Optical waveguide, optical waveguide construction method and communication equipment

Abstract

According to the optical waveguide, the optical waveguide construction method and the communication equipment provided by the embodiment of the invention, the middle bending section and the side bending section of the optical waveguide are constructed in a segmented manner, and the middle lines corresponding to the middle bending section and the side bending section are fitted in a segmented manner, so that the optical waveguide has relatively high degree of freedom and flexibility; the bending shape can be more accurately controlled, so that the bent waveguide with smaller size and lower insertion loss can be obtained; moreover, the side edge center line of the side edge bending section adopts related parameters of the middle center line in the fitting process, and the middle center line and the side edge center line are simultaneously subjected to nonlinear fitting, so that the joint of the middle center line and the side edge center line is more continuous and smoother, and the insertion loss of the optical waveguide caused by mode mismatch can be better reduced.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of optical communication, and in particular, to an optical waveguide, a method for constructing an optical waveguide, and a communication device. Background Art

[0002] With the continuous development of photon integrated chip technology and the gradual popularization of commercial applications, photon integrated chips are widely used in various fields, including optical modulation, optical detection, optical sensing, optical computing, etc. In the above application scenarios, the transformation of the optical field transmission direction needs to rely on an optical waveguide.

[0003] In the related art, the commonly used waveguide bending shape is a circular ring type, whose waveguide center line is an arc, and the waveguide width remains the same at each point. The design process and layout drawing of this structure are relatively simple, but the curvature radii of the arc and the straight line are discontinuous, which will lead to mode mismatch and increase the insertion loss. How to reduce the insertion loss caused by mode mismatch is an urgent problem to be discussed and solved. Summary of the Invention

[0004] The embodiments of the present application provide an optical waveguide, a method for constructing an optical waveguide, and a communication device, aiming to reduce the insertion loss of the optical waveguide caused by mode mismatch.

[0005] In a first aspect, the embodiments of the present application provide an optical waveguide, which includes: a first side bending section, a second side bending section, and an intermediate bending section located between the first side bending section and the second side bending section; wherein, the first side bending section has a first side center line, the second side bending section has a second side center line, the intermediate bending section has an intermediate center line, and the second side center line and the first side center line are in a mirror image relationship; the intermediate center line is obtained by fitting a preset intermediate center line according to intermediate center line parameters, the first side center line is obtained by fitting the preset side center line of the first side bending section according to the intermediate center line parameters, connection coordinates, and a first non-linear fitting function, and the intermediate center line and the first side center line satisfy a preset condition; wherein, the intermediate center line parameters are parameters characterizing the curve geometric features of the intermediate center line, and the connection coordinates include the coordinates characterizing the connection between the intermediate center line and the first side center line; the preset condition includes: at the connection between the intermediate center line and the first side center line, the intermediate center line and the first side center line are continuous, and the first derivative and the second derivative of the intermediate center line and the first derivative and the second derivative of the first side center line are continuous.

[0006] In a second aspect, an embodiment of the present application provides a method for constructing an optical waveguide. The optical waveguide includes: a first side bending section, a second side bending section, and an intermediate bending section located between the first side bending section and the second side bending section. Wherein, the first side bending section has a first side center line, the second side bending section has a second side center line, and the intermediate bending section has an intermediate center line;

[0007] The method includes: fitting a preset intermediate center line according to intermediate center line parameters to obtain the fitted intermediate center line. The intermediate center line parameters are parameters characterizing the curve geometric features of the intermediate center line; fitting the preset side center line of the first side bending section according to the intermediate center line parameters, connection coordinates, and a first non-linear fitting function to obtain the fitted first side center line and the second side center line of the second side bending section that is a mirror image of the first side bending section. Wherein, the connection coordinates include the coordinates characterizing the connection between the intermediate center line and the first side center line. The intermediate center line and the first side center line satisfy a preset condition. The preset condition includes: at the connection of the intermediate center line and the first side center line, the intermediate center line and the first side center line are continuous, and the first-order derivative and second-order derivative of the intermediate center line and the first-order derivative and second-order derivative of the first side center line are all continuous; constructing the optical waveguide according to the intermediate center line, the first side center line, and the second side center line.

[0008] In the solution of the embodiment of the present application, by segmentally constructing the intermediate bending section and the side bending section of the optical waveguide and segmentally fitting the intermediate lines corresponding to the intermediate bending section and the side bending section, it has a high degree of freedom and flexibility, can more precisely control the bending shape, and thus can obtain a bending waveguide with smaller size and lower insertion loss; moreover, the side center line of the side bending section adopts relevant parameters of the intermediate center line during the fitting process, and the intermediate center line and the side center line are jointly non-linearly fitted, so that the connection between the intermediate center line and the side center line is more continuous and smooth, and can better reduce the insertion loss caused by mode mismatch of the optical waveguide. Description of the Drawings

[0009] Figure 1 It is a schematic structural diagram of an optical waveguide provided by an embodiment of the present application;

[0010] Figure 2 It is a schematic flow diagram of a method for constructing an optical waveguide provided by an embodiment of the present application;

[0011] Figure 3 It is a schematic diagram of the coordinate position of the optical waveguide during the construction of the optical waveguide provided by an embodiment of the present application;

[0012] Figure 4 Schematic illustration of the intermediate center line, the first side center line, and the second side center line in the coordinate axes provided by an embodiment of the present application;

[0013] Figure 5 Schematic diagram of the shape of an optical waveguide provided by an example of the present application;

[0014] Figure 6 is Figure 5 simulation result of the bending of the optical waveguide shown;

[0015] Figure 7 Schematic diagram of the shape of an optical waveguide provided by another example of the present application;

[0016] Figure 8 is Figure 7 simulation result of the bending of the optical waveguide shown. Detailed implementation manners

[0017] In order to make the objectives, technical solutions, and advantages of the present application clearer and more understandable, the present application 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 application and are not used to limit the present application.

[0018] It should be noted that although the functional modules are divided in the device schematic diagram and the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order from the module division in the device or the flowchart. Terms such as "first" and "second" in the description of the embodiments of the present application are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence.

[0019] In the description of the embodiments of the present application, unless otherwise clearly defined, words such as "set", "installed", and "connected" should be understood in a broad sense. Those skilled in the art can reasonably determine the specific meanings of the above words in the embodiments of the present application in combination with the specific content of the technical solution.

[0020] In the embodiments of the present application, words such as "furthermore", "exemplarily", or "optionally" are used to represent examples, illustrations, or explanations, and should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Using words such as "furthermore", "exemplarily", or "optionally" is intended to present relevant concepts in a specific manner.

[0021] In the related art, with the continuous development of photon integrated chip technology and the gradual popularization of commercial use, photon integrated chips are widely used in various fields, including optical modulation, optical detection, optical sensing, optical computing, etc. In the above application scenarios, it is necessary to rely on optical waveguides to realize the transformation of the optical field transmission direction.

