Light splitting structure and manufacturing method thereof

Abstract

The invention relates to the technical field of optical splitters, in particular to an optical splitting structure and a manufacturing method thereof, and the optical splitting structure comprises a main path straight waveguide and a plurality of branch waveguides branched from the main path straight waveguide; a branch angle exists between the branch waveguide and the main straight waveguide; a branch offset distance exists between the branching position of the branch waveguide and the main path straight waveguide and the optical axis of the main path 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 the corresponding splitting ratio. Because the main path straight waveguide does not change the light path angle at the branch and is not bent, the input light of the branch waveguides at the upper and lower levels of the main path straight waveguide is still in quasi-symmetric single-mode light field distribution. The light splitting proportions of the branch waveguides are mutually independent, so that the branch waveguides can be independently optimized and controlled, and the optical characteristic that the insertion loss consistency is almost 0dB can be easily realized.

Description

Technical Field

[0001] The present invention relates to the technical field of spectrometers, and in particular to a spectrometer structure and a manufacturing method thereof. Background Art

[0002] In a passive optical network, the optical distribution network (ODN) is the optical transmission channel from the optical line terminal in the communication center room to the optical network unit on the user side. Among them, the optical branching device is the core device in the point-to-multipoint ODN architecture. The optical branching device used in the new generation of fiber-optic user access network (Fiber to the x, abbreviated as FTTx) is mainly an optical splitter, which is used to achieve 1:N optical power distribution. In traditional ODN networks, 1:N optical splitters usually adopt a uniform distribution structure, such as the most common equal distribution ratios of 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 the flexibility and scalability of the network. Therefore, a pre-connected ODN network is proposed, which adopts an optical splitter structure with a non-equal distribution ratio. The most common ones are 1:5 and 1:9 non-equal distribution structures.

[0003] Conventional non-equally divided structures, taking 1:5 as an example, usually use a non-equally divided structure to divide the input light into two branches of 85% and 15%, and then divide the 15% branch into two 7.5% optical path branches through the equal division structure, and these two 7.5% optical path branches are divided into four 3.75% optical path branches through the equal division structure. With this design structure, the insertion loss consistency of the four equally divided light paths is usually not very good. Moreover, as the number of branches increases, the insertion loss consistency will become greater and greater. On the other hand, in order to obtain ideal insertion loss consistency, the optical waveguide chip needs to optimize the design of each level of branches during the design process; if the optical path increases, or the spacing between the branch optical paths changes, the optical path arrangement will change, and the asymmetric distribution of the light field of each branch will also change, then the entire optical path structure must be re-optimized, so the structural design optimization work is complicated, the workload is large, and the time is long.

[0004] In view of this, overcoming the defects of the prior art is an urgent problem to be solved in the field of this technology. Summary of the invention

[0005] 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.

[0006] The present invention adopts the following technical solution:

[0007] 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;

[0008] There is a branch angle between the branch waveguide and the main straight waveguide;

[0009] 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;

[0010] 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.

[0011] Preferably, there is a first relationship between the branching angle and the light splitting ratio corresponding to the branch waveguide;

[0012] There is a second relationship between the branch offset distance and the light splitting ratio corresponding to the branch waveguide;

[0013] 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.

[0014] Preferably, the splitting ratio on the branch waveguide is preset to be a first splitting ratio;

[0015] 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.

[0016] 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;

[0017] 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;

[0018] 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.

[0019] Preferably, the branch connection structure includes a first connection structure, and the first connection structure includes a plurality of sections of gradient waveguides;

[0020] 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;

[0021] 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;

[0022] The preset interval remains unchanged or gradually increases along the light splitting direction of the branch waveguide.

[0023] 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;

[0024] Along the light splitting direction of the branch waveguide, the width Wx of the second connection structure gradually increases;

[0025] 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.

[0026] In a second aspect, a method for manufacturing a light splitting structure is provided, comprising:

[0027] 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;

[0028] 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.

[0029] Preferably, obtaining the splitting ratio corresponding to the branch waveguide according to the splitting ratio on the branch waveguide includes:

[0030] 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;

[0031] Y=(X / P) / [1-(X / P)] n-1 Formula 1

[0032] 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, the determining the branch angle and the branch offset distance respectively by the splitting ratio corresponding to the branch waveguide comprises:

[0033] Establishing a first relationship between a branching angle and a light splitting ratio corresponding to the branch waveguide;

[0034] Establishing a second relationship between the branch offset distance and the light splitting ratio corresponding to the branch waveguide;

[0035] The branching angle and the branching offset distance corresponding to the branching waveguide are obtained respectively according to the splitting ratio of the branching waveguide, the first relationship and the second relationship.

