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Showing papers on "Polarization rotator published in 1999"


Journal ArticleDOI
Franco Gori1
TL;DR: It is shown that, for a generic polarization state of the incident field, such a grating gives rise to first-order diffracted beams with counterrotating circular polarizations and can be used for measuring the Stokes parameters of a light beam in an achromatic manner.
Abstract: Ordinary gratings act on the amplitude and (or) the phase of a wave front. Polarization gratings produce instead a periodic modulation of the state of polarization. A simple grating of the latter type is constituted by a linear polarizer whose orientation varies periodically along a line. It is shown that, for a generic polarization state of the incident field, such a grating gives rise to first-order diffracted beams with counterrotating circular polarizations. It is also shown that such a grating can be used for measuring the Stokes parameters of a light beam in an achromatic manner. Several extensions are briefly discussed.

294 citations


Journal ArticleDOI
TL;DR: In this paper, the variation of the birefringence with input polarization and input power is measured, and an optical control of the BIR can be applied to wavelength conversion, signal regeneration, all-optical switching or gating.
Abstract: The polarization sensitivity of semiconductor optical amplifiers can be assessed in terms of gain or in terms of induced phase shift. Although the former aspect has received a lot of attention, the latter is rarely mentioned in the literature. Nevertheless, this birefringence leading to a rotation of the lightwave polarization at the output of the device may give rise to some interesting or unwanted effects. An optical control of the birefringence can be applied to wavelength conversion, signal regeneration, all-optical switching or gating. In this letter, the variation of the birefringence with input polarization and input power is measured.

147 citations


Journal ArticleDOI
TL;DR: In this article, a low-level linear birefringence photoelastic modulator was used to measure the magnitude and angle of the fast axis of a He-Ne laser beam.
Abstract: This article describes a sensitive method for measuring both the magnitude and the angle of the fast axis of low level linear birefringence in optical materials. Several different approaches have been investigated and one of them has been chosen as the basis for a linear birefringence measurement instrument. The instrument employs a low birefringence photoelastic modulator for modulating the polarization states of a He–Ne laser beam. After the modulated laser beam passes through the sample, two detecting channels analyze the polarization change caused by the sample. An algorithm has been developed to calculate the magnitude and angle of the retardance in a sample. A computer program implements the algorithm and displays the calculated values. Using this instrument, selected samples with different levels of linear birefringence have been studied. The resulting instrument achieves high precision and sensitivity for the final measurements. The sensitivity of the magnitude of linear birefringence is better than 0.005 nm (∼0.003 ° with a He–Ne laser at 632.8 nm), and the sensitivity of the fast axis angle of the sample is <1 ° (for retardance ⩾0.5 nm).

129 citations


Journal ArticleDOI
TL;DR: This work describes how to calculate the Jones matrix transfer function of a fiber if its principal states of polarization and its differential group delay as functions of frequency are known and shows that a previous method used for this purpose induces overestimation of second-order PMD effects.
Abstract: We describe how to calculate the Jones matrix transfer function of a fiber if its principal states of polarization and its differential group delay as functions of frequency are known. Using two counterexamples related to second-order polarization mode dispersion (PMD), we also show that a previous method used for the same purpose induces overestimation of second-order PMD effects by a factor of 2. Our new method is used to solve the problem for both counterexamples.

124 citations


Journal ArticleDOI
TL;DR: In this paper, the authors show that compensation sharpens the probability distribution function of the pulse durations by a factor that decreases with increasing polarization dispersion, and that compensation can be achieved by using principal states of polarization.
Abstract: Polarization mode dispersion in standard telecommunication fibers can be compensated to first order by using the concept of principal states of polarization. At the receiver the pulse is decomposed into the two waveforms polarized along the two principal states for the optical link and their delay is removed. We show by Monte Carlo simulation that compensation sharpens the probability distribution function of the pulse durations by a factor that decreases with increasing polarization dispersion.

109 citations


Journal ArticleDOI
TL;DR: A polarization controller capable of changing any state of polarization of light from one arbitrary state to another, developed in the framework of the Stokes parameters, allowing easy visualization by use of a Poincaré sphere representation.
Abstract: In this Letter we demonstrate a polarization controller capable of changing any state of polarization of light from one arbitrary state to another. The controller consists of a stack of three homogeneous nematic liquid-crystal cells. The polarization state is controlled by proper adjustment of the voltages applied across each of the cells. The mathematical algorithm and principles of this polarization controller are developed in the framework of the Stokes parameters, allowing easy visualization by use of a Poincare sphere representation. The transformation functions are given for conversion of an arbitrary input state to any output state. Experiments are carried out to demonstrate arbitrary polarization transformation.

