THERMAL SELF-FREQUENCY LOCKING OF A DOUBLY RESONANT OPTICAL PARAMETRIC OSCILLATOR

The increase in the circulating signal and idler fields that occurs in a high-Q doubly resonant optical parametric oscillator (OPO) as it ap proaches resonance results in a small increase in the crystal temperat ure owing to absorption of the generated fields. The temperature chang e affects the refractive index of the crystal and alters the optical p ath length of the cavity. This effect may lead to self-frequency locki ng of the OPO to a specific resonance of the signal and idler fields, and it also results in peculiarities in the transient response of the system as it is scanned through resonance. We show that the experiment ally observed effects are consistent with the results of a numerical m odel of the OPO. (C) 1997 Optical Society of America.