Receiving antenna

Abstract

The invention provides a receiving antenna, which comprises a fluorescent material layer, a metal periodic array structure, a transparent isolation layer and a light condensation structure, and is characterized in that the fluorescent material layer can receive an incident light signal at a large angle, and the metal periodic array structure can excite a plasmon coupling effect; the transparent isolation layer is located between the fluorescent material layer and the metal periodic array structure and can physically isolate the fluorescent material layer from the metal periodic array structure, so that fluorescence quenching is prevented, and a local electromagnetic field around metal units in the metal periodic array structure is enhanced; the absorption rate of the fluorescent material to incident light signals and the radiance of excited state electrons are increased, the average residence time of the electrons in the excited state is reduced, the fluorescence lifetime is shortened, and thus the receiving efficiency of the receiving antenna to the light signals can be improved. The light condensation structure is located on the side, away from the transparent isolation layer, of the fluorescent material layer or located on the side, away from the transparent isolation layer, of the metal periodic array structure and can converge fluorescent signals entering the light condensation structure to provide light receiving gain.

Description

Technical Field

[0001] The present application relates to the technical field of optical wireless communication, and in particular to a receiving antenna. Background Art

[0002] Optical wireless communication (OWC) has attracted widespread attention in the industry due to its advantages such as large available bandwidth, high device integration, and anti-electromagnetic interference. It is particularly suitable for application scenarios such as high-speed communication, quasi-static communication, and intensive multi-user communication. Wireless optical communication is currently a key research direction in academia and industry. Light sources, detectors and other devices for high-speed communication are undergoing continuous evolution. Among them, broadband photodetectors (PDs) have small photosensitive surfaces, which will bring more significant problems with the receiving antenna posture and alignment, which will limit the promotion of OWC technology.

[0003] In a current OWC receiving antenna based on fluorescent materials, the light receiving efficiency of the OWC receiving antenna is affected due to the self-absorption of the fluorescent signal output by the fluorescent material during the transmission process. In another OWC receiving antenna based on a laminated structure of fluorescent materials and metal nanomaterials, the adjacent laminated structure of the fluorescent material and the metal nanomaterial is prone to fluorescence quenching, and the OWC receiving antenna has low receiving efficiency for optical signals. Summary of the invention

[0004] The present application provides a receiving antenna, which is used to improve the receiving efficiency of the receiving antenna for optical signals.

[0005] In a first aspect, the present application provides a receiving antenna, comprising: a fluorescent material layer, a metal periodic array structure, a transparent isolation layer and a focusing structure, wherein the transparent isolation layer is located between the fluorescent material layer and the metal periodic array structure, the focusing structure is located on a side of the fluorescent material layer away from the transparent isolation layer, or the focusing structure is located on a side of the metal periodic array structure away from the transparent isolation layer.

[0006] The receiving antenna provided by the present application has a fluorescent material layer that can receive incident light signals at a large angle, and a metal periodic array structure that can excite a plasmon coupling effect. Since the transparent isolation layer is located between the fluorescent material layer and the metal periodic array structure, the fluorescent material layer and the metal periodic array structure can be physically separated. Compared with the fluorescent material layer and the metal periodic array structure directly stacked together, the receiving antenna of the present application can prevent fluorescence quenching on the one hand, and on the other hand, it can enhance the local electromagnetic field around the metal unit in the metal periodic array structure, thereby increasing the absorption utilization rate of the fluorescent material for the incident light signal and the radiation rate of the excited state electrons, reducing the average residence time of the electrons in the excited state, and reducing the fluorescence lifetime, thereby improving the receiving efficiency and emission efficiency of the receiving antenna for the light signal. In addition, the receiving antenna includes a focusing structure that can focus the fluorescent signal entering the focusing structure to provide light receiving gain.

[0007] In a possible implementation of the present application, the metal periodic array structure includes any one of the following: an array formed by a periodic distribution of triangular prism structure metal units; an array formed by a periodic distribution of cube structure metal units; an array formed by a periodic distribution of rectangular structure metal units; an array formed by a periodic distribution of cylindrical structure metal units.

[0008] In a possible implementation of the present application, the array formed by the periodic distribution of the triangular prism structure metal units is an array formed by the periodic distribution of the triangular prism structure metal units with curved sides. The curved triangle structure in the triangular prism structure metal unit with curved sides has a tip structure with a smaller radius of curvature, and the charges are more densely gathered at the tip structure, and the localized plasmons excited by a single metal unit are stronger. When the metal units are arranged into an ordered array, the diffraction waves generated on the surface of the array structure will be resonantly coupled with the localized plasmons of the single metal unit, resulting in a sharp narrowing of the resonance spectrum, so that the array structure has a higher quality factor and lower radiation attenuation, thereby improving the light collection efficiency and emission efficiency and increasing the bandwidth.

[0009] In a possible implementation of the present application, the fluorescent material layer includes at least one of the following materials: a fluorescent material whose fluorescent spectrum covers the visible light band; a fluorescent material whose fluorescent spectrum covers the infrared band; or a superlattice material.

