Graph duty ratio design method and system

Abstract

The invention relates to the technical field of waveguide device design simulation, in particular to a pattern duty ratio design method and system. Comprising the steps that a class of constraint conditions of a to-be-simulated object are obtained, at least one first waveguide pattern is arranged in the to-be-simulated object, and the class of constraint conditions comprise the pattern duty ratio of the first waveguide pattern; selecting a second-class constraint condition according to the type of the to-be-simulated object, wherein the second-class constraint condition comprises an auxiliary parameter used for describing the specification of the to-be-simulated object; constructing a simulation constraint model according to the first-class constraint condition and the second-class constraint condition; at least one round of simulation is conducted on the simulation constraint model through an electromagnetic simulation method, so that a design evaluation result of the simulation constraint model is obtained, and the design evaluation result comprises at least one simulation solution used for defining the optical performance of the to-be-simulated object. According to the method, the pattern duty ratio is optimally designed, so that the process implementation difficulty of the waveguide device in the nanoimprint process is reduced.

Description

Technical Field

[0001] This invention relates to the field of waveguide device design simulation technology, specifically to a graphical duty cycle design method and system. Background Technology

[0002] The nanoimprinting process involves uniformly coating an imprinting adhesive onto a waveguide substrate, using an imprinting template with a grating structure on its surface as a master template, and then using nanoimprinting equipment to copy the surface relief grating structure on the imprinting template onto the imprinting adhesive on the waveguide substrate. After exposure, demolding, and other steps, the fabrication of the grating waveguide is completed.

[0003] For example, patent application CN113655551A discloses an arbitrary dispersion-tunable metasurface device, whose fabrication process mainly consists of five steps. The first step is spin-coating photoresist, which involves spin-coating photoresist onto a selected dielectric substrate. Other methods can also be used to prepare the photoresist, followed by baking. The second step is precise exposure of the pattern using photolithography, including nanoimprint lithography. The third step is filling the exposed areas using atomic layer deposition to create a structure with excellent steepness. The fourth step is etching, which involves etching away any excess photoresist. The final step is resist removal, which removes all photoresist except for titanium dioxide.

[0004] However, the applicant noted that nanoimprinting technology still presents technical challenges in the practical application of fabricating some complex waveguide devices. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for designing graphic duty cycles, which can partially solve or alleviate the above-mentioned deficiencies in the prior art and can alleviate the problem of uneven thickness in nanoimprinting processes to a certain extent.

[0006] To solve the aforementioned technical problems, the present invention specifically adopts the following technical solution: A first aspect of the present invention is to provide a method for designing graphic duty cycles, comprising the steps of: S100, Obtain a set of constraints for the object to be simulated. The object to be simulated has at least one first waveguide pattern. The set of constraints includes the duty cycle of the first waveguide pattern, wherein the duty cycle is calculated as follows: ; in, The area occupied by the waveguide region. This refers to the area occupied by the non-waveguide region; S102, Select two types of constraints according to the type of the object to be simulated, the two types of constraints include auxiliary parameters used to describe the specifications of the object to be simulated; S104, Construct a simulation constraint model based on the first type of constraint and the second type of constraint; S106, The simulation constraint model is simulated at least once using an electromagnetic simulation method to obtain the design evaluation result of the simulation constraint model. The design evaluation result includes at least one simulation solution for defining the optical performance of the object to be simulated.

[0007] In some embodiments, S106 includes the step of: S1061, Define a first number of simulation combinations based on the first type of constraint and the second type of constraint, wherein the simulation combination includes: graphic duty cycle value and auxiliary value of auxiliary parameter; S1062, Perform simulation calculations on the simulation constraint model according to the simulation combination to obtain a first number of simulation solutions, wherein the type of the simulation solution is selected according to the type of the object to be simulated; S1063, Select a local optimum from the first number of simulation solutions; S1064, obtain the current global optimal solution, determine whether the local optimal solution is greater than the global optimal solution, if so, update the local optimal solution to the global optimal solution, otherwise, keep the current global optimal solution.

[0008] In some embodiments, S106 further includes the step of: S1065, determine whether the global optimal solution is greater than the preset solution target; If not, an optimization algorithm is used to generate a new simulation combination based on the global optimal solution and the corresponding simulation combination, and the process returns to step S1062.

[0009] In some embodiments, S104 includes the step of: Equivalent medium parameters are generated based on the aforementioned type of constraint conditions using effective medium theory. The first simulation constraint model is constructed based on the equivalent medium parameters and two types of constraints, wherein the simulation constraint model is a single-phase medium equivalent model.

