Near-infrared to middle-infrared cross-band adjustable selective absorber and preparation method, use method and application thereof

Abstract

The invention provides a near-infrared to middle-infrared cross-band adjustable selective absorber and a preparation method, a use method and application thereof, and relates to the technical field of infrared light absorbers. According to the invention, the vanadium dioxide film is doped into the Fabry-Perot resonator, and the phase change of the intermediate vanadium oxide layer is thermally induced, so that the thickness of the effective medium cavity of the adjustable Fabry-Perot resonator is adjusted, and the dynamic control of multi-peak infrared light is completed. The germanium, vanadium dioxide and sapphire structure provided by the invention realizes wavelength selective absorption with dynamic modulation capability, and further realizes selective absorption of an absorption peak in a wavelength range from near-infrared to medium-wave infrared by adjusting the thickness of the germanium layer.

Description

Technical Field

[0001] The present invention belongs to the field of infrared light absorbers, and in particular relates to a near-infrared to mid-infrared cross-band adjustable selective absorber and a preparation method, a use method and an application thereof. Background Art

[0002] In recent decades, infrared photonics technology has revolutionized military reconnaissance, medical diagnosis, environmental monitoring, spectral analysis, and remote sensing. The near-infrared (NIR, 0.78-2.5μm) to mid-infrared (MIR, 2.5-25μm) wavelengths have become a research hotspot due to their unique optical properties. The NIR band has strong penetration into biological tissue, making it suitable for in vivo imaging and noninvasive testing. The MIR band covers the vibrational and rotational absorption peaks of most molecules, serving as a "fingerprint" for compositional analysis. For example, in aerospace remote sensing, MIR spectroscopy can be used to monitor atmospheric pollutants. In medicine, near-infrared photothermal therapy relies on the photothermal conversion efficiency of this wavelength. Military infrared imaging systems require broad spectral response across this wavelength range.

[0003] However, as application scenarios become more complex and dynamic, traditional infrared optical devices face significant challenges. Traditional absorbers, filters, or detectors, primarily based on static structures, have fixed spectral response ranges and cannot be adjusted in real time to accommodate environmental changes or functional requirements. This results in insufficient adaptability in complex light fields (such as those with overlapping spectra from multiple targets or strong background interference). For example, traditional infrared detectors require manual filter replacement to switch wavelengths under varying temperature or lighting conditions, severely limiting the device's real-time performance and portability.

[0004] Prior art CN112684648A discloses a broadband tunable absorber based on vanadium dioxide and a Fabry-Perot cavity, which discloses: using a vanadium dioxide resonant structure as a resonator, and changing the conductivity of the vanadium dioxide through external excitation (light, temperature, and voltage) to achieve dynamic regulation of the absorber. Then, a dielectric layer is introduced above the vanadium dioxide resonant structure to form a Fabry-Perot cavity to improve the impedance matching between the absorber and free space, stimulate new absorption peaks, and thus achieve effective broadening of the absorption band. However, the absorber adopts a four-layer structure, including a metal layer, two dielectric layers, and a vanadium dioxide resonant structure, which is more complicated in preparation process and may increase processing difficulty and cost. In addition, the dielectric layer material is limited to silicon dioxide or cycloolefin copolymers, which will limit the absorption efficiency of the absorber in the near-infrared to mid-infrared band, affecting its absorption effect on light of a specific wavelength, and failing to give full play to the advantages of broadband tunable absorption. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides a near-infrared to mid-infrared cross-band adjustable selective absorber and its preparation method, use method and application.

[0006] Terminology Notes: Unless otherwise defined, all technical and scientific terms herein have the same meanings as commonly understood by persons skilled in the art to which the claimed subject matter belongs. Unless otherwise indicated, all patents, patent applications, and publications cited herein are incorporated by reference in their entirety. If multiple definitions of a term are used herein, the definitions in this section shall prevail.

[0007] It should be understood that the above brief description and the following detailed description are exemplary and explanatory only and do not limit the subject matter of the present invention in any way. In the present invention, unless otherwise specifically stated, the use of the singular also includes the plural. It should also be noted that unless otherwise stated, the use of "or" and "or" means "and / or". In addition, the use of the term "including" and other forms such as "comprising", "including" and "containing" are not limiting.

[0008] The term "near-infrared to mid-infrared cross-band" refers to the continuous spectral range covering the near-infrared band (usually 0.75-2.5μm) to the mid-infrared band (usually 2.5-25μm).

[0009] The term "selective absorber" refers to a device that absorbs light within a specific wavelength range while having weak or no absorption of light at other wavelengths.

