Photonic crystal structure for optimizing energy band measurement and preparation method
By introducing geometric scattering units into the photonic crystal, the problem of insufficient scattered light flux in dark field angle-resolved spectra was solved, thus optimizing the bandgap measurement of the photonic crystal and enhancing the measurement effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TAIYUAN UNIVERSITY OF TECHNOLOGY
- Filing Date
- 2026-01-21
- Publication Date
- 2026-05-05
AI Technical Summary
In traditional dark-field angle-resolved spectroscopy, the scattered light flux of a photonic crystal is much lower than that of the transmitted and reflected signals, resulting in low measurement sensitivity and efficiency, which affects the accuracy of photonic crystal bandgap measurements.
Artificial geometric scattering units, such as nanospheres or etched holes, are introduced into the photonic crystal structure. Randomly distributed scattering sources are then set on the surface or inside the photonic crystal through photolithography or spray doping processes to enhance the intensity of scattered light.
It significantly improves the measurement effect of dark field angle-resolved spectroscopy, enhances the observation of photonic crystal band patterns, and improves the sensitivity and efficiency of measurement.
Smart Images
Figure CN121978780A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of integrated photonic device technology, specifically relating to an optimized photonic crystal structure and preparation method for bandgap measurement. By introducing artificial structural modifications into the photonic crystal, the dark field measurement effect of the photonic crystal bandgap is enhanced. Background Technology
[0002] Photonic crystals are artificial optical materials with periodic dielectric structures, widely used in optical communication, sensing, and lasers. Their core value lies in their unique photonic band structure, essentially a distribution of frequency ranges where photons are "allowed" and "forbidden" to propagate within a periodic dielectric structure. Generally, these "allowed" and "forbidden" propagation areas are referred to as the allowed band and band gap. Utilizing the properties of the allowed and band gaps, desired photonic devices can be fabricated. For example, electromagnetic shielding and anti-interference devices utilize the photonic band gap to "completely suppress" electromagnetic waves of specific frequencies, allowing for the design of miniaturized electromagnetic shielding materials. In summary, through precise structural design, such as adjusting factors like period and shape, precise control of photon propagation can be achieved.
[0003] The energy band structure of photonic crystals can be measured using methods such as transmission / reflection angle-resolved spectroscopy, grating coupling, and near-field optical microscopy. Traditionally, bright-field transmission or reflection angle-resolved spectroscopy is used to study the dispersive properties and band structure of photonic crystals. However, in actual measurements, the collected angle-resolved spectral data contains both the resonant response information of the photonic crystal and the incident light signal. The superposition of these different signals interferes with the results of the photonic crystal band measurement, ultimately preventing the characterized band from accurately revealing the intrinsic mode characteristics of the photonic crystal. To avoid this band measurement problem caused by the presence of incident light, dark-field angle-resolved spectroscopy can be used to prevent incident light from entering the spectral detector, thereby achieving accurate measurement of the intrinsic energy bands of the photonic crystal. However, since dark-field angle-resolved measurement methods rely on light scattering, and the structure of conventional photonic crystals is very complete, the scattered light flux is much lower than that of conventional transmission and reflection signals. Therefore, the dark-field signal measured is usually very weak. This inherent limitation restricts the sensitivity and efficiency of dark field angle resolution in measuring the intrinsic band structure of photonic crystals, hindering subsequent analysis and application of the optical properties of photonic crystals. Summary of the Invention
[0004] To address the aforementioned technical problem that weak dark field signals limit measurement sensitivity and efficiency, this invention proposes an optimized photonic crystal structure and preparation method for bandgap measurement. By introducing artificial structural modifications, the number of scattering sources inside the photonic crystal can be increased, thereby enhancing the dark field measurement effect of the photonic crystal bandgap and achieving optimization of photonic crystal bandgap measurement.
[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a photonic crystal structure for optimized bandgap measurement, comprising: a substrate layer and a photonic crystal thin film layer disposed on the substrate layer. The photonic crystal thin film layer is provided with periodic photonic crystals and a modification structure, wherein the modification structure comprises a plurality of geometrically scattering units randomly distributed on the outer periphery of the photonic crystal thin film layer.
