Optical splitting structure and manufacturing method therefor

Abstract

An optical splitting structure and a manufacturing method therefor. The optical splitting structure comprises a main straight waveguide (20) and a plurality of branch waveguides (21, 22, 23, 24) branching off from the main straight waveguide (20), wherein there are branching angles (A) between the branch waveguides (21, 22, 23, 24) and the main straight waveguide (20); there are branching offset distances (G) between bifurcation positions of the branch waveguides (21, 22, 23, 24) and the main straight waveguide (20), and an optical axis (211) of the main straight waveguide (20); and the branching angles (A) and the branching offset distances (G) are set on the basis of optical splitting ratios (X) on the branch waveguides (21, 22, 23, 24), such that the branch waveguides (21, 22, 23, 24) have the corresponding optical splitting ratios (X). Since the main straight waveguide (20) does not change the angle of an optical path at a branching position and also does not bend, input light of the next-level branch waveguides (21, 22, 23, 24) on the main straight waveguide (20) still exhibits a quasi-symmetric single-mode optical field distribution. The optical splitting ratios (Y) of the branch waveguides (21, 22, 23, 24) are independent of each other, and can therefore be independently optimized and controlled, making it very easy to realize the optical characteristic of nearly 0 dB insertion loss consistency.

Description

A light splitting structure and its manufacturing method

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority from the following patent applications:

[0003] (1) A Chinese patent application entitled “A spectroscopic structure and its manufacturing method”, filed with the Chinese Patent Office on December 6, 2023, with application number 202311674733.9; Technical Field

[0004] The present invention relates to the technical field of optical splitters, and in particular to a optical splitter structure and a manufacturing method thereof. Background Art

[0005] In a passive optical network, the Optical Distribution Network (ODN) is the optical transmission channel from the optical line terminal in the communication center's computer room to the user-side optical network unit. Optical branching devices are the core components of the point-to-multipoint ODN architecture. The optical branching devices used in the new generation of fiber-to-the-x (FTTx) are primarily optical splitters, which are used to achieve 1:N optical power distribution. In traditional ODN networks, 1:N optical splitters typically use a uniform distribution structure, with the most common equal distribution ratios being 1:4, 1:8, and 1:16. With the development and evolution of ODN networks, traditional ODN networks face many adjustments, one of which is network flexibility and scalability. Therefore, a pre-connected ODN network was proposed, which uses a non-uniform optical splitter structure, with the most common 1:5 and 1:9 non-uniform structures.

[0006] Conventional non-uniform splitting structures, such as a 1:5 splitting ratio, typically split the input light into two branches with an 85% and 15% split ratio. The 15% branch is then split into two 7.5% branches using an equal splitting structure. These two 7.5% branches are then further split into four 3.75% branches using an equal splitting structure. With this design, the insertion loss consistency of the four equally split light paths is typically poor. Furthermore, as the number of branches increases, the insertion loss consistency increases. Furthermore, to achieve ideal insertion loss consistency, the optical waveguide chip design process requires individual optimization of each branch level. If the number of light paths increases or the spacing between branches changes, the optical path layout will change, and the asymmetric distribution of the light field in each branch will also change. This requires re-optimization of the entire optical path structure, making the design optimization of this structure complex, labor-intensive, and time-consuming.

[0007] In view of this, overcoming the defects of the prior art is an urgent problem to be solved in this technical field.

[0008] Application Contents

[0009] The technical problem to be solved by the present invention is: how to solve the problem that the insertion loss consistency of conventional optical splitters is poor and the insertion loss consistency accumulates as the number of branches increases.

[0010] The present invention adopts the following technical solutions:

[0011] In a first aspect, a light splitting structure is provided, comprising: a main straight waveguide and a plurality of branch waveguides branched from the main straight waveguide;

[0012] There is a branch angle between the branch waveguide and the main straight waveguide;

[0013] There is a branch offset distance between the bifurcation position of the branch waveguide and the main straight waveguide and the optical axis of the main straight waveguide;

[0014] The branching angle and the branching offset distance are set according to the splitting ratio on the branch waveguide, so that the branch waveguide has a corresponding splitting ratio.

[0015] Preferably, there is a first relationship between the branching angle and the light splitting ratio corresponding to the branch waveguide;

[0016] There is a second relationship between the branch offset distance and the splitting ratio corresponding to the branch waveguide;

[0017] The splitting ratio corresponding to the branch waveguide is obtained according to the splitting ratio on the branch waveguide, and the branch angle and the branch offset distance are respectively set according to the first relationship, the second relationship and the splitting ratio corresponding to the branch waveguide.

[0018] Preferably, the splitting ratio on the branch waveguide is preset to be a first splitting ratio;

[0019] The splitting ratio corresponding to the branch waveguide = (first splitting ratio / P) / [1-(first splitting ratio / P)] n-1 , where n is the number of branches of the branch waveguide on the main straight waveguide, and P is the total splitting ratio on the main straight waveguide corresponding to the branch waveguide.

