Efficient focusing metasurface optical fiber coupler and multimode optical fiber coupling device

Abstract

The invention discloses an efficient focusing metasurface optical fiber coupler and a multimode optical fiber coupling device. The metasurface optical fiber coupler comprises an optical fiber, a metasurface assembly and a supporting structural member. The optical fiber comprises a fiber core and a wrapping layer wrapping the outer layer of the fiber core, the metasurface assembly comprises a substrate and a micro-nano structure arranged at one end of the substrate and periodically arranged, and the surface layer of the micro-nano structure is covered with a layer of thin film; the end, provided with the micro-nano structure, of the metasurface assembly faces the optical fiber. A gap is formed between the substrate and the micro-nano structure; the side edge of the metasurface assembly is connected with the supporting structural member. According to the high-efficiency focusing metasurface optical fiber coupler, the micro-nano structure provided with the metasurface is combined, so that the problems existing in traditional single-mode and multi-mode optical fiber coupling devices can be well solved; higher focusing efficiency can be realized in a relatively small optical system, the compactness of the device is improved, and the device can be conveniently integrated into optical fiber communication equipment; moreover, the focusing effect can be improved, and the transmission performance of optical signals can be greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of fiber optic couplers, and in particular, to a highly efficient focusing metasurface fiber optic coupler and a multimode fiber optic coupling device. Background Art

[0002] Fiber optic communication is a communication method that uses light waves as information carriers and optical fibers as transmission media. It has become one of the main pillars of modern communication and has broad application and development prospects in the communication field.

[0003] Fiber optic communication is mainly applied to fields such as communication network construction, data center construction, intelligent transportation systems, and the energy industry. For example, most home broadband networks are based on fiber optic communication, enabling people to smoothly watch high-definition videos, play online games, etc.; in intelligent transportation systems, this technology can be used to achieve information interaction between vehicles and between vehicles and infrastructure, improving road safety and efficiency; fiber optic communication can also be applied to the exploration and development of oil and natural gas, improving the safety and economy of energy extraction. Fiber optic communication has the advantages of large communication capacity, long relay distance, good confidentiality, etc., and the raw material sources are rich and the potential price is low.

[0004] A fiber optic communication system mainly consists of the following parts: a light source, which can be a laser or a light-emitting diode; an optical fiber, including a core, a cladding, and a coating layer; an optical transmitter; an optical repeater; an optical receiver; an optical amplifier; an optical filter; an optical switch and a multiplexer; an optical fiber connector and a coupler. Among them, a fiber optic coupler is an optical device used to couple an optical signal from one or more optical fibers to another or more optical fibers. It realizes the distribution or combination of optical power between different optical fibers. The focusing efficiency of a fiber optic coupler refers to the ability to effectively focus the input light onto the output optical fiber or a specific area. A higher focusing efficiency means that the light energy can be utilized more effectively, reducing energy loss, which is of great significance for ensuring the quality and transmission performance of optical signals.

[0005] However, the fiber optic couplers applied in the prior art have various problems. Traditional fiber optic couplers are large in volume and heavy in weight, and cannot achieve miniaturization, lightweight, and integration; moreover, the manufacturing process of traditional fiber optic couplers is complex and costly. The focused light spot of traditional fiber optic couplers is usually relatively large, the energy is not concentrated and is easily lost, so the focusing efficiency is low; the internal structure of traditional multimode fiber optic coupling devices is complex, resulting in difficult assembly. Therefore, the fiber optic couplers in the prior art have problems of complex structure and poor focusing effect. Summary of the Invention

[0006] Embodiments of the present invention provide a highly efficient focusing metasurface fiber optic coupler and a multimode fiber optic coupling device, aiming to solve the problems of complex structure and poor focusing effect existing in the fiber optic couplers in the prior art methods.

