MULTIPLE CONVERSION AND OPTICAL LIMITING IN A SUBHARMONIC-PUMPED PARAMETRIC OSCILLATOR

We demonstrate that multiple coexisting frequency-conversion processes can occur in an externally resonant second-harmonic generator under s uitable conditions. Besides the generation of signal and idler waves b y subharmonic-pumped parametric oscillation, sum-frequency mixing amon g the resonant subharmonic (1064-nm), signal, and idler waves was obse rved, leading to additional emission wavelengths around the harmonic w avelength (532 nm). The output waves both exhibit high frequency stabi lity, with as long as 4 h of mode-hop-free parametric oscillation, and are continuously tunable over 2 GHz. Near degeneracy the parametric o scillator operates as an optical limiter for the harmonic wave. (C) 19 97 Optical Society of America.