Improved growth of AgGaSe2 crystals and phase matched second harmonic generation of 10.6 μm CO2 laser radiation

Good quality AgGaSe2 single crystal 22 mm in diameter and 80 mm in length is grown by an improved technique, i.e., descending ampoule with rotation. Although the crystals grow with optical defects, postgrowth heat treatment procedures are used to successfully eliminate the defects and produce material of 62.4% IR transmission at 10.6 mu m. The frequency-doubling device is cut from a cylindrical crystal boule using a new orientation cut method according to the type-1 phase-matched condition. A high optical quality, orientated AgGaSe2 single crystal of 10 x 10 x 12 mm size is used for second harmonic generation (SHG) of the pulsed output of a 10.6 mu m CO2 miniature transversely excited atmospheric laser. A relatively high energy conversion efficiency of 12% is obtained. It is found that the optical surface damage threshold of the crystal is larger than 12 MW/cm(2). (C) 1999 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(99)00512-7].