Wide-band antireflection film for infrared detector based on multilayer optical stack

Abstract

The application relates to the technical field of infrared detectors and discloses an infrared detector wide-band antireflection film based on a multilayer optical stack, which comprises the following specific steps: step one: first, the application wave band of the antireflection film is determined, the antireflection film material MgF2, Si and ZnSe are selected, and the base material is GaSb; step two: according to the Fresnel law and the related theory of light waves, the amplitude of reflected waves and transmitted waves and the change of reflection phase when the light waves pass through different interfaces are researched, the reflectivity characteristic matrix of the multilayer film is solved by using related formulas, and the refractive index and the absorption coefficient of the material are considered. By adopting the novel multilayer film design, the transmittance and the wave band response of the infrared detector are remarkably improved; the antireflection film is not only suitable for short and medium wave infrared detectors but also can be extended to other photoelectric devices, has wide application prospects and market potential, and through the technology, the performance of devices and equipment can be remarkably improved while the cost-effectiveness is maintained.

Description

Technical Field

[0001] The present invention relates to the technical field of infrared detectors, and in particular to a wide-band anti-reflection film for infrared detectors based on a multi-layer optical stack. Background Art

[0002] Among modern optoelectronic devices, infrared detectors have important market value due to their wide application in fields such as night vision, weather monitoring, and medical diagnosis. These applications place higher demands on the performance of detectors, especially in terms of optical transmittance and detection wavelength range. Currently, the anti-reflection coating technology used in most infrared detectors is still limited to a single layer or a few layers of film, which limits its light transmission efficiency and sensitivity over a wide band. Therefore, it is particularly important to develop an anti-reflection coating technology that can effectively expand the operating band and improve transmittance.

[0003] Research on this technical point shows that existing anti-reflection films mostly rely on traditional materials and designs, such as a single MgF2 or ZnSe film layer. These structures have obvious limitations in multi-band light transmission performance. The market demand for wide-band, high-efficiency light-transmitting films is increasing, prompting researchers to seek new solutions. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the present invention provides a wide-band anti-reflection film for infrared detectors based on a multi-layer optical stack to solve the problem.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: a wide-band antireflection film for infrared detectors based on a multi-layer optical stack, comprising the following specific steps:

[0006] Step 1: First determine the application band of the anti-reflection film, select the anti-reflection film material MgF2, Si, ZnSe, and the substrate material is GaSb;

[0007] Step 2: Based on Fresnel's law and related theories of light waves, study the amplitude of the reflected and transmitted waves and the change in the reflection phase when the light wave passes through different interfaces. Use relevant formulas to calculate the reflectivity characteristic matrix of the multilayer film. Considering the refractive index and absorption coefficient of the material, calculate the reflectivity and transmittance of the multilayer antireflection film.

[0008] Step 3: Use ethanol or acetone solvent to clean the GaSb substrate to ensure that there is no dust, grease or other contaminants on its surface;

[0009] Step 4: In the vacuum evaporation equipment, deposit each layer of material in the following order and thickness:

[0010] First layer: high-purity MgF2, thickness of 255.7nm;

[0011] Second layer: high-purity Si, thickness 13.1nm;

[0012] The third layer: high-purity ZnSe, thickness of 80.39nm;

[0013] The fourth layer: high-purity MgF2, thickness of 107.5nm;

[0014] The fifth layer: high-purity Si, thickness of 15.73nm;

[0015] The sixth layer: high-purity ZnSe, thickness of 35.78nm;

[0016] The seventh layer: high-purity MgF2, thickness of 14.54nm;

[0017] The eighth layer: high-purity Si, thickness of 85.01nm;

[0018] The deposition thickness and rate of each layer are computer controlled to ensure precise deposition;

[0019] Step 5: After each layer is deposited, the surface and optical properties are tested to ensure that each layer of material meets the design specifications. The transmittance and reflectance curves of the GaSb substrate coated with the anti-reflection film in the 800-3000nm band are tested and analyzed, and the performance is compared with that of the substrate without anti-reflection film to evaluate the effectiveness of the anti-reflection film.

