Efficient generation at 421 nm by resonantly enhanced doubling of GaAlAs laser diode array emission

The 842‐nm diffraction‐limited emission from an injection‐locked laser diode array was frequency doubled using a monolithic spherical‐mirror KNbO3 crystal cavity. Maximum unidirectional external 421 nm power of 24 mW was generated with 167 mW of pump power. Maximum total internal second‐harmonic power and conversion efficiency of 64 mW and 45% were obtained. Effects of heating in the crystal are described.