[0006] The modified structure is the same as the photonic crystal thin film material, and is set on the substrate layer by photolithography and photonic crystal etching simultaneously.
[0007] The geometric scattering unit of the modified structure is a nanosphere, which is set on the surface of the photonic crystal by spin coating or spray doping process.
[0008] The geometric scattering unit is circular, elliptical, square, triangular, or polygonal, and the photonic crystal is a one-dimensional or two-dimensional photonic crystal.
[0009] The photonic crystal structure for optimized bandgap measurement further includes a substrate layer, wherein the substrate layer is disposed on the substrate layer, the substrate layer is made of titanium dioxide, and the substrate layer is a conductive ITO glass or a silicon oxide substrate.
[0010] The diameter of the geometric scattering unit is 3-20 times the period of the photonic crystal in the photonic crystal thin film layer.
[0011] Furthermore, this invention also provides a method for preparing a photonic crystal structure for optimized bandgap measurement, comprising the following steps: Step 1: Determine the geometric parameters of the photonic crystal thin film layer, including the geometric parameters of the photonic crystal and the geometric scattering unit; Step 2: Determine the photolithography pattern based on the geometric parameters of the photonic crystal thin film layer; Step 3: Spin-coat photoresist onto the substrate, dry it, and then perform electron beam lithography on the photoresist using a photolithography pattern, followed by development and fixing to finally obtain a photonic crystal thin film layer containing the modified structure.
[0012] Furthermore, this invention also provides another method for preparing a photonic crystal structure optimized for bandgap measurement, comprising the following steps: Step 1: Determine the geometric parameters of the photonic crystal thin film layer, including the geometric parameters of the photonic crystal and the geometric scattering unit (5); Step 2: Determine the photolithography pattern based on the geometric parameters of the photonic crystal thin film layer; Step 3: Spin-coat photoresist onto the substrate, dry it, and then develop and fix the photoresist using a photolithography pattern. Step 4: Deposit photonic crystal material into the periodic structure formed by photoresist to form a photonic crystal thin film layer containing the modified structure; Step 5: Remove the photoresist to finally form a photonic crystal structure with optimized bandgap measurements.
[0013] In step three, PMMA A4 photoresist is spin-coated using a spin coater with spin-coating parameters of 3000 rad / s and 60 s, and then dried at 160°C for 10 min.
[0014] Compared with the prior art, the present invention has the following advantages: This invention discloses a photonic crystal structure and its preparation method for optimizing band structure measurements. By introducing a modification structure into the periodic structure of the photonic crystal, the intensity of scattered light is increased. In dark-field angle-resolved measurements, after the incident light excites the overall photonic crystal structure signal, the intensity of the excited scattered light is uniformly enhanced in all directions due to the randomly generated modification structure introduced on the periphery of the photonic crystal. When collecting the scattered light intensity in the middle of the photonic crystal (excluding the peripheral modification structure), the dark-field angle-resolved spectrum effect can be effectively improved. Experiments have confirmed that the band structure of the photonic crystal with the introduced modification structure can clearly show the band pattern. Therefore, this invention lays the foundation for subsequent research on the band structure of photonic crystals. Attached Figure Description
[0015] Figure 1 This is a surface schematic diagram of a photonic crystal structure for optimized bandgap measurement provided in Embodiment 1 of the present invention; wherein, (a) corresponds to a hollow structure and (b) corresponds to a nanosphere. Figure 2 This is a schematic cross-sectional view of a photonic crystal structure for optimized bandgap measurement provided in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of a repeating periodic structural unit on the surface of a photonic crystal structure for optimized bandgap measurement, provided in Embodiment 1 of the present invention. Figure 4 A local SEM image of the unmodified photonic crystal structure; Figure 5 A reflection microscope image of a photonic crystal structure for optimized bandgap measurement provided in Embodiment 1 of the present invention; Figure 6 This is a local SEM image of a photonic crystal structure for optimized bandgap measurement, provided in Embodiment 1 of the present invention. Figure 7 The energy band diagram of the photonic crystal before optimization; Figure 8 This is a band diagram of a photonic crystal structure for optimized band measurement, provided in Embodiment 1 of the present invention.
