Noncritically phase-matched frequency doubling using 994 nm dye and diode laser radiation in KTiOPO₄

The characteristic properties of noncritically phase-matched frequency doubling in KTiOPO4 have been investigated using ∼1 μm radiation from a Styryl-13 dye laser. Noncritically phase-matched type II second-harmonic generation was found to occur at 994.3 nm. The unusually wide angle, temperature, and wavelength tolerances observed for this nonlinear process are attractive for the design of practical blue-green laser sources. A special strained-layer InGaAs diode laser was fabricated to operate at 994 nm and generation of blue-green 497 nm radiation by noncritically phase-matched frequency doubling was demonstrated.