[0007] In a first aspect, an embodiment of the present invention provides a highly efficient focusing metasurface fiber coupler, wherein the metasurface fiber coupler includes an optical fiber, a metasurface component, and a support structure; The optical fiber includes a core and a cladding wrapped around the outer layer of the core. The metasurface component includes a substrate and micro-nano structures arranged in a periodic manner at one end of the substrate. A thin film covers the surface layer of the micro-nano structures; the end of the metasurface component where the micro-nano structures are arranged faces the optical fiber; there is a gap between the optical fiber and the micro-nano structures; The side of the metasurface component is connected to the support structure; The metasurface fiber coupler satisfies 0.5 ≤ F ≤ 4.0, 0.002 μm ≤ Φ RMS ≤ 3.500 μm 、0.005 μm ≤ Φ GEO ≤ 6.000 μm ; F is the focal ratio, Φ RMS is the average diameter of the focused spot, Φ GEO is the geometric diameter of the focused spot.

[0008] For the highly efficient focusing metasurface fiber coupler, it further includes a diaphragm; The diaphragm is arranged on the micro-nano structure side or the substrate side of the metasurface component. The micro-nano structure side is the end of the substrate where the micro-nano structures are arranged, and the substrate side is the other end of the substrate where the micro-nano structures are not arranged.

[0009] For the highly efficient focusing metasurface fiber coupler, the diaphragm is respectively arranged on the micro-nano structure side and the substrate side of the metasurface component.

[0010] For the highly efficient focusing metasurface fiber coupler, the thickness of the substrate along the optical axis is 0.3 - 3 mm.

[0011] For the highly efficient focusing metasurface fiber coupler, the material of the substrate is amorphous silicon, crystalline silicon, borosilicate, silica, quartz, or glass.

[0012] For the highly efficient focusing metasurface fiber coupler, the material of the micro-nano structures is amorphous silicon, crystalline silicon, silica, silicon nitride, or titanium dioxide.

[0013] The described highly efficient focusing metasurface fiber coupler, wherein an antireflection film is formed by coating the outer surface of the thin film in the metasurface component and the side surface of the substrate respectively.

[0014] The described highly efficient focusing metasurface fiber coupler, wherein the length of the gap along the optical axis is 0.08 - 0.4 mm.

[0015] The described highly efficient focusing metasurface fiber coupler, wherein the support structure extends towards the fiber side to form an opening; the fiber is embedded in the opening for fixation.

[0016] In a second aspect, an embodiment of the present invention further provides a multimode fiber coupling device, which comprises a plurality of highly efficient focusing metasurface fiber couplers as described in the first aspect above. Among them, the plurality of metasurface fiber couplers are arranged in an ordered or disordered manner to form a multimode fiber coupling device capable of simultaneously transmitting multiple optical signals.

