A solar-blind ultraviolet bandpass filter structure based on the superposition of tunneling peaks due to photonic crystal defects
By designing the superposition of tunneling peaks due to defects in photonic crystals and optimizing the periodicity of the photonic crystal structure and the thickness of the dielectric layer, the problem of low passband transmittance in solar-blind ultraviolet filter structures was solved, achieving high transmittance and deep cutoff filtering effects, thus improving the performance of solar-blind ultraviolet detection systems.
Patent Information
- Application Number
- CN202211304577.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-10-24
- Publication Date
- 2025-10-28
- Estimated Expiration
- 2042-10-24
AI Technical Summary
Existing solar-blind ultraviolet filter structures have low passband transmittance in the solar-blind ultraviolet band, poor passband uniformity, a large difference between peak transmittance and average transmittance, and low cutoff on both sides of the passband, resulting in unsatisfactory filtering performance.
A design for superimposing defect tunneling peaks in a photonic crystal with a structure of [(H/L)N1A(H/L)N1]N2 is adopted. By adjusting the periodic arrangement of high-refractive-index and low-refractive-index dielectric layers and the combination of defect layers, the localization characteristics of photons and the superposition of multiple defect tunneling peaks are enhanced. The dielectric thickness is optimized to achieve high transmittance and deep cutoff filtering effect.
High transmittance (90.71%) and low stopband transmittance (1.47%) in the solar-blind ultraviolet band were achieved, significantly improving the performance of the solar-blind ultraviolet detection system.
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Figure CN115657186B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of quantum optical materials technology, specifically a solar-blind ultraviolet bandpass filter structure based on the superposition of tunneling peaks of photonic crystal defects. Background Technology
[0002] Solar-blind ultraviolet (UV) filters are a crucial component in solar-blind UV optical systems, and the design of the solar-blind UV filter structure is a key technology for achieving high-quality solar-blind UV filtering. Currently, solar-blind UV filter structures based on optical media structures can achieve the passband and stopbands on both sides of the solar-blind band. However, the transmittance of the passband formed in the solar-blind UV band is still not high enough, and the uniformity of the passband is poor, with a large difference between peak transmittance and average transmittance. The cutoff on both sides of the passband is also low, resulting in an unsatisfactory filtering effect.
[0003] In 2016, Yan Shifei et al. (Performance Analysis of Special Solar Blind Ultraviolet Filters [J]. Yan Shifei et al. Optoelectronics Technology, 2016, Vol. 36 (4): 260-264) designed an absorption filter with a bandwidth of about 20nm, a peak transmittance of 25%, and a peak position that can be dynamically adjusted in the range of 250-280nm. However, this absorption filter has a narrow bandwidth and low transmittance.
[0004] In 2017, Fu Xiuhua et al. (Development of wideband low-noise filter devices for solar-blind detection [J]. Chinese Journal of Lasers, 2017, 44(6): 165-171) selected Al and AlF3 as two materials to form an FP structure and combined it with a matching structure composed of Al2O3 and AlF3 to design a filter film structure with an average transmittance of 54.15% in the 200-270nm band. However, the passband of this structure overlaps significantly with the solar-blind ultraviolet bandgap and has a low transmittance.
[0005] In 2018, Shang Peng et al. (Design and Low-Temperature Fabrication of Multi-Metal Layer Induced Transmission Ultraviolet "Solar-Blind" Detection Imaging Filters [J]. Infrared and Laser Engineering, 2018, Vol. 47(9): 185-191) obtained a three-cavity metal-induced transmission ultraviolet filter film based on a SiO2 / Al / SiO2 three-layer sandwich structure, and systematically analyzed the influence of the Al and SiO2 dielectric matching layer on the spectral performance of the ultraviolet filter film. This multilayer film structure containing Al metal contains both interference and absorption effects, but the method of introducing a metal dielectric into the structure has a better suppression effect in the visible light band, and to some extent also affects the transmittance in the ultraviolet band.
[0006] In 2018, Bai Yating et al. (Design of a solar-blind ultraviolet band-pass filter based on frequency domain superposition, Superlattices and Microstructures, Volume 122, 2018, Pages 486-491) designed a multiphoton crystal structure based on the principle of frequency domain superposition. Its average transmittance in the 240-280nm range was 72.2%. Although this superposition structure broadened the bandgap, the passband shape was messy and uneven, with large fluctuations.
[0007] In 2019, Yuan et al. (A High-Performance SiO2 / SiNx 1-D Photonic Crystal UVFilter Used for Solar-Blind Photodetectors, IEEE Photonics Journal, vol. 11, no. 4, 2019, pp. 1-7) designed and fabricated a SiO2 / SiNX filter on double-polished sapphire using NH3 as a SiNX precursor. The filter achieved a transmittance of 80% in the solar-blind region and less than 10% in the 285-345nm range. Summary of the Invention
[0008] This invention aims to solve the technical problem of low passband transmittance of existing filter structures in the solar-blind ultraviolet band, and provides a solar-blind ultraviolet bandpass filter structure based on the superposition of tunneling peaks of photonic crystal defects.