101 citations


Journal ArticleDOI
TL;DR: In this paper, the authors describe the polarization evolution in a fiber by one of the three general formalisms: by the Jones vectors and matrices formalism, by the Stokes vectors and Mueller matrices (SVM) formalism or by the Poincare sphere representation.
Abstract: Optical fibers exhibit particular polarization properties. The guided electromagnetic fields in optical fiber waveguides are called inhomogeneous plane waves since their amplitudes are not stable within the plane wave and the fields are characterized, in most cases, by non-transverse components. In the description of polarization phenomena in optical fibers there are generally two approaches [1]. The first one treats an optical fiber as an optical waveguide in which light being a kind of electromagnetic wave of optical frequencies can be guided in the form of waveguide modes. This approach identifies basic polarization eigenmodes of a fiber and relates them to the polarization state of the guided light. Changes in output polarization are described in terms of polarization-mode coupling due to birefringence changes acting as perturbations along the fiber. Another approach treats an optical fiber like any other optical device which transmits light and the fiber can be divided into separated sections behaving like . polarization state shifters. Here, polarization evolution in a fiber can be described by one of the three general formalisms: by the Jones vectors and matrices formalism, by the Stokes vectors and Mueller matrices formalism, or by the Poincare sphere representation. Since optical fibers allow very large propagation distances even very small birefringence effects can cumulate along fiber and their random distribution over the large lengths causes polarization properties of guided light generally difficult to determine. Although polarization effects in optical fibers have initially played a minor role in the development of light-wave systems their importance is still growing. Before 1980 it was impossible to exploit the polarization modulation in a fiber for

97 citations


Journal ArticleDOI
TL;DR: The polarization properties of concatenations of trunks of birefringent fibers and elements with polarization-dependent losses are analyzed and it is shown both theoretically and experimentally that the concatenation can have zero differential group delay over a whole range of wavelengths but that a pulse propagating down the concattenation can still experience significant pulse spreading.
Abstract: The polarization properties of concatenations of trunks of birefringent fibers and elements with polarization-dependent losses are analyzed We show both theoretically and experimentally that the concatenation can have zero differential group delay over a whole range of wavelengths but that a pulse propagating down the concatenation can still experience significant pulse spreading In this example the two main methods used for characterizing polarization mode dispersion in optical fiber systems, ie, Jones matrix eigenanalysis and the interferometric method, give different results This counterintuitive example underlines the need for a careful assessment of the basic concepts related to polarization effects in the presence of polarization-dependent losses

96 citations


Journal ArticleDOI
TL;DR: In this paper, the polarization dynamics of optically pumped vertical-cavity surface-emitting laser (VCSELs) with a pump light of arbitrary polarization ellipticity were investigated.
Abstract: We consider the polarization dynamics of optically pumped vertical-cavity surface-emitting lasers (VCSELs) with a pump light of arbitrary polarization ellipticity. We also consider the effect of an applied transverse magnetic field on the polarization properties of the output light. We first test our theoretical description by analyzing the polarization state of the photoluminescence light emitted by an optically pumped quantum well, and discuss a variety of phenomena known to originate from spin carrier dynamics in these materials. We discuss how these phenomena are modified when a VCSEL is operated above threshold, and we show that our model gives a good description of Larmor oscillations observed in VCSELs excited with short optical pulses. For VCSELs under continuous optical pump, we find a number of accessible experimental situations in which self-sustained polarization oscillations in the emitted light are possible. We identify and analyze three different mechanisms for these oscillations to occur. When no magnetic field is applied, we find polarization oscillations governed by birefringence and undamped polarization oscillations at the relaxation oscillation frequency. With an applied magnetic field, we find self-sustained oscillations governed by the Larmor frequency. In addition, our study of optically pumped VCSELs makes apparent the effects of spin carrier dynamics in the polarization properties of the emitted light.

