Optical superlens suitable for extreme environments and method of making the same

Abstract

The present application relates to an optical superlens suitable for extreme environment and a preparation method thereof, the optical superlens comprises a superlens structure layer in the center, and a moth-eye film structure layer, an optical substrate and an optical composite film symmetrically arranged on both sides of the superlens structure layer, the superlens structure layer, the moth-eye film structure layer and the optical substrate are each independently composed of a wide-bandgap semiconductor material with a thermal conductivity of 50 W / mK or more, at least one structural parameter of the moth-eye film structure layer is modulated along the thickness direction of the optical substrate to complete the refractive index transition of the superlens structure layer to the optical substrate. The present application solves the problem of efficiency reduction caused by refractive index mismatch, and enables the optical superlens to work normally under extreme conditions such as high temperature or high power.

Description

Technical Field

[0001] This invention relates to the technical field of optical elements, and in particular to an optical superlens suitable for extreme environments and its fabrication method. Background Technology

[0002] Optical superlenses are lenses used to focus the entire visible light spectrum. They can precisely control the phase of light, allowing light to be focused or defocused within a very thin structure, and even achieving a negative refractive index effect under certain conditions. The design of optical superlenses must consider the phase changes of light waves, which often depend on the microstructure of optical materials. Traditional lens designs are based on large-scale optical components, while optical superlenses require micrometer- or even nanometer-scale fine structures, posing significant challenges to computation and manufacturing. For example, in the field of optical superlenses, to meet the needs of phase modulation, the structure in the optical superlens needs to have a high refractive index, such as TiO2 or Si3N4. These materials are often amorphous or polycrystalline thin film materials, and due to their high cost and mechanical brittleness, they cannot be directly fabricated into independent self-supporting wafers. Therefore, the material structure commonly used in optical superlenses is a high-refractive-index dielectric thin film grown on quartz glass to achieve phase modulation.

[0003] Due to its low thermal conductivity and laser damage threshold, quartz glass frequently faces the problem of optical superlens failure in high-temperature or high-power laser applications. This problem is mainly caused by the refractive index mismatch between the high-refractive-index optical superlens structure and the interfaces between the upper and lower surfaces, the quartz glass substrate, and the air. Once this refractive index mismatch occurs, Fresnel reflections will occur at the interfaces. These reflections significantly reduce the transmittance of the optical superlens, thus leading to a decrease in its efficiency. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the first objective of the present invention is to provide an optical superlens suitable for extreme environments, which solves the problem of reduced efficiency caused by refractive index mismatch and enables the optical superlens to work normally under extreme conditions such as high temperature or high power.

[0005] The second objective of this invention is to provide a method for fabricating an optical superlens suitable for extreme environments, which has the advantages of simple fabrication, low cost, and high yield.

[0006] To achieve the first objective mentioned above, the present invention provides the following technical solution:

[0007] An optical superlens suitable for extreme environments includes a central superlens structure layer, and moth-eye film structure layers, an optical substrate, and an optical composite film symmetrically arranged on both sides of the superlens structure layer. The superlens structure layer, the moth-eye film structure layer, and the optical substrate are each independently composed of a wide bandgap semiconductor material with a thermal conductivity of 50 W / m·K or higher. At least one structural parameter of the moth-eye film structure layer along the thickness direction of the optical substrate is modulated to complete the refractive index transition from the superlens structure layer to the optical substrate.

[0008] Furthermore, the superlens structure layer includes multiple nanopillars arranged in a one-dimensional or two-dimensional array;

[0009] And / or, the nanopillars are mirror-symmetric in a central plane parallel to the length direction of the optical substrate;

[0010] And / or, the plurality of nanopillars have the same height and period, and the duty cycle increases along at least two array directions, wherein the at least two array directions (+X, -X, +Y, -Y) are array directions that are opposite, intersecting and / or perpendicular.

