An integrated fiber end splitter for a multi-core optical fiber

Abstract

The utility model discloses an integrated fiber end beam splitter for multicore optical fiber, including the sheath and the inside bushing of its multicore optical fiber, and the multicore optical fiber includes a plurality of independent setting fiber cores, and the one end of each fiber core is induced modification and then etches and forms a microlens, and a plurality of microlenses form a microlens array, and each microlens is bonded with a grating of diffraction grating, and the diffraction grating is a two-dimensional plane film structure as a whole, covers the outside of microlens array, and the surface is etched with uniform and regular grating. The utility model discloses only through the end of the plurality of optical fibers is equipped with the microlens, and each microlens is bonded with a grating of diffraction grating, can make each fiber core light beam can enter corresponding microlens and complete collimation and diffract, and then bring the change of light beam phase and then split, and the application structure is simple, does not need additional coupling spare, and the splitting efficiency is high, and the stability is strong, effectively improves production efficiency, and reduces production cost.

Description

Technical Field

[0001] This utility model relates to the field of optical fiber communication and optical device technology, specifically to an integrated fiber end splitter for multi-core optical fibers. Background Technology

[0002] Multi-core optical fibers, with their advantages of strong spatial multiplexing capability and large transmission capacity, have gradually become a research and application hotspot. In practical applications of multi-core optical fibers, it is necessary to split the beam emitted from the fiber ends according to a preset direction to achieve independent transmission of multi-channel signals or multi-directional detection. Existing multi-core optical fiber beam splitting schemes mostly adopt the method of external coupling devices, that is, by connecting a single-core fiber array to the multi-core fiber, or by using a combination of optical elements such as prisms and mirrors to achieve beam splitting. However, these schemes have the following shortcomings: First, the large number of external devices leads to a complex overall structure and large size of the beam splitter, making it difficult to meet the requirements of miniaturized applications; second, the multiple coupling links between multiple devices can easily introduce high insertion loss, reducing optical transmission efficiency; third, the stability of the coupling parts is poor, and under the influence of environmental factors such as temperature changes and vibration, beam deviation is prone to occur, resulting in beam splitting direction deviation and affecting the reliability of the device. Utility Model Content

[0003] This invention addresses the problems in the prior art by disclosing an integrated fiber-end beam splitter for multi-core optical fibers. This invention achieves beam splitting by simply attaching microlenses to the ends of multiple optical fibers and bonding each microlens to a diffraction grating. This allows the beam from each fiber core to enter the corresponding microlens for collimation and diffraction, resulting in a change in beam phase and thus beam splitting. This application has a simple structure, requires no additional coupling components, and offers high beam splitting efficiency and strong stability, effectively improving production efficiency and reducing production costs.

[0004] This utility model is achieved through the following technical solution: This invention first provides a multi-core optical fiber including a sheath and its internal sleeve. The multi-core optical fiber includes several parallel cores. One end of each core is first induced to modify and then etched to form a microlens. Multiple microlenses form a microlens array. Each microlens is bonded to a grating of a diffraction grating. The diffraction grating is a two-dimensional planar thin film structure covering the outside of the microlens array. The surface is etched with a uniform and regular grating.

[0005] As a further option, the multi-core fiber is a seven-core fiber with the following arrangement: one core in the center and the other six cores are distributed around the center at a 60° angle, with a spacing of 41.5μm between the cores and a core diameter of 8μm.

[0006] As a further option, fillers are provided between two adjacent fiber cores and between the fiber core and the sheath.

[0007] As a further option, the protrusion height of the microlens is 30 μm, and the radius of curvature of the lens spherical surface is 18.6 μm.

[0008] As a further embodiment, the diffraction grating includes a body and several gratings disposed above it. The body is disk-shaped and its outer diameter is the same as the inner diameter of the sheath. The several gratings are arranged in an array, and the array is the same as the array of microlenses.

[0009] As a further option, the grating uses a square lattice.

[0010] As a further embodiment, the grating includes several pillars arranged in a square array, with the distance between the centers of two adjacent pillars being 1000 nm.

[0011] As a further option, the pillars are square pillars, with both the length and width dimensions being 500 nm.

[0012] As a further option, the column is a cylinder with an outer diameter of 500 nm and a sidewall roughness of ≤15 nm.

[0013] As a further option, both the fiber core and the diffraction grating are made of silicon dioxide.

[0014] The features and beneficial effects of this utility model are as follows: (1) This utility model can enable the beam of each fiber core to enter the corresponding microlens to complete collimation and diffraction by simply providing microlenses at the ends of multiple optical fibers and bonding each microlens to a grating of a diffraction grating, thereby bringing about a change in the beam phase and thus splitting the beam. The structure of this application is simple, the beam splitting efficiency is high, the stability is strong, and the production efficiency is effectively improved and the production cost is reduced.

