A design method, device and equipment of a grating coupler and a storage medium

Abstract

The present application relates to the field of optical communication technology, and specifically relates to a design method, device and equipment of a grating coupler and a storage medium. The method comprises: obtaining initial parameters; determining the period of each grating unit according to the initial parameters and the relationship between the scattering angle and the period of the grating unit, and obtaining the initial structure of the grating coupler; under the initial structure, judging whether the scattering range of the grating coupler meets the target scattering range; when the scattering range of the grating coupler does not meet the target scattering range, adjusting the focal point coordinates or the groove array parameters, determining the new period of the grating unit, and repeating the process of adjusting the focal point coordinates or the groove array parameters and determining the period of the grating unit until the scattering range of the grating coupler meets the target scattering range. In the present application, the grating coupler with a specific scattering range is designed without introducing a lens, the good matching between the scattering range of the coupler and the divergence angle of the light source is realized, the coupling efficiency is improved, and the device packaging is not affected.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical communication technology, and particularly relates to a design method and device of a grating coupler, equipment and a storage medium. BACKGROUND

[0002] The grating coupler is a periodic groove structure introduced in a chip waveguide. The grating coupler can scatter the light beam transmitted in the chip into the free space, and can also couple the light beam in the free space into the chip for transmission. When the optical fiber is arranged in the free space, that is, the light beam scattered by the grating coupler is transmitted in the optical fiber, or the light beam output by the optical fiber enters the chip through the grating coupler, because the divergence angle of the light output by the optical fiber is small, the light beam scattered by the grating coupler into the optical fiber and the light beam entering the grating coupler from the optical fiber can maintain good mode field matching by using the current grating coupler with the same scattering angle of each grating unit.

[0003] At present, in order to adapt to the development of chip miniaturization, the optical fiber structure in the above structure needs to be removed. However, if the optical fiber structure is removed, the light beam emitted by the light source directly couples into the chip through the grating coupler, because the divergence angle of the light source is usually large, the use of the current grating coupler with the same scattering angle of each grating unit will cause the phenomenon of mode field mismatch. For example, when a light source with a divergence angle of 6° is used, the coupling efficiency of the light beam output by the light source into the chip through the grating coupler can reach 80%; when a light source with a divergence angle of 16° is used, the coupling efficiency of the light beam output by the light source directly coupled into the chip through the grating coupler without passing through the optical fiber is only 30%.

[0004] In order to solve this problem, a lens structure can be arranged above the grating coupler to shape the mode field of the light beam by the lens, but the introduction of the lens structure will increase the difficulty of device packaging. In addition, a special-shaped grating coupler can also be prepared, such as a slanted side surface inside the groove, so that different groove regions have coupling ability for light beams with different incident angles, but the compatibility of the special-shaped grating coupler with the conventional mass production preparation process is low. SUMMARY

[0005] Therefore, the present application provides a design method and device of a grating coupler, equipment and a storage medium to solve the problem of mode field mismatch during coupling of the grating coupler.

[0006] In a first aspect, the present application provides a design method of a grating coupler, the method comprising: obtaining initial parameters, the initial parameters comprising initial focal point coordinates, grating unit groove number set parameters in the grating coupler, and refractive index of the grating coupler; determining grating unit periods in the grating coupler according to the initial parameters and a relationship between grating unit scattering angles and periods, to obtain an initial structure of the grating coupler; judging whether a scattering range of the grating coupler satisfies a target scattering range under the initial structure; when the scattering range of the grating coupler does not satisfy the target scattering range, adjusting the focal point coordinates or the groove number set parameters, and determining new grating unit periods according to the adjusted focal point coordinates or the groove number set parameters, repeating the process of adjusting the focal point coordinates or the groove number set parameters and determining the grating unit periods until the scattering range of the grating coupler satisfies the target scattering range.

[0007] In the present application, a grating coupler with a specific scattering range is designed without introducing a lens, the scattering range of the coupler is well matched with the divergence angle of a light source, the coupling efficiency is improved, and the device packaging is not affected; meanwhile, the grating groove preparation process used is compatible with the conventional mass production process, and the process flow does not need to be adjusted or special equipment is not needed to be introduced.

[0008] In an optional implementation, the method further comprises: judging whether a central scattering angle of the grating coupler satisfies a preset range; when the central scattering angle of the grating coupler does not satisfy the preset range, adjusting the focal point coordinates, and determining new grating unit periods according to the adjusted focal point coordinates, repeating the process of adjusting the focal point coordinates and determining the grating unit periods until the central scattering angle of the grating coupler satisfies the preset range.

[0009] In the present application, by further judging and adjusting the central scattering angle, the scattering angle of any grating unit can be made not equal to zero, and the energy transmission of the ordinary grating caused by the local group velocity being zero can be prevented.

[0010] In an alternative embodiment, the period of each grating unit in the grating coupler is determined according to the initial parameters and the relationship between the scattering angle and the period of the grating unit, comprising: determining the coordinate of the first grating unit in the grating coupler according to the groove set parameters of the first grating unit; determining the scattering angle of the first grating unit according to the initial focal point coordinate and the coordinate of the first grating unit; determining the period of the first grating unit in the grating coupler according to the scattering angle of the first grating unit and the relationship between the scattering angle and the period of the grating unit; determining the coordinate of the second grating unit in the grating coupler according to the groove set parameters of the second grating unit and the period of the first grating unit; determining the scattering angle of the second grating unit according to the initial focal point coordinate and the coordinate of the second grating unit; determining the period of the second grating unit in the grating coupler according to the scattering angle of the second grating unit and the relationship between the scattering angle and the period of the grating unit; and repeating the determination of the coordinate of the current grating unit according to the groove set parameters of the current grating unit and the period of the previous grating unit, the determination of the scattering angle of the current grating unit according to the initial focal point coordinate and the coordinate of the current grating unit, and the determination of the period of the current grating unit in the grating coupler according to the scattering angle of the current grating unit and the relationship between the scattering angle and the period of the grating unit, until the period of the last grating unit is obtained.

[0011] In the present application, the scattering angle of each grating unit is determined based on the geometric relationship between each grating unit and the focal point, and then the period of each grating unit in the grating coupler is determined according to the relationship between the scattering angle and the period of the grating unit, so as to realize the determination of the structure of the grating coupler.

[0012] In an alternative embodiment, when the scattering range of the grating coupler does not meet the target scattering range, the focal point coordinate or the groove set parameters is adjusted, and the period of the new grating unit is determined according to the adjusted focal point coordinate or the groove set parameters, and the process of adjusting the focal point coordinate or the groove set parameters and determining the period of the grating unit is repeated until the scattering range of the grating coupler meets the target scattering range, comprising: determining the relationship between the scattering range of the grating coupler and the longitudinal coordinate of the focal point according to the geometric relationship between the focal point coordinate, the coordinate of the first grating unit in the grating coupler, the coordinate of the last grating unit in the grating coupler, and the scattering range of the grating coupler; adjusting the longitudinal coordinate of the focal point or the groove set parameters according to the relationship between the scattering range of the grating coupler and the longitudinal coordinate of the focal point, and determining the period of the new grating unit according to the adjusted longitudinal coordinate of the focal point or the groove set parameters, and repeating the process of adjusting the longitudinal coordinate of the focal point or the groove set parameters and determining the period of the grating unit until the scattering range of the grating coupler meets the target scattering range.

