Laser-induced breakdown (LIB) thresholds in AgClxBr 1-x crystals and fibers were studied under CO2 laser pulses and CW excitation. The value of LIB threshold Pc of the bulk crystals is about 7.2·108 W/cm2 for AgCl and 4·109 W/cm2 for AgBr under 60 ns TEA laser excitation. The LIB threshold in fibers is much smaller; about 2·10 8 W/cm2. The absorption of the crystals at 10.6 μm changes from 8·10-5 cm-1 for AgCl to 2·10-5 cm-1 for AgBr; for fibers with the same composition absorption is much greater (3·10-4 cm-1 for AgCl; 2·10-4 cm-1 for AgBr). The dependence of the LIB and IR absorption on composition, and mechanical and temperature treatments suggests that the LIB in silver halide crystals and fibers is due to the avalanche electrons in a high electric field. The initial free electrons for this process are supplied by ionization of the cation vacancy - charged dislocation complexes. The relatively lower optical stability of the fibers is due to the increased concentration of defects formed in the hot extrusion of the crystal. A simple thermal annealing method for reduction of the IR absorption is proposed.
|Number of pages
|Proceedings of SPIE - The International Society for Optical Engineering
|Published - 1997
|Laser-Induced Damage in Optical Materials: 1996 - Boulder, CO, United States
Duration: 7 Oct 1996 → 7 Oct 1996