CN114361805A

CN114361805A - Terahertz metamaterial adjustable directional selector

Info

Publication number: CN114361805A
Application number: CN202210003423.3A
Authority: CN
Inventors: 钟任斌; 徐博力; 张慧敏; 方建辉
Original assignee: University of Electronic Science and Technology of China
Current assignee: University of Electronic Science and Technology of China
Priority date: 2022-01-04
Filing date: 2022-01-04
Publication date: 2022-04-15
Anticipated expiration: 2042-01-04
Also published as: CN114361805B

Abstract

The invention discloses a terahertz metamaterial adjustable directional transmission selector and a polarization controller, belongs to the technical field of asymmetric transmission, and aims to provide an asymmetric transmission device capable of selecting the passing direction of electromagnetic waves and solve the problems that the direction of the existing asymmetric transmission device cannot be adjusted and the device is deadly. The terahertz metamaterial-based polarization control device comprises three layers of germanium, silicon dioxide and germanium from top to bottom, and the terahertz metamaterial-based adjustable orientation selector and the polarization controller realize the functions of unidirectional transmission and polarization control of terahertz electromagnetic waves passing through the selected direction by changing the working state of the device.

Description

Terahertz metamaterial adjustable directional selector

Technical Field

The invention belongs to the technical field of asymmetric transmission, and particularly relates to a terahertz metamaterial adjustable directional transmission selector and a polarization regulator.

Background

Terahertz waves having a frequency of 0.1 to 10THz are widely recognized as a frequency band resource due to their high-speed, large-capacity wireless communication capability. Over the years, terahertz devices are continuously researched and developed, and comprise wave absorbers, filters, sensors and other various terahertz metamaterials. The high-performance terahertz device has important significance for the research and development and application of a terahertz system. The device utilizing the terahertz asymmetric transmission technology is widely applied to the fields of chiral spectra, ultrafast information processing, optical interconnection, communication and the like and is used as an important device such as a photodiode, a circulator, an isolator and the like. Therefore, a device with high performance, adjustability and flexibility for the terahertz asymmetric transmission technology is designed in the terahertz frequency band and has important value.

In recent years, devices of various structures of terahertz asymmetric transmission technologies, including devices of all-metal structures, devices of all-dielectric structures, and the like, have been widely studied. However, the device of the traditional terahertz asymmetric transmission technology is a device for realizing determined unidirectional transmission, and the application of the device has the problem that the direction of the asymmetric transmission device is not adjustable. In the complicated and variable information communication, the tunable asymmetric transmission device is emphasized. The existing modulation asymmetric transmission device comprises a planar chiral metamaterial based on graphene, a dynamic metamaterial based on Dirac semimetal, an asymmetric transmission device based on liquid crystal and the like. The current devices of the terahertz asymmetric transmission technology realize the regulation and control of the asymmetric transmission device, but the regulation and control ideas of the devices aim at the regulation and control of the asymmetric transmission with or without conversion, and the regulation and control are too single. Aiming at the problems, the invention provides a novel terahertz adjustable metamaterial asymmetric transmission device structure, which realizes asymmetric transmission of terahertz frequency bands, regulates and controls the state of the device as required so as to realize asymmetric transmission direction modulation, finally realizes selection of the direction through which electromagnetic waves pass, and provides a flexible design idea for a multifunctional low-complexity electromagnetic control system

Disclosure of Invention

The invention aims to: the utility model provides a novel adjustable asymmetric transmission device structure of terahertz metamaterial realizes terahertz frequency channel asymmetric transmission now, solves current asymmetric transmission device direction and can not adjust, and adjust the problem such as slam. The device can realize the adjustable control of the passing direction of the electromagnetic waves and the polarization conversion of the electromagnetic waves; and realizing adjustable polarization filtering on a plurality of electromagnetic waves.

The technical scheme adopted by the invention is as follows:

the terahertz metamaterial adjustable directional selector comprises three layers of germanium-silicon dioxide-germanium from top to bottom. The germanium layer is a square ring with openings at the centers of four sides, and the upper germanium square ring and the lower germanium square ring are loaded with vanadium dioxide blocks corresponding to two adjacent openings.

