CN115166900A - Grating antenna and design method thereof - Google Patents
Grating antenna and design method thereof Download PDFInfo
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Abstract
The invention discloses a grating antenna design method, which comprises the steps of establishing a uniform waveguide grating antenna model; presetting a radiation angle alpha and the number m of grating grooves to obtain a far-field radiation pattern of the uniform waveguide grating antenna model; obtaining the optimized width of the grating groove according to the far field radiation pattern of the uniform waveguide grating antenna model
The insertion loss IR of a single grating groove and the wavelength lambda of light transmitted in the uniform waveguide grating antenna model; establishing a single waveguide grating antenna model; obtaining far-field radiation pattern data of the single waveguide grating antenna model; determining the number n of grating grooves in the target waveguide grating antenna by utilizing the IR and the optical power of the output port; establishing far field direction of waveguide grating antennaGraph theory model, far field radiation pattern data, IR, lambda, and the like of the single waveguide grating antenna model,
And n, optimizing the position of each grating groove to obtain a position distribution table of each grating groove so as to obtain the target waveguide grating antenna.
Description
Technical Field
The invention belongs to the technical field of optical antennas, and relates to a grating antenna and a design method thereof.
Background
The silicon-based laser phased array consists of an optical antenna unit array, a power division network, a phase shifter, an attenuator and the like. The optical antenna unit is a key component, and the radiation characteristic of the optical antenna unit has important influence on the laser phased array. The one-dimensional silicon-based laser phased array realizes scanning of one dimension by adjusting the phase of the optical antenna unit and realizes scanning of the other dimension by adjusting the working wavelength. The optical antenna units in the one-dimensional silicon-based laser phased array are usually grating antennas. The grating antenna radiates light in the waveguide into free space by etching the grating. At present, grating antennas all adopt uniformly etched gratings, namely, the width of a grating groove and the grating period in one grating antenna are fixed and unchanged, so that the design of the grating antenna is limited.
Application No.: 202010256764.2 "a design method of grating antenna" discloses a design method of grating antenna, which records the current grating period, etching width and radiation ratio under the condition that the radiation angle satisfies the preset condition, and fits the data, so as to design the grating antenna without involving the design method of non-uniform period grating antenna. Application No.: 202011529276.0 "waveguide grating antenna array for optical phased array and its preparation method" covers a covering layer with a spatial curved surface on a waveguide grating, increases the light beam emergence angle, and does not relate to a non-uniform period grating antenna design method.
Through the search of non-patent documents, the document "high-precision non-aliasing beam control" (optical, vol.3, no.8, 2016, pp887-890) proposes a uniformly etched grating antenna, and does not relate to a non-uniform waveguide grating antenna design method. The document "a switch-based two-dimensional integrated beam scanning device for lidar" (cloeo 2019, jth 2a.73), proposes an arc-shaped grating antenna, which does not involve etching a grating antenna on a waveguide. The document 'monolithic optical phased array on a wafer-level silicon-based photon/CMOS three-dimensional integrated platform' (IEEE Journal of Solid-State Circuits, vol.54, no.11, 2019, pp3061-3074) provides a non-uniform period grating antenna, the grating period and the size of a groove of the non-uniform period grating antenna are in a gradually-increased form, the growth rule is fixed, the grating groove is etched on the side surface of a waveguide, and a complete method for designing the non-uniform waveguide grating antenna is not involved.
At present, in reports at home and abroad, a complete method for designing a non-uniform waveguide grating antenna is not available.
Disclosure of Invention
The invention aims to overcome the defects and provides a grating antenna design method which comprises the steps of establishing a uniform waveguide grating antenna model; presetting a radiation angle alpha and the number m of grating grooves to obtain a far-field radiation pattern of the uniform waveguide grating antenna model; obtaining the optimized width of the grating groove according to the far field radiation pattern of the uniform waveguide grating antenna model
The insertion loss IR of a single grating groove and the wavelength lambda of light transmitted by the light in the uniform waveguide grating antenna model; establishing a single waveguide grating antenna model; obtaining far-field radiation pattern data of the single waveguide grating antenna model; determining the number n of grating grooves in the target waveguide grating antenna by utilizing the IR and the optical power of the output port; establishing a far-field pattern theoretical model of the waveguide grating antenna, and introducing far-field radiation pattern data, IR, lambda, and the like of the single waveguide grating antenna model,
And n, optimizing the position of each grating groove to obtain a position distribution table of each grating groove in the target waveguide grating antenna, thereby obtaining the target waveguide grating antenna. The invention removes the limitation of fixed grating period on the grating antenna design, and makes the grating antenna design more flexible.