[0010] In a possible implementation of the present application, the fluorescent material whose fluorescence spectrum covers the visible light band includes at least one of the following: perovskite quantum dots; organic light-emitting materials; rare earth fluorescent materials; cadmium-based quantum dots. As an example, perovskite quantum dots may include but are not limited to any of the following: cesium tribromolead (CsPbBr3) quantum dots, cesium triiodolead (CsPbI3) quantum dots, cesium trichlorolead (CsPbCl3) quantum dots. Cadmium-based quantum dots include but are not limited to CdSe quantum dots and ZnS quantum dots.

[0011] In a possible implementation of the present application, the fluorescent material whose fluorescence spectrum covers the infrared band includes at least one of the following: CdTe quantum dots, CdS quantum dots, and PbS quantum dots.

[0012] In a possible implementation of the present application, the material type of the fluorescent material layer, the type of the metal periodic array structure, and the spacing between adjacent metal units satisfy any of the following:

[0013] The material of the fluorescent material layer is a fluorescent material whose fluorescent spectrum covers the visible light band, and the metal periodic array structure is an array formed by periodic distribution of metal units of curved side triangular prism structure, and the spacing between adjacent metal units is 320-480nm;

[0014] The material of the fluorescent material layer is a fluorescent material whose fluorescent spectrum covers the infrared band, and the metal periodic array structure is an array formed by periodic distribution of metal units of curved side triangular prism structure, and the spacing between adjacent metal units is 960-1440nm;

[0015] The material of the fluorescent material layer is a fluorescent material whose fluorescent spectrum covers the blue light band, and the metal periodic array structure is an array formed by periodic distribution of cubic structure metal units, and the spacing between adjacent metal units is 200-300nm;

[0016] The material of the fluorescent material layer is a fluorescent material whose fluorescent spectrum covers the red light band, and the metal periodic array structure is an array formed by periodic distribution of cubic structure metal units, and the spacing between adjacent metal units is 480-720nm;

[0017] The material of the fluorescent material layer is a fluorescent material whose fluorescent spectrum covers the blue light band. The metal periodic array structure is an array formed by periodic distribution of cylindrical structure metal units, and the spacing between adjacent metal units is 360-540nm.

[0018] The above-mentioned fluorescent materials with fluorescence spectra covering different bands are used in combination with different metal periodic array structures, which can achieve better results in reducing the fluorescence lifetime of the fluorescent materials, increasing the system modulation bandwidth and improving the transmission performance of the optical communication system.

[0019] In a possible implementation of the present application, the focusing structure includes a top surface, a side surface and a bottom surface, one end of the side surface is connected to the top surface, and the other end is connected to the bottom surface, the top surface is used to receive the fluorescent signal emitted by the fluorescent material layer and entering the focusing structure, and the bottom surface is used to emit the outgoing light signal obtained by converging the fluorescent signal through the focusing structure, and the area of ​​the top surface is larger than the area of ​​the bottom surface. The top surface of the focusing structure has a larger area, and can receive fluorescent signals with a large field of view. After being concentrated by the focusing structure, the fluorescent signal is emitted from the bottom surface of the focusing structure to the photosensitive surface on the photodetector. Since the photosensitive surface on the photodetector is small, the area of ​​the bottom surface of the focusing structure is small, so that the outgoing light signal can be received by the photodetector as much as possible, thereby achieving optical gain and effectively improving the modulation bandwidth.

[0020] In a possible implementation of the present application, the material of the side of the focusing structure can be a total reflection film, which can prevent the fluorescent signal from being emitted from the side after entering the focusing structure, thereby reducing the loss of the fluorescent signal and improving the light receiving efficiency of the receiving antenna.

[0021] As an example, the material of the total reflection film may include but is not limited to any of the following: silver film, aluminum film, gold film, dielectric and EUV multilayer film.

[0022] In a possible implementation of the present application, the light-concentrating structure is in the shape of a truncated cone. In one embodiment, the light-concentrating structure may be in the shape of a truncated cone, which may also be called a truncated cone. In another embodiment, the light-concentrating structure may be in the shape of an oblique truncated cone. In yet another embodiment, the light-concentrating structure may be in the shape of a prism, which may also be called a truncated pyramid. In yet another embodiment, the light-concentrating structure may be in the shape of an oblique truncated pyramid.

[0023] In a possible implementation of the present application, the shape of the focusing structure is a compound parabolic concentrator. After the fluorescent signal enters the compound parabolic concentrator, it reaches the photodetector after several reflections, and the loss of the fluorescent signal is small. Moreover, the compound parabolic concentrator can also effectively collect obliquely incident light to achieve the maximum theoretical focusing ratio, and the performance is very close to that of an ideal concentrator.

