Abstract

We report multiple wavelength cascade laser operation of Tm³⁺YF₄ at room temperature. The laser operated continuously at 1.88 and 2.31µm from the ³H₄ Ä ³H₅ and³F₄→³H₆ transitions, respectively. Pumping was performed longitudinally by a CW Ti:Al₂O₃ laser tuned to the 0.786µm Tm³⁺ absorption peak. Lasing has been previously reported as 2.31 µm and at 1.88µm from Tm³⁺:LiYF₄ under pulse pumped conditions.¹ The laser consisted of a 1.5% Tm³⁺:LiYF₄ crystal and a 10 cm radius of curvature, 99% reflectivity output coupler. The Ti:Al₂O₃ laser pumps the ³H₄ level which decays to the ³H₅ level for output at 2.31 µm. Next, the energy decays via non- radiative multi-phonon processes between the ³H₅ ³F₄ levels. Finally, the ³F₄ level is populated and decays to the ³H₆ level for output at 1.88 µm. We report a 3% slope efficiency and a 2% conversion efficiency for both wavelengths operating simultaneously.

© 1990 Optical Society of America