Design method of focal length controllable negative-refraction grating plano-concave lens

Abstract

The invention discloses a design method of a focal length controllable negative-refraction grating plano-concave lens. The negative-refraction grating plano-concave lens is a plano-concave lens in cylindrical symmetry, an incident surface includes a circular plane, an emitting surface includes a concave surface, the central portion of the concave surface includes a small circular plane, the concave surface including one small circular plane and multiple cylindrical surfaces and annulus surfaces with height equivalent progressive increase from inside to outside is formed, and the radius of thesmall circular plane and the sizes of the annulus surfaces are determined by that S1) the light wavelength lambda0 of the negative-refraction grating plano-concave lens is determined, a proper mediumrefractive index n is selected, the height of the cylindrical surfaces is adjusted, and thus, a negative refraction grating realizes negative refraction in the working wavelength; and S2) on the premise that incident light is input vertically, an equivalent negative refraction index neff is obtained according to the working wavelength, material refractive index and the cylindrical surface height determined in the step S1). Via the method, a preset focal length can be regulated flexibly, incident light and emitting light are focused in the same side of the normal, and energy of electromagneticwaves is more concentrated.

Description

technical field [0001] The invention relates to a design method of a negative refraction grating plano-concave mirror with controllable focal length, belongs to the field of artificial microstructure materials and fine light field regulation, and can be used in the technical fields of light field focusing, particle acceleration, optical micro-control and the like. 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 acceleration, single-molecule imaging, small size effect and quantum tunneling effect. Photolithography and other fields have broad application prospects. [0003] The traditional parabolic mirror makes the beam converge in the same direction by changing the phase of the wavefront, but its reflection focusing method has certain shortcomings. There is mutual influence, which limits the use range and focusing effect of the focal field. In addition...

AI Technical Summary

Problems solved by technology

[0003] The traditional parabolic mirror makes the beam converge in the same direction by changing the phase of the wavefront, but its reflection focusing method has certain shortcomings. There is mutual influence, which limits the use range and focusing effect of the focal field. In addition, traditional lenses can only achieve ideal focusing under paraxial conditions, and there are certain requirements for the polarization state of light

One-dimensional photonic crystal plano-concave mirrors can achieve sub-wavelength focusing and are effective for any cylindrical vector light, but there are certain difficulties in the selection of materials and the preparation of structures

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