Photothermoelectric near-infrared photoelectric detector

Abstract

The invention relates to the technical field of photoelectric detection, and provides a photo-thermoelectric near-infrared photoelectric detector. Comprising a silicon-based substrate, and a pyroelectric material layer is arranged on the surface of the silicon-based substrate and used for converting thermal signals into electric signals. The silver absorption metasurface is arranged on the pyroelectric material layer and comprises a cylinder structure and a grating structure, and the cylinder structure and the grating structure are symmetrically broken in the y-axis direction and are used for absorbing incident light with specific wavelength and polarization state and converting the incident light into thermal signals. According to the invention, a Q-BICs mechanism is introduced by destroying the symmetry of the grating structure, so that the photo-thermal electric detector with high quality factor and high polarization sensitivity is realized. The detector can generate an ultra-narrow-band resonance spectrum in a near-infrared band of 875 nm, and has high-selectivity response to linear polarization and circularly polarized light. Due to the characteristics of quick response and high monochromaticity, the material has a wide application prospect in the field of high-integration multifunctional photoelectric detection and sensing.

Description

Technical Field

[0001] The present application relates to the field of infrared detection technology, and in particular to a photothermoelectric near-infrared photodetector. Background Art

[0002] With the development of photoelectric detection technology, polarization detection is increasingly used in imaging, optical communications and other fields. Traditional thermoelectric polarization detectors usually have a wide spectral absorption range and are insensitive to polarization. They often require external polarizers or filters, which increases the complexity and volume of the optical system.

[0003] In recent years, polarization detectors based on photonic crystals and plasmonic metamaterials have gradually attracted attention. By designing metasurfaces with high spectral selectivity and flexible response control, efficient polarization detection can be achieved without additional optical elements. However, in the near-visible light band, due to the large imaginary part of the dielectric constant of the material, it is still challenging to achieve monochromatic polarization-sensitive thermoelectric detection. Summary of the invention

[0004] The present application aims to solve at least one of the technical problems existing in the prior art or related art.

[0005] To this end, the present application provides a monochromatic polarization-sensitive near-infrared detector based on plasmon quasi-bound states (Q-BICs), which uses structural symmetry breaking to achieve strong optical anisotropy and high polarization ratio, and combines pyroelectric materials (LiNbO3) for pyroelectric signal conversion. The proposed on-chip plasmon material device overcomes the problems of low integration and slow response speed in traditional detectors.

[0006] The technical solution is as follows, including: Silicon-based substrate; A pyroelectric material layer, which is disposed on the surface of the silicon-based substrate and is used to convert thermal signals into electrical signals; A silver absorption metasurface is placed on the pyroelectric material layer, and the silver absorption metasurface includes a cylindrical structure and a grating structure. The cylindrical structure and the grating structure are symmetric in the y-axis direction and are used to absorb incident light of a specific wavelength and polarization state and convert it into a thermal signal.

[0007] In a possible technical solution, further, the cylindrical structures are arranged on both sides of the grating structure to form a periodicity in the y-axis direction, so as to generate a sharp quasi-continuous domain bound state absorption peak.

[0008] In this technical solution, the number of cylindrical structures arranged on both sides of each grating structure is at least four.

[0009] In a possible technical solution, further, the height of the cylindrical structure is 180 nanometers.

[0010] In this technical solution, the maximum absorption peak is reached when the height of the cylindrical structure is 180 nanometers.

[0011] In a possible technical solution, further, the period of the grating structure is a one-dimensional period, and the cross-section of the grating structure is rectangular.

[0012] In a possible technical solution, further, the symmetry breaking of the cylindrical structure and the grating structure in the y-axis direction also includes being achieved by adjusting the offset of the cylindrical structure.

[0013] In a possible technical solution, further, the offset is 15 nanometers. In this technical solution, when the offset increases to 15 nanometers, the chiral metasurface can achieve nearly perfect left-handed light absorption, while the absorption rate for right-handed light remains below 0.05. This strong circular dichroism response provides theoretical support for chiral light detection.

[0014] In a possible technical solution, further, the pyroelectric material layer is a lithium niobate pyroelectric material layer, which generates an electric signal through the pyroelectric effect under temperature changes, thereby outputting a signal current or voltage.

[0015] In a possible technical solution, further, the thickness of the pyroelectric material layer is 200 nanometers.

