Showing papers on "Waveplate published in 2008"

Miniature plasmonic wave plates

Abstract: Linear birefringence, as implemented in wave plates, is a natural way to control the state of polarization of light. We report on a general method for designing miniature planar wave plates using surface plasmons. The resonant optical device considered here is a single circular aperture surrounded by an elliptical antenna grating. The difference between the short and long axis of each ellipsis introduces a phase shift on the surface plasmons which enables the realization of a quarter wave plate. Furthermore, the experimental results and the theoretical analysis show that the general procedure used does not influence the optical coherence of the polarization state and allows us to explore completely the surface of the unit Poincare sphere by changing only the shape of the elliptical grating.

One-shot phase-shifting phase-grating interferometry with modulation of polarization: case of four interferograms.

Abstract: An experimental setup for optical phase extraction from 2-D interferograms using a one-shot phase-shifting technique able to achieve four interferograms with 90° phase shifts in between is presented. The system uses a common-path interferometer consisting of two windows in the input plane and a phase grating in Fourier plane as its pupil. Each window has a birefringent wave plate attached in order to achieve nearly circular polarization of opposite rotations one respect to the other after being illuminated with a 45° linear polarized beam. In the output, interference of the fields associated with replicated windows (diffraction orders) is achieved by a proper choice of the windows spacing with respect to the grating period. The phase shifts to achieve four interferograms simultaneously to perform phase-shifting interferometry can be obtained by placing linear polarizers on each diffraction orders before detection at an appropriate angle. Some experimental results are shown.

Detector configurations for optical metrology

Abstract: An apparatus is disclosed for obtaining ellipsometric measurements from a sample. A probe beam is focused onto the sample to create a spread of angles of incidence. The beam is passed through a quarter waveplate retarder and a polarizer. The reflected beam is measured by a detector. In one preferred embodiment, the detector includes eight radially arranged segments, each segment generating an output which represents an integration of multiple angle of incidence. A processor manipulates the output from the various segments to derive ellipsometric information.

The Silicon Backplane Design for an LCOS Polarization-Insensitive Phase Hologram SLM

Abstract: Polarization-insensitivity is achieved in a reflective spatial light modulator by laying a quarter-wave plate (QWP) at the incident wavelength directly over the mirror pixels of a silicon backplane, and forming a nematic Freedrickcz cell over the QWP to modulate the reflected phase. To achieve the highest drive voltage from the available silicon process, a switched voltage common front electrode design is described, with variable amplitude square wave drive to the pixels to maintain constant root-mean-square drive and minimize phase fluctuations during the dc balance refresh cycle. The silicon has been fabricated and liquid-crystal-on-silicon cells both with and without the QWP assembled; applications include optically transparent switches for optical networks, beam steering for add-drop multiplexers for wavelength-division-multiplexing telecommunications, television multicast, and holographic projection.

Polarization ellipticity compensation in polarization second-harmonic generation microscopy without specimen rotation

Abstract: In imaging anisotropic samples with optical microscopy, a controlled, polarized light source can be used to gain molecular information of fibrous materials such as muscles and collagen fibers. However, the delivery of the polarized excitation light source in a system such as a laser scanning optical microscope often encounters the problem of the polarization ellipticity altering effects of the optical components. Using a half-wave plate and a quarter-wave plate, we demonstrate that the polarization ellipticity altering effect of the dichroic mirror in an epi-illuminated multiphoton laser scanning microscope can be corrected, and that this approach can be used to obtain polarized second-harmonic generation (SHG) images of rat tail tendon and mouse leg muscle. The excitation polarization dependence of the SHG intensity is fitted to determine the ratio of the second-order susceptibility tensor elements associated with type I collagen in the rat tail tendon and myofibril in the mouse leg muscle. Our methodology can be applied to polarized SHG imaging without sample rotation. This approach has great potential for imaging noncentrosymmetric biological samples, providing structural information on the molecular scale in addition to morphological information of tissues.

z‐Polarization sensitive detection in micro‐Raman spectroscopy by radially polarized incident light

