×106%/RIU and 82%/K estimated by integrated response of the sensor, and owns the potentials for high-throughput array sensing. It is believed that the nanoscale sensor can be applied in spot detection for high speed multi-parameter sensing and accurate measurements.

  3. Demystifying back scatter interferometry: a sensitive refractive index detector

    DEFF Research Database (Denmark)

    Jepsen, Søren Terpager; Jørgensen, Thomas Martini; Trydal, Torleif;

    2014-01-01

    BACKGROUND: Back Scatter Interferometry (BSI) is a sensitive method for detecting changes of the refractive index (RI) in small capillaries. The method was originally developed as an off-axial column detector for use in Liquid Chromatography or Capillary Electrophoresis systems, but it has been...... acting like a common-path interferometer. METHODS: A HeNe laser is directed at a glass capillary with inner diameter of 1.4 mm and reflected light from air/glass and liquid/glass interfaces interfere to form an RI dependent intensity fringe pattern at a CCD detector. The fringe shift relative...

  4. Detection of analyte refractive index and concentration using liquid-core photonic Bragg fibers

    Science.gov (United States)

    Li, Jingwen; Qu, Hang; Skorobogatiy, Maksim

    2016-03-01

    We demonstrate detection of liquid analyte refractive index by using a hollow-core photonic Bragg fiber. We apply this fiber sensor to monitor concentrations of commercial cooling oil. The sensor operates on a spectral modality. Variation in the analyte refractive index modifies the bandgap guidance of a fiber, leading to spectral shifts in the fiber transmission spectrum. The sensitivity of the sensor to changes in the analyte refractive index filling in the fiber core is found to be 1460nm/Refractive index unit (RIU). By using the spectral modality and effective medium theory, we determine the concentrations of commercial fluid from the measured refractive indices with an accuracy of ~0.42%. The presented fiber sensor can be used for on-line monitoring of concentration of many industrial fluids and dilutions with sub-1%v accuracy.

  5. Engineering a resonant nanocoating for an optical refractive index sensor

    Science.gov (United States)

    Bialiayeu, A.; Ianoul, A.; Albert, J.

    2014-03-01

    We proposing to boost the performance of refractive index sensors based on the tilted fiber Bragg grating (TFBG) structure by resonant coupling of small spherical nanoparticles to the TFBG resonances. The optimal choice of nanoparticle parameters is discussed.

  6. Dependence of Physical Parameters of Compound Semiconductors on Refractive Index

    Directory of Open Access Journals (Sweden)

    R.R. Reddy

    2003-07-01

    Full Text Available Interesting relationships have been found between refractive index, plasmon energy, electronic polarisability, bond length, microhardness, bulk modulus, force constants and lattice energy. An attempt has been made for the first time to correlate only one physical parameter with others. The calculated values are in good agreement with the experimental values as well as with the values reported in the literature. Refractive index data is the only one parameter required to estimate all the above parameters.

  7. Measurement of the refractive index of silica aerogel in vacuum

    International Nuclear Information System (INIS)

    The photo injector test facility at DESY Zeuthen (PITZ) uses Cherenkov radiation of electrons inside aerogel to measure the bunch length of an electron beam. To evaluate the results the refractive index of the aerogel has to be precisely known. The aerogel is used either at atmospheric pressure or in vacuum. The pressure dependence of the refractive index of two aerogel samples is investigated in the range between high vacuum (10-5 mbar) and atmospheric pressure

  8. Dark Matter Constraints from a Cosmic Index of Refraction

    OpenAIRE

    Gardner, S.; Latimer, D. C.

    2009-01-01

    The dark-matter candidates of particle physics invariably possess electromagnetic interactions, if only via quantum fluctuations. Taken en masse, dark matter can thus engender an index of refraction which deviates from its vacuum value. Its presence is signaled through frequency-dependent effects in the propagation and attenuation of light. We discuss theoretical constraints on the expansion of the index of refraction with frequency, the physical interpretation of the terms, and the particula...

  9. The temperature dependence of refractive index of hemoglobin at the wavelengths 930 and 1100 nm

    Science.gov (United States)

    Lazareva, Ekaterina N.; Tuchin, Valery V.

    2016-04-01

    In this study, the refractive index of hemoglobin was measured at different temperatures within a physiological range and above that is characteristic to light-blood interaction at laser therapy. Measurements were carried out using the multi-wavelength Abbe refractometer (Atago, Japan). The refractive index was measured at two NIR wavelengths of 930 nm and 1100 nm. Samples of hemoglobin solutions with concentration of 80, 120 and 160 g/l were investigated. The temperature was varied between 25 and 55 °C. It was shown that the dependence of the refractive index of hemoglobin is nonlinear with temperature, which may be associated with changes in molecular structure of hemoglobin.

  10. Refractive index modulation in polymer film doped with diazo Meldrum's acid

    Science.gov (United States)

    Zanutta, Alessio; Villa, Filippo; Bertarelli, Chiara; Bianco, Andrea

    2016-08-01

    Diazo Meldrum's acid undergoes a photoreaction induced by UV light and it is used as photosensitizer in photoresists. Upon photoreaction, a change in refractive index occurs, which makes this system interesting for volume holography. We report on the sublimation effect at room temperature and the effect of photoirradiation on the refractive index in thin films of CAB (Cellulose acetate butyrate) doped with different amount of diazo Meldrum's acid. A net modulation of the refractive index of 0.01 is achieved with 40% of doping ratio together with a reduction of the film thickness.

  11. Effects of graded refractive index on steady and transient heat transfer inside a scattering semitransparent slab

    International Nuclear Information System (INIS)

    Coupled radiative-conductive heat transfer inside an absorbing-emitting-scattering semitransparent slab is solved. The refractive index of the media is distributed spatially in a linear relationship. The two boundary surfaces are diffuse and opaque. In this paper, the media with graded refractive index is simulated by using multilayer composite model, and in each sub-layer the refractive index is supposed to be constant and the rays of thermal radiation travel in a straight line. The multilayer model is developed by ray-tracing method combined with node analysis. A comparison of the present results with previous results shows that the multilayer simulation of media with graded refractive index is rational and correct. Considering isotropic scattering of thermal radiation, with the changes in the extinction coefficient, surface emissivities and the scattering albedo, the influences of refractive index distribution on the temperature and the radiative heat flux fields are investigated. The results show that the gradient distributing of refractive indexes can cause very different thermal behavior concerned with radiative transfer in semitransparent media compared with constant refractive indexes

  12. Structures with negative index of refraction

    Science.gov (United States)

    Soukoulis, Costas M.; Zhou, Jiangfeng; Koschny, Thomas; Zhang, Lei; Tuttle, Gary

    2011-11-08

    The invention provides simplified negative index materials (NIMs) using wire-pair structures, 4-gap single ring split-ring resonator (SRR), fishnet structures and overleaf capacitor SRR. In the wire-pair arrangement, a pair of short parallel wires and continuous wires are used. In the 4-gap single-ring SRR, the SRRs are centered on the faces of a cubic unit cell combined with a continuous wire type resonator. Combining both elements creates a frequency band where the metamaterial is transparent with simultaneously negative .di-elect cons. and .mu.. In the fishnet structure, a metallic mesh on both sides of the dielectric spacer is used. The overleaf capacitor SRR changes the gap capacities to small plate capacitors by making the sections of the SRR ring overlap at the gaps separated by a thin dielectric film. This technique is applicable to conventional SRR gaps but it best deploys for the 4-gap single-ring structures.

  13. Intensity correlations in random media induced by refractive index tuning (RIT)

    CERN Document Server

    Faez, Sanli; Lagendijk, Ad

    2009-01-01

    We introduce a new approach for measuring both the transport and the effective medium properties of light propagation in inhomogeneous media. These properties include the diffusion constant, the path length distribution, and the effective index of refraction. Our method utilizes the equivalence of frequency variation with a change in the index of refraction. A new correlation function that describes correlations in both frequency and index of refraction is introduced. Experimentally, we measure this correlation via spectrally resolved refractive index tuning (RIT), controlling the latter via changes in the ambient pressure. Our new generic measurement technique can be used to characterize a wide variety of materials, including photonic crystals, random photonic media, photonic meta-materials, and certain porous biological samples like bone and wood.

  14. Pterygium-induced corneal refractive changes

    Directory of Open Access Journals (Sweden)

    Maheshwari Sejal

    2007-01-01

    Full Text Available To study the effect of pterygium on corneal topography, a retrospective analysis of 151 eyes with primary pterygia was done. All cases underwent videokeratography preoperatively and one month postoperatively. Statistical analysis of average corneal power (ACP, corneal astigmatism, surface regularity index (SRI and surface asymmetry index (SAI was done before and one month after surgery. Topographic indices were compared statistically for various grades of pterygia. Increase in the grade of pterygia had a significant effect on topographic indices. Corneal astigmatism reduced from 4.40±3.64 diopter (D to 1.55±1.63D ( P value < 0.001 following surgery. The regularity of corneal surface improved and asymmetry of the cornea reduced one month after surgery. Pterygium leads to significant changes in corneal refractive status, which increase with the increase in the grade of pterygia and improve following pterygium excision.

  15. Bent induced refractive index profile variation and mode field distribution of step-index multimode optical fiber

    Science.gov (United States)

    Sokkar, T. Z. N.; Ramadan, W. A.; Shams El-Din, M. A.; Wahba, H. H.; Aboleneen, S. S.

    2014-02-01

    The effect of bending of step-index optical fiber on its refractive index profile and the mode field distribution were investigated. An enhanced slab model is suggested in this investigation. A qualitative study has been done on a bent step-index optical fiber. A very small radius of bending curvature (R) has been reached, practically R is 9.25 mm. In this case a dramatic change of the refractive index profile has been observed with an induced birefringence. The refractive index profile is recovered from the interferograms which were generated by Mach-Zehnder interferometer. The interferogram has been analyzed using advanced image analyses software. We have proposed another approach to calculate the refractive index profile of bent optical fiber. In this approach the fiber is divided into layers and slabs, simultaneously. The induced refractive index profile variation of the bent optical fiber, for parallel and perpendicular components of the light beam, is calculated considering the refraction of the light beam traversing the fiber. The mode field distribution and mode numbers in these two directions of polarizations are determined for both straight and bent fibers.

  16. Size dependence of complex refractive index function of growing nanoparticles

    Science.gov (United States)

    Eremin, A.; Gurentsov, E.; Popova, E.; Priemchenko, K.

    2011-08-01

    The evidence of the change of the complex refractive index function E( m) of carbon and iron nanoparticles as a function of their size was found from two-color time-resolved laser-induced incandescence (TiRe-LII) measurements. Growing carbon particles were observed from acetylene pyrolysis behind a shock wave and iron particles were synthesized by pulse Kr-F excimer laser photo-dissociation of Fe(CO)5. The magnitudes of refractive index function were found through the fitting of two independently measured values of particle heat up temperature, determined by two-color pyrometry and from the known energy of the laser pulse and the E( m) variation. Small carbon particles of about 1-14 nm in diameter had a low value of E( m)˜0.05-0.07, which tends to increase up to a value of 0.2-0.25 during particle growth up to 20 nm. Similar behavior for iron particles resulted in E( m) rise from ˜0.1 for particles 1-3 nm in diameter up to ˜0.2 for particles >12 nm in diameter.

  17. Entanglement Generation by Time Varying Refractive Index: Analogy with Cosmological Model

    CERN Document Server

    Moradi, Shahpoor

    2012-01-01

    Generation of entanglement between modes of a electromagnetic fields by sudden change of the refractive index of a medium is considered. We use the analogy between the Fock-space formulation of pair creation caused by the contraction and expansion of the universe on one hand and the pair creation in time-dependent electric fields on the other hand. It is shown that entanglement between photons encodes information concerning the underlying refractive index of a medium.

  18. A Refractive Index Sensor Based on the Resonant Coupling to Cladding Modes in a Fiber Loop

    Science.gov (United States)

    Reyes, Mauricio; Monzón-Hernández, David; Martínez-Ríos, Alejandro; Silvestre, Enrique; Díez, Antonio; Cruz, José Luis; Andrés, Miguel V.

    2013-01-01

    We report an easy-to-build, compact, and low-cost optical fiber refractive index sensor. It consists of a single fiber loop whose transmission spectra exhibit a series of notches produced by the resonant coupling between the fundamental mode and the cladding modes in a uniformly bent fiber. The wavelength of the notches, distributed in a wavelength span from 1,400 to 1,700 nm, can be tuned by adjusting the diameter of the fiber loop and are sensitive to refractive index changes of the external medium. Sensitivities of 170 and 800 nm per refractive index unit for water solutions and for the refractive index interval 1.40–1.442, respectively, are demonstrated. We estimate a long range resolution of 3 × 10−4 and a short range resolution of 2 × 10−5 for water solutions. PMID:23979478

  19. Investigation of the nonlinear refractive index of single-crystalline thin gold films and plasmonic nanostructures

    Science.gov (United States)

    Goetz, Sebastian; Razinskas, Gary; Krauss, Enno; Dreher, Christian; Wurdack, Matthias; Geisler, Peter; Pawłowska, Monika; Hecht, Bert; Brixner, Tobias

    2016-04-01

    The nonlinear refractive index of plasmonic materials may be used to obtain nonlinear functionality, e.g., power-dependent switching. Here, we investigate the nonlinear refractive index of single-crystalline gold in thin layers and nanostructures on dielectric substrates. In a first step, we implement a z-scan setup to investigate ~100-µm-sized thin-film samples. We determine the nonlinear refractive index of fused silica, n 2(SiO2) = 2.9 × 10-20 m2/W, in agreement with literature values. Subsequent z-scan measurements of single-crystalline gold films reveal a damage threshold of 0.22 TW/cm2 and approximate upper limits of the real and imaginary parts of the nonlinear refractive index, | n 2'(Au)| crystalline gold film). An upper limit for the nonlinear power-dependent phase change between two propagating near-field modes is determined to Δ φ < 0.07 rad.

  20. Measurement of refracting index of wood for microwave radiation

    International Nuclear Information System (INIS)

    The refracting index of wood depends strongly on its moisture content. In this work we present the results of measurements of the index using electromagnetic radiation with a frequency of 9.35 GHz that corresponds to microwaves. The relationship between the wood moisture content (MC) and the index in some softwood and hardwood species could be the basis for a determination method of moisture content, covering a wide range of values

  1. Optical humidity-sensitive mechanism based on refractive index variation

    Institute of Scientific and Technical Information of China (English)

    Zhenyuan Wang; Zhengtian Gu

    2009-01-01

    A novel composite model is put forward for humidity-sensitive material based on Maxwell-Garnett and effective medium theory.The analytical expression of the relation between effective refractive index and relative humidity is shown with different absorption factors and porosities.The larger the absorption factor is,the higher the refractive index is.The refractive index of humidity-sensitive SiO2 film decreases with the increase of ceramic material porosity.The sensitivity of optical humidity sensor can reach the magnitude of 10-3.In comparison with the experimental humidity-sensing curve by the method of p-polarized reflectance and the analysis of mechanism,theoretical simulation is in agreement with experimental results.Therefore,this composite model is proved to be reasonable which lays new theoretical foundation in further research on optical humidity sensor.

  2. Empirical modelling to predict the refractive index of human blood

    Science.gov (United States)

    Yahya, M.; Saghir, M. Z.

    2016-02-01

    Optical techniques used for the measurement of the optical properties of blood are of great interest in clinical diagnostics. Blood analysis is a routine procedure used in medical diagnostics to confirm a patient’s condition. Measuring the optical properties of blood is difficult due to the non-homogenous nature of the blood itself. In addition, there is a lot of variation in the refractive indices reported in the literature. These are the reasons that motivated the researchers to develop a mathematical model that can be used to predict the refractive index of human blood as a function of concentration, temperature and wavelength. The experimental measurements were conducted on mimicking phantom hemoglobin samples using the Abbemat Refractometer. The results analysis revealed a linear relationship between the refractive index and concentration as well as temperature, and a non-linear relationship between refractive index and wavelength. These results are in agreement with those found in the literature. In addition, a new formula was developed based on empirical modelling which suggests that temperature and wavelength coefficients be added to the Barer formula. The verification of this correlation confirmed its ability to determine refractive index and/or blood hematocrit values with appropriate clinical accuracy.

  3. Rainbow refractometry on particles with radial refractive index gradients

    Energy Technology Data Exchange (ETDEWEB)

    Saengkaew, Sawitree [CNRS/Universite et INSA de Rouen, UMR 6614/CORIA, BP12, 76 800, Saint Etienne du Rouvray CEDEX (France); Chulalongkorn University, Center of Excellence in Particle Technology, Faculty of Engineering, Bangkok (Thailand); Charinpanitkul, Tawatchai; Vanisri, Hathaichanok; Tanthapanichakoon, Wiwut [Chulalongkorn University, Center of Excellence in Particle Technology, Faculty of Engineering, Bangkok (Thailand); Biscos, Yves; Garcia, Nicolas; Lavergne, Gerard [ONERA/DMAE, Toulouse (France); Mees, Loic; Gouesbet, Gerard; Grehan, Gerard [CNRS/Universite et INSA de Rouen, UMR 6614/CORIA, BP12, 76 800, Saint Etienne du Rouvray CEDEX (France)

    2007-10-15

    The rainbow refractrometry, under its different configurations (classical and global), is an attractive technique to extract information from droplets in evaporation such as diameter and temperature. Recently a new processing strategy has been developed which increases dramatically the size and refractive index measurements accuracy for homogeneous droplets. Nevertheless, for mono component as well as for multicomponent droplets, the presence of temperature and/or of concentration gradients induce the presence of a gradient of refractive index which affects the interpretation of the recorded signals. In this publication, the effect of radial gradient on rainbow measurements with a high accuracy never reached previously is quantified. (orig.)

  4. Studying of refractive index measurements in reflected light

    CERN Document Server

    Tikhonov, E A

    2010-01-01

    Two methods of refractometry in reflected light from optical surface of samples are considered and studied experimentally. Methods are grounded on results of Fresnel theory of concerning light reflectivity at near normal incidence and Brewster angle. Sources of errors for both methods were considered and possibility of measuring of the refractive index with application of laser radiation with accuracy to within 4th sign was shown. Advantages of described methods concerning requirements to preparation of samples to refractive index measurement of solid, thin-film and absorbing materials are scored.

  5. Effects of refractive index mismatch in optical CT imaging of polymer gel dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Manjappa, Rakesh; Makki S, Sharath; Kanhirodan, Rajan, E-mail: rajan@physics.iisc.ernet.in [Department of Physics, Indian Institute of Science, Bangalore 560012 (India); Kumar, Rajesh [Radiological Physics and Advisory Division, BARC, Mumbai 400094 (India)

    2015-02-15

    Purpose: Proposing an image reconstruction technique, algebraic reconstruction technique-refraction correction (ART-rc). The proposed method takes care of refractive index mismatches present in gel dosimeter scanner at the boundary, and also corrects for the interior ray refraction. Polymer gel dosimeters with high dose regions have higher refractive index and optical density compared to the background medium, these changes in refractive index at high dose results in interior ray bending. Methods: The inclusion of the effects of refraction is an important step in reconstruction of optical density in gel dosimeters. The proposed ray tracing algorithm models the interior multiple refraction at the inhomogeneities. Jacob’s ray tracing algorithm has been modified to calculate the pathlengths of the ray that traverses through the higher dose regions. The algorithm computes the length of the ray in each pixel along its path and is used as the weight matrix. Algebraic reconstruction technique and pixel based reconstruction algorithms are used for solving the reconstruction problem. The proposed method is tested with numerical phantoms for various noise levels. The experimental dosimetric results are also presented. Results: The results show that the proposed scheme ART-rc is able to reconstruct optical density inside the dosimeter better than the results obtained using filtered backprojection and conventional algebraic reconstruction approaches. The quantitative improvement using ART-rc is evaluated using gamma-index. The refraction errors due to regions of different refractive indices are discussed. The effects of modeling of interior refraction in the dose region are presented. Conclusions: The errors propagated due to multiple refraction effects have been modeled and the improvements in reconstruction using proposed model is presented. The refractive index of the dosimeter has a mismatch with the surrounding medium (for dry air or water scanning). The algorithm

  6. Monitoring of temperature-mediated adipose tissue phase transitions by refractive-index measurements

    Science.gov (United States)

    Yanina, I. Yu.; Popov, A. P.; Bykov, A. V.; Tuchin, V. V.

    2014-10-01

    Monitoring of temperature-mediated adipose tissue phase transitions were studied in vitro using an Abbe refractometer. The 1-2-mm thick porcine fat tissues slices were used in the experiments. The observed change in the tissue was associated with several phase transitions of lipid components of the adipose tissue. It was found that overall heating of a sample from the room to higher temperature led to more pronounced and tissue changes in refractive index if other experimental conditions were kept constant. We observed an abrupt change in the refractive index in the temperature range of 37-60 °C.

  7. Refractive index modification of polymers using nanosized dopants

    Science.gov (United States)

    Hanemann, Thomas; Boehm, Johannes; Müller, Claas; Ritzhaupt-Kleissl, Eberhard

    2008-04-01

    The addition of nanosized inorganic or organic dopants to polymers allows the modification of the polymers physical properties enabling the realization of functionalized polymers with new application fields e.g. in microoptics. Exemplarily electron rich organic dopants, solved in polymers, cause a pronounced increase of the refractive index. Polymer based reactive resins like PMMA, solved in MMA, or unsaturated polyester, solved in styrene, can be cured to thermoplastic polymers. The resin's low viscous flow behaviour enables an easy composite formation by solving the organic dopants in the liquid up to a dopant content of 50 wt%, followed by solidification to a thermoplastic. The addition of simple organic molecules like phenanthrene or benzochinoline allows a refractive index elevation at 633 nm from 1.56 up to 1.60 retaining the good transmission properties. In comparison the refractive index of PMMA can be increased from the initial value of 1.49 up to values around 1.58 (@633 nm). All composites show an almost linear correlation between dopant content and refractive index. Using these composites devices like 3dB-couplers or an electrooptical modulator applying injection molded or hot embossed substrates have been realized.

  8. Refractive-Index Sensing with Ultrathin Plasmonic Nanotubes

    DEFF Research Database (Denmark)

    Raza, Søren; Toscano, Giuseppe; Jauho, Antti-Pekka;

    2013-01-01

    analytical expression for the extinction cross section and show how sensing of the refractive index of the surrounding medium and the figure of merit are affected by the shape and size of the nanotubes. Comparison with other localized surface plasmon resonance sensors reveals that the nanotube exhibits...

  9. Nano-imprint gold grating as refractive index sensor

    Science.gov (United States)

    Kumari, Sudha; Mohapatra, Saswat; Moirangthem, Rakesh S.

    2016-05-01

    Large scale of fabrication of plasmonic nanostructures has been a challenging task due to time consuming process and requirement of expensive nanofabrication tools such as electron beam lithography system, focused ion beam system, and extreme UV photolithography system. Here, we present a cost-effective fabrication technique so called soft nanoimprinting to fabricate nanostructures on the larger sample area. In our fabrication process, a commercially available optical DVD disc was used as a template which was imprinted on a polymer glass substrate to prepare 1D polymer nano-grating. A homemade nanoimprinting setup was used in this fabrication process. Further, a label-free refractive index sensor was developed by utilizing the properties of surface plasmon resonance (SPR) of a gold coated 1D polymer nano-grating. Refractive index sensing was tested by exposing different solutions of glycerol-water mixture on the surface of gold nano-grating. The calculated bulk refractive index sensitivity was found to be 751nm/RIU. We believed that our proposed SPR sensor could be a promising candidate for developing low-cost refractive index sensor with high sensitivity on a large scale.

  10. Silicon photonic crystal nanostructures for refractive index sensing

    DEFF Research Database (Denmark)

    Dorfner, Dominic; Hürlimann, T.; Zabel, T.;

    2008-01-01

    mode frequency between input and output waveguides. Optical characterization of the structures in air and various liquids demonstrate detectivities in excess of n=n = 0:018 and n=n = 0:006 for the H1-r and L3 cavities, respectively. The measured cavity-frequencies and detector refractive index...

  11. Effect of Effective Refractive Index of Grating in FBG Splitter

    Directory of Open Access Journals (Sweden)

    DINESH ARORA

    2011-09-01

    Full Text Available The Fiber Bragg Gratings have been used extensively in the communication industry. Fiber Bragg grating is written directly into the core of the optical fiber and it is quite an attractive technique for wavelength splitter since it provides high reflectivity at a certain wavelength, with negligible transmission losses for others, providing a wavelength-channel selection with low crosstalk between adjacent channels.In this paper we propose a Fiber Bragg Grating base splitter with alteration of effective refractive index of grating for Ethernet passive optical network. With the increase in the effective refractive index the reflectivity of grating is increased. We analysed the effect of effective refractive index on reflectivity of grating. In our work the Bragg wavelength has been fixed at 1550 nm,length of the grating as 10mm and with effective refractive index as 4.0 it has been found that the reflectivity of the grating or the effectiveness of the grating in extracting the wavelength is 92-93%.

  12. Refractive index and its impact on pseudophakic dysphotopsia

    Directory of Open Access Journals (Sweden)

    Radmall BR

    2015-07-01

    Full Text Available Bryce R Radmall,1 Anne Floyd,2 Zack Oakey,3 Randall J Olson4 1Department of Ophthalmology, Casey Eye Institute, Oregon Health and Science University, Portland, OR, 2Department of Ophthalmology, Louisiana State University Health Sciences Center, Shreveport, LA, 3Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, CA, 4Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA Purpose: It has been shown that the biggest dissatisfier for uncomplicated cataract surgery patients is pseudophakic dysphotopsia (PD. While edge design of an intraocular lens (IOL impacts this problem, refractive index is still controversial as to its impact. This retrospective cohort study was designed to determine the role of increasing refractive index in PD. Patients and methods: This study was conducted at the John A. Moran Eye Center, University of Utah, USA. A retrospective chart review identified patients who received one of two hydrophobic acrylic single piece IOLs (AcrySof WF SP [SN60WF] or Tecnis SP [ZCB00], which differed mainly by refractive index (1.55 versus 1.47. Eighty-seven patients who had received implantation of a one-piece hydrophobic acrylic IOL were enrolled. Patients were included if the surgery had been uncomplicated and took place at least a year before study participation. All eligible patients had 20/20 best corrected vision, without any disease known to impact visual quality. In addition to conducting a record review, the enrolled patients were surveyed for PD, using a modified National Eye Institute Visual Function questionnaire, as well as for overall satisfaction with visual quality. Results: Statistical analysis demonstrated no difference between the two cohorts regarding PD, general visual function, and overall visual satisfaction. Conclusion: The study suggests that with the two IOLs assessed, increasing the refractive index does not

  13. Refractive index of nanostructured optical materials

    Science.gov (United States)

    Flory, Francois; Escoubas, Ludovic; Drouard, Emmanuel; Lazarides, Basile

    2002-06-01

    Thanks to progresses in photolithography techniques optical materials can now be structured to a scale of a few tens of a nanometer. This has opened a wide field of new applications. When concerned with a scale of some tens of a micron down to a few microns, microlens and integrated optic components can be made. When the material is structured with a scale in the order of the wavelength of light, different filtering functions can be made. This concerns Bragg mirrors or more generally Photonic Crystals. A structuration in a scale small in front of the wavelength is also of a great interest. In this case the material does not diffract the light anymore an dit behaves like a homogeneous one. The calculated transmittance of a laser mirror is used to determine the effective index of the single layer equivalent to the multilayer stack. The artificial anisotropy of thin films structured with a one-dimension sub wavelength grating made by holography is measured. The limitation of the first order homogenization theory is given for two different grating steps. Polarizing coatings or polarization rotators are designed to work in normal incidence by inserting anisotropic films in simple multilayer structures.

  14. Experimental determination of the refractive index of metamaterials

    International Nuclear Information System (INIS)

    We present a simple experimental technique based on diffraction for determining the complex refractive index of metamaterials, and demonstrate it with metamaterials that consist of detuned electrical dipoles (DEDs), mimicking the dressed-state picture of electromagnetically induced transparency (EIT). The metamaterials are realized by fabricating lithographically defined gold nanorods on a silica substrate, covered with a ∼ 15 µm thick polymer layer, and feature EIT-like transmission spectra with transparency windows centered at wavelengths near ∼ 800 nm. The refractive indices are determined for wavelengths where the DED metamaterials exhibit enhanced transmission. Thereby, we experimentally demonstrate normal dispersion in the transmission window and estimate the group refractive index to ∼ 3.6. Furthermore, finite-element simulations are conducted on a monolayer of DED unit cells, which similarly exhibit the EIT-like behavior in terms of enhanced transmission revealed in the transmission spectra. Simulated transmission and reflection spectra are utilized for calculations of the real and imaginary parts of the metamaterial refractive index, showing consistent trends with those obtained experimentally

  15. Modification of the refractive index of dielectrica by means of ionizing radiation

    International Nuclear Information System (INIS)

    Refractive-index changes are studied, which result by interaction of ionizing radiation with dielectric, optically transparent solids. As examples two materials are studied. At the one hand it deals with polymethylmethacrylate (PMMA), a polymer, which is irradiated with synchrotron radiation, and at the other hand with lithium niobate (LiNbO3), an oxidic crystal, which is irradiated by fast helium ions. In both materials refractive-index changes in the range 10-4 to 10-3 can be produced, which is very interesting for many applications in photonics

  16. Electrically tunable refractive index in the dark conglomerate phase of a bent-core liquid crystal

    Science.gov (United States)

    Nagaraj, M.; Görtz, V.; Goodby, J. W.; Gleeson, H. F.

    2014-01-01

    Here we report an electrically tunable refractive index observed in an isotropic liquid crystal phase known as the dark conglomerate (DC) phase. This unusual change in the refractive index which has not been reported before in the DC phase of other bent-core liquid crystals occurs because of a series of electric-field-driven transformations that take place in the DC phase of the studied bent-core liquid crystal. These transformations give rise to a decrease in the refractive index of the system, when an electric field is applied across the device, and no change in the birefringence is seen during such behavior. The electro-optic phenomenon is described in detail and the possibility of exploiting this for a number of liquid crystal based device applications is discussed.

  17. Numerical Study of Negative-Refractive Index Ferrite Waveguide

    Directory of Open Access Journals (Sweden)

    Mohammed O. Sid-Ahmed

    2012-03-01

    Full Text Available Consider a magnetized ferrite-wire waveguide structure situated between two half free spaces. Ferrites to provide negative permeability and wire array to provide negative permittivity. The structure form left-handed material (LHM with negative refractive index. The transmission of electromagnetic waves through the structure is investigated theoretically. Maxwell's equations are used to determine the electric and magnetic fields of the incident waves at each layer. Snell's law is applied and the boundary conditions are imposed at each layer interface to calculate the reflected and transmitted powers of the structure. Numerical results are illustrated to show the effect of frequency, applied magnetic fields, angle of incidence and LHM thickness on the mentioned powers. The analyzed results show that the transmission is very good when the permeability and permittivity of the structure are both simultaneously negative. The frequency band corresponding to this transmission can be tuned by changing the applied magnetic fields. The obtained results are in agreement with the law of conservation of energy. Consider a magnetized ferrite-wire waveguide structure situated between two half free spaces. Ferrites to provide negative permeability and wire array to provide negative permittivity. The structure form left-handed material (LHM with negative refractive index. The transmission of electromagnetic waves through the structure is investigated theoretically. Maxwell's equations are used to determine the electric and magnetic fields of the incident waves at each layer. Snell's law is applied and the boundary conditions are imposed at each layer interface to calculate the reflected and transmitted powers of the structure. Numerical results are illustrated to show the effect of frequency, applied magnetic fields, angle of incidence and LHM thickness on the mentioned powers. The analyzed results show that the transmission is very good when the permeability and

  18. Nonlinear Refractive Index Measurement in Semiconductor-Doped Glasses

    Directory of Open Access Journals (Sweden)

    M. t. Tavassoli

    1997-04-01

    Full Text Available   There are several techniques in use for non-linear refractive index measurement, namely, interferometric techniques, in which conventional inter-ferometers are used, degenerate for wave mixing (DFWM, and z-scan, Each of these techniques suffers from some shortcmings. For example conventional interferometers like Fabry-Perot and Twyman-Green need high quality optical components, unwanted reflections on these components produce noise, and the device limits the probe-pump anglc, or in z-scan technique one needs very sensitive detectors and since the intensity is monitored by the nonlinear absorption, which is usually present, reduces the measurement accuracy.   In the techniqucs introduced here, in principle, only a plate of the sample is required, and even parallelism of the plate surfaces is not curcial. Experiments can be carried out successfully if the angle between the plate surface is less than few minutes. In the first technique, the probe beam strikes the surface at an arbitray angle of incidence. The reflected beam from the two surfaces of the sample interfere on a photo-sensitive screen like CCD, and more or less linear interference fringes are produced. When the pump beam is switched on, the interference pattern deforms. The amount and the direction of the deformation give the value and the sign of the non-linear refractive index. In this technique the probe-pump angle can be varied from 00 to 1900.  In the second technique, interference between the reflected probe beam from the sample and the diffracted pump beam from the grating induced by the interference of the probe and the pump beams, leads to a series of circular fringes. When the non-linear sample is replaced by a linear material like fuse silica glass, the above mentioned circular fringes are formed, but the number of fringes in a specified angular interval remains fixed as the pump beam intensity increases. But, in the case of a non-linear sample the number changes due to

  19. Femtosecond refractive-index tailoring of an optical fiber and phase retrieval from far-field measurements

    DEFF Research Database (Denmark)

    Savolainen, Juha-Matti; Grüner-Nielsen, Lars; Kristensen, Poul; Balling, Peter

    2013-01-01

    A refractive-index change is written inside an optical fiber close to the end face by femtosecond laser light. The induced phase change is measured by analyzing the far-field intensity profiles before and after the irradiation.......A refractive-index change is written inside an optical fiber close to the end face by femtosecond laser light. The induced phase change is measured by analyzing the far-field intensity profiles before and after the irradiation....

  20. Determination of refractive index of various materials on Brewster angle

    CERN Document Server

    Tikhonov, Eugene A

    2015-01-01

    Studied experimentally the origin of the non-zero reflection of p-polarized radiation (TM) of Brewster's angle. The results have shown the residual reflected light in the vicinity of Brewster angle occurs due to inaccessibility 100% polarization degree the incident linearly-polarized radiation and installation of the zero azimuthal angle. These factors create the s-component of the radiation reflected from the examined surface indeed. A smooth change of reflected light polarization in the vicinity of Brewster angle in the sequence p-s-p appears due to the changing power proportion of reflected p-, and s-components but not is the result of the atomically thin transitional layer at the border of the material/environment according to Drude model. Metrological aspects of refractive index measurement by Brewster angle are investigated: due to the above-mentioned factors, as well as due to the contribution of the reflected scattered light caused by on residual roughness of the optical surface. Advantages of Brewste...

  1. The use of a conical lens to find the refractive index of liquids

    International Nuclear Information System (INIS)

    In this work, the basic idea is to determine the refractive index of liquids unknown using a conical lens. The measurement of the refractive index of liquids is an important work in engineering and science since is one of the most important optical parameter. The adulteration problem is increasing day by day; therefore it is necessary to implement new and simple devices for measure the refractive index of several materials. There is a great variety of interferometric methods that may be used for determining the refractive index. However, these methods either need sophisticated equipment or have low accuracy. Our system consists of a conical lens coupled to a cylindrical container with a liquid whose composition can be changed easily or adulterated. The diameter of the emergent beam of the container is associated to the specific index of refraction of each substance. Any adulteration of the liquid will be reflected in the diameter of the beam, which will be detected by a charge-coupled device (CCD). Our hypothesis is supported by developed mathematical calculations and numerical simulations.

  2. The use of a conical lens to find the refractive index of liquids

    Energy Technology Data Exchange (ETDEWEB)

    Anguiano-Morales, Marcelino; Salas Peimbert, Didia P; Trujillo-Schiaffino, Gerardo, E-mail: manguiano@itchihuahua.edu.mx [Instituto Tecnologico de Chihuahua, Division de Estudios de Posgrado e Investigacion, Av. Tecnologico No 2909, Chihuahua, Chih., 31310 (Mexico)

    2011-01-01

    In this work, the basic idea is to determine the refractive index of liquids unknown using a conical lens. The measurement of the refractive index of liquids is an important work in engineering and science since is one of the most important optical parameter. The adulteration problem is increasing day by day; therefore it is necessary to implement new and simple devices for measure the refractive index of several materials. There is a great variety of interferometric methods that may be used for determining the refractive index. However, these methods either need sophisticated equipment or have low accuracy. Our system consists of a conical lens coupled to a cylindrical container with a liquid whose composition can be changed easily or adulterated. The diameter of the emergent beam of the container is associated to the specific index of refraction of each substance. Any adulteration of the liquid will be reflected in the diameter of the beam, which will be detected by a charge-coupled device (CCD). Our hypothesis is supported by developed mathematical calculations and numerical simulations.

  3. Engineering of refractive index in sulfide chalcogenide glass by direct laser writing

    KAUST Repository

    Zhang, Yaping

    2010-01-01

    Arsenic trisulfide (As2S3) glass is an interesting material for photonic integrated circuits (PICs) as infrared (IR) or nonlinear optical components. In this paper, direct laser writing was applied to engineer the refractive index of As2S3 thin film. Film samples were exposed to focused above bandgap light with wavelength at 405 nm using different fluence adjusted by laser power and exposure time. The index of refraction before and after laser irradiation was calculated by fitting the experimental data obtained from Spectroscopic Ellipsometer (SE) measurement to Tauc-Lorenz dispersion formula. A positive change in refractive index (Δn = 0.19 at 1.55 μm) as well as an enhancement in anisotropy was achieved in As2S3 film by using 10 mW, 0.3 μs laser irradiation. With further increasing the fluence, refractive index increased while anisotropic property weakened. Due to the rapid and large photo-induced modification of refractive index obtainable with high spatial resolution, this process is promising for integrated optic device fabrication.

  4. Infrared non-planar plasmonic perfect absorber for enhanced sensitive refractive index sensing

    Science.gov (United States)

    Cheng, Yongzhi; Mao, Xue Song; Wu, Chenjun; Wu, Lin; Gong, RongZhou

    2016-03-01

    We present a non-planar all-metal plasmonic perfect absorber (PA) with response polarization independent in infrared region, which can be served as a sensor for enhanced refractive index sensing. Distinct from previous designs, the proposed PA consisted of all metal structured film constructed with an assembly of four-tined rod resonators (FRRs). The PA with a high quality-factor (Q-factor) of 41.2 and an absorbance of 99.9% at 142.6 THz has been demonstrated numerically. The resonance behavior occurs in the space between the rods of the FRRs, which is remarkable different conventional sandwiched structural PAs. Based on equivalent LC circuit theory, the absorption peak can be finely tuned by varying the geometrical dimensions of the FRRs. Furthermore, the resonance frequency shows highly sensitive response to the change of refractive index in the surrounding medium. A careful design for refractive index sensor can yield a sensitivity of 1445 nm/refractive index unit (RIU) and a figure of merit (FOM) of 28.8. The demonstrated design of the plasmonic PA for sensing provides great potential application in enhancing refractive index sensors and the enhanced infrared spectroscopy.

  5. Dark Matter Constraints from a Cosmic Index of Refraction

    CERN Document Server

    Gardner, S

    2009-01-01

    The dark-matter candidates of particle physics invariably possess electromagnetic interactions, if only via quantum fluctuations. Taken en masse, dark matter can thus engender an index of refraction which deviates from its vacuum value. Its presence is signaled through frequency-dependent effects: the real part yields dispersive effects in propagation, and the imaginary part yields such in attenuation. We discuss theoretical constraints on the expansion of the index of refraction with frequency, the physical interpretation of the terms, and the particular observations needed to isolate its coefficients. This, with the advent of new opportunities to view gamma-ray bursts at cosmological distance scales, gives us a new probe of dark matter. As a first application we use the time delay determined from radio afterglow observations of gamma-ray bursts to limit the charge-to-mass ratio of dark matter to |\\epsilon/M|< 1.8 x 10^{-5}/eV at 95% CL.

  6. A Simple Model for Measuring Refractive Index of a Liquid Based upon Fresnel Equations

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhi-Wei; WU Zhi-Fang; WEN Ting-Dun

    2007-01-01

    Due to many experimental data required and a lot of calculations involved, it is very complex and cumbersome to model prism-based liquid-refractive-index-measuring methods. We develop a new method of mathematical modelling for measuring refractive index of a liquid based upon the Fresnel formula and prism internal reflection at an incident angle less than the critical angle. With this method, only two different concentrations measurements for a kind of solution can lead to the determination of computational model. Measurements are performed to examine the validity of the theoretical model. Experimental results indicate the feasibility of the theoretical model with an error of 1%. The method is also capable of measuring even smaller changes in the optical refractive index of the material on a metal surface by the surface plasma resonance sensing techniques.

  7. Estimating index of refraction for material identification in comparison to existing temperature emissivity separation algorithms

    Science.gov (United States)

    Martin, Jacob A.; Gross, Kevin C.

    2016-05-01

    As off-nadir viewing platforms become increasingly prevalent in remote sensing, material identification techniques must be robust to changing viewing geometries. Current identification strategies generally rely on estimating reflectivity or emissivity, both of which vary with viewing angle. Presented here is a technique, leveraging polarimetric and hyperspectral imaging (P-HSI), to estimate index of refraction which is invariant to viewing geometry. Results from a quartz window show that index of refraction can be retrieved to within 0.08 rms error from 875-1250 cm-1 for an amorphous material. Results from a silicon carbide (SiC) wafer, which has much sharper features than quartz glass, show the index of refraction can be retrieved to within 0.07 rms error. The results from each of these datasets show an improvement when compared with a maximum smoothness TES algorithm.

  8. Numerical Study of Negative-Refractive Index Ferrite Waveguide

    OpenAIRE

    Mohammed O. Sid-Ahmed; Shabat, Mohammed M; Muin F. Ubeid

    2012-01-01

    Consider a magnetized ferrite-wire waveguide structure situated between two half free spaces. Ferrites to provide negative permeability and wire array to provide negative permittivity. The structure form left-handed material (LHM) with negative refractive index. The transmission of electromagnetic waves through the structure is investigated theoretically. Maxwell's equations are used to determine the electric and magnetic fields of the incident waves at each layer. Snell's law is applied and ...

  9. Measurement of the Kerr nonlinear refractive index of Cs vapor

    CERN Document Server

    Araújo, Michelle O; Oriá, Marcos; Chevrollier, Martine; de Silans, Thierry Passerat; Castro, Romeu; Moretti, Danieverton

    2014-01-01

    Atomic vapors are systems well suited for nonlinear optics studies but very few direct measurements of their nonlinear refractive index have been reported. Here we use the z-scan technique to measure the Kerr coefficient, $n_2$, for a Cs vapor. Our results are analyzed through a four-level model, and we show that coherence between excited levels as well as cross-population effects contribute to the Kerr-nonlinearity.

  10. Matching the refractive index [in] density stratified flows

    OpenAIRE

    Hannoun, Imad

    1985-01-01

    The use of optical methods such as Laser Doppler Velocimetry (LDV) and laser induced fluorescence techniques (LIF) in experimental fluid mechanics is becoming very common. The greatest advantage of such methods is that measurements are made without disturbing the flow. A major impediment to using optical methods to study density stratified flows is the variation of the refractive index within the flow field. McDougall (1979a) has proposed a method for the reduction of refrac...

  11. Optical properties of higher and lower refractive index composites

    International Nuclear Information System (INIS)

    The focus of attention in this study was the choice of material for optically solar selective coatings on the basis of their optical constants. A computer program which calculate the optical constants, solar absorptance alpha and thermal emittence epsilon of the selective on the assumption of both the Maxwell Garnett and Bruggeman theories for the metallic volume fraction below and above 0-3 respectively, was used to design the structure of the composite films. Two systems of composite thin films of metal and dielectric were investigated experimentally, fabricated by (define it) RF and (define it) DC sputter coater. One system consist lower refractive index (Ni:SiO/sub 2/) and other has higher refractive index (V:Al/sub 2/O/sub 3) composites in the range of 0.3 mu m spectrum. These films were fabricated on infrared reflective substrates such as nickel plated copper. For comparison and verification, tungsten, cobalt and chromium based composites were also investigated which validated the concept of the choice of material in selective coatings. It was observed that high refractive index composites have lower reflective properties by choosing suitable metallic volume fraction (0.7) in dielectric and AR coating (70 nm). Higher value of imaginary part of refractive index, k, is responsible for higher absorption by a factor alpha = 2 pi k/lambda. Solar absorptance of 0.98 and 0.96 was achieved by simulation and experimental findings with less than 0.05 thermal emittance for 200 nm thick composites. It was also investigated that higher values of both n and k are more suitable in selective coatings. (author)

  12. Refractive index of some oxide and fluoride coating materials

    International Nuclear Information System (INIS)

    Spectroreflectometry was used to measure the refractive index of the following optical coating materials: Ta2O5, HfO2, Y2O3, La2O3, ZrO2, CeO2, CeF3, LaF3, LaF3, NdF3, MgF2 in the 250--2000-nm spectral range

  13. Enhanced refractive index without absorption in semiconductor quantum dots

    Science.gov (United States)

    Chen, Nan; Shui, Tao; Qian, Biqi; Wang, Zhiping; Yu, Benli

    2015-07-01

    We investigate the absorptive-dispersive properties of a weak probe field in a ladder-type quantum dot. It is found that the enhanced refraction index without absorption can be easily controlled via adjusting properly the corresponding parameters of the system. Our scheme may provide some new possibilities for technological applications in dispersion compensation and solid-state quantum communication for quantum information processing.

  14. Studying of refractive index measurements in reflected light

    OpenAIRE

    Tikhonov, E. A.; Ivashkin, V. A.

    2010-01-01

    Two methods of refractometry in reflected light from optical surface of samples are considered and studied experimentally. Methods are grounded on results of Fresnel theory of concerning light reflectivity at near normal incidence and Brewster angle. Sources of errors for both methods were considered and possibility of measuring of the refractive index with application of laser radiation with accuracy to within 4th sign was shown. Advantages of described methods concerning requirements to pre...

  15. Negative Refractive Index in a Four-Level Atomic System

    Institute of Scientific and Technical Information of China (English)

    ZhANG Hong-Jun; GONG Shang-Qing; NIU Yue-Ping; LI Ru Xin; XU Zhi-Zhan

    2006-01-01

    @@ We propose a scheme for realizing negative refractive index in a four-level atomic system. It is shown that such a system can simultaneously exhibit negative permittivity and negative permeability in an optical frequency range.Furthermore, by analysing the dispersion property of the left-handed material, we find that the probe beam can be controlled from superluminal to subluminal or vice versa via choosing appropriate parameters.

  16. Directly patternable high refractive index ferroelectric sol–gel resist

    Energy Technology Data Exchange (ETDEWEB)

    Garoli, D., E-mail: denis.garoli@iit.it [Istituto Italiano di Tecnologia, Via Morego 16, 16136 Genova (Italy); Della Giustina, G. [Industrial Engineering Department, University of Padova and INSTM, Via Marzolo 9, 35131 Padova (Italy)

    2015-08-15

    The development of a ferroelectric negative tone sol–gel resist for Ultraviolet (UV) and Electron Beam (EB) lithography is presented. A new system based on Lead Zirconate Titanate (PZT, with formula PbZr{sub 0.52}Ti{sub 0.48}O{sub 3}) was synthesized by sol–gel method. The lithographic performances were investigated and several structures spanning from the micron range down to less than 50 nm have been achieved by UV and EB lithography. The system interaction with UV light and Electron beam was thoroughly characterized by FT-IT spectroscopy. The exposed PZT was annealed at high temperatures in order to study the crystalline phase evolution, the optical constants values and stability of patterned structures. After exposure and annealing, the refractive index of the material can vary from 1.68 up to 2.33 (@400 nm), while the ferroelectric behaviour seems to be maintained after high temperature annealing. These results suggest a possible application of PZT resist not only as ferroelectric but also as nanopatternable high refractive index material. Moreover, direct nanopatterning by means of Focused Ion Beam (FIB) lithography was verified and the potentiality for the preparation of high aspect ratio hollow nanostructures will be presented. - Highlights: • A new formula directly patternable PZT high refractive index resist is presented. • The gel is sensitive to both UV and electron beam exposure. • The refractive index can vary from 1.68 up to 2.33 (@400 nm). • Direct nanopatterning by means of Focused Ion Beam (FIB) lithography was verified. • High aspect ratio hollow nanostructures will be presented.

  17. Fiber Optic-Based Refractive Index Sensing at INESC Porto

    Directory of Open Access Journals (Sweden)

    Orlando Frazão

    2012-06-01

    Full Text Available A review of refractive index measurement based on different types of optical fiber sensor configurations and techniques is presented. It addresses the main developments in the area, with particular focus on results obtained at INESC Porto, Portugal. The optical fiber sensing structures studied include those based on Bragg and long period gratings, on micro-interferometers, on plasmonic effects in fibers and on multimode interference in a large spectrum of standard and microstructured optical fibers.

  18. A RICH with aerogel: a study of refractive index uniformity

    CERN Document Server

    Alemi, M; Calvi, M; Matteuzzi, C; Musy, M; Perego, D L; Easo, S

    2004-01-01

    The use of aerogel as a radiator in the RICH detectors of LHCb is a challenge due to the hot environment of the hadron collider LHC. Large size tiles of silica aerogel were recently produced with unprecedented optical quality for such dimensions. Results of laboratory measurements and beam tests are briefly reported. A description of a method to measure the uniformity of the index of refraction within the tile is given.