[0016] In a possible technical solution, further, the detector has an operating wavelength of 875 nm, and based on a quality factor (Q-factor) of up to 550 at this wavelength, a narrow-band absorption spectrum with high monochromaticity is achieved.

[0017] Beneficial effects of the present application: The present application provides a monochromatic polarization-sensitive pyroelectric detection device based on plasmon quasi-bound states (Q-BICs), including a silver absorption metasurface, a lithium niobate pyroelectric material layer, and a silicon-based substrate. By introducing a one-dimensional grating structure into the silver absorption metasurface and destroying its symmetry, strong optical anisotropy is achieved, supporting a quasi-bound state mode with a high Q value, and being able to achieve high polarization ratio and monochromatic absorption in the near-infrared band (875 nanometers). The silver absorption metasurface on the top effectively converts light absorption into heat, and generates electrical signals through the pyroelectric effect of lithium niobate, giving the detector high sensitivity and responsiveness. In addition, the present application can also perform sensitive detection of linearly polarized light and circularly polarized light, and is suitable for fields such as optical polarization detection and high-resolution imaging.

[0018] Additional aspects and advantages of the present application will become apparent in the following description or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which: Figure 1 A schematic diagram of the structure of a photothermoelectric near-infrared photodetector according to an embodiment of the present application is shown; Figure 2 This is a comparison of the absorption spectra when the cylindrical structure height is 0 nanometers, 180 nanometers and 300 nanometers respectively.

[0020] Figure 3 It is the absorption spectrum of the silver absorption metasurface in the spectral range of 700 nanometers to 1000 nanometers.

[0021] Figure 4 It is the equivalent circuit diagram of the pyroelectric detector.

[0022] Figure 5 This is a schematic diagram of the detector's transient temperature and output transient signal current.

[0023] Figure 6 This is a schematic diagram of the transient temperature change of the lithium niobate pyroelectric material layer under different pulse powers.

[0024] Figure 7 It is a schematic diagram of voltage reading and current reading when different external impedances are connected.

[0025] Figure 8 Schematic diagram showing the calculation of the absorptivity and output current depending on the polarization direction.

[0026] Fig. 9 is the top view of the offset cylindrical structure.

[0027] Fig.10 Schematic diagram of the differential circular dichroism response for circularly polarized light detection.

[0028] The accompanying drawings are marked as follows: Silicon-based substrate 1, pyroelectric material layer 2, cylindrical structure 3, grating structure 4. DETAILED DESCRIPTION

[0029] In order to more clearly understand the above-mentioned purposes, features and advantages of the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0030] In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present application is not limited to the specific embodiments disclosed below.

[0031] Refer to the following Figures 1 to 10 The present invention describes a photothermoelectric near-infrared photodetector provided according to some embodiments of the present application.

[0032] Example 1 This embodiment provides a photothermoelectric near-infrared photothermoelectric near-infrared photodetector, comprising: Silicon-based substrate 1; A pyroelectric material layer 2, which is disposed on the surface of the silicon-based substrate 1 and is used to convert a thermal signal into an electrical signal, wherein the pyroelectric material layer 2 is a lithium niobate pyroelectric material layer with a thickness of 200 nanometers, and generates an electrical signal through the pyroelectric effect under temperature changes, thereby outputting a signal current or voltage; A silver absorption metasurface is placed on the pyroelectric material layer 2, and the silver absorption metasurface includes a cylindrical structure 3 and a grating structure 4. The period of the grating structure 4 is a one-dimensional period, and the cross-section of the grating structure 4 is rectangular. The cylindrical structure 3 and the grating structure 4 are symmetric in the y-axis direction, and are used to absorb incident light of a specific wavelength and polarization state and convert it into a thermal signal, wherein the height of the cylindrical structure 3 is 180 nanometers, the grating period is 850 nanometers, and the material of the pyroelectric material layer 2 is lithium niobate (LiNbO3).

[0033] In practical applications, the incident light is incident from one side of the silver absorption metasurface (cylindrical structure 3 and grating structure 4). The silver absorption metasurface layer forms a strong optical anisotropy through symmetry breaking, which can realize sensitive detection of linearly polarized light and circularly polarized light. The incident light is absorbed by the silver metasurface layer through the resonance effect, producing a strong photothermal effect and forming a narrow-band spectral absorption peak in the near-infrared band. Due to the introduction of Q-BICs, the absorption efficiency of light is greatly enhanced, and the absorption peak has a high Q value.