Abstract: We demonstrate z-polarization sensitive detection in micro-Raman spectroscopy by introducing a radially distributed polarized light and by employing a high numerical aperture objective lens and circular mask. The radial polarization is provided by a radial-waveplate consisting of an 8-way segmented half-waveplate with each segment having a different orientation of the optical axis. The segmented waveplate allows for both z-polarization (perpendicular to the sample plane) and xy-polarization (parallel to the sample plane) of the electric field at the focus by selecting the proper polarization of the incident field. The z-polarization Raman components that are barely detectable in conventional measurements can be clearly observed in this experimental setup. Alpha-quartz, which is well known in terms of polarized Raman spectroscopy, is utilized as a test sample. We have succeeded in extracting the z-Raman tensor components, and the intensity ratio of each measured tensor value in our experiment is in good agreement with previously reported work. The Raman spectral intensity ratios are greatly modified when observed under polarization control, and we can clearly see a small isolated Raman peak that usually appears only as a shoulder of a strong neighboring peak. The effect of the confocal detection setup on the accuracy of depolarization measurements is also discussed and the relationship between the depolarization ratio and pinhole size is shown. In this research, we aim to provide a solid basis for z-polarization imaging in a micro-Raman configuration under high numerical aperture objective lenses. Copyright © 2008 John Wiley & Sons, Ltd.

High speed interferometric ellipsometer

Abstract: A novel high speed interferometric ellipsometer (HSIE) is proposed and demonstrated. It is based on a novel differential-phase decoder which is able to convert the phase modulation into amplitude modulation in a polarized heterodyne interferometer. Not only high detection sensitivity but also fast response ability on ellipsometric parameters (EP) measurements based on amplitude-sensitive method is constructed whereas different amplitudes with respect to P and S polarized heterodyne signals in this phase to amplitude modulation conversion is discussed. The ability of HSIE was verified by testing a quarter wave plate while a real time differential-phase detection of a liquid crystal device versus applied voltage by using HSIE was demonstrated too. These results confirm that HSIE is able to characterize the optical property of specimen in terms of EP at high speed and high detection sensitivity experimentally.

The submillimeter array polarimeter

Abstract: We describe the Submillimeter Array (SMA) Polarimeter, a polarization converter and feed multiplexer installed on the SMA. The polarimeter uses narrow-band quarter-wave plates to generate circular polarization sensitivity from the linearly-polarized SMA feeds. The wave plates are mounted in rotation stages under computer control so that the polarization handedness of each antenna is rapidly selectable. Positioning of the wave plates is found to be highly repeatable, better than 0.2 degrees. Although only a single polarization is detected at any time, all four cross correlations of left- and right-circular polarization are efficiently sampled on each baseline through coordinated switching of the antenna polarizations in Walsh function patterns. The initial set of anti-reflection coated quartz and sapphire wave plates allows polarimetry near 345 GHz; these plates have been have been used in observations between 325 and 350 GHz. The frequency-dependent cross-polarization of each antenna, largely due to the variation with frequency of the retardation phase of the single-element wave plates, can be measured precisely through observations of bright point sources. Such measurements indicate that the cross-polarization of each antenna is a few percent or smaller and stable, consistent with the expected frequency dependence and very small alignment errors. The polarimeter is now available for general use as a facility instrument of the SMA.

Simultaneous generation of helical beams with linear and radial polarization by use of a segmented half-wave plate

Abstract: Simultaneous generation of helical beams with linear and radial polarization is demonstrated by use of a segmented half-wave plate in a Ti:sapphire laser cavity. A linearly polarized Laguerre-Gaussian beam is converted to a radially polarized beam with a spiral phase shift and vice versa. In addition, these two beams coexist in the cavity, and the cavity emits one of these two beams from an output coupler.

Ultrafast gaseous “half-wave plate”

Abstract: We demonstrate that filaments generated by ultrashort laser pulses can induce a remarkably large birefringence in Argon over its whole length, resulting in an ultrafast “half-wave plate” for a copropagating probe beam. This birefringence originates from the difference between the nonlinear refractive indices induced by the filament on the axes parallel and orthogonal to its polarization. An angle of 45° between the filament and the probe polarizations allows the realization of ultrafast Kerr-gates, with a switching time ultimately limited by the duration of the filamenting pulse.

Space-Variant Liquid Crystal Waveplate

Abstract: The invention provides a space-variant liquid-crystal (LC) photo-aligned waveplate having a vortex optic axis pattern, and an apparatus and method for fabricating thereof. The method in it preferred embodiment includes exposing a substrate coated with a photo-alignable material such as LPP to linearly polarized UV radiation through a wedge-shaped aperture, while rotating two of the aperture, the substrate and the polarization of the UV light, so that an exposure area performs a full rotation about a center point on the substrate, at angular velocities selected so as to form a vortex alignment pattern of a pre-defined order. An LC material is then deposited on the substrate in direct contact with the photo-alignable material so that the LC director is aligned according to the photo-induced vortex alignment pattern. The method enables to fabricate vortex waveplate of any pre-defined vortex order.