  19. Directly patternable high refractive index ferroelectric sol–gel resist

    International Nuclear Information System (INIS)

    The development of a ferroelectric negative tone sol–gel resist for Ultraviolet (UV) and Electron Beam (EB) lithography is presented. A new system based on Lead Zirconate Titanate (PZT, with formula PbZr0.52Ti0.48O3) was synthesized by sol–gel method. The lithographic performances were investigated and several structures spanning from the micron range down to less than 50 nm have been achieved by UV and EB lithography. The system interaction with UV light and Electron beam was thoroughly characterized by FT-IT spectroscopy. The exposed PZT was annealed at high temperatures in order to study the crystalline phase evolution, the optical constants values and stability of patterned structures. After exposure and annealing, the refractive index of the material can vary from 1.68 up to 2.33 (@400 nm), while the ferroelectric behaviour seems to be maintained after high temperature annealing. These results suggest a possible application of PZT resist not only as ferroelectric but also as nanopatternable high refractive index material. Moreover, direct nanopatterning by means of Focused Ion Beam (FIB) lithography was verified and the potentiality for the preparation of high aspect ratio hollow nanostructures will be presented. - Highlights: • A new formula directly patternable PZT high refractive index resist is presented. • The gel is sensitive to both UV and electron beam exposure. • The refractive index can vary from 1.68 up to 2.33 (@400 nm). • Direct nanopatterning by means of Focused Ion Beam (FIB) lithography was verified. • High aspect ratio hollow nanostructures will be presented

  20. 3D refractive index measurements of special optical fibers

    Science.gov (United States)

    Yan, Cheng; Huang, Su-Juan; Miao, Zhuang; Chang, Zheng; Zeng, Jun-Zhang; Wang, Ting-Yun

    2016-09-01

    A digital holographic microscopic chromatography-based approach with considerably improved accuracy, simplified configuration and performance stability is proposed to measure three dimensional refractive index of special optical fibers. Based on the approach, a measurement system is established incorporating a modified Mach-Zehnder interferometer and lab-developed supporting software for data processing. In the system, a phase projection distribution of an optical fiber is utilized to obtain an optimal digital hologram recorded by a CCD, and then an angular spectrum theory-based algorithm is adopted to extract the phase distribution information of an object wave. The rotation of the optic fiber enables the experimental measurements of multi-angle phase information. Based on the filtered back projection algorithm, a 3D refraction index of the optical fiber is thus obtained at high accuracy. To evaluate the proposed approach, both PANDA fibers and special elliptical optical fiber are considered in the system. The results measured in PANDA fibers agree well with those measured using S14 Refractive Index Profiler, which is, however, not suitable for measuring the property of a special elliptical fiber.

  1. Interference Imaging of Refractive Index Distribution in Thin Samples

    Directory of Open Access Journals (Sweden)

    Norbert Tarjanyi

    2004-01-01

    Full Text Available There are three versions of interference imaging of refractive index distribution in thin samples suggested in this contribution. These are based on imaging of interference field created by waves reflected from the front and the back sample surface or imaging of interference field of Michelson or Mach-Zehnder interferometer with the sample put in one of the interferometers arm. The work discusses the advantages and disadvantages of these techniques and presents the results of imaging of refrective index distribution in photorefractive record of a quasi-harmonic optical field in thin LiNbO3 crystal sample.

  2. Negative Refractive Index in Left-Handed Materials

    International Nuclear Information System (INIS)

    The real part of the refractive index n(ω) of a nearly transparent and passive medium is usually taken to have only positive values. Through an analysis of a current source radiating into a 1D ''left-handed'' material (LHM) -- where the permittivity and permeability are simultaneously less than zero -- we determine the analytic structure of n(ω) , demonstrating frequency regions where the sign of Re[n(ω)] must, in fact, be negative. The regime of negative index, made relevant by a recent demonstration of an effective LHM, leads to unusual electromagnetic wave propagation and merits further exploration

  3. Effect of intense high-frequency laser field on the linear and nonlinear intersubband optical absorption coefficients and refractive index changes in a parabolic quantum well under the applied electric field

    Energy Technology Data Exchange (ETDEWEB)

    Yesilgul, U., E-mail: uyesilgul@cumhuriyet.edu.tr [Cumhuriyet University, Physics Department, 58140 Sivas (Turkey); Ungan, F. [Cumhuriyet University, Physics Department, 58140 Sivas (Turkey); Sakiroglu, S. [Dokuz Eylül University, Physics Department, 35160 Buca, İzmir (Turkey); Mora-Ramos, M.E. [Facultad de Ciencias Universidad Autonoma del Estado de Morelos, Ave. Universidad 1001, C.P. 62209 Cuernavaca, Morelos (Mexico); Duque, C.A. [Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Kasapoglu, E.; Sarı, H. [Cumhuriyet University, Physics Department, 58140 Sivas (Turkey); Sökmen, I. [Dokuz Eylül University, Physics Department, 35160 Buca, İzmir (Turkey)

    2014-01-15

    The effects of the intense high-frequency laser field on the optical absorption coefficients and the refractive index changes in a GaAs/GaAlAs parabolic quantum well under the applied electric field have been investigated theoretically. The electron energy levels and the envelope wave functions of the parabolic quantum well are calculated within the effective mass approximation. Analytical expressions for optical properties are obtained using the compact density-matrix approach. The numerical results show that the intense high-frequency laser field has a large effect on the optical characteristics of these structures. Also we can observe that the refractive index and absorption coefficient changes are very sensitive to the electric field in large dimension wells. Thus, this result gives a new degree of freedom in the optoelectronic device applications. -- Highlights: • ILF has a large effect on the optical properties of parabolic quantum wells. • The total absorption coefficients increase as the ILF increases. • The RICs increase as the ILF increases.

  4. Effect of intense high-frequency laser field on the linear and nonlinear intersubband optical absorption coefficients and refractive index changes in a parabolic quantum well under the applied electric field

    International Nuclear Information System (INIS)

    The effects of the intense high-frequency laser field on the optical absorption coefficients and the refractive index changes in a GaAs/GaAlAs parabolic quantum well under the applied electric field have been investigated theoretically. The electron energy levels and the envelope wave functions of the parabolic quantum well are calculated within the effective mass approximation. Analytical expressions for optical properties are obtained using the compact density-matrix approach. The numerical results show that the intense high-frequency laser field has a large effect on the optical characteristics of these structures. Also we can observe that the refractive index and absorption coefficient changes are very sensitive to the electric field in large dimension wells. Thus, this result gives a new degree of freedom in the optoelectronic device applications. -- Highlights: • ILF has a large effect on the optical properties of parabolic quantum wells. • The total absorption coefficients increase as the ILF increases. • The RICs increase as the ILF increases

  5. A wide-range temperature immune ultra-sensitive refractive index sensor using concatenated LPGs

    OpenAIRE

    Tripathi, Saurabh Mani; Kumar, Arun; Bock, Wojtek J.; Mikulic, Predrag

    2013-01-01

    Compensating the temperature induced phase-changes of concatenated dual-resonance long-period-gratings by a suitably chosen inter-grating material and space we report wide-range temperature insensitivity along with extremely high refractive-index sensitivity, on either side of turn-around wavelength.

  6. Compositional dependence of optical band gap and refractive index in lead and bismuth borate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Mallur, Saisudha B.; Czarnecki, Tyler; Adhikari, Ashish; Babu, Panakkattu K.

    2015-08-15

    Highlights: • Refractive indices increase with increasing PbO/Bi{sub 2}O{sub 3} content. • Optical band gap arises due to direct forbidden transition. • Optical band gaps decrease with increasing PbO/Bi{sub 2}O{sub 3} content. • New empirical relation between the optical band gap and the refractive index. - Abstract: We prepared a series of lead and bismuth borate glasses by varying PbO/Bi{sub 2}O{sub 3} content and studied refractive index and optical band gap as a function of glass composition. Refractive indices were measured very accurately using a Brewster’s angle set up while the optical band gaps were determined by analyzing the optical absorption edge using the Mott–Davis model. Using the Lorentz–Lorentz method and the effective medium theory, we calculated the refractive indices and then compared them with the measured values. Bismuth borate glasses show better agreement between the calculated values of the refractive index and experimental values. We used a differential method based on Mott–Davis model to obtain the type of transition and optical band gap (E{sub opt}) which in turn was compared with the value of E{sub opt} obtained using the extinction coefficient. Our analysis shows that in both lead and bismuth borate glasses, the optical band gap arises due to direct forbidden transition. With increasing PbO/Bi{sub 2}O{sub 3} content, the absorption edge shifts toward longer wavelengths and the optical band gap decreases. This behavior can be explained in terms of changes to the Pb−O/Bi−O chemical bonds with glass composition. We obtained a new empirical relation between the optical band gap and the refractive index which can be used to accurately determine the electronic oxide polarizability in lead and bismuth oxide glasses.

  7. Compositional dependence of optical band gap and refractive index in lead and bismuth borate glasses

    International Nuclear Information System (INIS)

    Highlights: • Refractive indices increase with increasing PbO/Bi2O3 content. • Optical band gap arises due to direct forbidden transition. • Optical band gaps decrease with increasing PbO/Bi2O3 content. • New empirical relation between the optical band gap and the refractive index. - Abstract: We prepared a series of lead and bismuth borate glasses by varying PbO/Bi2O3 content and studied refractive index and optical band gap as a function of glass composition. Refractive indices were measured very accurately using a Brewster’s angle set up while the optical band gaps were determined by analyzing the optical absorption edge using the Mott–Davis model. Using the Lorentz–Lorentz method and the effective medium theory, we calculated the refractive indices and then compared them with the measured values. Bismuth borate glasses show better agreement between the calculated values of the refractive index and experimental values. We used a differential method based on Mott–Davis model to obtain the type of transition and optical band gap (Eopt) which in turn was compared with the value of Eopt obtained using the extinction coefficient. Our analysis shows that in both lead and bismuth borate glasses, the optical band gap arises due to direct forbidden transition. With increasing PbO/Bi2O3 content, the absorption edge shifts toward longer wavelengths and the optical band gap decreases. This behavior can be explained in terms of changes to the Pb−O/Bi−O chemical bonds with glass composition. We obtained a new empirical relation between the optical band gap and the refractive index which can be used to accurately determine the electronic oxide polarizability in lead and bismuth oxide glasses

  8. Imaging based refractometer for hyperspectral refractive index detection

    Energy Technology Data Exchange (ETDEWEB)

    Baba, Justin S.; Boudreaux, Philip R.

    2015-11-24

    Refractometers for simultaneously measuring refractive index of a sample over a range of wavelengths of light include dispersive and focusing optical systems. An optical beam including the range of wavelengths is spectrally spread along a first axis and focused along a second axis so as to be incident to an interface between the sample and a prism at a range of angles of incidence including a critical angle for at least one wavelength. An imaging detector is situated to receive the spectrally spread and focused light from the interface and form an image corresponding to angle of incidence as a function of wavelength. One or more critical angles are identified and corresponding refractive indices are determined.

  9. Highly compact refractive index sensor based on stripe waveguides for lab-on-a-chip sensing applications

    Science.gov (United States)

    Perera, Chamanei; Cheng, Elliot; Sathian, Juna; Jaatinen, Esa; Davis, Timothy

    2016-01-01

    Summary In this paper we report the design and experimental realisation of a novel refractive index sensor based on coupling between three nanoscale stripe waveguides. The sensor is highly compact and designed to operate at a single wavelength. We demonstrate that the sensor exhibits linear response with a resolution of 6 × 10−4 RIU (refractive index unit) for a change in relative output intensity of 1%. Authors expect that the outcome of this paper will prove beneficial in highly compact, label-free and highly sensitive refractive index analysis. PMID:27335763

  10. Refractive index of silica aerogel: Uniformity and dispersion law

    International Nuclear Information System (INIS)

    Two methods for the measurement of the uniformity of the refractive index n within a single block of silica aerogel are described. One is based on the deflection of a laser beam induced by transverse index gradients. The second exploits the Cherenkov effect, measuring the emission angle of photons radiated by 500 MeV electrons traversing the aerogel. The beam can scan the full aerogel surface providing information on point to point variations of n. The measurement of the dispersion law n(λ) is also reported. An Xe lamp coupled to a diffraction grating provides the monochromatic source. The index for each λ is measured by the prism method at a corner of an aerogel sample. A Sellmeier functional form for n(λ) is assumed, and the parameters best fitting the experimental data are given

  11. Study of transparent silica aerogel with high refractive index

    International Nuclear Information System (INIS)

    Optical quality of silica aerogel with refractive index values greater than 1.06 has been remarkably improved by introducing a new fabrication technique, called 'pinhole drying method'. This technique allows to produce ultra-high index aerogel up to 1.26 with excellent transparency. The transmission length of the aerogel tile with index of 1.06, obtained with the new method, was found to be doubled compared to that with conventional production. To evaluate the optical performance as a Cherenkov radiator, a prototype RICH counter was built and a test beam experiment was carried out. A clear Cherenkov ring has been observed and significant increase in the detected light yield has been confirmed.

  12. Alteration in refractive index profile during accommodation based on mechanical modelling

    OpenAIRE

    Bahrami, Mehdi; Heidari, Ali; Pierscionek, Barbara K.

    2015-01-01

    The lens of the eye has a gradient refractive index (GRIN). Ocular accommodation, which alters the shape of the lens in response to visual demand, causes a redistribution of the internal structure of the lens leading to a change in the GRIN profile. The nature of this redistribution and the consequence of change in the GRIN profile are not understood. A modelling approach that considers how the GRIN profile may change with accommodation needs to take into account optical and mecha...

  13. The Refractive Index Measurement Of Silicon Dioxide Thin Film by the Coupling Prism Method

    International Nuclear Information System (INIS)

    Refractive index of silicon dioxide thin film that doped with phosphor (SiO2:P) above the pure silicon dioxide substrate has been measured by light coupling prism method. The method principle is focusing the light on coupling prism base so that the light propagates into the waveguide layer while the reflected one forms a mode in the observation plane. The SiO2 thin film as waveguide layer has a refractive index that give the thick and refractive index relation. The He-Ne laser as light source has the wavelength λ 0,6328 μm. The refractive index measurement of the thin film with the substrate refractive index nsb = 1,47 and the thin film thick d = 2μm gives ng = 1,5534 ± 0,01136. This method can distinguish the refractive index of thin film about 6% to the refractive index of substrate

  14. Preparation of planar graded refractive index nanocomposites using microfluidics

    International Nuclear Information System (INIS)

    Highlights: → Preparation of planar graded refractive index nanocomposites using microfluidics → Microfluidic channels dispersed nanoparticles achieving high fidelity profiles. → A dispersion of rutile TiO2 nanoparticles created optically functional materials. → A Δn of 0.1 and an optically transparent material were achieved. - Abstract: In this paper, a microfluidics-based approach for preparing graded refractive index polymer composites is described. These graded refractive index polymers have potential for optical applications due to the fidelity and variety of the profiles that can be achieved using microfluidics technology. In this study, microfluidic devices, fabricated in poly(dimethylsiloxane) (PDMS), dispersed TiO2 nanoparticles in a prepolymer solution consisting of low molecular weight poly(ethylene glycol diacrylate) (PEGDA). Following dispersion of the particles to produce a controlled gradient profile in the liquid pre-polymer solution, UV light polymerized the solution to produce graded refractive index nanocomposites. Initially, as a means of understanding the flow parameters and straightforward elucidation of the gradient profiles, fluorescent polystyrene nanoparticles were dispersed. After a general method for dispersing nanoparticles was developed, anatase TiO2 was synthesized and dispersed to produce nanocomposites. However, transmission electron microscope (TEM) analysis and optical microscopy revealed that the particles were agglomerated and, consequently, the amount of TiO2 that would remain in the pre-polymer solution was severely limited. To address the problem of particle settling, rutile TiO2 was synthesized using a different precursor and dispersed. Rutile TiO2 was chosen because the synthesis scheme was expected to yield a well-dispersed solution. Also, rutile TiO2 is less likely to cause interference with the light used both for the polymerization and for demonstrating the material for optical applications. Following synthesis

  15. Prism refractive index measurement at INRiM

    International Nuclear Information System (INIS)

    A simple method to measure the refractive index of a glass prism with very low uncertainty was developed at INRiM. The method is a modification of the classical minimum deviation method. A brief description of the methods used to measure the vertex angles of the prism and the angle of minimum deviation is reported together with the uncertainty evaluation. The technique is going to be validated by a comparison between INRiM and two other laboratories. A relative standard uncertainty better than 1 ppm has been obtained

  16. Refractive index of nanoscale thickness films measured by Brewster refractometry

    CERN Document Server

    Tikhonov, E A; Malyukin, Yu V

    2015-01-01

    It is shown that reflective laser refractometery at Brewster angle can be usefull for precision measurements of refractive indexes (RI) in the transparency band of various films of nanoscale thickness. The RI measurements of nanoscale porous film on the basis of gadolinium orthosilicate and quartz have been carried out as first experience. It is shown that surface light scattering in such films that is connected with clustering of nanoscale pores can decrease the accuracy of the RI measurements at Brewster angle. Estimated physical dependence RI stipulated by the film thickness reduction (3D-2D transition) in the range of (20-160)nm has not been not detected.

  17. Jamin interferometer for precise measurement of refractive index of gases

    Czech Academy of Sciences Publication Activity Database

    Šulc, Miroslav

    Vol. 9442. Bellingham : SPIE-INT SOC OPTICAL ENGINEERING, 2015 - (Kovačičinová, J.; Vít, T.), 94421A-94421A ISBN 978-1-62841-557-5. ISSN 0277-786X. - (SPIE). [Optics and Measurement Conference 2014 (OaM 2014). Liberec (CZ), 07.10.2014-10.10.2014] R&D Projects: GA MŠk(CZ) LO1206 Institutional support: RVO:61389021 Keywords : folded Jamin interferometer * refractive index of gas Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering http://spie.org/Publications/Proceedings/Paper/10.1117/12.2175913

  18. Quantum vacuum emission from a moving refractive index front

    Science.gov (United States)

    Jacquet, M.; König, F.

    2015-09-01

    We investigate the spontaneous emission of light from the quantum vacuum in a dispersive dielectric at a moving Refractive Index Front (RIF). Our aim is to develop further an existing analytical model to fully characterize the emission and calculate its spectrum in different configurations. We show in which conditions the RIF acts as a point of non-return, an artificial black hole event horizon, for modes of the field. We calculate the spectrum of this emission and the number of photons emitted from the vacuum in the unique escaping mode as a function of the RIF height and velocity in the medium.

  19. Modified Kramers-Kronig relations and sum rules for meromorphic total refractive index

    International Nuclear Information System (INIS)

    Modified Kramers-Kronig relations and corresponding sum rules are shown to hold for the total refractive index that can be presented as a sum of complex linear and nonlinear refractive indices, respectively. It is suggested that a self-action process, involving the degenerate third-order nonlinear susceptibility, can yield a negative total refractive index at some spectral range

  20. Analytical Modelling of a Refractive Index Sensor Based on an Intrinsic Micro Fabry-Perot Interferometer

    Directory of Open Access Journals (Sweden)

    Everardo Vargas-Rodriguez

    2015-10-01

    Full Text Available In this work a refractive index sensor based on a combination of the non-dispersive sensing (NDS and the Tunable Laser Spectroscopy (TLS principles is presented. Here, in order to have one reference and one measurement channel a single-beam dual-path configuration is used for implementing the NDS principle. These channels are monitored with a couple of identical optical detectors which are correlated to calculate the overall sensor response, called here the depth of modulation. It is shown that this is useful to minimize drifting errors due to source power variations. Furthermore, a comprehensive analysis of a refractive index sensing setup, based on an intrinsic micro Fabry-Perot Interferometer (FPI is described. Here, the changes over the FPI pattern as the exit refractive index is varied are analytically modelled by using the characteristic matrix method. Additionally, our simulated results are supported by experimental measurements which are also provided. Finally it is shown that by using this principle a simple refractive index sensor with a resolution in the order of 2.15 × 10−4 RIU can be implemented by using a couple of standard and low cost photodetectors.

  1. Refractive index sensing characteristics of dual resonances in rectangular fractal nano-apertures

    Science.gov (United States)

    Aslan, Ekin; Turkmen, Mustafa

    2015-08-01

    Aperture based sensing platforms can be useful for both gas and bio-sensing applications. In this study, we investigate the refractive index sensing characteristics of dual resonances in rectangular fractal nanoapertures. By taking the advantages coming from its aperture based nature and dual band resonant behavior, one can use this platform to detect two different chemical/bio-molecules simultaneously. For the numerical analysis, we study the rectangular fractal nanoantenna array through the finite difference time domain (FDTD) method. We also introduce a fine tuning mechanism for adjusting the resonance frequencies which is important for the sensing applications. Then, we demonstrate the results of refractive index sensitivity tests in order to show the behavior of the structure against the refractive index changes. In these tests, we embed our sensing platform into different cladding media and obtain the refractive index sensing characteristics of dual resonances. Due to the dual-resonant behavior with easily accessible ultra-high-field localization characteristics, the proposed sensing platform can be a good candidate for ultra-sensitive chemical- and bio-sensing applications.

  2. Defocusing properties of Gaussian beams for measuring refractive index of thin transparent samples

    Science.gov (United States)

    Cervantes-L, Joel; Cywiak, Moisés; Olvera-R, Octavio; Morales, Arquímedes

    2013-11-01

    We show how the defocusing properties of Gaussian beams can be used to measure the refractive index of solutions in thin transparent samples (less than 2 mm). Additionally, it is possible to predict analytically the shape of the plot for the refractive index as a function of concentration in any range. Our theory is limited for substances whose refractive index increases with concentration. The thin sample is placed between the focusing lens and its back focal plane and the system is adjusted to best focusing conditions. As a result, changes of the refractive index of the sample cause variations of the size of the focused beam. To measure with high accuracy the size of the beam we use the homodyne knife-edge profilometer while profiling a calibrated holographic reflective grating. The recorded vertical heights of the grating provide statistical data for improving even more the accuracy of the measurements. We demonstrate that the sensitivity of the system is a function of the pitch of the grating allowing selecting the range of interest. We apply our method for glucose liquid solutions. We include analytical description of our method and experimental results.

  3. Optomecatronic system to estimate the index of refraction of a Compound Chromic

    International Nuclear Information System (INIS)

    The paper presents an optomechatronic system, which it can detect the displacement of laser beam refracted by Lophine layer deposited in a slider. The displacement was estimated by mean of image processing. The displacement of the laser beam is a function of the refractive index of the Lophine layer as function of temperature change. The system uses a Graphical User Interface (GUI), where it is possible to control the incidence angle of the laser beam, and the same time, the temperature of the lophine layer can be sensed. (Author)

  4. X-ray refractive index of laser-dressed atoms

    CERN Document Server

    Buth, Christian

    2008-01-01

    We investigated the complex index of refraction in the x-ray regime of atoms in laser light. The laser (intensity up to 10^13 W/cm^2, 800nm) modifies the atomic states but, by assumption, does not excite or ionize the atoms in their electronic ground state. Using quantum electrodynamics, we devise an ab initio theory to calculate the dynamic dipole polarizability and the photoabsorption cross section, which are subsequently used to determine the real and imaginary part, respectively, of the refractive index. The interaction with the laser is treated nonperturbatively; the x-ray interaction is described in terms of a one-photon process. We numerically solve the resolvents involved using a single-vector Lanczos algorithm. Finally, we formulate rate equations to copropagate a laser and an x-ray pulse through a gas cell. Our theory is applied to argon. We study the x-ray polarizability and absorption near the argon K edge over a large range of dressing-laser intensities. We find electromagnetically induced transp...

  5. Refractive index of erbium doped GaN thin films

    Energy Technology Data Exchange (ETDEWEB)

    Alajlouni, S.; Sun, Z. Y.; Li, J.; Lin, J. Y.; Jiang, H. X., E-mail: hx.jiang@ttu.edu [Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, Texas 79409 (United States); Zavada, J. M. [Department of Electrical and Computer Engineering, Polytechnic Institute of New York University, Brooklyn, New York 11201 (United States)

    2014-08-25

    GaN is an excellent host for erbium (Er) to provide optical emission in the technologically important as well as eye-safe 1540 nm wavelength window. Er doped GaN (GaN:Er) epilayers were synthesized on c-plane sapphire substrates using metal organic chemical vapor deposition. By employing a pulsed growth scheme, the crystalline quality of GaN:Er epilayers was significantly improved over those obtained by conventional growth method of continuous flow of reaction precursors. X-ray diffraction rocking curve linewidths of less than 300 arc sec were achieved for the GaN (0002) diffraction peak, which is comparable to the typical results of undoped high quality GaN epilayers and represents a major improvement over previously reported results for GaN:Er. Spectroscopic ellipsometry was used to determine the refractive index of the GaN:Er epilayers in the 1540 nm wavelength window and a linear dependence on Er concentration was found. The observed refractive index increase with Er incorporation and the improved crystalline quality of the GaN:Er epilayers indicate that low loss GaN:Er optical waveguiding structures are feasible.

  6. Dark matter constraints from a cosmic index of refraction

    Science.gov (United States)

    Gardner, Susan; Latimer, David C.

    2010-09-01

    The dark matter candidates of particle physics invariably possess electromagnetic interactions, if only via quantum fluctuations. Taken en masse, dark matter can thus engender an index of refraction which deviates from its vacuum value. Its presence is signaled through frequency-dependent effects in the propagation and attenuation of light. We discuss theoretical constraints on the expansion of the index of refraction with frequency, the physical interpretation of the terms, and the particular observations needed to isolate its coefficients. This, with the advent of new opportunities to view gamma-ray bursts at cosmological distance scales, gives us a new probe of dark matter and a new possibility for its direct detection. As a first application we use the time delay determined from radio afterglow observations of distant gamma-ray bursts to realize a direct limit on the electric charge-to-mass ratio of dark matter of |ɛ|/M<1×10-5eV-1 at 95% C.L.

  7. Simultaneous temperature and refractive index measurement of liquid using a local micro-structured fiber Bragg grating

    Institute of Scientific and Technical Information of China (English)

    Ye Cao; Yinfei Yang; Xiufeng Yang; Zhengrong Tong

    2012-01-01

    An alternative solution for the simultaneous measurement of temperature and refractive index is presented. A local micro-structured fiber Bragg grating (LMSFBG) is formed as the sensing head, in which a standard grating is etched by HF. According to the phase shift theory, the main spectral change of the LMSFBG is the formation of a narrow allowed band, which is strongly dependent on the etching features and the surrounding refractive index. As such, the temperature and refractive index measurements can be achieved by the shifts of the double peaks and narrow allowed band, and their fitting linearity coefficients are 0.996 and 0.994, respectively. Thus, the reflection and transmission peaks of the LMSFBG have a good linear relationship with temperature and refractive index.%An alternative solution for the simultaneous measurement of temperature and refractive index is presented.A local micro-structured fiber Bragg grating (LMSFBG) is formed as the sensing head,in which a standard grating is etched by HF.According to the phase shift theory,the main spectral change of the LMSFBG is the formation of a narrow allowed band,which is strongly dependent on the etching features and the surrounding refractive index.As such,the temperature and refractive index measurements can be achieved by the shifts of the double peaks and narrow allowed band,and their fitting linearity coefficients are 0.996 and 0.994,respectively.Thus,the reflection and transmission peaks of the LMSFBG have a good linear relationship with temperature and refractive index.

  8. Interferometric investigation and simulation of refractive index in glass matrixes containing nanoparticles of varying sizes

    Energy Technology Data Exchange (ETDEWEB)

    Feeney, Michael Gerard; Ince, Rabia; Yukselici, Mehmet Hikmet; Allahverdi, Cagdas

    2011-07-01

    The relationship between refractive index and nanoparticle radii of cadmium selenide (CdSe) nanoparticles embedded within glass matrixes was investigated experimentally and by simulations. A homemade automated Michelson interferometer arrangement employing a rotating table and a He-Ne laser source at a wavelength of 632.8 nm determined the refractive index versus nanoparticle radii of embedded cadmium selenide (CdSe) nanoparticles. The refractive index was found to decrease linearly with nanoparticle radius increase. However, one sample showed a step increase in refractive index; on spectroscopic analysis, it was found that its resonant wavelength matched that of the He-Ne source wavelength. The simulations showed that two conditions caused the step increase in refractive index: low plasma frequency and matched sample and source resonances. This simple interferometer setup defines a new method of determining the radii of nanoparticles embedded in substrates and enables refractive index tailoring by modification of exact annealing conditions.

  9. Tuning the Refractive Index and Optical Band Gap of Silk Fibroin Films by Electron Irradiation

    Directory of Open Access Journals (Sweden)

    S. Asha

    2015-01-01

    Full Text Available The Bombyx mori silk fibroin (SF films were prepared by solution casting method and effects of electron beam on the optical properties and optical constants of the films have been studied by using UV-Visible spectrophotometer. Optical properties like optical band gap Eg, refractive index n, extinction coefficient k, optical conductivity σopt, and dielectric constants ε∗ of virgin and electron irradiated films were determined by using UV-Visible absorption and transmission spectra. It was found that the reduction in optical band gap and increase in refractive index with increasing radiation dosage was observed. It is also observed from results that there is increase in dielectric constants with increasing photon energy. The observed optical changes have been tried to be correlated with the structural changes, revealed through FT-IR spectroscopy. The present study is quite important for tailoring the optical responses of SF films as per specific requirements.

  10. The Refractive Index of Silicon at Gamma Ray Energies

    CERN Document Server

    Habs, D; Jentschel, M; Urban, W

    2011-01-01

    The index of refraction n(E_{\\gamma})=1+\\delta(E_{\\gamma})+i\\beta(E_{\\gamma}) is split into a real part \\delta and an absorptive part \\beta. The absorptive part has the three well-known contributions to the cross section \\sigma_{abs}: the photo effect, the Compton effect and the pair creation, but there is also the inelastic Delbr\\"uck scattering. Second-order elastic scattering cross sections \\sigma_{sca} with Rayleigh scattering (virtual photo effect), virtual Compton effect and Delbr\\"uck scattering (virtual pair creation) can be calculated by integrals of the Kramers-Kronig dispersion relations from the cross section \\sigma_{abs}. The real elastic scattering amplitudes are proportional to the refractive indices \\delta_{photo}, \\delta_{Compton} and \\delta_{pair}. While for X-rays the negative \\delta_{photo} dominates, we show for the first time experimentally and theoretically that the positive \\delta_{pair} dominates for \\gamma rays, opening a new era of \\gamma optics applications, i.e. of nuclear photoni...

  11. Optical Enhancement in Optoelectronic Devices Using Refractive Index Grading Layers.

    Science.gov (United States)

    Lee, Illhwan; Park, Jae Yong; Gim, Seungo; Kim, Kisoo; Cho, Sang-Hwan; Choi, Chung Sock; Song, Seung-Yong; Lee, Jong-Lam

    2016-02-10

    We enhanced the optical transmittance of a multilayer barrier film by inserting a refractive index grading layer (RIGL). The result indicates that the Fresnel reflection, induced by the difference of refractive indices between SixNy and SiO2, is reduced by the RIGL. To eliminate the Fresnel reflection while maintaining high transmittance, the optimized design of grading structures with the RIGL was conducted using an optical simulator. With the RIGL, we achieved averaged transmittance in the visible wavelength region by 89.6%. It is found that the optimized grading structure inserting the multilayer barrier film has a higher optical transmittance (89.6%) in the visible region than that of a no grading sample (82.6%). Furthermore, luminance is enhanced by 14.5% (from 10 190 to 11 670 cd m(-2) at 30 mA cm(-2)) when the grading structure is applied to organic light-emitting diodes. Finally, the results offer new opportunities in development of multilayer barrier films, which assist industrialization of very cost-effective flexible organic electronic devices. PMID:26800204

  12. Optical glass with tightest refractive index and dispersion tolerances for high-end optical designs

    Science.gov (United States)

    Jedamzik, R.; Reichel, S.; Hartmann, P.

    2014-03-01

    In high end optical designs the quality of the optical system not only depends on the chosen optical glasses but also on the available refractive index and Abbe number tolerances. The primary optical design is based on datasheet values of the refractive index and Abbe number. In general the optical position of the delivered glass will deviate from the catalog values by given tolerances due to production tolerances. Therefore in many cases the final optical design needs to be modified based on real glass data. Tighter refractive index and Abbe number tolerances can greatly reduce this additional amount of work. The refractive index and Abbe number of an optical glass is a function of the chemical composition and the annealing process. Tight refractive index tolerances require not only a close control and high reliability of the melting and fine annealing process but also best possible material data. These data rely on high accuracy measurement and accurate control during mass production. Modern melting and annealing procedure do not only enable tight index tolerances but also a high homogeneity of the optical properties. Recently SCHOTT was able to introduce the tightest available refractive index and Abbe number tolerance available in the market: step 0.5 meaning a refractive index tolerance of +/- 0.0001 and an Abbe number tolerance of +/- 0.1%. This presentation describes how the refractive index depends on the glass composition and annealing process and describes the requirements to get to this tightest refractive index and Abbe number tolerance.

  13. Measurement of the magnetic field-dependent refractive index of magnetic fluids in bulk

    Institute of Scientific and Technical Information of China (English)

    Ting Liu; Xianfeng Chen; Ziyun Di; Junfeng Zhang; Xinwan Li; Jianping Chen

    2008-01-01

    An optical alignment-free and highly accurate method is employed to measure the magnetic field-dependent refractive index of magnetic fluid(MF) in bulk.The measured refractive index decreases significantly with the increasing magnetic strength and then tends to saturate in the high intensity range.By applying a tunable magnetic field ranging between 0 and 1661 Oe,the maximum shift of the refractive index of MF in bulk iS found to be 0.0231.

  14. Loop-mirror-based slot waveguide refractive index sensor

    Science.gov (United States)

    Kou, Jun-long; Xu, Fei; Lu, Yan-qing

    2012-12-01

    Loop mirror has been widely used in fiber optical devices and systems for it provides a smart way to make use of the fiber birefringence properties and can enhance the sensitivity greatly. On the other hand, slot waveguide is very promising for optical sensing applications because of their peculiar spatial mode profile. In this paper, we propose and analyze a loop-mirror-based slot waveguide (LMSW) sensor which can be routinely fabricated in modern high-volume complementary metal-oxide-semiconductor (CMOS) process. The finite element method (FEM) simulation results show that the birefringence can be as high as 0.8 which is orders of magnitude than that in conventional birefringent fiber loop mirror. High sensitivity up to 6 × 103 nm/RIU (refractive index unit) is achieved by this scheme.

  15. Loop-mirror-based slot waveguide refractive index sensor

    Directory of Open Access Journals (Sweden)

    Jun-long Kou

    2012-12-01

    Full Text Available Loop mirror has been widely used in fiber optical devices and systems for it provides a smart way to make use of the fiber birefringence properties and can enhance the sensitivity greatly. On the other hand, slot waveguide is very promising for optical sensing applications because of their peculiar spatial mode profile. In this paper, we propose and analyze a loop-mirror-based slot waveguide (LMSW sensor which can be routinely fabricated in modern high-volume complementary metal-oxide–semiconductor (CMOS process. The finite element method (FEM simulation results show that the birefringence can be as high as 0.8 which is orders of magnitude than that in conventional birefringent fiber loop mirror. High sensitivity up to 6 × 103 nm/RIU (refractive index unit is achieved by this scheme.

  16. Controlling a microdisk laser by local refractive index perturbation

    Energy Technology Data Exchange (ETDEWEB)

    Liew, Seng Fatt; Redding, Brandon; Cao, Hui, E-mail: hui.cao@yale.edu [Department of Applied Physics, Yale University, New Haven, Connecticut 06520 (United States); Ge, Li [Department of Engineering Science and Physics, College of Staten Island, CUNY, Staten Island, New York 10314 (United States); The Graduate Center, CUNY, New York, New York 10016 (United States); Solomon, Glenn S. [Joint Quantum Institute, NIST and University of Maryland, Gaithersburg, Maryland 20899 (United States)

    2016-02-01

    We demonstrate a simple yet effective approach of controlling lasing in a semiconductor microdisk by photo-thermal effect. A continuous wave green laser beam, focused onto the microdisk perimeter, can enhance or suppress lasing in different cavity modes, depending on the position of the focused beam. Its main effect is a local modification of the refractive index of the disk, which results in an increase in the power slope of some lasing modes and a decrease of others. The boundary roughness breaks the rotational symmetry of a circular disk, allowing the lasing process to be tuned by varying the green beam position. Using the same approach, we can also fine tune the relative intensity of a quasi-degenerate pair of lasing modes. Such post-fabrication control, enabled by an additional laser beam, is flexible and reversible, thus enhancing the functionality of semiconductor microdisk lasers.

  17. Scattering and refractive index properties of skin obtained with OCT

    Science.gov (United States)

    Knuettel, Alexander R.; Bonev, Slavtcho M.; Knaak, W.

    2003-10-01

    Optical Coherence Tomography (OCT) provides more parameters than pure morphology does. In a recent paper we have shown that the refractive index (RI) can be evaluated in a localized manner in skin tissue under in vivo conditions. Further evaluation provides scattering parameters (scatter width) of turbid materials down to penetration depths of some 100 μm. Measurements have been done in vitro in pig skin and in vivo in human skin with our OCT scanner SkinDex 300. The parameters RI and scatter width may have a viable impact on skin research and clinical diagnoses. In addition, we demonstrate the breakdown of the ballistic light propagation in turbid material and tissue due to multiple forward scattering.

  18. Controlling a microdisk laser by local refractive index perturbation

    International Nuclear Information System (INIS)

    We demonstrate a simple yet effective approach of controlling lasing in a semiconductor microdisk by photo-thermal effect. A continuous wave green laser beam, focused onto the microdisk perimeter, can enhance or suppress lasing in different cavity modes, depending on the position of the focused beam. Its main effect is a local modification of the refractive index of the disk, which results in an increase in the power slope of some lasing modes and a decrease of others. The boundary roughness breaks the rotational symmetry of a circular disk, allowing the lasing process to be tuned by varying the green beam position. Using the same approach, we can also fine tune the relative intensity of a quasi-degenerate pair of lasing modes. Such post-fabrication control, enabled by an additional laser beam, is flexible and reversible, thus enhancing the functionality of semiconductor microdisk lasers

  19. Finite element approximation of the radiative transport equation in a medium with piece-wise constant refractive index

    Energy Technology Data Exchange (ETDEWEB)

    Lehtikangas, O., E-mail: Ossi.Lehtikangas@uef.fi [Department of Applied Physics, University of Eastern Finland, PO Box 1627, 70211 Kuopio (Finland); Tarvainen, T. [Department of Applied Physics, University of Eastern Finland, PO Box 1627, 70211 Kuopio (Finland); Department of Computer Science, University College London, Gower Street, London WC1E 6BT (United Kingdom); Kim, A.D. [Applied Mathematics Unit, School of Natural Sciences, University of California, Merced, CA 95343 (United States); Arridge, S.R. [Department of Computer Science, University College London, Gower Street, London WC1E 6BT (United Kingdom)

    2015-02-01

    The radiative transport equation can be used as a light transport model in a medium with scattering particles, such as biological tissues. In the radiative transport equation, the refractive index is assumed to be constant within the medium. However, in biomedical media, changes in the refractive index can occur between different tissue types. In this work, light propagation in a medium with piece-wise constant refractive index is considered. Light propagation in each sub-domain with a constant refractive index is modeled using the radiative transport equation and the equations are coupled using boundary conditions describing Fresnel reflection and refraction phenomena on the interfaces between the sub-domains. The resulting coupled system of radiative transport equations is numerically solved using a finite element method. The approach is tested with simulations. The results show that this coupled system describes light propagation accurately through comparison with the Monte Carlo method. It is also shown that neglecting the internal changes of the refractive index can lead to erroneous boundary measurements of scattered light.

  20. Finite element approximation of the radiative transport equation in a medium with piece-wise constant refractive index

    International Nuclear Information System (INIS)

    The radiative transport equation can be used as a light transport model in a medium with scattering particles, such as biological tissues. In the radiative transport equation, the refractive index is assumed to be constant within the medium. However, in biomedical media, changes in the refractive index can occur between different tissue types. In this work, light propagation in a medium with piece-wise constant refractive index is considered. Light propagation in each sub-domain with a constant refractive index is modeled using the radiative transport equation and the equations are coupled using boundary conditions describing Fresnel reflection and refraction phenomena on the interfaces between the sub-domains. The resulting coupled system of radiative transport equations is numerically solved using a finite element method. The approach is tested with simulations. The results show that this coupled system describes light propagation accurately through comparison with the Monte Carlo method. It is also shown that neglecting the internal changes of the refractive index can lead to erroneous boundary measurements of scattered light

  1. Refractive index measurement of nanoparticles by immersion refractometry based on a surface plasmon resonance sensor

    Science.gov (United States)

    Kano, Hiroshi; Iseda, Ayumu; Ohenoja, Katja; Niskanen, Ilpo

    2016-06-01

    Accurate determination of the refractive index of nanoparticles has important ramifications for applications, such as pharmaceuticals, cosmetics, paints, textiles, and inks. We describe a new method to determine the refractive index of nanoparticles by immersion refractometry with a surface plasmon resonance sensor. With this method, the refractive index of the nanoparticles is perfectly matched with that of the surrounding liquid. We demonstrate this method for calcium fluoride nanoparticles that have an average diameter of 100 nm; the results achieve an accuracy of better than 0.002 refractive index units.

  2. Refractive index sensor based on a 1D photonic crystal in a microfluidic channel

    DEFF Research Database (Denmark)

    Rodrigues de Sousa Nunes, Pedro André; Mortensen, Asger; Kutter, Jörg Peter;

    2010-01-01

    A refractive index sensor has been fabricated in silicon oxynitride by standard UV lithography and dry etching processes. The refractive index sensor consists of a 1D photonic crystal (PhC) embedded in a microfluidic channel addressed by fiber-terminated planar waveguides. Experimental demonstrat......A refractive index sensor has been fabricated in silicon oxynitride by standard UV lithography and dry etching processes. The refractive index sensor consists of a 1D photonic crystal (PhC) embedded in a microfluidic channel addressed by fiber-terminated planar waveguides. Experimental...

  3. Cryogenic Refractive Index and Coefficient of Thermal Expansion for the S-TIH1 Glass

    Science.gov (United States)

    Quijada, Manuel A.; Leviton, Douglas; Content, David

    2013-01-01

    Using the CHARMS facility at NASA GSFC, we have measured the cryogenic refractive index of the Ohara S-TIH1 glass from 0.40 to 2.53 micrometers and from 120 to 300 K. We have also examined the spectral dispersion and thermo-optic coefficients (dn/dT). We also derived temperature-dependent Sellmeier models from which refractive index may be calculated for any wavelength and temperature within the stated ranges of each model. The S-TIH1 glass we tested exhibited unusual behavior in the thermo-optic coefficient. We found that for delta coefficient of thermal expansion (CTE) for the similar batch of S-TIH1 glass in order to understand its thermal properties. The CTE showed a monotonic change with a decrease in temperature.

  4. Simultaneous measurement of refractive index and temperature using a dual polarization ring.

    Science.gov (United States)

    Liu, Penghao; Shi, Yaocheng

    2016-05-01

    We present the design, fabrication, and characterization of a dual polarization silicon-on-insulator (SOI) microring resonator (MRR) for simultaneous measurement of refractive index (RI) and temperature. Due to the different energy distribution of transverse electric (TE) and transverse magnetic (TM) modes for the SOI waveguide, the TE and TM polarizations can have quite different sensitivities toward the changes of ambient RI and temperature. By using a gapless asymmetric coupling section, TE0 mode and TM0 mode have been excited simultaneously in the MRR. We demonstrated the feasibility ofobtaining RI and temperature simultaneously with a single measurement, achieving a RI sensitivity of 104 nm/RIU (refractive index unit) and a temperature sensitivity of 78.7 pm/°C for TE0 mode and a RI sensitivity of 319 nm/RIU and a temperature sensitivity of 34.1 pm/°C for TM0 mode. PMID:27140367

  5. Double-layered metal grating for high-performance refractive index sensing.

    Science.gov (United States)

    Li, Guozhen; Shen, Yang; Xiao, Guohui; Jin, Chongjun

    2015-04-01

    The detection of minuscule changes in the local refractive index by localized surface plasmon resonances (LSPRs), carried by metal nanostructures, has been used successfully in applications such as real-time and label-free detection of molecular binding events. However, localized plasmons demonstrate 1-2 orders of magnitude lower figure of merit (FOM) compared with their propagating counterparts. Here, we propose and experimentally demonstrate a high-performance refractive index sensor based on a structure of double-layered metal grating (DMG) with an FOM and FOM* reaching 38 and 40 respectively under normal incidence. Such a high FOM and FOM* arise from a result of a sharp fano resonance, which is caused by the coherent interference between the LSPR from the individual top gold stripes and Wood's anomaly (WA). Moreover, a small conformal decay length of ~68 nm is determined in DMG, indicating that the DMG is a promising candidate for label-free biomedical sensing. PMID:25968735

  6. Asymmetric Mach-Zehnder interferometers without an interaction window in polymer foils for refractive index sensing.

    Science.gov (United States)

    Hofmann, Meike; Xiao, Yanfen; Sherman, Stanislav; Gleissner, Uwe; Schmidt, Thomas; Zappe, Hans

    2016-02-10

    We report on the fabrication and characterization of integrated Mach-Zehnder interferometers in polymer foil without an interaction window. The interferometers are based on inverted rib waveguides, which allow single mode behavior even for waveguide widths larger than a few micrometers. The phase change between the two interferometer arms upon a refractive index change of the analyte that serves as the upper cladding is generated by the asymmetricity of the two interferometer arms. A difference of the waveguide width in the straight part of the interferometer leads to different effective refractive indices and thus to a change in the interference signal. We show in small scale the process chain, which is compatible with a cost-effective roll-to-roll fabrication process. For a proof of principle we apply deionized water and a glucose solution as analytes to the sensor foils and detect the transmitted intensity as a measure of the induced phase change. A detection limit of 3·10⁻³ refractive index units is reached for homogeneous sensing at a total system length of 9.3 mm and a total waveguide core thickness of 3 μm. PMID:26906387

  7. Optical refractive index of massive particles and physical meanings of left-handed media [rapid communication

    Science.gov (United States)

    Shen, Jian Qi

    2005-09-01

    In this Letter the expression for the refractive index of de Broglie wave in the presence of a potential field is obtained and based on this, the physical meanings of negative index of refraction is revealed. We demonstrate that the electromagnetic wave propagation in a left-handed medium with negative refractive index behaves just like that of antiphotons, which is required of the complex vector field theory. It is believed that the complex vector field theory is helpful in considering the wave propagation and photonic band gap structures in the left-handed medium photonic crystals with a periodicity in negative and positive indices of refraction.

  8. Design and fabrication activity towards 3D negative refraction index materials in the IR region

    DEFF Research Database (Denmark)

    Malureanu, Radu; Andryieuski, Andrei; Lavrinenko, Andrei

    2009-01-01

    In this paper we present a new 3D isotropic structure that allows obtaining negative refraction index in the telecom wavelength as well as first fabrication efforts towards obtaining such structures.......In this paper we present a new 3D isotropic structure that allows obtaining negative refraction index in the telecom wavelength as well as first fabrication efforts towards obtaining such structures....

  9. Measurement of the refractive index and attenuation length of liquid xenon for its scintillation light

    International Nuclear Information System (INIS)

    The attenuation length and refractive index of liquid xenon for its intrinsic scintillation light (λ=178 nm) have been measured in a single experiment. The value obtained for the attenuation length is 364±18 mm. The refractive index is found to be 1.69±0.02. Both values were measured at a temperature of 170±1 K

  10. Spectral response of Cantor multilayers made of materials with negative refractive index

    CERN Document Server

    Gerardin, J; Gerardin, Jaline; Lakhtakia, Akhlesh

    2002-01-01

    Whereas Cantor multilayers made of an isotropic dielectric-magnetic material with positive refractive index will show power-law characteristics, low-order Cantor multilayers made of materials with negative refractive index will not exhibit the power-law nature. A reason for this anomalous behavior is presented.

  11. Refractive Index Measurement within a Photonic Crystal Fibre Based on Short Wavelength Diffraction

    Directory of Open Access Journals (Sweden)

    Nathaniel Groothoff

    2007-10-01

    Full Text Available A new class of refractive index sensors using solid core photonic crystal fibres isdemonstrated. Coherent scattering at the cladding lattice is used to optically characterizematerials inserted into the fibre holes. The liquid to solid phase transition of water uponfreezing to ice 1h is characterized by determining the refractive index.

  12. X-ray tomography using the full complex index of refraction

    DEFF Research Database (Denmark)

    Nielsen, Mikkel Schou; Lauridsen, Torsten; Thomsen, M.;

    2012-01-01

    We report on x-ray tomography using the full complex index of refraction recorded with a grating-based x-ray phase-contrast setup. Combining simultaneous absorption and phase-contrast information, the distribution of the full complex index of refraction is determined and depicted in a bivariate...

