Terahertz-assisted even harmonics generation in silicon

作者：Yingying Ding, Yushan Zeng, Xieqiu Yu, Zhe Liu, Junyu Qian, Yanyan Li, Yujie Peng, Liwei Song, Ye Tian, Yuxin Leng, Ruxin Li · 发表于：iScience · 年份：2022 · DOI：10.1016/j.isci.2022.103750 · 被引用次数：14 · 研究领域：Terahertz technology and applications、Photonic and Optical Devices、Photorefractive and Nonlinear Optics

When a biased electric/light field is applied to centrosymmetric crystals like silicon, the broken symmetry creates even-order harmonics radiation which can reveal key insights into the material. Recently, the second harmonic has been generated by THz-induced symmetry breaking, but the observation of higher-order radiation remains largely unexplored. Here, we demonstrate picosecond-level ultrafast, nondestructive symmetry manipulation of silicon crystal by using a 500 kV/cm intense terahertz (THz) electric field. The THz-induced fourth harmonic of the infrared probe is also observed and characterized for the first time. In addition, we find that the even-order harmonics show no dependence on the THz field direction thus it allows for sub-cycle symmetry manipulations. Our study paves the way toward ultrafast all-optical crystal symmetry control in the future high-speed electronics and photonics.