Efficient generation of blue light by doubly resonant sum-frequency mixing in a monolithic KTP resonator

Efficient generation of blue light is demonstrated by using resonantly enhanced sum-frequency mixing in a monolithic KTP resonator. Two infrared sources, a diode-pumped Nd:YAG laser and a GaAlAs laser diode, were simultaneously coupled into the monolithic cavity and tuned to resonant frequencies, so that high-intensity intracavity fields were built up at both wavelengths. A blue power of 4 mW in a TEM(00) mode was generated with 55% of the 30 mW of 809-nm power and 45% of the 33 mW of 1064-nm power coupled into the standing-wave nonlinear resonator. By using a novel monolithic ring resonator, 2 mW of power was generated in a TEM(00) mode at 462 nm. Electric-field-induced tuning of the resonant frequencies was also demonstrated.