[0036] Preferably, obtaining the branch angle and the branch offset distance corresponding to the branch waveguide respectively according to the splitting ratio of the branch waveguide, the first relationship and the second relationship comprises:

[0037] Obtaining a branching angle corresponding to the light splitting ratio of the branch waveguide according to the first relationship;

[0038] The branch offset distance corresponding to the splitting ratio of the branch waveguide is obtained according to the second relationship.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 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; 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; 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 branching point of the main straight waveguide. Therefore, the input light of the branch waveguides at the upper and lower levels of the main straight waveguide is still a quasi-symmetrical single-mode light field distribution, and the splitting ratios of each branch waveguide 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 close to 0dB in design.

[0041] On the other hand, even if the number of branch waveguides increases or the spacing between 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 light splitting structure of the present invention, the flexibility and scalability of its optical design are stronger. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] 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.

[0043] Figure 1 is a schematic diagram of the structure of a prior art light splitting structure provided by an embodiment of the present invention;

[0044] Figure 2 is a structural schematic diagram of a light splitting structure provided by an embodiment of the present invention;

[0045] Figure 3 is a schematic diagram of the relationship between the branching angle and the splitting ratio of a splitting structure provided by an embodiment of the present invention;

[0046] Figure 4 It is a schematic diagram of the relationship between the branch offset distance and the splitting ratio of a splitting structure provided by an embodiment of the present invention;

[0047] Figure 5 is a structural schematic diagram of a first connection structure of a light splitting structure provided by an embodiment of the present invention;

[0048] Figure 6 is a structural schematic diagram of a second connection structure of a light splitting structure provided by an embodiment of the present invention;

[0049] Figure 7 It is a schematic flow chart of a method for manufacturing a light splitting structure provided by an embodiment of the present invention;

[0050] Figure 8 is a schematic diagram of a first structure of a light splitting structure provided by an embodiment of the present invention;

[0051] Fig. 9 It is a schematic diagram of the relationship between the wavelength and insertion loss consistency of a light splitting structure provided by an embodiment of the present invention;

[0052] Fig.10 is a structural schematic diagram of a second structure of a light splitting structure provided by an embodiment of the present invention;

[0053] Fig.11 is a structural schematic diagram of a third structure of a light splitting structure provided by an embodiment of the present invention;

[0054] Fig.12 It is a structural schematic diagram of a fourth structure of a light splitting structure provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with 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.

[0056] The terms "first", "second", etc. in the present invention are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0057] 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.

[0058] 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.

[0059] Embodiment 1:

[0060] In the existing technical means, the insertion loss consistency of the equally divided optical path is usually not very good, and as the number of branches increases, the insertion loss consistency will become increasingly larger. The reason is as follows: Ideally, when a symmetrical single-mode optical field is input to a 1:2 equally divided structure, the light intensity ratio of the two output branches is completely symmetrical, that is, 50%:50%. In the design optical path of a conventional 1:N splitter, Figure 1 For example, the input light of the equally divided structure 12 is transmitted from the output curved waveguide of the previous level splitting structure 11. The light field itself is not symmetrical in the curved waveguide. At the same time, the input waveguide of the equally divided structure 12 has an angle, so the asymmetric light field will oscillate and transmit in the input waveguide of the equally divided structure 12. Then the output branches of the equally divided structure 12 will deviate from 50%:50%, and have a certain asymmetry, which will be reflected in the insertion loss consistency not being 0dB. Moreover, as the number of branches increases, the insertion loss consistency of each level will continue to accumulate. The more branches the 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 value of insertion loss consistency also increases.

[0061] 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 as the number of branches increases, this embodiment provides a splitting structure, such as Figure 2As shown, it includes: 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; 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.

[0062] The light splitting structure includes a main straight waveguide and a plurality of branch waveguides branched from the main straight waveguide. Figure 2 As shown, there is a set branch 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 by the splitting ratio on the branch waveguide. By adjusting the splitting ratio corresponding to the branch waveguide, the branch angle and the 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 the branch offset distance, can be accurately adjusted. Such a design can achieve the required 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 depending on the actual application and device design. The branch angle can roughly 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 achieving good insertion loss consistency between each branch waveguide.