[0020] Preferably, the light splitting structure further includes a branch connection structure, and the branch connection structure is arranged between the main straight waveguide and the branch waveguide;

[0021] One end of the branch connection structure is connected to the main straight waveguide, and the other end of the branch connection structure is connected to the branch waveguide, and the optical axis of the branch connection structure coincides with the optical axis of the branch waveguide;

[0022] The branch connection structure is used to expand the size of the eigenmode spot in the branch waveguide, so as to increase the overlapping portion between the eigenmode in the branch waveguide and the eigenmode of the main straight waveguide, and to improve the light extraction capability of the branch waveguide.

[0023] Preferably, the branch connection structure includes a first connection structure, and the first connection structure includes multiple sections of gradient waveguides;

[0024] The multiple sections of gradient waveguides are arranged in sequence along the light splitting direction of the branch waveguides, and there is a preset interval between adjacent gradient waveguides;

[0025] The height of the gradient waveguide remains unchanged or gradually increases along the light splitting direction of the branch waveguide, and the width of the gradient waveguide remains unchanged or gradually increases along the light splitting direction of the branch waveguide;

[0026] The preset interval remains unchanged or gradually increases along the light splitting direction of the branch waveguide.

[0027] Preferably, the branch connection structure includes a second connection structure, the width of the starting point of the second connection structure is W0, the width of the tail of the second connection structure is W1, and the total length of the second connection structure is L0;

[0028] Along the light splitting direction of the branch waveguide, the width Wx of the second connection structure gradually increases;

[0029] At a distance dL from the starting point of the second connecting structure, the width of the second connecting structure Wx = W0 + f(dL / L0)*(W1-W0), where z = dL / L0, and the gradient function f(z) = a1*z+a2*z^2+…+an*z^n.

[0030] In a second aspect, a method for manufacturing a light splitting structure is provided, comprising:

[0031] Obtaining a splitting ratio corresponding to the branch waveguide according to the splitting ratio on the branch waveguide, and determining the branch angle and the branch offset distance respectively according to the splitting ratio corresponding to the branch waveguide;

[0032] Corresponding branch waveguides are separated from the main straight waveguide according to the branch angle and the branch offset distance, so that the branch waveguides have corresponding splitting ratios.

[0033] Preferably, obtaining the splitting ratio corresponding to the branch waveguide according to the splitting ratio on the branch waveguide includes:

[0034] The splitting ratio on the branch waveguide is preset as the first splitting ratio X, and the splitting ratio Y corresponding to the branch waveguide is obtained according to formula 1: Y = (X / P) / [1-(X / P)] n-1 Formula 1

[0035] Wherein, n is the number of branches arranged on the main straight waveguide where the branch waveguide is located, and P is the total splitting ratio on the main straight waveguide corresponding to the branch waveguide. Preferably, determining the branch angle and the branch offset distance respectively by the splitting ratio corresponding to the branch waveguide includes:

[0036] Establishing a first relationship between a branching angle and a light splitting ratio corresponding to the branch waveguide;

[0037] Establishing a second relationship between the branch offset distance and the splitting ratio corresponding to the branch waveguide;

[0038] The branching angle and the branching offset distance corresponding to the branching waveguide are obtained according to the splitting ratio of the branching waveguide, the first relationship, and the second relationship.

[0039] Preferably, obtaining the branch angle and the branch offset distance corresponding to the branch waveguide according to the splitting ratio of the branch waveguide, the first relationship, and the second relationship respectively includes:

[0040] Obtaining a branching angle corresponding to the light splitting ratio of the branch waveguide according to the first relationship;

[0041] The branch offset distance corresponding to the splitting ratio of the branch waveguide is obtained according to the second relationship.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] The optical splitting structure of the present invention includes a main straight waveguide and a plurality of branch waveguides branched from the main straight waveguide; a branch angle exists between the branch waveguide and the main straight waveguide; a branch offset distance exists between the bifurcation position of the branch waveguide and the main straight waveguide and the optical axis of the main straight waveguide; wherein the branch angle and the branch offset distance are set according to the splitting ratio on the branch waveguide so that the branch waveguide has a corresponding splitting ratio. The optical splitting structure proposed by the present invention does not change the optical path angle or bend at the branch of the main straight waveguide, so the input light of the branch waveguides above and below the main straight waveguide is still a quasi-symmetrical single-mode light field distribution, and the splitting ratios of the branch waveguides are independent of each other, so they can be optimized and controlled independently. Therefore, it is easy to achieve good optical characteristics with insertion loss consistency of nearly 0dB in design.

[0044] Furthermore, even if more branch waveguides are added or their spacing changes, the optical path arrangement does not change the light field distribution in the main straight waveguide, eliminating the need to modify the existing optical path design. Therefore, the optical splitting structure of the present invention offers greater flexibility and scalability in optical design. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 any creative work.

