Ti:sapphire laser intracavity difference-frequency generation of 30 mW cw radiation around 4.5 µm.

A cw mid-IR coherent source based on difference-frequency generation is designed and characterized. For mid-IR generation, a periodically poled MgO:LiNbO(3) crystal is placed inside a compact Ti:sapphire laser cavity. This provides high-power pump radiation for the nonlinear process. Optical injection by an external-cavity diode laser ensures single-frequency operation of the Ti:sapphire laser, while signal radiation is provided by a fiber-amplified Nd:YAG laser. Mid-IR radiation can be generated with 3850-4540 nm tuning range, narrow linewidth, Cs-standard traceability, and TEM(00) spatial mode. 30 mW power is obtained at 4510 nm.