Sample records for absolute refractive index

  1. Full field imaging based instantaneous hyperspectral absolute refractive index measurement

    SciTech Connect

    Baba, Justin S [ORNL; Boudreaux, Philip R [ORNL

    2012-01-01

    Multispectral refractometers typically measure refractive index (RI) at discrete monochromatic wavelengths via a serial process. We report on the demonstration of a white light full field imaging based refractometer capable of instantaneous multispectral measurement of absolute RI of clear liquid/gel samples across the entire visible light spectrum. The broad optical bandwidth refractometer is capable of hyperspectral measurement of RI in the range 1.30 1.70 between 400nm 700nm with a maximum error of 0.0036 units (0.24% of actual) at 414nm for a = 1.50 sample. We present system design and calibration method details as well as results from a system validation sample.

  2. High Accuracy, Absolute, Cryogenic Refractive Index Measurements of Infrared Lens Materials for JWST NIRCam using CHARMS

    NASA Technical Reports Server (NTRS)

    Leviton, Douglas; Frey, Bradley

    2005-01-01

    The current refractive optical design of the James Webb Space Telescope (JWST) Near Infrared Camera (NIRCam) uses three infrared materials in its lenses: LiF, BaF2, and ZnSe. In order to provide the instrument s optical designers with accurate, heretofore unavailable data for absolute refractive index based on actual cryogenic measurements, two prismatic samples of each material were measured using the cryogenic, high accuracy, refraction measuring system (CHARMS) at NASA GSFC, densely covering the temperature range from 15 to 320 K and wavelength range from 0.4 to 5.6 microns. Measurement methods are discussed and graphical and tabulated data for absolute refractive index, dispersion, and thermo-optic coefficient for these three materials are presented along with estimates of uncertainty. Coefficients for second order polynomial fits of measured index to temperature are provided for many wavelengths to allow accurate interpolation of index to other wavelengths and temperatures.

  3. Temperature-dependent Absolute Refractive Index Measurements of Synthetic Fused Silica

    NASA Technical Reports Server (NTRS)

    Leviton, Douglas B.; Frey, Bradley J.

    2006-01-01

    Using the Cryogenic, High-Accuracy Refraction Measuring System (CHARMS) at NASA's Goddard Space Flight Center, we have measured the absolute refractive index of five specimens taken from a very large boule of Corning 7980 fused silica from temperatures ranging from 30 to 310 K at wavelengths from 0.4 to 2.6 microns with an absolute uncertainty of plus or minus 1 x 10 (exp -5). Statistical variations in derived values of the thermo-optic coefficient (dn/dT) are at the plus or minus 2 x 10 (exp -8)/K level. Graphical and tabulated data for absolute refractive index, dispersion, and thermo-optic coefficient are presented for selected wavelengths and temperatures along with estimates of uncertainty in index. Coefficients for temperature-dependent Sellmeier fits of measured refractive index are also presented to allow accurate interpolation of index to other wavelengths and temperatures. We compare our results to those from an independent investigation (which used an interferometric technique for measuring index changes as a function of temperature) whose samples were prepared from the same slugs of material from which our prisms were prepared in support of the Kepler mission. We also compare our results with sparse cryogenic index data from measurements of this material from the literature.

  4. High-accuracy interferometer with a prism pair for measurement of the absolute refractive index of glass

    SciTech Connect

    Hori, Yasuaki; Hirai, Akiko; Minoshima, Kaoru; Matsumoto, Hirokazu

    2009-04-10

    We propose a variable-path interferometric technique for the measurement of the absolute refractive index of optical glasses. We use two interferometers to decide the ratio between changes in the optical path in a prism-shaped sample glass and in air resulting from displacement of the sample. The method allows precise measurements to be made without prior knowledge of the properties of the sample. The combined standard uncertainty of the proposed method is 1.6x10{sup -6}.

  5. Phase-sensitive swept-source interferometry for absolute ranging with application to measurements of group refractive index and thickness.

    PubMed

    Moore, Eric D; McLeod, Robert R

    2011-04-25

    Interferometric range measurements using a wavelength-tunable source form the basis of several measurement techniques, including optical frequency domain reflectometry (OFDR), swept-source optical coherence tomography (SS-OCT), and frequency-modulated continuous wave (FMCW) lidar. We present a phase-sensitive and self-referenced approach to swept-source interferometry that yields absolute range measurements with axial precision three orders of magnitude better than the transform-limited axial resolution of the system. As an example application, we implement the proposed method for a simultaneous measurement of group refractive index and thickness of an optical glass sample. PMID:21643062

  6. The Index of Refraction

    NSDL National Science Digital Library

    WGBH Educational Foundation

    2011-10-25

    In this media-rich lesson plan, students explore the refraction of light at the boundary between materials: they learn about the refractive indices of various materials and measure the index of refraction of plastic or gelatin.

  7. Index of Refraction

    NSDL National Science Digital Library

    Refraction is an important behavior of light that can be used to explain the operation of lenses, prisms, and optical fiber, as well as natural phenomena such as rainbows and mirages. The index of refraction, or refractive index, is defined as the ratio of the speed of light in a vacuum to the speed of light in a material. The index of refraction is an important property of optical materials and one that can be easily measured in the laboratory.This lesson begins with a video that introduces the concept of refraction. Students learn firsthand how when a wave of light travels from one medium to another, the change in the wave's speed leads to a change in its wavelength and the bending of the wave. Next, students investigate index of refraction through an interactive media asset, research, and a class discussion. Following a video about the index of refraction and Snell's law, students work in groups to conduct their own laboratory experiment to measure the index of refraction of gelatin (or plastic).Note: This is the first of two optics lesson plans. You may want to follow this lesson with the Fiber Optics Lesson Plan.

  8. Gradient Refractive Index Lenses.

    ERIC Educational Resources Information Center

    Morton, N.

    1984-01-01

    Describes the nature of gradient refractive index (GRIN) lenses, focusing on refraction in these materials, focal length of a thin Wood lens, and on manufacturing of such lenses. Indicates that GRIN lenses of small cross section are in limited production with applications suggested for optical communication and photocopying fields. (JN)

  9. Prism-pair interferometry by homodyne interferometers with a common light source for high-accuracy measurement of the absolute refractive index of glasses

    SciTech Connect

    Hori, Yasuaki; Hirai, Akiko; Minoshima, Kaoru

    2011-03-10

    A prism-pair interferometer comprising two homodyne interferometers with a common light source was developed for high-precision measurements of the refractive index of optical glasses with an uncertainty of the order of 10{sup -6}. The two interferometers measure changes in the optical path length in the glass sample and in air, respectively. Uncertainties in the absolute wavelength of the common light source are cancelled out by calculating a ratio between the results from the interferometers. Uncertainties in phase measurement are suppressed by a quadrature detection system. The combined standard uncertainty of the developed system is evaluated as 1.1x10{sup -6}.

  10. Fabrication of gradient refractive index ball lenses

    NASA Astrophysics Data System (ADS)

    Lv, Hao; Shi, Bangren; Wu, Jijiang; Guo, Lijun; Liu, Aimei

    2008-03-01

    The theoretical model of the Maxwell fish eye sphere lens has long been regarded as an absolute optical instrument without practical application since it was proposed. But the study on the theory of Maxwell fish eye micro-spherical lens shows that at certain condition it has fine image formation ability and coupling efficiency. Based on the Fick's diffusion equations, the distribution function of refractive index of gradient refractive index (GRIN) ball lenses is derived. Lithium-containing silicate glass is fabricated and GRIN ball lenses whose diameters are from 0.3 to 3.0 mm are made by ion exchange and the sagging method in sodium nitrate. Radial refractive index profiles of these GRIN ball lens are measured by interferometer. Results show that the distribution of the index of refraction is a parabolic curve and in concordance with the computational consequence and its ? n is 0.0002.

  11. Fiber optic refractive index monitor

    DOEpatents

    Weiss, Jonathan David (Albuquerque, NM)

    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.

  12. Index of Refraction without Geometry

    ERIC Educational Resources Information Center

    Farkas, N.; Henriksen, P. N.; Ramsier, R. D.

    2006-01-01

    This article presents several activities that permit students to determine the index of refraction of transparent solids and liquids using simple equipment without the need for geometrical relationships, special lighting or optical instruments. Graphical analysis of the measured data is shown to be a useful method for determining the index of…

  13. Infrared refractive index of diamond

    SciTech Connect

    Edwards, D.F.; Ochoa, E.

    1981-05-01

    The refractive index of natural Type IIa diamond is reported for spectral region 2.5--25mm. The data have been filtered to a Herzberger-type dispersion formula with a quality of fit of a few places in the fifth decimal place. The resultant index uncertainty is abut 10/sup -3/.

  14. Refractive Index of Sodium Iodide

    SciTech Connect

    Jellison Jr, Gerald Earle [ORNL; Boatner, Lynn A [ORNL; Ramey, Joanne Oxendine [ORNL; Kolopus, James A [ORNL; Ramey, Lucas A [ORNL; Singh, David J [ORNL

    2012-01-01

    The refractive index of sodium iodide, an important scintillator material that is widely used for radiation detection, is based on a single measurement made by Spangenberg at one wavelength using the index-matching liquid immersion method (Z. Kristallogr., 57, 494-534 (1923)). In the present paper, we present new results for the refractive index of sodium iodide as measured by the minimum deviation technique at six wavelengths between 436 nm (n=1.839 0.002) and 633 nm (n=1.786 0.002). These 6 measurements can be fit to a Sellmeier model, resulting in a 2 of 1.02, indicating a good fit to the data. In addition, we report on ellipsometry measurements, which suggest that the near-surface region of the air sensitive NaI crystal seriously degrades, even in a moisture-free environment, resulting in a significantly lower value of the refractive index near the surface. First-principles theoretical calculations of the NaI refractive index that agree with the measured values within 0.025-0.045 are also presented and discussed.

  15. Make That Invisible! Refractive Index Matching

    NSDL National Science Digital Library

    2014-09-18

    Students determine the refractive index of a liquid with a simple technique using a semi-circular hollow block. Then they predict the refractive index of a material (a Pyrex glass tube) by matching it with the known refractive index of a liquid using the percent light transmission measurement. The homemade light intensity detector uses an LED and multimeter, which are relatively inexpensive (and readily available) compared to commercially available measurement instruments.

  16. Refractive-index profiling of graded-index planar waveguides from effective indexes measured with different external refractive indexes

    Microsoft Academic Search

    Kin Seng Chiang; Chi Lai Wong; Sin Yip Cheng; Hau Ping Chan

    2000-01-01

    We extend the well-known inverse Wentzel-Kramer-Brillouin (WKB) method for refractive-index profiling of graded-index planar waveguides. We demonstrate, with numerical examples and experimental results, that the refractive-index profile of a graded-index planar waveguide can be calculated from effective indexes measured with different external refractive indexes. With this technique, single-mode and two-mode waveguides can be profiled easily to a good accuracy.

  17. Negative index of refraction in optical metamaterials

    Microsoft Academic Search

    Vladimir M. Shalaev; Wenshan Cai; Uday K. Chettiar; Hsiao-Kuan Yuan; Andrey K. Sarychev; Vladimir P. Drachev; Alexander V. Kildishev

    2005-01-01

    A double-periodic array of pairs of parallel gold nanorods is shown to have a negative refractive index in the optical range. Such behavior results from the plasmon resonance in the pairs of nanorods for both the electric and the magnetic components of light. The refractive index is retrieved from direct phase and amplitude measurements for transmission and reflection, which are

  18. Quantum storage via refractive-index control

    SciTech Connect

    Kalachev, Alexey [Institute for Quantum Studies and Department of Physics, Texas A and M University, College Station, Texas 77843-4242 (United States); Zavoisky Physical-Technical Institute of the Russian Academy of Sciences, Sibirsky Trakt 10/7, Kazan, 420029 (Russian Federation); Kocharovskaya, Olga [Institute for Quantum Studies and Department of Physics, Texas A and M University, College Station, Texas 77843-4242 (United States)

    2011-05-15

    Off-resonant Raman interaction of a single-photon wave packet and a classical control field in an atomic medium with controlled refractive index is investigated. It is shown that a continuous change of refractive index during the interaction leads to the mapping of a single photon state to a superposition of atomic collective excitations (spin waves) with different wave vectors and vice versa. The suitability of refractive-index control for developing multichannel quantum memories is discussed and possible schemes of implementation are considered.

  19. Quantum storage via refractive index control

    E-print Network

    Alexey Kalachev; Olga Kocharovskaya

    2011-01-04

    Off-resonant Raman interaction of a single-photon wave packet and a classical control field in an atomic medium with controlled refractive index is investigated. It is shown that a continuous change of refractive index during the interaction leads to the mapping of a single photon state to a superposition of atomic collective excitations (spin waves) with different wave vectors and visa versa. The suitability of refractive index control for developing multichannel quantum memories is discussed and possible schemes of implementation are considered.

  20. Refractive index measurement using comparative interferometry

    NASA Astrophysics Data System (ADS)

    Bojan, Mihaela; Apostol, D.; Damian, V.; Logofatu, P. C.; Garoi, F.; Iordache, Iuliana

    2007-05-01

    The refractive index of a material medium is an important optical parameter since it exhibits the optical properties of the material. The adulteration problem is increasing day by day and hence simple, automatic and accurate measurement of the refractive index of materials is of great importance these days. For solid thin films materials Abeles method was reconsidered. Quick, measurements of refractive index using simple techniques and refractometers can help controlling adulteration of liquids of common use to a greater extent. Very simple interferometric set-up using Fizeau fringe patterns compares the fringe pitch as obtained in a cell with two levels: one down level with the unknown refractive index liquids and the upper level with gas air. A CCD matrix and a PC can handle the data and produce the results up to for digits.

  1. Microstructured optical fiber refractive index sensor.

    PubMed

    Town, Graham E; Yuan, Wu; McCosker, Ravi; Bang, Ole

    2010-03-15

    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 selective filling of the microstructure with analyte can increase the device sensitivity by approximately 1 order of magnitude. PMID:20237622

  2. Refractive index measurement by prism autocollimation

    NASA Astrophysics Data System (ADS)

    Cheng, Chao-Chia

    2014-03-01

    An autocollimation-based method for measuring the refractive indices of solid or liquids using a Littrow prism is presented. Measurement accuracy is enhanced by use of a telescope. In solids, the refractive index is accurate to three decimal places. Similar accuracy is obtained in liquids by correcting for the wedge angle of the liquid container window. The proposed prismatic method confers high accuracy, compactness, and automation. It is suitable for index measurement applications in undergraduate laboratories.

  3. Temperature-dependent Refractive Index of Silicon and Germanium

    NASA Technical Reports Server (NTRS)

    Frey, Bradley J.; Leviton, Douglas B.; Madison, Timothy J.

    2006-01-01

    Silicon and germanium are perhaps the two most well-understood semiconductor materials in the context of solid state device technologies and more recently micromachining and nanotechnology. Meanwhile, these two materials are also important in the field of infrared lens design. Optical instruments designed for the wavelength range where these two materials are transmissive achieve best performance when cooled to cryogenic temperatures to enhance signal from the scene over instrument background radiation. In order to enable high quality lens designs using silicon and germanium at cryogenic temperatures, we have measured the absolute refractive index of multiple prisms of these two materials using the Cryogenic, High-Accuracy Refraction Measuring System (CHARMS) at NASA's Goddard Space Flight Center, as a function of both wavelength and temperature. For silicon, we report absolute refractive index and thermo-optic coefficient (dn/dT) at temperatures ranging from 20 to 300 K at wavelengths from 1.1 to 5.6 pin, while for germanium, we cover temperatures ranging from 20 to 300 K and wavelengths from 1.9 to 5.5 microns. We compare our measurements with others in the literature and provide temperature-dependent Sellmeier coefficients based on our data to allow accurate interpolation of index to other wavelengths and temperatures. Citing the wide variety of values for the refractive indices of these two materials found in the literature, we reiterate the importance of measuring the refractive index of a sample from the same batch of raw material from which final optical components are cut when absolute accuracy greater than k5 x 10" is desired.

  4. Optics Problem: Index of Refraction

    NSDL National Science Digital Library

    Wolfgang Christian

    A beam of parallel rays propagating to the right is refracted upon entering and leaving another medium. Both the position of the source and the angle of the source can be adjusted by click-dragging the circular hotspots. Angles may also be measured by click- dragging away from the hotspots.

  5. Index profile of gradient refractive index ball lens using the nondestructive measurement method

    Microsoft Academic Search

    Zhao Cai; Hao Lv; Aimei Liu; Jufang Tong; Xunong Yi; Qianguang Li; Xinmin Wang; Yaoming Ding

    2010-01-01

    In this paper, the polynomial which is used to calculate the gradient refractive index profiles of gradient refractive index ball lenses is given, and the gradient refractive index profiles of gradient refractive index ball lenses can be measured using shearing interferometer rapidly, automatically and nondestructively. Comparing the measuring results with the previous reports, we find the gradient refractive index profiles

  6. Cosmology With A Dark Refraction Index

    E-print Network

    B. Chen; R. Kantowski

    2009-02-23

    We review Gordon's optical metric and the transport equations for the amplitude and polarization of a geometrical optics wave traveling in a gravity field. We apply the theory to the FLRW cosmologies by associating a refraction index with the cosmic fluid. We then derive an expression for the accumulated effect of a refraction index on the distance redshift relations and fit the Hubble curve of current supernova observations with a non-accelerating cosmological model. We also show that some observational effects caused by inhomogeneities, e.g. the Sachs-Wolfe effect, can be interpreted as being caused by an effective index of refraction, and hence this theory could extend to other speed of light communications such as gravitational radiation and neutrino fluxes.

  7. Plasmonic crystal enhanced refractive index sensing

    SciTech Connect

    Stein, Benedikt; Devaux, Eloïse; Genet, Cyriaque, E-mail: genet@unistra.fr; Ebbesen, Thomas W. [ISIS and icRFC, University of Strasbourg and CNRS, 8 allée Gaspard Monge, 67000 Strasbourg (France)

    2014-06-23

    We demonstrate experimentally how the local anisotropy of the dispersion relation of surface plasmon modes propagating over periodic metal gratings can lead to an enhancement of the figure of merit of refractive index sensors. Exploiting the possibility to acquire defocused images of the Fourier space of a highly stable leakage radiation microscope, we report a twofold increase in sensing sensitivity close to the band gap of a one-dimensional plasmonic crystal where the anisotropy of the band structure is the most important. A practical sensing resolution of O(10{sup ?6}) refractive index units is demonstrated.

  8. Nanofabrication of negative refractive index metasurfaces

    Microsoft Academic Search

    Zoran Jakši?; Dana Vasiljevi?-Radovi?; Milan Maksimovi?; Milija Sarajli?; Aleksandar Vujani?; Zoran Djuri?

    2006-01-01

    We designed and fabricated planar metamaterial ‘particles’ (metasurfaces) intended to achieve negative effective refractive index in mid-infrared. We considered double split ring resonators (negative permeability particles) with additional capacitive gaps to compensate for the inertial inductance, as well as complementary double split rings (negative permittivity). We calculated dispersion relations and considered scaling conditions for our structures. For the fabrication of

  9. Isotropic negative refractive index at near infrared

    NASA Astrophysics Data System (ADS)

    Morits, Dmitry; Simovski, Constantin

    2012-12-01

    In this paper we suggest and study a metamaterial composed of non-magnetic spherical particles, which according to both approximate analytical theory and exact simulations possesses an isotropic negative refractive index in the near-infrared frequency range. The effect of negative refraction has been confirmed by full-wave simulations of the Gaussian beam diverted by a metamaterial prism. The disagreement between predictions of the theory for an infinite lattice and the results of full-wave simulations for the prism is discussed.

  10. Humidity contribution to the refractive index structure function C2

    E-print Network

    Chang, Mark J. L.

    Humidity contribution to the refractive index structure function C2 n. Carlos O. Font, Mark P. J. L the strength of weak clear air turbulence's refractive index structure function, C2 n, but in all cases

  11. Matched Index of Refraction Flow Facility

    ScienceCinema

    Mcllroy, Hugh

    2013-05-28

    What's 27 feet long, 10 feet tall and full of mineral oil (3000 gallons' worth)? If you said INL's Matched Index of Refraction facility, give yourself a gold star. Scientists use computers to model the inner workings of nuclear reactors, and MIR helps validate those models. INL's Hugh McIlroy explains in this video. You can learn more about INL energy research at the lab's facebook site http://www.facebook.com/idahonationallaboratory.

  12. Matched Index of Refraction Flow Facility

    SciTech Connect

    Mcllroy, Hugh

    2010-01-01

    What's 27 feet long, 10 feet tall and full of mineral oil (3000 gallons' worth)? If you said INL's Matched Index of Refraction facility, give yourself a gold star. Scientists use computers to model the inner workings of nuclear reactors, and MIR helps validate those models. INL's Hugh McIlroy explains in this video. You can learn more about INL energy research at the lab's facebook site http://www.facebook.com/idahonationallaboratory.

  13. Scanning focused refractive-index microscopy

    PubMed Central

    Sun, Teng-Qian; Ye, Qing; Wang, Xiao-Wan; Wang, Jin; Deng, Zhi-Chao; Mei, Jian-Chun; Zhou, Wen-Yuan; Zhang, Chun-Ping; Tian, Jian-Guo

    2014-01-01

    We present a novel scanning focused refractive-index microscopy (SFRIM) technique to obtain the refractive index (RI) profiles of objects. The method uses a focused laser as the light source, and combines the derivative total reflection method (DTRM), projection magnification, and scanning technique together. SFRIM is able to determine RIs with an accuracy of 0.002, and the central spatial resolution achieved is 1?µm, which is smaller than the size of the focal spot. The results of measurements carried out on cedar oil and a gradient-refractive-index (GRIN) lens agree well with theoretical expectations, verifying the accuracy of SFRIM. Furthermore, using SFRIM, to the best of our knowledge we have extracted for the first time the RI profile of a periodically modulated photosensitive gelatin sample. SFRIM is the first RI profile-resolved reflected light microscopy technique that can be applied to scattering and absorbing samples. SFRIM enables the possibility of performing RI profile measurements in a variety of applications, including optical waveguides, photosensitive materials and devices, photorefractive effect studies, and RI imaging in biomedical fields. PMID:25008374

  14. Tissue refractive index as marker of disease

    NASA Astrophysics Data System (ADS)

    Wang, Zhuo; Tangella, Krishnarao; Balla, Andre; Popescu, Gabriel

    2011-11-01

    The gold standard in histopathology relies on manual investigation of stained tissue biopsies. A sensitive and quantitative method for in situ tissue specimen inspection is highly desirable, as it would allow early disease diagnosis and automatic screening. Here we demonstrate that quantitative phase imaging of entire unstained biopsies has the potential to fulfill this requirement. Our data indicates that the refractive index distribution of histopathology slides, which contains information about the molecular scale organization of tissue, reveals prostate tumors and breast calcifications. These optical maps report on subtle, nanoscale morphological properties of tissues and cells that cannot be recovered by common stains, including hematoxylin and eosin. We found that cancer progression significantly alters the tissue organization, as exhibited by consistently higher refractive index variance in prostate tumors versus normal regions. Furthermore, using the quantitative phase information, we obtained the spatially resolved scattering mean free path and anisotropy factor g for entire biopsies and demonstrated their direct correlation with tumor presence. In essence, our results show that the tissue refractive index reports on the nanoscale tissue architecture and, in principle, can be used as an intrinsic marker for cancer diagnosis.

  15. Epifilm thickness measurements using Fourier transform infrared spectroscopy: Effect of refractive index dispersion and refractive index measurement

    Microsoft Academic Search

    Zhen-Hong Zhou; Byungin Choi; M. I. Flik; S. Fan; Rafael Reif

    1994-01-01

    Procedures and results of refractive index measurements using a Fourier transform infrared spectrometer are reported. These measurements were performed on both lightly and heavily doped silicon samples over the midinfrared (2.5-25 micrometers) spectrum region. A strong dependence of refractive index as a function of substrate dopant concentration was observed. Moreover, it was observed that the refractive index of heavily doped

  16. Extremely high refractive index terahertz metamaterials Muhan Choi1

    E-print Network

    Park, Namkyoo

    Extremely high refractive index terahertz metamaterials Muhan Choi1 , Seung Hoon Lee1 , Yushin Kim1 of refraction from large-area, freestanding, flexible terahertz metamaterials. In addition, two different types of high index metamaterials are proposed for polarization-insensitive effective refractive indices

  17. Microwave gain medium with negative refractive index

    NASA Astrophysics Data System (ADS)

    Ye, Dexin; Chang, Kihun; Ran, Lixin; Xin, Hao

    2014-12-01

    Artificial effective media are attractive because of the fantastic applications they may enable, such as super lensing and electromagnetic invisibility. However, the inevitable loss due to their strongly dispersive nature is one of the fundamental challenges preventing such applications from becoming a reality. In this study, we demonstrate an effective gain medium based on negative resistance, to overcompensate the loss of a conventional passive metamaterial, meanwhile keeping its original negative-index property. Energy conservation-based theory, full-wave simulation and experimental measurement show that a fabricated sample consisting of conventional sub-wavelength building blocks with embedded microwave tunnel diodes exhibits a band-limited Lorentzian dispersion simultaneously with a negative refractive index and a net gain. Our work provides experimental evidence to the assertion that a stable net gain in negative-index gain medium is achievable, proposing a potential solution for the critical challenge current metamateiral technology faces in practical applications.

  18. Measurement of refractive index distribution of biotissues by scanning focused refractive index microscopy

    NASA Astrophysics Data System (ADS)

    Sun, Tengqian; Ye, Qing; Wang, Xiao-Wan; Wang, Jin; Deng, Zhi-Chao; Mei, Jian-Chun; Zhou, Wen-Yuan; Zhang, Chun-Ping; Tian, Jian-Guo

    2014-11-01

    We adapt the improved scanning focused refractive-index microscopy (SFRIM) technique to the quantitative study of biological tissues. Delicate refractive index (RI) imaging of a porcine muscle tissue is obtained in a reflection mode. Some modifications are made to the SFRIM for better two dimension (2-D) observation of the tissues. The RI accuracy is 0.002. The central spatial resolution of SFRIM achieves 1?m, smaller than the size of the focal spot. Our method is free from signal distortion. The experimental result demonstrates that SFRIM is a potential technique in a wide field of biomedical research.

  19. A Simple Method to Determine the Refractive Index of Glass.

    ERIC Educational Resources Information Center

    Mak, Se-yuen

    1988-01-01

    Describes an experiment for determining the refractive index. Discusses the experiment procedure and mathematical expression for calculating the index. Provides two geometrical diagrams and a graph for determining the index with a typical data. (YP)

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

    NASA Astrophysics Data System (ADS)

    Sulc, Miroslav

    2015-01-01

    Modified folded Jamin interferometer for on-line measurement of refractive index of gases was designed, constructed and tested. The accuracy of this interferometer is better than 10-6 and can be still approved about two orders by appropriate mathematical method. Interferometer is almost vibration insensitive with vibration noise equivalent to refractive index variation 2•10-9. The interferometer qualities were tested by air refractive index monitoring.

  1. Index of Refraction and Snellâ??s Law

    NSDL National Science Digital Library

    In this video from the ICT Center, learn about the index of refraction and Snellâ??s law. Review a simple example of refraction, the speed of light in materials, and the formula for calculating the index of refraction. Explore a table of the refractive indices of common media and materials used in fiber optics and semiconductors. Finally, examine Snell's law to understand the relationship between incident and refracted angles.The video runs 4:04 and is accompanied by a background essay, standards alignment, and discussion questions. Users who sign up for a free account can save the resource and download the video as well.

  2. Humidity contribution to the refractive index structure function C 2

    E-print Network

    Chang, Mark J. L.

    Humidity contribution to the refractive index structure function C 2 n . Carlos O. Font, Mark P. J index structure function, C 2 n , but in all cases they have major failings: either they are too general

  3. Refractive index investigations of nanoparticles dispersed in water

    NASA Astrophysics Data System (ADS)

    Bodurov, I.; Yovcheva, T.; Sainov, S.

    2014-12-01

    The refractive index of nanoparticles dispersed in water is measured, using the total internal reflection method. The critical angle is determined by the disappearance of diffraction orders from a metal grating. The investigated nanoparticles are titanium dioxide (anatase phase), (35 nm diameter), zinc oxide, (<50 nm diameter), zirconium dioxide, (<100 nm diameter). The refractive index is measured with the experimental uncertainty of 1%. The Lorentz-Lorenz, Maxwell Garnett and Bruggeman relations are applied in the nanoparticle's refractive indices calculations.

  4. Total external reflection from metamaterials with ultralow refractive index

    Microsoft Academic Search

    Brian T. Schwartz; Rafael Piestun

    2003-01-01

    Metamaterials composed of metal-dielectric nanostructures are engineered to have an effective refractive index less than unity at optical wavelengths. The effect of total external reflection is demonstrated when light from vacuum is incident onto these materials at an angle exceeding the critical angle defined by Snell's law. Novel approaches are discussed to derive the effective index of refraction from the

  5. String and Sticky Tape Experiments: Refractive Index of Liquids.

    ERIC Educational Resources Information Center

    Edge, R. D., Ed.

    1979-01-01

    Describes a simple method of measuring the refractive index of a liquid using a paper cup, a liquid, a pencil, and a ruler. Uses the ratio between the actual depth and the apparent depth of the cup to calculate the refractive index. (GA)

  6. Measurement of Refractive Index Using a Michelson Interferometer.

    ERIC Educational Resources Information Center

    Fendley, J. J.

    1982-01-01

    Describes a novel and simple method of measuring the refractive index of transparent plates using a Michelson interferometer. Since it is necessary to use a computer program when determining the refractive index, undergraduates could be given the opportunity of writing their own programs. (Author/JN)

  7. Fresnel or Refractive Index Ellipsoid - Interactive Java Tutorial

    NSDL National Science Digital Library

    The refractive index, or the Fresnel, ellipsoid has a radius that yields the refractive index (n) or the squre root of the dielectric constant for waves whose electric displacement vectors lie in the direction of the radius of the ellipsoid within an anisotropic medium.

  8. Measuring refractive index using the focal displacement method.

    PubMed

    Murray, Joel M; Wei, Jean; Barnes, Jacob O; Slagle, Jonathan E; Guha, Shekhar

    2014-06-10

    A simple technique is introduced for measuring the refractive index of plane-parallel samples having thickness of the order of a millimeter. The refractive index values are reported for six bulk semiconductors, each index measured at two infrared wavelengths using this method. The values are found to be within a few percent of those in literature for four semiconductors. The other two semiconductors were newly grown ternary alloys (CdMgTe and CdMnTe), for which the refractive index values have not been reported previously at the wavelengths studied here. PMID:24921140

  9. Broadband, Volumetric Negative-Refractive-Index Media

    NASA Astrophysics Data System (ADS)

    Rudolph, Scott M.

    Since their invention, negative-refractive-index (NRI) media have been plagued by three primary limitations: narrow bandwidth, high loss and polarization dependence. In this thesis, each of these problems is addressed. First, a new metamaterial topology that achieves negative permeability over a broad bandwidth is introduced. This structure is used to realize a broadband, volumetric NRI medium that is then thoroughly analyzed using multiconductor transmission line (MTL) theory. A homogenized, periodic form of MTL analysis is used to derive a simplified dispersion equation, as well as expressions for the Bloch impedance, permittivity and permeability for an infinite NRI medium. The analytical methods are supported by both full-wave simulation and measured results. Two broadband NRI lenses are presented: one contained inside a waveguide and the other in free space. Both lenses exhibit super-resolving capabilities: the first at 2.45GHz and the second at 10.435GHz. The transmission and reflection coefficients of the free-space lens are measured using a quasioptical Gaussian beam telescope, and the material parameters of the lens are extracted for these measurements. This lens exhibits a negative index of refraction over a fractional bandwidth of 41.2%. The low-loss performance of this metamaterial lens is experimentally verified. The lens exhibits 0.17dB of loss per unit cell and a figure of merit (FOM = n'/n'') of 31.4 at the operating frequency of 10.435GHz. These properties allow the recovery of evanescent spatial frequencies over a bandwidth of 7.4%. Additionally, the measured focal pattern at the image plane of the lens is accurately predicted using the material parameters obtained from the transmission measurements. A polarization-independent NRI medium is also reported. The design of this structure uses stereolithography and electroplating to complete the requisite three-dimensional fabrication on a large scale (more than 400 unit cells). The NRI bandwidth of this medium is 24%. A NRI lens that operates at 1.54GHz is designed and fabricated using this isotropic topology. At this frequency, the lens produced a super-resolved focus independent of the type of source and its polarization.

  10. Refractive index dispersions of liquid crystals

    NASA Astrophysics Data System (ADS)

    Wu, Shin T.; Wu, Chiung S.; Warenghem, Marc; Ismaili, M.

    1993-08-01

    Refractive indices of two nematic liquid crystals, 5CB and 5PCH, were measured from the 400- to 800-nm region at various temperatures. Results fit the three-band model well. Through comparisons, the contributions of (sigma) and (pi) electrons to the refractive indices and birefringence of uniaxial liquid crystals are evaluated quantitatively. These physical insights are useful for tailoring liquid crystal molecules with proper refractive indices.

  11. Nonlinear refractive index measurement by Fresnel diffraction from phase object

    NASA Astrophysics Data System (ADS)

    Beygi, Masood G.; Karimzadeh, Rouhollah; Dashtdar, Masoomeh

    2015-03-01

    A simple and sensitive technique, based on Fresnel diffraction from phase objects, is proposed for specifying the nonlinear refractive index of a sample. In this technique, the nonlinear refractive index is obtained by measurement of the normalized intensity distribution of the Fresnel diffraction patterns. The fringe diffraction patterns are formed due to the propagating monochromatic plane wave beam through a phase object. The phase object is the result of the changes in the refractive index due to the heating of the sample by absorbed small fraction of the pump laser power. The change in the refractive index at this region imposes a nonlinear shift on the phase of the illuminating probe beam that leads to the Fresnel diffraction. Simulation and experimental studies show that the technique is reliable and quite sensitive to refractive index change. A simple technique is proposed for measuring the nonlinear refractive index. The technique is based on the Fresnel diffraction from the phase object. The central fringe intensity is different for the focusing and defocusing media. By increasing the laser power, the number of the diffraction fringes is increased. The nonlinear refractive index is measured by best fitting the experimental data.

  12. Determination of the refractive index of paper with clearing agents

    NASA Astrophysics Data System (ADS)

    Fabritius, Tapio; Saarela, Juha; Myllyla, Risto

    2006-01-01

    The refractive index of paper was determined by measuring the propagation delay of photons in optically cleared paper boards. The determination was based on the assumption that photon propagation delay achieves minimum value as the paper is optimally cleared. The measured paper sheets was made from elemental chlorine-free market pulp, i.e. fully bleached, unbeaten, softwood kraft pulp. Nine different clearing agents with a refraction index between 1.329 and 1.741 were eLuperimented with. According to the streakmem measurements, the refractive index of the test paper was 1.557.

  13. Charged-particle acceleration through decreasing refractive index

    NASA Astrophysics Data System (ADS)

    Kong, Ling-Bao; Chen, Zhaoyang; Liu, Pu-Kun; Yu, Ming Young

    2015-02-01

    We propose a mechanism for electron acceleration in which circularly polarized electromagnetic waves (CPEMW) propagate along a uniform magnetic field in a medium with a tapered refractive index. Results show that with a decreasing refractive index and a moderate CPEMW electric field, e.g., 1.20 × 108 V/m, the relativistic factor of an electron can go above 14 after it travels 10 cm in the direction of CPEMW propagation. Without tapering of the refractive index, the maximum value of the relativistic factor is less than 2.92 under the same wave and guiding magnetic field conditions. Similar acceleration efficiency is found for electrons with different initial velocities.

  14. Determining the Thickness and Refractive Index of a Mirror

    ERIC Educational Resources Information Center

    Uysal, Ahmet

    2010-01-01

    When a laser beam reflects from a back surface glass mirror and falls on a screen, a pattern of discrete bright spots is created by partial reflection and refraction of the light at the air-glass interface and reflection at the mirror surface (Fig. 1). This paper explains how this phenomenon can be used to determine the refractive index and the…

  15. Automated measurement of the refractive index of fluids

    SciTech Connect

    Pixton, Bruce M.; Greivenkamp, John E

    2008-04-01

    A method for automating refractive-index measurements of fluids has been developed. An encoded rotation stage and position-sensitive detector enable automated reading of angles typically acquired by visual means. Two tunable lasers are used to obtain index measurements at ten discrete wavelengths across the visible spectrum. This method has been implemented on a Hilger-Chance refractometer from which the bulk refractive-index values for various transparent fluids have been measured. An index measurement accuracy of better than one part in the fourth decimal place for distilled water and a few parts in the fourth decimal place for higher index fluids is obtained.

  16. Interferometric measurement of the refractive-index distribution in plastic lenses by use of computed tomography.

    PubMed

    Suhara, Hiroyuki

    2002-09-01

    A nondestructive measurement method that makes possible the measurement of a three-dimensional refractive-index distribution of any shape plastic lens is presented. In this method, a Mach-Zehnder interferometer and shearing interferometer are combined into a single optical system and are used selectively. Interference fringes of a test object that is immersed in matching liquid are detected at various rotation angles. And transmitted wave fronts are calculated with these interference fringes. Finally, the refractive-index distribution is obtained by computed tomography analysis. In addition, accurate control of the matching liquid temperature makes it possible to measure the absolute refractive index of the test object. This system has good performance with a measurement accuracy of 10(-4) or better peak to valley. PMID:12211559

  17. Miniature interferometer for refractive index measurement in microfluidic chip

    NASA Astrophysics Data System (ADS)

    Chen, Minghui; Geiser, Martial; Truffer, Frederic; Song, Chengli

    2012-12-01

    The design and development of the miniaturized interferometer for measurement of the refractive index or concentration of sub-microliter volume aqueous solution in microfludic chip is presented. It is manifested by a successful measurement of the refractive index of sugar-water solution, by utilizing a laser diode for light source and the small robust instrumentation for practical implementation. Theoretically, the measurement principle and the feasibility of the system are analyzed. Experimental device is constructed with a diode laser, lens, two optical plate and a complementary metal oxide semiconductor (CMOS). Through measuring the positional changes of the interference fringes, the refractive index change are retrieved. A refractive index change of 10-4 is inferred from the measured image data. The entire system is approximately the size of half and a deck of cards and can operate on battery power for long time.

  18. Spatially Varying Index of Refraction: An Open Ended Undergraduate Topic.

    ERIC Educational Resources Information Center

    Krueger, David A.

    1980-01-01

    Presents an experiment on the bending of light in a medium with a continuously varying index of refraction. Several theoretical approaches for the analysis of this experiment, designed for college physics students, are also presented. (HM)

  19. Bubbly pipe flow study via refractive index matching

    Microsoft Academic Search

    K. N. Stanley; D. E. Nikitopoulos; M. A. Khan

    2002-01-01

    A phase-Doppler light-scattering method is used to measure, nonintrusively, liquid and bubble velocities and bubble size in vertical-upwards, dispersed, bubbly pipe flow. Bubble size measurements are also obtained with a video imaging technique. Optical distortion is eliminated, by using pipe material with index of refraction equal to that of water at room temperature, in combination with an index-of-refraction-matching box. Pure-liquid

  20. Mean effective size and refractive index of transparent atmospheric particulates

    NASA Technical Reports Server (NTRS)

    Fymat, A. L.

    1975-01-01

    It is demonstrated that the scattering ratio-principle originally restricted to exact forward and exact backward scattering, and to values of the size parameter and of the product (refractive index x size parameter) less than 0.8 has a much wider applicability. After relaxing these stringent conditions, it is also shown that this principle can be retained as the basis of an experimental technique for retrieving the mean effective size and refractive index of transparent atmospheric particulates.

  1. Theoretical schemes for negative refraction and enhanced refractive index in atomic systems

    NASA Astrophysics Data System (ADS)

    Sikes, Daniel E.

    In this thesis we present a scheme for negative refraction in atomic systems. Negative refraction was predicted over 4 decades ago and recently experimentally demonstrated in the field of metamaterials. We seek a new approach for negative refraction using laser driven transition resonances in atomic systems. By utilizing atomic resonances we hope to achieve negative refraction in short wavelength regimes, such as visible and ultra-violet, and eliminate absorption by quantum interference. This scheme is based on the experimentally demonstrated "refractive index enhancement with vanishing absorption" technique, in which closely spaced absorptive and amplifying transitions are interfered. Our scheme utilizes Raman transitions and is able to drive an electric resonance while far-detuned from an electric-dipole transition. This far-off resonance feature allows our scheme to be adaptable to various atomic energy level structures, in that it does not require the simultaneous presence of an electric-dipole and a magnetic-dipole transition near the same wavelength. We show that two interfering Raman transitions coupled to a magnetic-dipole transition can achieve a negative index of refraction with low absorption through magnetoelectric cross coupling. Analytical predictions have been made for a model atomic system and their validity has been confirmed with exact numerical simulations of the density matrix. We consider possible experimental implementations of the scheme in rare-earth atomic systems, such as ultracold vapors and doped crystals. We also discuss applications of negative and enhanced refractive index for imaging. A fundamental challenge of imaging systems is the diffraction limit, which causes spatial features of an object smaller than the light wavelength to be lost in the image. Achieving negative refraction with vanishing absorption is important for near-perfect imaging systems based on Pendry's suggestion for a negative index perfect lens. A perfect lens is able to focus the light related to small spatial features through the ability of negative index materials to "amplify" evanescent waves. Alternatively, enhanced refractive index improves imaging resolution by effectively decreasing light wavelength by a factor inversely with refractive index. Additionally we consider proposals for all-optical devices based on refractive index enhancement such as a low-photon conditional phase shifter and a distributed Bragg reflector.

  2. Complex refractive index and color of quinacridone pigments

    NASA Astrophysics Data System (ADS)

    Kettler, Wilhelm H.

    2002-06-01

    Complex refractive index of pigment violet 19 (?- modification) was determined by means of an ellipsometric method within the visible spectral range. From the known complex refractive index and the particle size of the pigment, single-scattering properties (scattering and extinction efficiency, asymmetry parameter) were calculated for vehicles of different refractive indices employing an algorithm based on Mie-theory for spherical particles. These parameters were fed into a multiple-scattering model to investigate the dependence of reflectance of a semi-infinite film on particle size and refractive index of the embedding medium. Theoretically calculated results are in reasonable agreement with corresponding experimentally determined reflectance spectra of pigment violet 19 dispersed in different solvent- and water-based resin systems.

  3. Three-dimensional optical metamaterial with a negative refractive index

    Microsoft Academic Search

    Jason Valentine; Shuang Zhang; Thomas Zentgraf; Erick Ulin-Avila; Dentcho A. Genov; Guy Bartal; Xiang Zhang

    2008-01-01

    Metamaterials are artificially engineered structures that have properties, such as a negative refractive index, not attainable with naturally occurring materials. Negative-index metamaterials (NIMs) were first demonstrated for microwave frequencies, but it has been challenging to design NIMs for optical frequencies and they have so far been limited to optically thin samples because of significant fabrication challenges and strong energy dissipation

  4. Negative light refraction in a gradient medium with ultrasound-modulated refractive index

    NASA Astrophysics Data System (ADS)

    Naimi, E. K.; Vekilov, Yu. Kh.

    2015-01-01

    The conditions of the formation of a spatially ordered optical structure with an ultrasound-modulated refractive index in a gradient medium have been considered. It has been shown that the excitation of a standing ultrasonic wave in the medium creates a structure consisting of trajectories of separate light beams, which is a superlattice of the "dynamic 4D photonic crystal." Regions corresponding to negative light refraction have been revealed in beam trajectories. Possible fields of application of such structures have been discussed.

  5. Two-dimensional scanning focused refractive-index microscopy and applications to refractive-index profiling of optical fibers

    NASA Astrophysics Data System (ADS)

    Wang, Xiaowan; Ye, Qing; Sun, Tengqian; Wang, Jin; Deng, Zhichao; Mei, Jianchun; Zhou, Wenyuan; Zhang, Chunping; Tian, Jianguo

    2015-01-01

    The refractive-index profile (RIP) of optical fibers is of fundamental significance in determining critical fiber properties. Here, we present the application of a two-dimensional (2-D) scanning focused refractive-index microscopy (SFRIM) to accurately obtain the 2-D RIP of a graded-index optical fiber. Some modifications are made to SFRIM for better 2-D measurement. Quantitative RIP of the fiber is obtained with derivative total reflection method. The refractive-index accuracy is 0.002. The measured result is in good agreement with theoretical expectation. This method is straightforward, simple, repeatable, and free from signal distortion. This technique is suitable for symmetric and asymmetric optical fibers. The results indicate that this technique can be applied to obtain the RIPs of a wide range of materials and has broad application prospect in many fields.

  6. Evidence of Negative-Index Refraction in Nonlinear Chemical Waves

    NASA Astrophysics Data System (ADS)

    Yuan, Xujin; Wang, Hongli; Ouyang, Qi

    2011-05-01

    The negative index of refraction of nonlinear chemical waves has become a recent focus in nonlinear dynamics researches. Theoretical analysis and computer simulations have predicted that the negative index of refraction can occur on the interface between antiwaves and normal waves in a reaction-diffusion (RD) system. However, no experimental evidence has been found so far. In this Letter, we report our experimental design in searching for such a phenomenon in a chlorite-iodide-malonic acid (CIMA) reaction. Our experimental results demonstrate that competition between waves and antiwaves at their interface determines the fate of the wave interaction. The negative index of refraction was only observed when the oscillation frequency of a normal wave is significantly smaller than that of the antiwave. All experimental results were supported by simulations using the Lengyel-Epstein RD model which describes the CIMA reaction-diffusion system.

  7. Isotropic spiral plasmonic metamaterial for sensing large refractive index change.

    PubMed

    Ren, Mengxin; Pan, Chongpei; Li, Qunqing; Cai, Wei; Zhang, Xinzheng; Wu, Qiang; Fan, Shoushan; Xu, Jingjun

    2013-08-15

    We numerically investigate the optical properties of a spiral G-shaped metamaterial, which exhibits both a sharp resonance with a high-quality factor and a broad resonance with a long linear slope in the near-infrared region. By employing the sharp resonating mode, refractive index sensing with sensitivity up to 410 nm/RIU is demonstrated theoretically. In addition, the metamaterial shows single wavelength sensing ability, which allows fast determination of environmental refractive index changes as large as 0.5 by simply monitoring variations in the transmitted intensity of a certain wavelength, which will be beneficial to the development of refractive index sensors based on monochromatic light sources and detectors. As the resonances are independent of the polarization direction of a linearly polarized wave, the sensor manufacturing process will benefit as a result of the lack of an alignment requirement for the axis of polarizers with the metamaterials' orientation. PMID:24104668

  8. Refractive-index sensing with ultra-thin plasmonic nanotubes

    E-print Network

    Raza, S; Jauho, A -P; Mortensen, N A; Wubs, M

    2012-01-01

    We study the refractive-index sensing properties of plasmonic nanotubes with a dielectric core and ultra-thin metal shell. The few-nm thin metal shell is described by both the usual Drude model and the nonlocal hydrodynamic model to investigate the effects of nonlocality. We derive an 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 superior sensitivity and comparable figure-of-merit.

  9. Gravitational Lensing Analyzed by Graded Refractive Index of Vacuum

    E-print Network

    Xing-Hao Ye; Qiang Lin

    2008-02-13

    We found strong similarities between the gravitational lensing and the conventional optical lensing. The similarities imply a graded refractive index description of the light deflection in gravitational field. We got a general approach to this refractive index in a static spherically symmetric gravitational field and obtained its exterior and interior solutions exactly through the general relativity. In weak field case, the two solutions come to a simple unified exponential function of the gravitational potential. With these results, the gravitational lensing can be analyzed in a convenient optical way. Especially, the long puzzling problem of the central image missing can be solved easily. We also pointed out that the graded refraction property of the gravitational spacetime is related to the vacuum influenced by the gravitational matter.

  10. Cryogenic Temperature-Dependent Refractive Index Measurements of CaF2 and Infrasil 301

    NASA Technical Reports Server (NTRS)

    Frey, Bradley J.; Leviton, Douglas B.; Madison, TImothy J.

    2007-01-01

    In order to enable high quality lens design using calcium fluoride (CaF2) and Heraeus Infrasil 30 (Infrasil) at cryogenic temperatures, we have measured the absolute refractive index of prisms of these two materials using the Cryogenic, High-Accuracy Refraction Measuring System (CHARMS) at NASA's Goddard Space Flight Center, as a function of both wavelength and temperature. For CaF2, we report absolute refractive index and thermo-optic coefficient (dn/dT) at temperatures ranging from 25 to 300 K at wavelengths from 0.4 to 5.6 micrometers; for Infrasil we cover temperatures ranging from 35 to 300K and wavelengths from 0.4 to 3.6 micrometers. We investigate the interspecimen variability between measurements of two unrelated samples of CaF2, and we also compare our results for Infrasil to previous measurements fo Corning 7980 fused silica. Finally, we provide temperature-dependent Sellmeier coefficients based on our data to allow accurate interpolation of index to other wavelengths and temperatures and compare those results to other data found in the literature.

  11. Highly sensitive fiber Bragg grating refractive index sensors

    NASA Astrophysics Data System (ADS)

    Liang, Wei; Huang, Yanyi; Xu, Yong; Lee, Reginald K.; Yariv, Amnon

    2005-04-01

    We combine fiber Bragg grating (FBG) technology with a wet chemical etch-erosion procedure and demonstrate two types of refractive index sensors using single-mode optical fibers. The first index sensor device is an etch-eroded single FBG with a radius of 3?m, which is used to measure the indices of four different liquids. The second index sensor device is an etch-eroded fiber Fabry-Pérot interferometer (FFPI) with a radius of ˜1.5?m and is used to measure the refractive indices of isopropyl alcohol solutions of different concentrations. Due to its narrower resonance spectral feature, the FFPI sensor has a higher sensitivity than the FBG sensor and can detect an index variation of 1.4×10-5. Since we can measure the reflection signal, these two types of sensors can be fabricated at the end of a fiber and used as point sensors.