[0009] The technical means adopted by this invention to solve its technical problem is: to provide a solar-blind ultraviolet bandpass filter structure based on the superposition of tunneling peaks of photonic crystal defects, using [(H / L] N1 A(H / L) N1 ] N2 The structure consists of a high-refractive-index dielectric layer (H), a low-refractive-index dielectric layer (L), and a defect layer (A). The high-refractive-index and low-refractive-index dielectric layers are periodically arranged to form a photonic crystal. N1 is the period of the photonic crystals on both sides of the defect layer. The high-refractive-index dielectric layers and the low-refractive-index dielectric layers in the photonic crystal have the same thickness. The defect layer is combined with the photonic crystals on both sides to form a defect-type photonic crystal. N2 is the period of the defect-type photonic crystal.
[0010] Preferably, the high refractive index dielectric layer is made of Si3N4, the low refractive index dielectric layer is made of SiO2, and the defect layer is made of air.
[0011] Preferably, the period N1 of the photonic crystals (1) on both sides of the defect layer is 1 to 5. More preferably, the period N1 of the photonic crystals (1) on both sides of the defect layer is 1.
[0012] Preferably, the period N2 of the defective photonic crystal (2) is 3 to 5. More preferably, the period N2 of the defective photonic crystal (2) is 4.
[0013] Preferably, the thickness of the high-refractive-index dielectric layer is 22-32 nm, the thickness of the low-refractive-index dielectric layer is 37-47 nm, and the thickness of the defect layer is 59-71 nm. More preferably, the thickness of the high-refractive-index dielectric layer is 30 nm, the thickness of the low-refractive-index dielectric layer is 40 nm, and the thickness of the defect layer is 67 nm.
[0014] The beneficial effects of this invention are as follows: This invention designs a solar-blind ultraviolet bandpass filter structure based on the superposition of tunneling peaks caused by photonic crystal defects. Based on the photonic localization characteristics of the photonic crystal structure and the principle of superposition of multiple defect tunneling peaks, it can achieve high transmission and deep cutoff filtering in the solar-blind ultraviolet band (239-280nm). The average transmittance of the passband can reach 90.71%, while the average transmittance of the stopband is only 1.47%, which has the potential to significantly improve the performance of solar-blind ultraviolet detection systems. Attached Figure Description
[0015] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in 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 the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0016] Figure 1 This is a schematic diagram of a solar-blind ultraviolet bandpass filter structure based on the superposition of tunneling peaks of photonic crystal defects, as described in this invention.
[0017] Figure 2 This is a schematic diagram illustrating the influence of the period N1 of the photonic crystals on both sides of the defect layer of the present invention on the tunneling peak bandwidth of the solar-blind ultraviolet passband.
[0018] Figure 3 This is a schematic diagram illustrating the effect of the period N2 of the defective photonic crystal of the present invention on the tunneling peak bandwidth of the solar-blind ultraviolet passband.
[0019] Figure 4 The transmission spectrum of a photonic crystal after optimization based on the superposition of tunneling peaks in a photonic crystal defect is provided in an embodiment of the present invention. The solid line represents the transmittance and the dashed line represents the reflectance.
[0020] Figure 5The solar-blind ultraviolet bandpass filter structure based on the superposition of tunneling peaks of photonic crystal defects provided in this embodiment of the invention is affected by the incident angle.
[0021] In the diagram: 1. Photonic crystal; 2. Defect-type photonic crystal; H. High refractive index dielectric layer; L. Low refractive index dielectric layer; A. Defect layer; θ. Angle of incidence of light. Detailed Implementation
[0022] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.
[0023] In the description of this invention, it should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0024] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.
[0025] One embodiment provides a solar-blind ultraviolet bandpass filter structure based on the superposition of tunneling peaks caused by photonic crystal defects, as shown in the figure, using [(H / L]]. N1 A(H / L) N1 ] N2 The structure consists of a high-refractive-index dielectric layer (H), a low-refractive-index dielectric layer (L), and a defect layer (A). The high-refractive-index and low-refractive-index dielectric layers are periodically arranged to form photonic crystal 1. N1 is the period of photonic crystal 1 on both sides of the defect layer. The high-refractive-index dielectric layers and the low-refractive-index dielectric layers in photonic crystal 1 have the same thickness. The defect layer, combined with the photonic crystal 1 layers on both sides, forms a defect-type photonic crystal 2. N2 is the period of defect-type photonic crystal 2. The incident angle of light in this structure is θ.
[0026] Bandpass filtering is achieved by enhancing photonic localization and superimposing multiple defect tunneling peaks. The defect tunneling peaks of photonic crystal 1 are amplified, broadened, and their shape adjusted. These amplified and adjusted defect tunneling peaks serve as the passband for solar-blind ultraviolet bandpass filtering, achieving the desired effect. By adjusting the period N1 of photonic crystal 1 on both sides of the defect layer, the proportion of the defect layer in the structure is increased, thereby enhancing the localization effect of the outer photonic crystal 1 on the defect layer and achieving amplification, broadening, and shape adjustment of the defect tunneling peaks. Subsequently, by adjusting the period N2 of the defect-type photonic crystal 2, the single-defect photonic crystal 2 structure is periodically repeated, causing the defect modes to superimpose, changing the shape of the passband, improving the cutoff from the passband to the bandgap, and increasing the transmittance in the solar-blind region. Considering dispersion and absorption, the influence of medium thickness on the transmission spectrum is studied, and the thickness parameter of photonic crystal 1 is adjusted to achieve wide bandwidth and deep cutoff solar-blind ultraviolet bandpass filtering. It is well known to those skilled in the art that both period N1 and period N2 are integers.