  13. Electromagnetically induced transparency in planar complementary metamaterial for refractive index sensing applications

    International Nuclear Information System (INIS)

    We report on numerical work concerning a planar complementary metamaterial analogue of electromagnetically induced transparency (EIT) capable of exhibiting refractive index sensing with high sensitivity. The unit cell of the proposed complementary metamaterial consists of two cut-out nanostructures in a homogeneous metallic film, and can exhibit a sharply narrow reflectance transparency peak at near-infrared region breaking its structural symmetry. Moreover, the transparency peak shows highly sensitive response to the refractive index change in the surrounding medium. A complementary metamaterial sensor based on the EIT-like effect can yield a sensitivity of 928.9 nm/refractive index unit (RIU) and a figure of merit (FOM) of 19.2 increasing a supporting layer between the metamaterial and the substrate. The high sensitivity is attributed to the well-confined electric field and the increased spatial overlap between the induced local electric field and the surrounding medium. In addition, the sensitivity and FOM can be further improved by optimizing the asymmetric degree of two cut-out structures. (paper)

  14. Refractive index dependent local electric field enhancement in cylindrical gold nanohole

    International Nuclear Information System (INIS)

    We report on the local electric field characters in a long cylindrical gold nanohole. Theoretical calculation results based on quasi-static model show that the local environmental dielectric constant dependent electric field intensity and field distribution in the gold nanohole show quite unique properties, different from those in the thin gold nanotube. Because of the thick gold wall, no plasmon hybridization exists. So there is only one resonance frequency taking place, and the intense local field has been focused into the gold nanohole. Our main finding is that, the local field in the nanohole is largely dependent on the inner hole refractive index and outer environmental refractive index. The competition between inner hole and outer polarization leads to a non-monotonic change of the local field intensity with increasing the dielectric constant of the nanohole. This refractive index controlled local field enhancement in cylindrical gold nanohole presents a potential for tunable surface-enhanced fluorescence and novel nano-optical biosensing applications.

  15. Gradient shadow pattern reveals refractive index of liquid

    Science.gov (United States)

    Kim, Wonkyoung; Kim, Dong Sung

    2016-06-01

    We propose a simple method that uses a gradient shadow pattern (GSP) to measure the refractive index nL of liquids. A light source generates a “dark-bright-dark” GSP when it is projected through through the back of a transparent, rectangular block with a cylindrical chamber that is filled with a liquid sample. We found that there is a linear relationship between nL and the proportion of the bright region in a GSP, which provides the basic principle of the proposed method. A wide range 1.33 ≤ nL ≤ 1.46 of liquids was measured in the single measurement setup with error <0.01. The proposed method is simple but robust to illuminating conditions, and does not require for any expensive or precise optical components, so we expect that it will be useful in many portable measurement systems that use nL to estimate attributes of liquid samples.

  16. Polymer-based composite with outstanding mechanically tunable refractive index

    Science.gov (United States)

    Mohamed-Noriega, Nasser; Hinojosa, Moisés; González, Virgilio; Rodil, Sandra. E.

    2016-08-01

    A composite with high visible light transmittance, mechanically tunable refractive index (RI) and rubber-like mechanical properties, based on poly(dimethylsiloxane) (PDMS) and barium titanate nanoparticles (BT) was prepared on three steps. First, BT nanoparticles were obtained by high-energy milling. Second, the nanoparticles were embedded in PDMS by in-situ polymerization; the BT content was varied up to 1.0 wt% (0.17 vol%). Finally, ∼0.5 mm membranes were prepared by solvent casting. The effect of the BT concentration was examined. Powder XRD and Raman spectroscopy revealed a tetragonal crystal structure for the nanoparticles. SEM images confirmed a mean particle size of ∼64 nm and together with EDX mappings showed a moderate dispersion of the nanoparticles in some membranes, whereas other exhibited agglomerates at the surface. The normal transmittance of the membranes was measured with a spectroscopic ellipsometer while they were stretched in-situ at different percentages. The RI variations as a function of strain were calculated from the transmittance spectra. The results exhibit surprising variations in the RI, up to ∼5 times higher than those associated to PDMS alone, implying that the presence of BT significantly influences the optical response of the PDMS when stretched. However, the response is neither linear nor well understood; further studies must be performed to clarify this new interaction.

  17. Optical polymers with tunable refractive index for nanoimprint technologies

    International Nuclear Information System (INIS)

    In order to realize a versatile high throughput production of micro-optical elements, UV-curable polymer composites containing titanium dioxide nanoparticles were prepared and characterized. The composites are based on an industrial prototype epoxy polymer. Titanium dioxide nanoparticles smaller than 10 nm were synthesized by the nonaqueous sol method and in situ sterically stabilized by three different organic surfactants. The composites exhibit high transparency. Distinct alteration of optical transmission properties for visible light and near IR wavelength range could be avoided by adaption of the stabilizing organic surfactant. Most importantly, the refractive index (RI) of the composites that depends on the fraction of incorporated inorganic nanoparticles could be directly tuned. E.g. the RI at a wavelength of 635 nm of a composite containing 23 wt% titanium dioxide nanoparticles is increased to 1.626, with respect to a value of 1.542 for the pure polymer. Furthermore, it could be demonstrated that the prepared inorganic–organic nanocomposites are well suited for the direct fabrication of low-cost micro-optical elements by nanoimprint lithography. A low response of the optical composite properties to temperature treatment up to 220 °C with a shrinkage of only about 4% ensures its application for integrated micro-optical elements in industrial production. (paper)

  18. Refractive index imaging from radiative transfer equation-based reconstruction algorithm: Fundamentals

    International Nuclear Information System (INIS)

    We present the first reconstruction algorithm for refractive index imaging, which is based on the radiative transfer equation (RTE). An objective function is iteratively minimized to find a solution to the problem of inversion of the refractive index field. The function describes the discrepancies of the emerging light measurements on the surface of the sample to be probed with predicted data from the corresponding numerical model. The unknown refractive index field is updated within each reconstruction iteration according to a search direction on the index distribution given by the adjoint model to the RTE. In this paper, emphasis is placed on the theoretical aspects. Preliminary tests are demonstrated on generic phantoms.

  19. Alteration in refractive index profile during accommodation based on mechanical modelling.

    Science.gov (United States)

    Bahrami, Mehdi; Heidari, Ali; Pierscionek, Barbara K

    2016-01-01

    The lens of the eye has a gradient refractive index (GRIN). Ocular accommodation, which alters the shape of the lens in response to visual demand, causes a redistribution of the internal structure of the lens leading to a change in the GRIN profile. The nature of this redistribution and the consequence of change in the GRIN profile are not understood. A modelling approach that considers how the GRIN profile may change with accommodation needs to take into account optical and mechanical parameters and be cognisant of individual variability in the shape and size of lenses. This study models the normalised axial GRIN profile during accommodation using reduced modelling and incorporating finite element analysis to connect inhomogenous mechanical characteristics of the lens to optical performance. The results show that simulated stretching changes the length of the plateau but does not alter the cortical gradient, which supports clinical findings. There is a very small change to the accommodated and non-accommodated profiles when normalised, yet this yields measurable changes in aberrations with around 11% and almost 13% difference in spherical aberration and astigmatism respectively. The results can be used in reconstruction of the refractive index and for investigating gradual changes with age. PMID:26819821

  20. Full-field refractive index distribution measurement of a gradient-index lens with heterodyne interferometry

    International Nuclear Information System (INIS)

    A light beam coming from a circular heterodyne light source with an electro-optic modulator is incident on a gradient-index lens obliquely. The reflected light passes through an analyzer and an imaging lens, and is recorded by a fast CMOS camera. A group of periodic sinusoidal segments recorded by each pixel is modified, and its associated phase is derived with a unique technique. The processes are applied to other pixels; the two-dimensional phase distribution can be obtained similarly. The estimated data are substituted into the special equations derived from Fresnel's equations, and the full-field refractive index distribution of the gradient-index lens can be obtained. This method has the merits of both common-path interferometry and heterodyne interferometry

  1. The DRESOR method for radiative heat transfer in a one-dimensional medium with variable refractive index

    International Nuclear Information System (INIS)

    This paper extends the DRESOR (Distribution of Ratios of Energy Scattered by the medium Or Reflected by the boundary surface) method to radiative transfer in a variable refractive index medium. In this method, the intensity is obtained from the source term along the curved integration paths determined only by the variable refractive index, and the DRESOR values are calculated by the Monte Carlo method in which the propagation of the energy bundles are affected by Snell's law. With given temperatures on the black boundaries of a one-dimensional medium, the temperature distribution inside the medium with a variable scattering property is calculated under the condition of radiative equilibrium. It is shown that the DRESOR method has a good accuracy in the cases studied. For an isotropic-scattering medium with the same optical thickness, the scattering albedo has no effect on the temperature distribution, which can be obtained from the general equations and can be seen as an extension of what exists for a constant refractive index; however, the different refractive index causes obvious changes in the temperatures inside the medium. The effect of anisotropic scattering on the temperature distribution cannot be ignored, although it is still weaker than the effect caused by variation in the refractive index.

  2. Cladding modes in photonic crystal fiber: characteristics and sensitivity to surrounding refractive index

    Science.gov (United States)

    Jiang, Xiuli; Gu, Zhengtian; Zheng, Li

    2016-01-01

    Characteristics of cladding modes in a photonic crystal fiber (PCF) with triangular air-hole lattice in the cladding are numerically analyzed using a finite element method. The transition for LP11 cladding mode to core mode with variation of the normalized wavelength has been shown. The transition of the LP01 cladding mode to the outer silica mode and reorganization of the LP0m cladding modes caused by varying the fiber radius has been investigated. By choosing the optimized fiber radius, which is located in the cladding modes' reorganization region, the sensitivity of the coupled wavelength between the core mode LP01 and cladding mode LP03 to surrounding refractive index is increased by a factor of five and reaches to 2660 nm/refractive index unit over the range of 1.40 to 1.42. The sensitivity is competitive with that of long-period grating in PCF in response to changes in refractive indices of the medium contained in the cladding air channels.

  3. Digital processing of speckle photography to measure refractive index of a transparent plate

    Science.gov (United States)

    Moustafa, Nasser A.

    2013-04-01

    In this paper, an accurate and efficient method for measuring the refractive index of a transparent plate is developed. The refractive index is evaluated by using Fourier Transform Method (FTM), from a fringe pattern generated by digital speckle photography. The validity and accuracy of the method were confirmed with a standard reference material. Furthermore, the method is insensitive to environmental perturbations, and simple to implement, compared to the conventional index measurement methods providing similar accuracy.

  4. Terahertz multi-metal-wire hybrid-cladding hollow waveguide for refractive index sensing

    Science.gov (United States)

    Ying-Ying, Yu; Xu-You, Li; Kun-Peng, He; Bo, Sun

    2016-02-01

    We propose a design of terahertz refractive index sensing based on the multi-metal-wire (MMW) hybrid-cladding hollow waveguide. The proposed terahertz hybrid-cladding hollow waveguide comprises one air core in the center surrounding MMW surrounded dielectric. The central air core is used for filling lossless measurands and transmitting terahertz light. In particular, the refractive index sensing is realized by measuring the mode field area (MFA) variation of radially polarized mode. The modal effective refractive index, mode field intensity distribution, and mode field area properties responding to the measurand refractive indexes for different operating frequencies and structure dimensions are investigated, respectively. Simulations show that the proposed terahertz refractive index sensor can realize easily the measurement of the measurand refractive index. Meanwhile, the effects of operating frequency and structure parameters on sensitivity and measurement accuracy are also studied. In view of the trade-off between sensitivity and measurement accuracy, the reasonable choice of the operating frequency and structure parameters can optimize appropriately the sensitivity and measurement accuracy, and the sensitivity can reach approximately 0.585 mm2/RIU (RIU is short for refraction index units) with the proper frequency and structure parameter. Project supported by the National Natural Science Foundation of China (Grant No. 51309059).

  5. Density dependence of refractive index of nanoparticle-derived titania films on glass

    Energy Technology Data Exchange (ETDEWEB)

    Matthias, Anja [Institute of Non-Metallic Materials, Clausthal University of Technology, Zehntnerstraße 2a, 38678 Clausthal-Zellerfeld (Germany); Raićevic, Nevena [Faculty of Electrical Engineering, Helmut Schmidt University, Holstenhofweg 85, 21043 Hamburg (Germany); Donfeu Tchana, Romeo [Institute of Non-Metallic Materials, Clausthal University of Technology, Zehntnerstraße 2a, 38678 Clausthal-Zellerfeld (Germany); Kip, Detlef [Faculty of Electrical Engineering, Helmut Schmidt University, Holstenhofweg 85, 21043 Hamburg (Germany); Deubener, Joachim, E-mail: jd@tu-clausthal.de [Institute of Non-Metallic Materials, Clausthal University of Technology, Zehntnerstraße 2a, 38678 Clausthal-Zellerfeld (Germany)

    2014-05-02

    In order to test the relationship of refractive index to mass density within a wide range, porous titania films up to 800 nm thickness were prepared on silica glass by repetitive dip-coating and thermal curing of anatase sols having primary particle sizes below 7 nm. Profilometry showed a decrease in film thickness and an increase in the index of refraction of up to 50%, if the curing temperature was increased from 100 °C to 1000 °C. The decrease in film thickness was related to an increase in mass density, which directly acts on the optical polarizability and thus the (effective) refractive index of the film. In particular, mass density–refractive index calculations were performed using linear (Arago–Biot, Gladstone–Dale) and nonlinear mixture models (Drude, Lorentz–Lorenz), assuming either air- or water-filled pores, while anatase and rutile fractions were determined by X-ray diffraction. These investigations were verified using refractive index and mass density data from literature. For each model noticeable deviations from the expected trend were evident. We show that an empirical power law expression holds for the Lorentz–Lorenz theory and permits to calculate effective density and porosity of titania thin films from effective refractive index with high accuracy. - Highlights: • The relationship of refractive-index-to-mass-density of titania films is investigated. • Commonly used mixture models show noticeable deviations from experimental data. • An empirical power law expression permits to calculate porosity of titania thin films.

  6. Density dependence of refractive index of nanoparticle-derived titania films on glass

    International Nuclear Information System (INIS)

    In order to test the relationship of refractive index to mass density within a wide range, porous titania films up to 800 nm thickness were prepared on silica glass by repetitive dip-coating and thermal curing of anatase sols having primary particle sizes below 7 nm. Profilometry showed a decrease in film thickness and an increase in the index of refraction of up to 50%, if the curing temperature was increased from 100 °C to 1000 °C. The decrease in film thickness was related to an increase in mass density, which directly acts on the optical polarizability and thus the (effective) refractive index of the film. In particular, mass density–refractive index calculations were performed using linear (Arago–Biot, Gladstone–Dale) and nonlinear mixture models (Drude, Lorentz–Lorenz), assuming either air- or water-filled pores, while anatase and rutile fractions were determined by X-ray diffraction. These investigations were verified using refractive index and mass density data from literature. For each model noticeable deviations from the expected trend were evident. We show that an empirical power law expression holds for the Lorentz–Lorenz theory and permits to calculate effective density and porosity of titania thin films from effective refractive index with high accuracy. - Highlights: • The relationship of refractive-index-to-mass-density of titania films is investigated. • Commonly used mixture models show noticeable deviations from experimental data. • An empirical power law expression permits to calculate porosity of titania thin films

  7. Giant refractive-index modulation by two-photon reduction of fluorescent graphene oxides for multimode optical recording

    Science.gov (United States)

    Li, Xiangping; Zhang, Qiming; Chen, Xi; Gu, Min

    2013-01-01

    Graphene oxides (GOs) have emerged as precursors offering the potential of a cost-effective and large-scale production of graphene-based materials. Despite that their intrinsic fluorescence property has already brought interest of researchers for optical applications, to date, refractive-index modulation as one of the fundamental aspects of optical properties of GOs has received less attention. Here we reported on a giant refractive-index modulation on the order of 10−2 to 10−1, accompanied by a fluorescence intensity change, through the two-photon reduction of GOs. These features enabled a mechanism for multimode optical recording with the fluorescence contrast and the hologram-encoded refractive-index modulation in GO-dispersed polymers for security-enhanced high-capacity information technologies. Our results show that GO-polymer composites may provide a new material platform enabling flexible micro-/nano-photonic information devices. PMID:24085266

  8. Bulk refractive-index sensitivities of the THz-range plasmon resonances on a micro-size graphene strip

    International Nuclear Information System (INIS)

    We studied numerically the potential use of a micro-size graphene strip as a surface plasmon (SP) resonance-based bulk refractive-index sensor in the THz frequency regime. Our accurate computational instrument was an in-house algorithm based on integral equations (IEs) and Nystrom discretization. The refractive-index sensitivities and figure-of-merit (FOM) values of the associated plasmon resonances were calculated. It was found that the primary plasmon mode P 1 is more sensitive to the refractive-index changes than plasmons of higher orders, although the latter demonstrated much larger FOM values explained by the higher Q-factors. The FOM values of the higher-order resonances on a graphene strip in the THz range are at a level similar to the FOM values of the localized SP resonances on a noble-metal strip in the optical range. (paper)

  9. Recovering refractive index correlation function from measurement of tissue scattering phase function (Conference Presentation)

    Science.gov (United States)

    Rogers, Jeremy D.

    2016-03-01

    Numerous methods have been developed to quantify the light scattering properties of tissue. These properties are of interest in diagnostic and screening applications due to sensitivity to changes in tissue ultrastructure and changes associated with disease such as cancer. Tissue is considered a weak scatterer because that the mean free path is much larger than the correlation length. When this is the case, all scattering properties can be calculated from the refractive index correlation function Bn(r). Direct measurement of Bn(r) is challenging because it requires refractive index measurement at high resolution over a large tissue volume. Instead, a model is usually assumed. One particularly useful model, the Whittle-Matern function includes several realistic function types such as mass fractal and exponential. Optical scattering properties for weakly scattering media can be determined analytically from Bn(r) by applying the Rayleigh-Gans-Debye (RGD) or Born Approximation, and so measured scattering properties are used to fit parameters of the model function. Direct measurement of Bn(r) would provide confirmation that the function is a good representation of tissue or help in identifying the length scale at which changes occur. The RGD approximation relates the scattering phase function to the refractive index correlation function through a Fourier transform. This can be inverted without approximation, so goniometric measurement of the scattering can be converted to Bn(r). However, geometric constraints of the measurement of the phase function, angular resolution, and wavelength result in a band limited measurement of Bn(r). These limits are discussed and example measurements are described.

  10. Aqueous ammonium thiocyanate solutions as refractive index-matching fluids with low density and viscosity

    CERN Document Server

    Borrero-Echeverry, Daniel

    2016-01-01

    We show that aqueous solutions of ammonium thiocyanate (NH4SCN) can be used to match the index of refraction of several transparent materials commonly used in experiments, while maintaining low viscosity and density compared to other common refractive index-matching liquids. We present empirical models for estimating the index of refraction, density, and kinematic viscosity of these solutions as a function of temperature and concentration. Finally, we summarize some of the chemical compatibility of ammonium thiocyanate with materials commonly used in apparatus.

  11. Extrinsic fiber-optic Fabry-Perot interferometer sensor for refractive index measurement of optical glass

    International Nuclear Information System (INIS)

    A simple fiber-optic sensor based on Fabry-Perot interference for refractive index measurement of optical glass is investigated both theoretically and experimentally. A broadband light source is coupled into an extrinsic fiber Fabry-Perot cavity formed by the surfaces of a sensing fiber end and the measured sample. The interference signals from the cavity are reflected back into the same fiber. The refractive index of the sample can be obtained by measuring the contrast of the interference fringes. The experimental data meet with the theoretical values very well. The proposed technique is a new method for glass refractive index measurement with a simple, solid, and compact structure.

  12. Self-organization of dissipationless solitons in positive- and negative-refractive-index materials

    International Nuclear Information System (INIS)

    A generalized Ginzburg-Landau equation describing dissipative solitons dynamics in negative-refractive-index materials is derived from Maxwell equations. This equation having only real terms with opposite sign differs from the usual Ginzburg-Landau equation for positive-refractive-index media. A cross-compensation between the saturating nonlinearity excess, losses, and gain makes obtained self-organized solitons dissipationless and exceptionally robust. In the presence of such solitons medium becomes effectively dissipationless. The compensation of losses is of particular interest for media with resonant character of interactions like negative-refractive-index materials.

  13. Electromagnetically induced negative refractive index in a V-type four-level atomic system

    International Nuclear Information System (INIS)

    We propose a scheme for realizing negative refractive index in a V-type four-level atomic system. It is shown that the negative refractive index can be achieved in a wide frequency band based on the effect of quantum coherence. It is also found that the frequency band of negative refractive index and the absorption property of left-handed material are manipulated by the pump and control fields. Furthermore, left-handed material with reduced absorption is possible by choosing appropriate parameters

  14. Simultaneous detection of refractive index and surface charges in nanolaser biosensors

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Keisuke; Kishi, Yoji; Hachuda, Shoji; Watanabe, Takumi; Sakemoto, Mai; Nishijima, Yoshiaki; Baba, Toshihiko [Department of Electrical and Computer Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501 (Japan)

    2015-01-12

    The emission intensity of a GaInAsP photonic crystal nanolaser is affected by the pH of the solution, in which the nanolaser is immersed. This phenomenon can be explained by the change in the redox potential, which modifies the filling of electrons at surface states of the semiconductor and hence the nonradiative surface recombination. This phenomenon allows the nanolaser to simultaneously and independently detect the refractive index and electric charges near the surface on the basis of the variation in emission wavelength and intensity, respectively. This paper demonstrates this function through alternate deposition of charged polyelectrolytes and hybridization of deoxyribonucleic acids.

  15. Sensitivity of photonic crystal fiber grating sensors: biosensing, refractive index, strain, and temperature sensing

    DEFF Research Database (Denmark)

    Rindorf, Lars Henning; Bang, Ole

    2008-01-01

    We study the sensitivity of fiber grating sensors in the applications of strain, temperature, internal label-free biosensing, and internal refractive index sensing. New analytical expressions for the sensitivities, valid for photonic crystal fibers are rigorously derived. These are generally valid......, and we identify a previously unaccounted term for temperature and strain sensing. It is shown that dispersion plays a central role in determining the sensitivity, and that dispersion may enhance or suppress sensitivity as well as change the sign of the resonant wavelength shifts. We propose a quality...... factor, Q, for characterizing long period gratings sensors....

  16. Experimental characterization of negative refractive index material NRM at Ka band

    CERN Document Server

    Chatterjee, Sougata

    2016-01-01

    In this paper, we discuss the experimental characterization of a negative refractive material NRM at Ka band using LR labyrinth Ring and wire array WA. We describe in detail the the LR and wire array characterization separately, and after that the combined experimental results, for NRM are reported. The LRs analytical and simulation study is not new but design in Ka band and different experimental procedure for the characterization of the negative refractive index is the novelty of this paper. For performing a negative refractive index experiment we made prism of 150 Prism angle . We get enhanced transmittance of more than 20 dB from background, at a negative angle of refraction. The values of the negative refractive index in a band of about 1 G Hz around 31 GHz are retrieved from the experimental data.

  17. Transmittance and Refractive Index of the Lanthanum Strontium Aluminium Tantalum Oxide Crystal

    Institute of Scientific and Technical Information of China (English)

    HU Bo-Qing; WANG Xiao-Ming; ZHOU Tang; ZHAO Zong-Yuan; WU Xing; CHEN Xiao-Long

    2001-01-01

    The lanthanum strontium aluminium tantalum oxide (LSAT) crystal is grown by means of a floating or pulling method. Its optical transmittance, refractive indices in visible and near-infrared areas and its dispersion curve are reported. The transparence range of LSAT is from 0.45 to 4.2μm and its refractive index is 2.0244.

  18. Liquid Gradient Refractive Index Microlens for Dynamically Adjusting the Beam Focusing

    Directory of Open Access Journals (Sweden)

    Zichun Le

    2015-12-01

    Full Text Available An in-plane liquid gradient index (L-GRIN microlens is designed for dynamically adjusting the beam focusing. The ethylene glycol solution (core liquid withde-ionized (DI water (cladding liquid is co-injected into the lens chamber to form a gradient refractive index profile. The influences of the diffusion coefficient, mass fraction of ethylene glycol and flow rate of liquids on the refractive index profile of L-GRIN microlens are analyzed, and the finite element method and ray tracing method are used to simulate the convection-diffusion process and beam focusing process, which is helpful for the prediction of focusing effects and manipulation of the device. It is found that not only the focal length but the focal spot of the output beam can be adjusted by the diffusion coefficient, mass fraction and flow rate of liquids. The focal length of the microlens varies from 942 to 11 μm when the mass fraction of the ethylene glycol solution varies from 0.05 to 0.4, and the focal length changes from 127.1 to 8 μm by varying the flow rate of the core liquid from 0.5 × 103 to 5 × 103 pL/s when there is no slip between the core and cladding inlet. The multiple adjustable microlens with a simple planar microfluidic structure can be used in integrated optics and lab-on-chip systems.

  19. Application of high-refractive index fluid to KrF-immersion lithography

    Science.gov (United States)

    Yada, Yuji; Ito, Koji; Yamaguchi, Yoshikazu; Furukawa, Taiichi; Miyamatsu, Takashi; Wang, Yong; Hieda, Katsuhiko; Shimokawa, Tsutomu

    2006-03-01

    This paper describes the material characteristics for KrF-immersion lithography with a high refractive index fluid. We have obtained promising results in soaking experiments involving KrF lithography without topcoat film. Although water is currently used as the immersion fluid in 193nm lithography, providing suitable refractive index (n=1.44@193nm and n=1.37@248nm) and transmittance (>99%/mm), it is found to have leaching issues when used with KrF resist. On the other hand, our high refractive index fluid (JSR-HIL-001), which was developed for ArF immersion purposes, satisfies the following requirements: HIL-001 has indicated promising characteristics as a 248nm-immmersion fluid. The refractive index is 1.54@248nm and the transmittance is >99%/mm. In this paper the physical and chemical properties of HIL-001 for KrF-immersion fluid application are discussed in detail.

  20. Characterization and simulation on antireflective coating of amorphous silicon oxide thin films with gradient refractive index

    Science.gov (United States)

    Huang, Lu; Jin, Qi; Qu, Xingling; Jin, Jing; Jiang, Chaochao; Yang, Weiguang; Wang, Linjun; Shi, Weimin

    2016-08-01

    The optical reflective properties of silicon oxide (SixOy) thin films with gradient refractive index are studied both theoretically and experimentally. The thin films are widely used in photovoltaic as antireflective coatings (ARCs). An effective finite difference time domain (FDTD) model is built to find the optimized reflection spectra corresponding to structure of SixOy ARCs with gradient refractive index. Based on the simulation analysis, it shows the variation of reflection spectra with gradient refractive index distribution. The gradient refractive index of SixOy ARCs can be obtained in adjustment of SiH4 to N2O ratio by plasma-enhanced chemical vapor deposition (PECVD) system. The optimized reflection spectra measured by UV-visible spectroscopy confirms to agree well with that simulated by FDTD method.

  1. Method for engineering of refraction index profile of circular crosssection waveguide

    Directory of Open Access Journals (Sweden)

    V. G. Levandovskyy

    2009-10-01

    Full Text Available Engineering method for circular cross-section waveguide refraction index profile is proposed. Mathematical apparatus of Gel’fund-Levitan-Martchenko for solving of inverse scattering problem of nonrelativistic quantum mechanic been used.

  2. Qualitative Analysis of Relationship between Refractive Index and Atomic Parameters of Solid Materials

    Institute of Scientific and Technical Information of China (English)

    罗遵度; 黄艺东

    2004-01-01

    The refractive index is one of the important parameters describing the optical properties of solid materials. However, it is difficult to obtain a quantitative relation between the refractive index and the structure and composition of materials. A qualitative relation between the refractive index and some atomic parameters of materials was proposed and demonstrated by some oxide optical crystals. A parameter P=r-/F=r-/(r+ΔxD) is defined, in which Δx is the difference of the electronegativities between cations and anions in the materials and r+ and r- are the radii of cations and anions respectively. On the other hand, the factor D was introduced to describe the effect of mass difference of the ions. It is demonstrated by both theoretical discussion and experimental data that refractive index is a decreasing function of parameter P. The relation may be useful for the investigation of optical materials.

  3. Single-Mode Optical Waveguides on Native High-Refractive-Index Substrates

    CERN Document Server

    Grote, Richard R

    2016-01-01

    High-refractive-index semiconductor optical waveguides form the basis for modern photonic integrated circuits (PICs) , but the conventional methods of achieving optical confinement require a thick lower-refractive-index support layer that impedes large-scale co-integration with electronics. To address this challenge, we present a general architecture for single-mode waveguides that confine light in a high-refractive-index material on a native substrate. Our waveguide consists of a high-aspect-ratio fin of the guiding material surrounded by lower-refractive-index dielectrics and is compatible with standard top-down fabrication techniques. The proposed waveguide geometry removes the need for a buried-oxide-layer in silicon photonics, as well as the InGaAsP layer in InP-based PICs and will allow for photonic integration on emerging material platforms such as diamond and SiC.

  4. Determination Of Refractive Index And Reflectivity Of Thin Layer With Optical Absorption Method

    International Nuclear Information System (INIS)

    . The refractive index and reflectivity of ASi:H and Si Ox thin layer have been observed by optical absorption methods. Measurement has been done after the preparation of optical system which consists of a halogen lamp light source, monochromator, sample and light detector. The Monochromator output showed that measured halogen lamp spectrum light is between 470 nm -750 nm. The maximum voltage of halogen lamp is 220 Volt, the output light increases in intensity while the wave length increases. The inclination of intensity decrease at the wave length of 725 nm. The result of the calculation of refractive index varies in accordance with the wave length. The average refractive index of ASi:H is nf a = 1.753. The total reflectivity of air-thin layer-substrate is Rt a = 0.315. The refractive index of Si Ox sample is nf b2.182 and the total reflectivity is Rt b=O,514

  5. A study on refractive index sensors based on optical micro-ring resonators

    CERN Document Server

    Tsigaridas, Georgios N

    2015-01-01

    In this work the behavior of optical micro-ring resonators, especially when functioning as refractive index sensors, is studied in detail. Two configurations are considered, namely a linear waveguide coupled to a circular one and two linear waveguides coupled to each other through a circular one. The optimum coupling conditions are derived and it is shown that in both cases the condition for the resonant wavelength, i.e. the wavelength at which the transmission spectrum exhibits a dip (peak), is the same and depends only on the geometrical characteristics of the circular waveguide and the effective refractive index of the propagating mode. The latter, as well as the corresponding mode profile, can be easily calculated through numerical analysis. The sensitivity of the sensor is defined based on the dependence of the effective refractive index on the refractive index of the environment. Using a result of waveguide perturbation theory, the geometrical characteristics of the core of the circular waveguide that m...

  6. Determination of the effective refractive index of porous silicon/polymer composite films

    Institute of Scientific and Technical Information of China (English)

    Zhenhong Jia

    2005-01-01

    The equation for calculating the effective refractive index of porous silicon inserted polymer was obtained by three-component Bruggeman effective medium model. The dependence of the effective refractive index of porous silicon/polymer composite films on the polymer fraction with various initial porosity was given theorically and experimentally respectively. The porous silicon and polymer polymethylmetacrylate based dispersive red one (PMMA/DR1) composite films were fabricated in our experiments. It is found that the measured effective refractive index of porous silicon inserted polymer was slightly lower than the calculated result because of the oxidization of porous silicon. The effective refractive index of oxidized porous silicon inserted polymer also was analyzed by four-component medium system.

  7. A Naked Eye Refractive Index Sensor with a Visible Multiple Peak Metamaterial Absorber

    OpenAIRE

    Heli Ma; Kun Song; Liang Zhou; Xiaopeng Zhao

    2015-01-01

    We report a naked eye refractive index sensor with a visible metamaterial absorber. The visible metamaterial absorber consisting of a silver dendritic/dielectric/metal structure shows multiple absorption peaks. By incorporating a gain material (rhodamine B) into the dielectric layer, the maximal magnitude of the absorption peak can be improved by about 30%. As the metamaterial absorber is sensitive to the refractive index of glucose solutions, it can function as a sensor that quickly responds...

  8. Dependence of refractive indexes dispersion for LiNbO3 on impurity

    International Nuclear Information System (INIS)

    The effect of the impurities of the transition metals Co, Mn, Cr, Fe, Ni, Cu on the dispersion of the refractive indexes of LiNbO3 is studied. The dispersion curves for LiNbO3 are compared to those for the pure crystals. The relation between the difference of the refractive indexes of the pure and doped LiNbO3 and the ionic radius of the impurity is established. (author)

  9. Enhancement of graphene visibility on transparent substrates by refractive index optimization

    OpenAIRE

    Gonçalves, Hugo; Alves, Luis; Moura, C.; Belsley, M.; Stauber, Tobias; Schellenberg, Peter Michael

    2013-01-01

    Optical reflection microscopy is one of the main imaging tools to visualize graphene microstructures. Here is reported a novel method that employs refractive index optimization in an optical reflection microscope, which greatly improves the visibility of graphene flakes. To this end, an immersion liquid with a refractive index that is close to that of the glass support is used in-between the microscope lens and the support improving the contrast and resolution of the sample image. Results sho...

  10. Refraction index of shock compressed water in the megabar pressure range

    Science.gov (United States)

    Batani, D.; Jakubowska, K.; Benuzzi-Mounaix, A.; Cavazzoni, C.; Danson, C.; Hall, T.; Kimpel, M.; Neely, D.; Pasley, J.; Rabec Le Gloahec, M.; Telaro, B.

    2015-11-01

    We compressed water to megabar pressures by laser-driven shock waves and evidenced transparent, opaque and reflecting phases as pressure increases. The refraction index of water in the first two states was measured using a VISAR system. At high compression a sharp increase of the real and imaginary part of the refraction index is observed. Experiments were performed at the LULI and RAL laboratories.

  11. A spatial refractive index sensor using whispering gallery modes in an optically trapped microsphere

    OpenAIRE

    Zijlstra, P.; van der Molen, K. L.; Mosk, A.P.

    2006-01-01

    We propose the use of an optically trapped, dye doped polystyrene microsphere for spatial probing of the refractive index at any position in a fluid. We demonstrate the use of the dye embedded in the microsphere as an internal broadband excitation source, thus eliminating the need for a tunable excitation source. We measured the full width at half maximum of the TE and TM resonances, and their frequency spacing as a function of the refractive index of the immersion fluid. From these relations...

  12. Method of determining effects of heat-induced irregular refractive index on an optical system.

    Science.gov (United States)

    Song, Xifa; Li, Lin; Huang, Yifan

    2015-09-01

    The effects of an irregular refractive index on optical performance are examined. A method was developed to express a lens's irregular refractive index distribution. An optical system and its mountings were modeled by a thermomechanical finite element (FE) program in the predicted operating temperature range, -45°C-50°C. FE outputs were elaborated using a MATLAB optimization routine; a nonlinear least squares algorithm was adopted to determine which gradient equation best fit each lens's refractive index distribution. The obtained gradient data were imported into Zemax for sequential ray-tracing analysis. The root mean square spot diameter, modulation transfer function, and diffraction ensquared energy were computed for an optical system under an irregular refractive index and under thermoelastic deformation. These properties are greatly reduced by the irregular refractive index effect, which is one-third to five-sevenths the size of the thermoelastic deformation effect. Thus, thermal analyses of optical systems should consider not only thermoelastic deformation but also refractive index irregularities caused by inhomogeneous temperature. PMID:26368895

  13. Label free detection of DNA hybridization by refractive index tapered fiber biosensor

    Science.gov (United States)

    Zibaii, M. I.; Latifi, H.; Ghanati, E.; Gholami, M.; Hosseini, S. M.

    2010-04-01

    We demonstrate a simple refractive index sensor (RI) sensing system based on a biconical tapered optical fiber (BTOF), which is fabricated by heat pulling method, utilizing a CO2 laser. In this work we explore the application of these sensors for the detection of label free single stranded DNA (ssDNA) in real time. During the experiment, the target ssDNA did not need to be labeled with a fluorescent tag, which is expensive and complicated. The change in output optical transmission of the tapered fiber was recorded for Poly-L-Lysine (PLL) coating, ssDNA probe immobilization and hybridization. The result indicated that due to the hybridization with the complementary target ssDNA on the tapered surface, the RI of surrounding medium changes which leads to changes in the characteristics of the tapered region and change in the output power of the sensor.

  14. Surface waves versus negative refractive index in layered superconductors

    OpenAIRE

    Golick, V. A.; Kadygrob, D. V.; Yampol'skii, V. A.; Rakhmanov, A. L.; Ivanov, B. A.; Nori, Franco

    2010-01-01

    We predict a new branch of surface Josephson plasma waves (SJPWs) in layered superconductors for frequencies higher than the Josephson plasma frequency. In this frequency range, the permittivity tensor components along and transverse to the layers have different signs, which is usually associated with negative refraction. However, for these frequencies, the bulk Josephson plasma waves cannot be matched with the incident and reflected waves in the vacuum, and, instead of the negative-refractiv...

  15. Waveguides and nonlinear index of refraction of borate glass doped with transition metals

    Science.gov (United States)

    Almeida, Juliana M. P.; Fonseca, Ruben D.; De Boni, Leonardo; Diniz, Andre Rosa S.; Hernandes, Antonio C.; Ferreira, Paulo H. D.; Mendonca, Cleber R.

    2015-04-01

    The ability to write 3D waveguides by femtosecond laser micromachining and the nonlinear refractive index (n2) spectrum of a new borate glass matrix, containing zinc and lead oxides - (BZP) have been investigated. The transparent matrix was doped with transition metals (CdCl2, Fe2O3, MnO2 and CoO) in order to introduce electronic transitions in visible spectrum, aiming to evaluate their influence on the waveguides and n2 spectrum. We observed that n2 is approximately constant from 600 to 1500 nm, exhibiting an average value of 4.5 × 10-20 m2/W, which is about twice larger than the one for fused silica. The waveguide profile is influenced by the self-focusing effect of the matrix owing to its positive nonlinear index of refraction in the wavelength used for micromachining. A decrease in the waveguide loss of approximately four times was observed for the sample doped with Fe in comparison to the other ones, which may be associated with the change in the optical gap energy.

  16. Refractive change after vitrectomy for epiretinal membrane in pseudophakic eyes

    DEFF Research Database (Denmark)

    Hamoudi, Hassan; Kofod, Mads; La Cour, Morten

    2013-01-01

    Purpose:  To report the change in refraction in pseudophakic eyes following 23-gauge vitrectomy for epiretinal membrane (ERM), without use of silicone oil, intraocular gas or scleral buckling. Methods:  Retrospective review of the records of 28 pseudophakic eyes in 28 patients undergoing 23-gauge...... the mean postoperative refraction was -0.41 ± 0.93 D. Thus, a myopic shift was observed following vitrectomy with a mean change in refraction of -0.26 ± 0.60 D (range +0.75 to -2.13 D, p = 0.032). The postoperative change in refraction was within ±0.25, ±0.50 and ±1.00 D in 39%, 68% and 96% of the...... eyes, respectively. The mean absolute refractive error was 0.47 ± 0.44 D. The change in refraction in fellow eyes was +0.01 D (p = 0.82). Conclusion:  The change in refraction following 23-gauge pars plana vitrectomy for ERM in pseudophakic eyes was -0.26 D....

  17. Thermal-induced surface plasmon band shift of gold nanoparticle monolayer: morphology and refractive index sensitivity

    International Nuclear Information System (INIS)

    In this paper, thermal-induced behaviors of a gold nanoparticle monolayer on glass slides are investigated. First, through horizontal lifting, gold nanoparticle monolayers are transferred from a water/hexane interface to glass slides. Then thermal treatment is carried out in air, after which an apparent color change of the obtained samples is noticed, depending on the annealing temperature, reflecting a shift of the surface plasmon band (SPB). Depending on the trend of SPB shift, the overall thermal process is divided into three stages. In the first stage, SPB shows a redshift trend with concomitant band broadening. Further increase of the annealing temperature in the second stage results in an increase of interparticle distance. Thus an apparent decrease in absorbance takes place with SPB shift to shorter wavelengths. In the third stage, the SPB redshifts again. Bulk refractive index sensitivity (RIS) measurements are taken by immersing the obtained samples in solutions of various refractive indices and a linear dependence of RISλ and RISext on refractive index is concluded. In particular, the influences of parameters such as particle sizes, location of SPB, substrate effect and morphology effect on RIS are discussed in detail. The corresponding performance of each sample as a localized surface plasmon resonance-based sensor is evaluated by a figure of merit (FOM) represented as FOMλ and FOMext. It is found that the optimum annealing temperature is 500 deg. C. In terms of nanoparticle sizes, samples with a 35 nm gold nanoparticle monolayer perform better than those with 15 nm. The current strategy is simple and facile to achieve fine control of the SPB, in which large-size precision instruments or complex chemosynthesis are unnecessary. Therefore, this method has not only significance for theory but also usefulness in practical applications.

  18. Thermal-induced surface plasmon band shift of gold nanoparticle monolayer: morphology and refractive index sensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Xuemin; Zhang Junhu; Wang Huan; Hao Yudong; Zhang Xun; Wang Tieqiang; Wang Yunan; Zhao Ran; Zhang Hao; Yang Bai, E-mail: zjh@jlu.edu.cn [State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012 (China)

    2010-11-19

    In this paper, thermal-induced behaviors of a gold nanoparticle monolayer on glass slides are investigated. First, through horizontal lifting, gold nanoparticle monolayers are transferred from a water/hexane interface to glass slides. Then thermal treatment is carried out in air, after which an apparent color change of the obtained samples is noticed, depending on the annealing temperature, reflecting a shift of the surface plasmon band (SPB). Depending on the trend of SPB shift, the overall thermal process is divided into three stages. In the first stage, SPB shows a redshift trend with concomitant band broadening. Further increase of the annealing temperature in the second stage results in an increase of interparticle distance. Thus an apparent decrease in absorbance takes place with SPB shift to shorter wavelengths. In the third stage, the SPB redshifts again. Bulk refractive index sensitivity (RIS) measurements are taken by immersing the obtained samples in solutions of various refractive indices and a linear dependence of RIS{sub {lambda}} and RIS{sub ext} on refractive index is concluded. In particular, the influences of parameters such as particle sizes, location of SPB, substrate effect and morphology effect on RIS are discussed in detail. The corresponding performance of each sample as a localized surface plasmon resonance-based sensor is evaluated by a figure of merit (FOM) represented as FOM{sub {lambda}} and FOM{sub ext}. It is found that the optimum annealing temperature is 500 deg. C. In terms of nanoparticle sizes, samples with a 35 nm gold nanoparticle monolayer perform better than those with 15 nm. The current strategy is simple and facile to achieve fine control of the SPB, in which large-size precision instruments or complex chemosynthesis are unnecessary. Therefore, this method has not only significance for theory but also usefulness in practical applications.

  19. Thermal-induced surface plasmon band shift of gold nanoparticle monolayer: morphology and refractive index sensitivity

    Science.gov (United States)

    Zhang, Xuemin; Zhang, Junhu; Wang, Huan; Hao, Yudong; Zhang, Xun; Wang, Tieqiang; Wang, Yunan; Zhao, Ran; Zhang, Hao; Yang, Bai

    2010-11-01

    In this paper, thermal-induced behaviors of a gold nanoparticle monolayer on glass slides are investigated. First, through horizontal lifting, gold nanoparticle monolayers are transferred from a water/hexane interface to glass slides. Then thermal treatment is carried out in air, after which an apparent color change of the obtained samples is noticed, depending on the annealing temperature, reflecting a shift of the surface plasmon band (SPB). Depending on the trend of SPB shift, the overall thermal process is divided into three stages. In the first stage, SPB shows a redshift trend with concomitant band broadening. Further increase of the annealing temperature in the second stage results in an increase of interparticle distance. Thus an apparent decrease in absorbance takes place with SPB shift to shorter wavelengths. In the third stage, the SPB redshifts again. Bulk refractive index sensitivity (RIS) measurements are taken by immersing the obtained samples in solutions of various refractive indices and a linear dependence of RISλ and RISext on refractive index is concluded. In particular, the influences of parameters such as particle sizes, location of SPB, substrate effect and morphology effect on RIS are discussed in detail. The corresponding performance of each sample as a localized surface plasmon resonance-based sensor is evaluated by a figure of merit (FOM) represented as FOMλ and FOMext. It is found that the optimum annealing temperature is 500 °C. In terms of nanoparticle sizes, samples with a 35 nm gold nanoparticle monolayer perform better than those with 15 nm. The current strategy is simple and facile to achieve fine control of the SPB, in which large-size precision instruments or complex chemosynthesis are unnecessary. Therefore, this method has not only significance for theory but also usefulness in practical applications.

  20. Novel optical devices based on the tunable refractive index of magnetic fluid and their characteristics

    International Nuclear Information System (INIS)

    As a new type of functional material, magnetic fluid (MF) is a stable colloid of magnetic nanoparticles, dressed with surfactant and dispersed in the carrier liquid uniformly. The MF has many unique optical properties, and the most important one is its tunable refractive index property. This paper summarizes the properties of the MF refractive index and the related optical devices. The refractive index can be easily controlled by external magnetic field, temperature, and so on. But the tunable refractive index of MF has a relaxation effect. As a result, the response time is more than milliseconds and the MF is only suitable for low speed environment. Compared with the traditional optical devices, the magnetic fluid based optical devices have the tuning ability. Compared with the tunable optical devices (the electro-optic devices (LiNbO3) of more than 10 GHz modulation speed, acoustic-optic devices (Ge) of more than 20 MHz modulation speed), the speed of the magnetic fluid based optical devices is low. Now there are many applications of magnetic fluid based on the refractive index in the field of optical information communication and sensing technology, such as tunable beam splitter, optical-fiber modulator, tunable optical gratings, tunable optical filter, optical logic device, tunable interferometer, and electromagnetic sensor. With the development of the research and application of magnetic fluid,a new method, structure and material to improve the response time can be found, which will play an important role in the fields of optical information communication and sensing technology. - Highlights: → Magnetic fluid is a new type of functional material, which has many unique optical properties. → We summarize the tunable refractive index property and the related optical devices. → Refractive index can be easily controlled by external magnetic field, temperature and so on. → There are many applications in the field of optical communication and sensing

  1. Effects of atmospheric humidity on the refractive index and the size distribution of aerosols as estimated from light scattering measurements.

    OpenAIRE

    Takamura, Tamio; Tanaka, Masayuki; Nakajima, Teruyuki

    1984-01-01

    The complex index of refraction, scattering cross section and albedo for single scattering have been estimated from measurements of the angular distribution of light scattered by aerosol particles, by an inversion library method. The humidity dependence of these optical properties has been examined in compiling 250 samples for the period FebruaryNovember 1978. It is found that optical properties of aerosol particles change systematically according to the change of relative humidity. The humid...

  2. High refractive index composite for broadband antireflection in terahertz frequency range

    Science.gov (United States)

    Wang, Xuecheng; Li, Yunzhou; Cai, Bin; Zhu, YiMing

    2015-06-01

    In this study, titania-polymer composites with a very high refractive-index tenability and high transparency in the terahertz region were prepared. By controlling the blending ratio of the titania particle, a broad refractive-index tuning range from 1.5 to 3.1 was realized. Then, the composites were used to fabricate antireflective (AR) layers of high-resistivity silicon (HR-Si). By utilizing the thermoplasticity of the titania-polymer composite, a graded-index structure was fabricated via a hot-embossing method. Because of the good refractive-index matching between the composite and the HR-Si substrate, a broadband (0.2-1.6 THz, 7% reflection) AR layer was fabricated.

  3. Optimum Forward Light Scattering by Spherical and Spheroidal Dielectric Nanoparticles with High Refractive Index

    CERN Document Server

    Luk`yanchuk, Boris S; Paniagua-Dominguez, Ramon; Kuznetsov, Arseniy I

    2014-01-01

    High-refractive index dielectric nanoparticles may exhibit strong directional forward light scattering at visible and near-infrared wavelengths due to interference of simultaneously excited electric and magnetic dipole resonances. For a spherical high-index dielectric, the so-called first Kerker's condition can be realized, at which the backward scattering practically vanishes for some combination of refractive index and particle size. However, Kerker's condition for spherical particles is only possible at the tail of the scattering resonances, when the particle scatters light weakly. Here we demonstrate that significantly higher forward scattering can be realized if spheroidal particles are considered instead. For each value of refractive index exists an optimum shape of the particle, which produces minimum backscattering efficiency together with maximum forward scattering. This effect is achieved due to the overlapping of magnetic and electric dipole resonances of the spheroidal particle at the resonance fr...

  4. Integrated microsphere whispering gallery mode probe for highly sensitive refractive index measurement

    Science.gov (United States)

    Wang, Hanzheng; Yuan, Lei; Kim, Cheol-Woon; Huang, Jie; Lan, Xinwei; Xiao, Hai

    2016-06-01

    We report an integrated whispering gallery mode microresonator-based sensor probe for refractive index sensing. The probe was made by sealing a borosilicate glass microsphere into a thin-wall glass capillary pigtailed with a multimode optical fiber. The intensities of the resonant peaks were found decreasing exponentially (linearly in a log scale) with the increasing refractive index of the medium surrounding the capillary. The sensing capability of the integrated probe was tested using sucrose solutions of different concentrations and the resolution was estimated to be about 2.5×10-5 in the index range of 1.3458 to 1.3847. The integrated sensor probe may prove useful in many chemical and biological sensing applications where highly sensitive refractive index monitoring is needed.