[0011] Furthermore, the wide bandgap semiconductor material of the nanopillars is one or a combination of diamond, silicon carbide and gallium nitride with a bandgap exceeding 2 eV;

[0012] And / or, the cross-section of the nanopillar is circular, elliptical, or polygonal;

[0013] And / or, the height of the nanopillars is 200~1500 nm;

[0014] And / or, the period of the nanopillars is 250~900nm;

[0015] And / or, the duty cycle of the nanopillars ranges from 20% to 90%.

[0016] Furthermore, the moth-eye membrane structure layer is composed of multiple frustum columns arranged in a two-dimensional array;

[0017] And / or, the frustum is mirror-symmetrical on a central plane parallel to the thickness direction of the optical substrate;

[0018] And / or, the plurality of frustums have the same height and period, and their diameter increases in the direction from the nanopillars to the optical substrate.

[0019] Furthermore, the wide bandgap semiconductor material of the frustum column is one or a combination of diamond, silicon carbide and gallium nitride with a bandgap exceeding 2 eV;

[0020] And / or, the height of the frustum is 100~800nm;

[0021] And / or, the period of the frustum column is 100~600nm;

[0022] And / or, the diameter of the frustum is in the range of 30~550 nm.

[0023] Furthermore, the optical substrate and the moth-eye membrane structure layer are integrally formed;

[0024] And / or, the wide bandgap semiconductor material of the optical substrate is one or a combination of diamond, silicon carbide and gallium nitride with a bandgap width exceeding 2 eV;

[0025] And / or, the thickness of the optical substrate is 100~5000μm.

[0026] Furthermore, the optical composite film is composed of alternating layers of several low-refractive-index film layers with a refractive index not exceeding 1.7 and high-refractive-index film layers with a refractive index exceeding 2.1;

[0027] And / or, the low refractive index film is a composite film of one or more of silicon oxide and aluminum oxide;

[0028] And / or, the high refractive index film is a composite film of one or more of titanium oxide and hafnium oxide;

[0029] And / or, the thickness of the optical composite film is 0.5~50.0 μm.

[0030] To achieve the second objective mentioned above, the present invention provides the following technical solution:

[0031] A method for fabricating an optical superlens suitable for extreme environments includes the following steps:

[0032] S1 is patterned on one side of the surface of the optical substrate to obtain the moth eye membrane structure layer;

[0033] S2 directly bonds a wide bandgap semiconductor material onto the moth-eye membrane structure layer obtained in S1, then thins it to the predetermined height of the superlens structure layer, and then performs patterning processing to obtain the superlens structure layer.

[0034] S3 is directly bonded to the superlens structure layer obtained in S2 and the moth eye membrane structure layer obtained in S1;

[0035] S4 deposits a thin film on the other side surface of the pair of optical substrates obtained in S3 to obtain an optical composite film.

[0036] Furthermore, in S1, the equivalent refractive index distribution curve of the optical superlens structure formed by multiple nanopillars is obtained in advance, the range of refractive index change from the optical superlens structure to the optical substrate in the optical superlens plane is determined, and then the structural parameters of the moth eye membrane structure are determined by the transition from the equivalent refractive index of the optical superlens to the refractive index of the optical substrate.

[0037] Further, in S1, the optical substrate is first exposed and developed on one side surface, then a chromium mask is deposited, and the chromium mask in the non-patterned area is stripped off. Then the optical substrate in the non-patterned area is etched to obtain the moth-eye film structure layer. The exposure dose and development time are controlled to obtain a complete patterned area, and the thickness of the chromium mask is controlled to enable successful stripping.

[0038] Furthermore, in step S2, the bonding pressure and temperature are controlled to ensure that the coefficients of thermal expansion do not mismatch, and the amount of thinning is controlled to ensure uniform thickness within the plane. The patterning step includes spin coating, exposure, development, and pattern transfer.

[0039] Furthermore, in S3, the bonding pressure is controlled to ensure sufficient bonding strength and structural integrity.

[0040] Furthermore, in S4, the deposition time of each material in the thin film deposition is controlled to ensure the accuracy of the thickness.

