Study of a ruby laser with a passive shutter based on a LiF crystal with F 2 + color centers

Abstract

A large body of current work is dedicated to the study of materials with saturable absorption suitable for passive modulation of the Q of ruby lasers. LiF crystals with F/sub 2//sup +/ color centers are proposed as a passive shutter; however, their prospects to date are unclear. The authors' goal in this paper is a more detailed study of the characteristics of a ruby laser with a passive shutter of LiF:F/sub 2//sup +/ obtained by irradiating LiF crystals with gamma radiation from a cobalt-60 source. Crystals with an OH additive were used to obtain stable LiF:F/sub 2//sup +/. The passive shutter used in the experiments was a parallelepiped 20 x 20 x 9 mm. The initial transmittance of the crystal at the 694 nm wavelength was 41%. To determine these and other parameters of a passive shutter based on these crystals, the authors based their method on measurement of the shutter transmission as a function of the amount of energy of the incident pulsed radiation. The most homogeneous central portion of the beam of the pulsed ruby laser radiation was selected using a diaphragm 5 mm in diameter and was directed to the sample under study.