[0017] An embodiment of the present invention provides a highly efficient focusing metasurface fiber coupler and a multimode fiber coupling device. The metasurface fiber coupler includes a fiber, a metasurface component, and a support structure; the fiber includes a core and a cladding wrapped around the outer layer of the core, the metasurface component includes a substrate and a micro-nano structure arranged in a periodic manner at one end of the substrate, and a thin film covers the surface layer of the micro-nano structure; one end of the metasurface component provided with the micro-nano structure faces the fiber; there is a gap between them; the side of the metasurface component is connected to the support structure. The above-mentioned highly efficient focusing metasurface fiber coupler, combined with the micro-nano structure of the metasurface, can well solve the problems existing in traditional single-mode and multimode fiber coupling devices; it can achieve higher focusing efficiency in a relatively small optical system, reduce the volume and weight of the optical system, improve the compactness of the device, and is convenient to be integrated into fiber communication devices; and it can improve the focusing effect and greatly enhance the transmission performance of optical signals. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0019] Figure 1 It is a cross-sectional structure diagram of the highly efficient focusing metasurface fiber coupler provided by the embodiment of the present invention; Figure 2 It is a schematic diagram of the dispersion spot of the highly efficient focusing metasurface fiber coupler provided by the embodiment of the present invention; Figure 3Another cross-sectional structure diagram of the high-efficiency focusing metasurface fiber coupler provided by the embodiment of the present invention; Figure 4 Another schematic diagram of the spot size of the high-efficiency focusing metasurface fiber coupler provided by the embodiment of the present invention; Figure 5 Structure diagram of the multimode fiber coupling device provided by the embodiment of the present invention; Figure 6 Schematic diagram of the spot size of the multimode fiber coupling device provided by the embodiment of the present invention at the working wavelength of 1270 nm; Figure 7 Schematic diagram of the spot size of the multimode fiber coupling device provided by the embodiment of the present invention at the working wavelength of 1280 nm; Figure 8 Schematic diagram of the spot size of the multimode fiber coupling device provided by the embodiment of the present invention at the working wavelength of 1290 nm; Figure 9 Schematic diagram of the spot size of the multimode fiber coupling device provided by the embodiment of the present invention at the working wavelength of 1300 nm; Figure 10 Schematic diagram of the spot size of the multimode fiber coupling device provided by the embodiment of the present invention at the working wavelength of 1310 nm; Figure 11 Schematic diagram of the spot size of the multimode fiber coupling device provided by the embodiment of the present invention at the working wavelength of 1320 nm; Figure 12 Schematic diagram of the spot size of the multimode fiber coupling device provided by the embodiment of the present invention at the working wavelength of 13,30 nm; Figure 13 Schematic diagram of the spot size of the multimode fiber coupling device provided by the embodiment of the present invention at the working wavelength of 1340 nm; Figure 14 Schematic diagram of the spot size of the multimode fiber coupling device provided by the embodiment of the present invention at the working wavelength of 1350 nm; Reference numerals: 110, optical fiber; 20, metasurface component; 120, micro-nano structure; 130, substrate; 150, support structure member; 1, optical fiber output surface; 2, micro-nano structure side; 3, substrate side; 4, area to be focused. Detailed implementation manners

[0020] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0021] It should be understood that when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, wholes, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0022] It should also be understood that the terms used in the specification of the present invention are for the purpose of describing particular embodiments only and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly dictates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms.

[0023] It should be further understood that the term "and / or" used in the specification of the present invention and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0024] Please refer to Figure 1 and Figure 3 , as shown in the figure, an embodiment of the present application discloses a highly focused metasurface fiber coupler, which includes an optical fiber, a metasurface component, and a support structure; the optical fiber includes a core and a cladding wrapped around the outer layer of the core, the metasurface component includes a substrate and micro-nano structures arranged in a periodic manner at one end of the substrate, and a thin film covers the surface layer of the micro-nano structures; the end of the metasurface component where the micro-nano structures are arranged faces the optical fiber; there is a gap between the optical fiber and the micro-nano structures; the side of the metasurface component is connected to the support structure; the metasurface fiber coupler satisfies 0.5 ≤ F ≤ 4.0, 0.002 μm ≤ Φ RMS ≤ 3.500 μm 、0.005 μm ≤ Φ GEO ≤ 6.000 μm ; F is the focal ratio, Φ RMS is the average diameter of the focused spot, Φ GEO is the geometric diameter of the focused spot.

[0025] On the side of the metasurface component close to the optical fiber, a metasurface structure is formed, which includes micro-nano structures arranged in a periodic manner, and a thin film covers the surface layer of the micro-nano structures to protect the micro-nano structures. The substrate is connected to the support structure, and there is a gap between the optical fiber and the micro-nano structures. The size of the gap between the optical fiber and the metasurface structure can be adjusted by adjusting the insertion depth of the optical fiber.

[0026] In a more specific embodiment, the above-mentioned metasurface fiber coupler further includes a diaphragm; the diaphragm is disposed on the micro-nano structure side or the substrate side of the metasurface component, the micro-nano structure side is one end of the substrate where the micro-nano structure is disposed, and the substrate side is the other end of the substrate where the micro-nano structure is not disposed. Specifically, the diaphragms are respectively disposed on the micro-nano structure side and the substrate side of the metasurface component.