[0022] In the related art, the commonly used waveguide bending shape is a circular ring, the center line of the waveguide is a circular arc, and the waveguide width is consistent at all points. The design process and layout drawing of this structure are relatively simple, but the curvature radius of the arc and the straight line is discontinuous, which will lead to mode mismatch and increase the insertion loss; in addition, in order to suppress the excitation of high-order modes in the curved waveguide in the short wavelength band, the waveguide width cannot be too wide, but the reduction of the waveguide width will lead to increased radiation loss in the long wavelength band, so it is difficult to meet the low insertion requirements within a larger band range. How to reduce the insertion loss caused by mode mismatch is an issue that needs to be discussed and solved urgently.

[0023] Based on this, the embodiments of the present application provide an optical waveguide, an optical waveguide construction method and a communication device. The optical waveguide structure of the present application consists of a middle curved waveguide and two side curved waveguides. The middle curved segment and the side curved segment of the optical waveguide are constructed in segments, and different nonlinear functions are used to fit the middle lines corresponding to the middle curved segment and the side curved segment in segments. The angle ratio occupied by the middle curved segment and the side curved segment is adjusted according to actual needs, with high degrees of freedom and flexibility, and the bending shape can be more accurately controlled, so that a curved waveguide with a smaller size and lower insertion loss can be obtained; and the side center line of the side curved segment adopts the relevant parameters of the middle center line in the fitting process, and the middle center line and the side center line are jointly nonlinearly fitted, so that the connection between the middle center line and the side center line is more continuous and smooth, and has lower insertion loss than a single circular bending at the same bending radius, which can better reduce the insertion loss of the optical waveguide caused by mode mismatch.

[0024] The optical waveguide, optical waveguide construction method, and communication device provided by the embodiments of the present application also obtain the first width of the side bending section of the gradually changing optical waveguide through fitting with a second non-linear function. The corresponding first width of the side bending section changes non-linearly with the length or bending angle of the side bending section. The first width gradually becomes wider from one end of the side bending section far from the middle bending section to the end connected to the middle bending section. The waveguide width of the middle bending section is the same as the maximum width of the side bending section and remains unchanged. For the optical waveguide optimized by the optical waveguide construction method of the present application, the connection between the middle bending section and the side bending section is smoother than that of a conventional waveguide with linearly changing width, thereby further reducing the insertion loss, and the width change can be achieved within a shorter distance while maintaining the adiabatic transmission of the optical field, improving the compactness. In addition, at both ends of the optical waveguide of the present application, that is, at the ends of the two side bending sections far from the middle bending section, the width is smaller, which can serve as the light input section and light output section of the optical waveguide, suppressing the excitation of high-order modes in the bent waveguide in the short wavelength band. Moreover, the second width of the middle bending section is larger than the widths of the light input end and the light output end of the optical waveguide, thereby enhancing the confinement ability of the optical field, reducing the radiation loss, and at the same time, the optical field is more concentrated inside the waveguide, reducing the scattering loss caused by the unevenness of the waveguide sidewall.

[0025] The embodiments of the present application will be further described below with reference to the accompanying drawings.

[0026] Figure 1 FIG. is a schematic structural diagram of an optical waveguide provided by an embodiment of the present application. In Figure 1 the embodiment, the optical waveguide at least includes a first side bending section, a second side bending section, and a middle bending section located between the first side bending section and the second side bending section.

[0027] Among them, the first side bending section has a first side center line, the second side bending section has a second side center line, the middle bending section has a middle center line, and the second side center line is in a mirror image relationship with the first side center line; the middle center line is obtained by fitting a preset middle center line according to the middle center line parameters, the first side center line is obtained by fitting the preset side center line of the first side bending section according to the middle center line parameters, the connection coordinates, and a first non-linear fitting function, and the middle center line and the first side center line satisfy a preset condition; wherein, the middle center line parameters are parameters characterizing the curve geometric features of the middle center line, and the connection coordinates include the coordinates characterizing the connection between the middle center line and the first side center line; the preset conditions include: at the connection between the middle center line and the first side center line, the middle center line and the first side center line are continuous, and the first-order derivative, second-order derivative of the middle center line, and the first-order derivative, second-order derivative of the first side center line are all continuous.

[0028] Among them, the middle center line of the middle bending section is an arc or a Bessel curve, and the shapes of the first side center line and the second side center line are both fitted by the Euler function or the Bessel function. It should be noted that the first side center line and the second side center line can be separately fitted by the Euler function or the Bessel function, or after one of the side center lines is fitted by the Euler function or the Bessel function, the other side center line can be obtained by mirroring.

[0029] Among them, the waveguides of the middle bending section, the first side bending section and the second side bending section are all single-mode waveguides.

[0030] Such as Figure 1 As shown, the optical waveguide of the present application is a bent waveguide composed of two side bending sections and one middle bending section. The middle bending section corresponds to Figure 1 the dotted line part of the optical waveguide shown. Correspondingly, Figure 1 the center line of the middle bending section shown is the middle center line; the side bending section on the left side of the middle bending section is the first side bending section. Correspondingly, Figure 1 the center line of the first side bending section shown is the first side center line; the side bending section on the right side of the middle bending section is the second side bending section. Correspondingly, Figure 1 the center line of the second side bending section shown is the second side center line. The bent waveguide formed by the middle bending section, the first side bending section and the second side bending section is symmetric about the mirror image as a whole.

[0031] Exemplarily, such as Figure 1 shown, the bending radius of the optical waveguide is R (R>1.5um), the bending angle is θ (0°<θ<360°), the two side bending sections are mirror symmetric, and the bending angle of the middle bending section is θ c (θ c ≤θ), the width of the input and output ends of the bent waveguide is W i , the width of the middle bending section is W C , and the distance from the outer edge of the middle bending section to the center line is W b .

[0032] The optical waveguide structure of the present application is composed of one middle bent waveguide and two side bent waveguides at both ends. By segmentally constructing the middle bending section and the side bending sections of the optical waveguide, different nonlinear functions are used to segmentally fit the center lines corresponding to the middle bending section and the side bending sections. The angle ratios occupied by the middle bending section and the side bending sections are adjusted according to actual needs, with high degrees of freedom and flexibility, and can more precisely control the bending shape, so that a bent waveguide with smaller size and lower insertion loss can be obtained.

[0033] In one embodiment, the widths of the first side bending section and the second side bending section both gradually decrease from one end close to the middle bending section to the other end away from the middle bending section, and the widths at various positions of the first side bending section and the second side bending section are determined according to the side center line and the second non-linear fitting function.

[0034] As Figure 1 shown, the widths of the ends of the first side bending section and the second side bending section away from the middle bending section are the narrowest, with a width of W i ; the widths of the ends of the first side bending section and the second side bending section connected to the middle bending section are the widest, with a width of W C .

