Manufacturing method of multi-focus super lens, multi-focus super lens and optical system
By using ultraviolet-induced reduction of graphene oxide to form a multifocal superlens with a nanoscale concentric ring structure, the complex manufacturing process and precision issues in existing technologies have been solved, enabling efficient manufacturing of multifocal superlenses and miniaturized integration of optical systems.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-13
- Publication Date
- 2026-04-14
AI Technical Summary
Existing multifocal superlens manufacturing processes involve numerous and complex steps, demanding requirements. The process is difficult to implement under the requirements of large area and high precision, making it difficult to achieve miniaturization and integration of optical systems.
By employing an ultraviolet-induced reduction method, a portion of the light modulation matrix of graphene oxide is reduced to reduced graphene oxide, forming a nanoscale concentric ring structure. Through material transformation and structural shape changes, a light modulation layer is constructed, providing different light phase modulation conditions and enabling the fabrication of a multifocal superlens.
It simplifies the manufacturing process, improves controllability and reproducibility, and enables the fabrication of large-area, high-precision multifocal superlenses, meeting the miniaturization and integration requirements of optical systems.
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Figure CN121857112A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of optical lens technology, specifically to a method for manufacturing a multifocal superlens and a multifocal superlens and optical system. Background Technology
[0002] With the continuous improvement of micro-nano fabrication technology and the integration of optical devices, the demand for optical components with multifocal functions is gradually increasing. Multifocal optical devices can achieve multiple focusing positions in the same optical path and have wide applications in imaging, optical detection and other fields. However, existing multifocal optical systems usually rely on multiple lenses or complex optical combination structures, which not only result in a large system size, but also a complex assembly and adjustment process, which is not conducive to the miniaturization and integration of optical systems.
[0003] In recent years, planar optical devices have gradually become a development direction to replace traditional refractive optical elements. Among them, superlenses, by manipulating the light field at the subwavelength scale, can achieve focusing and imaging functions in planar structures. For multifocal requirements, existing technologies have introduced various phase modulation methods into the superlens structure to achieve multiple focusing positions of the light field along the propagation direction.
[0004] Existing multifocal superlens structures are mostly composed of various discrete micro / nano structural units such as nanopillars and nanopores. Phase modulation is achieved by changing the geometry, arrangement, or material parameters of these units. However, the fabrication of such structures typically involves multiple complex steps, including electron beam exposure, development, etching, and resist removal. Different sizes of nanopillars and nanopores need to be fabricated separately and then assembled or arranged in sequence, resulting in numerous and complex steps. Each step places high demands on fabrication accuracy, equipment stability, and operating conditions. Therefore, there are certain challenges in large-area fabrication and processing repeatability control, especially under high-precision requirements, where the process implementation is quite difficult.
[0005] Therefore, a solution is needed to address the challenges of manufacturing multifocal superlenses, which involve numerous and complex steps, demanding requirements, and high precision requirements for large areas. Summary of the Invention
[0006] This application provides a method for manufacturing a multifocal superlens, as well as a multifocal superlens and an optical system, to solve the problems of numerous and complex manufacturing processes, stringent requirements, and high process difficulty under large-area and high-precision requirements for multifocal superlens.
[0007] In one aspect of this application, a method for manufacturing a multifocal superlens is provided, comprising the following steps: providing a lens substrate; forming a light modulation substrate on one side surface of the lens substrate, the material of the light modulation substrate being graphene oxide; using ultraviolet-induced reduction of a portion of the light modulation substrate to form a modulation feature structure in the region irradiated by ultraviolet light; the modulation feature structure being a plurality of mutually spaced nanoscale concentric rings; the material of the modulation feature structure being changed from graphene oxide to reduced graphene oxide; the modulation feature structure and the light modulation substrate in the region not irradiated by ultraviolet light together constitute a light modulation layer; different modulation feature structures and their adjacent light modulation substrates together provide different light phase modulation conditions.
