Two types of acousto-optically Q-switched Nd:YVO4/KTA singly resonated optical parametric oscillators are performed. One is signal resonant, where a 1.5 μm wave resonates while a 3.5 μm wave does not. The other is idler resonant, where a 3.5 μm wave resonates while a 1.5 μm wave does not. All the experimental elements are kept the same for these two schemes except for the coatings of the optical parametic oscillator cavity output coupler. For these two kinds of lasers, the output characteristics of the threshold, output power, pulse width, peak power, and beam quality are measured and compared.

A stable passively mode-locked laser of Nd3+:Gd0.5Y2.5Al5O12 (Nd:GYAG) disordered crystal is experimentally investigated both using Z-type and W-type cavities with a semiconductor saturable absorbed mirror. The continuous-wave mode-locked threshold of the absorbed pump power is just 1.8 W. The maximum average output power is 210 mW, which is obtained at the absorbed pump power of 2.3 W. The pulse width is measured to be 11.1 ps assuming a Gaussian shape.