[0046] FIG1 is a schematic structural diagram of a prior art light splitting structure provided by an embodiment of the present invention;

[0047] FIG2 is a schematic structural diagram of a light splitting structure provided by an embodiment of the present invention;

[0048] 3 is a schematic diagram showing the relationship between the branching angle and the splitting ratio of a light splitting structure provided by an embodiment of the present invention;

[0049] 4 is a schematic diagram showing the relationship between branch offset distance and splitting ratio of a splitting structure provided by an embodiment of the present invention;

[0050] 5 is a schematic structural diagram of a first connection structure of a light splitting structure provided by an embodiment of the present invention;

[0051] 6 is a schematic structural diagram of a second connection structure of a light splitting structure provided by an embodiment of the present invention;

[0052] 7 is a schematic flow chart of a method for manufacturing a light splitting structure according to an embodiment of the present invention;

[0053] FIG8 is a schematic diagram of a first structure of a light splitting structure provided by an embodiment of the present invention;

[0054] 9 is a schematic diagram showing the relationship between wavelength and insertion loss consistency of a light splitting structure provided by an embodiment of the present invention;

[0055] FIG10 is a schematic structural diagram of a second structure of a light splitting structure provided by an embodiment of the present invention;

[0056] FIG11 is a schematic structural diagram of a third structure of a light splitting structure provided by an embodiment of the present invention;

[0057] FIG12 is a schematic structural diagram of a fourth type of light splitting structure provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0058] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0059] The terms "first," "second," etc., used in this disclosure are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referenced. Thus, a feature identified with "first," "second," etc., may explicitly or implicitly include one or more of such features. In the description of this disclosure, unless otherwise specified, "plurality" means two or more.

[0060] In the present invention, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium.

[0061] In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0062] Example 1:

[0063] In existing technologies, the insertion loss consistency of an equally split optical path is generally poor, and this consistency increases with the number of branches. The reason is as follows: Ideally, when a symmetrical single-mode light field is input to a 1:2 equally split structure, the light intensity ratio of the two output branches is completely symmetrical, that is, 50%:50%. However, in the design optical path of a conventional 1:N splitter, taking Figure 1 as an example, the input light of equally split structure 12 is transmitted from the output curved waveguide of the previous-stage splitting structure 11. The light field in the curved waveguide is inherently asymmetrical. Furthermore, the input waveguide of equally split structure 12 is angled, causing the asymmetric light field to oscillate within the input waveguide of equally split structure 12. Consequently, the output branches of equally split structure 12 deviate from the 50%:50 ratio, exhibiting a certain degree of asymmetry. This manifests as insertion loss consistency not exceeding 0dB. Furthermore, as the number of branches increases, the insertion loss consistency of each stage accumulates, and the more branches a splitter has, the worse the insertion loss consistency. This is also the reason why in the optical index requirements of commercial 1:N splitters, as N increases, the insertion loss consistency value also increases.

[0064] In order to solve the problem that the insertion loss consistency of conventional optical splitters in the prior art is poor and the insertion loss consistency accumulates with the increase of the number of branches, this embodiment provides a splitting structure, as shown in Figure 2, including: a main straight waveguide and multiple branch waveguides branched from the main straight waveguide; there is a branching angle between the branch waveguide and the main straight waveguide; there is a branch offset distance between the bifurcation position of the branch waveguide and the main straight waveguide and the optical axis of the main straight waveguide; wherein the branch angle and the branch offset distance are set according to the splitting ratio on the branch waveguide so that the branch waveguide has a corresponding splitting ratio.

[0065] Among them, the splitting structure includes a main straight waveguide and multiple branch waveguides branched from the main straight waveguide. As shown in Figure 2, there is a set branching angle A between the branch waveguide and the main straight waveguide, and there is a branch offset distance G between the bifurcation position of the branch waveguide and the optical axis of the main straight waveguide. In this structure, the corresponding splitting ratio can be obtained through the splitting ratio on the branch waveguide. By adjusting the splitting ratio corresponding to the branch waveguide, the branch angle and branch offset distance can be adjusted respectively. In other words, by adjusting the splitting ratio on the branch waveguide, the splitting performance of the branch waveguide, including the branch angle and branch offset distance, can be precisely adjusted. Such a design can achieve the desired splitting ratio on the branch waveguide, thereby meeting specific optical requirements and application needs. It is worth noting that the specific splitting ratio adjustment method may vary according to the actual application and device design. The branching angle can coarsely adjust the splitting ratio of the branch waveguide within a relatively large range, while the branch offset distance can fine-tune the splitting ratio of the branch waveguide within a relatively small range, thereby achieving equal splitting ratios in each branch waveguide and good insertion loss consistency between the branch waveguides.

[0066] In the optical splitting structure proposed in this embodiment, since the main straight waveguide does not change the optical path angle and does not bend at the branch, the input light of the branch waveguides above and below the main straight waveguide is still a quasi-symmetrical single-mode light field distribution. The splitting ratios of each branch waveguide are independent of each other, and can therefore be independently optimized and controlled. Therefore, it is easy to achieve good optical characteristics with an insertion loss consistency of nearly 0dB in design. On the other hand, even if the number of branch waveguides is increased or the spacing between the branch waveguides changes, the arrangement of the optical path will not cause the light field distribution in the main straight waveguide to change, and there is no need to modify the previous optical path design. Therefore, based on the optical splitting structure of the present invention, its optical design is more flexible and scalable.