[0010] In some embodiments, in S106, during the Xth simulation round, the first simulation constraint model is used for simulation; during the Yth simulation round, the second simulation constraint model is used for simulation; wherein, the second simulation constraint model is a multiphase medium model, and the second simulation constraint model is obtained by updating the first simulation constraint model using the latest simulation combination; wherein, X≤Y.

[0011] In some embodiments, X=1.

[0012] In some embodiments, S1061 includes: During the Xth round of simulation, a first number of first simulation combinations are generated based on the aforementioned type of constraint conditions. The first simulation combination includes: equivalent graphic duty cycle. During the Yth round of simulation, a second simulation combination of a second sub-quantity is generated based on the first type of constraint conditions. The second simulation combination includes: design graphic duty cycle.

[0013] In some embodiments, a first constraint range is used to limit the dispersion of the equivalent graphic duty cycle of the first sub-quantity, and a second constraint range is used to limit the dispersion of the design graphic duty cycle of the second sub-quantity.

[0014] In some embodiments, the duty cycle of the first waveguide pattern is in a first duty cycle range, and the non-functional area of ​​the object to be simulated is provided with at least one second waveguide pattern, the duty cycle of the second waveguide pattern being in a second duty cycle range. Correspondingly, before S100, the method further includes the following step: Calculate the scattering loss caused by the first waveguide pattern and the second waveguide pattern; Determine whether the scattering loss is greater than a preset scattering loss threshold; if yes, the first type of constraint includes: the graphic duty cycle of the first waveguide pattern and the graphic duty cycle of the second waveguide pattern; if no, the first type of constraint includes: the graphic duty cycle of the first waveguide pattern.

[0015] In another aspect, the present invention provides a graphic duty cycle design system, comprising: The first constraint module is used to obtain a class of constraints on the object to be simulated. The object to be simulated contains at least one first waveguide pattern. The class of constraints includes the duty cycle of the first waveguide pattern, wherein the duty cycle is calculated as follows: ; in, The area occupied by the waveguide region. This refers to the area occupied by the non-waveguide region; The second constraint module is used to select two types of constraint conditions according to the type of the object to be simulated. The two types of constraint conditions include auxiliary parameters used to describe the specifications of the object to be simulated. The model creation module is used to construct a simulation constraint model based on the first type of constraint conditions and the second type of constraint conditions. The simulation module is used to perform at least one round of simulation on the simulation constraint model using electromagnetic simulation methods to obtain the design evaluation results of the simulation constraint model. The design evaluation results include at least one simulation solution for defining the optical performance of the object to be simulated.

[0016] Beneficial technical effects: To address the issue of uneven adhesive layer thickness that may occur during the nanoimprinting process of complex waveguide patterns, this invention provides a method for simulating and evaluating waveguide pattern design schemes to facilitate the selection of waveguide patterns.

[0017] Specifically, this invention selects waveguide patterns and auxiliary parameters as two core constraints for constructing the simulation constraint model. In other words, this invention actually employs a multi-parameter simulation approach, namely, introducing the duty cycle of the waveguide pattern (and even multiple different waveguide patterns' duty cycles, uniformity, and specific waveguide dimensions) and auxiliary parameters for multi-parameter simulation. Furthermore, this invention provides a restrictive simulation method that progressively and hierarchically limits the simulation range during the simulation process to alleviate the problem of easily getting trapped in local solutions during multi-parameter simulation, while simultaneously improving the efficiency of multi-parameter simulation. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. The elements or parts in the drawings are not necessarily drawn to scale. Obviously, the drawings described below are some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0019] Figure 1 This is a schematic diagram of the waveguide pattern of a waveguide device in an exemplary embodiment; Figure 2 This is a schematic diagram of the waveguide pattern of a waveguide device in another exemplary embodiment; Figure 3 This is a schematic diagram of the graphic duty cycle design method in an exemplary embodiment of the present invention; Figure 4 This is a schematic diagram of the simulation method for the duty cycle of graphics in another exemplary embodiment of the present invention.

[0020] Summary of attached labeling and identification: 001. Multimode waveguide region; 002. Point waveguide; 003. Single-mode waveguide region; 004. Non-waveguide region; 005. Point waveguide. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0022] In this document, suffixes such as "module," "part," or "unit" used to denote elements are used only for the purpose of illustrative purposes and have no specific meaning in themselves. Therefore, "module," "part," or "unit" may be used interchangeably.

[0023] In this document, the terms "upper," "lower," "inner," "outer," "front," "rear," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the present invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0024] In this document, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0025] In this document, "and / or" includes any and all combinations of one or more of the listed related items.

