Optical splitter with built-in fiber bragg grating and preparation method

Abstract

The invention provides an optical splitter with a built-in fiber bragg grating and a preparation method, and belongs to the technical field of optical splitter packaging. Comprising a hollow box body; the optical splitter chip is arranged at the non-end position of the box body; the output optical fiber array is arranged at one end of the box body, one end of the output optical fiber array is in optical path connection with the output end of the optical splitter chip, and the other end of the output optical fiber array is in one-to-one corresponding optical path connection with the plurality of terminal ONUs; one end of the single-fiber input unit extends out of the box body and is connected with the trunk optical path, and the other end of the single-fiber input unit is connected with the input end optical path of the optical splitter chip; a grating is further packaged at one end, close to the optical splitter chip, of the single-fiber input unit. According to the optical splitter, the grating is integrated into the single-fiber input unit, so that the high integration level of the optical splitter is realized, a plurality of single-fiber input units can be ground at the same time, and the grinding consistency and the processing efficiency are improved.

Description

Technical Field

[0001] The invention relates to the technical field of optical splitter packaging, and in particular to an optical splitter with built-in optical fiber grating and a preparation method thereof. Background Art

[0002] ODN, Optical Distribution Network, commonly known as optical splitter, distributes the optical path signal of a trunk line to multiple terminal ONUs, Optical Network Units. It mainly realizes the task of optical signal power distribution. ODN is a pure passive optical distribution device composed of passive optical components.

[0003] There are multiple optical signals of different wavelengths on the trunk line for communication with the optical network. In order to monitor the abnormality on the optical path, optical couplers, fiber Bragg gratings and optical splitters are usually configured on the trunk line. The optical couplers are connected to the optical time domain reflectometer and the trunk optical path respectively. The normal transmission signal and the monitoring optical signal emitted by the optical time domain reflectometer are both transmitted into the trunk line; the fiber Bragg grating is also connected to the trunk optical path to reflect the detection optical signal back to the optical time domain reflectometer. The normal transmission signal passes smoothly from the fiber Bragg grating and enters the optical splitter. According to the status of the monitoring optical signal received by the optical time domain reflectometer, it reflects whether the optical path is abnormal. However, in this structure, the fiber Bragg grating and the optical splitter are independently packaged, and the packaging of the fiber Bragg grating requires special steel pipe glue sealing, and the fusion point is increased, which has an adverse effect on the transmission power, beam quality and loss.

[0004] Therefore, an optical splitter with built-in fiber Bragg grating and a preparation method are proposed to integrate the fiber Bragg grating as a whole with the optical splitter, simplify the packaging process and the number of overall fiber fusion points, which is very necessary for reducing transmission loss and improving beam quality. Summary of the invention

[0005] In view of this, the present invention proposes an optical splitter with built-in fiber gratings and a preparation method that can pre-position a single fiber, simultaneously grind, polish and cut multiple single fiber input units, and improve preparation efficiency and consistency.

[0006] In one aspect, the present invention provides an optical splitter with a built-in fiber grating, comprising:

[0007] Hollow box;

[0008] An optical splitter chip is arranged at a non-end position of the box;

[0009] An output optical fiber array is arranged at one end of the box, one end of the output optical fiber array is optically connected to the output end of the optical splitter chip, and the other end of the output optical fiber array is optically connected to a plurality of terminal ONUs one by one;

[0010] One end of the single-fiber input unit extends out of the box and is connected to the trunk optical path, and the other end is connected to the input optical path of the optical splitter chip; a grating is also encapsulated at one end of the single-fiber input unit close to the optical splitter chip.

