GaAs被动调Q的温度效应研究

Passive Q-switching is an efficient way to obtain nano-second pulsed lasers. Compared with active Q-switching, it possesses the advantages of low cost, easy operation and versatile parameters. So far, the most popular saturable absorber at 1 µm wavelength is Cr4+:YAG crystal, which can generate high quality pulses. GaAs is also a very good saturable absorber, which has high nonlinear coefficient, high damage threshold and stable chemical character, but the pulse stabilization is not always so good. My previous work revealed that the temperature of GaAs can affect the pulse characteristic. Under high temperature, with the influence of the TPA and FCA, the pulses presented high stabilization and shortening effect. We intend to realize a high-performance passively Q-switched laser with GaAs as the saturable absorber, Nd:YAG crystal and mixed vanadate crystals as the laser media , which is very meaningful for promoting the function of the GaAs passively Q-switched lasers.

被动调Q是获取纳秒脉冲激光器的有效手段，与主动调Q相比，被动调Q具有造价低廉、操作简便、参数设计灵活等优势。目前，1µm波段使用最为广泛的被动调Q饱和吸收体是Cr4+:YAG晶体，基于Cr4+:YAG晶体的被动调Q激光器已经产业化。半导体GaAs也是该波段优良的饱和吸收体，具有非线性系数高、光伤阈值高、物化性能稳定等优点，但所获取的脉冲序列稳定性往往较低。本人此前的研究表明GaAs温度的变化可以影响输出脉冲的稳定性及脉冲宽度。在高温条件下，双光子、载流子等非线性吸收方式的介入，使脉冲序列逐渐趋于稳定并伴随着脉冲缩短效应。本项目拟采用GaAs作为饱和吸收体，Nd:YAG晶体和掺钕钒酸盐混晶作为激光介质，深入研究温度对GaAs的脉冲输出性能的影响规律，对提升GaAs被动调Q激光器的性能具有重要意义。

被动调Q是获取纳秒脉冲激光器的有效手段，除了广泛应用的Cr4+:YAG晶体，半导体GaAs也是1微米波段优良的饱和吸收体，具有非线性系数高、光伤阈值高、物化性能稳定等优点，但所获取的脉冲序列稳定性往往较低。本项目采用GaAs作为饱和吸收体，Yb:NaYLa(VO4)2晶体和Yb:NaY(WO4)2晶体作为激光介质，深入研究了GaAs作为饱和吸收体的激光器脉冲输出性能，得出了温度与GaAs被动调Q脉冲的稳定性及脉冲宽度的对应关系，对提升GaAs被动调Q激光器的性能具有重要意义。项目还对GaAs作为2微米激光饱和吸收体的可能性做出了尝试，并与Ho:YAG陶瓷、Tm:KLuW晶体的石墨烯，碳纳米管，SESAM被动调Q激光器性能进行了对比研究。研究结果表明，在高泵浦功率条件下，双光子、载流子等非线性吸收方式的介入，使脉冲序列逐渐趋于稳定并伴随着脉冲缩短效应。