[0016] The meanings of the labels in the figures are as follows: 1. Substrate; 2. Substrate; 3. Photonic crystal thin film; 5. Geometric scattering unit; L1: Substrate thickness; L2: Photonic crystal thin film thickness; Ax: Period of the photonic crystal in the x-direction; Ay: Period of the photonic crystal in the y-direction; Wx: Width of the repeating unit in the photonic crystal along the x-axis; Wy: Width of the repeating unit in the photonic crystal along the y-axis. Detailed Implementation
[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0018] Example 1 like Figure 1-3 As shown, Embodiment 1 of the present invention provides a photonic crystal structure for optimizing bandgap measurement, comprising: a substrate layer 2 and a photonic crystal thin film layer 3 disposed on the substrate layer 2, characterized in that the photonic crystal thin film layer 3 is provided with periodic photonic crystals and a modification structure, the modification structure comprising a plurality of geometrically oriented scattering units 5 randomly distributed on the outer periphery of the photonic crystal thin film layer 3.
[0019] Specifically, in this embodiment, the modified structure is made of the same material as the photonic crystal thin layer 3, and is set on the substrate layer 2 by photolithography and synchronous etching of the photonic crystal.
[0020] Preferably, in this embodiment, the diameter of the geometric scattering unit 5 is 3-20 times the period of the photonic crystal in the photonic crystal thin film layer 3.
[0021] In this embodiment, the material of the substrate layer 2 can be selected from transparent materials of different wavelengths, such as magnesium fluoride (MgF2) and silicon dioxide (SiO2) in the ultraviolet band; titanium dioxide (TiO2) and silicon dioxide (SiO2) in the visible light band; and silicon dioxide (SiO2) and aluminum oxide (Al2O3) in the near-infrared band.
[0022] In this embodiment, the photonic crystal thin film layer 3 is composed of a high dielectric constant material, including titanium dioxide (TiO2, n≈2.5), single-crystal silicon (Si, n≈3.45), gallium nitride (GaN, n≈2.5), etc. Figure 2 As shown in (a) and (b), in this case, the geometric scattering unit 5 in the modified structure can be a hollow structure with a diameter larger than the period of the photonic crystal, such as... Figure 2 As shown in (a); the geometric scattering unit 5 can also be a nanosphere particle, such as Figure 2As shown in (b). Furthermore, the diameter of the nanospheres can also be larger than the size W of the photonic crystal. X .
[0023] Furthermore, the photonic crystal thin film layer 3 can also be constructed by etching a hole structure on a low dielectric constant material using photoresist. Commonly used low dielectric constant materials include silicon dioxide (SiO2, n≈1.46), polymethyl methacrylate (PMMA, n≈1.5), and polystyrene (PS, n≈1.6). Figure 2 As shown in (c) and (d), in this case, the geometric scattering unit 5 in the modified structure can be a hollow structure with a diameter larger than the period of the photonic crystal, such as... Figure 2 As shown in (c); the geometric scattering unit 5 can also be a nanosphere particle, such as Figure 2 As shown in (d). Furthermore, the diameter of the nanospheres can also be larger than the pore diameter.
[0024] It is important to note that in this embodiment, the refractive indices of the substrate material and the photonic crystal thin film material must be matched to avoid excessive energy loss.
[0025] In this embodiment, the photonic crystal is obtained by periodically etching holes (two-dimensional photonic crystal) or grooves (one-dimensional photonic crystal) on the photonic crystal thin film layer 3. In this embodiment, the modification structure can be introduced in two ways: Method 1: Introduced through photolithography design. On the photolithography pattern used to prepare the photonic crystal, in addition to the target pattern, geometric shapes are drawn in the surrounding area, thereby forming an embedded pattern in the lattice to act as a scattering source; then the geometric scattering unit 5 is a geometrically etched structure randomly distributed on the outer periphery of the photonic crystal thin film layer 3. Method 2: Introduced through post-processing. After the photonic crystal thin film is prepared, external scattering units (such as gold nanospheres) are transferred and attached to the film surface using spin coating or spray doping processes to simulate randomly distributed scattering sources. Therefore, in this embodiment, the geometric scattering unit 5 of the modification structure can also be a nanosphere, such as a gold nanosphere, which is set on the surface of the photonic crystal through spin coating or spray doping processes.