[0063] In the splitting structure proposed in this embodiment, since the main straight waveguide does not change the optical path angle at the branch and does not bend, the input light of the branch waveguides at the upper and lower levels of 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 increases 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 splitting structure of the present invention, the optical design is more flexible and scalable.

[0064] In order to obtain the corresponding branching angle and branch offset distance according to the corresponding splitting ratio on the branch waveguide, in a preferred embodiment, there is a first relationship between the branch angle and the splitting ratio corresponding to the branch waveguide; there is a second relationship between the branch 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 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.

[0065] In the experimental stage, the branching angle is continuously adjusted to obtain the first relationship between the branching angle and the splitting ratio corresponding to the branch waveguide (such as Figure 3 By continuously adjusting the branch offset distance, a second relationship between the branch offset distance and the splitting ratio corresponding to the branch waveguide is obtained (as shown in Figure 4 As shown); in the actual production process, the branch angle and the branch offset distance are set respectively according to the first relationship and the second relationship and by the splitting ratio corresponding to the branch waveguide.

[0066] In order to obtain the first relationship and the second relationship, the following steps may be performed:

[0067] 1. First, the transmission spectra corresponding to different splitting ratios on the branch waveguide are obtained through experiments or other means. In the experiment, a spectrometer or other measuring equipment can be used to record the transmission spectra under different splitting ratios.

[0068] 2. According to the obtained transmission spectrum, calculate the transmittance corresponding to different splitting ratios on the branch waveguide. The transmittance can be calculated by the peak value of the transmission spectrum.

[0069] 3. By analyzing the obtained data, a first relationship between the branch angle and the splitting ratio and a second relationship between the branch offset distance and the splitting ratio can be obtained. These relationships can be obtained by fitting analysis, for example, linear regression or other mathematical models can be used to fit the data and obtain a relationship.

[0070] 4. The obtained relationship can be used to calculate the required branching angle and branching offset distance according to the required splitting ratio. These parameters can be used to adjust the splitting performance of the branch waveguide to obtain the required splitting ratio.

[0071] It is worth noting that the specific implementation method and parameter settings may vary depending on the device and application. In practical applications, it is necessary to adjust and optimize according to the experimental and calibration requirements to obtain relatively accurate first and second relationships.

[0072] Next, it will be described how to obtain the splitting ratio corresponding to the branch waveguide shown according to the required splitting ratio.

[0073] 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.

[0074] The branch arrangement number refers to the number of the branch waveguides 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.

[0075] For example, in Figure 2 In the main straight waveguide 20 (i.e., P = 100%), the branch waveguides 21, 22, 23, 24, in order to make the splitting ratio of channel 1 3.75%, the splitting ratio of the branch waveguide 21 is 3.75% (i.e., n = 1); 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% (i.e., n = 2); in order to make The splitting ratio of channel 2 is 3.75%, and 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.

[0076] According to the above method, the splitting ratio corresponding to the first splitting ratio is obtained, and then the branch angle and the branch offset distance are obtained according to the splitting ratio and the first relationship and the second relationship. Then, the entire splitting structure is set accordingly to obtain the required splitting ratio on the branch waveguide.

[0077] In a preferred embodiment, in order to improve the light-collecting capability of the above-mentioned branch waveguide, in a preferred embodiment, the light-splitting structure also 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.

[0078] In this embodiment, two structures are proposed for the branch connection structure, such as Figure 5 As shown, the branch connection structure includes a first connection structure, which includes a plurality of sections of gradually changing waveguides; the plurality of sections of gradually changing waveguides are arranged in sequence along the splitting direction of the branch waveguide, and there is a preset interval between adjacent gradually changing waveguides; the height of the gradually changing waveguide remains unchanged or gradually increases along the splitting direction of the branch waveguide, and the width of the gradually changing 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.

[0079] Among them, 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 be gradually changed. Multiple sections of gradient waveguides are arranged in sequence along the splitting direction of the branch waveguide, arranged on the branch waveguide in a certain order, and are specifically arranged between the branch waveguide and the main straight waveguide. There is a preset interval P between adjacent gradient waveguides, and the preset interval can be a fixed distance in the splitting direction, or it can be gradually increased along the splitting direction. Among them, 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.

[0080] In a preferred embodiment, Figure 6 As shown, 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, let z=dL / L0, and the gradient function f(z)=a1*z+a2*z^2+…+an*z^n.