In order to achieve the purpose of the invention, the invention provides the following technical scheme:
a grating antenna design method comprises the following steps:
s1, establishing a waveguide model, and uniformly etching grating grooves on the upper surface of the waveguide model to form a uniform waveguide grating antenna model; presetting a radiation angle alpha and the number m of grating grooves, setting one end of a uniform waveguide grating antenna model as an input port and the other end as an output port, and simulating the uniform waveguide grating antenna model to obtain a far-field radiation pattern of the uniform waveguide grating antenna model;
s2, according to the far field radiation pattern of the uniform waveguide grating antenna model, the width of the grating groove in the uniform waveguide grating antenna model is measured
Optimizing to obtain the optimized grating groove width when the far field radiation directional diagram main lobe points to the preset radiation angle alpha
The insertion loss IR of a single grating groove and the wavelength lambda of light transmitted by the light in the uniform waveguide grating antenna model; the preset radiation angle alpha is equal to the beam main lobe pointing angle theta of the target waveguide grating antenna m ；
S3, establishing a single waveguide grating antenna model only comprising 1 grating groove, wherein the width of the grating groove in the single waveguide grating antenna model is equal to the optimized grating groove width in the uniform waveguide grating antenna model; simulating the single waveguide grating antenna model, and deriving far-field radiation pattern data in a simulation result;
s4, determining the number n of grating grooves in the target waveguide grating antenna by using the insertion loss IR of a single grating groove and the optical power of an output port;
s5, establishing a far field directional diagram theoretical model of the waveguide grating antenna;
leading in far-field radiation pattern data of a single waveguide grating antenna model, insertion loss IR of a single grating groove in a uniform waveguide grating antenna model, optical wavelength lambda of light transmitted in the uniform waveguide grating antenna model and optimized grating groove width in a far-field pattern theoretical model of the waveguide grating antenna
And the number n of grating grooves in the target waveguide grating antenna;
pointing theta = theta in a far-field pattern theoretical model of a waveguide grating antenna m The position of each grating groove is optimized by taking the maximum value obtained by the radiation power of the main lobe or the minimum value obtained by the level of the side lobe as an optimization target to obtain a position distribution table of each grating groove in the target waveguide grating antenna;
s6, according to the position distribution table of each grating groove in the target waveguide grating antenna, the position of each grating groove etched on the optical waveguide is set, and the target waveguide grating antenna is obtained.
Further, according to the far field radiation pattern of the uniform waveguide grating antenna model, the width of the grating groove in the uniform waveguide grating antenna model is adjusted
And optimizing, wherein when the main lobe of the far-field radiation pattern points to a preset radiation angle alpha, an initial value of lambda is generated by the following formula:
wherein theta is c Is the radiation angle, lambda, in the cladding of the uniform waveguide grating antenna model 0 Is the central wavelength of operation in free space, θ a For radiation angles in air, i.e. preset radiation angles alpha, n e Effective refractive index of grating groove region for uniform waveguide grating antenna model, n c Refractive index of the cladding layer of the uniform waveguide grating antenna model, n a Is the refractive index of air.
Further, assuming that the optical power of the input port is 1, the insertion loss IR of a single grating groove in the uniform waveguide grating antenna model is determined according to the following formula:
wherein S is 21 The insertion loss between an input port and an output port of the uniform waveguide grating antenna model is obtained.
Further, when the optical wavelength λ transmitted by the light in the uniform waveguide grating antenna model changes in a 2 π phase in the uniform waveguide grating antenna model according to the electric field component of the light, the distance of transmission of the electric field component of the light in the uniform waveguide grating antenna model is obtained.