[0035] Among them, the second non-linear fitting function may include, but is not limited to, exponential functions, logarithmic functions, trigonometric functions, Bessel functions, etc. or a combination of several non-linear functions. Further, the midpoint of the connection line between the inner and outer edges of the waveguide after the width change may have a certain offset from the waveguide center line.

[0036] The first width of the side bending section of the gradually varying optical waveguide is obtained by fitting with the second non-linear function. The corresponding first width of the side bending section varies non-linearly with the length or bending angle of the side bending section. The first width gradually increases from the end of the side bending section away from the middle bending section to the end connected to the middle bending section. The waveguide width of the middle bending section is the same as the maximum width of the side bending section and remains unchanged. For the optical waveguide optimized by the optical waveguide construction method of the present application, the connection between the middle bending section and the side bending section is smoother than that of a conventional waveguide with linearly varying width, thereby further reducing the insertion loss, and the width change can be achieved within a shorter distance while maintaining the adiabatic transmission of the optical field, improving the compactness.

[0037] In one embodiment, the widths at various positions of the middle bending section remain unchanged, and the widths of one ends of the first side bending section and the second side bending section close to the middle bending section are both equal to the width of the middle bending section. As Figure 1 shown, the width of the middle bending section is equal to the widths of the widest parts of the first side bending section and the second side bending section, both being W C . The width of the middle bending section is the maximum width of the optical waveguide and remains unchanged, so that the width of the middle part of the optical waveguide is relatively increased, thereby enhancing the confinement ability of the optical field, reducing the radiation loss, and at the same time, the optical field is more concentrated inside the waveguide, reducing the scattering loss caused by the unevenness of the waveguide sidewall.

[0038] In one embodiment, the material of the optical waveguide includes, but is not limited to, silicon on insulator, lithium niobate, silicon nitride, indium phosphide, or gallium arsenide.

[0039] It should be noted that the specific implementation details and effects of the optimization of the intermediate bending section, the first side bending section, and the second side bending section of the optical waveguide in this application are all reflected in the description of the optical waveguide construction method in the following embodiments of this application, and will not be elaborated here.

[0040] Figure 2 FIG. is a schematic flow chart of an optical waveguide construction method provided by an embodiment of this application. As Figure 2 shown, this optical waveguide construction method is used to construct the optical waveguides provided in the above embodiments of this application. The optical waveguide includes: a first side bending section, a second side bending section, and an intermediate bending section located between the first side bending section and the second side bending section. Among them, the first side bending section has a first side center line, the second side bending section has a second side center line, and the intermediate bending section has an intermediate center line.

[0041] In Figure 2 the embodiment of, this optical waveguide construction method may include, but is not limited to, step S1100, step S1200, and step S1300.

[0042] Step S1100: Fit a preset intermediate center line according to the intermediate center line parameters, where the intermediate center line parameters are parameters characterizing the curve geometric features of the intermediate center line, to obtain a fitted intermediate center line;

[0043] Step S1200: Fit the preset side center line of the first side bending section according to the intermediate center line parameters, the connection coordinates, and the first non-linear fitting function to obtain a fitted first side center line, and the second side center line of the second side bending section that is mirror-symmetrical to the first side bending section;

[0044] Among them, the connection coordinates include the coordinates characterizing the connection between the intermediate center line and the first side center line. The intermediate center line and the first side center line satisfy preset conditions, and the preset conditions include: at the connection between the intermediate center line and the first side center line, the intermediate center line and the first side center line are continuous, and the first derivative, second derivative of the intermediate center line, and the first derivative, second derivative of the first side center line are all continuous;

[0045] Step S1300: Construct an optical waveguide according to the intermediate center line, the first side center line, and the second side center line.

[0046] Among them, in step S1100, the intermediate centerline parameters refer to the parameters characterizing the curve geometric features of the intermediate centerline. Exemplarily, such as the bending angle and bending radius of the intermediate centerline, and the coordinates at various positions of the intermediate centerline, such as the coordinates of the two ends where the intermediate centerline is connected to the two side centerlines, and so on. The preset intermediate centerline refers to the intermediate centerline in the initial state to be fitted and optimized, which can be a non-linear function or preset geometric parameters, such as bending angle, bending radius, length, etc.

[0047] In step S1200, the connection coordinates refer to the coordinates characterizing the connection between the intermediate centerline and the first side centerline and / or the coordinates characterizing the connection between the intermediate centerline and the second side centerline. Further, when it is necessary to fit and optimize the preset side centerline of the first side bending section, the connection coordinates are the coordinates characterizing the connection between the intermediate centerline and the first side centerline; when it is necessary to fit and optimize the preset side centerline of the second side bending section, the connection coordinates are the coordinates characterizing the connection between the intermediate centerline and the second side centerline. The first non-linear fitting function refers to the type of non-linear function. Exemplarily, in this application, the first non-linear fitting function can be the Euler function or the Bessel function. Correspondingly, the preset side centerlines of the two side bending sections refer to the initial side centerlines that have not been fitted and optimized, which can be represented by the Euler function or the Bessel function. Correspondingly, fitting the preset side centerline of the first side bending section according to the intermediate centerline parameters, connection coordinates, and the first non-linear fitting function means using the intermediate centerline parameters and connection coordinates as input parameters and using the first non-linear function as the preset side centerline of the first side bending section to fit the preset side centerline.

[0048] At the connection between the intermediate centerline and the first side centerline, the continuity of the intermediate centerline and the first side centerline means that the values of the functions corresponding to the fitted intermediate centerline and the first side centerline are equal at the connection point; the continuity of the first-order derivative and second-order derivative of the intermediate centerline and the first-order derivative and second-order derivative of the first side centerline means that the values of the first-order derivative of the function corresponding to the intermediate centerline and the first-order derivative of the function corresponding to the first side centerline are equal at the connection point, and the values of the second-order derivative of the function corresponding to the centerline and the second-order derivative of the function corresponding to the first side centerline are also equal at the connection point. Further, since the second side bending section and the first side bending section are mirror images, the intermediate centerline and the second side centerline can also meet the preset conditions.

[0049] In step S1300, after optimizing and fitting to obtain the intermediate centerline, the first side centerline, and the second side centerline, the shapes of each section of the optical waveguide can be obtained according to each centerline.

[0050] The optical waveguide construction method of this embodiment segments the middle bending section and the side bending section of the optical waveguide, and uses different non-linear functions to segmentally fit the middle lines corresponding to the middle bending section and the side bending section. The angular ratios occupied by the middle bending section and the side bending section are adjusted according to actual needs, with high degrees of freedom and flexibility, enabling more precise control of the bending shape, so that a bent optical waveguide with smaller size and lower insertion loss can be obtained. Moreover, according to this method, the middle center line, the first side center line, and the second side center line can all meet the preset conditions, ensuring that the connections of the middle center line, the first side center line, and the second side center line are continuous and smooth, effectively avoiding radiation caused by mode mismatch and excessive bending at the connections, and reducing the insertion loss.

