Abstract-Guiding and emission of milijoule single-cycle THz pulse from laser-driven wire-like targets

Yushan Zeng, Chuliang Zhou, Liwei Song, Xiaoming Lu, Zhongpeng Li, Yingying Ding, Yafeng Bai, Yi Xu, Yuxin Leng, Ye Tian, Jiansheng Liu, Ruxin Li, and Zhizhan Xu

Simulated THz radiation pattern from tip and wire targets. (a) Radiation power pattern from the tip target. The blue line indicates the main lobe direction (which is 17° when 0.18 THz frequency is simulated). The inset represents a frame of electric vector distribution in the transverse cross section. (b) Left: 3D profile of the 0.18 THz frequency radiation power emitted from a 200 µm diameter, 60 mm long wire with a 1 mm diameter semicircle presented at end. Right: A slice distribution of the radiation intensity cutted at 𝜑$\phi$ = 90° (y-z plane), showing asymmetric energy distribution caused by the wire curvature. (c) Simulated electric field evolution (in y-z plane) respectively from the tip target (upper row) and wire (lower row, without curvature at wire end) in time domain. The t=0 has been set to the time when the field front arrives the waveguide end.

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-28-10-15258

The miscellaneous applications of terahertz have called for an urgent demand of a super intense terahertz source. Here, we demonstrate the capability of femtosecond laser-driven wires as an efficient ultra-intense terahertz source using 700 mJ laser pulses. When focused onto a wire target, coherent THz generation took place in the miniaturized gyrotron-like undulator where emitted electrons move in the radial electric field spontaneously created on wire surface. The single-cycle terahertz pulse generated from the target is measured to be radially polarized with a pulse energy of a few milijoule. By further applying this scheme to a wire-tip target, we show the near field of the 500 nm radius apex could reach up to 90 GV/m. This efficient THz energy generation and intense THz electric field mark a substantial improvement toward ultra-intense terahertz sources.

© 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Strong Spatial Confinement of Terahertz Wave inside Femtosecond Laser Filament

Jiayu Zhao, Wei Chu, Zhi Wang, Yan Peng, Cheng Gong, Lie Lin, Yiming Zhu, Weiwei Liu, Ya Cheng, Songlin Zhuang, and Zhizhan Xu

ACS Photonics, Just Accepted Manuscript

DOI: 10.1021/acsphotonics.6b00512

Publication Date (Web): November 8, 2016

Copyright © 2016 American Chemical Society

http://pubs.acs.org/doi/abs/10.1021/acsphotonics.6b00512

In this paper, a new experimental phenomenon is demonstrated. During the femtosecond laser filamentation, the generated terahertz (THz) pulse has been found to be strongly confined inside the plasma channel, reaching a spatial diameter of a few tens of micrometres. It has been attributed to the formation of a plasma negative dielectric waveguide induced by the transverse inhomogeneous plasma density distribution. The new experimental phenomenon will renew the understanding of the THz wave generation and propagation dynamics during the femtosecond laser and air plasma interaction. Due to this strong spatial confinement, THz electric field strength could be enhanced by orders of magnitude, potentially providing a new approach to perform THz nonlinear optics with low laser energy.

Abstract-Terahertz Wave Guiding by Femtosecond Laser Filament in Air

Jiayu Zhao, Yizhu Zhang, Zhi Wang, Wei Chu, Bin Zeng, Ya Cheng, Zhizhan Xu, Weiwei Liu

http://arxiv-web3.library.cornell.edu/abs/1310.5435

(Submitted on 21 Oct 2013)

Femtosecond laser filament generates strong terahertz (THz) pulse in air. In this paper, THz pulse waveform generated by femtosecond laser filament has been experimentally investigated as a function of the length of the filament. Superluminal propagation of THz pulse has been uncovered, indicating that the filament creates a THz waveguide in air. Numerical simulation has confirmed that the waveguide is formed because of the radially non-uniform refractive index distribution inside the filament. The underlying physical mechanisms and the control techniques of this type THz pulse generation method might be revisited based on our findings. It might also potentially open a new approach for long-distance propagation of THz wave in air.

Abstract-Waveform-Controlled Terahertz Radiation from the Air Filament Produced by Few-Cycle Laser Pulses

http://arxiv.org/abs/1204.1860

Ya Bai, Liwei Song, Rongjie Xu, Chuang Li, Peng Liu, Zhinan Zeng, Zongxin Zhang, Haihe Lu, Ruxin Li, Zhizhan Xu

(Submitted on 9 Apr 2012)

Waveform-controlled Terahertz (THz) radiation is of great importance due to its potential application in THz sensing and coherent control of quantum systems. We demonstrated a novel scheme to generate waveform-controlled THz radiation from air plasma produced when carrier-envelope-phase (CEP) stabilized few-cycle laser pulses undergo filamentation in ambient air. We launched CEP-stabilized 10 fs-long (~ 1.7 optical cycles) laser pulses at 1.8 {\mu}m into air and found that the generated THz waveform can be controlled by varying the filament length and the CEP of driving laser pulses. Calculations using the photocurrent model and including the propagation effects well reproduce the experimental results, and the origins of various phase shifts in the filament are elucidated.

Comments:	5pages, 5 figures
Subjects:	Optics (physics.optics); Plasma Physics (physics.plasm-ph)
Cite as:	arXiv:1204.1860v1 [physics.optics]