Photonic crystal composite film layer, heterojunction photonic crystal superprism and preparation method thereof

Abstract

This invention discloses a photonic crystal composite film, a heterojunction photonic crystal superprism, and their fabrication method, belonging to the field of photonic crystal device technology. The photonic crystal composite film includes a bonded glass layer and a photonic crystal film layer; the photonic crystal film layer is either spherical or non-spherical. The heterojunction photonic crystal superprism includes: a first glass layer, a spherical photonic crystal film layer, a heterojunction layer, a non-spherical photonic crystal film layer, and a second glass layer. Furthermore, this invention proposes a fabrication method for the heterojunction photonic crystal superprism, comprising: hydrophilically modifying the spherical photonic crystal film layer supported by the first glass layer and the non-spherical photonic crystal film layer supported by the second glass layer, and then stacking and curing the bonding surfaces of the two to obtain the heterojunction photonic crystal superprism. This invention achieves a wide refractive angle range for the superprism, suitable for different wavelengths.

Description

Technical Field

[0001] This invention relates to the field of photonic crystal device technology, specifically to a photonic crystal composite film, a heterojunction photonic crystal superprism, and their fabrication methods. Background Technology

[0002] Photonic crystal superprisms, with their super-diffraction-limited spectral dispersive properties, have significant application value in micro-nano spectral detection, optical communication, and other fields. Traditional photonic crystal superprisms are mostly fabricated using single-structure photonic crystals, which suffers from bottlenecks such as a narrow refractive angle range and a single applicable wavelength. Furthermore, existing fabrication methods struggle to achieve ordered film formation of gradient structures. In addition, SiO2-based photonic crystals are prone to random stacking during solid-state interface self-assembly, making it impossible to form a uniform and ordered close-packed film, thus limiting the performance improvement of superprisms.

[0003] While microfluidic technology enables precise control of micro and nanostructures, the strong sealing method (oxygen plasma bonding) between conventional PDMS and glass prevents the chip from being peeled off without damage, making it difficult to complete the in-situ deposition and curing of photonic crystal films within the channel. Furthermore, the Czochralski method is prone to film cracking and particle aggregation, failing to guarantee the integrity of the gradient structure. Therefore, there is an urgent need for a fabrication method adapted to the characteristics of SiO2 particles, combining microfluidics and gas-liquid interface self-assembly, to achieve efficient and ordered fabrication of spherical-non-spherical photonic crystal gradient heterostructures, breaking through the performance bottleneck of traditional superprisms. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide a photonic crystal composite film, a heterojunction photonic crystal superprism and its preparation method, thereby solving the technical problems of narrow refraction angle range and single applicable wavelength in the prior art.

[0005] To achieve the above-mentioned technical objectives, the present invention provides a photonic crystal composite film layer, comprising a bonded glass layer and a photonic crystal film layer; the photonic crystal film layer is a spherical photonic crystal film layer or a non-spherical photonic crystal film layer. This photonic crystal composite film layer can be used to fabricate heterojunction photonic crystal superprisms with a wide range of mirror refraction angles.

[0006] The present invention also proposes a heterojunction photonic crystal superprism, which is obtained by stacking and solidifying the above-mentioned photonic crystal composite film layers. The heterojunction photonic crystal superprism comprises, from top to bottom: a first photonic crystal composite film layer, a heterojunction layer, and a second photonic crystal composite film layer.

[0007] The first photonic crystal composite film layer includes a first glass layer and a spherical photonic crystal film layer, and the second photonic crystal composite film layer includes a second glass layer and a non-spherical photonic crystal film layer; the heterojunction photonic crystal superprism includes, from top to bottom, a first glass layer, a spherical photonic crystal film layer, a heterojunction layer, a non-spherical photonic crystal film layer and a second glass layer.

[0008] In any embodiment, the spherical photonic crystal film is a spherical photonic crystal gradient ordered film; and / or, the non-spherical photonic crystal film is a non-spherical photonic crystal gradient ordered film.

[0009] In any embodiment, the optical test of the super prism adopts an oblique incidence method with an incidence angle range of 20°~45°, the propagation direction of the incident light is perpendicular to the gradient direction of the film layer, and the refraction angle of the super prism ranges from 55° to 60°.

[0010] Furthermore, the present invention also proposes a method for preparing the above-mentioned photonic crystal composite film, comprising the following steps: bonding a chip to a glass substrate to form a closed microchannel, and injecting spherical particle suspension or non-spherical particle suspension into the closed microchannel to obtain a spherical photonic crystal film supported by a glass layer or a non-spherical photonic crystal film supported by a glass layer.

