Blue 459-nm laser source with rapid modulation based on intracavity frequency mixing.

An approach to the development of miniature blue solid-state lasers is described that is based on sum frequency mixing. Noncritically phase-matched sum frequency mixing in potassium titanyl phosphate (KTP) of 1064- and 809-nm radiation to produce blue light at 459 nm is the mechanism used. Since 809 nm corresponds to the strong absorption line of Nd3+ commonly used for IR diode laser pumping of miniature Nd lasers, it is possible to generate blue radiation by intracavity frequency mixing of the 809-nm pump radiation and the circulating 1064-nm laser radiation of a miniature Nd laser. The design of the cavity is described, and the blue output power generated by intra-cavity sum frequency mixing is shown as a function of incident 809-nm pump power. Direct rapid modulation of the blue output power was demonstrated using an acoustooptic device to modulate the pump radiation.