Narrow-band, tunable 2 μm optical parametric oscillator based on MgO:PPLN at degeneracy with a volume Bragg grating output coupler

Abstract

A degenerate optical parametric oscillator (OPO) using an MgO:PPLN crystal and a volume Bragg grating (VBG) output coupler is presented. By changing the temperature of the VBG, the resonance of the OPO can be tuned exactly on the degeneracy point. A single-longitudinal and a multi-longitudinal mode pump scheme as well as the performance of the optical parametric oscillator on and off degeneracy are compared. It was found that the multi-longitudinal mode pump setup provides superior results with respect to spectral width and stability at degeneracy. At 2128.4 nm, a spectral width of less than 0.7 nm, an output power of 1.7 W with a slope efficiency of 31.8%, and low power fluctuation of 0.3% were achieved.