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CN-121978784-A - Broad spectrum optical anti-reflection structure with continuous graded refractive index distribution, preparation and application thereof

CN121978784ACN 121978784 ACN121978784 ACN 121978784ACN-121978784-A

Abstract

The invention discloses a wide-spectrum optical anti-reflection structure with continuous graded refractive index distribution, and preparation and application thereof. The optical fiber comprises a substrate and a microsphere array, wherein the substrate is made of a first optical material, the microsphere array is arranged on the surface of the substrate and made of a second optical material, the refractive index of the second optical material is between that of an incident medium and that of the first optical material, the microsphere array is a single-layer array, the microsphere array is contacted with or embedded into the surface of the substrate to form a composite interface structure, and the composite interface structure shows continuously graded refractive index distribution from the incident medium to the refractive index of the second optical material in the depth direction. The invention can flexibly regulate and control the equivalent refractive index distribution by regulating the size and the embedding depth of the microsphere, realizes reflection inhibition or absorption enhancement in a wide angle and a wide spectrum range, and has bionic characteristics and adjustable optical properties.

Inventors

  • LI YANG
  • DU PANPAN

Assignees

  • 浙江大学

Dates

Publication Date
20260505
Application Date
20260407

Claims (10)

  1. 1. A broad spectrum optical anti-reflection structure having a continuously graded refractive index profile, comprising: A substrate (12) made of a first optical material; An array of microspheres (11) disposed on a surface of the substrate (12), made of a second optical material having a refractive index between that of the incident medium and that of the first optical material; The microsphere array (11) is a single-layer array, the microsphere array (11) is contacted with or embedded into the surface of the substrate (12) to form a composite interface structure, and the composite interface structure presents a refractive index distribution with continuous gradual change from an incident medium to a refractive index of a second optical material in the depth direction.
  2. 2. The broad spectrum optical antireflection structure having a continuous graded refractive index profile as claimed in claim 1, wherein the microsphere array (11) is an ordered arrangement or a quasi-ordered arrangement, the microspheres are in contact with each other or have a distance of not more than 10% of the radius of the microspheres, the microsphere array (11) is composed of a plurality of equal-sized microspheres, and the diameter of the microspheres ranges from 0.1 μm to 2 μm.
  3. 3. The broad spectrum optical anti-reflection structure with continuous graded index profile according to claim 1 or 2, wherein the microsphere array (11) is partially embedded in the surface of the substrate (12) such that the composite interface structure comprises a first section and a second section in sequence in a direction perpendicular to the surface of the substrate (12), the first section being composed of the microsphere portion exposed to the substrate (12) and the incident medium, and the second section being composed of the microsphere portion embedded in the substrate (12) and the substrate (12).
  4. 4. A broad spectrum optical anti-reflection structure having a continuously graded refractive index profile as claimed in claim 3, wherein the microsphere array (11) is embedded in the underlying substrate (12) to a depth in the range of 20% to 80% of the microsphere diameter.
  5. 5. The broad spectrum optical anti-reflection structure with continuous graded index profile as in claim 1, wherein the second optical material has a refractive index greater than the incident medium.
  6. 6. The broad spectrum optical anti-reflection structure having a continuous graded index profile as in claim 1, wherein the composite interface structure comprises at least one segment in the depth direction, each segment having a refractive index versus depth curve capable of fitting to a penta-like polynomial curve.
  7. 7. A method for manufacturing the broad spectrum optical anti-reflection structure according to any one of claims 1 to 6, comprising the steps of: Step S1) preparing a substrate (12) with a smooth surface using a first optical material; Step S2) forming a monolayer microsphere array (11) on the smooth surface of the substrate (12); step S3) embedding the bottom part or the whole of the microsphere array (11) into the surface of the substrate (12).
  8. 8. The method of claim 7, further comprising the step of making the refractive index change of each segment of the composite interface structure more gradual by increasing the diameter of the microspheres or the depth of the embedment, and making the refractive index change of each segment of the composite interface structure more abrupt by decreasing the diameter of the microspheres or the depth of the embedment.
  9. 9. An optical device comprising the broad spectrum optical anti-reflection structure according to any one of claims 1 to 6 or the broad spectrum optical anti-reflection structure obtained by the preparation method according to claims 7 to 8 is characterized in that the broad spectrum optical anti-reflection structure is used for realizing reflection inhibition or absorption enhancement.
  10. 10. The optical device of claim 9, wherein the broad spectrum optical anti-reflection structure is configured to effect reflection suppression when the first optical material and the second optical material are both substantially transparent dielectric materials within a target operating band, wherein the optical device is a photovoltaic cell, a display panel, or a transparent electrode, and wherein the broad spectrum optical anti-reflection structure is configured to effect absorption enhancement when the first optical material is an optically lossy material having absorption characteristics within the target operating band, wherein the optical device is a photothermal conversion, photocatalytic, or infrared absorbing device.

