SHG in doped GaSe:In crystals.

ABSTRACT

Optical transmission range and phase matching (PM) conditions for second harmonic generation (SHG) of Er3+YSGG and CO2 laser in indium doped GaSeIn(0.1, 1.23, 2.32 mass%) are studied in comparison with these in pure and sulfur doped GaSeS(0.09, 0.5, 2.2, 3 mass%) crystals. No changes in transparency curve are found in GaSe crystals up to 2.32 mass% indium content, but as small change as 0.18 degrees in PM angle for 2.79 microm Er3+YSGG laser SHG and approximately 0.06 degrees for 9.58 microm CO2 laser emission line SHG are detected. PM properties of the crystals are evaluated as a function of temperature over the range from -165 to 230 degrees C. The value of dtheta/dT, the change in PM angle with variation of temperature, is found to be very small for GaSeIn crystals. While for SHG of Er3+YSGG laser, dtheta/dT =22"/1 degrees C only, it is as small as -4.9"/1 degrees C for that of CO2 laser radiation. Linear variation of PM angle with temperature increasing is an indicator of absence of crystals structure transformation within temperature range from -165 to 230 degrees C. Thus, application of GaSeIn solid solutions in high average power nonlinear optical systems seems to be prospective.