<title>Use of parallel axicon for compensation of birefringence in active elements of solid state lasers</title>

Abstract

A new polarization optical element -a parallel axicon which is a cylinder whose face surfaces have a conical form with identical vertex angles and are parallel relative to each other -is proposed. It allows for compensation of thermally induced birefringence in laser rods of master oscillators and amplifiers. The optical scheme that we suggest consists of a quarter-wave plate, laser rod, 45 degree reciprocal rotator, parallel axicon and mirror. The parallel axicon operates as a quarter-wave plate whose axis inclination angle coincides with polar angle. As a result, after two passes through the whole scheme the radiation resumes its linear polarization, i.e., depolarization in the laser rod is totally compensated. In this work we discuss in detail numerous aspects of the proposed technique, including advantages and disadvantages of this technique in comparison with other methods. The proposed technique for compensation of birefringence in AE may find a broad application in powerful laser oscillators and amplifiers based on Nd:YAG and other isotropic active media.