[0027] Furthermore, as a specific implementation of this embodiment, the material of the high refractive index dielectric layer is Si3N4, the material of the low refractive index dielectric layer is SiO2, and the defect layer is air.
[0028] Among them, Si3N4 exhibits significant dispersion and absorption at short wavelengths, while absorption weakens and the refractive index tends to stabilize at long wavelengths. SiO2 exhibits slight dispersion and has no absorption effect in the 200-800nm wavelength range.
[0029] Furthermore, the period N1 of the photonic crystal 1 on both sides of the defect layer is 1 to 5, and the period N1 of the photonic crystal 1 on both sides of the defect layer is preferably 1.
[0030] like Figure 2 As shown, when the number of periods of photonic crystal 1 on both sides of the defect layer is large, the disruptive effect of the defect on the periodicity is weakened. Increasing the value of N1 makes the tunneling peak narrower, which is suitable for narrowband filtering. However, to obtain a wider passband tunneling peak, the number of periods on both sides of the defect layer of photonic crystal 1 should be reduced. When N1 is at its minimum value of 1, the passband has the maximum bandwidth.
[0031] Furthermore, the period N2 of the defective photonic crystal 2 is 3 to 5, and the period N2 of the defective photonic crystal 2 is preferably 4.
[0032] like Figure 3As shown, when N2 is small, the passband is arched, with higher transmittance at the center and gradually decreasing transmittance on both sides. With increasing N2, the top of the passband shows some dips, but the overall position remains higher and the fluctuations are smaller. As N2 continues to increase, the dips away from the center become more pronounced, affecting the average transmittance of the passband. Considering factors such as cutoff and transmittance, the period number N2 of the defective photonic crystal 2 is determined to be 4.
[0033] Furthermore, the thickness of the high-refractive-index dielectric layer is 22-32 nm, the thickness of the low-refractive-index dielectric layer is 37-47 nm, and the thickness of the defect layer is 59-71 nm. Specifically, the bandpass filter structure is [(Si3N4 / SiO2)Air(Si3N4 / SiO2)]. 4 When the thickness of the high-refractive-index dielectric layer is preferably 30 nm, the thickness of the low-refractive-index dielectric layer is preferably 40 nm, and the thickness of the defect layer is preferably 67 nm, high-transmission deep-cutoff filtering in blind ultraviolet light can be achieved, such as... Figure 4 As shown, the passband of this bandpass filter structure is 239-280 nm, the bandwidth is 41 nm, the average transmittance of the passband is 90.71%, and the average transmittance of the stopband is only 1.47%. The incident angle has a certain influence on the transmission spectrum of photonic crystal 1; as the incident angle increases, the transmission spectrum of photonic crystal 1 shifts generally towards shorter wavelengths. When the incident angle θ is below 20°, the degree of shift and the increase in shift of the transmission spectrum are relatively small, indicating low sensitivity to the incident angle of light. Figure 5 As shown.
[0034] In summary, this invention provides a solar-blind ultraviolet bandpass filter structure based on the superposition of tunneling peaks caused by photonic crystal defects, achieving high transmission and deep cutoff in solar-blind ultraviolet filtering. The breakthrough achieved in this research can be applied to the design of bandpass filters in other wavelength bands.
[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements 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 solar-blind ultraviolet bandpass filter structure based on the superposition of tunneling peaks due to defects in photonic crystals, characterized in that, Using [(H / L)] N1 A(H / L) N1 ] N2 The structure is as follows: H is a high refractive index medium layer, L is a low refractive index medium layer, A is a defect layer, and the high refractive index medium layer and the low refractive index medium layer are periodically arranged to form a photonic crystal (1). N1 is the period of the photonic crystals (1) on both sides of the defect layer. The high refractive index medium layer in the photonic crystal (1) has the same thickness, the low refractive index medium layer has the same thickness, and the thickness of the high refractive index medium layer is different from the thickness of the low refractive index medium layer. The defect layer and the photonic crystals (1) on both sides are combined to form a defect-type photonic crystal (2). N2 is the period of the defect-type photonic crystal (2). The high-refractive-index dielectric layer is made of Si3N4, the low-refractive-index dielectric layer is made of SiO2, and the defect layer is made of air. The period N1 of the photonic crystals (1) on both sides of the defect layer is 1; The period N2 of the defective photonic crystal (2) is 4; The thickness of the high refractive index dielectric layer is 30 nm, the thickness of the low refractive index dielectric layer is 40 nm, and the thickness of the defect layer is 67 nm.
Citation Information
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