Highly efficient and compact laser-diode end-pumped Q-switched Nd:YVO4/KTP red laser

A laser-diode end-pumped acousto-optic (AO) Q-switched Nd:YVO4/KTP red laser by using a plano-concave cavity was demonstrated for the first time. This linear cavity configuration could guarantee not only moderate intracavity focusing on KTP crystal but also good beam quality. Under the absorbed pump power of 14.8 W, the maximum average output power at 671 nm was obtained to be 1.37 W at the repetition frequency of 15 kHz, with the corresponding optical conversion efficiency of 9.3% and the pulse width of 33 ns. The energy of a single pulse and corresponding peak power are estimated to be 91.3 μJ and 2.77 kW, respectively. The rate equations are also numerically solved by introducing the nonlinear loss resulting from generation of second-harmonic wave.