A tunable 1319 nm laser with high power and high beam quality

1319 nm laser has important applications in fields such as fiber optic communication, laser medicine, laser color display, medical imaging and public safety. In addition, 1319 nm laser and Nd:YAG main spectral line 1064 nm can obtain 589 nm yellow light that resonates with sodium atoms through nonlinear-optics sum frequency generation, which has been successfully applied in adaptive optical systems. For uniformly widened Nd:YAG 1319 nm transitions, using a standing wave cavity will result in spatial hole burning effect, causing longitudinal non-uniformity in the intensity distribution inside the cavity. As the pump power increases, the spatial-hole burning effect will cause multiple longitudinal mode oscillations, resulting in broadening of the laser spectral line. Suppressing the multi longitudinal mode oscillation in the standing wave cavity with an etalon will cause a significant increase in cavity loss, resulting in a decrease in output power. The ring cavity enables the laser to operate in a traveling wave manner, eliminating the spatial-hole burning effect. When a certain longitudinal mode vibrates inside the cavity, it will consume the gain of other longitudinal modes, thereby suppressing the oscillation of multiple longitudinal modes. Therefore, it is widely used to obtain narrow-linewidth laser output. A three-mirror ring cavity with 808 nm semiconductor laser side pumped Nd:YAG crystal is used to obtain a tunable 1319 nm laser with high power and high beam quality. Inhibition of 1064 nm and 1338 nm spectral line oscillation in Nd:YAG is achieved through cavity mirror coating and insertion of an etalon, respectively. The Faraday rotator, half wave plate, and polarizer form a unidirectional device that allows the laser to operate in one direction. When the LD pump power is 96 W, a 1319 nm polarized laser output with an average power of 10 W is obtained under thermal near unstable cavity operation conditions, and the beam quality factors are M²_x = 1.20 and M²_y= 1.26. By precisely controlling the temperature of the etalon, the laser wavelength can be finely tuned from 1318.888 nm to 1319.358 nm with a tuning range of 470 pm (81 GHz) and a tuning accuracy of 0.7 pm (125 MHz).