[0024] In a possible implementation of the present application, the receiving antenna further includes a packaging structure layer; if the focusing structure is located on the side of the fluorescent material layer away from the transparent isolation layer, the packaging structure layer is located on the side of the metal periodic array structure away from the transparent isolation layer; or, if the focusing structure is located on the side of the metal periodic array structure away from the transparent isolation layer, the packaging structure layer is located on the side of the fluorescent material layer away from the transparent isolation layer. The packaging structure layer can provide protection for the fluorescent material layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of the structure of a receiving antenna in an embodiment of the present application;

[0026] Figure 2 Another structural schematic diagram of a receiving antenna in an embodiment of the present application;

[0027] Figure 3 This is a schematic diagram of a PS ball used as a mask in an embodiment of the present application;

[0028] Figure 4 It is a top view of the metal periodic array structure 30 in the embodiment of the present application;

[0029] Figure 5 A schematic diagram of the structure of a receiving antenna in an embodiment of the present application;

[0030] Figure 6 A schematic diagram of the structure of a receiving antenna in an embodiment of the present application;

[0031] Figure 7 A schematic diagram of the structure of a receiving antenna in an embodiment of the present application;

[0032] Figure 8 A schematic diagram of the structure of a receiving antenna in an embodiment of the present application;

[0033] Fig. 9 A schematic diagram of the structure of a receiving antenna in an embodiment of the present application. DETAILED DESCRIPTION

[0034] The terms used in the following embodiments are only for the purpose of describing specific embodiments and are not intended to be limiting of the present application. As used in the specification and appended claims of the present application, the singular expressions "a", "an", "said", "above", "the" and "this" are intended to also include expressions such as "one or more", unless there is a clear contrary indication in the context.

[0035] References to "one embodiment" or "some embodiments" etc. described in this specification mean that a particular feature, structure or characteristic described in conjunction with the embodiment is included in one or more embodiments of the present application. Thus, the phrases "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear at different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0036] There are several options for receiving antennas:

[0037] The first solution is to use a plano-convex lens or other lens as a receiving antenna to converge the light signal in space in the OWC receiving antenna based on the lens structure, and the photodetector is located at the focus of the lens. Although this solution can receive light signals, the field of view (FOV) that can support receiving light signals is limited. Parallel collimated light can converge to the focus after being processed by the lens. For light with a deflection angle, the light spot converged by the lens will deviate from the focus. When only one photodiode detector (PD) is located at the focus for reception, the light spot will deviate from the focus, causing the PD to be unable to receive the light signal. For this problem, one solution is to use a PD array to increase the photosensitive surface, but it increases the cost and complexity of the system. At the same time, it is also difficult to achieve a large field of view of the receiving system, especially in broadband communication scenarios. The diameter of the PD photosensitive surface is in the micrometer (um) order, and the cost and complexity rise sharply.

[0038] The second solution is to integrate fluorescent materials into optical fibers or flat light guide structures in the OWC receiving antenna based on fluorescent materials, and use the fluorescent photoluminescence effect to achieve wide field of view reception. However, conventional fluorescent materials have low bandwidth and are not suitable for high-speed wireless optical communications. In addition, the fluorescent signals output by fluorescent materials in the existing solutions have self-absorption during transmission, which affects the antenna's light receiving efficiency.

[0039] The third solution is an OWC receiving antenna based on a laminated structure of fluorescent materials and metal nanomaterials. The fluorescent material is used as the light-emitting layer and the laminated structure of metal nanoparticles is superimposed. The plasmon coupling effect on the metal surface is used to increase the fluorescence intensity. However, the basic metal structure has insufficient plasmon coupling effect and is not suitable for high-speed wireless optical communication receivers. Moreover, the laminated structure of fluorescent materials and metal nanoparticles easily leads to fluorescence quenching, and the OWC receiving antenna has low efficiency in receiving optical signals.

[0040] In order to solve the above technical problems, an embodiment of the present application provides a receiving antenna. Figure 1 FIG. 1 is a schematic diagram of the structure of a receiving antenna according to an embodiment of the present application. Figure 1 As shown, the receiving antenna includes a fluorescent material layer 10, a transparent isolation layer 20, a metal periodic array structure 30 and a light-concentrating structure 40. The transparent isolation layer 20 is located between the fluorescent material layer 10 and the metal periodic array structure 30.

[0041] In one embodiment of the present application, Figure 1 As shown, the focusing structure 40 is located on the side of the metal periodic array structure 30 away from the transparent isolation layer, that is, the light receiving antenna includes the following layers of materials: fluorescent material layer 10, transparent isolation layer 20, metal periodic array structure 30 and focusing structure 40.

[0042] In another embodiment of the present application, Figure 2 As shown, the light collecting structure 40 is located on the side of the fluorescent material layer 10 away from the transparent isolation layer 20 , that is, the light collecting material includes the layers of materials: the metal periodic array structure 30 , the transparent isolation layer 20 , the fluorescent material layer 10 and the light collecting structure 40 .

[0043] This application provides Figure 1 as well as Figure 2 In the receiving antenna shown, the fluorescent material layer 10 can receive incident light signals at a large angle, and the metal periodic array structure 30 can excite the plasmon coupling effect. Since the transparent isolation layer 20 is located between the fluorescent material layer 10 and the metal periodic array structure 30, the fluorescent material layer 10 and the metal periodic array structure 30 can be physically separated. Compared with the solution in which the fluorescent material layer 10 and the metal periodic array structure 30 are directly stacked together, the receiving antenna of the present application can prevent fluorescence quenching on the one hand, and on the other hand, it can enhance the local electromagnetic field around the metal unit in the metal periodic array structure 30, thereby increasing the absorption utilization rate of the fluorescent material for the incident light signal and the radiation rate of the excited state electrons, which can reduce the average residence time of the electrons in the excited state and reduce the fluorescence lifetime, thereby improving the receiving efficiency of the receiving antenna for the light signal. In addition, the receiving antenna includes

[0044] The light-collecting structure 40 can collect the fluorescent signal entering the light-collecting structure to provide light-collecting gain.

