Influence Of Birefringence Research Articles

Influence of birefringence- and core ellipticity-induced mode coupling on the gain statistics of forward-pumped Raman amplified few-mode fiber links.

The equations describing light propagation in a few-mode fiber for space-division multiplexing are derived under the presence of linear mode coupling and both Kerr- and Raman-induced nonlinearity. By considering physical models of stress birefringence and core ellipticity, the effect of such fiber imperfections on the gain of a forward-pumped Raman-amplified link is assessed through numerical simulations. The average gain and the variation of signal power at the output of the amplified fiber span is numerically evaluated for different levels of coupling strength in fibers supporting 2 and 4 groups of LP modes, identifying three main propagation regimes and assessing the effect of coupling between different groups of degenerate modes.

Numerical Tool for Calculating Birefringence in Mirror-Substrates for Gravitational-Wave Detectors

The influence of birefringence on rays entering and exiting a non-isotropic medium is a complex process that depends on its dielectric tensor, the orientation and geometry of the medium, the surrounding material, and the inclination of the incident ray. Thus, when aiming for a calculation of the effects, many parameters need to be taken into account while simplifications are generally not applicable. Moreover, the complexity of the general issue makes it almost impossible to find an analytical solution for backward calculations of stress-birefringence from polarization measurements. In this paper, a report is given on the formulation of a birefringence ray-tracing program in Python for the convenient evaluation of optical effects inside uniaxial crystals under stress. The aim thereby is to have an easily applicable tool that can be used in interferometer commissioning for current and future gravitational-wave detectors. Results from test simulations using realistic parameters for a sapphire mirror as used in the gravitational-wave detector KAGRA are implemented and show the capabilities of this tool.

Influence of birefringence in the instability spectra of oppositely directed coupler with negative index material channel

A theoretical investigation on the influence of birefringence in the modulational instability (MI) spectra of an oppositely directed coupler (ODC) with a negative index material (NIM) channel is presented. We study the effect of birefringence on MI in linear and circular birefringent ODCs for both normal and anomalous dispersion regimes. It is found that besides the instability band due to nonlinear positive index material (PIM) and negative index material (NIM) channels, new symmetric instability regions are observed as a result of birefringent effects. Also defocusing nonlinearity suppresses the NIM band in the normal dispersion regime, but in the anomalous dispersion regime the defocusing nonlinearity enhances the gain of the NIM band. In contrast to the case of linear birefringence, in terms of MI gain from circular birefringence, only two birefringent bands dominate: the inherently PIM and NIM bands. This preponderance is attributed to the fact that the cross-phase modulation effect for the case of circular birefringence is stronger, thus allowing a better coupling between the beams, which results in the enhancement of the gain. Therefore, the manipulation of MI and solitons in an ODC is better performed when the birefringence is circular rather than linear. Here we report how to generate and manipulate MI and solitons in birefringent ODCs with a particular emphasis on a NIM channel.

Formation of temperature fields in doped anisotropic crystals under spatially inhomogeneous light beams passing through them

The features of formation of thermal fields in potassium dihydrophosphate crystal doped with potassium permanganate under a 532-nm laser beam passing through it have been investigated. Data on the influence of birefringence on the temperature distribution in an anisotropic crystal whose surface is illuminated by a spatially modulated light beam are presented.

Determining the topography of the birefringence in fluorite crystals and a study of how it affects the image quality of photolithographic projection systems

This paper discusses apparatus for measuring the characteristics of the residual birefringence of large optical crystals of fluorite by the method of crossed polarizing sheets. A mathematical model of the proposed method is presented. The point-spread function, which describes the influence of birefringence on the image quality, is analyzed.

Compensating the birefringence effects of the elements of the optical channel when a polarization method is used to determine the relative rotation of objects

This paper discusses how birefringence in the elements of the optical channel affects the result of the computation of the relative rotation of objects when a polarization method is used to determine the angle. A method of dual-spectral probing of the optical channel is proposed and experimentally checked that makes it possible to automatically determine the optimum relative rotation of the elements to minimize the influence of birefringence.

Suppression of Polarization Switching in Birefringent Antiresonant Reflecting Optical Waveguide Vertical-Cavity Surface-Emitting Lasers

Influence of birefringence on the multimode operation of antiresonant reflecting optical waveguide (ARROW) vertical-cavity surface-emitting lasers (VCSELs) is analyzed. It can be shown that polarization switching is mainly due to thermal lensing effects. Hence, a new design rule is proposed to optimize the dimensions of ARROW for the suppression of polarization switching. Using the optimized design, the maximum single-polarization output power of VCSELs can be tripled. In addition, it is shown that the performance of the optimized ARROW VCSELs will not be deteriorated by the uncertainty of birefringence.