[0067] In order to obtain the corresponding branching angle and branching offset distance according to the corresponding splitting ratio on the branch waveguide, in a preferred embodiment, there is a first relationship between the branching angle and the splitting ratio corresponding to the branch waveguide; there is a second relationship between the branching offset distance and the splitting ratio corresponding to the branch waveguide; the splitting ratio corresponding to the branch waveguide is obtained according to the splitting ratio on the branch waveguide, and the branching angle and the branching offset distance are respectively set according to the first relationship, the second relationship and the splitting ratio corresponding to the branch waveguide.

[0068] During the experimental stage, the branching angle is continuously adjusted to obtain a first relationship between the branching angle and the splitting ratio corresponding to the branch waveguide (as shown in FIG3 ); the branching bias distance is continuously adjusted to obtain a second relationship between the branching bias distance and the splitting ratio corresponding to the branch waveguide (as shown in FIG4 ); in the actual production process, the branching angle and the branching bias distance are set respectively according to the first and second relationships and the splitting ratio corresponding to the branch waveguide.

[0069] In order to obtain the first relationship and the second relationship, the following steps may be performed:

[0070] 1. First, obtain the transmission spectra corresponding to different splitting ratios on the branch waveguide through experimental means. In the experiment, a spectrometer or other measuring equipment can be used to record the transmission spectra under different splitting ratios.

[0071] 2. Based on the obtained transmission spectrum, calculate the transmittance corresponding to different splitting ratios on the branch waveguide. The transmittance can be calculated from the peak value of the transmission spectrum.

[0072] 3. By analyzing the obtained data, a first relationship between the branching angle and the splitting ratio and a second relationship between the branching offset distance and the splitting ratio can be obtained. These relationships can be obtained through fitting analysis, for example, using linear regression or other mathematical models to fit the data and derive the relationship.

[0073] 4. Based on the obtained relationship, the required branching angle and branch offset distance can be calculated according to the desired splitting ratio. These parameters can be used to adjust the splitting performance of the branching waveguide to obtain the required splitting ratio.

[0074] It is worth noting that the specific implementation method and parameter settings may vary depending on the device and application. In actual applications, adjustments and optimizations need to be made based on experimental and calibration requirements to obtain relatively accurate first and second relationships.

[0075] Next, it will be described how to obtain the splitting ratio corresponding to the branch waveguide shown according to the required splitting ratio.

[0076] The splitting ratio on the branch waveguide is preset to be the first splitting ratio; the splitting ratio of the branch waveguide = (first splitting ratio / P) / [1-(first splitting ratio / P)] n-1 , where n is the number of branches of the branch waveguide on the main straight waveguide.

[0077] The branch arrangement number refers to the order of the branch waveguide on the main straight waveguide, that is, the branch waveguide is branched for the nth time on the main straight waveguide, and P is the total splitting ratio on the main straight waveguide corresponding to the branch waveguide.

[0078] For example, in FIG2 , the main straight waveguide 20 (i.e., P=100%) and the branch waveguides 21, 22, 23, and 24 are configured. To achieve a splitting ratio of 3.75% for channel 1, the splitting ratio of the branch waveguide 21 is 3.75% (i.e., n=1); to achieve a splitting ratio of 3.75% for channel 5, the splitting ratio of the branch waveguide 22 is 3.75% ÷ (1-3.75%) = 3.896% (i.e., n=2). In order to make the splitting ratio of channel 2 3.75%, the splitting ratio of the branch waveguide 23 is 3.75% ÷ (1-3.75%) ^ 2 = 4.054%; in order to make the splitting ratio of channel 4 3.75%, the splitting ratio of the branch waveguide 24 is 3.75% ÷ (1-3.75%) ^ 3 = 4.225% (i.e., n = 3); in this way, after 4-way splitting, the remaining 85% of the light will enter channel 3.

[0079] By obtaining the splitting ratio corresponding to the first splitting ratio in the above manner, the branching angle and branch offset distance are respectively obtained based on the splitting ratio and the above first and second relationships. The entire splitting structure is then configured accordingly to obtain the desired splitting ratio on the branch waveguide.

[0080] In a preferred embodiment, in order to improve the light-collecting capability of the above-mentioned branch waveguide, in a preferred embodiment, the splitting structure further includes a branch connection structure, which is arranged between the main straight waveguide and the branch waveguide; one end of the branch connection structure is connected to the main straight waveguide, and the other end of the branch connection structure is connected to the branch waveguide, and the optical axis of the branch connection structure coincides with the optical axis of the branch waveguide; the branch connection structure is used to expand the size of the eigenmode spot in the branch waveguide to increase the overlapping part between the eigenmode in the branch waveguide and the eigenmode of the main straight waveguide, and to improve the light-collecting capability of the branch waveguide.