[0026] In this article, "multiple" means two or more, that is, it includes two, three, four, five, etc.

[0027] As used in this specification, the term "about" typically means + / -5% of the value, more typically + / -4% of the value, more typically + / -3% of the value, more typically + / -2% of the value, even more typically + / -1% of the value, and even more typically + / -0.5% of the value.

[0028] In this specification, certain embodiments may be disclosed in a range-bound format. It should be understood that this "range-bound" description is merely for convenience and brevity and should not be construed as a rigid limitation on the disclosed range. Therefore, the description of a range should be considered as having specifically disclosed all possible subranges and the individual numerical values ​​within those ranges. For example, a description of the range 1-6 should be considered as having specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and the individual numbers within those ranges, such as 1, 2, 3, 4, 5, and 6. This rule applies regardless of the breadth of the range.

[0029] Waveguide patterns (or waveguide designs, or simply patterns or designs): In this paper, a "waveguide pattern" is a specific periodic or aperiodic structure in integrated optical or grating structures used to guide and control the propagation of light waves. For example, a waveguide pattern refers to a geometric structure formed in gratings, waveguide devices, or photonic crystals using micro- and nano-fabrication techniques (such as etching, deposition, and imprinting). These structures, through refractive index modulation or periodic arrangement, achieve directional coupling, mode selection, phase matching, or energy distribution modulation of light waves, thereby confining light to propagate along a specific path.

[0030] See Figure 1 As shown, this illustrates a conventional MMI (Multimode Interference) beamsplitter structure, which includes a multimode waveguide region 001, with single-mode waveguide regions 003 connected to both sides of the multimode waveguide region 001. The multimode waveguide region 001 and the single-mode waveguide region 003 are the functional areas of the beamsplitter. Surrounding these functional areas are dotted waveguide regions 005 (formed by spaced-apart dotted waveguides 002; the spaces between the dotted waveguides are non-waveguide regions 004, also known as hollow regions). The duty cycle refers to the area ratio of the waveguide region within the waveguide device.

[0031] The first waveguide pattern usually refers to the distribution pattern formed by the waveguide region in the object to be simulated.

[0032] For example, in some embodiments, the term "first waveguide pattern" herein refers to a geometric pattern formed by a multimode waveguide region 001, a single-mode waveguide region 003, or a combination of both. Correspondingly, with Figure 1 Taking the specifications shown as an example, the duty cycle (i.e., pattern duty cycle) of the multimode waveguide region 001 is D=1, and the duty cycle of the single-mode waveguide region 003 is D=0.2. The "second waveguide pattern" in this article refers to the geometric pattern formed by the arrangement of point-like waveguides.

[0033] The waveguide pattern formed by the dotted waveguide region 005 is also called a dummy pattern, which refers to a virtual structure or a dummy structure, or a non-functional structure added during chip manufacturing.

[0034] See Figure 2 As shown, a subwavelength grating MMI beam splitter structure is also illustrated. In this embodiment, the multimode waveguide region 001 adopts a subwavelength grating structure design. The multimode waveguide region 001 of the subwavelength grating MMI beam splitter uses a subwavelength grating waveguide structure with a grating period of 0.1 μm and a slot width of 0.05 μm. At the input and output ports, the waveguide gradually transitions from a subwavelength grating structure to a strip waveguide.

[0035] See Figure 1 Within an 8×8µm range, the traditional MMI beam splitter achieves a maximum duty cycle of 1 in the multimode waveguide region, while the output waveguide duty cycle is 0.2, indicating a large range of duty cycle variation. However, as... Figure 2 The maximum duty cycle of the MMI based on the subwavelength grating structure shown is 0.5, which reduces the duty cycle range.

[0036] In this invention, nanoimprint lithography is preferably used to prepare the above-mentioned complex waveguide pattern.

[0037] Specifically, when fabricating patterned waveguides using nanoimprint lithography, the etch barrier layer on the waveguide remains adhesive, but the designed pattern is formed by pressing a template (on which the shape of the waveguide pattern to be transferred) and then curing it with heat or UV. During the pressing process of the template, the deeper blank areas (i.e., the raised areas) push the imprinted adhesive to the shallower patterned areas, causing the adhesive layer to redistribute. However, the applicant noted that during nanoimprint lithography, if the width ratio of the blank area to the patterned area changes, it will affect the adhesive layer thickness in the patterned area and the residual adhesive thickness in the blank area. This leads to uneven thickness of the etch barrier layer (i.e., the adhesive layer), resulting in poor consistency in the etching depth of the entire chip.