[0011] Furthermore, this invention also proposes a method for fabricating the above-mentioned heterojunction photonic crystal superprism, comprising the following steps: S1. The chip is bonded to the glass substrate to form a closed microchannel. Spherical particle suspension or non-spherical particle suspension is injected into the closed microchannel to obtain a spherical photonic crystal film layer supported by the first glass layer or a non-spherical photonic crystal film layer supported by the second glass layer. S2. The spherical photonic crystal film layer supported by the first glass layer and the non-spherical photonic crystal film layer supported by the second glass layer are hydrophilically modified, and then the bonding surfaces of the two are stacked and solidified to form a heterojunction layer to obtain the heterojunction photonic crystal superprism.

[0012] In any embodiment, in step S1, the channel of the chip gradually narrows linearly along its length to obtain a spherical photonic crystal gradient ordered film layer supported by a first glass layer or a non-spherical photonic crystal gradient ordered film layer supported by a second glass layer.

[0013] In any embodiment, in step S1, the spherical particle suspension is prepared by the following steps: adding SiO2 spherical microspheres to an ethanol aqueous solvent, then adding SDBS (sodium dodecylbenzenesulfonate) dispersant and sonicating, and then degassing to remove bubbles to obtain the spherical particle suspension; and / or, the non-spherical particle suspension is prepared by the following steps: adding SiO2 sheet-like particles or SiO2 rod-like particles to an ethanol aqueous solvent, then adding SDBS dispersant and sonicating, and then degassing to remove bubbles to obtain the non-spherical particle suspension.

[0014] In any embodiment, the content of the SiO2 spherical microspheres or the SiO2 sheet particles in the spherical particle suspension or the non-spherical particle suspension is 0.3wt%-0.5wt%; and / or the content of the SDBS dispersant in the suspension is 0.01wt%-0.02wt%.

[0015] In any embodiment, in step S2, the hydrophilic modification includes: placing the spherical photonic crystal film layer supported by the first glass layer or the non-spherical photonic crystal film layer supported by the second glass layer into an oxygen plasma processor and processing it at a power of 100-120W for 25-30 seconds.

[0016] In any embodiment, in step S2, the curing includes baking at 50-60°C for 2-3 hours.

[0017] In any embodiment, in step S1, the injection flow rate of the spherical particle suspension or the non-spherical particle suspension injected into the closed microchannel is 0.05~0.1μL / min; and / or, in step S1, after the spherical particle suspension or the non-spherical particle suspension is injected, the channel is filled with the suspension and a stable gas-liquid interface is formed, and then it continues to be cured at 35-40℃ for 4-6h.

[0018] Compared with the prior art, the beneficial effects of the present invention include: the heterojunction photonic crystal superprism proposed in the present invention comprises, from top to bottom: a first glass layer, a spherical photonic crystal film layer, a heterojunction layer, a non-spherical photonic crystal film layer and a second glass layer. When illuminated with light of different wavelengths, the refraction angle range can reach 55°-60°, thus realizing a wide refraction angle range for the superprism and making it suitable for different wavelengths. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the chip structure in Embodiment 1 of the present invention.

[0020] Figure 2 This is a schematic diagram of the heterojunction photonic crystal superprism in Embodiment 1 of the present invention.

[0021] Figure 3 This is a schematic diagram of the microstructure of the heterojunction layer in Embodiment 1 of the present invention.

[0022] Figure 4 This is a schematic diagram of the super prism optical testing device in Embodiment 1 of the present invention.

[0023] Explanation of reference numerals in the attached figures: 1. Chip; 11. Channel inlet; 12. Channel; 13. Channel outlet; 21. First glass layer; 22. Spherical photonic crystal film layer; 221. Hexagonal unit cell; 23. Heterojunction layer; 24. Non-spherical photonic crystal film layer; 241. Parallelogram unit cell; 25. Second glass layer; 3. Angular resolution spectrometer; 4. Microfluidic device. Detailed Implementation

[0024] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for a specific parameter, it is also expected that ranges of 60~110 and 80~120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this application, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0025] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0026] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0027] This specific embodiment proposes a photonic crystal composite film layer, including a bonded glass layer and a photonic crystal film layer; the photonic crystal film layer is a spherical photonic crystal film layer or a non-spherical photonic crystal film layer.

