A wide-band infrared tunable polarization device and imaging method thereof

Abstract

The present invention proposes a wide-band infrared tunable polarization device and an imaging method thereof, which belong to the technical field of metamaterials and metasurfaces. The problem that the existing polarization device cannot meet the requirements of being applicable to a wide-band infrared range and being able to obtain full polarization information without losing polarization imaging resolution is solved. It includes a dielectric layer, a plurality of vanadium dioxide gratings and a chiral metasurface structure arranged above the dielectric layer, and the plurality of vanadium dioxide gratings are fixedly arranged inside the dielectric layer; in the chiral metasurface structure, the first component, the third component and the fifth component are arranged in parallel, the two ends of the second component are respectively fixedly connected to the first component and the third component, the first component and the third component are respectively located on both sides of the second component, and are both perpendicular to the second component, the two ends of the fourth component are respectively fixedly connected to the third component and the fifth component, the third component and the fifth component are respectively located on both sides of the fourth component, and are both perpendicular to the fourth component. It can achieve the acquisition of full polarization information.

Description

Technical Field

[0001] The invention belongs to the technical field of metamaterials and metasurfaces, and in particular relates to a wide-band infrared tunable polarization device and an imaging method thereof. Background Art

[0002] Polarization is an important characteristic of light, just like intensity, wavelength and phase. Traditional imaging technology only captures the intensity and spectral information of light, while ignoring the polarization information in the scene. However, the polarization state of light contains rich physical and chemical properties, which can reveal deep information such as the surface morphology, roughness, optical activity and chemical properties of materials. However, traditional polarization devices usually rely on mechanically rotated polarizers or retardation wave plates to measure the polarization information of light. Although this method can accurately obtain data in different polarization states, the acquisition process is time-consuming. At the same time, the equipment is bulky and complex in structure, which makes it difficult to meet the application requirements of portability and high efficiency. To overcome these shortcomings, pixelated linear polarization devices came into being. This type of device is composed of micro-nano metal gratings in different directions, which can simultaneously obtain information in multiple linear polarization directions in a single exposure, thereby significantly improving the acquisition efficiency and integration of polarization information. However, the device cannot detect the circular polarization state, which limits its applicability in application scenarios that require full polarization description.

[0003] In recent years, polarization detection technology based on chiral metasurfaces has received widespread attention. Chiral metasurfaces are two-dimensional optical materials composed of subwavelength nanostructures with geometric asymmetry. By precisely designing these structures, selective response to left-handed circular polarization (LCP) and right-handed circular polarization (RCP) can be achieved. Compared with mechanically rotated wave plates, chiral metasurfaces can not only greatly improve the detection efficiency of circularly polarized signals, but also have the advantages of ultra-thinness, light weight and easy integration. This gives it significant advantages in dynamic, high-resolution imaging scenarios. In addition, chiral metasurfaces also have wide spectral adaptability. By designing nanostructures of different scales and shapes, multiple spectral ranges from visible light to infrared can be covered.

[0004] However, the existing pixelated full polarization devices arrange micro-nano metal gratings and chiral metasurfaces at different positions in space, and then interpolate and solve different polarization information, which leads to a significant reduction in polarization imaging resolution. Therefore, there is an urgent need for a polarization device that is suitable for a wide-band infrared range and can obtain full polarization information without losing polarization imaging resolution. Summary of the invention

[0005] In view of this, in order to solve the problem that existing polarization devices cannot meet the requirements of being applicable to a wide-band infrared range and being able to obtain full polarization information without losing polarization imaging resolution, the present invention proposes a wide-band infrared tunable polarization device and an imaging method thereof.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A wide-band infrared tunable polarization device, characterized by comprising:

[0008] dielectric layer;

[0009] A plurality of vanadium dioxide gratings are arranged in parallel and fixedly disposed inside the dielectric layer;

[0010] A chiral metasurface structure comprises a first component, a second component, a third component, a fourth component and a fifth component, wherein the first component, the third component and the fifth component are arranged in parallel, two ends of the second component are respectively fixedly connected to the first component and the third component, the first component and the third component are respectively located on both sides of the second component and are both perpendicular to the second component, two ends of the fourth component are respectively fixedly connected to the third component and the fifth component, the third component and the fifth component are respectively located on both sides of the fourth component and are both perpendicular to the fourth component, and the first component, the second component, the third component, the fourth component and the fifth component are all fixedly arranged above the dielectric layer.