[0010] The term "Fabry-Perot resonator" refers to an optical structure consisting of two parallel reflective surfaces, in which light is reflected multiple times between the two reflective surfaces and interferes, thereby achieving selective enhancement or suppression of light of a specific wavelength.

[0011] The term "atomic layer deposition process" refers to a technology that can deposit thin films layer by layer on the surface of a substrate. By alternately introducing gaseous precursors into the reaction chamber, the precursors undergo chemical adsorption and reaction on the substrate surface, thereby forming a uniform and dense film.

[0012] The term "electron beam evaporation process" refers to a technology that uses an electron beam to bombard an evaporation material, causing the material to heat, evaporate, and deposit on the surface of a substrate to form a thin film.

[0013] On the one hand, the present invention provides a cross-band adjustable selective absorber from near-infrared to mid-infrared, including a germanium dielectric layer, a vanadium dioxide thin film layer and a sapphire substrate arranged in sequence from top to bottom to form an adjustable Fabry-Perot resonator of germanium, vanadium dioxide and sapphire structure.

[0014] Specifically, the thickness of the vanadium dioxide thin film layer is 80-120 nm.

[0015] More specifically, the thickness of the vanadium dioxide thin film layer is 90-110 nm.

[0016] Preferably, the thickness of the vanadium dioxide thin film layer is 99-101 nm.

[0017] More specifically, the vanadium dioxide thin film layer is prepared by an atomic layer deposition process and a post-annealing process.

[0018] Specifically, the germanium dielectric layer has a thickness gradient, and its thickness ranges from 300 nm to 1100 nm.

[0019] Preferably, the germanium dielectric layer has a thickness in the range of 400-1000 nm.

[0020] More specifically, the thickness gradient of the germanium dielectric layer is 1-250 nm.

[0021] In some specific embodiments of the present invention, the thickness of the germanium dielectric layer includes: 400 nm, 600 nm, 800 nm and 1000 nm, and the gradient thickness is 200 nm.

[0022] Based on further solving the technical problem of the present invention or solving multiple technical problems at the same time, in the technical solution provided in the first aspect of the present invention, the preferred solution includes: The first priority option: Adjust the thickness of the vanadium dioxide film layer according to the present invention, and on the basis of satisfying the basic phase change regulation, further enhance the sensitivity of the thermally induced phase change, so that the absorption peak blue shift response speed is increased by 10%-15%.

[0023] The second priority solution: According to the present invention, the thickness and thickness gradient of the germanium dielectric layer are adjusted to further optimize the linearity of the absorption peak red shift on the basis of achieving red shift adjustment, so that the adjustment error is controlled within ±2%.

[0024] The third priority solution: A tunable Fabry-Perot resonator made of germanium, vanadium dioxide, and sapphire is formed according to the present invention. This solution not only solves the fundamental problem of absorber adjustment performance, but also further addresses the stability and reliability of absorption peak adjustment.

[0025] In another aspect, the present invention provides a method for preparing the aforementioned near-infrared to mid-infrared cross-band adjustable selective absorber, comprising: S1: Vanadium dioxide thin film layer is prepared on sapphire substrate by atomic layer deposition process and post-annealing process; S2: Depositing a germanium dielectric layer with a gradient thickness on the vanadium dioxide film by electron beam evaporation process.

[0026] Specifically, in S1, the precursors used in the atomic deposition process include: deionized water, oxygen plasma and vanadium isopropoxide.

[0027] Specifically, in S2, the electron evaporation rate is 1.5-2.5Å / s.

[0028] More specifically, the electron evaporation rate is 1.8-2.2 Å / s.

[0029] Preferably, the electron evaporation rate is 1.9-2.1 Å / s.

[0030] Based on further solving the technical problem of the present invention or solving multiple technical problems at the same time, in the technical solution provided in the second aspect of the present invention, the preferred solution includes: The first priority solution: S1, an atomic deposition process using deionized water, oxygen plasma, and vanadium isopropoxide as a precursor. This technical solution not only addresses the fundamental feasibility of the preparation method, but also further addresses the control of the composition and structure of the vanadium dioxide film layer.

[0031] The second priority solution: The electron evaporation rate in S2 is 1.5-2.5Å / s. This technical solution not only solves the basic problem of the feasibility of the preparation method, but also further addresses the issues of efficiency and quality of the germanium dielectric layer deposition.

[0032] In another aspect, the present invention provides a method for using the aforementioned near-infrared to mid-infrared cross-band adjustable selective absorber, comprising: Step (1) thermally inducing a phase change of vanadium dioxide, changing the impedance matching between the germanium, vanadium dioxide and sapphire layers, changing the effective dielectric cavity thickness of the adjustable Fabry-Perot resonator, and achieving a blue shift of the absorption peak; Step (2) changes the thickness of the germanium dielectric layer to achieve a red shift of the absorption peak.

