Abstract

Efficient, low power, compact sources of tunable coherent near and mid-infrared wavelength radiation are necessary for many applications, including communications, spectroscopy, and process monitoring. Nonlinear optical frequency conversion that shifts laser diode outputs to the desired wavelength has attracted significant attention as a means to meet these requirements. Optical parametric oscillators (OPOs) offer near or mid-infrared wavelengths with extremely wide tunability while requiring only a single pump laser. An OPO is a resonant device which divides short-wavelength pump radiation into a pair of longer-wavelength signal and idler waves. Because of the large circulating signal (and sometimes idler) fields, overall energy conversion efficiency is much larger than that of single-pass interactions such as difference frequency generation (DFG). Because parametric gain increases with pump power while cavity losses generally remain fixed, a minimum pump power is required so that round-trip gain exceeds round-trip loss. One current challenge for OPOs is reducing the oscillation threshold to levels attainable with diode lasers.

© 1995 Optical Society of America