[0020] Preferably, the antireflection film is applied to the wavelength range of 800 to 3000 nm, and the arrangement order of the materials in the antireflection film is a specific multilayer structure.

[0021] Preferably, the antireflection film has an 8-layer structure, and the interference of light waves is controlled by optimizing the design of the multi-layer film structure to reduce reflection loss.

[0022] Preferably, the characteristic matrix of the reflectivity of the multilayer film is:

[0023]

[0024] Where: k is the number of film layers, δ j is the phase angle, η j is the equivalent refractive index.

[0025] Preferably, the reflectivity and transmittance of the multilayer antireflection film are:

[0026] R=(eta0B-C) / (eta0B+C)(eta0B-C) / (eta0B+C) *

[0027] T=(1-R)ψ

[0028] In the formula: ψ=Re(η s)Y * / Re(Y)BC * , where R is the reflectivity and T is the refractive index.

[0029] The present invention provides a wide-band antireflection film for infrared detectors based on a multi-layer optical stack. It has the following beneficial effects:

[0030] 1. The present invention significantly improves the transmittance and band response of infrared detectors by adopting a new multi-layer film design. This anti-reflection film is not only suitable for short- and medium-wave infrared detectors, but can also be extended to other optoelectronic devices. It has broad application prospects and market potential. Through this technology, the performance of devices and equipment can be significantly improved while maintaining cost-effectiveness.

[0031] 2. The present invention improves and optimizes these key performance parameters, significantly increasing the sensitivity of the detector. The detector can more keenly capture weak light signals, enabling it to operate over a wider wavelength range. Accuracy is also significantly improved, effectively reducing the probability of misjudgment and error, ensuring the accuracy and reliability of detection results, and improving sensitivity and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of the film structure of a wide-band multilayer anti-reflection film for an infrared detector based on a multilayer optical stack according to the present invention;

[0033] Figure 2 This is a transmittance curve diagram of a GaSb substrate of a wide-band antireflection film for an infrared detector based on a multi-layer optical stack according to the present invention in the wavelength range of 800 to 3000 nm when the present invention is not used;

[0034] Figure 3 The GaSb substrate of the infrared detector wide-band antireflection film based on the multi-layer optical stack of the present invention is not used Figure 1 The reflectivity curve of the multi-layer antireflection film structure in the 800-3000nm band is shown;

[0035] Figure 4 The present invention is a kind of infrared detector wide band antireflection film based on multi-layer optical stack Figure 1 The transmittance curve of the multilayer antireflection film structure shown is in the 800-3000nm band when applied to a GaSb-based optoelectronic device;

[0036] Figure 5 The present invention is a kind of infrared detector wide band antireflection film based on multi-layer optical stack Figure 1 The reflectivity curve of the multilayer antireflection film structure shown is in the 800-3000nm band when applied to a GaSb-based optoelectronic device. DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] Example:

[0039] Please see the attached Figure 1 -Attached Figure 5 The embodiment of the present invention provides a wide-band antireflection film for infrared detectors based on a multi-layer optical stack, comprising the following specific steps:

[0040] Step 1: First determine the application band of the anti-reflection film, select the anti-reflection film material MgF2, Si, ZnSe, and the substrate material is GaSb;

[0041] Step 2: Based on Fresnel's law and related theories of light waves, study the amplitude of the reflected and transmitted waves and the change in the reflection phase when the light wave passes through different interfaces. Use relevant formulas to calculate the reflectivity characteristic matrix of the multilayer film. Considering the refractive index and absorption coefficient of the material, calculate the reflectivity and transmittance of the multilayer antireflection film.