[0028] This specific embodiment provides a heterojunction photonic crystal superprism, which is obtained by stacking and solidifying the above-mentioned photonic crystal composite film layers. The heterojunction photonic crystal superprism comprises, from top to bottom: a first photonic crystal composite film layer, a heterojunction layer, and a second photonic crystal composite film layer; and from top to bottom: a first glass layer, a spherical photonic crystal film layer, a heterojunction layer, a non-spherical photonic crystal film layer, and a second glass layer; the spherical photonic crystal film layer is a spherical photonic crystal gradient ordered film layer, and the non-spherical photonic crystal film layer is a non-spherical photonic crystal gradient ordered film layer; the optical testing of the superprism adopts an oblique incidence method, with an incidence angle range of 20°~45°, the incident light propagation direction is perpendicular to the film layer gradient direction, and the refraction angle range of the superprism reaches 55°-60°. Traditional single-structure superprisms are prone to overlapping of deflection angles for different wavelengths, resulting in reduced resolution. However, the linear gradient distribution ensures that the deflection angles of different wavelengths correspond precisely and linearly to the lattice period. Long wavelengths are deflected in the large period region (entrance side) and short wavelengths are deflected in the small period region (exit side). The difference in deflection angles between wavelengths is amplified by the gradient, avoiding overlap.

[0029] Furthermore, this specific embodiment also proposes a method for preparing the above-mentioned photonic crystal composite film, including the following steps: bonding the chip to a glass substrate to form a closed microchannel, and injecting spherical particle suspension or non-spherical particle suspension into the closed microchannel to obtain a spherical photonic crystal film supported by a glass layer or a non-spherical photonic crystal film supported by a glass layer.

[0030] Furthermore, this specific embodiment also proposes a method for fabricating the above-mentioned heterojunction photonic crystal superprism, including the following steps: S1. The chip is bonded to a glass substrate to form a closed microchannel. A spherical particle suspension or a non-spherical particle suspension is injected into the closed microchannel to obtain a spherical photonic crystal film layer supported by a first glass layer or a non-spherical photonic crystal film layer supported by a second glass layer. The channel of the chip gradually narrows linearly along its length. The injection flow rate of the spherical particle suspension or non-spherical particle suspension into the closed microchannel is 0.05~0.1μL / min. After injection, the channel is filled with suspension and a stable gas-liquid interface is formed. The channel is then cured at 35-40℃ for 4-6 hours. S2. The spherical photonic crystal film layer supported by the first glass layer and the non-spherical photonic crystal film layer supported by the second glass layer are hydrophilically modified. Then, the bonding surfaces of the two are stacked and baked at 50-60℃ for 2-3 hours to solidify and form a heterojunction layer to obtain the heterojunction photonic crystal superprism. The hydrophilic modification includes: placing the spherical photonic crystal film layer supported by the first glass layer or the non-spherical photonic crystal film layer supported by the second glass layer into an oxygen plasma processor and processing it at 100-120W power for 25-30 seconds.

[0031] In some embodiments, the spherical particle suspension is prepared by the following steps: adding SiO2 spherical microspheres to an ethanol-water solvent, then adding SDBS dispersant and sonicating, followed by degassing to remove bubbles to obtain the spherical particle suspension; the non-spherical particle suspension is prepared by the following steps: adding SiO2 sheet-like particles to an ethanol-water solvent, then adding SDBS dispersant and sonicating, followed by degassing to remove bubbles to obtain the non-spherical particle suspension; in the spherical particle suspension or the non-spherical particle suspension, the content of the SiO2 spherical microspheres or the SiO2 sheet-like particles in the suspension is 0.3wt%-0.5wt%; the content of the SDBS dispersant in the suspension is 0.01wt%-0.02wt%.

[0032] Other beneficial effects: 1. This invention employs a weak sealing process between PDMS and glass (physical bonding + medical tape reinforcement), which ensures that the microchannel is closed and leak-proof, while also enabling the non-destructive peeling and reuse of the PDMS chip, thus solving the problem that the chip cannot be peeled off using traditional strong sealing processes.

[0033] 2. By using gas-liquid interface self-assembly to replace solid interface self-assembly, SiO2 particles are driven to spontaneously form a hexagonal close-packed ordered film by means of interfacial tension, which completely solves the problem of random accumulation of SiO2 particles at the solid interface, and the film formation rate is 100%.

