Experimental and theoretical study of passively Q-switched Yb:YAG laser with GaAs saturable absorber near 1050nm.

Abstract: A diode-end-pumped passively Q-switched ytterbium-doped yttrium aluminum garnet (Yb:YAG) laser with gallium arsenide (GaAs) wafer as saturable absorber has been realized. In the experiment, two pieces of GaAs wafers with respective thicknesses of 400 and 700 μm were used respectively. The output laser characteristics such as the pulse duration, single pulse energy and peak power, have been measured. By using thicker GaAs wafer as saturable absorber, a minimum pulse duration of 3.5ns was obtained with an average output power of 361mW and a pulse repetition rate (PRR) of 25kHz, corresponding to a single pulse energy of 19.6μJ and a peak power of 5.7kW. With a 400μm-thick GaAs wafer as saturable absorber, a maximum output power of 469 mW was achieved. The central wavelength of the laser was measured to be 1050.4nm at pump power of 7.8W and dual wavelength operation peaked at 1049.3nm and 1051.6nm was observed at a high pump power of 10W. By considering Gaussian spatial distribution and the thermal effects in the gain medium, the coupled rate equations for passively Q-switched Yb:YAG laser with GaAs saturable absorber were given. [Copyright &y& Elsevier]