[0011] On the basis of the above technical scheme, preferably, the single-fiber input unit comprises a single optical fiber, a first cover plate, a substrate, a second cover plate and at least one pair of dummy fibers; the single optical fiber and the at least one pair of dummy fibers are both provided with exposed sections at one end close to the optical splitter chip, and a grating is provided on the exposed section of the single optical fiber; the single optical fiber and the at least one pair of dummy fibers are surrounded by a coating layer at one end away from the optical splitter chip; the substrate is arranged in a box body, and different end faces of the substrate are respectively abutted against the coating layer and exposed section of the single optical fiber and the at least one pair of dummy fibers; the first cover plate is respectively abutted against the end face of the substrate close to the optical splitter chip, the exposed section of the single optical fiber and the exposed section of the at least one pair of dummy fibers, and the second cover plate is respectively abutted against the end face of the substrate away from the optical splitter chip, the first cover plate, the optical fiber coating layer and the coating layer of at least one pair of dummy fibers.

[0012] Preferably, the substrate is provided with a first end face and a second end face; the first end face is provided with at least one group of first embedded grooves, the exposed section of the single optical fiber extends into the middle part of the at least one group of first embedded grooves and extends in the direction where the optical splitter chip is located, the exposed sections of at least one pair of dummy fibers extend into non-middle positions of the at least one group of first embedded grooves respectively, and the axial length of the exposed sections of the at least one pair of dummy fibers is adapted to the axial length of the at least one group of first embedded grooves;

[0013] At least one group of stepped portions is arranged on the second end face, one end of at least one group of stepped portions is fixedly connected to the second end face, and the other end extends outward in a direction close to the first end face, and a plurality of second embedding grooves are arranged on at least one group of stepped portions, the coating layer of a single optical fiber is embedded in the second embedding groove at a non-edge position, the coating layer of at least one pair of dummy fibers is embedded in two second embedding grooves adjacent to the coating layer of the optical fiber, and the surface of the coating layer of the single optical fiber exceeding the second embedding groove is respectively abutted against the surface of the coating layer of at least one pair of dummy fibers exceeding the second embedding groove.

[0014] Further preferably, the extension length of at least one group of first embedded grooves along the axial direction of the single optical fiber is equal to the extension length of the first end face along the axial direction of the single optical fiber; the extension length of at least one group of step portions along the axial direction of the single optical fiber does not exceed the extension length of the second end face along the axial direction of the single optical fiber; the radial dimension of at least one group of first embedded grooves is adapted to the diameter of the exposed section of the single optical fiber or the exposed section of at least one pair of dummy fibers.

[0015] Further preferably, the first end face and the second end face are arranged in parallel; and a wedge-shaped transition face is arranged between the first end face and the second end face.

[0016] More preferably, the size of the first cover plate is adapted to the contour of the first end face, and an adhesive layer is provided on the surface of the exposed section of the single optical fiber or at least a pair of dummy fibers, and between the surface of the exposed section of the single optical fiber or at least a pair of dummy fibers and the adjacent surface of the first cover plate.

[0017] Still further preferably, the contour of the second cover plate is adapted to the second end face and the wedge-shaped transition surface, a avoidance portion is provided on the side of the second cover plate close to the second end face, and the avoidance portion is adapted to the contours of at least one group of step portions, the coating layer of a single optical fiber and at least one pair of dummy fiber coating layers; the second cover plate is respectively abutted against the end face of the first cover plate away from the optical splitter chip, the wedge-shaped transition surface, the second end face and the surface of the step portion; the surface of the optical fiber coating layer or at least one pair of dummy fiber coating layers, and the surface of the second cover plate close to the wedge-shaped transition surface, the second end face, at least one group of step portions and the first cover plate are all provided with an adhesive layer.

[0018] Further preferably, the contour shape of at least one group of first embedding grooves is V-shaped or rounded rectangular; and the contour shape of at least one group of second embedding grooves on the stepped portions is V-shaped or rounded rectangular.