[0027] To further improve the focusing effect of the metasurface fiber coupler, a diaphragm can be provided, specifically a screen-printed diaphragm; the screen-printed diaphragm is disposed on the plane of the micro-nano structure side or the plane of the substrate side. To further improve the focusing effect, the screen-printed diaphragms can be simultaneously disposed on the plane of the micro-nano structure side and the plane of the substrate side.

[0028] In a more specific embodiment, the thickness of the substrate along the optical axis is 0.3 - 3 mm. Among them, the material of the substrate is amorphous silicon, crystalline silicon, borosilicate, silicon dioxide, quartz or glass.

[0029] In a more specific embodiment, the material of the micro-nano structure is amorphous silicon, crystalline silicon, silicon dioxide, silicon nitride or titanium dioxide. Further, antireflection films are respectively coated on the outer surface of the thin film in the metasurface component and the surface of the substrate side. Among them, the length of the gap along the optical axis is 0.08 - 0.4 mm.

[0030] By coating the antireflection film, the antireflection properties of the micro-nano structure side and the substrate side in the metasurface component can be improved, and the transmission performance of the optical signal can be enhanced.

[0031] In a more specific embodiment, the support structure member extends towards the fiber side to form an opening; the fiber is embedded in the opening for fixation. When an opening is formed on the side of the support structure member opposite to the fiber, the fiber can be inserted into the opening of the support structure member, thereby realizing the alignment of the fiber and the metasurface structure, and at the same time, the gap size between the fiber and the metasurface can be determined by adjusting the insertion depth of the fiber.

[0032] The operating temperature of the above-mentioned metasurface fiber coupler is -30°C to 70°C.

[0033] A metasurface is the two-dimensional counterpart of electromagnetic materials. It is a two-dimensional artificial electromagnetic material composed of a large number of carefully designed unit arrangements. By interacting with the electromagnetic field, it generates various unique electromagnetic responses that natural materials do not possess. It can actively and intelligently control spatial electromagnetic waves in a programmable manner. By changing the structure, layout, and working mode of the basic units of the metasurface, precise control of the amplitude, phase, polarization, etc. of the incident electromagnetic wave can be achieved. Compared with traditional fiber couplers, the metasurface fiber coupler in the embodiments of this application has a simpler structure, smaller size, is easy to integrate, has a small focused spot, has low energy loss, and the metasurface design is flexible, which can adapt to different application scenarios and requirements.

[0034] Embodiment 1 Exemplarily, Table 1 details the specific optical data parameters of the highly focused metasurface fiber coupler provided by the embodiments of the present invention in a feasible implementation manner. The optical data parameters in Table 1 correspond to Figure 1 the highly focused metasurface fiber coupler shown; Table 1

[0035] Among them, surface serial number 1 correspondingly represents the light-emitting surface of optical fiber 110; surface serial number 2 correspondingly represents the plane on the micro-nano structure side; surface serial number 3 correspondingly represents the plane on the substrate side; surface serial number 4 correspondingly represents the area to be focused. Among them, the metasurface microstructure side (micro-nano structure side) is aligned with the optical fiber light outlet, the silk screen aperture is located on the micro-nano structure side, and the substrate side is aligned with the receiver or the area to be focused. Among them, the radius of curvature represents the degree of curvature of the lens surface. A positive value represents that the surface bends towards the image plane side, and a negative value represents that the surface bends towards the object plane side. In the embodiments of this application, each surface is a plane, so the radius of curvature is all "0". The spacing represents the central axial distance between the current surface and the next surface. The units of the radius of curvature and the spacing are both millimeters (mm); among them, the spacing of surface serial number 1 is "0.2 mm", that is, it correspondingly represents that the gap (the length along the optical axis direction) between the optical fiber and the micro-nano structure is 0.2 mm.

