CN112363329B

CN112363329B - Dull and stereotyped structure based on transmission characteristic can be regulated and control to phase change material

Info

Publication number: CN112363329B
Application number: CN202011418539.0A
Authority: CN
Inventors: 吴小虎; 刘睿一; 崔峥
Original assignee: Shandong Institute Of Advanced Technology
Current assignee: Shandong Institute Of Advanced Technology
Priority date: 2020-12-07
Filing date: 2020-12-07
Publication date: 2022-11-29
Anticipated expiration: 2040-12-07
Also published as: CN112363329A

Abstract

The invention discloses a flat plate structure capable of regulating and controlling transmission characteristics based on a phase-change material, and belongs to the technical field of photoelectric materials and electromagnetic wave transmission regulation and control. The invention solves the problems of complex structure, narrow regulation and control frequency band and the like of the traditional method for regulating and controlling transmission characteristics. The flat plate structure provided by the invention is formed by GST/SiO ₂ The flat plate structure realizes the regulation and control of transmission spectrum in a broadband range by controlling the state of GST, and when GST is converted between a crystalline state and an amorphous state, the average value of the transmissivity difference in the wavelength range of 5.786-7.164 Mum can reach 0.917. In addition, the invention has the characteristics of simple structure and easy mass production, and can still keep good performance when the incident angle is within 60 degrees, thereby having wider application in practice.

Description

Dull and stereotyped structure based on transmission characteristic can be regulated and control to phase change material

Technical Field

The invention relates to a flat plate structure capable of regulating and controlling transmission characteristics based on a phase-change material, and belongs to the technical field of photoelectric materials and electromagnetic wave transmission regulation and control.

Background

In recent years, the transmission characteristics of the infrared band are widely focused and researched, and the infrared band has a very wide application prospect in the aspects of imaging systems, biosensors, filters, optical switching and the like.

In practice, the structure capable of dynamically adjusting and controlling the transmission characteristics has wider application. In recent years, in designing structures with adjustable transmission characteristics, it is most of the time to adjust the transmission spectrum by changing the size of the structure, such as the thickness or the period of the resonant cell. In which case it is difficult to directly change the transmission spectral characteristics of the structure once it has been processed.

The phase change material is a light wave control material with great potential, and can change phase by adopting a temperature control mode so as to change the optical characteristics of the material. Phase change materials are widely used in the design of tunable optical devices. Ge (germanium) oxide ₂ Sb ₂ Te ₅ (GST) is a typical phase change materialThe material can realize the conversion between the crystalline state (cGST) and the amorphous state (aGST) in a time range of tens of nanoseconds. Any crystalline state between crystalline and amorphous states can be stabilized if the energy and duration of the energy imparted is precisely controlled. Because of their fast switching speed between states, good thermal stability, and significant difference in complex refractive index, GST has a great deal of brilliance in the design of tunable optical devices (e.g., absorbers, variable focus lenses, polarization converters). At present, optical devices for regulating and controlling transmission by utilizing phase-change materials are proposed in succession, but the problems that the structure is complex and the processing is not easy to carry out exist, and the regulation and control transmission characteristics are mostly concentrated in narrow bands, so that the effective regulation and control under a single wavelength can be realized only. Therefore, it is necessary to provide a structure which is simple in structure and effectively regulates and controls the transmission characteristics in a wide band range.

Disclosure of Invention

The invention provides a flat plate structure capable of regulating and controlling transmission characteristics based on a phase-change material, aiming at solving the problems of complex structure, narrow regulation and control frequency band and the like of the conventional structure for regulating and controlling the transmission characteristics.

The utility model provides a dull and stereotyped structure based on transmission characteristic can be regulated and control to phase change material, this dull and stereotyped structure is piled up by the three-layer flat board and forms, is top layer, intermediate level and bottom from top to bottom in proper order, top layer and bottom be the same phase change material GST of size, the intermediate level is SiO ₂ A material.

Further, the thickness of the phase change material GST of the top layer and the bottom layer is 0.65 μm to 0.8 μm.

Further, the thickness of the phase change material GST of the top layer and the bottom layer is 0.764 μm.

Further, the phase change materials GST of the top and bottom layers have refractive indexes varying with wavelength, and the refractive indexes thereof are as shown in fig. 2.

Further, the intermediate layer and the top layer are of different thickness.

Further, the intermediate layer has a thickness of 0.8 μm to 1.2. Mu.m.

Further, the thickness of the intermediate layer was 1 μm.

Further, the refractive index of the intermediate layer was 1.45.

Further, the top layer, the middle layer and the bottom layer are stacked without gaps.

The invention has the following beneficial effects: the flat plate structure with adjustable transmission characteristics provided by the invention realizes the adjustment and control of broadband transmission spectrum, can still keep good performance when being incident at a large angle, has good tolerance to the incident angle, and makes up the defect of complicated design structure in the prior art. The transmission spectrum regulation in a broadband range is realized by controlling the state of GST, when GST is switched between crystalline state and amorphous state, the average value of the transmittance difference in the wavelength range of 5.786-7.164 mu m can reach 0.917, and good performance can be still maintained when the incident angle is within 60 degrees.

