Dual-cavity doubly resonant optical parametric oscillators: demonstration of pulsed single-mode operation

The operating points of pulsed dual-cavity doubly resonant optical parametric oscillators have been investigated, taking into account the influence of the optical dispersion. A diagram is proposed to determine the spectral separation of doubly resonant positions for any optical lengths of both cavities. From the analysis of the distribution of doubly resonant coincidences, original conditions for stable single-mode operation are specified. This approach is validated by use of a type II phase-matched β-barium borate crystal. Frequency stability and tuning characteristics are also reported. To our best knowledge, this is the first demonstration of single-mode operation that uses a dual-cavity doubly resonant optical parametric oscillator in the nanosecond pulsed regime.