High-power continuous-wave single-frequency diamond Raman laser at 1178 nm

We demonstrate a continuous-wave single-frequency diamond Raman laser operating at 1178 nm by using a linear resonator that is stabilized using an intracavity χ (2) element. Optimization of the single-frequency power was realized by tuning the phase matching in the χ (2) element away from the second-harmonic peak to suppress neighboring modes via sum frequency generation but avoid large losses to the intracavity primary Stokes mode. A maximum single-longitudinal-mode power of 20 W at 1178 nm with an instrument-limited linewidth of 67 MHz was obtained using a 12 GHz multi-longitudinal-mode Yb-doped fiber pump laser at 1018 nm with power of 82 W. This work provides an interesting route for producing single-frequency high-power lasers near 1.2 μm utilizing diamond Raman conversion combined with broadband, high-power, low-cost YDF lasers.