[0036] Exemplarily, Table 2 details the phase of the metasurface in this embodiment in a feasible implementation manner; Table 2

[0037] Among them, R1 is the normalized radius of the binary surface. In this embodiment, the average diameter of the focused spot satisfies: Φ RMS =0.004 μm , and the geometric diameter satisfies: Φ GEO =0.008 μm; The F-number of the optical system (also known as the focal ratio or aperture number) satisfies: F = 1.0; The operating wavelength of the fiber coupler provided in this embodiment is 1310 nm. A1 is the correction intensity of the basic term, which can only achieve the focusing of an ideal thin lens, but there are actually aberrations; A2 - A5 are the correction intensities of the high-order terms, compensating for manufacturing errors, material dispersion, and wavefront distortion to ensure energy concentration (such as Figure 2 shown with a very small spot size). The difference in the order of magnitude of the coefficients of A1 - A5 reflects the correction intensity of different orders of aberrations; for example, A4 is the largest, indicating that the correction requirement for marginal aberrations is significant.

[0038] Figure 2 is the schematic diagram of the spot size of the metasurface fiber coupler provided by the embodiment of the present invention. Figure 2 In it, "deg" represents the abbreviation of "degree", which is a symbol in mathematics used to represent the unit of the degree of an angle; OBJ represents the position of the object, that is, the position where the light starts to enter the optical system (the light incident surface position of the fiber); IMA represents the image plane, which is the position where the image is formed after the light passes through the optical system (the area to be focused), and the blue "+" mark is the spot. The high-efficiency focusing metasurface fiber coupler provided by the embodiment of the present invention has a small spot diameter and concentrated energy, and can meet the usage requirements of fiber optic communication.

[0039] Embodiment 2 Exemplarily, Table 3 details the specific optical data parameters of the high-efficiency focusing metasurface fiber coupler provided by the embodiment of the present invention in a feasible implementation manner. The optical data parameters in Table 3 correspond to Figure 3 the shown high-efficiency focusing metasurface fiber coupler; Table 3

[0040] Among them, surface serial number 1 corresponds to the light-emitting surface of fiber 110; surface serial number 2 corresponds to the plane on the micro-nano structure side; surface serial number 3 corresponds to the plane on the substrate side; surface serial number 4 corresponds to the area to be focused. Among them, the metasurface microstructure side (micro-nano structure side) is aligned with the fiber light outlet, the silk-screen aperture is located on the micro-nano structure side, and the substrate side is aligned with the receiver or the area to be focused. The radius of curvature represents the degree of curvature of the lens surface. A positive value represents that the surface bends towards the image plane side, and a negative value represents that the surface bends towards the object plane side. In the embodiments of this application, each surface is a plane, so the radius of curvature is "0". The spacing represents the central axial distance between the current surface and the next surface. The units of the radius of curvature and the spacing are both millimeters (mm); among them, the spacing of surface serial number 1 is "0.2 mm", which also corresponds to the gap (the length along the optical axis direction) between the fiber and the micro-nano structure being 0.2 mm.

[0041] Exemplarily, Table 4 details the phase of the metasurface in this embodiment in a feasible implementation manner; Table 4

[0042] wherein, R1 is the normalized radius of the binary surface. In this embodiment, the average diameter of the focused spot satisfies: Φ RMS =3.048 μm , and the geometric diameter satisfies: Φ GEO =5.454 μm ; the F-number (also known as the focal ratio or aperture number) of the optical system satisfies: F =3.8; the operating wavelength of the fiber coupler provided in this embodiment is 1310 nm.

[0043] Figure 4 This is another schematic diagram of the dispersion spot of the metasurface fiber coupler provided by the embodiment of the present invention. The highly focused metasurface fiber coupler provided by the embodiment of the present invention has a small spot diameter and concentrated energy, and can meet the usage requirements of optical fiber communication.

[0044] In summary, the metasurface fiber coupler provided by the embodiment of the present invention has a small focused spot, concentrated energy, a small volume, and a simple structure. While saving costs, it can meet the requirements of high focusing efficiency and integration and lightweight.

[0045] The above-mentioned fiber coupler combined with the metasurface can well solve the problems existing in traditional single-mode and multi-mode fiber coupling devices, can achieve higher focusing efficiency in a relatively small optical system, helps to reduce the volume and weight of the optical system, is convenient to be integrated into optical fiber communication equipment, and greatly improves the transmission performance of optical signals.

