1200  nm pumped Tm³⁺:Lu₂O₃ ceramic lasers

We report on an experimental demonstration of a 1200-nm pumped Tm³⁺:Lu₂O₃ ceramic laser. By using a gain-switched, tunable Cr⁴⁺:forsterite laser, the excitation spectrum was measured, with optimum pumping bands centered near 1198 nm, 1204 nm, and 1211 nm. The highest slope efficiency of 21.5% was obtained at the pump wavelength of 1204 nm. Comparative energy efficiency measurements performed near 1200-nm and 800-nm pumping further showed that nearly 40% improvement was obtained in slope efficiency measured with respect to the incident pump energy for 1200-nm pumping. A transition was further observed from single-wavelength operation at 2066 nm to dual-wavelength operation near 2066 nm and 1967 nm for absorbed pump energies above 50 μJ. In this regime, two consecutive output pulses were observed in the time domain. The shortest temporal duration of the first pulse was 1.1 μs at the incident pulse energy of 105 μJ. The duration and build-up time of the second pulse remained around 5.9 μs and 18.5 μs. We believe that the improved energy efficiency demonstrated for the 1.5% Tm³⁺:Lu₂O₃ ceramic with 1200-nm pumping can be used as an alternative scheme for the excitation of Tm³⁺:Lu₂O₃ ceramic lasers.