Junewen CHEN^*, Jun-Ting LIN and Ou-Yang MANG¹

Institute of Mechanical and Aerospace Engineering, Chung-Hua University, Hsin-Chu, Taiwan 30067
¹Institute of Optical Science, National Central University, Chung-Li, Taiwan 320

(Received October 20, 2005; Accepted December 6, 2005)

The mechanism of the slowly opened Q-switch operation was investigated thoroughly. Maximum energy extraction from the resonator could be optimized, and the smallest output beam divergence could be achieved. In this article, we present a detailed analysis that has numerically verified the mode-selection mechanism in the slowly opened Q-switch operation, and the degree of the smaller output laser beam divergence that has been achieved. The mechanism of the slowly opened Q-switch operation is the inherent advantage of the passive saturable absorber in this operation. We can use the maximum energy extraction and the smallest output beam divergence results of the slowly opened Q-switch operation to design and optimize various passive saturable absorbers: plastic dye sheets, LiF:F₂^- color center crystals, Cr⁴⁺:YAG crystals, RG1000 color glass filters, and the single crystal semiconductor saturable absorber wafers that are in developed in our microchip laser systems.

Key words: Pockels' cell, Q-switched modulation, Porro resonator, slowly opened switch, fast opened switch, beam divergence

^*E-mail address: jwchen@chu.edu.tw