95 citations


Patent
08 Apr 1999
TL;DR: In this article, an optical modulator is provided to control the intensity of a transmitted or reflected light, where a separator splits arbitrarily polarized light into two polarization rays and one is made to travel a separate path from the other.
Abstract: An optical modulator is provided to control the intensity of a transmitted or reflected light. In a transmission mode, a separator splits arbitrarily polarized light into two polarization rays and one is made to travel a separate path from the other. A recombiner causes the two rays to recombine at an output unless an electro-optic phase retarder changes the polarization of the two rays, in which case, both of them miss the output by an amount which is a function of the voltage on the retarder. A normally-off version with low polarization mode dispersion is obtained by changing the orientation of the recombiner. A normally-on version with low polarization mode dispersion is obtained with a passive polarization direction rotation. Similar results can be obtained in a reflection mode where the input and output are on the same side of the modulator. Versions using a GRIN lens are particularly suited to modulation of light out of and back into fiber-optic cables. The device can be operated as a variable optical attenuator, an optical switch, or a high speed modulator and is insensitive to polarization of the input light. A preferred material for the phase retarder is a hot-pressed ceramic lead lanthanum zirconate titanate composition.

91 citations


Journal ArticleDOI
TL;DR: In this article, the Jones' matrix approach was used to predict the polarization states of transmitted and diffracted orders of polarization holographic gratings in azopolymers, and the results were nicely explained using a Jones matrix approach.
Abstract: Polarization analyses of transmitted and first-diffracted orders have been performed on photoinduced gratings in azopolymers. The polarization states of diffracted orders depend strongly on irradiation time because of the contribution from both a phase grating at short time and a surface relief grating at longer time. These results are nicely explained using a Jones’ matrix approach which predicts the polarization states of transmitted and diffracted orders of polarization holographic gratings.

Patent
Matthew S. Brennesholtz1
30 Jul 1999
TL;DR: In this paper, a broadband unpolarized white light source is used to produce a beam of polarized light, and a selective polarization filter is adapted to selectively rotate a polarization axis of a selected spectral band of light of the with respect to remaining polarized light based on a control signal.
Abstract: An imaging system, comprising a broadband unpolarized white light source ( 81 ), a polarization converter system for converting polarization axes of unpolarized white light into a substantially single polarization axis, to produce a beam of polarized light, a selective polarization filter ( 82 ), adapted to selectively rotate a polarization axis of a selected spectral band of light of the with respect to remaining polarized light based on a control signal ( 119 ), a polarized beam splitter ( 84 ), for separating light having a the substantially single polarization axis from light having a rotated polarization axis, a pair of electro-optic spatial light modulators ( 86, 89 ), disposed along a path of light within the spectral band and a path of remaining light outside the spectral band, respectively, and being adapted to modulate an image therein, and a polarized beam splitter ( 88 ), for recombining modulated light from the pair of light modulators. In a preferred embodiment, the selective polarization filter ( 82, 72 ) is divided into a plurality of regions ( 70, 71 ), each adapted to independently and selectively rotate a polarization axis of a selected spectral band of light of the with respect to remaining polarized light.

Proceedings ArticleDOI
21 Feb 1999
TL;DR: In this article, a simple and simple polarization-mode dispersion compensator based on the dynamic maximization of the degree of polarization is proposed and evaluated at 10 Gbit/s.
Abstract: We experimentally validate at 10 Gbit/s a new and simple polarization-mode dispersion compensator based on the dynamic maximization of the degree of polarization. First-order compensation is demonstrated and ultimate statistical performance is numerically assessed.

Journal ArticleDOI
TL;DR: This work analyzes polarization switching in vertical-cavity surface-emitting lasers, taking into account a proper semiconductor frequency-dependent complex susceptibility and spin-flip processes and finds that, for large birefringence, gain differences between the two linearly polarized modes are preponderant, and switching occurs owing to thermal shift.
Abstract: We analyze polarization switching in vertical-cavity surface-emitting lasers, taking into account a proper semiconductor frequency-dependent complex susceptibility and spin-flip processes. Thermal effects are included as a varying detuning, and gain differences arise from birefringence splitting. We find that, for large birefringence, gain differences between the two linearly polarized modes are preponderant, and switching occurs owing to thermal shift. For small birefringence polarization switching from the high- to the low-gain mode occurs owing to the combined effect of birefringence and semiconductor phase-amplitude-coupled dynamics for a finite value of the carrier spin-flip rate.