Furthermore, when a far-field directional pattern theoretical model of the grating antenna is established, one grating groove is regarded as an antenna unit, and one grating antenna is regarded as an array formed by the grating grooves;
the far-field pattern theoretical model | F (theta) | of the grating antenna is as follows:
|F(θ)|＝|F e (θ)|·|F a (θ)|；
wherein theta is a radiation angle between-180 degrees and 180 degrees, and F e (theta) | is the far field radiation pattern data of the single waveguide grating antenna model, F a (θ) is the array factor:
wherein, I i Obtaining the field intensity amplitude of an antenna unit formed by the ith grating groove in the grating antenna and the insertion loss IR of a single grating groove in the uniform waveguide grating antenna model; j represents an imaginary number; k is the wave vector in vacuum; d is a radical of i The distance between the ith grating groove and the 1 st grating groove in the grating antenna is set, i is more than or equal to 1 and is less than or equal to n; beta is a i The initial phase of the input light of the antenna unit formed by the ith grating groove in the grating antenna is according to d i And a wave vector k 'transmitted by the light in the uniform waveguide grating antenna model, wherein k' is obtained according to the wavelength lambda of the light transmitted by the light in the uniform waveguide grating antenna model.
Further, the width of the grating groove
The following formula is satisfied:
further, in the above-mentioned case,
β i ＝k′d i 。
further, the number n of grating grooves in the target waveguide grating antenna is determined by using the insertion loss IR of a single grating groove and the optical power of an output port according to the following formula:
(1-IR) n ＝1％；
and optimizing the position of each grating groove by adopting an iterative algorithm for solving a multi-extreme problem to obtain a position distribution table of each grating groove in the target waveguide grating antenna, wherein the maximum value of the main lobe radiation power or the minimum value of the side lobe level is taken as an optimization target.
Further, grating grooves are evenly etched on the upper surface of the waveguide model, and a uniform waveguide grating antenna model is formed by combining material parameters and structure size parameters of a uniform waveguide grating antenna, wherein the material parameters of the uniform waveguide grating antenna comprise the refractive index of a material, and the structure size parameters of the uniform waveguide grating antenna comprise the length and width of the uniform waveguide grating antenna, the grating period, the width of the grating grooves, the number of the grating grooves and the duty ratio; when the width of the grating groove in the uniform waveguide grating antenna model is optimized according to the far-field radiation directional diagram of the uniform waveguide grating antenna model, the length and the width of the uniform waveguide grating antenna, the number of the grating grooves and the duty ratio are preset fixed values, and the grating period is twice the width of the grating groove.
A grating antenna is obtained by the grating antenna design method.
Compared with the prior art, the invention has at least one of the following beneficial effects:
(1) The invention provides a design method of a non-uniform waveguide grating antenna, which removes the limitation of a fixed grating period on the design of the grating antenna, enables the design of the grating antenna to be more flexible, can design the grating antenna with expected beam pointing direction, and has important application prospect in a silicon-based laser phased array;
(2) The invention provides that the insertion loss of grating grooves with the same size in the waveguide grating antenna is the same and is irrelevant to the position of the grating grooves in the waveguide grating antenna;
(3) The invention provides a new method for taking each grating groove as an antenna unit, taking a waveguide grating antenna as an array consisting of the grating grooves, taking a far-field radiation pattern formula of an antenna array as a far-field radiation pattern formula of the waveguide grating antenna, and providing a variable I in the formula i And beta i The unique calculation formula of (a);
(4) The invention provides a method for deriving far field radiation pattern data of a single waveguide grating antenna simulated by three-dimensional electromagnetic field simulation software, and the data is used as an antenna unit far field radiation pattern in a target waveguide grating antenna far field radiation pattern formula, so that an optimization result is more reliable;
(5) The invention utilizes the simulation result of the waveguide grating antenna unit to analyze the result of each iteration and updates the position parameters of each grating groove in the target grating antenna, thereby improving the calculation accuracy;
(6) The invention provides a method for performing iterative optimization on the position of the grating groove by using a multi-extreme value iterative algorithm, which is more flexible than the traditional design.
