Electrically controlled polarization modulator based on NbSe2-metal multilayer structure

Abstract

The present invention discloses an electrically controlled polarization modulator based on a NbSe2-metal multilayer structure. It includes a substrate, a NbSe2 thin film layer arranged on the substrate, a first electrode pair arranged on the upper end surface of the NbSe2 thin film layer, and a second electrode pair arranged on the lower end surface of the substrate; the NbSe2 thin film layer is composed of a plurality of NbSe2 thin film layers stacked; the first electrode pair is composed of a first electrode and a second electrode, and the first electrode and the second electrode are combined to form a metal ring electrode; the second electrode pair is composed of a third electrode and a fourth electrode, and the third electrode and the fourth electrode are combined to form a metal ring electrode; a voltage is applied to the first electrode pair and the second electrode pair to electrically control and actively modulate electromagnetic waves. The above-mentioned electrically controlled polarization modulator is prepared based on the NbSe2 thin film layer to obtain an electrically controlled polarization modulator, which can realize dynamic modulation of the polarization state of electromagnetic waves from the visible light band to the millimeter wave band. Applying an external electric field through the metal ring electrode can increase the modulation depth, make the modulation depth uniform, and improve the bandwidth for modulating electromagnetic waves.

Description

Technical Field

[0001] The present invention relates to the technical field of modulation elements, and in particular to an electrically controlled polarization modulator based on a NbSe2-metal multilayer structure. Background Art

[0002] Two-dimensional layered materials have very excellent optical properties. A special two-dimensional material molecular composition, based on the structure of the main atomic chain as the main axis, has obvious anisotropic properties. In addition, based on the piezoelectric effect of the material, when an additional bias voltage is applied along the main atomic chain direction, the main atomic chain can be stretched, thereby realizing active control of the material structure. Therefore, the polarization selection and modulation of the electromagnetic wave incident on the material can be realized through an external electric field. Based on this characteristic, the two-dimensional layered material polarization modulator has received extensive attention and in-depth research from researchers. Because most polarization modulators currently have a limited modulation range and a very narrow modulation bandwidth. For electromagnetic waves with shorter wavelengths, the commonly used modulation device crystals are expensive and the modulation depth is uncontrollable. Moreover, for long-wavelength electromagnetic waves, since the existing metal grid modulation device has a fixed line spacing size, the modulation depth of the polarization device is relatively small for broadband electromagnetic waves. Therefore, there is a problem of narrow modulation bandwidth when the modulation element modulates the electromagnetic wave in the prior art method. Summary of the invention

[0003] The embodiment of the present invention provides an electrically controlled polarization modulator based on a NbSe2-metal multilayer structure, aiming to solve the problem of narrow modulation bandwidth when a modulation element modulates electromagnetic waves in the prior art method.

[0004] In the first aspect, an embodiment of the present invention provides an electrically controlled polarization modulator based on a NbSe2-metal multilayer structure, which includes a substrate, a NbSe2 thin film layer arranged on the substrate, a first electrode pair arranged on the upper end surface of the NbSe2 thin film layer, and a second electrode pair arranged on the lower end surface of the substrate; the NbSe2 thin film layer is composed of a plurality of NbSe2 thin film layers stacked together; the first electrode pair is composed of a first electrode and a second electrode, and the positions where the first electrode and the second electrode are opposite to each other and the positions where the second electrode and the first electrode are opposite to each other are both recessed inward to form a metal ring electrode; the second electrode pair is composed of a third electrode and a fourth electrode, and the positions where the third electrode and the fourth electrode are opposite to each other and the positions where the fourth electrode and the third electrode are opposite to each other are both recessed inward to form a metal ring electrode; a voltage is applied to the first electrode pair and the second electrode pair for electrical control to actively modulate electromagnetic waves.

[0005] The electrically controlled polarization modulator based on the NbSe2-metal multilayer structure, wherein the number of thin film layers included in the NbSe2 thin film layer is 5-9.

[0006] The electrically controlled polarization modulator based on the NbSe2-metal multilayer structure, wherein the thickness of the NbSe2 thin film layer is 12-50nm.

[0007] The electrically controlled polarization modulator based on the NbSe2-metal multilayer structure is prepared by liquid phase stripping, mechanical stripping or chemical vapor deposition.