[0019] In another aspect, the present invention provides a method for preparing an optical splitter with a built-in fiber grating, comprising the following steps:

[0020] An optical splitter equipped with the above-mentioned built-in fiber Bragg grating;

[0021] The single-fiber input unit comprises a plurality of single optical fibers, a substrate, a first cover plate, a second cover plate and at least one pair of dummy fibers, wherein the single optical fiber and the pair of dummy fibers form a component; a plurality of groups of first embedding grooves are arranged on the first end surface of the substrate, and the number of each group of first embedding grooves is three, and the exposed section of the single optical fiber is embedded in the middle position of each group of first embedding grooves, and the exposed section of a pair of dummy fibers is embedded in the non-middle position of each group of first embedding grooves; gratings are arranged on the exposed sections of the plurality of single optical fibers;

[0022] The second end surface of the substrate is provided with a plurality of groups of stepped portions, each of which is provided with three second embedding grooves, the coating layers of the dummy fibers arranged in pairs are embedded in two second embedding grooves at non-middle positions of the plurality of groups of stepped portions, the coating layers of the plurality of single optical fibers are embedded in the second embedding grooves at non-edge positions of each group of stepped portions, and before the single optical fibers and the dummy fibers are embedded in the first embedding grooves and the second embedding grooves, the surfaces are coated with an adhesive layer for curing;

[0023] A first cover plate is covered on the first end surface of the substrate, the first cover plate abuts against the exposed section of the optical fiber, and an adhesive layer for curing is also provided between the first cover plate and the exposed section of the single optical fiber;

[0024] After placing the first cover plate, further placing the second cover plate, and providing a curing adhesive layer on the second cover plate near the wedge-shaped transition surface, the second end surface, at least one set of step portions and the surface of the first cover plate;

[0025] After the adhesive layer is cured, the portions of the plurality of single optical fibers extending out of the first embedding groove are respectively ground and polished;

[0026] The first cover plate, the second cover plate and the base plate are cut respectively to form a plurality of single-fiber input units with built-in fiber gratings. The single-fiber input units, the optical splitter chip and the output optical fiber array are sequentially placed in the box for optical path connection to obtain an optical splitter.

[0027] Preferably, an input plug is provided at one end of the box, and the coating layer of the single optical fiber is inserted into the input plug and extends out of the box; an output plug is provided at the other end of the box, and the output optical fiber array is inserted into the output plug and extends out of the box.

[0028] The optical splitter with built-in fiber grating and the preparation method provided by the present invention have the following beneficial effects compared with the prior art:

[0029] (1) In order to better position the single optical fiber, the single-fiber input unit of the present invention is equipped with a set of first embedding grooves, stepped portions, second embedding grooves and a pair of dummy fibers, so as to better pre-position and combine and fix the placement of the single optical fiber, thereby reducing the difficulty of positioning and packaging the single optical fiber;

[0030] (2) In order to improve the overall manufacturing consistency of multiple single-fiber input units, multiple groups of single optical fibers and a pair of dummy fibers are configured on a larger scale. The components are ground and polished together before cutting, which greatly improves the production efficiency of the single-fiber input units. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 A structural stereogram of an optical splitter with a built-in optical fiber Bragg grating and a method for making the optical splitter according to the present invention;

[0033] Figure 2 A three-dimensional diagram of a single-fiber input unit of an optical splitter with a built-in fiber Bragg grating and a preparation method of the present invention;

[0034] Figure 3 A three-dimensional diagram of an exploded state of a single-fiber input unit of an optical splitter with a built-in fiber grating and a preparation method of the present invention;

[0035] Figure 4A schematic diagram of an optical splitter with built-in fiber Bragg grating and a preparation method of the present invention, wherein a plurality of groups of first embedded grooves and second embedded grooves are arranged on an uncut substrate;

[0036] Figure 5 It is a schematic diagram of setting multiple sets of avoidance parts on an uncut second cover plate according to an optical splitter with built-in fiber grating and a preparation method of the present invention;

[0037] Figure 6 The present invention is a schematic diagram of cutting a first cover plate, a second cover plate and a base plate according to an optical splitter with built-in fiber grating and a preparation method thereof.

