Q-switched diode-pumped Nd:YVO4 laser with active fluorescence feedback control

Active feedback control has been implemented in a Q-switched diode-pumped Nd:YVO4 laser by monitoring the fluorescence intensity from the laser crystal. When the initial inversion level indicated by the detected fluorescence has reached a predetermined value, Q-switching is initiated. The output Q pulse is stabler with our feedback scheme based on the fluorescence intensity than that with the conventional Q-switching when pumping source is not stable.