[0026] Furthermore, in this embodiment, the geometric scattering unit 5 is circular, elliptical, square, triangular, or polygonal, and the photonic crystal is a one-dimensional photonic crystal or a two-dimensional photonic crystal.
[0027] In addition, the photonic crystal structure for optimized bandgap measurement in this embodiment also includes a substrate layer 1, wherein a substrate layer 2 is disposed on the substrate layer 1, the substrate layer 2 is made of titanium dioxide, and the substrate layer 1 is a conductive ITO glass or a silicon oxide substrate.
[0028] In this embodiment, the geometric parameters of the photonic crystal thin film layer 3 include a, P, L1, L2, Ax, Ay and Wx, Wy, where a represents the size of the modified structure; P represents the size of the photonic crystal array; L1 represents the thickness of the substrate 2; L2 represents the thickness of the photonic crystal thin film layer 3; Ax represents the period of the photonic crystal in the x-direction; Ay represents the period of the photonic crystal in the y-direction; Wx represents the width of the repeating unit within the photonic crystal along the x-axis; and Wy represents the width of the repeating unit within the photonic crystal along the y-axis. See also... Figure 1 and Figure 3 (The figures are for illustrative purposes only and do not limit the shape of the photonic crystal thin film pattern.) The selection of these geometric parameters is determined by the energy band structure of the photonic crystal, and the parameters are determined by calculation after the material and shape are selected. The aforementioned photonic crystal periodic structure pattern is a one-dimensional photonic periodic structure pattern and / or a two-dimensional photonic crystal periodic structure pattern.
[0029] Furthermore, the geometric parameters of the photonic crystal are a = 2 μm, P = 200 μm, L1 = 100 nm, L2 = 200 nm, Ax = 460 nm, Ay = 0 nm and Wx = 300 nm, Wy = 0 nm.
[0030] like Figure 4 As shown, this is a local SEM image of a photonic crystal with an unmodified structure. Figure 5 The image shown is an image of the photonic crystal in this embodiment. Figure 6 The image shown is a partial SEM image of a photonic crystal structure for optimized bandgap measurement in an embodiment of the present invention.
[0031] To verify the significant advantages of dark-field angle-resolved technology in measuring artificially modified photonic crystals, a comparative experiment was conducted with an unmodified photonic crystal. Figure 7 The dark-field angular-resolved band structure of an unmodified reflective photonic crystal; such as Figure 8 Dark-field angle-resolved band structures were obtained using an artificially modified photonic crystal under the same conditions. A comparison of the two spectra clearly shows that the band structure obtained without the artificial modification is not clearly visible, while the band structure obtained with the modified photonic crystal is clearly visible. The ratio of the measured band structure to the background signal was calculated using the modified photonic crystal. Figure 8 As shown, the ratios of the scattered light intensity values to the background signal at three points are 1.62, 1.56, and 1.87, respectively. Figure 7 With a ratio of 1 for the three points, it is clear that the intensity of the collected light is increased by more than 1.5 times when collecting the scattered light signal from the photonic crystal.
[0032] Example 2 Embodiment 2 of the present invention provides a method for fabricating a photonic crystal structure for optimized bandgap measurement. The photonic crystal structure is made of PMMA material, and specifically includes the following steps: Step 1: Determine the geometric parameters of the photonic crystal thin film layer 3, including the geometric parameters of the photonic crystal and the geometric scattering unit 5.
[0033] Step 2: Determine the photolithography pattern based on the geometric parameters of the photonic crystal thin film layer 3.
[0034] In this embodiment, random geometric patterns are drawn around the planned photonic crystal layout to facilitate the subsequent formation of geometric scattering units 5, which serve as scattering sources.
[0035] Step 3: Spin-coat photoresist onto substrate 2, dry it, and then perform electron beam lithography (EBL) on the photoresist using a photolithography pattern, followed by development and fixing to finally obtain photonic crystal thin film layer 3 containing the modified structure.
[0036] Step three also includes a preprocessing step, specifically: 1) Cleaning the substrate: Soak the substrate in acetone, isopropanol, ethanol, and deionized water for ten minutes each.