[0041] In summary, the beneficial technical effects of the present invention are as follows:

[0042] 1. This invention proposes growing a moth-eye film structure on a wide-bandgap semiconductor substrate such as silicon carbide or diamond, then fabricating a thin layer of wide-bandgap semiconductor material on top, processing an optical superlens structure on the thin layer, and finally bonding it to a substrate also having a moth-eye film structure to achieve a sandwich structure. The so-called moth-eye film structure mimics the special microstructure of a moth's eye surface. According to the equivalent medium theory, the refractive index of this structure is equivalent to that of a graded multilayer film, avoiding the difficulties in fabricating multilayer films and the low durability of such films. Therefore, it can serve as a refractive index transition layer between the substrate and the optical superlens structure, and the same applies to the relationship between the optical superlens structure and air. This invention effectively solves the efficiency reduction problem caused by refractive index mismatch in traditional optical superlenses, and replaces the substrate material of the optical superlens, enabling the optical superlens to operate normally under extreme conditions such as high temperature or high power.

[0043] 2. To achieve 2π phase modulation, the nanopillars in optical superlenses often have high refractive indices, leading to strong interfacial reflections between them and both the air and the substrate, resulting in reduced propagation efficiency. This invention, without altering the phase distribution design of the optical superlens, adds a layer of microstructure on each side to increase the transmittance at the interfaces between the nanopillars and the air and substrate, further improving the efficiency of the optical superlens. Simultaneously, the substrate and the optical superlens nanopillars are made of wide-bandgap semiconductor materials (silicon carbide, diamond, etc.), giving the optical superlens stronger thermal stability and high-power resistance. For optical superlenses, this method significantly improves propagation efficiency without affecting the design of the optical superlens itself, improving light energy utilization and stability in practical applications.

[0044] 3. This invention can effectively improve the low efficiency of traditional optical superlenses caused by refractive index mismatch. Using the method of this patent, the stability of high-efficiency optical superlenses can be improved in extreme environments. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the structure of the optical superlens of Embodiment 1 of the present invention.

[0046] Figure 2 This is a flowchart of the method provided in Embodiment 6 of the present invention.

[0047] Figure 3 This is the equivalent refractive index distribution curve of Embodiment 7 of the present invention.

[0048] Figure 4 This is the transmittance curve of Embodiment 9 of the present invention.

[0049] In the figure, 1 is the superlens structure layer; 11 is the nanopillar; 2 is the moth-eye membrane structure layer; 21 is the frustum column; 3 is the optical substrate; and 4 is the optical composite film. Detailed Implementation

[0050] To make the technical means, creative features, objectives and effects of this invention clearer and easier to understand, the invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0051] Example 1: Refer to Figure 1This invention discloses an optical superlens suitable for extreme environments, comprising a central superlens structure layer 1, and symmetrically arranged on both sides of the superlens structure layer 1: a moth-eye film structure layer 2, an optical substrate 3, and an optical composite film 4. Each of the superlens structure layer 1, the moth-eye film structure layer 2, and the optical substrate 3 is independently composed of a wide bandgap semiconductor material with a thermal conductivity of 50 W / m·K or higher. At least one structural parameter of the moth-eye film structure layer 2 along the thickness direction of the optical substrate 3 is modulated to complete the refractive index transition from the superlens structure layer 1 to the optical substrate 3.

[0052] Example 2: This invention discloses an optical superlens suitable for extreme environments. The difference from Example 1 is that, firstly, the superlens structure layer 1 includes multiple nanopillars 11 arranged in a two-dimensional array along two mutually perpendicular directions (X, Y). The nanopillars 11 are mirror-symmetrical on a central plane parallel to the length direction of the optical substrate 3. These nanopillars 11 have the same height and period, and their duty cycle increases along the two array directions (+X, -X). Specifically, the wide bandgap semiconductor material of the nanopillars 11 is diamond, with a circular cross-section, a height of 1000 nm, a period of 400 nm, and a duty cycle ranging from 20% to 70%.