[0038] In response, this invention provides a design method that can rapidly simulate the morphological design of the pattern area, thereby reducing the problem of uneven thickness of the etching barrier layer during nanoimprinting to a certain extent by improving the structural uniformity of the pattern area.

[0039] Example 1: See Figure 3 As shown, this invention provides a method for designing graphic duty cycles, including the following steps: S100, Obtain a set of constraints for the object to be simulated. The object to be simulated has at least one first waveguide pattern. The set of constraints includes the duty cycle of the first waveguide pattern, wherein the duty cycle is calculated as follows: ; in, The area occupied by the waveguide region. This refers to the area occupied by the non-waveguide region; In some embodiments, the object to be simulated can be an active waveguide device or a passive waveguide device.

[0040] In some embodiments, the object to be simulated can be a beam splitter or an arrayed waveguide grating (AWG).

[0041] S102, Select two types of constraints according to the type of the object to be simulated, the two types of constraints include auxiliary parameters used to describe the specifications of the object to be simulated; S104, construct a simulation constraint model based on the first type of constraint conditions and the second type of constraint conditions; S106, perform at least one round of simulation on the simulation constraint model using an electromagnetic simulation method to obtain the design evaluation result of the simulation constraint model, the design evaluation result including at least one simulation solution for defining the optical performance of the object to be simulated.

[0042] For example, in some embodiments, in the initial stage, user-inputted first-class and second-class constraints are selected as the initial framework, and an initial model (i.e., the simulation constraint model) is constructed based on the actual design requirements of the object to be simulated. In the initial model, the basic framework of the object to be simulated can be determined according to the constraints, such as if it is an MMI-type beam splitter; further, it can be determined to be a subwavelength grating structure MMI-type beam splitter. Subsequent multi-round simulations refer to the continuous iterative optimization of this simulation constraint model.

[0043] For example, in some embodiments, multiple general models can be pre-stored for different types of objects to be simulated. The general models can be adjusted by user-input constraints to generate the corresponding initial models.

[0044] It should be noted that, in order to perform rapid simulation evaluation of waveguide pattern design, this invention selects waveguide pattern and auxiliary parameters as two types of core constraints for constructing simulation constraint models. The number / type of auxiliary parameters can be selected based on the device type of the object to be simulated, or by comprehensively considering simulation requirements (such as simulation efficiency and simulation accuracy).

[0045] For example, taking a beam splitter as an example, the selected auxiliary parameters can be one or more of the following: the width of the multimode waveguide region, the width of the input waveguide and the output waveguide, the spacing between the input waveguides, the spacing between the output waveguides, etc.

[0046] Specifically, in the simulation process, the optical performance of a specific structural device (i.e., the simulation constraint model) is calculated based on electromagnetic simulation methods. These electromagnetic simulation methods refer to methods that solve Maxwell's equations using analytical and discrete mathematical methods to calculate the spatiotemporal distribution of the light field, and then deduce the device performance. For example, specific simulation methods can be one or more of the following: Finite-Difference Time-Domain (FDTD), Finite-Element Time-Domain (FEM) / Frequency-Domain (FPM), Beam Propagation (BPM), etc.

[0047] For example, in some embodiments, simulation calculations can be performed using one or more of the following software: COMSOL Multiphysics' Wave Optics (FEM) module; Rsoft CAD's BeamProp module (BPM algorithm), FullWave (FDTD) module, and FemSIM module (FEM); Ansys Lumerical's FDTD module (FDTD) and FEEM module (FEM algorithm); and Optiwave's OptiBPM module (BPM algorithm).

[0048] For example, in some embodiments, the simulation solution may be one or more of the following optical performance indicators: device insertion loss (IL), additional loss, extinction ratio (ER), return loss, beam splitting ratio, etc.

[0049] For example, in some embodiments, the simulation solution can be the value of a single performance metric. Alternatively, in other embodiments, it can be a combined value of two or more performance metrics.

[0050] For example, in some embodiments, the object to be simulated can be a grating. Correspondingly, when the type of the object to be simulated is a grating, the auxiliary parameters can be: the width of the multimode waveguide region in the grating, the width of the input waveguide and the output waveguide, the spacing, etc.

[0051] In some embodiments, see Figure 4 As shown, S106 includes the following steps: S1061, Define a first number of simulation combinations based on the first type of constraint and the second type of constraint, wherein the simulation combination includes: graphic duty cycle value and auxiliary value of auxiliary parameter; For example, in some embodiments, a user can input a range of graphic duty cycle values, and correspondingly, n (i.e., a first number) different graphic duty cycle values ​​can be randomly generated based on this range.