[0038] Reference numerals: 1, single fiber input unit; 2, optical splitter chip; 3, output fiber array; 4, box; 5, input plug; 6, output plug;

[0039] 101, single optical fiber; 102, grating; 103, first cover plate; 104, substrate; 105, second cover plate; 106, dummy fiber; 200, first end face; 300, second end face; 400, first embedded groove; 500, step portion; 600, second embedded groove; 700, wedge-shaped transition surface. DETAILED DESCRIPTION

[0040] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] In the existing optical splitter structure with grating to reflect the detection light, the fiber Bragg grating and the optical splitter are packaged independently, and the packaging of the fiber Bragg grating requires special steel pipe glue sealing, and it will increase the welding points, which has an adverse effect on the transmission power, beam quality and loss. In view of this, if Figure 1 Combination Figure 2 and Figure 3 As shown, on the one hand, the present invention provides an optical splitter with built-in fiber grating, comprising:

[0042] A hollow box 4;

[0043] The optical splitter chip 2 is arranged at a non-end position of the box body 4;

[0044] The output fiber array 3 is arranged at one end of the box 4, one end of the output fiber array 3 is optically connected to the output end of the optical splitter chip 2, and the other end of the output fiber array 3 is optically connected to a plurality of terminal ONUs one by one;

[0045] One end of the single fiber input unit 1 extends out of the box 4 and is connected to the main optical path, and the other end is connected to the input optical path of the optical splitter chip 2; a grating is also encapsulated at one end of the single fiber input unit 1 close to the optical splitter chip 2.

[0046] From the above content, it can be seen that by encapsulating the grating inside the box, the fiber fusion points and assembly difficulty can be reduced, the beam quality can be improved, and the transmission loss can be reduced.

[0047] like Figure 1 As shown, an input plug 5 is provided at one end of the box 4, and the coating layer of the single optical fiber 101 is inserted into the input plug 5 and extends out of the box 4; an output plug 6 is provided at the other end of the box 4, and the output optical fiber array 3 is inserted into the output plug 6 and extends out of the box 4. The input plug 5 cooperates with the output plug 6 to improve the sealing of the box, and prevents external light from entering the box and interfering with the signal light transmission.

[0048] like Figure 2 and Figure 3 As shown, the figure shows the specific structure of the single fiber input unit 1. The single fiber input unit 1 includes a single optical fiber 101, a first cover plate 103, a substrate 104, a second cover plate 105 and at least one pair of dummy fibers 106; the single optical fiber 101 and the at least one pair of dummy fibers 106 are both provided with exposed sections at one end close to the optical splitter chip 2, and a grating 102 is provided on the exposed section of the single optical fiber 101; the single optical fiber 101 and the at least one pair of dummy fibers 106 are surrounded by a coating layer at one end away from the optical splitter chip 2; the substrate 104 is provided in the box 4, Different end faces of the substrate 104 are respectively against the coating layer and exposed section of the single optical fiber 101 and at least one pair of dummy fibers 106; the first cover plate 103 is respectively against the end face of the substrate 104 close to the optical splitter chip 2, the exposed section of the single optical fiber 101 and the exposed section surface of at least one pair of dummy fibers 106, and the second cover plate 105 is respectively against the end face of the substrate 104 away from the optical splitter chip 2, the first cover plate 103, the optical fiber coating layer and the coating layer of at least one pair of dummy fibers 106. The dummy fibers 106 can play the role of limiting and pre-positioning, and improve the position stability of the single optical fiber 101 when packaging.