[0051] In one embodiment, Figure 3 is a schematic diagram of the coordinate positions of the optical waveguide during the construction of the optical waveguide provided by an embodiment of this application. As Figure 3 shown, the starting point of the first side center line, that is, the end point of the first side center line far from the middle center line, is located at the origin of the coordinate axis; the direction of the port of the first side bending section far from the middle bending section faces the negative x-axis direction.

[0052] Figure 4 is a schematic diagram of the middle center line, the first side center line, and the second side center line in the coordinate axis provided by an embodiment of this application. As Figure 4 shown, Figure 4 the coordinate axis in Figure 3 is the same coordinate axis as that in Figure 4 and each section of the center line in Figure 2 corresponds to each section of the center line of the optical waveguide shown in Figure 2 , Figure 3 . It should be noted that in each embodiment of this application, the coordinate system referred to during the construction of the optical waveguide takes

[0053] as an example and will not be repeated here.

[0053] In one embodiment, after obtaining the fitted first side center line, the method includes:

[0054] Fitting the preset side center line of the second side bending section according to the middle center line parameters, the connection coordinates, and the first non-linear fitting function to obtain the fitted second side center line, where the connection coordinates include the coordinates representing the connection of the middle center line and the second side center line;

[0055] Or,

[0056] Mirroring the first side center line to obtain the second side center line.

[0057] Among them, the process of obtaining the second side center line is the same as that of the first side center line. The second side center line can be obtained by fitting the preset side center line of the second side bending section according to the middle center line parameters, the connection coordinates, and the first non-linear fitting function. At this time, the second side center line and the first side center line are still mirror images; it can also be obtained by mirroring the first side center line. Specifically, the method of obtaining the second side center line by mirroring the first side center line can save computing resources, reduce the computational complexity, and improve the efficiency of optical waveguide construction.

[0058] In one embodiment, fitting the preset middle center line according to the middle center line parameters includes:

[0059] Fitting the preset middle center line according to one of the preset arc angle and the preset arc radius;

[0060] Or,

[0061] Fitting the preset middle center line through the first Bessel function, where the first Bessel function is determined by the first coordinate, the second coordinate, and at least one first control point coordinate. The first coordinate is the coordinate of the connection between the middle center line and the first side center line, and the second coordinate is the coordinate of the connection between the middle center line and the second side center line. Among them, the first control point coordinate is the coordinate of the middle part of the middle center line selected according to requirements.

[0062] In one embodiment, in the case of fitting the preset middle center line according to one of the preset arc angle and the preset arc radius, the first non-linear fitting function is one of the Euler function and the second Bessel function;

[0063] In the case of fitting the preset middle center line through the first Bessel function, the first non-linear function is the Euler function.

[0064] In one embodiment, whether to select the arc scheme optimization fitting or the first Bessel function scheme for fitting the middle center line is determined according to the specific scenario requirements. Similarly, which first non-linear function to select for the first side center line and the second side center line is also determined according to the specific scenario requirements; it should be noted that the non-linear fitting functions selected for the middle center line and the first side center line / second side center line cannot be the same. Exemplarily, in the actual scenario, the three schemes of "arc + Euler function", "arc + second Bessel function", and "first Bessel function + Euler function" can be used to construct optical waveguides respectively, and then the three optical waveguides are detected respectively, and the optical waveguide with the best performance is selected.

[0065] Exemplarily, the shape of the middle center line of the middle bending section can be obtained by the following two methods:

[0066] 1) Arc: The middle center line of the middle curved section is an arc with an angle of θ c , and the radius is R c . Further, the middle curved section is determined by one of the preset angles or radii, and the shape of the final middle center line is obtained by subsequent joint calculation with the first side center line of the first side curved section.

[0067] 2) First Bessel function:

[0068] Use the first Bessel function to fit the shape of the middle center line of the middle curved section. Determine the function shape through 3 or more control points. Use the optimization algorithm to iteratively optimize the control parameters to complete the optimized construction of the middle center line shape. In this example, the first Bessel function is a quadratic Bessel function.

[0069] x b1 =(1 - t 1 ) 2 ×A 1 (1,1)+2(1 - t 1 )t 1 ×A 1 (2,1)+t 1 2 ×A 1 (3,1)

[0070] y b1 =(1 - t 1 ) 2 ×A 1 (1,2)+2(1 - t 1 )t 1 ×A 1 (2,2)+t 1 2 ×A 1 (3,2)

[0071] t 1 ∈[0,1]

[0072]

[0073] Among them, x b1 and y b1 respectively represent the horizontal and vertical coordinates at different positions of the middle center line of the middle curved section, A 1 is the control point matrix, and each row of A 1 corresponds to a control point coordinate, and (x1, y1) is the first control point coordinate. When t 1 =0, x b1 (0)=A 1 (1,1)=x connect_l , y b1 (0)=A1 (1, 2) = y connect_l , corresponding to the coordinates (x connect_l , y connect_l ) of the connection between the first side bending section and the middle bending section, that is, the first coordinate; when t 1 = 1, x b1 (1) = A 1 (3, 1) = x connect_r , y b1 (1) = A 1 (3, 2) = y connect_r , corresponding to the coordinates (x connect_r , y connect_r ) of the connection between the second side bending section and the middle bending section, that is, the second coordinate.

[0074] Exemplarily, in the case where the shape of the middle center line adopts an arc scheme, the first side center line adopting a first non-linear function can be an Euler function or a Bessel function. At this time, the specific scheme of fitting the shape of the first side center line with the Euler function is as follows:

[0075] The horizontal and vertical coordinates of the first side center line respectively satisfy:

[0076]

[0077]

[0078] In the formula, k is a proportionality coefficient, x is a real number greater than 0, and t 2 ∈[0, ∞). After the shape of the middle center line is given, the middle center line and the first side center line need to meet preset conditions, that is, at the connection of the middle center line and the first side center line, the middle center line and the first side center line are continuous, and the first derivative, second derivative of the middle center line and the first derivative, second derivative of the first side center line are all continuous.

[0079] According to the geometric relationship of the shape of the optical waveguide composed of the middle center line and the first side center line, it can be obtained that:

[0080]

[0081] At this time, by determining the bending radius R c of the middle bending section, the shapes of the middle center line and the first side center line under any bending radius R and bending angle θ can be obtained. Then, by mirroring the first side center line, the second side center line is obtained, thereby obtaining the shapes of the center lines of each section of the optical waveguide.

