Abstract
Optical transmission range and phase matching (PM) conditions for second harmonic generation (SHG) of Er3+:YSGG and CO2 laser in indium doped GaSe:In(0.1, 1.23, 2.32 mass%) are studied in comparison with these in pure and sulfur doped GaSe:S(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 GaSe:In 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 GaSe:In solid solutions in high average power nonlinear optical systems seems to be prospective.
Highlights
There is a severe need for nonlinear crystals able to cover the near-IR and mid-IR spectral regions and applicable in practical frequency conversion systems possessing generation of coherent light beams with wide wavelength tuning
Layered p-type ε-GaSe is an excellent crystal for frequency conversion over a wide spectral region from near-IR to mid-IR and even to terahertz region [1], but an application of GaSe in commercial systems is hampered by very poor mechanical properties
We have reported the transmission range and phase matching conditions for second harmonic generation of Er3+:YSGG and CO2 laser in doped GaSe:In(0.1, 1.23, 2.32 mass%) in comparison with pure and sulfur doped GaSe:S(0.09, 0.5, 2.2, 3 mass%) crystals
Summary
There is a severe need for nonlinear crystals able to cover the near-IR and mid-IR spectral regions and applicable in practical frequency conversion systems possessing generation of coherent light beams with wide wavelength tuning. Such key factors as stability of optical properties upon exposure of the crystal to high power laser beam, high optical homogeneity and sufficient mechanical properties are limiting for material selection. Layered p-type ε-GaSe is an excellent crystal for frequency conversion over a wide spectral region from near-IR to mid-IR and even to terahertz region [1], but an application of GaSe in commercial systems is hampered by very poor mechanical properties. Even general tendency in influence of In doping on transmission range and optical quality of GaSe is not clear
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