Continuous-wave singly resonant optical parametric oscillator pumped by a single-frequency resonantly doubled Nd:YAG laser.

We report what is to our knowledge the first demonstration of a continuous-wave singly resonant optical parametric oscillator based on potassium titanyl phosphate. The pump source used is a single-frequency resonantly doubled Nd:YAG laser. By double passing the pump through the crystal, we achieved a minimum oscillation threshold of 1.4 W. With 3.2 W of incident pump power, a maximum 1.07 W of nonresonant idler power was generated. Spectral measurement reveals that the singly resonant optical parametric oscillator operates consistently in a single axial mode with much relaxed axial mode hop tolerance to cavity length and pump-frequency fluctuations compared with doubly resonant optical parametric oscillators previously demonstrated.