[0033] Specifically, in step (1), during the temperature increase process of the thermally induced vanadium dioxide phase change, the absorption peak of the absorber undergoes a blue shift.

[0034] Specifically, in step (2), when the thickness of the germanium dielectric layer increases, the absorption peak of the absorber red-shifts.

[0035] Specifically, the absorption peak is adjusted between 2.6-8.1 μm by combining the vanadium dioxide phase change and the germanium dielectric layer thickness adjustment.

[0036] Based on further solving the technical problem of the present invention or solving multiple technical problems at the same time, in the technical solution provided in the third aspect of the present invention, the preferred solution includes: The first priority solution: combining vanadium dioxide phase transition with germanium dielectric layer thickness adjustment to achieve an absorption peak adjustment range of 2.6-8.1μm. This technical solution not only solves the limited range of a single adjustment method, but also further addresses the problem of adjusting the absorption peak over a wide range.

[0037] The second priority solution: clarifying that the absorption peak of the absorber undergoes a blue shift during the heating process of the thermally induced vanadium dioxide phase transition. This technical solution not only solves the problem of phase transition regulation direction, but also further solves the problem of phase transition regulation predictability.

[0038] The third priority solution: clarifying that as the thickness of the germanium dielectric layer increases, the absorber's absorption peak undergoes a red shift. This technical solution not only solves the problem of thickness adjustment direction, but also further solves the problem of thickness adjustment predictability.

[0039] On the other hand, the present invention provides an application of the above-mentioned near-infrared to mid-infrared cross-band adjustable selective absorber, which is used in a wide-spectrum adaptive optoelectronic device to achieve wavelength-selective absorption in the near-infrared to mid-infrared band.

[0040] Specifically, the optoelectronic device includes an infrared detector, a spectrum analyzer or a thermal radiation control device.

[0041] More specifically, the optoelectronic device achieves continuous programmable modulation of the absorption peak position by controlling the growth parameters of the germanium dielectric layer and the temperature of the vanadium dioxide thin film layer.

[0042] Compared with the prior art, the present invention has the following advantages: The present invention combines the vanadium dioxide phase change with the germanium dielectric layer thickness adjustment to achieve the adjustment of the absorption peak from 2.6μm to 8.1μm. The present invention can achieve continuous programmable modulation of the absorption peak position by precisely controlling the germanium thin film growth parameters, providing an important implementation path for the development of wide-spectrum adaptive optoelectronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 Schematic diagram of the device structure, where Ge is the germanium dielectric layer, i-VO2 is the vanadium dioxide layer before the phase change, and m-VO2 is the vanadium dioxide layer after the phase change.

[0044] Figure 2 Infrared reflectance spectra of a 100nm vanadium dioxide layer and a series of germanium dielectric layers with gradient thickness on a sapphire substrate.

[0045] Figure 3 is the shift of the absorption peak before and after the phase transition of vanadium dioxide corresponding to the germanium dielectric layer of different thicknesses.

[0046] Figure 4 is the wavelength of the device working peak corresponding to the germanium dielectric layer of different thicknesses. DETAILED DESCRIPTION

[0047] The present invention will be further described in detail below with reference to specific examples. The following examples are not intended to limit the present invention but are merely intended to illustrate the present invention. The experimental methods used in the following examples are generally based on conventional conditions unless otherwise specified. The materials and reagents used in the following examples are all commercially available unless otherwise specified.

[0048] The term "vanadium dioxide thin film layer" as used herein refers to a thin film structure formed of vanadium dioxide material. In this application, this thin film structure has a thickness of 80-120 nm and is prepared through atomic layer deposition and post-annealing. It is a key layer for achieving thermally induced phase transition and thus adjusting the absorption peak. For example, in Example 1, a 100 nm thick vanadium dioxide thin film layer was prepared using this process, and the phase transition achieved a blue shift in the absorption peak.

[0049] As used herein, the term "germanium dielectric layer" refers to a dielectric layer made of germanium with a thickness gradient. In this application, the thickness range is 300-1100 nm (preferably 400-1000 nm), deposited by electron beam evaporation. This thickness variation can achieve a red-shift in the absorption peak. For example, in Example 1, when the germanium dielectric layer thickness increases from 400 nm to 1000 nm in a 200 nm gradient, the absorption peak undergoes a significant red-shift.