  12. High temperature-gradient refractive index liquid crystals

    E-print Network

    Wu, Shin-Tson

    . Finkenzeller, Liquid Crystals: Applications and Uses (World Scientific, Singapore, 1990), Chap. 4. (C) 2004 OSA 26 April 2004; accepted 26 April 2004 #12;1. Introduction Besides displays [1, 2], liquid crystal (LCHigh temperature-gradient refractive index liquid crystals Jun Li, Sebastian Gauzia, and Shin

  13. Bioluminescence tomography for media with spatially varying refractive index

    Microsoft Academic Search

    R. F. Gong; X.-L. Cheng; W. Han

    2010-01-01

    Biomedical imaging has developed into the level of molecular imaging. Bioluminescence tomography (BLT), as an optical imaging modality, is a rapidly developing new and promising field. So far, much of the theoretical analysis of BLT is based on a diffusion approximation equation for media with constant refractive index. In this article, we study the BLT problem for media with spatially

  14. Experimental Verification of a Negative Index of Refraction

    Microsoft Academic Search

    R. A. Shelby; D. R. Smith; S. Schultz

    2001-01-01

    We present experimental scattering data at microwave frequencies on a structured metamaterial that exhibits a frequency band where the effective index of refraction (n) is negative. The material consists of a two-dimensional array of repeated unit cells of copper strips and split ring resonators on interlocking strips of standard circuit board material. By measuring the scattering angle of the transmitted

  15. Unidirectional transmission using array of zero-refractive-index metamaterials

    SciTech Connect

    Fu, Yangyang; Xu, Lin; Hong Hang, Zhi; Chen, Huanyang, E-mail: chy@suda.edu.cn [School of Physical Science and Technology, Soochow University, Suzhou 215006 (China)

    2014-05-12

    In this Letter, we find that high efficient unidirectional transmission occurs for an array of prisms made of zero-refractive-index metamaterials. As a specific demonstration, we further design the device using Dirac-cone-like photonic crystals. The device can function for a broadband of spectrum. Numerical simulations are performed to verify the one-way wave functionality.

  16. An updated equation for the refractive index of air

    NASA Astrophysics Data System (ADS)

    Li, Wenchen; Dai, Zuoxiao; Dai, Ning; Chen, Ren; Sun, Xiaojie; Xia, Xiang; Li, Tao; Ma, Bei; Sheng, Hao

    2014-12-01

    Laser has been widely used in spectroscopic and metrological measurement. High-precision laser metrology is affected by the refractive index of air. In order to apply the algorithm for the refractive index of air in some situation where low calculation complexity and high-precision are needed, the algorithm of the refractive index of Rueger is updated. As the errors of Rueger's algorithm are mainly affected by temperature, humidity, and the concentration of carbon dioxide in the atmosphere as well as laser wavelength, we do some revisions about these effects of the factors of atmosphere in Rueger's algorithm. The conditions of standard air is redefined in this paper because of the average concentration of carbon dioxide in the atmosphere has been changed in the past few decades. As the concentration of carbon dioxide in the air is not constant, the effect of carbon dioxide on the refractive index of air is taken into consideration in the updated algorithm. The updated algorithm adapts to the real atmosphere well. The effects of dry air and humid air on the algorithm are also corrected, and the refractive index of air calculated by the updated algorithm is much closer to that of Philip E.Ciddor's algorithm defined as reference algorithm in the paper because of its high-precision. The performance of the updated algorithm is also analyzed in this paper. It is compared to that of the reference algorithm and the real measured data. Comparing results show that the performance of the algorithm has been improved after the correction. Comparing to the reference algorithm, the performance of the updated algorithm is a little bit lower, but the updated algorithm is much simpler and easier to be applied. Comparing to Rueger's algorithm, the performance of the updated algorithm is much higher and the complexity of the updated algorithm increases very small. The updated algorithm meets low calculation complexity and high-precision requirements.

  17. Refractive index and birefringence of 2H silicon carbide

    NASA Technical Reports Server (NTRS)

    Powell, J. A.

    1972-01-01

    The refractive indices of 2H SiC were measured over the wavelength range 435.8 to 650.9 nm by the method of minimum deviation. At the wavelength lambda = 546.1 nm, the ordinary index n sub 0 was 2.6480 and the extraordinary index n sub e was 2.7237. The estimated error (standard deviation) in the measured values is 0.0006 for n sub 0 and 0.0009 for n sub e. The experimental data were curve fitted to the Cauchy equation for the index of refraction as a function of wavelength. The birefringence of 2H SiC was found to vary from 0.0719 at lambda = 650.9 nm to 0.0846 at lambda = 435.8 nm.

  18. Structures with negative index of refraction

    DOEpatents

    Soukoulis, Costas M. (Ames, IA); Zhou, Jiangfeng (Ames, IA); Koschny, Thomas (Ames, IA); Zhang, Lei (Ames, IA); Tuttle, Gary (Ames, IA)

    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.

  19. Ultrafast refractive index control of a terahertz graphene metamaterial

    NASA Astrophysics Data System (ADS)

    Lee, Seung Hoon; Choi, Jeongmook; Kim, Hyeon-Don; Choi, Hyunyong; Min, Bumki

    2013-07-01

    Modulation of the refractive index of materials is elementary, yet it is crucial for the manipulation of electromagnetic waves. Relying on the inherent properties of natural materials, it has been a long-standing challenge in device engineering to increase the index-modulation contrast. Here, we demonstrate a significant amount of ultrafast index modulation by optically exciting non-equilibrium Dirac fermions in the graphene layer integrated onto a high-index metamaterial. Furthermore, an extremely-large electrical modulation of refractive index up to ?n ~ -3.4 (at 0.69 THz) is achieved by electrical tuning of the density of the equilibrium Dirac fermion in the graphene metamaterial. This manifestation, otherwise remaining elusive in conventional semiconductor devices, fully exploits the characteristic ultrafast charge relaxation in graphene as well as the strong capacitive response of the metamaterial, both of which enable us to drastically increase the light-matter interaction of graphene and the corresponding index contrast in the graphene metamaterials.

  20. Ultrafast refractive index control of a terahertz graphene metamaterial

    PubMed Central

    Lee, Seung Hoon; Choi, Jeongmook; Kim, Hyeon-Don; Choi, Hyunyong; Min, Bumki

    2013-01-01

    Modulation of the refractive index of materials is elementary, yet it is crucial for the manipulation of electromagnetic waves. Relying on the inherent properties of natural materials, it has been a long-standing challenge in device engineering to increase the index-modulation contrast. Here, we demonstrate a significant amount of ultrafast index modulation by optically exciting non-equilibrium Dirac fermions in the graphene layer integrated onto a high-index metamaterial. Furthermore, an extremely-large electrical modulation of refractive index up to ?n ~ ?3.4 (at 0.69?THz) is achieved by electrical tuning of the density of the equilibrium Dirac fermion in the graphene metamaterial. This manifestation, otherwise remaining elusive in conventional semiconductor devices, fully exploits the characteristic ultrafast charge relaxation in graphene as well as the strong capacitive response of the metamaterial, both of which enable us to drastically increase the light-matter interaction of graphene and the corresponding index contrast in the graphene metamaterials. PMID:23823715

  1. Index of Refraction of Shock Loaded Soda-Lime Glass

    NASA Astrophysics Data System (ADS)

    Alexander, Scott

    2009-06-01

    Soda-lime glass (SLG) is a potential low-cost VISAR window for use at moderate shock pressures (up to approximately 25 GPa) where the material remains transparent. In order for SLG to be practical as a VISAR window, the correction factor, which describes the frequency correction related to the strain dependence of the refractive index, and hence the index of refraction itself, must be characterized as a function of pressure. Characterization data are reported in this paper and compared to previous results. The present data show good agreement with those of Dandekar [J. App. Physics, 84, 6614 (1998)] and separate study results by Gibbons and Ahrens [J. Geophys. Res., 76, 5489 (1971)] up to 7 GPa. However, at stresses over 7 GPa, marked discrepancies are evident between the present data and that of Gibbons and Ahrens. Differences in test methods may explain these discrepancies.

  2. The whistler mode refractive index as a function of gyrofrequency

    SciTech Connect

    Albert, J. M. [Air Force Research Laboratory/RVBX, Kirtland AFB, New Mexico 87117 (United States)

    2011-08-15

    The refractive index for a constant-frequency whistler mode wave in an electron-proton plasma is considered as a function of position, through the local gyrofrequencies {Omega}{sub e,i}. The full cold plasma dispersion relation is used. The wave frequency can take any value up to the smaller of {Omega}{sub e} and the plasma frequency {omega}{sub pe}, but {omega}{sub pe} is allowed to take any fixed value, as is the wavenormal angle. It is rigorously established that the refractive index is a decreasing function of {Omega}{sub e}. One application of this is to finding locations of Landau and cyclotron resonances, to evaluate the effects of whistler mode waves on radiation belt electrons.

  3. Refractive index fiber sensor based on cladding modes interference

    NASA Astrophysics Data System (ADS)

    Tatar, Peter; Kacik, Daniel; Schuster, Kay

    2014-12-01

    We present the optical fiber sensor based on fused silica capillary as a sensing element spliced between the lead-in and lead-out singlemode (SM) fibers. In the region of the splice the cladding modes of capillary are excited from the fundamental mode of led-in SM fiber. The intermodal interference of the propagating cladding modes results in the formation of the resonant peaks in the transmission spectrum. With the variations of the external refractive index the shift of resonance wavelength of the peak can be observed. The sensitivity for the refractive index values around n=1.33 is observed and using the wet etching technique can be increased, what gives an assumption for its using in a biomedical sensing applications.

  4. Complex refractive index of Martian dust - Mariner 9 ultraviolet observations

    NASA Technical Reports Server (NTRS)

    Pang, K.; Ajello, J. M.; Hord, C. W.; Egan, W. G.

    1976-01-01

    Mariner 9 ultraviolet spectrometer observations of the 1971 dust clouds obscuring the surface of Mars have been analyzed by matching the observed dust phase function with Mie scattering calculations for size distributions of homogeneous and isotropic material. Preliminary results indicate an effective particle radius of not less than 0.2. The real component of the index of refraction is not less than 1.8 at both 268 and 305 nm; corresponding values for the imagery component are 0.02 and 0.01. These values are consistent with those found by Mead (1970) for the visible and near-visible wavelengths. The refractive index and the absorption coefficient increase rapidly with decreasing wavelength in going from the visible to the ultraviolet, indicating the presence of an ultraviolet absorption band which may shield organisms from ultraviolet irradiation.

  5. Temperature Coefficients of the Refractive Index for Complex Hydrocarbon Mixtures

    NASA Astrophysics Data System (ADS)

    Wen, Qing; Shen, Jun; Gieleciak, Rafal; Michaelian, Kirk H.; Rohling, Jurandir H.; Astrath, Nelson G. C.; Baesso, Mauro L.

    2014-05-01

    Temperature coefficients of the refractive index () in the to temperature interval for hydrocarbon mixtures containing as many as 14 compounds were investigated in this work. The measured of the mixtures were compared with calculations based on the values for each compound and their concentrations. Differences of about 1 % between measured and calculated values were observed for all mixtures. The additivity of for these hydrocarbons enables preparation of surrogate fuels that are formulated to have properties like those of specific diesel fuels.

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

    PubMed Central

    Jorge, Pedro A. S.; Silva, Susana O.; Gouveia, Carlos; Tafulo, Paula; Coelho, Luis; Caldas, Paulo; Viegas, Diana; Rego, Gaspar; Baptista, José M.; Santos, José L.; Frazão, Orlando

    2012-01-01

    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. PMID:22969405

  7. GROUP THEORY BASED DESIGN OF ISOTROPIC NEGATIVE REFRACTIVE INDEX METAMATERIALS

    Microsoft Academic Search

    N. Wongkasemand; A. Akyurtlu; K. A. Marx

    2006-01-01

    Abstract—Novel isotropic planar and three-dimensional negative refractive index (NRI) metamaterial (MTM) designs consisting of periodically arranged cross structures are developed in the terahertz (THz) frequency regime using group theory. The novel designs not only avoid magnetoelectric coupling but also enable a simplified fabrication process. Using Finite-difference Time-Domain (FDTD) simulations, the design exhibits an NRI passband which is in good agreement

  8. Light localization induced by a random imaginary refractive index

    NASA Astrophysics Data System (ADS)

    Basiri, A.; Bromberg, Y.; Yamilov, A.; Cao, H.; Kottos, T.

    2014-10-01

    We show the emergence of light localization in arrays of coupled optical waveguides with randomness only in the imaginary part of their refractive index and develop a one-parameter scaling theory for the normalized participation number of Floquet-Bloch modes. This localization introduces a different length scale in the decay of the autocorrelation function of a paraxial beam propagation. Our results are relevant to a vast family of systems with randomness in the dissipative part of their impedance spatial profile.

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

    E-print Network

    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.

  10. Negative Refractive Index in Left-Handed Materials

    Microsoft Academic Search

    David R. Smith; Norman Kroll

    2000-01-01

    The real part of the refractive index n\\\\(omega\\\\) 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\\\\(omega\\\\), demonstrating frequency regions where the sign of Re[n\\\\(omega\\\\)

  11. Organic Plasmon-Emitting Diodes for Detecting Refractive Index Variation

    PubMed Central

    Chiu, Nan-Fu; Cheng, Chih-Jen; Huang, Teng-Yi

    2013-01-01

    A photo-excited organic layer on a metal thin film with a corrugated substrate was used to generate surface plasmon grating coupled emissions (SPGCEs). Directional emissions corresponded to the resonant condition of surface plasmon modes on the Au/air interface. In experimental comparisons of the effects of different pitch sizes on the plasmonic band-gap, the obtained SPGCEs were highly directional, with intensity increases as large as 10.38-fold. The FWHM emission spectrum was less than 70 nm. This method is easily applicable to detecting refractive index changes by using SP-coupled fluorophores in which wavelength emissions vary by viewing angle. The measurements and calculations in this study confirmed that the color wavelength of the SPGCE changed from 545.3 nm to 615.4 nm at certain viewing angles, while the concentration of contacting glucose increased from 10 to 40 wt%, which corresponded to a refractive index increase from 1.3484 to 1.3968. The organic plasmon-emitting diode exhibits a wider linearity range and a resolution of the experimental is 1.056 × 10?3 RIU. The sensitivity of the detection limit for naked eye of the experimental is 0.6 wt%. At a certain viewing angle, a large spectral shift is clearly distinguishable by the naked eye unaided by optoelectronic devices. These experimental results confirm the potential applications of the organic plasmon-emitting diodes in a low-cost, integrated, and disposable refractive-index sensor. PMID:23812346

  12. Origami with negative refractive index to generate super-lenses

    NASA Astrophysics Data System (ADS)

    Guenneau, Fanny; Chakrabarti, Sangeeta; Guenneau, Sebastien; Ramakrishna, S. Anantha

    2014-10-01

    Negative refractive index materials (NRIM) enable unique effects including superlenses with a high degree of sub-wavelength image resolution, a capability that stems from the ability of NRIM to support a host of surface plasmon states. Using a generalized lens theorem and the powerful tools of transformational optics, a variety of focusing configurations involving complementary positive and negative refractive index media can be generated. A paradigm of such complementary media are checkerboards that consist of alternating cells of positive and negative refractive index, and are associated with very singular electromagnetics. We present here a variety of multi-scale checkerboard lenses that we call origami lenses and investigate their electromagnetic properties both theoretically and computationally. Some of these meta-structures in the plane display thin bridges of complementary media, and this highly enhances their plasmonic response. We demonstrate the design of three-dimensional checkerboard meta-structures of complementary media using transformational optics to map the checkerboard onto three-dimensional corner lenses, the only restriction being that the corresponding unfolded structures in the plane are constrained by the four color-map theorem.

  13. Surface plasmon resonance based fiber optic refractive index sensors

    NASA Astrophysics Data System (ADS)

    Hlubina, Petr; Kadulova, Miroslava; Ciprian, Dalibor

    2014-12-01

    Refractive index sensors based on surface plasmon resonance (SPR) in a thin metal film deposited on an unclad core of a multimode fiber are presented. The sensing element of the fiber optic SPR sensors is a bare core of a step-index optical fiber made of fused silica with a double-sided sputtered gold film. First, an in-line transmissionbased sensing scheme with the fiber optic SPR probe is used. Second, a reflection-based sensing scheme with a terminated fiber optic SPR probe is employed. The fiber optic SPR probes have different lengths and the thickness of the sputtered gold film is about 50 nm. Both sensing schemes utilize a wavelength interrogation method so that the refractive index of a liquid is sensed by measuring the position of the dip in the transmitted or reflected spectral intensity distribution. As an example, the aqueous solutions of ethanol with refractive indices in a range from 1.333 to 1.364 are measured. For the transmission-based sensing scheme a polarization-dependent response is revealed.

  14. Refractive index of glass and its dipersion for visible light.

    SciTech Connect

    Smith, D. Y.; Karstens, W. (Physics); (Univ. of Vermont); (Saint Michael's Coll.)

    2010-01-01

    The classification of optical glass and empirical relations between the refractive index and its dispersion are discussed in terms of moments of the glass's IR and UV absorption spectra. The observed linear dependence of index on dispersion within glass families is shown to arise primarily from the approximately linear superposition of the electronic absorptions of glass former and glass modifiers. The binary classification into crown and flint glasses is also based primarily on electronic spectra: Crown glasses are 'wide-gap' materials with excitation energies greater than {approx}12.4 eV, while flint glasses are their 'narrow-gap' counterpart.

  15. High refractive index and temperature sensitivity LPGs for high temperature operation

    NASA Astrophysics Data System (ADS)

    Nascimento, I. M.; Gouveia, C.; Jana, Surnimal; Bera, Susanta; Baptista, J. M.; Moreira, Paulo; Biwas, Palas; Bandyopadhyay, Somnath; Jorge, Pedro A. S.

    2013-11-01

    A fiber optic sensor for high sensitivity refractive index and temperature measurement able to withstand temperature up to 450 °C is reported. Two identical LPG gratings were fabricated, whereas one was coated with a high refractive index (~1.78) sol-gel thin film in order to increase its sensitivity to the external refractive index. The two sensors were characterized and compared in refractive index and temperature. Sensitivities of 1063 nm/RIU (1.338 - 1.348) and 260 pm/°C were achieved for refractive index and temperature, respectively.

  16. Polymeric nanolayered gradient refractive index lenses: technology review and introduction of spherical gradient refractive index ball lenses

    NASA Astrophysics Data System (ADS)

    Ji, Shanzuo; Yin, Kezhen; Mackey, Matthew; Brister, Aaron; Ponting, Michael; Baer, Eric

    2013-11-01

    A nanolayered polymer films approach to designing and fabricating gradient refractive index (GRIN) lenses with designer refractive index distribution profiles and an independently prescribed lens surface geometry have been demonstrated to produce a new class of optics. This approach utilized nanolayered polymer materials, constructed with polymethylmethacrylate and a styrene-co-acrylonitrile copolymer with a tailorable refractive index intermediate to bulk materials, to fabricate discrete GRIN profile materials. A process to fabricate nanolayered polymer GRIN optics from these materials through thermoforming and finishing steps is reviewed. A collection of technology-demonstrating previously reported nanolayered GRIN case studies is presented that include: (1) the optical performance of a f/# 2.25 spherical GRIN plano-convex singlet with one quarter (2) the weight of a similar BK7 lens and a bio-inspired aspheric human eye GRIN lens. Original research on the fabrication and characterization of a Luneburg inspired GRIN ball lens is presented as a developing application of the nanolayered polymer technology.

  17. Plasmonic nanoshell functionalized etched fiber Bragg gratings for highly sensitive refractive index measurements.

    PubMed

    Burgmeier, Jörg; Feizpour, Amin; Schade, Wolfgang; Reinhard, Björn M

    2015-02-15

    A novel fiber optical refractive index sensor based on gold nanoshells immobilized on the surface of an etched single-mode fiber including a Bragg grating is demonstrated. The nanoparticle coating induces refractive index dependent waveguide losses, because of the variation of the evanescently guided part of the light. Hence the amplitude of the Bragg reflection is highly sensitive to refractive index changes of the surrounding medium. The nanoshell functionalized fiber optical refractive index sensor works in reflectance mode, is suitable for chemical and biochemical sensing, and shows an intensity dependency of 4400% per refractive index unit in the refractive index range between 1.333 and 1.346. Furthermore, the physical length of the sensor is smaller than 3 mm with a diameter of 6 ?m, and therefore offers the possibility of a localized refractive index measurement. PMID:25680146

  18. Extraction of complex refractive index dispersion from SPR data

    NASA Astrophysics Data System (ADS)

    Nakkach, Mohamed; Moreau, Julien; Canva, Michael

    2010-02-01

    Surface Plasmon Resonnance (SPR) techniques have been mostly set-up as angular reflectivity interrogation mode using quasi-monochromatic light or as spectral reflectivity interrogation mode at one given wavelength, providing information about variation of effective optical thickness ?n.e above the metal surface. In this communication we present a dual mode sensor working both in angular and spectral interrogation modes. A white light illuminates the sensor surface and the reflectivity spectra in TE and TM polarization are measured with a spectrometer. By changing the angular coupling conditions, a complete reflectivity surface R(?, ?) can be measured. The 2D reflectivity decrease valley is affected by both the real and imaginary part of the optical index of the dielectric medium as well as their spectral dispersion. With such experimental data set, it is possible to back calculate the dispersion of the complex refractive index of the dielectric layer. This is demonstrated using a turquoise dye doped solution. According to the Kramers-Kronig relations, the imaginary part of the refractive index for an absorbing medium is proportional to the absorption while the real part presents a large dispersion around the absorption wavelength. The reflectivity surface R(?, ?) was measured from 500 nm to 750 nm over about 8° angular range. The whole complex refractive optical index of the doped solution, absorbing around 630 nm, was reconstructed from the SPR reflectivity experimental data, using a homemade program based on an extended Rouard method to fit the experimental angular plasmon data for each wavelength. These results show that the classical SPR technique can be extended to acquire precise spectral information about biomolecular interactions occurring on the metallic layer.

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

    E-print Network

    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.

  20. Tissue Refractive Index Fluctuations Report on Cancer Development

    NASA Astrophysics Data System (ADS)

    Popescu, Gabriel

    2012-02-01

    The gold standard in histopathology relies on manual investigation of stained tissue biopsies. A sensitive and quantitative method for in situ tissue specimen inspection is highly desirable, as it will allow early disease diagnosis and automatic screening. Here we demonstrate that quantitative phase imaging of entire unstained biopsies has the potential to fulfill this requirement. Our data indicates that the refractive index distribution of histopathology slides, which contains information about the molecular scale organization of tissue, reveals prostate tumors. These optical maps report on subtle, nanoscale morphological properties of tissues and cells that cannot be recovered by common stains, including hematoxylin and eosin (H&E). We found that cancer progression significantly alters the tissue organization, as exhibited in our refractive index maps. Furthermore, using the quantitative phase information, we obtained the spatially resolved scattering mean free path and anisotropy factor g for entire biopsies and demonstrated their direct correlation with tumor presence. We found that these scattering parameters are able to distinguish between two adjacent grades, which is a difficult task and relevant for determining patient treatment. In essence, our results show that the tissue refractive index reports on the nanoscale tissue architecture and, in principle, can be used as an intrinsic marker for cancer diagnosis. [4pt] [1] Z. Wang, K. Tangella, A. Balla and G. Popescu, Tissue refractive index as marker of disease, Journal of Biomedical Optics, in press).[0pt] [2] Z. Wang, L. J. Millet, M. Mir, H. Ding, S. Unarunotai, J. A. Rogers, M. U. Gillette and G. Popescu, Spatial light interference microscopy (SLIM), Optics Express, 19, 1016 (2011).[0pt] [3] Z. Wang, D. L. Marks, P. S. Carney, L. J. Millet, M. U. Gillette, A. Mihi, P. V. Braun, Z. Shen, S. G. Prasanth and G. Popescu, Spatial light interference tomography (SLIT), Optics Express, 19, 19907-19918 (2011).[0pt] [4] Z. Wang, H. Ding and G. Popescu, Scattering-phase theorem, Optics Letters, 36, 1215 (2011).[0pt] [5] G. Popescu Quantitative phase imaging of cells and tissues (McGraw-Hill, New York, 2011).[0pt] [6] H. F. Ding, Z. Wang, F. Nguyen, S. A. Boppart and G. Popescu, Fourier Transform Light Scattering of Inhomogeneous and Dynamic Structures, Physical Review Letters, 101, 238102 (2008).

  1. Calibration of the Reflected Solar Instrument for the Climate Absolute Radiance and Refractivity Observatory

    NASA Technical Reports Server (NTRS)

    Thome, Kurtis; Barnes, Robert; Baize, Rosemary; O'Connell, Joseph; Hair, Jason

    2010-01-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) plans to observe climate change trends over decadal time scales to determine the accuracy of climate projections. The project relies on spaceborne earth observations of SI-traceable variables sensitive to key decadal change parameters. The mission includes a reflected solar instrument retrieving at-sensor reflectance over the 320 to 2300 nm spectral range with 500-m spatial resolution and 100-km swath. Reflectance is obtained from the ratio of measurements of the earth s surface to those while viewing the sun relying on a calibration approach that retrieves reflectance with uncertainties less than 0.3%. The calibration is predicated on heritage hardware, reduction of sensor complexity, adherence to detector-based calibration standards, and an ability to simulate in the laboratory on-orbit sources in both size and brightness to provide the basis of a transfer to orbit of the laboratory calibration including a link to absolute solar irradiance measurements.

  2. Refractive index and birefringence of 2H silicon carbide.

    NASA Technical Reports Server (NTRS)

    Powell, J. A.

    1972-01-01

    Measurement of the refractive indices of 2H SiC over the wavelength range from 435.8 to 650.9 nm by the method of minimum deviation. A curve fit of the experimental data to the Cauchy dispersion equation yielded, for the ordinary index, n sub zero = 2.5513 + 25,850/lambda squared + 8.928 x 10 to the 8th power/lambda to the 4th power and, for the extraordinary index, n sub e = 2.6161 + 28,230/lambda squared + 11.490 x 10 to the 8th power/lambda to the 4th power when lambda is expressed in nm. The estimated error (standard deviation) in these values is plus or minus 0.0006 for n sub zero and plus or minus 0.0009 for n sub e. The birefringence calculated from these expressions is about 20% less than previously published values.

  3. Influences of refractive index on forward light scattering

    NASA Astrophysics Data System (ADS)

    Han, Xueshan; Shen, Jianqi; Yin, Pengteng; Hu, Shiyu; Bi, Duo

    2014-04-01

    The influence of the relative refractive index (RRI) of the particles to the surrounding medium on the small-angle forward scattering signals is studied, based on the Mie theory, the Debye series expansion (DSE) and the Fraunhofer diffraction theory. It comes to the conclusion that, for small particles, the influence on the forward scattering signals is mainly due to the part of the internal reflection if the RRI deviates from 1. However, when the RRI is close to 1, the effects on the forward scattered light from both the surface reflection and the internal reflection are great. For large particles, the contributions of the surface reflection and the internal reflection to the forward scattered light are much weaker than the diffraction when the RRI deviates from 1. When the RRI is very close to 1, the effects on the forward scattered light from the internal reflection are great. To determine the influence of the RRI in detail, the modified Chahine algorithm is employed. The inversion results cannot give the correct PSD for small particles if the RRI used in the inversion procedure does not match the one of the sample. The result shows that it is necessary to determine the exact value of the RRI and one should avoid the RRI close to 1 by choosing dispersion with proper refractive index in practice.

  4. Refractive index of erbium doped GaN thin films

    SciTech Connect

    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.

  5. Refractive indexes of aqueous LiBr solutions

    SciTech Connect

    Zaltash, A.; Ally, M.R. (Energy Div., Oak Ridge National Lab., Oak Ridge, TN (US))

    1992-01-01

    This paper reports that the refractive indexes of water-lithium bromide solutions were measured in the temperature range from 5.0 to 80.0 {degrees}C and in the range of salt concentrations from 0.00 (deionized water) to 58.90 mass %. An electrolyte solution of LlBr in water was chosen for study because of its wide use as an absorption chiller fluid. The concentration of LlBr aqueous solution was determined by argentimetric titration using tetrabromofluoresceln (Eosin) as an adsorption indicator and was checked at a few discrete concentrations (10.06, 20.30, and 58.90 mass % LlBr) against the values obtained by gravimetric analysis. The deviation between values obtained using these two techniques was found to be less than 0.27 mass %. The refractive indexes are shown to represent a reliable and convenient way of measuring the concentration of salt (or water) in LlBr solutions with accuracies of {plus minus}0.3 mass % salt.

  6. Dark Matter Constraints from a Cosmic Index of Refraction

    E-print Network

    S. Gardner; D. C. Latimer

    2010-06-08

    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 |varepsilon|/M < 1 x 10^{-5} eV^{-1} at 95% CL.

  7. Refractive index of erbium doped GaN thin films

    NASA Astrophysics Data System (ADS)

    Alajlouni, S.; Sun, Z. Y.; Li, J.; Zavada, J. M.; Lin, J. Y.; Jiang, H. X.

    2014-08-01

    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.

  8. Dark Matter Constraints from a Cosmic Index of Refraction

    SciTech Connect

    Gardner, Susan; Latimer, David C.

    2009-04-01

    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 |{var_epsilon}|/M < 1.8 x 10{sup -5} eV{sup -1} at 95% CL.

  9. Measurement of complex refractive index of human blood by low-coherence interferometry

    NASA Astrophysics Data System (ADS)

    Jedrzejewska-Szczerska, M.

    2013-10-01

    In this article, the usefulness of the optical technique for measurements of blood complex refractive index has been examined. Measurement of optical properties of human blood is difficult to perform because of its nonuniform nature. However, results of my investigation have shown the usefulness of low-coherence interferometry for measurement complex refractive index of human blood. Furthermore, mathematical analysis of spectrum of measured signal have made possible to determined relationship between complex refractive index and hematocrit level in human blood.

  10. Change in refractive index of muscle tissue during laser-induced interstitial thermotherapy.

    PubMed

    Chen, Na; Chen, Meimei; Liu, Shupeng; Guo, Qiang; Chen, Zhenyi; Wang, Tingyun

    2014-01-01

    This paper presents a long-period fiber-grating (LPG) based Michelson interferometric refractometry to monitor the change in refractive index of porcine muscle during laser-induced interstitial thermotherapy (LITT). As the wavelength of RI interferometer alters with the change in refractive index around the probe, the LPG based refractometry is combined with LITT system to measure the change in refractive index of porcine muscle when irradiated by laser. The experimental results show the denaturation of tissue alters the refractive index significantly and the LPG sensor can be applied to monitor the tissue state during the LITT. PMID:24211967

  11. 3-D photo-patterning of refractive index structures in photosensitive thin film materials

    DOEpatents

    Potter, Jr., Barrett George (Albuquerque, NM); Potter, Kelly Simmons (Albuquerque, NM)

    2002-01-01

    A method of making a three-dimensional refractive index structure in a photosensitive material using photo-patterning. The wavelengths at which a photosensitive material exhibits a change in refractive index upon exposure to optical radiation is first determined and then a portion of the surface of the photosensitive material is optically irradiated at a wavelength at which the photosensitive material exhibits a change in refractive index using a designed illumination system to produce a three-dimensional refractive index structure. The illumination system can be a micro-lenslet array, a macroscopic refractive lens array, or a binary optic phase mask. The method is a single-step, direct-write procedure to produce a designed refractive index structure.

  12. Complex refractive index of Martian dust - Wavelength dependence and composition

    NASA Technical Reports Server (NTRS)

    Pang, K.; Ajello, J. M.

    1977-01-01

    The size distribution and complex refractive index of Martian dust-cloud particles observed in 1971 with the Mariner 9 UV spectrometer are determined by matching the observed single-scattering albedo and phase function with Mie-scattering calculations for size distributions of spheres. Values of phase function times single-scattering albedo are presented for 12 wavelength intervals in the range from 190 to 350 nm, and best-fit values are obtained for the absorption index. It is found that the absorption index of the dust particles increases with decreasing wavelength from 350 to about 210 nm and then drops off shortward of 210 nm, with a structural shoulder occurring in the absorption spectrum between 240 and 250 nm. A search for a candidate material that can explain the strong UV absorption yields TiO2, whose anatase polymorph has an absorption spectrum matching that of the Martian dust. The TiO2 content of the dust particles is estimated to be a few percent or less.

  13. Semiconductor laser devices having lateral refractive index tailoring

    DOEpatents

    Ashby, Carol I. H. (Edgewood, NM); Hadley, G. Ronald (Alburquerque, NM); Hohimer, John P. (Albuquerque, NM); Owyoung, Adelbert (Albuquerque, NM)

    1990-01-01

    A broad-area semiconductor laser diode includes an active lasing region interposed between an upper and a lower cladding layer, the laser diode further comprising structure for controllably varying a lateral refractive index profile of the diode to substantially compensate for an effect of junction heating during operation. In embodiments disclosed the controlling structure comprises resistive heating strips or non-radiative linear junctions disposed parallel to the active region. Another embodiment discloses a multi-layered upper cladding region selectively disordered by implanted or diffused dopant impurities. Still another embodiment discloses an upper cladding layer of variable thickness that is convex in shape and symmetrically disposed about a central axis of the active region. The teaching of the invention is also shown to be applicable to arrays of semiconductor laser diodes.

  14. Spatially varying index of refraction: An open ended undergraduate topic

    SciTech Connect

    Krueger, D.A.

    1980-03-01

    There are many commonplace examples of waves moving along a curved path in an inhomogeneous media. There are reports of a simple lecture demonstration of light bending in a sugar solution being used to motivate students in physics, geophysics, and acoustics courses. For those students who wish to pursue this topic we discuss many avenues of additional research. With relatively simple equipment one can measure the index of refraction n (y,t) and its first and second spatial derivatives as well as the time dependence. The analysis can be approached from a generalization of Snell's law, the equations for the eikonal, Fermat's principle, and the classical approximation and analogies with trajectories of particles.

  15. Refractive Index Profiles of Copper Ion Exchange Glass Planar Waveguides

    NASA Astrophysics Data System (ADS)

    Xia, Hong-Yun; Teng, Chuan-Xin; Zhao, Xiao-Wei; Zheng, Jie

    2012-08-01

    Glass planar optical waveguides are fabricated by the copper ion-exchange technique. The refractive index (RI) profiles of waveguides are reconstructed by the inverse Wentzel-Kramers-Brillouin (IWKB) method. Cu+ and Cu2+ ion concentrations are calculated by solving the diffusion equation, and the mechanism of RI changes is analyzed. The model between the RI and ion concentrations is proposed by taking both Cu+ and Cu2+ into account, according to polarizability changes among Cu+, Cu2+ and Na+. The results show that the contribution of Cu2+ is not negligible, and the reason for the RI change is of Cu+ and Cu2+. With the exchange time increasing, the redox process between Cu+ and Cu2+ will play an important role on RI profiles.

  16. A new phase space method for recovering index of refraction from travel times

    E-print Network

    Uhlmann, Gunther

    A new phase space method for recovering index of refraction from travel times Eric Chung 1 , Jianliang Qian 2 , Gunther Uhlmann 3 , and Hong­Kai Zhao 4 Abstract We develop a new phase space method for reconstructing the index of refraction of a medium from travel time measurements. The method is based on the so

  17. A new phase space method for recovering index of refraction from travel times

    E-print Network

    Soatto, Stefano

    A new phase space method for recovering index of refraction from travel times Eric Chung1 , Jianliang Qian2 , Gunther Uhlmann3 , and Hong-Kai Zhao4 Abstract We develop a new phase space method for reconstructing the index of refraction of a medium from travel time measurements. The method is based on the so

  18. Refractive-index matching between liquid crystals and photopolymers Yi-Hsin Lin

    E-print Network

    Wu, Shin-Tson

    -- Liquid crystals, Norland polymers, refractive index, polymer-dispersed liquid crystals. 1 Introduction Polymer-dispersed liquid crystal (PDLC) and polymer-sta- bilized liquid crystal (PSLC) are useful. In this paper, we compare the refractive index of cured polymers with liquid crystals at different wavelengths

  19. Gradient polymer network liquid crystal with a large refractive index change

    E-print Network

    Wu, Shin-Tson

    Gradient polymer network liquid crystal with a large refractive index change Hongwen Ren,1,* Su Xu gradient polymer network liquid crystal (PNLC) with a large refractive index change is demonstrated, "Cholesteric liquid crystal/polymer dispersion for hazefree light shutters," Appl. Phys. Lett. 60(25), 3102

  20. Volumetric layered transmission-line metamaterial exhibiting a negative refractive index

    E-print Network

    Iyer, Ashwin K.

    Volumetric layered transmission-line metamaterial exhibiting a negative refractive index Ashwin K metamaterials based on two-dimensional (2D) transmission-line layers that exhibit a negative refractive index lens in free space, and suggest an isotropic NRI over bandwidths anywhere from 25% to 45%. Finally

  1. Optical transmittance of a multilayer structure with Gaussian modulation of the refractive index

    NASA Astrophysics Data System (ADS)

    Madrigal-Melchor, J.; Enciso-Muñoz, A.; Contreras-Solorio, D. A.

    2013-06-01

    Using the transfer matrix method we calculate the electromagnetic transmittance for a multilayer dielectric structure, where the refractive index of the layers with odd numbering follows a Gaussian distribution of values, while the inserted even layers have a constant refractive index. The transmission spectrum presents intervals of stopbands and very flat passbands.

  2. Refractive index and density in F- and Cl-doped silica glasses

    SciTech Connect

    Kakiuchida, Hiroshi; Shimodaira, Noriaki; Sekiya, Edson H.; Saito, Kazuya; Ikushima, Akira J. [Research Center for Advanced Photon Technology, Toyota Technological Institute, 2-12-1 Hisakata, Tempaku, Nagoya, Aichi 468-8511 (Japan); Research Center for Advanced Photon Technology, Toyota Technological Institute, 2-12-1 Hisakata, Tempaku, Nagoya, Aichi 468-8511, Japan and Research Center, Asahi Glass Co., Ltd., 1150 Hazawa-cho, Kanagawa, Yokohama, Kanagawa 221-8755 (Japan); Research Center for Advanced Photon Technology, Toyota Technological Institute, 2-12-1 Hisakata, Tempaku, Nagoya, Aichi 468-8511 (Japan)

    2005-04-18

    The refractive index and density of fluorine- and chlorine-doped silica glasses were measured as functions of fictive temperature. The halogen concentrations were observed to have a refractive index or density that is independent of the fictive temperature were found. This implies that these properties are not affected by any heat-treatment conditions.

  3. Dynamics of the refraction index in a water-lecithin mixture

    NASA Astrophysics Data System (ADS)

    Maksimyak, Peter P.

    1997-12-01

    The effect of lecithin concentration on behavior of refractive index of perturbed water-lecithin system is investigated using a polarization interferometer. It is found that the time variations of the refractive index for different lecithin concentrations can be sued to assess the state of the lecithin in water, i.e. detect micelles, single and double molecular layers, etc.

  4. RELATIONSHIP OF FLY ASH COMPOSITION, REFRACTIVE INDEX, AND DENSITY TO IN-STACK OPACITY

    EPA Science Inventory

    The report gives results of an investigation of the refractive index, density, and composition of fly ash from coal-fired boilers, aimed at determining: (1) the interrelationship of refractive index and composition, and (2) the significance of ash properties on in-stack plume opa...

  5. Infrared reflectance measurements of zeolite film thickness, refractive index and other characteristics

    E-print Network

    Nair, Sankar

    Infrared reflectance measurements of zeolite film thickness, refractive index and other-destructive measurement of zeolite membrane characteristics by means of infrared (IR) reflectance measurements in the non with a polynomial expansion for the refractive index function, to interpret reflectance measurements from zeolite

  6. Construction of Lines of Constant Density and Constant Refractive Index for Ternary Liquid Mixtures.

    ERIC Educational Resources Information Center

    Tasic, Aleksandar Z.; Djordjevic, Bojan D.

    1983-01-01

    Demonstrates construction of density constant and refractive index constant lines in triangular coordinate system on basis of systematic experimental determinations of density and refractive index for both homogeneous (single-phase) ternary liquid mixtures (of known composition) and the corresponding binary compositions. Background information,…

  7. A FORTRAN Program for Computing Refractive Index Using the Double Variation Method.

    ERIC Educational Resources Information Center

    Blanchard, Frank N.

    1984-01-01

    Describes a computer program which calculates a best estimate of refractive index and dispersion from a large number of observations using the double variation method of measuring refractive index along with Sellmeier constants of the immersion oils. Program listing with examples will be provided on written request to the author. (Author/JM)

  8. Determination of average refractive index of spin coated DCG films for HOE fabrication

    NASA Technical Reports Server (NTRS)

    Kim, T. J.; Campbell, Eugene W.; Kostuk, Raymond K.

    1993-01-01

    The refractive index of holographic emulsions is an important parameter needed for designing holographic optical elements (HOE's). Theoretical calculations of the accuracy required for the refractive index and thickness of emulsions needed to meet predetermined Bragg angle conditions are presented. A modified interferometric method is used to find average refractive index of the unexposed and the developed dichromated gelatin holographic films. Slanted transmission HOE's are designed considering the index and thickness variations, and used to verify the index measurement results. The Brewster angle method is used to measure surface index of the unexposed and the developed films. The differences between average index and surface index are discussed. Theoretical calculation of the effects of index variation on diffraction efficiency, and experimental results for index modulation variation caused by process changes are also presented.

  9. Forming the refractive-index profile in flat scattering gradient-index elements made from germanate glass

    NASA Astrophysics Data System (ADS)

    Yakhkind, A. K.; Polyakov, A. V.

    2005-11-01

    This paper discusses the results of laboratory studies and commercial melts of multicomponent germanate glass containing sodium oxide. Ion exchange of commercial glass plates in a eutectic mixture of lithium chloride and sulfate was used to obtain flat scattering gradient-index elements with a parabolic refractive-index distribution. The distribution formula is derived. Concepts are formulated concerning the mechanism by which the refractive-index profile is formed.

  10. Spatial variation of stratospheric aerosol acidity and model refractive index - Implications of recent results

    NASA Technical Reports Server (NTRS)

    Russell, P. B.; Hamill, P.

    1984-01-01

    Recent experimental results indicate that little or no solid ammonium sulfate is present in background stratospheric aerosols. Other results allow straightforward calculation of sulfuric acid/water droplet properties (acidity, specific gravity, refractive index) as functions of stratospheric temperature and humidity. These results are combined with a variety of latitudinal and seasonal temperature and humidity profiles to obtain corresponding profiles of droplet properties. These profiles are used to update a previous model of stratospheric aerosol refractive index. The new model retains the simplifying approximation of vertically constant refractive index in the inner stratosphere, but has sulfuric acid/water refractive index values that significantly exceed the previously used room temperature values. Mean conversion ratios (e.g., extinction-to-number, backscatter-to-volume) obtained using Mie scattering calculations with the new refractive indices are very similar to those obtained for the old indices, because the effects of deleting ammonium sulfate and increasing acid indices tend to cancel each other.

  11. Refractive index matching improves optical object detection in paper

    NASA Astrophysics Data System (ADS)

    Saarela, J. M. S.; Heikkinen, S. M.; Fabritius, T. E. J.; Haapala, A. T.; Myllylä, R. A.

    2008-05-01

    The demand for high-quality recycled pulp products has increased the need for an efficient deinking process. Assessing process efficiency via residual ink on test sheets has so far been limited to the sheet surface due to the poor transparency of paper. A refractive index matching method was studied to obtain a quantitative measure of particles within the volume of a paper sheet. In actual measurements a glass plate with etched lines from 8.5 µm to 281.1 µm wide was placed beneath the layers of cleared paper, and visible lines were counted with a microscope. Three different paper grades were tested with transparentizing agents. A diffusion theory-based regression model was used to find a correlation between transparency, paper grammage and paper thickness. These equations enable the determination of the size of an object detectable from a paper with a certain transparentizing agent or the parameters of a test sheet needed to detect objects of a known size. Anise oil was found to be the better of the two agents used, and they both had better transparentizing ability than air or water. The transparent paper grammage of the paper grades was determined for all the tested media. Paper's transparency was found to depend more on paper's thickness than grammage.

  12. Optical polymers with tunable refractive index for nanoimprint technologies.

    PubMed

    Landwehr, J; Fader, R; Rumler, M; Rommel, M; Bauer, A J; Frey, L; Simon, B; Fodor, B; Petrik, P; Schiener, A; Winter, B; Spiecker, E

    2014-12-19

    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. PMID:25427225

  13. Optical polymers with tunable refractive index for nanoimprint technologies

    NASA Astrophysics Data System (ADS)

    Landwehr, J.; Fader, R.; Rumler, M.; Rommel, M.; Bauer, A. J.; Frey, L.; Simon, B.; Fodor, B.; Petrik, P.; Schiener, A.; Winter, B.; Spiecker, E.

    2014-12-01

    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.

  14. Negative refractive index materials for improved solar cells

    NASA Astrophysics Data System (ADS)

    Fahr, Stephan; Rockstuhl, Carsten; Lederer, Falk

    2013-09-01

    Planar thin-film solar cells can exploit Fabry-Perot resonances in the spectral domain of weak absorption to make them more efficient. However, their spectral width decreases and their number increases for a thicker solar cell, both being detrimental. Here, we show that an optically complementary material, i.e., a material with a negative but otherwise identical refractive index to that of the solar cell material and with the same impedance, allows a single, spectrally immensely broad, Fabry-Perot resonance to be obtained. This is useful to enhance the absorption across the entire spectral domain of interest. If a material with the required optical response were available, a solar cell could be implemented that performs close to the Lambertian limit. However, since the idealistic material properties assumed herein cannot be achieved, an actual implementation may exploit nanostructures such as, e.g., dispersion engineered photonic crystals. In a reasonable spectral range their optical response can be close to that required.

  15. Preliminary Error Budget for the Reflected Solar Instrument for the Climate Absolute Radiance and Refractivity Observatory

    NASA Technical Reports Server (NTRS)

    Thome, Kurtis; Gubbels, Timothy; Barnes, Robert

    2011-01-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) plans to observe climate change trends over decadal time scales to determine the accuracy of climate projections. The project relies on spaceborne earth observations of SI-traceable variables sensitive to key decadal change parameters. The mission includes a reflected solar instrument retrieving at-sensor reflectance over the 320 to 2300 nm spectral range with 500-m spatial resolution and 100-km swath. Reflectance is obtained from the ratio of measurements of the earth s surface to those while viewing the sun relying on a calibration approach that retrieves reflectance with uncertainties less than 0.3%. The calibration is predicated on heritage hardware, reduction of sensor complexity, adherence to detector-based calibration standards, and an ability to simulate in the laboratory on-orbit sources in both size and brightness to provide the basis of a transfer to orbit of the laboratory calibration including a link to absolute solar irradiance measurements. The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission addresses the need to observe high-accuracy, long-term climate change trends and to use decadal change observations as the most critical method to determine the accuracy of climate change projections such as those in the IPCC Report. A rigorously known accuracy of both decadal change observations as well as climate projections is critical in order to enable sound policy decisions. The CLARREO Project will implement a spaceborne earth observation mission designed to provide rigorous SI traceable observations (i.e., radiance, reflectance, and refractivity) that are sensitive to a wide range of key decadal change variables, including: 1) Surface temperature and atmospheric temperature profile 2) Atmospheric water vapor profile 3) Far infrared water vapor greenhouse 4) Aerosol properties and anthropogenic aerosol direct radiative forcing 5) Total and spectral solar irradiance 6) Broadband reflected and emitted radiative fluxes 7) Cloud properties 8) Surface albedo There are two methods the CLARREO mission will rely on to achieve these critical decadal change benchmarks: direct and reference inter-calibration. A quantitative analysis of the strengths and weaknesses of the two methods has led to the recommended CLARREO mission approach. The project consists of two satellites launched into 90-degree, precessing orbits separated by 90 degrees. The instrument suite receiver on each spacecraft includes one emitted infrared spectrometer, two reflected solar spectrometers: dividing the spectrum from ultraviolet through near infrared, and one global navigation receiver for radio occultation. The measurements will be acquired for a period of three years minimum, with a five-year lifetime goal, enabling follow-on missions to extend the climate record over the decades needed to understand climate change. The current work concentrates on the reflected solar instrument giving an overview of its design and calibration approach. The calibration description includes the approach to achieving an SI-traceable system on orbit. The calibration overview is followed by a preliminary error budget based on techniques currently in place at the National Institute of Standards and Technology (NIST).

  16. Modification of refractive index in Ag/Na ion-exchanged glasses by vacuum-ultraviolet pulse laser irradiation

    NASA Astrophysics Data System (ADS)

    Ruschin, S.; Sugioka, K.; Yarom, G.; Akane, T.; Midorikawa, K.

    2001-03-01

    Laser-induced refractive index modification in Ag+ ion exchanged waveguides on glass substrates was observed. Waveguiding effects were measured, and an increase in refractive index of more than 2×10-3 was deduced. Refractive index profiles show that the maximum radiation-induced difference is attained 4-5 ?m below the surface. Possible mechanisms for the material modification are discussed.

  17. Determination of refractive index of a simple negative, positive, or zero power lens using wedged plated interferometer

    NASA Technical Reports Server (NTRS)

    Shukla, R. P.; Perera, G. M.; George, M. C.; Venkateswarlu, P.

    1990-01-01

    A nondestructive technique for measuring the refractive index of a negative lens using a wedged plate interferometer is described. The method can be also used for measuring the refractive index of convex or zero power lenses. Schematic diagrams are presented for the use of a wedged plate interferometer for measuring the refractive index of a concave lens and of a convex lens.

  18. Gradient polymer network liquid crystal with a large refractive index change.

    PubMed

    Ren, Hongwen; Xu, Su; Wu, Shin-Tson

    2012-11-19

    A simple approach for preparing gradient polymer network liquid crystal (PNLC) with a large refractive index change is demonstrated. To control the effective refractive index at a given cell position, we applied a voltage to a homogeneous cell containing LC/diacrylate monomer mixture to generate the desired tilt angle and then stabilize the LC orientation with UV-induced polymer network. By varying the applied voltage along with the cells' movement, a PNLC with a gradient refractive index distribution is obtained. In comparison with conventional approaches using patterned photomask or electrode, our method offers following advantages: large refractive index change, freedom to design specific index profile, and large panel capability. Potential applications include tunable-focus lenses, prism gratings, phase modulators, and other adaptive photonic devices. PMID:23187501

  19. Fresnel reflectance in refractive index estimation of light scattering solid particles in immersion liquid

    NASA Astrophysics Data System (ADS)

    Räty, J.; Niskanen, I.; Peiponen, K.-E.

    2010-06-01

    The refractive index of homogenous particle population can be determined by the so-called immersion liquid method. The idea is to find a known liquid whose refractive index matches the index of the particles. We report on a method that simultaneously obtains the refractive index of particles and that of the immersion liquid. It is based on a system using internal light reflection and Fresnel's theory. The method includes a series of straightforward reflection measurements and a fitting procedure. The validity of the method was tested with CaF2 particles. The method has applications within scientific studies of microparticles and nanoparticles or micro-organism in suspensions. It can be also be utilized in industry for the detection of the refractive index of products involving particles for the purpose of improvement of product quality.