[0052] For example, in some embodiments, the user can input an auxiliary range value for any auxiliary parameter, and correspondingly, n different auxiliary values ​​can be randomly generated based on the range value.

[0053] Alternatively, in some embodiments, during the first round of simulation, the user can directly input the selected simulation combination, that is, set the values ​​of n sets of simulation combinations.

[0054] S1062, Perform simulation calculations on the simulation constraint model according to the simulation combination to obtain a first number of simulation solutions; wherein, the type of the simulation solution can be selected according to the type of the object to be simulated; For example, taking the MMI type beam splitter as an example, the suggested simulation solution type can be additional loss.

[0055] S1063, Select a local optimum from the first number of simulation solutions; For example, when the simulation solution has additional losses, the simulation solution with the minimum loss is selected as the local optimum.

[0056] S1064, obtain the current global optimal solution, determine whether the local optimal solution is greater than the global optimal solution, if so, update the local optimal solution to the global optimal solution, otherwise, keep the current global optimal solution.

[0057] For example, the local optimum in the first round is selected as the current global optimum, and the global optimum will be continuously updated in subsequent iterations.

[0058] Typically, in some embodiments, when the simulation solution is a loss-related index, such as insertion loss (IL), additional loss, or return loss, the smallest dominant parameter is selected as the local optimum, i.e., the local optimum can be the smallest dominant parameter in the current round; correspondingly, the global optimum is the smallest dominant parameter across all rounds. Specifically, after the first round of simulation, the current local optimum can be defined as the current global optimum.

[0059] Preferably, in this embodiment, in order to solve the problem of uneven blocking layer thickness that may occur in waveguide devices during nanoimprinting, the present invention will introduce uniformity constraints in the definition process of simulation combination.

[0060] For example, in some embodiments, a type of constraint condition further includes: the uniformity of the first waveguide pattern. Here, uniformity refers to the even distribution of waveguide regions within the waveguide pattern, such as... Figure 2Taking the multimode waveguide region 001 as an example, it is composed of multiple strip waveguides arranged at intervals. When the width similarity of the multiple strip waveguides is high and the spacing of the multiple adjacent strip waveguides is similar, the uniformity is considered to be high; conversely, the uniformity of the waveguide pattern in the multimode waveguide region is considered to be low.

[0061] In some embodiments, S106 further includes the step of: S1065, determine whether the global optimal solution is greater than the preset solution target; If not, an optimization algorithm is used to generate a new simulation combination based on the global optimal solution and the corresponding simulation combination, and the process returns to step S1062.

[0062] For example, in some embodiments, the optimization algorithm includes one or more of the following: Gradient-based optimization algorithms, such as the adjoint method; heuristic algorithms, such as genetic algorithms and particle swarm optimization; response surface algorithms, such as Bayesian optimization.

[0063] In some embodiments, S104 includes the step of: The effective dielectric theory is used to generate equivalent dielectric parameters (such as equivalent dielectric constant) based on the aforementioned type of constraint conditions. The first simulation constraint model is constructed based on the equivalent medium parameters and two types of constraints, wherein the simulation constraint model is a single-phase medium equivalent model.

[0064] For example, in some embodiments, a type of constraint includes: the duty cycle of at least one first waveguide pattern. Further, a type of constraint may also include the pattern type of the waveguide pattern (e.g., continuous fill type, such as...). Figure 1 The multimode waveguide region 001 in the image is composed of continuously filled waveguides; another example is the subwavelength grating type, such as... Figure 2 The multimode waveguide region 001 is composed of spaced long strip waveguides.

[0065] Based on the theory of effective electromagnetic medium, the designed waveguide region is equivalent to a uniform optical medium according to the periodic arrangement and duty cycle.

[0066] For example, based on the theory of effective media in electromagnetic fields, a structure with periodic arrangement, uniform duty cycle, and a period much smaller than the wavelength of light can be equivalently represented as a homogeneous optical medium with specific optical parameters (i.e., equivalent medium parameters). Correspondingly, the simulation constraint model is also a single-phase medium equivalent model.

[0067] This embodiment provides a two-stage simulation method. In the first stage, a single-phase dielectric equivalent model is used for simulation to quickly determine the initial adjustment direction of the waveguide pattern (such as the approximate duty cycle). In the second stage, a multiphase dielectric model (i.e., a simulation constraint model that realistically simulates different media such as waveguides and non-waveguide regions) is used to perform a refined evaluation of the duty cycle of the waveguide pattern.

