Diode-laser-pumped continuous-wave doubly linear resonator sum-frequency mixing red laser at 689 nm

We report for the first time a coherent red radiation at 689 nm by intracavity sum-frequency generation of the 1319- and 1444-nm laser-lines of two Nd:YAG lasers. Using type-II critical phase matching KTP crystal, 689-nm red laser was obtained by 1444- and 1319-nm intra-cavity sum-frequency mixing, and output power of 156 mW was obtained. At the output power level of 156 mW, the output power stability is better than 5.0% and laser beam quality M 2 factor is 1.23.