[0034] The absorbed light energy will cause the temperature of the pyroelectric material layer 2 to rise, and lithium niobate converts the temperature change into an electrical signal through the pyroelectric effect. The response of the electrical signal is directly related to the polarization state of the absorbed light, and the detection of polarized light can be achieved by monitoring the change of the electrical signal. The detector exhibits good monochromaticity at a wavelength of 875 nanometers, with an optical absorption peak with a high polarization ratio and a high Q value.

[0035] In this application, the silver absorption metasurface can effectively achieve strong polarization-sensitive absorption through the introduced Q-BICs structure, and combined with the pyroelectric effect of the lithium niobate layer, realizes the conversion of light, heat and electricity signals. The absorbed light energy directly stimulates the pyroelectric effect and outputs the corresponding electrical signal. This structure simplifies the system design and improves the integration and sensitivity of the detector. In addition, the relative independence of the working mechanisms of the silver absorption metasurface and the pyroelectric material layer 2 allows it to be divided into two modules and optimized independently.

[0036] It should be noted that the cylindrical structures 3 are arranged on both sides of the grating structure 4 to form a periodicity in the y-axis direction to generate a sharp quasi-continuous domain bound state absorption peak. In this technical solution, the number of cylindrical structures 3 arranged on both sides of each grating structure 4 is four.

[0037] It should be noted that the present application further studies the evolution characteristics of the absorption spectrum of the cylindrical structure 3 height in the silver absorption metasurface. The absorption spectrum at different cylindrical structure 3 heights shows a significant change trend. By calculating and analyzing the evolution of the cylindrical structure 3 height from 0 nanometers to 300 nanometers, the influence of the silver column height on the absorption peak position, intensity and spectral line width is revealed. Figure 2 As shown, we plotted the absorption spectra when the cylinder heights are 0 nm, 180 nm, and 300 nm, clearly illustrating the effect of the cylinder structure on the absorption spectrum.

[0038] The present application introduces a cylindrical structure 3 in a one-dimensional grating to form a periodicity in the Y-axis direction, thereby producing a sharp Q-BICs absorption peak. The height of the cylindrical structure 3 is gradually increased from 0 to 300 nanometers. As the height of the cylindrical structure 3 increases, the Q-BICs mode gradually appears, and the line width and resonance intensity of the absorption spectrum increase simultaneously, reaching a maximum absorption peak when the height of the cylindrical structure 3 is 180 nanometers. Afterwards, as the height continues to increase, the absorption linewidth narrows, the resonance peak decreases, the Q-BIC reverts to BIC, and becomes invisible in the spectrum. Despite the limitations imposed by the inherent losses of silver, the quality factor of the proposed plasma surface lattice resonance still reaches 550, which is rare in the near-infrared region and meets our requirements for monochromaticity. In addition, as Figure 3 As shown, we calculated the absorption spectrum in the range of 700 nm-1000 nm to ensure that the background spectrum near the working wavelength is clean.

[0039] This application determined the significant influence of the height of the cylindrical structure 3 on the absorption peak and line width through analysis and simulation calculation, and achieved the best monochromatic light absorption effect when the height was 180 nanometers. This design provides theoretical support for the optimization of efficient polarization-sensitive photothermoelectric detectors, and reveals the important role of the height adjustment of the cylindrical structure 3 in controlling optical performance.

[0040] Example 2 This embodiment further provides an equivalent circuit model of a pyroelectric detector based on the embodiment 1. Figure 2 As shown, the pyroelectric material layer 2 is a core component for thermoelectric signal conversion, and its working principle can be simulated by an equivalent circuit.

[0041] The equivalent circuit includes a capacitive element Cd, a resistive element Rd, an external load resistor Rext and an external circuit capacitor Cext connected to the pyroelectric material layer 2. When the pyroelectric material layer 2 conducts heat from the silver super surface layer, the pyroelectric effect will produce an instantaneous temperature change in the lithium niobate layer 3. This temperature change will drive the accumulation of polarized charges in the pyroelectric material layer 2 and form an output electrical signal through the load resistor Rext.

[0042] In practical applications, the output response of the pyroelectric signal is closely related to the capacitance and load resistance of the pyroelectric material. By optimizing the selection of the load resistance, the output electrical signal amplitude of the pyroelectric material layer 2 can be adjusted. Figure 3 As shown in the figure, the amplitude and response time of the output electrical signal change significantly under different load resistance values. When the load resistance value is small, the detector's response time is fast, but the signal amplitude is low; when the load resistance increases, the signal amplitude increases, but the response speed slows down. By properly selecting the load resistance, an optimal balance can be achieved between signal strength and response speed.