Drawings
FIG. 1 is a flow chart of a method for designing a grating antenna according to the present invention;
FIG. 2 is a schematic diagram of a uniform waveguide grating antenna according to embodiment 1 of the present invention;
fig. 3 is a schematic view of the radiation angle of the uniform waveguide grating antenna according to embodiment 1 of the present invention;
FIG. 4 is a schematic view of a single waveguide grating antenna model according to embodiment 1 of the present invention;
fig. 5 is a schematic diagram of a non-uniform target waveguide grating antenna obtained in embodiment 1 of the present invention.
Detailed Description
The features and advantages of the present invention will become more apparent and apparent from the following detailed description of the invention.
The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.
The invention provides a method for designing a non-uniform waveguide grating antenna, which determines parameter values in three-dimensional electromagnetic field software, optimizes grating groove positions in programming software, and finally completes antenna model design in the three-dimensional electromagnetic field software, thereby removing the limitation of fixed grating period on grating antenna design, enabling the grating antenna design to be more flexible, being capable of designing a grating antenna with an expected radiation directional pattern and having important application prospect in a silicon-based laser phased array.
As shown in fig. 1, the method for designing a grating antenna of the present invention includes the following steps:
s1, establishing a uniform waveguide grating antenna simulation model in three-dimensional electromagnetic field simulation software, wherein the radiation angle alpha of the uniform waveguide grating antenna is set according to requirements, the uniform waveguide grating antenna comprises m grating grooves which are uniformly distributed, and m is more than or equal to 40;
s2, carrying out simulation optimization in three-dimensional electromagnetic field simulation software by using the uniform waveguide grating antenna simulation model, specifically, carrying out simulation optimization on the width of a grating groove in the uniform waveguide grating antenna model
And optimizing, wherein the initial value of the lambda is determined by the following formula:
wherein theta is c Is the radiation angle, lambda, in the cladding of the uniform waveguide grating antenna model 0 Is the central wavelength of operation in free space, θ a For radiation angles in air, i.e. preset radiation angles alpha, n e Effective refractive index of grating groove region of uniform waveguide grating antenna model, n c Refractive index of the cladding layer of the uniform waveguide grating antenna model, n a Is the refractive index of air.
When the main lobe pointing angle of the far-field radiation directional diagram is equal to the preset radiation angle alpha, the optimization is completed, and the optimized width of the grating groove is obtained
Setting the optical power of an input port of a uniform waveguide grating antenna model to be 1 in three-dimensional electromagnetic field simulation software, and obtaining the insertion loss S between the input port and the output port of the uniform waveguide grating antenna model in a simulation result 21 By means of S 21 And calculating the insertion loss IR of each grating groove in the uniform waveguide grating antenna according to the following formula:
wherein m is the number of grating grooves contained in the uniform waveguide grating antenna, S 21 The insertion loss between an input port and an output port of the uniform waveguide grating antenna model is obtained.
Setting a uniform waveguide grating antenna model in three-dimensional electromagnetic field simulation software to display electric field distribution, and measuring the distance between 2 adjacent wave crests or 2 wave troughs in an electric field, namely the wavelength lambda of light in the uniform waveguide grating antenna.