Noise reduction in a laser polarimeter based on discrete waveplate rotations.

Abstract: While several analyses of polarimeter noise-reduction have been published, little data has been presented to support the analytical results, particularly for a laser polarimeter based on measurements taken at discrete, independent rotation angles of two birefringent waveplates. This paper derives and experimentally demonstrates the reduction of both system and speckle noise in this type of laser polarimeter, achieved by optimizing the rotation angles of the waveplates by minimizing the condition numbers of the appropriate matrix equation. Results are demonstrated experimentally in signal-to-noise ratio (SNR) variations for a range of materials and spatial bandwidths. Use of optimal waveplate angles is found to improve the average SNR of the normalized Mueller matrix over speckle by a factor of up to 8 for a non-depolarizing material, but to provide little improvement for a depolarizing material. In the limit of zero spatial bandwidth, the average SNR of the normalized Mueller matrix over speckle is found to be greater than one for a non-depolarizing material and less than one for a depolarizing material.

Error Analysis of a Rotating Quarter-Wave Plate Stokes' Polarimeter

Abstract: A simple polarimeter based on a quarter-wave plate and a polarizer is presented. All Stokes' vector components are calculated by rotating the quarter-wave plate and processing the resultant intensity variation. The effect of misalignment in the linear polarizer azimuth and the deviation from the pi/2 retardance of the quarter-wave plate is analytically and experimentally investigated. The technique has been verified with two algorithms for Stokes' vector calculation.

Method for the measurement of phase retardation of any wave plate with high precision

Abstract: We present a measuring method for any wave plate retardation with fairly high precision that utilizes a laser frequency splitting technique. To avoid strong mode competition in measuring half and full wave plates, we use two separate methods: comparing adjacent longitudinal mode spacing, and phase offset with an additional quarter wave plate. Therefore any wave plate can be characterized by a single instrument, and no complicated experimental arrangement or data analysis is required. The performance of the system is demonstrated by determining the phase retardation of several samples to a precision and repeatability better than lambda/10(4); moreover, an error analysis is proposed.

Polarization-Insensitive Operation of Lithium Niobate Mach–Zehnder Interferometer With Silica PLC-Based Polarization Diversity Circuit

Abstract: We demonstrate the polarization-insensitive operation of a Mach-Zehnder interferometer (MZI)-based lithium niobate switch with a silica waveguide polarization beam splitter. The splitter is composed of an MZI with a half wave plate installed in one arm, and exhibits a polarization extinction ratio of more than 15 dB. The switch functions for both polarizations with an extinction ratio of more than 20 dB, a polarization-dependent loss of 0.1 dB and a switching speed of 40 ps.

Optical Design of Multilayer Achromatic Waveplate by Simulated Annealing Algorithm

Abstract: We applied a Monte Carlo method — simulated annealing algorithm — to carry out the design of multilayer achromatic waveplate. We present solutions for three-, six- and ten-layer achromatic waveplates. The optimized retardance settings are found to be 89°51'39''±0°33'37'' and 89°54'46''±0°22'4'' for the six- and ten-layer waveplates, respectively, for a wavelength range from 1000 nm to 1800 nm. The polarimetric properties of multilayer waveplates are investigated based on several numerical experiments. In contrast to previously proposed three-layer achromatic waveplate, the fast axes of the new six- and ten-layer achromatic waveplate remain at fixed angles, independent of the wavelength. Two applications of multilayer achromatic waveplate are discussed, the general-purpose phase shifter and the birefringent filter in the Infrared Imaging Magnetograph (IRIM) system of the Big Bear Solar Observatory (BBSO). We also checked an experimental method to measure the retardance of waveplates.

Vibration detection device

Abstract: A vibration detection device includes: a light source emitting a laser beam; an interferometer including a vibrating body and a reflecting body both capable of reflecting the laser beam, a polarizing beam splitter splitting a laser beam emitted from the light source into beams traveling along first and second optical paths, a first ¼ wave plate arranged between the polarizing beam splitter and the vibrating body in the first optical path, and a second ¼ wave plate arranged between the polarizing beam splitter and the reflecting body in the second optical path, the interferometer causing interference between a reflected beam reflected by the vibrating body and a reference beam reflected by the reflecting body to form a interference pattern; and a detection means quantizing the vibration of the vibrating body on the basis of the formed interference pattern to detect the vibration.

