In order to study the depolarization properties of an improved Lyot depolarizer with monochromatic light, the theory of multi-beam superposition is adopted. The dependences of degree of depolarization (D) on vibration azimuth angle (VAA) and total retardation (TR) are analyzed. The results show that D is ideal for any VAA when TR is δ=(N+1/2)π (N is an integer) on the basis of wedge angle large enough. And when δ=Nπ, VAA makes the most significant impact on D. When δ is assigned to the other values, the impact on D made by VAA is between the former two. Using a 405 nm semiconductor laser, experiments for measuring D of the sample with wedge angle of 6° are conducted. The theo-retical results are well verified by experiments. D is over 98.8% when TR is nearly δ=(N+1/2)π by changing the incident angle.
We demonstrate a laser-diode （LD） pumped actively Q-switched laser with Nd：Sc0.2Y0.5SiO5 （Nd：SYSO） crystal for the first time. A stable actively Q-switched laser is obtained at dual wavelengths of 1 075.2 nm and 1 078.2 nm. The maximum average output power of 720 mW is obtained at the repetition rate of 15 kHz under the pump power of 8.7 W. The minimum pulse width of 58 ns is obtained at the repetition rate of 5 kHz under the pump power of 8.7 W, corresponding to the peak power of 1.9 kW and the pulse energy of 112 μJ.
