Compact blue and green lasers based on nonlinear optical processes

Abstract

Nonlinear optical processes permit the design of miniaturized blue - green laser devices that are pumped by near-infrared sources such as GaAIAs diode lasers. Frequency upconversion of infrared pump light can be achieved by processes that use the nonlinear susceptibility of noncentrosymmetric materials for second harmonic generation or sum-frequency mixing. In addition, two-photon excitation mechanisms including sequential two-step absorption and energy-transfer upconversion can be used to pump visible solid-state lasers with infrared light. The operation of several nonlinear laser devices in the blue - green spectral region has been demonstrated. Intracavity frequency mixing of a 1064-nm Nd:YAG laser and its 809-nm pump source resulted in efficient generation of 459-nm radiation using KTiOPO4 as the nonlinear material. Intracavity frequency doubling of a diode-laser pumped 946-nm Nd:YAG laser was used to generate 473-nm radiation. Two-photon-pumped upconversion lasing at 550nm has been demonstrated in YA103:Er3+ and YLiF4:Er3+ at temperatures ≤90K using infrared cw dye lasers near 800nm as pump sources. © 1988, SPIE.