  5. Quasi-guiding modes in microfibers on high refractive index substrate

    CERN Document Server

    Wang, Kaiyang; Sun, Wenzhao; Li, Jiankai; Xiao, Shumin; Song, Qinghai

    2015-01-01

    Light confinement and amplification in micro- & nano-fiber have been intensively studied and a number of applications have been developed. However, the typical micro- & anno- fibers are usually free-standing or positioned on a substrate with lower refractive index to ensure the light confinement and guiding mode. Here we numerically and experimentally demonstrate the possibility of confining light within a microfiber on a high refractive index substrate. In contrast to the strong leaky to the substrate, we found that the radiation loss was dependent on the radius of microfiber and the refractive index contrast. Consequently, quasi-guiding modes could be formed and the light could propagate and be amplified in such systems. By fabricating tapered silica fiber and dye-doped polymer fiber and placing them on sapphire substrates, the light propagation, amplification, and laser behaviors have been experimentally studied to verify the quasi-guiding modes in microfer with higher index substrate. We believe t...

  6. Air refractivity index in optical region: formulas and measurement in CZ

    Czech Academy of Sciences Publication Activity Database

    Pešice, Petr; Fišer, Ondřej; Chládová, Zuzana; Brázda, Vladimír

    Portsmouth : University of Portsmouth, 2012, COST IC0802/1-COST IC0802/7. [MCM 7. Portsmouth (GB), 16.04.2012-18.04.2012] R&D Projects: GA MŠk OC09027 Institutional support: RVO:68378289 Keywords : Refractivity index * structure index * free-space optics * temperature * humidity * air pressure Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  7. How indexes have changed

    International Nuclear Information System (INIS)

    The accompanying table compares refinery construction and operating wages monthly for the years 1990 and 1991. The Nelson-Farrar refinery construction cost indexes are inflation indexes, while the operating indexes incorporate a productivity which shows improvement with experience and the increasing size of operations. The refinery construction wage indexes in the table show a steady advance over the 2-year period. Common labor indexes moved up faster than skilled indexes. Refinery operating wages showed a steady increase, while productivities averaged higher near the end of the period. Net result is that labor costs remained steady for the period

  8. Effect of concentration of Er3+ ions on ultra-large index of refraction via atomic coherence in Er3+: YAG crystal

    Institute of Scientific and Technical Information of China (English)

    张惠芳; 戴振文; 张冰; 吴金辉; 高锦岳

    2003-01-01

    A four-level system is proposed to produce large index of refraction accompanied by vanishing absorption in the Er3+-doped yttrium aluminium garnet(YAG)crystal.It is found that the high index of refraction with zero absorption can be provided by adjusting the incoherent pumping,the coherent field,as well as the concentration of Er3+ ions in the crystal.Furthermore,the value of the incoherent pump to achieve the high index of refraction with zero absorption is greatly changed with increasing the concentration of Er3+ ions in the crystal.This indicates that the effect of concentration on the high index of refraction with zero absorption cannot be neglected.

  9. Measurement of optical penetration depth and refractive index of human tissue

    Institute of Scientific and Technical Information of China (English)

    Shusen Xie(谢树森); Hui Li(李晖); Buhong Li(李步洪)

    2003-01-01

    Experimental techniques for measurement of optical penetration depth and refractive index of human tissue are presented, respectively. Optical penetration depth can be obtained from the measurement of the relative fluence-depth distribution inside the target tissue. The depth of normal and carcinomatous human lung tissues irradiated with the wavelengths of 406.7, 632.8 and 674.4 nm in vitro are respectively determined. In addition, a novel simple method based on total internal reflection for measuring the refractive index of biotissue in vivo is developed, and the refractive indices of skin from people of different age, sex and skin color are measured. Their refractive indices are almost same and the average is 1.533.

  10. Topology of relativistic refractive index surfaces for electron cyclotron waves

    International Nuclear Information System (INIS)

    The dispersion of electron cyclotron waves in a weakly relativistic Maxwellian plasma is investigated. It is shown that the apparently very complicated picture of the coupling of the extraordinary (X) mode to Bernstein waves can be accounted for in a simple way by considering the refractive indices as Riemann-like surfaces in the Clemmow-Mullaly-Allis (CMA) parameter space, (ωp2/ω2, ωc/ω), and by introducing a few topological concepts from the analysis of complex functions. A detailed study is made of the surface representing the X mode for perpendicular propagation, with special attention given to the connection between this mode and Gross-Bernstein modes. For perpendicular propagation non-transcendental approximations to the relativistic refractive indices for X and O modes can be given. We show that these approximations are good up to ∼ 25 keV and, at frequencies up to the second harmonic of the electron cyclotron frequency, the X mode approximation also accounts correctly for the connection of the X mode to Bernstein modes. The accuracy and the numerical efficiency of the approximations make them well suited for routine calculations for millimetre wave applications in fusion plasmas, including the analysis of X mode and O mode reflectometry. (author)

  11. Three-Dimensional Holographic Refractive-Index Measurement of Continuously Flowing Cells in a Microfluidic Channel

    Science.gov (United States)

    Sung, Yongjin; Lue, Niyom; Hamza, Bashar; Martel, Joseph; Irimia, Daniel; Dasari, Ramachandra R.; Choi, Wonshik; Yaqoob, Zahid; So, Peter

    2014-02-01

    The refractive index of biological specimens is a source of intrinsic contrast that can be explored without any concerns of photobleaching or harmful effects caused by extra contrast agents. In addition, the refractive index contains rich information related to the metabolism of cells at the cellular and subcellular levels. Here, we report a no-moving-parts approach that provides three-dimensional refractive-index maps of biological samples continuously flowing in a microfluidic channel. Specifically, we use line illumination and off-axis digital holography to record the angular spectra of light scattered from flowing samples at high speed. Applying the scalar diffraction theory, we obtain accurate refractive-index maps of the samples from the measured spectra. Using this method, we demonstrate label-free three-dimensional imaging of live RKO human colon cancer cells and RPMI8226 multiple myeloma cells, and obtain the volume, dry mass, and density of these cells from the measured three-dimensional refractive-index maps. Our results show that the reported method, alone or in combination with the existing flow cytometry techniques, shows promise as a quantitative tool for stain-free characterization of a large number of cells.

  12. Determination of Diameter and Index of Refraction of Textile Fibers by Laser Backscattering

    International Nuclear Information System (INIS)

    A new method was developed to determine both diameters and indices of refraction and hence the birefringence of cylindrical textile and industrial fibers and bundles by measuring intensity patterns of the scattered light over an interval of scattering angles. The measured intensity patterns are compared with theoretical predictions (Mie theory) to determine fiber diameter and index of refraction. It is shown that the method is simple and accurate and may be useful as an on-line, noncontact diagnostic tool in real time

  13. Volumetric properties, viscosity and refractive index of the protic ionic liquid, pyrrolidinium octanoate, in molecular solvents

    OpenAIRE

    Anouti, M.; Vigeant, A.; Johan JACQUEMIN; Brigouleix, C.; Lemordant, D.

    2010-01-01

    Densities ([rho]) and viscosities ([eta]) of binary mixtures containing the Protic Ionic Liquid (PIL), pyrrolidinium octanoate with five molecular solvents: water, methanol, ethanol, n-butanol, and acetonitrile are determined at the atmospheric pressure as a function of the temperature and within the whole composition range. The refractive index of all mixtures (nD) is measured at 298.15†K. The excess molar volumes VE and deviation from additivity rules of viscosities [eta]E and refractive in...

  14. High-accuracy correction of air refractive index by using two-color heterodyne interferometry of optical frequency combs

    International Nuclear Information System (INIS)

    High-accuracy two-color heterodyne interferometry based on fundamental and second harmonic of frequency combs for air refractive index correction is developed. A monitor interferometer as well as a probe interferometer is constructed to compensate the phase noises and drifts, which are caused by introducing the acousto-optic modulators for heterodyne interferometer, to realize high-accuracy measurement of optical distance. A relative stability of 10−10 to the total length for 500 s is achieved in the measurement of an optical path length difference between two wavelengths. In long-term measurements, the interferometric measurement results and the calculations from empirical equation of air refractive indices are in good agreement with a standard deviation of 4.1 × 10−10 throughout the 10 h period. By applying the two-color method, high-accuracy correction of air refractive index with an uncertainty of 8.9 × 10−8 is achieved during 10 h continuous measurements while the total refractive index changes with a range of 2.0 × 10−6. (paper)

  15. Matching-index-of-refraction of transparent 3D printing models for flow visualization

    International Nuclear Information System (INIS)

    Matching-index-of-refraction (MIR) has been used for obtaining high-quality flow visualization data for the fundamental nuclear thermal-hydraulic researches. By this method, distortions of the optical measurements such as PIV and LDV have been successfully minimized using various combinations of the model materials and the working fluids. This study investigated a novel 3D printing technology for manufacturing models and an oil-based working fluid for matching the refractive indices. Transparent test samples were fabricated by various rapid prototyping methods including selective layer sintering (SLS), stereolithography (SLA), and vacuum casting. As a result, the SLA direct 3D printing was evaluated to be the most suitable for flow visualization considering manufacturability, transparency, and refractive index. In order to match the refractive indices of the 3D printing models, a working fluid was developed based on the mixture of herb essential oils, which exhibit high refractive index, high transparency, high density, low viscosity, low toxicity, and low price. The refractive index and viscosity of the working fluid range 1.453–1.555 and 2.37–6.94 cP, respectively. In order to validate the MIR method, a simple test using a twisted prism made by the SLA technique and the oil mixture (anise and light mineral oil) was conducted. The experimental results show that the MIR can be successfully achieved at the refractive index of 1.51, and the proposed MIR method is expected to be widely used for flow visualization studies and CFD validation for the nuclear thermal-hydraulic researches

  16. Matching-index-of-refraction of transparent 3D printing models for flow visualization

    Energy Technology Data Exchange (ETDEWEB)

    Song, Min Seop; Choi, Hae Yoon; Seong, Jee Hyun; Kim, Eung Soo, E-mail: kes7741@snu.ac.kr

    2015-04-01

    Matching-index-of-refraction (MIR) has been used for obtaining high-quality flow visualization data for the fundamental nuclear thermal-hydraulic researches. By this method, distortions of the optical measurements such as PIV and LDV have been successfully minimized using various combinations of the model materials and the working fluids. This study investigated a novel 3D printing technology for manufacturing models and an oil-based working fluid for matching the refractive indices. Transparent test samples were fabricated by various rapid prototyping methods including selective layer sintering (SLS), stereolithography (SLA), and vacuum casting. As a result, the SLA direct 3D printing was evaluated to be the most suitable for flow visualization considering manufacturability, transparency, and refractive index. In order to match the refractive indices of the 3D printing models, a working fluid was developed based on the mixture of herb essential oils, which exhibit high refractive index, high transparency, high density, low viscosity, low toxicity, and low price. The refractive index and viscosity of the working fluid range 1.453–1.555 and 2.37–6.94 cP, respectively. In order to validate the MIR method, a simple test using a twisted prism made by the SLA technique and the oil mixture (anise and light mineral oil) was conducted. The experimental results show that the MIR can be successfully achieved at the refractive index of 1.51, and the proposed MIR method is expected to be widely used for flow visualization studies and CFD validation for the nuclear thermal-hydraulic researches.

  17. Tunable effective nonlinear refractive index of graphene dispersions during the distortion of spatial self-phase modulation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Gaozhong; Zhang, Saifeng, E-mail: sfzhang@siom.ac.cn, E-mail: jwang@siom.ac.cn; Cheng, Xin; Dong, Ningning; Zhang, Long; Wang, Jun, E-mail: sfzhang@siom.ac.cn, E-mail: jwang@siom.ac.cn [Key Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Umran, Fadhil A. [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Institute of Laser for Post Graduate Studies, Baghdad University, Baghdad (Iraq); Coghlan, Darragh; Blau, Werner J. [Key Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); School of Physics and the Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin 2 (Ireland); Cheng, Ya [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)

    2014-04-07

    Spatial self-phase modulation (SSPM) was observed directly when a focused He-Ne laser beam at 633 nm went through liquid-phase-exfoliated graphene dispersions. The diffraction pattern of SSPM was found to be distorted rapidly right after the incident beam horizontally passing through the dispersions, while no distortion for the vertically incident geometry. We show that the distortion is originated mainly from the non-axis-symmetrical thermal convections of the graphene nanosheets induced by laser heating, and the relative change of nonlinear refractive index can be determined by the ratio of the distortion angle to the half-cone angle. Therefore, the effective nonlinear refractive index of graphene dispersions can be tuned by changing the incident intensity and the temperature of the dispersions.

  18. Tunable effective nonlinear refractive index of graphene dispersions during the distortion of spatial self-phase modulation

    International Nuclear Information System (INIS)

    Spatial self-phase modulation (SSPM) was observed directly when a focused He-Ne laser beam at 633 nm went through liquid-phase-exfoliated graphene dispersions. The diffraction pattern of SSPM was found to be distorted rapidly right after the incident beam horizontally passing through the dispersions, while no distortion for the vertically incident geometry. We show that the distortion is originated mainly from the non-axis-symmetrical thermal convections of the graphene nanosheets induced by laser heating, and the relative change of nonlinear refractive index can be determined by the ratio of the distortion angle to the half-cone angle. Therefore, the effective nonlinear refractive index of graphene dispersions can be tuned by changing the incident intensity and the temperature of the dispersions

  19. Simultaneous retrieval of the complex refractive index and particle size distribution.

    Science.gov (United States)

    Ren, Yatao; Qi, Hong; Chen, Qin; Ruan, Liming; Tan, Heping

    2015-07-27

    A secondary optimization technique is proposed that allows the complex refractive index and particle size distribution (PSD) to be retrieved simultaneously by using the diffuse transmittance (T), diffuse reflectance (R), and collimated transmittance (T(c)) of a 1-D spherical particle systems as measured values. In the proposed method, two 1-D experimental samples of different thicknesses were exposed to continuous wave lasers of two different wavelengths. First, T, R, and T(c) were calculated by solving the radiative transfer equation. Then, the complex refractive index and PSDs were retrieved simultaneously by applying the inversion technique, quantum particle swarm optimization. However, the estimated results of the PSDs proved to be inaccurate. Hence, a secondary optimization was performed to improve the accuracy of the PSDs on the basis of the first optimization process. The results showed that the proposed technique can estimate the complex refractive index and particle size distribution accurately. PMID:26367593

  20. Broadband giant-refractive-index material based on mesoscopic space-filling curves.

    Science.gov (United States)

    Chang, Taeyong; Kim, Jong Uk; Kang, Seung Kyu; Kim, Hyowook; Kim, Do Kyung; Lee, Yong-Hee; Shin, Jonghwa

    2016-01-01

    The refractive index is the fundamental property of all optical materials and dictates Snell's law, propagation speed, wavelength, diffraction, energy density, absorption and emission of light in materials. Experimentally realized broadband refractive indices remain media. Herein, we demonstrate a measured index >1,800 resulting from a mesoscopic crystal with a dielectric constant greater than three million. This gigantic enhancement effect originates from the space-filling curve concept from mathematics. The principle is inherently very broad band, the enhancement being nearly constant from zero up to the frequency of interest. This broadband giant-refractive-index medium promises not only enhanced resolution in imaging and raised fundamental absorption limits in solar energy devices, but also compact, power-efficient components for optical communication and increased performance in many other applications. PMID:27573337

  1. Plasma-enhanced growth, composition, and refractive index of silicon oxy-nitride films

    DEFF Research Database (Denmark)

    Mattsson, Kent Erik

    1995-01-01

    material is in a state of internal tension. The viscoelastic relaxation process for temperatures above 700 °C is dominated by the relaxation of this internal tension. A linear relation between the refractive index and material density is determined for silicon oxy-nitride with a nitrogen concentration......Secondary ion mass spectrometry and refractive index measurements have been carried out on silicon oxy-nitride produced by plasma-enhanced chemical vapor deposition (PECVD). Nitrous oxide and ammonia were added to a constant flow of 2% silane in nitrogen, to produce oxy-nitride films with atomic...... nitrogen concentrations between 2 and 10 at. %. A simple atomic valence model is found to describe both the measured atomic concentrations and published material compositions for silicon oxy-nitride produced by PECVD. A relation between the Si–N bond concentration and the refractive index is found. This...

  2. Spectral dependence of the refractive index of single-crystalline GaAs for optical applications

    Energy Technology Data Exchange (ETDEWEB)

    Plotnichenko, V G; Nazaryants, V O; Kryukova, E B; Dianov, E M, E-mail: victor@fo.gpi.ac.r [Fibre Optics Research Center of the Russian Academy of Sciences, 38 Vavilov Street, Moscow 119333 (Russian Federation)

    2010-03-17

    The refractive index of crystalline GaAs is measured by the method of interference refractometry in the wavenumber range from 10 500 to 540 cm{sup -1} (or the wavelength range from 0.9 to 18.6 {mu}m) with a resolution of 0.1 cm{sup -1}. The measurement results are approximated by the generalized Cauchy dispersion formula of the 8th power. Spectral wavelength dependences of the first- and second-order derivatives of the refractive index are calculated, and the zero material dispersion wavelength is found to be {lambda}{sub 0} = 6.61 {mu}m. Using three GaAs plates of different thicknesses we managed to raise the refractive index measurement accuracy up to 4 x 10{sup -4} or 0.02%, being nearly by an order of magnitude better than the data available.

  3. Suppression of Air Refractive Index Variations in High-Resolution Interferometry

    Directory of Open Access Journals (Sweden)

    Zdeněk Buchta

    2011-08-01

    Full Text Available The influence of the refractive index of air has proven to be a major problem on the road to improvement of the uncertainty in interferometric displacement measurements. We propose an approach with two counter-measuring interferometers acting as a combination of tracking refractometer and a displacement interferometer referencing the wavelength of the laser source to a mechanical standard made of a material with ultra-low thermal expansion. This technique combines length measurement within a specified range with measurement of the refractive index fluctuations in one axis. Errors caused by different position of the interferometer laser beam and air sensors are thus eliminated. The method has been experimentally tested in comparison with the indirect measurement of the refractive index of air in a thermal controlled environment. Over a 1 K temperature range an agreement on the level of 5 × 10−8 has been achieved.

  4. Emittance of a finite scattering medium with refractive index greater than unity

    International Nuclear Information System (INIS)

    Refractive index and scattering can significantly influence the transfer of radiation in a semitransparent medium such as water, glass, plastics, or ceramics. In a recent article (1979), the author presented exact numerical results for the emittance of a semiinfinite scattering medium with a refractive index greater than unity. The present investigation extends the analysis to a finite medium. The physical situation consists of a finite planar layer. The isothermal layer emits, absorbs, and isotropically scatters thermal radiation. It is characterized by single scattering albedo, optical thickness, refractive index, and temperature. A formula for the directional emittance is derived, the directional emittance being the emittance of the medium multiplied by the interface transmittance. The ratio of hemispherical to normal emittance is tabulated and discussed

  5. Refractive index dispersion sensing using an array of photonic crystal resonant reflectors

    International Nuclear Information System (INIS)

    Refractive index sensing plays a key role in various environmental and biological sensing applications. Here, a method is presented for measuring the absolute refractive index dispersion of liquids using an array of photonic crystal resonant reflectors of varying periods. It is shown that by covering the array with a sample liquid and measuring the resonance wavelength associated with transverse electric polarized quasi guided modes as a function of period, the refractive index dispersion of the liquid can be accurately obtained using an analytical expression. This method is compact, can perform measurements at arbitrary number of wavelengths, and requires only a minute sample volume. The ability to sense a material's dispersion profile offers an added dimension of information that may be of benefit to optofluidic lab-on-a-chip applications

  6. Refractive index dispersion sensing using an array of photonic crystal resonant reflectors

    Energy Technology Data Exchange (ETDEWEB)

    Hermannsson, Pétur G.; Vannahme, Christoph; Smith, Cameron L. C.; Sørensen, Kristian T.; Kristensen, Anders, E-mail: anders.kristensen@nanotech.dtu.dk [Department of Micro- and Nanotechnology, Technical University of Denmark, Ørsteds Plads, Building 345E, DK-2800 Kgs. Lyngby (Denmark)

    2015-08-10

    Refractive index sensing plays a key role in various environmental and biological sensing applications. Here, a method is presented for measuring the absolute refractive index dispersion of liquids using an array of photonic crystal resonant reflectors of varying periods. It is shown that by covering the array with a sample liquid and measuring the resonance wavelength associated with transverse electric polarized quasi guided modes as a function of period, the refractive index dispersion of the liquid can be accurately obtained using an analytical expression. This method is compact, can perform measurements at arbitrary number of wavelengths, and requires only a minute sample volume. The ability to sense a material's dispersion profile offers an added dimension of information that may be of benefit to optofluidic lab-on-a-chip applications.

  7. Refractive index modulating Raman spectroscopy based on perovskite PMN-PT ceramics.

    Science.gov (United States)

    Wei, Danzhu; Xu, Tian; Yuan, Li; Tian, Shu; Fang, Jinghuai; Jin, Yonglong; Wang, Chaonan; Ma, Xinxiang; Shi, Jianzhen

    2016-04-01

    A three-layer planar waveguide structure comprising a perovskite (1-x)Pb(Mg1/3Nb2/3Nb2/3)O3-xPbTiO3 (PMN-PT) ceramic sandwiched by two silver films is designed and called PMPW. Using the high sensitivity of ultrahigh-order modes, theoretical analysis is performed to calculate the effective refractive index (ERI) of the PMPW. A detailed analysis of the Raman spectrum of PMN-PT at 795  cm-1 is performed. A comparison of the numerical analysis and experimental results reveals that the nonlinear change in ERI plays a primary role in the Raman signal variation. Analysis of the Raman spectrum of a sample deposited on PMPW confirms that it is effective for modulating Raman signals. PMID:27139681

  8. Posterior corneal curvature changes following Refractive Small Incision Lenticule Extraction

    OpenAIRE

    Ganesh, Sri

    2015-01-01

    Sri Ganesh, Utsav Patel, Sheetal Brar Phaco and Refractive Surgery Department, Nethradhama Superspeciality Eye Hospital, Bengaluru, Karnataka, India Purpose: To compare the posterior corneal curvature changes, in terms of corneal power and asphercity, following Refractive Small Incision Lenticule Extraction (ReLEx SMILE) procedure for low, moderate, and high myopia.Methods: This retrospective, non randomized, comparative, interventional trial; included 52 eyes of 26 patients, divided in thr...

  9. High-refractive-index fluids for the next-generation ArF immersion lithography

    Science.gov (United States)

    Wang, Yong; Miyamatsu, Takashi; Furukawa, Taiichi; Yamada, Kinji; Tominaga, Tetsuo; Makita, Yutaka; Nakagawa, Hiroki; Nakamura, Atsushi; Shima, Motoyuki; Kusumoto, Shiro; Shimokawa, Tsutomu; Hieda, Katsuhiko

    2006-03-01

    ArF immersion lithography using a high-refractive-index fluid (HIF) is considered to be a promising candidate for the 32nm node or below. At SPIE 2005 we introduced a new immersion fluid, JSR HIL-1, which has a refractive index and transmittance of 1.64 and >98%/mm (193.4nm, 23 °C), respectively. With HIL-1 immersion and a two beam interferometric exposure tool, hp32nm L/S imaging has been demonstrated. In this paper, we will report another novel immersion fluid, HIL-2, which has a transmittance of >99%/mm, which is almost as high as that of water, and a refractive index of 1.65 (193.4nm, 23 °C). Furthermore, an ArF laser irradiation study has shown that the degree of photodecomposition for both HIL-1 and HIL-2 is small enough for immersion lithography application. A "fluid puddle" defect study confirmed that HILs have less tendency to form immersion-specific photoresist defects and the refractive indices of HILs were found constant under laser irradiation. Batch-to-batch variation in refractive index during manufacture of HILs was not observed. By refining prism designs, hp30nm L/S patterns have also been successfully imaged with two interferometric exposure tools and HIL immersion.

  10. Estimation of volcanic ash refractive index from satellite infrared sounder data

    Science.gov (United States)

    Ishimoto, H.; Masuda, K.

    2014-12-01

    The properties of volcanic ash clouds (cloud height, optical depth, and effective radius of the particles) are planned to estimate from the data of the next Japanese geostationary meteorological satellite, Himawari 8/9. The volcanic ash algorithms, such as those proposed by NOAA/NESDIS and by EUMETSAT, are based on the infrared absorption properties of the ash particles, and the refractive index of a typical volcanic rock (i.e. andesite) has been used in the forward radiative transfer calculations. Because of a variety of the absorption properties for real volcanic ash particles at infrared wavelengths (9-13 micron), a large retrieval error may occur if the refractive index of the observed ash particles was different from that assumed in the retrieval algorithm. Satellite infrared sounder provides spectral information for the volcanic ash clouds. If we can estimate the refractive index of the ash particles from the infrared sounder data, a dataset of the optical properties for similar rock type of the volcanic ash can be prepared for the ash retrieval algorithms of geostationary/polar-orbiting satellites in advance. Furthermore, the estimated refractive index can be used for a diagnostic and a correction of the ash particle model in the retrieval algorithm within a period of the volcanic activities. In this work, optimal estimation of the volcanic ash parameters was conducted through the radiative transfer calculations for the window channels of the atmospheric infrared sounder (AIRS). The estimated refractive indices are proposed for the volcanic ash particles of some eruption events.

  11. Negative refractive index, perfect lenses and checkerboards: Trapping and imaging effects in folded optical spaces

    Science.gov (United States)

    Guenneau, Sébastien; Ramakrishna, S. Anantha

    2009-06-01

    Newly discovered metamaterials have opened new vistas for better control of light via negative refraction, whereby light refracts in the "wrong" manner. These are dielectric and metallic composite materials structured at subwavelength lengthscales. Their building blocks consist of local resonators such as conducting thin bars and split rings driving the material parameters such as the dielectric permittivity and magnetic permeability to negative (complex) values. Combined together, these structural elements can bring about a (complex valued) negative effective refractive index for the Snell-Descartes law and result in negative refraction of radiation. Negative refractive index materials can support a host of surface plasmon states for both polarizations of light. This makes possible unique effects such as imaging with subwavelength image resolution through the Pendry-Veselago slab lens. Other geometries have also been investigated, such as cylindrical or spherical lenses that enable a magnification of images with subwavelength resolution. Superlenses of three-fold (equilateral triangle), four-fold (square) and six-fold (hexagonal) geometry allow for multiple images, respectively two, three, and five. Generalization to rectangular and triangular checkerboards consisting of alternating cells of positive and negative refractive index represents a very singular situation in which the density of modes diverges at the corners, with an infinity of images. Sine-cosecant anisotropic heterogeneous square and triangular checkerboards can be respectively mapped onto three-dimensional cubic and icosahedral corner lenses consisting of alternating positive and negative refractive regions. All such systems with corners between negative and positive refractive media display very singular behavior with the local density of states becoming infinitely large at the corner, in the limit of no dissipation. We investigate all of these, using the unifying viewpoint of transformation optics

  12. Infrared complex refractive index of astrophysical ices exposed to cosmic rays simulated in the laboratory

    CERN Document Server

    Rocha, W R M; de Barros, A L F; Andrade, D P P; Rothard, H; Boduch, P

    2016-01-01

    In dense and cold regions of the interstellar medium (ISM), molecules may be adsorbed onto dust grains to form the ice mantles. Once formed, they can be processed by ionizing radiation coming from stellar or interstellar medium leading to formation of several new molecules in the ice. Among the different kind of ionizing radiation, cosmic rays play an important role in the solid-phase chemistry because of the large amount of energy deposited in the ices. The physicochemical changes induced by the energetic processing of astrophysical ices are recorded in a intrinsic parameter of the matter called complex refractive index (CRI). In this paper, we present for the first time a catalogue containing 39 complex refractive indices (n, k) in the infrared from 2.0 - 16.6 micrometer for 13 different water-containing ices processed in laboratory by cosmic ray analogs. The calculation was done by using the NKABS (acronym of determination of N and K from ABSorbance data) code, which employs the Lambert-Beer and Kramers-Kr...

  13. Refractive index detection range adjustable liquid-core fiber optic sensor based on surface plasmon resonance and a nano-porous silica coating

    Science.gov (United States)

    Chen, Yuzhi; Li, Xuejin; Zhou, Huasheng; Hong, Xueming; Geng, Youfu

    2016-09-01

    A liquid-core fiber optic surface plasmon resonance sensor with an adjustable nano-porous silica coating is first presented in this paper. By adjusting the refractive index of the nano-porous silica coating, the sensor can be used in different refractive index detection ranges. A low refractive index interval of 1.33–1.34 and a high refractive index interval of 1.42–1.44 are taken as examples to be investigated. Results show that our sensor works well in these two intervals by using appropriate nano-porous silica coatings. The highest sensitivities of the low and high refractive index intervals are obtained to be 5840 nm/RIU and 5120 nm/RIU, respectively. In addition, the sensing performances and the working wavelengths can be adjusted to meet different working requirements by changing the refractive index of the nano-porous silica coating. We also take the single mode incidence cases to explain the effects of different single incident light modes on the sensing performances.

  14. Pterygium-induced corneal refractive changes

    OpenAIRE

    Maheshwari Sejal

    2007-01-01

    To study the effect of pterygium on corneal topography, a retrospective analysis of 151 eyes with primary pterygia was done. All cases underwent videokeratography preoperatively and one month postoperatively. Statistical analysis of average corneal power (ACP), corneal astigmatism, surface regularity index (SRI) and surface asymmetry index (SAI) was done before and one month after surgery. Topographic indices were compared statistically for various grades of pterygia. Increase in the grade of...

  15. A three-dimensional negative refractive index medium operated at multiple-angle incidences

    Science.gov (United States)

    Yeh, Ting-Tzuo; Yen, Ta-Jen

    2010-08-01

    We present a negative refractive index medium (NRIM) operating at multiple-angle incidences by expanding a conventional planar metamaterial to a three-dimensional (3D) structure. The proposed 3D NRIM is comprised of semi-spherical metal shells and planar plamonic wires, thus giving rise to negative magnetic permeability and negative electric permittivity, respectively. Our results show that reflectance (transmittance) peaks slightly which locate the region of negative refraction index are insensitive to the incident angles from 0° to 45° and the polarization of the excitation wave at a certain range of frequencies. Such pseudo-isotropic NRIM may be exploited for superlens and antenna applications.

  16. Relationship between Compostion,Density and Refractive Index for Heavy Metal Fluoride Glasses

    Institute of Scientific and Technical Information of China (English)

    ShaukatS.F; HobsonP.R.; 等

    2001-01-01

    The density and the refractive index for various compositions of heavy metal fluoride(HMF) glasses,used to make low-loss optical wave-guides,have been measured by standard archimedes method and by using as Pulfrich refrctometer respectively.The density as a function of composition is calculated considering the effective volume of the ions contained in the glass to be invariant.The refractive index as a function of composition is also calcuated.based on the Lorenz-Lorentz equation,by computing the electronic polarizability of HMF glasses.All calculated results are in good agreement with the observed data.

  17. "Peak-tracking chip" (PTC) for bulk refractive index sensing and bioarray sensing

    KAUST Repository

    Bougot-Robin, Kristelle

    2013-10-20

    Resonant techniques are of wide interest to detect variation of effective refractive index at a chip surface. Both Surface Plasmon Resonance (SPR) and dielectric resonant waveguide (RWGs) can be exploited. Through their design, RWGs allow more flexibility (size of the biomolecule to detect, detection angle…). Using specially designed RWG “Peak-tracking chip”, we propose to use spatial information from a simple monochromatic picture as a new label-free bioarray technique. We discuss robustness, sensitivity, multiplex detection, fluidic integration of the technique and illustrate it through bulk refractive index sensing as well as specific recognition of DNA fragment from gyrase A.

  18. Three-dimensional negative index of refraction at optical frequencies by coupling plasmonic waveguides.

    Science.gov (United States)

    Verhagen, Ewold; de Waele, René; Kuipers, L; Polman, Albert

    2010-11-26

    We identify a route towards achieving a negative index of refraction at optical frequencies based on coupling between plasmonic waveguides that support backwards waves. We show how modal symmetry can be exploited in metal-dielectric waveguide pairs to achieve negative refraction of both phase and energy. Control of waveguide coupling yields a metamaterial consisting of a one-dimensional multilayer stack that exhibits an isotropic index of -1 at a free-space wavelength of 400 nm. The concepts developed here may inspire new low-loss metamaterial designs operating close to the metal plasma frequency. PMID:21231386

  19. Three-dimensional negative index of refraction at optical frequencies by coupling plasmonic waveguides

    CERN Document Server

    Verhagen, Ewold; L.,; Kuipers,; Polman, Albert

    2010-01-01

    We identify a route towards achieving a negative index of refraction at optical frequencies based on coupling between plasmonic waveguides that support backwards waves. We show how modal symmetry can be exploited in metal-dielectric waveguide pairs to achieve negative refraction of both phase and energy. By properly controlling coupling between adjacent waveguides, a metamaterial consisting of a one-dimensional multilayer stack exhibiting an isotropic index of -1 can be achieved at a free-space wavelength of 400 nm. The general concepts developed here may inspire new low-loss metamaterial designs operating close to the metal plasma frequency.

  20. Three-Dimensional Negative Index of Refraction at Optical Frequencies by Coupling Plasmonic Waveguides

    Science.gov (United States)

    Verhagen, Ewold; de Waele, René; Kuipers, L.; Polman, Albert

    2010-11-01

    We identify a route towards achieving a negative index of refraction at optical frequencies based on coupling between plasmonic waveguides that support backwards waves. We show how modal symmetry can be exploited in metal-dielectric waveguide pairs to achieve negative refraction of both phase and energy. Control of waveguide coupling yields a metamaterial consisting of a one-dimensional multilayer stack that exhibits an isotropic index of -1 at a free-space wavelength of 400 nm. The concepts developed here may inspire new low-loss metamaterial designs operating close to the metal plasma frequency.

  1. Observation of a multiply ionized plasma with index of refraction greater than one

    Energy Technology Data Exchange (ETDEWEB)

    Filevich, J; Rocca, J J; Marconi, M C; Moon, S J; Nilsen, J; Scofield, J H; Dunn, J; Smith, R F; Keenan, R; Hunter, J R; Shlyaptsev, V N

    2004-10-14

    We present clear experimental evidence showing that the contribution of bound electrons can dominate the index of refraction of laser created plasmas at soft x-ray wavelengths. We report anomalous fringe shifts in soft x-ray laser interferograms of Al laser-created plasmas. The comparison of measured and simulated interferograms show that this results from the dominant contribution of low charge ions to the index of refraction. This usually neglected bound electron contribution can a.ect the propagation of soft x-ray radiation in plasmas and the interferometric diagnostics of plasmas for many elements.

  2. Time-resolved measurement of the refractive index for photopolymerization processes

    International Nuclear Information System (INIS)

    A double-interferometer technique is employed to examine the dynamics of a photopolymerization process. The dye molecule is eosine Y. The refractive index and the thickness of the photopolymerizable film are measured as a function of time. During the photopolymerization process, the first quantity increases by 2%, while the second quantity decreases by more than 4%. Therefore, the refractive index cannot be measured by means of single-interferometer techniques. By fitting our experimental curves to a rate equation, the quantum yield and the absorption coefficient of the sample can be determined with good accuracy

  3. Effect of Solvent on Nonlinear Refractive Index of 2-(2‧-HYDROXYPHENYL) Benzoxazole

    Science.gov (United States)

    ZHANG, GUILAN; XIONG, FEIBING; ZHANG, BAO; TANG, GUOQING; CHEN, WENJU; WANG, LIANYING; BAI, YUBAI

    Nonlinear refractive indexes n2 of 2-(2‧-hydroxyphenyl) benzoxazole (HBO) in three species of solvent (cyclohexane, ethanol and dimethyl sulfoxide) have been determined by using the Z-scan technique. The experimental results show that the n2 of HBO is strongly dependent on the polarity of the solvent. Through the study on the absorption and fluorescence spectra of HBO in different solvents, we regard that the principal origin of the nonlinear refractive index of HBO is not the thermal effect because of absorption of incident light but the excited state intramolecular proton transfer of HBO under the incident light.

  4. Wavelength Sweep Interferometry for Measuring the Refractive Index and Physical Thickness

    Institute of Scientific and Technical Information of China (English)

    SONG Guiju; WANG Xiangzhao; FANG Zujie

    2001-01-01

    A method combining wavelength sweep interferometry with the Fourior transform technique to perform the separate measurements of the physical thickness and the refractive index is proposed. By converting the optical path difference of the interferometer to the beat frequency of the interference signal we realize the depth scanning without mechanical moving parts. The effect of specimen dispersion is avoided by using a narrow tuning laser diode. For demonstrating this method we measure the physical thickness and the refractive index of an x-cut LiNbO3, BK9 and BK7 glass, and the results consist with the reported values.

  5. Determination of the refractive index of glucose-ethanol-water mixtures using spectroscopic refractometry near the critical angle.

    Science.gov (United States)

    Sobral, H; Peña-Gomar, M

    2015-10-01

    A spectroscopic refractometer was used to investigate the dispersion curves of ethanol and D-glucose solutions in water near the critical angle; here, the reflectivity was measured using a white source. Dispersion curves were obtained in the 320-1000 nm wavelength range with a resolution better than 10(-4) for the refractive index, n. The differential refractive index is measured as a function of wavelength, and a simple expression is proposed to obtain the refractive index of the glucose-ethanol-water ternary system. Using this expression, combined with the experimental differential refractive index values, the concentrations of individual components can be calculated. PMID:26479623

  6. Effect of substrate index of refraction on the design of antireflection coatings

    Science.gov (United States)

    Willey, Ronald R.

    2011-09-01

    Formulae to estimate the average percent reflectance (Rave) of a broadband antireflection (AR) coating as a function of the bandwidth (B), the overall thickness (C), the index of refraction of the last layer (L), and the difference between the indices of the high- and low-index layers (D) were reported in 1991. Various refinements of these formulae and other insights into the underlying behavior of such coating designs have been reported up until the present time. Dobrowolski, et al.6 and Tikhonravov, et al.7 have also added independent viewpoints to this subject over this period. In the previous studies, the effects of the index of refraction of the substrate have mostly been ignored and have appeared to be very minor. This study has investigated the influence of the substrate index on the Rave results. It has been found that there seem to be two classes of designs with respect to the effect of substrate index. In the class of "step down" AR designs, there is a significant effect, in the other class, there is no significant effect. Even in the step-down case, there is no effect of substrate index if any and all indices of refraction for the coating materials are available from that of the index of the substrate to the index of the media.

  7. Generation of J_0-Bessel-Gauss beam by a heterogeneous refractive index map

    KAUST Repository

    San-Román-Alerigi, Damián P.

    2012-07-01

    In this paper, we present the theoretical studies of a refractive index map to implement a Gauss to a J0-Bessel-Gauss convertor. We theoretically demonstrate the viability of a device that could be fabricated on a Si/Si1-yOy/Si1-x-yGexCy platform or by photo-refractive media. The proposed device is 200 ?m in length and 25 ?m in width, and its refractive index varies in controllable steps across the light propagation and transversal directions. The computed conversion efficiency and loss are 90%, and -0.457 dB, respectively. The theoretical results, obtained from the beam conversion efficiency, self-regeneration, and propagation through an opaque obstruction, demonstrate that a two-dimensional (2D) graded index map of the refractive index can be used to transform a Gauss beam into a J0-Bessel-Gauss beam. To the best of our knowledge, this is the first demonstration of such beam transformation by means of a 2D index-mapping that is fully integrable in silicon photonics based planar lightwave circuits (PLCs). The concept device is significant for the eventual development of a new array of technologies, such as micro optical tweezers, optical traps, beam reshaping and nonlinear beam diode lasers. © 2012 Optical Society of America.

  8. Role of refractive-index gradient in spin Hall effect of light

    CERN Document Server

    Luo, Hailu; Shu, Weixing; Fan, Dianyuan

    2010-01-01

    In this paper, we try to identify the role of refractive-index gradient in spin Hall effect (SHE) of light from the viewpoint of classical electrodynamics. We demonstrate that the refractive index gradient can enhance or suppress the spin-to-orbital angular momentum conversion, and thus control the SHE of light. Under the limit of ultra-large refractive index gradient, the polarization-dependent transverse shift is found to tend to a saturation value. The polarization-dependent shift is governed by the spin-to-orbital angular momentum conversion, clearly clarifying the role of refractive index gradient in the SHE. We suggest that the ultra-low or ultra-high index metamaterial may become a viable candidate for amplifying the SHE of light, and by properly facilitating the spin-to-orbital angular momentum conversion the SHE may be enhanced dramatically. These findings provide an important pathway for controlling the SHE of light, and thereby open up the possibility for developing new nano-photonic devices.

  9. Phase-conjugate interferometer to estimate refractive index and thickness of transparent plane parallel plates

    Energy Technology Data Exchange (ETDEWEB)

    Pastrana-Sanchez, R.; Rodriguez-Zurita, G.; Vazquez-Castillo, J. F. [Benemerita Universidad Autonoma de Puebla, Puebla (Mexico)

    2001-04-01

    A technique to estimate the refractive index and thickness of homogeneous plane parallel dielectric plates is proposed using a phase-conjugate interferometer, in which counting of interference fringes is employed. The light beam impinges a tilted plate before it enters a phase-conjugate interferometer, and a count of the fringes passing through a given reference at the observing plane gives the phase changes as a function of tilting angle. The obtained data is fitted to a mathematical model, which leads to the determination of both refractive index and thickness simultaneously. In this letter, experimental data from two interferometers are also discussed for comparison. One with an externally-pumped phase-conjugate mirror achieved with a BSO photorefractive crystal and another one with conventional mirrors. Results show that the phase sensitivity of the phase-conjugate interferometer is not simply twice the corresponding sensitivity of the conventional version. [Spanish] Se propone una tecnica para medir indices de refraccion y espesores de placas dielectricas plano paralelas homogeneas empleando un interferometro con fase conjugada, en el cual se usa el conteo de franjas. El haz luminoso incide en una placa inclinada bajo inspeccion antes de entrar en un interferometro equipado con un espejo conjugador de fase, y se realiza un conteo de las franjas que pasan por determinada referencia en el plano de observacion, proporcionando los cambios de fase en funcion del angulo de inclinacion. Los datos obtenidos se ajustan a un modelo, el cual conduce a la determinacion, tanto del indice de refraccion como del espesor, simultaneamente. En este trabajo se discuten datos experimentales provenientes de dos interferometros para su comparacion. Uno de ellos tiene un espejo conjugador basado en un cristal BSO fotorrefractivo, mientras que el otro es una variante con espejos convencionales. Se muestra que la sensibilidad de fase del interferometro con conjugador de fase no

  10. Determining particle size distribution and refractive index in a two-layer tissue phantom by linearly polarized light

    Institute of Scientific and Technical Information of China (English)

    Yong Deng; Qiang Lu; Qingming Luo

    2006-01-01

    We report a new method for measuring particle size distribution (PSD) and refractive index of the top layer in a two-layer tissue phantom simulated epithelium tissue by varying the azimuth angle of incident linearly polarized light. The polarization gating technique is used to decouple the single and multiple scattering components in the returned signal. The theoretical model based on Mie theory is presented and a nonlinear inversion method - floating genetic algorithm - is applied to inverting the azimuth dependence of component of polarization light backscattered. The experiment results demonstrate that the size distribution and refractive index of the scatters of the top layer can be determined by measuring and analyzing the differential signal of the parallel and perpendicular components from a two-layer tissue phantom. The method implies to detect precancerous changes in human epithelial tissue.

  11. Refractive index and solubility control of para-cymene solutions for index-matched fluid-structure interaction studies

    Science.gov (United States)

    Fort, Charles; Fu, Christopher D.; Weichselbaum, Noah A.; Bardet, Philippe M.

    2015-12-01

    To deploy optical diagnostics such as particle image velocimetry or planar laser-induced fluorescence (PLIF) in complex geometries, it is beneficial to use index-matched facilities. A binary mixture of para-cymene and cinnamaldehyde provides a viable option for matching the refractive index of acrylic, a common material for scaled models and test sections. This fluid is particularly appropriate for large-scale facilities and when a low-density and low-viscosity fluid is sought, such as in fluid-structure interaction studies. This binary solution has relatively low kinematic viscosity and density; its use enables the experimentalist to select operating temperature and to increase fluorescence signal in PLIF experiments. Measurements of spectral and temperature dependence of refractive index, density, and kinematic viscosity are reported. The effect of the binary mixture on solubility control of Rhodamine 6G is also characterized.

  12. Atomic force microscopy for the determination of refractive index profiles of optical fibres and waveguides: a quantitative study

    International Nuclear Information System (INIS)

    The use of preferential etching and atomic force microscopy to measure refractive index profiles of optical fibres is investigated. Both the etch rate and the position of lateral features are shown to be independent of etch time. An elliptical core fibre has been studied and the resultant profile found to be in qualitative agreement with the preform index profile. It is shown, however, that the ellipticity of the core has changed during the drawing process. The method has been extended to fluorine and germanium doped planar waveguides and the results correlated with the fabrication process

  13. Generation of J0-Bessel-Gauss Beam by an heterogeneous refractive index map

    CERN Document Server

    Alerigi, Damian P San Roman; Benslimane, Ahmed; Zhang, Yaping; Alsunaidi, Mohammad; Ooi, Boon S; 10.1364/JOSAA.29.001252

    2012-01-01

    In this paper, we present the theoretical studies of a refractive index map to implement a Gauss to J0-Bessel-Gauss convertor. We theoretically demonstrate the viability of such device by solving the inverse electromagnetic problem. The computed conversion e?ficiency is 90%. The theoretical results, obtained from the beam conversion efi?ciency, self-regeneration, and propagation through an opaque obstruction; demonstrate that a 2D graded index map of the refractive index can be used to transform a Gauss beam into a J0-Bessel-Gauss beam. To the best of our knowledge, this is the ?rst demonstration of such beam transformation by means of a 2D index-mapping which is fully integrable in silicon photonics based planar lightwave circuits (PLC). The concept device is signi?cant for the eventual development of a new array of technologies, such as micro optical tweezers, optical traps, beam reshaping and non-linear beam diode lasers.

  14. The iterative self-consistent reaction-field method: The refractive index of pure water

    DEFF Research Database (Denmark)

    Sylvester-Hvid, Kristian O.; Mikkelsen, K. V.; Ratner, M.A.

    2011-01-01

    We present different microscopic models for describing electromagnetic properties of condensed phases and the models involve iterative self-consistent procedures for calculating the properties. We report calculations of the frequency-dependent refractive index of pure water. We investigate the...

  15. Quantifying the refractive index dispersion of a pigmented biological tissue using Jamin-Lebedeff interference microscopy

    NARCIS (Netherlands)

    Stavenga, Doekele G.; Leertouwer, Hein L.; Wilts, Bodo D.

    2013-01-01

    Jamin-Lebedeff polarizing interference microscopy is a classical method for determining the refractive index and thickness of transparent tissues. Here, we extend the application of this method to pigmented, absorbing biological tissues, based on a theoretical derivation using Jones calculus. This n

  16. Infrared refractive index of thin YBa2Cu3O7 superconducting films

    International Nuclear Information System (INIS)

    This work investigates whether thin-film optics with a constant refractive index can be applied to high-Tc superconducting thin films. The reflectance and transmittance of YBa2Cu3O7 films on LaAlO3 substrates are measured using a Fourier-transform infrared spectrometer at wavelengths from 1 to 100 μm at room temperature. The reflectance of these superconducting films at 10K in the wavelength region from 2.5 to 25 μm is measured using a cryogenic reflectance accessory. The film thickness varies from 10 to 200 nm. By modeling the frequency-dependent complex conductivity in the normal and superconducting states and applying electromagnetic-wave theory, the complex refractive index of YBa2Cu3O7 films is obtained with a fitting technique. It is found that a thickness-independent refractive index can be applied even to a 25nm film, and average values of the spectral refractive index for film thicknesses between 25 and 200 nm are recommended for engineering applications

  17. Research Advances in Detection Techniques of High Performance Liquid Chromatography-Refractive Index Detector

    Institute of Scientific and Technical Information of China (English)

    Huo; Fang; Zhang; Zhimei; Wang; Jianjun; Guo; Shijin; Zhou; Chunfeng; Fu; Shijun

    2014-01-01

    As a highly sensitive and stable detector,refractive index detector is usually used for quantitative detection of substances such as polymer,sugar and organic acid. The research reviewed the application of HPLC-RID in the fields of quantitative determination of medicine and food,in order to lay a foundation for wider use of RID.

  18. Calculation of the refractive index of metal on the basis of nonlocal potential theory

    Science.gov (United States)

    Chrzanowski, Janusz

    2008-12-01

    In this paper a quantative discussion upon the frequency dependence of the refractive index of metal, in wide range of frequency, is performed on the basis of nonlocal potential theory connected with the concept of quasiparticles. Obtained results, for chosen metals, have been compared to evidence.

  19. The spatial- time distribution of vertical gradient of refraction index of air in territory of Mongolia

    International Nuclear Information System (INIS)

    The results of calculation of the vertical gradient of refraction index of air in 2-300 m layer of troposphere by 3 year (1987-1989) data of 8 meteorological stations in the Mongolia is been showed. Year course and integral distribution of g of this stations are described. 4 figs, 2 tables. (J.U)

  20. Design and use of guided mode resonance filters for refractive index sensing

    DEFF Research Database (Denmark)

    Hermannsson, Pétur Gordon

    . The structures investigated in this thesis were fabricated in a process based on nanoreplication, in which the surface of a polymer was patterned with a structured master, cured with ultra-violet light and coated with a high refractive index material. The masters were defined using electron beam...