[0034] 3. By leveraging the shear force and interfacial tension gradient effects of microfluidic linear gradient channels, linear gradient control of the lattice period of photonic crystal films can be achieved without the need for additional gradient control devices, resulting in a simple and precise process.

[0035] 4. By employing a stacking method of separate preparation and hydrogen bonding, gapless stacking of gradient films of spherical and non-spherical photonic crystals can be achieved. The gradient parameters of the two films can be controlled separately, enabling precise control of gradient matching and effectively improving the refraction angle range and wavelength adaptability of the superprism.

[0036] 5. The entire process involves no complex operations such as lifting or photolithography. All process steps are routine laboratory microfluidic and self-assembly operations. The equipment requirements are low, the fault tolerance is high, and it is suitable for large-scale preparation.

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0038] In this invention, the terms "some embodiments," "this embodiment," and examples are used to describe a subset of all possible embodiments. However, it is understood that "some embodiments" can be the same subset or different subsets of all possible embodiments and can be combined with each other without conflict.

[0039] If the application documents contain similar descriptions such as "first / second", the following explanation shall be added: In the following description, the terms "first / second / third" are used only to distinguish similar objects and do not represent a specific ordering of objects. It is understood that "first / second / third" may be interchanged in a specific order or sequence where permitted, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein.

[0040] In this embodiment, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, object A and / or object B can represent three situations: object A exists alone, object A and object B exist simultaneously, and object B exists alone.

[0041] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0042] Example 1 Combination Figure 2 This embodiment proposes a photonic crystal composite film layer, including a first glass layer 21 and a spherical photonic crystal film layer 22.

[0043] This embodiment also proposes a photonic crystal composite film layer including a second glass layer 25 and a non-spherical photonic crystal film layer 24.

[0044] This embodiment also proposes a heterojunction photonic crystal superprism, which includes, from top to bottom: a first glass layer 21, a spherical photonic crystal film layer 22, a heterojunction layer 23, a non-spherical photonic crystal film layer 24, and a second glass layer 25; the spherical photonic crystal film layer 22 is a gradient-ordered spherical photonic crystal film layer, and the non-spherical photonic crystal film layer 24 is a gradient-ordered non-spherical photonic crystal film layer.

[0045] This embodiment also proposes a method for fabricating the above-mentioned heterojunction photonic crystal superprism, including the following steps: S1. Preparation of particle suspension: SiO2 spherical microspheres with a particle size of 200 nm and monodispersity ≥98% (purity 99.9%), and SiO2 rod-shaped non-spherical particles with an aspect ratio of 3 and uniform particle size distribution (diameter 50 nm, length 150 nm) were selected. A mixed solvent of ethanol and deionized water (ethanol to deionized water volume ratio 1:1, ethanol being analytical grade, deionized water resistivity ≥18.2 MΩ·cm) was added, and after magnetic stirring for 30 min, a suspension with a SiO2 spherical microsphere mass concentration of 0.3 wt% was prepared. A suspension of SiO2 rod-shaped non-spherical particles with a mass concentration of 0.3wt% was prepared. 0.01wt% sodium dodecylbenzenesulfonate (SDBS) was precisely added to each suspension as a dispersant. The suspension was ultrasonically dispersed at 80W power for 30min (ultrasonic frequency 40kHz, intermittent ultrasonication, 5s working and 2s stopping). Then, it was placed in a vacuum chamber with a vacuum degree of -0.09MPa for 5min to completely remove air bubbles in the suspension. After standing for 10min, it was ready for use. The suspension of spherical particles and non-spherical particles were obtained without significant particle sedimentation.

[0046] S2. Chip and Substrate Pretreatment: A silicon template was prepared using SU-8 2025 photoresist. After pre-baking, exposure, post-baking, and development, a linear gradient straight-channel structure was obtained (channel inlet width 200μm, outlet width 50μm, channel height 20μm, length 2cm, channel sidewall perpendicularity ≥90°). PDMS prepolymer and curing agent were mixed at a mass ratio of 10:1 and magnetically stirred for 20 minutes until homogeneous. The mixture was then placed in a vacuum chamber for 30 minutes to remove air bubbles. The mixture was then poured onto the silicon template surface and cured at 80℃ for 2 hours. After natural cooling to room temperature, the PDMS gradient chip was slowly peeled off along the edge of the silicon template using pointed tweezers, retaining the chip's original hydrophobic surface (water contact angle ≈110°). No oxygen plasma treatment was performed. The inner walls of the chip channels were wiped with lint-free paper to remove residual impurities before use. Figure 1 The chip's channel 12 has a linearly narrowing width along its length. The channel inlet 11 has a width of 200 μm, the outlet 13 has a width of 50 μm, the channel height is 20 μm, the length is 2 cm, and the verticality of the channel sidewall is ≥90°. A 2 cm × 2 cm quartz glass substrate was selected and ultrasonically cleaned for 15 min each with acetone, ethanol, and deionized water (power 100 W, frequency 40 kHz). The surface moisture was dried with a nitrogen gun (flow rate 5 L / min), and the substrate was placed in an oxygen plasma treatment instrument and treated at 100 W power for 30 s. After removal, the water contact angle was immediately measured to be 8°, which meets the requirements for hydrophilic modification. The substrate was then sealed and stored for later use.