Apparatus for implementing orbit angular momentum state super position and modulation

Abstract: The invention relates to a device for realizing superposition and modulation of orbital angular momentum states of light beams, belonging to the laser application technical field. The invention consists of a laser, a polarizer, a one-fourth wave plate, a diffraction grating, a Fourier lens, a polarized beam-splitting prism, two Dove prisms, three holophotes and a pinhole diaphragm, wherein, firstly, an optical system which takes the diffraction grating and the Fourier lens as core elements is adopted to generate a plurality of bundles of light beams which are equidistantly distributed on the circumference which takes an optical axis of incident light as the center and are positioned in different orbital angular momentum states; secondly, an optical system which consists of the polarized beam-splitting prism, the holophotes and the rotatable Dove prisms is adopted to decompose an optical field into field components which rotate towards the opposite direction; thirdly, the field components are superposed, and superposition of required orbital angular momentum states is realized and then superposition and modulation of the orbital angular momentum states are realized. The device for realizing superposition and modulation of the orbital angular momentum states of the light beams has application value in the free space optical communication field.

Illumination system and method with efficient polarization recovery

Abstract: Light provided by a light-reflective light source (102) in an illumination system having polarization recovery is collimated by a collimator (104) and transmitted through a quarter-wave retardation plate (106) to produce light having orthogonal linearly polarized components of first and second linear polarization types. A light-reflective linear polarizer (108) largely transmits the first-linear-polarization-type component and reflects the second-linear-polarization-type component which is then largely converted by the retardation plate into circularly polarized light of a first handedness and directed by the collimator to the light source to be reflected forward and converted into circularly polarized light of an opposite second handedness. The circularly polarized light of the second handedness is largely collimated by the collimator, converted by the retardation plate into linearly polarized light of the first polarization type, and transmitted through the polarizer to complete the polarization recovery. A light integrator (160 or 170) causes partial fluxes of composite light collimated by the collimator and transmitted through the retardation plate and polarizer to be mixed so as to make the light illumination more uniform.

Combined interference device for aspheric surface measurement

Abstract: A combined interference device for measurement of aspheric surface includes a laser, a spatial filter, two beam expanding systems, a beam shrinking system, a spectroscope, a convertible lens, three polarizers, two optical plates, four circular optical wedges with small wedge angle, a beam-dividing grating, a 1/4 wave plate, a polarizer group and a CCD In the device, real-time measurement is realized through simultaneous phase-shifting method, and frequency conversion function is realized through rotating two pairs of double optical wedges The experimental device adopts common optical elements, so the cost is low, and the device can measure aspheric surfaces of different diameters and is suitable for the plane and the sphere The real-time high precision measurement in conventional environment can be realized, and the invention has frequency conversion function, which is very effective for treating the mirror surface with discontinuous regions

Starch granules as a probe for the polarization at the sample plane of a high resolution multiphoton microscope

Abstract: Because of its polarization sensitivity, SHG microscopy can provide information about the orientation and degree of structural organization inside biological samples. To fully exploit the above potential, the state of the polarization at the sample plane needs to be known. In this work we present starch granules as a reliable probe for the polarization state of the excitation beam at the sample plane of a high resolution multiphoton microscope. Polarization dependent SHG series of images demonstrated the radial distribution of SHG active molecules inside starch granules. This allowed the granule to exhibit symmetrical SHG emission regions. The pattern rotates along with the rotation of a λ/2 waveplate and thus, can demonstrate the polarization at the sample plane. Maximum signal in the forward detected geometry appears when imaging starch granules exactly at the hemisphere plane. Symmetric SHG regions rotating with the incoming linear polarization were also recorded in the backward detected geometry. A portion of the backwards detected SHG signal, which corresponds to two rotating equator arcs, does not overlap with the forward SHG signal. Importantly, polarization measurements, performed either in the forward or the backwards directions, have demonstrated the suitability and flexibility of this technique for both detection schemes. As result, observation of the starch signal allowed us to know the polarization of our SHG microscope. Furthermore, by coding this information in an angular representation, we corrected the input values in a theoretical model that predicts the average orientation of SHG active molecules. This has allowed us to map the mean orientation of SHG active molecules in body walls muscle of Caenorhabditis elegans, with pixel resolution.