[0008] The method for manufacturing a multifocal superlens provided in this application uses ultraviolet-induced reduction to reduce a portion (i.e., a predetermined location) of a graphene oxide (GO) light modulation substrate to reduced graphene oxide (rGO). During this process, in addition to the material transformation itself, some carbon skeleton and oxygen-containing groups are lost, resulting in gas loss. This causes the remaining volume to decrease relative to its original size before reduction; that is, the reduced graphene oxide after reduction has a smaller volume than before. Therefore, this process naturally leads to a change in structural shape in addition to the material transformation. Through this change in structural shape, a modulation feature structure with a different characteristic size from the light modulation substrate is naturally formed. The modulation feature structure and the remaining unreduced light modulation substrate can jointly constitute a light modulation layer, and different modulation feature structures and their adjacent light modulation substrates can jointly provide different optical phase modulation conditions. By using different optical phase modulation conditions, combined with the wavelength of the incident light, multiple focal points can be formed in the projection space behind the lens. This enables the fabrication of a multifocal superlens. This manufacturing process is simple, allowing for one-step fabrication of both the optical modulation substrate and the modulation feature structure. It is easy to implement, highly controllable, and reproducible. Furthermore, the photolithography process allows for the selection of appropriate masks to meet precision requirements, resulting in high consistency and stability in large-area reproducible fabrication. The direct formation of nanoscale modulation feature structures through UV-induced reduction allows for fabrication on extremely small substrates without assembly or other processing. This results in compact structures with small dimensions, which is beneficial for the miniaturization and integration of optical systems. Therefore, it can meet the process requirements for large-area, high-precision fabrication of multifocal superlenses.
[0009] In some embodiments of this application, the modulation feature structure is a groove formed by a depression relative to the surface of the light modulation substrate; the groove is formed by ultraviolet light irradiation of graphene oxide to reduce graphene oxide; different modulation feature structures are concentric annular grooves of different diameters.
[0010] In some embodiments of this application, the step of forming the modulation feature structure is to form grooves of the same degree of depression by one step of ultraviolet-induced reduction; or, to form various grooves of different degrees of depression by multiple steps of ultraviolet-induced reduction.
[0011] In some embodiments of this application, the ultraviolet-induced reduction step includes: providing a pre-patterned mask and placing the mask on the surface of a photomodulation substrate; irradiating the photomodulation substrate with ultraviolet light to transfer the pattern of the mask to the photomodulation substrate; forming patterned grooves in the photomodulation substrate; reducing graphene oxide at the patterned groove locations to reduced graphene oxide to form grooves that are recessed relative to the unirradiated portion of the photomodulation substrate surface; and removing the mask.
[0012] In some embodiments of this application, the lens substrate is a transparent substrate; the step of forming the light modulation substrate involves forming a graphene oxide layer on the surface of the transparent substrate using an electrostatic self-assembly method, including: pre-treating the graphene oxide; diluting and ultrasonically dispersing the graphene oxide dispersion; diluting and ultrasonically dispersing the polydiallyldimethylammonium chloride solution; immersing the transparent substrate in the treated graphene oxide dispersion, then rinsing it with deionized water and drying it with nitrogen; immersing the transparent substrate after graphene oxide immersion in the pre-treated polydiallyldimethylammonium chloride solution, then rinsing it with deionized water and drying it with nitrogen; alternately repeating the above steps of immersing in the graphene oxide dispersion and immersing in the polydiallyldimethylammonium chloride solution and drying it several times to form a graphene oxide layer on the surface of the transparent substrate, constituting the light modulation substrate.
[0013] In another aspect of this application, a multifocal superlens is also provided, manufactured using the manufacturing method of the multifocal superlens provided in this application, comprising: a lens substrate; a light modulation substrate disposed on one side surface of the lens substrate, the material of the light modulation substrate being graphene oxide; a modulation feature structure in the same layer as the light modulation substrate; the modulation feature structure being a plurality of mutually spaced nanoscale concentric rings; the material of the modulation feature structure being reduced graphene oxide; the modulation feature structure and the light modulation substrate in the region not irradiated by ultraviolet light together constitute a light modulation layer; different modulation feature structures and their adjacent light modulation substrates together provide different light phase modulation conditions.
[0014] The multifocal superlens provided in this application is manufactured using a multifocal superlens manufacturing method. A method involving ultraviolet-induced reduction is used to reduce a portion (i.e., a predetermined location) of a graphene oxide (GO) light modulation substrate to reduced graphene oxide (rGO). During this process, in addition to the material transformation itself, some carbon skeleton and oxygen-containing groups are lost, resulting in gas loss. This causes the remaining volume to decrease relative to its original size before reduction; that is, the reduced graphene oxide after reduction has a smaller volume than before. Therefore, this process naturally leads to a change in structural shape in addition to the material transformation. This change in structural shape naturally forms a modulation feature structure with dimensions different from the light modulation substrate. The modulation feature structure and the remaining unreduced light modulation substrate can together constitute a light modulation layer, and different modulation feature structures and their adjacent light modulation substrates can jointly provide different optical phase modulation conditions. By using different optical phase modulation conditions, combined with the wavelength of the incident light, multiple focal points can be formed in the projection space behind the lens. This enables the manufacture of a multifocal superlens. This manufacturing process is simple, allowing for one-step fabrication of both the optical modulation substrate and the modulation feature structure. It is easy to implement, highly controllable, and reproducible. Furthermore, the photolithography process allows for the selection of appropriate masks to meet precision requirements, resulting in high consistency and stability in large-area reproducible fabrication. The direct formation of nanoscale modulation feature structures through UV-induced reduction allows for fabrication on extremely small substrates without assembly or other processing. This results in compact structures with small dimensions, which is beneficial for the miniaturization and integration of optical systems. Therefore, it can meet the process requirements for large-area, high-precision fabrication of multifocal superlenses.