  20. Spoof plasmon resonance with 1D periodic grooves for terahertz refractive index sensing

    NASA Astrophysics Data System (ADS)

    Zhang, Yusheng; Hong, Zhi; Han, Zhanghua

    2015-04-01

    We analyze the use of spoof plasmon resonance due to the excitation of spoof surface plasmons in a 1D array of rectangular grooves for terahertz refractive index sensing in an Otto configuration. The dependence of the resonant angle on the change of the refractive index is numerically investigated and a high angular sensitivity about S=320°/RIU is demonstrated, which leads to a high resolution of 3×10-7 RIU assuming 1×10-4 degree for angular resolution. We further show that by using a slanted geometry an even higher sensitivity up to 452°/RIU can be achieved. These results provide a novel method for terahertz refractive index sensing.

  1. Photonic crystal fiber modal interferometer for refractive index sensing of glycerine solution

    NASA Astrophysics Data System (ADS)

    Huang, Jing; Li, Xueming; Yang, Jianchun

    2013-12-01

    A photonic crystal fiber sensor was prepared for refractive index sensing. Based on modal interferometer theory, the relationships between the refractive index of glycerine solution and resonant wavelength shift of the sensor are analyzed by numerical simulation. A fiber optical device was designed to operate the sensing experiment. The sensing experiment shows that the resonant wavelength blued-shift for the sensor with refractive index in the range of 1.33~1.41 happens when increasing glycerine solution from 0.0% to 50.0% (v/v). The experimental results are approximately consistent with theory.

  2. Measurement of thickness and refractive index using femtosecond and terahertz pulses

    NASA Astrophysics Data System (ADS)

    Hussain, Babar; Nawaz, Muhammad; Ahmed, Mushtaq; Raja, M. Yasin Akhtar

    2013-05-01

    We report a simple method to measure the thickness and refractive index of parallel-plane samples simultaneously using femtosecond and terahertz pulses. The time-of-flight measurements of the pulses with and without a sample are exploited to determine the thickness and refractive index of the sample. The accuracy in thickness measurement using femtosecond pulses is 2–3 ?m where refractive index can be measured with an accuracy up to three decimal points. The accuracy and lower limit of thickness measurement using terahertz pulses is also improved.

  3. Index of Refraction Measurements Using a Laser Distance Meter

    ERIC Educational Resources Information Center

    Ochoa, Romulo; Fiorillo, Richard; Ochoa, Cris

    2014-01-01

    We present a simple method to determine the refractive indices of transparent media using a laser distance meter. Indices of refraction have been obtained by measuring the speed of light in materials. Some speed of light techniques use time-of-flight measurements in which pulses are emitted by lasers and the time interval is measured for the pulse…

  4. Correction of image artifacts caused by refractive index gradients in scanning laser optical tomography

    NASA Astrophysics Data System (ADS)

    Antonopoulos, Georgios Christian; Pscheniza, Dimitri; Lorbeer, Raoul-Amadeus; Heidrich, Marko; Schwanke, Kristin; Zweigerdt, Robert; Ripken, Tammo; Meyer, Heiko

    2014-03-01

    We present a technique for correcting image artifacts caused by refractive index distributions in Scanning Laser Optical Tomography (SLOT) and Optical Projection Tomography (OPT). Projection images can be distorted due to the presence of a refractive index distribution around the sample. We consider the special case of a refractive index distribution given by a capillary around a sample. The particular application we are interested in is in vitro imaging of cell spheroids in a glass capillary. Numerical simulations and experimental results are used to illustrate the connection between the Radon transform and the refracted projection. Thereupon we will describe a technique that transforms refracted projections to parallel ray Radon projections and thus allows artifact free reconstruction within the sample volume.

  5. Method of producing optical quality glass having a selected refractive index

    DOEpatents

    Poco, John F. (Livermore, CA); Hrubesh, Lawrence W. (Livermore, CA)

    2000-01-01

    Optical quality glass having a selected refractive index is produced by a two stage drying process. A gel is produced using sol-gel chemistry techniques and first dried by controlled evaporation until the gel volume reaches a pre-selected value. This pre-selected volume determines the density and refractive index of the finally dried gel. The gel is refilled with solvent in a saturated vapor environment, and then dried again by supercritical extraction of the solvent to form a glass. The glass has a refractive index less than the full density of glass, and the range of achievable refractive indices depends on the composition of the glass. Glasses having different refractive indices chosen from an uninterrupted range of values can be produced from a single precursor solution.

  6. Determination of the suitable refractive index of solar cells silicon nitride

    NASA Astrophysics Data System (ADS)

    El Amrani, A.; Bekhtari, A.; El Kechai, A.; Menari, H.; Mahiou, L.; Maoudj, M.; Si-Kaddour, R.

    2014-09-01

    In silicon solar cells studies, the optimal refractive index of plasma- enhanced chemical vapor deposited silicon nitride films is usually determined by an electrical characterization. This technique is done by minority carrier lifetime or surface recombination velocity measurement. We developed in this study a method which encompasses electrical and optical film properties. This method is based on the calculation of the short circuit current densities of multicrystalline silicon solar cells. The optimal refractive index is determined by the maximum short circuit current density. Films with the following refractive indices were studied: 1.9, 2.0, 2.1 and 2.4. The thicknesses are those of an optimal anti-reflection coating (one-quarter wavelength). The optical characterization of these films deposited on multicrystalline silicon wafers and on corning glass gave a minimal weighted reflection for refractive index of 2.0 and a maximum transmission for refractive index of 1.9, respectively. The QSSPC characterization revealed that the film refractive index of 1.9 performed the best passivation quality. Internal quantum efficiencies of simulated multicrystalline silicon solar cells coated with these films were determined by PC1d program simulation. Short-circuit current densities calculated using these experimental and simulated data revealed that the optimal refractive index is 1.9.

  7. Refractive index measurements of double-cylinder structures found in natural spider silks

    NASA Astrophysics Data System (ADS)

    Little, Douglas J.; Kane, Deb M.

    2014-05-01

    The silks of Orb-Weaver spiders (family Araneidae) are emerging as fascinating optical materials due to their biocompatibility, ecological sustainability and mechanical robustness. Natural spider silks are mainly spun as double cylinders, with diameters ranging from 0.05 to 10 ?m, depending on the species and maturity of the spider. This small size makes the silks difficult to characterize optically with traditional techniques. Here, we present a technique that is capable of measuring both the real and imaginary refractive index components of spider silks. This technique is also a new capability for characterizing micro-optics more generally. It is based on the measurement and analysis of refracted light through the spider silk, or micro-optic, while it is immersed in a liquid of known refractive index. It can be applied at any visible wavelength. Results at 540 nm are reported. Real refractive indices in the range of 1.54-1.58 were measured, consistent with previous studies of spider silks. Large silk-to-silk variability of the p-polarized refractive index was observed of around 0.015, while variability in the s-polarized refractive index was negligible. No discernible difference in the refractive indices of the two cylinders making up the double cylinder silk structure were observed. Measured imaginary refractive indices corresponded to an optical loss of around 14 dB/mm at 540 nm.

  8. One-dimensional photonic crystals with a sawtooth refractive index: another exactly solvable potential

    NASA Astrophysics Data System (ADS)

    Morozov, G. V.; Sprung, D. W. L.; Martorell, J.

    2013-10-01

    Exact analytical results expressed in terms of Bessel functions for the bandgaps, reflectance and transmittance of one-dimensional photonic crystals with a sawtooth refractive index profile on the period are derived, to our knowledge for the first time. This extends the set of exactly solvable models with periodic refractive indices. Asymptotic approximations to the above exact results have been also obtained.

  9. Measuring the refractive index of thin transparent films using an extended cavity diode laser

    NASA Astrophysics Data System (ADS)

    Luetjen, Christopher; Hallsted, Jonathan; Kleinert, Michaela

    2013-12-01

    We report on a novel method for determining refractive indices of thin layers of liquids or gases, based on the use of extended cavity diode lasers. Measurements for air, water, and vegetable oil show excellent agreement with accepted values. Applications in determining the refractive index of thin optical coatings and biological cells are discussed.

  10. Liquid Crystal Clad Metamaterial with a Tunable Negative-Zero-Positive Index of Refraction

    E-print Network

    Shalaev, Vladimir M.

    strips separated by a thin layer of alumina form a magnetic resonator, which can provide a less dielectric material. The refractive indices used in the simulations for silica, alumina, and glass are given the permittivity function for the silver. Fig. 2 shows the effective index of refraction n = n +in plotted

  11. Measurement of Refractive Index Gradients by Deflection of a Laser Beam

    ERIC Educational Resources Information Center

    Barnard, A. J.; Ahlborn, B.

    1975-01-01

    In this simple experiment for an undergraduate laboratory a laser beam is passed through the mixing zone of two liquids with different refractive indices. The spatial variation of the refractive index, at different times during the mixing, can be determined from the observed deflection of the beam. (Author)

  12. Sensitive Real-Time Monitoring of Refractive Indexes Using a Novel Graphene-Based Optical Sensor

    PubMed Central

    Xing, Fei; Liu, Zhi-Bo; Deng, Zhi-Chao; Kong, Xiang-Tian; Yan, Xiao-Qing; Chen, Xu-Dong; Ye, Qing; Zhang, Chun-Ping; Chen, Yong-Sheng; Tian, Jian-Guo

    2012-01-01

    Based on the polarization-sensitive absorption of graphene under conditions of total internal reflection, a novel optical sensor combining graphene and a microfluidic structure was constructed to achieve the sensitive real-time monitoring of refractive indexes. The atomic thickness and strong broadband absorption of graphene cause it to exhibit very different reflectivity for transverse electric and transverse magnetic modes in the context of a total internal reflection structure, which is sensitive to the media in contact with the graphene. A graphene refractive index sensor can quickly and sensitively monitor changes in the local refractive index with a fast response time and broad dynamic range. These results indicate that graphene, used in a simple and efficient total internal reflection structure and combined with microfluidic techniques, is an ideal material for fabricating refractive index sensors and biosensor devices, which are in high demand. PMID:23205270

  13. Needle-based refractive index measurement using low-coherence interferometry

    E-print Network

    Boppart, Stephen

    , Urbana, Illinois 61801, USA Steven G. Adie, Julian J. Armstrong, Matthew S. Leigh, Alexandre Paduch tissues.1­3 Techniques using modified OCT systems have been developed to image the refractive index (RI

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

    PubMed Central

    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

  15. Surface antireflection properties of GaN nanostructures with various effective refractive index profiles.

    PubMed

    Han, Lu; Zhao, Hongping

    2014-12-29

    GaN nanostructures with various effective refractive index profiles (Linear, Cubic, and Quintic functions) were numerically studied as broadband omnidirectional antireflection structures for concentrator photovoltaics by using three-dimensional finite difference time domain (3D-FDTD) method. Effective medium theory was used to design the surface structures corresponding to different refractive index profiles. Surface antireflection properties were calculated and analyzed for incident light with wavelength, polarization and angle dependences. The surface antireflection properties of GaN nanostructures based on six-sided pyramid with both uniform and non-uniform patterns were also investigated. Results indicate a significant dependence of the surface antireflection on the refractive index profiles of surface nanostructures as well as their pattern uniformity. The GaN nanostructures with linear refractive index profile show the best performance to be used as broadband omnidirectional antireflection structures. PMID:25607159

  16. Nanofluidic Refractive-Index Sensors Formed by Nanocavity Resonators in Metals without Plasmons

    PubMed Central

    Tsai, Shih-Pin; Ma, Yao-Feng; Sung, Ming-Je; Huang, Ding-Wei

    2011-01-01

    Nanocavity resonators in metals acting as nanofluidic refractive-index sensors were analyzed theoretically. With the illumination of transverse electric polarized light, the proposed refractive index sensor structure acts as a pure electromagnetic resonator without the excitation of surface plasmons. The reflected signal from the nanocavity resonators can be very sensitive to the refractive index of the fluids inside the nanocavities due to the enhancement of the electric field of the resonant mode inside the cavities. Such a sensor configuration can be a useful tool for probing the refractive index change of the fluid inside the nanocavities using the spectral, angular or intensity interrogation schemes. The wavelength sensitivity of 430 nm/RIU, angular sensitivity of 200–1,000 deg/RIU and intensity sensitivity of 25.5 RIU?1 can be achieved in the proposed sensor configuration. PMID:22163776

  17. Refractive index maps and membrane dynamics of human red blood cells parasitized

    E-print Network

    Suresh, Subra

    Refractive index maps and membrane dynamics of human red blood cells parasitized by Plasmodium, Northwestern University, Evanston, IL, July 25, 2008 (received for review May 18, 2008) Parasitization development, the malaria parasite Plasmodium falciparum causes structural, biochemical, and mechanical changes

  18. Complex refractive index of ammonium nitrate in the 2-20-?m spectral range

    NASA Astrophysics Data System (ADS)

    Jarzembski, Maurice A.; Norman, Mark L.; Fuller, Kirk A.; Srivastava, Vandana; Cutten, Dean R.

    2003-02-01

    Using high-resolution Fourier-transform infrared absorbance and transmittance spectral data for ammonium sulfate (AMS), calcium carbonate (CAC), and ammonium nitrate (AMN), we made comparisons with previously published complex refractive-index data for AMS and CAC to infer experimental parameters to determine the imaginary refractive index for AMN in the infrared wavelength range from 2 to 20 ?m. Subtractive Kramers-Kronig mathematical relations were applied to calculate the real refractive index for the three compositions. Excellent agreement for AMS and CAC with the published values was found, validating the complex refractive index obtained for AMN. We performed backscatter calculations using a log-normal size distribution for AMS, AMN, and CAC aerosols to show differences in their backscattered spectra.

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

    E-print Network

    Ottino, Julio M.

    Targeted alteration of real and imaginary refractive index of biological cells by histological of epithe- lial cells caused by histological stains such as hematox- ylin and eosin-containing cytostain. We

  20. Optical fiber sensor system for remote refractive index measurement based on Fresnel reflection using an OTDR

    NASA Astrophysics Data System (ADS)

    Yuan, Jianying; Zhao, Chun-Liu; Ye, Manping; Zhang, Zaixuan; Jin, Shangzhong

    2013-12-01

    In this work, we present an optical fiber sensor system for remote refractive index measurement using the optical time domain reflectometry technique as an interrogation method, and investigate the refractive index sensibility of the sensor system in detail. The sensor system operates based on Fresnel reflection at the fiber's end that is cleaved as a vertical planar surface. Surrounding refractive index from a long distance away can be measured easily through utilizing this sensor system. The experimental setup is simple and easy to handle. Experimental results show the feasibility of the remote measurement of refractive index. The range of this measurement can reach ~30km, moreover, to ensure its repeatability and accuracy, we retest the same sample for many times, some of which are artificially applied with disturbance. Lastly we make a comparative analysis to certify that the sensor system has a good potential to remote practical applications.

  1. Photoacoustic measurement of refractive index of dye solutions and myoglobin for biosensing applications

    PubMed Central

    Goldschmidt, Benjamin S.; Mehta, Smit; Mosley, Jeff; Walter, Chris; Whiteside, Paul J. D.; Hunt, Heather K.; Viator, John A.

    2013-01-01

    Current methods of determining the refractive index of chemicals and materials, such as ellipsometry and reflectometry, are limited by their inability to analyze highly absorbing or highly transparent materials, as well as the required prior knowledge of the sample thickness and estimated refractive index. Here, we present a method of determining the refractive index of solutions using the photoacoustic effect. We show that a photoacoustic refractometer can analyze highly absorbing dye samples to within 0.006 refractive index units of a handheld optical refractometer. Further, we use myoglobin, an early non-invasive biomarker for malignant hyperthermia, as a proof of concept that this technique is applicable for use as a medical diagnostic. Comparison of the speed, cost, simplicity, and accuracy of the techniques shows that this photoacoustic method is well-suited for optically complex systems. PMID:24298407

  2. Refractive index of r-cut sapphire under shock pressure range 5 to 65?GPa

    SciTech Connect

    Cao, Xiuxia; Li, Jiabo; Li, Jun; Li, Xuhai; Xu, Liang; Wang, Yuan; Zhu, Wenjun; Meng, Chuanmin, E-mail: mcm901570@126.com [Laboratory for Shock Wave and Detonation Physics, Institute of Fluid Physics, Mianyang, Sichuan 621900 (China); Zhou, Xianming, E-mail: xzhou0816@163.com [The Peac Institute of Multiscale Sciences, Chengdu, Sichuan 610207 (China)

    2014-09-07

    High-pressure refractive index of optical window materials not only can provide information on electronic polarizability and band-gap structure, but also is important for velocity correction in particle-velocity measurement with laser interferometers. In this work, the refractive index of r-cut sapphire window at 1550?nm wavelength was measured under shock pressures of 5–65?GPa. The refractive index (n) decreases linearly with increasing shock density (?) for shock stress above the Hugoniot elastic limit (HEL): n?=?2.0485 (± 0.0197)???0.0729 (± 0.0043)?, while n remains nearly a constant for elastic shocks. This behavior is attributed to the transition from elastic (below HEL) to heterogeneous plastic deformation (above HEL). Based on the obtained refractive index-density relationship, polarizability of the shocked sapphire was also obtained.

  3. Simultaneous measurements of radar reflectivity and refractive index spectra in clear air convection.

    NASA Technical Reports Server (NTRS)

    Konrad, T. G.; Robison, F. L.

    1972-01-01

    Simultaneous measurements of radar reflectivity and radio refractive index at several altitudes in clear air convection have been made. The experimental data were compared with the theoretical relationship which relates the reflectivity to the refractivity spectrum. The agreement between the measurements and the theory is excellent and shows that the radar returns in clear air are the result of, and can be quantitatively described as being from, fine-scale refractivity fluctuations due to turbulent mixing. Further, the data give strong support to the -5/3 spectral decay of the refractivity spectrum in the inertial subrange.

  4. Negative refractive index metamaterials supporting 2-D waves

    Microsoft Academic Search

    Ashwin K. Iyer; George V. Eleftheriades

    2002-01-01

    Recent demonstrations of negative refraction utilize three-dimensional collections of discrete periodic scatterers to synthesize artificial dielectrics with simultaneously negative permittivity and permeability. In this paper, it is shown that planar, two-dimensional L-C transmission line networks in a high pass configuration can demonstrate negative refraction as a consequence of the fact that such media support propagating backward waves. Simulations illustrating negative

  5. Spin angular momentum transfer from TEM00 focused Gaussian beams to negative refractive index spherical particles

    PubMed Central

    Ambrosio, Leonardo A.; Hernández-Figueroa, Hugo E.

    2011-01-01

    We investigate optical torques over absorbent negative refractive index spherical scatterers under the influence of linear and circularly polarized TEM00 focused Gaussian beams, in the framework of the generalized Lorenz-Mie theory with the integral localized approximation. The fundamental differences between optical torques due to spin angular momentum transfer in positive and negative refractive index optical trapping are outlined, revealing the effect of the Mie scattering coefficients in one of the most fundamental properties in optical trapping systems. PMID:21833372

  6. Simple and precise measurement of the complex refractive index and thickness for thin films

    NASA Astrophysics Data System (ADS)

    Peng, Yu; Li, Wei

    2014-07-01

    We demonstrate applications of a novel scheme which is used for measuring refractive index and thickness of thin film by analyzing the relative phase difference and reflected ratio at reflection point of a monolithic folded Fabry-Perot cavity (MFC). The complex refractive index and the thickness are calculated according to the Fresnel formula. Results show that the proposed method has an improvement in accuracy with simple and clear operating process compared with the conventional Ellipsometry.

  7. Photoinduced absorption and refractive-index induction in phosphosilicate fibres by radiation at 193 nm

    Microsoft Academic Search

    A A Rybaltovsky; V O Sokolov; V G Plotnichenko; Aleksei V Lanin; S L Semenov; A N Guryanov; V F Khopin; Evgenii M Dianov

    2007-01-01

    The photoinduced room-temperature-stable increase in the refractive index by ?5×10-4 at a wavelength of 1.55 ?m was observed in phosphosilicate fibres without their preliminary loading with molecular hydrogen. It is shown that irradiation of preliminary hydrogen-loaded fibres by an ArF laser at 193 nm enhances the efficiency of refractive-index induction by an order of magnitude. The induced-absorption spectra of preforms

  8. Photoinduced absorption and refractive-index induction in phosphosilicate fibres by radiation at 193 nm

    Microsoft Academic Search

    A A Rybaltovsky; V O Sokolov; V G Plotnichenko; Aleksei V Lanin; S L Semenov; Evgenii M Dianov; A N Guryanov; V F Khopin

    2007-01-01

    The photoinduced room-temperature-stable increase in the refractive index by 5x10 at a wavelength of 1.55 m was observed in phosphosilicate fibres without their preliminary loading with molecular hydrogen. It is shown that irradiation of preliminary hydrogen-loaded fibres by an ArF laser at 193 nm enhances the efficiency of refractive-index induction by an order of magnitude. The induced-absorption spectra of preforms

  9. Experimental verification of backward-wave radiation from a negative refractive index metamaterial

    Microsoft Academic Search

    Anthony Grbic; George V. Eleftheriades

    2002-01-01

    A composite medium consisting of an array of fine wires and split-ring resonators has been previously used to experimentally verify a negative index of refraction. We present a negative refractive index (NRI) metamaterial that goes beyond the original split-ring resonator\\/wire medium and is capable of supporting a backward cone of radiation. We report experimental results at microwave frequencies that demonstrate

  10. Optimization of 3D plasmonic crystal structures for refractive index sensing

    Microsoft Academic Search

    Joana Maria; Tu T. Truong; Jimin Yao; Tae-Woo Lee; Ralph G. Nuzzo; Sven Leyffer; Stephen K. Gray; John A. Rogers

    2009-01-01

    We study the refractive index sensitive transmission of a 3D plasmonic crystal that consists of a square array of subwavelength cylindrical nanowells in a polymer conformally coated with a gold film. Using extensive 3D finite-difference time-domain simulations, we investigate the effect of system parameters such as periodicity, well diameter and depth, and metal thickness on its refractive index sensitivity. These

  11. Beat frequencies in a ring laser gyro with its refractive index over unity

    Microsoft Academic Search

    Takahiro Numai

    2001-01-01

    A frequency shift Deltaf during rotation in a ring laser gyro with its refractive index of unity was already well known. However, when the refractive index nr is over unity, several expressions for a beat frequency such as 2Deltaf~nr, nr0, nr-1, and nr-2 were proposed. In this article, a beat frequency in a uniformly rotating ring laser gyro with nr>1

  12. Planar optical waveguides for optical panel having gradient refractive index core

    DOEpatents

    Veligdan, James T.

    2004-08-24

    An optical panel is disclosed. A plurality of stacked planar optical waveguides are used to guide light from an inlet face to an outlet face of an optical panel. Each of the optical waveguides comprises a planar sheet of core material having a central plane. The core material has an index of refraction which decreases as the distance from the central plane increases. The decrease in the index of refraction occurs gradually and continuously.

  13. Enhanced refractive index without absorption in optical fibers via an indirect incoherent pump field

    NASA Astrophysics Data System (ADS)

    Ge, Qiang

    2014-12-01

    We demonstrate a scheme for realizing the refractive index with zero absorption in an Er3+-doped ZrF4-BaF2-LaF3-AlF3-NaF optical fiber. It is found that the refraction index of the probe laser can be easily controlled via adjusting properly the parameters of the corresponding system. Our scheme may provide some new possibilities for technological applications in optical-fiber communication.

  14. Planar optical waveguides for optical panel having gradient refractive index core

    DOEpatents

    Veligdan, James T. (6 Stephanie La., Manorville, NY 11949)

    2001-01-01

    An optical panel is disclosed. A plurality of stacked planar optical waveguides are used to guide light from an inlet face to an outlet face of an optical panel. Each of the optical waveguides comprises a planar sheet of core material having a central plane. The core material has an index of refraction which decreases as the distance from the central plane increases. The decrease in the index of refraction occurs gradually and continuously.

  15. Refractive index of silicon and germanium and its wavelength and temperature derivatives

    Microsoft Academic Search

    H. H. Li

    1980-01-01

    Refractive index data for silicon and germanium were searched, compiled, and analyzed. Recommended values of refractive index for the transparent spectral region were generated in the ranges 1.2 to 14 ?m and 100–740 K for silicon, and 1.9 to 16 ?m and 100–550 K for germanium. Generation of these values was based on a dispersion equation which best fits selected

  16. Quantification of nanoscale nuclear refractive index changes during the cell cycle

    NASA Astrophysics Data System (ADS)

    Bista, Rajan K.; Uttam, Shikhar; Wang, Pin; Staton, Kevin; Choi, Serah; Bakkenist, Christopher J.; Hartman, Douglas J.; Brand, Randall E.; Liu, Yang

    2011-07-01

    Intrigued by our recent finding that the nuclear refractive index is significantly increased in malignant cells and histologically normal cells in clinical histology specimens derived from cancer patients, we sought to identify potential biological mechanisms underlying the observed phenomena. The cell cycle is an ordered series of events that describes the intervals of cell growth, DNA replication, and mitosis that precede cell division. Since abnormal cell cycles and increased proliferation are characteristic of many human cancer cells, we hypothesized that the observed increase in nuclear refractive index could be related to an abundance or accumulation of cells derived from cancer patients at a specific point or phase(s) of the cell cycle. Here we show that changes in nuclear refractive index of fixed cells are seen as synchronized populations of cells that proceed through the cell cycle, and that increased nuclear refractive index is strongly correlated with increased DNA content. We therefore propose that an abundance of cells undergoing DNA replication and mitosis may explain the increase in nuclear refractive index observed in both malignant and histologically normal cells from cancer patients. Our findings suggest that nuclear refractive index may be a novel physical parameter for early cancer detection and risk stratification.

  17. Refractive index and absorption detector for liquid chromatography based on Fabry-Perot interferometry

    DOEpatents

    Yeung, Edward S. (Ames, IA); Woodruff, Steven D. (Ames, IA)

    1984-06-19

    A refractive index and absorption detector for liquid chromatography. It is based in part on a Fabry-Perot interferometer and is used for the improved detection of refractive index and absorption. It includes a Fabry-Perot interferometer having a normally fixed first partially reflecting mirror and a movable second partially reflecting mirror. A chromatographic flow-cell is positioned between the mirrors along the optical axis of a monochromatic laser beam passing through the interferometer. A means for deriving information about the interference fringes coming out of the interferometer is used with a mini-computer to compute the refractive index of the specimen injected into the flow cell. The minicomputer continuously scans the interferometer for continuous refractive index readings and outputs the continuous results of the scans on a chart recorder. The absorption of the specimen can concurrently be scanned by including a second optical path for an excitation laser which will not interfere with the first laser, but will affect the specimen so that absorption properties can be detected. By first scanning for the refractive index of the specimen, and then immediately adding the excitation laser and subsequently scanning for the refractive index again, the absorption of the specimen can be computed and recorded.

  18. Cryogenic Temperature-dependent Refractive Index Measurements of N-BK7, BaLKN3, and SF15 for NOTES PDI

    NASA Technical Reports Server (NTRS)

    Frey, Bradley J.; Leviton, Douglas F.; Madison, Timothy J.

    2007-01-01

    In order to enable high quality lens designs using N-BK7, BaLKN3, and SF15 at cryogenic temperatures, we have measured the absolute refractive index of prisms of these three materials using the Cryogenic, High-Accuracy Refraction Measuring System (CHARMS) at NASA's Goddard Space Flight Center, as a function of both wavelength and temperature. For N-BK7, we report absolute refractive index and thermo-optic coefficient (dn/dT) at temperatures ranging from 50 to 300 K at wavelengths from 0.45 to 2.7 micrometers; for BaLKN3 we cover temperatures ranging from 40 to 300 K and wavelengths from 0.4 to 2.6 micrometers; for SF15 we cover temperatures ranging from 50 to 300 K and wavelengths from 0.45 to 2.6 micrometers. We compare our measurements with others in the literature and provide temperature-dependent Sellmeier coefficients based on our data to allow accurate interpolation of index to other wavelengths and temperatures. While we generally find good agreement (plus or minus 2 x 10(exp -4) for N-BK7, less than 1 x 10(exp -4) for the other materials) at room temperature between our measured values and those provided by the vendor, there is some variation between the datasheets provided with the prisms we measured and the catalog values published by the vendor. This underlines the importance of measuring the absolute refractive index of the material when precise knowledge of the refractive index is required.

  19. Experimental determination of refractive index of condensed reflectin in squid iridocytes.

    PubMed

    Ghoshal, Amitabh; DeMartini, Daniel G; Eck, Elizabeth; Morse, Daniel E

    2014-06-01

    Loliginid squid dynamically tune the structural iridescence of cells in their skin for active camouflage and communication. Bragg reflectors in these cells consist of membrane-bound lamellae periodically alternating with low refractive index extracellular spaces; neuronal signalling induces condensation of the reflectin proteins that fill the lamellae, consequently triggering the expulsion of water. This causes an increase in refractive index within the lamellae, activating reflectance, with the change in lamellar thickness and spacing progressively shifting the wavelength of reflected light. We used micro-spectrophotometry to measure the functionally relevant refractive index of the high-index lamellae of the Bragg reflectors containing the condensed reflectins in chemically fixed dermal iridocytes of the squid, Doryteuthis opalescens. Our high-magnification imaging spectrometer allowed us to obtain normalized spectra of optically distinct sections of the individual, subcellular, multi-layer Bragg stacks. Replacement of the extracellular fluid with liquids of increasing refractive index allowed us to measure the reflectivity of the Bragg stacks as it decreased progressively to 0 when the refractive index of the extracellular medium exactly matched that of the reflectin-filled lamellae, thus allowing us to directly measure the refractive index of the reflectin-filled lamellae as ncondensed lamellae ? 1.44. The measured value of the physiologically relevant ncondensed lamellae from these bright iridocytes falls within the range of values that we recently determined by an independent optical method and is significantly lower than values previously reported for dehydrated and air-dried reflectin films. We propose that this directly measured value for the refractive index of the squid's Bragg lamellae containing the condensed reflectins is most appropriate for calculations of reflectivity in similar reflectin-based high-index layers in other molluscs. PMID:24694894

  20. Refraction of nonlinear beams by localized refractive index changes in nematic liquid crystals

    SciTech Connect

    Assanto, Gaetano [Department of Electronic Engineering, NooEL-Nonlinear Optics and OptoElectronics Lab, University of Rome 'Roma Tre', Via della Vasca Navale 84, 00146 Rome (Italy); Minzoni, Antonmaria A. [Department of Mathematics and Mechanics, Fenomenos Nonlineales y Mecanica (FENOMEC), Instituto de Investigacion en Matematicas Aplicadas y Sistemas, Universidad Nacional Autonoma de Mexico, 01000 Mexico D.F. (Mexico); Smyth, Noel F. [School of Mathematics and Maxwell Institute for Mathematical Sciences, University of Edinburgh, Edinburgh EH9 3JZ, Scotland (United Kingdom); Worthy, Annette L. [School of Mathematics and Applied Statistics, University of Wollongong, Northfields Avenue, Wollongong, New South Wales 2522 (Australia)

    2010-11-15

    The propagation of solitary waves in nematic liquid crystals in the presence of localized nonuniformities is studied. These nonuniformities can be caused by external electric fields, other light beams, or any other mechanism which results in a modified director orientation in a localized region of the liquid-crystal cell. The net effect is that the solitary wave undergoes refraction and trajectory bending. A general modulation theory for this refraction is developed, and particular cases of circular, elliptical, and rectangular perturbations are considered. The results are found to be in excellent agreement with numerical solutions.

  1. A novel type of proximity focusing RICH counter with multiple refractive index aerogel radiator

    E-print Network

    Iijima, T; Adachi, I; Fratina, S; Fukushima, T; Gorisek, A; Kawai, H; Konishi, M; Kozakai, Y; Krizan, P; Matsumoto, T; Mazuka, Y; Nishida, S; Ogawa, S; Ohtake, S; Pestotnik, R; Saitoh, S; Seki, T; Sumiyoshi, T; Uchida, Y; Unno, Y; Yamamoto, S

    2005-01-01

    A proximity focusing ring imaging Cherenkov detector, with the radiator consisting of two or more aerogel layers of different refractive indices, has been tested in 1-4 GeV/c pion beams at KEK. Essentially, a multiple refractive index aerogel radiator allows for an increase in Cherenkov photon yield on account of the increase in overall radiator thickness, while avoiding the simultaneous degradation in single photon angular resolution associated with the increased uncertainty of the emission point. With the refractive index of consecutive layers suitably increasing in the downstream direction, one may achieve overlapping of the Cherenkov rings from a single charged particle. In the opposite case of decreasing refractive index, one may obtain well separated rings. In the former combination an approximately 40% increase in photon yield is accompanied with just a minor degradation in single photon angular resolution. The impact of this improvement on the pion/kaon separation at the upgraded Belle detector is dis...

  2. A single-element interferometer for measuring refractive index of transparent liquids

    NASA Astrophysics Data System (ADS)

    Zhang, Tao; Feng, Guoying; Song, Zheyi; Zhou, Shouhuan

    2014-12-01

    A simple and stable method based on a single-element interferometer for accurately measuring refractive index of transparent liquids was demonstrated. The refractive index is measured by rotating a rectangular optical glass cell which contains sample liquid and air simultaneously, and by calculating interference fringe shift number which is detected from an interferogram. This method was successfully used to measure the refractive indices of various transparent liquids including distilled water, ethanol and NaCl-water and ethanol-water solutions at various concentrations. The temperature- dependent refractive index of distilled water was also measured. Furthermore, our method is simple to implement, vibration insensitive, and of high accuracy up to 10-4.

  3. [The arctic sea ice refractive index retrieval based on satellite AMSR-E observations].

    PubMed

    Chen, Han-Yue; Bi, Hai-Bo; Niu, Zheng

    2012-11-01

    The refractive index of sea ice in the polar region is an important geophysical parameter. It is needed as a vital input for some numerical climate models and is helpful to classifying sea ice types. In the present study, according to Hong Approximation (HA), we retrieved the arctic sea ice refractive index at 6.9, 10.7, 23, 37, and 89 GHz in different arctic climatological conditions. The refractive indices of wintertime first year (FY) sea ice and summertime ice were derived with average values of 1.78 - 1.75 and 1.724 - 1.70 at different frequencies respectively, which are consistent with previous studies. However, for multiyear (MY) ice, the results indicated relatively large bias between modeled results since 10.7 GHz. At a higher frequency, there is larger MY ice refractive index difference. This bias is mainly attributed to the volume scattering effect on MY microwave radiation due to emergence of massive small empty cavities after the brine water in MY ice is discharged into sea. In addition, the retrieved sea ice refractive indices can be utilized to classify ice types (for example, the winter derivation at 89 GHz), to identify coastal polynyas (winter retrieval at 6.9 GHz), and to outline the areal extent of significantly melting marginal sea ice zone (MIZ) (summer result at 6.9 GHz). The investigation of this study suggests an effective tool of passive microwave remote sensing in monitoring sea ice refractive index variability. PMID:23387184

  4. Analysis of the response of long period fiber gratings to external index of refraction

    Microsoft Academic Search

    Heather J. Patrick; Alan D. Kersey; Frank Bucholtz

    1998-01-01

    This paper demonstrates that the change in wavelength of a long period fiber grating attenuation band with changes in external index of refraction can be enhanced by proper selection of the grating period. We calculate and experimentally verify that the wavelength shift caused by changing the external index from n=1 to n=1.44 of the attenuation band which appears in the

  5. Refractive Index of a Transparent Liquid Measured with a Concave Mirror

    ERIC Educational Resources Information Center

    Joshi, Amitabh; Serna, Juan D.

    2012-01-01

    Measuring the refractive index "n" of a substance or medium is part of every introductory physics course. Various approaches to determine this index have been developed over the years based on the different ways light reflects and transmits in the medium. In this paper, the authors would like to present a simple geometrical derivation of the…

  6. Simultaneous measurement of refractive-index and thickness for optical materials by laser feedback interferometry

    NASA Astrophysics Data System (ADS)

    Xu, Ling; Zhang, Shulian; Tan, Yidong; Sun, Liqun

    2014-08-01

    The refractive index measurement by ordinary interferometers cannot avoid the air disturbances in the optical path. A novel approach is presented in this paper based on the Nd:YAG microchip laser feedback interferometry (MLFI) with 1064 nm wavelength. For eliminating the air flow and electric-heating influence the heterodyne modulation and quasi-common path in the MLFI are used. The simultaneous measurement with high accuracy of the refractive index and thickness is realized. The measurement results for three kinds of materials are presented including N-SF57 glass with high index up to 1.81057. The measurement uncertainty of refractive index is better than 0.00002 and of thickness is better than 0.0006 mm.

  7. Complex Refractive Index of Ammonium Nitrate in the 2-20 micron Spectral Range

    NASA Technical Reports Server (NTRS)

    Jarzembski, Maurice A.; Norman, Mark L.; Fuller, Kirk A.; Srivastava, Vandana; Cutten, Dean R.

    2002-01-01

    Using high resolution Fourier Transform Infrared Spectroscopy (FTIR) absorbance/transmittance spectral data for ammonium sulfate (AMS), calcium carbonate (CAC) and ammonium nitrate (AMN), comparisons were made with previously published complex refractive indices data for AMS and CAC to infer experimental parameters to determine the imaginary refractive index for AMN in the infrared wavelength range from 2 to 20 microns. Kramers-Kronig mathematical relations were applied to calculate the real refractive index for the three compositions. Excellent agreement for AMS and CAC with the published values was found, validating the complex refractive indices obtained for AMN. Backscatter calculations using a lognormal size distribution for AMS, AMN, and CAC aerosols were performed to show differences in their backscattered spectra.

  8. Refractive Index Estimation Using Polarisation and Photometric Stereo

    Microsoft Academic Search

    Gule Saman; Edwin R. Hancock

    \\u000a This paper describes a novel approach to the estimation of refractive indices of surfaces using polarisation information.\\u000a We use a moments estimation method for computing the polarisation image components from intensity images obtained using multiple\\u000a polariser angles. This yields estimates of the mean-intensity, polarisation and phase at each pixel location.The surface normals\\u000a are estimated using the photometric stereo. Using the

  9. Hybrid zirconium sol-gel thin films with high refractive index

    NASA Astrophysics Data System (ADS)

    Gorin, Arnaud; Copperwhite, Robert; Elmaghrum, Salem; Mc Donagh, Colette; Oubaha, Mohamed

    2011-08-01

    We describe the synthesis of optical quality thin film materials with high refractive index, employing zirconium based hybrid sol-gel precursors. As the zirconium propoxide precursor is unstable in the presence of a strong nucleophilic agent such as water, two synthesis routes have been performed employing a chelating agent and an organosilane precursor to avoid the formation of any undesired ZrO2 agglomerates, leading to organo-zirconate complexes and silicato-zirconate copolymers, respectively. The prepared hybrid sol-gel materials were deposited by spin-coating to form a transparent thin film on silicon substrates, and heat treated at 100 °C for the final stabilisation of the layer. The effect of the two synthesis routes on the optical properties of zirconium based hybrid sol-gel material is discussed. It was found that the nature and concentration of the organosilane precursor can significantly affect the structural properties of the deposited films. A correlation was also demonstrated between the concentration of the organosilane precursor and the refractive index of the material. By reducing the concentration of organosilane precursor, high refractive index materials were obtained. Similar behaviour was observed for the materials synthesised via chelating agent. The synthesis employing an organosilane precursor produces films with higher refractive index. A maximum refractive index of 1.746 was measured at 635nm for the deposited thin films.

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

    NASA Astrophysics Data System (ADS)

    Anguiano-Morales, Marcelino; Salas Peimbert, Didia P.; Trujillo-Schiaffino, Gerardo

    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.

  11. Dependence of tissue optical properties on solute-induced changes in refractive index and osmolarity

    NASA Astrophysics Data System (ADS)

    Liu, Hanli; Beauvoit, Bertrand; Kimura, Mika; Chance, Britton

    1996-04-01

    Additions of a solute/carbohydrate in tissue affect the size of tissue cells and the refractive indexes of the extra- and intracellular fluids, and thus the overall tissue scattering properties. We use both the Rayleigh-Gans and Mie theory approximation in calculating effects of the osmolarity and refractive indexes on the reduced scattering coefficient of tissue, and employ photon diffusion theory to associate the reduced scattering coefficient to the mean optical path length. The calculations show that changes of scattering in tissue depend not only on the change in extracellular refractive index but also on the change in osmolarity, and thus on the change in cell size and volume fraction. Experimentally, we have utilized time-domain and frequency- domain NIR techniques to measure the changes of optical properties caused by an addition of a solute in tissue models and in perfused rat livers. The temperature-dependent path length measurement of the perfused liver confirms the dependence of tissue scattering on the tissue cell size. The results obtained from the liver with three kinds of carbohydrate perfusion display different scattering aspects and can be well explained by changes in cell size and in extracellular as well as intracellular refractive indexes. The consistency between the theoretical and experimental results confirms the dependence of optical properties in (liver) tissue on both tissue osmolarity and relative refractive indexes between the extracellular and intracellular compartments. This study suggests that the NIR technique is a novel and useful tool for noninvasive, physiological monitoring.

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

    NASA Astrophysics Data System (ADS)

    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.

  13. Measurement and characteristic analysis of refractive index of biological medium adsorption on two-dimensional photonic crystal surface

    NASA Astrophysics Data System (ADS)

    Tong, Kai; Lu, Jianru; Zhang, Zhenguo; Wang, Hui-bo; Chen, Ying

    2014-07-01

    The two-dimensional (2D) SiO2 photonic crystal (PC) is constructed with the substrate of polyester film. The PC period is 800nm, and the duty cycle is 0.5.The high refractive index coating is deposited on the surface of PC. Rigorous coupled-wave (RCWA) theory is used to analyze 2D PC narrowband reflection spectrum characteristic. A relationship model between reflection peak wavelength and medium refractive index adsorption on surface of 2D PC is established. The conclusion shows that there is a linear relationship between reflection wavelength of the PC and the refractive index of adsorption medium, with the refractive index of adsorption medium in the range of 1.3-1.8. The effects of the refractive index of deposited coating on the sensitivity of the PC biosensor are analyzed. With the increase of the refractive index of the deposited coating, the sensitivity of the sensor is increasing.

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

    SciTech Connect

    H. Okuda; B. Stratton; L. Meixler; P. Efthimion; D.Mansfield

    2003-07-24

    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.

  15. Discrete transfer method applied to radiative transfer in a variable refractive index semitransparent medium

    NASA Astrophysics Data System (ADS)

    Krishna, N. Ananda; Mishra, Subhash C.

    2006-12-01

    Application of the discrete transfer method (DTM) has been extended to the analysis of radiative heat transfer in a variable refractive index participating medium. To validate the DTM formulation, radiative heat transfer in an absorbing, emitting and isotropically scattering planar medium was considered. The participating medium was assumed to be in radiative equilibrium. For both constant and variable refractive indices of the medium, the DTM results were compared with those available in the literature. The DTM was found to provide accurate results.

  16. Retrieving the Vertical Structure of the Effective Aerosol Complex Index of Refraction from a Combination of Aerosol in Situ and Remote Sensing Measurements During TARFOX

    NASA Technical Reports Server (NTRS)

    Redemann, J.; Turco, R. P.; Liou, K. N.; Russell, P. B.; Bergstrom, R. W.; Schmid, B.; Livingston, J. M.; Hobbs, P. V.; Hartley, W. S.; Ismail, S.; Ferrare, R. A.; Browell, E. V.

    2000-01-01

    The largest uncertainty in estimates of the effects of atmospheric aerosols on climate stems from uncertainties in the determination of their microphysical properties, including the aerosol complex index of refraction, which in turn determines their optical properties. A novel technique is used to estimate the aerosol complex index of refraction in distinct vertical layers from a combination of aerosol in situ size distribution and remote sensing measurements during the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX). In particular, aerosol backscatter measurements using the NASA Langley LASE (Lidar Atmospheric Sensing Experiment) instrument and in situ aerosol size distribution data are utilized to derive vertical profiles of the "effective" aerosol complex index of refraction at 815 nm (i.e., the refractive index that would provide the same backscatter signal in a forward calculation on the basis of the measured in situ particle size distributions for homogeneous, spherical aerosols). A sensitivity study shows that this method yields small errors in the retrieved aerosol refractive indices, provided the errors in the lidar-derived aerosol backscatter are less than 30% and random in nature. Absolute errors in the estimated aerosol refractive indices are generally less than 0.04 for the real part and can be as much as 0.042 for the imaginary part in the case of a 30% error in the lidar-derived aerosol backscatter. The measurements of aerosol optical depth from the NASA Ames Airborne Tracking Sunphotometer (AATS-6) are successfully incorporated into the new technique and help constrain the retrieved aerosol refractive indices. An application of the technique to two TARFOX case studies yields the occurrence of vertical layers of distinct aerosol refractive indices. Values of the estimated complex aerosol refractive index range from 1.33 to 1.45 for the real part and 0.001 to 0.008 for the imaginary part. The methodology devised in this study provides, for the first time, a complete set of vertically resolved aerosol size distribution and refractive index data. yielding the vertical distribution of aerosol optical properties required for the determination of aerosol-induced radiative flux changes.

  17. Retrieving the Vertical Structure of the Effective Aerosol Complex Index of Refraction from a Combination of Aerosol in Situ and Remote Sensing Measurements During TARFOX

    NASA Technical Reports Server (NTRS)

    Redemann, J.; Turco, R. P.; Liou, K. N.; Russell, P. B.; Bergstrom, R. W.; Schmid, B.; Livingston, J. M.; Hobbs, P. V.; Hartley, W. S.; Ismail, S.

    2000-01-01

    The largest uncertainty in estimates of the effects of atmospheric aerosols on climate stems from uncertainties in the determination of their microphysical properties, including the aerosol complex index of refraction, which in turn determines their optical properties. A novel technique is used to estimate the aerosol complex index of refraction in distinct vertical layers from a combination of aerosol in situ size distribution and remote sensing measurements during the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX). In particular, aerosol backscatter measurements using the NASA Langley LASE (Lidar Atmospheric Sensing Experiment) instrument and in situ aerosol size distribution data are utilized to derive vertical profiles of the 'effective' aerosol complex index of refraction at 815 nm (i.e., the refractive index that would provide the same backscatter signal in a forward calculation on the basis of the measured in situ particle size distributions for homogeneous, spherical aerosols). A sensitivity study shows that this method yields small errors in the retrieved aerosol refractive indices, provided the errors in the lidar derived aerosol backscatter are less than 30% and random in nature. Absolute errors in the estimated aerosol refractive indices are generally less than 0.04 for the real part and can be as much as 0.042 for the imaginary part in the case of a 30% error in the lidar-derived aerosol backscatter. The measurements of aerosol optical depth from the NASA Ames Airborne Tracking Sunphotometer (AATS-6) are successfully incorporated into the new technique and help constrain the retrieved aerosol refractive indices. An application of the technique to two TARFOX case studies yields the occurrence of vertical layers of distinct aerosol refractive indices. Values of the estimated complex aerosol refractive index range from 1.33 to 1.45 for the real part and 0.001 to 0.008 for the imaginary part. The methodology devised in this study provides, for the first time a complete set of vertically resolved aerosol size distribution and refractive index data, yielding the vertical distribution of aerosol optical properties required for the determination of aersol-induced radiative flux changes

  18. Nonlinear refractive index of some anthraquinone dyes in 1294-1b liquid crystal

    NASA Astrophysics Data System (ADS)

    Milanchian, K.; Abdi, E.; Tajalli, H.; Ahmadi K., S.; Zakerhamidi, M. S.

    2012-03-01

    Third order nonlinear refractive index of three anthraquinone dyes, i.e., Solvent Blue 59, Solvent Blue 35 and Solvent Green 3 doped in 1294-1b nematic liquid crystal (NLC) were studied by the single beam Z-scan technique using a continuous-wave He-Ne laser at 632.8 nm. The negative nonlinear refractive index (n 2) in the order of 10 - 5 cm 2/w for all samples was obtained. We believe that, this large nonlinearity is owing to Janossy effect and the difference in the nonlinear refractive index of our dyes can be described by the structures of dyes and the interactions between dyes and 1294-1b molecules. So as to understand the effect of dye structure on nonlinearity enhancement, the dichroic ratio of these dyes in 1294-1b was measured using polarized spectroscopy.

  19. Cavity-enhanced measurements for determining dielectric-membrane thickness and complex index of refraction.

    PubMed

    Stambaugh, Corey; Durand, Mathieu; Kemiktarak, Utku; Lawall, John

    2014-08-01

    The material properties of silicon nitride (SiN) play an important role in the performance of SiN membranes used in optomechanical applications. An optimum design of a subwavelength high-contrast grating requires accurate knowledge of the membrane thickness and index of refraction, and its performance is ultimately limited by material absorption. Here we describe a cavity-enhanced method to measure the thickness and complex index of refraction of dielectric membranes with small, but nonzero, absorption coefficients. By determining Brewster's angle and an angle at which reflection is minimized by means of destructive interference, both the real part of the index of refraction and the sample thickness can be measured. A comparison of the losses in the empty cavity and the cavity containing the dielectric sample provides a measurement of the absorption. PMID:25090324

  20. Waveguide characteristics of single-mode microstructural fibres with a complicated refractive index distribution profile

    SciTech Connect

    Belov, A V; Dianov, Evgenii M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

    2002-07-31

    The method of equivalent step profile of the refractive index is used to calculate the main waveguide characteristics of single-mode microstructural fibres (MFs). A new structure is proposed for such fibres with a W-shaped profile of the refractive index distribution. The dispersion characteristics of such fibres were calculated by solving the scalar wave equation. It is shown that the chromatic dispersion zero may shift to the blue ({lambda}{sub 0} {approx} 0.8 {mu}m) in such structures while the single-mode propagation regime is preserved. A number of MF structures with a complicated distribution of the refractive index profile are proposed and the possibility of assembling such structures in circular quartz tubes is discussed. (laser applications and other topics in quantum electronics)

  1. Correction of refraction index based on adjacent pulse repetition interval lengths

    NASA Astrophysics Data System (ADS)

    Wei, Dong; Aketagawa, Masato

    2014-11-01

    Correction of refraction index is important for length measurement. The two-color method has been widely used for correction. The wavelengths of lasers have been used as a ruler of that. Based on the analogy between the wavelength and the adjacent pulse repetition interval length (APRIL), in this paper we investigate the possibility of two-color method based on adjacent pulse repetition interval lengths. Since the wavelength-based two-color method can eliminate the inhomogeneous disturbance of effects caused by the phase refractive index, therefore the APRIL-based two-color method can eliminate the air turbulence of errors induced by the group refractive index. Our analysis will contribute to high-precision length measurement.

