Birefringence Compensation Research Articles

Birefringence compensation in polarization coupled lasers

The use of optical rotators and waveplates to compensate for thermally induced birefringence in cylindrical laser rods is reported. The use of these components allows polarization coupled lasers to operate efficiently at high average power levels. Experimentally a Nd:YAG oscillator has been operated in a Q-switched TEM(00) mode giving 300-mJ pulses and 15 W of average power.

Stokes-spectro-polarimetry with a two-dimensional diode array

A new apparatus is described which measures the Stokes profiles by means of a two-dimensional 100 × 100 detector array. On-line data processing allows the immediate visualization of the profiles corresponding to several spectral lines observed simultaneously along one spatial direction on the solar disk. An improved method for the accurate compensation of the telescopic birefringence with a Bowen compensator is realized. Three different methods for the investigation of fluxtube properties are discussed, based on the analysis of V profiles and illustrated by first measurements with the apparatus. Two characteristics of V profiles; excess polarization and zero crossing wavelength of the V profile show strong spatial variations in plages and network indicating different dynamical conditions for individual fluxtubes.

Performance of a Nd: YAG oscillator/ampflifier with phase-conjugation via stimulated Brillouin scattering

Phase conjugation via stimulated Brillouin scattering in CH4 gas has been used to correct amplifier aberrations in a Nd: YAG oscillator/amplifier system. The single amplifier stage has been used in two-pass and four-pass arrangements. Using the four-pass arrangement incorporating compensation for thermal birefringence, a single-frequency diffraction-limited output of 350 mJ, in a compressed 6 ns pulse is achieved at 15 Hz repetition rate.

Dispersion of photoelastic constants in doped KDP crystals

The photoelastic behaviour ofkdp crystals with additives like borax,adp, nickel phosphate, manganese phosphate and sodium dihydrogen orthophosphate has been studied as a variable birefringent compensator. The dispersion of the stress birefringence with wavelength was studied for a single orientation.

Photoelastic studies on ammonium Rochelle salt single crystal

Elastooptic measurements at room temperature on single crystals of ammonium Rochelle salt (ARS) which belongs to the Class 222 ( D 2) of orthorhombic system and is isomorphous with Rochelle salt in its non-polar phase, have been made at 5890 Å. The values of all the photoelastic tensors, q ij and p ij of (ARS) at 5890 Å are reported. These constants have been determined from the measurements of relative and absolute path retardations produced in crystal prisms of various orientations when subjected to linear stresses using the birefringent compensator method and a modified form of Rayleigh refractometer respectively. The effect of hydrostatic pressure on the principal refractive indices and birefringences of (ARS) has also been deduced.

Elasto-optic studies on potassium acid phthalate single crystal

Potassium acid phthalate (KAP) belongs to the stress-optical constants qe and 12 strain-optical mm2(C2v) class of orthothombic system according constants Pu. The complete matrices of qli and PU to Okaya [1]. Betyaev etal . [2] have studied its and also the expressions for the absolute and rela. optical, dielectric, piezoelectric and elastic properative path retardations for different directions of ties. The acousto-optic interactions and hence the stress and directions of observation for an orthorindividual values of nine of the twelve strain optical hombic crystal are given by Narasimhamurty [5]. constants have been determined by Belikova et al. The crystals of KAP were grown in the labora[3] using the Bragg ultrasonic diffraction techtory by the slow evaporation of an aqueous nique. Since the acousto-optic interaction in this solution of its salt at room temperature. Large crystal characterizes it as an interesting material crystals o f 40ram × 30ram x 8ram size were for use in acousto-optic devices, we have studied obtained, by seeding, in a period of 8 to 10 weeks. in detail the elasto-optic behaviour of the single The crystallographic data reported by Okaya [1] crystal of KAP and now present the complete was used to identify the faces and the crystaUoset of absolute values of its stress-optical and graphic axes of the crystal. The assignment of the strain-optical constants qij and Pij respectively, cartesian axes x, y , z to the crystal follows that by These constants have been obtained from the Belyaev et at. [2]. The orientations of the KAP experimental measurements of relative path retarprisms were accurate to within 1 °. dation employing the bi-refringent compensator Observations on the differential stress bimethod of Veerabhadra Rao and Narasimhamurty refringence at mean sodium yellow light are [4] and absolute path retardation employing a presented in Table I and those on the absolute modified form of Rayleigh refractometer, when path retardation measurements are collected in crystals of different orientations were subject to Table II. linear stresses. The values of the principal refractive indices The photo-elastic tensor of orthohombic and etastic constants used in the calculations are crystals is described in Pockels' scheme by its 12 taken from Belyaev etal . [2] and are

Compensation of birefringence induced in laser systems by passive anisotropic elements

An analysis is made of two systems for compensating birefringence induced in an active element when thermal stresses in the element have a longitudinal symmetry plane. Simple passive anisotropic elements are used in both systems. The Jones matrix method is used to demonstrate that these systems, together with thermally stressed active elements, are equivalent to a half-wave phase plate. An estimate is obtained of the influence of a thermal lens formed in an active element on the birefringence compensation process. Experiments proving the feasibility of the systems are reported. A periodic double-pass amplifier based on these systems is proposed.

Optical Network Synthesis Using Birefringent Crystals V Synthesis of Lossless Networks Containing Equal-Length Crystals and Compensators*

Part I of this series reported a procedure for synthesizing birefringent networks having a prescribed amplitude transmittance. The desired transmittance C(ω) was written as C(ω) = C0 + C1e−iαω + C2e−i2aω + ⋯ + Cne−inaω, where the Ci could be arbitrarily chosen as long as each was real. The synthesis procedure of this paper is a generalization of the procedure of Part I and allows for the realization of C(ω) having complex Ci. The resulting network consists of n stages between an input and output polarizer, with each stage containing a birefringent crystal and (achromatic) optical compensator. The form of this network is essentially the same as the practical form of the network obtained from Part I, and hence the additional versatility is obtained at no extra cost in network complexity.

Effective Thickness of Two Birefringent Crystals for the Study of Natural Birefringence

A new optical technique using a birefringent compensator has been developed to study the natural birefringence of calcite and ADP. Experimental results are compared with those obtained by the usual banded spectrum technique. Application of this method for very highly birefringent substances is indicated.

Birefringent Compensator for Studying Very Small Changes in Double Refraction

A new optical method of studying the dispersion of the photoelastic constants of glasses is described. Experimental results on a specimen of glass are compared with those obtained by Filon’s method. The sensitivity of the method is discussed. The applicability of the birefringent compensator method to the study of the dispersion of photoelastic constants of uniaxial and biaxial crystals is indicated.

Achromatic combinations of birefringent plates

An achromatic quarter-wave plate is obtained by superposing three birefringent plates of the same material; the first and last should have the same retardation 2δ1 their fast vibration directions being parallel to one another but inclined at a specific angle c to that of the central plate-of retardation π. The desired range of achromatism determines the optimum values of 2δ1 and c (which, in turn, will determine the orientation of the effective principal planes of the combination). As an example, using mica retardation plates prepared for Hg 5461, the range from 4100 A to 6800 A is covered with 2δ1 = 115° 42' and c = 69° 54'. Further, for a particular wave-length, a birefringent compensator of variable retardation (0 to 2π) is obtained by interposing a half-wave plate that can be rotated in its own plane, between two quarter-wave plates that have their fast vibration directions parallel. The results follow from the Poincare sphere by geometrically compounding successive rotations.