[0008] In the electrically controlled polarization modulator based on the NbSe2-metal multilayer structure, the thickness of the first electrode pair and the second electrode pair are both 120-400 μm.

[0009] The electrically controlled polarization modulator based on the NbSe2-metal multilayer structure, wherein the first electrode, the second electrode, the third electrode and the fourth electrode all include a semicircular structure recessed inward, and the diameter of the semicircular structure is 1.2-4 mm.

[0010] In the electrically controlled polarization modulator based on the NbSe2-metal multilayer structure, the first electrode pair and the second electrode pair are both prepared by magnetron sputtering technology or vacuum evaporation technology.

[0011] The electrically controlled polarization modulator based on the NbSe2-metal multilayer structure, wherein the substrate is an indium tin oxide substrate, and the thickness of the indium tin oxide substrate is 12-50 nm.

[0012] The electrically controlled polarization modulator based on the NbSe2-metal multilayer structure, wherein the substrate is a semiconductor element substrate, and the thickness of the semiconductor element substrate is 30-80 μm.

[0013] In the electrically controlled polarization modulator based on the NbSe2-metal multilayer structure, the semiconductor element substrate is a silicon substrate or a germanium substrate.

[0014] The embodiment of the present invention provides an electrically controlled polarization modulator based on a NbSe2-metal multilayer structure. It includes a substrate, a NbSe2 thin film layer arranged on the substrate, a first electrode pair arranged on the upper end surface of the NbSe2 thin film layer, and a second electrode pair arranged on the lower end surface of the substrate; the NbSe2 thin film layer is composed of a plurality of NbSe2 thin film layers stacked; the first electrode pair is composed of a first electrode and a second electrode, and the first electrode and the second electrode are combined to form a metal ring electrode; the second electrode pair is composed of a third electrode and a fourth electrode, and the third electrode and the fourth electrode are combined to form a metal ring electrode; voltage is applied to the first electrode pair and the second electrode pair for electrical control to actively modulate electromagnetic waves. The above-mentioned electrically controlled polarization modulator is prepared based on the NbSe2 thin film layer to obtain an electrically controlled polarization modulator, which can realize dynamic modulation of the polarization state of electromagnetic waves from the visible light band to the millimeter wave band. Applying an external electric field through the metal ring electrode can increase the modulation depth and make the modulation depth uniform, which greatly improves the bandwidth for modulating electromagnetic waves. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0016] Figure 1 The overall structure diagram of the electrically controlled polarization modulator based on the NbSe2-metal multilayer structure provided by the embodiment of the present invention;

[0017] Figure 2 A cross-sectional structural diagram of an electrically controlled polarization modulator based on a NbSe2-metal multilayer structure provided in an embodiment of the present invention;

[0018] Figure 3 A planar structural diagram of an electrically controlled polarization modulator based on a NbSe2-metal multilayer structure provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0021] It should also be understood that the terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0022] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0023] See also Figures 1 to 3 , Figure 1 The overall structure diagram of the electrically controlled polarization modulator based on the NbSe2-metal multilayer structure provided by the embodiment of the present invention; Figure 2 A cross-sectional structural diagram of an electrically controlled polarization modulator based on a NbSe2-metal multilayer structure provided in an embodiment of the present invention; Figure 3 A planar structural diagram of an electrically controlled polarization modulator based on a NbSe2-metal multilayer structure provided in an embodiment of the present invention. The electrically controlled polarization modulator based on a NbSe2-metal multilayer structure comprises: a substrate 1, a NbSe2 thin film layer 2 arranged on the substrate 1, a first electrode pair 3 arranged on the upper end surface of the NbSe2 thin film layer 2, and a second electrode pair 4 arranged on the lower end surface of the substrate 1; the NbSe2 thin film layer 2 is composed of a plurality of NbSe2 thin film layers stacked; the first electrode pair 3 is composed of a first electrode 31 and a second electrode 32, and the first electrode 31 and the second electrode 32 are opposite to each other at positions that are concave inward to form a metal ring electrode; the second electrode pair 4 is composed of a third electrode 41 and a fourth electrode 42, and the third electrode 41 and the fourth electrode 42 are opposite to each other at positions that are concave inward to form a metal ring electrode; a voltage is applied to the first electrode pair 3 and the second electrode pair 4 for electrical control to actively modulate electromagnetic waves.