Influence of birefringence on soliton switching in a twin‐core fiber coupler

AbstractIn this paper, the effects of randomly varying birefringence on soliton switching in a twin‐core fiber coupler are discussed in detail by numerical simulation. The results obtained show that these effects on sub‐ps soliton switching cannot be neglected, they would degrade the quality of the coupler. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 502–506, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10649

Influence of birefringence induced at low temperature on balanced detection of polarization-dependent photon-number squeezing and its optical compensation

The polarization-dependent photon-number squeezing of 1.5 dB from a grating feedback locking quantum-well laser in a cryostat has been experimentally detected with a balanced homodyne detector including an imperfect nonpolarized-beam splitter. The great influence of the birefringence induced at low temperature on the determination of the shot-noise-limit and on the detection of photon-number squeezing is discussed in detail. Birefringence is compensated for by insertion of a half-wave plate of adjustable inclination into the output beam before the polarization components of the optical system.

Influence of birefringence on the image formation of high-resolution projection optics

The influence of birefringence on high-resolution projection optics used for microlithography is investigated theoretically. A formula for partially coherent imaging that is based on the scalar diffraction theory is extended to include the birefringent properties of lens materials. By the determination of the birefringent properties of lens materials by use of random numbers, data on 200 lenses, each composed of 10 birefringent elements, are generated to estimate statistically the degree of imaging-performance degradation. As a result, it was found that the image contrast of a five-bar pattern decreases as a quadratic function of the maximum magnitude of the birefringence that was set in common for all elements in each lens data set.

Distorted wave front produced by a high-resolution projection optical system having rotationally symmetric birefringence

The influence of birefringence caused by rotationally symmetric stress distribution in a high-resolution projection optical system is investigated. The general form of the pupil function is derived based on the Jones matrix calculation, expressing the wave front as a combination of the two orthogonal polarization components. Assuming a linearly polarized incident beam, it is found that the main polarization portion of the wave front exiting the projection lens has astigmatic aberration in the Seidel region and shows phase singularity at four pupil points at which the amplitude transmittance becomes zero.

High-efficiency and compact blue source: intracavity frequency tripling by using LBO and BBO without the influence of birefringence

A new intracavity frequency-tripled laser resonator design that circumvents the birefringence interference problems normally associated with a laser resonator with two intracavity nonlinear crystals is developed. Two hundred mW of UV laser output in a TEM(00) mode is obtained from an intracavity frequency-tripled Nd:YAG laser; the 250-Hz pulsed input does not exceed 400 W. LBO and BBO nonlinear crystals are utilized for second-harmonic generation and third-harmonic generation, respectively. The peak power of the UV output measures 90 kW.

Influence of birefringence on the signal quality of magnetooptic disks using polycarbonate substrates

Magnetooptic (MO) disks using polycarbonate (PC) substrates were investigated. Birefringences of the PC disk substrates molded with different methods were measured. Signal qualities for MO disks with the PC disk substrates were also measured and the effect of the birefringence on the signal quality was estimated.

Simultaneous determination of elastic and optical properties of polymers by high performance Brillouin spectroscopy using different scattering geometries

General aspects of high performance Brillouin spectroscopy in polymers using special scattering geometries such as 90A-scattenng geometry are discussed. Technical improvements are reported resulting in absolute accuracies up to 0.05 % for sound velocity determination. A method of data analysis is presented delivering simultaneously the complete set of elastic stiffness constants. The influence of birefringence on the Brillouin line shifts in anisotropic polymeric systems is estimated and techniques to reduce this influence are proposed. The determination of the principal refractive indices by Brillouin spectroscopy is discussed. Furthermore, a quantityD X , which is sensitive to hypersonic relaxation processes, is introduced.

Magnetooptical current transformer 1: Principles

The principles of measuring currents in high-voltage lines by magnetooptical means are described. Particular attention is payed to using an optical fiber both as a transmission line and a measuring sensor. The influence of birefringence on the measuring signal is discussed.

Influence of thermal self-interactions on the continuous generation of the second harmonic

The results are given of an experimental investigation of the influence of thermal self-interactions on the second-harmonic generation in KDP, ADP (90% phase matching), and Ag3AsS3 (~22? phase-matching angle) crystals. The cause of the fall of the second-harmonic power was determined. It was found that at pumping powers exceeding a critical value characteristic of a given crystal the conversion efficiency fell because of the induced thermal detuning of the phase matching. The influence of birefringence was also considered.