High power terahertz pulses generated in intense laser—plasma interactions

Abstract

Terahertz (THz) radiation has attracted much attention due to its wide potential applications. Though radiation can be generated with various ways, it is still a big challenge to obtain strong tabletop sources. Plasma, with the advantage of no damage limit, is a promising medium to generate strong THz radiation. This review reports recent advances on strong THz radiation generation from low-density gases and high-density solid targets at different laser intensities.

Theoretical investigation on generating terahertz radiation from gas plasma induced by three-color ultrashort lasers

“…[1][2][3][4][5][6][7] For THz generation, thanks to the advent of ultrashort laser pulse with millijoule energy, single-cycle electromagnetic radiation covering THz gap (0.1 THz-10 THz) with MV/cm electric field amplitude can be generated from laser-induced gas plasma. [8][9][10][11] Generation of THz radiation from gas plasma scheme was first demonstrated by Hamster et al [12,13] One single frequency femtosecond (fs) laser beam is focused in the air to ionize the gas, and conical THz emission can be detected at an angle with respect to the direction of propagation. The underlying mechanism was explained as ponderomotive acceleration of the ionized electrons in the plasma.…”

Power dependence of terahertz carrier frequency in a plasma-based two-color generation process

“…Since it was first predicted in 1993, terahertz (THz) emission generated by a laser focused in the air has aroused a considerable amount of interest in various fields, [1,2] including material characterization, nondestructive evaluation, and biomedical and pharmaceutical testing. [3][4][5][6][7] An ultrashort laser fundamental (ω) and second harmonic (2ω) pulses are cofocused in the air to ionize the air molecules, and thus generate a THz wave through four-wave mixing. [8][9][10][11][12] In this model, a highly nonlinear and phase-sensitive asymmetric laser field can be generated, in which the bound gas-phase electrons can acquire a nonzero drift velocity and produce a free electron current with simultaneous emission of THz radiation in the far-field.…”

New terahertz dispersive device for single-shot spectral measurements of terahertz pulse

“…The intense terahertz waves emission from laser plasma interaction of intense ultrashort laser pulses with gas or solid target, due to its unique features of sub-picosecond duration, high peak power, and broadband spectral coverage, attracts significant attention. [1][2][3][4][5] Since the spectral distribution of terahertz emission from the laser plasma interaction contains important information related to the interaction process, it becomes an effective approach to diagnose the interaction by measuring the emission spectrum of single-shot broadband terahertz source. [6] Hereby, it is necessary to gain on a single-shot basis the spectral distribution of broadband terahertz source.…”