  2. Photoinduced absorption and refractive-index induction in phosphosilicate fibres by radiation at 193 nm

    SciTech Connect

    Rybaltovsky, A A; Sokolov, V O; Plotnichenko, V G; Lanin, Aleksei V; Semenov, S L; Dianov, Evgenii M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation); Gur'yanov, A N; Khopin, V F [Institute of Chemistry of High-Purity Substances, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation)

    2007-04-30

    The photoinduced room-temperature-stable increase in the refractive index by {approx}5x10{sup -4} at a wavelength of 1.55 {mu}m was observed in phosphosilicate fibres without their preliminary loading with molecular hydrogen. It is shown that irradiation of preliminary hydrogen-loaded fibres by an ArF laser at 193 nm enhances the efficiency of refractive-index induction by an order of magnitude. The induced-absorption spectra of preforms with a phosphosilicate glass core and optical fibres fabricated from them are studied in a broad spectral range from 150 to 5000 nm. The intense induced-absorption band ({approx}800 cm{sup -1}) at 180 nm is found, which strongly affects the formation of the induced refractive index. The quantum-chemical model of a defect related to this band is proposed. (optical fibres)

  3. Optical extinction, refractive index, and multiple scattering for suspensions of interacting colloidal particles

    E-print Network

    Alberto Parola; Roberto Piazza; Vittorio Degiorgio

    2014-07-21

    We provide a general microscopic theory of the scattering cross-section and of the refractive index for a system of interacting colloidal particles, exact at second order in the molecular polarizabilities. In particular: a) we show that the structural features of the suspension are encoded into the forward scattered field by multiple scattering effects, whose contribution is essential for the so-called "optical theorem" to hold in the presence of interactions; b) we investigate the role of radiation reaction on light extinction; c) we discuss our results in the framework of effective medium theories, presenting a general result for the effective refractive index valid, whatever the structural properties of the suspension, in the limit of particles much larger than the wavelength; d) by discussing strongly-interacting suspensions, we unravel subtle anomalous dispersion effects for the suspension refractive index.

  4. Sensitivity enhancement of fiber-optic refractive index sensor based on multimode interference with gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Taue, Shuji; Daitoh, Hiroyuki; Fukano, Hideki

    2015-04-01

    In this study, we investigated combinations of fiber-based multimode interference (MMI) sensors with gold nanoparticles (NPs). Gold NPs were synthesized and attached to the MMI sensor region using a silane-coupling agent. Light absorption due to the NPs was confirmed at wavelengths of 560 nm and longer, including the telecommunication band (1300–1600 nm). We examined the variation in the interfered wavelengths with changes in the medium surrounding the MMI sensor, both with and without NPs. The interfered wavelengths were redshifted when the refractive index (RI) increased, and the shift with NPs was almost twice as large as the shift without NPs. We determined the sensitivity of the MMI sensor with NPs to be approximately 218.28 nm/RIU (refractive index unit) in a refractive index range from 1.31535 to 1.35199.

  5. Interferometric spectroscopy of scattered light can quantify the statistics of subdiffractional refractive-index fluctuations

    PubMed Central

    Cherkezyan, L.; Capoglu, I.; Subramanian, H.; Rogers, J. D.; Damania, D.; Taflove, A.

    2014-01-01

    Despite major importance in physics, biology, and other sciences, optical sensing of nanoscale structures in the far-zone remains an open problem due to the fundamental diffraction limit of resolution. We establish that the expected value of spectral variance (??2) of a far-field, diffraction-limited microscope image can quantify the refractive-index fluctuations of a label-free, weakly scattering sample at subdiffraction length scales. We report the general expression of ?? for an arbitrary refractive-index distribution. For an exponential refractive-index spatial correlation, we obtain a closed-form solution of ?? which is in excellent agreement with three-dimensional finite-difference time-domain solutions of Maxwell's equations. Sensing complex inhomogeneous media at the nanoscale can benefit fields from material science to medical diagnostics. PMID:23909326

  6. Lattice and electronic contributions to the refractive index of CuWO4

    NASA Astrophysics Data System (ADS)

    Ruiz-Fuertes, J.; Pellicer-Porres, J.; Segura, A.; Rodríguez-Hernández, P.; Muñoz, A.

    2014-09-01

    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 ?(?) = 4.5(1) for light polarization parallel to the c-axis and ?(?) = 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, 7 eV, 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.

  7. Hybrid optical fiber Fabry-Perot interferometer for simultaneous measurement of gas refractive index and temperature.

    PubMed

    Wang, Ruohui; Qiao, Xueguang

    2014-11-10

    We present a hybrid miniature optical fiber Fabry-Perot interferometer for simultaneous measurement of gas refractive index and temperature. The interferometer is fabricated by cascading two short sections of capillary tubes with different inner diameters. One extrinsic interferometer is based on the air gap cavity formed by the capillary tube with large diameter. Another section of capillary tube with small inner diameter performs as an intrinsic interferometer and also provides a channel enabling gas to enter and leave the extrinsic cavity freely. The experiment shows that the different dips or peaks in fringe exhibit different responses to the changes in gas refractive index and temperature. Owing to this feature, simultaneous measurement of the gas refractive index and temperature can be realized. PMID:25402996

  8. Influence of refractive index and molecular weight of alcohol agents on skin optical clearing effect

    NASA Astrophysics Data System (ADS)

    Mao, Zhongzhen; Zheng, Ying; Hu, Yating; Lu, Wei; Luo, Qingming; Zhu, Dan

    2007-02-01

    In order to discuss the relative factors affecting the optical clearing effect of agents on skin tissues, six hydroxy-terminated and saturated alcohols with different refractive index and molecular weight were chosen as the optical clearing agents (OCAs). After being treated by different OCAs, the change of transmitted intensity of porcine skins in vitro was measured by single integrating sphere system. The results showed the optical clearing effects of six OCAs, i.e., glycerol, PEG400, PEG200, 1,3-propylene glycol, 1,4-butanediol and 1-butanol, arranged in the descending order. Based on the above results, the refractive index and molecular weight was further discussed. The optical clearing effect of alcohols has been deduced to have negative correlation with refractive index (r=-0.608), but no correlation with molecular weight (r= 0.008).

  9. Index of refraction, Rayleigh scattering length, and Sellmeier coefficients in solid and liquid argon and xenon

    E-print Network

    Grace, Emily

    2015-01-01

    Like all the noble elements, argon and xenon are scintillators, \\emph{i.e.} they produce light when exposed to radiation. Large liquid argon detectors have become widely used in low background experiments, including dark matter and neutrino research. However, the index of refraction of liquid argon at the scintillation wavelength has not been measured and current Rayleigh scattering length calculations disagree with measurements. Furthermore, the Rayleigh scattering length and index of refraction of solid argon and solid xenon at their scintillation wavelengths have not been previously measured or calculated. We introduce a new calculation using previously measured data in liquid and solid argon and xenon to extrapolate the optical properties at the scintillation wavelengths using the Sellmeier dispersion relationship. As a point of validation, we compare our extrapolated index of refraction for liquid xenon against the measured value and find agreement within the uncertainties. This method results in a Rayle...

  10. Refractive index measurement of the mouse crystalline lens using optical coherence tomography.

    PubMed

    Chakraborty, Ranjay; Lacy, Kip D; Tan, Christopher C; Park, Han Na; Pardue, Machelle T

    2014-08-01

    In recent years, there has been a growing interest for using mouse models in refractive development and myopia research. The crystalline lens is a critical optical component of the mouse eye that occupies greater than 50% of the ocular space, and significant increases in thickness with age. However, changes in refractive index of the mouse crystalline lens are less known. In this study, we examined the changes in thickness and refractive index of the mouse crystalline lens for two different strains, wild-type (WT) and a nyx mutant (nob) over the course of normal visual development or after form deprivation. Refractive index and lens thickness measurements were made on ex vivo lenses using spectral domain optical coherence tomography (SD-OCT). Comparison of refractive index measurements on 5 standard ball lenses using the SD-OCT and their known refractive indices (manufacturer provided) indicated good precision (intra-class correlation coefficient, 0.998 and Bland-Altman coefficient of repeatability, 0.116) of the SD-OCT to calculate mouse lens refractive index ex vivo. During normal visual development, lens thickness increased significantly with age for three different cohorts of mice, aged 4 (average thickness from both eyes; WT: 1.78 ± 0.03, nob: 1.79 ± 0.08 mm), 10 (WT: 2.02 ± 0.05, nob: 2.01 ± 0.04 mm) and 16 weeks (WT: 2.12 ± 0.06, nob: 2.09 ± 0.06 mm, p < 0.001). Lens thickness was not significantly different between the two strains at any age (p = 0.557). For mice with normal vision, refractive index for isolated crystalline lenses in nob mice was significantly greater than WT mice (mean for all ages; WT: 1.42 ± 0.01, nob: 1.44 ± 0.001, p < 0.001). After 4 weeks of form deprivation to the right eye using a skull-mounted goggling apparatus, a thinning of the crystalline lens was observed in both right and left eyes of goggled animals compared to their naïve controls (average from both the right and the left eye) for both strains (p = 0.052). In form deprived mice, lens refractive index was significantly different between the goggled animals and non-goggled naïve controls in nob mice, but not in WT mice (p = 0.009). Both eyes of goggled nob mice had significantly greater lens refractive index (goggled, 1.49 ± 0.01; opposite, 1.47 ± 0.03) compared to their naïve controls (1.45 ± 0.02, p < 0.05). The results presented here suggest that there are genetic differences in the crystalline lens refractive index of the mouse eye, and that the lens refractive index in mice significantly increase with form deprivation. Research applications requiring precise optical measurements of the mouse eye should take these lens refractive indices into account when interpreting SD-OCT data. PMID:24939747

  11. Two-dimensional refractive index and stresses profiles of a homogenous bent optical fiber.

    PubMed

    Ramadan, W A; Wahba, H H; Shams El-Din, M A

    2014-11-01

    We present a significant contribution to the theory of determining the refractive index profile of a bent homogenous optical fiber. In this theory we consider two different processes controlling the index profile variations. The first is the linear index variation due to stress along the bent radius, and the second is the release of this stress on the fiber surface. This release process is considered to have radial dependence on the fiber radius. These considerations enable us to construct the index profile in two dimensions normal to the optical axis, considering the refraction of light rays traversing the fiber. This theory is applied to optical homogenous bent fiber with two bending radii when they are located orthogonal to the light path of the object arm in the holographic setup (like the Mach-Zehnder interferometer). Digital holographic phase shifting interferometry is employed in this study. The recorded phase shifted holograms have been combined, reconstructed, and processed to extract the phase map of the bent optical fiber. A comparison between the extracted optical phase differences and the calculated one indicates that the refractive index profile variation should include the above mentioned two processes, which are considered as a response for stress distribution across the fiber's cross section. The experimentally obtained refractive index profiles provide the stress induced birefringence profile. Thus we are able to present a realistic induced stress profile due to bending. PMID:25402912

  12. Crystalline sulfur dioxide: Crystal field splittings, absolute band intensities and complex refractive indices derived from infrared spectra

    NASA Technical Reports Server (NTRS)

    Khanna, R. K.; Zhao, Guizhi

    1986-01-01

    The infrared absorption spectra of thin crystalline films of sulfur dioxide at 90 K are reported in the 2700 to 450/cm region. The observed multiplicity of the spectral features in the regions of fundamentals is attributed to factor group splittings of the modes in a biaxial crystal lattice and the naturally present minor S-34, S-36, and O-18 isotopic species. Complex refractive indices determined by an iterative Kramers-Kronig analysis of the extinction data, and absolute band strengths derived from them, are also reported in this region.

  13. Lateral shearing interferometer for measuring photoinduced refractive index change in As(2)S(3).

    PubMed

    Krishnaswami, Kannan; Bernacki, Bruce E; Hô, Nicolas; Allen, Paul J; Anheier, Norman C

    2008-09-01

    We have built and demonstrated a lateral shearing interferometer as a process engineering and control tool for the fabrication and characterization of direct-laser-written waveguide structures in chalcogenide glasses. Photoinduced change in refractive index of 0.154+/-0.002 was measured for as-deposited amorphous As(2)S(3) thin films at 633 nm with an estimated measurement uncertainty of 1.3% for this air-gap interferometer configuration. The simple design of this interferometer can easily be adapted to other wavelengths including mid- and long-wave infrared regions to measure changes in refractive index or material inhomogeneities in transmissive materials. PMID:19044448

  14. Observation of asymmetric solitons in waveguide arrays with refractive index gradient.

    PubMed

    Weimann, Steffen; Kartashov, Yaroslav V; Vysloukh, Victor A; Szameit, Alexander; Torner, Lluis

    2014-06-15

    We study light propagation in waveguide arrays made in Kerr nonlinear media with a transverse refractive index gradient, and we find that the presence of the refractive index gradient leads to the appearance of a number of new soliton families. The effective coupling between the solitons and the localized linear eigenmodes of the lattice induces a drastic asymmetry in the soliton shapes and the appearance of long tails at the soliton wings. Such unusual solitons are found to be completely stable under propagation, and we report their experimental observation in fs-laser written waveguide arrays with focusing Kerr nonlinearity. PMID:24978570

  15. Inverse Abbe-method for observing small refractive index changes in liquids.

    PubMed

    Räty, Jukka; Peiponen, Kai-Erik

    2015-05-01

    This study concerns an optical method for the detection of minuscule refractive index changes in the liquid phase. The proposed method reverses the operation of the traditional Abbe refractometer and thus utilizes the light dispersion properties of materials, i.e. it involves the dependence of the refractive index on light wavelength. In practice, the method includes the detection of light reflection spectra in the visible spectral range. This inverse Abbe method is suitable for liquid quality studies e.g. for monitoring water purity. Tests have shown that the method reveals less than per mil NaCl or ethanol concentrations in water. PMID:25770617

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

    E-print Network

    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.

  17. Broadband and low loss high refractive index metamaterials in the microwave regime

    NASA Astrophysics Data System (ADS)

    Campbell, T.; Hibbins, A. P.; Sambles, J. R.; Hooper, I. R.

    2013-03-01

    A broadband, low-loss, isotropic, high refractive index metamaterial comprising an array of close-packed cubic elements of cross-linked square metal plates is demonstrated in the microwave regime. The structuring of the cubic elements reduces the diamagnetic response exhibited by arrays of solid metal cubes, whilst maintaining the strongly enhanced permittivity arising from capacitative coupling between adjacent metal elements. The corresponding increase in refractive index can be tailored through appropriate structuring of the faces and/or spacing of the cubes.

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Broadband focusing and collimation of water waves by zero refractive index

    PubMed Central

    Zhang, Chi; Chan, C. T.; Hu, Xinhua

    2014-01-01

    It is always a challenge to realize extreme and unusual values of refractive index for a broad range of frequencies. We show that when water is covered by a thick, rigid and unmovable plate, it behaves like a medium with zero refractive index for water waves at any frequency. Hence, by covering water with a plate of a concave or rectangular shape, water waves can be focused or collimated in a broad range of frequencies. Experiments were conducted to demonstrate these effects and results are in excellent agreement with numerical simulations. PMID:25381845

  20. Density and refractive index of binary CH4, N2 and CO2 ice mixtures

    NASA Astrophysics Data System (ADS)

    Luna, R.; Satorre, M. Á.; Domingo, M.; Millán, C.; Santonja, C.

    2012-09-01

    In this work we present the results of a series of laboratory experiments performed to obtain the density and the real part of the refractive index of binary mixtures of ices of astrophysical interest. Densities of CO2:CH4 mixtures obey the expected weighted mean and the other binary mixtures have densities up to 20% lower than expected. Refractive index for all the binary mixtures deviates up to 5% from the theoretical, obtaining higher values than expected for CO2:CH4 and lower values than predicted for CO2:N2 and CH4:N2.

  1. Large photoinduced refractive index changes of a polymer containing photochromic norbornadiene groups

    SciTech Connect

    Kinoshita, K.; Horie, K. [Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113 (Japan)] [Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113 (Japan); Morino, S. [Photofunctional Chemistry Division, Research Laboratory of Resources Utilization, Tokyo Institute of Technology, Nagatsuta-cho 4259, Midori-ku, Yokohama, Kanagawa 226 (Japan)] [Photofunctional Chemistry Division, Research Laboratory of Resources Utilization, Tokyo Institute of Technology, Nagatsuta-cho 4259, Midori-ku, Yokohama, Kanagawa 226 (Japan); Nishikubo, T. [Department of Applied Chemistry, Faculty of Engineering, Kanagawa University, Rokkakubashi, Kanagawa-ku, Yokohama, 221 (Japan)] [Department of Applied Chemistry, Faculty of Engineering, Kanagawa University, Rokkakubashi, Kanagawa-ku, Yokohama, 221 (Japan)

    1997-06-01

    We prepared a polymer containing pendant norbornadiene (NBD) moieties, P(MMA{sub 0.43}-co-GMA{sub 0.57}-PNCA), and measured absorbance and refractive index spectra before and after photoisomerization of norbornadiene moieties. Large photoinduced refractive index changes of {approximately}0.01 were obtained at 632.8 nm, the region far from the absorption band. A quantum yield of 0.50 was obtained for the photoisomerization of NBD moieties in this polymer. These values are sufficient to make efficient channel waveguides by photoisomerization. {copyright} {ital 1997 American Institute of Physics.}

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

    NASA Astrophysics Data System (ADS)

    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.

  3. Broadband focusing and collimation of water waves by zero refractive index

    NASA Astrophysics Data System (ADS)

    Zhang, Chi; Chan, C. T.; Hu, Xinhua

    2014-11-01

    It is always a challenge to realize extreme and unusual values of refractive index for a broad range of frequencies. We show that when water is covered by a thick, rigid and unmovable plate, it behaves like a medium with zero refractive index for water waves at any frequency. Hence, by covering water with a plate of a concave or rectangular shape, water waves can be focused or collimated in a broad range of frequencies. Experiments were conducted to demonstrate these effects and results are in excellent agreement with numerical simulations.

  4. Retrieval of dust-particle refractive index using the phenomenon of negative polarization

    NASA Astrophysics Data System (ADS)

    Zubko, Evgenij; Videen, Gorden; Shkuratov, Yuriy

    2015-01-01

    We study the phenomenon of negative polarization in irregularly shaped agglomerated debris particles. We find that the location of the negative polarization minimum is unambiguously governed by Re(m). Furthermore, the amplitude of the negative polarization puts a strong constraint on the material absorption in target particles regardless of their real part of refractive index Re(m). The interrelation can be parameterized with a simple formula and it can be utilized in remote sensing. We apply our finding to laboratory optical measurements of Allende meteorite at ?=0.633 ?m and estimate its complex refractive index to be m?(1.68-1.83)+(0.01-0.02)i.

  5. Ray-tracing method for isotropic inhomogeneous refractive-index media from arbitrary discrete input.

    PubMed

    Nishidate, Yohei; Nagata, Takashi; Morita, Shin-ya; Yamagata, Yutaka

    2011-09-10

    We have developed a ray-tracing simulation procedure for optically isotropic gradient refractive-index media. The procedure can take discrete points of arbitrary distribution for the definition of refractive-index distributions and lens surfaces. It is useful for simulating ray trajectories in real lens systems. The procedure is applied to a ray-tracing simulation of the Luneburg lens and a radial gradient optical fiber. The simulation results are compared with the analytical solutions, and it is shown that they are in precise agreement. PMID:21947003

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

    PubMed

    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

  7. Refractive-index profile and physical process determination in thick gratings in electrooptic crystals

    NASA Technical Reports Server (NTRS)

    Su, S. F.; Gaylord, T. K.

    1976-01-01

    A method for determining the refractive index profile of thick phase gratings in linear electrooptic crystals is presented. This method also determines the effective photovoltaic electric field and the relative contributions of diffusion and drift during hologram recording. The method requires only a knowledge of the modulation ratio during hologram recording and the fundamental and the higher-order diffraction efficiencies of the grating. As an illustration of the method, the refractive index profile, the effective photovoltaic field, and the relative contributions of diffusion and drift are determined from experimental measurements for a lithium niobate holographic grating.

  8. Acoustic transmission line metamaterial with negative/zero/positive refractive index

    NASA Astrophysics Data System (ADS)

    Bongard, Frédéric; Lissek, Hervé; Mosig, Juan R.

    2010-09-01

    A one-dimensional acoustic negative refractive index metamaterial based on the transmission line approach is presented. This structure implements the dual transmission line concept extensively investigated in microwave engineering. It consists of an acoustic waveguide periodically loaded with membranes realizing the function of series “capacitances” and transversally connected open channels realizing shunt “inductances.” Transmission line based metamaterials can exhibit a negative refractive index without relying on resonance phenomena, which results in a bandwidth of operation much broader than that observed in resonant devices. In the present case, the negative refractive index band extends over almost one octave, from 0.6 to 1 kHz. The developed structure also exhibits a seamless transition between the negative and positive refractive index bands with a zero index at the transition frequency of 1 kHz. At this frequency, the unit cell is only one tenth of the wavelength. Simple acoustic circuit models are introduced, which allow efficient designs both in terms of dispersion and impedance, while accurately describing all the physical phenomena. Using this approach, a good matching at the structure terminations is achieved. Full-wave simulations, made for a 10-cell-long structure, confirm the good performances in terms of dispersion diagram, Bloch impedance, and reflection and transmission coefficients.

  9. Active metamaterials: sign of refraction index and gain-assisted dispersion management

    E-print Network

    Alexander A. Govyadinov; Mikhail A. Noginov; Viktor A. Podolskiy

    2007-04-27

    We derive an approach to define the causal direction of the wavevector of modes in optical metamaterials, which in turn, determines signs of refractive index and impedance as a function of {\\it real and imaginary} parts of dielectric permittivity and magnetic permeability. We use the developed technique to demonstrate that the interplay between resonant response of constituents of metamaterials can be used to achieve efficient dispersion management. Finally we demonstrate broadband dispersion-less index and impedance matching in active nanowire-based negative index materials. Our work opens new practical applications of negative index composites for broadband lensing, imaging, and pulse-routing.

  10. Influence of the refractive index and dispersion of spectacle lens on its imaging properties

    NASA Astrophysics Data System (ADS)

    Miks, Antonin; Novak, Jiri; Novak, Pavel

    2007-12-01

    The paper shows an influence of the refractive index and dispersion of the spectacle lens on its imaging properties. Relations are presented for calculation of radii of curvature of anastigmatic spectacle lenses and their chromatic aberration. Moreover, the formulas are derived for calculation of the change of astigmatism of spectacle lens due to dispersion of spectacle lens material.

  11. Graded refraction index antireflection coatings based on silicon and titanium oxides

    Microsoft Academic Search

    Abdelhakim Mahdjoub

    2007-01-01

    Thin films with a graded refraction index constituted from silicon and titanium oxides were deposited by plasma enhanced chemical vapor deposition using electron cyclotron resonance. A plasma of oxygen reacted with two precursors: the tetraethoxysilane (TEOS) and the titanium isopropoxide (TIPT). The automatic regulation of the precursor flows makes it possible to modify the chemical composition, and consequently the optical

  12. Measuring the Refractive Index of Highly Crystalline Monolayer MoS2 with High Confidence

    NASA Astrophysics Data System (ADS)

    Zhang, Hui; Ma, Yaoguang; Wan, Yi; Rong, Xin; Xie, Ziang; Wang, Wei; Dai, Lun

    2015-02-01

    Monolayer molybdenum disulphide (MoS2) has attracted much attention, due to its attractive properties, such as two-dimensional properties, direct bandgap, valley-selective circular dichroism, and valley Hall effect. However, some of its fundamental physical parameters, e.g. refractive index, have not been studied in detail because of measurement difficulties. In this work, we have synthesized highly crystalline monolayer MoS2 on SiO2/Si substrates via chemical vapor deposition (CVD) method and devised a method to measure their optical contrast spectra. Using these contrast spectra, we extracted the complex refractive index spectrum of monolayer MoS2 in the wavelength range of 400 nm to 750 nm. We have analyzed the pronounced difference between the obtained complex refractive index spectrum and that of bulk MoS2. The method presented here is effective for two-dimensional materials of small size. Furthermore, we have calculated the color contour plots of the contrast as a function of both SiO2 thickness and incident light wavelength for monolayer MoS2 using the obtained refractive index spectrum. These plots are useful for both fundamental study and device application.

  13. Imaging-eclipsing-Z-scan method for measurement of the nonlinear refractive index of materials

    Microsoft Academic Search

    Mehrdad Mohebi; Nooshin Jamasbi; Omar Morales; Jesus Garduno; Ali A. Said; Eric W. van Stryland

    1999-01-01

    We present a new variation of the Z-scan technique, which provides a sensitive method for measurement of the nonlinear refractive index of materials. The method is based on imaging of a top hat beam onto a blocking disk; therefore, it is very sensitive. In addition to greater sensitivity the method offers the advantage that it does not require a Gaussian

  14. Nonlinear Refractive Index Of CS2 At 10.6 µm

    NASA Astrophysics Data System (ADS)

    Mohebi, M.; Reali, G.; Soileau, M. J.; Van Stryland, E. W.

    1985-11-01

    We have measured the nonlinear refractive index n2 of CS2 at 10.6 ?m using two different techniques. We find that n2 is (2.2 +/- 0.7) x 1010 esu which is over an order of magnitude larger than its value in the visible.

  15. 2-D Isotropic Effective Negative Refractive Index Metamaterial in Planar Technology

    Microsoft Academic Search

    A. Vallecchi; F. Capolino; A. G. Schuchinsky

    2009-01-01

    We present a fully printable effective negative refractive index (NRI) metamaterial responsive to arbitrarily linearly polarized incident waves. The proposed metamaterial is composed of a periodic array of tightly coupled Jerusalem cross conductor pairs printed on the opposite sides of a dielectric substrate. Each pair supports both symmetric and antisymmetric resonance modes, whose superposition can lead to an effective NRI

  16. Manipulating intracellular refractive index for contrast-enhanced digital holographic imaging of subcellular structures

    NASA Astrophysics Data System (ADS)

    Rommel, Christina E.; Dierker, Christian; Schmidt, Lisa; Przibilla, Sabine; von Bally, Gert; Kemper, Björn; Schnekenburger, Jürgen

    2011-02-01

    The online analysis of rapid cellular processes by morphological alterations strongly depends on the ability to rapidly visualize and to quantify cell shape and intracellular structures. Digital holographic microscopy (DHM) enables quantitative phase contrast imaging for high resolution and minimal invasive live cell analysis without the need of labeling or complex sample preparation. However, due to the rather homogenous intracellular refractive index, the phase contrast of subcellular structures is limited and often low. We analyzed the impact of specific intracellular refractive index manipulation by microinjection of refractive index changing agents on the DHM phase contrast. Glycerol was chosen as osmolyte, which combines high solubility in aqueous solutions and cellular compatibility. We present data showing that the intracellular injection of glycerol causes a contrast enhancement that can be explained by a decrease of the cytosolic refractive index due to a water influx. The underlying principle was proven by experiments inducing cell shrinkage and protein concentration. The integrity of cell membranes is considered as a prerequisite and allows a reversible cell swelling and shrinking within a certain limit. The presented approach to control the intracellular phase contrast demonstrated for DHM opens also prospects for application with other quantitative phase contrast imaging technologies.

  17. Effect of optical pumping on the refractive index and temperature in the core of active fibre

    SciTech Connect

    Gainov, V V; Ryabushkin, Oleg A [V.A.Kotel'nikov Institute of Radio Engineering and Electronics, Fryazino Branch, Russian Academy of Sciences, Fryazino, Moscow Region (Russian Federation)

    2011-09-30

    This paper examines the refractive index change (RIC) induced in the core of Yb{sup 3+}-doped active silica fibres by pulsed pumping. RIC kinetic measurements with a Mach - Zehnder interferometer make it possible to separately assess the contributions of the electronic and thermal mechanisms to the RIC and evaluate temperature nonuniformities in the fibre.

  18. Nonlinear refractive index measurement utilizing bistable behavior of double coupling optical fiber ring resonator

    NASA Astrophysics Data System (ADS)

    Yang, Lei; Pan, Wei; Luo, Bin; Yan, Lianshan

    2015-03-01

    A novel approach for measuring the nonlinear refractive index of an optical fiber utlizing the bistable behavior of the double coupling optical fiber ring resonator was proposed and investigated. The switch-off or switch-on power decreases with an increase in the nonlinear refractive index n 2 (m2/W), and the dependence of swith-off or switch-on power on the nonlinear refractive index was analyzed numerically. Simulation results showed that the switch-off power and switch-on power (in dBW) decreased linearly with log10( n 2) in a 100-m-length fiber ring resonator, when n 2 changed from 3.2 × 10-20 m2/W to 2.5 × 10-17 m2/W or nearly n 2 = 3.2 × 10-20 m2/W. These mean that high accuracy as well as large-scale nonlinear refractive index measurement can be achieved by the proposed approach.

  19. Gouy shift correction for highly accurate refractive index retrieval in time-domain

    E-print Network

    Ku?el, Petr

    for the transmission function which accounts for spatially limited Gaussian terahertz beams. We demonstrateGouy shift correction for highly accurate refractive index retrieval in time-domain terahertz Republic, Na Slovance 2, 182 21 Prague 8, Czech Republic *kuzelp@fzu.cz Abstract: Terahertz spectroscopic

  20. Photoinduced refractive index change and absorption bleaching in poly(methylphenylsilane) under varied atmospheres.

    SciTech Connect

    Potter, Barrett George, Jr. (University of Arizona, Tucson, AZ); Simmons-Potter, Kelly (University of Arizona, Tucson, AZ); Chandra, Haripin (University of Arizona, Tucson, AZ); Thomes, William Joseph, Jr.; Jamison, Gregory Marks

    2005-06-01

    Polysilane materials exhibit large photo-induced refractive index changes under low incident optical fluences, making them attractive candidates for applications in which rapid patterning of photonic device structures is desired immediately prior to their use. This agile fabrication strategy for integrated photonics inherently requires that optical exposure, and associated material response, occurs in nonlaboratory environments, motivating the study of environmental conditions on the photoinduced response of the material. The present work examines the impact of atmosphere on the photosensitive response of poly(methylphenylsilane) (PMPS) thin films in terms of both photoinduced absorption change and refractive index modification. Material was subjected to UV light exposure resonant with the lowest energy optical transition associated with the conjugated Si-Si backbone. Exposures were performed in both aerobic and anaerobic atmospheres (oxygen, air, nitrogen, and 5% H{sub 2}/95% N{sub 2}). The results clearly demonstrate that the photosensitive response of this model polysilane material was dramatically affected by local environment, exhibiting a photoinduced refractive index change, when exposed under an oxygen containing atmosphere, that was twice that observed under anaerobic conditions. This effect is discussed in terms of photo-oxidation processes within the polysilane structure and in the context of the need for predictable photosensitive refractive index change in varied photoimprinting environments.

  1. Ultraviolet and visible imaginary refractive index of strongly absorbing atmospheric particulate matter

    NASA Astrophysics Data System (ADS)

    Gillespie, James B.; Lindberg, James D.

    1992-04-01

    Determinations of the imaginary refractive index in the ultraviolet and visible spectral regions as determined from diffuse reflectance measurements are presented. Materials examined are carbon black and oxides of iron, lead, mercury, copper, manganese, and vanadium along with lead iodide and iron sulfide.

  2. High-precision diode-laser-based temperature measurement for air refractive index compensation.

    PubMed

    Hieta, Tuomas; Merimaa, Mikko; Vainio, Markku; Seppä, Jeremias; Lassila, Antti

    2011-11-01

    We present a laser-based system to measure the refractive index of air over a long path length. In optical distance measurements, it is essential to know the refractive index of air with high accuracy. Commonly, the refractive index of air is calculated from the properties of the ambient air using either Ciddor or Edlén equations, where the dominant uncertainty component is in most cases the air temperature. The method developed in this work utilizes direct absorption spectroscopy of oxygen to measure the average temperature of air and of water vapor to measure relative humidity. The method allows measurement of temperature and humidity over the same beam path as in optical distance measurement, providing spatially well-matching data. Indoor and outdoor measurements demonstrate the effectiveness of the method. In particular, we demonstrate an effective compensation of the refractive index of air in an interferometric length measurement at a time-variant and spatially nonhomogeneous temperature over a long time period. Further, we were able to demonstrate 7 mK RMS noise over a 67 m path length using a 120 s sample time. To our knowledge, this is the best temperature precision reported for a spectroscopic temperature measurement. PMID:22086025

  3. Roles of wave impedance and refractive index in photonic crystals with magnetic and dielectric properties

    Microsoft Academic Search

    Chul-Sik Kee; Jae-Eun Kim; Hae Yong Park; H. Lim

    1999-01-01

    We investigated the roles of wave impedance and refractive index in photonic crystals by means of analytical expressions for edges frequencies of a photonic bandgap (PBG) in a one-dimensional photonic crystal with magnetic and dielectric properties. The analytical expressions were derived when the optical thicknesses of layers are the same. The wave impedance governs the formation of PBG's and the

  4. Germanosilicate glass refractive-index change induced by direct excitation of GODC triplet state

    Microsoft Academic Search

    E. M. Dianov; D. S. Starodubov; S. A. Vasiliev; A. A. Frolov; O. I. Medvedkov; A. O. Rybaltovsky

    1997-01-01

    In conclusion the results obtained have shown the possibility of fiber grating fabrication using more commonly used lasers operating in the near-UV region. Besides these results gain insight into the phenomenon of the photo-induced glass refractive-index change

  5. The refractive index of krypton for lambda in the closed interval 168-288 nm

    NASA Technical Reports Server (NTRS)

    Smith, P. L.; Parkinson, W. H.; Huber, M. C. E.

    1975-01-01

    The index of refraction of krypton has been measured at 27 wavelengths between and including 168 and 288 nm. The probable error of each measurement is plus or minus 0.1%. Our results are compared with other measurements. Our data are about 3.8% smaller than those of Abjean et al.

  6. Glasses having a low non-linear refractive index for laser applications

    DOEpatents

    Faulstich, Marga (Mainz, DE); Jahn, Walter (Ingelheim, DE); Krolla, Georg (Mainz, DE); Neuroth, Norbert (Mainz-Mombach, DE)

    1980-01-01

    Glass composition ranges are described which permit the introduction of laser activators into fluorphosphate glass with exceptionally high fluorine content while forming glasses of high crystallization stability and permitting the realization of large melt volumes. The high fluorine content imparts to the glasses an exceptionally low nonlinear refractive index n.sub.2 down to O,4 .times.10.sup.-13 esu.

  7. Ultraviolet complex refractive index of Martian dust Laboratory measurements of terrestrial analogs

    NASA Technical Reports Server (NTRS)

    Egan, W. G.; Hilgeman, T.; Pang, K.

    1975-01-01

    The optical complex index of refraction of four candidate Martian surface materials has been determined between 0.185 and 0.4 microns using a modified Kubelka-Munk scattering theory. The cadidate materials were limonite, andesite, montmorillonite, and basalt. The effect of scattering has been removed from the results. Also presented are diffuse reflection and transmission data on these samples.

  8. A Negative-Refractive-Index Metamaterial for Incident Plane Waves of Arbitrary Polarization

    Microsoft Academic Search

    Loïc Markley; George V. Eleftheriades

    2007-01-01

    In this letter, a left-handed artificial dielectric is proposed. Using resonating broadside coupled patches to generate a negative permeability and thin strips to generate negative permittivity, a negative index of refraction that is matched to free space can be designed. The structure is fabricated from a single dielectric sheet printed on both sides by metal patterns that couple to externally

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Three-dimensional metamaterials with an ultra-high effective refractive index over broad bandwidth

    E-print Network

    Jonghwa Shin; Jung-Tsung Shen; Shanhui Fan

    2008-04-14

    The authors introduce a general mechanism, based on electrostatic and magnetostatic considerations, for designing three-dimensional isotopic metamaterials that possess an enhanced refractive index over an extremely large frequency range. The mechanism allows nearly independent control of effective electric permittivity and magnetic permeability without the use of resonant elements.

  11. Measuring the Refractive Index of Highly Crystalline Monolayer MoS2 with High Confidence

    PubMed Central

    Zhang, Hui; Ma, Yaoguang; Wan, Yi; Rong, Xin; Xie, Ziang; Wang, Wei; Dai, Lun

    2015-01-01

    Monolayer molybdenum disulphide (MoS2) has attracted much attention, due to its attractive properties, such as two-dimensional properties, direct bandgap, valley-selective circular dichroism, and valley Hall effect. However, some of its fundamental physical parameters, e.g. refractive index, have not been studied in detail because of measurement difficulties. In this work, we have synthesized highly crystalline monolayer MoS2 on SiO2/Si substrates via chemical vapor deposition (CVD) method and devised a method to measure their optical contrast spectra. Using these contrast spectra, we extracted the complex refractive index spectrum of monolayer MoS2 in the wavelength range of 400?nm to 750?nm. We have analyzed the pronounced difference between the obtained complex refractive index spectrum and that of bulk MoS2. The method presented here is effective for two-dimensional materials of small size. Furthermore, we have calculated the color contour plots of the contrast as a function of both SiO2 thickness and incident light wavelength for monolayer MoS2 using the obtained refractive index spectrum. These plots are useful for both fundamental study and device application. PMID:25676089

  12. Three-Dimensional Metamaterials with an Ultrahigh Effective Refractive Index over a Broad Bandwidth

    Microsoft Academic Search

    Jonghwa Shin; Jung-Tsung Shen; Shanhui Fan

    2009-01-01

    The authors introduce a general mechanism, based on electrostatic and magnetostatic considerations, for designing three-dimensional isotropic metamaterials that possess an enhanced refractive index over an extremely large frequency range. The mechanism allows nearly independent control of effective electric permittivity and magnetic permeability without the use of resonant elements.

  13. Optical coherence tomography imaging of microfluidic pattern with different refractive index contrast

    NASA Astrophysics Data System (ADS)

    Hu, Zhixiong; Hao, Bingtao; Liu, Wenli; Hong, Baoyu

    2014-11-01

    Optical coherence tomography (OCT) technology is analogous to ultrasound imaging, except that OCT employs light instead of sound. The non-invasive imaging method works by projecting light on test target and detecting the backscattering from the underlying layers. As the OCT technology is based on optical interference, the internal structural features and inhomogeneities induced by different refractive index contrast could be detected and displayed in the form of a gray scale or false color image. In this paper, a typical microfluidic device was produced and measured by a spectral domain OCT instrument. The internal dimensions of the lab-on-chip device were determined using the OCT imaging technology and were in agreement with results obtained with conventional confocal microscope. In order to study the effect of different refractive index contrast on OCT imaging, fluid with various refractive indexes was injected into the microfluidic channel respectively, and the acquired OCT images of the internal microfluidic channel were compared. The results demonstrate that optical coherence tomography could be used as a new metrology tool to determine the internal channel dimensions of lab-on-chip devices. Furthermore, the experiment results reveal the relations between the refractive index contrast and OCT image quality.

  14. Measuring the Refractive Index of Highly Crystalline Monolayer MoS2 with High Confidence.

    PubMed

    Zhang, Hui; Ma, Yaoguang; Wan, Yi; Rong, Xin; Xie, Ziang; Wang, Wei; Dai, Lun

    2015-01-01

    Monolayer molybdenum disulphide (MoS2) has attracted much attention, due to its attractive properties, such as two-dimensional properties, direct bandgap, valley-selective circular dichroism, and valley Hall effect. However, some of its fundamental physical parameters, e.g. refractive index, have not been studied in detail because of measurement difficulties. In this work, we have synthesized highly crystalline monolayer MoS2 on SiO2/Si substrates via chemical vapor deposition (CVD) method and devised a method to measure their optical contrast spectra. Using these contrast spectra, we extracted the complex refractive index spectrum of monolayer MoS2 in the wavelength range of 400?nm to 750?nm. We have analyzed the pronounced difference between the obtained complex refractive index spectrum and that of bulk MoS2. The method presented here is effective for two-dimensional materials of small size. Furthermore, we have calculated the color contour plots of the contrast as a function of both SiO2 thickness and incident light wavelength for monolayer MoS2 using the obtained refractive index spectrum. These plots are useful for both fundamental study and device application. PMID:25676089

  15. Effect of scintillometer height on structure parameter of the refractive index of air measurements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Scintillometers measure amount of scintillations by emitting a beam of light over a horizontal path and expresses as the atmospheric turbulence structure parameter as the refractive index of air (Cn**2). Cn**2 represents the turbulent strength of the atmosphere and describes the ability of the atmos...

  16. Rapid Inversion of Angular Deflection Data for Certain Axisymmetric Refractive Index Distributions

    NASA Technical Reports Server (NTRS)

    Rubinstein, R.; Greenberg, P. S.

    1994-01-01

    Certain functions useful for representing axisymmetric refractive-index distributions are shown to have exact solutions for Abel transformation of the resulting angular deflection data. An advantage of this procedure over direct numerical Abel inversion is that least-squares curve fitting is a smoothing process that reduces the noise sensitivity of the computation

  17. Variable refractive index effects on radiation in semitransparent scattering multilayered regions

    NASA Technical Reports Server (NTRS)

    Siegel, R.; Spuckler, C. M.

    1993-01-01

    A simple set of equations is derived for predicting the temperature distribution and radiative energy flow in a semitransparent layer consisting of an arbitrary number of laminated sublayers that absorb, emit, and scatter radiation. Each sublayer can have a different refractive index and optical thickness. The plane composite region is heated on each exterior side by a different amount of incident radiation. The results are for the limiting case where heat conduction within the layers is very small relative to radiative transfer, and is neglected. The interfaces are assumed diffuse, and all interface reflections are included in the analysis. The thermal behavior is readily calculated from the analytical expressions that are obtained. By using many sublayers, expressions provide the temperature distribution and heat flow for a diffusing medium with a continually varying refractive index, including internal reflection effects caused by refractive index gradients. Temperature and heat flux results are given to show the effect of variations in refractive index and optical thickness through the multilayer laminate.

  18. Cosmology With A Dark Refraction Index B. Chen 1 , and R. Kantowski 1, y

    E-print Network

    Kantowski, Ron

    Cosmology With A Dark Refraction Index B. Chen 1 , #3; and R. Kantowski 1, y 1 Homer L. Dodge Dept and polariza- tion of a geometrical optics wave traveling in a gravity #12;eld. We apply the theory to the FLRW through a spacetime possessing an optical metric. Readers not interested in the mathematical details can

  19. PROGRESS IN PHYSICS Local Doppler effect, index of refraction through the Earth crust,

    E-print Network

    Boyer, Edmond

    PROGRESS IN PHYSICS Local Doppler effect, index of refraction through the Earth crust, PDF to the local Doppler effect between a local clock attached to a given detector at Gran Sasso, say CG, x, y, z) with velocity given by Eq. (1). Since CG crosses CC, the Doppler effect between the proper

  20. Microfabricated refractive index gradient based detector for reversed-phase liquid chromatography with mobile phase gradient elution

    Microsoft Academic Search

    Adam D. McBrady; Robert E. Synovec

    2006-01-01

    Typical refractive index (RI) detectors for liquid chromatography (LC) are not well suited to application with mobile phase gradient elution, due to the difficulty in correcting for the detected baseline shift during the gradient. We report a sensitive, highly reproducible, microfabricated refractive index gradient (micro-RIG) detector that performs well with mobile phase gradient elution LC. Since the micro-RIG signal remains

  1. Lidar determination of altitude profile of the refraction index in electro-optical monitoring of the Earths atmosphere

    E-print Network

    Lidar determination of altitude profile of the refraction index in electro-optical monitoring reserved. Keywords: Electro-optical lidar; Electro-optical Kerr effect; Refraction index; Statistically by the lidar tech- nique has been gaining acceptance in the recent years [16­21]. Aerosole lidar measurements

  2. Relationship of fly ash composition, refractive index, and density to in-stack opacity. Final report, June 1981May 1982

    Microsoft Academic Search

    S. J. Cowen; D. S. Ensor

    1985-01-01

    The report gives results of an investigation of the refractive index, density, and composition of fly ash from coal-fired boilers, aimed at determining: (1) the interrelationship of refractive index and composition, and (2) the significance of ash properties on in-stack plume opacity. A survey was made of 14 ash samples representing a wide range of coals. Light absorption was measured

  3. Refractive index distribution and spherical aberration in the crystalline lens of the African cichlid fish Haplochromis burtoni.

    PubMed

    Kröger, R H; Campbell, M C; Munger, R; Fernald, R D

    1994-07-01

    Refractive index distribution in the teleost crystalline lens was measured with a nondestructive method in freshly excised lenses of the African teleost fish Haplochromis burtoni. Independently, spherical aberration was measured in a parallel set of lenses. The measured refractive index profiles show a continual decrease of refractive index from the center to the surface of the lens. The H. burtoni lens is of high optical quality and slightly overcorrected for spherical aberration. Details of the small residual spherical aberration were accurately predicted by ray-tracing model calculations based on the measured refractive index profile. The refractive index profile and the spherical aberration both show more complex characteristics than suggested by earlier measurements and lens models. PMID:7941384

  4. Optimization of torque on an optically driven micromotor by manipulation of the index of refraction

    NASA Astrophysics Data System (ADS)

    Wing, Frank M., III; Mahajan, Satish; Collett, Walter

    2004-12-01

    Since the 1970"s, the focused laser beam has become a familiar tool to manipulate neutral, dielectric micro-objects. A number of authors, including Higurashi and Gauthier, have described the effects of radiation pressure from laser light on microrotors. Collett, et al. developed a wave, rather than a ray optic, approach in the calculation of such forces on a microrotor for the first time. This paper describes a modification to the design of a laser driven, radiation pressure microrotor, intended to improve the optically generated torque. Employing the wave approach, the electric and magnetic fields in the vicinity of the rotor are calculated using the finite difference time domain (FDTD) method, which takes into account the wave nature of the incident light. Forces are calculated from the application of Maxwell"s stress tensor over the surfaces of the rotor. Results indicate a significant increase in torque when the index of refraction of the microrotor is changed from a single value to an inhomogeneous profile. The optical fiber industry has successfully employed a variation in the index of refraction across the cross section of a fiber for the purpose of increasing the efficiency of light transmission. Therefore, it is hoped that various fabrication methods can be utilized for causing desired changes in the index of refraction of an optically driven microrotor. Various profiles of the index of refraction inside a microrotor are considered for optimization of torque. Simulation methodology and results of torque on a microrotor for various profiles of the index of refraction are presented. Guidelines for improvised fabrication of efficient microrotors may then be obtained from these profiles.

  5. The role of macromolecular crowding in the evolution of lens crystallins with high molecular refractive index

    PubMed Central

    Zhao, Huaying; Magone, M. Teresa; Schuck, Peter

    2011-01-01

    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 ? crystallins in vertebrates and S crystallins in cephalopods. 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 ? 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 crystalline 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 ? crystallins and S crystallins. PMID:21566271

  6. Instrumentation and First Results of the Reflected Solar Demonstration System for the Climate Absolute Radiance and Refractivity Observatory

    NASA Technical Reports Server (NTRS)

    McCorkel, Joel; Thome, Kurtis; Hair, Jason; McAndrew, Brendan; Jennings, Don; Rabin, Douglas; Daw, Adrian; Lundsford, Allen

    2012-01-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission key goals include enabling observation of high accuracy long-term climate change trends, use of these observations to test and improve climate forecasts, and calibration of operational and research sensors. The spaceborne instrument suites include a reflected solar spectroradiometer, emitted infrared spectroradiometer, and radio occultation receivers. The requirement for the RS instrument is that derived reflectance must be traceable to Sl standards with an absolute uncertainty of <0.3% and the error budget that achieves this requirement is described in previo1L5 work. This work describes the Solar/Lunar Absolute Reflectance Imaging Spectroradiometer (SOLARIS), a calibration demonstration system for RS instrument, and presents initial calibration and characterization methods and results. SOLARIS is an Offner spectrometer with two separate focal planes each with its own entrance aperture and grating covering spectral ranges of 320-640, 600-2300 nm over a full field-of-view of 10 degrees with 0.27 milliradian sampling. Results from laboratory measurements including use of integrating spheres, transfer radiometers and spectral standards combined with field-based solar and lunar acquisitions are presented. These results will be used to assess the accuracy and repeatability of the radiometric and spectral characteristics of SOLARIS, which will be presented against the sensor-level requirements addressed in the CLARREO RS instrument error budget.

  7. Non-magnetic nano-composites for optical and infrared negative refraction index media

    E-print Network

    Robyn Wangberg; Justin Elser; Evgenii E. Narimanov; Viktor A. Podolskiy

    2005-06-27

    We develop an approach to use nanostructured plasmonic materials as a non-magnetic negative-refractive index system at optical and near-infrared frequencies. In contrast to conventional negative refraction materials, our design does not require periodicity and thus is highly tolerant to fabrication defects. Moreover, since the proposed materials are intrinsically non-magnetic, their performance is not limited to proximity of a resonance so that the resulting structure has relatively low loss. We develop the analytical description of the relevant electromagnetic phenomena and justify our analytic results via numerical solutions of Maxwell equations.

  8. Lens-free inline holographic microscopy with numerical correction of layers with different refractive index.

    PubMed

    Kanka, Mario; Riesenberg, Rainer

    2015-03-01

    Digital inline holographic microscopy is applied for lens-free imaging with high lateral resolution. Microfluidic chambers for the imaging of cells in water-like or native solutions, e.g., thick layers of glass and other materials with different refractive index, cause aberrations that limit the spatial resolution and change the magnification scale. In this Letter, a fast reconstruction technique considering parallel layer systems of different refractive indices is presented. In the experiments, properly scaled images of microbeads and red human blood cells with an optical resolution corresponding to a numerical aperture of about 0.62 were reconstructed. PMID:25723424

  9. A Multi-D-Shaped Optical Fiber for Refractive Index Sensing

    PubMed Central

    Chen, Chien-Hsing; Tsao, Tzu-Chein; Tang, Jaw-Luen; Wu, Wei-Te

    2010-01-01

    A novel class of multi-D-shaped optical fiber suited for refractive index measurements is presented. The multi-D-shaped optical fiber was constructed by forming several D-sections in a multimode optical fiber at localized regions with femtosecond laser pulses. The total number of D-shaped zones fabricated could range from three to seven. Each D-shaped zone covered a sensor volume of 100 ?m depth, 250 ?m width, and 1 mm length. The mean roughness of the core surface obtained by the AFM images was 231.7 nm, which is relatively smooth. Results of the tensile test indicated that the fibers have sufficient mechanical strength to resist damage from further processing. The multi-D-shaped optical fiber as a high sensitive refractive-index sensor to detect changes in the surrounding refractive index was studied. The results for different concentrations of sucrose solution show that a resolution of 1.27 × 10?3–3.13 × 10?4 RIU is achieved for refractive indices in the range of 1.333 to 1.403, suggesting that the multi-D-shaped fibers are attractive for chemical, biological, and biochemical sensing with aqueous solutions. PMID:22399908

  10. Fiber-optic refractive index sensor based on surface plasmon resonance

    NASA Astrophysics Data System (ADS)

    Hlubina, Petr; Ciprian, Dalibor; Kadulova, Miroslava

    2015-01-01

    A fiber-optic refractive index sensor based on surface plasmon resonance (SPR) in a thin metal film deposited on an unclad core of a multimode fiber is presented. The sensing element of the SPR fiber-optic sensor is a bare core of a step-index optical fiber made of fused silica with a deposited gold film. First, a model of the SPR fiber-optic sensor based on the theory of attenuated total internal reflection is presented. The analysis is carried out in the frame of optics of multilayered media. The sensing scheme uses a wavelength interrogation method and the calculations are performed over a broad spectral range. Second, in a practical realization of the sensor with a double-sided sputtered gold film, a reflection-based sensing scheme to measure the refractive indices of liquids is considered. The refractive index of a liquid is sensed by measuring the position of the dip in the reflected spectral intensity distribution. As an example, the aqueous solutions of ethanol with refractive indices in a range from 1.333 to 1.364 are measured.