[0013] In the application, the relationship between the scattering range of the grating coupler and the longitudinal coordinate of the focus point is determined according to the geometric relationship between the focus point coordinate, the coordinate of the first grating unit of the grating coupler, the coordinate of the last grating unit of the grating coupler and the scattering range of the grating coupler, thereby providing a data basis for the adjustment of the focus point.

[0014] In an optional embodiment, the longitudinal coordinate of the focus point or the groove number set parameter is adjusted according to the relationship between the scattering range of the grating coupler and the longitudinal coordinate of the focus point, and a new grating unit period is determined according to the adjusted longitudinal coordinate of the focus point or the groove number set parameter, and the process of adjusting the longitudinal coordinate of the focus point or the groove number set parameter and determining the grating unit period is repeated until the scattering range of the grating coupler meets the target scattering range, comprising: determining the longitudinal coordinate of the focus point corresponding to the relationship inflection point according to the relationship between the scattering range of the grating coupler and the longitudinal coordinate of the focus point; when the current longitudinal coordinate of the focus point is equal to the longitudinal coordinate of the focus point corresponding to the relationship inflection point, if the current scattering range of the grating coupler is greater than the target scattering range, the longitudinal coordinate of the focus point is increased or decreased, and if the current scattering range of the grating coupler is less than the target scattering range, the number of grooves in the groove number set parameter is increased; when the current longitudinal coordinate of the focus point is greater than the longitudinal coordinate of the focus point corresponding to the relationship inflection point, if the current scattering range of the grating coupler is greater than the target scattering range, the longitudinal coordinate of the focus point is increased, and if the current scattering range of the grating coupler is less than the target scattering range, the longitudinal coordinate of the focus point is decreased; when the current longitudinal coordinate of the focus point is less than the longitudinal coordinate of the focus point corresponding to the relationship inflection point, if the current scattering range of the grating coupler is greater than the target scattering range, the longitudinal coordinate of the focus point is decreased, and if the current scattering range of the grating coupler is less than the target scattering range, the longitudinal coordinate of the focus point is increased; a new grating unit period is determined according to the adjusted longitudinal coordinate of the focus point or the groove number set parameter, and the process of adjusting the longitudinal coordinate of the focus point or the groove number set parameter and determining the grating unit period is repeated until the scattering range of the grating coupler meets the target scattering range.

[0015] In the application, the relationship between the scattering range of the grating coupler and the longitudinal coordinate of the focus point is analyzed, thereby the accurate adjustment of the longitudinal coordinate of the focus point can be realized, and the efficiency of the adjustment is improved.

[0016] In an optional implementation, the relationship between the scattering range of the grating coupler and the longitudinal coordinate of the focal point is determined according to a geometric relationship among the focal point coordinate, the coordinate of the first grating unit of the grating coupler, the coordinate of the last grating unit of the grating coupler, and the scattering range of the grating coupler, including: determining a geometric relationship among the focal point coordinate, the coordinate of the last grating unit of the grating coupler, and the scattering range of the grating coupler and a relationship between the longitudinal coordinate of different focal points and the coordinate of the last grating unit of the grating coupler; and substituting the relationship between the longitudinal coordinate of different focal points and the coordinate of the last grating unit of the grating coupler into the geometric relationship to obtain the relationship between the scattering range of the grating coupler and the longitudinal coordinate of the focal point.

[0017] In an optional implementation, the preset range is a half width of the target scattering range, and when the central scattering angle of the grating coupler does not satisfy the preset range, the focal point coordinate is adjusted, a new grating unit period is determined according to the adjusted focal point coordinate, the process of adjusting the focal point coordinate and determining the grating unit period is repeated until the central scattering angle of the grating coupler satisfies the preset range, including: when the central scattering angle of the grating coupler is less than the half width of the target scattering range, the absolute value of the transverse coordinate of the focal point is increased, a new grating unit period is determined according to the increased absolute value of the transverse coordinate of the focal point, the process of adjusting the transverse coordinate of the focal point and determining the grating unit period is repeated until the central scattering angle of the grating coupler is greater than or equal to the half width of the target scattering range.

[0018] In a second aspect, the present application provides a design device of a grating coupler, including: a parameter acquisition module, configured to acquire initial parameters, the initial parameters including an initial focal point coordinate, a grating unit slot number set parameter in the grating coupler, and a refractive index of the grating coupler; an initial structure determination module, configured to determine a grating unit period in the grating coupler according to the initial parameters and a relationship between a grating unit scattering angle and a period, to obtain an initial structure of the grating coupler; a judgment module, configured to judge whether a scattering range of the grating coupler satisfies a target scattering range under the initial structure; and an adjustment module, configured to adjust the focal point coordinate or the grating unit slot number set parameter when the scattering range of the grating coupler does not satisfy the target scattering range, to determine a new grating unit period according to the adjusted focal point coordinate or grating unit slot number set parameter, and to repeat the process of adjusting the focal point coordinate or grating unit slot number set parameter and determining the grating unit period until the scattering range of the grating coupler satisfies the target scattering range.

[0019] In a third aspect, the present application provides a computer device, including: a memory and a processor, which are in communication connection with each other, and the memory stores computer instructions; the processor executes the computer instructions to perform the design method of the grating coupler in the first aspect or any of the corresponding embodiments thereof.

[0020] In a fourth aspect, the present application provides a computer readable storage medium, having stored thereon computer instructions for causing a computer to execute the design method of the grating coupler according to the first aspect or any of the corresponding embodiments thereof.