[0042] Step 3: Use ethanol or acetone solvent to clean the GaSb substrate to ensure that there is no dust, grease or other contaminants on its surface;

[0043] Step 4: In the vacuum evaporation equipment, deposit each layer of material in the following order and thickness:

[0044] First layer: high-purity MgF2, thickness of 255.7nm;

[0045] Second layer: high-purity Si, thickness 13.1nm;

[0046] The third layer: high-purity ZnSe, thickness of 80.39nm;

[0047] The fourth layer: high-purity MgF2, thickness of 107.5nm;

[0048] The fifth layer: high-purity Si, thickness of 15.73nm;

[0049] The sixth layer: high-purity ZnSe, thickness of 35.78nm;

[0050] The seventh layer: high-purity MgF2, thickness of 14.54nm;

[0051] The eighth layer: high-purity Si, thickness of 85.01nm;

[0052] The deposition thickness and rate of each layer are controlled by computer to ensure accurate deposition;

[0053] Step five: after each layer is deposited, the surface and optical properties are detected to ensure that each layer of material meets the design specifications, the transmittance and reflectance curves of the GaSb substrate coated with the antireflection film in the 800-3000 nm wavelength range are tested and analyzed, and the performance of the substrate without the antireflection film is compared to evaluate the effect of the antireflection film.

[0054] The arrangement order of each material in the antireflection film applied in the 800-3000 nm wavelength range antireflection film is a specific multilayer structure.

[0055] The antireflection film is an 8-layer structure, and the interference of light waves is controlled through the optimization design of the multilayer film structure to reduce reflection loss.

[0056] The characteristic matrix of the reflectivity of the multilayer film is:

[0057]

[0058] In the formula, k is the number of film layers, δ j is the phase angle, η j is the equivalent refractive index.

[0059] The reflectivity and transmittance of the multilayer antireflection film are:

[0060] R = (η0B-C) / (η0B+C) (η0B-C) / (η0B+C) *

[0061] T = (1-R)ψ

[0062] In the formula, ψ = Re(η s )Y * / Re(Y)BC * , where R is the reflectivity and T is the refractive index.

[0063] The following will be described in conjunction with specific examples:

[0064] Example one:

[0065] According to the above preparation method, an infrared detector wide-band antireflection film based on a multilayer optical stack is prepared. The performance of the prepared antireflection film is tested, and the transmittance and reflectance curves in the 2000 nm wavelength range are obtained. The results show that the highest transmittance is 99.7%, the average transmittance is as high as 98.18%, the lowest reflectance is 0.2% at 2550 nm, and the average reflectance is reduced to 1.66%.

[0066] Example two:

[0067] The prepared wide-band antireflection coating for infrared detectors based on a multilayer optical stack was applied to an actual infrared detector, and its performance was compared with that of a detector without the coating. The detector without the coating had an average transmittance of only 24% in the 3000nm band, with a maximum of no more than 36%. In contrast, the detector with the coating achieved an average transmittance exceeding 98% in the same band, with a maximum approaching 100%. Furthermore, the use of the coating significantly improved the detector's optical response, demonstrating the significant advantages of the present invention in practical applications.

[0068] like Figure 2 As shown in FIG. 1 , the average transmittance of the infrared detector substrate without antireflection film is only 24%, and the highest is only 36%.

[0069] like Figure 3 As shown, the average reflectivity of the infrared detector substrate without anti-reflection film is 40%, and the highest is close to 60%.

[0070] like Figure 4 As shown, when the present invention is applied to optoelectronic devices, the highest transmittance is 99.7%, the average transmittance is as high as 98.18%, and the maximum transmittance is close to 100%, indicating that there is almost no loss of incident light in a specific wavelength band.

[0071] like Figure 5 As shown, when the present invention is applied to optoelectronic devices, the minimum reflectivity is 0.2% at 2550nm, the average reflectivity is reduced to 1.66%, and the minimum reflectivity is close to 0%, effectively reducing light energy loss. This shows that there is almost no loss of incident light in a specific wavelength band.

