OPTICAL PARAMETRIC OSCILLATION WITH DETUNED INTRACAVITY SUM-FREQUENCY GENERATION

We consider frequency up-conversion by means of an optical parametric oscillator (OPO), in which sum-frequency generation (SFG) takes place in a crystal preceding the OPO crystal in the resonator. The SFG crystal produces light with a frequency at the sum of the pump and OPO signal frequencies. Only the OPO signal is resonated. A small detuning (phase mismatch) of the SFG crystal yields stable steady-state operation with quantum efficiency greater than 40% for a factor of 34 variation in the pump intensity. Detuning also reduces the power loading on the OPO crystal. Conversion of 1.064 mum radiation to 589 nm radiation is discussed as an example. For this example power conversion efficiency exceeding 85% is possible.