[0024] The NbSe2 thin film layer 2 is made of NbSe2 material. As a transition metal element compound, NbSe2 is a two-dimensional layered material with a 1T' phase structure. It has strong anisotropy and a near-zero bandgap, which can achieve broadband modulation. It has high carrier mobility and can perform voltage regulation from millimeter waves to visible light. By combining the NbSe2 thin film layer 2 with the substrate 1, a NbSe2-metal multilayer structure can be formed. This NbSe2-metal multilayer structure can achieve frequency, amplitude and phase modulation of electromagnetic waves with wavelengths ranging from millimeter waves to visible light.

[0025] In a more specific embodiment, the number of thin film layers included in the NbSe2 thin film layer 2 is 5-9. The thickness H2 of the NbSe2 thin film layer 2 is 12-50 nm. Specifically, the NbSe2 thin film layer 2 is prepared by liquid phase stripping, mechanical stripping or chemical vapor deposition.

[0026] To solve the problems existing in the existing modulation elements, the embodiment of the present invention adds a group of metal ring electrodes on the upper and lower sides of the NbSe2-metal multilayer structure formed by the combination of the NbSe2 thin film layer 2 and the substrate 1, that is, the first electrode pair 3 and the second electrode pair 4 are each used as a group of metal ring electrodes. By adding the metal ring electrodes, the electromagnetic waves in the range of millimeter waves to visible light wavelengths can be actively controlled by an external electric field, that is, a polarization modulator with a broadband modulation function is obtained. The electrically controlled polarization modulator has a simple structure and a large modulation depth. The NbSe2 thin film layer 2 is prepared by liquid phase stripping, mechanical stripping or chemical vapor deposition, and then the direction of its main atomic chain is marked by a transmission electron microscope. Finally, the metal ring electrode is prepared in the direction of the main atomic chain by magnetron sputtering or vacuum evaporation to realize the processing of the device. The thickness H2 of the NbSe2 thin film layer is usually set to 12-50nm. In the optimal embodiment, the thickness H2 can be set to 30nm. At this thickness, the electrically controlled polarization modulator can achieve the optimal modulation effect; the NbSe2 thin film layer is composed of a multi-layer thin film stack, and the number of layers is 5-9.

[0027] In a more specific embodiment, the thickness H1 of the first electrode pair 3 and the second electrode pair 4 is 120-400 μm. Specifically, the first electrode 31, the second electrode 32, the third electrode 41 and the fourth electrode 42 all include a semicircular structure that is recessed inward, and the diameter D of the semicircular structure is 1.2-4 mm. The first electrode pair 3 and the second electrode pair 4 are both prepared by magnetron sputtering technology or vacuum evaporation technology.

[0028] Specifically, the first electrode pair 3 and the second electrode pair 4 can be made of metal materials such as gold, silver, copper, iron, aluminum or platinum. The thickness H1 of the metal ring electrode can usually be set to 120-400μm. In the optimal embodiment, the thickness H1 of the metal ring electrode can be set to 200μm. At this thickness, the electrically controlled polarization modulator can achieve the optimal modulation effect. The diameter D of the semicircular structure of the first electrode 31 that is recessed inward can be set to 1.2-4mm. Similarly, the diameter D of the semicircular structure in the second electrode 32, the third electrode 41 and the fourth electrode 42 can also be set to 1.2-4mm. In the optimal embodiment, the diameter D of the semicircular structure can be set to 2mm, and the electrically controlled polarization modulator can achieve the optimal modulation effect. By applying an external electric field to the first electrode pair 3 and the second electrode pair 4 to adjust the voltage, active modulation of electromagnetic waves from millimeter waves to visible light can be achieved.

[0029] In a more specific embodiment, the substrate 1 is an indium tin oxide substrate, and the thickness H3 of the indium tin oxide substrate is 12-50 nm; or, the substrate 1 is a semiconductor element substrate, and the thickness H3 of the semiconductor element substrate is 30-80 μm. The semiconductor element substrate is a silicon substrate or a germanium substrate.