[0011] As a preferred solution of the above-mentioned wide-band infrared tunable polarization device, the first component, the second component, the third component, the fourth component and the fifth component are an integrally formed structure.

[0012] As a preferred solution of the above-mentioned wide-band infrared tunable polarization device, the chiral metasurface structure is made of silicon material.

[0013] As a preferred solution of the above-mentioned wide-band infrared tunable polarization device, the dielectric layer is made of silicon oxide material.

[0014] As a preferred solution of the above-mentioned wide-band infrared tunable polarization device, the reversible phase change process of the vanadium dioxide grating from a metallic state to an insulating state can be achieved by external excitation, and the external excitation is light, temperature or voltage.

[0015] As a preferred solution of the above-mentioned wide-band infrared tunable polarization device, the angle between the vanadium dioxide grating and the width direction of the dielectric layer is 0°, 45°, 90° or 135°.

[0016] As a preferred embodiment of the above-mentioned wide-band infrared tunable polarization device, the lateral period and longitudinal period of the chiral metasurface structure are both p 1= 1 μm, the height of the chiral metasurface structure is h 3 =0.6μm.

[0017] As a preferred solution of the above-mentioned wide-band infrared tunable polarization device, the second component and the fourth component are both rectangular parallelepipeds with equal sizes and a length of L. 3 = 0.5 μm, width L 5 = 0.2 μm, the length of the third component is L 1 = 0.3 μm, the width of the third component is L 2 =0.2μm, the first component and the fifth component are both cubes with a width of L 4 =0.1μm.

[0018] As a preferred solution of the above-mentioned wide-band infrared tunable polarization device, the period of the vanadium dioxide grating is p 2 = 0.2 μm, the height of the vanadium dioxide grating is h 1 =0.6μm, the width w of the vanadium dioxide grating 1 =0.1μm; the distance between the vanadium dioxide grating and the chiral metasurface structure is h 2 =0.4μm.

[0019] The present invention also provides a wide-band infrared tunable polarization imaging method, which uses the above-mentioned wide-band infrared tunable polarization device, including:

[0020] By changing the ambient temperature, the vanadium dioxide of the vanadium dioxide grating switches between a metallic state and an insulating state;

[0021] When vanadium dioxide is in a metallic state, the incident light is circularly polarized, and first passes through the chiral metasurface structure to improve its transmittance and circular dichroism. After passing through the vanadium dioxide grating, the transmittance of the circularly polarized light drops sharply. When the incident light is linearly polarized, it first passes through the chiral metasurface structure to improve its transmittance. After passing through the vanadium dioxide grating, the linear polarized light perpendicular to the vanadium dioxide grating can achieve high transmittance, while the linear polarized light in the horizontal direction of the vanadium dioxide grating can achieve low transmittance, thus realizing the linear polarization selection function.

[0022] When vanadium dioxide is in an insulating state, the incident light is circularly polarized, and first passes through the chiral metasurface structure to improve its transmittance and circular dichroism, and then passes through the vanadium dioxide grating, the transmittance of the circularly polarized light remains unchanged; the incident light is linearly polarized, and first passes through the chiral metasurface structure to improve its transmittance, and then passes through the vanadium dioxide grating, the linear polarized light in the vertical and horizontal directions to the vanadium dioxide grating can achieve high transmittance, and at this time it does not have a linear polarization function, but has a circular polarization selection function;

[0023] The plurality of wide-band infrared tunable polarization devices are arranged periodically to form an array consistent with the size of the selected detector pixel, and each pixel is ensured to correspond one-to-one with the wide-band infrared tunable polarization device, so that linear polarization information or circular polarization information can be obtained through a single exposure, and full polarization information can be obtained through a second exposure by changing the temperature, ultimately achieving snapshot imaging within a wide band range and having the ability to image dynamic targets with high resolution.

[0024] Compared with the prior art, the wide-band infrared tunable polarization device provided by the present invention has the following beneficial effects:

[0025] The present invention provides a wide-band infrared tunable polarization device, in which, when vanadium dioxide is in a metallic state, the incident light is circularly polarized, and after passing through a chiral metasurface structure, circularly polarized light with high transmittance and high circular dichroism is obtained, and after passing through a vanadium dioxide grating, the transmittance of the circularly polarized light is sharply reduced; the incident light is linearly polarized, and after passing through a chiral metasurface structure, linearly polarized light with high transmittance is obtained, and after passing through a vanadium dioxide grating, the linearly polarized light (TM) perpendicular to the vanadium dioxide grating can achieve high transmittance, while the linearly polarized light (TE) in the horizontal direction to the vanadium dioxide grating achieves low transmittance. Finally, in the metallic state of vanadium dioxide, the wide-band infrared tunable polarization device realizes the linear polarization selection function.