[0072] The anti-reflection coating design optimizes optical performance in the short- to mid-wave infrared bands, proposing a multi-layer structure to significantly improve the light transmittance and reflectance of infrared detectors. As can be seen from the provided graph, it is expected to greatly enhance the optical performance of infrared detectors in the 800 to 3000 nanometer band. The anti-reflection coating has a minimum reflectivity of 0.2% at 2550nm, a maximum transmittance of 99.7%, an average transmittance of 98.18%, and a maximum transmittance of nearly 100%, indicating that there is almost no loss of incident light in this specific wavelength band; the average reflectivity is reduced to 1.66%, and the minimum reflectivity is close to 0%, effectively reducing light energy loss. In comparison, the average transmittance of the infrared detector substrate without anti-reflection coating is only 24%, with a maximum of only 36%, while the average reflectivity is 40%, with a maximum of nearly 60%.

[0073] Reflectivity without AR coating: In contrast, the substrate without AR coating shows a periodic reflectivity variation of up to 60% between 800 and 1200 nm, indicating significant loss of incident light without AR coating. Transmission without AR coating: The substrate without AR coating shows significant instability in transmittance, with transmittance dropping below 15% at certain wavelengths, indicating that light suffers severe attenuation without AR coating.

[0074] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a wide-band antireflection film for an infrared detector based on a multi-layer optical stack, characterized in that: The specific steps include: Step 1: First determine the application band of the anti-reflection film, select the anti-reflection film material MgF2, Si, ZnSe, and the substrate material is GaSb; Step 2: Based on Fresnel's law and light wave theory, study the amplitude of the reflected and transmitted waves and the change in the reflection phase when the light wave passes through different interfaces, calculate the reflectivity characteristic matrix of the multilayer film, and consider the refractive index and absorption coefficient of the material to calculate the reflectivity and transmittance of the multilayer antireflection film; Step 3: Use ethanol or acetone solvent to clean the GaSb substrate to ensure that there is no dust, grease or other contaminants on its surface; Step 4: In the vacuum evaporation equipment, deposit each layer of material in the following order and thickness: First layer: MgF2, thickness 255.7nm; Second layer: Si, thickness 13.1nm; The third layer: ZnSe, thickness is 80.39nm; Fourth layer: MgF2, thickness 107.5nm; Fifth layer: Si, thickness 15.73nm; The sixth layer: ZnSe, thickness is 35.78nm; The seventh layer: MgF2, thickness is 14.54nm; The eighth layer: Si, thickness is 85.01nm; The deposition thickness and rate of each layer are computer controlled to ensure precise deposition; Step 5: After each layer is deposited, the surface and optical properties are tested to ensure that each layer of material meets the design specifications. The transmittance and reflectance curves of the GaSb substrate coated with the anti-reflection film in the 800-3000nm band are tested and analyzed, and the performance is compared with that of the substrate without anti-reflection film to evaluate the effect of the anti-reflection film.

2. The infrared detector wide-band antireflection film based on a multi-layer optical stack according to claim 1, characterized in that: The antireflection film is applied to the wavelength range of 800-3000 nm. The arrangement order of the materials in the antireflection film is a specific multilayer structure.

3. The infrared detector wide-band antireflection film based on a multi-layer optical stack according to claim 1, characterized in that: The antireflection film has an 8-layer structure, and the interference of light waves is controlled by optimizing the design of the multi-layer film structure to reduce reflection loss.

4. The infrared detector wide-band antireflection film based on a multi-layer optical stack according to claim 1, characterized in that: The characteristic matrix of the reflectivity of the multilayer film is: Where: k is the number of film layers, is the phase angle, is the equivalent refractive index.

5. The infrared detector wide-band antireflection film based on a multi-layer optical stack according to claim 4, characterized in that: The reflectivity and transmittance of the multilayer antireflection film are: Where: , where R is the reflectivity and T is the refractive index.

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