S3, establishing a single waveguide grating antenna model, wherein the single waveguide grating antenna model only comprises 1 grating groove, the width of the grating groove in the single waveguide grating antenna model is equal to the width of the optimized grating groove in the uniform waveguide grating antenna, and the derived far-field radiation pattern data format is txt;
s4, setting the number of grating grooves in the target waveguide grating antenna as n, and using the insertion loss IR obtained in S2, (1-IR) n If the power of the output port of the target waveguide grating antenna is theoretically equal to 1% of the power of the input port, the influence of the added grating grooves on the radiation characteristics of the target waveguide grating antenna can be ignored even if the number n of the grating grooves is increased, and the calculated amount is increased on the contrary;
s5, establishing a far-field directional pattern theoretical model program of the target waveguide grating antenna in programming software, wherein a far-field radiation directional pattern function in the program is established according to the following formula:
|F(θ)|＝|F e (θ)|·|F a (θ)|；
wherein theta is a radiation angle, theta is more than or equal to-180 degrees and less than or equal to 180 degrees, and F is e (theta) | is the far field radiation pattern data of the single waveguide grating antenna model, F a (θ) is the array factor:
wherein, I i The field intensity amplitude of an antenna unit formed by the ith grating groove in the grating antenna is obtained by utilizing the insertion loss IR of a single grating groove in the uniform waveguide grating antenna model; j represents an imaginary number; k is the wave vector in vacuum; d is a radical of i The distance between the ith grating groove and the 1 st grating groove in the grating antenna is set, and 1 grating i is less than or equal to n; beta is a i The initial phase of the input light of the antenna unit formed by the ith grating groove in the grating antenna is according to d i And the wave vector of light transmission in the uniform waveguide grating antenna modelk' is obtained according to the wavelength λ of light transmitted by the light in the uniform waveguide grating antenna model, and specifically comprises the following steps:
initial phase beta of ith antenna element i In relation to the position of the ith antenna element, the following formula is used for calculation:
β i ＝k′d i ；
field intensity amplitude I of antenna unit formed by ith grating groove i Calculated according to the following formula:
setting a desired beam pointing angle of a target waveguide grating antenna to theta m IR, λ and obtained in step S2
Substituting the data of the far-field radiation pattern of the single waveguide grating antenna unit and n into a grating antenna far-field radiation pattern model program, wherein the program points theta = theta in the far-field radiation pattern m The beam at (a) is taken as a main lobe, and the value thereof is taken as the main lobe radiation power in theta m As a center, searching for a side lobe in a range outside the first zero beam width, obtaining a side lobe position and a corresponding power value by using a function of searching for an extremum in programming software, searching for a maximum value in the power values, taking a ratio of the maximum value to main lobe radiation power as a side lobe level, taking the maximum value of the main lobe radiation power or the minimum value of the side lobe level as an optimization target according to actual application requirements, setting the position of a grating groove as a parameter to be optimized in a program, selecting an iterative algorithm for solving a multi-extremum problem, setting iteration times, wherein the more the iteration times, the larger the main lobe radiation power or the smaller the side lobe level (related to the selected optimization target), the better the optimization result, but the longer the consumed calculation time and the more the iteration timesAfter the number is increased to a certain degree, the optimization result is almost not promoted any more, the calculation time is mainly influenced by the hardware performance of a computer, the execution time of a program and the value of n, the number of iterations can be preset to be 100, the number of iterations is adjusted according to the simulation result and the consumed time, and finally, a position distribution table of n grating grooves in the target grating antenna is obtained;
s6, setting the positions of the grating grooves etched on the optical waveguide according to the position distribution table of the n grating grooves in the target grating antenna, and obtaining the non-uniform target grating antenna.
Further, in S1, the length and width of the grating antenna, the number of grating grooves, and the duty ratio (for example, 50%) are preset, the radiation angle is preset, the grating grooves are etched on the upper surface of the waveguide to generate the grating antenna, a uniform waveguide grating antenna simulation model is established in three-dimensional electromagnetic field simulation software, one end of the uniform waveguide grating antenna simulation model is set as an input port, and the other end of the uniform waveguide grating antenna simulation model is set as an output port, so as to simulate the uniform waveguide grating antenna;
further, in S5, in the far-field pattern theoretical model of the waveguide grating antenna, each grating groove in the grating antenna is taken as an antenna unit, and the grating antenna is regarded as a linear array formed by the grating grooves.
The design method of the grating antenna has no limit on grating antenna materials, no limit on a multi-extreme optimization algorithm of iterative grating groove positions and no limit on simulation software of a grating antenna model, and all changes to the grating antenna materials, the antenna simulation software and the optimization algorithm of the grating groove positions in the invention are all included in the protection scope of the invention. The grating antenna design method provided by the invention can remove the limitation of uniform grating period on the grating antenna design, so that the grating antenna design is more flexible, and the grating antenna design method has important significance on designing the grating antenna with the expected directional diagram.