[0049] Due to the existence of the exposed section and the coating layer, the outer diameters of the single optical fiber and the dummy fiber 106 at different positions are different, so the exposed section and the coating layer are supported and limited on the substrate. The substrate 104 is provided with a first end face 200 and a second end face 300; the first end face 200 is provided with at least one group of first embedded grooves 400, the exposed section of the single optical fiber 101 extends into the middle part of at least one group of first embedded grooves 400 and extends in the direction of the optical splitter chip 2, the exposed sections of at least one pair of dummy fibers 106 extend into non-middle positions of at least one group of first embedded grooves 400, and the axial length of the exposed section of at least one pair of dummy fibers 106 is adapted to the axial length of at least one group of first embedded grooves 400; the first embedded groove on the first end face 200 is used to limit the exposed sections of the single optical fiber and the dummy fiber.

[0050] At least one set of stepped portions 500 is provided on the second end face 300, one end of at least one set of stepped portions 500 is fixedly connected to the second end face 300, and the other end extends outward in a direction close to the first end face 200. At least one set of stepped portions 500 is provided with a plurality of second embedding grooves 600, the coating layer of the single optical fiber 101 is embedded in the second embedding groove 600 at a non-edge position, the coating layer of at least one pair of dummy fibers 106 is embedded in two adjacent second embedding grooves 600 of the coating layer of the optical fiber, and the surface of the coating layer of the single optical fiber 101 that exceeds the second embedding groove 600 is respectively abutted against the surface of the coating layer of at least one pair of dummy fibers 106 that exceeds the second embedding groove 600. The first stepped portion 500 cooperates with the second embedding groove to limit the coating layers of the single optical fiber and the dummy fiber respectively.

[0051] The extension length of at least one group of first embedded grooves 400 along the axial direction of the single optical fiber 101 is equal to the extension length of the first end face 200 along the axial direction of the single optical fiber 101; the extension length of at least one group of step portions 500 along the axial direction of the single optical fiber 101 does not exceed the extension length of the second end face 300 along the axial direction of the single optical fiber 101; the radial dimension of at least one group of first embedded grooves 400 is adapted to the diameter of the exposed section of the single optical fiber 101 or the exposed section of at least one pair of dummy fibers 106. The size of the first cover plate 103 is adapted to the contour of the first end face 200, and an adhesive layer is provided on the surface of the exposed section of the single optical fiber 101 or the exposed section of at least one pair of dummy fibers 106, and between the surface of the exposed section of the single optical fiber 101 or the exposed section of at least one pair of dummy fibers 106 and the adjacent surface of the first cover plate 103.

[0052] The length of the exposed section of the single optical fiber 101 exceeds the length of the first embedding groove 400, but the length of the exposed section of the dummy fiber does not exceed the length of the first embedding groove 400, which will not have an adverse effect on subsequent grinding and other processes.

[0053] In this solution, the first end face 200 and the second end face 300 are arranged in parallel; a wedge-shaped transition surface 700 is arranged between the first end face 200 and the second end face 300. The wedge-shaped transition surface 700 combines the first cover plate 103 and the second end face to provide a basis for pre-positioning the second cover plate 105.

[0054] The profile of the second cover plate 105 is adapted to the second end face 300 and the wedge-shaped transition surface 700. A relief portion is provided on one side of the second cover plate 105 close to the second end face 300. The relief portion is adapted to the profiles of at least one group of stepped portions 500, the coating layer of the single optical fiber 101, and the coating layer of at least one pair of dummy fibers 106. The second cover plate 105 is respectively abutted against the end face of the first cover plate 103 away from the optical splitter chip 2, the wedge-shaped transition surface 700, the second end face 300, and the surface of the stepped portion 500. The surface of the optical fiber coating layer or the coating layer of at least one pair of dummy fibers 106, as well as the surface of the second cover plate 105 close to the wedge-shaped transition surface 700, the second end face 300, the at least one group of stepped portions 500, and the first cover plate 103 are all provided with an adhesive layer.

[0055] The contour shape of at least one group of first embedding grooves 400 is V-shaped or rounded rectangular; the contour shape of at least one group of second embedding grooves 600 on the stepped portion 500 is V-shaped or rounded rectangular. The shapes of the first embedding grooves 400 and the second embedding grooves 600 can provide line contact support or surface contact support for the surface of the single optical fiber and the dummy fiber, thereby improving the position stability after placement. The material used for the bonding layer in this solution is UV curing glue.