[0046] Please refer to Figure 5 , as shown in the figure, the embodiment of the present application also discloses a multi-mode fiber coupling device. The multi-mode fiber coupling device includes a plurality of highly focused metasurface fiber couplers as described in the above embodiment. The combined multi-mode fiber coupling device is also a metasurface multi-mode fiber coupling device; wherein, the plurality of metasurface fiber couplers are combined and arranged in an ordered or disordered manner to serve as a multi-mode fiber coupling device capable of simultaneously transmitting multiple optical signals.

[0047] Embodiment 3 Exemplarily, the embodiment of the present invention combines and arranges 9 highly focused metasurface fiber couplers in the form of a nine-square grid, such as Figure 5As shown, optical signals with wavelengths of 1270 nm, 1280 nm, 1290 nm, 1300 nm, 1310 nm, 1320 nm, 1330 nm, 1340 nm, and 1350 nm are transmitted respectively. Table 5 shows detailed optical data parameters; Table 5

[0048] Among them, surface serial number 1 correspondingly represents the light-emitting surface of optical fiber 110; surface serial number 2 correspondingly represents the plane on the micro-nano structure side; surface serial number 3 correspondingly represents the plane on the substrate side; surface serial number 4 correspondingly represents the area to be focused. Among them, the metasurface microstructure side (micro-nano structure side) is aligned with the light outlet of the optical fiber, the silk-screen diaphragm is located on the micro-nano structure side, and the substrate side is aligned with the receiver or the area to be focused. Among them, the radius of curvature represents the degree of bending of the lens surface. A positive value represents that the surface bends towards the image plane side, and a negative value represents that the surface bends towards the object plane side. In the embodiments of the present application, each surface is a plane, so the radius of curvature is all "0". The spacing represents the central axial distance between the current surface and the next surface. The units of the radius of curvature and the spacing are both millimeters (mm); among them, the spacing of surface serial number 1 is "0.2 mm", that is, it correspondingly represents that the gap (the length along the optical axis direction) between the optical fiber and the micro-nano structure is 0.2 mm.

[0049] Exemplarily, Table 6 details the phases of the metasurfaces corresponding to each wavelength in this embodiment in a feasible implementation manner; Table 6

[0050] Among them, R1 is the normalized radius of the binary surface. In this embodiment, the average diameter of the focused spot satisfies: Φ RMS =0.4~0.5 μm and the geometric diameter satisfies: Φ GEO =0.8~0.9 μm ; the F-number (F-number, also known as the focal ratio or aperture number) of the optical system satisfies: F =0.8.

[0051] Figures 6 - 14 This is a schematic diagram of the dispersion spot of the metasurface multimode fiber coupling device provided by the embodiment of the present invention at each working wavelength. The multimode fiber coupling device provided by the embodiment of the present invention has high transmission efficiency and low loss. Compared with the traditional multimode fiber coupling device, it has a simple structure, low assembly difficulty, and is suitable for mass production.

[0052] In Embodiment 1, Embodiment 2, and Embodiment 3, the device performance parameters respectively satisfy the relationships shown in Table 7 below: Table 7

[0053] The high-efficiency focusing metasurface fiber coupler in the embodiments of the present application has the following advantages: 1. Adopting the technical solution of a single-piece metasurface to realize a fiber coupler with high focusing efficiency, the energy is concentrated, ensuring the quality and transmission performance of the optical signal; 2. The manufacturing process of the metasurface is relatively simple, and conventional photolithography, sputtering, spraying and other methods can be used, with low cost; 3. Using the technical solution of the metasurface to reduce the volume and weight of the optical system, which is convenient to be integrated into fiber communication devices to achieve miniaturization, light weight and integration design; 4. By combining and arranging multiple metasurface fiber couplers, a multimode fiber coupling device can be fabricated, with high transmission efficiency and low loss. Compared with the traditional multimode fiber coupling device, it has a simple structure, low assembly difficulty and is suitable for mass production.