[0081] Among them, in the normal use process, let a1=1, or let a2=1, the shape of the second connection structure can be adjusted according to the needs to reduce the loss of the waveguide. Determine the design parameters of the second connection 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. You can choose a suitable gradient function form, such as linear, quadratic, cubic, etc., and the specific form is determined by coefficients a1, a2, etc. Use the gradient function to calculate the width change of the second connection structure along the splitting direction. According to the formula Wx=W0+f(dL / L0)*(W1-W0), calculate the width Wx at different positions. The designed second connection structure can be simulated and analyzed using numerical simulation tools (such as optical waveguide simulation software). 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 collection ability of the branch waveguide.

[0082] 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.

[0083] Embodiment 2:

[0084] In the first embodiment, a light splitting structure is proposed. In the present embodiment, a method for manufacturing the light splitting structure is proposed. Figure 7 As shown, the manufacturing method comprises:

[0085] Step 101: 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.

[0086] 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, and the splitting ratio Y corresponding to the branch waveguide is obtained according to Formula 1:

[0087] Y=(X / P) / [1-(X / P)] n-1 Formula 1

[0088] Wherein, n is the branch arrangement number 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. Wherein, the branch arrangement number refers to the number of branches 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.

[0089] A first relationship between a branch angle and a light splitting ratio corresponding to a branch waveguide is established; a second relationship between a branch offset distance and a light splitting ratio corresponding to a branch waveguide is established; and according to the light 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. According to the first relationship, the branch angle corresponding to the light splitting ratio of the branch waveguide is obtained; according to the second relationship, the branch offset distance corresponding to the light splitting ratio of the branch waveguide is obtained. Wherein, as to how to specifically obtain the first relationship and the second relationship, refer to Example 1, which will not be repeated in this embodiment.

[0090] Step 102: Branching a corresponding branch waveguide from the main straight waveguide according to the branch angle and the branch offset distance, so that the branch waveguide has a corresponding splitting ratio.

[0091] According to the above formula 1, the splitting ratio Y corresponding to the first splitting ratio X is obtained, and then the branching angle and the branching offset distance are obtained according to the splitting ratio and the above first relationship and the second relationship. Finally, according to the calculated branching angle and branching offset distance, the entire splitting structure is set accordingly, and a splitting structure that can obtain the required splitting ratio on the branch waveguide can be manufactured.

[0092] The specific structure of the light splitting structure is referred to in Example 1 and will not be further described here.

[0093] Embodiment 3:

[0094] A light splitting structure is proposed in Example 1. In this example, a first example is proposed to further illustrate the light splitting structure. In this example, it is assumed that a 1:5 non-uniform light splitting structure is designed and manufactured on a planar optical waveguide manufacturing process platform with a refractive index contrast of 0.36%.

[0095] A 1x5 non-uniform optical structure with good insertion loss consistency. Figure 8 As shown, the non-uniform optical structure at least includes: a main straight waveguide 20, and branch waveguides 21, 22, 23 and 24 that directly split light from the main optical straight waveguide 20. Taking the branch waveguide 21 as an example, the branch waveguide 21 has the following characteristics: a certain branch angle A exists between the optical axis 212 of the branch waveguide and the optical axis 211 of the main straight waveguide 20; a certain branch offset distance G exists between the bifurcated central axis 213 of the optical axis 21 of the branch waveguide and the optical axis 211 of the main straight waveguide 20.

[0096] In order to obtain a 1:5 non-uniform 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 4-way splitting, the remaining 85% of the light will enter channel 3.

[0097] like Figure 8 As shown, by controlling the branching angles A of the branch waveguides 21, 22, 23, and 24, the ability to adjust the light splitting ratio can be obtained in a relatively large range. Figure 3 It can be seen from the figure that the branching angle A can be selected to be 5.5°, so that the splitting ratio of the splitting waveguide is close to the required 3.75% to 4.225%.

[0098] like Figure 8 As shown, by controlling the branch offset distance G of the branch waveguides 21, 22, 23, and 24, the ability to precisely adjust the splitting ratio can be obtained within a relatively small range. Figure 4 It can be seen that the branch offset distances G of the branch waveguides 21, 22, 23, and 24 can be 1.16um, 1.03um, 0.90um, and 0.75um, respectively.

[0099] The measured spectrum of a 1:5 non-uniform beam splitter designed according to the present embodiment is shown in FIG. Fig. 9 As shown. The insertion loss consistency between the 4-way 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 unequal 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 optical 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.