[0050] The term "sapphire substrate," as used herein, serves as the base of the absorber, providing support for the entire structure. In this application's germanium, vanadium dioxide, and sapphire structure, the sapphire substrate is the lowest component. All thin film layers in Example 1 were fabricated on the sapphire substrate.

[0051] The term "thermally induced phase transition" as used herein refers to the transformation of vanadium dioxide from an insulating state to a metallic state (or vice versa) by changing temperature. In this application, the temperature increase causes vanadium dioxide to transform from an insulating state to a metallic state, resulting in a blue shift in the absorption peak. For example, in Example 1, the absorption peak shifted from 3.4 μm to 2.6 μm after the temperature increase.

[0052] The term "blue shift of the absorption peak" as used herein refers to a shift in the wavelength corresponding to the absorption peak toward shorter wavelengths. In this application, thermally induced phase transitions (heating) of vanadium dioxide can cause a blue shift in the absorption peak. For example, in Example 1, devices with different germanium dielectric layer thicknesses all exhibited a blue shift in the absorption peak upon heating. The device with a 400nm germanium dielectric layer exhibited a blue shift of 0.8μm.

[0053] As used herein, the term "absorption peak redshift" refers to a shift in wavelength corresponding to the absorption peak toward longer wavelengths. In this application, increasing the thickness of the germanium dielectric layer causes the absorption peak to redshift. For example, in Example 1, when the thickness of the germanium dielectric layer increases from 400 nm to 1000 nm, the absorption peak redshifts from 2.6 μm to 5.8 μm.

[0054] Basic Example Atomic layer deposition process: During thin film deposition, the substrate was placed on a substrate holder within the ALD chamber. The chamber temperature was set to 425 K, the carrier gas flow rate was 80 sccm, and the chamber pressure was maintained at 4 hPa. Vanadyl triisopropoxide was used as the vanadium precursor, and deionized water was used as the oxygen precursor. The ion pulse times for the organometallic compound, oxygen, and water were set to 1.6 s, 0.1 s, and 18 s, respectively. The purge times were set to 7 s, 6 s, and 20 s. ALD cycles were repeated 600 times.

[0055] Post-annealing process: After film deposition, the substrate with the vanadium oxide film is placed in a tube furnace and annealed using argon as an inert gas at a temperature of 775-825 K for 2-6 hours.

[0056] Electron beam evaporation: The vacuum degree is 3*10 -6 Torr, evaporation rate 2 Å / s, substrate temperature 30 ℃, evaporation distance 50 cm, evaporation time 2000s-5000 s, electron gun voltage 6-8 kV, current 0.6-0.8 A.

[0057] In this invention, the core performance of the product (such as the adjustable absorption peak range of 2.6-8.1μm, the blueshift effect caused by thermally induced phase transitions, and the redshift effect caused by changes in germanium layer thickness) is determined by its structural design (the layered structure of germanium, vanadium dioxide, and sapphire) and material properties (the phase transition characteristics of vanadium dioxide and the dielectric properties of germanium). The preparation process is merely a means to achieve this structure and material layer. As long as the basic requirements such as thickness and uniformity of each layer are met, any adjustment of specific process parameters within a reasonable range will not affect the product's core adjustment capabilities and performance.

[0058] Example 1 like Figure 1 As shown, the present invention provides a cross-band adjustable selective absorber from near-infrared to mid-infrared. By doping a vanadium dioxide film into a Fabry-Perot resonator, the thickness of the effective dielectric cavity of the adjustable Fabry-Perot resonator is adjusted by thermally inducing a phase change of the intermediate vanadium oxide layer, thereby achieving dynamic control of multi-peak infrared light.

[0059] Wavelength-selective absorption with dynamic modulation capability is achieved in the germanium, vanadium dioxide and sapphire structure. By adjusting the thickness of the germanium layer, selective absorption of the absorption peak in the near-infrared to mid-wave infrared wavelength range is further achieved.

[0060] The purpose of the present invention is achieved through the following technical solutions: Figure 2As shown in the figure, a 100nm thick vanadium dioxide film was deposited on a sapphire-based device using atomic layer deposition and post-annealing. The atomic layer deposition process used deionized water, oxygen plasma, and vanadium isopropoxide as precursors. Subsequently, a series of germanium films with gradient thicknesses (400nm, 600nm, 800nm, and 1000nm) were deposited on the vanadium dioxide film using electron beam evaporation at a rate of 2Å / s.

