Abstract
Solid-state lasers is one of the most active region of laser research, because of its characteristics such as high efficiency, long life, compact size, and high quality mode. For many applications, especially the nonlinear frequency conversion, it needs a high peak power laser source. Although there have been various laser source capable of producing sufficient laser energy, the cost and the size of the laser system is unfriendly to users. Our goal is to buildup a more economic and high efficiency active Q-switched laser. In this thesis, we approached the higher and steadier power by reducing the cross-section area from 3x3 mm2 to 1x1 mm2. When the dimension of the gain medium is reduced, the overlapping efficiency between the pumping beam and the oscillating beam is getting higher, and it also reduces the path of heat conductivity. The maximum output power under CW operation is 6W with 85% output coupler, and its slope efficiency is 31.78%. The M2 value of the cavity mode is about 1.69. The focal length of thermal lens is 25cm. The active Q-switched system provides high repetition rate that can increase the signal to noise ratio. It increases the accuracy and simplify the optical measurement. The maximum output energy under pulse operation is 559uJ and the pulse width is 8.7ns with a 70% reflectance output coupler. The self-design water-cooling system could conduct the heat from the gain medium and AO crystal efficiently, so that the laser output power could sustain stable.