[0047] S3. Preparation of Non-Spherical Gradient Film: The channel surface of the native hydrophobic PDMS chip is attached to the surface of a hydrophilic quartz glass substrate with the channel side facing each other. The chip is gently pressed evenly around its perimeter with a finger (approximately 0.05 MPa). This utilizes interfacial capillary force and atmospheric pressure to form closed microchannels. Microscopic observation confirms that the channels are gap-free and leak-free. Medical transparent tape is applied to the edges of the chip, leaving a 1.5 mm margin unattached for easy peeling later. The tape edges are firmly pressed to prevent chip warping due to pressure changes during injection. A suspension of non-spherical rod-shaped SiO2 particles is loaded into a 1 mL syringe, connected to a micro-injection pump, and the syringe needle is aligned and sealed with the PDMS chip inlet. Injection is performed at a rate of 0.08 μL / min. Liquid was injected into the channel at a high flow rate. During injection, the chip side was gently tapped with tweezers (approximately twice per second) to help remove residual air bubbles until the channel was completely filled with suspension. Microscopic observation revealed a smooth and stable gas-liquid interface at the top of the channel (no significant fluctuations were observed between the hydrophobic inner wall of the PDMS and the suspension). The injection pump was then turned off and the syringe was secured. The sealed chip and glass substrate were placed on a clean bench (room temperature 25℃, humidity 45%) and left to stand for 5 hours, avoiding vibration. Rod-shaped SiO2 particles spontaneously migrated to the interface under the influence of gas-liquid interfacial tension, gradually forming a hexagonal close-packed ordered film. Due to the channel width gradient effect, the particle packing density at the narrow channel outlet reached 1.2 × 10⁻⁶. 12 pcs / cm 2 The lattice period is approximately 220 nm, and the particle packing density at the wide entrance channel is 5.8 × 10⁻⁶. 11 pcs / cm 2 The lattice period is approximately 350 nm, achieving linear gradient control of the film's lattice period. The self-assembled sample is placed in a vacuum drying oven at 38°C and -0.08 MPa for 6 hours to slowly remove the ethanol-water solvent, allowing the particle film to firmly bond to the glass substrate via van der Waals forces, preventing shrinkage and cracking. After drying, the sample is removed and cooled to 25°C. The surrounding medical tape is removed, and the PDMS chip is gently peeled off at a constant speed of 0.3 cm / min along the substrate edge using pointed tweezers, yielding a non-spherical photonic crystal gradient-ordered film supported by a second glass layer. The film has a uniform thickness (approximately 200 nm) and is undamaged. After wiping the inner wall of the channel with lint-free paper, the peeled PDMS chip can be reused 3-5 times. Following this procedure, the rod-shaped SiO2 particle suspension is replaced with a spherical SiO2 particle suspension, with all other process parameters and steps identical, to prepare a spherical photonic crystal gradient-ordered film supported by a first glass substrate.

[0048] S4. Heterojunction Preparation: The two films with glass substrates obtained in step S3 (i.e., the non-spherical photonic crystal gradient-ordered film supported by the second glass layer and the spherical photonic crystal gradient-ordered film supported by the first glass substrate) are placed in an oxygen plasma treatment instrument and treated at 100W power for 30s to generate hydroxyl groups (-OH) on the bonding surface of the two films, thereby improving the surface hydrophilicity. The bonding surface of the modified spherical gradient-ordered film is then bonded face-to-face to the bonding surface of the non-spherical gradient-ordered film, and the film surface is gently pressed with a clean glass slide (approximately 0.02MPa). The air between the two films is squeezed out slowly from the center outwards, and the hydrogen bonding of the hydroxyl groups on the surface of the two films is used to achieve a gapless adhesion. The stacked structure is placed in a vacuum drying oven and baked at 60°C for 2 hours to strengthen the hydrogen bond strength, so that the two films are firmly bonded to form a heterojunction layer. Finally, a heterojunction photonic crystal superprism is obtained, which includes a glass substrate layer (i.e., the first glass layer), a spherical photonic crystal gradient ordered film layer, a heterojunction layer, a non-spherical photonic crystal gradient ordered film layer, and a glass substrate layer (i.e., the second glass layer) from top to bottom.

