Abstract
Efficient room‐temperature optical parametric oscillation was obtained using a single‐mode, giant‐pulse ruby laser to directly pump a crystal of LiNbO3 placed in an optical cavity resonant at both the signal and idler wavelengths and also in a cavity resonant at only the signal wavelength. For the doubly resonant oscillator, 22% of the pump power was converted into signal power; for the singly resonant oscillator, conversion was 6%. The behavior of both oscillators was reproducible. Several features of the oscillator dynamics are discussed.