Characterization of laser-diode end-pumped intracavity frequency doubled, passively Q-switched and mode-locked Nd:YVO4 laser

Simultaneous Q-switching and mode-locking in a laser-diode end-pumped intracavity frequency doubled Nd:YVO4/KTP green laser using Cr4+:YAG saturable absorber is experimentally demonstrated. The influence of the initial transmission (T0) of the Cr4+:YAG crystal on the Q-switched mode-locked green pulses as well as on the average green power is characterized by using Cr4+:YAG crystal with various T0. The effect of T0 on the pulse build-up time in intracavity second harmonic configuration is theoretically investigated. It was found that the depth of modulation for the mode-locked pulses is greatly improved at the second harmonic wavelength as compared to that for the fundamental wavelength. The average pulse duration of the individual mode-locked pulse for the second harmonic beam measured to be less than 500ps with a repetition rate of 400MHz.