Tunable Pr3+:LiYF4 lasers in the green-red spectral region

Abstract

A tunable Pr³⁺:LiYF₄ laser using a single birefringent filter (BF) plate under excitation with a frequency doubled optically pumped semiconductor laser was demonstrated to operate at nine different laser wavelengths of 523, 546, 604, 613, 639, 645, 670, 698, and 720 nm. Within these wavelengths, several new wavelengths of 613, 639, 645, and 670 nm were obtained. The total tuning range exceeded 190 nm in the visible spectral range on nine intervals between 523 nm and 720 nm. The highest output power of 2.32 W was achieved at an emission wavelength of 523 nm with a slope efficiency of 61.5% and an optical-to-optical efficiency of 52.1% with respect to the absorbed pump power. Moreover, by adjusting the rotation angle of the BF plate, a continuous-wave simultaneous dual-wavelength Pr³⁺:LiYF₄ laser operating at 698 and 720 nm was also demonstrated. At an absorbed pump power of 4.45 W, the maximum output powers at 698 nm and 720 nm were 162 mW and 258 mW, respectively.