Anisotropic hinge model for polarization-mode dispersion in installed fibers.

Abstract: We discuss a generalized waveplate hinge model to characterize anisotropic effects associated with the hinge model of polarization-mode dispersion in installed systems. In this model, the action of the hinges is a random time-dependent rotation about a fixed axis. We obtain the probability density function of the differential group delay and the outage probability of an individual wavelength band using a combination of importance sampling and the cross-entropy method, and we then compute the noncompliant capacity ratio by averaging over wavelength bands. The results show that there are significant differences between the outage statistics predicted by isotropic and anisotropic hinge models.

Light polarization converter for converting linearly polarized light into radially polarized light and related methods

Abstract: The conversion of linear polarized light into radial-polarized light is accomplished through a radial polarization generator containing multiple layers of polarizing film, or polarization converters, for converting the beam of light to a different orientation Using the radial polarization generator, a quasi radial-polarized beam of light can be obtained quickly and easily by simply aligning the light at the center of the polarization generator True radial-polarization can be obtained by passing the laser through a spatial filter With such a radial polarization generator, a large frequency range of light may be converted from a linear orientation to a radial orientation

Concurrent measurement of linear and circular birefringence using rotating-wave-plate Stokes polarimeter

Abstract: A novel technique is presented for obtaining concurrent measurements of the linear and circular birefringence properties of an optical sample by using a rotating-wave-plate Stokes polarimeter to extract the 2×2 central elements of the corresponding Mueller matrix via two linearly polarized probe lights. For a compound sample comprising a half-wave plate in series with a quarter-wave plate, the measured values of the principal angle and retardance of the quarter-wave plate are found to have average normalized errors of 0.56% and 1.16%, respectively, while the measured value of the rotation angle of the half-wave plate has an error of just 0.39%. When analyzing glucose solutions with concentrations ranging from 0-1.2 g/dl positioned in front of a half-wave plate, the average normalized errors in the principal axis angle and retardance measurements of the half-wave plate are 0.69% and 2.65%, respectively, while the error in the rotation angle measurements of the glucose solutions is 2.13%. The correlation coefficient between the measured rotation angle and the concentration of the glucose solution is determined to be 0.99985, while the standard deviation is just 0.0022 deg. Overall the experimental results demonstrate the ability of the proposed system to obtain highly accurate measurements of the linear and circular birefringence properties of an optical sample and to decouple the relationship between the principal axis angle and the rotation angle.

In-situ polarimetry of illumination for 193-nm lithography

Abstract: Ellipsometry is defined as a technique for determining the properties of a bulk material or a thin film, such as optical index and thickness, from the measurement of a polarization state of a reflected light or a change of polarization states between the incident and reflected lights. On the other hand, polarimetry is defined as a technique for determining a polarization state of a light. In other words, ellipsometry uses polarization as a probe and polarimetry measures polarization itself. We have constructed a theory of polarimetry of illumination used in lithography equipments, fabricated a polarimeter mask, and demonstrated it for a hyper-NA (numerical aperture) immersion lithography scanner. The polarimeter mask comprises polarizers and quarter-wave (λ/4) plates that are crammed into a narrow space with a height of 6.35 mm. The thin plate polarizers available at a wavelength of 193 nm are made of calcite, and the λ/4-plates insensitive to angle of incidence are made of four thin plates, two of which are crystalline quartz; the other two are sapphire. A light traveling through a window of the polarimeter mask reaches an image detector at the wafer level through projection optics. Stokes parameters of the illumination light can be measured without any influence from polarization characteristics of the projection optics between the mask and the image detector.

Wire grid polarizers in window shading applications and varying thickness wave retarders

Abstract: A light transmissive panel comprising a first sheet and a second sheet, wherein each sheet is made up of a non-birefringent substrate and a wire grid polarizer pattern of continuously varying absorption axis orientation formed on the non-birefringent substrate. The wire grid polarizer patterns on each of the first and second sheet are mechanically translatable relative to each other, wherein the mechanical translation controls transmission of light through the light transmissive panel. Light transmissive panels wherein each sheet of the panel is made of a wire grid polarizer that is laminated with a continuous variable thickness wave plate retarder, wherein the continuous variable thickness wave plate retarder rotates input light by an amount determined by the thickness of the wave plate retarder.

