Phase Engineering of Giant Second Harmonic Generation in Bi 2 O 2 Se

作者：Zhefeng Lou, Yingjie Zhao, Zhihao Gong, Ziye Zhu, Mengqi Wu, Tao Wang, Jialu Wang, Haoyu Qi, Huakun Zuo, Zhuokai Xu, Jichuang Shen, Zhiwei Wang, Lan Li, Shuigang Xu, Wei Kong, Wenbin Li, Xiaorui Zheng, Hua Wang, Xiao Lin · 发表于：Advanced Materials · 年份：2024 · DOI：10.1002/adma.202409887 · 被引用次数：6 · 研究领域：2D Materials and Applications、Photorefractive and Nonlinear Optics、Acoustic Wave Resonator Technologies

Abstract 2D materials with remarkable second‐harmonic generation (SHG) hold promise for future on‐chip nonlinear optics. Relevant materials with both giant SHG response and environmental stability are long‐sought targets. Here, the enormous SHG from the phase engineering of a high‐performance semiconductor, Bi 2 O 2 Se (BOS), under uniaxial strain, is demonstrated. SHG signals captured in strained 20 nm‐BOS films exceed those of NbOI 2 and NbOCl 2 of similar thickness by a factor of 10, and are four orders of magnitude higher than monolayer‐MoS 2 , resulting in a significant second‐order nonlinear susceptibility on the order of 1 nm V −1 . Intriguingly, the strain enables continuous adjustment of the ferroelectric phase transition across room temperature. An exceptionally large tunability of SHG, approximately six orders of magnitude, is achieved through strain modulation. This colossal SHG, originating from the geometric phase of Bloch wave functions and coupled with sensitive strain tunability in this air‐stable 2D semiconductor, opens new possibilities for designing chip‐scale, switchable nonlinear optical devices.