  1. Refractive index sensing with hyperbolic metamaterials: strategies for biosensing and nonlinearity enhancement.

    Science.gov (United States)

    Vasilantonakis, N; Wurtz, G A; Podolskiy, V A; Zayats, A V

    2015-06-01

    Metamaterials with hyperbolic dispersion based on metallic nanorod arrays provide a flexible platform for the design of bio- and chemical sensors and nonlinear devices, allowing the incorporation of functional materials into and onto the plasmonic metamaterial. Here, we have investigated, both analytically and numerically, the dependence of the optical response of these metamaterials on refractive index variations in commonly used experimental sensing configurations, including transmission, reflection, and total internal reflection. The strategy for maximising refractive index sensitivity for different configurations has been considered, taking into account contributions from the superstrate, embedding matrix, and the metal itself. It is shown that the sensitivity to the refractive index variations of the host medium is at least 2 orders of magnitude higher than to the ones originating from the superstrate. It is also shown that the refractive index sensitivity increases for higher-order unbound and leaky modes of the metamaterial sensor. The impact of the transducer's thickness was also analysed showing significant increase of the sensitivity for the thinner metamaterial layers (down to few 0.01 fraction of wavelength and, thus, requiring less analyte) as long as modes are supported by the structure. In certain configurations, both TE and TM-modes of the metamaterial transducer have comparable sensitivities. The results provide the basis for the design of new ultrasensitive chemical and biosensors outperforming both surface plasmon polaritons and localised surface plasmons based transducers. PMID:26072797

  2. Chiral metamaterials with negative refractive index based on four "U" split ring resonators

    OpenAIRE

    Li, Zhaofeng; Zhao, Rongkuo; Koschny, Thomas; Kafesaki, Maria; Alici, Kamil Boratay; Colak, Evrim; Caglayan, Humeyra; Soukoulis, Ekmel Ozbayand C. M.

    2010-01-01

    A uniaxial chiral metamaterial is constructed by double-layered four "U" split ring resonators mutually twisted by 90 degrees. It shows a giant optical activity and circular dichroism. The retrieval results reveal that a negative refractive index is realized for circularly polarized waves due to the large chirality. The experimental results are in good agreement with the numerical results.

  3. Reflection-based fibre-optic refractive index sensor using surface plasmon resonance

    Czech Academy of Sciences Publication Activity Database

    Hlubina, P.; Kadulová, M.; Ciprian, D.; Sobota, Jaroslav

    2014-01-01

    Roč. 9, August 19 (2014), 14033:1-5. ISSN 1990-2573 R&D Projects: GA MŠk(CZ) LO1212 Keywords : surface plasmon resonance * fibre-optic sensor * spectral interrogation technique * aqueous solutions of ethanol * refractive index Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.231, year: 2014

  4. Optical waveguides with compound multiperiodic grating nanostructures for refractive index sensing

    DEFF Research Database (Denmark)

    Neustock, Lars Thorben; Jahns, Sabrina; Adam, Jost;

    2016-01-01

    (Rudin-Shapiro, Fibonacci, Thue-Morse). The refractive index sensitivity of the TE-resonances is similar for all types of investigated nanostructures. For the TM-resonances the compound multiperiodic nanostructures exhibit higher sensitivity values compared to the monoperiodic nanostructure and similar...

  5. High-refractive index particles in counter-propagating optical tweezers - manipulation and forces

    NARCIS (Netherlands)

    Horst, Astrid van der

    2006-01-01

    With a tightly focused single laser beam, also called optical tweezers, particles of a few nanometers up to several micrometers in size can be trapped and manipulated in 3D. The size, shape and refractive index of such colloidal particles are of influence on the optical forces exerted on them in the

  6. Refractive index dispersion sensing using an array of photonic crystal resonant reflectors

    DEFF Research Database (Denmark)

    Hermannsson, Pétur Gordon; Vannahme, Christoph; Smith, Cameron;

    2015-01-01

    covering the array with a sample liquid and measuring the resonance wavelength associated with transverse electric polarized quasi guided modes as a function of period, the refractive index dispersion of the liquid can be accurately obtained using an analytical expression. This method is compact, can...

  7. Gouy shift correction for highly accurate refractive index retrieval in time-domain terahertz spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Kužel, Petr; Němec, Hynek; Kadlec, Filip; Kadlec, Christelle

    2010-01-01

    Roč. 18, č. 15 (2010), s. 15338-15348. ISSN 1094-4087 R&D Projects: GA ČR GC202/09/J045 Institutional research plan: CEZ:AV0Z10100520 Keywords : terahertz spectroscopy * Gouy phase shift * gaussian beams * refractive index Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.749, year: 2010

  8. Laplace-Gauss and Helmholtz-Gauss paraxial modes in media with quadratic refraction index.

    Science.gov (United States)

    Kiselev, Aleksei P; Plachenov, Alexandr B

    2016-04-01

    The scalar theory of paraxial wave propagation in an axisymmetric medium where the refraction index quadratically depends on transverse variables is addressed. Exact solutions of the corresponding parabolic equation are presented, generalizing the Laplace-Gauss and Helmholtz-Gauss modes earlier known for homogeneous media. Also, a generalization of a zero-order asymmetric Bessel-Gauss beam is given. PMID:27140777

  9. Observation of optical emission from high refractive index waveguide excited by traveling electron beam

    OpenAIRE

    Kuwamura, Yuji; Yamada, Minoru; Okamoto, Ryuichi; Kanai, Takeshi; Fares, Hesham

    2008-01-01

    A new scheme for optical emission using a high refractive index waveguide and the traveling electron beam in vacuum was demonstrated. Optical emission around wavelength of 1.5 pm was observed for electron acceleration voltage of 40KV. © 2008 Optical Society of America.

  10. Research of Refractive Index Impact on Dual Wavelenght FSO Link Attenuation

    Czech Academy of Sciences Publication Activity Database

    Pešek, J.; Fišer, Ondřej

    New York: IEEE, 2011 - (Pinker, J.), 1-3 ISBN 978-80-7043-987-6. ISSN 1803-7232. [International Conference on Applied Electronics . Pilsen (CZ), 07.09.2011-08.09.2011] Institutional research plan: CEZ:AV0Z30420517 Keywords : Structure index of atmosphere * refractive index * FSO link Attenuation Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering http://ieeexplore.ieee.org/xpl/articleDetails.jsp?reload=true&arnumber=6049120&contentType=Conference+Publications

  11. Surface Wave Cloak from Graded Refractive Index Nanocomposites.

    Science.gov (United States)

    La Spada, L; McManus, T M; Dyke, A; Haq, S; Zhang, L; Cheng, Q; Hao, Y

    2016-01-01

    Recently, a great deal of interest has been re-emerged on the possibility to manipulate surface waves, in particular, towards the THz and optical regime. Both concepts of Transformation Optics (TO) and metamaterials have been regarded as one of key enablers for such applications in applied electromagnetics. In this paper, we experimentally demonstrate for the first time a dielectric surface wave cloak from engineered gradient index materials to illustrate the possibility of using nanocomposites to control surface wave propagation through advanced additive manufacturing. The device is designed analytically and validated through numerical simulations and measurements, showing good agreement and performance as an effective surface wave cloak. The underlying design approach has much wider applications, which span from microwave to optics for the control of surface plasmon polaritons (SPPs) and radiation of nanoantennas. PMID:27416815

  12. Surface Wave Cloak from Graded Refractive Index Nanocomposites

    Science.gov (United States)

    La Spada, L.; McManus, T. M.; Dyke, A.; Haq, S.; Zhang, L.; Cheng, Q.; Hao, Y.

    2016-07-01

    Recently, a great deal of interest has been re-emerged on the possibility to manipulate surface waves, in particular, towards the THz and optical regime. Both concepts of Transformation Optics (TO) and metamaterials have been regarded as one of key enablers for such applications in applied electromagnetics. In this paper, we experimentally demonstrate for the first time a dielectric surface wave cloak from engineered gradient index materials to illustrate the possibility of using nanocomposites to control surface wave propagation through advanced additive manufacturing. The device is designed analytically and validated through numerical simulations and measurements, showing good agreement and performance as an effective surface wave cloak. The underlying design approach has much wider applications, which span from microwave to optics for the control of surface plasmon polaritons (SPPs) and radiation of nanoantennas.

  13. Omnidirectional Photonic Band Gap Using Low Refractive Index Contrast Materials and its Application in Optical Waveguides

    KAUST Repository

    Vidal Faez, Angelo

    2012-07-01

    Researchers have argued for many years that one of the conditions for omnidirectional reflection in a one-dimensional photonic crystal is a strong refractive index contrast between the two constituent dielectric materials. Using numerical simulations and the theory of Anderson localization of light, in this work we demonstrate that an omnidirectional band gap can indeed be created utilizing low refractive index contrast materials when they are arranged in a disordered manner. Moreover, the size of the omnidirectional band gap becomes a controllable parameter, which now depends on the number of layers and not only on the refractive index contrast of the system, as it is widely accepted. This achievement constitutes a major breakthrough in the field since it allows for the development of cheaper and more efficient technologies. Of particular interest is the case of high index contrast one-dimensional photonic crystal fibers, where the propagation losses are mainly due to increased optical scattering from sidewall roughness at the interfaces of high index contrast materials. By using low index contrast materials these losses can be reduced dramatically, while maintaining the confinement capability of the waveguide. This is just one of many applications that could be proven useful for this discovery.

  14. Optical device for sensing the index of refraction of liquids with high turbidity

    Science.gov (United States)

    Pena-Gomar, M.; Fajardo-Lira, C.; Rosete-Aguilar, Martha; Garcia-Valenzuela, Augusto

    2000-12-01

    We discuss the use of photo-reflectance near the critical angle (PRCA) to monitor small changes of the RI of highly turbid liquids. The theory of the reflectance of a laser beam near the critical angle for an external medium with a complex RI is summarized. The applicability of PRCA to sense highly turbid media is demonstrated experimentally on bovine milk samples. We give experimental results showing the temporal variation of the refractive index (RI) during three different processes in bovine milk: (1) Mechanical stirring, (2) temperature changes, and (3) pH variations around the isoelectric point of the casein micelles (micelle aggregation). RI changes in the order of a few times 1 X 10-3 are observed during the experiments. The experimental results show that the RI of milk can be used to track physico-chemical changes in time allowing one to measure the time constant of the different process. The design of a compact RI probe for in situ applications is discussed. The miniaturization of such a probe will probably limited by factors other than the loss of sensitivity. A novel angle-of-incidence control which requires only linear displacements of some of the optical components (no rotation) is proposed and shown to be feasible. Such an optical probe may be used in the dairy industry and in general in the food industry or food science research laboratories. It could give additional analytical power to the food scientist, engineer, or technician.

  15. Monitoring of high refractive index edible oils using coated long period fiber grating sensors

    Science.gov (United States)

    Coelho, Luís.; Viegas, Diana; Santos, José Luís.; de Almeida, Jose Manuel M. M.

    2015-05-01

    Monitoring the quality of high refractive index edible oils is of great importance for the human health. Uncooked edible oils in general are healthy foodstuff, olive oil in particular, however, they are frequently used for baking and cooking. High quality edible oils are made from seeds, nuts or fruits by mechanical processes. Nevertheless, once the mechanical extraction is complete, up to 15% of the oil remains in oil pomace and in the mill wastewater, which can be extracted using organic solvents, often hexane. Optical fiber sensors based on long period fiber gratings (LPFG) have very low wavelength sensitivity when the surround refractive index is higher than the refractive index of the cladding. Titanium dioxide (TiO2) coated LPFG could lead to the realization of high sensitivity chemical sensor for the food industry. In this work LPFG coated with a TiO2 thin film were successfully used for to detect small levels of hexane diluted in edible oils and for real time monitoring the thermal deterioration of edible oils. For a TiO2 coating of 30 nm a wavelength sensitivity of 1361.7 nm/RIU (or 0.97 nm / % V/V) in the 1.4610-1.4670 refractive index range was achieved, corresponding to 0 to 12 % V/V of hexane in olive oil. A sensitivity higher than 638 nm/RIU at 225 ºC was calculated, in the 1.4670-1.4735 refractive index range with a detection limit of thermal deterioration of about 1 minute.

  16. Surface tension and refractive index of pure and water-saturated tetradecyltrihexylphosphonium-based ionic liquids

    International Nuclear Information System (INIS)

    Highlights: ► Data for the refractive index and surface tension of tetradecyltrihexylphosphonium-based ionic liquids are reported. ► Experimental data for both pure and water-saturated ionic liquids are provided. ► The refractive index decreases with the increase on the water content. ► The surface tension decreases or increases as a function of the water content. ► The surface thermodynamic properties and critical temperatures are presented and discussed. - Abstract: Experimental data on the surface tension and refractive index of tetradecyltrihexylphosphonium-based ionic liquids with bromide, chloride, decanoate, methanesulfonate, dicyanimide, bis(2,4,4-trimethylpentyl)phosphinate and bis(trifluoromethylsulfonyl)imide anions are reported. The data were obtained for pure and water saturated samples at temperatures from 283 K to 353 K and at atmospheric pressure. The refractive index of the investigated ionic liquids decreases with increasing the water content in the sample. On the other hand, no clearly dependence of the surface tension with the water content up to a weight fraction of 16% was found. The prediction of the refractive index for the studied ionic liquids was also accomplished by a group contribution method and new values for the cation and diverse anions were estimated and proposed. The studied ionic liquids show lower surface tension in comparison with imidazolium-, pyridinium- or pyrrolidinium-based ionic liquids with a similar anion; also they show higher surface entropy than cyclic nitrogen-based fluids which indicates a lower surface organization. The anion dependence of the surface tension and surface entropy for the investigated ionic liquids is weaker than that for short-chain imidazolium-based ionic liquids. Their critical temperatures evaluated from Eötvos and Guggenheim equations are also lower than those of N-heterocyclic ionic fluids.

  17. Characterization of fluorinated silica thin films with ultra-low refractive index deposited at low temperature

    International Nuclear Information System (INIS)

    Structural and optical properties of low refractive index fluorinated silica (SiOxCyFz) films were investigated. The films were deposited on p-type silicon and polycarbonate substrates by radio frequency plasma enhanced chemical vapor deposition method at low temperatures. A mixture of tetraethoxysilane vapor, oxygen, and CF4 was used for deposition of the films. The influence of oxygen flow rate on the elemental compositions, chemical bonding states and surface roughness of the films was studied using energy dispersive X-ray analyzer, Fourier transform infrared spectroscopy in reflectance mode and atomic force microscopy, respectively. Effects of chemical bonds of the film matrix on optical properties and chemical stability were discussed. Energy dispersive spectroscopy showed high fluorine content in the SiOxCyFz film matrix which is in the range of 7.6–11.3%. It was concluded that in fluorine content lower than a certain limit, chemical stability of the film enhances, while higher contents of fluorine heighten moisture absorption followed by increasing refractive index. All of the deposited films were highly transparent. Finally, it was found that the refractive index of the SiOxCyFz film was continuously decreased with the increase of the O2 flow rate down to the minimum value of 1.16 ± 0.01 (at 632.8 nm) having the most ordered and nano-void structure and the least organic impurities. This sample also had the most chemical stability against moisture absorption. - Highlights: • Low deposition temperature and organic precursor led to higher film fluorination. • High fluorine and nanovoid structure led to drastic decrease in the refractive index. • Silica based thin film with ultralow refractive index of 1.16 was produced. • The produced ultralow-n film is highly stable against moisture absorption

  18. Absorption and refractive index recovery in an InGaAsP MQW electro-absorption modulator

    DEFF Research Database (Denmark)

    Romstad, Francis Pascal; Mørk, Jesper; Hvam, Jørn Märcher

    We show the first measurements of gain and refractive index recovery in an electro-absorber. The measurements show strong dependence of the refractive index dynamics on the reverse bias. The results are discussed in relation to field screening following the optical carrier injection....

  19. Dynamical measurement of refractive index distribution using digital holographic interferometry based on total internal reflection.

    Science.gov (United States)

    Zhang, Jiwei; Di, Jianglei; Li, Ying; Xi, Teli; Zhao, Jianlin

    2015-10-19

    We present a method for dynamically measuring the refractive index distribution in a large range based on the combination of digital holographic interferometry and total internal reflection. A series of holograms, carrying the index information of mixed liquids adhered on a total reflection prism surface, are recorded with CCD during the diffusion process. Phase shift differences of the reflected light are reconstructed exploiting the principle of double-exposure holographic interferometry. According to the relationship between the reflection phase shift difference and the liquid index, two dimensional index distributions can be directly figured out, assuming that the index of air near the prism surface is constant. The proposed method can also be applied to measure the index of solid media and monitor the index variation during some chemical reaction processes. PMID:26480394

  20. Optically transparent bionanofiber composites with low sensitivity to refractive index of the polymer matrix

    Science.gov (United States)

    Nogi, Masaya; Handa, Keishin; Nakagaito, Antonio Norio; Yano, Hiroyuki

    2005-12-01

    Transparent polymers were reinforced by bacterial cellulose (BC) nanofibers, which are 10×50nm ribbon-shaped fibers. They exhibited high luminous transmittance at a fiber content as high as 60 wt %, and low sensitivity to a variety of refractive indices of matrix resins. Due to the nanofiber size effect, high transparency was obtained against a wider distribution of refractive index of resins from 1.492 to 1.636 at 20 °C. The optical transparency was also surprisingly insensitive to temperature increases up to 80 °C. As such, BC nanofibers appear to be viable candidates for optically transparent reinforcement.

  1. Full Polarization Conical Dispersion and Zero-Refractive-Index in Two-Dimensional Photonic Hypercrystals.

    Science.gov (United States)

    Wang, Jia-Rong; Chen, Xiao-Dong; Zhao, Fu-Li; Dong, Jian-Wen

    2016-01-01

    Photonic conical dispersion has been found in either transverse magnetic or transverse electric polarization, and the predominant zero-refractive-index behavior in a two-dimensional photonic crystal is polarization-dependent. Here, we show that two-dimensional photonic hypercrystals can be designed that exhibit polarization independent conical dispersion at the Brillouin zone center, as two sets of triply-degenerate point for each polarization are accidentally at the same Dirac frequency. Such photonic hypercrystals consist of periodic dielectric cylinders embedded in elliptic metamaterials, and can be viewed as full-polarized near zero-refractive-index materials around Dirac frequency by using average eigen-field evaluation. Numerical simulations including directional emissions and invisibility cloak are employed to further demonstrate the double-zero-index characteristics for both polarizations in the photonic hypercrystals. PMID:26956377

  2. Aqueous ammonium thiocyanate solutions as refractive index-matching fluids with low density and viscosity

    Science.gov (United States)

    Morrison, Benjamin C.; Borrero-Echeverry, Daniel

    2015-11-01

    Index-matching fluids play an important role in many fluid dynamics experiments, particularly those involving particle tracking, as they can be used to minimize errors due to distortion from the refraction of light across interfaces of the apparatus. Common index-matching fluids, such as sodium iodide solutions or mineral oils, often have densities or viscosities very different from those of water. This can make them undesirable for use as a working fluid when using commercially available tracer particles or at high Reynolds numbers. A solution of ammonium thiocyanate (NH4SCN) can be used for index-matching common materials such as borosilicate glass and acrylic, and has material properties similar to those of water (ν ~ 1 . 6 cSt and ρ ~ 1 . 1 g/cc). We present an empirical model for predicting the refractive index of aqueous NH4SCN solutions as a function of temperature and NH4SCN concentration that allows experimenters to develop refractive index matching solutions for various common materials. This work was supported by the National Science Foundation (CBET-0853691) and by the James Borders Physics Student Fellowship at Reed College.

  3. Modification of the refractive index of dielectrica by means of ionizing radiation; Modifikation des Brechungsindexes von Dielektrika mit Hilfe ionisierender Strahlung

    Energy Technology Data Exchange (ETDEWEB)

    Andreas, B.

    2005-05-01

    Refractive-index changes are studied, which result by interaction of ionizing radiation with dielectric, optically transparent solids. As examples two materials are studied. At the one hand it deals with polymethylmethacrylate (PMMA), a polymer, which is irradiated with synchrotron radiation, and at the other hand with lithium niobate (LiNbO{sub 3}), an oxidic crystal, which is irradiated by fast helium ions. In both materials refractive-index changes in the range 10{sup -4} to 10{sup -3} can be produced, which is very interesting for many applications in photonics.

  4. Propagation of hypergeometric laser beams in a medium with a parabolic refractive index

    International Nuclear Information System (INIS)

    An expression to describe the complex amplitude of a family of paraxial hypergeometric laser beams propagating in a parabolic-index fiber is proposed. A particular case of a Gaussian optical vortex propagating in a parabolic-index fiber is studied. Under definite parameters, the Gaussian optical vortices become the modes of the medium. This is a new family of paraxial modes derived for the parabolic-index medium. A wide class of solutions of nonparaxial Helmholtz equations that describe modes in a parabolic refractive index medium is derived in the cylindrical coordinate system. As the solutions derived are proportional to Kummer’s functions, only those of them which are coincident with the nonparaxial Laguerre–Gaussian modes possess a finite energy, meaning that they are physically implementable. A definite length of the graded-index fiber is treated as a parabolic lens, and expressions for the numerical aperture and the focal spot size are deduced. An explicit expression for the radii of the rings of a binary lens approximating a parabolic-index lens is derived. Finite-difference time-domain simulation has shown that using a binary parabolic-index microlens with a refractive index of 1.5, a linearly polarized Gaussian beam can be focused into an elliptic focal spot which is almost devoid of side-lobes and has a smaller full width at half maximum diameter of 0.45 of the incident wavelength. (paper)

  5. Negative refractive index in a four-level atomic system

    Institute of Scientific and Technical Information of China (English)

    Zhang Zhen-Qing; Liu Zheng-Dong; Zhao Shun-Cai; Zheng Jun; Ji Yan-Fang; Liu Nian

    2011-01-01

    A closed four-level system in atomic vapour is proposed,which is made to possess left handedness by using the technique of quantum coherence.The density matrix method is utilized in view of the rotating-wave approximation and the effect of a local field in dense gas.The numerical simulation result shows that the negative permittivity and the negative permeability of the medium can be achieved simultaneously (i.e.the left handedness) in a wider frequency band under appropriate parameter conditions.Furthermore,when analysing the dispersion property of the left-handed material,we can find that the probe beam propagation can be controlled from superluminal to subluminal,or vice versa via changing the detuning of the probe field.

  6. Thermodynamic study of three pharmacologically significant drugs: Density, viscosity, and refractive index measurements at different temperatures

    International Nuclear Information System (INIS)

    Measurements of density, viscosity, and refractive index of three pharmacologically significant drugs, i.e. diclofenac sodium, cetrizine, and doxycycline have been carried in aqueous medium at T = (293.15 to 313.15) K. An automated vibrating-tube densimeter, viscometer, and refractometer are used in a concentration range from (7.5) . 10-3 to 25 . 10-3) mol . kg-1. The precise density results are used to evaluate the apparent molar volume, partial molar volume, thermal expansion coefficient, partial molar expansivity, and the Hepler's constant. Viscosity results are used to calculate the Jones-Dole viscosity B-coefficient, free energy of activation of the solute and solvent, activation enthalpy, and activation entropy. The molar refractive indices of the drug solutions can be employed to calculate molar refraction. It is inferred from these results that the above mentioned drugs act as structure-making compounds due to hydrophobic hydration of the molecules in the drugs

  7. Index of Refraction and Absorption Coefficient Spectra of Paratellurite in the Terahertz Region

    Science.gov (United States)

    Unferdorben, Márta; Buzády, Andrea; Hebling, János; Kiss, Krisztián; Hajdara, Ivett; Kovács, László; Péter, Ágnes; Pálfalvi, László

    2016-07-01

    Index of refraction and absorption coefficient spectra of pure paratellurite (α-TeO2) crystal as a potential material for terahertz (THz) applications were determined in the 0.25-2 THz frequency range at room temperature by THz time domain spectroscopy (THz-TDS). The investigation was performed with beam polarization both parallel (extraordinary polarization) and perpendicular (ordinary polarization) to the optical axis [001] of the crystal. Similarly to the visible spectral range, positive birefringence was observed in the THz range as well. It was shown that the values of the refractive index for extraordinary polarization are higher and show significantly larger dispersion than for the ordinary one. The absorption coefficient values are also larger for extraordinary polarization. The measured values were fitted by theoretical curves derived from the complex dielectric function containing independent terms of Lorentz oscillators due to phonon-polariton resonances. The results are compared with earlier publications, and the observed significant discrepancies are discussed.

  8. Refractive index matching to develop transparent polyaphrons: Characterization of immobilized proteins.

    Science.gov (United States)

    Ward, Keeran; Stuckey, David C

    2016-06-01

    Refractive index matching was used to create optically transparent polyaphrons to enable proteins adsorbed to the aphron surface to be characterized. Due to the significant light scattering created by polyaphrons, refractive index matching allowed for representative circular dichroism (CD) spectra and acceptable structural characterization. The method utilized n-hexane as the solvent phase, a mixture of glycerol and phosphate buffer (30% [w/v]) as the aqueous phase, and the non-ionic surfactants, Laureth-4 and Kolliphor P-188. Deconvolution of CD spectra revealed that the immobilized protein adapted its native conformation, showing that the adsorbed protein interacted only with the bound water layer ("soapy shell") of the aphron. Isothermal calorimetry further demonstrated that non-ionic surfactant interactions were virtually non-existent, even at the high concentrations used (5% [w/v]), proving that non-ionic surfactants can preserve protein conformation. PMID:26952359

  9. Pressure dependence of the refractive index in wurtzite and rocksalt indium nitride

    Energy Technology Data Exchange (ETDEWEB)

    Oliva, R. [Institut Jaume Almera, Consell Superior d' Investigacions Científiques (CSIC), Lluís Solé i Sabarís s.n., 08028 Barcelona, Catalonia (Spain); MALTA-Consolider Team, Departament de Física Aplicada, ICMUV, Universitat de València, c/Dr. Moliner 50, 46100 Burjassot, València (Spain); Segura, A. [MALTA-Consolider Team, Departament de Física Aplicada, ICMUV, Universitat de València, c/Dr. Moliner 50, 46100 Burjassot, València (Spain); Ibáñez, J., E-mail: jibanez@ictja.csic.es; Artús, L. [Institut Jaume Almera, Consell Superior d' Investigacions Científiques (CSIC), Lluís Solé i Sabarís s.n., 08028 Barcelona, Catalonia (Spain); Yamaguchi, T.; Nanishi, Y. [Faculty of Science and Engineering, Ritsumeikan University, Shiga 525-8577 (Japan)

    2014-12-08

    We have performed high-pressure Fourier transform infrared reflectance measurements on a freestanding InN thin film to determine the refractive index of wurtzite InN and its high-pressure rocksalt phase as a function of hydrostatic pressure. From a fit to the experimental refractive-index curves including the effect of the high-energy optical gaps, phonons, free carriers, and the direct (fundamental) band-gap in the case of wurtzite InN, we obtain pressure coefficients for the low-frequency (electronic) dielectric constant ε{sub ∞}. Negative pressure coefficients of −8.8 × 10{sup −2 }GPa{sup −1} and −14.8 × 10{sup −2 }GPa{sup −1} are obtained for the wurtzite and rocksalt phases, respectively. The results are discussed in terms of the electronic band structure and the compressibility of both phases.

  10. Sustainable UV-curable low refractive index resins with novel polymers for polymer cladding materials

    Science.gov (United States)

    Tokoro, Hiroki; Ishikawa, Takako; Koike, Nobuyuki; Yamashina, Yohzoh

    2014-03-01

    Low refractive index polymers are used as cladding materials for high numerical aperture (NA) fibers. Since transparent fluoro polymers are ideal for this application, they have been used over many years. However, some fluoro chemicals face an issue related to perfluoro octanoic acid (PFOA) which is caused by its longtime persistence in the environment and human body. In this research, non-PFOA type UV curable fluoro resins suitable for cladding were developed with novel materials. The cured films showed high transparency, good adhesion to glass and low refractive index of 1.359 and 1.386 at 850 nm. Optical fibers prepared with those cladding showed almost equivalent attenuation to a fiber with commercially available material.

  11. Quantum Enhancement of the Index of Refraction in a Bose-Einstein Condensate.

    Science.gov (United States)

    Bons, P C; de Haas, R; de Jong, D; Groot, A; van der Straten, P

    2016-04-29

    We study the index of refraction of an ultracold bosonic gas in the dilute regime. Using phase-contrast imaging with light detuned from resonance by several tens of linewidths, we image a single cloud of ultracold atoms for 100 consecutive shots, which enables the study of the scattering rate as a function of temperature and density using only a single cloud. We observe that the scattering rate is increased below the critical temperature for Bose-Einstein condensation by a factor of 3 compared to the single-atom scattering rate. We show that current atom-light interaction models to second order of the density show a similar increase, where the magnitude of the effect depends on the model that is used to calculate the pair-correlation function. This confirms that the effect of quantum statistics on the index of refraction is dominant in this regime. PMID:27176521

  12. Design of reflective optical fiber sensor for determining refractive index and sugar concentration of aqueous solutions

    Science.gov (United States)

    Marzuki, Ahmad; Wulan Sari, Nila; Riatun

    2016-02-01

    A reflective optical fiber sensor designed for measuring refractive index and sugar concentration of aqueous solutions is described. Two strains of parallel polymer optical fibers (POF) were wrapped in a bundle such that one of their fiber's end cross-sections had the same distance to the mirror surface. The light coming out from one strain of the fiber was reflected by the mirror to the second fiber. Sugar concentration of the aqueous solution filling the space between the fiber ends and the mirror was varied (1.0 M, 1.5 M, 2.0 M, 2.5 M, 3.0 M, 4.0 M, and 5.0 M). It was shown from the experiment that light intensity detected by photo-detector is linearly related to the percentage of the dissolved sugar in the solution as well as the variation of the sugar solution refractive index (R2 = 0.987).

  13. Interference method for monitoring the refractive index and the thickness of transparent films during deposition

    Science.gov (United States)

    Alius, H.; Schmidt, R.

    1990-04-01

    An interferometric method is described for simultaneous measurement of the refractive index and the thickness of transparent isotropic films during the deposition process. Two laser beams are focused impinging at two different angles onto the film. The intensity of the beams reflected from the growing film shows minima and maxima, which are counted and evaluated to determine the refractive index n and the thickness d of the film in the range of some 100 nm up to several micrometers using 633-nm laser light. n and d can be determined within an accuracy better than 1%, if the thickness is larger than three times the vacuum wavelength of the laser. The measurements are well in accordance with calculations of the intensity modulation. The method can easily be extended to multilayer systems.

  14. Infrared refractive index dispersion of PMMA spheres from synchrotron extinction spectra

    CERN Document Server

    Blümel, R; Lukacs, R; Kohler, A

    2016-01-01

    We performed high-resolution Fourier-transform infrared (FTIR) spectroscopy of a polymethyl methacrylate (PMMA) sphere of unknown size in the Mie scattering region. Apart from a slow, oscillatory structure (wiggles), which is due to an interference effect, the measured FTIR extinction spectrum exhibits a ripple structure, which is due to electromagnetic resonances. We fully characterize the underlying electromagnetic mode structure of the spectrum by assigning two mode numbers to each of the ripples in the measured spectrum. We show that analyzing the ripple structure in the spectrum in the wavenumber region from about $3000\\,$cm$^{-1}$ to $8000\\,$cm$^{-1}$ allows us to both determine the unknown radius of the sphere and the PMMA index of refraction, which shows a strong frequency dependence in this near-infrared spectral region. While in this paper we focus on examining a PMMA sphere as an example, our method of determining the refractive index and its dispersion from synchrotron infrared extinction spectra ...

  15. Symmetry relations in the generalized Lorenz-Mie theory for lossless negative refractive index media

    Science.gov (United States)

    André Ambrosio, Leonardo

    2016-09-01

    In this paper we present a theoretical analysis of the generalized Lorenz-Mie theory for negative refractive index (NRI) media and spherical scatterers, extending the well-known concepts and definitions found in the literature involving dielectric or positive refractive index (PRI) particles. The consequences of a negative phase velocity and an anti-parallelism of the wave vector with respect to the Poynting vector are investigated and interpreted in this framework and, together with the symmetries found for the beam-shape coefficients when compared to the conventional PRI case, it is shown that the description of plane waves, Gaussian beams and, more generally, on-axis azimuthally symmetric waves along a NRI medium, their fields and all physical properties can be conveniently correlated with that of dielectric media once the electromagnetic response functions are replaced by their corresponding dielectric counterparts.

  16. Spatial Frequency Responses of Anisotropic Refractive Index Gratings Formed in Holographic Polymer Dispersed Liquid Crystals

    Directory of Open Access Journals (Sweden)

    Yoshiaki Fukuda

    2016-03-01

    Full Text Available We report on an experimental investigation of spatial frequency responses of anisotropic transmission refractive index gratings formed in holographic polymer dispersed liquid crystals (HPDLCs. We studied two different types of HPDLC materials employing two different monomer systems: one with acrylate monomer capable of radical mediated chain-growth polymerizations and the other with thiol-ene monomer capable of step-growth polymerizations. It was found that the photopolymerization kinetics of the two HPDLC materials could be well explained by the autocatalytic model. We also measured grating-spacing dependences of anisotropic refractive index gratings at a recording wavelength of 532 nm. It was found that the HPDLC material with the thiol-ene monomer gave higher spatial frequency responses than that with the acrylate monomer. Statistical thermodynamic simulation suggested that such a spatial frequency dependence was attributed primarily to a difference in the size of formed liquid crystal droplets due to different photopolymerization mechanisms.

  17. The influence of mediums' refractive index on scattering characteristics of abnormal dispersion scatterer

    International Nuclear Information System (INIS)

    Based on the Mie scattering theory, we obtained that the calculation formula of scattering intensity Is, Qsca and Qabs. And we calculated scattering characteristics of SiC particle in the abnormal dispersion region under different refractive index mediums. The results show that with the increasing of mediums' refractive index, the peak position of scattering intensity moves towards the direction of larger wavelength and the peak value of scattering intensity increases; the peak position of Qsca and Qads move towards the direction of larger wavelength and the peak values of Qsca and Qabs decrease in the abnormal dispersion region. These could provide theoretical reference for the optical theory, experiment and application in the abnormal dispersion region. (authors)

  18. Determination of thin film refractive index and thickness by means of film phase thickness

    Science.gov (United States)

    Nenkov, Milen; Pencheva, Tamara

    2008-06-01

    A new approach for determination of refractive index dispersion n(λ) (the real part of the complex refractive index) and thickness d of thin films of negligible absorption and weak dispersion is proposed. The calculation procedure is based on determination of the phase thickness of the film in the spectral region of measured transmittance data. All points of measured spectra are included in the calculations. Barium titanate thin films are investigated in the spectral region 0.38-0.78 μm and their n(λ) and d are calculated. The approach is validated using Swanepoel's method and it is found to be applicable for relatively thin films when measured transmittance spectra have one minimum and one maximum only.

  19. High refractive index Fresnel lens on a fiber fabricated by nanoimprint lithography for immersion applications.

    Science.gov (United States)

    Koshelev, Alexander; Calafiore, Giuseppe; Piña-Hernandez, Carlos; Allen, Frances I; Dhuey, Scott; Sassolini, Simone; Wong, Edward; Lum, Paul; Munechika, Keiko; Cabrini, Stefano

    2016-08-01

    In this Letter, we present a Fresnel lens fabricated on the end of an optical fiber. The lens is fabricated using nanoimprint lithography of a functional high refractive index material, which is suitable for mass production. The main advantage of the presented Fresnel lens compared to a conventional fiber lens is its high refractive index (n=1.68), which enables efficient light focusing even inside other media, such as water or an adhesive. Measurement of the lens performance in an immersion liquid (n=1.51) shows a near diffraction limited focal spot of 810 nm in diameter at the 1/e2 intensity level for a wavelength of 660 nm. Applications of such fiber lenses include integrated optics, optical trapping, and fiber probes. PMID:27472584

  20. Binary and Ternary Mixtures of Biopolymers and Water: Viscosity, Refractive Index, and Density

    Science.gov (United States)

    Silva, Bárbara Louise L. D.; Costa, Bernardo S.; Garcia-Rojas, Edwin E.

    2016-08-01

    Biopolymers have been the focus of intense research because of their wide applicability. The thermophysical properties of solutions containing biopolymers have fundamental importance for engineering calculations, as well as for thermal load calculations, energy expenditure, and development of new products. In this work, the thermophysical properties of binary and ternary solutions of carboxymethylcellulose and/or high methoxylation pectin and water at different temperatures have been investigated taking into consideration different biopolymer concentrations. The experimental data related to the thermophysical properties were correlated to obtain empirical models that can describe the temperature-concentration combined effect on the density, refractive index, and dynamic viscosity. From data obtained from the experiments, the density, refractive index, and dynamic viscosity increase with increasing biopolymer concentration and decrease with increasing temperature. The polynomial models showed a good fit to the experimental data and high correlation coefficients (R2ge 0.98) for each studied system.

  1. Refractive-index-matched hydrogel materials for modeling flow-structure interactions

    CERN Document Server

    Byron, Margaret L

    2012-01-01

    In imaging-based studies of flow around solid objects, it is useful to have materials that are refractive-index-matched to the surrounding fluid. However, materials currently in use are usually rigid and matched to liquids that are either expensive or highly viscous. This does not allow for measurements at high Reynolds number, nor accurate modeling of flexible structures. This work explores the use of two hydrogels (agarose and polyacrylamide) as refractive-index-matched models in water. These hydrogels are inexpensive, can be cast into desired shapes, and have flexibility that can be tuned to match biological materials. The use of water as the fluid phase allows this method to be implemented immediately in many experimental facilities and permits investigation of high Reynolds number phenomena. We explain fabrication methods and present a summary of the physical and optical properties of both gels, and then show measurements demonstrating the use of hydrogel models in quantitative imaging.

  2. High refractive index Fresnel lens on a fiber fabricated by nanoimprint lithography for immersion applications

    Science.gov (United States)

    Koshelev, Alexander; Calafiore, Giuseppe; Piña-Hernandez, Carlos; Allen, Frances I.; Dhuey, Scott; Sassolini, Simone; Wong, Edward; Lum, Paul; Munechika, Keiko; Cabrini, Stefano

    2016-08-01

    In this Letter we present a Fresnel lens fabricated on the end of an optical fiber. The lens is fabricated using nanoimprint lithography of a functional high refractive index material, which is suitable for mass production. The main advantage of the presented Fresnel lens compared to a conventional fiber lens is its high refractive index (n=1.69), which enables efficient light focusing even inside other media such as water or adhesive. Measurement of the lens performance in an immersion liquid (n=1.51) shows a near diffraction limited focal spot of 810 nm in diameter at the 1/e2 intensity level for a wavelength of 660 nm. Applications of such fiber lenses include integrated optics, optical trapping and fiber probes.

  3. High refractive index Fresnel lens on a fiber fabricated by nanoimprint lithography for immersion applications

    CERN Document Server

    Koshelev, Alexander; Piña-Hernandez, Carlos; Allen, Frances; Dhuey, Scott; Sassolini, Simone; Wong, Edward; Lum, Paul; Munechika, Keiko; Cabrini, Stefano

    2016-01-01

    In this Letter we present a Fresnel lens fabricated on the end of an optical fiber. The lens is fabricated using nanoimprint lithography of a functional high refractive index material, which is suitable for mass production. The main advantage of the presented Fresnel lens compared to a conventional fiber lens is its high refractive index (n=1.69), which enables efficient light focusing even inside other media such as water or adhesive. Measurement of the lens performance in an immersion liquid (n=1.51) shows a near diffraction limited focal spot of 810 nm in diameter at the 1/e2 intensity level for a wavelength of 660 nm. Applications of such fiber lenses include integrated optics, optical trapping and fiber probes.

  4. Study of refractive index and thickness of TiO2/ormosil planar waveguide

    Institute of Scientific and Technical Information of China (English)

    Wang Bao-Ling; Hu Li-Li

    2004-01-01

    Hybrid titania/ormosil waveguide films have been prepared by sol-gel method at low thermal treatment temperature of 150℃. The influence of processing parameters including the molar ratios of Ti(OBu)4/ glycidoxypropyltrimethoxysilane (GLYMO) and H2O/Ti(OBu)4 (expressed as R), especially aging of sol, on the refractive index and thickness of film was investigated. The optical properties of films were measured with Scanning Electron Microscope and m-line spectroscopy. The results indicate that the film thickness increases with the aging time of sol, but the variation of refractive index as a function of aging time of sol depends on the relative ratio of GLYMO to Ti-alkoxide.The relation between film thickness and corresponding sol viscosity is linear as the volume of GLYMO is 80% within the range of measured data.

  5. Band gap and refractive index tunability in thallium based layered mixed crystals

    International Nuclear Information System (INIS)

    Compositional variation of the band gap energy and refractive index of TlMeX2-type (Me = Ga or In and X = S or Se) layered mixed crystals have been studied by the transmission and reflection measurements in the wavelength range of 400–1100 nm. The analysis of absorption data of TlGa1-xInxSe2, TlGa(S1−xSex)2, TlGa1−xInxS2, and TlIn(Se1−xSx)2 mixed crystals revealed the presence of both optical indirect and direct transitions. It was found that the energy band gaps of mixed crystals decrease at the replacing of gallium atoms by indium and of sulfur atoms by selenium ones. Through the similar replacing of atoms (smaller atoms by larger ones) in the studied mixed crystals, the refractive index shows the quite opposite behavior

  6. Refractive Index Sensor Based on a 1D Photonic Crystal in a Microfluidic Channel

    Directory of Open Access Journals (Sweden)

    Klaus B. Mogensen

    2010-03-01

    Full Text Available A refractive index sensor has been fabricated in silicon oxynitride by standard UV lithography and dry etching processes. The refractive index sensor consists of a 1D photonic crystal (PhC embedded in a microfluidic channel addressed by fiber-terminated planar waveguides. Experimental demonstrations performed with several ethanol solutions ranging from a purity of 96.00% (n = 1.36356 to 95.04% (n = 1.36377 yielded a sensitivity (Δλ/Δn of 836 nm/RIU and a limit of detection (LOD of 6 x 10-5 RIU, which is, however, still one order of magnitude higher than the theoretical lower limit of the limit of detection 1.3 x 10–6 RIU.

  7. Preparation of MgF2-SiO2 thin films with a low refractive index by a solgel process.

    Science.gov (United States)

    Ishizawa, Hitoshi; Niisaka, Shunsuke; Murata, Tsuyoshi; Tanaka, Akira

    2008-05-01

    Porous MgF(2)-SiO(2) thin films consisting of MgF(2) particles connected by an amorphous SiO(2) binder are prepared by a solgel process. The films have a low refractive index of 1.26, sufficient strength to withstand wiping by a cloth, and a high environmental resistance. The refractive index of the film can be controlled by changing the processing conditions. Films can be uniformly formed on curved substrates and at relatively low temperatures, such as 100 degrees C. The low refractive index of the film, which cannot be achieved by conventional dry processes, is effective in improving the performance of antireflective coatings. PMID:18449247

  8. Effect of small variations in the refractive index of the ambient medium on the spectrum of a bent fibre-optic Fabry - Perot interferometer

    Energy Technology Data Exchange (ETDEWEB)

    Kulchin, Yurii N; Vitrik, O B; Gurbatov, S O [Institute for Automation and Control Processes, Far-Eastern Branch, Russian Academy of Sciences, Vladivostok (Russian Federation)

    2011-09-30

    The phase of light propagating through a bent optical fibre is shown to depend on the refractive index of the medium surrounding the fibre cladding when there is resonance coupling between the guided core mode and cladding modes. This shifts the spectral maxima in the bent fibre-optic Fabry - Perot interferometer. The highest phase and spectral sensitivities achieved with this interferometer configuration are 0.71 and 0.077, respectively, and enable changes in the refractive index of the ambient medium down to 5 Multiplication-Sign 10{sup -6} to be detected. This makes the proposed approach potentially attractive for producing highly stable, precision refractive index sensors capable of solving a wide range of liquid refractometry problems.

  9. Refractive index spectral dependence, Raman and transmission spectra of high-purity $^{28}$Si, $^{29}$Si, $^{30}$Si, and $^{nat}$Si single crystals

    CERN Document Server

    Plotnichenko, V G; Kryukova, E B; Koltashev, V V; Sokolov, V O; Dianov, E M; Gusev, A V; Gavva, V A; Kotereva, T V; Churbanov, M F

    2011-01-01

    Precise measurement of the refractive index of stable silicon isotopes $^{28}$Si, $^{29}$Si, $^{30}$Si single crystals with enrichments above 99.9 at.% and a silicon single crystal $^{nat}$Si of natural isotopic composition is performed with the Fourier-transform interference refractometry method from 1.06 to more than 80 mkm with 0.1 cm$^{-1}$ resolution and accuracy of $2 \\times 10^{-5} ... 1 \\times 10^{-4}$. The oxygen and carbon concentrations in all crystals are within $5 \\times 10^{15}$ cm$^{-3}$ and the content of metal impurities is $10^{-5} ... 10^{-6}$ at.%. The peculiar changes of the refractive index in the phonon absorption region of all silicon single crystals are shown. The coefficients of generalized Cauchy dispersion function approximating the experimental refractive index values all over the measuring range are given. The transmission and Raman spectra are also studied.

  10. High index of refraction films for dielectric mirrors prepared by metal-organic chemical vapor deposition

    International Nuclear Information System (INIS)

    A wide variety of metal oxides with high index of refraction can be prepared by Metal-Organic Chemical Vapor Deposition. We present some recent optical and laser damage results on oxide films prepared by MOCVD which could be used in a multilayer structure for highly reflecting (HR) dielectric mirror applications. The method of preparation affects both optical properties and laser damage threshold. 10 refs., 8 figs., 4 tabs

  11. Design of photonic crystal fiber long-period grating refractive index sensor

    Czech Academy of Sciences Publication Activity Database

    Kaňka, Jiří; Zhu, Y.; He, Z.; Du, H.

    Bellingham, Washington : SPIE, 2009 - (Udd, E.; Du, H.; Wang, A.), 73161D-1-73161D-8 ISBN 9780819475824. ISSN 0277-786X. - (Proceedings of SPIE 7316). [SPIE Defense, Security, and Sensing. Orlando (US), 13.04.2009-17.04.2009] R&D Projects: GA ČR GA102/08/1719 Institutional research plan: CEZ:AV0Z20670512 Keywords : Photonic crystal fiber * Long-period grating * Refractive index sensors Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  12. Contribution of the Refractive Index Fluctuations to the Length Noise in Displacement Interferometry

    Czech Academy of Sciences Publication Activity Database

    Holá, Miroslava; Hrabina, Jan; Šarbort, Martin; Oulehla, Jindřich; Číp, Ondřej; Lazar, Josef

    2015-01-01

    Roč. 15, č. 5 (2015), s. 263-267. ISSN 1335-8871 R&D Projects: GA ČR GB14-36681G; GA TA ČR TA02010711; GA TA ČR TE01020233; GA MŠk(CZ) LO1212; GA MŠk EE2.3.30.0054 Institutional support: RVO:68081731 Keywords : nanometrology * interferometry * refractive index of air Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.989, year: 2014

  13. Effect of annealing on various dielectric functions and refractive index of lead iodide single crystals

    Czech Academy of Sciences Publication Activity Database

    Hassan, M. A. S.; Matuchová, Marie

    2006-01-01

    Roč. 60, 2/3 (2006), s. 51-54. ISSN 1407-009X R&D Projects: GA ČR(CZ) GA102/03/0379; GA ČR(CZ) GA102/04/0959; GA AV ČR(CZ) KSK1010104 Institutional research plan: CEZ:AV0Z20670512 Keywords : dielectric losses * refractive index * characteristics measurement Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  14. Aluminum-jointed silicon dioxide octagon nanohelix array with desired complex refractive index.

    Science.gov (United States)

    Jen, Yi-Jun; Chen, Chien-Chi; Jheng, Ci-Yao

    2014-06-15

    In this Letter, glancing angle deposition is used to form an aluminum-jointed silicon dioxide octagon nanohelix array as a 3D nanostructured thin film. As a sculptured metal-dielectric composite, the film exhibits a complex refractive index of near unity with a small imaginary part. This structured film is demonstrated as an efficient light absorber to absorb light in a broad band and over a wide range of angles for both polarization states. PMID:24978492

  15. Quantifying the refractive index dispersion of a pigmented biological tissue using Jamin-Lebedeff interference microscopy

    OpenAIRE

    Stavenga, Doekele G; Leertouwer, Hein L.; WILTS, Bodo D.

    2013-01-01

    Jamin-Lebedeff polarizing interference microscopy is a classical method for determining the refractive index and thickness of transparent tissues. Here, we extend the application of this method to pigmented, absorbing biological tissues, based on a theoretical derivation using Jones calculus. This novel method is applied to the wings of the American Rubyspot damselfly, Hetaerina americana. The membranes in the red-colored parts of the damselfly's wings, with a thickness of similar to 2.5 mu m...

  16. Nanofabrication of planar split ring resonators for negative refractive index metamaterials in the infrared range

    OpenAIRE

    ZORAN JAKSIC; DANA VASILJEVIC-RADOVIC; MILAN MAKSIMOVIC; MILIJA SARAJLIC; ZORAN DJURIC

    2006-01-01

    Experimental nanofabrication of planar structures for one-dimensional metamaterials designed to achieve a negative effective refractive index in the mid-infrared range (5–10 micrometers) was performed. Double split ring and complementary double split ring resonators (SRR and CSRR) with square and circular geometries, were chosen to be fabricated since these are the basic building blocks to achieve a negative effective dielectric permittivity and magnetic permeability. Scanning probe nanolitho...

