Future directions in quasi-phasematched semiconductors for mid-infrared lasers

Quasi-phase-matched (QPM) materials such as periodically poled lithium niobate (PPLN) and tantalate (PPLT) have led to extremely efficient frequency-shifted laser sources in the visible and near-infrared, and QPM semiconductors promise to extend this performance beyond 4 mu m. Orientation patterned semiconductors are not only transparent far deeper into the mid-IR but also offer higher nonlinear coefficients, higher thermal conductivity, higher purity levels, and very low losses when grown from the vapor phase. We compare the properties, processing, and performance of orientation-patterned GaAs (OPGaAs) with candidate compound semiconductors being for development as the next generation QPM nonlinear optical materials in the mid-infrared, and identify gallium phosphide as the most promising material for near-term development.