[0037] 2) Substrate layer: A substrate layer is deposited on the cleaned ITO glass.
[0038] Furthermore, in this embodiment, the photonic crystal periodic pattern lithography method can also be implemented using focused ion beam etching (FIB). If electron beam lithography is used, a conductive layer must be present below or above the photoresist to prevent charge accumulation that could lead to inaccurate patterns; typically, a material with good conductivity is selected as the substrate. However, conductive glass (ITO) exhibits significant losses in the infrared band, thus causing severe attenuation of the collected optical signal intensity in this band. Using ordinary glass as the substrate presents the problem of its inherent non-conductivity. To address this, a conductive layer can be deposited on the photoresist; commonly used conductive materials include gold (Au) and aluminum (Al). The thickness of the conductive layer is typically 20 nm.
[0039] In step three, PMMA A4 photoresist is spin-coated using a spin coater with spin-coating parameters of 3000 rad / s and 60 s, and then dried at 160°C for 10 min.
[0040] Furthermore, the substrate layer 2 can be deposited using methods such as vapor deposition, electron beam evaporation, thermal evaporation, and sputtering deposition. To obtain better film quality, the vacuum level of the coating apparatus should be evacuated to 10. -8 For Torr, the coating rate should be set to 0.3 angstroms per second.
[0041] Photolithography is a process of directly writing onto photoresist using an electron beam or laser. Photoresist materials are categorized into positive and negative photoresists based on their development effect. Positive photoresists include electron beam positive photoresists (PMMA) and diazonaphthoquinone (DNQ) based positive photoresists. Negative photoresists include electron beam negative photoresists and cyclized rubber based negative photoresists. The drying time and temperature of the photoresist depend on the specific conditions required for each photoresist; for example, PMMA A4 photoresist requires drying at 160℃ for ten minutes.
[0042] In this embodiment, the photonic crystal thin film layer is made of photoresist, which can save subsequent steps, avoid the factors of incomplete stripping and stripping difficulties in the stripping step, and greatly reduce the complexity of the process.
[0043] Example 3 Embodiment 3 of the present invention provides a method for preparing a photonic crystal structure with optimized bandgap measurement, characterized by comprising the following steps: Step 1: Determine the geometric parameters of the photonic crystal thin film layer 3, including the geometric parameters of the photonic crystal and the geometric scattering unit 5.
[0044] Step 2: Determine the photolithography pattern based on the geometric parameters of the photonic crystal thin film layer 3.
[0045] In this embodiment, random geometric patterns are drawn around the planned photonic crystal layout to facilitate the subsequent formation of geometric scattering units 5, which serve as scattering sources.
[0046] Step 3: Spin-coat photoresist onto substrate 2, dry it, and then develop and fix the photoresist using a photolithography pattern.
[0047] In step three, PMMA A4 photoresist is spin-coated using a spin coater with spin-coating parameters of 3000 rad / s and 60 s, and then dried at 160°C for 10 min.
[0048] Step three also includes a preprocessing step, specifically: 1) Cleaning the substrate: Soak the substrate in acetone, isopropanol, ethanol, and deionized water for ten minutes each.
[0049] 2) Substrate layer: Substrate layer 2 is deposited on the cleaned ITO glass.
[0050] The substrate layer 2 can be coated using vapor deposition, electron beam evaporation, thermal evaporation, sputtering deposition, or other coating technologies.
[0051] Step 4: Deposit photonic crystal material into the periodic structure formed by photoresist to form a photonic crystal thin film layer 3 containing the modified structure.
[0052] In step four, it is necessary to ensure that the target material is deposited vertically within the air cavity of the periodic structure formed by the photoresist without affecting the properties of the photoresist, so as to avoid damage to the structure. Therefore, thermal evaporation is preferred.
[0053] In step 4, the coating method for the photonic crystal material can be vapor deposition, electron beam evaporation, thermal evaporation, sputtering deposition, or other coating technologies.
[0054] Step 5: Remove the photoresist to finally form a photonic crystal structure with optimized bandgap measurements.
