Ultrafast Optical Modulation of Harmonic Generation in Two-Dimensional Materials
Yang Cheng, Hao Hong, Hui Zhao, Chunchun Wu, Yu Pan, Can Liu, Yonggang Zuo, Zhihong Zhang, Jin Xie, Jinhuan Wang, Dapeng Yu, Yu Ye, Sheng Meng, Kaihui Liu
Abstract
The modulation of optical harmonic generation in two-dimensional (2D) materials is of paramount importance in nanophotonic and nano-optoelectronic devices for their applications in optical switching and communication. However, an effective route with ultrafast modulation speed, ultrahigh modulation depth, and broad operation wavelength range is awaiting a full exploration. Here, we report that an optical pump can dynamically modulate the third harmonic generation (THG) of a graphene monolayer with a relative modulation depth above 90% at a time scale of 2.5 ps for a broad frequency ranging from near-infrared to ultraviolet. Our observation, together with the real-time, time-dependent density functional theory (TDDFT) simulations, reveals that this modulation process stems from nonlinear dynamics of the photoexcited carriers in graphene. The superior performance of the nonlinear all-optical modulator based on 2D materials paves the way for its potential applications including nanolasers and optical communication circuits.