[0056] In addition, if Figure 4 , Figure 5 and Figure 6 As shown, the present invention provides a method for preparing an optical splitter with a built-in fiber grating, comprising the following steps:

[0057] S1: an optical splitter equipped with the above-mentioned built-in fiber Bragg grating;

[0058] S2: The single-fiber input unit 1 comprises a plurality of single optical fibers 101, a substrate 104, a first cover plate 103, a second cover plate 105 and at least one pair of dummy fibers 106, wherein the single optical fiber 101 and the pair of dummy fibers 106 form a component; a plurality of groups of first embedding grooves 400 are arranged on the first end surface 200 of the substrate 104, and the number of each group of first embedding grooves 400 is three, and the exposed section of the single optical fiber 101 is embedded in the middle position of each group of first embedding grooves 400, and the exposed section of a pair of dummy fibers 106 is embedded in the non-middle position of each group of first embedding grooves 400; gratings are arranged on the exposed sections of the plurality of single optical fibers 101;

[0059] S3: The second end surface 300 of the substrate 104 is provided with a plurality of groups of stepped portions 500, each of which is provided with three second embedding grooves 600, the coating layers of the dummy fibers 106 arranged in pairs are embedded in two second embedding grooves 600 at non-middle positions of the plurality of groups of stepped portions 500, the coating layers of the plurality of single optical fibers 101 are embedded in the second embedding grooves 600 at non-edge positions of each group of stepped portions 500, and before the single optical fibers 101 and the dummy fibers 106 are embedded in the first embedding grooves 400 and the second embedding grooves 600, the surfaces are coated with an adhesive layer for curing;

[0060] S4: Covering the first cover plate 103 on the first end surface 200 of the substrate 104, the first cover plate 103 and the exposed section of the optical fiber are abutted, and an adhesive layer for curing is also provided between the first cover plate 103 and the exposed section of the single optical fiber 101;

[0061] S5: After placing the first cover plate 103, further placing the second cover plate 105, the second cover plate 105 near the wedge-shaped transition surface 700, the second end surface 300, at least one set of step portions 500 and the surface of the first cover plate 103 are all provided with an adhesive layer for curing;

[0062] S6: After the UV adhesive of the bonding layer is cured, the portions of the single optical fibers 101 extending out of the first embedding groove 400 are ground and polished respectively;

[0063] S7: Cut the first cover plate 103, the second cover plate 105 and the base plate 104 respectively to form a plurality of single-fiber input units 1 with built-in optical fiber gratings, and sequentially place the single-fiber input units 1, the optical splitter chip 2 and the output optical fiber array 3 into the box 4 for optical path connection to obtain an optical splitter.

[0064] Figure 4-Figure 6 The schematic diagram shows that three groups of single-fiber input units 1 are integrally formed, but the number of single-fiber input units 1 shown in the diagram can be adjusted as needed, and the number of single-fiber input units 1 processed simultaneously in the diagram is not regarded as a limitation on the solution.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An optical splitter with built-in fiber Bragg grating, characterized in that: include A hollow box (4); An optical splitter chip (2) is arranged at a non-end position of the box (4); An output optical fiber array (3) is arranged at one end of the box (4), one end of the output optical fiber array (3) is optically connected to the output end of the optical splitter chip (2), and the other end of the output optical fiber array (3) is optically connected to a plurality of terminal ONUs in a one-to-one correspondence; One end of the single-fiber input unit (1) extends out of the box (4) and is connected to the main optical path, and the other end is connected to the input optical path of the optical splitter chip (2); a grating is also encapsulated at one end of the single-fiber input unit (1) close to the optical splitter chip (2).