[0055] This invention is not limited to a specific waveband, but is applicable to all wavebands. It is necessary to pay attention to the refractive index matching between the substrate layer and the photonic crystal thin film layer, and to consider the material loss in different wavebands when using different materials for the substrate, substrate layer and photonic crystal thin film, so as to avoid significant signal attenuation leading to inaccurate collection of band signals.
[0056] The modified structure described in this invention can enhance the intensity of scattered light without affecting the band structure of the photonic crystal itself; it only enhances the scattering source inside the photonic crystal.
[0057] This invention only lists the method of fabricating photonic crystals through photolithography, but is not limited to photolithography. The core idea is to enhance the scattering of photonic crystals through artificially introduced structural modifications.
[0058] This invention discloses an optimized photonic crystal structure and its fabrication method for bandgap measurements. By introducing a modification structure into the periodic structure of the photonic crystal, the intensity of scattered light is increased. This method effectively improves the dark-field angular-resolved spectroscopy, laying the foundation for subsequent research into the band structure of photonic crystals.
[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A photonic crystal structure for optimized bandgap measurement, comprising: The substrate layer (2) and the photonic crystal thin film layer (3) disposed on the substrate layer (2) are characterized in that the photonic crystal thin film layer (3) is provided with periodic photonic crystals and modification structures, the modification structures including a plurality of geometric scattering units (5) randomly distributed on the outer periphery of the photonic crystal thin film layer (3).
2. The photonic crystal structure for optimized bandgap measurement according to claim 1, characterized in that, The modified structure is made of the same material as the photonic crystal thin layer (3), and is set on the substrate layer (2) by photolithography and synchronous etching of the photonic crystal.
3. The photonic crystal structure for optimized bandgap measurement according to claim 1, characterized in that, The geometric scattering unit (5) of the modified structure is a nanosphere, which is set on the surface of the photonic crystal by spin coating or spray doping process.
4. The photonic crystal structure for optimized bandgap measurement according to claim 1, characterized in that, The geometric scattering unit (5) is circular, elliptical, square, triangular or polygonal, and the photonic crystal is a one-dimensional photonic crystal or a two-dimensional photonic crystal.
5. The photonic crystal structure for optimized bandgap measurement according to claim 1, characterized in that, It also includes a substrate layer (1), wherein the substrate layer (2) is disposed on the substrate layer (1), the substrate layer (2) is made of titanium dioxide, and the substrate layer (1) is a conductive ITO glass or a silicon oxide substrate.
6. The photonic crystal structure for optimized bandgap measurement according to claim 1, characterized in that, The diameter of the geometric scattering unit (5) is 3-20 times the period of the photonic crystal in the photonic crystal thin film layer (3).
7. A method for preparing a photonic crystal structure for optimized bandgap measurement according to any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Determine the geometric parameters of the photonic crystal thin film layer (3), including the geometric parameters of the photonic crystal and the geometric scattering unit (5); Step 2: Determine the photolithography pattern based on the geometric parameters of the photonic crystal thin film layer (3); Step 3: Spin-coat photoresist onto the substrate layer (2), dry it, and then perform electron beam lithography on the photoresist using the photolithography pattern, followed by development and fixing, to finally obtain a photonic crystal thin film layer (3) containing the modified structure.
8. A method for preparing a photonic crystal structure for optimized bandgap measurement according to any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Determine the geometric parameters of the photonic crystal thin film layer (3), including the geometric parameters of the photonic crystal and the geometric scattering unit (5); Step 2: Determine the photolithography pattern based on the geometric parameters of the photonic crystal thin film layer (3); Step 3: Spin-coat photoresist onto substrate (2), dry it, and then develop and fix the photoresist using a photolithography pattern. Step 4: Deposit photonic crystal material into the periodic structure formed by photoresist to form a photonic crystal thin film layer containing the modified structure (3). Step 5: Remove the photoresist to finally form a photonic crystal structure with optimized bandgap measurements.
9. A method for preparing a photonic crystal structure for optimized bandgap measurement according to any one of claims 7-8, characterized in that, In step three, PMMA A4 photoresist is spin-coated using a spin coater with spin-coating parameters of 3000 rad / s and 60 s, and then dried at 160°C for 10 min.