"Source: China Science News

Recently, researcher Jun Wang's team at the Laboratory of Functional Materials for Micro- and Nanophotonics, Shanghai Institute of Optics, Chinese Academy of Sciences, has made progress in the study of nonlinear optical response and ultrafast carrier dynamics properties of indium selenide (InSe) nanosheets, revealing the potential of InSe for optoelectronic device applications. The research results were published online in Advanced Optical Materials on Oct. 6.

InSe is a bandgap-tunable layered semiconductor material with nonlinear optical response over a wide wavelength range. The researchers obtained InSe nanosheets with suitable thickness and band gap by liquid-phase exfoliation method and systematically investigated their nonlinear optical and ultrafast carrier dynamics properties at different pulse width scales (ns and fs).

The researchers found that InSe nanosheets are more likely to reach saturation absorption under broad-pulse laser excitation. In addition, the InSe dispersions exhibit different mechanisms of scattering phenomena at different pulse durations due to thermal effects under ns pulse excitation and dynamic spatial self-phase modulation of the laser flow under fs pulse excitation. The optical switching modulation is also achieved by exploiting the competing relationship between saturation absorption at low energy and nonlinear scattering at high energy. The time-resolved pumping probe results show that InSe dispersions have ultrafast saturable absorption processes and photogenic absorption processes possibly caused by free carrier absorption or bandgap reformation.

Experts say that this work on the systematic study of linear and nonlinear optical properties of InSe nanosheets and ultrafast carrier dynamics processes provides experimental and theoretical guidance for the development of InSe based optoelectronic devices.

Related paper information: https://doi.10.1002/adom.202101432