Drawings

FIG. 1 is a schematic diagram of a plate structure based on phase change materials with controllable transmission characteristics;

FIG. 2 is a graph of the refractive indices of the top and bottom layer phase change materials GST;

FIG. 3 is a transmitted light spectrum of the flat panel structure of example 1 at normal incidence of TM waves;

FIG. 4 is a magnetic field plot in the x-z plane of the slab structure of example 1 at an incident wavelength of 6 μm with the GST being amorphous aGST;

FIG. 5 is a magnetic field plot in the x-z plane of the plate structure of example 1 at an incident wavelength of 6 μm with GST being crystalline cGST;

FIG. 6 is a transmission spectrum of the plate structure of example 1 when the GST is amorphous aGST, and TM waves are incident at different incident angles;

FIG. 7 is a transmitted light spectrum of the plate structure of example 1 when GST is crystalline cGST, and TM waves are incident at different incident angles;

in the figure, 1-the top layer, 2-the middle layer, 3-the bottom layer.

Detailed Description

The experimental procedures used in the following examples are conventional unless otherwise specified. The materials, reagents, methods and apparatus used, unless otherwise specified, are conventional in the art and are commercially available to those skilled in the art.

Example 1:

as shown in fig. 1, the plate structure with adjustable transmission characteristics based on phase change material in the present embodiment is formed by stacking three layers of plates, wherein the top layer 1 is phase change material GST, and the thickness t is ₁ 0.764 μm; the intermediate layer 2 is silicon dioxide, has a refractive index of 1.45 and a thickness t ₂ Is 1 μm; the bottom layer 3 is phase change material GST with thickness t ₃ It was 0.764. Mu.m. The refractive indices of the phase change materials GST of the top layer 1 and the bottom layer 3 are shown in fig. 2. As can be seen from FIG. 2, there is a large difference between real parts of aGST and cGST refractive indices in the infrared band, and this difference remains stable at 5-8 μm. Since the imaginary part of the aGST index is 0, there is no absorption.

The performance of the flat plate structure based on the adjustable transmission characteristic of the phase-change material is characterized through software simulation:

numerical simulation is carried out by adopting a finite difference time domain method (FDTD), periodic boundary conditions are adopted in the x direction and the y direction during simulation, a Perfect Matching Layer (PML) is adopted in the z direction, plane waves with the wavelength range of 5-8 mu m are used for incidence along the z axis, the mode of a light source is arranged to be bloch/period under the normal incidence condition, and a monitor is placed above a simulation area below the structure and used for monitoring the transmittance.

Simulations were performed according to the above settings, resulting in transmission spectrograms in both aGST and cGST states, as shown in FIG. 3. As can be seen from FIG. 3, two distinct transmission peaks were observed in the aGST state, with a transmission of up to 0.99 at wavelengths of 6 μm and 6.866 μm, respectively, and with a continuous high transmission (T)>80%) was 1.378 μm. And in the cGST state, the average transmittance of 5-8 μm in the entire simulation band is 0.016. In order to quantitatively describe the regulation and control of transmission characteristics, we define the transmission difference value in two states as delta T = | T _cGST -T _aGST L. When the wavelengths are 6 μm and 6.866 μm, the difference in transmittance in the two states of GST can reach 0.99. And the average value of the transmissivity difference in the wavelength range of 5.786-7.164 mu m can reach 0.917. Therefore, the flat plate structure provided in example 1 can realize the adjustment and control of the transmission characteristics in a broadband range.

The magnetic field distribution in the x-y plane at a wavelength of 6 μm was calculated, and the result is shown in FIG. 4. As can be seen from fig. 4, for gst, the magnetic field is enhanced at the top and bottom layers due to FP resonance generated at the gst of the top and bottom layers, whereas for cGST, light is localized at the top cGST plate, and thus the transmission is almost 0.

The transmission spectrum of the TM wave at different angles of incidence (0 °, 20 °, 40 ° and 60 °) is shown in fig. 5. As can be seen from the figure, in gst, the wavelength band of high transmittance is blue-shifted with increasing incidence angle, but the transmittance is not decreased. For cGST, the transmittance curve of the 5-7 μm band almost coincides with that at normal incidence as the angle of incidence increases, and the transmittance is still less than 0.2 when the angle of incidence is less than 60 °, although there is a slight increase in transmittance at long wavelengths. Therefore, the flat plate structure provided by the invention can still maintain good performance under the condition of large-angle incidence.

Claims

1. The utility model provides a dull and stereotyped structure based on transmission characteristic can be regulated and control to phase change material, its characterized in that, this dull and stereotyped structure is piled up by the three-layer flat board and forms, is top layer, intermediate level and bottom from top to bottom in proper order, top layer and bottom be the same phase change material GST of size, the intermediate level is SiO ₂ A material;

the thickness of the phase change material GST of the top layer and the bottom layer is 0.65-0.8 μm;

the thicknesses of the middle layer and the top layer are different;

the thickness of the intermediate layer is 0.8-1.2 μm.

2. The plate structure of claim 1, wherein the thickness of the phase change material GST in the top and bottom layers is 0.764 μm.

3. The phase change material-based tunable transmission characteristic plate structure of claim 1, wherein the thickness of the intermediate layer is 1 μm.

4. The slab structure with tunable transmission characteristics based on a phase-change material as claimed in claim 1, wherein the refractive index of the intermediate layer is 1.45.

5. The phase change material based tunable transmission characteristic plate structure of claim 1, wherein the top layer, the middle layer and the bottom layer are stacked without a gap.