[0015] In some embodiments of this application, the modulation feature structure is a groove formed by a depression relative to the surface of the light modulation substrate; different modulation feature structures are concentric annular grooves of different diameters; the bottom of the groove is a modulation feature structure of reduced graphene oxide, and the sidewall of the groove is the light modulation substrate of graphene oxide.
[0016] In some embodiments of this application, all modulation feature structures are divided into several groups, and each group of modulation feature structures provides different optical phase modulation conditions, so that the transmitted light can form multiple focal points at different positions.
[0017] In some embodiments of this application, the lens substrate is a transparent substrate.
[0018] In another aspect, this application also provides an optical system, including the multifocal superlens provided in this application; the optical system is an optical focusing or optical imaging system;
[0019] The optical system includes an image source and an acquisition component spaced apart from the multifocal superlens; The image source is adapted to transmit incident light containing an optical image to the multifocal superlens, project the optical image onto the multifocal superlens, and form corresponding images at multiple focal points in the projection space behind the multifocal superlens; The acquisition component is suitable for acquiring images formed at various focal positions in the projection space; It also includes adjustment components suitable for adjusting the relative positional relationship between the image source, the multifocal superlens, and the acquisition components.
[0020] The optical system provided in this application includes a multifocal superlens, manufactured using the method described herein. This method employs ultraviolet-induced reduction to reduce a portion (i.e., a predetermined location) of a graphene oxide (GO) light modulation substrate to reduced graphene oxide (rGO). During this process, in addition to the material transformation itself, some carbon skeleton and oxygen-containing groups are lost, resulting in gas loss. This causes the remaining volume to decrease relative to its original size before reduction; that is, the reduced graphene oxide has a smaller volume than before reduction. Therefore, this process naturally results in a change in structural shape in addition to the material transformation. This change in structural shape naturally forms a modulation feature structure with dimensions different from the light modulation substrate. The modulation feature structure and the remaining unreduced light modulation substrate can together constitute a light modulation layer, and different modulation feature structures and their adjacent light modulation substrates can jointly provide different optical phase modulation conditions. By using different optical phase modulation conditions, combined with the wavelength of the incident light, multiple focal points can be formed in the projection space behind the lens. This enables the manufacture of a multifocal superlens. This manufacturing process is simple, allowing for one-step fabrication of both the optical modulation substrate and the modulation feature structure. It is easy to implement, highly controllable, and reproducible. Furthermore, the photolithography process allows for the selection of appropriate masks to meet precision requirements, resulting in high consistency and stability in large-area reproducible fabrication. The direct formation of nanoscale modulation feature structures through UV-induced reduction allows for fabrication on extremely small substrates without assembly or other processing. This results in compact structures with small dimensions, which is beneficial for the miniaturization and integration of optical systems. Therefore, it can meet the process requirements for large-area, high-precision fabrication of multifocal superlenses. Attached Figure Description
[0021] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0022] Figure 1This is a schematic flowchart of a method for manufacturing a multifocal superlens according to an embodiment of this application; Figure 2 This is a schematic cross-sectional view of a multifocal superlens according to an embodiment of this application; Figure 3 This is a three-dimensional structural schematic diagram of a multifocal superlens according to an embodiment of this application; Figure 4 This is a design and fabrication drawing of a multifocal superlens according to an embodiment of this application; Figure 5 This is a multifocal superlens according to an embodiment of the present application, showing the acquisition results of multiple imaging focal points formed in the projection space after illumination with 550nm light; Figure 6 This is a multifocal superlens according to an embodiment of the present application, showing the acquisition results of multiple imaging focal points formed in the projection space after illumination with 450nm light; Figure 7 This is a multifocal superlens according to an embodiment of the present application, showing the acquisition results of multiple imaging focal points formed in the projection space after illumination with 650nm light; Figures 8a-8c This is an example of a multifocal superlens of this application, showing the imaging results formed at different imaging focal points in the projection space after being illuminated with 550nm light; Figures 9a-9c This is an example of a multifocal superlens of this application, which projects images of different imaging focal points in the space after being illuminated with 450nm light. Figures 10a-10c This is an example of a multifocal superlens according to an embodiment of this application, showing the imaging results formed at different imaging focal points in the projection space after being illuminated with 650nm light. Detailed Implementation
[0023] As mentioned earlier, the current manufacturing process for multifocal superlenses involves numerous and complex steps, with stringent requirements, and is challenging to implement under the conditions of large area and high precision.
