Narrow-linewidth, multimode-background-suppressed dual-wavelength Ti: sapphire laser based on a composite...

A widely tunable, narrow-linewidth dual-wavelength Ti: sapphire laser incorporating a prism pair and a Littman-grating dual self-injection cavity was demonstrated. The prism pair was inserted into the gain cavity to introduce spatial dispersion to enhance the mode selection ability, while the Littman-grating dual self-injection structure in the dispersive cavity further enabled accurate dual-wavelength frequency selection. The combination of the two effectively suppressed the gain of the non-selected longitudinal modes and realize the flexible tuning of the narrow-linewidth dual-wavelength laser, which has been effectively proved in both theoretical calculations and experiments. This made up for the shortcomings of the multimode background and tuning limitation of the typical Littman-grating self-injected Ti: sapphire laser. By independently tuning the end mirrors of the dual gain cavity and the reflectors of the dual dispersive cavity, arbitrary wavelength combination and continuously adjustable intervals of the narrow-linewidth dual-wavelength output was achieved across the 740-870 nm spectral range, maintaining a linewidth of less than 3 pm throughout the entire tuning range. When the pump power was 40.8 W, the maximum total output power of the narrow-linewidth dual-wavelength at 780 nm and 800 nm was 4.2 W, and the conversion efficiency was 10.28%.