[0021] In a fifth aspect, the present application provides a computer program product comprising computer instructions for causing a computer to execute the design method of the grating coupler according to the first aspect or any of the corresponding embodiments thereof. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the specific embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0023] Figure 1 is a flowchart of the design method of the grating coupler according to an embodiment of the present application;

[0024] Figure 2 is a schematic diagram of the focal point and the grating coupler position according to an embodiment of the present application;

[0025] Figure 3 is a schematic diagram of the change of the scattering range when adjusting the focal point ordinate according to an embodiment of the present application;

[0026] Figure 4 is a schematic diagram of the position of the front center scattering angle of the focal point ordinate according to an embodiment of the present application;

[0027] Figure 5 is a schematic diagram of the position of the back center scattering angle of the focal point ordinate according to an embodiment of the present application;

[0028] Figure 6 is a flowchart of another design method of the grating coupler according to an embodiment of the present application;

[0029] Figure 7 is a flowchart of another design method of the grating coupler according to an embodiment of the present application;

[0030] Figure 8 is a schematic diagram of the change of the value of X when Y0 changes from 5 μm to 150 μm according to an embodiment of the present application; n

[0031] Figure 9 ​is a schematic diagram of a function relationship of a according to an embodiment of the present application with respect to Y0;

[0032] Figure 10 、 Figure 11 and Figure 12 are schematic diagrams of corresponding electric field surface distributions when the target scattering range is 19°, 27° and 35° according to an embodiment of the present application;

[0033] Figure 13 、 Figure 14 and Figure 15 are schematic diagrams of Far-field distributions when the target scattering range is 19°, 27° and 35° according to an embodiment of the present application;

[0034] Figure 16 is a structural block diagram of a design device of a grating coupler according to an embodiment of the present application;

[0035] Figure 17 is a schematic diagram of a hardware structure of a computer device according to an embodiment of the present application. DETAILED DESCRIPTION

[0036] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0037] According to an embodiment of the present application, a design method of a grating coupler is provided. It should be noted that the steps shown in the flowchart of the drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described herein can be executed in an order different from that shown herein.

[0038] In the present embodiment, a design method of a grating coupler is provided, which can be used in electronic devices such as computers, mobile phones, tablet computers, etc. Figure 1 is a flowchart of a design method of a grating coupler according to an embodiment of the present application, as shown in Figure 1 the flowchart includes the following steps:

[0039] In step S101, initial parameters are obtained, including initial focal point coordinates, grating unit groove number set parameters in the grating coupler, and refractive index of the grating coupler.

[0040] Specifically, the focusing point coordinate can be understood as the position of the light source above the grating coupler, that is, the light source is arranged at the focusing point position, and the light beam emitted by the light source is coupled into the chip through the grating coupler; at the same time, the focusing point coordinate can also be understood as the position where the light beam transmitted in the chip is focused after being scattered into the free space by the grating coupler. In the embodiment, the initial focusing point coordinate can be any position in the free space, and the focusing point coordinate is adjusted by judging the scattering range of the designed grating coupler, so that the light beam emitted by the light source arranged at the focusing point position can achieve good coupling effect with the grating coupler, or the scattered light beam of the grating coupler can be focused at the focusing point coordinate. That is, it can be understood that the divergence angle of the light source and the scattering range of the grating coupler can correspond to each other.

[0041] In the grating coupler, the structure of the grating unit can be prepared by a conventional mass production process, that is, the grooves of each grating unit are rectangular, and the side surface of the grating unit is perpendicular to the horizontal plane. In the embodiment, the groove number of each grating unit in the grating coupler includes the groove number, which can be set arbitrarily in the initial parameter, and can be adjusted by judging the scattering range of the designed grating coupler. It should be noted that the groove width and groove depth of each grating unit in the embodiment can be designed according to related technologies, thereby facilitating the preparation by the conventional mass production process.

[0042] The refractive index of the grating coupler can be determined by simulation. Specifically, the wavelength of the light beam emitted by the light source at the focusing point position can be determined in advance, that is, the target wavelength; and the material of the grating coupler can be determined, that is, the target material. Then the target wavelength is input into the target material by simulation to determine the refractive index of the grating coupler.

[0043] In step S102, the period of each grating unit in the grating coupler is determined according to the initial parameters and the relationship between the grating unit scattering angle and the period, and the initial structure of the grating coupler is obtained. The relationship between the grating unit scattering angle and the period can be determined by phase matching, and the relationship between the grating unit scattering angle and the period is determined by the phase of each grating unit and the phase matching between the grating units. It should be noted that when the light beam is scattered into the free space by the grating coupler, each grating unit in the grating coupler scatters the light beam to form a certain scattering angle, and thus the scattering angles of all grating units in the grating coupler form the scattering range of the grating coupler.

[0044] Specifically, based on the obtained initial parameters and the geometric relationship between the grooves and the focusing point, the scattering angle of each grating unit can be determined, and the period of each grating unit can be obtained by substituting the scattering angle into the relationship between the grating unit scattering angle and the period, thereby obtaining the initial structure of the grating coupler.

[0045] Step S103, under the initial structure, determine whether the scattering range of the grating coupler meets the target scattering range. Specifically, the scattering range of the grating coupler can also be determined in a simulated manner. For example, after determining the initial structure of the grating coupler, the parameters of the initial structure are input into the simulation software for simulation, and the beam angle range at which the intensity of the scattered beam of the initial structure is reduced to 1 / e of the maximum value under far field conditions is obtained, that is, the scattering range of the grating coupler under the initial structure is obtained. The target scattering range can be understood as the scattering range that the grating coupler is expected to achieve, and the target scattering range can be determined in advance. 2

[0046] After the scattering range of the grating coupler is simulated, it is compared with the target scattering range to determine whether they are equal. If they are equal, it means that the current grating coupler meets the requirements, and thus there is no need to perform subsequent processing. In addition, in other embodiments, when the scattering range of the grating coupler is compared with the target scattering range, if the precision requirement is not high, it can also be determined whether the difference between the two meets a preset value. When the preset value is met, it can also be determined that the scattering range of the grating coupler meets the target scattering range.

[0047] Step S104, when the scattering range of the grating coupler does not meet the target scattering range, adjust the focal point coordinates or the groove array parameters, and determine a new grating unit period according to the adjusted focal point coordinates or the groove array parameters. Repeat the process of adjusting the focal point coordinates or the groove array parameters and determining the grating unit period until the scattering range of the grating coupler meets the target scattering range.

[0048] Specifically, when it is determined that the scattering range of the grating coupler does not meet the target scattering range, the focal point coordinates or the groove array parameters are adjusted, and steps S102 and S103 are re-executed based on the adjusted data. If it still does not meet, the focal point coordinates or the groove array parameters continue to be adjusted, and steps S102 and S103 are executed again until the scattering range of the grating coupler meets the target scattering range.

[0049] The design method of the grating coupler provided in the embodiment of the present application designs a grating coupler with a specific scattering range without introducing a lens, realizes good matching of the scattering angle of the coupler and the divergence angle of the light source, improves the coupling efficiency, and has no influence on device packaging. At the same time, the preparation process of the grating groove adopted is compatible with the conventional mass production process, and there is no need to adjust the process flow or introduce special equipment.

[0050] In the embodiment, a design method of a grating coupler is provided, and the method comprises the following steps:

[0051] ​In step S201, initial parameters are obtained, including initial focus point coordinates, grating element groove number set parameters of the grating coupler, and refractive index of the grating coupler. Details are described below. Figure 1 In step S104 of the embodiment shown, details are not described herein.

[0052] In step S202, the period of each grating element in the grating coupler is determined according to the initial parameters and the relationship between the scattering angle and the period of the grating element, to obtain the initial structure of the grating coupler.

