Narrowband, intracavity-pumped, type-II BaGa2GeSe6 optical parametric oscillator

We present a tunable (6.62-11.34 mu m), singly -resonant, cascade optical parametric oscillator with intracavity pumping of BaGa2GeSe6 in the second stage and spectral narrowing realized by a Volume Bragg Grating acting on the signal wave of the first stage which serves as a pump for the second stage. The maximum energy achieved near 8 mu m in the narrowband regime is 1.1 mJ at 100 Hz (spectral width: similar to 20 cm-1, pulse duration: similar to 7 ns). The overall conversion efficiency from 1 to 8 mu m for broadband and narrowband operation is 4.0% and 3.1%, respectively, corresponding to quantum efficiencies of 31% and 23%.