[0053] Secondly, the moth-eye membrane structure layer 2 consists of multiple frustum pillars 21 arranged in a two-dimensional array along two mutually perpendicular directions (X, Y). The frustum pillars 21 are mirror-symmetrical on a central plane parallel to the thickness direction of the optical substrate 3. These frustum pillars 21 have the same height and period, and their diameter increases from the nano-dielectric pillars to the optical substrate 3. Specifically, the frustum pillars 21 are made of diamond, have a height of 150 nm, a period of 250 nm, and a diameter ranging from 50 to 210 nm.

[0054] Furthermore, the optical substrate 3 and the moth-eye membrane structure layer 2 are integrally formed. The optical substrate 3 is made of diamond and has a thickness of 400μm.

[0055] Finally, the antireflective coating is composed of several alternating layers of low-refractive-index films (alumina films) and high-refractive-index films (titanium oxide films). The thickness of the antireflective coating is 0.850 μm. Starting from the air interface, the first layer is silicon oxide, the second layer is titanium oxide, and they are stacked sequentially with thicknesses of 181.8 nm, 125.7 nm, 13.4 nm, 90.9 nm, 18.8 nm, 102.7 nm, 98.9 nm, 84.6 nm, 48.3 nm, and 86.6 nm, respectively, achieving high transmittance in the near-infrared band of 1000~1550 nm.

[0056] Example 3: This invention discloses an optical superlens suitable for extreme environments. The difference from Example 1 is that, firstly, the superlens structure layer 1 includes multiple nanopillars 11 arranged in a two-dimensional array along two mutually perpendicular directions (X, Y). The nanopillars 11 are mirror-symmetrical on a central plane parallel to the length direction of the optical substrate 3. These nanopillars 11 have the same height and period, and their duty cycle increases along the two array directions (+X, -X). Specifically, the wide bandgap semiconductor material of the nanopillars 11 is diamond, with a circular cross-section, a height of 200 nm, a period of 250 nm, and a duty cycle ranging from 20% to 40%.

[0057] Secondly, the moth-eye membrane structure layer 2 consists of multiple frustum pillars 21 arranged in a two-dimensional array along two mutually perpendicular directions (X, Y). The frustum pillars 21 are mirror-symmetrical on a central plane parallel to the thickness direction of the optical substrate 3. These frustum pillars 21 have the same height and period, and their diameter increases from the nano-dielectric pillars to the optical substrate 3. Specifically, the frustum pillars 21 are made of diamond, silicon carbide, and gallium nitride, with a height of 800 nm, a period of 600 nm, and a diameter ranging from 450 to 550 nm.

[0058] Furthermore, the optical substrate 3 and the moth-eye membrane structure layer 2 are integrally formed. The optical substrate 3 is made of diamond and has a thickness of 100μm.

[0059] Finally, the antireflective coating is composed of several alternating layers of low refractive index film (silicon oxide film) and high refractive index film (hafnium oxide film), with a thickness of 50.000 μm, achieving high transmittance in the near-infrared band of 1000~1550 nm.

[0060] Example 4: This invention discloses an optical superlens suitable for extreme environments. The difference from Example 1 is that, firstly, the superlens structure layer 1 includes multiple nanopillars 11 arranged in a two-dimensional array along two mutually perpendicular directions (X, Y). The nanopillars 11 are mirror-symmetrical on a central plane parallel to the length direction of the optical substrate 3. These nanopillars 11 have the same height and period, and their duty cycle increases along the two array directions (+X, -X). Specifically, the wide bandgap semiconductor material of the nanopillars 11 is silicon carbide, with a circular cross-section, a height of 1500 nm, a period of 900 nm, and a duty cycle ranging from 70% to 90%.

[0061] Secondly, the moth-eye membrane structure layer 2 consists of multiple frustum pillars 21 arranged in a two-dimensional array along two mutually perpendicular directions (X, Y). The frustum pillars 21 are mirror-symmetrical on a central plane parallel to the thickness direction of the optical substrate 3. These frustum pillars 21 have the same height and period, and their diameter increases from the nano-dielectric pillars to the optical substrate 3. Specifically, the frustum pillars 21 are made of gallium nitride, have a height of 100 nm, a period of 100 nm, and a diameter ranging from 30 to 100 nm.