Journal ArticleDOI
TL;DR: In this article, a relatively comprehensive analysis of polarization evolution in depolarized interferometric fiber-optic gyroscopes is presented, together with signal fading and mean wavelength stability.
Abstract: Single-mode (SM) fiber which is used in the sensing coil of depolarized interferometric fiber-optic gyroscopes (IFOG's) does not maintain the polarization state of light. As a consequence, the state of polarization evolves freely over the length of the sensing coil and over environment. The polarization evolution is induced by birefringence within the SM coil. Variations of this birefringence may lead to nonreciprocal errors whose treatment is presented in this paper together with signal fading and the mean wavelength stability. Thus, this treatment provides a relatively comprehensive analysis of polarization evolution in depolarized gyroscopes. The analysis leads to the conclusion that the depolarized gyro architecture with two depolarizers on the opposite sides of the gyro loop must be used to obtain low-drift behaviour.

Journal ArticleDOI
TL;DR: It is concluded that, for any optical fiber that does not experience polarization-dependent gain or loss, there exist two orientations for linearly polarized light input into the optical Fiber that will also exit the fiber linearly polarization.
Abstract: A simple theoretical formalism is developed to describe the effect of transmission on linearly polarized light through a fiber with random fluctuations of birefringence. We conclude that, for any optical fiber that does not experience polarization-dependent gain or loss, there exist two orientations for linearly polarized light input into the optical fiber that will also exit the fiber linearly polarized. We report experimental results that verify this prediction and also investigate its practical implications and limitations; in particular we investigate the stability of these linearly polarized output states in laboratory conditions.

Patent
22 Dec 1999
TL;DR: In this paper, a polarization controller (PC) receives a dithering optical signal including first and second principal states of polarization (PSPs) and PMD distortion received by the PMD compensator.
Abstract: A polarization mode dispersion (PMD) compensator (10) compensates for PMD in an optical signal by an automatic tracking of a principal state of polarization (PSP). A polarization controller (PC)(22) receives a dithering optical signal including first and second principal states of polarization (PSPs) and PMD distortion received by the PMD compensator. The PC transforms the first and second PSPs into linearly polarized components, and is responsive to a feedback control signal for aligning the lenearly polarized first and second PSPs to first and second polarization axes of the PBS, respectively. A polarization beam splitter (PBS) (24) directs first polarized components of the received dithering optical signal onto a first output path, and directs second orthogonally polarized components of the received dithering optical signal onto a second output path for transmission as a PMD compensator output signal.

Journal ArticleDOI
TL;DR: In this paper, the stability and resolution of this technique was shown to be below 0.2 fs and the precision was improved by reducing the length of the down-conversion crystal and increasing the spectral band pass of the system.
Abstract: system. The stability and resolution of this technique is shown to be below 0.2 fs. We explore how this precision is improved by reducing the length of the down-conversion crystal and increasing the spectral band pass of the system.

Journal ArticleDOI
TL;DR: In this article, the vertical polarization splitters utilize birefringent polymer materials to create an adiabatic structure and achieve extinction ratios as high as 22 and 12 dB for TE and TM polarizations.
Abstract: Design considerations, fabrication procedures, and experimental results are presented for vertically integrated waveguide polarization splitters. These devices separate the TE and TM polarizations onto different vertical levels of a three-dimensionally integrated optic circuit. This provides increased integration density for polarization diverse structures. The vertical polarization splitters utilize birefringent polymer materials to create an adiabatic structure. Experimental results yielded extinction ratios as high as 22 and 12 dB for TE and TM polarizations, respectively.

Journal ArticleDOI
TL;DR: In this paper, a polarization stabilizer which employs liquid crystal (LC) rotatable waveplates was proposed for single-mode fiber (SMF) transmission systems, which is useful for optimizing the performance of polarization dependent systems or devices.
Abstract: In standard single-mode fiber (SMF) transmission systems, a polarization stabilizer is useful for optimizing the performance of polarization dependent systems or devices. We have proposed and developed a polarization stabilizer which employs liquid crystal (LC) rotatable waveplates. It has a simple configuration, no moving parts, and endless-control characteristic. High polarization stability was confirmed under various state of polarization (SOP) fluctuations. The maximum response speed of the polarization stabilizer is about 900/spl deg//s, but this can be increased by improving the controller. We applied the polarization stabilizer to a semiconductor optical amplifier (SOA) having polarization dependence, and achieved good gain stabilization.

