Optical parametric oscillator with unstable resonators

摘要

We present a theoretical and experimental investigation of the efficiency, beam quality and signal bandwidth of a confocal, unstable OPO resonator. Reduction by more than 20 times of the divergence as well as bandwidth narrowing by factor of ～5 of the signal beam, in comparison to the plane-parallel resonator, are obtained. Resonator configurations have been found where the beam quality of the signal exceeds the beam quality of the pump.