Example 1:
FIG. 2 is a top view of a simulation model of a uniform waveguide grating antenna including conventional silicon and dioxide, which is built in a three-dimensional electromagnetic field simulation software according to this embodimentSilicon material, setting working wavelength at 1550nm in software, adding Si and SiO 2 The refractive indices of the materials were set to 3.48 and 1.52, respectively. The waveguide grating antenna has a width of 450nm and a thickness of 220nm, and grating grooves are uniformly etched on the silicon waveguide, the depth of the grating grooves can be 70nm, and the width of the grating grooves can be 70nm
The grating period is Λ. And a substrate is added below the grating antenna, a coating layer covers the grating antenna, and the substrate and the coating layer are made of silicon dioxide. An input port is arranged on the left side of the grating antenna, and an output port is arranged on the right side of the grating antenna. And starting simulation after the corresponding simulation setting is finished.
As shown in fig. 3, θ c The beam radiation of the simulated uniform waveguide grating antenna is in theta for the radiation angle in the cladding of the uniform waveguide grating antenna model a The angle radiates into the air.
After the simulation is finished, measuring the distance between 2 adjacent wave crests or 2 wave troughs of the electric field of the grating antenna, and determining the wavelength of light in the grating antenna.
Observing insertion loss S between input port and output port of uniform waveguide grating antenna in simulation software 21 According to S 21 And the number m of grating grooves, and calculating the insertion loss caused by averaging the single grating grooves, namely the energy radiated into the free space.
As shown in fig. 4, a grating antenna with only one grating groove etched is designed in three-dimensional electromagnetic field simulation software, a single waveguide grating antenna model is established, and far-field radiation pattern data of the single waveguide grating antenna model is derived through simulation.
A grating antenna far-field radiation direction diagram model is established in programming software, the position of a grating groove can be optimized by using an iterative algorithm for solving a multi-extreme-value problem, a light beam main lobe pointing angle is preset, and the amplitude of an antenna main lobe or the level of an auxiliary lobe is used as an optimization target. One grating groove is considered as one antenna element. And setting iteration times, and optimizing to obtain a grating groove position distribution table.
As shown in fig. 5, in the three-dimensional electromagnetic field simulation software, the positions of the etched grating grooves are set according to the position distribution table calculated in the programming, and the grating antenna design is completed.
The grating antenna design method provided by the invention eliminates the limitation of uniform grating period on grating antenna design, is more flexible in grating antenna design, can be used for optimally designing the grating antenna with an expected directional diagram, and has important significance in designing grating antennas with different application requirements.
The invention has been described in detail with reference to specific embodiments and illustrative examples, but the description is not intended to be construed in a limiting sense. Those skilled in the art will appreciate that various equivalent substitutions, modifications or improvements may be made to the embodiments and implementations of the invention without departing from the spirit and scope of the invention, and are within the scope of the invention. The scope of the invention is defined by the appended claims.
Those skilled in the art will appreciate that those matters not described in detail in the present specification are well known in the art.
Claims (10)
1. A method for designing a grating antenna, comprising:
s1, establishing a waveguide model, and uniformly etching grating grooves on the upper surface of the waveguide model to form a uniform waveguide grating antenna model; presetting a radiation angle alpha and the number m of grating grooves, setting one end of a uniform waveguide grating antenna model as an input port and the other end as an output port, and simulating the uniform waveguide grating antenna model to obtain a far-field radiation pattern of the uniform waveguide grating antenna model;
s2, according to the far-field radiation pattern of the uniform waveguide grating antenna model, the width of the grating groove in the uniform waveguide grating antenna model is adjusted
Optimizing to obtain the optimized grating groove width when the far field radiation directional diagram main lobe points to the preset radiation angle alpha
The insertion loss IR of a single grating groove and the wavelength lambda of light transmitted in the uniform waveguide grating antenna model; the preset radiation angle alpha is equal to the beam main lobe pointing angle theta of the target waveguide grating antenna m ；
S3, establishing a single waveguide grating antenna model only comprising 1 grating groove, wherein the width of the grating groove in the single waveguide grating antenna model is equal to the width of the optimized grating groove in the uniform waveguide grating antenna model; simulating the single waveguide grating antenna model, and deriving far-field radiation pattern data in a simulation result;
s4, determining the number n of grating grooves in the target waveguide grating antenna by using the insertion loss IR of a single grating groove and the optical power of an output port;
s5, establishing a far field directional diagram theoretical model of the waveguide grating antenna;
leading in far-field radiation pattern data of a single waveguide grating antenna model, insertion loss IR of a single grating groove in a uniform waveguide grating antenna model, optical wavelength lambda of light transmitted in the uniform waveguide grating antenna model and optimized grating groove width in a far-field pattern theoretical model of the waveguide grating antenna
And the number n of grating grooves in the target waveguide grating antenna;
pointing theta = theta in a far-field pattern theoretical model of a waveguide grating antenna m The position of each grating groove is optimized by taking the maximum value obtained by the radiation power of the main lobe or the minimum value obtained by the level of the side lobe as an optimization target to obtain a position distribution table of each grating groove in the target waveguide grating antenna;
s6, according to the distribution table of the positions of the grating grooves in the target waveguide grating antenna, the positions of the grating grooves etched on the optical waveguide are set, and the target waveguide grating antenna is obtained.