[0043] This application accurately simulates the thermoelectric conversion process of the pyroelectric detector through an equivalent circuit model, and provides a theoretical basis for optimizing the performance of the detector. The equivalent circuit model can effectively explain the pyroelectric effect, response speed and signal strength regulation mechanism of the detector, and has important application value.

[0044] The symmetry breaking of the cylindrical structure 3 and the grating structure 4 in the y-axis direction also includes being achieved by adjusting the offset of the cylindrical structure 3 .

[0045] Example 3 Based on Example 2, this example studies the optical response switching behavior of the above detector under 875 nm near-infrared pulse excitation. Figure 5 As shown, the transient temperature change and pyroelectric current response of the lithium niobate pyroelectric material layer under pulsed laser irradiation are demonstrated. When the device is irradiated by laser without bias voltage, a transient negative current spike is generated rapidly; when the laser is turned off, a positive pyroelectric current is generated. This process can be divided into four stages.

[0046] In stage I, the laser pulse is not turned on and the temperature of the lithium niobate pyroelectric material layer remains unchanged. At this time, the spontaneous polarization charge inside the lithium niobate attracts an equal amount of induced charge due to electrostatic induction, resulting in a weak dark current in the device, but no pyroelectric current is generated.

[0047] Entering stage II, when the laser pulse is turned on, the pyroelectric film begins to heat up. As the temperature rises, the polarization level of the film gradually decreases, and the bound charge decreases accordingly. In order to maintain dynamic charge balance, the excess free charge is released through the external load, generating a negative current signal.

[0048] In stage III, after continuous pulse energy absorption, the temperature of the device gradually increases and eventually reaches a steady-state temperature, at which time the current signal gradually decreases and tends to zero.

[0049] When entering the IV stage, the laser pulse is turned off and the device begins to cool through natural convection and thermal conduction, generating a positive pyroelectric current signal during this process.

[0050] Through this example, the temperature response of the device under pulse excitation conditions and the dynamic behavior of the pyroelectric current were verified, further revealing the detector's sensitive detection capability for near-infrared light without bias voltage. This feature provides a theoretical basis for the application of efficient pyroelectric detectors in pulse light detection.

[0051] It is worth mentioning that the present application further studies the transient temperature response characteristics of the detector under different powers. The detector is illuminated by a pulse light source, the transient temperature rise is measured, and the response time of the detector is analyzed.

[0052] Specifically, if Figure 6 As shown, with the increase of incident light power, the surface temperature of the detector rises rapidly. At lower power, the temperature rise is smaller, the response time is shorter, and the temperature stability state can be reached in a very short time. When the light power gradually increases, the rate of temperature rise also increases, and the response time of the detector remains within a short range, proving that the device has a fast thermal response capability. The linear relationship between steady-state temperature and pulse power provides great convenience for quantitative modulation. By optimizing the material selection and structural design of the pyroelectric material layer 2, the detector of the present application can not only achieve temperature changes in a short time, but also has a higher thermoelectric conversion efficiency. The rapid temperature rise characteristics of the device give it a wide range of application prospects in transient optical signal detection, especially in the fields of high-speed imaging and real-time monitoring.

[0053] This embodiment verifies the transient temperature response characteristics of the detector under different power conditions, and proves that it has an extremely short heating time and good thermoelectric conversion performance, providing a theory for achieving efficient and rapid photoelectric detection.

[0054] Example 4 On the basis of the above embodiments, this embodiment further studies the detector reading method when different resistance values ​​are externally connected, which is a method of using a low resistance value resistor to read the current signal and a high resistance value resistor to read the voltage signal.

[0055] like Figure 7 As shown in the figure, when a low-resistance resistor is connected externally, the detector mainly reads the current signal. In this method, the detector has a short response time and can quickly respond to changes in the optical signal, which is suitable for high-speed pulse light detection applications. In this case, although the current value of the output signal is small, its response speed is fast, and it can capture the transient changes of the pulse light, with high time resolution.

