Frequency doubling and optical parametric oscillation with potassium niobate

Frequency doubling and optical parametric oscillation are investigated with potassium niobate in an external resonator. For frequency doubling of 860 nm input, 650 mW of cw blue light around 430 nm has been generated for 1.35 W of infrared input. In a cavity with reduced losses, overall conversion efficiency of up to 70% has been achieved. With regard to parametric oscillation with a 430 nm pump, 100 mW of stable cw emission from the optical parametric oscillator has been obtained for pump power 250 mW. Blue-light induced infrared absorption has been discovered to have significant deleterious effects and to be the principal reason why even higher efficiencies have not been reached.