[0026] When vanadium dioxide is in an insulating state, the incident light is circularly polarized, and after passing through the chiral metasurface structure, circularly polarized light with high transmittance and high circular dichroism is obtained. After passing through the vanadium dioxide grating, the transmittance of the circularly polarized light remains unchanged; the incident light is linearly polarized, and after passing through the chiral metasurface structure, linearly polarized light with high transmittance is obtained. After passing through the vanadium dioxide grating, the linear polarized light in the vertical and horizontal directions to the vanadium dioxide grating can achieve high transmittance. Finally, in the insulating state of vanadium dioxide, this wide-band infrared tunable polarizer realizes the circular polarization selection function.

[0027] Therefore, by changing the ambient temperature, vanadium dioxide can switch back and forth between the metallic state and the insulating state. When vanadium dioxide is in the metallic state, the wide-band infrared tunable polarization device can realize the linear polarization selection function, and when vanadium dioxide is in the insulating state, the wide-band infrared tunable polarization device can realize the circular polarization selection function. Finally, in the wide-band infrared range, only a single structure is used to obtain full polarization information.

[0028] Moreover, the existing full-polarization imaging device combines four metal grating-type linear polarizations of 0°, 45°, 90°, and 135° and two chiral metasurfaces of left-handed circular polarization and right-handed circular polarization to form six imaging areas; while the present invention utilizes the property of variable conductivity of vanadium dioxide to combine the metal grating and the chiral metasurface, and realizes the acquisition of linear polarization and circular polarization respectively through the conversion between the metallic state and the insulating state of vanadium dioxide, and only requires four imaging areas, thereby being able to improve the imaging resolution under the condition of limited resolution of the detector. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0030] Figure 1 is a schematic structural diagram of a wide-band infrared tunable polarization device provided in this embodiment;

[0031] Figure 2 is a front view of the wide-band infrared tunable polarization device provided in this embodiment;

[0032] Figure 3 is a top view of the wide-band infrared tunable polarization device provided in this embodiment;

[0033] Figure 4 is a transmittance curve diagram of left-handed circularly polarized light and right-handed circularly polarized light for the chiral metasurface structure of the wide-band infrared tunable polarization device provided in this embodiment;

[0034] Figure 5 is a circular dichroism (CD) curve diagram for the chiral metasurface structure of the wide-band infrared tunable polarization device provided in this embodiment;

[0035] Figure 6 is a graph showing the conductivity of vanadium dioxide changing with temperature;

[0036] Figure 7 is a curve diagram of transmittance and extinction ratio of incident linearly polarized light for the vanadium dioxide grating of the wide-band infrared tunable polarization device provided in this embodiment, when the vanadium dioxide is in a metallic state;

[0037] Figure 8 is a curve diagram of transmittance and extinction ratio of incident linearly polarized light when the vanadium dioxide grating of the wide-band infrared tunable polarization device provided in this embodiment is in an insulating state;

[0038] Fig. 9 is a transmittance curve diagram of left-handed circularly polarized light and right-handed circularly polarized light when vanadium dioxide is in a metallic state for the wide-band infrared tunable polarization device provided in this embodiment;

[0039] Fig.10 is a circular dichroism (CD) curve diagram of the wide-band infrared tunable polarization device provided in this embodiment when vanadium dioxide is in a metallic state;

[0040] Fig.11 is a transmittance curve diagram of left-handed circularly polarized light and right-handed circularly polarized light when vanadium dioxide is in an insulating state for the wide-band infrared tunable polarization device provided in this embodiment;

[0041] Fig.12 is a circular dichroism (CD) curve diagram of the wide-band infrared tunable polarization device provided in this embodiment when vanadium dioxide is in an insulating state;

[0042] Fig.13 is a curve diagram of transmittance and extinction ratio of incident linearly polarized light when vanadium dioxide is in a metallic state for the wide-band infrared tunable polarization device provided in this embodiment;

[0043] Fig.14 This is a curve diagram of transmittance and extinction ratio of incident linearly polarized light when vanadium dioxide is in an insulating state for the wide-band infrared tunable polarization device provided in this embodiment.