Description

Broad spectrum optical anti-reflection structure with continuous graded refractive index distribution, preparation and application thereof Technical Field The invention mainly relates to the field of optical anti-reflection and anti-reflection films and structures, in particular to a wide-spectrum optical anti-reflection structure with continuous graded refractive index distribution, and preparation and application thereof. Background With the acceleration and transformation of global energy structures to clean and low carbonization directions and the continuous evolution of photoelectric functional devices to high integration and high performance directions, the technical innovation of the core fields such as photovoltaic power generation, photoelectric detection, photocatalysis, photo-thermal conversion and the like is coming to a rapid development period. In order to achieve higher light energy utilization efficiency, the need for functional structures with efficient light energy modulation capability over a wide spectral range is increasing. Since the early 20 th century, the principle of reducing glass surface reflection by oxide layers (Lord Rayleigh) has been proposed, and Anti-Reflective (AR) coating technology has been continuously developed. The technology realizes the improvement of light transmittance and the reduction of reflection loss by regulating and controlling the reflection and interference behaviors of light between interfaces of different media. Over the course of a century evolution, AR coatings have evolved from early single layer films to multilayer interference film systems and are widely used in critical optics such as optical lenses, solar cells, displays and biosensors. However, the design concept of conventional multilayer interference AR films mainly relies on alternating stacks of dielectric materials of different refractive indices, exploiting the principle of quarter-wavelength thick interference to suppress reflection at specific wavebands and improve transmission. Chinese patent CN202510262295.8 discloses a wide-angle domain optical antireflective method based on equivalent gradient index matching and phase angle constraint, chinese patent CN202421531661.2 discloses a high light transmission base film. Although such structures have good optical properties in a specific wavelength band, there are various limitations in practical applications: On one hand, the preparation process of the multilayer alternating structure is complex, the requirements on the thickness and uniformity of the film layer are extremely high, and the production cost is high; on the other hand, the abrupt change of refractive index between layers is easy to cause interface reflection, reduces the overall transmission performance, is highly sensitive to the incident angle, and has sharp attenuation of the optical performance under the wide-angle incident condition. Therefore, it is difficult to achieve the combination of the wide-band, wide-angle and high-performance optical characteristics of the conventional interference type AR film. The Jin et al adopts an ink-jet printing technology under normal pressure, combines the digital regulation of printing resolution, utilizes an aperiodic multilayered structure to prepare a high-performance long-pass Optical Interference Filter (OIFs), and realizes the average transmittance of 91.7% in the wave band of 540-800 nm (Nature Communications, 2024, 15 (1): 3372). However, the precise collaborative design and large-scale application of the multilayer film system are still to be further broken through towards a multi-broad-spectrum anti-reflection scene (the anti-reflection requirement of covering the full wave band, the cross wave band or the wide angle range of visible light is required). In recent years, bionic structures (such as moth-eye structures) have become a research hotspot due to their natural broad spectrum anti-reflection properties. The periodic or quasi-periodic micro-nano structure with sub-wavelength scale is constructed on the surface of the material, so that the refractive index of the interface is gradually transited, and excellent anti-reflection performance is realized in the range from visible light to infrared band. Sun et al replicate a biomimetic moth-eye structure with a period of about 200-300 nm on a transparent polycarbonate substrate using Roll-to-Plate ultraviolet nanoimprint technology (UV-NIL), which has an average reflectance of only 1.21% at a wavelength band of 380-760 nm, a reflectance of still less than 4% at an incident angle of 50℃and is significantly better than untreated samples (SCIENTIFIC REPORTS, 2018, 8 (1): 1-10). However, the existing moth-eye structure generally depends on preparation processes such as nano imprinting, etching or template replication, and the like, and has the disadvantages of complex process flow, limited parameter controllability and higher preparation cost. And the obtained structure is usual