Adjustable terahertz radiation source based on femtosecond laser induced liquid crystal

Abstract

The invention discloses an adjustable terahertz radiation source based on femtosecond laser induced liquid crystal. The adjustable terahertz radiation source comprises a light source, a first lens and a liquid crystal box which are arranged in sequence, wherein the liquid crystal box comprises a first substrate, a first light orientation layer, a liquid crystal layer, a second light orientation layer, graphene and a second substrate which are arranged in sequence, the light source outputs femtosecond laser, the femtosecond laser passes through the first lens and is focused on the liquid crystal box, terahertz waves are generated, the liquid crystal box can be connected with external voltage equipment, and the terahertz waves are modulated by externally applying an electric field to the liquid crystal box to control the properties of liquid crystals. The nonlinear characteristic of a liquid crystal material is utilized, terahertz signals are generated under induction of the femtosecond laser, and terahertz wave peak value electric field intensity linearly changes along with pump light power; and terahertz waves with adjustable intensity, phase and polarization are generated by externally applying an electric field to the liquid crystal box.

Description

technical field [0001] The invention relates to an adjustable terahertz radiation source, in particular to an adjustable terahertz radiation source based on a femtosecond laser-induced liquid crystal. Background technique [0002] Terahertz (THz) waves are electromagnetic waves with a frequency between 0.1 and 10 THz, which have the following advantages: high permeability, non-metallic and non-polar materials have less absorption of THz waves; condensed matter and biomacromolecular skeleton vibration and The rotational energy level and the weak interaction between molecules are in the THz frequency band; it has extremely high directivity and strong cloud penetration ability, and can achieve a wireless transmission rate above Gbit / s. The above advantages make terahertz science and technology in the safe Inspection, biomedicine, non-destructive detection, high-speed communication and many other fields have important application prospects. As a key element in the development o...

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Problems solved by technology

Semiconductors are optically isotropic, and terahertz radiation needs to be generated under specific pump light; the refractive index difference between the pump light band and the terahertz band of the LN crystal is large, and phase matching cannot be directly achieved, and an external tilt pump is required. The terahertz radiation can only be generated by the optical wavefront device; organic crystals have higher requirements on the wavelength of the laser due to the existence of phonon absorption bands in the terahertz band, and the phase and spectrum of the generated terahertz wave are complex, which will lead to multi-period waveforms. In addition, the above-mentioned terahertz wave Hertzian radiation sources cannot directly modulate terahertz waves

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