  17. Transmission of a broadband light through a fiber optic loop: effect of nonlinear refractive index

    OpenAIRE

    Zakhidov, Erkin; KOKHKHAROV, ABDUMUTALLIB; MIRTADJIEV, Farrukh

    2014-01-01

    The results of studies of broadband light transmission through a fiber loop and a double loop under the effect of nonlinear refractive index are presented in this paper. Fiber loop and double loop transmission/reflection vs. a coupler splitting ratio at various powers of the light with a spectral width of approximately 35 nm are studied and high efficient nonlinear light switching is demonstrated. It is shown that a double loop formed by consecutive connecting 2 fiber loops allows us to...

  18. Enhanced refractive index without absorption in four-level asymmetrical double semiconductor quantum well

    Science.gov (United States)

    Kang, Chengxian; Wang, Zhiping; Yu, Benli

    2016-03-01

    We investigate the absorptive-dispersive properties of a weak probe field in a four-level asymmetrical double semiconductor quantum well. It is found that the enhanced refraction index without absorption can be easily controlled via adjusting properly the corresponding parameters of the system. Our scheme may provide some new possibilities for technological applications in dispersion compensation and solid-state quantum communication for quantum information processing.

  19. Frequency measurement of refraction index of air for high-resolution laser interferometry

    Czech Academy of Sciences Publication Activity Database

    Číp, Ondřej; Petrů, František; Matoušek, V.; Lazar, Josef

    Bellingham : SPIE, 2004, s. 273-277. ISBN 0-8194-5380-3. ISSN 0277-786X. [Optical Micro- and Nanometrology in Manufacturing Technology. Strasbourg (FR), 29.04.2004-30.04.2004] R&D Projects: GA AV ČR(CZ) IAB2065001 Keywords : index of refraction of air * high-resolution laser interferometry * Edlen formula Subject RIV: BH - Optics, Masers, Laser s

  20. Engineering properties of high-refractive index optical gels for photonic device applications

    Science.gov (United States)

    Stone, David S.; Connor, Samantha R.

    2000-04-01

    We have investigated a new class of high refractive index, non-yellowing, viscoelastic optical gels. Refractive indices for these materials can be adjusted from that needed to match fused silica to above nD equals 1.6 to match the higher index engineering glasses, plastics, and semiconductors. These materials are designed for permanent optically clear encapsulation in devices where severe mechanical shock or differential thermal expansion, such as occurs during PCB soldering operations, may render conventional high strength optical epoxies unusable. These low shear stress gels can also be customized to exhibit a wide range of rheological 'stiffness'. We have demonstrated quasi-fluid versions with apparent viscosities of 500,000 cP to hard-rubber-like consistencies registering on the high end of the Shore 00 durometer scale. In this paper, we present measurements of engineering properties on both elastometer-like curing optical gels, and thixotropic non- curing optical gels for: a) optical properties from near UV to near IR: refractive index over temperature, dispersion, and optical absorption; b) rheological properties: viscosity vs. shear rate, Shore hardness and cone penetration. Validation of ultra-low volatility and high temperature thermo oxidative stability required for long-lived photonic devices is discussed. Use of gel technology in fiber splices and photonic devices is described.

  1. Study on Optical Constants and Refractive Index Dispersion of Neutral red Doped Polymer Film

    Directory of Open Access Journals (Sweden)

    Hussain A. Badran

    2012-01-01

    Full Text Available Problem statement: The some optical constants polymer thin film with red dye 3-amino-7-dimethylamino-2-methyl phenazine (NR as the guest material and Polyvinylpyrrolidone (PVP as the host material were prepared by adulteration and spin-coating methods. Approach: The values of some important parameters (refractive index n, extinction coefficient K and dielectric constant ε∞ of polymer thin film are determined from these spectra. Results: It has been found that the dispersion data obey the single oscillator relation of the Wemple-DiDomenico model, from which the dispersion parameters and high-frequency dielectric constant were determined. The estimation of the E0, Ed and ε∞ are 1.27, 3.175 and 3.5 eV respectively. Conclusion: The single oscillator model was used to calculate their optical constants from the transmittance and reflectance spectra. The dispersion of the refractive index in film follow the single electronic oscillator mode relation. The UV-Visible spectroscopic studies showed that, the NR film have high refractive index and high dielectric constant. The variation of the dielectric constant with the wavelength indicates that some interactions between photon and electrons in the films are produced in this wavelength range. These interactions are observed on the shapes of the real and imaginary parts of the dielectric constant and they cause the formation of peaks in the dielectric spectra which depends on the material type.

  2. Zoned near-zero refractive index fishnet lens antenna: Steering millimeter waves

    International Nuclear Information System (INIS)

    A zoned fishnet metamaterial lens is designed, fabricated, and experimentally demonstrated at millimeter wavelengths to work as a negative near-zero refractive index lens suitable for compact lens antenna configurations. At the design frequency f = 56.7 GHz (λ0 = 5.29 mm), the zoned fishnet metamaterial lens, designed to have a focal length FL = 9λ0, exhibits a refractive index n = −0.25. The focusing performance of the diffractive optical element is briefly compared with that of a non-zoned fishnet metamaterial lens and an isotropic homogeneous zoned lens made of a material with the same refractive index. Experimental and numerically-computed radiation diagrams of the fabricated zoned lens are presented and compared in detail with that of a simulated non-zoned lens. Simulation and experimental results are in good agreement, demonstrating an enhancement generated by the zoned lens of 10.7 dB, corresponding to a gain of 12.26 dB. Moreover, beam steering capability of the structure by shifting the feeder on the xz-plane is demonstrated

  3. Zoned near-zero refractive index fishnet lens antenna: Steering millimeter waves

    Energy Technology Data Exchange (ETDEWEB)

    Pacheco-Peña, V., E-mail: victor.pacheco@unavarra.es; Orazbayev, B., E-mail: b.orazbayev@unavarra.es; Beaskoetxea, U., E-mail: unai.beaskoetxea@unavarra.es; Beruete, M., E-mail: miguel.beruete@unavarra.es [TERALAB (MmW—THz—IR and Plasmonics Laboratory), Universidad Pública de Navarra, Campus Arrosadía, 31006 Pamplona (Spain); Navarro-Cía, M., E-mail: m.navarro@imperial.ac.uk [Optical and Semiconductor Devices Group, Department of Electrical and Electronic Engineering, Imperial College London, London SW7 2BT (United Kingdom); Centre for Plasmonics and Metamaterials, Imperial College London, London SW7 2AZ (United Kingdom); Centre for Terahertz Science and Engineering, Imperial College London, London SW7 2AZ (United Kingdom)

    2014-03-28

    A zoned fishnet metamaterial lens is designed, fabricated, and experimentally demonstrated at millimeter wavelengths to work as a negative near-zero refractive index lens suitable for compact lens antenna configurations. At the design frequency f = 56.7 GHz (λ{sub 0} = 5.29 mm), the zoned fishnet metamaterial lens, designed to have a focal length FL = 9λ{sub 0}, exhibits a refractive index n = −0.25. The focusing performance of the diffractive optical element is briefly compared with that of a non-zoned fishnet metamaterial lens and an isotropic homogeneous zoned lens made of a material with the same refractive index. Experimental and numerically-computed radiation diagrams of the fabricated zoned lens are presented and compared in detail with that of a simulated non-zoned lens. Simulation and experimental results are in good agreement, demonstrating an enhancement generated by the zoned lens of 10.7 dB, corresponding to a gain of 12.26 dB. Moreover, beam steering capability of the structure by shifting the feeder on the xz-plane is demonstrated.

  4. Velocimetry with refractive index matching for complex flow configurations, phase 1

    Science.gov (United States)

    Thompson, B. E.; Vafidis, C.; Whitelaw, J. H.

    1987-01-01

    The feasibility of obtaining detailed velocity field measurements in large Reynolds number flow of the Space Shuttle Main Engine (SSME) main injector bowl was demonstrated using laser velocimetry and the developed refractive-index-matching technique. An experimental system to provide appropriate flow rates and temperature control of refractive-index-matching fluid was designed and tested. Test results are presented to establish the feasibility of obtaining accurate velocity measurements that map the entire field including the flow through the LOX post bundles: sample mean velocity, turbulence intensity, and spectral results are presented. The results indicate that a suitable fluid and control system is feasible for the representation of complex rocket-engine configurations and that measurements of velocity characteristics can be obtained without the optical access restrictions normally associated with laser velocimetry. The refractive-index-matching technique considered needs to be further developed and extended to represent other rocket-engine flows where current methods either cannot measure with adequate accuracy or they fail.

  5. Lattice and electronic contributions to the refractive index of CuWO₄

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz-Fuertes, J., E-mail: ruiz-fuertes@kristall.uni-frankfurt.de [Geowissenschaften, Goethe-Universität, Altenhöferallee 1, 60438 Frankfurt am Main (Germany); Malta-Consolider Team, Departamento de Física Aplicada-ICMUV, Universitat de València, Dr. Moliner 50, 46100 Burjassot (Spain); Pellicer-Porres, J.; Segura, A. [Malta-Consolider Team, Departamento de Física Aplicada-ICMUV, Universitat de València, Dr. Moliner 50, 46100 Burjassot (Spain); Rodríguez-Hernández, P.; Muñoz, A. [Malta-Consolider Team Departamento de Física Fundamental II, Instituto de Materiales y Nanotecnología, Universidad de La Laguna, La Laguna, 38205 Tenerife (Spain)

    2014-09-14

    We report an investigation of the refractive index dispersion and anisotropy in CuWO₄ by means of interference measurements in two extinction directions from mid infrared to the visible region of the energy spectrum. The analysis of the refractive index dispersion yields ϵ(∞)=4.5(1) for light polarization parallel to the c-axis and ϵ(∞)=5.3(1) with respect to the other extinction axis. In addition, we report reflectance measurements carried out from the far infrared to the near ultraviolet to study the lattice and electronic contributions to the refractive index of CuWO₄. We have determined the wavenumbers of nine infrared active lattice modes and compared them with previous ab initio calculations. The value of the Penn gap, 7eV, as well as the origin of a structure observed at 4.4 eV in the reflectance spectrum, is discussed in the context of the CuWO₄ electronic structure.

  6. Derivation of a Vacuum Refractive Index in a Stringy Space-Time Foam Model

    CERN Document Server

    Ellis, Jonathan Richard; Nanopoulos, D V

    2008-01-01

    It has been suggested that energetic photons propagating in vacuo should experience a non-trivial refractive index due to the foamy structure of space-time induced by quantum-gravitational fluctuations. The sensitivity of recent astrophysical observations, particularly of AGN Mk501 by the MAGIC Collaboration, approaches the Planck scale for a refractive index depending linearly on the photon energy. We present here a new derivation of this quantum-gravitational vacuum refraction index, based on a stringy analogue of the interaction of a photon with internal degrees of freedom in a conventional medium. We model the space-time foam as a gas of D-particles in the bulk space-time of a higher-dimensional cosmology where the observable Universe is a D3-brane. The interaction of an open string representing a photon with a D-particle stretches and excites the string, which subsequently decays and re-emits the photon with a time delay that increases linearly with the photon energy and is related to stringy uncertainty...

  7. Standard guide for choosing a method for determining the index of refraction and dispersion of glass

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2006-01-01

    1.1 This guide identifies and describes seven test methods for measuring the index of refraction of glass, with comments relevant to their uses such that an appropriate choice of method can be made. Four additional methods are mentioned by name, and brief descriptive information is given in Annex A1. The choice of a test method will depend upon the accuracy required, the nature of the test specimen that can be provided, the instrumentation available, and (perhaps) the time required for, or the cost of, the analysis. Refractive index is a function of the wavelength of light; therefore, its measurement is made with narrow-bandwidth light. Dispersion is the physical phenomenon of the variation of refractive index with wavelength. The nature of the test-specimen refers to its size, form, and quality of finish, as described in each of the methods herein. The test methods described are mostly for the visible range of wavelengths (approximately 400 to 780m); however, some methods can be extended to the ultraviolet a...

  8. Measuring the Terahertz Refractive Index of Boron-Doped Silicon Using a Photoconducting Antenna Terahertz Generator

    Science.gov (United States)

    McNamara, Brendan P.

    The frequency range commonly referred to as the terahertz gap occurs between the infrared and microwave regions of the electromagnetic spectrum. This range of frequencies is highly suited to investigating the free carrier interactions of materials, as the range is particularly sensitive to these interactions. Using terahertz time-domain spectroscopy (THz-TDS), it is possible to measure the effect these interactions have on a terahertz pulse and, using classical optical techniques, determine the terahertz refractive index of a given material, which is directly related to the free carrier spectrum of said material. Knowing the refractive index of a material in the THz range opens the possibility of future terahertz applications for said material, including a non-destructive dopant testing of silicon. In this work, a series of Silicon on Insulator (SOI) wafer samples are implanted with boron in a range of carrier concentrations. Using a photoconducting antenna (PCA), high-frequency laser pulses were converted to THz pulses and the complex terahertz refractive index of the samples was then measured in the 0.2-2 THz frequency range. This measurement is a direct examination of the free carrier spectrum through experimental methods. The results are compared with the predictions of the Drude model for the free carrier spectrum across this frequency range and are found to closely coincide at higher carrier concentrations, indicating that the behavior of free holes in p-type silicon can likely be described classically at high carrier densities, consistent with previous work on n-type silicon.

  9. Refractive Index and Fourier Transform Infrared Spectra of Virgin Coconut Oil and Virgin Olive Oil

    Directory of Open Access Journals (Sweden)

    W. M.M. Yunus

    2009-01-01

    Full Text Available This study presents the refractive index and FTIR spectra of virgin coconut oil and virgin olive oil that have been measured in the wavelength range from 491.0-667.8 nm. The measurement of refractive index was carried out using a minimum deviation method while the IR transmission ranging from 600-4000 cm-1 was measured using FTIR spectrometer respectively. The measurements were done at room temperature and the dispersion equations for the studied samples were verified and the Cauchy constants were obtained by fitting the experimental data to the Cauchy formula. For both, refractive index and Cauchy constants, the value obtained are higher in virgin olive oil as compared to virgin coconut oil. A similar result for FTIR absorption spectrum was also observed where the five important peaks explaining the stretching absorption due to aldehyde (C = O and esters (C-O, bending absorption (methylene (CH2 and methyl (CH3 groups and double bond absorptions (C = O were strong in virgin olive oil.

  10. SiOxNy thin films with variable refraction index: Microstructural, chemical and mechanical properties

    International Nuclear Information System (INIS)

    In this work amorphous silicon oxynitride films with similar composition (ca. Si0.40N0.45O0.10) were deposited by reactive magnetron sputtering from a pure Si target under different N2-Ar mixtures. Rutherford backscattering (RBS) studies revealed that the coatings presented similar composition but different density. The mechanical properties evaluated by nanoindentation show also a dependence on the deposition conditions that does not correlate with a change in composition. An increase in nitrogen content in the gas phase results in a decrease of hardness and Young's modulus. The microstructural study by high resolution scanning electron microscopy (SEM-FEG) on non-metalized samples allowed the detection of a close porosity in the form of nano-voids (3-15 nm in size), particularly in the coatings prepared under pure N2 gas. It has been shown how the presence of the close porosity allows tuning the refraction index of the films in a wide range of values without modifying significantly the chemical, thermal and mechanical stability of the film.

  11. Influence of Surfactant Bilayers on the Refractive Index Sensitivity and Catalytic Properties of Anisotropic Gold Nanoparticles.

    Science.gov (United States)

    Martinsson, Erik; Shahjamali, Mohammad M; Large, Nicolas; Zaraee, Negin; Zhou, Yu; Schatz, George C; Mirkin, Chad A; Aili, Daniel

    2016-01-20

    Shape-controlled synthesis of gold nanoparticles generally involves the use of surfactants, typically cetyltrimethylammonium (CTAX, X = Cl(-) , Br(-)), to regulate the nucleation growth process and to obtain colloidally stable nanoparticles. The surfactants adsorb on the nanoparticle surface making further functionalization difficult and therefore limit their use in many applications. Herein, the influence of CTAX on nanoparticle sensitivity to local dielectric environment changes is reported. It is shown, both experimentally and theoretically, that the CTAX bilayer significantly reduces the refractive index (RI) sensitivity of anisotropic gold nanoparticles such as nanocubes and concave nanocubes, nanorods, and nanoprisms. The RI sensitivity can be increased by up to 40% by removing the surfactant layer from nanoparticles immobilized on a solid substrate using oxygen plasma treatment. This increase compensates for the otherwise problematic decrease in RI sensitivity caused by the substrate effect. Moreover, the removal of the surfactants both facilitates nanoparticle biofunctionalization and significantly improves their catalytic properties. The strategy presented herein is a simple yet effective universal method for enhancing the RI sensitivity of CTAX-stabilized gold nanoparticles and increasing their potential as transducers in nanoplasmonic sensors, as well as in catalytic and biomedical applications. PMID:26583756

  12. Estimation of the path-averaged atmospheric refractive index structure constant from time-lapse imagery

    Science.gov (United States)

    Basu, Santasri; McCrae, Jack E.; Fiorino, Steven T.

    2015-05-01

    A time-lapse imaging experiment was conducted to monitor the effects of the atmosphere over some period of time. A tripod-mounted digital camera captured images of a distant building every minute. Correlation techniques were used to calculate the position shifts between the images. Two factors causing shifts between the images are: atmospheric turbulence, causing the images to move randomly and quickly, plus changes in the average refractive index gradient along the path which cause the images to move vertically, more slowly and perhaps in noticeable correlation with solar heating and other weather conditions. A technique for estimating the path-averaged C 2n from the random component of the image motion is presented here. The technique uses a derived set of weighting functions that depend on the size of the imaging aperture and the patch size in the image whose motion is being tracked. Since this technique is phase based, it can be applied to strong turbulence paths where traditional irradiance based techniques suffer from saturation effects.

  13. Simultaneous measurement of refractive index and temperature based on asymmetric structures modal interference

    Science.gov (United States)

    Wang, Huihao; Meng, Hongyun; Xiong, Rui; Wang, Qinghao; Huang, Ben; Zhang, Xing; Yu, Wei; Tan, Chunhua; Huang, Xuguang

    2016-04-01

    An in-line fiber sensor for simultaneous measurement of refractive index (RI) and temperature is proposed and demonstrated. The sensor head is composed of an asymmetric Mach-Zehnder interferometer (MZI), which is combining the single mode-multimode-single mode (SMS) fiber structure and a peanut-shape structure. The transmission dips of the sensor will shift as the ambient RI or temperature variation due to the phase changing. The different wavelength transmission dips formed by the cladding modes interfering with the core mode have different sensitivity responses, so the simultaneous measurement of the RI and temperature can be achieved by monitoring the wavelength shifts of the two transmission dips. The experimental results show that the sensing sensitivities of RI and temperature are -86.7434 nm/RIU and 0.0590 nm/°C in the RI range from 1.3105 to 1.3517 and temperature range from 25 °C to 85 °C, respectively. The novel sensor processes easy fabrication, low cost, and high sensitivity, making it offers high potential applications in physical, biological and chemical sensing.

  14. Anomalous behavior of neutron refraction index in a perfect crystal near the Bragg reflex

    International Nuclear Information System (INIS)

    Anomalous behavior of neutron refraction index in a perfect crystal near Bragg resonance was studied. This phenomenon is connected with the resonance behavior of potential of neutron interaction with crystal near the Bragg reflex. The amplitude of this resonance is equal to magnitude of g-harmonic of neutron interaction potential Vg and width is about the Bragg width of reflex. Recently, it was shown that for the case of noncentrosymmetric crystal this effect result in a large electric field acting on a neutron (value of the field can reach about 108V/cm) . This effect is planed using to search for the electric dipole moment of a neutron. If the degree of crystal imperfect is less than the Bragg reflection width (case of perfect crystal) the width of the reflex is determined by the own width of crystal reflex that is about 10−5 of the neutron energy. The value of g-harmonics of interaction of neutron with crystal Vg and optical potential of the interaction of neutron with crystal V0 are usually about the same. Therefore the variation of neutron energy on a 10−5 of its value will change significantly a potential of neutron interaction with crystal

  15. The role of macromolecular crowding in the evolution of lens crystallins with high molecular refractive index

    International Nuclear Information System (INIS)

    Crystallins are present in the lens at extremely high concentrations in order to provide transparency and generate a high refractive power of the lens. The crystallin families prevalent in the highest density lens tissues are γ-crystallins in vertebrates and S-crystallins in cephalopods. As shown elsewhere, in parallel evolution, both have evolved molecular refractive index increments 5–10% above those of most proteins. Although this is a small increase, it is statistically very significant and can be achieved only by very unusual amino acid compositions. In contrast, such a molecular adaptation to aid in the refractive function of the lens did not occur in crystallins that are preferentially located in lower density lens tissues, such as vertebrate α-crystallin and taxon-specific crystallins. In the current work, we apply a model of non-interacting hard spheres to examine the thermodynamic contributions of volume exclusion at lenticular protein concentrations. We show that the small concentration decrease afforded by the higher molecular refractive index increment of crystallins can amplify nonlinearly to produce order of magnitude differences in chemical activities, and lead to reduced osmotic pressure and the reduced propensity for protein aggregation. Quantitatively, this amplification sets in only at protein concentrations as high as those found in hard lenses or the nucleus of soft lenses, in good correspondence to the observed crystallin properties in different tissues and different species. This suggests that volume exclusion effects provide the evolutionary driving force for the unusual refractive properties and the unusual amino acid compositions of γ-crystallins and S-crystallins

  16. Optical fiber Fabry-Perot interferometer cavity fabricated by femtosecond laser micromachining and fusion splicing for refractive index sensing.

    Science.gov (United States)

    Liao, C R; Hu, T Y; Wang, D N

    2012-09-24

    We demonstrate a fiber in-line Fabry-Perot interferometer cavity sensor for refractive index measurement. The interferometer cavity is formed by drilling a micro-hole at the cleaved fiber end facet, followed by fusion splicing. A micro-channel is inscribed by femtosecond laser micromachining to vertically cross the cavity to allow liquid to flow in. The refractive index sensitivity obtained is ~994 nm/RIU (refractive index unit). Such a device is simple in configuration, easy for fabrication and reliable in operation due to extremely low temperature cross sensitivity of ~4.8 × 10(-6) RIU/°C. PMID:23037431

  17. Refractive index gradient measurement across the thickness of a dielectric film by the prism coupling method

    International Nuclear Information System (INIS)

    A method is proposed for measuring the refractive index gradient n(z) in nonuniformly thick dielectric films. The method is based on the excitation of waveguide modes in a film using the prism coupling technique and on the calculation of n(z) and film thickness Hf with the help of the angular positions of the TE or TM modes. The method can be used for an arbitrary shape of the index modulation over the film thickness in the limit of a small gradient [Δ n(z)/n(z) || 1]. (laser applications and other topics in quantum electronics)

  18. Negative index of refraction, perfect lenses and transformation optics -- some words of caution

    CERN Document Server

    Bergamin, Luzi

    2010-01-01

    In this paper we show that a negative index of refraction is not a direct implication of transformation optics with orientation-reversing diffeomorphisms. Rather a negative index appears due to a specific choice of sign freedom. Furthermore, we point out that the transformation designed lens, which relies on the concept of spacetime folding, does not amplify evanescent modes, in contrast to the Pendry-Veselago lens. Instead, evanescent modes at the image point are produced by a duplicated source and thus no imaging of the near field (perfect lensing) takes place.

  19. Nonlinear index of refraction of Cu- and Pb-implanted fused silica

    International Nuclear Information System (INIS)

    We have measured the nonlinear index of refraction in high-purity fused silica implanted with Pb and Cu ions, using 100-ps pulses from a cw, mode-locked, frequency-doubled Nd:YAG laser (λ = 532 nm). The nonlinear index measured for the Pb-implanted silica is an order of magnitude larger than that for Cu:silica. Qualitative evidence from infrared reflectance spectra suggests that these differences may result from distinctive ways in which these implanted ions are incorporated into the glass network: the Cu appears to form nm-size colloids, while the Pb may be incorporated into a Pb-O-Si glassy phase. (orig.)

  20. Characterization of fluorinated silica thin films with ultra-low refractive index deposited at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Abbasi-Firouzjah, Marzieh [Semnan Science and Technology Park, 3614933578, Shahrood (Iran, Islamic Republic of); Shokri, Babak, E-mail: b-shokri@sbu.ac.ir [Laser & Plasma Research Institute, Shahid Beheshti University, G.C., Evin, Tehran 1983963113 (Iran, Islamic Republic of); Physics Department, Shahid Beheshti University, G.C., Evin, Tehran 1983963113 (Iran, Islamic Republic of)

    2015-02-27

    Structural and optical properties of low refractive index fluorinated silica (SiO{sub x}C{sub y}F{sub z}) films were investigated. The films were deposited on p-type silicon and polycarbonate substrates by radio frequency plasma enhanced chemical vapor deposition method at low temperatures. A mixture of tetraethoxysilane vapor, oxygen, and CF{sub 4} was used for deposition of the films. The influence of oxygen flow rate on the elemental compositions, chemical bonding states and surface roughness of the films was studied using energy dispersive X-ray analyzer, Fourier transform infrared spectroscopy in reflectance mode and atomic force microscopy, respectively. Effects of chemical bonds of the film matrix on optical properties and chemical stability were discussed. Energy dispersive spectroscopy showed high fluorine content in the SiO{sub x}C{sub y}F{sub z} film matrix which is in the range of 7.6–11.3%. It was concluded that in fluorine content lower than a certain limit, chemical stability of the film enhances, while higher contents of fluorine heighten moisture absorption followed by increasing refractive index. All of the deposited films were highly transparent. Finally, it was found that the refractive index of the SiO{sub x}C{sub y}F{sub z} film was continuously decreased with the increase of the O{sub 2} flow rate down to the minimum value of 1.16 ± 0.01 (at 632.8 nm) having the most ordered and nano-void structure and the least organic impurities. This sample also had the most chemical stability against moisture absorption. - Highlights: • Low deposition temperature and organic precursor led to higher film fluorination. • High fluorine and nanovoid structure led to drastic decrease in the refractive index. • Silica based thin film with ultralow refractive index of 1.16 was produced. • The produced ultralow-n film is highly stable against moisture absorption.

  1. A FORTRAN code for the calculation of probe volume geometry changes in a laser anemometry system caused by window refraction

    Science.gov (United States)

    Owen, Albert K.

    1987-01-01

    A computer code was written which utilizes ray tracing techniques to predict the changes in position and geometry of a laser Doppler velocimeter probe volume resulting from refraction effects. The code predicts the position change, changes in beam crossing angle, and the amount of uncrossing that occur when the beams traverse a region with a changed index of refraction, such as a glass window. The code calculates the changes for flat plate, cylinder, general axisymmetric and general surface windows and is currently operational on a VAX 8600 computer system.

  2. Sol-gel derived titania hybrid thin films with high refractive index

    International Nuclear Information System (INIS)

    Incorporation of metal alkoxides into polymers through sol-gel process is of significant interest for tuning the refractive index of optical materials. In this paper, the organic-inorganic hybrid material with high refractive index (RI) and transparency was studied. Tetrabutoxytitanate (TBOT) and alkoxysilanes including diphenyldimethoxysilane (DPS) and γ-glycidoxypropyl trimethoxysilane (GPTS) were employed as sources of the titania sol and the silica sol, respectively. Two series of titania-based inorganic-organic hybrid materials with and without acetylacetone (AcAc) were prepared using the sol-gel method. Subsequently, crack-free films were fabricated by spin coating. The hybrid films with different Ti content were characterized by various techniques including IR, UV-vis, TG/DSC, SEM and auto-laser ellipsometer. The results indicated that the hybrid films displayed homogeneous morphology and titania was crosslinked with alkoxysilanes. Films without AcAc showed higher optical transparency in the visible region than those containing AcAc. The RI of films without AcAc increased from 1.54 to 1.64 at 633 nm with Ti molar fraction varying from 10 to 70%. Whereas, in the films with AcAc, the refractive indices were higher and unorderly. The study has demonstrated great potential to obtain titania hybrid films with high RI and transparency.

  3. Dispersion engineered silicon nitride waveguides by geometrical and refractive-index optimization

    CERN Document Server

    Boggio, J M Chavez; Fremberg, T; Haynes, R; Roth, M M; Eisermann, R; Lisker, M; Zimmermann, L; Boehm, M

    2014-01-01

    Dispersion engineering in silicon nitride (SiX NY ) waveguides is investigated through the optimization of the waveguide transversal dimensions and refractive indices in a multi-cladding arrangement. Ultra-flat dispersion of -84.0 +/- 0.5 ps/nm/km between 1700 and 2440 nm and 1.5 +/- 3 ps/nm/km between 1670 and 2500 nm is numerically demonstrated. It is shown that typical refractive index fluctuations as well as dimension fluctuations during the fabrication of the SiX NY waveguides are a limitation for obtaining ultra-flat dispersion profiles. Single- and multi-cladding waveguides are fabricated and their dispersion profiles measured (over nearly 1000 nm) using a low-coherence frequency domain interferometric technique. By appropriate thickness optimization, the zero-dispersion wavelength is tuned over a large spectral range in both single-cladding waveguides and multi-cladding waveguides with small refractive index contrast (3 %). A flat dispersion profile with 3.2 ps/nm/km variation over 500 nm is obtained ...

  4. Design of acid-lead battery stage-of-charge detection system based on refractive index detection technology

    Science.gov (United States)

    Chen, Junyao; Yang, Kecheng; Xia, Min; Li, Lei; Zeng, Xianjiang

    2015-10-01

    Based on optical total reflection critical Angle method, we have designed a refractive index measurement system. It adopted a divergent light source and a CCD camera as the occurrence and receiver of the signal. The divergent light source sent out a bunch of tapered beam, exposure to the interface of optical medium and sulfuric acid solution. Light intensity reflected from the interface could be detected by the CCD camera and then sent to the embedded system. In the DSP embedded system, we could obtain the critical edge position through the light intensity distribution curve and converted it to critical angle. Through experiment, we concluded the relation between liquid refractive index and the critical angle edge position. In this system, the detecting precision of the refractive index of sulfuric acid solution reached 10-4. Finally, through the conversion of the refractive index and density, we achieved high accuracy online measurement of electrolyte density in lead-acid battery.

  5. A hybrid algorithm for reengineering the refractive index profile of inhomogeneous coatings from optical in-situ broadband monitoring data

    Institute of Scientific and Technical Information of China (English)

    S.Wilbrandt; O.Stenzel; D.G(a¨)bler; N.Kaiser

    2005-01-01

    Reengineering the refractive index profile of inhomogeneous coatings is a troublesome task. Multiplicity of solutions may significantly reduced by providing additional information. For this reason an in-situ broadband monitoring system was developed to measure the transmittance of the growing film directly at the rotating substrate. For characterization of these coatings, a new model was developed, which significantly reduces the number of parameters. The refractive index profile may be described by a proper number of equally spaced volume fraction values using the Bruggeman effective media approach. A good initial approximation of the refractive index profile can be generated based on deposition rates for both materials recorded with quartz crystal monitor during manufacturing. During the optimization process, a second order minimization algorithm was used to vary the refractive index profile of the whole coating and film thickness of the intermediate stages. Finally, a significantly improved accuracy of the modelled transmittance was achieved.

  6. SYNTHESIS AND CHARACTERIZATION OF FUNCTIONALIZED CARBON BLACK/POLY(VINYL ALCOHOL) HIGH REFRACTIVE INDEX NANOCOMPOSITES

    Institute of Scientific and Technical Information of China (English)

    Peng-fei Xue; Ji-bin Wang; Yu-bin Bao; Qiu-ying Li; Chi-fei Wu

    2012-01-01

    Carbon black (CB)/polymer composites with high refractive index (RI) were fabricated from poly(vinyl alcohol) (PVA) and covalently functionalized nano-CB (PVA-es-CB) by simple esterification reaction.Transmission electron microscopy showed that uniform aggregates of PVA-es-CB nanoparticles with a size smaller than 100 nm formed in the nanocomposite films.Ellipsometric measurements indicated that the PVA-es-CB/PVA composite films had a RI in the range 1.520-1.598 linearly increased with the PVA-es-CB volume content.Theoretical equation based on Lorentz-Lorenz theory provided reasonably close estimation of the refractive indices to the experimentally observed values.The hybrid films also revealed relatively good surface planarity,thermal stability and optical transparency.

  7. Low refractive index gas sensing using a surface plasmon resonance fibre device

    International Nuclear Information System (INIS)

    A series of surface plasmonic fibre devices were fabricated using multiple coatings deposited on a lapped section of a single mode fibre. Coupling from the guided mode to surface plasmons was promoted following UV laser irradiation of the coated region through a phase mask, which generated a surface relief grating structure. The devices showed high spectral sensitivities and strong coupling for low refractive indices as compared to other grating-type fibre devices. The plasmonic devices were used to detect the variation in the refractive indices of alkane gases with measured wavelength and coupling sensitivity to index of 3400 nm RIU−1 and 8300 dB RIU−1, respectively. As a demonstration of the performance of these gas sensors, a minimum concentration of 2% by volume of butane in ethane was achieved

  8. The Cryogenic, High-Accuracy, Refraction Measuring System (CHARMS): A New Facility for Cryogenic Infrared through Vacuum Far-Ultraviolet Refractive Index Measurements

    Science.gov (United States)

    Frey, Bradley J.; Leviton, Douglas B.

    2004-01-01

    The optical designs of future NASA infrared (IR) missions and instruments, such as the James Webb Space Telescope's (JWST) Near-Mixed Camera (NIRCam), will rely on accurate knowledge of the index of refraction of various IR optical materials at cryogenic temperatures. To meet this need, we have developed a Cryogenic, High-Accuracy Refraction Measuring System (CHARMS). In this paper we discuss the completion of the design and construction of CHARMS as well as the engineering details that constrained the final design and hardware implementation. In addition, we will present our first light, cryogenic, IR index of refraction data for LiF, BaF2, and CaF2, and compare our results to previously published data for these materials.

  9. Methods for the measurement of the refractive index of MeV photons using total internal and external reflection

    International Nuclear Information System (INIS)

    Recently it has been theoretically and experimentally shown that for 1-10 MeV and 1-2 MeV photons, respectively, the refractive index of Si is greater than 1. Taking into account the difficulties of the carried out experiment it is proposed to measure directly the refractive index of Si and other materials detecting the total internal and external reflections.

  10. Effect of Refractive Index of Substrate on Fabrication and Optical Properties of Hybrid Au-Ag Triangular Nanoparticle Arrays

    OpenAIRE

    Jing Liu; Yushan Chen; Haoyuan Cai; Xiaoyi Chen; Changwei Li; Cheng-Fu Yang

    2015-01-01

    In this study, the nanosphere lithography (NSL) method was used to fabricate hybrid Au-Ag triangular periodic nanoparticle arrays. The Au-Ag triangular periodic arrays were grown on different substrates, and the effect of the refractive index of substrates on fabrication and optical properties was systematically investigated. At first, the optical spectrum was simulated by the discrete dipole approximation (DDA) numerical method as a function of refractive indexes of substrates and mediums. S...

  11. The effect of lens wear on refractive index of conventional hydrogel and silicone-hydrogel contact lenses : a comparative study

    OpenAIRE

    Lira, Madalena; Santos, Lívia; Azeredo, Joana; Yebra-Pimentel Vilar, Eva; Oliveira, M. Elisabete

    2008-01-01

    Purpose: The purpose of this work was to evaluate the ability of four silicone-hydrogel contact lenses (galyfilcon A, balafilcon A, lotrafilcon A and lotrafilcon B) to retain their equilibrium water content before and after wear, through measurements of refractive index and compare with that of a conventional disposable hydrogel contact lens (etafilcon A). Methods: The refractive indices of 115 contact lenses were measured using an automated refractometer (CLR 12-70, Index Instrument...

  12. A proposal of T-structure fiber-optic refractive index sensor based on surface plasmon resonance

    Science.gov (United States)

    Wang, Xiao-Ming; Zhao, Chun-Liu; Wang, Yan-Ru; Jin, Shangzhong

    2016-06-01

    We present a compact and novel "T" structure optical fiber refractive index sensor proposal based on surface plasmon resonance. "T" structure sensing head consists of a single mode fiber (SMF) with a plasmonic facet and a cladding partly removed single mode fiber (CPR-SMF) with a gap. The gold film is deposited on the end of SMF instead of the side of the CPR-SMF. The simulation results show that the SPR based on the "T" structure can be excited effectively. The SPR transmission spectrum shifts towards longer wavelength with the sensing sample refractive index increasing largely. When we divide the refractive index range of the sensing sample to two parts, the linear relationships between the SPR wavelength and the refractive index can be used. The resolutions can be highly up to 7.115×10-6 RIU and 3.525×10-6 RIU for the refractive index ranges of 1.3333-1.36 and 1.37-1.4, respectively. The proposed "T" structure sensor works well for achieving the refractive index measurement with high sensitivity and wide range for samples with a tiny amount.

  13. Effect of Refractive Index of Substrate on Fabrication and Optical Properties of Hybrid Au-Ag Triangular Nanoparticle Arrays

    Directory of Open Access Journals (Sweden)

    Jing Liu

    2015-05-01

    Full Text Available In this study, the nanosphere lithography (NSL method was used to fabricate hybrid Au-Ag triangular periodic nanoparticle arrays. The Au-Ag triangular periodic arrays were grown on different substrates, and the effect of the refractive index of substrates on fabrication and optical properties was systematically investigated. At first, the optical spectrum was simulated by the discrete dipole approximation (DDA numerical method as a function of refractive indexes of substrates and mediums. Simulation results showed that as the substrates had the refractive indexes of 1.43 (quartz and 1.68 (SF5 glass, the nanoparticle arrays would have better refractive index sensitivity (RIS and figure of merit (FOM. Simulation results also showed that the peak wavelength of the extinction spectra had a red shift when the medium’s refractive index n increased. The experimental results also demonstrated that when refractive indexes of substrates were 1.43 and 1.68, the nanoparticle arrays and substrate had better adhesive ability. Meanwhile, we found the nanoparticles formed a large-scale monolayer array with the hexagonally close-packed structure. Finally, the hybrid Au-Ag triangular nanoparticle arrays were fabricated on quartz and SF5 glass substrates and their experiment extinction spectra were compared with the simulated results.

  14. Commercial scale fabrication method for fabricating a gradient refractive-index rod: Overcoming volume shrinkage and chemical restrictions.

    Science.gov (United States)

    Cho, Hansol; Son, Young Mok; Kim, Mu Gyeom; Ra, Byoung Joo; Park, Joon-Yong; Lee, Seung Hui; Choi, Jin Sung; Song, Min Young; Park, O Ok; Kim, Youn Cheol; Hwang, Jin Taek

    2006-10-01

    We report a fabrication method for a gradient refractive-index polymeric object from a binary comonomer system, regardless of the monomers' reactivity ratio and the molar volume criteria of gradient refractive-index development. To fabricate a large gradient refractive-index rod consisting of a methyl methacrylate and 2,2,3,3-tetrafluoropropyl methacrylate comonomer pair that has not been used for fabrication of a copolymer gradient refractive-index rod by previous conventional methods because of chemical restrictions in molar volume and reactivity ratio difference, we use the so-called successive UV polymerization in a controlled radial volume in conjunction with an automatic refill reactor. Simultaneously and automatically, the volume shrinkage problem, an inevitable shortcoming for the fabrication of a large polymeric object in a commercial production scale, is overcome and exploited. The theoretical features of the refractive-index profile generation of this method are also compared with those of conventional methods for which the chemical restrictions of monomers are crucial for the shape of a refractive-index profile. PMID:16983409

  15. Refractive index of thin films realized by Satisloh SP reactive sputtering system

    Science.gov (United States)

    Monaco, Gianni; Colautti, Arturo; Allegro, Cristina; Godin, Tom; Gold, Steffan; Witzany, Michael

    2013-09-01

    Pulsed DC reactive sputtering is a very interesting technique for coating applications. Reactive sputtering can give very dense layers, low stress of the deposited multilayer film, high reproducibility, very high hardness (up to 1200 Vickers hardness) with unbeatable high rates ideal for industrial applications. SP-100 is Satisloh reactive sputtering systems with only one target material but can deposit various film materials simply by using different gases such as argon, as well as the reactive gases nitrogen and oxygen. Silicon-oxides, silicon-nitrides and all kinds of silicon-oxy-nitrides (SiOx-SixOyNz-SixNy) with a refractive index range of 1.44-2.05 in the visible range can be obtained. In the reactive sputtering the material it is usually deposited in the so called "transition mode" where it must be found the correct equilibrium point between the target voltage and the reactive gas flow. The transition mode assures a dense film with a stable rate. Condition to find such equilibrium point is given by the so called "material hysteresis" in which the target voltage is depicted in function of the reactive gas voltage. The hysteresis and the consequent equilibrium point are strongly depended by the power supplied to the target and the inert gas (argon) flow which could affect the optical characteristics and the deposition rate. We checked the refractive indexes of the SiOx and SixNy of very thin (1 QW Optical thickness at 520 nm) and thicker (3, 5 and 9 QW @520 nm) reporting how the different conditions can affect the refractive index and the deposition rate of the different materials.

  16. A Near-Zero Refractive Index Meta-Surface Structure for Antenna Performance Improvement

    OpenAIRE

    Mohammad Habib Ullah; Mohammad Rashed Iqbal Faruque; Mohammad Tariqul Islam

    2013-01-01

    A new meta-surface structure (MSS) with a near-zero refractive index (NZRI) is proposed to enhance the performance of a square loop antenna array. The main challenge to improve the antenna performance is increment of the overall antenna volume that is mitigated by assimilating the planar NZRI MSS at the back of the antenna structure. The proposed NZRI MSS-loaded CPW-fed (Co-Planar Waveguide) four-element array antenna is designed on ceramic-bioplastic-ceramic sandwich substrate using high-fre...

  17. Oscillation of spatial solitons in a waveguide with a symmetrical refractive index profile

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Dynamics of (1+1)D spatial solitons in a Kerr medium with a transversely symmetrical refractive index profile is investigated. Propagation of solitons is analysed theoretically by using an effective-particle approach. Analytical results show that the soliton oscillates periodically with a variable acceleration. The expression of oscillatory period is derived by introducing a concept of 'average acceleration'. Both acceleration and oscillatory period are determined by the parameters of the input soliton and the waveguide. Propagations of solitons are simulated numerically and good agreement is obtained between the theoretical and numerical results.

  18. Precision positioning with suppression of the influence of refractive index of air

    Czech Academy of Sciences Publication Activity Database

    Holá, Miroslava; Hrabina, Jan; Oulehla, Jindřich; Čížek, Martin; Mikel, Břetislav; Řeřucha, Šimon; Buchta, Zdeněk; Číp, Ondřej; Lazar, Josef

    Bellingham : SPIE, 2013, 878831:1-7. ISBN 978-0-8194-9604-1. [Optical Measurement Systems for Industrial Inspection /8./. Munich (DE), 13.05.2013-16.05.2013] R&D Projects: GA ČR GA102/09/1276; GA ČR GPP102/11/P820; GA TA ČR TA02010711; GA TA ČR TE01020233; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : nanometrology * refractometry * interferometry * refractive index * nanoscale Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  19. Active modulation of refractive index by stress in the terahertz frequency range: erratum.

    Science.gov (United States)

    Song, Wei; Wang, Zhiyong

    2016-03-20

    A previous paper [Appl. Opt.52, 6364 (2013)APOPAI0003-693510.1364/AO.52.006364] presented experimental work on the stress-optical effect in the terahertz frequency range. Although the theoretical model of experimental measurement is correct, there are two errors in the original version. As a result, the presented experimentally measured value of the refractive index-stress coefficient A of polytetrafluoroethylene (PTFE) is erroneous. This erratum points out the errors in the original paper and reports the correct values. PMID:27140555

  20. Quantitative Mass Density Image Reconstructed from the Complex X-Ray Refractive Index

    OpenAIRE

    Mukaide, Taihei; Iida, Atsuo; Watanabe, Masatoshi; Takada, Kazuhiro; Noma, Takashi

    2015-01-01

    We demonstrate a new analytical X-ray computed tomography technique for visualizing and quantifying the mass density of materials comprised of low atomic number elements with unknown atomic ratios. The mass density was obtained from the experimentally observed ratio of the imaginary and real parts of the complex X-ray refractive index. An empirical linear relationship between the X-ray mass attenuation coefficient of the materials and X-ray energy was found for X-ray energies between 8 keV an...

  1. Phase thickness approach for determination of thin film refractive index dispersion from transmittance spectra

    Science.gov (United States)

    Nenkov, M. R.; Pencheva, T. G.

    2008-06-01

    A novel approach for determination of refractive index dispersion n(λ ) and thickness d of thin films of negligible absorption and weak dispersion is proposed. The calculation procedure is based on determination of the phase thickness of the film in the spectral region of measured transmittance data. All points of measured spectra are included in the calculations. Barium titanate and titanium oxide thin films are investigated and their n(λ ) and d are calculated. The approach is validated using Swanepoel's method and it is found to be applicable for relatively thinner films when measured transmittance spectra have one minimum and one maximum only.

  2. Highly sensitive fiber refractive index sensor based on side-core holey structure

    International Nuclear Information System (INIS)

    We propose a side-core holey fiber (SCHF)-based surface plasmon resonance (SPR) sensor to achieve high refractive index (RI) sensitivity. The SCHF structure can facilitate analyte filling and enhance the overlapping area of the core mode and surface plasmon polariton (SPP) mode. The coupling properties of the sensor are analyzed by numerical simulation. The maximum sensitivity of 5000 nm/RIU in an RI range of 1.33–1.44, and the average sensitivity of 9295 nm/RIU in an RI range from 1.44 to 1.54 can be obtained. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  3. The anisotropic Kerr nonlinear refractive index of \\beta-BaB_2O_4

    CERN Document Server

    Bache, Morten; Zhou, Binbin; Zeng, Xianglong

    2012-01-01

    We study the anisotropic nature of the Kerr nonlinear response in a \\beta-BaB_2O_4 (BBO) crystal. The focus is on determining the relevant $\\chi^{(3)}$ cubic tensor component in connection with type I cascaded quadratic interaction, which is done by analyzing various experiments in the literature. We correct the data from some of the experiments for contributions from cascading as well as for updated material parameters, and find that the Kerr nonlinear refractive index used to model self-phase modulation in cascading is considerably larger than what has been used to date.

  4. Structural properties of aqueous metoprolol succinate solutions. Density, viscosity, and refractive index at 311 K

    Science.gov (United States)

    Deosarkar, S. D.; Kalyankar, T. M.

    2013-06-01

    Density, viscosity and refractive index of aqueous solutions of metoprolol succinate of different concentrations (0.005-0.05 mol dm-3) were measured at 38°C. Apparent molar volume of resultant solutions were calculated and fitted to the Masson's equation and apparent molar volume at infinite dilution was determined graphically. Viscosity data of solutions has been fitted to the Jone-Dole equation and viscosity A- and B-coefficients were determined graphically. Physicochemical data obtained were discussed in terms of molecular interactions.

  5. Adaptive refinement and selection process through defect localization for reconstructing an inhomogeneous refraction index

    International Nuclear Information System (INIS)

    We consider the iterative reconstruction of both the internal geometry and the values of an inhomogeneous acoustic refraction index through a piecewise constant approximation. In this context, we propose two enhancements intended to reduce the number of parameters used in reconstruction, while preserving accuracy. This is achieved through the use of geometrical information obtained from a previously developed defect localization method. The first enhancement consists of a preliminary selection of relevant parameters, while the second one is an adaptive refinement to enhance precision with a low number of parameters. Each of them is numerically illustrated. (paper)

  6. High refractive index in wurtzite GaP measured from Fabry-Pérot resonances

    Science.gov (United States)

    Assali, S.; van Dam, D.; Haverkort, J. E. M.; Bakkers, E. P. A. M.

    2016-04-01

    We investigate the optical emission of wurtzite GaP/Al0.4Ga0.6P core/shell nanowires (NWs) transferred to a SiOx substrate to demonstrate a high degree of waveguiding of the emitted photoluminescence (PL) signal. By analysing the Fabry-Pérot mode spacing in combination with calculations of the guided modes in the NWs, we calculate a very high refractive index of bulk WZ GaP of 4.2 at a wavelength of 600 nm. The measured quality factors up to 600 indicate the excellent optical quality of the nanowire resonator.

  7. Spatiotemporal collapse in a nonlinear waveguide with a randomly fluctuating refractive index.

    Science.gov (United States)

    Gaididei, Y B; Christiansen, P L

    1998-07-15

    Analytical results, based on the virial theorem and the Furutsu-Novikov theorem, of the spatiotemporal evolution of a pulse in a nonlinear waveguide with a randomly fluctuating refractive index are presented. For initial conditions in which total collapse occurs in a homogeneous waveguide, random fluctuations postpone the collapse. Sufficiently large-amplitude and short-wavelength fluctuations can cause an initially localized pulse to spread instead of contracting. We show that the disorder can be applied to induce a high degree of controllability of the spatiotemporal extent of the pulses in the nonlinear waveguide. PMID:18087437

  8. Refractive index fluctuations in solids: nanoprobing by means of single-molecule spectroscopy

    CERN Document Server

    Anikushina, T A; Gorshelev, A A; Naumov, A V

    2015-01-01

    We suggest a novel approach for probing of local fluctuations of the refractive index $n$ in solids by means of single-molecule (SM) spectroscopy. It is based on the dependence $T_1(n)$ of the effective radiative lifetime $T_1$ of dye centres in solids on $n$ due to the local field effects. Detection of SM zero-phonon lines at ultra-low temperatures gives the values of SM natural spectral linewidth (which is inverse proportional to $T_1$) and makes it possible to reveal the distribution of the local $n$ values in solids. Here we demonstrate this possibility on the example of amorphous polyethylene and polycrystalline naphthalene doped with terrylene.