[0015] (2) The present invention sets the column of the grating as a cylindrical structure. Since the cylindrical structure is a symmetrical structure due to rotation, the shape remains unchanged after rotating at any angle, which can eliminate the influence of polarization state on beam splitting performance and solve the core problem of angle shift and loss fluctuation caused by polarization sensitivity of square column. At the same time, the rotational symmetry structure of the cylinder makes the light field distribution more uniform in all directions, which can avoid the light intensity fluctuation caused by X / Y axis scattering difference of square column.

[0016] (3) The fiber cores and the sheath of this utility model are filled with fillers, which makes the structure very stable and will not affect the optical path due to external vibration. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the integrated fiber end splitter for multi-core optical fibers described in an embodiment of the present invention; Figure 2 This is a schematic diagram of the microlens array described in an embodiment of the present invention; Figure 3 This is a schematic diagram of the diffraction grating described in an embodiment of the present invention; Figure 4 This is a grid structure in one embodiment of the present utility model; Figure 5 This is a grid structure in another embodiment of the present utility model.

[0019] Explanation of reference numerals in the attached figures: 1-Sheath; 2-Multi-core optical fiber; 21-Fiber core; 3-Microlens array; 31-Microlens; 4-Diffraction grating; 41-Body; 42-Grate; 421-Post. Detailed Implementation

[0020] To facilitate understanding of this utility model, a more comprehensive description of this utility model will be provided below, along with embodiments of this utility model, but this does not limit the scope of this utility model.

[0021] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0022] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0023] An integrated fiber end splitter for multi-core optical fibers, such as Figures 1 to 5 As shown, the fiber includes a sheath 1 and a multi-core optical fiber 2 inside it. The multi-core optical fiber 2 includes several parallel fiber cores 21. One end of each fiber core 21 is first induced to be modified and then etched to form a microlens 31. Multiple microlenses 31 form a microlens array 3. Each microlens 31 is bonded to a grating 42 of a diffraction grating 4.

[0024] In some embodiments, in order to meet the needs of high-capacity transmission scenarios, there are multiple multi-core optical fibers 2, which are arranged in an array.

[0025] In some embodiments, in order to meet the high-capacity transmission scenario, the multi-core optical fiber 2 is a seven-core optical fiber, and the optical fiber is arranged as follows: one fiber core 21 in the center, and the other 6 fiber cores 21 are distributed around the center at an angle of 60°, and the spacing between the fiber cores 21 is 41.5μm.

[0026] In some embodiments, the diameter of the fiber core 21 is 8 μm.

[0027] In some embodiments, a microlens 31 is formed by inducing modification and etching at the end of the fiber core 21 near the diffraction grating 4 using a femtosecond laser. Each fiber core 21 has a microlens 31 formed at its end through induction modification and etching, and multiple microlenses 31 form a microlens array 3. This structure ensures that each microlens 31 corresponds precisely to one fiber core 21, essentially acting as a dedicated collimation unit for each fiber core 21. After the light beam exits from the fiber core 21, it first enters the microlens array 3. The microlens 31 converts the diverging light beam into parallel light according to a preset focal length, ensuring that the outgoing light beams from all fiber cores 21 are parallel and oriented in the same direction, thus completing the beam collimation. At the same time, this structure directly etches the microlens 31 onto the fiber core 21, eliminating the need for additional external optical components and saving raw materials.

[0028] In some embodiments, the protrusion height of the microlens 31 is 30 μm, and the radius of curvature of the lens spherical surface is 18.6 μm.

[0029] The specific method for forming the microlens 31 is as follows: A femtosecond laser with a wavelength of 515 nm was used to modify the fiber core 21 in three layers, each 10 μm deep, along a direction perpendicular to the end face. After induced modification, the density of the modified region was higher than that of the unmodified region. Then, an etching solution was used to fabricate the microlens array 3. The etching solution used a 1:3 volume ratio of hydrofluoric acid and ammonium fluoride, with a concentration of 20%. Because the density of the modified region was higher than that of the unmodified region, the etching solution could quickly remove the unmodified area. Due to surface tension, a spherical surface was formed. Because of the three-layer modification, the spherical protrusion height was controlled to 30 μm, and the radius of curvature of the lens spherical surface was 18.6 μm, meeting the beam collimation parameters, thus completing the fabrication of the microlens array.

[0030] In some embodiments, both the fiber core 21 and the diffraction grating 4 are made of silicon dioxide, and the fact that they are made of the same material allows the fiber core 21 and the diffraction grating 4 to fit together tightly.

[0031] In some embodiments, a filler is provided between each fiber core 21. The filler is located between the fiber core 21 and the sheath 1, and its function is to fill the gaps and protect the fiber core 21 and the protective layer. The filler is generally a material with good elasticity and resistance to aging, such as vinyl ester resin or polyurethane. The type and quantity of filler are determined according to the different requirements of the multi-core optical fiber 2.

[0032] The sheath 1 is typically made of PVC, low-smoke halogen-free materials, etc., which have properties such as oxidation resistance, flame retardancy, and corrosion resistance. Depending on the application requirements, the sheath can also be made of materials such as steel strip, aluminum-plastic composite strip, and PE.