Complementary waveplate rotating compensator ellipsometer

Abstract: Ellipsometry using two waveplates of complementary retardation in a dual rotating compensator configuration is disclosed. Two waveplates of complementary retardation may be used to increase the useful spectral range of a rotating compensator ellipsometer, in particular towards the deep Ultraviolet (UV) spectrum. The improved rotating compensating ellipsometer disclosed herein enables a user to select specific and different waveplate retardations for the purpose of increasing the operating wavelength range of the rotating compensating ellipsometer.

Microfabricated optical wave plate

Abstract: A microfabricated optical wave plate comprises a reflective polarizer and a mirror separated by a fixed or variable distance. The wave plate imparts a relative phase delay on polarization components of incident light, thereby transforming the overall polarization of the light.

Diffraction grating array outer cavity semiconductor laser line array

Abstract: The utility model relates to an outer cavity semiconductor laser linear array of a diffraction grating array, belonging to the field of semiconductor laser, which comprises a semiconductor laser linear array, a fast axis collimation lens, a lens, a half wave plate, a lens, a diffraction grating array and diffraction grating units. The laser array is characterized in that the diffraction grating array is used for carrying out outer cavity feedback and leading one or a plurality of lighting units of the semiconductor laser linear array to enter one diffraction grating unit; by means of regulating each diffraction grating unit, feedback light of the lighting units with different bending degree returned along the original path after the lighting units goes through the diffraction unit has similar central wavelength; therefore, the output light of the lighting units with different bending degrees has similar central wavelength, and the total spectral line width is decreased. The laser linear array has the advantages of smaller grating area, convenient processing and optical path regulation, low cost and corresponding improvement of output power.

Essentials of Photonics

Abstract: Photons and Electrons Historical Sketch The Wave Nature of Light Polarization The Electromagnetic Spectrum Emission and Absorption Processes Photon Statistics The Behaviour of Electrons Lasers Summary Wave Properties of Light The Electromagnetic Spectrum Wave Representation Electromagnetic Waves Reflection and Refraction Total Internal Reflection Interference of Light Light Waveguiding Interferometers Diffraction Gaussian Beams and Stable Optical Resonators Polarization Optics The Polarization Ellipse Crystal Optics Retarding Waveplates A Variable Waveplate: The Soleil-Babinet Compensator Polarizing Prisms Linear Birefringence Circular Birefringence Elliptical Birefringence Practical Polarization Effects Polarization Analysis The Form of the Jones Matrices Light and Matter Emission, Propagation, and Absorption Processes Classical Theory of Light Propagation in Uniform Dielectric Media Optical Dispersion Emission and Absorption of Light Optical Coherence and Correlation Introduction Measure of Coherence Wiener-Khinchin Theorem Dual-Beam Interference Practical Examples Some Essential Physics of Radiation and Solids Radiation Electrons in Solids Optical Sources, Modulators, and Detectors Optical Sources Optical Modulators Photodetectors Optical Waveguides The Planar Waveguide Integrated Optics Cylindrical Waveguides Optical Fibres Optical Fibres for Communications Polarization-Holding Waveguides Photonic Crystal Fibres Nonlinear Optics Nonlinear Optics and Optical Fibres The Formalism of Nonlinear Optics Second-Harmonic Generation and Phase Matching Optical Mixing Intensity-Dependent Refractive Index Four-Photon Mixing (FPM) Parametric and Inelastic Processes Solitons Photosensitivity Non-Linear Effects in Photonic Crystal Fibres (PCF) Photonics in Action Antireflective Coatings Optical-Fibre Current Measurement The Integrated Optical Spectrum Analyser The Audio Compact Disc (CD) The Optical-Fibre Gyroscope Holography Optical-Time-Domain Reflectometry (OTDR) and Its Use in Distributed Optical-Fibre Raman Temperature Sensing (DTS) Measurement of Very Short Optical Pulses: The Autocorrelator Topics in Optical-Fibre Communications Regimes-Correlation Length Epilogue And What of the Future? Appendices Appendix I: Maxwell's Equations Appendix II: The Fourier Inversion Theorem Appendix III: Symmetry of the Permittivity Tensor Appendix IV: The Polarization Ellipse Appendix V: Radiation from an Oscillating Dipole Appendix VI: The d-Function Appendix VII: The Fermi-Dirac Function Appendix VIII: Second Harmonic Generation Appendix IX: The Sampling Theorem Appendix X: The Semiconductor Equation Appendix XI: The Formal Analysis of Polarization-Mode Dispersion (PMD) References Each chapter includes an introduction, conclusion, problems, references, and suggestions for further reading