[0081] Among them, in this embodiment, two structures are proposed regarding the branch connection structure. As shown in Figure 5, the branch connection structure includes a first connection structure, which includes multiple sections of gradient waveguides; the multiple sections of gradient waveguides are arranged in sequence along the splitting direction of the branch waveguide, and there is a preset interval between adjacent gradient waveguides; the height of the gradient waveguide remains unchanged or gradually increases along the splitting direction of the branch waveguide, and the width of the gradient waveguide remains unchanged or gradually increases along the splitting direction of the branch waveguide; the preset interval remains unchanged or gradually increases along the splitting direction of the branch waveguide.

[0082] Wherein, the first connection structure includes a plurality of sections of gradient waveguides. In the splitting direction of the branch waveguide, there are multiple gradient waveguides, and each gradient waveguide is designed to change gradually. The multiple sections of gradient waveguides are arranged in sequence along the splitting direction of the branch waveguide, and are arranged on the branch waveguide in a certain order. They are specifically arranged between the branch waveguide and the main straight waveguide. There is a preset interval P between adjacent gradient waveguides. The preset interval can be a fixed distance in the splitting direction, or it can gradually increase along the splitting direction. Wherein, the height H of the gradient waveguide can remain unchanged or gradually increase along the splitting direction, and the width T can also remain unchanged or gradually increase. This design helps to achieve the expansion and adaptability of the light spot. The first connection structure is expected to achieve the expansion of the size of the eigenmode light spot in the branch waveguide through the design of multiple sections of gradient waveguides, thereby increasing the overlapping part with the eigenmode of the main straight waveguide, and then enhancing the light collection ability of the branch waveguide. The specific implementation requires detailed waveguide design and optimization, and its performance can be verified with the help of optical simulation tools and experimental verification.

[0083] In a preferred embodiment, as shown in Figure 6, the branch connection structure includes a second connection structure, the width of the starting point of the second connection structure is W0, the tail width of the second connection structure is W1, and the total length of the second connection structure is L0; along the splitting direction of the branch waveguide, the width Wx of the second connection structure gradually increases, and at a distance dL from the starting point of the second connection structure, the width Wx of the second connection structure is W0+f(dL / L0)*(W1-W0), wherein z=dL / L0, the gradient function f(z)=a1*z+a2*z^2+…+an*z^n.

[0084] Among them, during normal use, let a1=1, or let a2=1, and the shape of the second connecting structure can be adjusted according to needs to reduce the loss of the waveguide. Determine the design parameters of the second connecting structure, such as the starting point width W0, the tail width W1, and the total length L0. The selection of these parameters should take into account the specific needs and performance goals of the optical device. Define the form of the gradient function f(z), where z=dL / L0 represents the ratio of the position to the starting point. A suitable gradient function form can be selected, such as linear, quadratic, cubic, etc., and the specific form is determined by coefficients a1, a2, etc. The gradient function is used to calculate the width change of the second connecting structure along the splitting direction. According to the formula Wx=W0+f(dL / L0)*(W1-W0), the width Wx at different positions is calculated. Numerical simulation tools (such as optical waveguide simulation software) can be used to simulate and analyze the designed second connecting structure. By adjusting the parameters and observing the simulation results, the design of the connection structure is optimized to ensure that it achieves effective spot expansion in the branch waveguide. To improve the light extraction ability of the branch waveguide.

[0085] It is worth noting that in the design of a specific light splitting structure, the first connection structure and / or the second connection structure can be selected, that is, all first connection structures can be selected, or all second connection structures can be selected, or both the first connection structure and the second connection structure can be selected.

[0086] Example 2:

[0087] In Example 1, a light splitting structure is proposed. In this embodiment, a method for manufacturing the light splitting structure is proposed. As shown in FIG7 , the manufacturing method includes:

[0088] Step 101: obtaining a splitting ratio corresponding to the branch waveguide according to the splitting ratio on the branch waveguide, and determining the branching angle and the branching offset distance respectively according to the splitting ratio corresponding to the branch waveguide.

[0089] First, the splitting ratio corresponding to the branch waveguide is obtained according to the splitting ratio required on the branch waveguide. The splitting ratio on the branch waveguide is preset as the first splitting ratio X. The splitting ratio Y corresponding to the branch waveguide is obtained according to formula 1: Y = (X / P) / [1-(X / P)] n-1 Formula 1

[0090] Where n is the branch arrangement number of the branch waveguide on the main straight waveguide, and P is the total splitting ratio of the main straight waveguide corresponding to the branch waveguide. The branch arrangement number refers to the order of the branch waveguide on the main straight waveguide, that is, whether the branch waveguide branches for the nth time on the main straight waveguide.

[0091] A first relationship is established between the branch angle and the splitting ratio corresponding to the branch waveguide; a second relationship is established between the branch offset distance and the splitting ratio corresponding to the branch waveguide; and based on the splitting ratio of the branch waveguide, the first relationship, and the second relationship, the branch angle and branch offset distance corresponding to the branch waveguide are respectively obtained. Based on the first relationship, the branch angle corresponding to the splitting ratio of the branch waveguide is obtained; based on the second relationship, the branch offset distance corresponding to the splitting ratio of the branch waveguide is obtained. Regarding how to specifically obtain the first and second relationships, refer to Example 1 and will not be repeated in this embodiment.

