Research On Diode-pumped Passiely Q-switched Nd:YAG/Cr⁴⁺:YAG Microchip Laser

Diode-pumped passively Q-switched micro laser with all-solid-state, compact structure, small size, low cost and it's high repetition frequency, short pulse width, high peak power, is widely used in optical communications, laser radar, nonlinear transformation, laser micromachining, laser medical and other fields. Also it can be a seed source in the MOPA system to get a high power laser. A diode-pumped passively Q-switched Nd:YAG/Cr⁴⁺:YAG micro laser with high beam quality and good stability is designed in the paper. And it can be a good seed source. The main research and results are as follows.1. The factors which affect stability of passively Q-switched laser were analyzed from the rate equations of Cr⁴⁺:YAG crystal. The principle of passively Q-switched laser's stability enhancing by pre-pumped method were expounded.2. The effects of output couple reflectivity and the initial transmission of Cr⁴⁺: YAG on the output pulse characteristics were studied. Given the initial transmittance for Cr⁴⁺: YAG crystal, there is an optimum reflectivity of the output coupler mirror to make the output pulse characteristics of the best.3. The effects of pulse repetition frequency continuous tuning range by prepumping parameters were experimentally studied. The pre-pumping optimum conditions were analyzed. The repetition frequency controlled and stable within 2kHz 28 kHz range of the laser pulse output were got in the paper.4. The effects of beam quality by pump laser were experimentally studied. The optimum positon of pump focus spot was determined and a high beam quality laser was got.The single pulse energy of diode-pumped passively Q-switched Nd:YAG/ Cr⁴⁺:YAG micro laser in the paper is 11.5?J, the pulse width is 1.23 ns, the repetition frequency is continuously adjustable in the range 2-28 kHz, the beam quality of M2=1.18. The frequency instability of 2.4% and amplitude instability of 2% were obtained. The micro laser with compact structure, small size, low cost and easy operation can be a good seed source in the MOPA system.