[0082] Exemplarily, in the case where the shape of the middle center line adopts the solution of the first Bessel function, the first side center line adopts the first nonlinear function as the Euler function. At this time, the solution of fitting the shape of the first side center line using the Euler function is as follows: according to the geometric relationship of the shape of the optical waveguide composed of the middle center line and the first side center line, the first Bessel function corresponding to the middle center line and the Euler function corresponding to the first side center line are combined to obtain:

[0083]

[0084]

[0085] At this time, determine the bending angle θ of the middle center line c , the shapes of the middle center line and the first side center line under any bending radius R and bending angle θ can be obtained. Then, the second side center line is obtained by mirroring the first side center line, thereby obtaining the shapes of the center lines of each section of the optical waveguide.

[0086] Exemplarily, when the shape of the middle center line adopts an arc solution, the first nonlinear function adopted by the first side center line may be an Euler function or a Bessel function. At this time, the solution of fitting the shape of the first side center line using the Bessel function is as follows:

[0087] Use the Bessel function to fit the shape of the centerline of the first side. Determine the function shape through 4 or more control points. Use the optimization algorithm to iteratively optimize the control parameters to complete the optimization design of the centerline shape of the side bending segment. In this example, the cubic Bessel function is used to fit the bending shape of the centerline of the first side.

[0088] x b2 =(1-t 3 ) 3 ×A 2 (1,1)+3(1-t 3 ) 2 t 3 ×A 2 (2,1)+3(1-t 3 )t 3 2 ×A 2 (3,1)+t 3 3 ×A 2 (4,1)

[0089] y b2 =(1-t 3 ) 3 ×A 2 (1,2)+3(1-t 3 ) 2t 3 ×A 2 (2,2)+3(1 - t 3 )t 3 2 ×A 2 (3,2)+t 3 3 ×A 2 (4,2)

[0090] t 3 ∈[0,1]

[0091]

[0092] where x b2 and y b2 respectively represent the abscissa and ordinate at different positions on the center line of the first side, A 2 is the control point matrix, each row of A 2 corresponds to a control point coordinate, (x2, y2) and (x3, y3) are two variable control points. When t 3 = 0, x b2 (0) = A 2 (1,1) = 0, y b2 (0) = A 2 (1,2) = 0, corresponding to the starting point (0,0) of the center line of the first side; when t 3 = 1, x b2 (1) = A 2 (4,1) = x connect , y b2 (1) = A 2 (4,2) = y connect , corresponding to the coordinate (x connect , y connect ) of the end where the center line of the first side is connected to the middle center line.

[0093] According to the geometric relationship of the shape of the optical waveguide formed by the middle center line and the first side center line, it can be obtained that:

[0094]

[0095] θ c is the bending angle of the middle center line, θ e is the bending angle of the first side center line, R c is the arc radius of the middle center line. At this time, the coordinate of the connection point between the middle center line and the first side center line is determined as [A 2 (4,1), A 2(4,2)], the shapes of the middle centerline and the first side centerline at any bending radius R and bending angle θ can be obtained. Then, by mirroring the first side centerline, the second side centerline is obtained, thereby obtaining the shapes of the centerlines of each segment of the optical waveguide.

[0096] In one embodiment, step S1300 includes:

[0097] According to the first side centerline, determine the first width at each position in the first side bending section and the second side bending section, and the second width of the middle bending section;

[0098] According to the middle centerline, the first side centerline, and the second side centerline, determine the first distance, the second distance, and the third distance. Among them, the first distance includes the distances between the respective positions of the target edges of the first side bending section and the corresponding positions of the first side centerline, the second distance includes the distances between the respective positions of the target edges of the second side bending section and the corresponding positions of the second side centerline, and the third distance includes the distance between the target edge of the middle bending section and the middle centerline;

[0099] Construct an optical waveguide according to the first width, the second width, the first distance, the second distance, and the third distance.

[0100] In one embodiment, determining the first width at each position in the first side bending section and the second side bending section, and the second width of the middle bending section according to the first side centerline includes:

[0101] According to the first side centerline and the second non-linear fitting function, determine the first width at each position in the first side bending section and the second side bending section. Among them, the first widths of the first side bending section and the second side bending section both gradually decrease from the end close to the middle bending section to the end far from the middle bending section, and the first widths of the ends of the first side bending section and the second side bending section close to the middle bending section are the same;

[0102] Determine the first width of the end of the first side bending section close to the middle bending section as the second width, where the width at each position in the middle bending section remains unchanged. It should be noted that the second width of the middle bending section is determined by the first width of the end of the first side bending section close to the middle bending section. The second width will change with the change of the fitted first width, but after determining the second width, the width at each position in the middle bending section remains unchanged and is all the second width.

[0103] In one embodiment, determining the widths at each position in the first side bending section and the second side bending section according to the first side centerline and the second non-linear fitting function includes:

[0104] Determine the first width at each position in the first side bending section according to the first side center line and the second non-linear fitting function, and determine the first width at each position in the second side bending section according to the second side center line and the second non-linear fitting function;

[0105] Or, determine the first width at each position in the first side bending section according to the first side center line and the second non-linear fitting function, and obtain the first width at each position in the second side bending section by mirroring.

[0106] Exemplarily, the waveguide width of the first side bending section changes non-linearly with the length passed from left to right or the bending angle of the bending section, and the change can be fitted by an exponential function, a logarithmic function, a trigonometric function, a Bessel function, etc. or a combination of the above several non-linear functions.

[0107] In this example, the first width W at each position of the first side bending section is fitted by a trigonometric function and a cubic Bessel curve respectively v Compared with the linear change of the width, the edge at the connection is smoother, so better performance can be achieved.

[0108] 1) Trigonometric function:

[0109]

[0110] Among them, S is the cumulative length at each position of the first side center line or the angle turned by the bend, a is a real number greater than 0, and by optimizing a, the change mode of the first width of the first side center line is changed. Specifically, after obtaining the shape of the first side center line by fitting the optical waveguide construction method provided in the above embodiment, the length at each position of the first side center line or the angle turned by the bend can be determined. After fitting the first width W at each position of the first side bending section v After that, by mirroring the first side bending section, the first width at each position of the second side bending section is obtained.

[0111] 2) Bessel function:

[0112] Use the Bessel function to fit the relationship between the width change and the cumulative length or bending angle at each position of the first side center line, and determine the width of the first side bending section corresponding to the cumulative length or bending angle at different positions of the first side center line through 4 or more control points. Use an optimization algorithm to iteratively optimize the control parameters to complete the optimized design of the waveguide width change mode. In this example, the cubic Bessel function is used to fit the change of the first width at each position of the first side bending section with the cumulative length at each position of the first side center line.