[0054] In the high-efficiency focusing metasurface fiber coupler and multimode fiber coupling device provided by the embodiments of the present invention, the metasurface fiber coupler includes an optical fiber, a metasurface component and a support structure member; the optical fiber includes a core and a cladding wrapped around the outer layer of the core, the metasurface component includes a substrate and micro-nano structures arranged in a periodic manner at one end of the substrate, and a thin film covers the surface layer of the micro-nano structures; the end of the metasurface component where the micro-nano structures are arranged faces the optical fiber; there is a gap between the micro-nano structures; and the side of the metasurface component is connected to the support structure member. The above-mentioned high-efficiency focusing metasurface fiber coupler, combined with the micro-nano structures of the metasurface, can well solve the problems existing in traditional single-mode and multimode fiber coupling devices; it can achieve higher focusing efficiency in a relatively small optical system, reduce the volume and weight of the optical system, improve the compactness of the device, and is convenient to be integrated into fiber communication devices; and it can improve the focusing effect and greatly enhance the transmission performance of the optical signal.

[0055] As mentioned above, the above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. An efficient focusing metasurface fiber coupler, characterized in that It includes an optical fiber, a metasurface component and a support structure; The optical fiber includes a core and a cladding wrapped around the outer layer of the core. The metasurface component includes a substrate and micro-nano structures arranged in a periodic manner at one end of the substrate. A thin film covers the surface of the micro-nano structures. The end of the metasurface component where the micro-nano structures are provided faces the optical fiber. There is a gap between the optical fiber and the micro-nano structures; The side of the metasurface component is connected to the support structure; The metasurface fiber coupler satisfies 0.5 ≤ F ≤ 4.0, 0.002 μm ≤ Φ RMS ≤ 3.500 μm , 0.005 μm ≤ Φ GEO ≤ 6.000 μm ; F is the focal ratio, Φ RMS is the average diameter of the focused spot, Φ GEO is the geometric diameter of the focused spot.

2. The highly efficient focusing metasurface fiber coupler according to claim 1, characterized in that, It further includes a diaphragm; The diaphragm is arranged on the micro-nano structure side or the substrate side of the metasurface component. The micro-nano structure side is the end of the substrate where the micro-nano structures are provided, and the substrate side is the other end of the substrate where no micro-nano structures are provided.

3. The highly efficient focusing metasurface fiber coupler according to claim 2, wherein The diaphragm is respectively arranged on the micro-nano structure side and the substrate side of the metasurface component.

4. The highly efficient focusing metasurface fiber coupler according to any one of claims 1-3, characterized in that, The thickness of the substrate along the optical axis is 0.3 - 3 mm.

5. The highly efficient focusing metasurface fiber coupler according to claim 4, wherein The material of the substrate is amorphous silicon, crystalline silicon, borosilicate, silicon dioxide, quartz or glass.

6. The highly efficient focusing metasurface fiber coupler according to any one of claims 1-3, characterized in that, The material of the micro-nano structures is amorphous silicon, crystalline silicon, silicon dioxide, silicon nitride or titanium dioxide.

7. The highly efficient focusing metasurface fiber coupler according to claim 6, wherein Anti-reflection films are respectively coated on the outer surface of the thin film in the metasurface component and the surface of the substrate side.

8. The highly efficient focusing metasurface fiber coupler according to claim 7, wherein The length of the gap along the optical axis is 0.08 - 0.4 mm.

9. The highly efficient focusing metasurface fiber coupler according to claim 8, wherein The support structure extends towards the side of the optical fiber to form an opening. The optical fiber is embedded in the opening for fixation.

10. A multimode fiber coupling device, the multimode fiber coupling device comprising a plurality of highly efficient focusing metasurface fiber couplers as described in any one of claims 1-9, characterized in that, Multiple such metasurface optical fiber couplers are arranged in an ordered or disordered manner to form a multimode fiber coupling device capable of simultaneously transmitting multiple optical signals.

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