[0044] In the figure:

[0045] 1. Chiral metasurface structure; 2. Dielectric layer; 3. Vanadium dioxide grating; 11. First component; 12. Second component; 13. Third component; 14. Fourth component; 15. Fifth component. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely explain the technical solutions in the embodiments of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict, and the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0047] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0049] In the description of this embodiment, the terms "upper", "lower", "right" and other directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplified operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0050] See also Figure 1-14 The present embodiment is described. The present invention provides a wide-band infrared tunable polarization imaging method. The wide-band infrared tunable polarization device comprises a dielectric layer 2, a plurality of vanadium dioxide gratings 3 and a chiral metasurface structure 1. The plurality of vanadium dioxide gratings 3 are arranged in parallel and are all fixedly arranged inside the dielectric layer 2; the chiral metasurface structure 1 comprises a first component 11, a second component 12, a third component 13, a fourth component 14 and a fifth component 15. The first component 11, the third component 13 and the fifth component 15 are arranged in parallel. Two ends of the second component 12 are respectively fixedly connected to the first component 11 and the third component 13. The first component 11 and the third component 13 are respectively located on both sides of the second component 12 and are both perpendicular to the second component 12. Two ends of the fourth component 14 are respectively fixedly connected to the third component 13 and the fifth component 15. The third component 13 and the fifth component 15 are respectively located on both sides of the fourth component 14 and are both perpendicular to the fourth component 14. The first component 11, the second component 12, the third component 13, the fourth component 14 and the fifth component 15 are all fixedly arranged above the dielectric layer 2.

[0051] In the wide-band infrared tunable polarization device, the chiral metasurface structure 1 designed in this way can realize the efficient circular polarization state acquisition function and can be used as a good circular polarization device. Figure 4 and Figure 5They are the transmittance curves and circular dichroism (CD=TR-TL, where TR and TL represent the transmittance of right-handed circularly polarized light and left-handed circularly polarized light, respectively) curves of the chiral metasurface structure 1. It can be seen from the figure that in the wavelength range of 3~15μm, it has a high CD value, and the CD value at a wavelength of 6μm reaches 0.78.

[0052] Through external excitation, the conductivity of vanadium dioxide can realize the reversible phase transition process of vanadium dioxide from metallic state to insulating state. In this embodiment, temperature is used as external excitation. The trend of the conductivity of vanadium dioxide grating 3 changing with temperature is as follows: Figure 6 shown.

[0053] When vanadium dioxide is in a metallic state, the transmittance of linearly polarized light (T TM : TM transmission, i.e. the transmittance of linearly polarized light perpendicular to the grating direction) and extinction ratio (ER=T TM / T TE , where T TE The transmittance curve of linear polarized light horizontal to the grating direction is as follows Figure 7 As shown in the figure, it can be seen that the ER is relatively high in the wavelength range of 3~15μm, and reaches 1200 at 15μm. This shows that when vanadium dioxide is in a metallic state, the linear polarized light (TM) perpendicular to the vanadium dioxide grating 3 can achieve high transmittance, while the linear polarized light (TE) horizontal to the vanadium dioxide grating 3 can achieve low transmittance, so the vanadium dioxide grating 3 has a good linear polarization selection function and can be used as a linear polarization device.

[0054] When vanadium dioxide is in a metallic state, linearly polarized light as incident light first passes through the chiral metasurface structure 1 to obtain linearly polarized light with high transmittance and high circular dichroism. After passing through the vanadium dioxide grating 3, the linearly polarized light (TE) horizontal to the direction of the vanadium dioxide grating 3 is blocked, and the transmittance is sharply reduced, while the linearly polarized light (TM) perpendicular to the direction of the vanadium dioxide grating 3 can achieve high transmittance. Fig.13 The transmittance and extinction ratio (ER) curves of linear polarized light (TM) perpendicular to the 3-direction of the vanadium dioxide grating are shown in the figure. It can be seen that in the wavelength range of 3~15μm, the average value of ER can reach 600, and it reaches a maximum of 1200 at a wavelength of 15μm. The results show that the wide-band infrared tunable polarizer at this time has a good linear polarization selection function.

