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采用射频磁控溅射和热退火处理技术制备SiNx/Si/SiNx多层薄膜,测试了纳米硅晶粒平均尺寸、光学带隙和薄膜对1064nm激光的非线性吸收系数。建立SiNx/Si/SiNx多层薄膜被动调Q的Nd∶YVO4双波长激光器速率方程,得到双波长调Q脉冲的数值模拟结果。在激光二极管(LD)端面抽运的三镜复合腔Nd∶YVO4激光器中,SiNx/Si/SiNx多层薄膜作为可饱和吸收体同时实现了双波长激光被动调Q,获得20ns的1064nm激光脉冲和19ns的1342nm激光脉冲输出。研究表明,薄膜对1064nm和对1342nm的双光子饱和吸收是双波长激光被动调Q的直接原因;激光器两个支腔输出损耗的差别和薄膜对两个波长的非线性吸收系数的相对值影响了双波长脉冲的宽度和时间间隔。
The SiNx / Si / SiNx multilayers were prepared by radio frequency magnetron sputtering and thermal annealing. The average size of nano-silicon grains, the optical band gap and the nonlinear absorption coefficient of 1064nm laser were measured. The rate equation of Nd: YVO4 dual-wavelength laser with passively Q-switched SiNx / Si / SiNx multilayers was established, and the numerical simulation results of dual-wavelength Q-switched pulses were obtained. In the three-mirror composite cavity Nd: YVO4 laser pumped by the laser diode (LD) end face, the SiNx / Si / SiNx multilayers as the saturable absorber simultaneously achieve the dual-wavelength laser passively Q-adjusting to obtain a 10 ns laser pulse of 20 ns and 19ns 1342nm laser pulse output. The results show that the two-photon saturation absorption at 1064nm and 1342nm is the direct reason for the passive Q-switched Q-switched laser. The difference between the two laser cavity’s output losses and the relative value of the film’s nonlinear absorption coefficient at two wavelengths The width and time interval of the two-wavelength pulse.