[0092] Step 102: Branching corresponding branch waveguides from the main straight waveguide according to the branching angle and the branch offset distance, so that the branch waveguides have corresponding splitting ratios.

[0093] The splitting ratio Y corresponding to the first splitting ratio X is obtained using the above formula 1. The branching angle and branch offset distance are then calculated based on this splitting ratio and the above first and second relationships. Finally, the entire splitting structure is configured accordingly based on the calculated branching angles and branch offset distances to produce a splitting structure that achieves the desired splitting ratio on the branch waveguide.

[0094] The specific structure of the light splitting structure is described in Example 1 and will not be further explained here.

[0095] Example 3:

[0096] A beam splitting structure was proposed in Example 1. In this example, a first example is provided to further illustrate the beam splitting structure. In this example, it is assumed that a 1:5 unequal beam splitting structure is designed and fabricated on a planar optical waveguide fabrication process platform with a refractive index contrast of 0.36%.

[0097] A 1x5 non-uniform optical structure with good insertion loss consistency. As shown in Figure 8, the non-uniform optical structure includes at least: a main straight waveguide 20, and branch waveguides 21, 22, 23, and 24 that directly split the main straight waveguide 20. Taking branch waveguide 21 as an example, branch waveguide 21 has the following characteristics: a branch angle A is defined between the optical axis 212 of the branch waveguide and the optical axis 211 of the main straight waveguide 20; and a branch offset distance G is defined between the bifurcation centerline 213 of the branch waveguide's optical axis 21 and the optical axis 211 of the main straight waveguide 20.

[0098] To obtain a 1:5 non-uniformly divided structure of 85%:3.75%:3.75%:3.75%:3.75%, this can be achieved by controlling the branch angle A and the branch offset distance G. The specific method is as follows: First, the splitting ratio requirement of each branch waveguide is calculated. In order to make the splitting ratio of channel 1 3.75%, the splitting ratio of the branch waveguide 21 is 3.75%; in order to make the splitting ratio of channel 5 3.75%, the splitting ratio of the branch waveguide 22 is 3.75% ÷ (1-3.75%) = 3.896%; in order to make the splitting ratio of channel 2 3.75%, the splitting ratio of the branch waveguide 23 is 3.75% ÷ (1-3.75%) ^ 2 = 4.054%; in order to make the splitting ratio of channel 4 3.75%, the splitting ratio of the branch waveguide 24 is 3.75% ÷ (1-3.75%) ^ 3 = 4.225%; in this way, after the four-way splitting, the remaining 85% of the light will enter channel 3.

[0099] As shown in Figure 8 , by controlling the branching angle A of the branch waveguides 21, 22, 23, and 24, the ability to adjust the splitting ratio can be achieved over a relatively wide range. As shown in Figure 3 , the branching angle A can be selected to be 5.5°, so that the splitting ratio of the splitting waveguide is close to the desired 3.75% to 4.225%.

[0100] As shown in Figure 8 , by controlling the branch offset distance G of the branch waveguides 21, 22, 23, and 24, precise adjustment of the splitting ratio can be achieved within a relatively small range. As shown in Figure 4 , the branch offset distance G of the branch waveguides 21, 22, 23, and 24 can be 1.16 μm, 1.03 μm, 0.90 μm, and 0.75 μm, respectively.

[0101] The measured spectrum of a 1:5 non-equal splitter designed according to the scheme of this embodiment is shown in Figure 9. The insertion loss consistency between the four branches with a splitting ratio of 3.75% is ≤0.2dB. The typical value of the insertion loss consistency of the traditional commercial 1:5 non-equal splitting structure is 0.6dB, and the commercial index requirement is 0.8dB. The technical effect achieved by this embodiment is far superior to the current traditional splitting structure scheme and commercial index requirements. The fundamental reason is that the theoretical design insertion loss consistency of this embodiment can be easily designed to be close to the theoretical value of 0dB, while the traditional splitting structure scheme is affected by the bending of the branch light path and the distortion of the light field. It is almost impossible to eliminate the insertion loss consistency in design, and the insertion loss consistency will increase with the increase of the number of branches. For the specific structure of the splitting structure, please refer to Example 1 and will not be explained in detail here.

[0102] Example 4:

[0103] In Example 1, a splitting structure was proposed. In this example, a second example is presented to further illustrate the splitting structure. A 1x5 unequal optical path structure, as shown in Figure 10, includes at least a main straight waveguide 80 and branch waveguides 81, 82, 83, and 84 that directly split the main optical path straight waveguide 80.

[0104] To achieve a 1:5 unequal split structure of 85%:3.75%:3.75%:3.75%:3.75%, the splitting ratio of branch waveguide 81 is 3.75%; the splitting ratio of branch waveguide 82 is 3.896%; the splitting ratio of branch waveguide 83 is 4.054%; and the splitting ratio of branch waveguide 84 is 4.225%. Thus, after the four-way splitting, the remaining 85% of the light will enter channel 5. The specific structure of the splitting structure is described in Example 1 and will not be further explained here.

