Nonlinear THz-nano metasurfaces

• Main Authors: Dong, Tian, Li, Shaoxian, Manjappa, Manukumara, Yang, Peidi, Zhou Jiangping, Kong, Deyin, Quan, Baogang, Chen, Xieyu, Ouyang, Chen, Dai, Fei, Han, Jiaguang, Ouyang, Chunmei, Zhang, Xueqian, Li, Junjie, Li, Yang, Miao, Jungang, Li, Yutong, Wang, Li, Singh, Rajan, Zhang, Weili, Wu, Xiaojun
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2022
• Subjects: Science::Physics; Metasurfaces; Nano-Gaps
• Online Access: https://hdl.handle.net/10356/159681
• Institution: Nanyang Technological University

Extreme terahertz (THz) science and technologies, the next disruptive frontier in nonlinear optics, provide multifaceted capabilities for exploring strong light-matter interactions in a variety of physical systems. However, current techniques involve the need for an extremely high-field free space THz source that is difficult to generate and has limited investigations to a rather weak and linear regime of light-matter interactions. Therefore, new approaches are being sought for the tight confinement of THz waves that can induce nonlinear effects. Here, a nonlinear “tera-nano” metasurface is demonstrated exhibiting extremely large THz nonlinearity and sensitive self-modulation of resonances at moderate incident THz field strengths. A record deep-subwavelength (≈λ/33 000) confinement of strongly enhanced (≈3200) THz field in a nano-gap (15 nm) exhibits remarkable THz field-tailored nonlinearity. Further, ultrafast injection of photocarriers reveals a competition between nonlinear THz field-induced intervalley scattering and optically driven interband excitations. The results on “tera-nano” metasurfaces enable a novel platform to realize enhanced nonlinear nano/micro composites for field-sensitive extreme THz nonlinear applications without the need for intense THz light sources.