[0053] Specifically, step S202 includes the following steps.

[0054] In step S2021, the coordinates of the first grating element are determined according to the groove number set parameters of the first grating element in the grating coupler.

[0055] In step S2022, the scattering angle of the first grating element is determined according to the initial focus point coordinates and the coordinates of the first grating element.

[0056] In step S2023, the period of the first grating element in the grating coupler is determined according to the scattering angle of the first grating element and the relationship between the scattering angle and the period of the grating element.

[0057] In step S2024, the coordinates of the second grating element are determined according to the groove number set parameters of the second grating element in the grating coupler and the period of the first grating element.

[0058] In step S2025, the scattering angle of the second grating element is determined according to the initial focus point coordinates and the coordinates of the second grating element.

[0059] In step S2026, the period of the second grating element in the grating coupler is determined according to the scattering angle of the second grating element and the relationship between the scattering angle and the period of the grating element.

[0060] In step S2027, the coordinates of the current grating element are determined according to the groove number set parameters of the current grating element and the period of the previous grating element, the scattering angle of the current grating element is determined according to the initial focus point coordinates and the coordinates of the current grating element, and the period of the current grating element in the grating coupler is determined according to the scattering angle of the current grating element and the relationship between the scattering angle and the period of the grating element, until the period of the last grating element is obtained.

[0061] The relationship between the scattering angle and the period of the grating element is determined based on the phase of each grating element and the phase matching between the grating elements. The phase of each grating element is expressed by the following formula:

[0062]

[0063] The phase matching between the grating elements is expressed by the following formula:

[0064]

[0065] Based on the above two formulas, the relationship between the scattering angle and period of the grating unit can be derived as follows:

[0066]

[0067] In the formula, The π represents the phase of the grating unit, ∧ represents the period, and l e Indicates the groove width, n wg The effective refractive index of the waveguide in the unetched region is represented by λ, and the target wavelength is represented by n. e n represents the effective refractive index of the waveguide at a specific groove depth in the etched region. c Let θ represent the cladding refractive index, and θ represent the scattering angle of the grating element. It should be noted that when the groove depth is the same, the waveguide refractive index is the same in all etched regions. Therefore, n can be obtained by performing refractive index simulation measurement at a specific groove location. e .

[0068] For ease of calculation, such as Figure 2 As shown, in this embodiment, a Cartesian coordinate system is established using the focal point and the plane where the grating coupler is located, with the starting position of the groove of the first grating unit in the grating coupler as the zero point. The groove width le of the grating unit is defined as follows. (n) The half-width is the coordinate reference point of the grating unit. Therefore, the coordinates of the first grating unit can be expressed as X1 = le1 / 2, where le1 is the groove width of the first grating unit. Simultaneously, based on the geometric relationship between the initial focal point coordinates (X0, Y0) and the first grating unit, the scattering angle of the first grating unit can be expressed as... Based on the relationship between the scattering angle and period of the grating unit, the period of the first grating unit can then be obtained as follows:

[0069] For the second grating unit, its coordinates are determined based on the period of the first grating unit and its own groove width; that is, the coordinates of the second grating unit are... Then, using the same method as calculating the period of the first grating unit, the scattering angle of the second grating unit is determined. The period of the second grating unit is

[0070] Similarly, the period of each subsequent grating unit can be calculated using the same method as when calculating the period of the second grating unit. Therefore, if the number of grating units in the grating coupler is n, then the coordinates of the nth grating unit are... The scattering angle of the nth grating unit is The period of the nth grating unit is

[0071] Step S203: Under the initial structure, determine whether the scattering range of the grating coupler meets the target scattering range; for details, please refer to [link to relevant documentation]. Figure 1 Step S103 of the illustrated embodiment will not be described again here.

[0072] Step S204: When the scattering range of the grating coupler does not meet the target scattering range, adjust the focal point coordinates or groove array parameters, and determine a new grating unit period based on the adjusted focal point coordinates or groove array parameters. Repeat the process of adjusting the focal point coordinates or groove array parameters and determining the grating unit period until the scattering range of the grating coupler meets the target scattering range.

[0073] Specifically, step 204 above includes:

[0074] Step S2041: Based on the geometric relationship between the focal point coordinates, the coordinates of the first grating unit of the grating coupler, the coordinates of the last grating unit of the grating coupler, and the scattering range of the grating coupler, determine the relationship between the scattering range of the grating coupler and the vertical coordinate of the focal point.

[0075] In an optional implementation, step S2042 includes:

[0076] Step a1: Determine the geometric relationship between the focal point coordinates, the coordinates of the first grating unit of the grating coupler, the coordinates of the last grating unit of the grating coupler, and the scattering range of the grating coupler, and the relationship between the ordinate of different focal points and the coordinates of the last grating unit of the grating coupler.

[0077] Specifically, as shown in the figure, based on geometric relationships, the scattering range α(X) of the grating coupler... n Y0) can be represented by the following formula:

[0078]

[0079] In this formula, the coordinate X1 of the first grating unit is related to the parameters of the grating unit groove array, while the coordinate X of the nth grating unit... n The scattering range needs to be determined using the coordinates of the previous grating unit and the focal point coordinates. Therefore, the scattering range is related to the focal point coordinates and the groove array parameters. In this embodiment, the groove array parameters of the grating unit and the x-coordinate of the focal point are fixed, and the x-coordinate corresponding to the y-coordinate Y0 of different focal points is determined through simulation. n And draw X n Regarding the scatter plot of Y0, fit X n The function expression X of Y0n (Y0).

[0080] Step a2, the relationship between the longitudinal coordinate of the different focusing points and the coordinate of the last grating unit of the grating coupler is substituted into the geometric relationship to obtain the relationship between the scattering range of the grating coupler and the longitudinal coordinate of the focusing point. Specifically, X n The function expression X n (Y0) is substituted into the scattering range calculation formula a(X n ,Y0) of the grating coupler to obtain the relationship between the scattering range of the grating coupler and the longitudinal coordinate of the focusing point, i.e., the expression of a(Y0).

[0081] Step S2042, the longitudinal coordinate of the focusing point or the groove set parameter is adjusted according to the relationship between the scattering range of the grating coupler and the longitudinal coordinate of the focusing point, and a new grating unit period is determined according to the adjusted longitudinal coordinate of the focusing point or the groove set parameter. The process of adjusting the longitudinal coordinate of the focusing point or the groove set parameter and determining the grating unit period is repeated until the scattering range of the grating coupler meets the target scattering range.

[0082] Specifically, based on the expression of a(Y0), the adjustment of the longitudinal coordinate of the focusing point can be used to adjust the scattering range of the grating coupler. At the same time, since the coordinate of the grating unit is also related to the groove set parameter, the adjustment of the groove set parameter can also be used to adjust the scattering range of the grating coupler.

