Watt-level diode-pumped thulium lasers around 2.3 µm

Abstract

We report on efficient diode-pumped mid-infrared lasers based on , , and crystals. These lasers operate in the continuous-wave (CW) regime and deliver watt-level output power at the wavelengths of 2.2–2.3 µm (the transition). In particular, a 1.8 at. % laser pumped at 789 nm generates a maximum CW output power of 1.32 W at 2272–2277 nm with a slope efficiency of 33.1% (with respect to the absorbed pump power), a linear laser polarization (), and a fundamental transverse output mode (the measured , ). In the quasi-CW regime, the output peak power is scaled up to 2.69 W. The pump quantum efficiency and the fractional heat loading are estimated and discussed.