Continuous-wave optical parametric oscillator tuned by a diffraction grating.

A new continuous-wave singly resonant optical parametric oscillator is described. It is capable of stable, widely tunable single-frequency output in the mid-infrared region. A magnesium oxide doped periodically poled LiNbO(3) crystal provides the parametric amplification. The signal beam is in resonance with a 4-mirror linear cavity, where a diffraction grating in the Littrow configuration replaces one end mirror. The output frequency is tunable by rotating the grating. No additional components are needed inside the resonator.