[0105] Example 5:

[0106] In embodiment 1, a light splitting structure is proposed. In this embodiment, a third example is proposed to further illustrate the light splitting structure.

[0107] This embodiment provides a 1x5 non-uniform optical path structure with good insertion loss consistency. As shown in Figure 11, the non-uniform optical path structure includes at least: a main straight waveguide 90, branch waveguides 91 and 92 that directly split light from the main straight waveguide 90, an equal-splitting structure 93 located on the branch optical path of branch waveguide 91, and an equal-splitting structure 94 located on the branch optical path of branch waveguide 92.

[0108] To achieve a 1:5 non-uniform splitting structure of 85%:3.75%:3.75%:3.75%:3.75%, branch waveguide 91 splits the light at a ratio of 7.5%; branch waveguide 92 splits the light at a ratio of 8.11%; the equally split structure 93 splits the light at a ratio of 50%; and the equally split structure 94 splits the light at a ratio of 50%. Thus, after four-way splitting, the remaining 85% of the light enters channel 3. Because the sum of the splits of channels 1 and 2 is independently controlled by branch waveguide 91, and the sum of the splits of channels 3 and 4 is independently controlled by branch waveguide 92, insertion loss consistency between channels is not accumulated. This structure offers excellent insertion loss consistency and is easy to optimize.

[0109] The specific structure of the light splitting structure is described in Example 1 and will not be further explained here.

[0110] Example 6:

[0111] In embodiment 1, a light splitting structure is proposed. In this embodiment, a fourth example is proposed to further illustrate the light splitting structure.

[0112] This embodiment provides a non-uniform optical path structure with good insertion loss consistency of 2x10. As shown in Figure 12, the non-uniform optical path structure includes at least: a main straight waveguide 100, an equally divided structure 101 on the main straight waveguide 100, an upper branch 1011 and a lower branch 1012 of the equally divided structure 101, branch waveguides 102, 103, 104, and 105 that directly split light from the upper branch 1011, and branch waveguides 106, 107, 1010, and 109 that directly split light from the lower branch 1012. The upper branch 1011 serves as the main straight waveguide for branch waveguides 102, 103, 104, and 105, and the lower branch 1012 serves as the main straight waveguide for branch waveguides 106, 107, 1010, and 109.

[0113] In order to obtain a 2x10 non-uniform structure of 35%:35%:3.75%:3.75%:3.75%:3.75%:3.75%:3.75%:3.75%:3.75%, the light splitting ratio of the equally divided structure 101 is 50%. In this embodiment, since the light splitting ratio of the equally divided structure 101 is 50%, the formula 1 Y = (X / P) / [1-(X / P)] n-1 In the figure, the P value is 50%, so the splitting ratio of the branch waveguide 102 is 7.5%; the splitting ratio of the branch waveguide 103 is 8.11%; the splitting ratio of the branch waveguide 104 is 8.82%; the splitting ratio of the branch waveguide 105 is 9.68%; the splitting ratio of the branch waveguide 106 is 7.5%; the splitting ratio of the branch waveguide 107 is 8.11%; the splitting ratio of the branch waveguide 108 is 8.82%; the splitting ratio of the branch waveguide 109 is 9.68%; the remaining 35% of the light in the lower branch 1012 will enter the channel 6.

[0114] Because the splitting ratios of channels 1, 2, 3, and 4 are independently controlled by branch waveguides 101, 102, 103, and 104, and the splitting ratios of channels 7, 8, 9, and 10 are independently controlled by branch waveguides 106, 107, 108, and 109, the insertion loss consistency between channels can be optimized independently. This structure offers excellent insertion loss consistency and is easily optimized.

[0115] The specific structure of the light splitting structure is described in Example 1 and will not be further explained here.

[0116] 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 and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A light splitting structure, characterized in that: include: A main straight waveguide and a plurality of branch waveguides branched from the main straight waveguide; There is a branch angle between the branch waveguide and the main straight waveguide; There is a branch offset distance between the bifurcation position of the branch waveguide and the main straight waveguide and the optical axis of the main straight waveguide; The branch angle and the branch offset distance are set according to the splitting ratio on the branch waveguide, so that the branch waveguide has a corresponding splitting ratio.

2. The light splitting structure according to claim 1, characterized in that: There is a first relationship between the branching angle and the light splitting ratio corresponding to the branch waveguide; There is a second relationship between the branch offset distance and the light splitting ratio corresponding to the branch waveguide; The splitting ratio corresponding to the branch waveguide is obtained according to the splitting ratio on the branch waveguide, and the branch angle and the branch offset distance are respectively set according to the first relationship, the second relationship and the splitting ratio corresponding to the branch waveguide.

3. The light splitting structure according to claim 2, characterized in that: Presetting the splitting ratio on the branch waveguide to be a first splitting ratio; The splitting ratio corresponding to the branch waveguide = (first splitting ratio / P) / [1-(first splitting ratio / P)] n-1 , where n is the number of branches of the branch waveguide on the main straight waveguide, and P is the total splitting ratio on the main straight waveguide corresponding to the branch waveguide.