[0083] In an optional embodiment, the above step S2042 comprises:

[0084] Step b1, the longitudinal coordinate of the focusing point corresponding to the inflection point of the relationship is determined according to the relationship between the scattering range of the grating coupler and the longitudinal coordinate of the focusing point. Specifically, by analyzing the relationship between the scattering range of the grating coupler and the longitudinal coordinate of the focusing point, it can be found that there is an inflection point in the relationship, before the inflection point, the scattering range monotonically increases with the longitudinal coordinate, and after the inflection point, the scattering range monotonically decreases with the longitudinal coordinate. Therefore, by comparing the current longitudinal coordinate of the focusing point with the longitudinal coordinate of the inflection point, it can be determined how to adjust the longitudinal coordinate of the focusing point.

[0085] Step b2, when the longitudinal coordinate of the current focusing point is equal to the longitudinal coordinate of the focusing point corresponding to the inflection point of the relationship, if the scattering range of the current grating coupler is greater than the target scattering range, the longitudinal coordinate of the focusing point is increased or decreased, and if the scattering range of the current grating coupler is less than the target scattering range, the number of grooves in the groove set parameter is increased.

[0086] Specifically, the current focus point ordinate can be understood as the ordinate of the focus point before the focus point coordinate is adjusted when it is judged that the scattering range of the grating coupler does not satisfy the target scattering range. For example, the scattering range of the grating coupler of the initial structure does not satisfy the target scattering range, and the current focus point ordinate is the ordinate of the focus point in the initial focus point coordinate.

[0087] In the case where the ordinate of the current focus point is equal to the ordinate of the focus point corresponding to the inflection point, if the scattering range of the current grating coupler is greater than the target scattering range, according to the monotonicity on both sides of the inflection point, the ordinate of the focus point can be increased or decreased at this time. If the scattering range of the current grating coupler is less than the target scattering range, because the scattering range corresponding to the inflection point has reached the maximum value, i.e., changing the ordinate of the focus point cannot improve the scattering range, at this time, the parameters of the groove set can be changed, such as increasing the number of grooves to improve the scattering range.

[0088] Step b3, when the ordinate of the current focus point is greater than the ordinate of the focus point corresponding to the relationship inflection point, if the scattering range of the current grating coupler is greater than the target scattering range, the ordinate of the focus point is increased, and if the scattering range of the current grating coupler is less than the target scattering range, the ordinate of the focus point is decreased.

[0089] Specifically, in the case where the ordinate of the current focus point is greater than the ordinate of the focus point corresponding to the relationship inflection point, if the scattering range of the current grating coupler is greater than the target scattering range, according to the monotonicity on the right side of the inflection point, the ordinate of the focus point needs to be increased. If the scattering range of the current grating coupler is less than the target scattering range, the ordinate of the focus point needs to be decreased.

[0090] Step b4, when the ordinate of the current focus point is less than the ordinate of the focus point corresponding to the relationship inflection point, if the scattering range of the current grating coupler is greater than the target scattering range, the ordinate of the focus point is decreased, and if the scattering range of the current grating coupler is less than the target scattering range, the ordinate of the focus point is increased.

[0091] Specifically, in the case where the ordinate of the current focus point is less than the ordinate of the focus point corresponding to the relationship inflection point, if the scattering range of the current grating coupler is greater than the target scattering range, according to the monotonicity on the left side of the inflection point, the ordinate of the focus point needs to be decreased. If the scattering range of the current grating coupler is less than the target scattering range, the ordinate of the focus point needs to be increased.

[0092] Step b5, according to the adjusted ordinate of the focus point or the parameters of the groove set, a new grating unit period is determined, and the process of adjusting the ordinate of the focus point or the parameters of the groove set and determining the grating unit period is repeated until the scattering range of the grating coupler satisfies the target scattering range.

[0093] Specifically, after adjusting the ordinate of the focal point or the groove array parameters, it is necessary to return to step S202 to calculate the period of the grating unit based on the adjusted parameters and determine whether the scattering range of the grating coupler meets the target scattering range. If not, it is necessary to continue adjusting the ordinate of the focal point or the groove array parameters according to step S204 until the scattering range of the grating coupler meets the target scattering range. For example, Figure 3 As shown, changing the vertical coordinate of the focal point can adjust the scattering range of the grating coupler. For example, when the focal point is adjusted from focal point 1 to focal point 2, the scattering range of the grating coupler changes from α1 to α2.

[0094] Step S205: Determine whether the center scattering angle of the grating coupler meets the preset range; when the center scattering angle of the grating coupler does not meet the preset range, adjust the focal point coordinates and determine the new grating unit period based on the adjusted focal point coordinates, repeat the process of adjusting the focal point coordinates and determining the grating unit period until the center scattering angle of the grating coupler meets the preset range.

[0095] In determining whether the scattering range of the grating coupler meets the target scattering range, it is also necessary to further ensure that the center scattering angle of the grating coupler meets the preset range, thereby ensuring that the scattering angle of any grating unit is not equal to 0, thus preventing the grating coupler from experiencing slow energy transmission due to the local group velocity being zero.

[0096] Specifically, step S205 includes:

[0097] Step S2051: When the absolute value of the center scattering angle of the grating coupler is less than half the width of the target scattering range, increase the absolute value of the abscissa of the focal point, and determine a new grating unit period based on the increased absolute value of the abscissa of the focal point. Repeat the process of adjusting the abscissa of the focal point and determining the grating unit period until the center scattering angle of the grating coupler is greater than or equal to half the width of the target scattering range.

[0098] The center scattering angle of the grating coupler is such that the intensity of the scattered beam decreases to its maximum value of 1 / e. 2 The angle corresponding to half of the beam angle range at that time. For example, as Figure 4 The diagram shows the variation of the intensity of the scattered beam with the scattering angle. The intensity decreases to its maximum value of 1 / e. 2 The beam angle range is the angle between A and B, which is the target scattering range. Point A corresponds to an angle of -10°, and point B corresponds to an angle of 15°. Therefore, the target scattering range α = BA = 15° - (-10°) = 25°. Thus, the half-width of the target scattering range is... The center scattering angle of the grating coupler is the angle corresponding to half of the angular range between A and B, that is, the absolute value of the center scattering angle. In this example, the absolute value of the center scattering angle is less than half the width of the target scattering range.

[0099] Since the ordinate of the focal point and the groove array parameters have been determined in step S204, the abscissa of the focal point can now be adjusted, such as by increasing the absolute value of the abscissa. Then, the process returns to step S202 to calculate the period of the grating unit, determine whether it conforms to the target scattering range, and determine whether the central scattering angle is greater than or equal to half the width of the scattering range. If, after adjusting the abscissa of the focal point, the central scattering angle is greater than or equal to half the width of the scattering range, then the current structure of the grating coupler is used as the final structure.