[0049] Combination Figure 3 In the heterojunction photonic crystal superprism, the spherical SiO2 particles in the spherical photonic crystal gradient ordered film are hexagonal unit cells, while the SiO2 particles in the non-spherical photonic crystal gradient ordered film are parallelogram unit cells, forming a heterojunction interface between the two.

[0050] Optical performance testing: combined Figure 4 The optical performance testing equipment includes an angular resolution spectrometer (3) and a microfluidic device (4). The fabricated gradient heterojunction photonic crystal superprism is fixed on the optical testing platform. A near-infrared laser is used as the light source, and near-infrared light in the 800~1500nm wavelength range is irradiated onto the upper surface of the spherical gradient ordered film at a 30° incident angle, ensuring that the incident light propagation direction is perpendicular to the gradient direction of the film layer. A spectrometer (detection accuracy 0.1nm) and a CCD camera (2048×2048 pixels) are placed on the side of the heterojunction (perpendicular to the glass substrate) to simultaneously collect the emitted light and record the wavelength-deflection angle correspondence. The test results show that the superprism has a refraction angle range of 60°, which is 57.9% higher than that of the traditional single spherical SiO2 photonic crystal superprism (refraction angle range 38°, both using the same single homogeneous spherical SiO2 structure). It can achieve effective spectral splitting in the entire 800~1500nm wavelength range without obvious spectral blind zone, and the film layer has no scattering loss, exhibiting excellent optical stability.

[0051] Example 2 This embodiment proposes a heterojunction photonic crystal superprism, which includes, from top to bottom: a first glass layer, a spherical photonic crystal film layer, a heterojunction layer, a non-spherical photonic crystal film layer, and a second glass layer; the spherical photonic crystal film layer is a spherical photonic crystal gradient ordered film layer, and the non-spherical photonic crystal film layer is a non-spherical photonic crystal gradient ordered film layer.

