High-peak-power orthogonally-polarized dual-wavelength Nd:YLF/BaWO4 Raman laser

Orthogonally-polarized dual-wavelength laser has significant practical applications in various fields, such asprecision metrology, terahertz radiation generation, differential radar, spectral analysis. The Nd:YLF crystal hastwo orthogonally-polarized emission peaks with comparable emission cross sections, high-energy storagecapability and relatively weak thermal lens effect. Owing to these properties, it has been recognized as asuitable gain medium for generating orthogonally-polarized dual-wavelength laser. In this paper, the Nd:YLFcrystal with low doping concentration is employed as a laser gain medium to produce 1047 nm and 1053 nmdual-wavelength fundamental lasers with orthogonal polarizations, and the risk of thermal cracking of Nd:YLFcrystal is reduced by appropriately increasing the pump spots. Using the intracavity Raman frequency shift inBaWO4 crystal, orthogonally-polarized dual-wavelength Raman lasers at 1159.9 nm and 1167.1 nm are achievedto have high peak power. Under the total incident pump power of 40 W and a pulse repetition rate of 5 kHz,the maximum dual-wavelength Raman output power is obtained to be 2.67 W. The corresponding total opticalconversion efficiency is 6.7%. For 1159.9 nm and 1167.1 nm Raman laser, their maximum average output powervalues are 1.31 W and 1.36 W, respectively. Their narrowest pulse widths are 1.50 ns and 1.53 ns, and thecorresponding peak power values are as high as 174.7 kW and 177.8 kW, respectively. The results show that theproblem of thermal cracking of Nd:YLF crystal at high pump power can be solved by reducing the dopingconcentration and increasing the pump spot. The Nd:YLF/BaWO4 is a promising crystal combination forrealizing orthogonally-polarized dual-wavelength Raman laser