[0100] For example, after adjusting the x-coordinate of the focal point, the intensity of the scattered beam changes with the scattering angle as follows: Figure 5 As shown. At this point, the intensity decreases to its maximum value of 1 / e. 2 The beam angle range at time is the angle between C and D, which is the target scattering range. Point C corresponds to an angle of -30°, and point D corresponds to an angle of -5°. Therefore, the target scattering range α = DC = (-5°) - (-30°) = 25°. Thus, the half-width of the target scattering range is... The center scattering angle of the grating coupler is the angle corresponding to half of the angular range between CD, that is, the absolute value of the center scattering angle. It can be seen that after adjusting the x-coordinate of the focal point, the absolute value of the central scattering angle is greater than or equal to the half-width of the target scattering range.

[0101] As a specific application embodiment of the present invention, such as Figure 6 and Figure 7 As shown, the design method of this grating coupler can be implemented using the following process:

[0102] S1, simulate and retrieve refractive index, configure input parameters.

[0103] 1.1 Select the target wavelength λ and the target scattering range α T .

[0104] 1.2, Given the initial focal point coordinates (X0, Y0) and the initial groove width le of each grating unit. (n) Array.

[0105] 1.3, Waveguide refractive index N of the target material at the target wavelength λ is retrieved through simulation. wg And the effective refractive index N of the waveguide at the specified trench depth e Select the cladding refractive index n c .

[0106] S2, based on phase matching and geometric relationships, generates the initial grating structure.

[0107] 2.1, take the starting position of the first grating groove as zero coordinates, define the grating unit groove width le (n) , and the half width is the coordinate reference point of the grating unit.

[0108] 2.2, according to the groove width of the first grating unit, the coordinates X1 of the grating unit are obtained, the scattering angle θ1 is obtained according to the geometric relationship, and the period ∧1 is obtained according to the phase matching relationship, and the periods of all grating units are recursively obtained to obtain the initial grating structure.

[0109] S3, set the termination condition, match the scattering range.

[0110] 3.1, output the beam angle range α (that is, the initial scattering range) when the initial grating structure far-field scattering beam intensity is reduced to 1 / e 2 of the maximum value.

[0111] 3.2, if α = α T , terminate S3.

[0112] 3.3, if α ≠ α T ; obtain the relationship formula α (X n , Y0) of the scattering range α and the grating length X n , the focusing height Y0 through geometric relationship. Extract the X n value of the initial groove width le (n) under different Y0 through simulation, draw the scatter plot of X n about Y0, fit the function expression X n about Y0 X n (Y0); substitute X n (Y0) into α (X n , Y0) to obtain the expression of α (Y0), and draw the scatter plot of α under different Y0. Fix X0, and combine the interval monotonicity of the function α (Y0) to precisely control the scattering range α of the grating coupler by changing the focusing height Y0 until α = α T .

[0113] Specifically, when Y0 = Y g , and α > α T , increase or decrease Y0 and execute S2; if α < α T , increase the number of elements of the grating array parameter and execute S2; when Y0 > Y g , and α > α T , increase Y0 and execute S2; if α < α T , decrease Y0 and execute S2; when Y0 < Y g , and α > α T , decrease Y0 and execute S2; if α < α TIf Y0 is increased, then S2 is executed.

[0114] S4, setting termination condition, optimizing central scattering angle.

[0115] Adjusting X0 so that the scattering angle of any grating unit is not equal to zero, preventing ordinary grating from causing slow energy transmission due to local group velocity being zero.

[0116] 4.1, when the absolute value of the central scattering angle |β| < scattering range half-width α / 2, increasing |X0| and then executing S2 and S3.

[0117] 4.2, when the absolute value of the central scattering angle |β| ≥ scattering range half-width α / 2, terminating S4 and outputting the period of each grating unit and the scattering range α.

[0118] Taking the silicon nitride (Silicon Nitride on Insulator, SNOI) photonic integrated material platform as an example, the grating structure is designed according to the parameters of standard mass production SNOI, and the corresponding silicon dioxide buried oxygen layer, silicon nitride layer and groove depth are 5 μm, 350 nm and 210 nm respectively. The target wavelength λ is selected as 850 nm, and the initial focal point coordinates of the radiation on the arbitrary given grating coupler are (-5 μm, 100 μm); the groove number array parameters of the grating unit consist of 70 elements, of which the first 35 elements are increased by 3 nm gradient with 60 nm as the starting value, and the last 35 elements are 162 nm; the cladding medium is selected as air, and the corresponding refractive index n c = 1. Through FDTD (Finite Difference Time Domain, Finite Difference Time Domain) calculation, the effective refractive indexes n u and n e of the unetched region (region without grooves) and the etched region (groove region) of the waveguide are 1.8276 and 1.5787 respectively.

[0119] Combined with the actual process conditions, the value of X n is extracted from FDTD when Y0 changes from 5 μm to 150 μm, and the curve is shown in Figure 8 , and the function relationship of X n ~ Y0 is fitted by using a double-parameter exponential decay function. When Adj. R-Square (adjusted coefficient of determination) > 0.999, the following expression is obtained:

[0120]

[0121] Substituting the above formula into α (X n , Y0) obtains the function relationship of α about Y0, and the curve is shown in Figure 9As shown in the figure, it can be seen that the function presents opposite monotonicity on both sides of the inflection point Y0=13μm, and from the pure geometric point of view, the grating coupler composed of the given groove array parameters has a scattering range maximum of 44.6°.

[0122] Three target scattering ranges are selected, respectively, α T =19°, 27° and 35°, combined with the monotonic decreasing characteristics of the right interval of the function inflection point, the grating structure is regulated on the basis of the initial focal point (-5μm, 100μm), and the target scattering ranges are obtained after multiple iterations, as shown in Figure 10 , Figure 11 and Figure 12 are respectively the electric field surface distribution diagrams corresponding to the obtained target scattering ranges of 19°, 27° and 35°, as shown in Figure 13 , Figure 14 and Figure 15 are respectively the Far-field distribution diagrams when the target scattering ranges are 19°, 27° and 35°.

[0123] In the embodiment, a design device of a grating coupler is also provided, which is used to implement the above-mentioned embodiments and preferred embodiments, and details have been described above. As used below, the term "module" can be a combination of software and / or hardware that implements a predetermined function. Although the device described in the following embodiments is preferably implemented in software, implementation of hardware, or a combination of software and hardware, is also possible and is contemplated.

[0124] The embodiment provides a design device of a grating coupler, as shown in Figure 16 , comprising:

[0125] A parameter acquisition module 161 is configured to acquire initial parameters, wherein the initial parameters include initial focal point coordinates, groove array parameter of each grating unit in the grating coupler, and refractive index of the grating coupler;

[0126] An initial structure determination module 162 is configured to determine a period of each grating unit in the grating coupler according to the initial parameters and the relationship between the grating unit scattering angle and the period, to obtain an initial structure of the grating coupler;

[0127] A judgment module 163 is configured to judge whether the scattering range of the grating coupler satisfies a target scattering range under the initial structure.

