Backward THz Emission from Two-Color Laser Field-Induced Air Plasma Filament
Abstract
Two-color laser field-induced plasma filaments are efficient broadband terahertz (THz) sources with intense THz waves emitted mainly in the forward direction, and they have been investigated intensively. However, investigations on the backward emission from such THz sources are rather rare. In this paper, we theoretically and experimentally investigate the backward THz wave radiation from a two-color laser field-induced plasma filament. In theory, a linear dipole array model predicts that the proportion of the backward emitted THz wave decreases with the length of the plasma filament. In our experiment, we obtain the typical waveform and spectrum of the backward THz radiation from a plasma with a length of about 5 mm. The dependence of the peak THz electric field on the pump laser pulse energy indicates that the THz generation processes of the forward and backward THz waves are essentially the same. As the laser pulse energy changes, there is a peak timing shift in the THz waveform, implying a plasma position change caused by the nonlinear-focusing effect. Our demonstration may find applications in THz imaging and remote sensing. This work also contributes to a better understanding of the THz emission process from two-color laser-induced plasma filaments.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- May 10, 2023
- Source ID
- 10.3390/s23104630
Entities
People
- Jianming Dai
- Liyuan Liu
- Xi-Cheng Zhang
- Yuhang He
- Yuxuan Chen
- Zhen Tian
Organizations
- Air Force Office of Scientific Research
- National Natural Science Foundation of China
- National Science Foundation
- Tianjin University
- University of Rochester