[0045] The receiving antenna of the embodiment of the present application may include, in addition to the fluorescent material layer 10, the transparent isolation layer 20, the metal periodic array structure 30 and the focusing structure 40, an encapsulation structure layer 50. The encapsulation structure layer 50 can provide protection for the fluorescent material layer 10. In one embodiment of the present application, the material of the encapsulation structure layer 50 may include, but is not limited to, at least one of the following: silicon dioxide (SiO2), SU-8 photoresist, magnesium oxide (MgO), and titanium dioxide (TiO2).

[0046] If the light-concentrating structure 40 is located on the side of the metal periodic array structure 30 away from the transparent isolation layer, the encapsulation structure layer 50 is located on the side of the fluorescent material layer 10 away from the transparent isolation layer 20. Figure 1 The receiving antenna shown in the figure includes the following layers of materials from top to bottom: packaging structure layer 50, fluorescent material layer 10, transparent isolation layer 20, metal periodic array structure 30 and focusing structure 40. For example, SiO2 material can be used, and a film can be coated on the side of the metal periodic array structure 30 away from the transparent isolation layer 20 by magnetron sputtering.

[0047] If the light-collecting structure 40 is located on the side of the fluorescent material layer 10 away from the transparent isolation layer 20, the encapsulation structure layer 50 is located on the side of the metal periodic array structure 30 away from the transparent isolation layer. Figure 2 The receiving antenna shown in the figure includes the following layers of materials from top to bottom: packaging structure layer 50, metal periodic array structure 30, transparent isolation layer 20, fluorescent material layer 10 and focusing structure 40. For example, SiO2 material can be used, and the fluorescent material layer 10 is coated on the side away from the transparent isolation layer 20 by magnetron sputtering.

[0048] In the receiving antenna provided in the embodiment of the present application, fluorescent materials with fluorescence spectra covering different bands can be used and applied to optical systems in the visible and near-infrared bands to improve light conversion efficiency, while also improving FOV and optical gain, thereby improving the transmission performance of the optical communication system.

[0049] Based on any of the above embodiments, the fluorescent material layer 10 includes at least one of the following materials: a fluorescent material whose fluorescent spectrum covers the visible light band; a fluorescent material whose fluorescent spectrum covers the infrared band; a superlattice material. Among them, the superlattice material can be a quantum dot self-assembled superlattice, and the quantum dots are spontaneously assembled into a long-range ordered structure through weak interaction forces, which is called a quantum dot self-assembled superlattice.

[0050] In one embodiment of the present application, the fluorescent material whose fluorescence spectrum covers the visible light band includes but is not limited to at least one of the following: perovskite quantum dots; organic light-emitting materials; rare earth fluorescent materials; cadmium-based quantum dots.

[0051] Exemplarily, perovskite quantum dots may include but are not limited to any of the following: cesium tribromolead (CsPbBr3) quantum dots, cesium triiodolead CsPbI3 quantum dots, cesium trichlorolead CsPbCl3 quantum dots. Among them, CsPbBr3 quantum dots can emit green light, CsPbI3 quantum dots can emit red light, and CsPbCl3 quantum dots can emit blue light. Cadmium-based quantum dots include but are not limited to CdSe quantum dots and ZnS quantum dots. CdSe quantum dots and ZnS quantum dots can emit red light. Organic light-emitting materials such as organic dyes.

[0052] In another embodiment of the present application, the fluorescent material whose fluorescence spectrum covers the infrared band includes but is not limited to at least one of the following: CdTe quantum dots, CdS quantum dots, and PbS quantum dots.

[0053] The above-mentioned superlattice materials not only have the performance of a single quantum dot, but also have some new multi-body collaborative phenomena, such as lasing, superfluorescence, superradiance, etc. The generation of superradiance and superfluorescence phenomena can make the radiation lifetime of quantum dot superlattice materials break through the ns level and reach the ps level.

[0054] In the embodiment of the present application, the transparent isolation layer 20 is used to physically separate the fluorescent material layer 10 from the metal periodic array structure 30. The use of a transparent isolation layer can not only stabilize the influence of the precious metal nanoparticles in the metal periodic array structure 30 on thermal and chemical interactions, but also has the following two advantages: first, it can avoid the fluorescence quenching caused by the active electrons in the excited state of the molecules being captured by the particles when the precious metal nanoparticles and the fluorescent material are in direct contact; second, the metal periodic array is used to form collective plasma oscillations, compressing the mode volume of the fluorescent material radiation, reducing the life span and increasing the bandwidth.

