CW and AO Q-switched operation of a dual-crystal Tm, Ho:GdVO4 laser pumped by two diodes

Continuous wave (CW) mode and acousto-optic (AO) Q-switched mode operation of a dual-crystal Tm, Ho:GdVO4 laser is reported. The dual-crystal Tm, Ho:GdVO4 laser with output wavelength of 2.05??m was pumped by two laser diodes (LDs). The Tm, Ho:GdVO4 crystals were cooled by liquid nitrogen and pumped by two fiber-coupled LDs with a center output wavelength of 801.0?nm. A 20.5?W output power was obtained at a 255?mm physical cavity length in CW mode operation, and a 19.6?W average power was obtained at a pulse repetition frequency (PRF) of 10?kHz with a 19?ns pulse duration. Also, the efficiency loss of the laser is not more than 4.4% from CW mode to Q-switch mode, and the M2 factor, which is measured by the traveling knife-edge method, does not exceed 1.2.