研究了一种新型激光晶体Na+,Yb3+:CaF2在激光二极管抽运下的激光性能。该晶体仅以自调Q方式运转,激光波长为1.05 μm,最低抽运吸收阈值功率仅30 mW,功率密度为0.60 kW/cm2。当输入功率接近5 W时,脉冲宽度稳定在1.5 μs,相应的重复频率为28 kHz。采用半导体可饱和吸收镜对Na+,Yb3+:CaF2晶体进行被动锁模,获得自调Q被动锁模激光脉冲。单束输出功率为180 mW,自调Q脉宽为7 μs,重复频率为5.2 kHz,其包络下的锁模超短激光脉冲的变换极限脉冲宽度为1 ps,重复频率为183 MHz,对应脉冲峰值功率为27 kW。

Laser performances of a new Na+,Yb3+:CaF2 crystal under laser diode pumping were demonstrated. This crystal only operated in the self-Q-switched scheme, with laser wavelength of 1.05 μm, and minimum pump absorbed power of 30 mW corresponding to power density of 0.60 kW/cm2. On 5 W incident power, the repetition rate and width of the self-Q-switched pulses reached 28 kHz and 1.5 μs, respectively. By using a semiconductor saturable absorber mirror (SESAM), simultaneous transform-limited 1 ps passively mode-locked pulses, with the average output power of one laser beam 180 mW and the repetition rate of 183 MHz, were obtained under the self-Q-switched envelope induced by the laser medium. The corresponding pulse peak power arrived at 27 kW, indicating the promising application of Yb3+,Na+-codoped CaF2 crystals in achieving ultra-short pulses and high pulse peak power.