[0055] In one embodiment of the present application, the material of the transparent isolation layer 20 may include but is not limited to at least one of the following: PMMA, SiO2, SU-8 photoresist, MgO, TiO2. The transparent isolation layer 20 may also be other organic or inorganic materials with transparent properties. When using different materials, the transparent isolation layer 20 can select a suitable thickness according to its refractive index, so that the optimal distance between the fluorescent material and the metal structure can be maintained to achieve a compromise between bandwidth enhancement and efficiency. Optionally, the thickness of the transparent isolation layer 20 can be set to 0 to 50nm. For example, when using PMMA photoresist with a refractive index of 1.5 to prepare the isolation layer, a thickness of about 10nm is selected, and when using magnesium fluoride material with a refractive index of 1.38 to prepare the isolation layer, a thickness of about 5nm is selected. The following provides a method for preparing a transparent isolation layer 20 using PMMA. For example, PMMA photoresist can be used to spin-coat for 60s at a speed of 9000r / min to obtain a transparent isolation layer 20 with a thickness of 1 to 10nm.

[0056] In an embodiment of the present application, a transparent isolation layer 20 is provided between the fluorescent material layer 10 and the metal periodic array structure 30 in the receiving antenna. Compared with a receiving antenna without a transparent isolation layer 20 between the fluorescent material layer 10 and the metal periodic array structure 30, the photoluminescence quantum yield of the receiving antenna of the present application can be increased by about 20%.

[0057] In one embodiment of the present application, the metal periodic array structure 30 includes but is not limited to any one of the following (1) to (4):

[0058] (1) An array formed by periodic distribution of triangular prism structure metal units;

[0059] As an example, the array formed by the periodic distribution of the triangular prism structure metal units can be an array formed by the periodic distribution of the triangular prism structure metal units with curved sides, such as Figure 1 The metal periodic array structure 30 shown in FIG. The metal periodic array structure 30 can be used as shown in FIG. Figure 3 The single-layered polystyrene (PS) beads shown are used as a mask.

[0060] The following is an embodiment of a method for preparing a metal periodic array structure 30. The preparation method may include the following steps:

[0061] Step S1, a solution containing PS beads with a diameter of 400 nm and a mass percentage of 10 wt% of PS beads is dropped on the water surface to form a temporary alcohol-water bilayer. The PS beads diffuse on the water surface along the alcohol flow, and a part of the alcohol evaporates, and the other part of the alcohol gradually mixes in the water, so that the PS beads float on the gas-liquid interface to form a temporary alcohol-water bilayer. Figure 3 The single-layer structure composed of PS balls is shown. Any three PS balls in the single-layer structure can form a curved triangular gap.

[0062] Step S2, transferring the single-layer structure composed of PS beads to a quartz cone light-collecting structure with a bottom diameter of 15 mm.

[0063] Step S3, evaporating metal (such as silver) on the light collecting structure having a single-layer structure composed of PS beads, and then washing away the PS beads to obtain Figure 1 The metal periodic array structure 30 shown in FIG. Figure 4 As shown, the periodic spacing of the metal periodic array structure 30 can be the diameter of the PS ball.

[0064] The curved triangle structure in the above-mentioned triangular prism structure metal unit has a tip structure with a smaller radius of curvature, and the charges are more densely gathered at the tip structure, making the localized plasmons excited by a single metal unit stronger. When the metal units with periodic distribution of the curved triangle structure are arranged into an ordered array structure, the diffraction waves generated on the surface of the ordered array structure will be resonantly coupled with the localized plasmons of the single metal unit, causing the resonance spectrum to become sharply narrowed. The array structure has a higher quality factor and lower radiation attenuation, thereby improving the light collection efficiency and increasing the bandwidth.

[0065] As another example, the array formed by the periodic distribution of the triangular prism structure metal units can also be as follows: Figure 5 The array formed by the periodic distribution of triangular prism structure metal units with a flat side shown in the figure can be obtained by etching regularly arranged triangular holes on a substrate using an electron beam lithography (EBL) method, then evaporating metal, and then removing the template.

[0066] (2) Figure 6 The cube-structured metal units shown are arranged periodically to form an array.

[0067] The periodic spacing of the cube structure metal unit is the distance between the centers of two adjacent cube structures. The array formed by the periodic distribution of the cube structure metal unit can be obtained by etching regularly arranged square holes on the substrate using the EBL method, then evaporating metal (such as silver), and then removing the template.

[0068] (3) An array formed by periodic distribution of rectangular structured metal units.

[0069] The periodic spacing of the rectangular structure metal unit is the distance between the centers of gravity of two adjacent rectangular structures. The array formed by the periodic distribution of the rectangular structure metal unit can be obtained by etching regularly arranged rectangular small holes on the substrate using the EBL method and then evaporating metal (such as silver).

[0070] (4) Figure 7 The cylindrical structure shown is an array formed by periodic distribution of metal units.

[0071] The periodic spacing of the cylindrical structure metal unit is the distance between the centers of two adjacent circular structures. The array 30-3 formed by the periodic distribution of the cylindrical structure metal unit can be formed by using EBL or porous anodic aluminum oxide (AAO) film template method to form regularly arranged circular small holes on the substrate, and then evaporate metal (such as silver) and remove the template to obtain.

