Direct modulation of blue radiation from frequency-doubled AlGaAs laser diode using the electro-optic effect in a KNbO3 nonlinear crystal

Abstract
A novel method for modulating frequency‐doubled blue radiation from an AlGaAs laser diode was developed utilizing the electro‐optic effect in a KNbO3 nonlinear crystal. Stable blue radiation was obtained from an external ring resonant cavity containing a KNbO3 crystal. The weakly excited counterpropagating mode in the resonant cavity was re‐injected into the laser diode to establish self‐locking. Nearly 100% intensity modulation was observed when a 3 kV/cm ac electric field was applied parallel to the c axis of the KNbO3 crystal.