2. The optical splitter with built-in fiber Bragg grating according to claim 1, characterized in that: The single-fiber input unit (1) comprises a single optical fiber (101), a first cover plate (103), a substrate (104), a second cover plate (105), and at least one pair of dummy fibers (106); the ends of the single optical fiber (101) and the at least one pair of dummy fibers (106) close to the optical splitter chip (2) are both provided with exposed sections, and a grating (102) is provided on the exposed section of the single optical fiber (101); the ends of the single optical fiber (101) and the at least one pair of dummy fibers (106) away from the optical splitter chip (2) are surrounded by a coating layer; the substrate (104) is arranged in a box. (4), different end faces of the substrate (104) respectively abut against the coating layer and exposed section of the single optical fiber (101) and at least one pair of dummy fibers (106); the first cover plate (103) respectively abuts against the end face of the substrate (104) close to the optical splitter chip (2), the exposed section of the single optical fiber (101) and the exposed section surface of at least one pair of dummy fibers (106); the second cover plate (105) respectively abuts against the end face of the substrate (104) far from the optical splitter chip (2), the first cover plate (103), the optical fiber coating layer and the coating layer of at least one pair of dummy fibers (106).

3. The optical splitter with built-in fiber Bragg grating according to claim 2, characterized in that: The substrate (104) is provided with a first end face (200) and a second end face (300); the first end face (200) is provided with at least one group of first embedded grooves (400); the exposed section of the single optical fiber (101) extends into the middle part of the at least one group of first embedded grooves (400) and extends in the direction of the optical splitter chip (2); the exposed sections of at least one pair of dummy fibers (106) extend into non-middle positions of the at least one group of first embedded grooves (400), and the axial length of the exposed sections of the at least one pair of dummy fibers (106) is adapted to the axial length of the at least one group of first embedded grooves (400); At least one group of stepped portions (500) is provided on the second end surface (300), one end of the at least one group of stepped portions (500) is fixedly connected to the second end surface (300), and the other end extends outward in a direction close to the first end surface (200), and a plurality of second embedded grooves (600) are provided on the at least one group of stepped portions (500), the coating layer of the single optical fiber (101) is embedded in the second embedded groove (600) at a non-edge position, the coating layer of at least one pair of dummy fibers (106) is embedded in two second embedded grooves (600) adjacent to the coating layer of the optical fiber, and the surface of the coating layer of the single optical fiber (101) that exceeds the second embedded groove (600) is respectively abutted against the surface of the coating layer of the at least one pair of dummy fibers (106) that exceeds the second embedded groove (600).

4. The optical splitter with built-in fiber Bragg grating according to claim 3, characterized in that: The extension length of at least one group of first embedded grooves (400) along the axial direction of the single optical fiber (101) is equal to the extension length of the first end face (200) along the axial direction of the single optical fiber (101); the extension length of at least one group of step portions (500) along the axial direction of the single optical fiber (101) does not exceed the extension length of the second end face (300) along the axial direction of the single optical fiber (101); and the radial dimension of at least one group of first embedded grooves (400) is adapted to the diameter of an exposed section of the single optical fiber (101) or an exposed section of at least one pair of dummy fibers (106).

5. The optical splitter with built-in fiber Bragg grating according to claim 3, characterized in that: The first end surface (200) and the second end surface (300) are arranged in parallel; a wedge-shaped transition surface (700) is arranged between the first end surface (200) and the second end surface (300).

6. The optical splitter with built-in fiber Bragg grating according to claim 5, characterized in that: The size of the first cover plate (103) is adapted to the contour of the first end surface (200), and an adhesive layer is provided between the surface of the exposed section of the single optical fiber (101) or at least a pair of dummy fibers (106), and between the surface of the exposed section of the single optical fiber (101) or at least a pair of dummy fibers (106) and the adjacent surface of the first cover plate (103).