[0068] Among them, the multiphase medium model refers to a medium composed of at least two different materials or phases (such as waveguides, gaseous media, etc.), whose electromagnetic properties (such as dielectric constant, permeability, conductivity, etc.) may exhibit non-uniform distribution in space.

[0069] In some embodiments, in S106, during the Xth simulation round, the first simulation constraint model is used for simulation; during the Yth simulation round, the second simulation constraint model is used for simulation; wherein, the second simulation constraint model is a multiphase medium model, and the second simulation constraint model is obtained by updating the first simulation constraint model using the latest simulation combination; wherein, X≤Y.

[0070] In some embodiments, X=1. That is, preferably, a unidirectional medium model is used for simulation in the first round of simulation.

[0071] In some embodiments, S1061 includes: In the Xth round of simulation (or the first simulation phase), a first number of first simulation combinations are generated based on the aforementioned type of constraints. These first simulation combinations include equivalent graphic duty cycles; specifically, these equivalent graphic duty cycles can be characterized using equivalent medium parameters. In other words, in this simulation phase, the simulation region is treated as a single-phase homogeneous medium.

[0072] During the Yth round of simulation (or the second simulation phase), a second set of simulation combinations with a second sub-quantity is generated based on the aforementioned type of constraints. The second set of simulation combinations includes: design graphic duty cycles.

[0073] In some embodiments, a first constraint range is used to limit the dispersion of the equivalent graphic duty cycle of the first sub-quantity, and a second constraint range is used to limit the dispersion of the design graphic duty cycle of the second sub-quantity.

[0074] Discreteness, also known as variability or dispersion, refers to the degree to which each data point in a set of data deviates from its central point (such as the mean or median). Discreteness can be used to measure whether the data distribution is compact, uniform, or exhibits significant or minimal fluctuations.

[0075] Preferably, in some embodiments, the first constraint range is greater than the second constraint range. That is, in the first simulation stage, the equivalent graphic duty cycle value can be taken in a larger range, while in the second simulation stage, the design graphic duty cycle value is taken in a smaller range.

[0076] In some embodiments, the duty cycle of the first waveguide pattern is in a first duty cycle range, and the non-functional area of ​​the object to be simulated is provided with at least one second waveguide pattern, the duty cycle of the second waveguide pattern being in a second duty cycle range. Correspondingly, before S100, the method further includes the following step: Calculate the scattering loss caused by the first waveguide pattern and the second waveguide pattern; Determine whether the scattering loss is greater than a preset scattering loss threshold; if yes, the first type of constraint includes: the graphic duty cycle of the first waveguide pattern and the graphic duty cycle of the second waveguide pattern; if no, the first type of constraint includes: the graphic duty cycle of the first waveguide pattern.

[0077] For example, in some embodiments, the first duty cycle is larger than the second duty cycle.

[0078] For example, in some embodiments, the first waveguide pattern mainly refers to the waveguide pattern set in the functional area (such as the multimode waveguide area or the single-mode waveguide area) of the waveguide device. The size of the functional area is usually required to be no less than 20mm × 20mm, and the duty cycle of the pattern in the functional area and the non-functional area needs to be within a certain range (typically 0.3~0.7). Therefore, in this embodiment, it is possible to try filling the blank areas of the non-functional area with waveguide patterns to increase the duty cycle, as shown above. Figure 1 The image shows an example of filling a dummy graphic.

[0079] Specifically, a dummy pattern is selected to fill the blank areas of the non-functional region (typically 3-6 μm away from the waveguide) to ensure that the uniformity of the duty cycle in the local area (a box range with a side length of 8-30 μm) meets the requirements.

[0080] In some embodiments, the simulation object is provided with at least two first waveguide patterns. Correspondingly, the type of constraint includes: the graphic duty cycle of the at least two first waveguide patterns, and the regional attributes of the first waveguide patterns, which may include: size or position. Correspondingly, these regional attributes can be further incorporated into the simulation constraints during the simulation process.

[0081] For example, to meet some complex device design requirements, additional functions may be added to the conventional MMI type beam splitter. For instance, the beam splitter may be required to be polarization-independent, or other complex characteristics may be required. Different patterns may be set in the multimode waveguide region, such as dividing it into different long strip waveguides in the lateral or longitudinal direction. In this case, different patterns have different equivalent dielectric constants.

[0082] In some embodiments, different patterned regions can be prepared using different materials, resulting in different dielectric constants.

[0083] In some embodiments, it also includes: The pattern type is determined based on the first waveguide pattern, wherein the pattern type includes one or more of the following: holes, dot matrix, and lines; The size of the first quantity is determined based on the pattern type.

