Abstract-Generation of terahertz annular vector beams with arbitrary order from gas-plasma induced by few-cycle vector beams

Honggeng Wang, Ya Bai, Erheng Wu, Zhanshan Wang, Peng Liu, Chengpu Liu



https://www.sciencedirect.com/science/article/abs/pii/S0030401818306345

A method for the generation of annular vector beams (AVBs) with arbitrary order in the THz regime is proposed and numerically confirmed based on the photocurrent model from gas-plasma induced by a near-infrared few-cycle laser driver. Moreover, the variance of its radius R with its azimuthal order L follows a simple rule, i.e., $R\sim L^{1∕2}$, the same as that for the few-cycle laser driver. In contrast, as for the width of spatial intensity annual rings, that of few-cycle laser driver increases with the increase of L, whereas that of THz AVBs decreases.

Abstract-Terahertz necklace beams generated from two-color vortex laser-induced air-plasma

Honggeng Wang, Ya Bai, Erheng Wu, Zhanshan Wang, Peng Liu, and Chengpu Liu

https://journals.aps.org/pra/accepted/2e071N2eC311671ca53515c0e7c290857bc2f6a82

A method for generating a terahertz (THz) necklace beam from a two-color vortex laser-induced air-plasma is proposed and theoretically investigates based on the frequency down-conversion process. The simulation demonstrations based on both the four-wave mixing (FWM) and the photo-current (PC) schemes confirm that the generated THz pulse is a necklace beam without orbital angular momentum (OAM). The origin of OAM vanishment is attributed to the fact that the spatial phase difference of two-color vortex field does not contribute to the phase but only to the amplitude of THz pulse.

Abstract-Absorption of laser plasma in competition with oscillation currents for a terahertz spectrum

Xiaolu Li, Ya Bai, Na Li, and Peng Liu

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-43-1-114&origin=search

We generate terahertz radiation in a supersonic jet of nitrogen molecules pumped by intense two-color laser pulses. The tuning of terahertz spectra from blue shift to red shift is observed by increasing laser power and stagnation pressure, and the red shift range is enlarged with the increased stagnation pressure. Our simulation reveals that the plasma absorption of the oscillation currents and expanded plasma column owing to increased laser intensity and gas number density are crucial factors in the recurrence of the red shift of terahertz spectra. The findings disclose the microscopic mechanism of terahertz radiation and present a controlling knob for the manipulation of a broadband terahertz spectrum from laser plasma.

© 2017 Optical Society of America

Abstract-Generation of largely elliptically polarized terahertz radiation from laser-induced plasma

Honggeng Wang, Na Li, Ya Bai, Peng Liu, Zhanshan Wang, and Chengpu Liu

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-25-25-30987

A novel all-optical control scheme is proposed to continuously tune the THz radiation polarization, where the driving laser is based on a three-pulse configuration with adjustable time delays or intensity ratio. With this scheme, not only is the circularly polarized THz radiation realized, the continuous tuning from circular polarization to linear polarization can also be obtained conveniently just by adjusting time delays or intensity ratio. Moreover, the left or the right chirality of THz radiation can be transformed between each other with suitable time delays.

© 2017 Optical Society of America

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]