Patent
09 Feb 1999
TL;DR: In this paper, the rotator switch was used to switch between rotating the polarization by zero degrees and by a fixed angle, β, for achromatic shutter using a planar aligned rotatable half-wave retarder.
Abstract: This invention provides a liquid crystal achromatic polarization rotator switch, and an achromatic shutter using the rotator switch. The rotator switch requires input light of a fixed orientation and switches between rotating the polarization by zero degrees and by a fixed angle, β. The achromatic shutter uses an achromatic 90-degree rotator switch positioned between a pair of polarizers. A first embodiment of the rotator switch comprises one planar-aligned rotatable smectic liquid crystal half-wave retarder in series with one passive half-wave retarder. The smectic liquid crystal cell has fixed retardance and is driven between two orientations for off- and on-states. A second embodiment of the rotator switch utilizes two variable birefringence liquid crystal cells. The variable birefringence cells having fixed orientation and variable retardance. In the off-state both retarders have zero retardance and in the on-state they have half-wave retardance.

Journal ArticleDOI
TL;DR: In this paper, the authors present various schemes for extending the novel polarization light of insertion devices with the EPU structure, which can be used in the polarization switching from a right/left circular, to a vertically linear or from a horizontally linear direction, to linear at 45°/135°, to vertically linear direction.
Abstract: This article reviews various schemes for extending the novel polarization light of insertion devices. According to this review, the “Apple-II” device associated with the Elliptically Polarized Undulator (EPU) structure can be used in the polarization switching from a horizontally linear direction, to right/left circular, to a vertically linear or from a horizontally linear direction, to linear at 45°/135°, to a vertically linear direction. Meanwhile, half period length ( λ u /2) of the phasing distance is sufficient to fulfil the various polarization modes. Also discussed herein is the optimization between the polarization rate and photon flux when tuning the energy in the different polarization modes. The derived equations predict which conditions will satisfy the corresponding polarization mode. The condition will give us how to move the phase position to obtain the various polarization modes. Additionally, the field distribution of a prototype “Apple-II” device with EPU structure is constructed and measured, verifying that the prediction correlates well with the measured results.

Journal ArticleDOI
TL;DR: In this article, the authors present a simulation result for the statistics of the polarization mode dispersion (PMD) in the presence of polarization dependent loss (PDL) in a single mode fiber.

Patent
23 Feb 1999
TL;DR: In this paper, a broadband source and a polarizer are used to measure very low levels of polarization mode dispersion of optical devices, that is inexpensive, robust and portable, comprises a broadband sources and polarizer for directing substantially completely polarized broadband light into the device under test with the polarization in a plane substantially perpendicular to the propagation direction of the light.
Abstract: Apparatus for measuring very low levels of polarization mode dispersion of optical devices, that is inexpensive, robust and portable, comprises a broadband source and a polarizer for directing substantially completely polarized broadband light into the device under test with the polarization in a plane substantially perpendicular to the propagation direction of the light. Light leaving the device is analyzed spectrally to produce a spectrum of intensity in dependence upon wavelength or frequency of such light for each of at least two mutually orthogonal polarization axes in a plane perpendicular to the propagation axis of the light leaving the device. The spectra are used to compute Stokes parameters s1, s2 and |s3| for each of a plurality of wavelengths within the bandwidth of the broadband light. The polarization mode dispersion of the device is characterized in dependence upon the Stokes parameters using one of several techniques including standard Fixed Analyzer techniques and polarimetric techniques, especially the Poincare sphere technique. The apparatus is particularly suitable for measuring PMD of components of optical telecommunications systems, including optical fibers, optical isolators, couplers, light amplifiers, and dispersion compensators.