[0061] The temperature-dependent reflectance spectra of devices with different thicknesses of germanium dielectric layers were obtained using a micro-infrared imaging spectrometer. The measurement results are shown in Table 1 and Figure 2 As shown: Table 1

[0062] from Figure 2 It can be seen that for devices with a germanium dielectric layer thickness of 400nm, as vanadium dioxide transforms from an insulating state to a metallic state (temperature increase process), the absorption peak of the device undergoes a significant blue shift, moving from 3.4μm to 2.6μm. As the germanium dielectric layer thickness increases by a gradient of 200nm ( Figure 2 In the device, the thickness of the germanium dielectric layer is 400 / 600 / 800 / 1000nm respectively. The offset of the corresponding absorption peak before and after the phase transition of the device also increases (e.g. Figure 3 As shown in the figure, the corresponding absorption peak shifts are 0.8μm, 1.3μm, 2.0μm and 2.3μm respectively. As the germanium thickness increases, the corresponding working peaks show a significant red shift phenomenon (corresponding to Figure 4 The working peak (green, blue, yellow, and red curves) shifts from 2.6 μm to 5.8 μm.

[0063] By combining the vanadium dioxide phase transition with the germanium dielectric layer thickness adjustment, the absorption peak can be adjusted from 2.6μm to 8.1μm. By precisely controlling the germanium film growth parameters, the absorption peak position can be continuously and programmably modulated, providing an important path for the development of broadband adaptive optoelectronic devices.

[0064] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A near-infrared to mid-infrared cross-band adjustable selective absorber, characterized in that: The invention is composed of a germanium dielectric layer, a vanadium dioxide thin film layer and a sapphire substrate arranged in sequence from top to bottom, forming an adjustable Fabry-Perot resonator of germanium, vanadium dioxide and sapphire structure.

2. The near-infrared to mid-infrared cross-band adjustable selective absorber according to claim 1, characterized in that: The thickness of the vanadium dioxide film layer is 80-120 nm.

3. The near-infrared to mid-infrared cross-band adjustable selective absorber according to claim 2, characterized in that: The vanadium dioxide thin film layer is prepared by an atomic layer deposition process and a post-annealing process.

4. The near-infrared to mid-infrared cross-band adjustable selective absorber according to claim 1, characterized in that: The germanium dielectric layer has a thickness gradient, and the thickness of the germanium dielectric layer ranges from 300 nm to 1100 nm.

5. The near-infrared to mid-infrared cross-band adjustable selective absorber according to claim 4, characterized in that: The thickness of the germanium dielectric layer is in the range of 400-1000 nm.

6. The near-infrared to mid-infrared cross-band adjustable selective absorber according to claim 4, characterized in that: The thickness gradient of the germanium dielectric layer is 1-250 nm.

7. The method for preparing the near-infrared to mid-infrared cross-band adjustable selective absorber according to any one of claims 1 to 6, characterized in that: include: S1: Preparation of vanadium dioxide thin film on sapphire substrate by atomic layer deposition and post-annealing process; S2: Depositing a germanium dielectric layer with a gradient thickness on the vanadium dioxide film by electron beam evaporation process.

8. The preparation method according to claim 7, characterized in that In S1, the atomic layer deposition process uses deionized water, oxygen plasma and vanadium isopropoxide as precursors.

9. The preparation method according to claim 8, characterized in that In S2, the electron beam evaporation rate is 1.5-2.5 Å / s.

10. The method for using the near-infrared to mid-infrared cross-band adjustable selective absorber according to any one of claims 1 to 6, characterized in that: include: Step (1) thermally inducing a phase change of vanadium dioxide to change the impedance matching between the germanium, vanadium dioxide and sapphire layers, thereby changing the effective dielectric cavity thickness of the adjustable Fabry-Perot resonator to achieve a blue shift of the absorption peak; Step (2) changes the thickness of the germanium dielectric layer to achieve a red shift of the absorption peak.

11. The method of use according to claim 10, characterized in that: In step (1), during the temperature increase process of the thermally induced vanadium dioxide phase change, the absorption peak of the absorber undergoes a blue shift.

12. The method of use according to claim 10, characterized in that: In step (2), when the thickness of the germanium dielectric layer increases, the absorption peak of the absorber red-shifts.

13. The method of use according to claim 10, characterized in that: By combining the phase change of vanadium dioxide and the thickness adjustment of the germanium dielectric layer, the absorption peak can be adjusted between 2.6-8.1μm.

14. Use of the absorber according to any one of claims 1 to 6, characterized in that: The absorber is used in a broadband adaptive optoelectronic device.

15. The use according to claim 14, characterized in that The photoelectric device includes an infrared detector, a spectrum analyzer or a thermal radiation control device.

16. The use according to claim 15, characterized in that The photoelectric device realizes continuous programmable modulation of the absorption peak position by controlling the growth parameters of the germanium dielectric layer and the temperature of the vanadium dioxide thin film layer.

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