  11. Controlled refractive index of photosensitive polymer: towards photo-induced waveguide for near infrared wavelengths

    NASA Astrophysics Data System (ADS)

    Assa??d, Imane; Hardy, Isabelle; Bosc, Dominique

    2002-12-01

    Photo-writing process of polymer optical waveguides can offer advantages to make easier connection fiber guide, and noticeably simplifies the fabrication procedure. In order to carry out a photo-writing technique, we choose a photosensitive polymer. Thus, under far UV irradiation, polyvinylcinnamate (PVCi) undergoes a change in its absorption, yielding a refractive index variation. This work presents the first results of relationship between the bleaching of the UV band and the refractive index change in the area of optical telecommunication spectrum. By the way, it is shown that the index contrast obtained by controlling the UV source, can be improved, in order to make suitable this process for printing integrated optical waveguides.

  12. Refractive index sensor based on stress-induced long period grating

    NASA Astrophysics Data System (ADS)

    Lin, Guei-Ru; Chang, Hung-Ying; Fu, Ming-Yue; Sheng, Hao-Jan; Liu, Wen-Fung

    2014-09-01

    We proposed a novel refractive index sensor based on a side-polishing fiber to be cascaded with a stress-induced long period fiber grating (LPG), which is created by applying a force to a V-grooved plate on the single mode fiber with micro-bending deformation. When the refractive index (RI) surrounding the side-polishing surface is changed, the LPG-induced cladding mode light could be coupled back to the core mode, so that it will result in the magnitude variation of LPG loss-peak. This property of index sensing based on the stress-induced LPG by monitoring the power-level change may be exploited in chemical sensing and environmental monitoring applications.

  13. Retrieving the complex refractive index of atmospheric aerosols from ratios of solar spectral extinction measurements

    NASA Technical Reports Server (NTRS)

    Fymat, A. L.; Mease, K. D.

    1978-01-01

    The technique proposed by Fymat (1976) for retrieving the complex refractive index of atmospheric aerosols using narrowband spectral transmission ratios, taken within an overall narrow spectral interval, is investigated in the case of modelled polydispersions of rural, maritime-continental, maritime-sea spray and meteoric dust aerosols. It is confirmed that for not too broad size distributions most of the information comes from a narrow size range of 'active' aerosols so that, under these circumstances, the refractive index components can indeed be retrieved essentially independently of the size distribution. For 0.1% accurate data in three colors, the technique can provide the real and imaginary components of the index respectively within 0.07% and 0.3% accuracy.

  14. Improving Axial Resolution in Confocal Microscopy with New High Refractive Index Mounting Media

    PubMed Central

    Fouquet, Coralie; Gilles, Jean-François; Heck, Nicolas; Dos Santos, Marc; Schwartzmann, Richard; Cannaya, Vidjeacoumary; Morel, Marie-Pierre; Davidson, Robert Stephen; Trembleau, Alain; Bolte, Susanne

    2015-01-01

    Resolution, high signal intensity and elevated signal to noise ratio (SNR) are key issues for biologists who aim at studying the localisation of biological structures at the cellular and subcellular levels using confocal microscopy. The resolution required to separate sub-cellular biological structures is often near to the resolving power of the microscope. When optimally used, confocal microscopes may reach resolutions of 180 nm laterally and 500 nm axially, however, axial resolution in depth is often impaired by spherical aberration that may occur due to refractive index mismatches. Spherical aberration results in broadening of the point-spread function (PSF), a decrease in peak signal intensity when imaging in depth and a focal shift that leads to the distortion of the image along the z-axis and thus in a scaling error. In this study, we use the novel mounting medium CFM3 (Citifluor Ltd., UK) with a refractive index of 1.518 to minimize the effects of spherical aberration. This mounting medium is compatible with most common fluorochromes and fluorescent proteins. We compare its performance with established mounting media, harbouring refractive indices below 1.500, by estimating lateral and axial resolution with sub-resolution fluorescent beads. We show furthermore that the use of the high refractive index media renders the tissue transparent and improves considerably the axial resolution and imaging depth in immuno-labelled or fluorescent protein labelled fixed mouse brain tissue. We thus propose to use those novel high refractive index mounting media, whenever optimal axial resolution is required. PMID:25822785

  15. On the mechanism of photoinduced refractive index changes in phosphosilicate glass

    SciTech Connect

    Larionov, Yu V [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Sokolov, V O; Plotnichenko, V G [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

    2010-05-26

    The photoinduced growth of the refractive index of phosphosilicate glass during Bragg grating inscription and the thermal decay of the grating have a number of unusual features. The observed index variations are interpreted in terms of a new model for photoinduced glass network rearrangement. The model assumes the formation of photoinduced voids (nanopores) in the glass network near point defects. The nanopores may migrate through the network via bond switching when the network is in a 'soft' state. The photoinduced variations in network density lead to index variations. (fibres)

  16. Sub-Wavelength Imaging of Photo-Induced Refractive Index Pattern in Chalcogenide Glass Films

    SciTech Connect

    Yang, Zhiyong; Anheier, Norman C.; Qiao, Hong (Amy); Lucas, Pierre

    2009-11-15

    Mapping of refractive index patterns with sub-wavelength resolution is achieved using Near-field Scanning Optical Microscopy (NSOM) in reflection mode. Imaging of index pattern is performed on surface gratings photo-imprinted in As2S3 films. The NSOM is adapted with a near infrared laser which wavelength (785 nm) is chosen to be within the transparency window of the glass film therefore allowing consistent measure of reflected light. Quantitative measurements of photo-induced index changes can then be obtained from knowledge of the initial film index. Images of gratings with a period of 0.5 micron are easily collected therefore demonstrating sub-wavelength spatial resolution. The technique permits to concurrently obtain a topographic image and index image of the gratings thereby permitting to quantify the extent of photodarkening and photoexpansion simultaneously. It is shown that relief gratings tend to vanish in films aged in air for several months however the index gratings remain.

  17. Lossy gradient index metamaterial with sinusoidal periodicity of refractive index: case of constant impedance throughout the structure

    NASA Astrophysics Data System (ADS)

    Dalarsson, Mariana; Norgren, Martin; Jakši?, Zoran

    2011-01-01

    We used an exact analytical approach to investigate the electromagnetic wave propagation across an isotropic metamaterial composite with i. a sinusoidally periodic gradient of the real parts of the effective permittivity and permeability, ii. spatially uniform imaginary parts of the effective permittivity and permeability, and iii. spatially uniform impedance. The real part of the effective refractive index can be positive and negative along the direction of nonhomogeneity. A remarkably simple direct solution for the field distribution was obtained.

  18. Methods to calibrate and scale axial distances in confocal microscopy as a function of refractive index

    PubMed Central

    BESSELING, TH; JOSE, J; BLAADEREN, A VAN

    2015-01-01

    Accurate distance measurement in 3D confocal microscopy is important for quantitative analysis, volume visualization and image restoration. However, axial distances can be distorted by both the point spread function (PSF) and by a refractive-index mismatch between the sample and immersion liquid, which are difficult to separate. Additionally, accurate calibration of the axial distances in confocal microscopy remains cumbersome, although several high-end methods exist. In this paper we present two methods to calibrate axial distances in 3D confocal microscopy that are both accurate and easily implemented. With these methods, we measured axial scaling factors as a function of refractive-index mismatch for high-aperture confocal microscopy imaging. We found that our scaling factors are almost completely linearly dependent on refractive index and that they were in good agreement with theoretical predictions that take the full vectorial properties of light into account. There was however a strong deviation with the theoretical predictions using (high-angle) geometrical optics, which predict much lower scaling factors. As an illustration, we measured the PSF of a correctly calibrated point-scanning confocal microscope and showed that a nearly index-matched, micron-sized spherical object is still significantly elongated due to this PSF, which signifies that care has to be taken when determining axial calibration or axial scaling using such particles. PMID:25444358

  19. Methods to calibrate and scale axial distances in confocal microscopy as a function of refractive index.

    PubMed

    Besseling, T H; Jose, J; Van Blaaderen, A

    2015-02-01

    Accurate distance measurement in 3D confocal microscopy is important for quantitative analysis, volume visualization and image restoration. However, axial distances can be distorted by both the point spread function (PSF) and by a refractive-index mismatch between the sample and immersion liquid, which are difficult to separate. Additionally, accurate calibration of the axial distances in confocal microscopy remains cumbersome, although several high-end methods exist. In this paper we present two methods to calibrate axial distances in 3D confocal microscopy that are both accurate and easily implemented. With these methods, we measured axial scaling factors as a function of refractive-index mismatch for high-aperture confocal microscopy imaging. We found that our scaling factors are almost completely linearly dependent on refractive index and that they were in good agreement with theoretical predictions that take the full vectorial properties of light into account. There was however a strong deviation with the theoretical predictions using (high-angle) geometrical optics, which predict much lower scaling factors. As an illustration, we measured the PSF of a correctly calibrated point-scanning confocal microscope and showed that a nearly index-matched, micron-sized spherical object is still significantly elongated due to this PSF, which signifies that care has to be taken when determining axial calibration or axial scaling using such particles. PMID:25444358

  20. Influence of the refractive index on EGFP fluorescence lifetimes in mixtures of water and glycerol

    NASA Astrophysics Data System (ADS)

    Suhling, Klaus; Davis, Daniel M.; Petrasek, Zdenek; Siegel, Jan; Phillips, David

    2001-07-01

    As a precursor to applying fluorescence lifetime imaging (FLIM) to studies of intercellular communication in molecular immunology, we have investigated the fluorescence lifetime of enhanced green fluorescent protein (EGFP) in mixtures of water and glycerol using time-correlated single photon counting (TCSPC). We find that the EGFP lifetime decreases with increasing glycerol content. This is accounted for quantitatively by the refractive index dependence of the fluorescence lifetime as predicted by the Strickler Berg formula which relates the fluorescence lifetime to the absorption spectrum. The solvent viscosity has no influence on the fluorescence lifetime. We also discuss the refractive index dependence of the GFP fluorescence lifetime in more complex systems. The findings are particularly relevant for the interpretation of FLIM of GFP expressed in environments such as bacteria and cells.

  1. Ellipsometry and ab initio approaches to the refractive index of porous silicon

    NASA Astrophysics Data System (ADS)

    Cisneros, Rodolfo; Ramírez, Carlos; Wang, Chumin

    2007-10-01

    Spectroscopic ellipsometry is used to determine the complex refractive index (n-ik), porosity, and thickness of porous silicon (PSi) films. These films are obtained by anodizing p-type crystalline silicon in a hydrofluoric acid bath. After etching, PSi samples are heated to 750 °C in a controlled oxygen environment. A detailed analysis of the ellipsometry data is performed in order to determine the complex refractive index of PSi thin film. This frequency dependence of n and k is compared with the results of ab initio quantum mechanical calculations carried out by means of CASTEP codes within the density functional theory. The theoretical results show a diminution of the lattice constant as the oxygen content grows, in contrast to the hydrogen-saturated surface case.

  2. Etching Bragg gratings in Panda fibers for the temperature-independent refractive index sensing.

    PubMed

    Li, Jie; Wang, Hao; Sun, Li-Peng; Huang, Yunyun; Jin, Long; Guan, Bai-Ou

    2014-12-29

    We demonstrate the evolution of the Bragg gratings inscribed in Panda fibers with chemical etching. The resonance wavelengths can blueshift with cladding reduction similar to the conventional counterparts. But the wavelength separation between the two polarizations is co-determined by the stress and the asymmetric shape effects. The fast and slow axes of the fiber can be reversed with each other and zero birefringence can be achieved by chemical etching the structure. When the stress-applying parts of the fiber are removed, the finalizing grating can be exploited for the temperature-independent refractive index sensing, since the modes corresponding to the two polarizations exhibit the dissimilar responses to the external refractive index change but the same response to temperature. Our device is featured with easy achievement, spectral controllability, and relative robustness. PMID:25607160

  3. Temperature-dependent Sellmeier equation for the refractive index of stoichiometric lithium tantalate.

    PubMed

    Bruner, Ariel; Eger, David; Oron, Moshe B; Blau, Pinhas; Katz, Moti; Ruschin, Shlomo

    2003-02-01

    We present a temperature-dependent Sellmeier equation for the refractive index of stoichiometric LiTaO3. The extraordinary refractive index, for the range 0.39-4.1 microm and for temperatures of 30-200 degrees C, are based on previously published data [Jpn. J. Appl. Phys. 41, 465 (2002)] and on measured data derived from quasi-phase-matched (QPM) resonances. We used the new Sellmeier coefficients that we obtained to calculate the QPM wavelengths for an optical parametric oscillator (OPO) based on periodically poled stoichiometric LiTaO3 pumped at 1064 nm. The measured wavelengths of the OPO were in good agreement with our predictions. PMID:12656329

  4. Measurements of refractive index sensitivity using long-period grating refractometer

    NASA Astrophysics Data System (ADS)

    Chong, Joo Hin; Shum, Ping; Haryono, H.; Yohana, A.; Rao, M. K.; Lu, Chao; Zhu, Yinian

    2004-01-01

    We report the development and demonstration of a long-period grating refractometer. The principle of operation is based on the using of a long-period grating that is structurally induced by a CO 2 laser, and where the resonance wavelengths are shifted as the refractive index of medium surrounding the cladding of the long-period grating. The different concentrations for three types of solutions (ethylene glycol, salt, and sugar) were experimentally measured, and results show that, as a refractometer, this fiber-based device not only can differentiate chemicals based on their refractive index, but it can also become a concentration indicator of a particular chemical solution, and applied in the oil and petroleum industry.

  5. Measurement of Elastic Constant and Refraction Index of Thin Films at Low Temperatures Using Picosecond Ultrasound

    NASA Astrophysics Data System (ADS)

    Tanigaki, Kenichi; Kusumoto, Tatsuya; Ogi, Hirotsugu; Nakamura, Nobutomo; Hirao, Masahiko

    2010-07-01

    In this paper, a picosecond ultrasound measurement is conducted to evaluate the low-temperature elastic and optical properties of thin films and semiconductors. Specimens are cooled with liquid He through a heat exchanger in a cryostat, and an ultrahigh-frequency acoustic pulse is generated using a femtosecond light pulse, which propagates in the film-thickness direction. Pulse echoes of the longitudinal wave and Brillouin oscillation are observed by the changes in reflectivity of the time-delayed probe light, which depend on the material, and give the longitudinal-wave out-of-plane elastic constant. When the stiffness is known, the Brillouin oscillation provides the refractive index. We determined the stiffness of a Pt thin film and the refractive index of Si at 5 K. The methodology developed in this paper is useful for studing the elastic and optical properties of metallic thin films and transparent materials at cryogenic temperatures.

  6. Ultrasensitive refractive index sensor with temperature insensitivity based on concatenated LPGs

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    In this paper we report on fabrication and characterization of a refractive index sensor based on two concatenated double resonanced long period fiber gratings (LPFGs) with an inter grating space in between them. The inter grating space provides a temperature dependent extra phase difference between the core mode and the participating cladding modes, making the sensor similar to a Mach-Zehnder interferometer with its arms phase shifted. We demonstrate that by adjusting the inter grating space the thermally induced phase difference in the LPG region can be compensated, producing temperature insensitive resonance wavelengths. The interferometer is highly stable over a wide range of temperatures (20-100 °C). The measured refractive index sensitivity for aqueous solutions (1.333-1.393) is 2583.3 nm/RIU, which is highly desirable for precision sensing of biological samples.

  7. The refractive index and electronic gap of water and ice increase with increasing pressure

    PubMed Central

    Pan, Ding; Wan, Quan; Galli, Giulia

    2014-01-01

    Determining the electronic and dielectric properties of water at high pressure and temperature is an essential prerequisite to understand the physical and chemical properties of aqueous environments under supercritical conditions, for example, in the Earth interior. However, optical measurements of compressed ice and water remain challenging, and it has been common practice to assume that their band gap is inversely correlated with the measured refractive index, consistent with observations reported for hundreds of materials. Here we report ab initio molecular dynamics and electronic structure calculations showing that both the refractive index and the electronic gap of water and ice increase with increasing pressure, at least up to 30?GPa. Subtle electronic effects, related to the nature of interband transitions and band edge localization under pressure, are responsible for this apparently anomalous behaviour. PMID:24861665

  8. Observation of refractive index gradients in a laser-generated plume using laser schlieren imaging

    SciTech Connect

    Essien, M.; Keicher, D.M.; Jellison, J.L.

    1995-12-31

    Understanding the interaction between a pulsed Nd:YAG laser beam and the plume generated above the surface of a workpiece during laser welding is important for process modeling and control. We present a laser schlieren method which can be used to observe this interaction by imaging the refractive index gradient within the plume. The laser schlieren technique uses an expanded, collimated probe laser beam to image a phase object onto a filter with a radial gradient in optical density. The probe beam is focused through the filter and onto the image plane of an intensified high-speed camera, so that the temporal variation of the laser/plume interaction may be observed over the duration of the laser pulse. Qualitative measurements of the spatial distribution of refractive index are presented. The velocity of the vaporized metal forming the plume is also measured for a stainless steel weldment.

  9. The Deviation of the Vacuum Refractive Index Induced by a Static Gravitational Field

    E-print Network

    Xing-Hao Ye; Qiang Lin

    2007-04-10

    We analyzed the influence of static gravitational field on the vacuum and proposed the concept of inhomogeneous vacuum. According to the observational result of the light deflection in solar gravitational field as well as the corresponding Fermat's principle in the general relativity, we derived an analytical expression of the refractive index of vacuum in a static gravitational field. We found that the deviation of the vacuum refractive index is composed of two parts: one is caused by the time dilation effect, the other is caused by the length contraction effect. As an application, we simulated the effect of the gravitational lensing through computer programming and found that the missing central imaging could be interpreted in a reasonable way.

  10. Imaging-eclipsing-Z-scan method for measurement of the nonlinear refractive index of materials

    NASA Astrophysics Data System (ADS)

    Mohebi, Mehrdad; Jamasbi, Nooshin; Morales, Omar; Garduno, Jesus; Said, Ali A.; Van Stryland, Eric W.

    1999-07-01

    We present a new variation of the Z-scan technique, which provides a sensitive method for measurement of the nonlinear refractive index of materials. The method is based on imaging of a top hat beam onto a blocking disk; therefore, it is very sensitive. In addition to greater sensitivity the method offers the advantage that it does not require a Gaussian beam, therefore it can be used with low energy lasers with any beam profile.

  11. Isotropic optical negative index of refraction metamaterials composed of randomly arranged nanoparticles

    Microsoft Academic Search

    Adil-Gerai Kussow; Alkim Akyurtlu

    2007-01-01

    We report a strategy for achieving fully isotropic negative refraction index in a homogenized composite medium (HCM) conceptualized using both Maxwell-Garnett's and Lewin's effective medium formulations. The HCM consists of two isotropic dielectric-magnetic media (DMM): one DMM (randomly distributed small gold nanoparticles in free space) provides only negative permittivity, and another DMM (spherical SiC particles) provides only negative permeability via

  12. Design of a refractive index sensor based on surface soliton waveguides

    NASA Astrophysics Data System (ADS)

    Fiumara, T.; Fazio, E.

    2013-12-01

    The design of an innovative integrated sensor based on superficial soliton waveguides is presented. This configuration is called a RISSOR: refractive-index surface-soliton sensor. The hybrid structure combines traditional rib waveguides with a superficial one realized by a superficial photorefractive soliton. Simulations are performed using a BPM numerical code. The sensitivity of the proposed device is based on the solitonic evanescent wave as well as the coupling between the rib and solitonic waveguides.

  13. Genetic Algorithm Retrieval of Real Refractive Index from Aerosol Distributions that are not Lognormal

    Microsoft Academic Search

    Brian Barkey; Hwajin Kim; Suzanne E. Paulson

    2010-01-01

    Size distributions of real-world aerosols typically deviate substantially from log-normal or other simple mathematical descriptions. The effect of assuming a lognormal shape for distributions that are not well described by this function on the genetic algorithm (GA) retrieval of the real refractive index (mr from scattering properties is investigated. Tests using several laboratory-generated ammonium sulfate aerosols with relatively broad bimodal

  14. Refractive index and birefringence of InxGa1-xN films grown by MOCVD

    Microsoft Academic Search

    N. A. Sanford; A. Munkholm; M. R. Krames; A. Shapiro; I. Levin; A. V. Davydov; S. Sayan; L. S. Wielunski; T. E. Madey

    2005-01-01

    The refractive index and birefringence of InxGa1-xN films grown on GaN layers were measured by prism coupling used in conjunction with multilayer optical waveguide analysis. Samples with x = 0.036, 0.049, 0.060, and 0.066 were examined at the separate wavelengths of 442, 457.9, 476.5, 488, 514.5, 532, and 632.8 nm. The In fraction x was determined by Rutherford backscattering spectroscopy.

  15. Preparation of nearly monodisperse multiply coated submicrospheres with a high refractive index

    Microsoft Academic Search

    Qunyan Li; Peng Dong

    2003-01-01

    Nearly monodisperse SiO2\\/TiO2\\/SiO2 multiply coated submicrospheres with nearly monodisperse silica submicrospheres as cores, thick titania layers, and thin silica skin were prepared to increase the refractive index of complex submicrospheres while keeping their near monodispersity and perfect surface properties. Nearly monodisperse colloidal silica submicrospheres as cores with a diameter of 200 nm were synthesized by a seeding technique on the basis

  16. Liquid core fibre Bragg grating based refractive index sensor formed by femtosecond assisted chemical etching technique

    Microsoft Academic Search

    P. Saffari; Z. Yan; K. Zhou; L. Zhang; I. Bennion

    2011-01-01

    We report the fabrication of a refractive index (RI) sensor based on a liquid core fibre Bragg grating (FBG). A micro-slot FBG was created in standard telecom optical fibre employing the tightly focused femtosecond laser inscription aided chemical etching. A micro-slot with dimensions of 5.74(h) × 125(w) × 1388.72(l) mum was engraved across the whole fibre and along 1mm long

  17. Calculation of Refractive Index Changes from Thermal Lens Fringes using Continuous Wavelet Algorithm

    NASA Astrophysics Data System (ADS)

    Saraç, Zehra; Dursun, Ali; Yerdelen, Sündüs; Necati Ecevit, F.

    2007-06-01

    Thermal lens fringes are obtained on the nile-blue/ethanol solution by illuminating it with a He-Ne laser in a Mach-Zehnder interferometer. The refractive index change distribution of these fringes is calculated by using two different continuous wavelet transform (CWT) algorithms. It is concluded that the CWT-phase method works better than the CWT-gradient algorithm for the analysis of thermal lens fringes according to theoretical results.

  18. Extracting accurate complex refractive index from solid pellets based on time-domain terahertz reflection spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Lin; Zhang, Yu; He, Yingfeng; Sun, Ping; Zou, Yun; Jia, Qiongzhen; Yang, Qinghua

    2014-11-01

    A complex filtering method for eliminating systematic and random noises of THz-TDS is proposed. This method is the combination of deconvolution and wavelet filtering algorithms. A self-reference method for extracting the complex refractive index of material accurately is also proposed in order to avoid a phase shift due to the misplacement between the surfaces of the reference and sample using the time-domain terahertz reflection spectroscopy. The basic idea of self-reference method is that the first and the second peaks of the reflection spectrum of solid pellets are regarded as the reference and sample signals, respectively. Thus more information of samples can be extracted because of a longer optical path, and meanwhile, phase error can be avoided by obtaining the reference and sample signals through a single measurement. According to the Fresnel formulas, we deduce the expression of complex refractive index and then design an iterative algorithm for solving it. We choose the glucose solid pellets as samples to test the self-reference method. After measuring the time-domain reflection spectrum, we adopted the complex filter method for filtering and utilized the self-reference method to extract the complex refractive index. Based on Density Functional Theory (DFT), the characteristic absorption spectrum of multiple glucose molecules in the THz absorption spectroscopy was obtained by the simulation analysis on the vibration of multiple glucose molecules. The results indicate that the absorption peaks appear in the absorption coefficient curves at the corresponding frequency positions which are approximately consistent with the results of the simulation based on DFT. So the methods we proposed can help improve the retrieval accuracy of complex refractive index.

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

    SciTech Connect

    Adamova, M S; Zolotovskii, Igor' O; Sementsov, Dmitrii I [Ul'yanovsk State University, Ul'yanovsk (Russian Federation)

    2009-03-31

    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. (solitons)

  20. Refractive index and dispersion of butterfly chitin and bird keratin measured by polarizing

    E-print Network

    Refractive index and dispersion of butterfly chitin and bird keratin measured by polarizing are 1.569, 1.556 and 1.548, respectively. The dispersion spectra of the chitin in the butterfly scales.517 and B = 8.80·103 nm2 for the butterfly chitin and A = 1.532 and B = 5.89·103 nm2 for the bird keratin

  1. Adsorption-Based Reflectance Tuning of 2D Metamaterial with Ultralow Effective Refractive Index

    Microsoft Academic Search

    Katarina Radulovi; Dragan Tanaskovi

    2007-01-01

    We analyzed metamaterial structures with all- positive, near-zero refractive index, composed of nanowire mesh media with a Drude-type, plasma-like dispersion of dielectric permittivity. We investigated the possibility to tune electromagnetic properties of these structures by allowing adsorption of a thin gaseous or liquid dielectric layer (down to a monomolecular or monoatomic thickness) on the wire surface, or, alternatively, by immersing

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

    NASA Astrophysics Data System (ADS)

    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.

  3. Studies of Microwave Absorption in Liquids by Optical Heterodyne Detection of Thermally Induced Refractive Index Fluctuations

    Microsoft Academic Search

    Mays Littleton Swicord

    1980-01-01

    This work describes the development and implementation of an optical detection method for determining the microwave absorption properties of liquids and liquid suspensions. The method employs a Mach-Zehnder interferometer illuminated with a single-frequency laser to detect fluctuations in the index of refraction of a transparent or semi-transparent substance placed in one arm of the interferometer. The fluctuations are induced by

  4. The design and performance of an isotropic negative-refractive-index metamaterial lens

    Microsoft Academic Search

    S. M. Rudolph; A. Grbic

    2011-01-01

    In this paper, a three-dimensional, fully-isotropic, broadband negative-refractive-index (NRI) medium is proposed. The structure has a NRI bandwidth of 23.5% and a simulated loss of 0.063dB\\/cell at the operating frequency of 1.51GHz (where ?? ?? ?? 1). The metamaterial is used to realize a NRI lens, the fabrication of which is described in detail. Analytical methods are used to predict

  5. Nonlinear wave mixing and susceptibility properties of negative refractive index materials

    Microsoft Academic Search

    Aref Chowdhury; John A. Tataronis

    2007-01-01

    We present an analysis of second-order and third-order nonlinear susceptibilities and wave-mixing properties of negative refractive index materials. We show that the nonlinear susceptibilities for noncentrosymmetric and centrosymmetric media may be positive or negative and away from resonance depending on the frequency of interest relative to the resonant frequencies of the material. Manipulation of the signs of the nonlinear susceptibilities

  6. Refractive index of He in the region 920-1910 A

    NASA Technical Reports Server (NTRS)

    Huber, M. C. E.; Tondello, G.

    1974-01-01

    The refractive index of He has been determined in the region 920-1910 A by measurements of wavelength shifts in a 3-m spectrograph alternately filled with He and evacuated. Differential pumping systems were used to allow operation of the light source at conveniently low pressures. Several plates were measured and analyzed in order to reduce statistical errors. The results at 919 A agree with the theory within 1%, i.e., less than the experimental error.

  7. Refractive Index of Light in the Quark-Gluon Plasma with the Hard-Thermal-Loop Perturbation Theory

    E-print Network

    Juan Liu; M. J. Luo; Qun Wang; Hao-jie Xu

    2011-12-20

    The electric permittivity and magnetic permeability for the quark-gluon plasma (QGP) is calculated within the hard-thermal-loop (HTL) perturbation theory. The refractive indices in the magnetizable and non-magnetizable plasmas are calculated. In a magnetizable plasma, there is a frequency pole $\\omega_{mp}$ in the magnetic permeability and the refractive index. The refractive index becomes negative in the range $\\omega\\in[k,\\omega_{mp}]$, where $k$ is the wave number, but no propagating modes are found. In a non-magnetizable plasma, the magnetic permeability and the refractive index are always positive. This marks the main distinction of a weakly coupled plasma from a strongly coupled one, where the negative refraction is shown to exist in a holographic theory.

  8. Correction of stain variations in nuclear refractive index of clinical histology specimens.

    PubMed

    Uttam, Shikhar; Bista, Rajan K; Hartman, Douglas J; Brand, Randall E; Liu, Yang

    2011-11-01

    For any technique to be adopted into a clinical setting, it is imperative that it seamlessly integrates with well-established clinical diagnostic workflow. We recently developed an optical microscopy technique-spatial-domain low-coherence quantitative phase microscopy (SL-QPM) that can extract the refractive index of the cell nucleus from the standard histology specimens on glass slides prepared via standard clinical protocols. This technique has shown great potential in detecting cancer with a better sensitivity than conventional pathology. A major hurdle in the clinical translation of this technique is the intrinsic variation among staining agents used in histology specimens, which limits the accuracy of refractive index measurements of clinical samples. In this paper, we present a simple and easily generalizable method to remove the effect of variations in staining levels on nuclear refractive index obtained with SL-QPM. We illustrate the efficacy of our correction method by applying it to variously stained histology samples from animal model and clinical specimens. PMID:22112118

  9. Zoned near-zero refractive index fishnet lens antenna: Steering millimeter waves

    NASA Astrophysics Data System (ADS)

    Pacheco-Peña, V.; Orazbayev, B.; Beaskoetxea, U.; Beruete, M.; Navarro-Cía, M.

    2014-03-01

    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 (?0 = 5.29 mm), the zoned fishnet metamaterial lens, designed to have a focal length FL = 9?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.

  10. Spatial variation of refractive index in a pane of float glass.

    PubMed

    Bennett, R L; Kim, N D; Curran, J M; Coulson, S A; Newton, A W

    2003-01-01

    In the statistical interpretation of forensic glass evidence it is standard practice to make the assumption of homogeneity of the refractive index (RI) of the source glass, or of localized homogeneity. However, the work of Locke and Hayes showed that, for toughened windscreen glass, this assumption might not be true. This work is well cited, but there appears to have been little follow-on published research. Furthermore, the toughening process is something known to affect the refractive index, and is a process that float glass does not undergo. Float glass is a major component of casework in New Zealand and for that reason it would be interesting to know whether the findings of Locke and Hayes apply when dealing with float glass. In this paper we describe an experiment similar to that of Locke and Hayes, systematically examining the variation of RI in a pane of float window glass. It was found that, although there were no systematic differences in refractive index, there were observable differences across the pane. PMID:12879568

  11. Contrast-enhanced digital holographic imaging of cellular structures by manipulating the intracellular refractive index

    NASA Astrophysics Data System (ADS)

    Rommel, Christina E.; Dierker, Christian; Schmidt, Lisa; Przibilla, Sabine; von Bally, Gert; Kemper, Björn; Schnekenburger, Jürgen

    2010-07-01

    The understanding of biological reactions and evaluation of the significance for living cells strongly depends on the ability to visualize and quantify these processes. Digital holographic microscopy (DHM) enables quantitative phase contrast imaging for high resolution and minimal invasive live cell analysis without the need of labeling or complex sample preparation. However, due to the rather homogeneous intracellular refractive index, the phase contrast of subcellular structures is limited and often low. We analyze the impact of the specific manipulation of the intracellular refractive index by microinjection on the DHM phase contrast. Glycerol is chosen as osmolyte, which combines high solubility in aqueous solutions and biological compatibility. We show that the intracellular injection of glycerol causes a contrast enhancement that can be explained by a decrease of the cytosolic refractive index due to a water influx. The underlying principle is proven by experiments inducing cell shrinkage and with fixated cells. The integrity of the cell membrane is considered as a prerequisite and allows a reversible cell swelling and shrinking within a certain limit. The presented approach to control the intracellular phase contrast demonstrated for the example of DHM opens prospects for applications with other quantitative phase contrast imaging methods.

  12. Lattice and electronic contributions to the refractive index of CuWO{sub 4}

    SciTech Connect

    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 CuWO{sub 4} 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 ?(?)?=?4.5(1) for light polarization parallel to the c-axis and ?(?)?=?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 CuWO{sub 4}. 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, 7?eV, as well as the origin of a structure observed at 4.4?eV in the reflectance spectrum, is discussed in the context of the CuWO{sub 4} electronic structure.

  13. Correction of stain variations in nuclear refractive index of clinical histology specimens

    NASA Astrophysics Data System (ADS)

    Uttam, Shikhar; Bista, Rajan K.; Hartman, Douglas J.; Brand, Randall E.; Liu, Yang

    2011-11-01

    For any technique to be adopted into a clinical setting, it is imperative that it seamlessly integrates with well-established clinical diagnostic workflow. We recently developed an optical microscopy technique--spatial-domain low-coherence quantitative phase microscopy (SL-QPM) that can extract the refractive index of the cell nucleus from the standard histology specimens on glass slides prepared via standard clinical protocols. This technique has shown great potential in detecting cancer with a better sensitivity than conventional pathology. A major hurdle in the clinical translation of this technique is the intrinsic variation among staining agents used in histology specimens, which limits the accuracy of refractive index measurements of clinical samples. In this paper, we present a simple and easily generalizable method to remove the effect of variations in staining levels on nuclear refractive index obtained with SL-QPM. We illustrate the efficacy of our correction method by applying it to variously stained histology samples from animal model and clinical specimens.

  14. Zoned near-zero refractive index fishnet lens antenna: Steering millimeter waves

    SciTech Connect

    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 (?{sub 0}?=?5.29?mm), the zoned fishnet metamaterial lens, designed to have a focal length FL?=?9?{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.

  15. Measurement of air refractive index fluctuation based on interferometry with two different reference cavity lengths.

    PubMed

    Chen, Qianghua; Luo, Huifu; Wang, Sumei; Wang, Feng; Chen, Xinhua

    2012-09-01

    A measurement method based on interferometry with two different reference cavity lengths is presented and applied in air refractive index measurement in which the two cavity lengths and a laser wavelength are combined to generate two wavelength equivalents of cavity. Corresponding calculation equations are derived, and the optical path configuration is designed, which is inspired by the traditional synthetic wavelength method. Theoretical analyses indicate that the measurement uncertainty of the determined index of refraction is about 2.3×10(-8), which is mainly affected by the length precision of the long vacuum cavity and the ellipticity of polarization components of the dual-frequency laser, and the range of nonambiguity is 3.0×10(-5), which is decided by the length difference of the two cavities. Experiment results show that the accuracy of air refractive index measurement is better than 5.0×10(-8) when the laboratory conditions changes slowly. The merit of the presented method is that the classical refractometry can be also used without evacuation of the gas cavity during the experiment. Furthermore, the application of the traditional synthetic wavelength method may be extended by using the wavelength equivalents of cavity, any value of which can be easily acquired by changing cavity length rather than using actual wavelengths whose number is limited. PMID:22945157

  16. Optically active ?-disks resonators-based sensor for refractive index variation detection

    NASA Astrophysics Data System (ADS)

    Ferrarese Lupi, F.; Navarro-Urrios, D.; Rubio-Garcia, J.; Monserrat, J.; Domínguez, C.; Garrido, B.

    2012-06-01

    The design, optical characterization and sensoristic capability provided by a complementary metal-oxide-semiconductor (CMOS) compatible integrated sensor based on a ?-disk resonator cavity are reported. The working principle of the presented device consists in monitoring the changes in the effective refractive index of the supported optical modes induced by variations of the refractive index of the surrounding material. The detection system has been designed on the base of a high quality factor (Q=1.4×104) Si-rich Si3N4 (SRSN) ?-disk - emitting in the VIS under optical pumping - bottom coupled to a low loss passive stoichiometric Si3N4 waveguide (WG), with losses values under 1 dB/cm measured in the same spectral region. The PL emission in the VIS range provided by the SRSN enable the use of Si-based detectors, easily integrable using the current CMOS standard technology. Proof of concept measurements performed on the coupled device revealed a good sensitivity of 51.79 nm/RIU (Refractive Index Unit), in accordance with the simulated data, and a minimum detection limit of 1.1 × 10-3 RIU.

  17. Determining the refractive index of shocked [100] lithium fluoride to the limit of transmissibility

    NASA Astrophysics Data System (ADS)

    Rigg, P. A.; Knudson, M. D.; Scharff, R. J.; Hixson, R. S.

    2014-07-01

    Lithium fluoride (LiF) is a common window material used in shock- and ramp-compression experiments because it displays a host of positive attributes in these applications. Most commonly, it is used to maintain stress at an interface and velocimetry techniques are used to record the particle velocity at that interface. In this application, LiF remains transparent to stresses up to 200 GPa. In this stress range, LiF has an elastic-plastic response with a very low (<0.5 GPa) elastic precursor and exhibits no known solid-solid phase transformations. However, because the density dependence of the refractive index of LiF does not follow the Gladstone-Dale relation, the measured particle velocity at this interface is not the true particle velocity and must be corrected. For that reason, the measured velocity is often referred to as the apparent velocity in these types of experiments. In this article, we describe a series of shock-compression experiments that have been performed to determine the refractive index of LiF at the two most commonly used wavelengths (532 nm and 1550 nm) between 35 and 200 GPa to high precision. A modified form of the Gladstone-Dale relation was found to work best to fit the determined values of refractive index. In addition, we provide a direct relationship between the apparent and true particle velocity to correct experimentally obtained wave profiles by others using these velocimetry techniques.

  18. Blood pH optrode based on evanescent waves and refractive index change

    NASA Astrophysics Data System (ADS)

    Hammarling, Krister; Hilborn, Jöns; Nilsson, Hans-Erik; Manuilskiy, Anatoliy

    2014-02-01

    Sensing pH in blood with an silica multimode optical fiber. This sensor is based on evanescent wave absorption and measures the change of the refractive index and absorption in a cladding made of a biocompatible Polymer. In contrast to many existing fiber optical sensors which are based upon different dyes or florescent material to sense the pH, here presents a solution where a part of the cladding is replaced with a Poly (?-amino ester) made of 1.4-Butanediol diacrylate, Piperazine, and Trimethylolpropane Triacrylate. Piperazine has the feature of changing its volume by swelling or shrinking in response to the pH level. This paper utilizes this dimension effect and measure the refractive index and the absorption of the cladding in respect to different pH-levels. The alteration of refractive index also causes a change in the absorption and therefore the output power changes as a function of the pH level. The sensor is sensitive to pH in a wide spectral range and light absorbency can be observed for wavelengths ranging from UV to far IR.

  19. Refractive Index and Scattering Effects on Radiative Behavior of a Semitransparent Layer

    NASA Technical Reports Server (NTRS)

    Spuckler, C. M.; Siegel, R.

    1993-01-01

    Heat transfer characteristics are analyzed for a plane layer of semitransparent material with refractive index not less than 1. Energy transfer in the material is by conduction, emission, absorption, and isotropic scattering. Each side of the layer is heated by radiation and convection. For a refractive index larger than unity, there is internal reflection of some of the energy within the layer. This, coupled with scattering, has a substantial effect on distributing energy across the layer and altering the temperature distribution from when the refractive index is unity. The effect of scattering is examined by comparisons with results from an earlier paper for an absorbing layer. Results are given for a gray medium with a scattering albedo up to 0.999, and for a two-band spectral variation of the albedo with one band having low absorption. Radiant energy leaving the surface as a result of emission and scattering was examined to determine if it could be used to accurately indicate the surface temperature.

  20. Velocimetry with refractive index matching for complex flow configurations, phase 1

    NASA Technical Reports Server (NTRS)

    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.

  1. Densities, refractive indices, absolute viscosities, and static dielectric constants of 2-methylpropan-2-ol + hexane, + benzene, + propan-2-ol, + methanol, + ethanol, and + water at 303.2 K

    SciTech Connect

    Rived, F.; Roses, M.; Bosch, E. [Universitat de Barcelona (Spain). Departament de Quimica Analitica

    1995-09-01

    Densities, refractive indices, absolute viscosities, and static dielectric constants have been measured over the entire range of composition for binary mixtures of 2-methylpropan-2-ol with hexane, benzene, propan-2-ol, methanol, ethanol, and water at 303.2 K. Excess molar volumes were fitted to Redlich-Kister equations.

  2. 1028 OPTICS LETTERS / Vol. 27, No. 12 / June 15, 2002 Direct measurement of index of refraction in the

    E-print Network

    of America OCIS codes: 160.2120, 120.3180. Refractive indices, n v 1 2 d v 1 ib v , in the extreme in the extreme-ultraviolet wavelength region with a novel interferometer Chang Chang,* Erik Anderson, Patrick, the first direct measurement of the dispersive part of the refractive index is performed at extreme

  3. Refraction of electromagnetic energy for wave packets incident on a negative-index medium is always negative

    E-print Network

    Sridhar, Srinivas

    Refraction of electromagnetic energy for wave packets incident on a negative-index medium is always February 2004 We analyze refraction of electromagnetic wave packets on passing from an isotropic positive, since all physical sources of electromagnetic waves produce radiation fields of finite spatial

  4. The application of the interference microscopy for the refractive index determination of the cell wall and cytoplasm in plant cells.

    PubMed

    Gabry?, H

    1978-03-01

    Interference microscopy method has been used for measuring the refractive indices of cell wall and cytoplasm of two plant species: Funaria hygrometrica and Lemna trisulca. The refractive index of the cytoplasm was determined by measuring the centrifuged cells. The mean values obtained for different wavelengths lie in the range 1.41-1.42. PMID:634148

  5. Refractive index gradient measurement across the thickness of a dielectric film by the prism coupling method

    SciTech Connect

    Sokolov, Viktor I; Panchenko, Vladislav Ya; Seminogov, V N [Institute of Laser and Information Technologies, Russian Academy of Sciences, Troitsk, Moscow Region (Russian Federation)

    2012-08-31

    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 H{sub f} 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 [{Delta} n(z)/n(z) || 1]. (laser applications and other topics in quantum electronics)

  6. All-dielectric three-dimensional broadband Eaton lens with large refractive index range

    SciTech Connect

    Yin, Ming; Yong Tian, Xiao, E-mail: leoxyt@mail.xjtu.edu.cn; Ling Wu, Ling; Chen Li, Di [State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an 710049 (China)

    2014-03-03

    We proposed a method to realize three-dimensional (3D) gradient index (GRIN) devices requiring large refractive index (RI) range with broadband performance. By combining non-resonant GRIN woodpile photonic crystals structure in the metamaterial regime with a compound liquid medium, a wide RI range (1–6.32) was fulfilled flexibly. As a proof-of-principle for the low-loss and non-dispersive method, a 3D Eaton lens was designed and fabricated based on 3D printing process. Full-wave simulation and experiment validated its omnidirectional wave bending effects in a broad bandwidth covering Ku band (12?GHz–18?GHz)

  7. Design of a novel negative refractive index material based on numerical simulation

    NASA Astrophysics Data System (ADS)

    Rizwan, Muhammad; Dou, Yan-Kun; Jin, Hai-Bo; Hou, Zhi-Ling; Kong, Ling-Bao; Li, Jing-Bo; Butt, Faheem K.; Rehman, Fida

    2013-07-01

    This paper presents a novel metamaterial constructed with wires, spheres and hollow slabs (WSHS), which simultaneously exhibits negative permittivity and permeability. An electromagnetic wave simulation is performed based on the proposed metamaterial and shows that a negative refractive index is achieved for this metamaterial. Adjusting the lattice constant of the unit cell is an easy way to manipulate the frequency of negative index of this structure. A left-hand material prism is designed composed of metamaterial unit cells and the simulation on the proposed prism proves the left-hand behavior of the designed metamaterial.

  8. The role of macromolecular crowding in the evolution of lens crystallins with high molecular refractive index

    NASA Astrophysics Data System (ADS)

    Zhao, Huaying; Magone, M. Teresa; Schuck, Peter

    2011-08-01

    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 ?-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 ?-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 ?-crystallins and S-crystallins.

  9. Zero Phase Delay in Negative-refractive-index Photonic Crystal Superlattices

    SciTech Connect

    Stein, A.; Kocaman, S.; Aras, M.S.; Hsieh, P.-C. McMillan, J.F.; Biris, C.G.; Panoiu, N.C.; Yu, M.B.; Kwong, D.L.; Wong, C.W.

    2011-08-01

    We show that optical beams propagating in path-averaged zero-index photonic crystal superlattices can have zero phase delay. The nanofabricated superlattices consist of alternating stacks of negative index photonic crystals and positive index homogeneous dielectric media, where the phase differences corresponding to consecutive primary unit cells are measured with integrated Mach-Zehnder interferometers. These measurements demonstrate that at path-averaged zero-index frequencies the phase accumulation remains constant and equal to zero despite the increase in the physical path length. We further demonstrate experimentally that these superlattice zero- bandgaps remain invariant to geometrical changes of the photonic structure and have a center frequency which is deterministically tunable. The properties of the zero- gap frequencies, optical phase, and effective refractive indices are well described by detailed experimental measurements, rigorous theoretical analysis, and comprehensive numerical simulations.

  10. Fabrication of gradient refractive index ball lenses using the method of combination of ion exchanging and sagging

    NASA Astrophysics Data System (ADS)

    Hao, Lv; Bangren, Shi; Jijiang, Wu; Lijun, Guo; Aimei, Liu

    2007-08-01

    Based on the Fick's diffusion equations, the distribution function of refractive index of a gradient refractive index ball lens (GRIN ball lens/GBL) is derived. Lithium containing silicate glass is fabricated and GRIN ball lenses (GBLs) which diameters are from 0.3 mm to 3.0 mm are made by the method of combination of Ion exchanging and sagging in sodium nitrate. Refractive index profiles of these GBLs are measured by interferometer, and the performances such as effective focal length (EFL), back focal length (BFL) and numerical aperture (NA) between GBLs and homogeneous ball lenses (HBLs) are compared. Results show that the distribution of the index of refraction is parabolic curve and its ? n is about 0.0002, the performances of the former are super to the latter.

  11. A Fresnel reflection-based optical fiber sensor system for remote refractive index measurement using an OTDR

    NASA Astrophysics Data System (ADS)

    Yuan, Jianying; Zhao, Chunliu; Ye, Manping; Kang, Juan; Zhang, Zaixuan; Jin, Shangzhong

    2014-03-01

    In this paper, we propose a Fresnel reflection-based optical fiber sensor system for remote refractive index measurement using the optical time domain reflectometry technique as an interrogation method. The surrounding refractive index from a long distance away can be measured easily by using this sensor system, which operates based on testing the Fresnel reflection intensity from the fiber-sample interface. This system is a simple configuration, which is easy to handle. Experimental results showed that the range of this measurement could reach about 100.8 km, and the refractive index sensitivities were from 38.71 dB/RIU to 304.89 dB/RIU in the refractive index (RI) range from 1.3486 to 1.4525.

  12. Water density and polarizability deduced from the refractive index determined by interferometric measurements up to 250 MPa

    NASA Astrophysics Data System (ADS)

    Weiss, L.; Tazibt, A.; Tidu, A.; Aillerie, M.

    2012-03-01

    The refractive index of water is precisely determined in the visible light range as a function of the pressure until 250 MPa by means of a new measurement device that uses a special pipe tee included in an interferometer set. This technique allows revisiting the Bradley-Tait and Sellmeier equations to make them dependent on the wavelength and the pressure, respectively. The Bradley-Tait equation for the pressure dependence of the water refractive index is completed by a wavelength-dependent factor. Also, in the considered pressure and wavelength ranges, it is shown that the Sellmeier coefficients can be straightforwardly linked to the pressure, allowing the determination of the refractive index of water for either any wavelength or pressure. A new simple model allows the determination of the density of water as a function of the measured refractive index. Finally, the polarizability of water as function of pressure and wavelength is calculated by means of the Lorentz-Lorenz equation.

  13. A Simple Accurate Alternative to the Minimum-Deviation Method for the Determination of the Refractive Index of a Prism.

    ERIC Educational Resources Information Center

    Waldenstrom, S.; Naqvi, K. Razi

    1978-01-01

    Proposes an alternative to the classical minimum-deviation method for determining the refractive index of a prism. This new "fixed angle of incidence method" may find applications in research. (Author/GA)

  14. Synthesis of multifunctional plasmonic nanopillar array using soft thermal nanoimprint lithography for highly sensitive refractive index sensing.

    PubMed

    Yang, Sheng-Chieh; Hou, Ji-Ling; Finn, Andreas; Kumar, Amit; Ge, Yang; Fischer, Wolf-Joachim

    2015-03-19

    A low-cost plasmonic nanopillar array was synthesized using soft thermal nanoimprint lithography, and its sensitivity was determined through far-field spectroscopic measurements. Its transmission spectrum was highly dependent on the refractive index of the surrounding medium, with its sensitivity being 375 nm per refractive index unit according to the spectral shift. Moreover, a simple sensor whose reflected color changed with a change in the plasma frequency on varying the surrounding medium was fabricated. PMID:25757066

  15. OPTICAL FIBRES: Photoinduced absorption and refractive-index induction in phosphosilicate fibres by radiation at 193 nm

    Microsoft Academic Search

    A. A. Rybaltovsky; V. O. Sokolov; V. G. Plotnichenko; Aleksei V. Lanin; S. L. Semenov; A. N. Gur'yanov; V. F. Khopin; Evgenii M. Dianov

    2007-01-01

    The photoinduced room-temperature-stable increase in the refractive index by ~5×10-4 at a wavelength of 1.55 mum was observed in phosphosilicate fibres without their preliminary loading with molecular hydrogen. It is shown that irradiation of preliminary hydrogen-loaded fibres by an ArF laser at 193 nm enhances the efficiency of refractive-index induction by an order of magnitude. The induced-absorption spectra of preforms

  16. Study of the dynamics of transformation of point defects in phosphosilicate fibres by the induced refraction index

    SciTech Connect

    Larionov, Yu V; Rybaltovsky, A A; Semenov, S L [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation); Kurzanov, M A; Obidin, Aleksei Z; Vartapetov, Sergei K [Physics Instrumentation Center, A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Troitsk, Moscow Region (Russian Federation)

    2003-10-31

    A method for studying the dynamics of transformation of defects in optical fibres, exposed to UV radiation, by the dose dependence of the induced refractive index is proposed. The processes of transformation of defects in a low-loss phosphosilicate fibre, loaded with molecular hydrogen, irradiated at the 193-nm wavelength are investigated using this method. It is assumed that such a fibre has at least two types of defects, responsible for the induction of the refractive index. (optical fibres)

  17. Miscibility of ethyl cellulose/copolyamide6/66/1010 blends by viscometry and refractive index method

    NASA Astrophysics Data System (ADS)

    Zhang, Xiuzhen; Shen, Yuhua; Xie, Anjian; Gao, Sulian; Xing, Zhiying

    2011-04-01

    The miscibility of ethyl cellulose (EC)/copolyamide6/66/1010 (PA-130) in formic acid is studied by viscometry and refractive index techniques at 25°C. Using viscosity data, the criteria ? b, ? b', ?[?]m, interaction parameter ?, ? and thermodynamic parameter ? are calculated. These investigations indicate that blend of EC/PA-130 is miscible when the ethyl cellulose content is more than 50 wt % in the blend. Further the result was also confirmed by refractive index measurements.