  9. Sensitive refractive index sensing with tunable sensing range and good operation angle-polarization-tolerance using graphene concentric ring arrays

    International Nuclear Information System (INIS)

    A highly tunable refractive index sensor with excellent performance and good operation angle-polarization-tolerance is proposed and demonstrated numerically by means of the finite element method. The proposed sensor consists of a planar regular array of paired graphene concentric ring resonators sandwiched between a substrate and a sensing medium. Numerical calculation results show that a high sensitivity of 9.59 µm per refractive index unit and figure of merit of 5.82 can be reached for lower sensing medium refractive indices. The introduction of graphene in this sensor can enhance the absorption of biomolecules and make the sensing range actively tunable. Therefore, it can be conveniently used for possible detection of the refractive index variation of gases, liquids or mixed solutions. Also, we predict that a multi-channel sensor can be achieved by introducing several graphene concentric ring resonators into each unit cell of the array. (paper)

  10. Surrogate immiscible liquid pairs with refractive indexes matchable over a wide range of density and viscosity ratios

    Science.gov (United States)

    Saksena, Rajat; Christensen, Kenneth T.; Pearlstein, Arne J.

    2015-08-01

    In liquid-liquid flows, use of optical diagnostics is limited by interphase refractive index mismatch, which leads to optical distortion and complicates data interpretation, and sometimes also by opacity. Both problems can be eliminated using a surrogate pair of immiscible index-matched transparent liquids, whose density and viscosity ratios match corresponding ratios for the original liquid pair. We show that a wide range of density and viscosity ratios is accessible using aqueous solutions of 1,2-propanediol and CsBr (for which index, density, and viscosity are available), and solutions of light and heavy silicone oils and 1-bromooctane (for which we measured the same properties at 119 compositions). For each liquid phase, polynomials in the composition variables, least-squares fitted to index and density and to the logarithm of kinematic viscosity, were used to determine accessible density and viscosity ratios for each matchable index. Index-matched solution pairs can be prepared with density and viscosity ratios equal to those for water-liquid CO2 at 0 °C over a range of pressure (allowing water-liquid CO2 behavior at inconveniently high pressure to be simulated by 1-bar experiments), and for water-crude oil and water-trichloroethylene (avoiding opacity and toxicity problems, respectively), each over a range of temperature. For representative index-matched solutions, equilibration changes index, density, and viscosity only slightly, and mass spectrometry and elemental analysis show that no component of either phase has significant interphase solubility. Finally, procedures are described for iteratively reducing the residual index mismatch in surrogate solution pairs prepared on the basis of approximate polynomial fits to experimental data, and for systematically dealing with nonzero interphase solubility.

  11. Development of a single crystal with a high index of refraction

    International Nuclear Information System (INIS)

    Time-of-flight Positron emission tomography (TOF-PET) is one of the next-generation medical imaging methods, which requires scintillators with a very short decay time. However, the shortest scintillation decay times are typically 20–30 ns, and these values are not sufficient for TOF-PET. Cherenkov counters are used in high energy physics and they are expected to be applied in medical imaging due to their short decay time. Here, high-refractive index materials are necessary for Cherenkov radiators to reach a high light output. We measured refractive indices of Gd3Ga5O12 (GGG), Y3Ga5O12 (YGG) and Lu3Ga5O12 (LuGG) crystals grown by a micro-pulling-down (μ-PD) method. The GGG, YGG and LuGG crystals were found to have refractive indices of ∼2.5, ∼2.3 and ∼2.3 at 400 nm, respectively. Then we grew a 40 mm diameter GGG crystal by the Czochralski method, and the emission decay times of the GGG crystals irradiated with muons and gamma rays were 10±1ns and 10±2ns, respectively, using a photomultiplier tube (Hamamatsu R6231-100). Cherenkov light of the GGG crystal could be observed for the gamma-ray irradiation

  12. Development of a single crystal with a high index of refraction

    Energy Technology Data Exchange (ETDEWEB)

    Kurosawa, Shunsuke, E-mail: kurosawa@imr.tohoku.ac.jp [Institute for Materials Research, Tohoku University, Sendai (Japan); New Industry Creation Hatchery Center (NICHe), Tohoku University, Sendai (Japan); Kochurikhin, Vladimir V. [General Physics Institute, Moscow (Russian Federation); Yamaji, Akihiro [Institute for Materials Research, Tohoku University, Sendai (Japan); Yokota, Yuui [New Industry Creation Hatchery Center (NICHe), Tohoku University, Sendai (Japan); Kubo, Hidetoshi; Tanimori, Toru [Department of Physics, Kyoto University, Kyoto (Japan); Yoshikawa, Akira [Institute for Materials Research, Tohoku University, Sendai (Japan); New Industry Creation Hatchery Center (NICHe), Tohoku University, Sendai (Japan)

    2013-12-21

    Time-of-flight Positron emission tomography (TOF-PET) is one of the next-generation medical imaging methods, which requires scintillators with a very short decay time. However, the shortest scintillation decay times are typically 20–30 ns, and these values are not sufficient for TOF-PET. Cherenkov counters are used in high energy physics and they are expected to be applied in medical imaging due to their short decay time. Here, high-refractive index materials are necessary for Cherenkov radiators to reach a high light output. We measured refractive indices of Gd{sub 3}Ga{sub 5}O{sub 12} (GGG), Y{sub 3}Ga{sub 5}O{sub 12} (YGG) and Lu{sub 3}Ga{sub 5}O{sub 12} (LuGG) crystals grown by a micro-pulling-down (μ-PD) method. The GGG, YGG and LuGG crystals were found to have refractive indices of ∼2.5, ∼2.3 and ∼2.3 at 400 nm, respectively. Then we grew a 40 mm diameter GGG crystal by the Czochralski method, and the emission decay times of the GGG crystals irradiated with muons and gamma rays were 10±1ns and 10±2ns, respectively, using a photomultiplier tube (Hamamatsu R6231-100). Cherenkov light of the GGG crystal could be observed for the gamma-ray irradiation.

  13. Thermodynamic study of three pharmacologically significant drugs: Density, viscosity, and refractive index measurements at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, Muhammad Javed [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan)], E-mail: mjiqauchem@yahoo.com; Chaudhry, Mansoora Ahmed [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

    2009-02-15

    Measurements of density, viscosity, and refractive index of three pharmacologically significant drugs, i.e. diclofenac sodium, cetrizine, and doxycycline have been carried in aqueous medium at T = (293.15 to 313.15) K. An automated vibrating-tube densimeter, viscometer, and refractometer are used in a concentration range from (7.5) . 10{sup -3} to 25 . 10{sup -3}) mol . kg{sup -1}. The precise density results are used to evaluate the apparent molar volume, partial molar volume, thermal expansion coefficient, partial molar expansivity, and the Hepler's constant. Viscosity results are used to calculate the Jones-Dole viscosity B-coefficient, free energy of activation of the solute and solvent, activation enthalpy, and activation entropy. The molar refractive indices of the drug solutions can be employed to calculate molar refraction. It is inferred from these results that the above mentioned drugs act as structure-making compounds due to hydrophobic hydration of the molecules in the drugs.

  14. Development of Negative Index of Refraction Metamaterials with Split Ring Resonators and Wires for RF Lens Applications

    Science.gov (United States)

    Parazzoli, Claudio G.; Greegor, Robert B.; Tanielian, M. H.

    Metamaterials are engineered ring and wire composites whose response to an incident electromagnetic wave can be described by an effective negative dielectric permittivity ɛ and magnetic permeability μ. Simultaneous negative ɛ and μ within a given frequency band of a metamaterial gives rise to a negative index of refraction n. This has been demonstrated via a Snell's law experiment. The electromagnetic properties of many metamaterial structures in the microwave region are investigated through numerical simulations and experiments. A negative index of refraction, n, allows lenses with reduced primary (Seidel) aberrations compared to equivalent positive index lens. This is demonstrated both for cylindrical lenses and spherical lenses, as well as for the gradient index lenses. Detailed field maps of the focal region of the metamaterials lenses are made and compared to a comparable positive index of refraction lens.

  15. Infrared Refractive Index of Silicon: Parity and Sum-Rule Tests

    Science.gov (United States)

    Karstens, William; Inokuti, Mitio; Smith, David Y.

    2012-02-01

    We have resolved conflicting reports for the IR refractive index of silicon using general considerations of linear response theory. We find that use of unphysical series expansions in the analysis of channel spectra has been a significant source of systematic error. Recognition that the index is an even function of photon energy is crucial for analysis of these measurements and clarifies data presentation. In the region of high IR transparency of elemental semiconductors, the index may be expanded in a rapidly convergent Taylor series. Coefficients of terms in the (2n)^th power of energy are proportional to the (2n+1)^th inverse moment of the electronic absorption spectrum. In the favorable case of intrinsic Si, the electronic absorption is sufficiently well known that independent values of the intercept, slope and curvature of plots of index vs. the square of photon energy may be calculated. Index data sets with parameters significantly different from these suffer from systematic errors or refer to impure samples. Using these parity and sum-rule tests we have prepared a composite index data set for intrinsic silicon that represents a best fit to reliable measurements from microwaves to the visible. Applications to germanium and diamond will be discussed.

  16. Determination of refractive index variation of a glass-integrated optical waveguide by the acousto-optic effect

    International Nuclear Information System (INIS)

    Ion exchange on a glass substrate is now a well-known technology that enables the realization of optical waveguide devices. In recent years, the hybridization of ion-exchanged glass waveguides has become a promising method for functional integration. In this context, an integrated Mach–Zehnder interferometer (MZI), made by ion exchange on a glass substrate, was used to realize an acousto-optic modulator. Over one arm of the MZI a PZT ceramic driven by a high-voltage signal was glued. The acoustic waves cross the light waveguide and locally modify the refractive index of the glass. The optical intensity observed at the output of the interferometer varies according to the piezoelectric ceramic excitation. This component is used to find the relation between the refractive index change induced and the applied stress. Measurements were made for two linear polarizations: TE and TM. The proposed method was validated on a specific glass substrate and can be directly extended to any kind of glass

  17. A Sensitivity-Enhanced Refractive Index Sensor Using a Single-Mode Thin-Core Fiber Incorporating an Abrupt Taper

    Directory of Open Access Journals (Sweden)

    Jie Shi

    2012-04-01

    Full Text Available A sensitivity-enhanced fiber-optic refractive index (RI sensor based on a tapered single-mode thin-core diameter fiber is proposed and experimentally demonstrated. The sensor head is formed by splicing a section of tapered thin-core diameter fiber (TCF between two sections of single-mode fibers (SMFs. The cladding modes are excited at the first SMF-TCF interface, and then interfere with the core mode at the second interface, thus forming an inter-modal interferometer (IMI. An abrupt taper (tens of micrometers long made by the electric-arc-heating method is utilized, and plays an important role in improving sensing sensitivity. The whole manufacture process only involves fiber splicing and tapering, and all the fabrication process can be achieved by a commercial fiber fusion splicer. Using glycerol and water mixture solution as an example, the experimental results show that the refractive index sensitivity is measured to be 0.591 nm for 1% change of surrounding RI. The proposed sensor structure features simple structure, low cost, easy fabrication, and high sensitivity.

  18. A new method for measuring the imaginary part of refractive index structure parameter in the urban surface layer

    Directory of Open Access Journals (Sweden)

    R. Yuan

    2014-08-01

    Full Text Available Atmospheric refractive index consists of both the real and the imaginary parts. The intensity of refractive index fluctuation is usually expressed as the refractive index structure parameter, whose real part reflects the strength of the atmospheric turbulence while the imaginary part reflects the absorption in the light path. The large aperture scintillometer (LAS is often used to measure the structure parameter of the real part of atmospheric refractive index, and the sensible and latent heat fluxes can further be obtained, while the influence of the imaginary part is ignored, or thought to be a noise. Based on the expression for the spectrum of the logarithmic light intensity fluctuation caused by the imaginary part of refractive index, new expressions for the logarithmic intensity fluctuation variance and the structure function related to the imaginary part of refractive index are derived. Then a simple expression for the imaginary part of the atmospheric refractive index structure parameter (ARISP is obtained. It can be conveniently used to measure the imaginary part of the ARISP from LAS. Experiments of light propagation were performed in the urban surface layer and the imaginary part of the ARISP was calculated. The experimental results showed a good agreement with the presented theory. The results also suggested that, the imaginary part of ARISP shows a different variation from the real part of ARISP. For the light with the wavelength of 0.62 μm, the variation of the imaginary part of ARISP is related to both the turbulent transport process and the spatial distribution characteristics of aerosols. Based on the theoretical analysis, it can be expected that the method presented in this study can be applied to measuring the imaginary part of the ARISP caused by the trace gas, if the light wavelength is selected within the corresponding gas absorption region.

  19. Nonlinear refractive index measurements and self-action effects in Roselle-Hibiscus Sabdariffa solutions

    Science.gov (United States)

    Henari, F. Z.; Al-Saie, A.

    2006-12-01

    We report the observation of self-action phenomena, such as self-focusing, self-defocusing, self-phase modulation and beam fanning in Roselle-Hibiscus Sabdariffa solutions. This material is found to be a new type of natural nonlinear media, and the nonlinear reflective index coefficient has been determined using a Z-scan technique and by measuring the critical power for the self-trapping effect. Z-scan measurements show that this material has a large negative nonlinear refractive index, n 2 = 1 × 10-4 esu. A comparison between the experimental n 2 values and the calculated thermal value for n 2 suggests that the major contribution to nonlinear response is of thermal origin.

  20. Conical photonic crystals for enhancing light extraction efficiency from high refractive index materials.

    Science.gov (United States)

    Kim, Jeong-Gil; Hsieh, Chih-Hung; Choi, Hyungryul J; Gardener, Jules; Singh, Bipin; Knapitsch, Arno; Lecoq, Paul; Barbastathis, George

    2015-08-24

    We propose, analyze and optimize a two-dimensional conical photonic crystal geometry to enhance light extraction from a high refractive index material, such as an inorganic scintillator. The conical geometry suppresses Fresnel reflections at an optical interface due to adiabatic impedance matching from a gradient index effect. The periodic array of cone structures with a pitch larger than the wavelength of light diffracts light into higher-order modes with different propagating angles, enabling certain photons to overcome total internal reflection (TIR). The numerical simulation shows simultaneous light yield gains relative to a flat surface both below and above the critical angle and how key parameters affect the light extraction efficiency. Our optimized design provides a 46% gain in light yield when the conical photonic crystals are coated on an LSO (cerium-doped lutetium oxyorthosilicate) scintillator. PMID:26368241

  1. Single-mode D-shaped optical fiber sensor for the refractive index monitoring of liquid

    Science.gov (United States)

    Qazi, Hummad Habib; Mohammad, Abu Bakar bin; Ahmad, Harith; Zamani Zulkifli, Mohd; Wadi Harun, Sulaiman

    2016-04-01

    A new fabrication method is introduced for the production of D-shaped optical fiber. A mechanical end and edge polishing system with aluminum oxide polishing film is utilized to perform sequential polishing on one side (lengthwise) of single-mode optical fiber in order to obtain a D-shaped cross section. Adjusting specific mechanical parameters allows for control of the volume of the D-shaped zone, while the fiber surface smoothness is governed by selection of polishing film grit size. To meet the accuracy and repeatability requirements, optical power loss is monitored during the entire polishing process in situ and in real time. This proposed technique possesses advantages of rapidity, safety, simplicity, repeatability and stability with high precision in comparison with contemporary methods for production. Sensor performance tests on the fiber reveal a linear response with linearity up to R2 = 0.984 for surrounding refractive index in the range of 1.320-1.342 refractive index, which corresponds to different concentrations of the glucose solution test environment. The produced D-shaped optical fiber has potential sensing and monitoring applications in chemical, environmental, biological and biochemical fields.

  2. Differential refractive index sensor based on photonic molecules and defect cavities

    Science.gov (United States)

    Andueza, Ángel; Pérez-Conde, Jesús; Sevilla, Joaquín

    2016-08-01

    We present a novel differential refractive index sensor based on arrays of photonic molecules (PM) of dielectric cylinders and two structural defect cavities. The transmission spectrum of the photonic proposed structure as sensor shows a wide photonic stop band with two localized states. One of them, the reference state, is bound to a decagonal ring of cylinders and the other, the sensing state, to the defect cavities of the lattice. It is shown that defect mode is very sensitive to the presence of materials with dielectric permittivity different from that of the surrounding cylinders while the state in the PM is not affected by their presence. This behavior allows to design a device for sensing applications. A prototype of the sensor, in the microwave region, was built using a matrix of 3x2 PM arrays made of soda-lime glass cylinders (dielectric permittivity of 4.5). The transmission spectra was measured in the microwave range (8-12 GHz) with samples of different refractive index inserted in the defect cavities. Simulations with Finite Integration time-domain Method are in good agreement with experiments. We find that the response of the sensor is linear. Device measurement range is determined by the dielectric constant of the cylinders that make up the device. The results here presented in the microwave region can be extrapolated to the visible range due to scale invariance of Maxwell equations. This make our prototype a promising structure as sensor also in the optical range.

  3. Making the invisible visible: a microfluidic chip using a low refractive index polymer.

    Science.gov (United States)

    Hanada, Yasutaka; Ogawa, Tatsuya; Koike, Kazuhiko; Sugioka, Koji

    2016-07-01

    Microfluidic frameworks known as micro-total-analysis-systems or lab-on-a-chip have become versatile tools in cell biology research, since functional biochips are able to streamline dynamic observations of various cells. Glass or polymers are generally used as the substrate due to their high transparency, chemical stability and cost-effectiveness. However, these materials are not well suited for the microscopic observation of cell migration at the fluid boundary due to the refractive index mismatch between the medium and the biochip material. For this reason, we have developed a new method of fabricating three-dimensional (3D) microfluidic chips made of the low refractive index fluoric polymer CYTOP. This novel fabrication procedure involves the use of a femtosecond laser for direct writing, followed by wet etching with a dilute fluorinated solvent and annealing, to create high-quality 3D microfluidic chips inside a polymer substrate. A microfluidic chip made in this manner enabled us to more clearly observe the flagellum motion of a Dinoflagellate moving in circles near the fluid surface compared to the observations possible using conventional microfluidic chips. We believe that CYTOP microfluidic chips made using this new method may allow more detailed analysis of various cell migrations near solid boundaries. PMID:27265196

  4. Measurement of nonlinear refractive index in open-aperture -scan experiments

    Indian Academy of Sciences (India)

    Ritwick Das; Mukesh Kumar Shukla

    2014-12-01

    We present an experimental study on measurement of nonlinear refractive index (2) of organic liquids when the thermo-optic effects manifest into large nonlinear phase shifts ($_0$) in an open-aperture -scan configuration. Although we do not obtain the familiar peak–valley normalized transmittance curve as in the case of closed-aperture -scan technique, we use a theoretical model using Gaussian beam decomposition (GD) technique to estimate the value of 2. Using this recipe, we obtain the nonlinear refractive index 2 = −(4.90 ± 1.20) × 10−15 cm2/W for toluene (organic solvent) and 2 = −(10.60 ± 2.10) × 10−15 cm2/W for an organic polymer solution (10−4 Min toluene). By carrying out absorption measurements directly with an unfocussed Gaussian beam, we found nonlinear absorptions tol = (2.42 ± 0.20) × 10−13 m/W and poly = (2.79 ± 0.24) × 10−13 m/W which are close to the expected results.

  5. TCF-MMF-TCF fiber structure based interferometer for refractive index sensing

    Science.gov (United States)

    Fu, Haiwei; Li, Huidong; Shao, Min; Zhao, Na; Liu, Yinggang; Li, Yan; Yan, Xu; Liu, Qinpeng

    2015-06-01

    A liquid refractive index (RI) sensor based on in-fiber Mach-Zehnder interferometer (MZI) by sandwiching multi-mode fiber (MMF) between two short sections of thinned core fiber (TCF) is proposed in this paper. The first section of TCF excites the high-order modes and the second section TCF couples the core mode and high-order modes into lead-out SMF to form intermodal interference. The sensor with MMF length of 20 mm and TCFs length of 1 mm was fabricated. The transmission spectrum variation of the sensor with respect to surrounding refractive index (SRI) has been studied by experiment. The results show that the central wavelength of dips/peaks shifting had a good linearity with SRI. The RI sensitivity of the sensor is 130.00 nm/RIU over the RI range of 1.3333-1.4182. The RI sensitivity increase to 433.60 nm/RIU after etching the MMF cladding of the sensor. The sensor keeps low dependence on temperature before and after etching.

  6. Fabrication of Refractive Index Tunable Polydimethylsiloxane Photonic Crystal for Biosensor Application

    Science.gov (United States)

    Raman, Karthik; Murthy, T. R. Srinivasa; Hegde, G. M.

    Photonic crystal based nanostructures are expected to play a significant role in next generation nanophotonic devices. Recent developments in two-dimensional (2D) photonic crystal based devices have created widespread interest as such planar photonic structures are compatible with conventional microelectronic and photonic devices. Various optical components such as waveguides, resonators, modulators and demultiplexers have been designed and fabricated based on 2D photonic crystal geometry. This paper presents the fabrication of refractive index tunable Polydimethylsiloxane (PDMS) polymer based photonic crystals. The advantages of using PDMS are mainly its chemical stability, bio-compatibility and the stack reduces sidewall roughness scattering. The PDMS structure with square lattice was fabricated by using silicon substrate patterned with SU8-2002 resist. The 600 nm period grating of PDMS is then fabricated using Nano-imprinting. In addition, the refractive index of PDMS is modified using certain additive materials. The resulting photonic crystals are suitable for application in photonic integrated circuits and biological applications such as filters, cavities or microlaser waveguides.

  7. Time variation of adipose tissue refractive index under photodynamic treatment: in vitro study using OCT

    Science.gov (United States)

    Yanina, Irina Yu.; Trunina, Natalia A.; Tuchin, Valery V.

    2012-03-01

    Time variation of the adipose tissue refractive index under photodynamic treatment was studied using OCT. Fat tissue slices 200-500 μm thick were used in in vitro experiments. To stain the fat tissue we used water-ethanol solutions of indocyanine green (ICG) and brilliant green (BG) with the concentration 1 mg/ml and 6 mg/ml, respectively. The CW laser diode (VD-VII DPSS, 808 nm) and the dental diode irradiator Ultra Lume Led 5 (442 and 597 nm) were used for irradiation of tissue slices. The irradiation time was 5 min for the laser and 15 min for the diode lamp. The experiments were carried out at room temperature. It was discovered the immersion optical clearing of fat tissue slices due to fat cell lipolysis under photodynamic treatment. Released cell content works as an immersion agent, thus the relative refractive index of tissue scatterers decreasing with the time elapsed after the treatment. These data support the hypothesis that photodynamic treatment induces fat cell lipolysis for some period after treatment.

  8. Report on supplementary comparison COOMET.PR-S3: refractive index

    Science.gov (United States)

    Vishnyakov, G. N.; Fricke, A.; Parkhomenko, N. M.; Hori, Y.; Pisani, M.

    2016-01-01

    The Supplementary Comparison COOMET.PR-S3 was carried out to ensure the correctness and comparability of refractive index of solid transparent materials in visible spectral range measured by the participants of the comparison within the uncertainties claimed for their measuring facility. COOMET.PR-S3 was conducted within the Regional Metrology Organization (RMO) "Euro-Asian Cooperation of National Metrological Institutions" known as COOMET, and has the RMO project number of 438/RU/08. The Comparison was piloted by the All-Russian Research Institute for Optical and Physical Measurements (VNIIOFI). Five NMIs from three RMOs (COOMET, EURAMET and APMP) participated in the comparison. This report describes the measurement results of three prismatic samples made of different types of glass. Three participants, VNIIOFI, PTB and Ukrmetrteststandart have made measurements of the refractive index at the wavelengths of 480 nm, 509 nm, 546 nm, 589.3 nm, 644 nm, and three participants, VNIIOFI, INRiM and AIST at the wavelength of 632.8 nm. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCPR, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  9. Measurement of nonlinear refractive index of organic materials by z-scan

    Science.gov (United States)

    Fontalvo, M.; Garcia, A.; Valbuena, S.; Racedo, F.

    2016-02-01

    The nonlinear effects characterization by using the Z-Scan transmission technique in many materials has generated great in forest according to the technological necessities. The majority part of the nonlinear effects can be described by the classic electromagnetic theory, with the electrical susceptibility in the constitutive equation that relates the electrical polarization with the electrical field. In this work the sign and refractive index magnitude and the nonlinear absorption coefficient of the following organic substance were determined: methylene-blue, rodamine LD, vegetable powder and gentian violet a hundred percent pure dissolved in isopropyl alcohol, a laser Nd: YAG was used as a source excitation. The bunch of laser was focused with a lens of ten centimeters of focal length; by using a displacement system the sweeping of twenty centimeters was realized. The following results of the normalized curves of the transmittance in function of the z position were obtained applying the Sheik- Bahae theory: The nonlinear refractive index of the dye shows an increase in function of its concentration and the power of exciting of the laser with negative nonlinear sign in the majority of the sample.

  10. Surface Plasmon Scattering in Exposed Core Optical Fiber for Enhanced Resolution Refractive Index Sensing.

    Science.gov (United States)

    Klantsataya, Elizaveta; François, Alexandre; Ebendorff-Heidepriem, Heike; Hoffmann, Peter; Monro, Tanya M

    2015-01-01

    Refractometric sensors based on optical excitation of surface plasmons on the side of an optical fiber is an established sensing architecture that has enabled laboratory demonstrations of cost effective portable devices for biological and chemical applications. Here we report a Surface Plasmon Resonance (SPR) configuration realized in an Exposed Core Microstructured Optical Fiber (ECF) capable of optimizing both sensitivity and resolution. To the best of our knowledge, this is the first demonstration of fabrication of a rough metal coating suitable for spectral interrogation of scattered plasmonic wave using chemical electroless plating technique on a 10 μm diameter exposed core of the ECF. Performance of the sensor in terms of its refractive index sensitivity and full width at half maximum (FWHM) of SPR response is compared to that achieved with an unstructured bare core fiber with 140 μm core diameter. The experimental improvement in FWHM, and therefore the detection limit, is found to be a factor of two (75 nm for ECF in comparison to 150 nm for the large core fiber). Refractive index sensitivity of 1800 nm/RIU was achieved for both fibers in the sensing range of aqueous environment (1.33-1.37) suitable for biosensing applications. PMID:26426022

  11. Surface Plasmon Scattering in Exposed Core Optical Fiber for Enhanced Resolution Refractive Index Sensing

    Directory of Open Access Journals (Sweden)

    Elizaveta Klantsataya

    2015-09-01

    Full Text Available Refractometric sensors based on optical excitation of surface plasmons on the side of an optical fiber is an established sensing architecture that has enabled laboratory demonstrations of cost effective portable devices for biological and chemical applications. Here we report a Surface Plasmon Resonance (SPR configuration realized in an Exposed Core Microstructured Optical Fiber (ECF capable of optimizing both sensitivity and resolution. To the best of our knowledge, this is the first demonstration of fabrication of a rough metal coating suitable for spectral interrogation of scattered plasmonic wave using chemical electroless plating technique on a 10 μm diameter exposed core of the ECF. Performance of the sensor in terms of its refractive index sensitivity and full width at half maximum (FWHM of SPR response is compared to that achieved with an unstructured bare core fiber with 140 μm core diameter. The experimental improvement in FWHM, and therefore the detection limit, is found to be a factor of two (75 nm for ECF in comparison to 150 nm for the large core fiber. Refractive index sensitivity of 1800 nm/RIU was achieved for both fibers in the sensing range of aqueous environment (1.33–1.37 suitable for biosensing applications.

  12. Effective group index of refraction in non-thermal plasma photonic crystals

    International Nuclear Information System (INIS)

    Plasma photonic crystals (PPCs) are periodic arrays that consist of alternate layers of micro-plasma and dielectric. These structures are used to control the propagation of electromagnetic waves. This paper presents a survey of research on the effect of non-thermal plasma with bi-Maxwellian distribution function on one dimensional PPC. A plasma with temperature anisotropy is not in thermodynamic equilibrium and can be described by the bi-Maxwellian distribution function. By using Kronig-Penny's model, the dispersion relation of electromagnetic modes in one dimensional non-thermal PPC (NPPC) is derived. The band structure, group velocity vg, and effective group index of refraction neff(g) of such NPPC structure with TeO2 as the material of dielectric layers have been studied. The concept of negative group velocity and negative neff(g), which indicates an anomalous behaviour of the PPCs, are also observed in the NPPC structures. Our numerical results provide confirmatory evidence that unlike PPCs there are finite group velocity and non-zero effective group indexes of refraction in photonic band gaps (PBGs) that lie in certain ranges of normalized frequency. In other words, inside the PBGs of NPPCs, neff(g) becomes non-zero and photons travel with a finite group velocity. In this special case, this velocity varies alternately between 20c and negative values of the order 103c (c is the speed of light in vacuum)

  13. Broadband opto-electro-mechanical effective refractive index tuning on a chip.

    Science.gov (United States)

    Pruessner, Marcel W; Park, Doweon; Stievater, Todd H; Kozak, Dmitry A; Rabinovich, William S

    2016-06-27

    Photonic integrated circuits have enabled progressively active functionality in compact devices with the potential for large-scale integration. To date the lowest loss photonic circuits are achieved with silica or silicon nitride-based platforms. However, these materials generally lack reconfigurability. In this work we present a platform for achieving active functionality in any dielectric waveguide via large-scale opto-electro-mechanical tuning of the effective refractive index (Δneff≈0.01-0.1) and phase (Δϕ>2π). A suspended microbridge weakly interacts with the evanescent field of a low-mode confinement waveguide to tune the effective refractive index and phase with minimal loss. Metal-coated bridges enable electrostatic actuation to displace the microbridge to dynamically tune nEFF. In a second implementation we place a non-metallized dielectric microbridge in a gradient electric field to achieve actuation and tuning. Both approaches are broadband, universally applicable to any waveguide, and pave the way for adding active functionality to many passive optical materials. PMID:27410554

  14. Band gap and refractive index tunability in thallium based layered mixed crystals

    Energy Technology Data Exchange (ETDEWEB)

    Gasanly, N. M., E-mail: nizami@metu.edu.tr [Department of Physics, Middle East Technical University, Ankara 06800 (Turkey); Virtual International Scientific Research Centre, Baku State University, Baku 1148 (Azerbaijan)

    2015-07-21

    Compositional variation of the band gap energy and refractive index of TlMeX{sub 2}-type (Me = Ga or In and X = S or Se) layered mixed crystals have been studied by the transmission and reflection measurements in the wavelength range of 400–1100 nm. The analysis of absorption data of TlGa{sub 1-x}In{sub x}Se{sub 2}, TlGa(S{sub 1−x}Se{sub x}){sub 2}, TlGa{sub 1−x}In{sub x}S{sub 2}, and TlIn(Se{sub 1−x}S{sub x}){sub 2} mixed crystals revealed the presence of both optical indirect and direct transitions. It was found that the energy band gaps of mixed crystals decrease at the replacing of gallium atoms by indium and of sulfur atoms by selenium ones. Through the similar replacing of atoms (smaller atoms by larger ones) in the studied mixed crystals, the refractive index shows the quite opposite behavior.

  15. Refractive index and wavenumber properties for cyclotron resonant quasilinear diffusion by cold plasma waves

    International Nuclear Information System (INIS)

    Wave-particle interactions have a large effect on magetospheric particles, in the radiation belts and elsewhere. Bounce-averaged quasilinear diffusion coefficients have been calculated for whistler hiss and chorus and electromagnetic ion cyclotron waves (EMIC), which are all believed to play major roles. To perform these calculations efficiently, techniques have been developed that use properties of the refractive index of these modes to identify ranges of wave-normal angle that are compatible with cyclotron resonance in a given frequency band. Other cold plasma waves, in the L-X, L-O, R-X, and Z modes, can also resonate with energetic electrons, and some preliminary calculations of their diffusion coefficients have been reported. Here, it is shown that the refractive index of these modes allows the techniques developed for whistler and EMIC waves to be applied to them as well. Sample calculations are presented for Z mode waves, with ωpe>Ωe and ωpee. It is also observed that for any cold plasma mode, the wavenumber is an increasing function of frequency for a fixed value of wave-normal angle; this is proved algebraically with mild approximations and verified numerically for a very wide range of parameters. This allows a variant of the technique for efficiently calculating diffusion coefficients

  16. A Schrodinger formulation research for light beam propagation through the media of complex refractive index

    Institute of Scientific and Technical Information of China (English)

    刘承宜; 郭弘; 胡巍

    2002-01-01

    The Helmhotz equation of light beam propagating through a medium of complex refractive index is reduced to the axial-coordinate-dependent Schr?dinger equation of complex potential. The new bra vector, the new expectation value of a dynamical variable and the extended Heisenberg picture are defined by the inverse of the evolution operator instead of its Hermitian adjoint, and the complex beam propagation parameters defined in terms of the new expectation value, the complex ABCD law and the ABCD formulation of the Huygens' integral are discussed in terms of quantum mechanics. It is shown that the evolution equations of the complex beam propagation parameters are the same as those of the beam propagation parameters of beam propagating through a medium of real refractive index. The research on an optical system of the conservative complex beam quality factor shows that the complex ABCD law holds, the evolution of its coordinate operator and the momentum operator is linear, and the Huygens' integral is of the ABCD formulation.

  17. Differential Refractive index sensor based on Photonic molecules and defect cavities

    CERN Document Server

    Andueza, Angel; Sevilla, Joaquin

    2016-01-01

    We present a novel differential refractive index sensor based on arrays of photonic molecules (PM) of dielectric cylinders and two structural defect cavities. The transmission spectrum of the photonic proposed structure as sensor shows a wide photonic stop band with two localized states. One of them, the reference state, is bound to a decagonal ring of cylinders and the other, the sensing state, to the defect cavities of the lattice. It is shown that defect mode is very sensitive to the presence of materials with dielectric permittivity different from that of the surrounding cylinders while the state in the PM is not affected by their presence. This behavior allows to design a device for sensing applications. A prototype of the sensor, in the microwave region, was built using a matrix of 3x2 PM arrays made of soda-lime glass cylinders (dielectric permittivity of 4.5). The transmission spectra was measured in the microwave range (8-12 GHz) with samples of different refractive index inserted in the defect cavit...

  18. Low refractive index SiOF thin films prepared by reactive magnetron sputtering

    International Nuclear Information System (INIS)

    We have studied low refractive index fluorine doped silica thin films prepared by reactive magnetron sputtering. Two experimental parameters were varied to increase the porosity of the films, the geometry of the deposition process (i.e., the use of glancing angle deposition) and the presence of chemical etching agents (fluorine species) at the plasma discharge during film growth. The microstructure, chemistry, optical properties, and porosity of the films have been characterized by scanning electron and atomic force microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, UV–vis, and spectroscopic ellipsometry. It is found that either the deposition at glancing angles or the incorporation of CFx species in the plasma discharge during film growth produces a decrease in the refractive index of the deposited films. The combined effect of the two experimental approaches further enhances the porosity of the films. Finally, the films prepared in a glancing geometry exhibit negative uniaxial birefringence. - Highlights: • SiOF thin films with controlled porosity prepared by reactive magnetron sputtering • Incorporation of CFx precursors in the plasma discharge enhances film porosity. • Deposition at glancing geometries further increases void fraction within the films

  19. Fabry-Perot interferometer based on etched side-hole fiber for microfluidic refractive index sensing

    Science.gov (United States)

    Wu, Shengnan; Yan, Guofeng; Zhou, Bin; He, Sailing

    2015-08-01

    In this paper, we present a novel fiber-optic open-cavity Fabry-Perot interferometer (FPI), which is specially designed for microfluidic refractive index (RI) sensing. An etching Side-hole fiber (SHF) was sandwiched between in two single-mode-fibers (SMF) and then a cavity was opened up by chemical etching method in the SHF. The minute order of the etching process endow such FPIs with low cost and ease of fabrication. For further microfluidic sensing test, the FPI was integrated with a cross microfluidic slit that was fabricated through photolithography. The refractive index response of the FPI was characterized using sodium hydroxide solution with RI range from 1.3400 to 1.3470. Experimental results show that FPIs with different length of open-cavity have the similar liner RI response with different RI sensitivities. The optimal RI sensitivity of more than 1138 nm/RI can be achieved with open-cavity length of 56 μm. The temperature response was also investigated, which shows that FPIs exhibit a very low temperature cross-sensitivities of 4.00 pm/ °C and 1.95 pm/ °C corresponding FPIs with cavity length of 123 μm and 56 μm, respectively. Such good performance renders the FPI a promising in-line microfluidic sensor for temperature-insensitive RI sensing.

  20. Quantitative 3D refractive index decrement reconstruction using single-distance phase-contrast tomography data

    International Nuclear Information System (INIS)

    X-ray propagation-based phase-contrast imaging is an attractive phase-sensitive imaging technique that has found applications in many research fields. Here, we report the investigations of a method which can quantitatively reconstruct in 3D the refractive index decrement of a quasi-homogeneous object using single-distance phase-contrast tomography data. The method extends the Born-type approximation phase-retrieval algorithm, which is based on the phase-attenuation duality (ε = δ/β, with constant ε) and suitable for homogeneous objects, to tomography and we study its application to quasi-homogeneous objects. The noise performance and the phase-attenuation duality influences of the method are also investigated. In simulation, the method allows us to quantitatively reconstruct the 3D refractive index decrement for quasi-homogeneous and weakly absorbing samples and it performs well in the practical noise situation. Furthermore, it shows a substantial contrast increase and successfully distinguishes different materials in a quasi-homogeneous and weakly absorbing sample from experimental data, even with inappropriate ε value. (paper)

  1. Simultaneous detection of liquid level and refractive index with a long-period fiber grating based sensor device

    International Nuclear Information System (INIS)

    In this study, a long-period fiber grating (LPFG)-based optical fiber sensor device is proposed for simultaneous detection of liquid level and refractive index (RI). When part of the grating was submerged in an unknown liquid, the resonant wavelength of each cladding mode of the LPFG sensor varied linearly with the submerged length and nonlinearly with the RI of the liquid. By retaining the first-order (sensitivity) and second-order (cross sensitivity) terms of a Taylor expansion of the nonlinear relation, the changes in submerged length (or liquid level) and RI can be simultaneously evaluated from the changes in resonant wavelength of two cladding modes. The sensitivity coefficients to liquid level, RI, their cross effect and environmental effects were studied both analytically and experimentally. The maximum prediction error by the proposed evaluation algorithm was found to be 1 mm for liquid level and 0.005 for RI. (paper)

  2. Posterior corneal curvature changes following Refractive Small Incision Lenticule Extraction

    Directory of Open Access Journals (Sweden)

    Ganesh S

    2015-07-01

    Full Text Available Sri Ganesh, Utsav Patel, Sheetal Brar Phaco and Refractive Surgery Department, Nethradhama Superspeciality Eye Hospital, Bengaluru, Karnataka, India Purpose: To compare the posterior corneal curvature changes, in terms of corneal power and asphercity, following Refractive Small Incision Lenticule Extraction (ReLEx SMILE procedure for low, moderate, and high myopia.Methods: This retrospective, non randomized, comparative, interventional trial; included 52 eyes of 26 patients, divided in three groups: low myopia (myopia ≤3 D [diopters] spherical equivalent [SE], moderate myopia (myopia >3 D and <6 D SE, and high myopia (myopia ≥6 D SE. All patients were treated for myopia and myopic astigmatism using ReLEx SMILE. The eyes were examined pre-operatively and 3 months post-operatively using SCHWIND SIRIUS, a three-dimensional rotating Scheimpflug camera with a Placido disc topographer to assess corneal changes with regard to keratometric power and asphericity of the cornea.Results: A statistically significant increase in mean keratometric power in the 3, 5, and 7 mm zones of the posterior corneal surface compared with its pre-ReLEx SMILE value was detected after 3 months in the moderate myopia group (pre-operative [pre-op] -6.14±0.23, post-operative [post-op] -6.29±0.22, P<0.001 and high myopia group (pre-op -6.19±0.16, post-op -6.4±0.18, P<0.001, but there was no significant change in keratometric power of the posterior surface in the low myopia group (pre-op -5.87±0.17, post-op -6.06±0.29, P=0.143. Asphericity (Q-value of the posterior surface changed significantly (P<0.001 after ReLEx SMILE in the moderate myopia group in the 3, 5, and 7 mm zones, and in the high myopia group in the 3 and 7 mm zones; but there was no significant change in the Q-value in the low myopia group in all three zones (pre-op 0.23±0.43, post-op -0.40±0.71, P=0.170, and in the high myopia group in the 5 mm zone (P=0.228.Conclusion: ReLEx SMILE causes significant

  3. Compression of ultra-short light pulses using the graded refractive index one-dimensional photonic crystals

    Science.gov (United States)

    Shiri, R.; Bananej, A.; Safari, E.

    2016-09-01

    The one-dimensional photonic crystals (1D PCs) containing a graded refractive index layer have been theoretically utilized to compress the positively chirped ultra-short pulses of light. Two types of simple and graded index multi-layer structures consisting alternating layers of TiO2 and SiO2 with the same total thicknesses and periodicity have been investigated and compared. For the graded structure, three different refractive index distributions including linear, exponential and parabolic profiles have been considered. The results revealed that replacing one of the homogeneous layers of the unit cells in simple photonic crystal with a graded material having parabolic refractive index profile efficiently improves compression behavior of the structure. The compress factors of as much as 47% and 78% depending on the pulse's initial chirp rate obtained with parabolic profile of such the structures.

  4. Sensitivity Analysis for Aerosol Refractive Index and Size Distribution Estimation Methods Based on Polarized Atmospheric Irradiance Measurements

    Directory of Open Access Journals (Sweden)

    Kohei Arai

    2014-01-01

    Full Text Available Aerosol refractive index and size distribution estimations based on polarized atmospheric irradiance measurements are proposed together with its application to reflectance based vicarious calibration. A method for reflectance based vicarious calibration with aerosol refractive index and size distribution estimation using atmospheric polarization irradiance data is proposed. It is possible to estimate aerosol refractive index and size distribution with atmospheric polarization irradiance measured with the different observation angles (scattering angles. The Top of the Atmosphere (TOA or at-sensor radiance is estimated based on atmospheric codes with estimated refractive index and size distribution then vicarious calibration coefficient can be calculated by comparing to the acquired visible to near infrared instrument data onboard satellites. The estimated TOA radiance based on the proposed method is compared to that with aureole-meter based approach which is based on refractive index and size distribution estimated with solar direct, diffuse and aureole (Conventional AERONET approach. It is obvious that aureole-meter is not portable, heavy and large while polarization irradiance measurement instruments are light and small (portable size and weight.

  5. Towards refractive index sensitivity of long-period gratings at level of tens of µm per refractive index unit: fiber cladding etching and nano-coating deposition.

    Science.gov (United States)

    Śmietana, Mateusz; Koba, Marcin; Mikulic, Predrag; Bock, Wojtek J

    2016-05-30

    In this work we report experimental results on optimizing the refractive index (RI) sensitivity of long-period gratings (LPGs) by fiber cladding etching and thin aluminum oxide (Al2O3) overlay deposition. The presented LPG takes advantage of work in the dispersion turning point (DTP) regime as well as the mode transition (MT) effect for higher-order cladding modes (LP09 and LP010). The MT was obtained by depositing Al2O3 overlays with single-nanometer precision using the Atomic Layer Deposition method (ALD). Etching of both the overlay and the fiber cladding was performed using hydrofluoric acid (HF). For shallow etching of the cladding, i.e., DTP observed at next = 1.429 and 1.439 RIU for an LPG with no overlay, followed by deposition of an overlay of up to 167 nm in thickness, HF etching allowed for post-deposition fine-tuning of the overlay thickness resulting in a significant increase in RI sensitivity mainly at the DTP of the LP09 cladding mode. However, at an external RI (next) above 1.39 RIU, the DTP of LP010 was noticed, and its RI sensitivity exceeded 9,000 nm/RIU. Deeper etching of the cladding, i.e., DTP observed for next above 1.45 RIU, followed by the deposition of thicker overlays (up to 201 nm in thickness) allowed the sensitivity to reach values of over 40,000 nm/RIU in a narrow RI range. Sensitivity exceeding 20,000 nm/RIU was obtained in an RI range suitable for label-free biosensing applications. PMID:27410112

  6. Refractive-index based tomosynthesis using dark-field imaging optics

    International Nuclear Information System (INIS)

    Tomosynthesis (TS) is a pseudo-3-dimensional image reconstruction method to recover depth-resolved information using restricted number of projections. In this research, refraction index based TS imaging using dark-field imaging (DFI) optics is proposed and biomedical soft tissues were imaged in low dose exposure. By a single exposure of an object, two projected images are obtained from a Laue-case analyzer of DFI. Calculating the both images refraction component is deduced, while two exposures are needed in DEI (diffraction enhanced imaging). Thus the measurement time and the radiation dose in DFI are half of DEI. In addition, the proposed reconstruction algorithm, derived from the quantitative relationship in measurement process, allows high contrast tomographic imaging in spite of one order smaller number of projections for CT (computed tomography). To demonstrate the proposed imaging protocol efficacy, an ex-vivo excised tissue of human lung were imaged using a system constructed at the vertical wiggler beamline at PF-BL14C at KEK. TS image is successfully delineated high quality soft tissue structures comparable to CT.

  7. Local Doppler Effect, Index of Refraction through the Earth Crust, PDF and the CNGS Neutrino Anomaly?

    Directory of Open Access Journals (Sweden)

    Assis A. V. D. B.

    2012-04-01

    Full Text Available In this brief paper, we show the neutrino velocity discrepancy obtained in the OPERA experiment may be due to the local Doppler effect between a local clock attached to a given detector at Gran Sasso, say C G , and the respective instantaneous clock crossing C G , say C C , being this latter at rest in the instantaneous inertial frame having got the velocity of rotation of CERN about Earth’s axis in relation to the fixed stars. With this effect, the index of refraction of the Earth crust may accomplish a refractive effect by which the neutrino velocity through the Earth crust turns out to be small in relation to the speed of light in the empty space, leading to an encrusted discrepancy that may have contamined the data obtained from the block of detectors at Gran Sasso, leading to a time interval excess that did not provide an exact match between the shift of the protons PDF (probability distribution function by TOF c and the detection data at Gran Sasso via the maximum likelihood matching.

  8. Negative Index Refraction in the Complex Ginzburg—Landau Equation in Connection with the Experimental CIMA Reaction

    International Nuclear Information System (INIS)

    In comparison with the phenomenon of negative index refraction observed in artificial meta-materials, it is interesting to ask if this type of behavior also exists or not in reaction-diffusion systems that support nonlinear chemical waves. Previous studies indicate that the negative index refraction could occur on a interface between a medium of a normal wave and a medium that supports anti-waves. Here we investigate the phenomenon in the complex Ginzburg—Landau equation (CGLE) in a close relationship with the quantitative model for the chloriteiodide-malonic acid (CIMA) reaction. The amplitude equation CGLE is deduced from the CIMA reaction, and simulations with mapped parameters from the reaction-diffusion equation reveal that the competition between normal waves and anti-waves on the interface determines whether the negative index refraction occurs or not

  9. Implementation of transformed lenses in bed of nails reducing refractive index maximum value and sub-unity regions.

    Science.gov (United States)

    Prado, Daniel R; Osipov, Andrey V; Quevedo-Teruel, Oscar

    2015-03-15

    Transformation optics with quasi-conformal mapping is applied to design a Generalized Maxwell Fish-eye Lens (GMFEL) which can be used as a power splitter. The flattened focal line obtained as a result of the transformation allows the lens to adapt to planar antenna feeding systems. Moreover, sub-unity refraction index regions are reduced because of the space compression effect of the transformation, reducing the negative impact of removing those regions when implementing the lens. A technique to reduce the maximum value of the refractive index is presented to compensate for its increase because of the transformation. Finally, the lens is implemented with the bed of nails technology, employing a commercial dielectric slab to improve the range of the effective refractive index. The lens was simulated with a 3D full-wave simulator to validate the design, obtaining an original and feasible power splitter based on a dielectric lens. PMID:25768148

  10. The effect of oxygen flow rate on refractive index of aluminum oxide film deposited by electron beam evaporation technique

    Directory of Open Access Journals (Sweden)

    R Shakouri

    2016-02-01

    Full Text Available The effects of oxygen flow rate on refractive index of aluminum oxide film have been investigated. The Al2O3 films are deposited by electron beam on glass substrate at different oxygen flow rates. The substrate was heated to reach  and the temperature was constant during the thin film growth. The transmittance spectrum of samples was recorded in the wavelength 400-800 nm.  Then, using the maxima and minima of transmittance the refractive index and the extinction coefficient of samples were determined. It has been found that if we reduce the oxygen flow, while the evaporation rate is kept constant, the refractive index of Al2O3 films increases. On the other hand, reduced oxygen pressure causes the Al2O3 films to have some absorption.