[0062] Furthermore, the optical substrate 3 and the moth-eye membrane structure layer 2 are integrally formed. The optical substrate 3 is made of silicon carbide and has a thickness of 5000μm.

[0063] Finally, the antireflective coating is composed of several low-refractive-index layers (silicon oxide and aluminum oxide layers) and high-refractive-index layers (titanium oxide and hafnium oxide layers) stacked alternately, with a thickness of 0.500 μm, achieving high transmittance in the near-infrared band of 1000~1550 nm.

[0064] Example 5: This invention discloses an optical superlens suitable for extreme environments. The difference from Example 1 is that, firstly, the superlens structure layer 1 includes multiple nanopillars 11 arranged in a two-dimensional array along two mutually perpendicular directions (X, Y). The nanopillars 11 are mirror-symmetrical on a central plane parallel to the length direction of the optical substrate 3. These nanopillars 11 have the same height and period, and their duty cycle increases along the two array directions (+X, -X). Specifically, the wide bandgap semiconductor material of the nanopillars 11 is gallium nitride, with a circular cross-section, a height of 600 nm, a period of 750 nm, and a duty cycle ranging from 40% to 60%.

[0065] Secondly, the moth-eye membrane structure layer 2 consists of multiple frustum pillars 21 arranged in a two-dimensional array along two mutually perpendicular directions (X, Y). The frustum pillars 21 are mirror-symmetrical on a central plane parallel to the thickness direction of the optical substrate 3. These frustum pillars 21 have the same height and period, and their diameter increases from the nano-dielectric pillars to the optical substrate 3. Specifically, the frustum pillars 21 are made of silicon carbide, have a height of 500 nm, a period of 300 nm, and a diameter ranging from 250 to 400 nm.

[0066] Furthermore, the optical substrate 3 and the moth-eye membrane structure layer 2 are integrally formed. The optical substrate 3 is made of gallium nitride and has a thickness of 500 μm.

[0067] Finally, the antireflective coating is composed of several low-refractive-index layers (silicon oxide and aluminum oxide layers) and high-refractive-index layers (titanium oxide and hafnium oxide layers) stacked alternately, with a thickness of 0.800 μm, achieving high transmittance in the near-infrared band of 1000~1550 nm.

[0068] Example 6: Refer to Figure 2 This invention discloses a method for fabricating an optical superlens suitable for extreme environments, which differs from Example 1 in that it includes the following steps:

[0069] S1 patterns one side surface of the optical substrate 3 to obtain the moth eye membrane structure layer 2;

[0070] After directly bonding a wide bandgap semiconductor material to the moth-eye membrane structure layer 2 obtained in S1, S2 thins it to the predetermined height of the superlens structure layer 1 and then performs patterning to obtain the superlens structure layer 1.

[0071] S3 is directly bonded to the superlens structure layer 1 obtained in S2 and the moth eye membrane structure layer 2 obtained in S1.

[0072] In step S4, a thin film is deposited on the other side surface of the optical substrate 3 obtained in step S3 to obtain an optical composite film 4.

[0073] Example 7: This is a method for fabricating a high-focusing-efficiency optical superlens disclosed in this invention. The difference from Example 6 is that it includes the following steps:

[0074] In S1, in an electron beam evaporation coating equipment, the deposition parameters for two film materials, silicon oxide and titanium oxide, are set. At room temperature, the deposition rate of silicon oxide is 1.5 nm / s and the deposition rate of titanium oxide is 3 nm / s. The deposition time for each layer is set, and several silicon oxide film layers and titanium oxide film layers are deposited alternately to obtain an antireflection film.