[0128] The adjustment module 164 is used to adjust the focal point coordinates or groove array parameters when the scattering range of the grating coupler does not meet the target scattering range, and to determine a new grating unit period based on the adjusted focal point coordinates or groove array parameters. The process of adjusting the focal point coordinates or groove array parameters and determining the grating unit period is repeated until the scattering range of the grating coupler meets the target scattering range.

[0129] Further functional descriptions of the above modules are the same as those in the corresponding embodiments described above, and will not be repeated here.

[0130] This invention also provides a computer device having the above-described features. Figure 16 The design device for the grating coupler is shown.

[0131] Please see Figure 17 , Figure 17 This is a schematic diagram of the structure of a computer device provided in an optional embodiment of the present invention, such as... Figure 17 As shown, the computer device includes one or more processors 10, memory 20, and interfaces for connecting the components, including high-speed interfaces and low-speed interfaces. The components communicate with each other via different buses and can be mounted on a common motherboard or otherwise installed as needed. The processors can process instructions executed within the computer device, including instructions stored in or on memory to display graphical information of a GUI on external input / output devices (such as display devices coupled to the interfaces). In some alternative implementations, multiple processors and / or multiple buses can be used with multiple memories and multiple memory modules, if desired. Similarly, multiple computer devices can be connected, each providing some of the necessary operations (e.g., as a server array, a group of blade servers, or a multiprocessor system). Figure 17 Take a processor 10 as an example.

[0132] Processor 10 may be a central processing unit, a network processor, or a combination thereof. Processor 10 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The programmable logic device may be a complex programmable logic device (CAMP), a field-programmable gate array (FPGA), a general-purpose array logic (GDA), or any combination thereof.

[0133] The memory 20 stores instructions executable by at least one processor 10 to cause at least one processor 10 to perform the method shown in the above embodiments.

[0134] The memory 20 can include a program storage area and a data storage area. The program storage area can store an operating system, application programs required by at least one function, etc. The data storage area can store data created by the computer device according to the presentation of a small program landing page, etc. In addition, the memory 20 can include a high-speed random access memory, and can also include a non-transitory memory, such as at least one magnetic disk storage device, a flash memory device, or other non-transitory solid-state memory device. In some optional embodiments, the memory 20 can optionally include a memory disposed remotely relative to the processor 10, and these remote memories can be connected to the computer device through a network. Examples of the network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and a combination thereof.

[0135] The memory 20 can include a volatile memory, such as a random access memory, and can also include a non-volatile memory, such as a flash memory, a hard disk, or a solid-state disk, and can also include a combination of the above-mentioned memories.

[0136] The computer device further includes a communication interface 30 for the computer device to communicate with other devices or a communication network.

[0137] The embodiments of the present application also provide a computer readable storage medium, and the above-mentioned method according to the embodiments of the present application can be implemented in hardware, firmware, or recorded in a storage medium, or stored in a remote storage medium or a non-transitory machine readable storage medium and stored in a local storage medium through network downloading of computer code, so that the method described herein can be processed by such software on a storage medium using a general-purpose computer, a special-purpose processor, or programmable or special-purpose hardware. The storage medium can be a magnetic disk, an optical disk, a read-only memory, a random access memory, a flash memory, a hard disk, or a solid-state disk, etc. Further, the storage medium can also include a combination of the above-mentioned memories. It can be understood that the computer, the processor, the microprocessor controller, or the programmable hardware includes a storage component that can store or receive software or computer code, and when the software or computer code is accessed and executed by the computer, the processor, or the hardware, the method shown in the above embodiments is implemented.

[0138] Part of the present application can be applied as a computer program product, for example, computer program instructions, when executed by a computer, through the operation of the computer, can invoke or provide the method and / or technical solutions according to the present application. Those skilled in the art should understand that the form of computer program instructions in computer readable medium includes but is not limited to source files, executable files, installation package files and the like, and accordingly, the way of computer program instructions executed by computer includes but is not limited to: the computer directly executes the instructions, or the computer compiles the instructions and then executes the corresponding compiled program, or the computer reads and executes the instructions, or the computer reads and installs the instructions and then executes the corresponding installed program. Here, the computer readable medium can be any available computer readable storage medium or communication medium accessible to the computer.

[0139] Although the embodiments of the present application are described in conjunction with the drawings, various modifications and changes can be made by those skilled in the art without departing from the spirit and scope of the present application, and such modifications and changes fall within the scope defined by the appended claims.

Claims

1. A method of designing a grating coupler, characterized by, The method comprises: obtaining initial parameters, the initial parameters comprising initial focus point coordinates, grating cell groove number set parameters in a grating coupler, and a refractive index of the grating coupler; determining grating cell periods in the grating coupler according to the initial parameters and a relationship between grating cell scattering angles and periods, to obtain an initial structure of the grating coupler; under the initial structure, judging whether a scattering range of the grating coupler meets a target scattering range; when the scattering range of the grating coupler does not meet the target scattering range, adjusting the focus point coordinates or the groove number set parameters, and determining new grating cell periods according to the adjusted focus point coordinates or the groove number set parameters, and repeating the processes of adjusting the focus point coordinates or the groove number set parameters and determining the grating cell periods until the scattering range of the grating coupler meets the target scattering range; wherein when the scattering range of the grating coupler does not meet the target scattering range, adjusting the focus point coordinates or the groove number set parameters, and determining new grating cell periods according to the adjusted focus point coordinates or the groove number set parameters, and repeating the processes of adjusting the focus point coordinates or the groove number set parameters and determining the grating cell periods until the scattering range of the grating coupler meets the target scattering range, comprising: determining a relationship between the scattering range of the grating coupler and a longitudinal coordinate of the focus point according to a geometric relationship between the focus point coordinates, coordinates of a first grating cell of the grating coupler, coordinates of a last grating cell of the grating coupler, and the scattering range of the grating coupler; adjusting the longitudinal coordinate of the focus point or the groove number set parameters according to the relationship between the scattering range of the grating coupler and the longitudinal coordinate of the focus point, and determining new grating cell periods according to the adjusted longitudinal coordinate of the focus point or the groove number set parameters, and repeating the processes of adjusting the longitudinal coordinate of the focus point or the groove number set parameters and determining the grating cell periods until the scattering range of the grating coupler meets the target scattering range.

2. The method of claim 1, wherein, The method further comprises: judging whether a central scattering angle of the grating coupler meets a preset range; when the central scattering angle of the grating coupler does not meet the preset range, adjusting the focus point coordinates, and determining new grating cell periods according to the adjusted focus point coordinates, and repeating the processes of adjusting the focus point coordinates and determining the grating cell periods until the central scattering angle of the grating coupler meets the preset range.

