System and method for generating high-intensity terahertz wave by double plasmas with adjustable spacing

Abstract

The invention discloses a system and method for generating a high-intensity terahertz wave by double plasmas with an adjustable spacing. The system comprises a laser, an optical parametric amplifier,a chopper, a climbing device, a laser beam expander, a spatial light modulator, a mirror, a BBO crystal, a first off-axis parabolic mirror, a second off-axis parabolic mirror, a filter, and a siliconwafer which are set along the light path in order. By adjusting the spacing between phase diagrams of two pairs of Fresnel lens loaded on the spatial light modulator and the rotation angle of the symmetric axis, the system and method can control the spacing and spatial distribution between double plasmas, which not only improves the intensity of the terahertz wave, but also precisely controls theenergy and polarization state of the terahertz wave, fills in the vacancy in the technical field of high-intensity terahertz wave generation, and has strong scientific research and practical application value. The system has the advantages of simple structure, low construction cost, easy maintenance, high stability. The generated terahertz wave has stronger energy and wider spectrum, and can facilitate spectrum measurement.

Description

technical field [0001] The present invention relates to the technical field of terahertz wave generation, in particular to a system and method for generating high-intensity terahertz waves with adjustable spacing of dual plasmas. Background technique [0002] The technology of focusing ultrashort laser pulses in the surrounding air to directly generate terahertz has attracted widespread attention in recent years. This method can generate terahertz waves at a distance (up to several kilometers away), so the application prospect is very bright. [0003] When a high-energy ultrashort laser pulse is focused in the air, the air at the focal point will ionize to form a plasma, and the resulting mass dynamics will form a large density difference between the ion charge and the electronic charge, and This charge separation process results in powerful electromagnetic transients that emit terahertz radiation. [0004] In previous experiments, a femtosecond laser was generally used to ...

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Problems solved by technology

However, the intensity of the generated terahertz wave is not very large, which cannot meet the needs of use

In 2007, Y.Liu et al. found a method to generate terahertz waves by focusing double plasmons with a single lens, but the spacing and spatial distribution of the double plasmons cannot be precisely controlled

In 2016, Sun Wenfeng and others invented a method of modulating the terahertz spectrum with front and rear dual filaments, but the intensity and generation efficiency of terahertz waves have not been significantly enhanced under this setting

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