Improvement in the output characteristics of a pulsed optical parametric oscillator on injection of an external signal into an extracavity wave

A pulsed singly resonant optical parametric oscillator was constructed from an LiNbO₃ crystal. Narrow-band radiation from a cw He–Ne laser (λ = 3394 nm) was injected into an extracavity wave when the oscillator was pumped with multimode radiation from a Q-switched YAG:Nd laser. Narrowing of the spectrum of the parametric oscillator to the width of the pump wave spectrum was observed and this was accompanied by an increase in the conversion efficiency in the oscillator by a factor of 1.5–2.