CN205608219U - Electromagnetic wave direct transmission device - Google Patents

Abstract

The utility model discloses an electromagnetic wave direct transmission device, its characterized in that includes: the first metal cycle array at super material structure of hyperbolic and the super material top of hyperbolic and the second metal cycle array of bottom, wherein the super material structure of hyperbolic is ag and the thick stack structure that siO2 NULL constituteed of 25nm by 30nm is thick, first metal cycle array comprises the metal diffraction grating that two -dimensional array distributes, and its cycle is 280nm, second metal cycle array comprises the metal diffraction grating that two -dimensional array distributes, and its cycle is 200nm. Be two -dimensional array raster structure with the one -dimensional grating institutional advancement, formed to the equal effectual direct transmission device of each polarization state, the rethread suitably reduces all issues of the super material of hyperbolic, has improved the transmissivity and the contrast of direct transmission, realized finally that the polarization does not have the mesh that relies on with the reinforcing transmission. The utility model provides a can be to equal effective, the direct transmission device that has higher contrast of various polarization states.

Description

A kind of electromagnetic wave direct transmission device

Technical field

This utility model belongs to sub-wavelength photonics and integrated optics field, surpasses material particularly to one based on hyperbolic Material and the direct transmission device of two-dimensional metallic grating.

Background technology

Direct transmission device is used for communication and information processing in integrated optics system, such as orients insensitive beam splitter, Multiplexing and light network.Its own feature is: under the conditions of opposite direction directional light shines, the light of forward and reverse transfer has higher Contrast.Although direct transmission device cannot be used for realizing the active device of only nonreciprocal function, but they have not Symmetrical transmission and the particular advantages of passive operation.Direct transmission device can by man-made structures such as: unsymmetrical grating, and photon is brilliant Bodies etc., realize the purpose of direct transmission by breaking inversion symmetry.But, owing to this device itself is intrinsic Complexity, still has the biggest room for promotion manufacturing and designing with aspect of performance.

Hyperbolic Meta Materials based on metal-dielectric multi-layer film structure, the yardstick of its construction unit is in degree of depth sub-wavelength, It it is a kind of uniform electromagnetic medium with hyperbolic space frequency response, high anisotropy.This material offers a kind of effective Handle the mode that light is propagated, create many novel phenomenons, such as negative reflection, ultrahigh resolution imaging, strengthen optical state density, slow Light etc., therefore hyperbolic Meta Materials also becomes study hotspot in recent years.

Ting Xu et al. is at entitled " Visible-frequency asymmetric transmission devices Incorporating a hyperbolic metamaterial " article in propose one and be capable of direct transmission merit The planar device of energy, its upper and lower surface is one-dimensional parallel metal diffraction grating, sees nature communication volume 5: 4141, but it is effective to a polarization state.

Therefore, invention one has higher contrast, can seem by direct transmission device all effective to various polarization states Necessary.

Utility model content

The purpose of this utility model is to provide one can direct transmission device all effective to various polarization states.

To achieve these goals, this utility model by the following technical solutions: a kind of electromagnetic wave direct transmission device, its It is characterised by including: hyperbolic metamaterial structure and the first metal periodic array at hyperbolic Meta Materials top and the second gold medal of bottom Belong to periodic array；Wherein said hyperbolic metamaterial structure is the SiO thick by Ag and 25nm thick for 30nm₂Alternately arranged formed Stacked structure；The Metal diffraction grating that described first metal periodic array is distributed by two-dimensional array is constituted, and its cycle is 280nm； The Metal diffraction grating that described second metal periodic array is distributed by two-dimensional array is constituted, and its cycle is 200nm.

The SiO that Ag and 25nm thick for 30nm in described hyperbolic metamaterial structure is thick₂As a periodic unit, described hyperbolic The periodicity of metamaterial structure is 3～5.

Described first metal periodic array and the second metal periodic array grating use crome metal, and the height of grating is 50nm。

One have higher contrast, can direct transmission device all effective to various polarization states, existing to solve Absorbance and the contrast of direct transmission device are low, and the problem being confined to a polarization state TM polarization state.Hyperbolic surpasses material Material is the SiO thick by Ag and 25nm thick for 30nm₂The stacked structure formed as a periodic unit, surpasses by reducing hyperbolic The periodicity of material improves transmitance, and this utility model periodicity is 3, and periodicity reduces can effectively reduce what silver brought Loss, makes light only can pass through when forward entrance and goes, but the thickness of hyperbolic Meta Materials is greater than the attenuation length of light, protects The card the most incident time can not pass through.Being irradiated from bottom by incident illumination and be defined as forward entrance to top, incident illumination shines from top Reverse incidence it is defined as bottom directive.

Incidence end grating and exit end grating are the Metal diffraction grating structures being distributed by the two-dimensional array with some cycles Becoming, its cycle is respectively G_A=200nm (bottom) and G_B=280nm (top), the wavelength of incident illumination is 532nm.By by one-dimensional Grating is adjusted to two-dimensional grating, realizes direct transmission effective to each polarization state, and one-dimensional grating becomes the array of two dimension, Just so that can pass through the diffracted wave of the polarization state of both direction while, it is achieved thereby that polarization no dependence.