3. The method of claim 1, wherein, determining the grating cell periods in the grating coupler according to the initial parameters and the relationship between the grating cell scattering angles and the periods, comprising: determining coordinates of the first grating cell according to the groove number set parameters of the first grating cell in the grating coupler; determining a scattering angle of the first grating cell according to the initial focus point coordinates and the coordinates of the first grating cell; determining a period of the first grating cell in the grating coupler according to the scattering angle of the first grating cell and the relationship between the grating cell scattering angles and the periods; determining coordinates of the second grating cell according to the groove number set parameters of the second grating cell in the grating coupler and the period of the first grating cell; determining a scattering angle of the second grating cell according to the initial focus point coordinates and the coordinates of the second grating cell; determining the period of the second grating unit in the grating coupler according to the scattering angle of the second grating unit and the relationship between the scattering angle and the period of the grating unit; repeating the process of determining the coordinate of the current grating unit according to the groove set parameter of the current grating unit and the period of the previous grating unit, determining the scattering angle of the current grating unit according to the initial focal point coordinate and the coordinate of the current grating unit, and determining the period of the current grating unit in the grating coupler according to the scattering angle of the current grating unit and the relationship between the scattering angle and the period of the grating unit, until the period of the last grating unit is obtained.

4. The method of claim 1, wherein, adjusting the longitudinal coordinate of the focal point or the groove set parameter according to the relationship between the scattering range of the grating coupler and the longitudinal coordinate of the focal point, and determining the new period of the grating unit according to the adjusted longitudinal coordinate of the focal point or the groove set parameter, repeating the process of adjusting the longitudinal coordinate of the focal point or the groove set parameter and determining the period of the grating unit until the scattering range of the grating coupler meets the target scattering range, comprising: determining the longitudinal coordinate of the focal point corresponding to the relationship inflection point according to the relationship between the scattering range of the grating coupler and the longitudinal coordinate of the focal point; when the longitudinal coordinate of the current focal point is equal to the longitudinal coordinate of the focal point corresponding to the relationship inflection point, if the scattering range of the current grating coupler is greater than the target scattering range, increasing or decreasing the longitudinal coordinate of the focal point, if the scattering range of the current grating coupler is less than the target scattering range, increasing the number of grooves in the groove set parameter; when the longitudinal coordinate of the current focal point is greater than the longitudinal coordinate of the focal point corresponding to the relationship inflection point, if the scattering range of the current grating coupler is greater than the target scattering range, increasing the longitudinal coordinate of the focal point, if the scattering range of the current grating coupler is less than the target scattering range, decreasing the longitudinal coordinate of the focal point; when the longitudinal coordinate of the current focal point is less than the longitudinal coordinate of the focal point corresponding to the relationship inflection point, if the scattering range of the current grating coupler is greater than the target scattering range, decreasing the longitudinal coordinate of the focal point, if the scattering range of the current grating coupler is less than the target scattering range, increasing the longitudinal coordinate of the focal point; determining the new period of the grating unit according to the adjusted longitudinal coordinate of the focal point or the groove set parameter, repeating the process of adjusting the longitudinal coordinate of the focal point or the groove set parameter and determining the period of the grating unit until the scattering range of the grating coupler meets the target scattering range.

5. The method of claim 1, wherein, determining the relationship between the scattering range of the grating coupler and the longitudinal coordinate of the focal point according to the geometric relationship between the focal point coordinate, the coordinate of the first grating unit of the grating coupler, the coordinate of the last grating unit of the grating coupler and the scattering range of the grating coupler, comprising: determining the geometric relationship between the focal point coordinate, the coordinate of the first grating unit of the grating coupler, the coordinate of the last grating unit of the grating coupler and the scattering range of the grating coupler and the relationship between the longitudinal coordinates of different focal points and the coordinate of the last grating unit of the grating coupler; substituting the relationship between the longitudinal coordinates of different focal points and the coordinate of the last grating unit of the grating coupler into the geometric relationship to obtain the relationship between the scattering range of the grating coupler and the longitudinal coordinate of the focal point.

6. The method of claim 2, wherein, The preset range is a half width of the target scattering range, when the central scattering angle of the grating coupler does not satisfy the preset range, the focal point coordinates are adjusted, and a new grating unit period is determined according to the adjusted focal point coordinates, the process of adjusting the focal point coordinates and determining the grating unit period is repeated until the central scattering angle of the grating coupler satisfies the preset range, comprising: When the central scattering angle of the grating coupler is less than the half width of the target scattering range, the absolute value of the horizontal coordinate of the focal point is increased, and a new grating unit period is determined according to the increased absolute value of the horizontal coordinate of the focal point, the process of adjusting the horizontal coordinate of the focal point and determining the grating unit period is repeated until the central scattering angle of the grating coupler is greater than or equal to the half width of the target scattering range.

7. A design apparatus of a grating coupler, characterized by, The device comprises: The parameter acquisition module is configured to acquire initial parameters, the initial parameters comprising initial focal point coordinates, a grating unit slot set parameter in the grating coupler and a refractive index of the grating coupler; The initial structure determination module is configured to determine a grating unit period in the grating coupler according to the initial parameters and a relationship between a grating unit scattering angle and the grating unit period, to obtain an initial structure of the grating coupler; The judging module is configured to judge whether a scattering range of the grating coupler satisfies a target scattering range under the initial structure; The adjusting module is configured to adjust the focal point coordinates or the slot set parameter when the scattering range of the grating coupler does not satisfy the target scattering range, and to determine a new grating unit period according to the adjusted focal point coordinates or the slot set parameter, and to repeat the process of adjusting the focal point coordinates or the slot set parameter and determining the grating unit period until the scattering range of the grating coupler satisfies the target scattering range; When the scattering range of the grating coupler does not satisfy the target scattering range, the focal point coordinates or the slot set parameter is adjusted, and a new grating unit period is determined according to the adjusted focal point coordinates or the slot set parameter, the process of adjusting the focal point coordinates or the slot set parameter and determining the grating unit period is repeated until the scattering range of the grating coupler satisfies the target scattering range, comprising: The relationship between the scattering range of the grating coupler and the vertical coordinate of the focal point is determined according to a geometric relationship between the focal point coordinates, a coordinate of a first grating unit of the grating coupler, a coordinate of a last grating unit of the grating coupler and the scattering range of the grating coupler; The vertical coordinate of the focal point or the slot set parameter is adjusted according to the relationship between the scattering range of the grating coupler and the vertical coordinate of the focal point, and a new grating unit period is determined according to the adjusted vertical coordinate of the focal point or the slot set parameter, the process of adjusting the vertical coordinate of the focal point or the slot set parameter and determining the grating unit period is repeated until the scattering range of the grating coupler satisfies the target scattering range.

8. A computer device, comprising: Comprise: A memory and a processor, which are in communication connection with each other, the memory stores computer instructions, and the processor executes the computer instructions to perform the design method of the grating coupler in any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, The computer readable storage medium has stored thereon computer instructions for causing a computer to perform the design method of the optical grating coupler according to any one of claims 1 to 6.

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