Abstract
In this thesis, the theory of Passively Q-witched Laser will be discussed in detail. A Volume Bragg Grating (VBG) was used to eliminate longitudinal mode in cavity. The gain medium was Nd:GdVO4 with 1% Nd doped and the saturable absorber was Cr:YAG. There were four laser systems finished step by step including (1) CW laser generation with linear cavity (2) passively Q-switched laser generation with linear cavity (3) CW laser generation with V-type cavity (4) passively Q-switched generation with V-type cavity. VBG was used in the third and the fourth system to compare with the first and the second system which without VBG. Another saturable absorber Cr:YVO4 was used to try to build a passively Q-switched laser.