Compact Q-switched Tm:YLF laser with high slope efficiency, high power stability and high beam quality

This paper presents a high-efficiency and actively Q-switched Tm:YLF laser with a compact design by arranging the optical elements closest to each other in a linear cavity. With a flat output coupler (OC), slope efficiency of 74.7% and output power of 12.41 W were achieved in continuous-wave operation. Using a volume Bragg grating (VBG) as the OC and wavelength selector, the output power and slope efficiency of the 1.908 & mu;m laser were 10.65 W and 67.3%, respectively. The corresponding beam quality M2 was about 1.5 at the maximum power. The Tm:YLF laser with VBG revealed high stability with a power fluctuation of 0.45% and central wavelength variation of 0.23 nm for one-hour continuous testing. In pulsed operation at 10 kHz, average power of 10.07 W and slope efficiency of 66.0% were obtained. This actively Q-switched Tm:YLF laser of 10-W level will be an ideal pump source for compact and high-efficiency mid-infrared optical parametrical oscillators for practical applications.