Abstract

We report the experimental demonstration of the novel optical parametric oscillator (OPO) approach to tunable optical frequency division. OPO-based tunable frequency dividers are potentially useful for optical frequency metrology, precision measurements, and squeezed-state applications. Our doubly resonant KTP OPO, which has a 22-mW pump threshold and a 30% total conversion efficiency, generates stable, cw single-mode subharmonic outputs near its frequency degenerate point with excellent tuning characteristics. Angle and temperature tuning of the crystal permit operation at any signal-idler beat frequency separation within 1 THz of frequency degeneracy. Continuous tuning of ~0.5 GHz is obtained through temperature and electric field tuning of the crystal and a piezoelectrically controlled cavity-length servo. We have made direct beat-frequency measurements up to 26 GHz with high signal-to-noise ratio. Precisely controlled tuning of the signal and idler output frequencies, even at frequency degeneracy, can be important in optical-microwave precision measurements and tunable squeezed state generation.

© 1991 Optical Society of America