Furthermore, the intermediate dielectric layer is made of silicon dioxide.

In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:

the terahertz wave absorber is simple in structure and easy to process and manufacture, and the opening structure design of the terahertz wave absorber further enhances the effect of electromagnetic waves and the structure, so that the aim of improving the asymmetric transmission effect is fulfilled. The vanadium dioxide block is loaded at the center of a pair of adjacent edges of the germanium square frame, and the design concept is based on the temperature regulation and control of the vanadium dioxide. Under different temperature regulation and control, the working state of the device can be switched between two states. The device allows the electromagnetic waves to pass through in different directions in two different states, so that the selective passing action of the device on the electromagnetic waves is realized. When the terahertz metamaterial adjustable directional selector works in one state, y-polarized electromagnetic waves of the terahertz metamaterial adjustable directional selector can only be transmitted from the forward direction and cannot be transmitted from the reverse direction. When the working state of the device is changed into another state, the y-polarized electromagnetic wave can only be transmitted from the reverse direction and can not be transmitted from the forward direction. The same can be achieved for x-polarized waves. In the aspect of polarization of electromagnetic waves, aiming at single electromagnetic wave, the polarization converter can be used as the polarization converter; aiming at a plurality of electromagnetic waves with different polarizations, the working state of the device can be adjusted according to needs, so that polarization filtering of x polarization or y polarization is realized. The electromagnetic wave passing direction and the polarization regulation and control function are selected, and a flexible design idea is provided for a multifunctional electromagnetic control system with low complexity. The asymmetric transmission device effectively solves the problem that the existing asymmetric transmission device has no modulation or single modulation.

Drawings

FIG. 1 is a three-dimensional schematic diagram of a unit structure of a terahertz metamaterial adjustable directional selector;

FIG. 2 is a naming schematic diagram of a unit structure of a terahertz metamaterial adjustable directional selector;

FIG. 3 is a transmission curve of a y-polarized electromagnetic field incident at a time when the terahertz metamaterial adjustable directional selector is in a working state;

FIG. 4 is a transmission curve of an incident y-polarized electromagnetic field when the terahertz metamaterial adjustable directional selector is in a second working state;

FIG. 5 is an asymmetric transmission parameter diagram of a terahertz metamaterial adjustable directional selector;

FIG. 6 is a graph of the field current distribution at the center of the device at the peak frequency of the incident y-polarized electromagnetic field;

FIG. 7 is a forward transmission curve of the working state of the terahertz metamaterial adjustable directional selector in one time

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Furthermore, the material of the medium middle layer is silicon dioxide.

FIG. 1 is a three-dimensional schematic diagram of a unit structure of a terahertz metamaterial adjustable orientation selector. Three layers are arranged in the Z-axis direction, and germanium-silicon dioxide-germanium is arranged from top to bottom. The germanium layer is a square ring with an opening in the center of four sides. The geometric parameters P of the three layers are 120 μm, a 90 μm, h1 c 15 μm, h2 25 μm, e 1.155 μm, and w 30 μm.

FIG. 2 is a naming diagram of a unit structure of the terahertz metamaterial adjustable directional selector, two directions are defined, the negative direction along the Z axis is a positive direction, the positive direction along the Z axis is a negative direction, and four vanadium dioxide blocks are marked with numbers of 1-4. Two states are defined: in the first state, M is 1, the vanadium dioxide with the

numbers

1 and 3 is in a medium low-temperature state, and the vanadium dioxide with the

numbers

2 and 4 is in a metal high-temperature state; and in the second state, M is 2, the vanadium dioxide with the

numbers

1 and 3 is in a metal high-temperature state, and the vanadium dioxide with the

numbers

2 and 4 is in a medium low-temperature state. The two states are switched to realize modulation from forward conduction and reverse non-conduction to reverse conduction and forward non-conduction, so that the electromagnetic wave is flexibly controlled.

Fig. 3 is a transmission curve of a y-polarized electromagnetic field incident at a time when the terahertz metamaterial adjustable directional selector is in a working state, and near 1.944THz, a transmission effect of the y-polarized electromagnetic wave in a reverse direction approaches to 1, and a transmission effect of the y-polarized electromagnetic wave in a forward direction approaches to 0, that is, in a working state of the current device, the y-polarized electromagnetic wave can only be transmitted in a reverse direction, but not in a forward direction.