The beneficial effects of the utility model are: this device has reached the effect of direct transmission, and have of a relatively high right Than degree and can be effective to various polarization states.Have huge in association areas such as sub-wavelength photonics, integrated optics fields Using value.

Accompanying drawing explanation

Fig. 1 is the structural representation of this utility model electromagnetic wave direct transmission device.

Fig. 2 is the side view of this utility model electromagnetic wave direct transmission device.

Fig. 3 is the top view of this utility model electromagnetic wave direct transmission device.

The dispersion relation figure of hyperbolic Meta Materials when Fig. 4 is incident light wave a length of λ=532nm.

Fig. 5 is field pattern during light forward entrance, and the cycle of hyperbolic Meta Materials is 3.

Fig. 6 is field pattern during light reversely incidence, and the cycle of hyperbolic Meta Materials is 3.

Detailed description of the invention

Below in conjunction with specific embodiments and the drawings, the utility model is described in further detail.

As it is shown in figure 1, a kind of direct transmission device based on hyperbolic Meta Materials and two-dimensional metallic grating, surpass material including hyperbolic Material structure 1, the first metal periodic array 2 at hyperbolic Meta Materials top, the second metal periodic array 3 bottom hyperbolic Meta Materials. Hyperbolic metamaterial structure is the SiO thick by Ag and 25nm thick for 30nm₂The stacked structure formed as a periodic unit.The The Metal diffraction grating that one metal periodic array is distributed by two-dimensional array is constituted, its cycle G_A=200nm；Second metal cycle battle array The Metal diffraction grating that row are distributed by two-dimensional array is constituted, and its cycle is G_B=280nm.Fig. 2 is the side of this utility model structure View.Fig. 3 is the top view of this utility model structure.Fig. 4 is hyperbolic Meta Materials dispersion relation figure.

The effective dielectric constant of hyperbolic Meta Materials is:

${\stackrel{\‾}{\mathrm{\ϵ}}}_{eff}=\left(\begin{array}{ccc}{\mathrm{\ϵ}}_{\⊥}& 0& 0\\ 0& {\mathrm{\ϵ}}_{\⊥}& 0\\ 0& 0& {\mathrm{\ϵ}}_{//}\end{array}\right)$

By Wiener formula calculating the two principal dielectric constants:With Represent respectively in hyperbolic Meta Materials and be perpendicular to the permittivity component in z-axis direction and be parallel to the permittivity component of z-axis, select Dutycycle f of silver is 0.54.On x-z cross section, this hyperbolic Meta Materials dispersion relation is k_x ²/ε_⊥+k_z ²/ε_//=k₀ ², wherein k_x= k_x'+ik_x", represent wave vector in the x-direction, k_x' for the real part of wave vector, k_x" imaginary part of wave vector；k_z=k_z'+k_z", represent in the z-direction Wave vector, k_z' for the real part of wave vector, k_z" imaginary part of wave vector；Vacuum wave vector is k₀=2 π/λ₀, λ₀Correspondence and vacuum medium wavelength.When entering Penetrate when the wavelength of light is 532nm the dispersion relation of hyperbolic Meta Materials as shown in Figure 4.

Light attenuation length formula in the material isFree space (in vacuum) wavelength X₀= 532nm with 633nm distinguishes the most corresponding attenuation length L=42.20nm and 38.56nm, when the periodicity of structure elects 3 as: structure is indulged To a size of (30+25) × 3=165nm, the thickness of construction unit is greater than attenuation length, and light will not be by this device when reverse Part, this utility model periodicity is set to 3.

Fig. 5 is light forward entrance distribution map of the electric field when entering in this device, and Fig. 6 is light electric field when reversely entering in this device Scattergram.

Utilize the technical scheme belonging to this utility model or those skilled in the art in the technical solution of the utility model Inspiration under, design similar technical scheme and reach above-mentioned technique effect each fall within protection domain of the present utility model.

Claims (3)

1. an electromagnetic wave direct transmission device, it is characterised in that including: hyperbolic metamaterial structure and hyperbolic Meta Materials top The first metal periodic array and the second metal periodic array of bottom；Wherein said hyperbolic metamaterial structure is thick by 30nm The SiO that Ag and 25nm is thick₂Alternately arranged formed stacked structure；Described first metal periodic array is distributed by two-dimensional array Metal diffraction grating is constituted, and its cycle is 280nm；The metal diffraction light that described second metal periodic array is distributed by two-dimensional array Grid are constituted, and its cycle is 200nm.

Electromagnetic wave direct transmission device the most according to claim 1, it is characterised in that: in described hyperbolic metamaterial structure The SiO that Ag and 25nm thick for 30nm is thick₂As a periodic unit, the periodicity of described hyperbolic metamaterial structure is 3～5.

Electromagnetic wave direct transmission device the most according to claim 1, it is characterised in that: described first metal periodic array and Second metal periodic array grating uses crome metal, and the height of grating is 50nm.