The present invention discloses a high power Q-switched, intracavity frequency-doubled laser for laser ablation of soft tissue. Operating a high power Q-switched laser in a frequent on-off mode is highly desirable for laser prostatectomy. Giant first pulse may occur when a Q-switched laser is switched from laser-ready mode to pulse-on mode due to sudden depletion of stored energy in the gain medium. Such a giant first pulse may cause power damage of intracavity optics. Besides, temperature shock induced by sudden onset of a high power pulse train may cause optical damage on surface coating of intracavity optics. The present invention contemplates to suppress these giant first pulses and temperature shocks through pre-lasing and ramping profile of laser parameters. Reliable and frequent on-off operation of a diode-pumped, Q-switched, frequency-doubled Nd:YAG laser is demonstrated for output power up to 100 W.