[0100] Embodiment 4:

[0101] In the first embodiment, a light splitting structure is proposed. In this embodiment, a second example is proposed to further illustrate the light splitting structure. A 1x5 non-uniform light path structure. Fig.10 As shown, it at least includes: a main optical path straight waveguide 80, and branch waveguides 81, 82, 83, 84 that directly split the main optical path straight waveguide 80.

[0102] In order to obtain a 1:5 non-equally divided structure of 85%:3.75%:3.75%:3.75%:3.75%, the splitting ratio of the branch waveguide 81 is 3.75%; the splitting ratio of the branch waveguide 82 is 3.896%; the splitting ratio of the branch waveguide 83 is 4.054%; and the splitting ratio of the branch waveguide 84 is 4.225%. In this way, after 4-way splitting, the remaining 85% of the light will enter the channel 5. For the specific structure of the splitting structure, refer to Example 1, and no further explanation is given here.

[0103] Embodiment 5:

[0104] In the first embodiment, a light splitting structure is proposed. In this embodiment, a third example is proposed to further illustrate the light splitting structure.

[0105] This embodiment provides a 1x5 non-uniform optical path structure with good insertion loss consistency. Fig.11 As shown, the non-equally divided optical path structure includes at least: a main straight waveguide 90, a branch waveguide 91 and a branch waveguide 92 that directly split light from the main straight waveguide 90, an equal-dividing structure 93 located on the branch optical path of the branch waveguide 91, and an equal-dividing structure 94 located on the branch optical path of the branch waveguide 92.

[0106] In order to obtain a 1:5 non-equally divided structure of 85%:3.75%:3.75%:3.75%:3.75%, the splitting ratio of the branch waveguide 91 is 7.5%; the splitting ratio of the branch waveguide 92 is 8.11%; the splitting ratio of the equal-division structure 93 is 50%; the splitting ratio of the equal-division structure 94 is 50%; in this way, after 4-way splitting, the remaining 85% of the light will enter channel 3. Since the sum of the splitting of channels 1 and 2 is independently controlled by the branch waveguide 91, and the sum of the splitting of channels 3 and 4 is independently controlled by the branch waveguide 92, the insertion loss consistency between channels will not accumulate. This structure has the characteristics of good insertion loss consistency and easy optimization design.

[0107] The specific structure of the light splitting structure is referred to in Example 1 and will not be further described here.

[0108] Embodiment 6:

[0109] In the first embodiment, a light splitting structure is proposed. In this embodiment, a fourth example is proposed to further illustrate the light splitting structure.

[0110] This embodiment provides a non-uniform optical path structure with good insertion loss consistency of 2x10. Fig.12 As shown, the non-equally divided optical path structure at least includes: a main straight waveguide 100, an equally divided structure 101 on the main optical path straight waveguide 100, an upper branch 1011 and a lower branch 1012 of the equally divided structure 101, branch waveguides 102, 103, 104, 105 that directly split light from the upper branch 1011, and branch waveguides 106, 107, 1010, 109 that directly split light from the lower branch 1012, wherein the upper branch 1011 serves as the main straight waveguide for the branch waveguides 102, 103, 104, 105, and the lower branch 1012 serves as the main straight waveguide for the branch waveguides 106, 107, 1010, 109.

[0111] In order to obtain a 2x10 non-equally divided structure of 35%:35%:3.75%:3.75%:3.75%:3.75%:3.75%:3.75%:3.75%:3.75%, the splitting ratio of the equally divided structure 101 is 50%. In this embodiment, since the splitting ratio of the equally divided structure 101 is 50%, the formula 1 Y=(X / P) / [1-(X / P)] n-1 , 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.

[0112] Since 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. Therefore, the structure has the characteristics of good insertion loss consistency and easy optimization design.

[0113] The specific structure of the light splitting structure is referred to in Example 1 and will not be further described here.

[0114] 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 protection scope of the present invention.

Claims

1. A light splitting structure, It is 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, It is 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, It is 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, It is 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, It is 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 4, It is 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.

7. A method for manufacturing a light splitting structure, It is characterized in that The manufacturing method is used to manufacture the light splitting structure according to any one of claims 1 to 6, 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.

8. The method for manufacturing the light splitting structure according to claim 7, It is 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.

9. The method for manufacturing the light splitting structure according to claim 7, It is 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; The branching angle and the branching offset distance corresponding to the branching waveguide are obtained respectively according to the splitting ratio of the branching waveguide, the first relationship and the second relationship.

10. The method for manufacturing the light splitting structure according to claim 9, It is 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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