[0084] Furthermore, the simulated value is the optical loss performance.

[0085] In this embodiment, appropriately selecting the first quantity for different pattern types helps to constrain the simulation range to a certain extent during the simulation process. For example, different recommended values ​​for the first quantity are preset for different pattern types.

[0086] It should be noted that, as waveguide devices become increasingly complex—for example, waveguide devices may contain multiple different waveguide patterns—and in high-precision equipment applications, the loss requirements for waveguide devices are extremely stringent. These complex design requirements result in very high computational pressure during actual simulation calculations, demanding very high simulation computing power.

[0087] To address this issue, for the simulation of complex waveguide devices under high simulation pressure, this invention selects pattern type as the basis for constraining the simulation scale. The purpose of this constraint is to limit the number of simulation combinations generated in each round of simulation based on the pattern type (equivalent to constraining the simulation interval, i.e., limiting the population size). This pattern type-based constraint model can improve simulation efficiency to a certain extent, while also designing reasonable constraint ranges for different simulation paths, thus reconciling the conflict between simulation efficiency requirements and the reliability requirements of simulation results.

[0088] From another perspective, this invention introduces pattern types and a two-stage training model to limit the range and discreteness of variables (i.e., simulation combinations), thereby alleviating to some extent the problem of easily getting trapped in local solutions during multi-parameter simulation (especially in the case of multi-waveguide pattern simulation).

[0089] Next, taking Figure 2 (sub - wavelength grating multimode interference beam splitter) as an example, the simulation process will be exemplarily described as follows: The multimode waveguide region of the beam splitter is created by parametric modeling. The tooth width a of the grating (i.e., the width of the long - strip waveguide) and the duty cycle D are taken as variables (i.e., a type of constraint condition), and the grating period is Lp = a / D. The second - type constraint conditions also include the width of the multimode waveguide region, the width and spacing of the input and output waveguides, etc.

[0090] Based on the optimization algorithm, trial solutions are generated within the constraint conditions, that is, the simulation combinations of independent variables. For the duty - cycle variable, the constraint condition is that the duty cycle is between the upper and lower limits Dmin < D < Dmax (i.e., D belongs to the first duty - cycle range). Then, the device structure is determined by the independent variables, and the optical performance of the device, such as additional loss and splitting ratio, is calculated based on the simulation method. The fitness function is taken as a single performance parameter, a combination of multiple performance parameters (such as multiplication - addition combination, etc.), a combination of performance parameters and duty cycle, etc. For example, the fitness FOM = A*EL + B*f(D), where EL is the additional loss, f(D - Dopt) is a decreasing function of the difference between the duty cycle D and the preferred value Dopt, and A and B are positive weight values (which can be preset by the user).

[0091] As a special case, the MMI region can be divided into multiple regions, and different grating tooth widths an and duty cycles Dn are set for each region.

[0092] As a special case, the lines of the sub - wavelength grating can also be changed to a rectangular dot - matrix structure with length a and width b, and the length a, width b of the rectangle, and the two - dimensional duty cycles Dx, Dy are taken as variables (i.e., as a type of constraint condition). Thus, the two - dimensional periods of the dot - matrix are Lx = a / Dx and Ly = b / Dy.

[0093] Embodiment 2: The present invention also provides a graphic duty - cycle design system, including: A first constraint module, configured to obtain a first - type constraint condition of the object to be simulated, where at least one first waveguide pattern is provided in the object to be simulated, and the first - type constraint condition includes: the graphic duty - cycle of the first waveguide pattern, where the calculation method of the graphic duty - cycle is as follows: ; Where is the area occupied by the waveguide region, is the area occupied by the non - waveguide region; A second constraint module, configured to select a second - type constraint condition according to the type of the object to be simulated, and the second - type constraint condition includes auxiliary parameters for describing the specifications of the object to be simulated; The model creation module is used to construct a simulation constraint model based on the first type of constraint conditions and the second type of constraint conditions. The simulation module is used to perform at least one round of simulation on the simulation constraint model using electromagnetic simulation methods to obtain the design evaluation results of the simulation constraint model. The design evaluation results include at least one simulation solution for defining the optical performance of the object to be simulated.

[0094] It is understood that the system in this invention can be used to implement the method steps in any one or more of the above embodiments, and will not be repeated here.

