Investigation on the linewidth characteristics of 972.26 nm BBO-OPO with a volume Bragg grating output coupler

The spectral linewidth characteristics of BBO-optical parametric oscillator (OPO) with a volume Bragg grating (VBG) output coupler were investigated in theoretical simulation and experimental validation. Superior performance in narrowing the linewidth of OPO signal light could be obtained when lower reflectivity VBG was employed. In a concave-VBG cavity, pumped by a 532.23 nm single-longitudinal -mode (SLM) laser at 1 kHz repetition rate with maximum power of 6.3 W, 1.2 W power of 972.26 nm signal light with 3 pm linewidth was achieved when a VBG with 80% reflectivity was used. The pulse duration was around 2.2 ns, and the optical conversion efficiency of OPO signal light was up to 19%. Finally, 486.13 nm blue laser with 1.4 pm spectral linewidth was obtained by using one single LBO crystal as the second harmonic generator.