[0033] In some embodiments, the diffraction grating 4 includes a body 41 and a plurality of gratings 42 disposed above it. The body 41 is disk-shaped and its outer diameter is the same as the inner diameter of the sheath 1. The plurality of gratings 42 are arranged in an array, and the array is the same as the microlens array 3, so that each microlens 31 is bonded to a grating 42.

[0034] In some embodiments, the diffraction grating 4 is a two-dimensional planar thin film structure covering the outside of all microlens arrays 3. Its surface is etched with uniform and regular gratings 42. When the beam passes through the pillars 421 of the grating, the beam is diffracted and split at a preset angle according to the distribution of the grating pillars 421.

[0035] In some embodiments, the lattice of the grating 42 is a square lattice.

[0036] In some embodiments, the grating 42 includes a plurality of pillars 421, which are square pillars arranged in a square array. The distance between the centers of two adjacent pillars 421 is 1000 nm, and the length and width of each pillar 421 are 500 nm. Due to the difference in refractive index between silicon dioxide and air, light travels slower in the pillars 421 than in air, thus causing a change in the phase of the light and achieving beam splitting. However, the sharp edges of the square pillar units can cause polarization sensitivity, leading to beam deviation from the receiving end and crosstalk between beams.

[0037] To address the polarization sensitivity issue, the outer diameter of the body 41 and the inner diameter of the sheath 1 are both 250 μm, effectively preventing beam loss.

[0038] In another embodiment, the pillar 421 is a cylinder with a center distance of 1000 nm between two adjacent cylinders; the outer diameter of the cylinder is 500 nm, and the roughness of the cylinder sidewall is ≤15 nm. The smooth curved surface can reduce scattering loss.

[0039] Because of its rotational symmetry, the cylindrical unit retains its shape after rotation at any angle, which can eliminate the influence of polarization state on beam splitting performance. This solves the core problem of angle shift and loss fluctuation caused by the polarization sensitivity of square pillars. At the same time, the rotational symmetry of the cylinder makes the light field distribution more uniform in all directions, which can avoid the light intensity fluctuation caused by the X / Y axis scattering difference of square pillars.

[0040] The working principle of an integrated fiber end splitter for multi-core optical fibers is as follows: When the light beam enters the multi-core fiber 2 from the light source, the light beam from each fiber core 21 can enter the corresponding microlens 31 to complete collimation. Then, the light beam is diffracted by the pillar 421 of the corresponding grating 42. Since the refractive index of silicon dioxide (the material of grating 42) is different from that of air, the light beam travels slower in the pillar than in air, which can bring about a change in the phase of the light beam, thereby achieving the purpose of beam splitting.

[0041] The proposed solution has a simple structure, high beam splitting efficiency, and strong stability, which effectively improves production efficiency and reduces production costs.

[0042] It should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. An integrated fiber end splitter for multi-core optical fibers, characterized in that: The fiber includes a sheath and a multi-core optical fiber with internal sheathing. The multi-core optical fiber includes several parallel fiber cores. One end of each fiber core is first induced to modify and then etched to form a microlens. Multiple microlenses form a microlens array. Each microlens is bonded to a grating of a diffraction grating. The diffraction grating is a two-dimensional planar thin film structure that covers the outside of the microlens array. The surface is etched with uniform and regular gratings.

2. The integrated fiber end splitter for multi-core optical fibers according to claim 1, characterized in that: The multi-core fiber is a seven-core fiber with the following arrangement: one core in the center and the other six cores are distributed around the center at a 60° angle, with a spacing of 41.5μm between the cores and a core diameter of 8μm.

3. The integrated fiber end splitter for multi-core optical fibers according to claim 1, characterized in that: Filler is provided between two adjacent fiber cores and between the fiber core and the sheath.

4. The integrated fiber end splitter for multi-core optical fibers according to claim 1, characterized in that: The protrusion height of the microlens is 30 μm, and the radius of curvature of the lens spherical surface is 18.6 μm.

5. An integrated fiber end splitter for multi-core optical fibers according to claim 1, characterized in that: The diffraction grating includes a body and several gratings disposed above it. The body is disk-shaped and its outer diameter is the same as the inner diameter of the sheath. The several gratings are arranged in an array, and the array is the same as the array of microlenses.

6. An integrated fiber end splitter for multi-core optical fibers according to claim 1, characterized in that: The grating uses a square lattice.

7. An integrated fiber end splitter for multi-core optical fibers according to claim 1, characterized in that: The grating consists of several pillars arranged in a square array, with a distance of 1000 nm between the centers of two adjacent pillars.

8. An integrated fiber end splitter for multi-core optical fibers according to claim 7, characterized in that: The pillars are square pillars, with each pillar measuring 500 nm in length and width.

9. An integrated fiber end splitter for multi-core optical fibers according to claim 7, characterized in that: The column is a cylinder with an outer diameter of 500 nm and a sidewall roughness of ≤15 nm.

10. An integrated fiber end splitter for multi-core optical fibers according to claim 1, characterized in that: Both the fiber core and the diffraction grating are made of silicon dioxide.

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