[0055] When vanadium dioxide is in a metallic state, circularly polarized light as incident light first passes through the chiral metasurface structure 1 to obtain circularly polarized light with high transmittance and high circular dichroism, and then passes through the vanadium dioxide grating 3, where the transmittance decreases sharply. Fig. 9 and Fig.10Figure 2 is the transmittance curve of right-handed circularly polarized light and left-handed circularly polarized light, as well as the circular dichroism (CD) curve. It can be seen that the CD value is small, only in the range of 0~0.16, indicating that the wide-band infrared tunable polarization device at this time does not have the circular polarization selection function.

[0056] When vanadium dioxide is in an insulating state, the transmittance and extinction ratio curves of linearly polarized light are as follows: Figure 8 As shown in the figure, it can be seen that the ER in the wavelength range of 3~15μm is low, only in the range of 0.4~1.4. This shows that when vanadium dioxide is in an insulating state, linear polarized light perpendicular to and horizontal to the vanadium dioxide grating 3 can achieve high transmittance, so the vanadium dioxide grating 3 does not have a polarization selection function and cannot be used as a linear polarization device.

[0057] When vanadium dioxide is in an insulating state, linearly polarized light as incident light first passes through the chiral metasurface structure 1 to obtain linearly polarized light with high transmittance and high circular dichroism. After passing through the vanadium dioxide grating 3, the linearly polarized light (TE) horizontal to the direction of the vanadium dioxide grating 3 and the linearly polarized light (TM) perpendicular to the direction of the vanadium dioxide grating 3 can both achieve high transmittance. Fig.14 This is the TM transmittance and extinction ratio (ER) curve at this time. It can be seen from the figure that in the wavelength range of 3~15μm, the range of ER is only between 0~1.5, indicating that the wide-band infrared tunable polarizer at this time does not have the linear polarization selection function.

[0058] When vanadium dioxide is in an insulating state, circularly polarized light as incident light first passes through the chiral metasurface structure 1 to obtain circularly polarized light with high transmittance and high circular dichroism. After passing through the vanadium dioxide grating 3, the transmittance remains almost unchanged. The results are shown in Fig.11 and Fig.12 As shown in the figure, within the wavelength range of 3~15μm, the average CD value can reach 0.6, and at a wavelength of 6μm it reaches 0.8. The results show that the wide-band infrared tunable polarization device at this time has a good circular polarization selection function.

[0059] Therefore, by changing the ambient temperature, vanadium dioxide can switch back and forth between the metallic state and the insulating state. When vanadium dioxide is in the metallic state, the wide-band infrared tunable polarization device can realize the linear polarization selection function, and when vanadium dioxide is in the insulating state, the wide-band infrared tunable polarization device can realize the circular polarization selection function. Finally, in the wide-band infrared range, only a single structure is used to obtain full polarization information.

[0060] Moreover, the existing full-polarization imaging device combines four metal grating-type linear polarizations of 0°, 45°, 90°, and 135° and two chiral metasurfaces of left-handed circular polarization and right-handed circular polarization to form six imaging areas; while the present invention utilizes the property of variable conductivity of vanadium dioxide to combine the metal grating and the chiral metasurface, and realizes the acquisition of linear polarization and circular polarization respectively through the conversion between the metallic state and the insulating state of vanadium dioxide, and only requires four imaging areas, thereby being able to improve the imaging resolution under the condition of limited resolution of the detector.

[0061] The relative dielectric constant of vanadium dioxide is described by the Drude model:

[0062]

[0063] in, is the high frequency dielectric constant; , is the angular frequency of the incident wave; i is the imaginary unit; The plasma frequency at can be approximated by express, , .

[0064] When the conductivity of vanadium dioxide When in the metallic state, the conductivity of vanadium dioxide When the conductivity of the vanadium dioxide material of the vanadium dioxide grating 3 changes, the vanadium dioxide is converted between the metallic state and the insulating state, and finally the designed wide-band infrared tunable polarization device is switched back and forth between the circular polarization acquisition state and the linear polarization acquisition state.

[0065] Optionally, an angle between the vanadium dioxide grating 3 and the width direction of the dielectric layer 2 is 0°, 45°, 90° or 135°. Figure 1 The direction of the X axis is the width direction of the dielectric layer 2. By changing the direction of the vanadium dioxide grating 3, information of different linear polarization directions can be obtained. By setting the angle between the vanadium dioxide grating 3 and the dielectric layer 2 to 0°, 45°, 90° or 135°, polarized light of 0°, 45°, 90° and 135° can be obtained.

