新型硫化钼可饱和吸收体的制备及其固体锁模皮秒激光研究

Because of good passive mode-locked laser features of graphene, the research of a new type of two-dimensional material similar to graphene-molybdenum sulfide (MoS2) has attracted much attention. The fiber mode-locked lasers based on MoS2 have been reported. Due to nonlinear effect, the output power and pulse energy of fiber laser is limited. In order to obtain high-power passive mode-locked laser, the solid-state mode-locked laser based on MoS2 has attracted more attention. However, solid-state mode-locked laser based on MoS2 has never been reported. In our project, we study the relationship between the concentration of sulfide, the spinning of catalyst, precision of temperature control, heating rate and the area and quality of MoS2 through chemical vapor deposition method. Coating a dielectric film can improve the damage threshold of MoS2 saturable absorber. The MoS2 absorber with high quality is obtained. The relationship between the formation and stable operation of passive mode-locked laser pulses and the macro parameters of the modulation depth and saturation fluence of MoS2 is revealed. Theoretical model of passive mode locking based on MoS2 is established. The parameters of material property of saturable absorber is improved and optimized. High power passively mode-locked based on MoS2 saturable absorber is successfully obtained. This research has significant innovation and practicality. It is a new research method of mode-locked laser characteristic based on new type of MoS2 saturable absorber.

由于石墨烯优秀的被动锁模激光特性，因此类石墨烯的新型二维材料－硫化钼（MoS2）的研究备受关注。MoS2可饱和吸收体的光纤锁模激光器已有报导。由于非线性效应，光纤激光输出功率和脉冲能量受到限制。为获得高功率被动锁模激光，MoS2固体锁模激光特性成为研究热点，但国内外未见MoS2在固体激光器中实现连续锁模的报导。本项目研究中采用化学气相沉积法，深入研究硫的浓度、催化剂的旋涂、控温精度、升温速度等对MoS2的制备面积、质量的影响，采用镀保护膜等方法提高其激光损伤阈值。制备出高质量MoS2吸收体。揭示基于MoS2被动锁模激光脉冲形成及稳定运转与调制深度、饱和通量等宏观参量的关系。建立MoS2非线性饱和吸收被动锁模的理论模型。不断完善和优化可饱和吸收体的材料特性等参数，成功获得基于硫化钼的被动锁模皮秒激光运转。该研究具有显著的创新性和实用性，为新型MoS2吸收体及被动锁模激光特性研究开辟了新方案。

石墨烯具有优秀的被动锁模激光特性，此类石墨烯的新型二维材料－硫化钼（MoS2）的 研究备受关注。MoS2可饱和吸收体的光纤锁模激光器已有报导。由于非线性效应，光纤激光输 出功率和脉冲能量受到限制。为获得高功率被动锁模激光，MoS2固体锁模激光特性成为研究热点。项目采用改进的CVD系统在石英基底材料上大面积（4cm2的方形）单层连续薄膜的制备，并且设计了锁模激光腔型研究MoS2材料，成功实现了连续锁模激光输出，获得了295mW的锁模激光输出，脉冲重复频率为79.5 MHz，脉冲能量为3.7 nJ，光光转换效率为11.2%。MoS2可饱和吸收体的光学损伤阈值大于345 MW/cm2。这是第一次将CVD方法制备的MoS2可饱和吸收体应用于固体锁模领域。由于该MoS2可饱和吸收材料具有大尺寸、高透过率、低非饱和损耗、高损伤阈值的优势，将在固体锁模激光器中有重要应用。