Journal ArticleDOI
TL;DR: In this article, the Stokes parameters of light and the phase difference of two modes that describe the quantum polarization states of optical field are investigated. And the problem of determining the phase differences in two modes of optical fields for the quantum polarized states of light is discussed.
Abstract: In our paper we consider the non-classical behaviour of both the Hermitian (observable) Stokes parameters of light and the phase difference of two modes that describe the quantum polarization states of optical field. To characterize the degree of polarization of light we introduce a new quantity taking into account the quantum properties of different quantum states of two orthogonally polarized modes. The problem of determination of the phase difference in two modes of optical field for the quantum polarization states of light is discussed. To describe in general such a quantum field we introduce two pairs of the phase operators: the phase angles for the Stokes parameters of light in a three-dimensional picture of the Poincare sphere. We also consider a special type of the eight-port polarization interferometer (polarimeter) for simultaneous homodyne detection of both the Stokes parameters of light and the polarization phase operators and their fluctuations as well. Using an anisotropic (spatiope...

Journal ArticleDOI
TL;DR: It is demonstrated that a single linearly polarized fundamental wave, when it is propagating in a quadratic medium, can efficiently generate a new fundamental wave of orthogonal polarization.
Abstract: A method of intensity-dependent polarization switching is proposed. The effect is based on simultaneous action of two phase-matched second-order processes in a quadratic medium. Using analytical and numerical techniques, we demonstrate that a single linearly polarized fundamental wave, when it is propagating in such a medium, can efficiently generate a new fundamental wave of orthogonal polarization. The polarization switching is explained by an effective four-wave-mixing process that is performed through second-order cascading.

Patent
11 Mar 1999
TL;DR: In this article, a polarization device includes a reflection-type polarization element disposed at a side to which an optical beam comes in and an absorption-type polarizing element disposed behind the reflection type polarization element.
Abstract: A polarization device includes a reflection-type polarization element disposed at a side to which an optical beam comes in and an absorption-type polarization element disposed behind the reflection-type polarization element, wherein the reflection-type polarization element and the absorption-type polarization element are disposed such that a transmission axis of the reflection-type polarization element coincides with the transmission axis of the absorption-type polarization element. Further, an optical projector using such a polarization device is disclosed.

Patent
Nobuhiko Kikuchi1
07 Jul 1999
TL;DR: In this article, a compensation circuit for polarization mode dispersion, a degree of polarization measuring circuit, and a control circuit are presented, where the compensation circuit generates a control signal based on the degree of the divided optical signal.
Abstract: The present invention offers a polarization mode dispersion compensator and a compensation method for polarization mode dispersion having simple constitution and being strong against external disturbances. The polarization mode dispersion compensator, a representative example of the present invention, is provided with a compensation circuit for polarization mode dispersion, a degree of polarization measuring circuit, and a control circuit. An optical signal is input to the compensation circuit for polarization mode dispersion through an optical fiber, and after the process of compensation for polarization mode dispersion, it is output to an optical fiber. An optical coupler divides a part of the optical signal passing through the optical fiber. The degree of polarization measuring circuit finds the degree of polarization of the divided optical signal. The control circuit generates a control signal based on the degree of polarization obtained in the above, and so controls the compensation circuit for polarization mode dispersion as to make the degree of polarization maximum.

Journal ArticleDOI
TL;DR: The result obtained is that thermally emitted radiance might have a circular polarization component and the emissivity depends only on the reflectance matrix.
Abstract: An expression for the polarized emissivity of a material is obtained with the Stokes vector-Mueller matrix polarization formalism. The result obtained is that thermally emitted radiance might have a circular polarization component. In addition, the emissivity depends only on the reflectance matrix.

Journal ArticleDOI
Kerstin Worhoff, Bert Jan Offrein1, Paul Lambeck, Gian-Luca Bona1, Ann Driessen 
TL;DR: In this paper, a double-core waveguiding structure is proposed for planar optical networks, which adds a thin birefringence-compensating layer, which results in a double core waveguide.
Abstract: For application in communication networks, polarization-independent planar optical waveguiding structures are essential, because the polarization state of the optical signal in an optical network is arbitrary. A new concept for polarization-independent waveguides simply adds a thin birefringence-compensating layer, which results in a double-core waveguiding structure. One of the major advantages of the double-core concept is its technological simplicity. The impact of the layer parameters is simulated and the compensating mechanisms are discussed. The feasibility of this concept is demonstrated on waveguides fabricated with silicon oxynitride technology, where the channel birefringence is tuned over a wide range(+1.6/spl times/10/sup -3/ to -1.1/spl times/10/sup -2/) by varying the thickness of the birefringence compensating layer.