Investigation of Yb:CaWO4 as a potential new self-Raman laser crystal

Abstract

We report on the growth, Raman spectra, absorption and emission spectra, and lasing properties of the Yb:CaWO₄ crystal. The frequencies of all Raman active vibrational modes were obtained. Room-temperature absorption and emission cross-section spectra for π and σ polarizations were determined. The strongest absorption and emission were found to occur for π polarization, with the maximum absorption cross-section measured to be 2.07 × 10⁻²⁰ cm² at 965.5 nm, while the peak emission cross-section at 997.7 nm was 5.60 × 10⁻²⁰ cm². Continuous-wave laser action was demonstrated with a c-cut crystal under the excitation of broad-band 935 nm radiation, generating an output power of 2.0 W at wavelengths around 1026 nm with an optical-to-optical efficiency of 26.3%, while the slope efficiency for laser action could reach 37%. Self-Raman conversion was realized with an a-cut crystal in a passively Q-switched resonator and the Raman gain coefficient was estimated to be 2.6 cm GW⁻¹. Our work reveals the potential of Yb:CaWO₄ as a new self-Raman laser crystal.