[0113] P=(1 - t 5 ) 3 ×A3 (1,1) + 3(1 - t 5 ) 2 t 5 × A 3 (2,1) + 3(1 - t 5 )t 5 2 × A 3 (3,1) + t 5 3 × A 3 (4,1)

[0114] W v =(1 - t 5 ) 3 × A 3 (1,2) + 3(1 - t 5 ) 2 t 5 × A 3 (2,2) + 3(1 - t 5 )t 5 2 × A 3 (3,2) + t 5 3 × A 3 (4,2)

[0115] t 5 ∈ [0, 1]

[0116]

[0117] The above formula represents that the first width W at the position P of the first side bending section, where P represents different length positions or bending angle positions, and each row of A v corresponds to a control point coordinate. S is the cumulative length of the center line of the first side or the angle turned by bending. (x4, y4) and (x5, y5) are two variable control points. When t 3 = 0, P(0) = A 5 (1,1) = 0, Wv(0) = A 3 (1,2) = W 3 , corresponding to the end of the first side bending section far from the middle bending section, that is, the first width at the starting point is W i ; when t i = 1, P(1) = A 5 (4,1) = S, W 3 (1) = A v (4,2) = W 3 , corresponding to the first width at the connection of the first side bending section and the middle bending section is W c . c .

[0118] In one embodiment, determining the first distance and the second distance includes:

[0119] Performing linear fitting according to the side centerline parameters of the first side bending segment and the first starting distance to obtain the first distance between the respective positions of the target edge of the first side bending segment and the corresponding positions of the first side centerline, and obtaining the second distance between the respective positions of the target edge of the second bending segment that is a mirror image of the first side bending segment and the corresponding positions of the second side centerline, where the first starting distance is the distance between the target edge at the starting point of the first side bending segment and the first side centerline, and the starting point of the first side bending segment is the end of the first side bending segment that is far from the middle bending segment;

[0120] Wherein, the side centerline parameters of the first side bending segment are the bending angles and cumulative lengths of the respective positions of the first side centerline, and the target edge is the inner edge or the outer edge.

[0121] In one embodiment, after obtaining the first distance between the respective positions of the target edge of the first side bending segment and the corresponding positions of the first side centerline, one of the following is included:

[0122] Performing linear fitting according to the side centerline parameters of the second side bending segment and the second starting distance to obtain the second distance between the respective positions of the target edge of the second side bending segment and the corresponding positions of the second side centerline, where the side centerline parameters of the second side bending segment are the bending angles and cumulative lengths of the respective positions of the second side centerline, and the second starting distance is the distance between the target edge at the starting point of the second side bending segment and the second side centerline, and the starting point of the second side bending segment is the end of the second side bending segment that is far from the middle bending segment;

[0123] Or,

[0124] Mirroring the first distance between the respective positions of the target edge of the first side bending segment and the corresponding positions of the first side centerline to obtain the second distance between the respective positions of the target edge of the second bending segment and the corresponding positions of the second side centerline.

[0125] In one embodiment, determining the first distance and the second distance includes:

[0126] According to the side center line parameters of the first side bending section and the third starting point distance for linear fitting, the first distance between the midpoint of the connection line of the inner and outer edges at each position of the first side bending section and the corresponding position of the first side center line is obtained, and the second distance between the midpoint of the connection line of the inner and outer edges at each position of the second bending section that is mirror - imaged with respect to the first side bending section and the corresponding position of the second side center line is obtained. Among them, the third starting point distance is the distance between the midpoint of the connection line of the inner and outer edges at the starting point of the first side bending section and the first side center line. The starting point of the first side bending section is the end of the first side bending section far from the middle bending section;

[0127] Among them, the side center line parameters of the first side bending section are the bending angles and cumulative lengths of each position of the first side center line.

[0128] In one embodiment, after obtaining the first distance between the midpoint of the connection line of the inner and outer edges at each position of the first side bending section and the corresponding position of the first side center line, it includes one of the following:

[0129] According to the side center line parameters of the second side bending section and the fourth starting point distance for linear fitting, the second distance between the midpoint of the connection line of the inner and outer edges at each position of the second side bending section and the corresponding position of the second side center line is obtained. Among them, the side center line parameters of the second side bending section are the bending angles and cumulative lengths of each position of the second side center line, and the fourth starting point distance is the distance between the midpoint of the connection line of the inner and outer edges at the starting point of the second side bending section and the second side center line;

[0130] Or,

[0131] Mirror the first distance between the midpoint of the connection line of the inner and outer edges at each position of the first side bending section and the corresponding position of the first side center line to obtain the second distance between the midpoint of the connection line of the inner and outer edges at each position of the second side bending section and the corresponding position of the second side center line.

[0132] In one embodiment, the third distance, the first distance between the target edge at the end of the first side bending section close to the middle bending section and the first side center line, and the second distance between the target edge at the end of the second side bending section close to the middle bending section and the second side center line are all equal.

[0133] Exemplarily, as Figure 1 shown, the positions of the input port and output port of the optical waveguide, that is, the positions at the ports of the first side bending section far from the middle bending section and the ports of the second side bending section far from the middle bending section. The midpoint of the connection line of the inner and outer edges of the first side bending section is located on the first side center line, and the midpoint of the connection line of the inner and outer edges of the second side bending section is located on the second side center line. At this position, the distance between the midpoint of the connection line of the inner and outer edges of the first side bending section and the second side bending section to the inner and outer edges is both W i / 2, the midpoints of the connecting lines of the inner and outer edges at other positions may not be on the corresponding center lines.

[0134] As Figure 1 shown, at the connection of the first side bending section and the middle bending section, the distance from the outer edge of the first side bending section to the first side center line is W b .

[0135] The third distance from the outer edge of the middle bending section to the middle center line remains W b . The variation manner of the distance between the inner and outer edges of each position of the first side bending section to the corresponding position of the first side center line is as follows:

[0136] 1) The first distance between the outer edge of each position of the first side bending section and the corresponding position of the first side center line varies linearly with the cumulative length or bending angle of each position of the first side center line. Assume the linear function is Y = k 1 S + b, where S is the cumulative length or bending angle of each position of the first side center line, k 1 is the coefficient, and b is the distance from the outer edge at the starting position of the first bending section to the first side center line, b = W i / 2, and Y is the distance between the outer edge of each position of the required side bending section and the corresponding position of the first side center line.

[0137] 2) The distance between the inner edge of each position of the first side bending section and the corresponding position of the first side center line varies linearly with the cumulative length or bending angle of each position of the first side center line. Assume the linear function is Y = k 1 S + b, where S is the cumulative length or bending angle of each position of the first side center line, k 1 is the coefficient, and b is the distance from the inner edge at the starting position of the first bending section to the first side center line, b = W i / 2, and Y is the distance between the inner edge of each position of the required side bending section and the corresponding position of the first side center line.

[0138] 3) The distance between the midpoint of the connecting line of the inner and outer edges of each position of the first side bending section and the corresponding position of the first side center line varies linearly with the cumulative length or the angle of bending rotation of each position of the first side center line. Assume the linear function is Y = k 1 S + b, where S is the cumulative length or bending angle of each position of the first side center line, k 1 is the coefficient, and b is the distance from the midpoint of the connecting line of the inner and outer edges at the starting position of the first bending section to the first side center line, b = 0, and Y is the distance between the midpoint of the connecting line of the inner and outer edges of each position of the required side bending section and the corresponding position of the first side center line.

