Note: Pulsed single longitudinal mode optical parametric oscillator for sub-Doppler spectroscopy of jet cooled transient species.

We present a pulsed single longitudinal mode optical parametric oscillator that was recently constructed for sub-Doppler spectroscopic studies of transient species in a supersonic slit jet expansion environment. The system consists of a Littman-type grazing-incidence-grating resonator and a KTP crystal and is pumped at 532 nm. By spatially filtering the pump laser beam and employing an active cavity-length-stabilization scheme, a frequency down-conversion efficiency up to 18% and generation of Fourier-transform limited pulses with a typical pulse duration of ∼5.5 ns and a bandwidth less than 120 MHz have been achieved. In combination with a slit jet expansion, a sub-Doppler spectrum of SiC2 has been recorded at ∼498 nm, showing a spectral resolution of Δν/ν ≈ 6.2 × 10-7 .