[0056] On the other hand, when a high-resistance resistor is connected externally, the detector mainly reads a voltage signal. At this time, the sensitivity of the detector is significantly improved, the output voltage is large, and it can effectively amplify weak light signals, which is suitable for high-precision photoelectric signal detection. However, since the higher resistance increases the time constant of the circuit, the response speed of the detector will be reduced. This method is more suitable for occasions where the signal strength is accurately measured, especially in weak light detection applications, where the signal-to-noise ratio can be significantly improved through high-resistance resistors to obtain higher quality output signals.

[0057] This application provides guidance for optimizing the design of detectors in different application scenarios by comparing the readout methods under low-resistance and high-resistance resistors. For applications that require fast response, low-resistance resistors can achieve fast readout of current signals; while in high-sensitivity weak light detection, high-resistance resistors are more preferred for reading voltage signals.

[0058] Example 5 This example explores the application of near-infrared pyroelectric detectors in highly polarization-sensitive responses, focusing on high optical anisotropy and pyroelectric conversion efficiency. The plasmonic metasurface we designed can effectively detect linearly polarized light. To verify the optical anisotropy of the detector, we continuously changed the polarization angle from 0 to 360 degrees and studied the effect of the polarization angle on the absorptivity at a wavelength of 875 nanometers. The results are shown in Figure 2. Figure 8 As shown, the incident light is linearly polarized light, and the absorptivity of the detector as a function of the polarization angle can be well fitted by a sine function. The polarization-resolved pyroelectric current response can also be fitted by a similar formula.

[0059] In traditional polarization detection methods, the polarization ratio (PR) is usually used to evaluate sensitivity. The polarization ratio (PR) is defined as the ratio of the maximum signal to the minimum signal. Although this method calculates the difference between the maximum and minimum values, it ignores the overall response of the detector to the signal and therefore cannot fully reflect the polarization sensitivity. Therefore, when evaluating polarization sensitivity, it is necessary to consider both the responsivity and the polarization ratio. The responsivity is used to describe the absolute response capability of the detector, and the two together determine the polarization detection performance of the detector.

[0060] The detector of the present application exhibits extremely high polarization sensitivity at a wavelength of 875 nanometers. Under unit light power (1 watt) irradiation, the current signal changes by about 0.67 microamperes for each degree of polarization angle change, and the polarization ratio is close to 13. Compared with the polarization angle sensitivity of detectors in the prior art, the effect is more significant. For example, existing polarization detectors based on high-loss materials such as graphene generally have a polarization angle sensitivity of 0.1 to 0.3 microamperes per degree. This high sensitivity can be attributed to the response rate of up to 65.9 microamperes per watt of light power (obtained from the linear relationship between signal current and light power) and the higher polarization ratio. In the near-visible band, the absorption of linearly polarized light at a polarization angle of 0 degrees cannot reach zero due to the high intrinsic loss of plasmon materials (such as silver). In mid-infrared or far-infrared research, detectors may achieve higher polarization ratios.

[0061] In addition, we studied the temperature and current signal changes at 0 and 90 degree polarization angles separately. The results show that under the same pulse excitation conditions, the temperature change and current signal at 90 degree polarization are significantly higher than those at 0 degree polarization. This difference shows that the detector can accurately detect the polarization direction, thus providing support for polarization-sensitive applications.

[0062] Example 6 This embodiment further deviates the structure of the cylinder based on the structure of the above embodiment, such as Fig. 9As shown. A chiral plasmonic metasurface that breaks mirror symmetry is designed, which can effectively couple electric and magnetic dipoles and produce significant chiral responses. In order to achieve monochromaticity, the design introduces in-plane mirror symmetry breaking in the metasurface by offsetting the position of the cylindrical structure 3 to induce a chiral response. As the offset of the cylindrical structure 3 increases, the quality factor (Q-factor) of the chiral quasi-bound states (Q-BICs) is studied. The results show that when the offset increases from 0 nanometers to 100 nanometers, the quality factor gradually decreases. However, when the circular dichroism response reaches the maximum (offset of 15 nanometers), the quality factor (Q-factor) only decreases from 550 to 400, which maintains the monochromaticity of the chiral Q-BICs, which is in sharp contrast to the exponential decay of the quality factor in previous studies. This phenomenon is attributed to the fact that the optical absorption is mainly dominated by the grating structure 4, while the offset of the cylindrical structure 3 is only used to break the mirror symmetry and produce a circular dichroic response. Circular dichroism (CD) can be defined by the difference in absorption between left-handed and right-handed light.

