Reflecting-type super diffraction line focusing device based on metal strip-shaped antenna array

Abstract

The invention provides a reflecting-type super diffraction line focusing device based on a metal strip-shaped antenna array. The device sequentially comprises the metal strip-shaped antenna array, a dielectric layer, a metal membrane layer and a substrate layer. Each metal strip-shaped antenna array unit is of a Y-direction array structure formed by arranging metal strip-shaped antennas in the Y direction by taking Ty as a cycle, and the metal strip-shaped antenna array units are arranged in the X direction by taking Tx as a cycle to form the metal strip-shaped antenna array. For the given incident light wavelength gamma, regulation and control over the amplitude and the phase of reflected light in the space plane are achieved by selecting a metal material, a material of the dielectric layer and the thickness of the metal strip-shaped antennas and changing the length L and the width W of metal strips, the length Li and the width Wi of the i metal-shaped antenna of which the center is located at xi are obtained according to amplitude space distribution A(xi) and phase space distribution P(xi), and then a far-field super diffraction line focusing function on the reflected light is achieved. According to device, the diffraction limit can be broken through, the focal spot size smaller than the diffraction limit is achieved, the sidelobe peak ratio is low, and the peak strength is high.

Description

technical field

[0001] The invention belongs to the field of light focusing and light imaging, in particular to a reflective superdiffraction line focusing device. Background technique

[0002] In micro-nano optical devices, superdiffractive focusing lenses usually use sub-wavelength structure arrays to control the amplitude and phase of incident electromagnetic waves. However, it is difficult for transmissive sub-wavelength structures to take into account high amplitude transmittance and large phase control range, resulting in low transmittance of the device. , which greatly limits its application. The reflective sub-wavelength structure can realize a wide range of phase adjustment of the incident light under the premise of ensuring a high transmittance, which can effectively improve the focusing efficiency and focusing performance of the focusing device, such as: increasing the focusing energy and reducing the focusing light field sidelobe, reducing the focal spot size, e...

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