[0030] Specifically, the substrate 1 is rectangular, such as with a size of 2cm×2cm. The substrate 1 can be made of indium tin oxide (ITO). When the indium tin oxide substrate is made of indium tin oxide, its thickness H3 can be configured to be 12-50nm. The electrically controlled polarization modulator made based on the indium tin oxide substrate can modulate electromagnetic waves with wavelengths ranging from visible light to infrared light. In the optimal embodiment, the thickness H3 of the indium tin oxide substrate can be configured to be 25nm. The indium tin oxide substrate of this thickness has the best modulation effect on electromagnetic waves with wavelengths ranging from visible light to infrared light. The substrate 1 can also be made of semiconductor elements such as silicon (Si) or germanium (Ge). When a silicon substrate or a germanium substrate is made of silicon or germanium, its thickness H3 can be configured to be 30-80μm. The electrically controlled polarization modulator made based on the silicon substrate or the germanium substrate has excellent transparency and can modulate electromagnetic waves with wavelengths ranging from millimeter waves to visible light. In the optimal embodiment, the thickness H3 of the silicon substrate or the germanium substrate can be configured to be 50μm. The silicon substrate or the germanium substrate of this thickness has the best modulation effect on electromagnetic waves with wavelengths ranging from millimeter waves to visible light.

[0031] Embodiment 1:

[0032] The first electrode 31 is used as the positive electrode and the second electrode 32 is used as the negative electrode, and an external voltage is applied. The polarization degree of the modulated electromagnetic wave increases, and the modulation depth increases slightly, thereby generating elliptically polarized light.

[0033] Embodiment 2:

[0034] The first electrode 31 is used as the positive electrode, the third electrode 41 is used as the negative electrode, and an external voltage is applied, so that the polarization degree of the modulated electromagnetic wave increases, the modulation depth increases, and linearly polarized light is generated.

[0035] Embodiment 3:

[0036] The first electrode 31 is used as the positive electrode, the second electrode 32 is used as the negative electrode, the third electrode 41 is used as the positive electrode, and the fourth electrode 42 is used as the negative electrode, and an external voltage is applied. The increase in the polarization degree of the modulated electromagnetic wave is greater than that of Example 2, and the maximum modulation depth can be achieved, thereby generating stronger linear polarized light.

[0037] In the above three embodiments, an external voltage can be applied through a programmable DC power supply, so as to apply a DC voltage required for electrical control between the metal ring electrodes, and the voltage range is 0-30V.

[0038] At present, electromagnetic waves with wavelengths ranging from millimeter waves to visible light can be controlled by magnetic control, optical control, and electrical control. Generally, the modulation speed of the magnetic control method is slow (the maximum modulation speed is only in the order of microseconds), the device size is large, and it is not suitable for fast imaging and communication. The temperature control method is limited by cost and structural complexity, and the modulation depth is not ideal. The electrical control method has the advantages of high compatibility, easy integration, compact and novel structure, good control effect, and large modulation depth. The technical features and effects of the wide-band electrically controlled polarization modulator based on the NbSe2-metal multilayer structure of the present invention are as follows: (1) The preparation of the NbSe2 thin film layer adopts liquid phase stripping, mechanical stripping or chemical vapor deposition, and the preparation process is simple and the cost is low; (2) The metal ring electrode uses magnetron sputtering or vacuum evaporation to achieve a subwavelength-level precision structure; (3) The NbSe2 thin film layer is a superconducting material, which can modulate the millimeter wave to visible light band by itself, and the external electric field can increase the modulation depth and make the modulation depth uniform; (4) The intensity of the external electric field can be adjusted by a programmable DC power supply to achieve arbitrary regulation of the polarization signal; (5) The NbSe2-metal multilayer structure can expand the effective bandwidth and improve the polarization conversion efficiency and transmittance. (6) The above-mentioned electrically controlled polarization modulator has a wide band and can realize dynamic regulation of the polarization state of electromagnetic waves with wavelengths in the visible light band to the millimeter wave band. (7) The piezoelectric effect of the NbSe2-metal multilayer structure can be used to modulate the polarization state. The polarization states of the incident electromagnetic wave and the outgoing electromagnetic wave are tested when different voltages are applied, and the corresponding relationship between the polarization state and the voltage is marked to achieve precise control of the polarization state.