[0063] When analyzing the response to two types of circularly polarized light (left-handed and right-handed), it was found that when the offset of the cylindrical structure 3 was 0 nanometers, the absorption difference between left-handed and right-handed light was small, but when the offset increased to 15 nanometers, the chiral metasurface was able to achieve nearly perfect absorption of left-handed light, while the absorption rate of right-handed light remained below 0.05. This strong circular dichroism response provides theoretical support for chiral light detection.

[0064] like Fig.10 As shown in Figure 1, we further studied the evolution of the optical response when the offset changes from -100 nm to 100 nm. For opposite offsets, the chiral response is completely reversible, resulting in the generation of two enantiomers with opposite chiral dichroism. To further clarify the relationship between intrinsic chirality and circular dichroism response, the ellipticity is described by Stokes parameters (S0 and S3), S0 is the first Stokes parameter, and S3 is the fourth Stokes parameter, which is used to characterize the intrinsic chirality. The calculation results show that the circular dichroism response is closely related to the intrinsic chirality as the offset changes.

[0065] In the study of transient temperature response, different types of circularly polarized light irradiation produced significant differences in temperature changes. Due to the temperature changes caused by optical chiral dichroism, the output signal current also produced significant differences. The results show that the signal current generated by left-handed light is significantly greater than that of right-handed light, successfully achieving a high polarization ratio of circularly polarized light signal output.

[0066] The present application provides a monochromatic polarization-sensitive pyroelectric detection device based on plasmon quasi-bound states Q-BICs, including a silver absorption metasurface, a lithium niobate pyroelectric material layer, and a silicon-based substrate. By introducing a one-dimensional grating structure on the silver absorption metasurface and destroying its symmetry, strong optical anisotropy is achieved, supporting a high-Q-value quasi-bound state (Q-BICs) mode, and being able to achieve high polarization ratio and monochromatic absorption in the near-infrared band (875 nanometers). The silver absorption metasurface on the top effectively converts light absorption into heat, and generates electrical signals through the pyroelectric effect of lithium niobate, giving the detector high sensitivity and responsiveness. In addition, the present application can also perform sensitive detection of linearly polarized light and circularly polarized light, and is suitable for fields such as optical polarization detection and high-resolution imaging.

[0067] In this application, the term "plurality" means two or more than two, unless otherwise clearly defined. The terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0068] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0069] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A photothermoelectric near-infrared photodetector, characterized in that: include: Silicon-based substrate (1); A pyroelectric material layer (2), which is disposed on the surface of the silicon-based substrate (1) and is used to convert a thermal signal into an electrical signal; A silver absorption metasurface is disposed on the pyroelectric material layer (2), the silver absorption metasurface comprising a cylindrical structure (3) and a grating structure (4), wherein the cylindrical structure (3) and the grating structure (4) are symmetric in the y-axis direction and are used to absorb incident light of a specific wavelength and polarization state and convert it into a thermal signal.

2. The photothermoelectric near-infrared photodetector according to claim 1, characterized in that: The cylindrical structures (3) are arranged on both sides of the grating structure (4) to form a periodicity in the y-axis direction, and are used to generate a sharp quasi-continuous domain bound state absorption peak.

3. The photothermoelectric near-infrared photodetector according to claim 2, characterized in that: The number of cylindrical structures (3) arranged on both sides of each grating structure (4) is at least four.

4. The photothermoelectric near-infrared photodetector according to claim 2, characterized in that: The height of the cylindrical structure (3) is 180 nanometers.

5. The photothermoelectric near-infrared photodetector according to claim 2, characterized in that: The period of the grating structure (4) is a one-dimensional period, and the cross-section of the grating structure (4) is rectangular.

6. The photothermoelectric near-infrared photodetector according to claim 2, characterized in that: The symmetry breaking of the cylindrical structure (3) and the grating structure (4) in the y-axis direction is also achieved by adjusting the offset of the cylindrical structure (3).

7. The photothermoelectric near-infrared photodetector according to claim 6, characterized in that: The offset is 15 nanometers.

8. The photothermoelectric near-infrared photodetector according to claim 1, characterized in that: The pyroelectric material layer (2) is a lithium niobate pyroelectric material layer.

9. The photothermoelectric near-infrared photodetector according to claim 8, characterized in that: The thickness of the pyroelectric material layer (2) is 200 nanometers.

10. The photothermoelectric near-infrared photodetector according to claim 1, characterized in that: The working wavelength of the detector is 875 nm.

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