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