  18. Performance analysis simulation of new SPR microstructured D-type optical fiber sensor configurations for refractive index measurement

    NASA Astrophysics Data System (ADS)

    Santos, D. F.; Guerreiro, A.; Baptista, J. M.

    2014-05-01

    This paper presents the performance analysis of two new sensing configurations of refractive index based on surface plasmon resonance (SPR) in microstructured D-type optical fiber with a thin gold layer using simulations obtained with COMSOL Multiphysics. The configurations are analyzed in terms of the intensity of the electric field. The results are compared with a conventional SPR D-type optical fiber sensor for refractive index measurement.

  19. The Cryogenic, High-Accuracy, Refraction Measuring System (CHARMS): A New Facility for Cryogenic Infrared through Vacuum Far-Ultraviolet Refractive Index Measurements

    NASA Technical Reports Server (NTRS)

    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.

  20. Infrared Spectra, Index of Refraction, and Optical Constants of Nitrile Ices Relevant to Titan's Atmosphere

    NASA Technical Reports Server (NTRS)

    Moore, Marla; Ferrante, Robert; Moore, William; Hudson, Reggie

    2010-01-01

    Spectra and optical constants of nitrite ices known or suspected to be in Titan's atmosphere are presented from 2.5 to 200 microns (4000 to 50 per cm ). These results are relevant to the ongoing modeling of Cassini CIRS observations of Titan's winter pole. Ices studied include: HCN, hydrogen cyanide; C2N2, cyanogen; CH3CN, acetonitrile; C 2H5CN, propionitrile; and HC3N, cyanoacetylene. For each of these molecules we report new measurements of the index of refraction, n, determined in both the amorphous- and crystallinephase at 670 nm. Spectra were measured and optical constants were calculated for each nitrite at a variety of temperatures including 20, 35, 50, 75, 95, and 110 K, in the amorphous- and crystalline-phase. This laboratory effort uses a dedicated FTIR spectrometer to record transmission spectra of thin-film ice samples. Laser interference is used to measure film thickness during condensation onto a transparent cold window attached to the tail section of a closed-cycle helium cryostat. Optical constants, real (n) and imaginary (k) refractive indices, are determined using Kramers-Kronig (K-K) analysis. Our calculation reproduces the complete spectrum, including all interference effects. Index of refraction measurements are made in a separate dedicated FTIR spectrometer where interference deposit fringes are measured using two 670 nm lasers at different angles to the ice substrate. A survey of these new measurements will be presented along with a discussion of their validation, errors, and application to Titan data.

  1. Thickness and refractive index of DPPC and DPPE monolayers by multiple-beam interferometry.

    PubMed

    Kienle, Daniel F; de Souza, João V; Watkins, Erik B; Kuhl, Tonya L

    2014-07-01

    The thickness and refractive index of 1,2-dipalmitoyl-sn-glycero-3-phosphatidyl choline (DPPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) monolayers Langmuir--Blodgett (LB) deposited on mica were measured in dry air and bulk water using multiple-beam interferometry (MBI). Measurements of thickness using atomic force microscopy (AFM) of identical monolayers, and X-ray reflectivity (XRR) of the monolayers on quartz were taken for comparison. The measurement of the properties of solid-supported monolayers in dry air allows lipid optical properties to be determined free from solvent effects. The thickness and refractive index measured by MBI were 25.5?±?0.6 Å and 1.485?±?0.007 for DPPE monolayers, and 23.9?±?0.5 Å and 1.478?±?0.006 for DPPC monolayers in dry air. These thicknesses are consistent with the other techniques used in this work as well as other measurements in the literature. The refractive indices of solid-supported lipid monolayers have not been previously measured. The values are higher than previous measurements on black lipid films done by reflectometry, which is attributed to increased lipid packing density and the absence of hydrocarbon solvents. Applying water to the monolayers had no measurable effect on their properties, indicating that any change in hydration was below detection. PMID:24842403

  2. Three-layered metallodielectric nanoshells: plausible meta-atoms for metamaterials with isotropic negative refractive index at visible wavelengths.

    PubMed

    Wu, DaJian; Jiang, ShuMin; Cheng, Ying; Liu, XiaoJun

    2013-01-14

    A three-layered Ag-low-permittivity (LP)-high-permittivity (HP) nanoshell is proposed as a plausible meta-atom for building the three-dimensional isotropic negative refractive index metamaterials (NIMs). The overlap between the electric and magnetic responses of Ag-LP-HP nanoshell can be realized by designing the geometry of the particle, which can lead to the negative electric and magnetic polarizabilities. Then, the negative refractive index is found in the random arrangement of Ag-LP-HP nanoshells. Especially, the modulation of the middle LP layer can move the negative refractive index range into the visible region. Because the responses arise from the each meta-atom, the metamaterial is intrinsically isotropic and polarization independent. It is further found with the increase of the LP layer thickness that the negative refractive index range of the random arrangement shows a large blue-shift and becomes narrow. With the decrease of the filling fraction, the negative refractive index range shows a blue-shift and becomes narrow while the maximum of the negative refractive index decreases. PMID:23389001

  3. Air cavity-based Fabry-Perot interferometer sensor fabricated using a sawing technique for refractive index measurement

    NASA Astrophysics Data System (ADS)

    Jung, Eun Joo; Lee, Woo-Jin; Kim, Myoung Jin; Hwang, Sung Hwan; Rho, Byung Sup

    2014-01-01

    We have demonstrated a refractive index sensor based on a fiber optic Fabry-Perot (FP) interferometer with an open air cavity fabricated using a one-step mechanical sawing technique. The sensor head consists of a short FP cavity near the fiber patch cord tip, which was assembled by joining a ceramic ferrule and a single-mode fiber together. Owing to the open air cavity in the sensor head, various liquid samples with different refractive index can fill in-line air cavity, which makes the device usable as a refractometer. Moreover, due to the sensor head encircled with the robust ceramic ferrule, the device is attractive for sensing measurement in harsh environments. The sensor was tested in different refractive index solutions. The experimental result shows that the attenuation peak wavelength of the sensor is shifted toward a shorter wavelength with increasing refractive index, and the refractive index sensitivity is ˜92.5 nm/refractive index unit (RIU) and 73.75 dB/RIU. The proposed sensor can be used as an in-line refractometer for many potential applications in the sensing field.

  4. Pressure Sensing in High-Refractive-Index Liquids Using Long-Period Gratings Nanocoated with Silicon Nitride

    PubMed Central

    Smietana, Mateusz; Bock, Wojtek J.; Mikulic, Predrag; Chen, Jiahua

    2010-01-01

    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 ? = 1,550 nm), but is also the thinnest (<100 nm) able to tune the external-refractive-index sensitivity of the gratings. To the best of our knowledge, this is the first time a nanocoating has been applied on LPGs that is able to simultaneously tune the refractive-index sensitivity and to enable measurements of other parameters. PMID:22163527

  5. Analysis of the refractive index change of optical waveguide in LiNbO3 using a femtosecond laser

    NASA Astrophysics Data System (ADS)

    Yang, Shi-han; Zhang, Liang; Lin, Xue-song; Feng, Jie; Zhou, Zi-gang; Chen, Jang-jun

    2014-11-01

    We used a commercially available 75 MHz regeneratively amplified laser system emitting 50 femtosecond pulses of energies up to 3nJ at a wavelength of 800 nm. All waveguides were fabricated by focussing the femotsecond pulse train polarised parallel to the x-axis to a distance of approximately 125 ?m below the sample surface using a 0.65 NA, ×40 microscope objective and translating the sample along the y axis. To find the optimum waveguide fabrication parameters the translation speed was varied from 2 to 100 ?m/s. We introduces a method of measuring the refractive index of optical waveguide in ten micrometer. Useing CCD to measure the two-dimensional near-field light intensity distribution of the output cross-section of the waveguide, by measuring the two-dimensional near-field light intensity distribution of the output cross-section of the waveguide can be calculated the two-dimensional distribution of refractive index of waveguides. The context detailedly gives measurement results about femtosecond laser inducing the near-field intensity of lithium niobate optical waveguide cross-section and calculations of refractive index of optical waveguide. The results show that the refractive index of waveguides showed a large central, gradually reduce and the change of refractive index in the range of 0.001. This method is of great significance to measure the optical waveguide refractive index distribution.

  6. Material Structure of a Graded Refractive Index Lens in Decapod Squid

    NASA Astrophysics Data System (ADS)

    Cai, Jing; Heiney, Paul; Sweeney, Alison

    2013-03-01

    Underwater vision with a camera-type eye that is simultaneously acute and sensitive requires a spherical lens with a graded distribution of refractive index. Squids have this type of lens, and our previous work has shown that its optical properties are likely achieved with radially variable densities of a single protein with multiple isoforms. Here we measure the spatial organization of this novel protein material in concentric layers of the lens and use these data to suggest possible mechanisms of self-assembly of the proteins into a graded refractive index structure. First, we performed small angle x-ray scattering (SAXS) to study how the protein is spatially organized. Then, molecular dynamic simulation allowed us to correlate structure to the possible dynamics of the system in different regions of the lens. The combination of simulation and SAXS data in this system revealed the likely protein-protein interactions, resulting material structure and its relationship to the observed and variable optical properties of this graded index system. We believe insights into the material properties of the squid lens system will inform the invention of self-assembling graded index devices.

  7. Fabrication Quality Analysis of a Fiber Optic Refractive Index Sensor Created by CO2 Laser Machining

    PubMed Central

    Chen, Chien-Hsing; Yeh, Bo-Kuan; Tang, Jaw-Luen; Wu, Wei-Te

    2013-01-01

    This study investigates the CO2 laser-stripped partial cladding of silica-based optic fibers with a core diameter of 400 ?m, which enables them to sense the refractive index of the surrounding environment. However, inappropriate treatments during the machining process can generate a number of defects in the optic fiber sensors. Therefore, the quality of optic fiber sensors fabricated using CO2 laser machining must be analyzed. The results show that analysis of the fiber core size after machining can provide preliminary defect detection, and qualitative analysis of the optical transmission defects can be used to identify imperfections that are difficult to observe through size analysis. To more precisely and quantitatively detect fabrication defects, we included a tensile test and numerical aperture measurements in this study. After a series of quality inspections, we proposed improvements to the existing CO2 laser machining parameters, namely, a vertical scanning pathway, 4 W of power, and a feed rate of 9.45 cm/s. Using these improved parameters, we created optical fiber sensors with a core diameter of approximately 400 ?m, no obvious optical transmission defects, a numerical aperture of 0.52 ± 0.019, a 0.886 Weibull modulus, and a 1.186 Weibull-shaped parameter. Finally, we used the optical fiber sensor fabricated using the improved parameters to measure the refractive indices of various solutions. The results show that a refractive-index resolution of 1.8 × 10?4 RIU (linear fitting R2 = 0.954) was achieved for sucrose solutions with refractive indices ranging between 1.333 and 1.383. We also adopted the particle plasmon resonance sensing scheme using the fabricated optical fibers. The results provided additional information, specifically, a superior sensor resolution of 5.73 × 10?5 RIU, and greater linearity at R2 = 0.999. PMID:23535636

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

    NASA Astrophysics Data System (ADS)

    Lehtikangas, O.; Tarvainen, T.; Kim, A. D.; Arridge, S. R.

    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.

  9. Refractive index sensing with Fano resonant plasmonic nanostructures: a symmetry based nonlinear approach

    NASA Astrophysics Data System (ADS)

    Butet, Jérémy; Martin, Olivier J. F.

    2014-11-01

    Sensing using surface plasmon resonances is one of the most promising practical applications of plasmonic nanostructures and Fano resonances allow achieving a lower detection limit thanks to their narrow spectral features. However, a narrow spectral width of the subradiant mode in a plasmonic system, as observed in the weak coupling regime, is in general associated with a low modulation of the complete spectral response. In this article, we show that this limitation can be overcome by a nonlinear approach based on second harmonic generation and its dependence on symmetry at the nanoscale. The Fano resonant systems considered in this work are gold nanodolmens. Their linear and nonlinear responses are evaluated using a surface integral equation method. The numerical results demonstrate that a variation of the refractive index of the surrounding medium modifies the coupling between the dark and bright modes, resulting in a modification of the electromagnetic wave scattered at the second harmonic wavelength, especially the symmetry of the nonlinear emission. Reciprocally, we show that evaluating the asymmetry of the nonlinear emission provides a direct measurement of the gold nanodolmens dielectric environment. Interestingly, the influence of the refractive index of the surrounding medium on the nonlinear asymmetry parameter is approximately 10 times stronger than on the spectral position of the surface plasmon resonance: hence, smaller refractive index changes can be detected with this new approach. Practical details for an experimental realization of this sensing scheme are discussed and the resolution is estimated to be as low as ?n = 1.5 × 10-3, respectively 1.5 × 10-5, for an acquisition time of 60 s for an isolated gold nanodolmen, respectively an array of 10 × 10 nanodolmens.Sensing using surface plasmon resonances is one of the most promising practical applications of plasmonic nanostructures and Fano resonances allow achieving a lower detection limit thanks to their narrow spectral features. However, a narrow spectral width of the subradiant mode in a plasmonic system, as observed in the weak coupling regime, is in general associated with a low modulation of the complete spectral response. In this article, we show that this limitation can be overcome by a nonlinear approach based on second harmonic generation and its dependence on symmetry at the nanoscale. The Fano resonant systems considered in this work are gold nanodolmens. Their linear and nonlinear responses are evaluated using a surface integral equation method. The numerical results demonstrate that a variation of the refractive index of the surrounding medium modifies the coupling between the dark and bright modes, resulting in a modification of the electromagnetic wave scattered at the second harmonic wavelength, especially the symmetry of the nonlinear emission. Reciprocally, we show that evaluating the asymmetry of the nonlinear emission provides a direct measurement of the gold nanodolmens dielectric environment. Interestingly, the influence of the refractive index of the surrounding medium on the nonlinear asymmetry parameter is approximately 10 times stronger than on the spectral position of the surface plasmon resonance: hence, smaller refractive index changes can be detected with this new approach. Practical details for an experimental realization of this sensing scheme are discussed and the resolution is estimated to be as low as ?n = 1.5 × 10-3, respectively 1.5 × 10-5, for an acquisition time of 60 s for an isolated gold nanodolmen, respectively an array of 10 × 10 nanodolmens. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr05623j

  10. Refractive index of planktonic cells as a measure of cellular carbon and chlorophyll a content

    NASA Astrophysics Data System (ADS)

    Stramski, Dariusz

    1999-02-01

    Current methods for determining carbon content in individual planktonic cells from particle volume alone may involve large errors, and no routine technique exists for determining chlorophyll a content in individual phytoplankters. In this study the concept of using the refractive index of cells as a measure of intracellular concentrations of carbon and chlorophyll a is discussed. Specifically, the real part of the refractive index n (at light wavelengths where absorption is negligible or very small) is shown to correlate well with the intracellular concentration of carbon, Ci. The imaginary part of the refractive index n' (in the red band of chlorophyll a) correlates well with the intracellular chlorophyll concentration, Chl i. These relationships were found to be nearly identical for two species, a cyanobacterium Synechococcus and a diatom Thalassiosira pseudonana, over a two-fold range in Ci and Chl i. This range was associated with interspecies differences and intraspecies variations in the cell properties over a day-night cycle. These observations and the underlying theoretical considerations suggest that the relationships Ci vs. n and Chl i vs. n' may be robust and hold for a variety of planktonic species regardless of interspecies and intraspecies variability in cellular carbon content, Chl a content, and cell size. In addition, these relationships may be applicable to single-particle analysis of natural water samples, which promises a unique capability to acquire information about the distribution of carbon and chlorophyll a among individual cells, different size classes, and taxonomic groups of planktonic microorganisms in the ocean. Further research with various planktonic species is needed to examine the generality of the relationships Ci vs. n and Chl i vs. n' before the approach can be implemented in field studies.

  11. Higher-order nonlinearity of refractive index: the case of argon.

    PubMed

    Tarazkar, Maryam; Romanov, Dmitri A; Levis, Robert J

    2014-06-01

    The nonlinear coefficients, n4, of the time-dependent refractive index for argon are calculated in the non-resonant optical regime. Second-order polynomial fitting of DC-Kerr, ?((2))(-?; ?, 0, 0), electric field induced second harmonic generation (ESHG), ?((2))(-2?; ?, ?, 0), and static second-order hyperpolarizability, ?((2))(0; 0, 0, 0), is performed using an auxiliary electric field approach to obtain the corresponding fourth-order optical properties. A number of basis sets are investigated for the fourth-order hyperpolarizability processes at 800 nm at coupled cluster singles and doubles level of theory, starting with the t-aug-cc-pV5Z basis set and expanding that basis set by adding diffuse functions and polarization functions. Comparison shows that the results obtained with the t-aug-cc-pV5Z basis are in very good agreement with the results obtained using the q-aug-cc-pV5Z, t-aug-cc-pV6Z, and q-aug-cc-pV6Z basis sets. To calculate the nonlinear refractive index n4, an approximate formula is suggested which expresses the related degenerate six-wave mixing coefficient, ?((4))(-?; ?, -?, ?, -?, ?), in terms of the DC-Kerr, ?((4))(-?; ?, 0, 0, 0, 0), ESHG, ?((4))(-2?; ?, ?, 0, 0, 0), and the static fourth-order hyperpolarizability coefficients. The higher-order nonlinear refractive index n4 is found to be positive over the wavelengths 300 nm-2000 nm. In the infrared spectral range, the obtained values of n4 are in qualitative agreement with the results of Kramers-Kronig-based calculations. PMID:24908017

  12. Measurement of the nonlinear refractive index of tellurite glass fiber by using induced grating autocorrelation technique

    NASA Astrophysics Data System (ADS)

    Traore, Aboubakar

    Nonlinear phenomena in optical fibers have been attracting considerable attention because of the rapid growth of the fiber optics communication industry. The increasing demand in internet use and the expansion of telecommunications in the developing world have triggered the need for high capacity and ultra-fast communication devices and also the need to increase the number of transmission channels in the fibers. Wavelength Division Multiplexing (WDM) and Dense Wavelength Division Multiplexing (DWDM) systems are capable of transmitting large volumes of data at very high rates into huge numbers of optical transmission channels. This ability is limited by the gain bandwidth of Silica based fiber optics amplifiers already installed in the communication networks. Tellurite based fiber amplifiers offer the necessary bandwidth for amplification of WDM and DWDM channels. To investigate the nonlinear properties of the optical fibers in this research, we used a 10 picoseconds pulse width passively mode-locked Nd:Vanadate ( Nd:YVO4) laser operating at 1342nm with a repetition rate of 76 MHz. We accurately measured the nonlinear refractive index of single mode silica fibers utilizing the Induced Grating Autocorrelation (IGA) technique. IGA technique was extended furthermore to study nonlinear effects in multimode fibers, and for the first time, we successfully measured the nonlinear refractive index (n2) of a multimode silica fiber. Confident of the ability of IGA technique for determining n 2 of multimode silica fibers, we measured the nonlinear refractive index of multimode Tellurite glass fibers with length as short as 0.5 meter. The goal of this work is to provide accurate and reliable information on the nonlinear optical properties of Tellurite glass fibers, novel fibers with promising future for developing ultrafast and high transmission capacity communication devices.

  13. Swift and heavy ion implanted chalcogenide laser glass waveguides and their different refractive index distributions.

    PubMed

    Qiu, Feng; Narusawa, Tadashi; Zheng, Jie

    2011-02-10

    Planar waveguides have been fabricated in Nd- or Ho-doped gallium lanthanum sulfide laser glasses by 60?MeV Ar or 20?MeV N ion implantation. The refractive index profiles were reconstructed based on the results of prism coupling. The Ar implanted waveguides exhibit an approximate steplike distribution, while the N implanted ones show a "well + barrier" type. This difference can be attributed to the much lower dose of Ar ions. After annealing, the N implanted waveguides can support two modes at 1539?nm and have low propagation loss, which makes them candidates for novel waveguide lasers. PMID:21343996

  14. Calculation of the profile of turbulent inhomogeneities of the air refraction index

    NASA Astrophysics Data System (ADS)

    Shikhovtsev, A. Yu.; Kovadlo, P. G.

    2014-11-01

    The results of investigations of vertical profile of turbulent inhomogeneities of the air refractive index using NCEP / NCAR Reanalysis data are discussed in this paper. Model used for calculations is based on the spectral features of atmospheric turbulence characteristics in a wide range of scales. The differences of the shapes of small-scale atmospheric turbulence spectra in the free atmosphere and the boundary layer are in the focus of the paper. The obtained results may allow us to estimate characteristics of turbulent and, thus, parameters of adaptive optics systems.

  15. Highly birefringent suspended-core photonic microcells for refractive-index sensing

    NASA Astrophysics Data System (ADS)

    Wang, Chao; Jin, Wa; Liao, Changrui; Ma, Jun; Jin, Wei; Yang, Fan; Ho, Hoi Lut; Wang, Yiping

    2014-08-01

    An in-line photonic microcell with a highly birefringent suspended microfiber core is fabricated by locally heating and pressurizing selected air-holes of an endless single mode photonic crystal fiber. The microfiber core has rhombus-like cross-sectional geometry and could achieve a high birefringence of up to 10-2. The microfiber core is fixed at the center of the microcell by thin struts attached to an outer jacket tube, which protects and isolates the microfiber from environmental contaminations. Highly sensitive and robust refractive index sensors based on such microcells are experimentally demonstrated.

  16. Measurement of the nonlinear refractive index of materials with a single pulse

    NASA Astrophysics Data System (ADS)

    Mohebi, Mehrdad; Jamasbi, Nooshin; Ruiz de la Cruz, Alexandro

    1999-07-01

    We present a single shot method of measurement of the nonlinear refractive index of materials. In this method a single laser pulse is used in a setup similar to the Z-scan technique. It is therefore as simple and sensitive as the z- scan. In this method unlike the Z-scan, the sample is fixed with respect to the lens while the focus position is scanned across the sample (F-scan). The far field transmission of the beam through an aperture is then measured. This method eliminates the need to move the sample in addition to the measurement error due to peak power fluctuations from pulse to pulse.

  17. Discrimination of glass sources using elemental composition and refractive index: development of predictive models.

    PubMed

    Almirall, J R; Cole, M D; Gettinby, G; Furton, K G

    1998-01-01

    Refractive index and metal ion concentrations (Al, Ba, Ca, Fe, Mg, Mn, Sr, Ti and Zr) were determined for four product-use categories: headlamp glass; container glass, non-vehicle window float glass, and vehicle float glass. Linear discriminant modelling using these data allowed differentiation of the four glass types but further discrimination was not possible within a product-use category. For this specific set of glasses, the concentrations of a number of metal ions were found to be correlated in some cases. This precluded the use of traditional probability calculations in using elemental composition data for interpretation of glass evidence. Alternative approaches to glass data interpretation are suggested. PMID:9624818

  18. Significant correlation between refractive index and activity of mitochondria: single mitochondrion study.

    PubMed

    Haseda, Keisuke; Kanematsu, Keita; Noguchi, Keiichi; Saito, Hiromu; Umeda, Norihiro; Ohta, Yoshihiro

    2015-03-01

    Measurements of refractive indices (RIs) of intracellular components can provide useful information on the structure and function of cells. The present study reports, for the first time, determination of the RI of an isolated mitochondrion in isotonic solution using retardation-modulated differential interference contrast microscopy. The value was 1.41 ± 0.01, indicating that mitochondria are densely packed with molecules having high RIs. Further, the RIs of each mitochondrion were significantly correlated with the mitochondrial membrane potential, an index of mitochondrial activity. These results will provide useful information on the structures and functions of cells based on the intracellular distribution of RIs. PMID:25798310

  19. A Hybrid LPG/CFBG for Highly Sensitive Refractive Index Measurements

    PubMed Central

    Sun, An; Wu, Zhishen

    2012-01-01

    A simple and high sensitive method employing a hybrid long period grating (LPG)/chirped fiber Bragg grating (CFBG) for refractive index (RI) measurements is proposed and investigated experimentally. The wide wavelength range of backward cladding modes are excited through the coupling and recoupling between LPG and CFBG. Experimental results indicate that the recoupled cladding modes between LPG and CFBG and core mode are modulated by the surrounding RI and highly sensitive RI measurements can be achieved by simply measuring the reflected intensity changes of the recoupled cladding modes and core mode. PMID:22969347

  20. Design and optimization of liquid core optical ring resonator for refractive index sensing

    NASA Astrophysics Data System (ADS)

    Lin, Nai; Jiang, Lan; Wang, Sumei; Xiao, Hai; Lu, Yongfeng; Tsai, Hai-Lung

    2011-07-01

    This study performs a detailed theoretical analysis of refractive index (RI) sensors based on whispering gallery modes (WGMs) in liquid core optical ring resonators (LCORRs). Both TE- and TM-polarized WGMs of various orders are considered. The analysis shows that WGMs of higher orders need thicker walls to achieve a near-zero thermal drift, but WGMs of different orders exhibit a similar RI sensing performance at the thermostable wall thicknesses. The RI detection limit is very low at the thermostable thickness. The theoretical predications should provide a general guidance in the development of LCORR-based thermostable RI sensors.

  1. Design and optimization of liquid core optical ring resonator for refractive index sensing.

    PubMed

    Lin, Nai; Jiang, Lan; Wang, Sumei; Xiao, Hai; Lu, Yongfeng; Tsai, Hai-Lung

    2011-07-10

    This study performs a detailed theoretical analysis of refractive index (RI) sensors based on whispering gallery modes (WGMs) in liquid core optical ring resonators (LCORRs). Both TE- and TM-polarized WGMs of various orders are considered. The analysis shows that WGMs of higher orders need thicker walls to achieve a near-zero thermal drift, but WGMs of different orders exhibit a similar RI sensing performance at the thermostable wall thicknesses. The RI detection limit is very low at the thermostable thickness. The theoretical predications should provide a general guidance in the development of LCORR-based thermostable RI sensors. PMID:21743574

  2. Negative refractive index material-inspired 90-deg electrically tilted ultra wideband resonator

    NASA Astrophysics Data System (ADS)

    Upadhyaya, Trushit K.; Kosta, Shiv Prasad; Jyoti, Rajeev; Palandoken, Merih

    2014-10-01

    A negative refractive index material loaded patch antenna is proposed for ultra wideband applications. The wideband operation has been achieved by creating a defected ground plane with a CNC shaped split ring resonator. The defected ground plane CNC resonator also exhibits a 90-deg electrical tilt. Two additional slots are engineered in the patch antenna for further bandwidth enhancement. A -10 dB bandwidth with an order of 57.89% has been achieved with a peak gain of 5.37 dBi at a 5.5 GHz resonant frequency. Measured results demonstrate good agreement with simulated results.

  3. Causality-based criteria for a negative refractive index must be used with care

    E-print Network

    Kinsler, P; 10.1103/PhysRevLett.101.167401

    2008-01-01

    Using the principle of causality as expressed in the Kramers-Kronig relations, we derive a generalized criterion for a negative refractive index that admits imperfect transparency at an observation frequency $\\omega$. It also allows us to relate the global properties of the loss (i.e. its frequency response) to its local behaviour at $\\omega$. However, causality-based criteria rely the on the group velocity, not the Poynting vector. Since the two are not equivalent, we provide some simple examples to compare the two criteria.

  4. Significant correlation between refractive index and activity of mitochondria: single mitochondrion study

    PubMed Central

    Haseda, Keisuke; Kanematsu, Keita; Noguchi, Keiichi; Saito, Hiromu; Umeda, Norihiro; Ohta, Yoshihiro

    2015-01-01

    Measurements of refractive indices (RIs) of intracellular components can provide useful information on the structure and function of cells. The present study reports, for the first time, determination of the RI of an isolated mitochondrion in isotonic solution using retardation-modulated differential interference contrast microscopy. The value was 1.41 ± 0.01, indicating that mitochondria are densely packed with molecules having high RIs. Further, the RIs of each mitochondrion were significantly correlated with the mitochondrial membrane potential, an index of mitochondrial activity. These results will provide useful information on the structures and functions of cells based on the intracellular distribution of RIs. PMID:25798310

  5. Propagation of acoustic waves in a metamaterial with a refractive index of near zero

    NASA Astrophysics Data System (ADS)

    Park, Choon Mahn; Lee, Sang Hun

    2013-06-01

    A metamaterial system with a refractive index of near zero for acoustic wave is realized. The designed system, which uses Helmholtz resonators, is analyzed using the equivalent circuit theory. Through the simulation and the experiment, we observed a large phase velocity in the metamaterial and a concentration of the energy density in the narrow normal waveguide directly coupled to the metamaterial. This is different to the metamaterial for the electromagnetic wave, because the concentration of energy density of the electromagnetic wave occurs in the metamaterial inside. The acoustic metamaterial system can be applied to the development of device for the acoustic energy concentrator and the acoustic filter.

  6. Refractive index sensor based on an abrupt taper Michelson interferometer in a single-mode fiber

    Microsoft Academic Search

    Zhaobing Tian; Scott S.-H. Yam; Hans-Peter Loock

    2008-01-01

    A simple refractive index sensor based on a Michelson interferometer in\\u000a a single-mode fiber is constructed and demonstrated. The sensor consists\\u000a of a single symmetrically abrupt taper region in a short piece of\\u000a single-mode fiber that is terminated by similar to 500 nm thick gold\\u000a coating. The sensitivity of the new sensor is similar to that of a\\u000a long-period-grating-type sensor,

  7. Corrections to refractive index data of stoichiometric lithium tantalate in the 5-6 microm range.

    PubMed

    Kolev, V Z; Duering, M W; Luther-Davies, B

    2006-07-01

    We propose corrections to the coefficients in the published Sellmeier equation for stoichiometric LiTaO3 [Opt. Lett.28, 194 (2003)] that allow the extension of the wavelength range within the region of midinfrared absorption edge up to 6 microm. The required extraordinary refractive index data for this range were obtained using single-pass optical parametric fluorescence measurements with a pump wavelength of 1064.4 nm. We also observed efficient parasitic second-harmonic generation that could affect some quasi-phase-matching interactions. The corrected Sellmeier equation improves the accuracy of poling period calculations where the idler wavelength is within the region. PMID:16770423

  8. Corrections to refractive index data of stoichiometric lithium tantalate in the 5-6 ?m range

    NASA Astrophysics Data System (ADS)

    Kolev, V. Z.; Duering, M. W.; Luther-Davies, B.

    2006-07-01

    We propose corrections to the coefficients in the published Sellmeier equation for stoichiometric LiTaO3 [Opt. Lett.28, 194 (2003)] that allow the extension of the wavelength range within the region of midinfrared absorption edge up to 6 ?m. The required extraordinary refractive index data for this range were obtained using single-pass optical parametric fluorescence measurements with a pump wavelength of 1064.4nm. We also observed efficient parasitic second-harmonic generation that could affect some quasi-phase-matching interactions. The corrected Sellmeier equation improves the accuracy of poling period calculations where the idler wavelength is within the region.

  9. Random Estimate the values of seed oil of Cucurbita maxima by refractive index method.

    PubMed

    Saxena, R B

    2010-01-01

    The crude oil having lower iodine and free fatty acids values has Aamdosha properties. These properties are present due to toxic and anti-toxic compounds. These compounds can be harmful for the special diseases and may be unsaturated, saturated, open chain etc. The adulteration can take part as catalytic action for the toxic effect for the special diseases. Toxic properties of oils are removed by different ingrediants and methods. C. maxima seed tail (mst) is used with food and medicine. The present paper deals with the study of oil by refractive index and equations. PMID:22131677

  10. Estimation of the refractive index structure characteristic of air from coherent Doppler wind lidar data.

    PubMed

    Banakh, V A; Smalikho, I N; Rahm, S

    2014-08-01

    A technique is proposed for estimating the refractive index structure characteristic of air from data of a coherent Doppler wind lidar. The proposed technique is tested in atmospheric experiments. Time profiles of the structure characteristic in the atmospheric surface layer are obtained and compared with the time profiles of the dissipation rate of the kinetic energy of turbulence obtained from the same lidar data. It is shown in this way that coherent lidars can be used for investigating not only wind turbulence, but also temperature turbulence. PMID:25078167

  11. Unidirectional acoustic transmission through a prism with near-zero refractive index

    NASA Astrophysics Data System (ADS)

    Li, Yong; Liang, Bin; Gu, Zhong-ming; Zou, Xin-ye; Cheng, Jian-chun

    2013-07-01

    We propose a two-dimensional model of acoustic prism comprising metamaterials with near-zero refractive index to yield high efficiency unidirectional transmission and demonstrate an implementation by coiling up space. Due to the acoustic tunneling effect, the waveform is kept consistent between input and output waves, and the transmitted angle can be controlled by reshaping the prism, even in the presence of hard scatterer. A directional waveguide is also designed whose transmission property can be freely switched between all possible states. Our design may have potential for practical applications of acoustic one-way devices in various fields such as ultrasound imaging and treatment.

  12. Refractive index measured by laser beam displacement at {lambda}=1064 nm for solvents and deuterated solvents

    SciTech Connect

    Shelton, David P.

    2011-07-20

    The refractive index of a liquid is determined with 0.0003 accuracy from measurements of laser beam displacement by a liquid-filled standard 10 mm spectrophotometer cell. The apparatus and methods are described and the results of measurements at {lambda}=1064 nm and T=25.0 deg. C for 30 solvents and deuterated solvents are presented. Several sources of potential systematic errors as large as 0.003 are identified, the most important being the curvature of the liquid cell windows. The measurements are analyzed accounting for the significant imperfections of the apparatus.

  13. Enhancing the efficiency of slow-wave electron cyclotron masers with the tapered refractive index

    SciTech Connect

    Kong Lingbao; Hou Zhiling; Jing Jian [School of Science and Beijing Key Laboratory of Environmentally Harmful Chemicals Assessment, Beijing University of Chemical Technology, Beijing 100029 (China); Jin Haibo [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Du Chaohai [Institute of Electronics, Chinese Academy of Sciences, Beijing 100190 (China)

    2013-04-15

    The nonlinear analysis of slow-wave electron cyclotron masers (ECM) based on anomalous Doppler effect in a slab waveguide is presented. A method of tapered refractive index (TRI) is proposed to enhance the efficiency of slow-wave ECM. The numerical calculations show that the TRI method can significantly enhance the efficiency of slow-wave ECM with the frequency ranging from the microwave to terahertz band. The effect of beam velocity spread on the efficiency has also been studied. Although the velocity spread suppresses the efficiency significantly, a great enhancement of efficiency can still be introduced by the TRI method.

  14. Improvement in refractive index sensitivity by means of internally curved long period fiber gratings

    NASA Astrophysics Data System (ADS)

    Chiavaioli, F.; Trono, C.; Baldini, F.

    2014-05-01

    A novel configuration of long period fiber grating (LPFG), based on a specially designed refractive index (RI) profile, was manufactured and studied. The internally manufactured geometric structure is characterized by grating planes tilted at increasing angles, as moving away from the center of symmetry of the structure towards its both edges. This structure reproduces the bending of an optical fiber and improves the RI sensitivity of an LPG to the external surrounding medium. A three-fold enhancement in the RI sensitivity was experimentally proved, thus giving a further contribution towards the development of more sensitive RI sensors based on optical fiber LPGs.

  15. Specially designed long period grating with internal geometric bending for enhanced refractive index sensitivity

    NASA Astrophysics Data System (ADS)

    Chiavaioli, F.; Trono, C.; Baldini, F.

    2013-06-01

    We propose a long period grating (LPG) characterized by specially designed refractive index (RI) profile in which each grating plane is tilted at increasing angles, as moving away from the center of symmetry of the structure towards its both edges. This internally manufactured geometric structure, which basically simulates the bending of an optical fiber, increases the RI sensitivity of an LPG to the external medium. We experimentally demonstrate a three-fold improvement in the RI sensitivity, thus providing the basis for another step forward in the field of RI sensors based on optical fiber gratings.

  16. Enhancing the efficiency of slow-wave electron cyclotron masers with the tapered refractive index

    NASA Astrophysics Data System (ADS)

    Kong, Ling-Bao; Hou, Zhi-Ling; Jing, Jian; Jin, Hai-Bo; Du, Chao-Hai

    2013-04-01

    The nonlinear analysis of slow-wave electron cyclotron masers (ECM) based on anomalous Doppler effect in a slab waveguide is presented. A method of tapered refractive index (TRI) is proposed to enhance the efficiency of slow-wave ECM. The numerical calculations show that the TRI method can significantly enhance the efficiency of slow-wave ECM with the frequency ranging from the microwave to terahertz band. The effect of beam velocity spread on the efficiency has also been studied. Although the velocity spread suppresses the efficiency significantly, a great enhancement of efficiency can still be introduced by the TRI method.

  17. Highly sensitive fiber refractive index sensor based on side-core holey structure

    NASA Astrophysics Data System (ADS)

    Han, Ya; Xia, Li; Liu, De-Ming

    2014-10-01

    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.

  18. Swift and heavy ion implanted chalcogenide laser glass waveguides and their different refractive index distributions

    SciTech Connect

    Qiu Feng; Narusawa, Tadashi; Zheng Jie

    2011-02-10

    Planar waveguides have been fabricated in Nd- or Ho-doped gallium lanthanum sulfide laser glasses by 60 MeV Ar or 20 MeV N ion implantation. The refractive index profiles were reconstructed based on the results of prism coupling. The Ar implanted waveguides exhibit an approximate steplike distribution, while the N implanted ones show a ''well + barrier'' type. This difference can be attributed to the much lower dose of Ar ions. After annealing, the N implanted waveguides can support two modes at 1539 nm and have low propagation loss, which makes them candidates for novel waveguide lasers.

  19. Determining the refractive index and thickness of thin films from prism coupler measurements

    NASA Technical Reports Server (NTRS)

    Kirsch, S. T.

    1981-01-01

    A simple method of determining thin film parameters from mode indices measured using a prism coupler is described. The problem is reduced to doing two least squares straight line fits through measured mode indices vs effective mode number. The slope and y intercept of the line are simply related to the thickness and refractive index of film, respectively. The approach takes into account the correlation between as well as the uncertainty in the individual measurements from all sources of error to give precise error tolerances on the best fit values. Due to the precision of the tolerances, anisotropic films can be identified and characterized.

  20. Spatiotemporal collapse in a nonlinear waveguide with a randomly fluctuating refractive index.

    PubMed

    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

  1. Highly birefringent suspended-core photonic microcells for refractive-index sensing

    SciTech Connect

    Wang, Chao [Department of Electrical Engineering, The Hong Kong Polytechnic University, Hong Kong (China); The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen 518057 (China); Jin, Wa; Ma, Jun; Jin, Wei, E-mail: eewjin@polyu.edu.hk; Yang, Fan; Ho, Hoi Lut [Department of Electrical Engineering, The Hong Kong Polytechnic University, Hong Kong (China); Liao, Changrui; Wang, Yiping [Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education/Guangdong Province, Shenzhen University, Shenzhen 518060 (China)

    2014-08-11

    An in-line photonic microcell with a highly birefringent suspended microfiber core is fabricated by locally heating and pressurizing selected air-holes of an endless single mode photonic crystal fiber. The microfiber core has rhombus-like cross-sectional geometry and could achieve a high birefringence of up to 10{sup ?2}. The microfiber core is fixed at the center of the microcell by thin struts attached to an outer jacket tube, which protects and isolates the microfiber from environmental contaminations. Highly sensitive and robust refractive index sensors based on such microcells are experimentally demonstrated.

  2. Development of a single crystal with a high index of refraction

    NASA Astrophysics Data System (ADS)

    Kurosawa, Shunsuke; Kochurikhin, Vladimir V.; Yamaji, Akihiro; Yokota, Yuui; Kubo, Hidetoshi; Tanimori, Toru; Yoshikawa, Akira

    2013-12-01

    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 (?-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±1 ns and 10±2 ns, respectively, using a photomultiplier tube (Hamamatsu R6231-100). Cherenkov light of the GGG crystal could be observed for the gamma-ray irradiation.

  3. Rapid assessment of mid-infrared refractive index anisotropy using a prism coupler: chemical vapor deposited ZnS

    SciTech Connect

    Qiao, Hong (Amy) [Amy; Lipschultz, Kristen A.; Anheier, Norman C.; McCloy, John S.

    2012-04-01

    A state-of-the-art mid-infrared prism coupler was used to study the refractive index properties of forward-looking-infrared (FLIR) grade zinc sulfide samples prepared with unique planar grain orientations and locations with respect to the CVD growth axis. This study was motivated by prior photoluminescence and x-ray diffraction measurements that suggested refractive index may vary according to grain orientation. Measurements were conducted to provide optical dispersion and thermal index (dn/dT) data at discrete laser wavelengths between 0.633 and 10.591 {mu}m at two temperature set points (30 C and 90 C). Refractive index measurements between samples exhibited an average standard deviation comparable to the uncertainty of the prism coupler measurement (0.0004 refractive index units), suggesting that the variation in refractive index as a function of planar grain orientation and CVD deposition time is negligible, and should have no impact on subsequent optical designs. Measured dispersion data at mid-infrared wavelengths was found to agree well with prior published measurements.

  4. Detection of refractive index changes in chemical reactions of fluids within micro channels using digital holographic microscopy

    NASA Astrophysics Data System (ADS)

    Nasehi, Adel; Moradi Mehr, Shiva; Moradi, Ali-Reza

    2013-11-01

    Digital holographic microscopy (DHM) provides a non-destructive measurement technique based on calculation of optical path length changes of the sample under study. If the changes are caused by refractive index variations within a constant physical thickness, the technique results in the precise measurement of the refractive index . In this paper, DHM is utilized to map the refractive index over a wide surface of a T-shaped micro channel. The micro channel is filled up by a solution of two chemical reactant fluids. In some chemical reactions the refractive index of the resultant may be highly different from the refractive indices of the reactants. Using microinjection pumps methane and water as reactants are injected into the channel at the same flow rates. Changes in optical path ways are measured by live recording the digital holograms during the fluids interaction for all the field of view pixels. The holograms are recorded by a detector and post processed by a computer in order to reconstruct the phase profile changes though angular spectrum propagation method. The changes in the refractive indices that take place during the reaction process, are viewed by the detector and are calculated and mapped for the T channel and Y channel.

  5. Measurements of the imaginary part of the refractive index between 300 and 700 nanometers for Mount St. Helens ash

    SciTech Connect

    Patterson, E.M.

    1981-01-01

    The absorption properties, expressed as a wavelength-dependent imaginary index of refraction, of the Mount St. Helens ash from the 18 May 1980 eruption were measured between 300 and 700 nanometers by diffuse reflectance techniques. The measurements were made for both surface and stratospheric samples. The stratospheric samples show imaginary index values that decrease from approximately 0.01 to 0.02 at 300 nanometers to about 0.0015 at 700 nanometers. The surface samples show less wavelength variation in imaginary refractive index over this spectral range.

  6. High refractive index contrast in a photosensitive polymer and waveguide photo-printing demonstration

    NASA Astrophysics Data System (ADS)

    Bosc, Dominique; Grosso, Philippe; Hardy, Isabelle; Assa??d, Imane; Batté, Thomas; Haesaert, Séverine; Vinouze, Bruno

    2004-05-01

    In this paper, the realisation and performances of a photo-printed waveguide in an intrinsically photosensitive polymer film have been demonstrated. One of the advantages of this technique, is the reduced number of process steps. In this polymer (polyvinylcinnamate), local UV irradiation yields a lowering of refractive index. Using this polymer, the photo-induced index contrast in a film is significantly improved from 1.5 × 10 -2 (previous works) up to 2.5 × 10 -2 at 1550 nm. This is one of the highest contrast value reported for a photo-printed non-birefringent waveguide. Concerning optical transmission properties, first promising results have been obtained. Optical measurements in the polymer film (0.25 dB/cm at 1550 nm) and in polymer solution (less than 0.2 dB/cm at telecommunication wavelengths) have shown the high potentiality of this material.

  7. Nonlinear refractive index measurements and self-action effects in Roselle-Hibiscus Sabdariffa solutions

    NASA Astrophysics Data System (ADS)

    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.

  8. Reflectivity enhanced refractive index sensor based on a fiber-integrated Fabry-Perot microresonator.

    PubMed

    Wieduwilt, T; Dellith, J; Talkenberg, F; Bartelt, H; Schmidt, M A

    2014-10-20

    We discuss a fiber-integrated refractive index sensor with strongly improved detection performance. The resonator has been implemented by means of focused-ion beam milling of a step index fiber and shows a sensitivity of about 1.15µm/RIU. Coating the resonator walls led to a strongly improved mirror reflectivity by a factor of about 26. Design rules for device optimization and a detailed mathematical analysis are discussed, revealing that the sensor operates as an optimized Fabry-Perot resonator. We also show that the performance of such kind of Fabry-Perot sensors is, in general, limited by the detection limit function - a quantity depending on the cavitiy's finesse and on the measurement capabilities used. PMID:25401567

  9. Computational determination of refractive index distribution in the crystalline cones of the compound eye of Antarctic krill (Euphausia superba).

    PubMed

    Gál, József; Miyazaki, Taeko; Meyer-Rochow, Victor Benno

    2007-01-21

    In order to understand how a compound eye channels light to the retina and forms an image, one needs to know the refractive index distribution in the crystalline cones. Direct measurements of the refractive indices require sections of fresh, unfixed tissue and the use of an interference microscope, but frequently neither is available. Using the eye of the Antarctic krill Euphausia superba (the main food of baleen whales) we developed a computational method to predict a likely refractive index distribution non-invasively from sections of fixed material without the need of an interference microscope. We used a computer model of the eye and calculated the most realistic spatial distribution of the refractive index gradient in the crystalline cone that would enable the eye to produce a sharp image on the retina. The animals are known to see well and on the basis of our computations we predict that for the eyes of the adult a maximum refractive index of 1.45-1.50 in the centre of the cone yields a better angular sensitivity and light absorption in a target receptor of the retina than if N(max) were 1.55. In juveniles with a narrower spatial separation between dioptric structures and retina, however, an N(max) of 1.50-1.55 gives a superior result. Our method to determine the most likely refractive index distribution in the cone without the need of fresh material and an interference microscope could be useful in the study of other invertebrate eyes that are known to possess good resolving power, but for a variety of reasons are not suitable for or will not permit direct refractive index measurements of their dioptric tissues to be taken. PMID:16989868

  10. Fabrication of Refractive Index Tunable Polydimethylsiloxane Photonic Crystal for Biosensor Application

    NASA Astrophysics Data System (ADS)

    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.

  11. Float genetic algorithm for determination of particle size distribution and refractive index in polarized LSS

    NASA Astrophysics Data System (ADS)

    Deng, Yong; Hu, Rui; Luo, Qingming; Lu, Qiang

    2005-04-01

    Polarized light scattering spectroscopy (LSS) is sensitive to the cell nuclear morphological changes in the various forms of epithelial dysplasia. Extensive studies illustrate it is a promising in situ technique to detect precancerous and early cancerous changes in the epithelial tissue. To determine the density and size distribution of cell nuclei with spectra, generally, Mie theory-based inverse model is adopted. This model is of multiple parameters, multiple extreme values and nonlinear. The determination of all unknown parameters needs to solve a nonlinear inverse problem. Other than least-square fitting used by previous studies, in this paper, we developed a novel method - float genetic algorithm (FGA) to determine the particle size distribution and refractive index for LSS. Our results showed that, relative errors of three estimated statistical quantities: diameter, standard deviation and refractive index are less than 5% for different additive Gauss noise levels with 70 iteration epochs. The errors gradually decrease with iteration epoch increases. Moreover, comparing with Newton-type iteration method coupled with a Marquardt-Tikhanov regularization scheme, FGA avoids the problems of local extreme value and selection of initial value and regularization parameters, thus obtains the advantages of high precision, stability and robustness.

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

    NASA Astrophysics Data System (ADS)

    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.

  13. Sensitivity enhancement in photonic crystal waveguide platform for refractive index sensing applications

    NASA Astrophysics Data System (ADS)

    Dutta, Hemant Sankar; Goyal, Amit Kumar; Pal, Suchandan

    2014-01-01

    A photonic crystal (PhC) waveguide platform based on ring-shaped holes in a silicon-on-insulator substrate is proposed in order to realize a refractive index sensor with an improved sensitivity. The three-dimensional finite-difference time domain method is used to analyze the proposed design. The sensitivity is estimated by measuring the shift in the upper band-edge of the output transmission spectrum. Sensitivity analysis of a conventionally designed PhC waveguide, followed by modification of the structure, has been carried out for improving the sensitivity by introducing a row of holes that forms the line defect. Further improvement in sensitivity is obtained by replacing the defect row of holes by ring-shaped holes, which shows a significantly high sensitivity along with considerable output signal strength. The optimized design shows a wavelength shift of 210 nm for a change in ambient refractive index from air (RI=1) to xylene (RI=1.5), corresponding to an average sensitivity of 420 nm/RIU.

  14. Electric field induced optical absorption and refractive index changes in a diluted magnetic quantum well

    NASA Astrophysics Data System (ADS)

    Leonora, J. Merciline; Peter, A. John; Yoo, ChangKyoo

    2013-01-01

    Binding energy of a confined exciton is investigated in a CdMnTe/CdMnTe/CdMnTe diluted magnetic quantum well in the influence of electric field. Calculations are performed for various Mn incorporation in Cd1-xMnxTe material within a single band effective mass approximation using variational method. Spin polaronic shifts are estimated using mean field theory for different Mn concentration and the well sizes. A theoretical study of diluted magnetic semiconductors treating local sp-d exchange interaction J between the itinerant carriers and the Mn electrons is treated within a realistic band structure. The optical absorption and the refractive index changes as a function of normalized photon energy in the presence of electric field strength and the Mn ion content are analysed. Our results show that the occurred red shift of the absorption resonant peak due to the electric field gives the information about the variation of two energy levels in the quantum well. The optical absorption coefficients and the refractive index changes strongly depend on the incident optical intensity, the electric field strength and Mn content.

