Single mode-locking pulse generation underneath the Q-switched envelope of the doubly QML green laser with EO and GaAs

Abstract

By using electro-optic (EO) modulator and GaAs saturable absorber, a diode-pumped doubly Q-switched and mode-locked (QML) YVO4/NdYVO4/KTP laser at 0.53μm is realized. The experimental results show both the pulse width of the Q-switched envelope and the number of the mode-locking pulse underneath the Q-switched envelope decrease with increasing pump power. When the pump power exceeds 7.09W and the repetition rate of EO is 1kHz, a single mode-locking pulse underneath the Q-switched envelope can be generated. At the pump power of 8.76W, the pulse width of the single mode-locking pulse is evaluated to be sub-nanosecond 700ps and the corresponding peak power is 150kW. By using a hyperbolic secant square function and considering the Gaussian distribution of the intracavity photon density, the coupled equations for diode-pumped doubly QML YVO4/Nd:YVO4/KTP green laser are given and the numerical solutions of the equations are basically in accordance with the experimental results.