[0066] Optionally, the reversible phase transition process of the vanadium dioxide grating 3 from the metallic state to the insulating state can be achieved by external excitation, and the external excitation is light, temperature or voltage. In this embodiment, the external excitation used is temperature.

[0067] Optionally, the first component 11, the second component 12, the third component 13, the fourth component 14 and the fifth component 15 are an integrally formed structure.

[0068] Optionally, the chiral metasurface structure 1 is made of silicon material.

[0069] Optionally, the dielectric layer 2 is made of silicon oxide material.

[0070] Optionally, the lateral period and longitudinal period of the chiral metasurface structure 1 are both P 1 = 1 μm, the height of the chiral metasurface structure 1 is h 3 =0.6μm.

[0071] Optionally, the second component 12 and the fourth component 14 are both cuboids with the same size and a length of L. 3 = 0.5 μm, width L 5 =0.2 μm, the length of the third component 13 is L 1 =0.3 μm, the width of the third component 13 is L 2 =0.2 μm, the first component 11 and the fifth component 15 are both cubes with a width of L 4 =0.1μm.

[0072] Optionally, the period of the vanadium dioxide grating 3 is p 2 = 0.2 μm, the height of the vanadium dioxide grating 3 is h 1 = 0.6 μm, the width w of the vanadium dioxide grating 3 1 =0.1μm.

[0073] Optionally, the distance between the vanadium dioxide grating 3 and the chiral metasurface structure 1 is h 2 =0.4μm.

[0074] Optionally, the distance between the vanadium dioxide grating 3 at the edge and the edge of the dielectric layer 2 is the edge width, and the edge width is w 2 =0.05μm.

[0075] The present invention also provides a wide-band infrared tunable polarization imaging method, which uses the above-mentioned wide-band infrared tunable polarization device. The wide-band infrared tunable polarization imaging method includes:

[0076] By changing the ambient temperature, the vanadium dioxide in the vanadium dioxide grating can be switched between a metallic state and an insulating state.

[0077] When vanadium dioxide is in a metallic state, the incident light is circularly polarized, and first passes through the chiral metasurface structure to improve its transmittance and circular dichroism. After passing through the vanadium dioxide grating, the transmittance of the circularly polarized light drops sharply. When the incident light is linearly polarized, it first passes through the chiral metasurface structure to improve its transmittance. After passing through the vanadium dioxide grating, the linear polarized light (TM) perpendicular to the vanadium dioxide grating can achieve high transmittance, while the linear polarized light (TE) horizontal to the vanadium dioxide grating can achieve low transmittance, thus realizing the linear polarization selection function.

[0078] When vanadium dioxide is in an insulating state, the incident light is circularly polarized, and first passes through the chiral metasurface structure to improve its transmittance and circular dichroism, and then passes through the vanadium dioxide grating, the transmittance of the circularly polarized light remains unchanged; the incident light is linearly polarized, and first passes through the chiral metasurface structure to improve its transmittance, and then passes through the vanadium dioxide grating, the linear polarized light in the vertical and horizontal directions to the vanadium dioxide grating can achieve high transmittance, and at this time it does not have a linear polarization function, but has a circular polarization selection function;

[0079] The plurality of wide-band infrared tunable polarization devices are arranged periodically to form an array consistent with the size of the selected detector pixel, and each pixel is ensured to correspond one-to-one with the wide-band infrared tunable polarization device, so that linear polarization information or circular polarization information can be obtained through a single exposure, and full polarization information can be obtained through a second exposure by changing the temperature, ultimately achieving snapshot imaging within a wide band range and having the ability to image dynamic targets with high resolution.

[0080] Obviously, the embodiments of the present invention disclosed above are only used to help illustrate the present invention. The embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. According to the content of this specification, many modifications and changes can be made. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. It is not necessary and impossible to exhaustively list all the embodiments here.