7. The optical splitter with built-in fiber Bragg grating according to claim 6, characterized in that: The profile of the second cover plate (105) is adapted to the second end face (300) and the wedge-shaped transition surface (700); a relief portion is provided on one side of the second cover plate (105) close to the second end face (300); the relief portion is adapted to the profiles of at least one group of stepped portions (500), the coating layer of the single optical fiber (101), and the coating layer of at least one pair of dummy fibers (106); the second cover plate (105) is respectively abutted against the end face of the first cover plate (103) away from the optical splitter chip (2), the wedge-shaped transition surface (700), the second end face (300), and the surface of the stepped portion (500); and an adhesive layer is provided on the surface of the optical fiber coating layer or the coating layer of at least one pair of dummy fibers (106), and on the surface of the second cover plate (105) close to the wedge-shaped transition surface (700), the second end face (300), the at least one group of stepped portions (500), and the first cover plate (103).

8. The optical splitter with built-in fiber Bragg grating according to claim 3, characterized in that: The contour shape of at least one group of first embedding grooves (400) is V-shaped or a rounded rectangle; and the contour shape of at least one group of second embedding grooves (600) on the stepped portions (500) is V-shaped or a rounded rectangle.

9. A method for preparing an optical splitter with a built-in fiber Bragg grating, characterized in that: The steps include: An optical splitter with a built-in fiber Bragg grating as described in any one of claims 5 to 8; The single-fiber input unit (1) comprises a plurality of single optical fibers (101), a substrate (104), a first cover plate (103), a second cover plate (105) and at least one pair of dummy fibers (106), wherein the single optical fiber (101) and the pair of dummy fibers (106) form a component; a plurality of groups of first embedding grooves (400) are arranged on the first end surface (200) of the substrate (104), the number of each group of first embedding grooves (400) being three, the exposed section of the single optical fiber (101) is embedded in the middle position of each group of first embedding grooves (400), and the exposed sections of a pair of dummy fibers (106) are embedded in the non-middle position of each group of first embedding grooves (400); gratings are arranged on the exposed sections of the plurality of single optical fibers (101); The second end surface (300) of the substrate (104) is provided with a plurality of groups of stepped portions (500), each of the stepped portions (500) is provided with three second embedding grooves (600), the coating layers of the dummy fibers (106) arranged in pairs are embedded in two second embedding grooves (600) at non-middle positions of the plurality of groups of stepped portions (500), the coating layers of the plurality of single optical fibers (101) are embedded in the second embedding grooves (600) at non-edge positions of each group of stepped portions (500), and before the single optical fibers (101) and the dummy fibers (106) are embedded in the first embedding grooves (400) and the second embedding grooves (600), the surfaces are coated with an adhesive layer for curing; A first cover plate (103) is covered on the first end surface (200) of the substrate (104), the first cover plate (103) abuts against the exposed section of the optical fiber, and an adhesive layer for curing is also provided between the first cover plate (103) and the exposed section of the single optical fiber (101); After placing the first cover plate (103), further placing the second cover plate (105), and providing a curing adhesive layer on the second cover plate (105) near the wedge-shaped transition surface (700), the second end surface (300), at least one group of step portions (500), and the surface of the first cover plate (103); After the adhesive layer is cured, the portions of the plurality of single optical fibers (101) extending out of the first embedding groove (400) are respectively ground and polished; The first cover plate (103), the second cover plate (105) and the base plate (104) are cut respectively to form a plurality of single-fiber input units (1) with built-in optical fiber gratings. The single-fiber input units (1), the optical splitter chip (2) and the output optical fiber array (3) are sequentially placed in a box (4) for optical path connection, thereby obtaining an optical splitter.

10. The method for preparing an optical splitter with built-in fiber Bragg grating according to claim 9, characterized in that: An input plug (5) is provided at one end of the box (4), and a coating layer of a single optical fiber (101) is inserted into the input plug (5) and extends out of the box (4); an output plug (6) is provided at the other end of the box (4), and an output optical fiber array (3) is inserted into the output plug (6) and extends out of the box (4).

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