[0024] Therefore, this application provides a method for manufacturing a multifocal superlens, as well as a multifocal superlens and an optical system, to solve the above-mentioned problems.
[0025] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0026] It is understood that before using the technical solutions disclosed in the various embodiments of this application, users should be informed of the types, scope of use, and usage scenarios of the personal information involved in this application in an appropriate manner in accordance with relevant laws and regulations, and user authorization should be obtained.
[0027] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.
[0028] Example 1 This embodiment provides a method for manufacturing a multifocal superlens, referring to... Figure 1 , combined Figures 2 to 3 This includes the following steps: Provide lens substrate 100; A light modulation substrate 210 is formed on one side surface of the lens substrate 100, and the material of the light modulation substrate 210 is graphene oxide; A portion of the substrate 210 is modulated using ultraviolet-induced reduction light, causing the region irradiated by ultraviolet light to form a modulation feature structure 220; the modulation feature structure 220 consists of several mutually spaced nanoscale concentric rings; the material of the modulation feature structure 220 is changed from graphene oxide to reduced graphene oxide. The modulation feature structure 220 and the light modulation substrate 210 in the region not exposed to ultraviolet light together constitute the light modulation layer 200; different modulation feature structures 220 and their adjacent light modulation substrates 210 together provide different light phase modulation conditions.
[0029] The multifocal superlens manufacturing method provided in this embodiment uses ultraviolet-induced reduction to reduce a portion (i.e., a predetermined location) of the graphene oxide (GO) light modulation substrate 210 into a reduced graphene oxide (rGO) modulation feature structure 220. During this process, in addition to the material transformation itself, there is also the loss of some carbon skeleton and oxygen-containing groups, resulting in gas escape. This causes the remaining volume to decrease relative to the volume before reduction; that is, the reduced graphene oxide after reduction has a smaller volume than the unreduced graphene oxide. Therefore, this process naturally results in a change in structural shape in addition to the material transformation. Through this change in structural shape, a modulation feature structure 220 with a different feature size than the light modulation substrate 210 is naturally formed. The modulation feature structure 220 and the remaining unreduced light modulation substrate 210 can jointly constitute the light modulation layer 200, and different modulation feature structures 220 and their adjacent light modulation substrates 210 can jointly provide different optical phase modulation conditions. By using different optical phase modulation conditions, combined with the wavelength of the incident light, multiple focal points can be formed in the projection space behind the lens. This enables the fabrication of multifocal superlenses. The manufacturing process is simple, with both the light modulation substrate 210 and the modulation feature structure 220 formed in a single step. It is easy to implement, highly controllable, and reproducible. Furthermore, the photolithography process allows for the selection of appropriate masks to meet the precision requirements, resulting in high consistency and stability in large-area reproducible fabrication. The direct formation of nanoscale modulation feature structures through UV-induced reduction allows for fabrication on extremely small substrates without assembly or other processing. This results in compact structures with small dimensions, beneficial for the miniaturization and integration of optical systems. Therefore, it can meet the process requirements for large-area, high-precision fabrication of multifocal superlenses. High-precision batch fabrication is possible within the range of 100μm×100μm to 3cm×3cm, with groove depths reaching 100nm level precision and widths as fine as 0.6μm.
[0030] Furthermore, in some embodiments of this application, reference is made to... Figure 2 The modulation feature structure 220 is a groove formed by a surface depression relative to the light modulation substrate 21; the groove is formed by ultraviolet light irradiation reducing graphene oxide to reduced graphene oxide; reference Figure 3 Different modulation feature structures 220 are concentric annular grooves of different diameters.
[0031] Furthermore, in some embodiments of this application, The step of forming modulation feature structure 220 involves forming grooves of the same degree of indentation through a one-step ultraviolet-induced reduction; or, Various grooves with different degrees of indentation are formed through multi-step ultraviolet-induced reduction.
[0032] Typically, if only one groove depth is required, a single ultraviolet-induced reduction step is sufficient to form the entire multifocal superlens. If different groove depths are required, multiple ultraviolet-induced reduction steps can be used. However, it should be noted that because different concentric rings have different diameters, even grooves of the same depth can achieve multifocal light projection imaging.