[0052] This embodiment also proposes a method for fabricating the above-mentioned heterojunction photonic crystal superprism, including the following steps: S1. Preparation of Particle Suspensions: SiO2 spherical microspheres (99.9% purity) with a particle size of 300 nm and monodispersity ≥97%, and SiO2 sheet-like non-spherical particles (120 nm diameter, 30 nm thickness) with an aspect ratio of 4 and uniform thickness were selected. A mixed solvent of ethanol and deionized water (ethanol to deionized water volume ratio 1:1, ethanol being analytical grade, and deionized water resistivity ≥18.2 MΩ·cm) was added to each suspension. After magnetic stirring for 40 min, suspensions with a mass concentration of 0.5 wt% for both SiO2 spherical microspheres and SiO2 rod-like non-spherical particles were prepared (for high-concentration suspensions, the stirring time needs to be extended to ensure uniform particle dispersion). 0.01 wt% of the particle size was added to each suspension. SDBS dispersant was ultrasonically dispersed at 100W power for 30 minutes (ultrasonic frequency 40kHz, intermittent ultrasonication, 6 seconds working and 3 seconds stopping). Then it was placed in a vacuum chamber with a vacuum degree of -0.095MPa for 5 minutes to remove air bubbles in the suspension. After standing for 15 minutes, it was ready for use. The particle size distribution was measured by a laser particle size analyzer and the particle dispersion coefficient was ≤0.1, with no obvious agglomeration. S2. Chip and Substrate Pretreatment: Using the same SU-8 photoresist silicon template as in Example 1, a PDMS gradient chip (entrance width 200μm, exit width 50μm, channel height 20μm, length 2cm) was prepared. The original hydrophobic surface of the chip was retained. After wiping the inner wall of the channel with lint-free paper, it was ready for use. The channel of the chip gradually narrows linearly along the length direction. The channel entrance width of the chip is 200μm, the exit width is 50μm, the channel height is 20μm, the length is 2cm, and the verticality of the channel sidewall is ≥90°. A 2cm×2cm quartz glass substrate was selected and treated according to the cleaning process of Example 1 (acetone, ethanol, and deionized water, each ultrasonicated for 15min). After drying with a nitrogen gun, it was placed in an oxygen plasma treatment instrument and treated at 100W power for 30s. The water contact angle was detected to be 7°, which met the hydrophilic modification standard. It was sealed and stored in the dark to avoid the loss of surface hydroxyl groups. S3. Preparation of Non-Spherical Gradient Film: A native hydrophobic PDMS chip was bonded face-to-face to the surface of a hydrophilic quartz glass substrate. The chip was gently pressed around its perimeter (approximately 0.05 MPa) to form a closed microchannel. After microscopic observation confirmed the absence of gaps and leakage, medical tape was used to secure the chip, leaving a 1 mm corner for peeling. A suspension of non-spherical sheet-like SiO2 particles was loaded into a 1 mL syringe and connected to a micro-injection pump. Due to the high concentration of the suspension, a low injection rate of 0.05 μL / min was used. During injection, the sides of the chip were continuously tapped to ensure complete removal of air bubbles from the channels until the channels were filled with suspension and a stable gas-liquid interface was formed. The sealed sample was placed on a clean bench (room temperature 26℃, humidity 40%) and allowed to stand for 6 hours to allow the SiO2 sheet-like particles to fully migrate to the gas-liquid interface and complete hexagonal close-packed self-assembly. Microscopic observation showed that the particle packing density at the narrow channel reached 1.5 × 10⁻⁶. 12 pcs / cm 2 The lattice period is approximately 280 nm, and the particle packing density in the wide channels is 6.2 × 10⁻⁶. 11 pcs / cm 2 The lattice period is approximately 420 nm, with a uniform gradient distribution. The sample was placed in a vacuum drying oven at 40°C and a vacuum of -0.085 MPa for 6 hours. The high temperature parameter accelerates the evaporation of the solvent in the high-concentration suspension while preventing film cracking. After drying, the sample was cooled to 25°C at room temperature, the medical tape was removed, and the PDMS chip was peeled off at a low speed of 0.2 cm / min to obtain a non-spherical photonic crystal gradient-ordered film supported by a second glass layer. The film had good integrity and a surface flatness of ≤5 nm. Following the same procedure, the sheet-like SiO2 particle suspension was replaced with a spherical SiO2 particle suspension, with all other process parameters and operating steps remaining identical, to prepare a spherical photonic crystal gradient-ordered film supported by a first glass layer.

[0053] S4. Heterojunction Fabrication: The two films with glass substrates obtained in step S3 (i.e., the non-spherical photonic crystal gradient-ordered film supported by the second glass layer and the spherical photonic crystal gradient-ordered film supported by the first glass substrate) are modified with oxygen plasma (100W, 30s). Immediately after removal, the spherical film bonding surface is placed face-to-face with the non-spherical film bonding surface. A glass slide is used to gently press and degas from the center outwards, ensuring a gapless bonding between the two films. The stacked structure is placed in a vacuum drying oven and baked at 60℃ for 2 hours to enhance hydrogen bonding and stabilize the heterostructure, ultimately forming a heterojunction layer to obtain the target photonic crystal superprism. The two films exhibit excellent bonding strength with no peeling. The final product is a heterojunction photonic crystal superprism consisting of a glass substrate layer (i.e., the first glass layer), a spherical photonic crystal gradient-ordered film, a heterojunction layer, a non-spherical photonic crystal film, and a glass substrate layer (i.e., the second glass layer), from top to bottom; this is the target photonic crystal superprism.

[0054] Optical performance testing: The superprism was fixed on an optical testing platform, and a visible light laser was used as the light source. Visible light in the 400~760nm wavelength range was irradiated onto the upper surface of the spherical gradient film at an incident angle of 40°, with the incident light propagation direction perpendicular to the gradient direction of the film. The outgoing light was collected by a high-precision spectrometer and a CCD camera, and the wavelength-deflection angle correspondence and spectral resolution were detected. The test results show that the superprism has a refraction angle range of 55°, which is 71.9% higher than that of a traditional single non-spherical SiO2 photonic crystal superprism (refractive angle range of 32°). In the 400~760nm visible light band, the spectral resolution reaches 5nm, which is better than that of traditional superprisms (conventional resolution of 8~10nm). Moreover, there is no spectral distortion in the short-wavelength blue light (400~450nm) band, making it suitable for high-precision visible light spectral detection scenarios.