[0075] S2 first exposes and develops the other side of the optical substrate 3, then deposits a metal mask, and peels off the metal mask in the unpatterned area. Then, it etches the optical substrate 3 in the unpatterned area to obtain the moth-eye film. The exposure dose is selected as 20 nA, the development time is 1 min, and a complete patterned area is obtained. The thickness of the metal mask is controlled to be less than 80 nm in order to successfully peel off the mask.

[0076] S3 first spin-coats photoresist (AZ1518) onto the moth-eye membrane, and then removes the photoresist above the surface of the moth-eye membrane by dry etching. Next, spin-coats photoresist (zep520) to the predetermined height of the nano-dielectric pillars, and then exposes and develops the photoresist surface. After depositing high-refractive-index material in the patterned area, the high-refractive-index material above the predetermined height of the nano-dielectric pillars is removed by dry etching to obtain multiple nano-dielectric pillars. The exposure dose is controlled at 10 nA, the development time is 1 min, the spin-coating speed of the photoresist is 200 rps / min, and the etching time of the photoresist is 10 min. In addition, the deposition is carried out at room temperature to ensure the integrity of the photoresist.

[0077] S4 controls the bonding pressure to a moderate value, ensuring bonding strength without damaging the material structure.

[0078] S5 removes the photoresist on the moth-eye membrane and nano-dielectric pillars obtained in S3 and S4 by wet stripping, controlling the wet stripping time using acetone solution to be within 1 hour, to obtain the optical superlens shown in Example 2.

[0079] Example 8: This invention discloses a method for fabricating a high-focusing-efficiency optical superlens. The difference from Example 7 is that in S4, photoresist (AZ1518) is first spin-coated onto the surface of the multiple nano-dielectric pillars and photoresist (zep520) obtained in S3 to a predetermined moth-eye film height. Then, the photoresist surface is exposed and developed. After material deposition in the patterned area, high-refractive-index material above the predetermined thickness of the optical substrate 3 is removed by dry etching to obtain another moth-eye film and optical substrate 3. Then, S1 is repeated. The exposure dose is controlled at 10 nA, the development time at 1 min, the photoresist spin-coating speed at 200 rps / min, and the photoresist etching time at 10 min. Deposition is performed at room temperature to ensure the integrity of the photoresist. Finally, the optical superlens shown in Example 3 is obtained.

[0080] Example 9: This is a method for fabricating a high-focusing-efficiency optical superlens disclosed in this invention. The difference from Example 6 is that in S2 and S4, reference is made to... Figure 3 The equivalent refractive index distribution curve of an optical superlens structure formed by multiple nano-dielectric pillars was obtained in advance to determine the range of refractive index variation from the optical superlens structure to the optical substrate 3 within the optical superlens plane. Then, by observing the transition from the equivalent refractive index of the optical superlens to the refractive index of the optical substrate 3, the structural parameters of the moth-eye membrane were determined, ultimately achieving enhanced transmittance. Without the equivalent refractive index transition, the transmittance of the optical superlens was [missing value]. Figure 4 The curve containing the hollow circle in the image shows that, after calculating and matching the equivalent refractive index, the transmittance of the optical superlens is... Figure 4 As can be seen from the curve containing the solid circle, the transmittance of the optical superlens is effectively improved, thereby increasing the focusing efficiency.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An optical superlens suitable for extreme environments, characterized in that: The system includes a superlens structure layer (1) located at the center, and a moth-eye membrane structure layer (2), an optical substrate (3), and an optical composite film (4) symmetrically arranged on both sides of the superlens structure layer (1). The superlens structure layer (1), the moth-eye membrane structure layer (2), and the optical substrate (3) are each independently composed of a wide bandgap semiconductor material with a thermal conductivity of 50 W / m·K or higher. At least one structural parameter of the moth-eye membrane structure layer (2) along the thickness direction of the optical substrate (3) is modulated to complete the refractive index transition from the superlens structure layer (1) to the optical substrate (3). The superlens structure layer (1) includes multiple nanopillars (11) arranged in a one-dimensional or two-dimensional array; The nanopillars (11) are mirror-symmetric on a central plane parallel to the length direction of the optical substrate (3); and / or, the plurality of nanopillars (11) have the same height and period, and the duty cycle increases along at least two array directions, which are array directions that are opposite, intersecting and / or perpendicular.