[0033] Furthermore, in some embodiments of this application, the ultraviolet-induced reduction step includes: A pre-graphicated mask is provided and the mask is placed on the surface 210 of the light modulation substrate; Irradiate the light modulation substrate 210 with ultraviolet light to transfer the pattern of the photomask to the light modulation substrate 210; the light modulation substrate 210 forms patterned grooves; the graphene oxide at the patterned groove positions is reduced to reduced graphene oxide, forming grooves that are recessed on the surface of the light modulation substrate 210 relative to the unirradiated portion. Finally, remove the mask template.
[0034] Furthermore, in some embodiments of this application, the lens substrate 100 is a transparent substrate; The step of forming the light modulation substrate 210 involves forming a graphene oxide layer on the surface of a transparent substrate using an electrostatic self-assembly method, including: Pre-treat graphene oxide by diluting and ultrasonically dispersing the graphene oxide dispersion. The polydiallyl dimethylammonium chloride (PDDA) solution was diluted and ultrasonically dispersed; the transparent substrate was immersed in the treated graphene oxide dispersion, then removed and rinsed with deionized water and dried with nitrogen. The transparent substrate, after being soaked in graphene oxide, was immersed in a pretreated polydiallyldimethylammonium chloride solution, then removed and rinsed with deionized water, and dried with nitrogen gas. The steps of immersing in the graphene oxide dispersion and then drying, and immersing in the polydiallyldimethylammonium chloride solution and then drying are repeated several times to form a graphene oxide layer on the surface of the transparent substrate, constituting the light modulation substrate 210.
[0035] The manufacturing process of a specific multifocal superlens is illustrated below: A lens substrate 100 is provided. A quartz glass slide with a thickness of about 1 mm is selected as the lens substrate 100. The slide is cleaned with deionized water and anhydrous ethanol in sequence, and then dried with nitrogen gas to remove contaminants from the substrate surface.
[0036] A light modulation substrate 210 is formed by preparing a graphene oxide film on the surface of a lens substrate 100 using an electrostatic self-assembly method, which serves as the light modulation substrate 210. The specific process is as follows: A graphene oxide (GO) dispersion (5 mg / L) was diluted at a volume ratio of 1:9 and then sonicated for 30 min to ensure uniform dispersion of the graphene oxide sheets. Simultaneously, a polydiallyldimethylammonium chloride (PDDA) solution was diluted at a volume ratio of 1:16 and also sonicated for 30 min.
[0037] The pretreated lens substrate 100 was immersed in a graphene oxide dispersion for 30 seconds, then removed and thoroughly rinsed with deionized water, followed by drying with a nitrogen spray gun. Next, the lens substrate 100 was immersed in a PDDA solution for 30 seconds, rinsed with deionized water, and dried. This process constitutes one complete electrostatic self-assembly cycle. This cycle was repeated approximately 50 times, alternating between immersion and drying of graphene oxide and immersion and drying of PDDA, for approximately 50 cycles. A continuous and uniform graphene oxide film was formed on the substrate surface, serving as the light modulation substrate 210. The graphene oxide film prepared by this method has a thickness of approximately 200 nm, with a thickness increase of approximately 3.5 nm to 4 nm per cycle.
[0038] After obtaining the photomodulation substrate 210, ultraviolet light was used to induce photoreduction of graphene oxide through exposure using a photomask, forming the modulation feature structure 220 and constructing a multifocal superlens structure. The processing equipment used was a two-photon polymerization lithography machine with an ultraviolet wavelength of 365 nm, an output power of 15 W, an irradiation time of 5 hours, and a 100× objective lens with a numerical aperture (NA) of 0.7. The photomask had a pre-formed patterned pattern, and the ultraviolet light was applied to the graphene oxide film surface along a pre-defined concentric circular trajectory, i.e., the patterned pattern of the photomask.
[0039] In the ultraviolet-irradiated region, graphene oxide undergoes localized reduction, and the material (mainly some carbon skeleton and oxygen-containing groups) is removed as a gas, thus forming a modulation feature structure 220 with a groove structure on the photomodulation substrate 210. After exposure, the effective material thickness (i.e., feature size) corresponding to the groove region is approximately 100 nm, and the groove depth is approximately 100 nm. The unexposed region retains the graphene oxide material state. Thus, a photomodulation layer 200 is formed on the continuous graphene oxide film, i.e., the photomodulation substrate 210, consisting of the feature modulation structure 220 of the reduced graphene oxide groove and the unexposed graphene oxide photomodulation substrate 210, which together with the lens substrate constitutes a multifocal superlens structure.
