ReS_(2)薄膜的超快载流子动力学和太赫兹发射研究

Ultrafast carrier dynamics and terahertz emission in ReS_(2) thin films

基于超快时间分辨光谱实验手段,研究了化学气相沉积(chemical vapor deposition,CVD)生长的ReS_(2)薄膜的超快载流子动力学和太赫兹发射。分别利用光泵浦探测和光泵浦太赫兹发射两套系统对ReS_(2)薄膜进行了测试,结果表明:ReS_(2)薄膜具有超快的载流子热化过程和亚纳秒量级的复合过程;在飞秒激光泵浦下能够产生频谱宽度为2.5 THz的太赫兹辐射。通过分析太赫兹辐射随泵浦光入射角改变而出现极性相反的现象,得出ReS_(2)薄膜产生太赫兹辐射的主要机制为表面场效应。研究结果不仅有助于理解ReS_(2)薄膜对超快激光脉冲的瞬态响应,而且为太赫兹光子器件(如太赫兹发射器等)的研究设计提供了重要参考。

In this paper,the ultrafast optical response of chemical vapor deposition(CVD)grown ReS_(2) thin films is investigated by means of ultrafast time-resolved spectroscopy.The optical pump probe study shows that the ReS_(2) thin films have ultrafast carrier thermalization processes and sub-nanosecond scale compounding processes.Optical pumping terahertz emission tests show that the ReS_(2) films are capable of producing terahertz radiation with a spectral width of 2.5 THz under femtosecond laser pumping.The polarity of the terahertz radiation is reversed with the change of the pump light incidence angle.The analysis shows that the main physical mechanism of terahertz emission from femtosecond-pumped ReS_(2) films is the surface field effect.The microscopic mechanism elucidated in this study has important reference value for the application of ReS_(2) thin films in ultrafast and terahertz optoelectronic devices.