[0072] In the receiving antenna provided in the embodiment of the present application, when using fluorescent materials whose fluorescence spectra cover different bands, different metal periodic array structures can be used to match fluorescent materials whose fluorescence spectra cover different bands. In this way, the desired effect can be achieved as much as possible in combination with different fluorescent materials, such as reducing the fluorescence lifetime of the fluorescent material, increasing the system modulation bandwidth, and improving the transmission performance of the optical communication system.

[0073] In one embodiment of the present application, the material type of the fluorescent material layer 10 and the type of the metal periodic array structure 30 as well as the spacing between adjacent metal units satisfy any of the following conditions:

[0074] (1) The material of the fluorescent material layer 10 is a fluorescent material whose fluorescent spectrum covers the visible light band. The metal periodic array structure 30 is an array formed by periodic distribution of metal units with curved side triangular prism structures, and the spacing between adjacent metal units is 320-480 nm.

[0075] For example, the material of the fluorescent material layer 10 can be a fluorescent material with a fluorescence peak position of 530nm as shown in Table 1 below, such as CsPbBr3 quantum dots, and the metal periodic array structure 30 is an array formed by a periodic distribution of curved side triangular prism structure metal units, and the spacing between adjacent curved side triangular prism structure metal units can be 400nm.

[0076] (2) The material of the fluorescent material layer 10 is a fluorescent material whose fluorescent spectrum covers the infrared band. The metal periodic array structure 30 is an array formed by periodic distribution of metal units with curved side triangular prism structures, and the spacing between adjacent metal units is 960-1440 nm.

[0077] For example, the material of the fluorescent material layer 10 can be a fluorescent material with a fluorescence peak position of 1100nm as shown in Table 1 below, such as PbS quantum dots, and the metal periodic array structure 30 is an array formed by a periodic distribution of curved side triangular prism structure metal units, and the spacing between adjacent curved side triangular prism structure metal units can be 1200nm.

[0078] (3) The material of the fluorescent material layer 10 is a fluorescent material whose fluorescent spectrum covers the blue light band. The metal periodic array structure 30 is an array formed by periodic distribution of cubic structure metal units, and the spacing between adjacent metal units is 200-300 nm.

[0079] For example, the material of the fluorescent material layer 10 can be a fluorescent material with a fluorescence peak position of 440nm as shown in Table 1 below, such as CsPbCl3 quantum dots. The metal periodic array structure 30 is an array formed by periodic distribution of cubic structure metal units, and the spacing between adjacent cubic structure metal units can be 250nm.

[0080] (4) The material of the fluorescent material layer 10 is a fluorescent material whose fluorescent spectrum covers the red light band, and the metal periodic array structure 30 is an array formed by periodic distribution of cubic structure metal units, and the spacing between adjacent metal units is 480-720 nm.

[0081] For example, the material of the fluorescent material layer 10 can be a fluorescent material with a fluorescence peak position of 600nm as shown in Table 1 below, such as CsPbI3 quantum dots. The metal periodic array structure 30 is an array formed by periodic distribution of cubic structure metal units, and the spacing between adjacent cubic structure metal units can be 600nm.

[0082] (5) The material of the fluorescent material layer 10 is a fluorescent material whose fluorescent spectrum covers the blue light band. The metal periodic array structure 30 is an array formed by periodic distribution of cylindrical structure metal units, and the spacing between adjacent metal units is 360-540 nm.

[0083] For example, the material of the fluorescent material layer 10 can be a fluorescent material with a fluorescence peak position of 450nm as shown in Table 1 below, such as GS-Cu nanoparticles. The metal periodic array structure 30 is an array formed by periodic distribution of cylindrical structure metal units, and the spacing between adjacent cylindrical structure metal units can be 450nm.

[0084] Table 1 Examples of matching different metal periodic array structures with different fluorescent material layers 10

[0085] Metal periodic array structure Cycle spacing Fluorescence emission peak position An array formed by periodic distribution of metal units in a triangular prism structure with curved sides 400nm 530nm An array formed by periodic distribution of metal units in a triangular prism structure with curved sides 1200nm 1100nm Array formed by periodic distribution of cube-structured metal units 250nm 440nm Array formed by periodic distribution of cube-structured metal units 600nm 600nm Array formed by periodic distribution of cylindrical metal units 450nm 450nm

[0086] The above-mentioned fluorescent materials with fluorescence spectra covering different bands are used in combination with different metal periodic array structures 30, which can achieve better results in reducing the fluorescence lifetime of the fluorescent materials, improving the system modulation bandwidth and improving the transmission performance of the optical communication system.

[0087] In one embodiment of the present application, the shape of the material of the fluorescent material layer 10 and the shape of the metal periodic array structure 30 can also be matched for use. For example, according to the shape of the material of the fluorescent material layer 10, a metal periodic array structure 30 that matches the shape of the material of the fluorescent material layer 10 is selected, so that a stronger coupling effect can be generated, the radiation life of the fluorescent material can be reduced, and the antenna bandwidth can be increased. Exemplarily, for example, the material of the fluorescent material layer 10 is a CsPbBr3 superlattice material, and the CsPbBr3 superlattice material is a square superlattice structure, which can be matched with an array formed by a periodic distribution of metal units of a cube structure. The preparation process of the array formed by the periodic distribution of metal units of a cube structure is mostly EBL, which is relatively expensive.

