Cavity length resonances in a nanosecond singly resonant optical parametric oscillator

Markus Henriksson,Fredrik Laurell,Lars Sjöqvist,Valdas Pasiskevicius

doi:10.1364/oe.18.010742

Abstract

Resonant output energy enhancement in a singly resonant nondegenerate type-I optical parametric oscillator with a volume Bragg grating output coupler is demonstrated. The resonances occur when the pump laser and parametric oscillator cavity length ratio is an integer or a fraction of small integers. Although the length resonances are similar to those observed in doubly resonant optical parametric oscillators, the physical mechanism is distinctly different. The resonances in the singly resonant oscillator are caused by correlation of the instantaneous power between the quasi-periodic multimode pump laser beam and the OPO signal.

Highlights

The output pulse energy from a pulsed optical parametric oscillator (OPO) will in general decrease as the cavity length is increased
The spectrum of the doubly resonant OPO (DRO) pumped with a multi-longitudinal mode beam was found to be sensitive to the cavity length and only at the length resonances the spectrum acquires a shape corresponding to single-mode pumping
In this work we demonstrate that cavity length resonances are readily observable in a spectrally-narrowed nondegenerate singly resonant multi-longitudinal mode OPO operating up to twice the oscillation threshold

Summary

Introduction

The output pulse energy from a pulsed optical parametric oscillator (OPO) will in general decrease as the cavity length is increased. The causes for this are increased diffraction losses in the longer cavity, especially if plane mirrors are used, and longer build-up time because of the increased roundtrip time. It has been shown [1,2], that under certain conditions in a doubly resonant cavity the pulse energy is not continuously decreasing with increasing cavity length when the OPO is pumped by a multi-longitudinal mode laser. Experimental investigation of these resonances in a SRO has not been reported previously

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Results

Conclusion