Frequency upconversion of semiconductor diode lasers

A number of different techniques have been used for nonlinear frequency upconversion of near-infrared semiconductor diode lasers. Intracavity frequency doubling of a diode-laser-pumped 946-nm NdrYAG laser led to the generation of 9.5 mW of blue 473-nm power. A special electronic servo technique was devised to lock the output frequency of a single-mode GaAlAs diode laser to a monolithic KNbO3 resonator. Using this approach, 41 mW of 428-nm output were obtained with an electrical-to-optical conversion efficiency of ∼10%. Strained-layer InGaAs/GaAs diode laser operating at ∼1 μm have been fabricated for non-critically phase-matched frequency doubling in KTiOPO4. A 802-nm GaAlAs diode laser was used for upconversion pumping of a YLiF4+ laser which operates at 551 nm with a threshold power of 50 mW at 77K.