Atomic and molecular spectroscopy with a continuous-wave, doubly-resonant, monolithic optical parametric oscillator

Doppler-broadened atomic and molecular spectra were observed with a 1-octave tunable, continuous-wave, doubly resonant, monolithic optical parametric oscillator (OPO) using 5%-MgO-doped LiNbO₃ as a nonlinear crystal. By tuning the frequency of a pump laser, longitudinal mode selection over 20 successive modes, corresponding to a 60 GHz span, was possible. Continuous frequency tuning was achieved using an external waveguide-type electrooptic phase modulator (EOM). We could observe the Cs-D₁ (894 nm), Cs-D₂ (852 nm), Rb-D₁ (795 nm), acetylene R9 (1520 nm) and P9 (1530 nm) transitions with the single monolithic OPO.