High-diffraction-efficiency negative refraction grating plano-concave mirror and design method thereof

Abstract

The invention discloses a high-diffraction-efficiency negative refraction grating plano-concave lens and a design method thereof. The plano-concave lens comprises an incident plane and an emergent plane, the incident plane of the plano-concave lens is a plane, the emergent plane is a concave surface, and the emergent plane is composed of a series of equal-height concentric ring steps with the sameheight and the inner diameter gradually increased from bottom to top. Incident light of the negative refraction grating is radially polarized light, and the plano-concave lens takes a single materialas a medium. According to the design method, sub-wavelength-scale tight focusing, such as radial polarized light and angular polarized light, can be realized on the vector light beam; sub-wavelengthscale tight focusing, such as linearly polarized light, can also be carried out on scalar beams. According to the technical scheme, the equivalent negative refraction effect is utilized, the equal optical path principle is combined, and the method has the advantages that evanescent waves are amplified, the energy utilization rate of diffracted beams is increased, secondary focal spots can be eliminated, and focal field energy distribution of a focusing point is more optimized.

Description

technical field [0001] The invention relates to a high-diffraction-efficiency negative-refraction grating plano-concave mirror and a design method thereof, which can be used in technical fields such as artificial microstructure materials and light field regulation. Background technique [0002] Artificial microstructure is a hotspot in the field of optics. It can achieve some effects that macrostructures do not have, such as particle manipulation, laser fine processing, high-density optical data storage, super-resolution imaging, etc. Therefore, in information storage, biomedicine, Optical imaging and lithography and other fields have broad application prospects. [0003] Using a parabolic mirror focusing system to achieve focusing by reflecting light can obtain a tightly focused spot without spherical aberration under paraxial conditions, but overall energy utilization efficiency is not high; using a high numerical aperture to achieve focusing requires a larger value Apert...

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Problems solved by technology

[0003] Using a parabolic mirror focusing system to achieve focusing by reflecting light can obtain a tightly focused spot without spherical aberration under paraxial conditions, but overall energy utilization efficiency is not high; using a high numerical aperture to achieve focusing requires a larger value Aperture, although tight focusing of the beam can be achieved, with the increase of the numerical aperture, the beam in the middle part of the aperture cannot be well focused at the focal point, which reduces the energy utilization efficiency; the one-dimensional photonic crystal plano-concave mirror can realize Sub-wavelength focusing is effective for any column vector light, but different material properties have different effects on the beam. The improvement of energy utilization needs to be combined with appropriate material selection, and there are certain difficulties in the preparation of the structure.

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