[0088] For another example, the material of the fluorescent material layer 10 is PbS quantum dots, which are mostly spherical and can be used to match the array formed by the periodic distribution of cylindrical structure metal units. The preparation process of the array formed by the periodic distribution of cylindrical structure metal units can be selected from the AAO template method, which is economical and affordable.

[0089] For another example, the material of the fluorescent material layer 10 is PbS quantum dots. Changing the shape of the PbS quantum dots into a square is conducive to assembling into a superlattice. The square PbS quantum dots can be used to match the array formed by the periodic distribution of cube-structured metal units. The preparation process of the array formed by the periodic distribution of cube-structured metal units is mostly EBL, which is relatively costly.

[0090] For another example, the material of the fluorescent material layer 10 is CsPbI3 quantum dots, which can be used to match an array formed by a periodic distribution of triangular prism structure metal units. The array formed by a periodic distribution of triangular prism structure metal units with curved sides is preferred because the local electric field enhancement at the tip of the curved triangle in the triangular prism structure metal unit with curved sides is higher than the local electric field enhancement at the tip of the triangle in the triangular prism structure metal unit with a flat side, and the preparation process of the array formed by the periodic distribution of triangular prism structure metal units with curved sides is simpler and has a higher success rate.

[0091] In one embodiment of the present application, the light-focusing structure 40 includes a top surface, a side surface, and a bottom surface. One end of the side surface is connected to the top surface, and the other end is connected to the bottom surface. The top surface is used to receive the fluorescent signal emitted by the fluorescent material layer and entering the light-focusing structure 40, and the bottom surface is used to emit the outgoing light signal obtained by converging the fluorescent signal through the light-focusing structure 40. The area of ​​the top surface of the light-focusing structure 40 is larger, and it can receive fluorescent signals with a large field of view. After being concentrated by the light-focusing structure 40, the fluorescent signal is emitted from the bottom surface of the light-focusing structure 40 to the photosensitive surface on the photodetector. Since the photosensitive surface on the photodetector is small, the area of ​​the bottom surface of the light-focusing structure 40 is small, so that the outgoing light signal can be received by the photodetector as much as possible, thereby achieving optical gain and effectively improving the modulation bandwidth.

[0092] The light-concentrating structure 40 may be a cone, and the shape of the light-concentrating structure 40 may be realized in various ways.

[0093] In a possible implementation of the present application, the light-focusing structure 40 is in the shape of a truncated cone.

[0094] In one embodiment, the light focusing structure 40 may be in the shape of a frustum, which may also be called a truncated cone, for example Figure 8 The truncated cone-shaped focusing structure shown in FIG. Figure 1 A section of the top of the cone is cut off to form a top surface, and a truncated cone is obtained. The top of the light collecting structure is convenient for installing a photodetector, and the light collecting area of ​​the photodetector can be guaranteed. For example, the height of the light collecting structure 40 is 15 mm, the top surface is a circular surface with a diameter of 1 mm, and the bottom surface is a circular surface with a diameter of 20 mm. The outgoing light signal is emitted from the top surface of the truncated cone.

[0095] In another embodiment, the light-focusing structure 40 may be in the shape of an oblique truncated cone.

[0096] In another embodiment, the light-concentrating structure 40 may be in the shape of a truncated pyramid, which may also be called a truncated pyramid. In another embodiment, the light-concentrating structure 40 may be in the shape of a truncated pyramid.

[0097] In another possible implementation of the present application, the shape of the light focusing structure 40 is as follows: Fig. 9 In the compound parabolic concentrator (CPC) shown in the figure, after the fluorescence signal enters the compound parabolic concentrator, it reaches the photodetector after several reflections, and the fluorescence signal loss is small. Moreover, the compound parabolic concentrator can also effectively collect obliquely incident fluorescence to achieve the maximum theoretical concentration ratio, and the performance is very close to that of an ideal concentrator.

[0098] Based on any of the above embodiments, the side of the focusing structure 40 can be coated. For example, the material of the side of the focusing structure 40 can be a total reflection film. By coating the total reflection film, the fluorescent signal will not be emitted from the side after entering the focusing structure 40, which can reduce the loss of the fluorescent signal and improve the light receiving efficiency of the receiving antenna.

[0099] As an example, the material of the total reflection film may include but is not limited to any of the following: silver film, aluminum film, gold film, dielectric and EUV multilayer film.

[0100] Below Figure 1 Taking the receiving antenna shown in the figure as an example, the working process of the receiving antenna is introduced.

[0101] like Figure 1 As shown, the working process of the receiving antenna includes the following steps:

[0102] S1, the incident light signal enters the light receiving antenna from the packaging structure layer 50.

[0103] S2, the incident light signal excites surface plasmon resonance in the metal periodic array structure 30, thereby enhancing the local electromagnetic field around the metal units in the metal periodic array structure 30.

[0104] S3, the fluorescent material layer 10 affected by the local electromagnetic field emits fluorescent light of a specific wavelength.