4. The light splitting structure according to claim 1, characterized in that: The light splitting structure further includes a branch connection structure, and the branch connection structure is arranged between the main straight waveguide and the branch waveguide; One end of the branch connection structure is connected to the main straight waveguide, the other end of the branch connection structure is connected to the branch waveguide, and the optical axis of the branch connection structure coincides with the optical axis of the branch waveguide; The branch connection structure is used to expand the size of the eigenmode spot in the branch waveguide, so as to increase the overlapping portion between the eigenmode in the branch waveguide and the eigenmode of the main straight waveguide, and to enhance the light extraction capability of the branch waveguide.

5. The light splitting structure according to claim 4, characterized in that: The branch connection structure includes a first connection structure, and the first connection structure includes a plurality of sections of gradient waveguides; The multiple sections of gradient waveguides are arranged in sequence along the light splitting direction of the branch waveguide, and there is a preset interval between adjacent gradient waveguides; The height of the gradient waveguide remains unchanged or gradually increases along the light splitting direction of the branch waveguide, and the width of the gradient waveguide remains unchanged or gradually increases along the light splitting direction of the branch waveguide; The preset interval remains unchanged or gradually increases along the light splitting direction of the branch waveguide.

6. The light splitting structure according to claim 5, characterized in that: The height H of the gradient waveguide can remain unchanged or gradually increase along the light splitting direction, and the width T can also remain unchanged or gradually increase.

7. The light splitting structure according to claim 5, characterized in that: The branch connection structure includes a second connection structure, the width of the starting point of the second connection structure is W0, the width of the tail of the second connection structure is W1, and the total length of the second connection structure is L0; Along the light splitting direction of the branch waveguide, the width Wx of the second connection structure gradually increases; At a distance dL from the starting point of the second connecting structure, the width of the second connecting structure Wx=W0+f(dL / L0)*(W1-W0), wherein z=dL / L0, and the gradient function f(z)=a1*z+a2*z^2+…+an*z^n.

8. The light splitting structure according to claim 7, characterized in that: In normal use, by setting a1=1 or a2=1, the shape of the second connection structure can be adjusted according to demand to reduce the loss of the waveguide.

9. The light splitting structure according to claim 7, characterized in that: Select a suitable gradient function form, such as linear, quadratic, cubic, etc. The specific form is determined by coefficients a1, a2, etc.

10. The light splitting structure according to claim 7, characterized in that: In the design of a specific light splitting structure, the first connection structure and / or the second connection structure may be selected.

11. A method for manufacturing a light splitting structure, characterized in that: The manufacturing method is used to manufacture the light splitting structure according to any one of claims 1 to 10, comprising: Obtaining the splitting ratio corresponding to the branch waveguide according to the splitting ratio on the branch waveguide, and determining the branch angle and the branch offset distance respectively according to the splitting ratio corresponding to the branch waveguide; Corresponding branch waveguides are separated from the main straight waveguide according to the branch angle and the branch offset distance, so that the branch waveguides have corresponding splitting ratios.

12. The method for manufacturing a light splitting structure according to claim 11, characterized in that: The step of obtaining the splitting ratio corresponding to the branch waveguide according to the splitting ratio on the branch waveguide comprises: The splitting ratio on the branch waveguide is preset as a first splitting ratio X, and the splitting ratio Y corresponding to the branch waveguide is obtained according to formula 1; Y=(X / P) / [1-(X / P)] n-1 Formula 1 Wherein, n is the number of branches arranged on the main straight waveguide where the branch waveguide is located, and P is the total splitting ratio on the main straight waveguide corresponding to the branch waveguide.

13. The method for manufacturing a light splitting structure according to claim 11, characterized in that: The determining the branch angle and the branch offset distance respectively by the splitting ratio corresponding to the branch waveguide comprises: Establishing a first relationship between a branching angle and a light splitting ratio corresponding to the branch waveguide; Establishing a second relationship between the branch offset distance and the light splitting ratio corresponding to the branch waveguide; According to the splitting ratio of the branch waveguide, the first relationship and the second relationship, the branch angle and the branch offset distance corresponding to the branch waveguide are obtained respectively.

14. The method for manufacturing a light splitting structure according to claim 13, characterized in that: By continuously adjusting the branching angle, a first relationship between the branching angle and the light splitting ratio corresponding to the branch waveguide is obtained; By continuously adjusting the branch offset distance, a second relationship between the branch offset distance and the light splitting ratio corresponding to the branch waveguide is obtained.

15. The method for manufacturing a light splitting structure according to claim 13, characterized in that: The step of obtaining the branch angle and the branch offset distance corresponding to the branch waveguide according to the splitting ratio of the branch waveguide, the first relationship, and the second relationship comprises: Obtaining a branching angle corresponding to the light splitting ratio of the branch waveguide according to the first relationship; The branch offset distance corresponding to the splitting ratio of the branch waveguide is obtained according to the second relationship.

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