[0139] Specifically, since the second side bending section is a mirror image of the first side bending section, the distances from the inner and outer edges of the second side bending to the center line of the second side are the same as the distances from the inner and outer edges of the first side bending section to the center line of the first side.

[0140] Specifically, after obtaining the distances between the inner and outer edges at various positions of the first side bending section and the corresponding positions of the center line of the first side, the position where the center line of the first side is set in the first side bending section can be determined. The same applies to the middle bending section and the second side bending section.

[0141] The embodiment of the present application also provides a communication device, which includes the optical waveguide provided in each of the above embodiments, or the optical waveguide obtained by the optical waveguide construction method provided in each of the above embodiments. It should be noted that the specific implementation details and beneficial effects of the optical waveguide included in this communication device can all be reflected in each of the above embodiments and will not be elaborated here.

[0142] The following specifically describes the optical waveguide and the optical waveguide construction method of the present application through examples. It can be understood that the following embodiments are all for further fully explaining the optical waveguide and the optical waveguide construction method of the present application and are not specifically limited.

[0143] Example 1:

[0144] Figure 5 It is a schematic diagram of the shape of the optical waveguide provided in an example of the present application. As Figure 5 shown, this optical waveguide is a bent waveguide with a bending radius of 3 um optimized according to the optical waveguide construction method provided in each of the above embodiments. The waveguide material is silicon, the upper and lower claddings are silicon dioxide, the bending angle is 90°, the waveguide width at the input and output ends is 0.5 um, the center lines of the two side bending sections are fitted with Euler's function, the center line of the middle bending section is fitted with a quadratic Bezier function, the waveguide width changes to 0.55 um and is fitted with trigonometric functions to the lengths of the center lines of each section. The distances between the midpoints of the connecting lines of the inner and outer edges at various positions of the two side bending sections and the corresponding positions of the corresponding side center lines change linearly with the angles turned by the center lines at various positions of the side center lines.

[0145] The working mode is as follows: The optimized bent waveguide shape reduces the loss due to mode mismatch. The increase in waveguide width improves the confinement of the optical field by the waveguide, reduces the radiation loss, and also reduces the scattering loss caused by the uneven sidewalls.

[0146] In this example, the optical waveguide is a strip waveguide, the waveguide height is 220 nm, and the upper and lower claddings are silicon dioxide. Figure 6 For Figure 5 the simulation result of the bending of the optical waveguide shown. As Figure 6As shown, the insertion loss of the fundamental mode is less than 0.005 dB in the wavelength band of 1.45 μm to 1.65 μm, and the insertion loss in the long wavelength band does not deteriorate significantly.

[0147] Example 2:

[0148] Figure 7 The schematic diagram of the shape of the optical waveguide provided for another example of this application. As Figure 7 shown, the optical waveguide is a bent waveguide with a bending radius of 3.5 μm optimized according to the optical waveguide construction method provided in the above embodiments. The waveguide material is silicon, the upper and lower claddings are silicon dioxide, the bending angle is 180°, the waveguide widths at the input and output ends are 0.5 μm, the side centerlines of the two side bent segments are fitted with a cubic Bézier function, the middle centerline of the middle bent segment is fitted with an arc, the waveguide width changes to 0.6 μm and is fitted with a cubic Bézier function to the centerline length, and the distance between the inner edge at each position of the two side bent segments and the corresponding position of the side centerline changes linearly with the cumulative length of each position of the side centerline.

[0149] The working mode is as follows: The optimized bent waveguide shape reduces the loss due to mode mismatch. The increase in waveguide width improves the confinement of the optical field by the waveguide, reduces the radiation loss, and also reduces the scattering loss caused by the uneven sidewalls.

[0150] In this example, the optical waveguide is a strip waveguide with a waveguide height of 220 nm, and the upper and lower claddings are silicon dioxide. Figure 8 For Figure 7 the simulation results of the bending of the optical waveguide shown. As Figure 8 shown, the insertion loss of the fundamental mode is less than 0.0025 dB in the wavelength band of 1.45 μm to 1.65 μm, and the insertion loss in the long wavelength band does not deteriorate significantly.

[0151] Some embodiments of this application have been described above with reference to the accompanying drawings. The scope of the rights of this application is not limited thereby. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the scope and essence of this application shall fall within the scope of the rights of this application.

Claims

1. An optical waveguide, the optical waveguide comprises: a first side bending section, a second side bending section, and an intermediate bending section located between the first side bending section and the second side bending section; wherein, the first side bending section has a first side center line, the second side bending section has a second side center line, the intermediate bending section has an intermediate center line, and the second side center line and the first side center line are in a mirror image relationship; the intermediate center line is obtained by fitting a preset intermediate center line according to intermediate center line parameters, the first side center line is obtained by fitting a preset side center line of the first side bending section according to the intermediate center line parameters, connection coordinates, and a first non-linear fitting function, and the intermediate center line and the first side center line satisfy a preset condition; wherein, the intermediate center line parameters are parameters characterizing the curve geometric features of the intermediate center line, the connection coordinates include the coordinates characterizing the connection between the intermediate center line and the first side center line; the preset condition includes: at the connection between the intermediate center line and the first side center line, the intermediate center line and the first side center line are continuous, and the first-order derivative and second-order derivative of the intermediate center line and the first-order derivative and second-order derivative of the first side center line are all continuous.

2. The optical waveguide according to claim 1, wherein, the widths of both the first side bending section and the second side bending section gradually decrease from one end close to the intermediate bending section to the end far from the intermediate bending section, and the widths at each position of the first side bending section and the second side bending section are determined according to the side center line and a second non-linear fitting function.

3. The optical waveguide according to claim 2, wherein, the widths at each position of the intermediate bending section remain unchanged, and the widths of one ends of the first side bending section and the second side bending section close to the intermediate bending section are both equal to the width of the intermediate bending section.

4. An optical waveguide construction method, the optical waveguide comprises: a first side bending section, a second side bending section, and an intermediate bending section located between the first side bending section and the second side bending section, wherein the first side bending section has a first side center line, the second side bending section has a second side center line, and the intermediate bending section has an intermediate center line; the method comprises: fitting a preset intermediate center line according to intermediate center line parameters to obtain the fitted intermediate center line, and the intermediate center line parameters are parameters characterizing the curve geometric features of the intermediate center line; Fitting the preset side center line of the first side bending section according to the middle center line parameters, the connection coordinates, and the first non-linear fitting function to obtain the fitted first side center line and the second side center line of the second side bending section that is mirror-symmetrical to the first side bending section. Among them, the connection coordinates include the coordinates representing the connection between the middle center line and the first side center line. The middle center line and the first side center line satisfy preset conditions, and the preset conditions include: at the connection between the middle center line and the first side center line, the middle center line and the first side center line are continuous, and the first-order derivatives and second-order derivatives of the middle center line and the first-order derivatives and second-order derivatives of the first side center line are all continuous; Constructing the optical waveguide according to the middle center line, the first side center line, and the second side center line.