[0039] The embodiment of the present invention provides an electrically controlled polarization modulator based on a NbSe2-metal multilayer structure. It includes a substrate, a NbSe2 thin film layer arranged on the substrate, a first electrode pair arranged on the upper end surface of the NbSe2 thin film layer, and a second electrode pair arranged on the lower end surface of the substrate; the NbSe2 thin film layer is composed of a plurality of NbSe2 thin film layers stacked; the first electrode pair is composed of a first electrode and a second electrode, and the first electrode and the second electrode are combined to form a metal ring electrode; the second electrode pair is composed of a third electrode and a fourth electrode, and the third electrode and the fourth electrode are combined to form a metal ring electrode; voltage is applied to the first electrode pair and the second electrode pair for electrical control to actively modulate electromagnetic waves. The above-mentioned electrically controlled polarization modulator is prepared based on the NbSe2 thin film layer to obtain an electrically controlled polarization modulator, which can realize dynamic modulation of the polarization state of electromagnetic waves from the visible light band to the millimeter wave band. Applying an external electric field through the metal ring electrode can increase the modulation depth and make the modulation depth uniform, which greatly improves the bandwidth for modulating electromagnetic waves.

[0040] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. An electrically controlled polarization modulator based on a NbSe2-metal multilayer structure, characterized in that: It includes a substrate, a NbSe2 thin film layer arranged on the substrate, a first electrode pair arranged on the upper surface of the NbSe2 thin film layer, and a second electrode pair arranged on the lower surface of the substrate; The NbSe2 thin film layer is composed of a plurality of NbSe2 thin film layers stacked together; The first electrode pair is composed of a first electrode and a second electrode, wherein the first electrode is recessed inwardly at a position opposite to the second electrode and the second electrode is recessed inwardly at a position opposite to the first electrode to form a metal ring electrode; The second electrode pair is composed of a third electrode and a fourth electrode, the third electrode is recessed inward at a position opposite to the fourth electrode, and the fourth electrode is recessed inward at a position opposite to the third electrode to form a metal ring electrode; the first electrode, the second electrode, the third electrode and the fourth electrode all include a semicircular structure recessed inward; the first electrode pair and the second electrode pair are made of gold, silver, copper, iron, aluminum or platinum; Voltage is applied to the first electrode pair and the second electrode pair for electrical control so as to actively modulate the electromagnetic wave.

2. The electrically controlled polarization modulator based on the NbSe2-metal multilayer structure according to claim 1, characterized in that: The number of thin film layers included in the NbSe2 thin film layer is 5-9.

3. The electrically controlled polarization modulator based on NbSe2-metal multilayer structure according to claim 2, characterized in that: The thickness of the NbSe2 thin film layer is 12-50nm.

4. The electrically controlled polarization modulator based on NbSe2-metal multilayer structure according to claim 2, characterized in that: The NbSe2 thin film layer is prepared by liquid phase stripping, mechanical stripping or chemical vapor deposition.

5. The electrically controlled polarization modulator based on NbSe2-metal multilayer structure according to claim 2, characterized in that: The thickness of the first electrode pair and the second electrode pair are both 120-400 μm.

6. The electrically controlled polarization modulator based on NbSe2-metal multilayer structure according to claim 5, characterized in that: The diameter of the semicircular structure is 1.2-4 mm.

7. The electrically controlled polarization modulator based on NbSe2-metal multilayer structure according to claim 6, characterized in that: The first electrode pair and the second electrode pair are both prepared by using magnetron sputtering technology or vacuum evaporation technology.

8. The electrically controlled polarization modulator based on NbSe2-metal multilayer structure according to claim 6, characterized in that: The substrate is an indium tin oxide substrate, and the thickness of the indium tin oxide substrate is 12-50 nm.

9. The electrically controlled polarization modulator based on NbSe2-metal multilayer structure according to claim 6, characterized in that: The substrate is a semiconductor element substrate, and the thickness of the semiconductor element substrate is 30-80 μm.

10. The electrically controlled polarization modulator based on NbSe2-metal multilayer structure according to claim 9, characterized in that: The semiconductor element substrate is a silicon substrate or a germanium substrate.

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