[0055] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A photonic crystal composite film, characterized in that, It includes a bonded glass layer and a photonic crystal film layer; the photonic crystal film layer is a spherical photonic crystal film layer or a non-spherical photonic crystal film layer.

2. A heterojunction photonic crystal superprism, characterized in that, The heterojunction photonic crystal superprism, obtained by superimposing and solidifying the photonic crystal composite film layer as described in claim 1, comprises, from top to bottom: a first photonic crystal composite film layer, a heterojunction layer, and a second photonic crystal composite film layer.

3. The heterojunction photonic crystal superprism according to claim 2, characterized in that... The first photonic crystal composite film layer includes a first glass layer and a spherical photonic crystal film layer, and the second photonic crystal composite film layer includes a second glass layer and a non-spherical photonic crystal film layer; the heterojunction photonic crystal superprism includes, from top to bottom, a first glass layer, a spherical photonic crystal film layer, a heterojunction layer, a non-spherical photonic crystal film layer and a second glass layer.

4. The heterojunction photonic crystal superprism according to claim 3, characterized in that, The spherical photonic crystal film is a gradient-ordered spherical photonic crystal film; and / or, the non-spherical photonic crystal film is a gradient-ordered non-spherical photonic crystal film.

5. A method for preparing the photonic crystal composite film according to claim 1, characterized in that, The process includes the following steps: bonding the chip to a glass substrate to form a closed microchannel, and injecting either a spherical particle suspension or a non-spherical particle suspension into the closed microchannel to obtain a spherical photonic crystal film layer supported by a glass layer or a non-spherical photonic crystal film layer supported by a glass layer.

6. A method for fabricating a heterojunction photonic crystal superprism according to any one of claims 2-4, characterized in that, Includes the following steps: S1. The chip is bonded to the glass substrate to form a closed microchannel. Spherical particle suspension or non-spherical particle suspension is injected into the closed microchannel to obtain a spherical photonic crystal film layer supported by the first glass layer or a non-spherical photonic crystal film layer supported by the second glass layer. S2. The spherical photonic crystal film layer supported by the first glass layer and the non-spherical photonic crystal film layer supported by the second glass layer are hydrophilically modified, and then the bonding surfaces of the two are stacked and solidified to form a heterojunction layer to obtain the heterojunction photonic crystal superprism.

7. The method for fabricating a heterojunction photonic crystal superprism according to claim 6, characterized in that, In step S1, the channel of the chip gradually narrows linearly along its length to obtain a spherical photonic crystal gradient ordered film layer supported by a first glass layer or a non-spherical photonic crystal gradient ordered film layer supported by a second glass layer.

8. The method for fabricating a heterojunction photonic crystal superprism according to claim 6, characterized in that, In step S1, the spherical particle suspension is prepared by the following steps: adding SiO2 spherical microspheres to an ethanol-water solvent, then adding SDBS dispersant and sonicating, followed by degassing to remove bubbles to obtain the spherical particle suspension; and / or, the non-spherical particle suspension is prepared by the following steps: adding SiO2 sheet-like particles or SiO2 rod-like particles to an ethanol-water solvent, then adding SDBS dispersant and sonicating, followed by degassing to remove bubbles to obtain the non-spherical particle suspension.

9. The method for fabricating a heterojunction photonic crystal superprism according to claim 8, characterized in that, In the spherical particle suspension or the non-spherical particle suspension, the content of the SiO2 spherical microspheres or the SiO2 sheet particles in the suspension is 0.3wt%-0.5wt%; and / or, the content of the SDBS dispersant in the suspension is 0.01wt%-0.02wt%.

10. The method for fabricating a heterojunction photonic crystal superprism according to claim 6, characterized in that, In step S2, the hydrophilic modification includes: placing the spherical photonic crystal film layer supported by the first glass layer or the non-spherical photonic crystal film layer supported by the second glass layer into an oxygen plasma treatment instrument and treating it at a power of 100-120W for 25-30s; and / or, in step S2, the curing includes: baking at 50-60℃ for 2-3h; and / or, in step S1, injecting the spherical particle suspension or non-spherical particle suspension into the closed microchannel at a flow rate of 0.05~0.1μL / min; and / or, in step S1, after injecting the spherical particle suspension or non-spherical particle suspension, filling the channel with suspension and forming a stable gas-liquid interface, and then continuing to cure at 35-40℃ for 4-6h.

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