[0095] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0096] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a computer terminal (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0097] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A method for designing graphic duty cycle, characterized in that, Including the following steps: S100, Obtain a type of constraint condition for the object to be simulated. The object to be simulated has at least one first waveguide pattern. The type of constraint condition includes: the graphic duty cycle of the first waveguide pattern, wherein the graphic duty cycle is calculated as follows: ; in, The area occupied by the waveguide region. The area occupied by the non-waveguide region; S102, Select two types of constraints according to the type of the object to be simulated, the two types of constraints include auxiliary parameters used to describe the specifications of the object to be simulated; S104, Construct a simulation constraint model based on the first type of constraint and the second type of constraint; S106, The simulation constraint model is simulated at least once using an electromagnetic simulation method to obtain the design evaluation result of the simulation constraint model. The design evaluation result includes at least one simulation solution for defining the optical performance of the object to be simulated.

2. The method according to claim 1, characterized in that, S106 includes the following steps: S1061, Define a first number of simulation combinations based on the first type of constraint and the second type of constraint, wherein the simulation combination includes: graphic duty cycle value and auxiliary value of auxiliary parameter; S1062, Perform simulation calculations on the simulation constraint model according to the simulation combination to obtain a first number of simulation solutions, wherein the type of the simulation solution is selected according to the type of the object to be simulated; S1063, Select a local optimum from the first number of simulation solutions; S1064, obtain the current global optimal solution, determine whether the local optimal solution is greater than the global optimal solution, if so, update the local optimal solution to the global optimal solution, otherwise, keep the current global optimal solution.

3. The method according to claim 2, characterized in that, S106 also includes the following steps: S1065, determine whether the global optimal solution is greater than the preset solution target; If not, an optimization algorithm is used to generate a new simulation combination based on the global optimal solution and the corresponding simulation combination, and the process returns to step S1062.

4. The method according to claim 2, characterized in that, S104 includes the following steps: Equivalent medium parameters are generated based on the aforementioned type of constraint conditions using effective medium theory. The first simulation constraint model is constructed based on the equivalent medium parameters and two types of constraints, wherein the simulation constraint model is a single-phase medium equivalent model.

5. The method according to claim 4, characterized in that, In S106, during the Xth simulation round, the first simulation constraint model is used for simulation; during the Yth simulation round, the second simulation constraint model is used for simulation; wherein, the second simulation constraint model is a multiphase medium model, and the second simulation constraint model is obtained by updating the first simulation constraint model using the latest simulation combination; wherein, X≤Y.

6. The method according to claim 5, characterized in that, X=1。 7. The method according to claim 5, characterized in that, S1061 includes: During the Xth round of simulation, a first number of first simulation combinations are generated based on the aforementioned type of constraint conditions. The first simulation combination includes: equivalent graphic duty cycle. During the Yth round of simulation, a second simulation combination of a second sub-quantity is generated based on the first type of constraint conditions. The second simulation combination includes: design graphic duty cycle.

8. The method according to claim 7, characterized in that, A first constraint range is used to limit the dispersion of the equivalent graphic duty cycle value of the first sub-quantity, and a second constraint range is used to limit the dispersion of the design graphic duty cycle value of the second sub-quantity.

9. The method according to claim 1, characterized in that, The first waveguide pattern has a duty cycle within a first duty cycle range. The non-functional area of ​​the object to be simulated is provided with at least one second waveguide pattern, and the duty cycle of the second waveguide pattern is within a second duty cycle range. Correspondingly, before S100, the following step is also included: Calculate the scattering loss caused by the first waveguide pattern and the second waveguide pattern; Determine whether the scattering loss is greater than a preset scattering loss threshold; If yes, then the first type of constraint includes: the graphic duty cycle of the first waveguide pattern and the graphic duty cycle of the second waveguide pattern; if no, then the first type of constraint includes: the graphic duty cycle of the first waveguide pattern.

10. A graphic duty cycle design system, characterized in that, include: The first constraint module is used to obtain a class of constraints on the object to be simulated. The object to be simulated contains at least one first waveguide pattern. The class of constraints includes the duty cycle of the first waveguide pattern, wherein the duty cycle is calculated as follows: ; in, The area occupied by the waveguide region. The area occupied by the non-waveguide region; The second constraint module is used to select two types of constraint conditions according to the type of the object to be simulated. The two types of constraint conditions include auxiliary parameters used to describe the specifications of the object to be simulated. The model creation module is used to construct a simulation constraint model based on the first type of constraint conditions and the second type of constraint conditions. The simulation module is used to perform at least one round of simulation on the simulation constraint model using electromagnetic simulation methods to obtain the design evaluation results of the simulation constraint model. The design evaluation results include at least one simulation solution for defining the optical performance of the object to be simulated.

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