Terahertz-assisted even harmonics generation in silicon

Yingying Ding; Yushan Zeng; Xieqiu Yu; Zhe Liu; Junyu Qian; Yanyan Li; Yujie Peng; Liwei Song; Ye Tian; Yuxin Leng; Ruxin Li

doi:10.1016/j.isci.2022.103750

Terahertz-assisted even harmonics generation in silicon

iScience. 2022 Jan 7;25(2):103750. doi: 10.1016/j.isci.2022.103750. eCollection 2022 Feb 18.

Authors

Yingying Ding^{1

2}, Yushan Zeng¹, Xieqiu Yu^{1

2}, Zhe Liu¹, Junyu Qian^{1

2}, Yanyan Li¹, Yujie Peng¹, Liwei Song¹, Ye Tian¹, Yuxin Leng¹, Ruxin Li¹

Affiliations

¹ State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, P.R. China.
² Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy, Beijing 100049, P.R. China.

Abstract

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.