Second-harmonic generation in GaAs ’’stack of plates’’ using high-power CO2 laser radiation

Efficient wide-band high-power generation of CO2 laser second-harmonic radiation is reported using a ’’stack-of-plates’’ approach to phase match the interaction in GaAs. A long collinear interaction length is achieved by using a series of {111} GaAs crystalline plates at Brewster’s angle, each one coherence length thick, oriented so as to alternate the sign of the nonlinear polarization in each consecutive plate. The peak second-harmonic power generated was 60 kW at 5.3 μm using 3 MW of mode-locked pump power with a stack of 12 GaAs plates. 420