  15. Preparation of nearly monodisperse multiply coated submicrospheres with a high refractive index.

    PubMed

    Li, Qunyan; Dong, Peng

    2003-05-15

    Nearly monodisperse SiO2/TiO2/SiO2 multiply coated submicrospheres with nearly monodisperse silica submicrospheres as cores, thick titania layers, and thin silica skin were prepared to increase the refractive index of complex submicrospheres while keeping their near monodispersity and perfect surface properties. Nearly monodisperse colloidal silica submicrospheres as cores with a diameter of 200 nm were synthesized by a seeding technique on the basis of the hydrolysis of tetraethyl orthosilicate (TEOS) in an aqueous ethanol solution with ammonia as catalyst. On the basis of the hydrolysis of tetrabutyl orthotitanate, a procedure combining continuous feeding with multistep coating was determined to prepare titania coatings about 40 nm thick and increase the refractive index of the complex submicrospheres. The hydrolysis of TEOS was still used to get the outmost silica coating about 10 nm thick on titania coated silica submicrospheres to eliminate random aggregation caused by the TiO2 surface properties of the TiO2/SiO2 complex submicrospheres during the final fabrication of photonic crystals. PMID:16256538

  16. Light sheet microscopy of cleared mouse brains: aberrations effects caused by refractive index mismatch

    NASA Astrophysics Data System (ADS)

    Silvestri, Ludovico; Sacconi, Leonardo; Pavone, Francesco S.

    2013-06-01

    Fluorescence light sheet microscopy has known a true renaissance in the last years. In fact, since optical sectioning is achieved in a wide-field detection scheme, this technique allows high resolution three-dimensional imaging with high frame rate. Light sheet microscopy is therefore an ideal candidate for reconstructing macroscopic specimens with micron resolution: coupled with clearing protocols based on refractive index matching it has been exploited to image entire mouse brains without physical sectioning. Use of clearing protocols poses several challenges to light sheet microscopy. First of all, residual light scattering inside the tissue expands the excitation light sheet, leading to the excitation of out-of-focus planes, and thus frustrating the very principle of light sheet illumination. To reject out-of-focus contributions we recently coupled light sheet illumination with confocal detection, achieving significant contrast enhancement in real time. Another issue which often arises when working with clearing agents is the refractive index mismatch between the clearing and the medium objective design medium. This introduces severe spherical aberration, which leads to broadening of the point spread function and to a strong reduction in its peak value: When imaging deep (several mm) inside macroscopic specimens, the signal can be reduced by more than an order of magnitude. We investigated the possibility of correcting such spherical aberration by introducing extra optical devices in the detection path.

  17. Controlling band gap and refractive index in dopant-free ?-Fe2O3 films

    NASA Astrophysics Data System (ADS)

    Kumar, Pawan; Rawat, Nitin; Hang, Da-Ren; Lee, Heung-No; Kumar, Rajesh

    2015-01-01

    Dopant-free hematite (a-Fe2O3) films are formed at a liquid-vapor interface by means of an easy method in order to control the band gap and refractive index of the films. The a-Fe2O3 films after being transferred to a glass substrate are studied for their structural and optical properties. Control over the thickness of the films in the range from 75 to 400 nm and the constituent nanocrystallite size from 3 to 46 nm is achieved by controlling the synthesis parameters. By controlling the film thickness, crystallite size, and crystallinity of dopant-free a-Fe2O3 films, the optical band gap is increased significantly (by ? 0.64 eV) from 2.30 to 2.94 eV, along with increase in the refractive index from 1.35 to 2.8. The observed increase in the optical band gap is explained on the basis of change in lattice symmetry (via change in the c/a ratio) of a-Fe2O3 crystallites.

  18. Extraction of light trapped due to total internal reflection using porous high refractive index nanoparticle films

    NASA Astrophysics Data System (ADS)

    Mao, Peng; Sun, Fangfang; Yao, Hanchao; Chen, Jing; Zhao, Bo; Xie, Bo; Han, Min; Wang, Guanghou

    2014-06-01

    TiO2 nanoparticle layers composed of columnar TiO2 nanoparticle piles separated with nanoscale pores were fabricated on the bottom surface of the hemispherical glass prism by performing gas phase cluster beam deposition at glancing incidence. The porosity as well as the refractive index of the nanoparticle layer was precisely tuned by the incident angle. Effective extraction of the light trapped in the substrate due to total internal reflection with the TiO2 nanoparticle layers was demonstrated and the extraction efficiency was found to increase with the porosity. An enhanced Rayleigh scattering mechanism, which results from the columnar aggregation of the nanoparticles as well as the strong contrast in the refractive index between pores and TiO2 nanoparticles in the nanoporous structures, was proposed. The porous TiO2 nanoparticle coatings were fabricated on the surface of GaN LEDs to enhance their light output. A nearly 92% PL enhancement as well as a 30% EL enhancement was observed. For LED applications, the enhanced light extraction with the TiO2 nanoparticle porous layers can be a supplement to the microscale texturing process for light extraction enhancement.

  19. Extraction of light trapped due to total internal reflection using porous high refractive index nanoparticle films.

    PubMed

    Mao, Peng; Sun, Fangfang; Yao, Hanchao; Chen, Jing; Zhao, Bo; Xie, Bo; Han, Min; Wang, Guanghou

    2014-07-21

    TiO? nanoparticle layers composed of columnar TiO? nanoparticle piles separated with nanoscale pores were fabricated on the bottom surface of the hemispherical glass prism by performing gas phase cluster beam deposition at glancing incidence. The porosity as well as the refractive index of the nanoparticle layer was precisely tuned by the incident angle. Effective extraction of the light trapped in the substrate due to total internal reflection with the TiO? nanoparticle layers was demonstrated and the extraction efficiency was found to increase with the porosity. An enhanced Rayleigh scattering mechanism, which results from the columnar aggregation of the nanoparticles as well as the strong contrast in the refractive index between pores and TiO? nanoparticles in the nanoporous structures, was proposed. The porous TiO? nanoparticle coatings were fabricated on the surface of GaN LEDs to enhance their light output. A nearly 92% PL enhancement as well as a 30% EL enhancement was observed. For LED applications, the enhanced light extraction with the TiO? nanoparticle porous layers can be a supplement to the microscale texturing process for light extraction enhancement. PMID:24927071

  20. Simultaneous measurement of refractive index and temperature based on intensity demodulation using matching grating method

    NASA Astrophysics Data System (ADS)

    Qi, Liang; Zhao, Chun-Liu; Kang, Juan; Jin, Yongxing; Wang, Jianfeng; Ye, Manping; Jin, Shangzhong

    2013-07-01

    A solution refractive index (SRI) and temperature simultaneous measurement sensor with intensity-demodulation system based on matching grating method were demonstrated. Long period grating written in a photonic crystal fiber (LPG-PCF), provides temperature stable and wavelength dependent optical intensity transmission. The reflective peaks of two fiber Bragg gratings (FBGs), one of which is etched then sensitive to both SRI and temperature, another (FBG2) is only sensitive to temperature, were located in the same linear range of the LPG-PCF's transmission spectrum. An identical FBG with FBG2 was chosen as a matching FBG. When environments (SRI and temperature) change, the wavelength shifts of the FBGs are translated effectively to the reflection intensity changes. By monitoring output lights of unmatching and matching paths, the SRI and temperature were deduced by a signal processing unit. Experimental results show that the simultaneous refractive index and temperature measurement system work well. The proposed sensor system is compact and suitable for in situ applications at lower cost.

  1. Air etalon facilitated simultaneous measurement of group refractive index and thickness using spectral interferometry.

    PubMed

    Zhang, Ke; Tao, Li; Cheng, Wenkai; Liu, Jianhua; Chen, Zhongping

    2014-11-01

    A simple method based on air etalons of a transparent cavity is proposed to simultaneously measure the group refractive index and thickness of a transparent optical plate by spectral domain low coherence interferometry. In this method, only a single beam path is needed in contrast to the two beam paths, the reference and sample arms, of the conventional Michelson interferometer. An empty cavity is first constructed in the beam path by two glass plates. Then the transparent plate under test is inserted into the cavity, so that two air gaps are formed in the cavity. A beam of light of low coherence length is then transmitted through the cavity in the normal direction. Measurements of the reflected waves by the air gaps before and after the sample plate is put into the cavity allow us to determine the group refractive index (ng) and thickness (d) of the sample simultaneously. The relative precision of the results for d and ng are both approximately 7×10-4. PMID:25402915

  2. Low-loss multilayered metamaterial exhibiting a negative index of refraction at visible wavelengths

    NASA Astrophysics Data System (ADS)

    Garcia-Meca, Carlos

    2012-02-01

    Over the last decade, metamaterials have attracted a great interest thanks to their potential to expand the range of electromagnetic properties found in natural materials. In particular, the possibility of achieving negative refractive index media (NIM) enables us to implement superlenses and optical storing devices. Since the first experimental demonstration at microwave frequencies, much effort has been put in extending negative refraction to the visible spectrum, where we can take full advantage of NIM properties. For instance, the superior imaging ability of NIM would be essential for visible microscopy. The desired features for NIM are low loss and isotropy. This last property includes polarization independence and negative-index behavior in all spatial directions. None of these features have been attained in previous experiments. Thus, the current challenge is to improve such aspects in order to make NIM suitable for practical applications. In this work, we experimentally demonstrate a low-loss multilayer metamaterial exhibiting a double-negative index in the visible spectrum, while presenting polarization independence at normal incidence. This has been achieved by exploiting the properties of a second-order magnetic resonance of the so-called fishnet structure, in contrast to previous works that used first-order magnetic resonances, both related to gap surface plasmon polariton (SPP) modes. The low-loss nature of the employed magnetic resonance, together with the effect of the interacting adjacent layers, results in a figure of merit as high as 3.34. A wide spectral range of negative index is achieved, covering the wavelength region between 620 and 806 nm with only two different designs. The fabricated metamaterials are the first experimental multilayer NIM in the visible spectrum, which entails an important step towards homogeneous NIM in this range. Finally, we found that the SPP modes determining the permeability resonance display weak angular dispersion.

  3. Strong ion migration in high refractive index contrast waveguides formed by femtosecond laser pulses in phosphate glass

    NASA Astrophysics Data System (ADS)

    Hoyo, J.; Sotillo, Belen; Hernandez, M.; Toney Fernandez, T.; Haro-González, Patricia; Jaque, D.; Fernandez, P.; Domingo, C.; Siegel, J.; Solis, J.

    2014-05-01

    Strong ion migration in shown to enable the production of high refractive index contrast waveguides by fs-laser writing in a commercial (Er,Yb)-doped phosphate based glass. Waveguide writing was performed using a high repetition rate fslaser fibre amplifier operated at 500 kHz and the slit shaping technique. Based on measurements of the NA of waveguides, the positive refractive index change (?n) of the guiding region has been estimated to be ˜1-2 x10-2. The compositional maps of the waveguides cross-sections performed by X-ray microanalysis evidenced a large increase of the La local concentration in the guiding region up to ~25% (relative to the non-irradiated material). This large enrichment in La was accompanied by the cross migration of K to a neighbouring low refractive index zone. The refractive index of the La-phosphate glass increases linearly with the La2O3 content (?n per mole fraction increase of La2O3 ? 5x10-3) mainly because of the relative mass of the La3+ ions. The density increase without substantial modification of the glass network was confirmed by space-resolved micro-Raman spectroscopy measurements showing minor variations in the (PO2)sym vibration Raman band. These results provide evidence for the feasibility of adapting the glass composition for enabling laser-writing of high refractive index contrast structures via spatially selective modification of the glass composition.

  4. Enhanced vibrational spectroscopy, intracellular refractive indexing for label-free biosensing and bioimaging by multiband plasmonic-antenna array.

    PubMed

    Chen, Cheng-Kuang; Chang, Ming-Hsuan; Wu, Hsieh-Ting; Lee, Yao-Chang; Yen, Ta-Jen

    2014-10-15

    In this study, we report a multiband plasmonic-antenna array that bridges optical biosensing and intracellular bioimaging without requiring a labeling process or coupler. First, a compact plasmonic-antenna array is designed exhibiting a bandwidth of several octaves for use in both multi-band plasmonic resonance-enhanced vibrational spectroscopy and refractive index probing. Second, a single-element plasmonic antenna can be used as a multifunctional sensing pixel that enables mapping the distribution of targets in thin films and biological specimens by enhancing the signals of vibrational signatures and sensing the refractive index contrast. Finally, using the fabricated plasmonic-antenna array yielded reliable intracellular observation was demonstrated from the vibrational signatures and intracellular refractive index contrast requiring neither labeling nor a coupler. These unique features enable the plasmonic-antenna array to function in a label-free manner, facilitating bio-sensing and imaging development. PMID:24836017

  5. Implementation of transformed lenses in bed of nails reducing refractive index maximum value and sub-unity regions.

    PubMed

    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

  6. Nonlinear intersubband absorption and refractive index change in n-type ?-doped GaAs for different donor distributions

    NASA Astrophysics Data System (ADS)

    Ozturk, Emine

    2015-01-01

    In this study, both the linear and nonlinear intersubband optical absorption coefficients and the refractive index changes are calculated for the uniform, triangular and Gaussian-like donor distribution. The Gaussian-like distribution differs from the Gaussian distribution other authors use. The electronic structure of n-type Si ?-doped GaAs has been theoretically calculated by solving the Schrödinger and Poisson equations self-consistently. Our results show that the location and the size of the linear and total absorption coefficients and refractive index changes depend on the donor distribution type. The shape of ?-effective potential profile and the subband properties are changed as dependent on the donor distribution model. Therefore, the variation of the absorption coefficients and refraction index changes, which can be appropriate for various optical modulators and infrared optical device applications can be smooth obtained by the alteration donor distribution model.

  7. Experimental analysis of distributed pump absorption and refractive index changes in Yb-doped fibers using acousto-optic interaction.

    PubMed

    Alcusa-Sáez, E P; Díez, A; Andrés, M V

    2015-03-01

    In-fiber acousto-optic interaction is used to characterize the refractive index changes at the C band in a single-mode ytterbium-doped optical fiber under 980 nm pumping. The transmission notch created by the acoustic-induced coupling between the core mode and a cladding mode shifts to longer wavelengths when the pump is delivered to the fiber. The electronic contribution to the refractive index change is quantified from the wavelength shift. Using a time-resolved acousto-optic method, we investigate the distribution of pump absorption, and the resulting refractive index change profile, along sections of ytterbium-doped fiber exceeding 1 m long under different pump power levels. PMID:25723408

  8. Characterization of a novel ultra low refractive index material for biosensor application

    PubMed Central

    Memisevic, Jasenka; Korampally, Venumadhav; Gangopadhyay, Shubhra; Grant, Sheila A.

    2009-01-01

    Nanoporous materials can provide significant benefits to the field of biosensors. Their size and porous structure makes them an ideal tool for improving sensor performance. This study characterized a novel ultra low index of refraction nanoporous organosilicate (NPO) material for use as an optical platform for fluorescence-based optical biosensors. While serving as the low index cladding material, the novel coating based on organosilicate nanoparticles also provides an opportunity for a high surface area coating that can be utilized for immobilizing biological probes. Biological molecules were immobilized onto NPO, which was spin-coated on silicon and glass substrates. The biological molecule was composed of Protein A conjugated to AlexaFluor 546 fluorophore and then immobilized onto the NPO substrate via silanization. Sample analysis consisted of spectrofluorometry, FT-IR spectroscopy, scanning electron microscopy, contact angle measurement and ellipsometry. The results showed the presence of emission peaks at 574 nm, indicating that the immobilization of Protein A to the NPO material is possible. When compared to Si and glass substrates not coated with NPO, the results showed a 100X and 10X increase in packing density with the NPO coated films respectively. Ellipsometric analysis, FT-IR, contact angle, and SEM imaging of the surface immobilized NPO films suggested that while the surface modifications did induce some damage, it did not incur significant changes to its unique characteristics, i.e., pore structure, wettability and index of refraction. It was concluded that NPO films would be a viable sensor substrate to enhance sensitivity and improve sensor performance. PMID:20161155

  9. Practical application of the refracted near-field technique for the measurement of optical fibre refractive index profiles

    Microsoft Academic Search

    K. I. White

    1979-01-01

    Both the theoretical basis and experimental realization of the refracted near-field technique for the direct measurement of optical fibre profiles are presented. The technique requires minimal sample preparation, no computation and is applicable to both single and multimode fibres. Both the core and the cladding are profiled. After outlining the problems associated with other techniques, the use of this method

  10. Combined Use of Satellite and Surface Observations to Infer the Imaginary Part of Refractive Index of Saharan Dust

    NASA Technical Reports Server (NTRS)

    Sinyuk, Alexander; Torres, Omar; Dubovik, Oleg; Bhartia, P. K. (Technical Monitor)

    2002-01-01

    We present a method for retrieval of the imaginary part of refractive index of desert dust aerosol in the near UV part of spectrum. The method uses Total Ozone Mapping Spectrometer (TOMS) measurements of the top of the atmosphere radiances at 331 and 360 run and aerosol optical depth provided by the Aerosol Robotic Network (AERONET). Obtained values of imaginary part of refractive index retrieved for Saharan dust aerosol at 360 nm are significantly lower than previously reported values. The average retrieved values vary between 0.0054 and 0.0066 for different geographical locations. Our findings are in good agreement with the results of several recent investigations.

  11. Interference color modulation, tunable refractive index, and chiroptical electrochromism in a ?-conjugated polymer with cholesteric liquid crystal order

    NASA Astrophysics Data System (ADS)

    Goto, Hiromasa

    2009-06-01

    A ?-conjugated polymer film prepared by electrolytic polymerization using a cholesteric liquid crystal (CLC) is demonstrated to have a tunable interference function under electrochemical doping and dedoping. The polymer exhibits a CLC-like periodic structure with a potential-dependent refractive index and optical absorption properties. The interference color of the polymer film can thus be modulated dynamically by appropriate application of a voltage in the ±1 V range. This research involves structural chirality and tunable chiroptical properties, doping-dedoping driven tunable refractive index, electrochromism, and interference color modulation for the present polymer. The phenomena demonstrate the possibility of electrochemical photonics.

  12. X-ray-refractive-index measurements at photon energies above 100 keV with a grating interferometer

    NASA Astrophysics Data System (ADS)

    Ruiz-Yaniz, M.; Zanette, I.; Rack, A.; Weitkamp, T.; Meyer, P.; Mohr, J.; Pfeiffer, F.

    2015-03-01

    The knowledge of the x-ray index of refraction of materials is important for the interpretation or simulation of many x-ray physics phenomena. But its precise and accurate experimental determination is challenging, particularly in the hard x-ray energy range above 100 keV. In this article we present and discuss experimental measurements of the real and imaginary part of the index of refraction for different materials based on x-ray grating interferometry at energies above 130 keV.

  13. Diffractionless beam in free space with adiabatic changing refractive index in a single mode tapered slab waveguide

    PubMed Central

    Tsai, Chang-Ching; Vinegoni, Claudio; Weissleder, Ralph

    2009-01-01

    We propose a novel design to produce a free space diffractionless beam by adiabatically reducing the difference of the refractive index between the core and the cladding regions of a single mode tapered slab waveguide. To ensure only one propagating eigenmode in the adiabatic transition, the correlation of the waveguide core width and the refractive index is investigated. Under the adiabatic condition, we demonstrate that our waveguide can emit a diffractionless beam in free space up to 500 micrometers maintaining 72% of its original peak intensity. The proposed waveguide could find excellent applications for imaging purposes where an extended depth of field is required. PMID:19997414

  14. Superlensing effect for surface acoustic waves in a pillar-based phononic crystal with negative refractive index

    SciTech Connect

    Addouche, Mahmoud, E-mail: mamoud.addouche@femto-st.fr; Al-Lethawe, Mohammed A., E-mail: mohammed.abdulridha@femto-st.fr; Choujaa, Abdelkrim, E-mail: achoujaa@femto-st.fr; Khelif, Abdelkrim, E-mail: abdelkrim.khelif@femto-st.fr [Institut FEMTO-ST, Université de Franche-Comté, CNRS, 32 Avenue de l'Observatoire, 25044 Besançon Cedex (France)

    2014-07-14

    We demonstrate super resolution imaging for surface acoustic waves using a phononic structure displaying negative refractive index. This phononic structure is made of a monolithic square lattice of cylindrical pillars standing on a semi-infinite medium. The pillars act as acoustic resonator and induce a surface propagating wave with unusual dispersion. We found, under specific geometrical parameters, one propagating mode that exhibits negative refraction effect with negative effective index close to ?1. Furthermore, a flat lens with finite number of pillars is designed to allow the focusing of an acoustic point source into an image with a resolution of (?)/3 , overcoming the Rayleigh diffraction limit.

  15. Measurement of refractive-index change at a liquid-solid interface close to the critical angle.

    PubMed

    Martinelli, M; Gugliotti, M; Horowicz, R J

    2000-06-01

    We measured the refractive-index change on a liquid sample, using the reflection of a polarized Gaussian laser beam close to the angle of total reflection. We applied this technique to a solution of nickel (ii) phthalocyanine tetrasulfonated (NiPTS) in water-ethanol (1/1 v/v), in which the nonlinearity of the refractive index is due to optically induced thermal effects. We show that close to the angle of total reflection the sensitivity of this technique is four times bigger than at normal incidence. PMID:18345195

  16. Measurement of the refractive index by using a rectangular cell with a fs-laser engraved diffraction grating inner wall.

    PubMed

    Durán-Ramírez, Víctor M; Martínez-Ríos, Alejandro; Guerrero-Viramontes, J Ascención; Muñoz-Maciel, Jesús; Peña-Lecona, Francisco G; Selvas-Aguilar, Romeo; Anzueto-Sánchez, Gilberto

    2014-12-01

    A very simple method to obtain the refractive index of liquids by using a rectangular glass cell and a diffraction grating engraved by fs laser ablation on the inner face of one of the walls of the cell is presented. When a laser beam impinges normally on the diffraction grating, the diffraction orders are deviated when they pass through the cell filled with the liquid to be measured. By measuring the deviation of the diffraction orders, we can determine the refractive index of the liquid. PMID:25606919

  17. Variation of refractive index in strained In(x)Ga(1-x)As-GaAs heterostructures

    NASA Technical Reports Server (NTRS)

    Das, U.; Bhattacharya, P. K.

    1986-01-01

    In(x)Ga(1-x)As-GaAs heterostructures and strained-layer superlattices can be used as optical waveguides. For such applications it is important to know explicitly the refractive index variation with mismatch strain and with alloying in the ternary layer. Starting from the Kramers-Kronig integral dispersion relations, a model has been developed from which the refractive index change in the ternary layer of In(x)Ga(1-x)As-GaAs heterojunctions can be calculated. The results are presented and discussed. The expected changes in a superlattice have been qualitatively predicted.

  18. Stratospheric aerosol acidity, density, and refractive index deduced from SAGE 2 and NMC temperature data

    NASA Technical Reports Server (NTRS)

    Yue, G. K.; Poole, L. R.; Wang, P.-H.; Chiou, E. W.

    1994-01-01

    Water vapor concentrations obtained by the Stratospheric Aerosol and Gas Experiment 2 (SAGE 2) and collocated temperatures provided by the National Meteorological Center (NMC) from 1986 to 1990 are used to deduce seasonally and zonally averaged acidity, density, and refractive index of stratospheric aerosols. It is found that the weight percentage of sulfuric acid in the aerosols increases from about 60 just above the tropopause to about 86 at 35 km. The density increases from about 1.55 to 1.85 g/cu cm between the same altitude limits. Some seasonal variations of composition and density are evident at high latitudes. The refractive indices at 1.02, 0.694, and 0.532 micrometers increase, respectively, from about 1.425, 1.430, and 1.435 just above the tropopause to about 1.445, 1.455, and 1.458 at altitudes above 27 km, depending on the season and latitude. The aerosol properties presented can be used in models to study the effectiveness of heterogeneous chemistry, the mass loading of stratospheric aerosols, and the extinction and backscatter of aerosols at different wavelengths. Computed aerosol surface areas, rate coefficients for the heterogeneous reaction ClONO2 + H2O yields HOCl + HNO3 and aerosol mass concentrations before and after the Pinatubo eruption in June 1991 are shown as sample applications.

  19. Refractive index profile and its guided mode characteristics of ion-exchanged planar optical waveguides

    NASA Astrophysics Data System (ADS)

    Haneda, N.; Imal, M.; Ohtsuka, Y.

    1983-07-01

    The refractive index profile and the propagation characteristics of guided beam mode for planar optical waveguides fabricated with ion exchange from molten salts of silver nitrate are discussed. The pyrex glass substrate was dipped into an AgNO3 melt for a typical 3 to 9 hours at 300 C of diffusion temperature; some alkali ions are exchanged by Ag(+) ions forming a high index at the surface. The index profiles are determined by the inverse W.K.B. method based on mode spectroscopy and shown to be exponentially decreasing from the surface. The mode functions are obtained by solving the wave equation for an exponential profile and shown graphically in order to have some understanding of the mechanism producing a scattering loss. The attenuation of the sample waveguides fabricated is also measured and yields a beam loss of 2.0 to 2.5 dB/cm for TE sub 0 mode excitation. Measurements of mode conversion, mode and thickness dependent losses of the waveguide are discussed in detail. These results allow identification of the loss mechanism which depends on either the surface roughness or silver ion concentration in an ion exchanged planar optical waveguide.

  20. Wave guiding by low refractive-index strips on surfaces of Chalcogenide glass thin films

    NASA Astrophysics Data System (ADS)

    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 1.5?m 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.

  1. Tailoring the index of refraction of nanocrystalline hafnium oxide thin films

    SciTech Connect

    Vargas, Mirella [Department of Metallurgical and Materials Engineering, University of Texas at El Paso, El Paso, Texas 79968 (United States)] [Department of Metallurgical and Materials Engineering, University of Texas at El Paso, El Paso, Texas 79968 (United States); Murphy, N. R. [Materials and Manufacturing Directorate (RX), 3005 Hobson Way, Wright-Patterson Air Force Base (WPAFB), Dayton, Ohio 45433 (United States)] [Materials and Manufacturing Directorate (RX), 3005 Hobson Way, Wright-Patterson Air Force Base (WPAFB), Dayton, Ohio 45433 (United States); Ramana, C. V., E-mail: rvchintalapalle@utep.edu [Department of Mechanical Engineering, University of Texas at El Paso, El Paso, Texas 79968 (United States)

    2014-03-10

    Hafnium oxide (HfO{sub 2}) films were grown by sputter-deposition by varying the growth temperature (T{sub s}?=?25–700?°C). HfO{sub 2} films grown at T{sub s}?index of refraction (n) profiles derived from spectroscopic ellipsometry analyses follow the Cauchy dispersion relation. Lorentz-Lorenz analysis (n{sub (?)}?=?550?nm) and optical-model adopted agree well with the XRR data/analyses. A direct T{sub s}-?-n relationship suggests that tailoring the optical quality is possible by tuning T{sub s} and the microstructure of HfO{sub 2} films.

  2. Topological insulator metamaterials with tunable negative refractive index in the optical region

    PubMed Central

    2013-01-01

    A blueshift tunable metamaterial (MM) exhibiting a double-negative refractive index based on a topological insulator (bismuth selenide, Bi2Se3) has been demonstrated in the near-infrared (NIR) spectral region. The potential of Bi2Se3 as a dielectric interlayer of the multilayer MM is explored. The optical response of elliptical nanohole arrays penetrating through Au/Bi2Se3/Au films is numerically investigated using the finite difference time domain (FDTD) method. The blueshift tuning range of the MM is as high as 370 nm (from 2,140 to 1,770 nm) after switching the Bi2Se3 between its trigonal and orthorhombic states. PMID:24330596

  3. Sensitivity analysis of a photonic crystal waveguide for refraction index sensing

    NASA Astrophysics Data System (ADS)

    Bougriou, F.; Boumaza, T.; Bouchemat, M.; Paraire, N.

    2012-11-01

    Photonic crystal (PC) sensors have attracted much attention because of their inherent compactness, high sensitivity and biocompatibility traits. In this paper, we analyze the design of highly sensitive infiltrated liquid sensors based on a two-dimensional PC slab waveguide formed by increasing the radii of air holes localized on each side of the line defect and filling with homogeneous de-ionized water (nc = 1.33). The transmission spectrum of the sensor has been obtained by the finite-difference time domain method, and it has been observed that a 270 nm wavelength position of the upper band edge shift was observed corresponding to a sensitivity of more than 818 nm per refractive index unit. The simulation results on the sensitive PC structure show that the optical properties of PCs can be used to design sensing devices characterized by a high degree of compactness and good resolution.

  4. Flow Measurement in Porous Media Using Particle Tracking Velocimetry and Matching Refractive Index

    NASA Astrophysics Data System (ADS)

    Dominguez Ontiv, E.; Estrada-Perez, C.; Hassan, Y.; Mendoza-Sanchez, I.

    2005-12-01

    In this study, an experiment in a packed bed column is performed to obtain pore-scale full-field velocity components of the flow. Particle tracking velocimetry (PTV) technique is used to obtain instantaneous accurate flow fields and detailed information of the flow patterns. A refractive index matching liquid is used to provide the required transparency, so the measurements could be performed at the middle plane of the packed bed reactor. Immersion optical methods are applied to explore transfer phenomena in multiphase granular beds. In this research, P-Cymene 99% is investigated as the working fluid in a packed bed vertical square channel for the immersed method. P-cymene is chosen because of the close similarity of its physical properties to those of the water.

  5. Whistler-mode refractive index gradients in the inner magnetosphere: Themis observations

    NASA Astrophysics Data System (ADS)

    Cully, C. M.; Danko, A.

    2013-12-01

    Whistler-mode waves such as chorus and hiss can have a pronounced effect on the inner magnetosphere and radiation belts. The propagation paths followed by these waves, and hence their geophysical effect, depend on local gradients in the refractive index, and are particularly influenced by gradients in the density. Propagation has typically been considered in one of two idealized cases: either a smooth magnetosphere or a deep duct. Using Themis data, we characterize observed density gradients using simultaneous measurements from multiple closely-spaced satellites under a variety of conditions, and show that the measured gradients are often very different from these ideals. We discuss the consequences of these observed gradients on whistler-mode chorus propagation paths and geoeffectiveness.

  6. Application of matching liquid on the refractive index measurement of biotissue: A theoretical and experimental study

    NASA Astrophysics Data System (ADS)

    Wang, Jin; Ye, Qing; Deng, Zhichao; Zhou, Wenyuan; Mei, Jianchun; Zhang, Chunping; Tian, Jianguo

    2014-05-01

    The application of matching liquid on the measurement of the refractive index (RI) of biotissue using total internal reflection (TIR) method is investigated in detail. A theoretical model describing samples with different absorbing and scattering ability is given based on Fresnel formula. The theoretical calculation is verified by experimental results of three simulation samples (transparent plexiglass, white plexiglass and ZB3 glass) and cedar wood oil as the matching liquid. Reflectance curves of porcine tissue samples were recorded and systematically studied using two kinds of matching liquid (cedar wood oil and adipose oil) at the incident of TE and TM wave, respectively. Method for proper selection of matching liquid under different conditions is discussed.

  7. Elliptical-core two mode fiber sensors and devices incorporating photoinduced refractive index gratings

    NASA Technical Reports Server (NTRS)

    Greene, Jonathan A.; Miller, Mark S.; Starr, Suzanne E.; Fogg, Brian R.; Murphy, Kent A.; Claus, Richard O.; Vengsarkar, Ashish M.

    1991-01-01

    Results of experiments performed using germanium-doped, elliptical core, two-mode optical fibers whose sensitivity to strain was spatially varied through the use of chirped, refractive-index gratings permanently induced into the core using Argon-ion laser light are presented. This type of distributed sensor falls into the class of eighted-fiber sensors which, through a variety of means, weight the strain sensitivity of a fiber according to a specified spatial profile. We describe results of a weighted-fiber vibration mode filter which successfully enhances the particular vibration mode whose spatial profile corresponds to the profile of the grating chirp. We report on the high temperature survivability of such grating-based sensors and discuss the possibility of multiplexing more than one sensor within a single fiber.

  8. Effect of Refractive Index Variation on Two-Wavelength Interferometry for Fluid Measurements

    NASA Technical Reports Server (NTRS)

    Mercer, Carolyn R.

    1998-01-01

    Two wavelength interferometry can in principle be used to measure changes in both temperature and concentration in a fluid, but measurement errors may be large if the fluid dispersion is small. This paper quantifies the effects of uncertainties in dn/dT and dn/dC on the measured temperature and concentration when using the simple expression dn = (dn/dT)dT + (dn/dC)dC. For the data analyzed here, ammonium chloride in water from -5 to 10(exp infinity) C over a concentration range of 2-14% and for wavelengths 514.5 and 633 nm, it is shown that the gradients must be known to within 0.015% to produce a modest 10% uncertainty in the measured temperature and concentration. These results show that real care must be taken to ensure the accuracy of refractive index gradients when using two wavelength interferometry for the simultaneous measurement of temperature and concentration.

  9. Determination of crystalline perfection, optical indicatrix, birefringence and refractive-index homogeneity of ZTS crystals

    NASA Astrophysics Data System (ADS)

    Dinakaran, S.; Verma, Sunil; Das, S. Jerome; Bhagavannarayana, G.; Kar, S.; Bartwal, K. S.

    2011-05-01

    Single crystals of the semi-organic non-linear optical material zinc tris (thiourea) sulphate (ZTS) were grown by slow evaporation solution growth technique. The crystals were characterized for crystalline perfection and optical homogeneity using high-resolution X-ray diffraction (HRXRD) and optical interferometric techniques. The FWHM of 6 arc sec in HRXRD rocking curve shows the good crystalline quality. Transmittance of ˜75% shows that the crystal is free from volume defects. Conoscopy was used to assess the optical quality and investigate the optical indicatrix of the grown crystal. Birefringence values of the crystal along the three principal crystallographic axes were measured using birefringence interferometry. Mach-Zehnder interferograms exhibit good refractive-index homogeneity of the grown crystal.

  10. Progress Toward Development of Low-Temperature Microwave Refractive Index Gas Thermometry at NRC

    NASA Astrophysics Data System (ADS)

    Rourke, P. M. C.; Hill, K. D.

    2015-03-01

    Progress toward the development of a low-temperature microwave refractive index gas thermometry implementation for primary thermometry at NRC is reported. A prototype quasi-spherical copper resonator has been integrated into a cryogenic system with a 5 K base temperature, and preliminary microwave measurements in vacuum have been completed to characterize the resonator between 5 K and 297 K. The dependence of experimental results on spectral fitting background terms, 1st- and 2nd-order shape corrections, and waveguide corrections has also been explored. The current NRC results agree with previous room-temperature measurements on the same resonator at NIST, and indicate no significant change in resonator shape between room temperature and low temperature. The temperature dependences of the resonator electrical conductivity and linear thermal expansion coefficient, as obtained from the microwave resonances, agree with published literature values for oxygen-free high-conductivity copper measured using other techniques.

  11. High Er 3+ concentration low refractive index fluorophosphate glass for evanescent wave optical amplifiers

    NASA Astrophysics Data System (ADS)

    Zhang, Liyan; Chen, Nan-Kuang; Hu, Lili

    2008-10-01

    This is about the first reported laser glass with very low nD, high Er 3+ concentration and no quenching. In this work, a series of high Er 3+ concentration (10.6-12.2×10 20 ions/cm 3), low refractive index ( n1550<1.47) and relatively high fluorescence lifetime (6.8-12.6 ms) fluorophosphate glasses were made. A cw-pumping evanescent wave optical amplifier experiment was performed with it, and a relative gain of around 2 dB at 1550 nm wavelength was achieved while the noise level was almost unchanged. To our knowledge, this is the first successful relative gain in evanescent wave optical amplifiers (EWOA) demonstrated with cw pumping. It is a valuable study of specially designed fluorophosphate glass suitable for EWOA communication experiment.

  12. Evolution of polarization in an atomic vapour with negative refractive index

    NASA Astrophysics Data System (ADS)

    Zhuang, Fei; Shen, Jianqi

    2006-08-01

    A three-level Lambda-configuration atomic vapour may exhibit simultaneously negative permittivity and permeability in the optical frequency band, and an isotropic left-handed vapour medium could therefore be realized within the framework of quantum optics. One of the most remarkable features of the present scheme is that both the refractive index and the photon helicity reversal inside the vapour can be controllably manipulated by an external coupling light field. The phenomenological Hamiltonian that describes the process of helicity reversal is constructed and the time-dependent Schrödinger equation governing the time evolution of the polarization states of the lightwave is solved by means of the Lewis-Riesenfeld invariant theory. The transition between the polarization states (and hence the accompanied photon helicity reversal), which is exactly analogous to the transition operation between bits in digital circuit, may be valuable for the development of new techniques in quantum optics and would have potential applications in information technology.

  13. Measurement of organic chemical refractive indexes using an optical time-domain reflectometer.

    PubMed

    Yeh, Chien-Hung; Chow, Chi-Wai; Sung, Jiun-Yu; Wu, Ping-Chun; Whang, Wha-Tzong; Tseng, Fan-Gang

    2012-01-01

    In this investigation, we propose and experimentally demonstrate a method for measuring the refractive index (RI) of liquid organic chemicals. The scheme is based on a single-mode fiber (SMF) sensor and an optical time-domain reflectometer (OTDR). Here, due to the different reflectance (R) between the SMF and organic liquid chemicals, the reflected power level of the backscattering light (BSL) measured by the OTDR would be different. Therefore, we can measure the RI of chemical under test via the measured BSL level. The proposed RI sensor is simple and easy to manipulate, with stable detected signals, and has the potential to be a valuable tool for use in biological and chemical applications. PMID:22368480

  14. Assessment of wavelength dependent complex refractive index of strongly light absorbing liquids.

    PubMed

    Räty, Jukka; Pääkkönen, Pertti; Peiponen, Kai-Erik

    2012-01-30

    A practical measurement procedure for the determination of the complex refractive index of strongly absorbing liquids within a finite spectral range was developed. The method is based on separate measurements of reflectance and transmittance of the liquid sample, a property of dispersion and absorption, and exploitation of Fresnel's theory. The advantage of the method is that the knowledge of the layer thickness of the light absorbing medium, which is required typically in transmittance measurements, is not needed. In addition, both measurements, the transmittance and the reflectance, were accomplished with one spectrophotometer using a home-built reflectometer and without any sample dilution. The method is validated by numerical simulation using the Lorentz model for permittivity of an insulator, and also by experimental data obtained from three strongly absorbing offset inks, namely magenta, yellow and cyan. PMID:22330520

  15. Correlation between the nonlinear refractive index and structure of germanium-based chalcogenide glasses

    SciTech Connect

    Petit, L. [School of Materials Science and Engineering, Clemson University, Clemson, SC 29634 (United States)], E-mail: lpetit@clemson.edu; Carlie, N. [School of Materials Science and Engineering, Clemson University, Clemson, SC 29634 (United States); Humeau, A.; Boudebs, G. [Laboratoire des Proprietes Optiques des Materiaux et Applications, UMR CNRS 6163, Universite d'Angers, 2 Boulevard Lavoisier, 49045 Angers Cedex 01 (France); Jain, H. [Center for Optical Technologies and Department of Materials Science and Engineering, Lehigh University, 5 E Packer Avenue, Bethlehem, PA 18015 (United States); Miller, A.C. [Center for Advanced Materials and Nanotechnology, Lehigh University, Bethlehem, PA 180015-1539 (United States); Richardson, K. [School of Materials Science and Engineering, Clemson University, Clemson, SC 29634 (United States)

    2007-12-04

    The nonlinear refractive index (n{sub 2}) of new germanium-based sulfo-selenide glasses has been measured at 1064 nm using Z-scan technique, with picosecond pulses emitted by a 10 Hz Q-switched mode-locked Nd:Yag laser. We have determined the impact of the progressive replacement of S by Se on the nonlinear properties of these glasses. The value of n{sub 2} strongly increases with the substitution of S by Se, up to 350 times the n{sub 2} for fused silica. X-ray photoelectron spectroscopy (XPS) indicates that the increase of Ge-Se bond units in the glass network is responsible for the increase of n{sub 2}. The suitability of these glasses for optical switching at telecommunication wavelengths based on such nonlinear properties has been also confirmed.

  16. Topological insulator metamaterials with tunable negative refractive index in the optical region.

    PubMed

    Cao, Tun; Wang, Shuai

    2013-01-01

    A blueshift tunable metamaterial (MM) exhibiting a double-negative refractive index based on a topological insulator (bismuth selenide, Bi2Se3) has been demonstrated in the near-infrared (NIR) spectral region. The potential of Bi2Se3 as a dielectric interlayer of the multilayer MM is explored. The optical response of elliptical nanohole arrays penetrating through Au/Bi2Se3/Au films is numerically investigated using the finite difference time domain (FDTD) method. The blueshift tuning range of the MM is as high as 370 nm (from 2,140 to 1,770 nm) after switching the Bi2Se3 between its trigonal and orthorhombic states. PMID:24330596

  17. Preparation of inulin-type fructooligosaccharides using fast protein liquid chromatography coupled with refractive index detection.

    PubMed

    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

  18. Calibration correction of an active scattering spectrometer probe to account for refractive index of stratospheric aerosols

    NASA Technical Reports Server (NTRS)

    Pueschel, R. F.; Overbeck, V. R.; Snetsinger, K. G.; Russell, P. B.; Ferry, G. V.

    1990-01-01

    The use of the active scattering spectrometer probe (ASAS-X) to measure sulfuric acid aerosols on U-2 and ER-2 research aircraft has yielded results that are at times ambiguous due to the dependence of particles' optical signatures on refractive index as well as physical dimensions. The calibration correction of the ASAS-X optical spectrometer probe for stratospheric aerosol studies is validated through an independent and simultaneous sampling of the particles with impactors; sizing and counting of particles on SEM images yields total particle areas and volumes. Upon correction of calibration in light of these data, spectrometer results averaged over four size distributions are found to agree with similarly averaged impactor results to within a few percent: indicating that the optical properties or chemical composition of the sample aerosol must be known in order to achieve accurate optical aerosol spectrometer size analysis.

  19. Measurement of resonant and nonresonant induced refractive index changes in Yb-doped fiber grating amplifier.

    PubMed

    Shapira, Y P; Oscar, D; Spektor, B; Smulakovsky, V; Horowitz, M

    2015-02-15

    We have measured the refractive index change (RIC) induced in a fiber Bragg grating (FBG) written in a Yb-doped fiber amplifier (YB-FBG) because of the amplifier pumping. The measurement was performed by exploiting the high sensitivity of the YD-FBG transmission to the RIC. We have separated between electronic and thermal contributions to the RIC based on the difference between the time-scales of the two effects. Because of high UV-induced loss in FBGs, the thermal contribution to the RIC is increased, in comparison with previously published work, where no grating was written in the fiber amplifier. The measurement method allows us to find the sign of each contribution to the RIC, and it requires only a few centimeters of fiber. Optimal pumping scheme for reducing the RIC in a YB-FBG is studied. PMID:25680141

  20. On the feasibility of optical-CT imaging in media of different refractive index

    PubMed Central

    Rankine, Leith; Oldham, Mark

    2013-01-01

    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 (?) 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 radii) than point and parallel geometries. A further disadvantage of converging geometry was an increased requirement on detector size by up to 18°. Conclusions: For applications where dose information is not required in the periphery of the dosimeter, some dry and low-viscous matching configurations may be feasible. For all three dose distributions (uniform, VMAT, brachytherapy) the point source geometry produced slightly more favorable results (an extra 1%–2% usable radii) than parallel and converging. When dosimetry is required on the periphery, best results were obtained using close refractive matching and ART. A concern for water or dry-scanning is the increase in required detector size, introducing potential cost penalties for manufacturing. PMID:23635249

  1. On the feasibility of optical-CT imaging in media of different refractive index

    SciTech Connect

    Rankine, Leith [Medical Physics Graduate Program, Duke University, Durham, North Carolina 27710 (United States); Oldham, Mark [Department of Radiation Oncology Physics, Duke University Medical Center, Durham, North Carolina 27710 (United States)

    2013-05-15

    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{sup Registered-Sign }, 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 ({Gamma}) 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 radii) than point and parallel geometries. A further disadvantage of converging geometry was an increased requirement on detector size by up to 18 Degree-Sign . Conclusions: For applications where dose information is not required in the periphery of the dosimeter, some dry and low-viscous matching configurations may be feasible. For all three dose distributions (uniform, VMAT, brachytherapy) the point source geometry produced slightly more favorable results (an extra 1%-2% usable radii) than parallel and converging. When dosimetry is required on the periphery, best results were obtained using close refractive matching and ART. A concern for water or dry-scanning is the increase in required detector size, introducing potential cost penalties for manufacturing.

  2. Equation of state, refractive index and polarizability of compressed water to 7 GPa and 673 K.

    PubMed

    Sanchez-Valle, Carmen; Mantegazzi, Davide; Bass, Jay D; Reusser, Eric

    2013-02-01

    The equation of state (EoS), refractive index n, and polarizability ? of water have been determined up to 673 K and 7 GPa from acoustic velocity measurements conducted in a resistively heated diamond anvil cell using Brillouin scattering spectroscopy. Measured acoustic velocities compare favorably with previous experimental studies but they are lower than velocities calculated from the extrapolation of the IAPWS95 equation of state above 3 GPa at 673 K and deviations increase up to 6% at 7 GPa. Densities calculated from the velocity data were used to propose an empirical EoS suitable in the 0.6-7 GPa and 293-673 K range with a total estimated uncertainty of 0.5% or less. The density model and thermodynamic properties derived from the experimental EoS have been compared to several EoS proposed in the literature. The IAPWS95 EoS provides good agreement, although underestimates density by up to 1.2% at 7 GPa and 673 K and the thermodynamic properties deviate greatly (10%-20%) outside the estimated uncertainties above 4 GPa. The refractive index n of liquid water increases linearly with density and do not depend intrinsically on temperature. The polarizability decreases with pressure by less than 4% within the investigated P-T range, suggesting strong intermolecular interactions in H(2)O that are consistent with the prevalence of the hydrogen bond network in the fluid. The results will allow the refinement of interaction potentials that consider polarization effects for a better understanding of solvent-solvent and ion-solvent interactions in aqueous fluids at high pressure and temperature conditions. PMID:23406131

  3. Spatially confined and temporally resolved refractive index and scattering evaluation in human skin performed with optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Knuettel, Alexander R.; Boehlau-Godau, Martin

    2000-01-01

    In the present applications of optical coherence tomography (OCT), parameters besides pure morphology are evaluated in skin tissue under in vivo conditions. Spatially mapped refractive indices and scattering coefficients may support tissue characterization for research and diagnostic purposes in cosmetics/pharmacy and medicine, respectively. The sample arm of our OCT setup has been arranged to permit refractive index evaluation with little mechanical adjustment of a lens within the objective. A simple algorithm has been derived. Known from atmospheric work, the Klett algorithm has been applied to the same data set for retrieval of scattering coefficients. Both parameters have been measured in layered structures in skin like stratum corneum, epidermis and dermis. Significant water content in a localized sweat gland duct has been observed by refractive index evaluation. Time studies over 1.5 h permitted a first understanding about physiological changes in skin which are not obtainable by intrusive methods.

  4. Mechanism of femtosecond-laser induced refractive index change in phosphate glass under a low repetition-rate regime

    NASA Astrophysics Data System (ADS)

    Little, Douglas J.; Ams, Martin; Dekker, Peter; Marshall, Graham D.; Withford, Michael J.

    2010-08-01

    Raman microscopy and refractive near-field profilometry were used to analyze waveguides written in Yb-doped Kigre QX glass under the low repetition-rate (noncumulative-heating) regime. It was found that femtosecond-laser induced refractive index change was due to an increase in the proportion of Q1 P-tetrahedra and the associated increase in the polarizability of the glass. The role of color center formation and removal in this process is clearly defined, phosphorous-oxygen hole centers (POHCs) and PO3- ions form as a result of P-O bonds being broken during the modification process, and the subsequent removal of POHCs give rise to the increased proportion of Q1 P-tetrahedra. This result, when compared to other studies undertaken in the cumulative-heating regime, show conclusively that the mechanism of refractive index change in a particular type of glass can be very different, depending on the irradiation conditions.

  5. Simultaneous Measurement of Refractive Index and Temperature by Using Dual Long-Period Gratings With an Etching Process

    Microsoft Academic Search

    Jinhua Yan; A. Ping Zhang; Li-Yang Shao; Jin-Fei Ding; Sailing He

    2007-01-01

    A new structure of long-period grating (LPG) sensor is introduced for simultaneous measurement of the refractive index (RI) and temperature. This type of grating device consists of two LPG sections, one of which is post etched by hydrofluoric acid (HF) solution and, therefore, has an improved RI sensitivity (the demonstrated improvement of sensitivity is 3.6 times). The experimental results show

  6. Enabling RF\\/microwave devices using negative-refractive-index transmission-line (NRI-TL) metamaterials

    Microsoft Academic Search

    George V. Eleftheriades

    2007-01-01

    Metamaterials are artificially engineered structures with unusual electromagnetic properties. In this article, we review the implementation of isotropic metamaterials that exhibit a negative permittivity and a negative permeability, thus leading to a negative index of refraction. Specifically, the article focuses on transmission-line metamaterials, which are planar structures comprising a network of distributed transmission lines loaded periodically with inductors, L, and

  7. Synthesis of multifunctional plasmonic nanopillar array using soft thermal nanoimprint lithography for highly sensitive refractive index sensing

    NASA Astrophysics Data System (ADS)

    Yang, Sheng-Chieh; Hou, Ji-Ling; Finn, Andreas; Kumar, Amit; Ge, Yang; Fischer, Wolf-Joachim

    2015-03-01

    A low-cost plasmonic nanopillar array was synthesized using soft thermal nanoimprint lithography, and its sensitivity was determined through far-field spectroscopic measurements. Its transmission spectrum was highly dependent on the refractive index of the surrounding medium, with its sensitivity being 375 nm per refractive index unit according to the spectral shift. Moreover, a simple sensor whose reflected color changed with a change in the plasma frequency on varying the surrounding medium was fabricated.A low-cost plasmonic nanopillar array was synthesized using soft thermal nanoimprint lithography, and its sensitivity was determined through far-field spectroscopic measurements. Its transmission spectrum was highly dependent on the refractive index of the surrounding medium, with its sensitivity being 375 nm per refractive index unit according to the spectral shift. Moreover, a simple sensor whose reflected color changed with a change in the plasma frequency on varying the surrounding medium was fabricated. Electronic supplementary information (ESI) available: Experimental setup for measuring the transmission spectra; simulated reflectance spectrum of the metal nanodisk array; simulated reflectance spectra of PNPA structures with Ti (1 nm)/Au (23 nm) and Ti (1 nm)/Ag (20 nm)/Au (3 nm) layers: experimentally determined transmission spectra of the PNPA and the PNPA without the metal nanodisk array. See DOI: 10.1039/c5nr00472a

  8. Effects of Refractive Index and Viscosity on Fluorescence and Anisotropy Decays of Enhanced Cyan and Yellow Fluorescent Proteins

    Microsoft Academic Search

    Jan Willem Borst; Mark A. Hink; Arie van Hoek; Antonie J. W. G. Visser

    2005-01-01

    The fluorescence lifetime strongly depends on the immediate environment of the fluorophore. Time-resolved fluorescence measurements of the enhanced forms of ECFP and EYFP in water–glycerol mixtures were performed to quantify the effects of the refractive index and viscosity on the fluorescence lifetimes of these proteins. The experimental data show for ECFP and EYFP two fluorescence lifetime components: one short lifetime

  9. Initial growth, refractive index, and crystallinity of thermal and plasma-enhanced atomic layer deposition AlN films

    SciTech Connect

    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.