Fig. 4 is a transmission curve of a y-polarized electromagnetic field incident when the terahertz metamaterial adjustable directional selector is in the second operating state, and near 1.944THz, the forward transmission effect of the y-polarized electromagnetic wave approaches to 1, and the reverse transmission effect of the y-polarized electromagnetic wave approaches to 0, that is, in the operating state of the current device, the y-polarized electromagnetic wave can only be transmitted from the forward direction, but cannot be transmitted from the reverse direction. Comparing fig. 3, it can be seen that, when the two states are switched, the modulation from forward conduction and reverse conduction to reverse conduction and forward conduction is realized, so as to flexibly control the electromagnetic wave.

FIG. 5 is an asymmetric transmission parameter diagram of a terahertz metamaterial adjustable directional selector. It can be seen from the figure that in the second state, the propagation of the input y-polarized electromagnetic wave along the forward direction is much larger than that along the reverse direction, that is, the device allows the electromagnetic wave to transmit in the forward direction but not in the reverse direction, so that the asymmetric transmission of the electromagnetic wave is realized. When the second state is changed into the first state by modulating vanadium dioxide, the propagation of the input y-polarized electromagnetic wave along the reverse direction is far larger than that along the forward direction, namely the device allows the electromagnetic wave to be transmitted from the reverse direction and does not allow the electromagnetic wave to be transmitted in the forward direction. Generally speaking, the electromagnetic wave is conducted in the forward direction and cut off in the reverse direction in the second state, and the electromagnetic wave is conducted in the forward direction and cut off in the first state, so that the selective passing action of the electromagnetic wave is realized.

Fig. 6 is a magnetic field current distribution diagram of the center position of the device at the peak frequency of the incident y-polarized electromagnetic field, and in a state two, at a frequency of 1.944thz, the xy plane field diagram of the center position of the device when the y-polarized electromagnetic wave is incident, the gray scale represents the magnetic field amplitude, and the arrows represent the current vectors. The ring magnetic dipole resonance brings about this peak.

Fig. 7 is a transmission curve of the terahertz metamaterial adjustable directional selector in a forward direction at a working state, and it can be seen from the graph that a terahertz device with a frequency of 1.944 transmits incident electromagnetic waves with x-polarization up to 0.8 and transmits incident waves with y-polarization below 0.1, which is a significant difference, and polarization filtering can be achieved. In the transmission curve, the cross-polarization transmission of the device is large, and the device can be used as a polarization deflector.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

1. The terahertz metamaterial adjustable directional selector is characterized by comprising three layers of germanium (2) -silicon dioxide (1) -germanium (2) from top to bottom, wherein the germanium structure layer (2) comprises a germanium square frame unit loaded with a vanadium dioxide block.

2. The terahertz metamaterial adjustable directional selector is characterized in that the same device has two working states, and different working states allow electromagnetic waves to pass through in different directions, so that different unidirectional transmission is realized. And the polarization state of the electromagnetic wave can be regulated and selected.

3. The terahertz metamaterial adjustable directional selector as claimed in claim 1, wherein the intermediate dielectric layer (1) is made of silicon dioxide, and the germanium structure layer (2) is made of germanium.

4. The terahertz metamaterial adjustable orientation selector as claimed in claim 1, wherein the germanium layer structure is arranged in a square frame, a vanadium dioxide block is embedded in the middle of one pair of adjacent edges, and the other two edges are opened at the middle of the other two edges.

5. The terahertz metamaterial adjustable orientation selector of claim 4, wherein the germanium layer structure is the same as the vanadium dioxide layout top and bottom layers.

6. The terahertz metamaterial adjustable directional selector as claimed in claim 2, wherein the working state is adjusted and controlled in real time through the temperature and property state of vanadium dioxide blocks corresponding to the top layer and the bottom layer in pair, and the working state of the device is changed in real time through the spatial position layout and the state attribute layout of the vanadium dioxide blocks.