Narrow Linewidth, Nanosecond Pulsed Optical Parametric Oscillator with a Compound Cavity

We report a new type of optical parametric oscillator (OPO) cavity, i.e., a compound cavity OPO. Both the numerical simulation and experimental results show that this type of cavity is superior, in that its threshold is lower than that of a simple narrow-band cavity with dispersive elements, and its external efficiency is increased while its narrow linewidth remains nearly the same across the tunable range of the nonlinear crystals used.