  11. Refractive index dispersion of chalcogenide glasses for ultra-high numerical-aperture fiber for mid-infrared supercontinuum generation

    DEFF Research Database (Denmark)

    Dantanarayana, Harshana G.; Abdel-Moneim, Nabil; Tang, Zhuoqi; Sojka, Lukasz; Sujecki, Slawomir; Furniss, David; Seddon, Angela B.; Kubat, Irnis; Bang, Ole; Benson, Trevor M.

    2014-01-01

    We select a chalcogenide core glass, AsSe, and cladding glass, GeAsSe, for their disparate refractive indices yet sufficient thermal-compatibility for fabricating step index fiber (SIF) for mid-infrared supercontinuum generation (MIR-SCG). The refractive index dispersion of both bulk glasses is...... measured over the 0.4 μm–33 μm wavelength-range, probing the electronic and vibrational behavior of these glasses. We verify that a two-term Sellmeier model is unique and sufficient to describe the refractive index dispersion over the wavelength range for which the experimentally determined extinction...... coefficient is insignificant. A SIF composed of the glasses is fabricated and calculated to exhibit an ultra-high numerical aperture >0.97 over the entire wavelength range 0.4-33 μm suggesting that the SIF glass pair is a promising candidate for MIR-SCG. Material dispersion characteristics and the zero...

  12. Low hazard refractive index and density-matched fluid for quantitative imaging of concentrated suspensions of particles

    Science.gov (United States)

    Zhu, W.; Knapp, Y.; Deplano, V.

    2016-05-01

    A novel refractive index and density-matched liquid-solid suspension system taking into account chemical hazard and health concerns was developed and characterized. The solid phase is made of PMMA spheres, the refractive index of which being adapted with a mixture of 2,2'-thiodiethanol and phosphate-buffered saline (PBS), while the density is adapted with a mixture of PBS and glycerol. The proposed chemicals present low hazard characteristics in comparison with former solutions. Data collected from density and refractive index measurements of the solid phase and of the different fluid constituents are used to define a specific ternary mixture adapted to commercial grade micron-size particles. The defined mixture is validated in a micron-sized granular flow experiment. The described method can be applied to other low-density solids.

  13. Fiber-optic temperature sensor based on interaction of temperature-dependent refractive index and absorption of germanium film.

    Science.gov (United States)

    Li, Min; Li, Yulin

    2011-01-10

    The interaction of a large temperature-dependent refractive index and a temperature-dependent absorption of semiconductor materials at 1550 nm can be used to build a very sensitive, film coated fiber-optic temperature probe. We developed a sensor model for the optical fiber-germanium film sensor. A temperature sensitivity of reflectivity change of 0.0012/°C, corresponding to 0.1°C considering a moderate signal processing system, over 100°C within the temperature regime of -20°C to 120°C, has been demonstrated by experimental tests of the novel sensor. The potential sensitivity and further applications of the sensor are discussed. PMID:21221150

  14. Mach-Zehnder interferometer by utilizing phase modulation of transmitted light through magnetic fluid films possessing tunable refractive index

    International Nuclear Information System (INIS)

    Due to its diverse applications in photonics, bio-sensors, mechanics, etc., Mach-Zehnder interferometer becomes one of important devices. Hence, lots of efforts have been paid to develop advanced Mach-Zehnder interferometers. In this work, we explore new-model Mach-Zehnder interferometer, in which one of arm is consisted of magnetic fluid films. By utilizing the tunable refractive index of magnetic fluid films under external magnetic fields, the traveling phase of a propagating light through the magnetic fluid film is changed. This could lead to a variation in the interfered intensity of the Mach-Zehnder interferometer when an external magnetic field is applied. The modulation in the interfered intensity by the external magnetic field is demonstrated experimentally, and the relevant physical origin is also discussed

  15. TAKE, development of the refractive index measurement technology for industrial needs; TAKE, taitekerroinmittaustekniikan kehittaeminen teollisuuden tarpeisiin - MPKT 12

    Energy Technology Data Exchange (ETDEWEB)

    Raety, J. [Oulu Univ. (Finland)

    1998-12-31

    Refractive index is one of the basic physical phenomena of materials. Traditional refractive index measurement has been widely used e.g. In research, in quality inspection of products and raw materials. It is also used for follow up of the different industrial processes. A measuring and research environment, by which it is possible to determine the complex refractive index of liquid samples, was developed in 1996 at the Measuring Instrument laboratory of the University of Oulu. This equipment, based on the reflectance of light measures both the refractive index and absorption factor of liquids simultaneously. While the commercial refractometers are best suitable for research of clear liquids, by the developed equipment it is possible to investigate by the side of clear fluids also dark strongly light absorbing samples. The measuring wave length can be chosen continuously inside the UV-Visual range. The knowing of the wave-length dependence of the complex refractive index gives additional information on the state of the fluid under inspection. The main objective of the task is to solve measuring problems of biotechnology, food industry and forest industry by a new type of refractometric method. This means the simultaneous measurement of refractive index and absorption, and the utilisation of this knowledge in wide spectral region. A refractometer, based on the technology, suitable for applied research of new measuring targets will be designed and constructed in the research. The above mentioned goals also require the survey of the present situation of the refractometry. This one and a half year project will be started in spring 1998. (orig.)

  16. On the feasibility of optical-CT imaging in media of different refractive index

    International Nuclear Information System (INIS)

    Purpose: Achieving accurate optical-CT 3D dosimetry without the use of viscous refractive index (RI) matching fluids would greatly increase convenience. Methods: Software has been developed to simulate optical-CT 3D dosimetry for a range of scanning configurations including parallel-beam, point, and converging light sources. For each configuration the efficacy of three refractive media was investigated: air, water, a fluid closely matched to PRESAGE®, and perfect matching (RI = 1.00, 1.33, 1.49, and 1.501 respectively). Reconstructions were performed using both filtered backprojection (FBP) and algebraic reconstruction technique (ART). The efficacy of the three configurations and the two algorithms was evaluated by calculating the usable radius (i.e., the outermost radius where data were accurate to within 2%), and gamma (Γ) analysis. This definition recognizes that for optical-CT imaging, errors are greatest near the edge of the dosimeter, where refraction can be most pronounced. Simulations were performed on three types of dose distribution: uniform, volumetric modulated arc therapy (VMAT), and brachytherapy (Cs-137). Results: For a uniformly irradiated dosimeter the usable radius achieved with filtered backprojection was 68% for water-matching and 31% for dry-scanning in air. Algebraic reconstruction gave usable radii of 99% for both water and air (dry-scanning), indicating greater recovery of useful data for the uniform distribution. FBP and ART performed equally well for a VMAT dose distribution where less dose is delivered near the edge of the dosimeter. In this case, the usable radius was 86% and 53% for scanning in water and air, respectively. For brachytherapy, the usable radius was 99% and 98% for scanning in water and air, respectively using FBP, and a major decrease was seen with ART. Point source geometry provided 1%–2% larger usable radii than parallel geometry. Converging geometry recovered less usable dosimetry data (up to 10% reduced usable

  17. Physics of Negative Refraction and Negative Index Materials Optical and Electronic Aspects and Diversified Approaches

    CERN Document Server

    Krowne, Clifford M

    2007-01-01

    This book deals with the subject of optical and electronic negative refraction (NR) and negative index materials NIM). Diverse approaches for achieving NR and NIM are covered, such as using photonic crystals, phononic crystals, split-ring resonators (SRRs) and continuous media, focusing of waves, guided-wave behavior, and nonlinear effects. Specific topics treated are polariton theory for LHMs (left handed materials), focusing of waves, guided-wave behavior, nonlinear optical effects, magnetic LHM composites, SRR-rod realizations, low-loss guided-wave bands using SRR-rods unit cells as LHMs, NR of electromagnetic and electronic waves in uniform media, field distributions in LHM guided-wave structures, dielectric and ferroelectric NR bicrystal heterostructures, LH metamaterial photonic-crystal lenses, subwavelength focusing of LHM/NR photonic crystals, focusing of sound with NR and NIMs, and LHM quasi-crystal materials for focusing.

  18. High-performance Refractive Index Sensor Based on Photonic Crystal Single Mode Resonant Micro-cavity

    Institute of Scientific and Technical Information of China (English)

    Shengye Huang; Junfeng Shi; Dongsheng Wang; Wei Li

    2006-01-01

    An effective refractive index sensor built with square lattice photonic crystal is proposed, which can be applicable to photonic integrated circuits. Two photonic crystal waveguides rather than conventional ridge waveguides are used as entrance/exit waveguides to the micro-cavity. Three layers of photonic lattice are set between the photonic crystal waveguides and the micro-cavity to achieve both a high transmission and a high sensitivity. The plane wave method is utilized to calculate the disperse curves and the finite difference time domain scheme is employed to simulate the light propagation. At the resonant wavelength of about 1500 nm, the resonant wavelength shifts up by 0.7 nm for each increment of △n=0.001. A transmission of more than 0.75 is observed. Although the position disorder of the photonic crystal doesn't affect the sensitivity of the sensor,the transmission reduces rapidly as the disorder increases.

  19. On the Correlation of Effective Terahertz Refractive Index and Average Surface Roughness of Pharmaceutical Tablets

    Science.gov (United States)

    Chakraborty, Mousumi; Bawuah, Prince; Tan, Nicholas; Ervasti, Tuomas; Pääkkönen, Pertti; Zeitler, J. Axel; Ketolainen, Jarkko; Peiponen, Kai-Erik

    2016-08-01

    In this paper, we have studied terahertz (THz) pulse time delay of porous pharmaceutical microcrystalline compacts and also pharmaceutical tablets that contain indomethacin (painkiller) as an active pharmaceutical ingredient (API) and microcrystalline cellulose as the matrix of the tablet. The porosity of a pharmaceutical tablet is important because it affects the release of drug substance. In addition, surface roughness of the tablet has much importance regarding dissolution of the tablet and hence the rate of drug release. Here, we show, using a training set of tablets containing API and with a priori known tablet's quality parameters, that the effective refractive index (obtained from THz time delay data) of such porous tablets correlates with the average surface roughness of a tablet. Hence, THz pulse time delay measurement in the transmission mode provides information on both porosity and the average surface roughness of a compact. This is demonstrated for two different sets of pharmaceutical tablets having different porosity and average surface roughness values.

  20. Label-free characterization of white blood cells by measuring 3D refractive index maps

    CERN Document Server

    Yoon, Jonghee; Park, HyunJoo; Choi, Chulhee; Jang, Seongsoo; Park, YongKeun

    2015-01-01

    The characterization of white blood cells (WBCs) is crucial for blood analyses and disease diagnoses. However, current standard techniques rely on cell labeling, a process which imposes significant limitations. Here we present three-dimensional (3D) optical measurements and the label-free characterization of mouse WBCs using optical diffraction tomography. 3D refractive index (RI) tomograms of individual WBCs are constructed from multiple two-dimensional quantitative phase images of samples illuminated at various angles of incidence. Measurements of the 3D RI tomogram of WBCs enable the separation of heterogeneous populations of WBCs using quantitative morphological and biochemical information. Time-lapse tomographic measurements also provide the 3D trajectory of micrometer-sized beads ingested by WBCs. These results demonstrate that optical diffraction tomography can be a useful and versatile tool for the study of WBCs.

  1. Metamaterial lens made of fully printed resonant-type negative-refractive-index transmission lines

    Science.gov (United States)

    Xu, He-Xiu; Wang, Guang-Ming; Qing Qi, Mei; Lv, Yuan-Yuan; Gao, Xi

    2013-05-01

    We studied a well-resolved lens based on planar fully printed resonant-type negative-refractive-index transmission lines made of complementary split ring resonators. The lens goes beyond previous lens in terms of moderate loss and compactness. The focusing has been demonstrated by the circuit theory simulation and full-wave simulation and finally confirmed by the experiments, showing that that the lens is able to overcome the diffraction limit of 0.5 effective wavelengths and exhibits a super resolution as small as 0.348 effective wavelengths inside the lens. The superlens free of any lumped elements opens an easy and inexpensive avenue toward imaging devices with super performances.

  2. Wave guiding by low refractive-index strips on surfaces of Chalcogenide glass thin films

    Science.gov (United States)

    Zhai, Yanfen; Zhang, Wei; Huang, Yidong

    2014-10-01

    In this paper, we proposed and demonstrated a simple ChG waveguide structure, guided by low refractive-index strips on the surfaces of planar ChG films. Theoretical analysis shows that it supports quasi-TE mode transmission in 1.5μm band with high nonlinearity. Samples of this surface guiding ChG waveguides are fabricated. Its transmission properties are measured by the cut-off method, showing a waveguide attenuation of 0.67dB/mm and a coupling loss with optical fibers of ~8dB/facet. It provides a simple way to realize high quality ChG waveguides, which has great potential in developing nonlinear photonic devices.

  3. Minimization of losses in a structure having a negative index of refraction

    International Nuclear Information System (INIS)

    A structure consisting of an array of wires cladded with a nonmagnetic dielectric and embedded in a ferrimagnetic host has been calculated to have a negative index of refraction. The structure has moderate losses over a bandwidth of a few GHz. The calculation takes into account the skin effect within the wires and is valid provided the wavelength of electromagnetic waves in the structure is long compared to the radius of the cladded wires. The structure's electromagnetic response is accurately described by the ferrimagnet's permeability and a permittivity derived in the long wavelength limit. Losses can be minimized by choosing the pass band to be between 30 and 80% of the plasma frequency and by choosing wires to be of the highest possible conductivity and largest radius compatible with the required plasma frequency

  4. An effective vacuum refractive index from gravity and the present ether-drift experiments

    CERN Document Server

    Consoli, M

    2006-01-01

    Re-analyzing the data published by the Berlin and Duesseldorf ether-drift experiments, we have found a clean non-zero daily average for the amplitude of the signal. The two experimental values, A_0\\sim (10.5 \\pm 1.3) 10^{-16} and A_0\\sim (12.1\\pm 2.2) 10^{-16}$ respectively, are entirely consistent with the theoretical prediction (9.7\\pm 3.5) 10^{-16} that is obtained once the Robertson-Mansouri-Sexl anisotropy parameter is expressed in terms of N_{vacuum}, the effective vacuum refractive index that one would get, for an apparatus placed on the Earth's surface, in a flat-space picture of gravity .

  5. Flexible chiral metamaterials with dynamically optical activity and high negative refractive index

    Science.gov (United States)

    Dincer, Furkan; Karaaslan, Muharrem; Unal, Emin; Akgol, Oguzhan; Sabah, Cumali

    2015-06-01

    We demonstrate numerically and experimentally chiral metamaterials (MTMs) based on gammadion-bilayer cross-wires that uniaxially create giant optical activity and tunable circular dichroism as a result of the dynamic design. In addition, the suggested structure gives high negative refractive index due to the large chirality in order to obtain an efficient polarization converter. We also present a numerical analysis in order to show the additional features of the proposed chiral MTM in detail. Therefore, a MTM sensor application of the proposed chiral MTM is introduced and discussed. The presented chiral designs offer a much simpler geometry and more efficient outlines. The experimental results are in a good agreement with the numerical simulation. It can be seen from the results that, the suggested chiral MTM can be used as a polarization converter, sensor, etc. for several frequency regimes.

  6. Directional Fano Resonances at Light Scattering by a High Refractive Index Dielectric Sphere

    CERN Document Server

    Tribelsky, Michael I; Litman, Amelie; Eyraud, Christelle; Moreno, Fernando

    2016-01-01

    In this research, we report the experimental evidence of the directional Fano resonances at the scattering of a plane, linearly polarized electromagnetic wave by a homogeneous dielectric sphere with high refractive index and low losses. We observe a typical asymmetric Fano profile for the intensity scattered in, practically, any given direction, while the overall extinction cross section remains Lorentzian. The phenomenon is originated in the interference of the selectively excited electric dipolar and quadrupolar modes. The selectivity of the excitation is achieved by the proper choice of the frequency of the incident wave. Thanks to the scaling invariance of the Maxwell equations, in these experiments we mimic the scattering of the visible and near IR radiation by a nanoparticle made of common superconductor materials (Si, Ge, GaAs, GaP) by the equivalent scattering of a spherical particle of 18 mm in diameter in the microwave range. The theory developed to explain the experiments extends the conventional F...

  7. Measuring the Nonlinear Refractive Index of Graphene using the Optical Kerr Effect Method

    CERN Document Server

    Dremetsika, Evdokia; Gorza, Simon-Pierre; Ciret, Charles; Martin, Marie-Blandine; Hofmann, Stephan; Seneor, Pierre; Dolfi, Daniel; Massar, Serge; Emplit, Philippe; Kockaert, Pascal

    2016-01-01

    By means of the ultrafast optical Kerr effect method coupled to optical heterodyne detection (OHD-OKE), we characterize the third order nonlinear response of graphene at telecom wavelength, and compare it to experimental values obtained by the Z-scan method on the same samples. From these measurements, we estimate a negative nonlinear refractive index for monolayer graphene, $n_2 = - 1.1\\times 10^{-13} m^2/W$. This is in contradiction to previously reported values, which leads us to compare our experimental measurements obtained by the OHD-OKE and the Z-scan method with theoretical and experimental values found in the literature, and to discuss the discrepancies, taking into account parameters such as doping.

  8. Electromagnetic polarization controlled perfect switching effect with high refractive index dimers. the beam-splitter configuration

    CERN Document Server

    Barreda, Angela I; Litman, Amelie; Gonzalez, Francisco; Geffrin, Jean-Michel; Moreno, Fernando

    2016-01-01

    High Refractive Index (HRI) dielectric particles smaller than the wavelength, isolated or forming a designed ensemble are ideal candidates as new multifunctional elements for building optical devices. Their directionality effects are traditionally analyzed through forward and backward measurements, even if these directions are not suitable for practical purposes. Here we present unambiguous experimental evidence in the microwave range that, for a dimer of HRI spherical particles, a perfect switching effect (perfect means off = null intensity) is observed out of those directions as a consequence of the mutual particle electric/magnetic interaction. The binary state depends on the excitation polarization (polarization switching). Its analysis is performed through the linear polarization degree of scattered radiation at a detection direction perpendicular to the incident direction: the beam-splitter configuration. The scaling property of Maxwell equations allows generalizing our results to other frequency range ...

  9. Quantitative Mass Density Image Reconstructed from the Complex X-Ray Refractive Index.

    Science.gov (United States)

    Mukaide, Taihei; Iida, Atsuo; Watanabe, Masatoshi; Takada, Kazuhiro; Noma, Takashi

    2015-01-01

    We demonstrate a new analytical X-ray computed tomography technique for visualizing and quantifying the mass density of materials comprised of low atomic number elements with unknown atomic ratios. The mass density was obtained from the experimentally observed ratio of the imaginary and real parts of the complex X-ray refractive index. An empirical linear relationship between the X-ray mass attenuation coefficient of the materials and X-ray energy was found for X-ray energies between 8 keV and 30 keV. The mass density image of two polymer fibers was quantified using the proposed technique using a scanning-type X-ray microbeam computed tomography system equipped with a wedge absorber. The reconstructed mass density agrees well with the calculated one. PMID:26114770

  10. Highly Sensitive Detection of Naphthalene in Solvent Vapor Using a Functionalized PBG Refractive Index Sensor

    Directory of Open Access Journals (Sweden)

    Ralf Hellmann

    2012-02-01

    Full Text Available We report an optical refractive index sensor system based on a planar Bragg grating which is functionalized by substituted γ-cyclodextrin to determine low concentrations of naphthalene in solvent vapor. The sensor system exhibits a quasi-instantaneous shift of the Bragg wavelength and is therefore capable for online detection. The overall shift of the Bragg wavelength reveals a linear relationship to the analyte concentration with a gradient of 12.5 ± 1.5 pm/ppm. Due to the spectral resolution and repeatability of the interrogation system, this corresponds to acquisition steps of 80 ppb. Taking into account the experimentally detected signal noise a minimum detection limit of 0.48 ± 0.05 ppm is deduced.

  11. Tuning the Fano resonance between localized and propagating surface plasmon resonances for refractive index sensing applications

    CERN Document Server

    Lodewijks, Kristof; Van Roy, Willem; Borghs, Gustaaf; Lagae, Liesbet; Van Dorpe, Pol

    2012-01-01

    Localized and propagating surface plasmon resonances are known to show very pronounced interactions if they are simultaneously excited in the same nanostructure. Here we study the fano interference that occurs between localized (LSPR) and propagating (SPP) modes by means of phase sensitive spectroscopic ellipsometry. The sample structures consist of periodic gratings of gold nanodisks on top of a continuous gold layer and a thin dielectric spacer, in which the structural dimensions were tuned in such a way that the dipolar LSPR mode and the propagating SPP modes are excited in the same spectral region. We observe pronounced anti-crossing and strongly asymmetric line shapes when both modes move to each others vicinity, accompagnied of largely increased phase differences between the respective plasmon resonances. Moreover we show that the anti-crossing can be exploited to increase the refractive index sensitivity of the localized modes dramatically, which result in largely increased values for the Figure-Of-Mer...

  12. On the Correlation of Effective Terahertz Refractive Index and Average Surface Roughness of Pharmaceutical Tablets

    Science.gov (United States)

    Chakraborty, Mousumi; Bawuah, Prince; Tan, Nicholas; Ervasti, Tuomas; Pääkkönen, Pertti; Zeitler, J. Axel; Ketolainen, Jarkko; Peiponen, Kai-Erik

    2016-03-01

    In this paper, we have studied terahertz (THz) pulse time delay of porous pharmaceutical microcrystalline compacts and also pharmaceutical tablets that contain indomethacin (painkiller) as an active pharmaceutical ingredient (API) and microcrystalline cellulose as the matrix of the tablet. The porosity of a pharmaceutical tablet is important because it affects the release of drug substance. In addition, surface roughness of the tablet has much importance regarding dissolution of the tablet and hence the rate of drug release. Here, we show, using a training set of tablets containing API and with a priori known tablet's quality parameters, that the effective refractive index (obtained from THz time delay data) of such porous tablets correlates with the average surface roughness of a tablet. Hence, THz pulse time delay measurement in the transmission mode provides information on both porosity and the average surface roughness of a compact. This is demonstrated for two different sets of pharmaceutical tablets having different porosity and average surface roughness values.

  13. Detecting small lung tumors in mouse models by refractive-index microradiology

    Energy Technology Data Exchange (ETDEWEB)

    Chien, Chia-Chi; Hwu, Y. [Academia Sinica, Institute of Physics, Taipei (China); National Tsing Hua University, Department of Engineering and System Science, Hsinchu (China); Zhang, Guilin; Yue, Weisheng; Li, Yan; Xue, Hongjie [Chinese Academy of Sciences, Shanghai Institute of Applied Physics, Shanghai (China); Liu, Ping; Sun, Jianqi; Xu, Lisa X. [Shanghai Jiao Tong University, Shanghai (China); Wang, Chang Hai; Chen, Nanyow; Lu, Chien Hung; Lee, Ting-Kuo [Academia Sinica, Institute of Physics, Taipei (China); Yang, Yuh-Cheng; Lu, Yen-Ta [Mackay Memorial Hospital, Taipei City (China); Ching, Yu-Tai [National Chiao Tung University, Department of Computer Science, Hsinchu (China); Shih, T.F.; Yang, P.C. [National Taiwan University, College of Medicine, Taipei (China); Je, J.H. [Pohang University of Science and Technology Pohang, X-ray Imaging Center, Pohang CT, Kyungbuk (Korea, Republic of); Margaritondo, G. [Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne (Switzerland)

    2011-08-15

    Refractive-index (phase-contrast) radiology was able to detect lung tumors less than 1 mm in live mice. Significant micromorphology differences were observed in the microradiographs between normal, inflamed, and lung cancer tissues. This was made possible by the high phase contrast and by the fast image taking that reduces the motion blur. The detection of cancer and inflammation areas by phase contrast microradiology and microtomography was validated by bioluminescence and histopathological analysis. The smallest tumor detected is less than 1 mm{sup 3} with accuracy better than 1 x 10{sup -3} mm{sup 3}. This level of performance is currently suitable for animal studies, while further developments are required for clinical application. (orig.)

  14. Refractive index sensors based on the fused tapered special multi-mode fiber

    Science.gov (United States)

    Fu, Xing-hu; Xiu, Yan-li; Liu, Qin; Xie, Hai-yang; Yang, Chuan-qing; Zhang, Shun-yang; Fu, Guang-wei; Bi, Wei-hong

    2016-01-01

    In this paper, a novel refractive index (RI) sensor is proposed based on the fused tapered special multi-mode fiber (SMMF). Firstly, a section of SMMF is spliced between two single-mode fibers (SMFs). Then, the SMMF is processed by a fused tapering machine, and a tapered fiber structure is fabricated. Finally, a fused tapered SMMF sensor is obtained for measuring external RI. The RI sensing mechanism of tapered SMMF sensor is analyzed in detail. For different fused tapering lengths, the experimental results show that the RI sensitivity can be up to 444.517 81 nm/RIU in the RI range of 1.334 9—1.347 0. The RI sensitivity is increased with the increase of fused tapering length. Moreover, it has many advantages, including high sensitivity, compact structure, fast response and wide application range. So it can be used to measure the solution concentration in the fields of biochemistry, health care and food processing.

  15. Role of shape of hole in transmission and negative refractive index of sandwiched metamaterials

    International Nuclear Information System (INIS)

    Transmission and negative refractive index (NRI) of metal—dielectric—metal (MDM) sandwiched metamaterial perforated with four kinds of shapes of holes are numerically studied. Results indicate that positions of all transmission peaks of these kinds of holes are sensitive to the shape of the hole. Under the same conditions, the circular hole can obtain the maximum NRI and the rectangular hole can obtain the maximum frequency bandwidth of NRI. Moreover, the figure of merit (FOM) of the circular hole is the maximum too. As a result, we can obtain a higher NRI and FOM metamaterial by drilling circular hole arrays on MDM metamaterial. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  16. Preparation of inulin-type fructooligosaccharides using fast protein liquid chromatography coupled with refractive index detection.

    Science.gov (United States)

    Li, J; Cheong, K L; Zhao, J; Hu, D J; Chen, X Q; Qiao, C F; Zhang, Q W; Chen, Y W; Li, S P

    2013-09-20

    A fast protein liquid chromatography coupled with refractive index detection (FPLC-RID) method was firstly developed for preparation and purification of fructooligosaccharides with different degree of polymerization from burdock, Arctium lappa. After extraction with 60% ethanol and decolorization with MCI gel CHP20P, total fructooligosaccharides were purified on Bio-Gel P-2 column eluted with water at the flow rate of 0.3 ml/min, which was the optimized conditions. The obtained fructooligosaccharides with degree of polymerization of 3-9 were identified based on their methylation analysis, MS and NMR data. This method has the advantages of high automation, good recovery and easy performance, which could be used for preparation of FOS from other sources, as well as other targeted compounds without UV absorbance. PMID:23962565

  17. An ultrasensitive and multispectral refractive index sensor based on quad-supercell metamaterials

    CERN Document Server

    Xiao, Shuyuan; Liu, Yuebo; Han, Xu; Yan, Xicheng

    2015-01-01

    Plasmonic metamaterials support the localized surface plasmon resonance (LSPR) and the strong field enhancement could be applied to ultrasensitive biochemical sensing. In this work, a novel design of quad-supercell metamaterials of split ring resonators (SRRs) is proposed and simultaneous excitations of odd (N=1 and N=3) and even (N=2) resonance modes are realized due to additional asymmetry from the rotation with respect to the excitation field. The full utilization of these three resonance dips show bright prospects for multispectral application. As a refractive index (RI) sensor, ultrahigh sensitivities ~1000nm/RIU for LC mode (N=1) and ~500nm/RIU for plasmon mode (N=2) are obtained in near infrared (NIR) spectrum.

  18. Prediction model of atmospheric refractive index structure parameter in coastal area

    Science.gov (United States)

    Wang, Hongxing; Li, Bifeng; Wu, Xiaojun; Liu, Chuanhui; Hu, Zhihui; Xu, Pengfei

    2015-09-01

    In this paper, we focus on the prediction of atmospheric refractive index structure parameter (?) in coastal area using the routine meteorological parameters. Based on the micrometeorology, macrometeorology and Monin-Obukhov similarity theory, three modified prediction models of ? are presented in combination with the long-term observation data of ? and meteorological parameters in coastal city, respectively. For different weather, the applicable cases of three ? prediction models are comparatively analysed and their applicable effects are comprehensively evaluated. The results indicate that the modified micrometeorology model of ? shows better applicability for overcast sky, the offshore macrometeorology model of ? displays better predictability for sunny day and the offshore Thiermann model provides better availability for overcast sky, cloudy day, overcast to sunny or sunny to overcast day.

  19. Power-Interrogated Refractive Index Sensor Using Long Period Grating in Photonic Crystal Fiber

    Directory of Open Access Journals (Sweden)

    X. L. Jiang

    2015-01-01

    Full Text Available We reported a long period grating (LPG written in specially designed photonic crystal fiber (PCF for refractive index (RI sensing by interrogating the transmitted light power. The outermost ring of clad holes of the PCF is enlarged where the analyte is filled. We showed that the leakage loss of the clad mode increases with the RI in the larger holes. By numerically analyzing the complex couple mode equations for the core mode and the first clad mode, we found the depth of attenuation band in the transmitted spectra and the total transmitted power is sensitive to the leakage loss of the clad mode or the RI in the larger holes. We also demonstrated that the transmitted power is sensitive to the RI even less than that of the silica, which just avoids the limitation that the transmitted light power of LPG in conventional fiber is only sensitive to the RI of the external media higher than that of fiber clad.

  20. From Dark to Bright: First-Order Perturbation Theory with Analytical Mode Normalization for Plasmonic Nanoantenna Arrays Applied to Refractive Index Sensing

    Science.gov (United States)

    Weiss, T.; Mesch, M.; Schäferling, M.; Giessen, H.; Langbein, W.; Muljarov, E. A.

    2016-06-01

    We present a first-order perturbation theory to calculate the frequency shift and linewidth change of photonic resonances in one- and two-dimensional periodic structures under modifications of the surrounding refractive index. Our method is based on the resonant state expansion, for which we extend the analytical mode normalization to periodic structures. We apply this theory to calculate the sensitivity of bright dipolar and much darker quadrupolar plasmonic modes by determining the maximum shift and optimal sensing volume.

  1. Effective group index of refraction in non-thermal plasma photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Mousavi, A.; Sadegzadeh, S., E-mail: sadegzadeh@azaruniv.edu [Physics Department, Azarbaijan Shahid Madani University, Tabriz (Iran, Islamic Republic of)

    2015-11-15

    Plasma photonic crystals (PPCs) are periodic arrays that consist of alternate layers of micro-plasma and dielectric. These structures are used to control the propagation of electromagnetic waves. This paper presents a survey of research on the effect of non-thermal plasma with bi-Maxwellian distribution function on one dimensional PPC. A plasma with temperature anisotropy is not in thermodynamic equilibrium and can be described by the bi-Maxwellian distribution function. By using Kronig-Penny's model, the dispersion relation of electromagnetic modes in one dimensional non-thermal PPC (NPPC) is derived. The band structure, group velocity v{sub g}, and effective group index of refraction n{sub eff}(g) of such NPPC structure with TeO{sub 2} as the material of dielectric layers have been studied. The concept of negative group velocity and negative n{sub eff}(g), which indicates an anomalous behaviour of the PPCs, are also observed in the NPPC structures. Our numerical results provide confirmatory evidence that unlike PPCs there are finite group velocity and non-zero effective group indexes of refraction in photonic band gaps (PBGs) that lie in certain ranges of normalized frequency. In other words, inside the PBGs of NPPCs, n{sub eff}(g) becomes non-zero and photons travel with a finite group velocity. In this special case, this velocity varies alternately between 20c and negative values of the order 10{sup 3}c (c is the speed of light in vacuum)

  2. Study of the Composition and Spectral Characteristics of a HDG-Prism Disperse System (GRISM) by Refractive Index Phase Matching

    CERN Document Server

    Jo, Chon-Gyu; Im, Song-Jin

    2015-01-01

    The composition and characteristics of a GRISM gained by refractive index matching between a refractive index modulation type HDG and a prism is investigated, the HDG being built by processing silver halide emulsion with halide vapor. The GRISM has been stable under external influences like humidity or ultraviolet light exposure. The mercury atomic spectrum obtained by a GRISM based on a HDG with a spatial frequency of 600mm-1 shows yellow dual lines with the wavelength difference of 2.1nm sufficiently separated.

  3. Remote steering of laser beams by radar- and laser-induced refractive-index gradients in the atmosphere

    International Nuclear Information System (INIS)

    Refractive-index gradients induced in the atmospheric air by properly tailored laser and microwave fields are shown to enable a remote steering of laser beams. Heating-assisted modulation of the refractive index of the air by microwave radiation is shown to support small-angle laser-beam bending with bending angles on the order of 10-2. Ionization of the atmospheric air by dyads of femto- and nanosecond laser pulses, on the other hand, can provide beam deflection angles in excess of π/5, offering an attractive strategy for radiation transfer, free-space communications, and laser-based standoff detection

  4. Enabling novel functionality in heavily doped ZnO:Ga by nanostructuring: an efficient plasmonic refractive index sensor.

    Science.gov (United States)

    Kuznetsov, Alexander S; Schäfer, Peter; John, Wilfred; Prasai, Deepak; Sadofev, Sergey; Kalusniak, Sascha

    2016-01-15

    We demonstrate a proof-of-concept refractive index sensor based on heavily doped ZnO:Ga nanostructured in a grating configuration, which supports free space excitation of propagating surface plasmons. The bulk sensitivity of the sensor of 4.9 × 10(3) nm per refractive index unit, achieved in the mid-infrared spectral range with the first grating prototype, surpasses that of the noble metal counterparts by three to four times. Sensing performance is discussed in the light of numerical simulations of the spatial profile of the near field of surface plasmon polaritons. PMID:26629968

  5. Giant refractive-index modulation by two-photon reduction of fluorescent graphene oxides for multimode optical recording

    OpenAIRE

    Li, Xiangping; Zhang, Qiming; Chen, Xi; Gu, Min

    2013-01-01

    Graphene oxides (GOs) have emerged as precursors offering the potential of a cost-effective and large-scale production of graphene-based materials. Despite that their intrinsic fluorescence property has already brought interest of researchers for optical applications, to date, refractive-index modulation as one of the fundamental aspects of optical properties of GOs has received less attention. Here we reported on a giant refractive-index modulation on the order of 10−2 to 10−1, accompanied b...

  6. SPR-based PCF D-type sensor based on a metamaterial composed of planar metals for refractive index sensing

    Science.gov (United States)

    Santos, D. F.; Guerreiro, A.; Baptista, J. M.

    2016-05-01

    This paper presents a numerically investigation of the performance analysis of a conventional photonic crystal fiber (PCF) with a planar metamaterials structure for refractive index sensing, based on surface plasmon resonance (SPR), using the finite element method (FEM). We study the concentration metamaterials conformed by the aluminium oxide (Al2O3) and silver (Ag) and compared its performance with a single metal (Ag), assessing their impacts in the effective refractive index. Furthermore, we also use different types of mechanics to describe the effects of varying the structural parameters sensor on the evanescent field and the sensor performance.

  7. Analyzing the effect of absorption and refractive index on image formation in high numerical aperture transmission microscopy of single cells

    Science.gov (United States)

    Coe, Ryan L.; Seibel, Eric J.

    2013-02-01

    Transmission bright-field microscopy is the clinical mainstay for disease diagnosis where image contrast is provided by absorptive and refractive index differences between tissue and the surrounding media. Different microscopy techniques often assume one of the two contrast mechanisms is negligible as a means to better understand the tissue scattering processes. This particular work provides better understanding of the role of refractive index and absorption within Optical Projection Tomographic Microscopy (OPTM) through the development of a generalized computational model based upon the Finite-Difference Time-Domain method. The model mimics OPTM by simulating axial scanning of the objective focal plane through the cell to produce projection images. These projection images, acquired from circumferential positions around the cell, are reconstructed into isometric three-dimensional images using the filtered backprojection normally employed in Computed Tomography (CT). The model provides a platform to analyze all aspects of bright-field microscopes, such as the degree of refractive index matching and the numerical aperture, which can be varied from air-immersion to high NA oil-immersion. In this preliminary work, the model is used to understand the effects of absorption and refraction on image formation using micro-shells and idealized nuclei. Analysis of absorption and refractive index separately provides the opportunity to better assess their role together as a complex refractive index for improved interpretation of bright-field scattering, essential for OPTM image reconstruction. This simulation, as well as ones in the future looking at other effects, will be used to optimize OPTM imaging parameters and triage efforts to further improve the overall system design.

  8. Fano lineshapes of 'Peak-tracking chip' spatial profiles analyzed with correlation analysis for bioarray imaging and refractive index sensing

    KAUST Repository

    Bougot-Robin, K.

    2013-05-22

    The asymmetric Fano resonance lineshapes, resulting from interference between background and a resonant scattering, is archetypal in resonant waveguide grating (RWG) reflectivity. Resonant profile shift resulting from a change of refractive index (from fluid medium or biomolecules at the chip surface) is classically used to perform label-free sensing. Lineshapes are sometimes sampled at discretized “detuning” values to relax instrumental demands, the highest reflectivity element giving a coarse resonance estimate. A finer extraction, needed to increase sensor sensitivity, can be obtained using a correlation approach, correlating the sensed signal to a zero-shifted reference signal. Fabrication process is presented leading to discrete Fano profiles. Our findings are illustrated with resonance profiles from silicon nitride RWGs operated at visible wavelengths. We recently demonstrated that direct imaging multi-assay RWGs sensing may be rendered more reliable using “chirped” RWG chips, by varying a RWG structure parameter. Then, the spatial reflectivity profiles of tracks composed of RWGs units with slowly varying filling factor (thus slowly varying resonance condition) are measured under monochromatic conditions. Extracting the resonance location using spatial Fano profiles allows multiplex refractive index based sensing. Discretization and sensitivity are discussed both through simulation and experiment for different filling factor variation, here Δf=0.0222 and Δf=0.0089. This scheme based on a “Peak-tracking chip” demonstrates a new technique for bioarray imaging using a simpler set-up that maintains high performance with cheap lenses, with down to Δn=2×10-5 RIU sensitivity for the highest sampling of Fano lineshapes. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

  9. Physicochemical and catalytic properties of Au nanorods micro-assembled in solvents of varying dipole moment and refractive index

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Rupinder; Pal, Bonamali, E-mail: bpal@thapar.edu

    2015-02-15

    Highlights: • Physicochemical activities of Au nanorods in water largely differ from organic solvents. • Au nanorods agglomeration increased with dipole moments of different polar solvents. • Refractive indexes of Au nanorods dispersion in various polar solvents are enhanced. • Electrokinetics significantly altered depending on agglomerated size of Au nanorods. • Catalysis or co-catalysis activity is varied as per the extent of Au nanorods coagulation. - Abstract: This paper deals with the impact of dipole moment (1.66–3.96 D) and refractive index (1.333–1.422) of the dispersion solvent on the plasmon absorption, surface charge, zeta potential, and adsorption properties of Au nanorods (AuNRs). AuNRs (length ≈ 53 nm and width ≈ 20 nm) undergo agglomeration (size 50–180 nm) with increase in the dipole moment of solvent (iPrOH < MeOH < DMF < DMSO). Whereas, no such coagulation occurs in H{sub 2}O and CCl{sub 4} suspension as confirmed by DLS and TEM size distribution. The electrostatic interaction of AuNRs with its surface adsorbed solvent dipoles leads to alteration of the their ionic state, absolute electronic charge and zeta potential (+49.79 mV in H{sub 2}O, +8.99 mV in DMF and −4.65 mV in MeOH dispersion) to a greater extent. This interaction distinctly modifies the adsorption behavior of polar molecules like p-nitrophenol and salicylic acid on AuNRs surface, as evidenced by the measured changes in their electro-kinetic parameters. As a result, we observe a substantial difference in catalytic and co-catalytic activities of AuNRs dispersed in various solvents as mentioned above because the catalytic properties of AuNRs are strongly dependent on the type of solvent in which they are dispersed.

  10. Zero absorption and a large negative refractive index in a left-handed four-level atomic medium

    International Nuclear Information System (INIS)

    In this paper, we have investigated three external fields interacting with the four-level atomic system described by the density-matrix approach. The atomic system exhibits left-handedness with zero absorption and large negative refractive index. Varying the parameters of the three external fields, the properties of zero absorption and large negative refractive index from the atomic system remain unvarying. Our scheme proposes an approach to obtain a negative refractive medium with zero absorption. The zero absorption property of the atomic system may be used to amplify the evanescent waves that have been lost in the imaging by traditional lenses, and a slab fabricated by the left-handed atomic system may be an ideal candidate for designing perfect lenses.

  11. Electrospray deposition of chalcogenide glass films for gradient refractive index and quantum dot incorporation

    Science.gov (United States)

    Novak, Spencer

    Chalcogenide glasses (ChGs) are well-known for their optical properties, making them ideal candidates for emerging applications of mid-infrared microphotonic devices, such as lab-on-a-chip chemical sensing devices, which currently demand additional flexibility in processing and materials available to realize new device designs. Solution-derived processing of ChG films, initially developed in the 1980s by Chern and Lauks, has consisted mainly of spin-coating and offers unique advantages over the more traditional physical vapor deposition techniques. In the present effort, the nanoparticles of interest are luminescent quantum dots (QDs), which can be used as an on-chip source of light for a planar chemical sensing device. Prior efforts of QD incorporation have exposed limitations of spin-coating of ChG solutions, namely QD aggregation and material waste, along with incompatibility with larger scale manufacturing methods such roll-to-roll processing. This dissertation has evaluated electrospray (ES) as an alternative method of solution-derived chalcogenide glass film deposition. While employed in other materials systems, deposition of optical quality ChG films via electrospray has not been previously attempted, nor have parameters until now, been defined. This study has defined pre-cursor solution chemistry, electrospray jet process parameters required for formation of stable films, annealing protocols and resulting film attributes, yielding important correlations needed to realize high optical quality films. Electrosprayed films attributes were compared to those seen for spin coating and trade-offs in processing route and resulting quality, were identified. Optical properties of importance to device applications were defined, including surface roughness, refractive index, and infrared transmission. The use of a serpentine path of the spray over the substrate was demonstrated to obtain uniform thickness, blanket films, and demonstrates process compatibility with roll

  12. Effect of anisotropic fluctuations of the refractive index on transhorizon ultrashort-wave propagation in the atmosphere

    Science.gov (United States)

    Koshel', K. V.; Shishkarev, A. A.

    1993-02-01

    A perturbation theory for complex propagation constants is considered, based on the invariant imbedding method. This approach makes it possible to describe the effect of nonstratified fluctuations of the refractive index on transhorizon propagation of ultrashort waves in the framework of the adiabatic approximation in the case when an evaporation duct exists. Examples of calculations are presented, and characteristic stochastic effects are studied.

  13. Initial growth, refractive index, and crystallinity of thermal and plasma-enhanced atomic layer deposition AlN films

    Energy Technology Data Exchange (ETDEWEB)

    Van Bui, Hao, E-mail: H.VanBui@utwente.nl; Wiggers, Frank B.; Gupta, Anubha; Nguyen, Minh D.; Aarnink, Antonius A. I.; Jong, Michel P. de; Kovalgin, Alexey Y., E-mail: A.Y.Kovalgin@utwente.nl [MESA Institute for Nanotechnology, University of Twente, P. O. Box 217, 7500 AE Enschede (Netherlands)

    2015-01-01

    The authors have studied and compared the initial growth and properties of AlN films deposited on Si(111) by thermal and plasma-enhanced atomic layer deposition (ALD) using trimethylaluminum and either ammonia or a N{sub 2}-H{sub 2} mixture as precursors. In-situ spectroscopic ellipsometry was employed to monitor the growth and measure the refractive index of the films during the deposition. The authors found that an incubation stage only occurred for thermal ALD. The linear growth for plasma-enhanced ALD (PEALD) started instantly from the beginning due to the higher nuclei density provided by the presence of plasma. The authors observed the evolution of the refractive index of AlN during the growth, which showed a rapid increase up to a thickness of about 30 nm followed by a saturation. Below this thickness, higher refractive index values were obtained for AlN films grown by PEALD, whereas above that the refractive index was slightly higher for thermal ALD films. X-ray diffraction characterization showed a wurtzite crystalline structure with a (101{sup ¯}0) preferential orientation obtained for all the layers with a slightly better crystallinity for films grown by PEALD.

  14. Pressure Sensing in High-Refractive-Index Liquids Using Long-Period Gratings Nanocoated with Silicon Nitride

    Directory of Open Access Journals (Sweden)

    Jiahua Chen

    2010-12-01

    Full Text Available The paper presents a novel pressure sensor based on a silicon nitride (SiNx nanocoated long-period grating (LPG. The high-temperature, radio-frequency plasma-enhanced chemical-vapor-deposited (RF PECVD SiNx nanocoating was applied to tune the sensitivity of the LPG to the external refractive index. The technique allows for deposition of good quality, hard and wear-resistant nanofilms as required for optical sensors. Thanks to the SiNx nanocoating it is possible to overcome a limitation of working in the external-refractive-index range, which for a bare fiber cannot be close to that of the cladding. The nanocoated LPG-based sensing structure we developed is functional in high-refractive-index liquids (nD > 1.46 such as oil or gasoline, with pressure sensitivity as high as when water is used as a working liquid. The nanocoating developed for this experiment not only has the highest refractive index ever achieved in LPGs (n > 2.2 at λ = 1,550 nm, but is also the thinnest (

  15. The spatial-time distribution of vertical gradient of refraction index of air in territory of Mongolia

    International Nuclear Information System (INIS)

    The results of calculation of the vertical gradient of refraction index of air in 2-300 m and 2-900 m layer of troposphere by 3 year (1987-1989) data of 8 meteorological stations in the Mongolia is been showed. Year course and integral distribution of gn of this stations are discriminated

  16. Note: Optical fiber milled by focused ion beam and its application for Fabry-Pérot refractive index sensor

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Wang, Fei; Savenko, Alexey;

    2011-01-01

    We introduce a highly compact fiber-optic Fabry-Pérot refractive index sensor integrated with a fluid channel that is fabricated directly near the tip of a 32 μm in diameter single-mode fiber taper. The focused ion beam technique is used to efficiently mill the microcavity from the fiber side...

  17. Giant in-particle field concentration and Fano resonances at light scattering by high-refractive-index particles

    Science.gov (United States)

    Tribelsky, Michael I.; Miroshnichenko, Andrey E.

    2016-05-01

    We present the results of a detailed analytical study of light scattering by a particle with high refractive index m +i κ and low losses (m ≫1 ,0 academic interest, the obtained results may be employed to design new highly nonlinear heterogenic nanostructures and other metamaterials.

  18. Study on Effect of Number of Transparent Covers and Refractive Index on Performance of Solar Water Heater

    Directory of Open Access Journals (Sweden)

    B. Kalidasan

    2014-01-01

    Full Text Available Liquid flat plate collector (solar flat plate collector is one of the important applications in solar thermal system. The development in solar photovoltaic is an emerging challenge for the solar thermal system. In the current work an attempt has been made to optimize the number of transparent covers and refractive index to improve the optical efficiency and thermal efficiency for the collector. Performance of the liquid flat plate collector at VIT University Vellore has been simulated numerically for January 21st at an interval of half an hour with different numbers of transparent covers (0–3 and different refractive index values ranging from 1.1 to 1.7. The formulation and solutions are developed with simple software Microsoft Office Excel to result the performance characteristics. The result shows that the efficiency of the flat plate collector increases with an increase in number of covers and decreases after an optimum number of covers. It also decreases with an increase in refractive index. The combination of optimum number (two and lower refractive index (1.1 results improved useful heat.

  19. An iterative method to reconstruct the refractive index of a medium from time-of-flight measurements

    Science.gov (United States)

    Schröder, Udo; Schuster, Thomas

    2016-08-01

    The article deals with a classical inverse problem: the computation of the refractive index of a medium from ultrasound time-of-flight measurements. This problem is very popular in seismics but also for tomographic problems in inhomogeneous media. For example ultrasound vector field tomography needs a priori knowledge of the sound speed. According to Fermat’s principle ultrasound signals travel along geodesic curves of a Riemannian metric which is associated with the refractive index. The inverse problem thus consists of determining the index of refraction from integrals along geodesics curves associated with the integrand leading to a nonlinear problem. In this article we describe a numerical solver for this problem scheme based on an iterative minimization method for an appropriate Tikhonov functional. The outcome of the method is a stable approximation of the sought index of refraction as well as a corresponding set of geodesic curves. We prove some analytical convergence results for this method and demonstrate its performance by means of several numerical experiments. Another novelty in this article is the explicit representation of the backprojection operator for the ray transform in Riemannian geometry and its numerical realization relying on a corresponding phase function that is determined by the metric. This gives a natural extension of the conventional backprojection from 2D computerized tomography to inhomogeneous geometries. The authors dedicate this article to Prof Todd Quinto on the occasion of his 65th birthday.

  20. Retrieval of structure functions of air temperature and refractive index from large eddy simulations of the atmospheric boundary layer

    NARCIS (Netherlands)

    Wilson, C.; Eijk, A.M.J. van; Fedorovich, E.

    2013-01-01

    A methodology is presented to infer the refractive-index structure function parameter and the structure parameters for temperature and humidity from numerical simulations of the turbulent atmospheric convective boundary layer (CBL). The method employs spatial and temporal averaging of multiple reali