Tunable single- and dual-wavelength nanosecond Ti:Sapphire laser around 765 nm

We report on the longitudinally pumped tunable single- and dual-wavelength nanosecond Ti:Sapphire laser operation around 765 nm by using a Brewster-cut single Ti:Sapphire crystal in combination with an intracavity prism and etalon. Tilting the etalon to a specific angle, single-wavelength operation at 767.9 nm is achieved first, with a maximum output power value of 1.3 W below 5.5 W pump power. Then, increasing the pump power leads to simultaneously operation at dual wavelength (765.0, 771.3 nm), (763.9, 772.2 nm), (763.5, 772.2 nm), and (762.4, 773.7 nm) with a maximum output power of ~ 2.98 W, pulse width of ~ 20 ns, and a laser slope efficiency of about 34.7% at 1 kHz repetition rate. By tilting the etalon, other dual- and single-wavelength laser operations could be achieved. Experimental results show that it is tunable in the region 750–840 nm which here is limited by the reflectivity of the cavity mirrors. We observed, when laser oscillates at dual wavelength, the separation of the wavelengths increased with pump power which could be because of thermal lensing in Ti:Sapphire. The output characteristics versus incident pump power at 1 and 5 kHz repetition rate show output power increases linearly with incident pump power with similar slope for both 1 and 5 kHz repetition rates, whereas pump threshold increased in the case of 5 kHz.