Switchable TE polarization non-reciprocal heat radiator based on magneto-optical material and VO2

Abstract

The invention discloses a switchable TE polarization non-reciprocal heat radiator based on magneto-optical materials and VO2. The heat radiator comprises a substrate, a metal layer, a magneto-optical material film, a VO2 film and a Si cylinder array. The device has the advantages of being flexible and convenient to use, high in nonreciprocity, capable of generating nonreciprocal heat radiation of TE polarization, switchable in nonreciprocity and the like, is a very ideal switchable TE polarization nonreciprocal heat radiation device, can be produced on a large scale at low cost by utilizing a nano photoetching process, is stable and reliable in performance after being manufactured, and is suitable for large-scale production. The method has an important application prospect.

Description

Technical Field

[0001] The invention relates to a switchable TE polarization non-reciprocal thermal radiator based on magneto-optical material and VO2. Background Art

[0002] According to Kirchhoff's law of thermal radiation, the spectral emissivity of an object is equal to the spectral absorptivity. This phenomenon is caused by Lorentz reciprocity, which provides a method to measure the spectral emissivity of an object. Recently, studies have found that Kirchhoff's law of thermal radiation is only valid for reciprocal material devices and invalid for non-reciprocal material devices. Non-reciprocal material devices will produce non-reciprocal thermal radiation phenomena (spectral emissivity is not equal to spectral absorptivity). Non-reciprocal thermal radiation has a wide range of applications in many fields, such as thermophotoelectrics, thermal imaging, radiation cooling and thermal management. In practice, how to flexibly apply non-reciprocal thermal radiation has always been a research hotspot. At present, researchers have invested a lot of energy in studying non-reciprocal thermal radiation devices. However, most of these works can only produce TM polarized non-reciprocal thermal radiation phenomena. There are also some works that can produce TE polarized non-reciprocal thermal radiation phenomena, but their azimuth angle is not 0. It is of great significance to achieve TE polarized non-reciprocal thermal radiation with an azimuth angle of 0. In addition, the switching control of TE polarized non-reciprocal thermal radiation has not yet been realized. This requires finding a new non-reciprocal thermal radiation device structure to achieve these goals. Summary of the invention

[0003] In order to overcome the shortcomings of the prior art, the present invention provides a switchable TE polarization non-reciprocal thermal radiator based on magneto-optical material and VO2, the purpose of which is to enable the thermal radiator to generate switchable TE polarization non-reciprocity.

[0004] Based on the above purpose, the present invention provides a switchable TE polarization non-reciprocal thermal radiator based on magneto-optical material and VO2. The thermal radiator comprises a substrate, a metal layer, a magneto-optical material film, a VO2 film and a Si cylinder array from bottom to top; The substrate material may be silicon, silicon dioxide or other suitable base materials.

[0005] The metal layer can be made of gold, silver, aluminum or other metal materials with corresponding properties.

[0006] The magneto-optical material film is made of InAs.

[0007] The thickness of the metal layer is 0.1 micron, the thickness of the magneto-optical material film is 0.79 micron, the thickness of the VO2 film is 0.07 micron, the height of the Si cylinder array is 2.52 micron, and the diameter is 2.55 micron.

[0008] The Si cylindrical array is distributed periodically in the X and Y directions, with a period of 3.98 microns.

[0009] Beneficial effects of the present invention: (1) When VO2 is in an insulating state, the external magnetic field is 1.5T, and the light is incident at an angle of 10°, the thermal radiator of the present invention will generate TE polarized non-reciprocal thermal radiation at a wavelength of 9.481 microns, and the generated non-reciprocal peak is 0.45. When the diameter of the Si cylinder changes, the position of the non-reciprocal spectrum changes, which is tunable; when other structural parameters change, the peak of the spectrum can still remain stable, that is, it has stability. When VO2 is in a metallic state, the thermal radiator of the present invention generates broadband thermal radiation in the wavelength range of 9-10 microns.

[0010] (2) The present invention has the advantages of flexible and convenient use, high non-reciprocity, ability to generate TE polarized non-reciprocal thermal radiation, and switchable non-reciprocity. It is an ideal narrow-bandwidth incident angle non-reciprocal thermal radiation device. It can be produced in large quantities at low cost using nano-lithography technology. The performance of the manufactured thermal radiation device is stable and reliable, and it has important application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1a It is a three-dimensional schematic diagram of a switchable TE polarization non-reciprocal thermal radiator based on magneto-optical materials and VO2.

[0012] Figure 1b Top view of a switchable TE polarization nonreciprocal thermal radiator based on magneto-optical materials and VO2.

[0013] Figure 2 It is a curve diagram of the device absorptivity, emissivity and non-reciprocity when VO2 is in an insulating state, an external magnetic field of 1.5T is applied, and TE polarized light is incident at an angle of 10° in an embodiment of the present invention.

[0014] Figure 3 It is a curve diagram of the device absorptivity, emissivity and non-reciprocity when VO2 is in a metallic state, an external magnetic field of 1.5 T is applied, and TE polarized light is incident at an angle of 10° in an embodiment of the present invention.

[0015] The markings in the figure are: h1: Si cylinder array height; h2: VO2 film thickness; h3: magneto-optical material film thickness; h4: metal layer height; P: period of structure; D: diameter of Si cylinder.