2. The optical superlens suitable for extreme environments according to claim 1, characterized in that: The wide bandgap semiconductor material of the nanopillar (11) is one or a combination of diamond, silicon carbide and gallium nitride with a bandgap width exceeding 2eV. And / or, the cross-section of the nanopillar (11) is circular, elliptical or polygonal; And / or, the height of the nanopillar (11) is 200~1500 nm; And / or, the period of the nanopillar (11) is 250~900nm; And / or, the duty cycle of the nanopillar (11) is in the range of 20 to 90%.

3. The optical superlens suitable for extreme environments according to claim 1, characterized in that: The moth-eye membrane structure layer (2) is composed of multiple frustum columns (21) arranged in a two-dimensional array; The frustum column (21) is mirror-symmetrical on a central plane parallel to the thickness direction of the optical substrate (3); And / or, the plurality of frustums (21) have the same height and period, and their diameters increase in the direction from the nanopillars (11) to the optical substrate (3).

4. The optical superlens suitable for extreme environments according to claim 3, characterized in that: The wide bandgap semiconductor material of the frustum column (21) is one or a combination of diamond, silicon carbide and gallium nitride with a bandgap width exceeding 2eV. And / or, the height of the frustum (21) is 100~800nm; And / or, the period of the frustum column (21) is 100~600nm; And / or, the diameter of the frustum (21) is in the range of 30~550 nm.

5. The optical superlens suitable for extreme environments according to claim 1, characterized in that: The optical substrate (3) and the moth-eye membrane structure layer (2) are integrally formed; And / or, the wide bandgap semiconductor material of the optical substrate (3) is one or a combination of diamond, silicon carbide and gallium nitride with a bandgap width exceeding 2eV; And / or, the thickness of the optical substrate (3) is 100~5000μm.

6. The optical superlens suitable for extreme environments according to claim 1, characterized in that: The optical composite film (4) is composed of several low refractive index film layers with a refractive index not exceeding 1.7 and high refractive index film layers with a refractive index exceeding 2.1, which are alternately stacked. The low refractive index film is a composite film of one or more of silicon oxide and aluminum oxide; And / or, the high refractive index film is a composite film of one or more of titanium oxide and hafnium oxide; And / or, the thickness of the optical composite film (4) is 0.5~50.0 μm.

7. A method for fabricating an optical superlens suitable for extreme environments according to any one of claims 1 to 6, characterized in that: Includes the following steps, S1 patterns one side of the surface of the optical substrate (3) to obtain the moth eye membrane structure layer (2); S2 directly bonds a wide bandgap semiconductor material to the moth-eye membrane structure layer (2) obtained in S1, then thins it to the predetermined height of the superlens structure layer (1), and then performs patterning to obtain the superlens structure layer (1). S3 directly bonds the superlens structure layer (1) obtained in S2 to the moth eye membrane structure layer (2) obtained in S1; S4 deposits a thin film on the other side surface of the pair of optical substrates (3) obtained in S3 to obtain an optical composite film (4).

8. The method for fabricating an optical superlens suitable for extreme environments according to claim 7, characterized in that: In S1, the equivalent refractive index distribution curve of the optical superlens structure formed by multiple nanopillars (11) is obtained in advance, the range of refractive index change from the optical superlens structure to the optical substrate (3) in the optical superlens plane is determined, and then the structural parameters of the moth eye membrane structure are determined by the transition from the equivalent refractive index of the optical superlens to the refractive index of the optical substrate (3).

9. The method for fabricating an optical superlens suitable for extreme environments according to claim 7, characterized in that: In S1, the optical substrate (3) is first exposed and developed on one side surface, then a chromium mask is deposited by vapor deposition, and the chromium mask in the unpatterned area is stripped off. Then the optical substrate (3) in the unpatterned area is etched to obtain the moth-eye membrane structure layer (2).

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