[0040] Design and fabrication drawings for multifocal superlenses manufactured using the above methods are provided for reference. Figure 4 . Figure 4 Among the multiple adjacent nanoscale concentric rings, the brighter ones are the light modulation substrate 210, and the darker ones are the modulation feature structures 220.
[0041] To verify the actual effect of the multifocal superlens manufactured by the manufacturing method provided in this embodiment, the following tests were conducted: Test 1: The multifocal superlens manufactured according to the above specific implementation process is installed in an optical testing system, and a collimated beam is irradiated onto the surface of the multifocal superlens in an approximately normal incidence manner. The relative position between the multifocal superlens and the detection system is adjusted, and the light intensity distribution in the propagation area behind the multifocal superlens is scanned and measured.
[0042] During the scanning process, multiple regions of enhanced light intensity can be observed along the propagation direction, corresponding to multiple focusing positions. The distribution of different focusing positions along the optical axis indicates that this superlens structure can achieve multifocal focusing functionality.
[0043] The results are as follows Figure 5 ,like Figure 6 , Figure 7 The images show the bright light at multiple focal positions scanned within the propagation region behind the multifocal superlens after illuminating it with 550nm, 450nm, and 650nm light, respectively. For example... Figure 5 Three bright spots are obtained at the focal points f1, f2, and f3, respectively. The incident light from the surface converges at these three points after passing through the multifocal superlens, forming focal points. This indicates that the superlens structure can achieve multifocal focusing functionality.
[0044] Test 2: Based on Test 1, the multifocal superlens was tested by introducing filters with different center wavelengths into the optical path and selecting different bands of visible light as incident light. Under different wavelength conditions, multifocal focusing was observed in the propagation direction.
[0045] The sample to be imaged was placed in front of the superlens, an imaging optical path was constructed, and the sample was imaged for testing. The imaging results show that the multifocal superlens can achieve sample imaging under different wavelength conditions and can be used in multifocal focusing and imaging-related optical systems.
[0046] The results are as follows Figures 8a-8c , Figures 9a-9c , Figures 10a-10c The images shown depict optical focusing at multiple focal points obtained by scanning the propagation region behind the multifocal superlens after illuminating the sample with 550nm, 450nm, and 650nm light. Figure 8a , 8b 8c represents the image at different focal positions. Although the brightness and sharpness of the images differ, an image can be observed in all of them. This demonstrates that a multifocal superlens can indeed form multiple focal points. Combined with... Figures 9a-9c , Figures 10a-10c The results demonstrate that sample imaging can be achieved under different spectral conditions, and it can be used in multifocal focusing and imaging-related optical systems.
[0047] It should also be noted that the relative brightness relationships at the corresponding focal points f1, f2, and f3 in Test 1 and Test 2 are not entirely consistent. This is because the brightness acquired during image acquisition is affected not only by the distance between the focal point and the lens but also by other acquisition conditions. Although the brightness at the corresponding focal points in Test 1 and Test 2 is not entirely consistent, both tests show converged light or imaging at the corresponding focal points. Therefore, it can be concluded that converged imaging can be achieved at multiple corresponding focal points, indicating that the superlens provided in this embodiment has multifocal imaging capabilities.
[0048] Example 2 This embodiment provides a multifocal superlens, manufactured using the multifocal superlens manufacturing method provided in Embodiment 1 above, combined with... Figure 2 and Figure 3 ,include: Lens substrate 100; A light modulation substrate 210 is disposed on one side surface of the lens substrate 100, and the material of the light modulation substrate 210 is graphene oxide; The modulation feature structure 220 is in the same layer as the light modulation substrate 210; the modulation feature structure 220 consists of several mutually spaced nanoscale concentric rings; the material of the modulation feature structure 220 is reduced graphene oxide; The modulation feature structure 220 and the optical modulation substrate 210 together constitute the optical modulation layer 200; different modulation feature structures 210 and their adjacent optical modulation substrates 210 together provide different optical phase modulation conditions.
