A diode-pumped single frequency Tm:YAG laser operating at 2 μm is demonstrated in this letter. The laser crystal is controlled at room temperature by using a thermoelectric cooler. Two solid uncoated fused silica etalons are employed to narrow the laser line-width, the thicknesses of which are 0.1 mm and 1 mm, respectively. By tuning the angle of the etalons, single frequency laser is achieved and the oscillating wavelength can be changed from 2008 nm to 2021 nm. And at each wavelength, single-frequency laser is achieved. The maximum single frequency laser power is up to 75.0 mW with the central wavelength of 2013.9 nm. To our knowledge, this is the first time to obtain single-frequency Tm:YAG laser of 75.0 mW with F-P etalons in the cavity. FSR = 3.75 GHz

High power and high beam quality continuous wave Tm:YLF laser by the dual-end-pumped is presented in this letter. The highest output power reaches 21.3 W when the totally input pump power is 54.6 W. The optical conversion efficiency is 39.0% and the slope efficiency is 47.3%. With an F-P etalon in the cavity, the output center wavelength is tuned to 1908 nm with about 0.5 nm FWHM. With the optimal cavity, the beam quality factor M 2 can be ∼ 1.1. As we know, our work is the first time to investigate the Tm:YLF laser output spectrum with an F-P etalon in the cavity, and acquire near-diffraction limited laser output. Output power, W 25 20 15 10 5 0 60 50 40 30 20 10 0 Incident pumped power, W

We report the room temperature continuous wave and acousto-optically Q-switched Ho:YAG laser double-pass pumped by a diode-pumped Tm:YLF laser. Continuous wave output power of 10.5 W at 2090 nm is obtained under the incident pump power of 18.1 W, corresponding to a conversion efficiency of 58.0% and a slope efficiency of 65.7%. For the Q-switched regime the maximum pulse energy of 1.0 mJ and the minimum pulse width of 25 ns at the repetition rate of 10 kHz are achieved, resulting in a peak power of 40.0 kW.

Continuous wave (CW) and acousto-optical (AO) Q-switch operation of Tm (5 at.%), Ho (0.3 at.%):YAP laser at 2.13 μm wavelength were reported in this paper. The Tm,Ho:YAP crystal was cooled by liquid nitrogen and doubleend-pumped by a 14.2 W fiber-coupled laser diode at 798 nm. Different resonator lengths and output couplers for the pump power were tried. A maximum conversion efficiency of 31.3% and a maximum slope efficiency of 35.2% were acquired with CW output power of 4.45 W. Average power of 4.21 W was obtained at pulse repetition frequency (PRF) of 15 kHz, corresponding to an optical-to-optical conversion efficiency of 29.6% and a slope efficiency of 32.4%. The energy per pulse of 2.3 mJ in 64 ns was achieved at 1.5 kHz with the peak power of 35.8 kW.

A room-temperature diode-end-pumped acoustooptical (AO) Q-switched Tm:GdVO4 laser was firstly reported. The minimum AO Q-switch pulse width was measured to be about 48 ns with output power of 2 W and repetition rate of 5 kHz. Continuous-wave output power of 2.8 W at 1912 nm was obtained under the absorbed pump power of 15 W. In addition, laser pulse widths and the ratio of QCW power/CW power at different repetition rates were discussed.Oscilloscope trace of a Q-switched pulse with a FWHM of 48 ns at a repetition rate of 5 kHz and an output power of 2 W