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

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

A 74 pm ultra-narrow linewidth diode laser (LD) claddingding-pumped Tm3+-doped fiber laser was reported. The maximal continuous wave (CW) output power was 14.5 W at 1946 nm, with a slope efficiency of 37.5% and the threshold of 5.3 W. The single-mode double-cladding Tm3+-doped fiber had a core diameter of 15 μm (NA:0.1), and the regular hexagonal inner-cladding diameter was 200 μm (NA:0.46). The high reflection coupler was based on the intra-core fiber Bragg gratings (FBGs), which were directly written into the Tm3+-doped non-photosensitive fiber core by the 800 nm femtosecond laser and a phase mask. The output coupler was the other fiber end with 3.6% Fresnel reflection, and the pump source was a high power 792 nm LD with a 200 μm pigtail fiber output. According to our knowledge, this was the first report on the ultra-narrow linewidth Tm3+-doped fiber laser using intra-core FBGs approximately 2 μm.

Lasing characteristics of a diode-pumped injection seeded Tm,Ho:GdVO4 laser is presented in this letter. A Qswitched output energy of as much as 2 mJ at 20 Hz with a pulse width of 170 ns was obtained. Single-frequency, nearly transform-limited operation of the laser was achieved by injection seeded. The high power and high beam quality of this laser make it well suited for use as a coherent wind lidar transmitter on a space platform. To our knowledge, this work is the first time to investigate the injection-seeded in Tm,Ho:GdVO4 to achieve Q-switched single-longitudinal-mode output laser.Voltage of detector, a.u.