[0049] The multifocal superlens provided in this embodiment is manufactured using a multifocal superlens manufacturing method. A portion (i.e., a predetermined location) of the graphene oxide (GO) light modulation substrate 210 is reduced to a modulation feature structure 220 of reduced graphene oxide (rGO). During this process, in addition to the material transformation itself, some carbon skeleton and oxygen-containing groups are lost, resulting in gas loss. This causes the remaining volume to decrease relative to its original size before reduction; that is, the reduced graphene oxide has a smaller volume than before reduction. Therefore, this process naturally results in a change in structural shape in addition to the material transformation. This change in structural shape naturally forms a modulation feature structure with a different feature size than the light modulation substrate 210. The modulation feature structure 220 and the remaining unreduced light modulation substrate can jointly constitute the light modulation layer 200, and different modulation feature structures 220 and their adjacent light modulation substrates 210 can jointly provide different optical phase modulation conditions. By using different optical phase modulation conditions, combined with the wavelength of the incident light, multiple focal points can be formed in the projection space behind the lens. This enables the fabrication of multifocal superlenses. The manufacturing process is simple, allowing for one-step formation of both the light modulation substrate and the modulation feature structure. It is easy to implement, highly controllable, and reproducible. Furthermore, the photolithography process allows for the selection of appropriate masks to meet precision requirements, resulting in high consistency and stability in large-area reproducible fabrication. The direct formation of nanoscale modulation feature structures through UV-induced reduction allows for fabrication on extremely small substrates without assembly or other processing. This results in compact structures with small dimensions, beneficial for the miniaturization and integration of optical systems. Therefore, it can meet the process requirements for large-area, high-precision fabrication of multifocal superlenses.
[0050] Furthermore, in some embodiments of this application, the modulation feature structure 220 is a groove formed by a surface recess relative to the optical modulation substrate 210; Different modulation feature structures 220 are concentric annular grooves of different diameters; The bottom of the groove is a modulation feature structure 220 of reduced graphene oxide, and the sidewall of the groove is a light modulation substrate 210 of graphene oxide.
[0051] Furthermore, in some embodiments of this application, the recess depths of each modulation feature structure 220 relative to the surface of the light modulation substrate 210 may be the same or different. For simplicity of fabrication, the recess depths of each modulation feature structure 220 (i.e., the grooves) can be chosen to be the same, thus allowing completion in a single ultraviolet-induced reduction step. If there are special requirements, different grooves can have different recess depths to meet specific needs. This is achieved through multi-step ultraviolet-induced reduction processing. It should be noted that because different grooves have different diameters, even if the groove recess depths are the same, multifocal transmission imaging can still be achieved.
[0052] Furthermore, in some embodiments of this application, the lens substrate 100 is a transparent substrate.
[0053] Example 3 This embodiment provides an optical system, including the multifocal superlens provided in Embodiment 2 above; the optical system is an optical focusing or optical imaging system. The optical system includes an image source and an acquisition component spaced apart from the multifocal superlens; The image source is adapted to transmit incident light containing an optical image to the multifocal superlens, project the optical image onto the multifocal superlens, and form corresponding images at multiple focal points in the projection space behind the multifocal superlens; The acquisition component is suitable for acquiring images formed at various focal positions in the projection space; It also includes adjustment components suitable for adjusting the relative positional relationship between the image source, the multifocal superlens, and the acquisition components.
[0054] The optical system provided in this application includes a multifocal superlens, manufactured using the method described herein. This method employs ultraviolet-induced reduction to reduce a portion (i.e., a predetermined location) of a graphene oxide (GO) light modulation substrate to reduced graphene oxide (rGO). During this process, in addition to the material transformation itself, some carbon skeleton and oxygen-containing groups are lost, resulting in gas loss. This causes the remaining volume to decrease relative to its original size before reduction; that is, the reduced graphene oxide has a smaller volume than before reduction. Therefore, this process naturally results in a change in structural shape in addition to the material transformation. This change in structural shape naturally forms a modulation feature structure with dimensions different from the light modulation substrate. The modulation feature structure and the remaining unreduced light modulation substrate can together constitute a light modulation layer, and different modulation feature structures and their adjacent light modulation substrates can jointly provide different optical phase modulation conditions. By using different optical phase modulation conditions, combined with the wavelength of the incident light, multiple focal points can be formed in the projection space behind the lens. This enables the manufacture of a multifocal superlens. This manufacturing process is simple, allowing for one-step fabrication of both the optical modulation substrate and the modulation feature structure. It is easy to implement, highly controllable, and reproducible. Furthermore, the photolithography process allows for the selection of appropriate masks to meet precision requirements, resulting in high consistency and stability in large-area reproducible fabrication. The direct formation of nanoscale modulation feature structures through UV-induced reduction allows for fabrication on extremely small substrates without assembly or other processing. This results in compact structures with small dimensions, which is beneficial for the miniaturization and integration of optical systems. Therefore, it can meet the process requirements for large-area, high-precision fabrication of multifocal superlenses.
[0055] Although embodiments of this application have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of this application, and all such modifications and variations fall within the scope defined by the appended claims.
