Focal length adjustable terahertz graphene metasurface lens and design method

Abstract

The invention relates to a focal length adjustable terahertz graphene metasurface lens and a design method, and belongs to the field of novel artificial electromagnetic materials and terahertz scienceand technology. The metasurface lens comprises three layers of structures, which are a metal gate layer, a dielectric layer and a graphene micro-structure layer in sequence, wherein a bias voltage control device is arranged between a graphene microstructure and a metal gate, and is used for changing the conductivity of graphene. By changing an arrangement sequence of units, the focal length of the metasurface lens can be moved and kept still along with a bias voltage. Dynamic regulation of a focal point of the lens can be realized, and the focal length of the lens is not sensitive to the material characteristics of the graphene, so that different application requirements can be met; and meanwhile, the metasurface lens has the advantages of high numerical aperture, transmission type, highefficiency, compact structure and the like.

Description

technical field [0001] The invention belongs to the field of novel artificial electromagnetic materials and terahertz science and technology, and specifically relates to a high-efficiency, high-numerical-aperture, transmission-type terahertz plane lens with adjustable focal length and a design method thereof. Background technique [0002] Located at 0.1—10THz (1THz=10 12 Hz) range, due to its small photon energy, no damage to biological tissues, and strong penetrating ability to textiles, plastics, etc., it has extremely high scientific research value in the fields of biomedical imaging and security imaging. Wide application prospects. The terahertz lens is one of the key devices in the imaging system. Existing terahertz lenses are mainly spherical and aspheric lenses made of polyethylene, poly-4-methylpentene, high-resistance silicon and other terahertz transparent materials, which have the advantages of broadband and achromatic, but due to the The wavelength is long, th...

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Problems solved by technology

[0005] Purpose of the invention: The purpose of the present invention is to provide a terahertz graphene metasurface lens with adjustable focal length and its design method, which not only solves the problems of low numerical aperture and low efficiency in existing solutions, but also increases the focal length with graphene Fermi level. The moving speed of the unit can be regulated by the arrangement order of the units to meet the needs of different imaging systems with greater flexibility

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