Claims

1. A wide-band infrared tunable polarization device, characterized in that: include: dielectric layer; A plurality of vanadium dioxide gratings are arranged in parallel and fixedly disposed inside the dielectric layer; The chiral metasurface structure comprises a first component (11), a second component (12), a third component (13), a fourth component (14) and a fifth component (15). The first component (11), the third component (13) and the fifth component (15) are arranged in parallel. Two ends of the second component (12) are respectively fixedly connected to the first component (11) and the third component (13). The first component (11) and the third component (13) are respectively located on two sides of the second component (12) and are both perpendicular to the second component (12). Two ends of the fourth component (14) are respectively fixedly connected to the third component (13) and the fifth component (15). The third component (13) and the fifth component (15) are respectively located on two sides of the fourth component (14) and are both perpendicular to the fourth component (14). The first component (11), the second component (12), the third component (13), the fourth component (14) and the fifth component (15) are all fixedly arranged above a dielectric layer.

2. The wide-band infrared tunable polarization device according to claim 1, characterized in that: The first component (11), the second component (12), the third component (13), the fourth component (14) and the fifth component (15) are an integrally formed structure.

3. The wide-band infrared tunable polarization device according to claim 1, characterized in that: The chiral super surface structure is made of silicon material.

4. The wide-band infrared tunable polarization device according to claim 1, characterized in that: The dielectric layer is made of silicon oxide material.

5. The wide-band infrared tunable polarization device according to claim 1, characterized in that: The reversible phase transition process of the vanadium dioxide grating from a metallic state to an insulating state can be achieved through external excitation, and the external excitation is light, temperature or voltage.

6. The wide-band infrared tunable polarization device according to claim 1, characterized in that: The angle between the vanadium dioxide grating and the width direction of the dielectric layer is 0°, 45°, 90° or 135°.

7. The wide-band infrared tunable polarization device according to claim 1, characterized in that: The lateral period and the longitudinal period of the chiral metasurface structure are both p1=1 μm, and the height of the chiral metasurface structure is h3=0.6 μm.

8. The wide-band infrared tunable polarization device according to claim 1, characterized in that: The second component (12) and the fourth component (14) are both rectangular parallelepipeds with equal dimensions, with a length of L3=0.5 μm and a width of L5=0.2 μm. The length of the third component (13) is L1=0.3 μm and the width of the third component (13) is L2=0.2 μm. The first component (11) and the fifth component (15) are both cubes with a width of L4=0.1 μm.

9. The wide-band infrared tunable polarization device according to claim 1, characterized in that: The period of the vanadium dioxide grating is p2=0.2 μm, the height of the vanadium dioxide grating is h1=0.6 μm, the width of the vanadium dioxide grating is w1=0.1 μm, and the distance between the vanadium dioxide grating and the chiral metasurface structure is h2=0.4 μm.

10. A wide-band infrared tunable polarization imaging method, characterized in that: The wide-band infrared tunable polarization device according to any one of claims 1 to 9 comprises: By changing the ambient temperature, the vanadium dioxide of the vanadium dioxide grating switches between a metallic state and an insulating state; When vanadium dioxide is in a metallic state, the incident light is circularly polarized, and first passes through the chiral metasurface structure to improve its transmittance and circular dichroism. After passing through the vanadium dioxide grating, the transmittance of the circularly polarized light drops sharply. When the incident light is linearly polarized, it first passes through the chiral metasurface structure to improve its transmittance. After passing through the vanadium dioxide grating, the linear polarized light perpendicular to the vanadium dioxide grating can achieve high transmittance, while the linear polarized light in the horizontal direction of the vanadium dioxide grating can achieve low transmittance, thus realizing the linear polarization selection function. When vanadium dioxide is in an insulating state, the incident light is circularly polarized, and first passes through the chiral metasurface structure to improve its transmittance and circular dichroism, and then passes through the vanadium dioxide grating, the transmittance of the circularly polarized light remains unchanged; the incident light is linearly polarized, and first passes through the chiral metasurface structure to improve its transmittance, and then passes through the vanadium dioxide grating, the linear polarized light in the vertical and horizontal directions to the vanadium dioxide grating can achieve high transmittance, and at this time it does not have a linear polarization function, but has a circular polarization selection function; The plurality of wide-band infrared tunable polarization devices are arranged periodically to form an array consistent with the size of the selected detector pixel, and each pixel is ensured to correspond one-to-one with the wide-band infrared tunable polarization device, so that linear polarization information or circular polarization information can be obtained through a single exposure, and full polarization information can be obtained through a second exposure by changing the temperature, ultimately achieving snapshot imaging within a wide band range and having the ability to image dynamic targets with high resolution.

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