Claims
1. A method for manufacturing a multifocal superlens, characterized in that, Includes the following steps: Provide lens substrate; A light modulation substrate is formed on one side surface of the lens substrate, and the material of the light modulation substrate is graphene oxide; A portion of the optical modulation substrate is reduced by ultraviolet light to form a modulation feature structure in the ultraviolet-irradiated area; the modulation feature structure is a plurality of mutually spaced nanoscale concentric rings. The material of the modulation feature structure is changed from graphene oxide to reduced graphene oxide; The modulation feature structure and the light modulation substrate in the region not exposed to ultraviolet light together constitute the light modulation layer; different modulation feature structures and their adjacent light modulation substrates together provide different light phase modulation conditions.
2. The method for manufacturing a multifocal superlens according to claim 1, characterized in that, The modulation feature structure is a groove formed by a recess relative to the surface of the optical modulation substrate; The groove is formed by irradiating graphene oxide with ultraviolet light to reduce graphene oxide to reduced graphene oxide; The different modulation feature structures are concentric annular grooves of different diameters.
3. The method for manufacturing a multifocal superlens according to claim 2, characterized in that, The step of forming the modulation feature structure involves forming grooves of the same degree of indentation through a one-step ultraviolet-induced reduction. or, Various grooves with different degrees of indentation are formed through multi-step ultraviolet-induced reduction.
4. The method for manufacturing a multifocal superlens according to claim 1, characterized in that, The ultraviolet-induced reduction step includes: A pre-graphicated mask is provided and disposed on the surface of the light modulation substrate; The pattern of the photomask is transferred to the photomodulation substrate by irradiating it with ultraviolet light; The light modulation substrate forms patterned grooves; the graphene oxide at the patterned groove locations is reduced to reduced graphene oxide, forming grooves that are recessed on the surface of the light modulation substrate relative to the unilluminated portion. Remove the mask template.
5. The method for manufacturing a multifocal superlens according to claim 1, characterized in that, The lens substrate is a transparent substrate; The step of forming the light modulation substrate involves forming a graphene oxide layer on the surface of the transparent substrate using an electrostatic self-assembly method, including: Pre-treat graphene oxide by diluting and ultrasonically dispersing the graphene oxide dispersion. Dilute the polydiallyldimethylammonium chloride solution and disperse it ultrasonically; The transparent substrate was immersed in the treated graphene oxide dispersion, then removed and rinsed with deionized water and dried with nitrogen. The transparent substrate, after being soaked in graphene oxide, is immersed in the pretreated polydiallyldimethylammonium chloride solution, then removed, rinsed with deionized water, and dried with nitrogen gas. The steps of immersing in the graphene oxide dispersion and then drying, and immersing in the polydiallyldimethylammonium chloride solution and then drying are repeated several times to form a graphene oxide layer on the surface of the transparent substrate, constituting the light modulation substrate.
6. A multifocal superlens, characterized in that, Manufactured using the manufacturing method of any one of claims 1 to 5, comprising: Lens substrate; The light modulation substrate is disposed on one side surface of the lens substrate, and the material of the light modulation substrate is graphene oxide; A modulation feature structure in the same layer as the optical modulation substrate; the modulation feature structure is a plurality of mutually spaced nanoscale concentric rings; the material of the modulation feature structure is reduced graphene oxide; The modulation feature structure and the optical modulation substrate together constitute the optical modulation layer; different modulation feature structures and their adjacent optical modulation substrates together provide different optical phase modulation conditions.
7. The multifocal superlens according to claim 6, characterized in that, The modulation feature structure is a groove formed by a recess relative to the surface of the optical modulation substrate; The different modulation feature structures are concentric annular grooves of different diameters; The bottom of the groove is a modulation feature structure of reduced graphene oxide, and the sidewalls of the groove are a light modulation substrate of graphene oxide.
8. The multifocal superlens according to claim 7, characterized in that, The depth of the depression of each of the modulation feature structures relative to the surface of the optical modulation substrate may be the same or different.
9. The multifocal superlens according to claim 6, characterized in that, The lens substrate is a transparent substrate.
10. An optical system, characterized in that, Includes the multifocal superlens of any one of claims 6 to 8; The optical system is an optical focusing system or an optical imaging system; The optical system includes an image source and an acquisition component spaced apart from the multifocal superlens; The image source is adapted to transmit incident light containing an optical image to the multifocal superlens, project the optical image onto the multifocal superlens, and form corresponding images at multiple focal points in the projection space behind the multifocal superlens; The acquisition component is adapted to acquire images formed at each focal position in the projection space; It also includes an adjustment component adapted to adjust the relative positional relationship between the image source, the multifocal superlens, and the acquisition component.