[0016] In the figure, there are Si cylinder array 1, VO2 film 2, magneto-optical material film 3, metal layer 4, and substrate 5. DETAILED DESCRIPTION

[0017] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0018] like Figure 1a , Figure 1b As shown, the present invention relates to a switchable TE non-reciprocal thermal radiator based on magneto-optical material and VO2, which is composed of a Si cylinder array 1, a VO2 film 2, a magneto-optical material film 3, a metal layer 4, and a substrate 5 from top to bottom.

[0019] In order to realize the TE non-reciprocity of the thermal radiator, the Si cylinder array 1 is placed on the magneto-optical material film 3.

[0020] In order to realize the switchability of the TE non-reciprocity, the VO2 film 2 is placed on the magneto-optical material film 3.

[0021] Figure 1a In the example, TE polarized light is incident on the device at an angle of θ, and the vibration direction of the electric field vector corresponding to TE polarized light is perpendicular to the incident plane, that is, the y-axis. Figure 1a Under the geometric structure shown, the present invention uses the finite element analysis method to calculate the absorption and radiation efficiency of the switchable TE polarization non-reciprocal thermal radiator in the infrared band. The structural parameters of the switchable TE polarization non-reciprocal thermal radiator are obtained through optimization.

[0022] Figure 1b is a top view of the structure, in which the period and diameter of the Si cylinder array are indicated.

[0023] An embodiment of the present invention is given below. In this case, the bottom substrate material is SiO2, with a refractive index of 1.45, the metal layer material is Al, and its refractive index is referenced in [AD Rakić, Appl. OpT. 34 (1995) 4755–4767], and the magneto-optical film material is InAs. When the external magnetic field B is along the y-axis direction, its dielectric constant tensor in the infrared region can be expressed as:

[0024] in:

[0025]

[0026]

[0027] High frequency dielectric constant =12.37, plasma frequency ω p = ( n ee 2 / m*ε 0) -1 / 2 , cyclotron frequency ω c = eB / m* , InAs doping concentration of magneto-optical material n e is 3 × 10 18 cm -3 , relaxation rate γ =4.5 × 10 12 rad·s -1 , e is the electron charge, ε 0 is the dielectric constant of vacuum, and the effective electron mass m* = 0.033 m e , m e The mass of the electron.

[0028] The thickness of the metal layer is 0.1 micron, the thickness of the InAs film is 0.79 micron, the thickness of the VO2 film is 0.07 micron, and the thickness of the Si cylinder array is 2.52 micron and the diameter is 2.55 micron.

[0029] Figure 2 is an embodiment of the present invention, at a wavelength of 9-10 microns, VO2 is in an insulating state, an external magnetic field of 1.5T, and TE polarized light is incident at an angle of 10°, the absorption, emission and non-reciprocity of the device vary with wavelength, as shown by Figure 2 It can be seen that when the external magnetic field is 1.5 T, the absorption and emission spectra no longer overlap with each other, indicating a violation of the traditional Kirchhoff's law.

[0030] Figure 3 Shown Figure 2 The absorption, emission and non-reciprocity of VO2 after it is transformed into a metallic state are plotted as a function of wavelength. Figure 3 It can be seen that when VO2 is in a metallic state, its non-reciprocity disappears.

[0031] When making the switchable TE polarization non-reciprocal thermal radiator based on magneto-optical material and VO2 for use in the infrared band of the present invention, by appropriately selecting the height and radius of the Si cylinder array, and the thickness of the magneto-optical material film and the VO2 film, a switchable TE non-reciprocal thermal radiator with strong non-reciprocity can be obtained.

[0032] The switchable TE polarization non-reciprocal thermal radiator based on magneto-optical material and VO2 of the present invention has the advantages of flexible and convenient use, high non-reciprocity, ability to generate TE polarization non-reciprocal thermal radiation, switchable non-reciprocity, etc. It is a thermal radiation device with great application value. It can be produced in large quantities and at low cost using nanolithography technology. The manufactured thermal radiator has stable and reliable performance and has important application prospects.

[0033] The technical features of the above-described embodiments can be further combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0034] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, all of which belong to the protection scope of the present invention. The protection scope of the present invention is given by the attached claims and any equivalent technical solutions thereof.

Claims

1. A switchable TE polarization non-reciprocal thermal radiator based on magneto-optical material and VO2, characterized by: The heat radiator comprises a substrate, a metal layer, a magneto-optical material film, a VO2 film and a Si column array in sequence from bottom to top.

2. The switchable TE polarization non-reciprocal thermal radiator based on magneto-optical material and VO2 according to claim 1 is characterized in that: Optional materials for the substrate include silicon and silicon dioxide.

3. The switchable TE polarization non-reciprocal thermal radiator based on magneto-optical material and VO2 according to claim 1 is characterized in that: Optional materials for the metal layer include gold, silver and aluminum.

4. The switchable TE polarization non-reciprocal thermal radiator based on magneto-optical material and VO2 according to claim 1 is characterized in that: The magneto-optical material film is made of InAs.

5. The switchable TE polarization non-reciprocal thermal radiator based on magneto-optical material and VO2 according to claim 1 is characterized in that: The thickness of the metal layer is 0.1 micron, the thickness of the magneto-optical material film is 0.79 micron, the thickness of the VO2 film is 0.07 micron, the height of the Si cylinder array is 2.52 micron, and the diameter is 2.55 micron.

6. The switchable TE polarization non-reciprocal thermal radiator based on magneto-optical material and VO2 according to claim 1 is characterized by: The Si cylindrical array is distributed periodically in the X and Y directions, with a period of 3.98 microns.

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