[0105] The material of the fluorescent material layer 10 is different, and the wavelength of the fluorescence emitted by the fluorescent material layer 10 in step S3 is also different. For example, the fluorescent material layer 10 is a fluorescent material whose emission spectrum covers the visible light band, and the fluorescent material layer 10 in step S3 emits visible light. For another example, the fluorescent material layer 10 is a fluorescent material whose emission spectrum covers the infrared light band, and the fluorescent material layer 10 in step S3 emits infrared light.

[0106] S4, the fluorescence emitted by the fluorescent material enters the light-condensing structure 40 from the top surface of the light-condensing structure 40, is converged to a point by the light-condensing structure 40, and is emitted from the bottom surface of the light-condensing structure 40, so that the outgoing light signal can be emitted to the photosensitive surface of the photodetector.

[0107] The receiving antenna of the present application, since it includes at least a fluorescent material layer, a metal periodic array structure, a transparent isolation layer located between the fluorescent material layer and the metal periodic array structure, and a focusing structure, can achieve a large field of view and high-efficiency light collection, and can also reduce the fluorescence lifetime.

[0108] An embodiment of the present application also provides a receiving device, which includes the receiving antenna provided by any of the above embodiments.

[0109] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A receiving antenna, characterized in that: include: a fluorescent material layer; Metal periodic array structure; a transparent isolation layer, wherein the transparent isolation layer is located between the fluorescent material layer and the metal periodic array structure; A light-concentrating structure is located on a side of the fluorescent material layer away from the transparent isolation layer, or the light-concentrating structure is located on a side of the metal periodic array structure away from the transparent isolation layer.

2. The receiving antenna according to claim 1, characterized in that The metal periodic array structure includes any one of the following: An array formed by a periodic distribution of triangular prism structure metal units; an array formed by a periodic distribution of cube structure metal units; an array formed by a periodic distribution of rectangular structure metal units; an array formed by a periodic distribution of cylindrical structure metal units.

3. The receiving antenna according to claim 2, characterized in that The array formed by the periodic distribution of the triangular prism structure metal units is an array formed by the periodic distribution of the triangular prism structure metal units with curved sides.

4. The receiving antenna according to any one of claims 1 to 3, characterized in that: The fluorescent material layer includes at least one of the following materials: Fluorescent materials whose fluorescence spectra cover the visible light band; fluorescent materials whose fluorescence spectra cover the infrared band; superlattice materials.

5. The receiving antenna according to claim 4, characterized in that The fluorescent material whose fluorescent spectrum covers the visible light band includes at least one of the following: Perovskite quantum dots; organic light-emitting materials; rare earth fluorescent materials; cadmium-based quantum dots; near-infrared quantum dots.

6. The receiving antenna according to any one of claims 1 to 3, characterized in that: The material type of the fluorescent material layer, the type of the metal periodic array structure, and the spacing between adjacent metal units satisfy any of the following: The material of the fluorescent material layer is a fluorescent material whose fluorescent spectrum covers the visible light band, and the metal periodic array structure is an array formed by periodic distribution of metal units of curved side triangular prism structure, and the spacing between adjacent metal units is 320-480nm; The material of the fluorescent material layer is a fluorescent material whose fluorescent spectrum covers the infrared band, and the metal periodic array structure is an array formed by periodic distribution of metal units with curved side triangular prism structures, and the spacing between adjacent metal units is 960-1440nm; The material of the fluorescent material layer is a fluorescent material whose fluorescent spectrum covers the blue light band, and the metal periodic array structure is an array formed by periodic distribution of cubic structure metal units, and the spacing between adjacent metal units is 200-300nm; The material of the fluorescent material layer is a fluorescent material whose fluorescent spectrum covers the red light band, and the metal periodic array structure is an array formed by periodic distribution of cubic structure metal units, and the spacing between adjacent metal units is 480-720nm; The material of the fluorescent material layer is a fluorescent material whose fluorescent spectrum covers the blue light band. The metal periodic array structure is an array formed by periodic distribution of cylindrical structure metal units, and the spacing between adjacent metal units is 360-540nm.

7. The receiving antenna according to any one of claims 1 to 6, characterized in that: The focusing structure includes a top surface, a side surface and a bottom surface, one end of the side surface is connected to the top surface, and the other end is connected to the bottom surface, the top surface is used to receive the fluorescent signal emitted by the fluorescent material layer and entering the focusing structure, and the bottom surface is used to emit the output light signal obtained by converging the fluorescent signal through the focusing structure; the area of ​​the top surface is larger than the area of ​​the bottom surface.

8. The receiving antenna according to claim 7, characterized in that The light-focusing structure is in the shape of a truncated cone.

9. The receiving antenna according to claim 7, characterized in that: The light-concentrating structure is in the shape of a compound parabolic concentrator.

10. The receiving antenna according to any one of claims 7 to 9, characterized in that: The material of the side surface is a total reflection film.

11. The receiving antenna according to any one of claims 1 to 10, characterized in that: The receiving antenna also includes a packaging structure layer; If the light-concentrating structure is located on a side of the fluorescent material layer away from the transparent isolation layer, the encapsulation structure layer is located on a side of the metal periodic array structure away from the transparent isolation layer; or, If the light-concentrating structure is located on a side of the metal periodic array structure away from the transparent isolation layer, the encapsulation structure layer is located on a side of the fluorescent material layer away from the transparent isolation layer.

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