  10. OPTICAL FIBRES: Study of the dynamics of transformation of point defects in phosphosilicate fibres by the induced refraction index

    Microsoft Academic Search

    Yu V. Larionov; A. A. Rybaltovsky; S. L. Semenov; M. A. Kurzanov; Aleksei Z. Obidin; Sergei K. Vartapetov

    2003-01-01

    A method for studying the dynamics of transformation of defects in optical fibres, exposed to UV radiation, by the dose dependence of the induced refractive index is proposed. The processes of transformation of defects in a low-loss phosphosilicate fibre, loaded with molecular hydrogen, irradiated at the 193-nm wavelength are investigated using this method. It is assumed that such a fibre

  11. Study of the dynamics of transformation of point defects in phosphosilicate fibres by the induced refraction index

    Microsoft Academic Search

    Yu V Larionov; A A Rybaltovsky; S L Semenov; M A Kurzanov; Aleksei Z Obidin; Sergei K Vartapetov

    2003-01-01

    A method for studying the dynamics of transformation of defects in optical fibres, exposed to UV radiation, by the dose dependence of the induced refractive index is proposed. The processes of transformation of defects in a low-loss phosphosilicate fibre, loaded with molecular hydrogen, irradiated at the 193-nm wavelength are investigated using this method. It is assumed that such a fibre

  12. Influence of the sign of the refractive index in the reflectivity of a metamaterial surface with localized roughness

    Microsoft Academic Search

    Vivian Grunhut; Ricardo A. Depine

    2011-01-01

    To study the scattering properties of metamaterials, we generalize two scattering methods developed for conventional (non-magnetic) isotropic materials to the case of materials with arbitrary values (positive or negative) of magnetic permeability and electric permittivity. The generalized methods are used to study the changes in the reflectivity of a metamaterial surface with localized roughness when the relative refractive index changes

  13. Spectral Behavior in Nano-Coated Tilted Fiber Bragg Gratings: Effect of Thickness and External Refractive Index

    Microsoft Academic Search

    D. Paladino; A. Cusano; P. Pilla; S. Campopiano; C. Caucheteur; P. Megret

    2007-01-01

    This work reports on the experimental investigation of the spectral effects induced by uniform high refractive index nano-coatings deposited on weakly tilted fiber Bragg gratings (TFBGs). To this aim, weakly TFBGs with different tilt angles were fabricated and then coated with thin overlays of syndiotactic polystyrene. Automated dip coating technique was used to obtain ring-shaped coatings with thickness ranging in

  14. Solution of radiative transfer equation with a continuous and stochastic varying refractive index by legendre transform method.

    PubMed

    Gantri, M

    2014-01-01

    The present paper gives a new computational framework within which radiative transfer in a varying refractive index biological tissue can be studied. In our previous works, Legendre transform was used as an innovative view to handle the angular derivative terms in the case of uniform refractive index spherical medium. In biomedical optics, our analysis can be considered as a forward problem solution in a diffuse optical tomography imaging scheme. We consider a rectangular biological tissue-like domain with spatially varying refractive index submitted to a near infrared continuous light source. Interaction of radiation with the biological material into the medium is handled by a radiative transfer model. In the studied situation, the model displays two angular redistribution terms that are treated with Legendre integral transform. The model is used to study a possible detection of abnormalities in a general biological tissue. The effect of the embedded nonhomogeneous objects on the transmitted signal is studied. Particularly, detection of targets of localized heterogeneous inclusions within the tissue is discussed. Results show that models accounting for variation of refractive index can yield useful predictions about the target and the location of abnormal inclusions within the tissue. PMID:25013454

  15. Laser-Based Measurement of Refractive Index Changes: Kinetics of 2,3-Epoxy-1-propanol Hydrolysis.

    ERIC Educational Resources Information Center

    Spencer, Bert; Zare, Richard N.

    1988-01-01

    Describes an experiment in which a simple laser-based apparatus is used for measuring the change in refractive index during the acid-catalyzed hydrolysis of glycidol into glycerine. Gives a schematic of the experimental setup and discusses the kinetic analysis. (MVL)

  16. Effective refractive index for determining ray propagation in an absorbing dielectric particle

    E-print Network

    Liou, K. N.

    wavelength. When a scattering particle is absorptive, a localized electromagnetic wave refracted of refraction is a complex quantity, electromagnetic waves refracted into a particle are inhomogeneous Article history: Received 21 September 2008 Received in revised form 4 November 2008 Accepted 5 November

  17. Influence of the Rayleigh backscattering on the mode composition of radiation in multimode graded-index waveguides with a quadratic refractive-index profile

    Microsoft Academic Search

    G L Esayan; S G Krivoshlykov

    1989-01-01

    A method of coherent states is used to describe the process of Rayleigh scattering in a multimode graded-index waveguide with a quadratic refractive-index profile. Explicit expressions are obtained for the coefficients representing excitation of Gaussian–Hermite backscattering modes in two cases of practical importance: excitation of a waveguide by an extended noncoherent light source and selective excitation of different modes at

  18. A new method for measuring the imaginary part of the atmospheric refractive index structure parameter in the urban surface layer

    NASA Astrophysics Data System (ADS)

    Yuan, R.; Luo, T.; Sun, J.; Zeng, Z.; Ge, C.; Fu, Y.

    2015-03-01

    The atmospheric refractive index consists of both real and imaginary parts. The intensity of refractive index fluctuations is generally expressed as the refractive index structure parameter, with the real part reflecting the strength of atmospheric turbulence and the imaginary part reflecting absorption in the light path. A large aperture scintillometer (LAS) is often used to measure the structure parameter of the real part of the atmospheric refractive index, from which the sensible and latent heat fluxes can further be obtained, whereas the influence of the imaginary part is ignored or considered noise. In this theoretical analysis study, the relationship between logarithmic light intensity variance and the atmospheric refractive index structure parameter (ARISP), as well as that between the logarithmic light intensity structure function and the ARISP, is derived. Additionally, a simple expression for the imaginary part of the ARISP is obtained which can be conveniently used to determine the imaginary part of the ARISP from LAS measurements. Moreover, these relationships provide a new method for estimating the outer scale of turbulence. Light propagation experiments were performed in the urban surface layer, from which the imaginary part of the ARISP was calculated. The experimental results showed good agreement with the presented theory. The results also suggest that the imaginary part of the ARISP exhibits a different diurnal variation from that of the real part. For the wavelength of light used (0.62 ?m), the variation of the imaginary part of the ARISP is related to both the turbulent transport process and the spatial distribution characteristics of aerosols.

  19. Effective broadband refractive index retrieval by a white light optical particle counter.

    PubMed

    Flores, J Michel; Trainic, Miri; Borrmann, Stephan; Rudich, Yinon

    2009-09-28

    A new approach to retrieve the effective broadband refractive indices (nbroad,eff) of aerosol particles by a white light aerosol spectrometer (WELAS) optical particle counter (OPC) is presented. Using a tandem differential mobility analyzer (DMA)-OPC system, the nbroad,eff are obtained for both laboratory and field applications. This method was tested in the laboratory using substances with a wide range of optical properties. With the obtained nbroad,eff, WELAS aerosol size distributions can be corrected. Therefore, this method can be used for instrument calibration in both laboratory and field measurements. The retrieved effective broadband refractive indices for the scattering aerosols were: ammonium sulfate ((NH4)2SO4, AS) nbroad,eff=1.52(+/-0.01)+i0.0, glutaric acid (HOOC(CH2)3COOH, GA) nbroad,eff=1.45(+/-0.01)+i0.0, and sodium chloride (NaCl) nbroad,eff=1.49(+/-0.02)+i0.0, all within 4% of literature values. A lightly absorbing substance, Suwannee river fulvic acid (SRFA), was also measured, and its retrieved nbroad,eff is like that of a pure scatterer, with a value of nbroad,eff=1.53(+/-0.01)+i0.0. The retrieved real part of nbroad,eff is in accordance with literature values and the imaginary part with the behavior of the white light spectrum of the WELAS, which is not sensitive below a wavelength of 380 nm, where SRFA mainly absorbs. For absorbing substances, nigrosine and various mixtures of nigrosine with AS and GA were measured. For nigrosine, nbroad,eff=1.64(+/-0.04)+i0.20(+/-0.03) was retrieved, in very good agreement with values found in the literature. The nbroad,eff retrieved by this method for the mixtures was in accordance with the complex refractive index expected. The nbroad,eff retrieved by this method would be similar to the values obtained using the solar spectrum. PMID:19727501

  20. Restriction of the phase matching condition on refractive index modulation of 1D photonic crystals in second harmonic generation

    NASA Astrophysics Data System (ADS)

    Wu, Huinan; Huang, Jinjer; Pu, Shaozhi; Zhang, Liuyang; Yang, Zhongying

    2015-01-01

    Phase and group velocity matching equations of second harmonic generation are reconsidered for 1D photonic crystals to analyze an induced structure restriction. A multiplicity of solutions is found through a numerical computation, which separates the restricted structure parameters into infinite units. The local and global characteristics of the restriction on refractive indices and material lengths are discussed in detail as well. The analysis shows that increasing either the dispersion of the nonlinear material or the thickness of a single layer will require a larger refractive index contrast.

  1. Impact of incoherent pumping field and Er3+ ion concentration on group velocity and index of refraction in an Er3+-doped YAG crystal

    NASA Astrophysics Data System (ADS)

    Jafarzadeh, Hossein; Asadpour, Seyyed Hossein; Rahimpour Soleimani, H.

    2015-03-01

    The effect of Er3+ ion concentration and incoherent pumping field on the refractive index and group index in an Er3+: YAG crystal is investigated. It is shown that under different concentrations of Er3+ ion in the crystal, the index of refraction and absorption can be changed and a high index of refraction is accompanied by amplification in the medium. Also, it is shown that with the switching from subluminal to superluminal, or vice versa, light propagation can be obtained by different concentrations of Er3+ ions in the crystal.

  2. DESIGN OF WIRE-WRAPPED ROD BUNDLE MATCHED INDEX-OF-REFRACTION EXPERIMENTS

    SciTech Connect

    Hugh McIlroy; Hongbin Zhang; Kurt Hamman

    2008-05-01

    Experiments will be conducted in the Idaho National Laboratory (INL) Matched Index-of-Refraction (MIR) Flow Facility [1] to characterize the three-dimensional velocity and turbulence fields in a wire-wrapped rod bundle typically employed in liquid-metal cooled fast reactors and to provide benchmark data for computer code validation. Sodium cooled fast reactors are under consideration for use in the U.S. Department of Energy (DOE) Global Nuclear Energy Partnership (GNEP) program. The experiment model will be constructed of quartz components and the working fluid will be mineral oil. Accurate temperature control (to within 0.05 oC) matches the index-of-refraction of mineral oil with that of quartz and renders the model transparent to the wavelength of laser light employed for optical measurements. The model will be a scaled 7-pin rod bundle enclosed in a hexagonal canister. Flow field measurements will be obtained with a LaVision 3-D particle image velocimeter (PIV) and complimented by near-wall velocity measurements obtained from a 2-D laser Doppler velocimeter (LDV). These measurements will be used as benchmark data for computational fluid dynamics (CFD) validation. The rod bundle model dimensions will be scaled up from the typical dimensions of a fast reactor fuel assembly to provide the maximum Reynolds number achievable in the MIR flow loop. A range of flows from laminar to fully-turbulent will be available with a maximum Reynolds number, based on bundle hydraulic diameter, of approximately 22,000. The fuel pins will be simulated by 85 mm diameter quartz tubes (closed on the inlet ends) and the wire-wrap will be simulated by 25 mm diameter quartz rods. The canister walls will be constructed from quartz plates. The model will be approximately 2.13 m in length. Bundle pressure losses will also be measured and the data recorded for code comparisons. The experiment design and preliminary CFD calculations, which will be used to provide qualitative hydrodynamic information, are presented in this paper.

  3. Determination of a refractive index and an extinction coefficient of standard production of CVD-graphene

    NASA Astrophysics Data System (ADS)

    Ochoa-Martínez, Efraín; Gabás, Mercedes; Barrutia, Laura; Pesquera, Amaia; Centeno, Alba; Palanco, Santiago; Zurutuza, Amaia; Algora, Carlos

    2015-01-01

    The refractive index and extinction coefficient of chemical vapour deposition grown graphene are determined by ellipsometry analysis. Graphene films were grown on copper substrates and transferred as both monolayers and bilayers onto SiO2/Si substrates by using standard manufacturing procedures. The chemical nature and thickness of residual debris formed after the transfer process were elucidated using photoelectron spectroscopy. The real layered structure so deduced has been used instead of the nominal one as the input in the ellipsometry analysis of monolayer and bilayer graphene, transferred onto both native and thermal silicon oxide. The effect of these contamination layers on the optical properties of the stacked structure is noticeable both in the visible and the ultraviolet spectral regions, thus masking the graphene optical response. Finally, the use of heat treatment under a nitrogen atmosphere of the graphene-based stacked structures, as a method to reduce the water content of the sample, and its effect on the optical response of both graphene and the residual debris layer are presented. The Lorentz-Drude model proposed for the optical response of graphene fits fairly well the experimental ellipsometric data for all the analysed graphene-based stacked structures.The refractive index and extinction coefficient of chemical vapour deposition grown graphene are determined by ellipsometry analysis. Graphene films were grown on copper substrates and transferred as both monolayers and bilayers onto SiO2/Si substrates by using standard manufacturing procedures. The chemical nature and thickness of residual debris formed after the transfer process were elucidated using photoelectron spectroscopy. The real layered structure so deduced has been used instead of the nominal one as the input in the ellipsometry analysis of monolayer and bilayer graphene, transferred onto both native and thermal silicon oxide. The effect of these contamination layers on the optical properties of the stacked structure is noticeable both in the visible and the ultraviolet spectral regions, thus masking the graphene optical response. Finally, the use of heat treatment under a nitrogen atmosphere of the graphene-based stacked structures, as a method to reduce the water content of the sample, and its effect on the optical response of both graphene and the residual debris layer are presented. The Lorentz-Drude model proposed for the optical response of graphene fits fairly well the experimental ellipsometric data for all the analysed graphene-based stacked structures. Electronic supplementary information (ESI) available: DETAILS. See DOI: 10.1039/c4nr06119e

  4. Determination of the phase of the complex nonlinear refractive index by transient two-wave mixing in saturable absorbers.

    PubMed

    Boothroyd, S A; Chrostowski, J; O'Sullivan, M S

    1989-09-01

    The ratio of the imaginary part to the real part of the complex nonlinear refractive index has been measured by transient two-wave mixing in acridine-orange-doped fluorophosphate glass, fluorescein-doped boric-acid glass, and ruby at argon-ion wavelengths. The method enables the individual signs of the components of the nonlinear index to be obtained. A simple theory based on a single homogeneously broadened absorption from the ground state agrees with measurements of the phase of the nonlinear index in acridine but not in fluorescein, where our data suggest that excited-state absorption plays an important role. PMID:19753020

  5. A Simple Method for Prediction of Effective Core Area and Index of Refraction of Single-mode Graded Index Fiber in the Low V Region

    NASA Astrophysics Data System (ADS)

    Majumdar, Angshuman; Das, Satabdi; Gangopadhyay, Sankar

    2014-12-01

    Based on the simple power series formulation of fundamental mode developed by Chebyshev formalism in the low V region, we prescribe analytical expression for effective core area of graded index fiber. Taking step and parabolic index fibers as examples, we estimate the effective core areas as well as effective refractive index for different normalized frequencies (V number) having low values. We also show that our estimations match excellently with the available exact results. The concerned predictions by our method require little computation. Thus, this simple but accurate formalism will be user friendly for the system engineers.

  6. Light extraction analysis of organic light emitting diodes fabricated on high refractive index glass scattering layer

    NASA Astrophysics Data System (ADS)

    Nakamura, N.; Fukumoto, N.; Wada, N.; Ohgawara, M.

    2015-02-01

    Optical analysis was performed for Organic Light Emitting Diodes (OLEDs) formed on a high refractive index glass (high-n-glass) scattering layer. Angular dependency of luminance for OLEDs fabricated on high-n-glass substrate with a hemisphere high-n-glass lens has a good agreement with the emitting directivity calculated by an interference simulation. Applying this emitting directivity, ray trace simulation was performed for OLEDs on various types of substrates and hemisphere lenses. The calculated out-coupled light flux has a good agreement with the measured values. From the experimental and simulation results, it can be concluded that out-coupling efficiency is 1.7 times compared to the reference, and about 55% of lights out of the OLED device can be extracted to the air by the high-n-glass scattering layer. In this case, the probability of light out-coupling as a function of emitting angle starts at 66% at 0°, and still remains more than 30% up to 70° from the normal direction.

  7. Photonic crystal fiber refractive index sensor based on surface plasmon resonance

    NASA Astrophysics Data System (ADS)

    Chen, Jiahua; Brabant, Daniel; Bock, Wojtek J.; Mikulic, Predrag; Eftimov, Tinko

    2010-06-01

    This paper presents a photonic crystal fiber (PCF) refractive index sensor. The sensor structure is quite simple. It is composed of three segments of optical fibers spliced together. The multimode fibers with core diameter of 50 ?m are used for light input and output. The middle fiber is a short segment of PCF, ESM-12-01. Although it has some advantages such as being able to operate in single mode for a large number of light wavelengths and has great temperature stability, it also has a common drawback of the PCFs, that is, the tiny holes will collapse when they are spliced. This paper makes use of this drawback to facilitate the generation of the surface plasmon resonance. The spliced region of a PCF actually becomes a thin silica rod that is no longer a PCF or a traditional optical fiber. For this reason once the light travels into this region it diverts in all possible directions. Thus, the splice acts as a mode converter that converts the core modes of the multimode fiber into a set of the modes spreading into the PCF cladding. Among those modes some are suitable for SPR excitation. The width and the depth of the output spectrum dip depend on the length of the sensing part and the thickness and uniformity of the gold coating, and hence these parameters affect the properties of the sensor. The developed sensor is compact in size, simple to fabricate, promising in performance, and has a potential for practical applications.

  8. Determination of a refractive index and an extinction coefficient of standard production of CVD-graphene.

    PubMed

    Ochoa-Martínez, Efraín; Gabás, Mercedes; Barrutia, Laura; Pesquera, Amaia; Centeno, Alba; Palanco, Santiago; Zurutuza, Amaia; Algora, Carlos

    2015-01-28

    The refractive index and extinction coefficient of chemical vapour deposition grown graphene are determined by ellipsometry analysis. Graphene films were grown on copper substrates and transferred as both monolayers and bilayers onto SiO2/Si substrates by using standard manufacturing procedures. The chemical nature and thickness of residual debris formed after the transfer process were elucidated using photoelectron spectroscopy. The real layered structure so deduced has been used instead of the nominal one as the input in the ellipsometry analysis of monolayer and bilayer graphene, transferred onto both native and thermal silicon oxide. The effect of these contamination layers on the optical properties of the stacked structure is noticeable both in the visible and the ultraviolet spectral regions, thus masking the graphene optical response. Finally, the use of heat treatment under a nitrogen atmosphere of the graphene-based stacked structures, as a method to reduce the water content of the sample, and its effect on the optical response of both graphene and the residual debris layer are presented. The Lorentz-Drude model proposed for the optical response of graphene fits fairly well the experimental ellipsometric data for all the analysed graphene-based stacked structures. PMID:25504461

  9. The effect of annealing on the variation of glass refractive index.

    PubMed

    Rushton, K P; Coulson, S A; Newton, A W N; Curran, J M

    2011-06-15

    The variation of refractive index (RI) over a non-toughened, float pane of glass and a toughened, float pane of glass was investigated. The two panes of colourless, float glass were cut into 150 5 cm × 5 cm squares. The pre- and post-annealing RI values from three random areas from each square were measured. Bayesian statistical hierarchical modelling of the results showed that for the non-toughened, float glass pane annealing increased the variability in RI by a factor of 1.29-1.58, with a mean of 1.43 (with 95% probability); and for the toughened, float pane of glass annealing decreased the variability in RI by a factor of 0.63-0.76, with a mean of 0.69 (with 95% probability). In addition it was found that although there were no systematic differences in ?RI across either pane of glass, there were observable differences across both panes of glass. These results provide information regarding the expected RI variation over entire panes of both non-toughened and toughened float window glass for both pre- and post-annealing RI measurements. PMID:21310561

  10. Optical fiber sensor based on capillary wall for highly-sensitive refractive index measurement

    NASA Astrophysics Data System (ADS)

    Liu, Yun; Peng, Wei; Zhang, Xinpu; Qian, Siyu

    2014-05-01

    This paper reports a temperature-compensated fiber-optic refractive index (RI) sensor for high sensitivity measurement. The sensor includes a piece of fused-silica capillary (FSC) and a fiber Bragg grating (FBG), both of which are sandwiched by single-mode fibers (SMFs). When light from the lead-in SMF enters into the wall of the FSC that acts as a RI sensing element, multiple modes are excited and interfere to form fringes collected by the lead-out SMF. The FBG is fabricated adjunct to the FSC to compensate its temperature sensitivity. The FSC based sensor prototype is fabricated and sealed in a flow cell to test its performance. Experimental results show that the sensor is highly sensitive to RI, and the sensitivity in the tested RI range from 1.33 to 1.35 is 698.52 nm/RIU and from 1.35 to 1.37 is 1061.78 nm/RIU. The temperature sensitivity of the FSC is -0.173 nm/°C, which is compensated by the FBG. This capillary wall based sensor can be further developed as a miniaturized fiber optic biosensor for biochemical application.

  11. Polarization-dependent optical absorption of MoS2 for refractive index sensing

    NASA Astrophysics Data System (ADS)

    Tan, Yang; He, Ruiyun; Cheng, Chen; Wang, Dong; Chen, Yanxue; Chen, Feng

    2014-12-01

    As a noncentrosymmetric crystal with spin-polarized band structure, MoS2 nanomaterials have attracts increasing attention in many areas such as lithium ion batteries, flexible electronic devices, photoluminescence and valleytronics. The investigation of MoS2 is mainly focused on the electronics and spintronics instead of optics, which restrict its applications as key elements of photonics. In this work, we demonstrate the first observation of the polarization-dependent optical absorption of the MoS2 thin film, which is integrated onto an optical waveguide device. With this feature, a novel optical sensor combining MoS2 thin-film and a microfluidic structure has been constituted to achieve the sensitive monitoring of refractive index. Our work indicates the MoS2 thin film as a complementary material to graphene for the optical polarizer in the visible light range, and explores a new application direction of MoS2 nanomaterials for the construction of photonic circuits.

  12. Polarization-dependent optical absorption of MoS? for refractive index sensing.

    PubMed

    Tan, Yang; He, Ruiyun; Cheng, Chen; Wang, Dong; Chen, Yanxue; Chen, Feng

    2014-01-01

    As a noncentrosymmetric crystal with spin-polarized band structure, MoS2 nanomaterials have attracts increasing attention in many areas such as lithium ion batteries, flexible electronic devices, photoluminescence and valleytronics. The investigation of MoS2 is mainly focused on the electronics and spintronics instead of optics, which restrict its applications as key elements of photonics. In this work, we demonstrate the first observation of the polarization-dependent optical absorption of the MoS2 thin film, which is integrated onto an optical waveguide device. With this feature, a novel optical sensor combining MoS2 thin-film and a microfluidic structure has been constituted to achieve the sensitive monitoring of refractive index. Our work indicates the MoS2 thin film as a complementary material to graphene for the optical polarizer in the visible light range, and explores a new application direction of MoS2 nanomaterials for the construction of photonic circuits. PMID:25516116

  13. Refractive index susceptibility of the plasmonic palladium nanoparticle: potential as the third plasmonic sensing material.

    PubMed

    Sugawa, Kosuke; Tahara, Hironobu; Yamashita, Ayane; Otsuki, Joe; Sagara, Takamasa; Harumoto, Takashi; Yanagida, Sayaka

    2015-02-24

    We demonstrate that Pd nanospheres exhibit much higher susceptibility of the localized surface plasmon resonance (LSPR) peak to medium refractive index changes than commonly used plasmonic sensing materials such as Au and Ag. The susceptibility of spherical Au nanoparticle-core/Pd-shell nanospheres (Au/PdNSs, ca. 73 nm in diameter) was found to be 4.9 and 2.5 times higher, respectively, than those of Au (AuNSs) and Ag nanospheres (AgNSs) having similar diameters. The experimental finding was theoretically substantiated using the Mie exact solution. We also showed from a quasi-static (QS) approximation framework that the high susceptibility of Pd LSPR originates from the smaller dispersion of the real part of its dielectric function than those of Au and Ag LSPR around the resonant wavelength. We conclude that the Pd nanoparticle is a promising candidate of "the third plasmonic sensing material" following Au and Ag to be used in ultrahigh-sensitive LSPR sensors. PMID:25629586

  14. Raman imaging of pharmaceutical materials: refractive index effects on contrast at buried interfaces.

    PubMed

    Mecker-Pogue, Laura C; Kauffman, John F

    2015-02-01

    Resolution targets composed of bilayer polydimethylsiloxane (PDMS) devices with buried polyethylene glycol (PEG) channels have been fabricated using traditional photolithographic and micromolding techniques to develop resolution targets that mimic pharmaceutical materials. Raman chemical images of the resulting PEG-in-PDMS devices composed of varying parallel line widths were investigated by imaging the PEG lines through a thin overlayer of PDMS. Additionally, a scattering agent, Al2O3, was introduced at varying concentrations to each layer of the device to explore the effects of scattering materials on Raman images. Features in the resulting chemical images of the PEG lines suggest that reflection at the PEG/PDMS interface contributes to the Raman signal. A model based on geometric optics was developed to simulate the observed image functions of the targets. The results emphasize the influence of refractive index discontinuities at the PEG/PDMS interface on the apparent size and shape of the PEG features. Such findings have an impact on interpretation of Raman images of nonabsorbing, opaque pharmaceutical samples. PMID:25527977

  15. Electrical modulation of the complex refractive index in mid-infrared quantum cascade lasers.

    PubMed

    Teissier, J; Laurent, S; Manquest, C; Sirtori, C; Bousseksou, A; Coudevylle, J R; Colombelli, R; Beaudoin, G; Sagnes, I

    2012-01-16

    We have demonstrated an integrated three terminal device for the modulation of the complex refractive index of a distributed feedback quantum cascade laser (QCL). The device comprises an active region to produce optical gain vertically stacked with a control region made of asymmetric coupled quantum wells (ACQW). The optical mode, centered on the gain region, has a small overlap also with the control region. Owing to the three terminals an electrical bias can be applied independently on both regions: on the laser for producing optical gain and on the ACQW for tuning the energy of the intersubband transition. This allows the control of the optical losses at the laser frequency as the absorption peak associated to the intersubband transition can be electrically brought in and out the laser transition. By using this function a laser modulation depth of about 400 mW can be achieved by injecting less than 1 mW in the control region. This is four orders of magnitude less than the electrical power needed using direct current modulation and set the basis for the realisation of electrical to optical transducers. PMID:22274462

  16. Estimated Uncertainties in the Idaho National Laboratory Matched-Index-of-Refraction Lower Plenum Experiment

    SciTech Connect

    Donald M. McEligot; Hugh M. McIlroy, Jr.; Ryan C. Johnson

    2007-11-01

    The purpose of the fluid dynamics experiments in the MIR (Matched-Index-of-Refraction) flow system at Idaho National Laboratory (INL) is to develop benchmark databases for the assessment of Computational Fluid Dynamics (CFD) solutions of the momentum equations, scalar mixing, and turbulence models for typical Very High Temperature Reactor (VHTR) plenum geometries in the limiting case of negligible buoyancy and constant fluid properties. The experiments use optical techniques, primarily particle image velocimetry (PIV) in the INL MIR flow system. The benefit of the MIR technique is that it permits optical measurements to determine flow characteristics in passages and around objects to be obtained without locating a disturbing transducer in the flow field and without distortion of the optical paths. The objective of the present report is to develop understanding of the magnitudes of experimental uncertainties in the results to be obtained in such experiments. Unheated MIR experiments are first steps when the geometry is complicated. One does not want to use a computational technique, which will not even handle constant properties properly. This report addresses the general background, requirements for benchmark databases, estimation of experimental uncertainties in mean velocities and turbulence quantities, the MIR experiment, PIV uncertainties, positioning uncertainties, and other contributing measurement uncertainties.

  17. Polarization-dependent optical absorption of MoS2 for refractive index sensing

    PubMed Central

    Tan, Yang; He, Ruiyun; Cheng, Chen; Wang, Dong; Chen, Yanxue; Chen, Feng

    2014-01-01

    As a noncentrosymmetric crystal with spin-polarized band structure, MoS2 nanomaterials have attracts increasing attention in many areas such as lithium ion batteries, flexible electronic devices, photoluminescence and valleytronics. The investigation of MoS2 is mainly focused on the electronics and spintronics instead of optics, which restrict its applications as key elements of photonics. In this work, we demonstrate the first observation of the polarization-dependent optical absorption of the MoS2 thin film, which is integrated onto an optical waveguide device. With this feature, a novel optical sensor combining MoS2 thin-film and a microfluidic structure has been constituted to achieve the sensitive monitoring of refractive index. Our work indicates the MoS2 thin film as a complementary material to graphene for the optical polarizer in the visible light range, and explores a new application direction of MoS2 nanomaterials for the construction of photonic circuits. PMID:25516116

  18. Complex modes and effective refractive index in 3D periodic arrays of plasmonic nanospheres.

    PubMed

    Campione, Salvatore; Steshenko, Sergiy; Albani, Matteo; Capolino, Filippo

    2011-12-19

    We characterize the modes with complex wavenumber for both longitudinal and transverse polarization states (with respect to the mode traveling direction) in three dimensional (3D) periodic arrays of plasmonic nanospheres, including metal losses. The Ewald representation of the required dyadic periodic Green's function to represent the field in 3D periodic arrays is derived from the scalar case, which can be analytically continued into the complex wavenumber space. We observe the presence of one longitudinal mode and two transverse modes, one forward and one backward. Despite the presence of two modes for transverse polarization, we notice that the forward one is "dominant" (i.e., it contributes most to the field in the array). Therefore, in case of transverse polarization, we describe the composite material in terms of a homogenized effective refractive index, comparing results from (i) modal analysis, (ii) Maxwell Garnett theory, (iii) Nicolson-Ross-Weir retrieval method from scattering parameters for finite thickness structures (considering different thicknesses, showing consistency of results), and (iv) the fitting of the fields obtained through HFSS simulations. The agreement among the different methods justifies the performed homogenization procedure in case of transverse polarization. PMID:22274192

  19. How subvisible particles become invisible-relevance of the refractive index for protein particle analysis.

    PubMed

    Zölls, Sarah; Gregoritza, Manuel; Tantipolphan, Ruedeeporn; Wiggenhorn, Michael; Winter, Gerhard; Friess, Wolfgang; Hawe, Andrea

    2013-05-01

    The aim of the present study was to quantitatively assess the relevance of transparency and refractive index (RI) on protein particle analysis by the light-based techniques light obscuration (LO) and Micro-Flow Imaging (MFI). A novel method for determining the RI of protein particles was developed and provided an RI of 1.41 for protein particles from two different proteins. An increased RI of the formulation by high protein concentration and/or sugars at pharmaceutically relevant levels was shown to lead to a significant underestimation of the subvisible particle concentration determined by LO and MFI. An RI match even caused particles to become "invisible" for the system, that is, not detectable anymore by LO and MFI. To determine the influence of formulation RI on particle measurements, we suggest the use of polytetrafluoroethylene (PTFE) particles to test a specific formulation for RI effects. In case of RI influences, we recommend also using a light-independent technique such as resonant mass measurement (RMM) (Archimedes) for subvisible particle analysis in protein formulations. PMID:23463514

  20. Simultaneous measurement of refractive index and temperature using an epoxy resin-based interferometer.

    PubMed

    Wang, Jian; Wu, Shengli; Ren, Wenyi

    2014-11-20

    A fiber-optics reflection probe based on fiber Fabry-Perot interference (FFPI) is proposed and experimentally demonstrated. The sensing structure comprises an epoxy resin (ER)-based cap on the end-face of the single-mode fiber. A well-defined interference spectrum is obtained by the reflective beams of two surfaces of the ER cap. The simultaneous measurements, including fringe contrast-referenced for the surrounding refractive index (SRI) and wavelength-referenced for temperature, have been achieved via selective interference dips monitoring. Experimental results indicate that the proposed FFPI presents an SRI sensitivity of 57.69 dB/RIU in the measurement range of 1.33-1.40 RIU and a temperature sensitivity of 0.98??pm·?m-1·°C-1 with per unit cavity length in the range of 30°C-70°C. The proposed sensor has advantages of being compact and robust, making it an alternative candidate as a smart sensor in chemical and biological applications. PMID:25607854

  1. Field-induced refractive index variation in the dark conglomerate phase for polarization-independent switchable liquid crystal lenses.

    PubMed

    Milton, H E; Nagaraj, M; Kaur, S; Jones, J C; Morgan, P B; Gleeson, H F

    2014-11-01

    Liquid crystal lenses are an emerging technology that can provide variable focal power in response to applied voltage. Many designs for liquid-crystal-based lenses are polarization dependent, so that 50% of light is not focused as required, making polarization-independent technologies very attractive. Recently, the dark conglomerate (DC) phase, which is an optically isotropic liquid crystalline state, has been shown to exhibit a large change in refractive index in response to an applied electric field (?n=0.04). This paper describes computational modeling of the electrostatic solutions for two different types of 100 ?m diameter liquid crystal lenses, which include the DC phase, demonstrating that it shows great potential for efficient isotropic optical switching in lenses. A feature of the field dependence of the refractive index change in the DC phase is that it is approximately linear in a certain range, leading to the prediction of excellent optical quality for driving fields in this regime. Interestingly, a simulated microlens is shown to exhibit two modes of operation: a positive lens based upon a uniform bulk change in refractive index at high voltages, and a negative lens resulting from the induction of a gradient index effect at intermediate voltages. PMID:25402888

  2. Demonstration of higher colour response with ambient refractive index in Papilio blumei as compared to Morpho rhetenor

    PubMed Central

    Wang, Wanlin; Zhang, Wang; Fang, Xiaotian; Huang, Yiqiao; Liu, Qinglei; Gu, Jiajun; Zhang, Di

    2014-01-01

    Multilayer structures are known to produce vivid iridescent colouration in many butterflies. Morpho butterflies are well known for their high reflectance, which appears to remain high over a wide range of viewing angles. Thus these butterflies have served as the inspiration for sensing materials. Using microscopic images and videos, we visually demonstrate that the colour response with ambient refractive index of Papilio blumei is better than that of Morpho rhetenor. This result was also verified using measurements of the reflectance for different viewing angles. The finite-difference time-domain method was then used to simulate the microscopic pictures and reflections. Finally, the relationships between the structure, ambient refractive index, reflection and viewing angle are discussed in detail. PMID:24998707

  3. Influence of the sign of the refractive index in the reflectivity of a metamaterial surface with localized roughness

    NASA Astrophysics Data System (ADS)

    Grünhut, V.; Depine, R. A.

    2011-04-01

    To study the scattering properties of metamaterials, we generalize two scattering methods developed for conventional (non-magnetic) isotropic materials to the case of materials with arbitrary values (positive or negative) of magnetic permeability and electric permittivity. The generalized methods are used to study the changes produced in the reflectivity of a metamaterial surface with localized roughness when the relative refractive index changes sign. Our results show that, unlike the case of a plane surface whose reflectivity is unaffected by the change of sign of the relative refractive index, in rough surfaces the change of sign is manifested in the reflectivity, even for very low roughness, particularly in observation directions away from the specular direction.

  4. Negative index of refraction in a four-level system with magnetoelectric cross coupling and local field corrections

    E-print Network

    F. Bello

    2011-07-01

    This research focuses on a coherently driven four-level atomic medium with the aim of inducing a negative index of refraction while taking into consideration local field corrections as well as magnetoelectric cross coupling, i.e. chirality, within the material's response functions. Two control fields are used to render the medium transparent for a probe field which simultaenously couples to an electric and a magnetic dipole transition, thus allowing one to test the permittivity and permeability of the material at the same time. Numerical simulations show that a negative index of refraction with low absorption can be obtained for a range of probe detunings while depending on number density and the ratio between the intensities of the control fields.

  5. Negative index of refraction in a four-level system with magnetoelectric cross coupling and local field corrections

    SciTech Connect

    Bello, F. [Departament de Fisica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain)

    2011-07-15

    This research focuses on a coherently driven four-level atomic medium with the aim of inducing a negative index of refraction while taking into consideration local field corrections as well as magnetoelectric cross coupling (i.e.,chirality) within the material's response functions. Two control fields are used to render the medium transparent for a probe field which simultaneously couples to an electric and a magnetic dipole transition, thus allowing one to test the permittivity and permeability of the material at the same time. Numerical simulations show that a negative index of refraction with low absorption can be obtained for a range of probe detunings while depending on number density and the ratio between the intensities of the control fields.

  6. Negative index of refraction in a four-level system with magnetoelectric cross coupling and local field corrections

    E-print Network

    Bello, F

    2011-01-01

    This research focuses on a coherently driven four-level atomic medium with the aim of inducing a negative index of refraction while taking into consideration local field corrections as well as magnetoelectric cross coupling, i.e. chirality, within the material's response functions. Two control fields are used to render the medium transparent for a probe field which simultaenously couples to an electric and a magnetic dipole transition, thus allowing one to test the permittivity and permeability of the material at the same time. Numerical simulations show that a negative index of refraction with low absorption can be obtained for a range of probe detunings while depending on number density and the ratio between the intensities of the control fields.

  7. Single mode tapered fiber-optic interferometer based refractive index sensor and its application to protein sensing.

    PubMed

    Yadav, T K; Narayanaswamy, R; Abu Bakar, M H; Kamil, Y Mustapha; Mahdi, M A

    2014-09-22

    We demonstrate refractive index sensors based on single mode tapered fiber and its application as a biosensor. We utilize this tapered fiber optic biosensor, operating at 1550 nm, for the detection of protein (gelatin) concentration in water. The sensor is based on the spectroscopy of mode coupling based on core modes-fiber cladding modes excited by the fundamental core mode of an optical fiber when it transitions into tapered regions from untapered regions. The changes are determined from the wavelength shift of the transmission spectrum. The proposed fiber sensor has sensitivity of refractive index around 1500 nm/RIU and for protein concentration detection, its highest sensitivity is 2.42141 nm/%W/V. PMID:25321749

  8. Role of resonant refractive-index grating in a nonreciprocal Nd:YAG self-pumped phase conjugator

    NASA Astrophysics Data System (ADS)

    Antipov, Oleg L.; Chausov, Dmitry V.; Yarovoy, Vladimir V.

    2001-03-01

    We have studied both experimentally and numerically the role of resonant refractive index gratings in a self-pumped phase conjugate mirror based on an Nd:YAG amplifier with nonreciprocal feedback loop. In experiment the generation of the phase-conjugating laser was delayed with respect to recording of a holographic nonlinear mirror by an external beam. An increase in the phase-conjugate reflectivity at a delay time of about 3 microseconds was measured. The numerical calculation confirmed the additional contribution of the resonant refractive-index grating, which is formed in the pumped Nd:YAG crystal due to excitation of a higher-lying level of Nd3+ ions, to efficiency of phase conjugation.

  9. High-resolution electrohydrodynamic jet printing for the direct fabrication of 3D multilayer terahertz metamaterial of high refractive index

    NASA Astrophysics Data System (ADS)

    Teguh Yudistira, Hadi; Pradhipta Tenggara, Ayodya; Oh, Sang Soon; Nguyen, VuDat; Choi, Muhan; Choi, Choon-gi; Byun, Doyoung

    2015-04-01

    The fabrication of 3D metamaterials, such as multilayer structures, is of great interest in practical applications of the metamaterial. Here we present an electrohydrodynamic jet printing technique as a direct fabrication method of 3D multilayer metamaterial. By alignment of the nozzle movement, we could fabricate multiple layers of the metamaterial. Controlling an electrical pulse to make droplets on-demand, we fabricated a high refractive index metamaterial and compared the optical performances of a single layer and multiple layers, with 10?µm width and 5?µm gap of I-shaped meta-atoms on the polyimide substrate. The peak refractive index was 25.7 at 0.46?THz for a four-layer metamaterial.

  10. Effect of the refractive index on the hawking temperature: an application of the Hamilton-Jacobi method

    NASA Astrophysics Data System (ADS)

    Sakalli, I.; Mirekhtiary, S. F.

    2013-10-01

    Hawking radiation of a non-asymptotically flat 4-dimensional spherically symmetric and static dilatonic black hole (BH) via the Hamilton-Jacobi (HJ) method is studied. In addition to the naive coordinates, we use four more different coordinate systems that are well-behaved at the horizon. Except for the isotropic coordinates, direct computation by the HJ method leads to the standard Hawking temperature for all coordinate systems. The isotropic coordinates allow extracting the index of refraction from the Fermat metric. It is explicitly shown that the index of refraction determines the value of the tunneling rate and its natural consequence, the Hawking temperature. The isotropic coordinates in the conventional HJ method produce a wrong result for the temperature of the linear dilaton. Here, we explain how this discrepancy can be resolved by regularizing the integral possessing a pole at the horizon.

  11. Effect of the refractive index on the hawking temperature: an application of the Hamilton-Jacobi method

    SciTech Connect

    Sakalli, I., E-mail: izzet.sakalli@emu.edu.tr; Mirekhtiary, S. F., E-mail: fatemeh.mirekhtiary@emu.edu.tr [Eastern Mediterranean University G. Magosa, Department of Physics (Turkey)

    2013-10-15

    Hawking radiation of a non-asymptotically flat 4-dimensional spherically symmetric and static dilatonic black hole (BH) via the Hamilton-Jacobi (HJ) method is studied. In addition to the naive coordinates, we use four more different coordinate systems that are well-behaved at the horizon. Except for the isotropic coordinates, direct computation by the HJ method leads to the standard Hawking temperature for all coordinate systems. The isotropic coordinates allow extracting the index of refraction from the Fermat metric. It is explicitly shown that the index of refraction determines the value of the tunneling rate and its natural consequence, the Hawking temperature. The isotropic coordinates in the conventional HJ method produce a wrong result for the temperature of the linear dilaton. Here, we explain how this discrepancy can be resolved by regularizing the integral possessing a pole at the horizon.

  12. Demonstration of higher colour response with ambient refractive index in Papilio blumei as compared to Morpho rhetenor

    NASA Astrophysics Data System (ADS)

    Wang, Wanlin; Zhang, Wang; Fang, Xiaotian; Huang, Yiqiao; Liu, Qinglei; Gu, Jiajun; Zhang, Di

    2014-07-01

    Multilayer structures are known to produce vivid iridescent colouration in many butterflies. Morpho butterflies are well known for their high reflectance, which appears to remain high over a wide range of viewing angles. Thus these butterflies have served as the inspiration for sensing materials. Using microscopic images and videos, we visually demonstrate that the colour response with ambient refractive index of Papilio blumei is better than that of Morpho rhetenor. This result was also verified using measurements of the reflectance for different viewing angles. The finite-difference time-domain method was then used to simulate the microscopic pictures and reflections. Finally, the relationships between the structure, ambient refractive index, reflection and viewing angle are discussed in detail.

  13. Anneal-induced enhancement of refractive index and hardness of silicophosphate glasses containing six-fold coordinated silicon

    NASA Astrophysics Data System (ADS)

    Zeng, Huidan; Jiang, Qi; Li, Xiang; Ye, Feng; Tian, Tian; Zhang, Haoxuan; Chen, Guorong

    2015-01-01

    A considerable number of optical devices have significantly benefited from the development of phosphate glasses as substrate materials. Introducing silica into sodium phosphate is an effective method to enhance its mechanical and optical properties. Through annealing treatment, the tetrahedral silicon oxide network structure (Si(4)) can be transformed into an octahedral structure (Si(6)) with more constraints. Here, we use high-temperature Raman and Nuclear Magnetic Resonance to reveal the mechanism of transformation between the Si(4) and Si(6) silicon oxide structures. The increase of the Si(6) content results in the phosphate glasses having higher refractive index and hardness. Based on this, the refractive index contribution of SiO6 is obtained.

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

    SciTech Connect

    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.

  15. Polarizability, volume expansion, and stress contributions to the refractive index change of Cu+-Na+ ion exchanged waveguides in glass.

    PubMed

    Oven, Robert

    2011-09-10

    The refractive index of optical waveguides formed by electric field assisted Cu(+)-Na(+) ion exchange in two types of glass is measured. Assuming, as in a previously published work, that the observed refractive index increase is solely due to polarizability changes, the difference in electronic polarizability between Cu(+) and Na(+) ions is determined by applying the Lorentz-Lorenz equation to the data. In our work, the concentration of exchanged ions, which is a necessary input to the Lorentz-Lorenz equation, is determined by combining optical data and electrical data obtained during the exchange. Values for the electronic polarizability difference are in agreement with that in the literature. However, when a correction is made, taking into consideration the measured volume expansion and stress in the glass, the calculated electronic polarizability difference is shown to increase by 19%. PMID:21946987

  16. A fiber tip refractive index sensor using FIB-milled gold-coated singlemode-multimode-singlemode structure

    NASA Astrophysics Data System (ADS)

    Ding, Ming; Wang, Pengfei; Wang, Junlong; Yuan, Heng; Brambilla, Gilberto

    2014-05-01

    A compact fiber tip refractive index sensor using FIB-milled gold-coated singlemode-multimode-singlemode structure is demonstrated. Focused ion beam (FIB) is exploited to cut the fiber tip to obtain a flat end-face and then a layer of gold is coated on the tip surface, to increase its reflection. An average sensitivity of 265 nm/RIU is obtained experimentally with a ~2.94 ?m diameter singlemode-multimode-singlemode fiber tip (SMST). Because of several advantages, including compactness, ease of fabrication, linear response, high sensitivity, easy connection with other fiberized optical components and low cost, this refractive index sensor could find various applications in chemical and biological area.

  17. Influence of the sign of the refractive index in the reflectivity of a metamaterial surface with localized roughness

    E-print Network

    Grunhut, Vivian

    2011-01-01

    To study the scattering properties of metamaterials, we generalize two scattering methods developed for conventional (non-magnetic) isotropic materials to the case of materials with arbitrary values (positive or negative) of magnetic permeability and electric permittivity. The generalized methods are used to study the changes in the reflectivity of a metamaterial surface with localized roughness when the relative refractive index changes sign. Our results show that, unlike the case of a plane surface whose reflectivity is unaffected by the change of sign of the relative refractive index, in rough surfaces the change of sign is manifested in the reflectivity, even for very low roughness, particularly in observation directions away from the specular direction.

  18. Stack of PECVD silicon nitride nano-films on optical fiber end-face for refractive index sensing

    NASA Astrophysics Data System (ADS)

    ?mietana, Mateusz; Koba, Marcin; Ró?ycki-Bakon, Radoslaw

    2014-05-01

    This paper presents a stack of silicon nitride (SiNx) nano-films deposited with radio-frequency plasma-enhanced chemical deposition (RF PECVD) method on single-mode fiber end-face for refractive index (RI) sensing. The stack consist of high (n~2.4) and low (n~1.9) refractive index (at ?=1550 nm) SiNx nano-films arranged alternately. As a result of the experiment where 5 nano-layers were deposited, we received down to -30 dB-deep resonance in reflection spectrum at about ?=1550 nm. In the proposed sensing scheme both reflected power and wavelength of the resonance can be used for external RI measurements.

  19. Z-scan measurements of the nonlinear refractive index of a pumped semiconductor disk laser gain medium

    NASA Astrophysics Data System (ADS)

    Quarterman, A. H.; Tyrk, M. A.; Wilcox, K. G.

    2015-01-01

    We measure the nonlinear refractive index of an antiresonant 1050 nm semiconductor disk laser (SDL) gain medium using a reflection-type z-scan system, with a 1064 nm, 10-ps-pulse laser as a probe, and a fiber-coupled 808 nm diode pump laser for carrier injection. Empirically, the nonlinear refractive index is found to depend approximately linearly on applied pump intensity, having a value of -1.5(0.2) × 10-12 cm2/W at zero excitation but increasing to take on positive values at typical SDL operating conditions. The focal lengths of corresponding Kerr lenses calculated using typical SDL pulse intensities and spot sizes are sufficiently short to be comparable to SDL cavity mirrors, implying that Kerr lens modelocking may be responsible for the behavior described in recent reports of self-mode-locked SDLs.

  20. Combined use of Satellite and Surface Observations to Infer the Imaginary Part of Refractive Index of Saharan Dust

    NASA Technical Reports Server (NTRS)

    Sinyuk, Alexander; Torres, Omar; Dubovik, Oleg; Bhartia, P. K. (Technical Monitor)

    2002-01-01

    We present a method for retrieval of imaginary part of refractive index of desert dust aerosol in UV part of spectrum along with aerosol layer height above the ground. The method uses Total Ozone Mapping Spectrometer' (TOMS) measurements of the top of atmosphere radiances (331 nm, 360 nm) and aerosol optical depth provided by Aerosol Robotic Network (AERONET) (440 nm). Obtained values of imaginary part of refractive index retrieved for Saharan dust aerosol at 360 nm are significantly lower than previously reported values. The average retrieved values vary between 0.0054 and 0.0066 for different geographical locations. Our findings are in good agreement with the results of several recent investigations. The time variability of retrieved values for aerosol layer height is consistent with the predictions of dust transport model.