5. The method according to claim 4, wherein, after obtaining the fitted first side center line, the method includes: Fitting the preset side center line of the second side bending section according to the middle center line parameters, the connection coordinates, and the first non-linear fitting function to obtain the fitted second side center line. Among them, the connection coordinates include the coordinates representing the connection between the middle center line and the second side center line; or, mirroring the first side center line to obtain the second side center line.

6. The method according to claim 4, wherein, the constructing the optical waveguide according to the middle center line, the first side center line, and the second side center line includes: Determining the first width at each position of the first side bending section and the second side bending section and the second width of the middle bending section according to the first side center line; Determining a first distance, a second distance, and a third distance according to the middle center line, the first side center line, and the second side center line. Among them, the first distance includes the distance between each position of the target edge of the first side bending section and the corresponding position of the first side center line, the second distance includes the distance between each position of the target edge of the second side bending section and the corresponding position of the second side center line, and the third distance includes the distance between the target edge of the middle bending section and the middle center line; Constructing the optical waveguide according to the first width, the second width, the first distance, the second distance, and the third distance.

7. The method according to claim 6, wherein, the determining the first width at each position of the first side bending section and the second side bending section and the second width of the middle bending section according to the first side center line includes: Determine the first width at each position in the first side bending section and the second side bending section according to the first side center line and the second non-linear fitting function, wherein the first widths of the first side bending section and the second side bending section both gradually decrease from one end close to the middle bending section to the end far from the middle bending section, and the first widths at the ends of the first side bending section and the second side bending section close to the middle bending section are the same; Determine the first width at the end of the first side bending section close to the middle bending section as the second width, wherein the widths at each position in the middle bending section are constant.

8. The method according to claim 7, wherein, the determining the widths at each position in the first side bending section and the second side bending section according to the first side center line and the second non-linear fitting function includes: determining the first width at each position in the first side bending section according to the first side center line and the second non-linear fitting function, and determining the first width at each position in the second side bending section according to the second side center line and the second non-linear fitting function; or, determining the first width at each position in the first side bending section according to the first side center line and the second non-linear fitting function, and obtaining the first width at each position in the second side bending section by mirroring.

9. The method according to claim 6, wherein, the determining the first distance and the second distance includes: linearly fitting according to the side center line parameters of the first side bending section and the first starting point distance, obtaining the first distance between each position of the target edge of the first side bending section and the corresponding position of the first side center line, and obtaining the second distance between each position of the target edge of the second bending section mirrored to the first side bending section and the corresponding position of the second side center line, wherein the first starting point distance is the distance between the target edge at the starting point of the first side bending section and the first side center line, and the starting point of the first side bending section is the end far from the middle bending section of the first side bending section; wherein, the side center line parameters of the first side bending section are the bending angles and cumulative lengths at each position of the first side center line, and the target edge is the inner edge or the outer edge.

10. The method according to claim 9, wherein, after obtaining the first distance between each position of the target edge of the first side bending section and the corresponding position of the first side center line, it includes one of the following: The second distances between the respective positions of the target edge of the second side bending section and the corresponding positions of the second side center line are linearly fitted according to the side center line parameters of the second side bending section and the second starting point distance, where the side center line parameters of the second side bending section are the bending angles and cumulative lengths of the respective positions of the second side center line, the second starting point distance is the distance between the target edge at the starting point of the second side bending section and the second side center line, and the starting point of the second side bending section is the end of the second side bending section far from the middle bending section; Or, The first distances between the respective positions of the target edge of the first side bending section and the corresponding positions of the first side center line are mirrored to obtain the second distances between the respective positions of the target edge of the second bending section and the corresponding positions of the second side center line.

11. The method according to claim 6, wherein, the determining the first distance and the second distance includes: Linearly fitting according to the side center line parameters of the first side bending section and the third starting point distance to obtain the first distance between the midpoints of the inner and outer edge connections at each position of the first side bending section and the corresponding positions of the first side center line, and to obtain the second distance between the midpoints of the inner and outer edge connections at each position of the second bending section that is mirror-imaged with respect to the first side bending section and the corresponding positions of the second side center line, where the third starting point distance is the distance between the midpoint of the inner and outer edge connections at the starting point of the first side bending section and the first side center line, and the starting point of the first side bending section is the end of the first side bending section far from the middle bending section; wherein the side center line parameters of the first side bending section are the bending angles and cumulative lengths of the respective positions of the first side center line.

12. The method according to claim 11, wherein, after obtaining the first distance between the midpoints of the inner and outer edge connections at each position of the first side bending section and the corresponding positions of the first side center line, one of the following is included: Linearly fitting according to the side center line parameters of the second side bending section and the fourth starting point distance to obtain the second distance between the midpoints of the inner and outer edge connections at each position of the second side bending section and the corresponding positions of the second side center line, where the side center line parameters of the second side bending section are the bending angles and cumulative lengths of the respective positions of the second side center line, and the fourth starting point distance is the distance between the midpoint of the inner and outer edge connections at the starting point of the second side bending section and the second side center line; Or, Mirroring the first distance between the midpoints of the inner and outer edge connections at each position of the first side bending section and the corresponding positions of the first side center line to obtain the second distance between the midpoints of the inner and outer edge connections at each position of the second side bending section and the corresponding positions of the second side center line.

13. The method according to claim 6, wherein, The third distance, the first distance between the target edge of one end of the first side bending section close to the middle bending section and the first side center line, and the second distance between the target edge of one end of the second side bending section close to the middle bending section and the second side center line are all equal.

14. The method according to claim 4, wherein, the fitting of the preset intermediate center line according to the intermediate center line parameter includes: fitting the preset intermediate center line according to one of a preset arc angle and a preset arc radius; or, fitting the preset intermediate center line by a first Bessel function, wherein the first Bessel function is determined by a first coordinate, a second coordinate and at least one first control point coordinate, the first coordinate is the coordinate at the connection of the intermediate center line and the first side center line, and the second coordinate is the coordinate at the connection of the intermediate center line and the second side center line.

15. The method according to claim 14, wherein, in the case of fitting the preset intermediate center line according to one of a preset arc angle and a preset arc radius, the first non-linear fitting function is one of an Euler function and a second Bessel function; in the case of fitting the preset intermediate center line by a first Bessel function, the first non-linear function is an Euler function.

16. A communication device, wherein, the communication device includes: an optical waveguide as described in any one of claims 1-3; or an optical waveguide obtained by an optical waveguide construction method as described in any one of claims 4-15.

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