2. A grating antenna design method according to claim 1, characterized in that based on uniform waveguide gratingFar field radiation pattern of antenna model versus width of grating grooves in uniform waveguide grating antenna model
And optimizing, wherein when the far-field radiation directional diagram main lobe points to a preset radiation angle alpha, the initial value of lambda is generated by the following formula:
wherein theta is c Is the radiation angle, lambda, in the cladding of the uniform waveguide grating antenna model 0 Is the central wavelength of operation in free space, θ a For radiation angles in air, i.e. preset radiation angles alpha, n e Effective refractive index of grating groove region for uniform waveguide grating antenna model, n c Refractive index of the cladding layer of the uniform waveguide grating antenna model, n a Is the refractive index of air.
3. The method of claim 1, wherein the optical power of the input port is 1, and the insertion loss IR of a single grating groove in the uniform waveguide grating antenna model is determined according to the following formula:
wherein S is 21 The insertion loss between an input port and an output port of the uniform waveguide grating antenna model is obtained.
4. The method according to claim 1, wherein in step S2, the distance that the electric field component of the light is transmitted in the uniform waveguide grating antenna model is obtained when the wavelength λ of the light transmitted in the uniform waveguide grating antenna model changes by 2 pi phase according to the electric field component of the light in the uniform waveguide grating antenna model.
5. The method according to claim 1, wherein when establishing the far field pattern theoretical model of the grating antenna, one grating groove is regarded as one antenna unit, and one grating antenna is regarded as an array consisting of grating grooves;
the far field pattern theoretical model | F (theta) | of the grating antenna is as follows:
|F(θ)|＝|F e (θ)|·|F a (θ)|；
wherein theta is a radiation angle, theta is more than or equal to-180 degrees and less than or equal to 180 degrees, and F is e (theta) | is the far field radiation pattern data of the single waveguide grating antenna model, F a (θ) is the array factor:
wherein, I i Obtaining the field intensity amplitude of an antenna unit formed by the ith grating groove in the grating antenna and the insertion loss IR of a single grating groove in the uniform waveguide grating antenna model; j represents an imaginary number; k is the wave vector in vacuum; d i The distance between the ith grating groove and the 1 st grating groove in the grating antenna is set, i is more than or equal to 1 and is less than or equal to n; beta is a i The initial phase of the input light of the antenna unit formed by the ith grating groove in the grating antenna is according to d i And a wave vector k 'of the light transmitted in the uniform waveguide grating antenna model, wherein k' is obtained according to the wavelength lambda of the light transmitted in the uniform waveguide grating antenna model.
6. The method of claim 5, wherein the grating grooves have a width
The following formula is satisfied:
7. the design method of grating antenna as claimed in claim 5,
β i ＝k′d i 。
8. a grating antenna design method according to claim 1, characterized in that the number n of grating grooves in the target waveguide grating antenna is determined by using the insertion loss IR of a single grating groove and the optical power of the output port according to the following formula:
(1-IR) n ＝1％；
and (3) taking the maximum value obtained by the radiation power of the main lobe or the minimum value obtained by the level of the side lobe as an optimization target, and optimizing the position of each grating groove by adopting an iterative algorithm for solving the problem of multiple extreme values to obtain a position distribution table of each grating groove in the target waveguide grating antenna.
9. The method of claim 1, wherein the grating grooves are uniformly etched on the upper surface of the waveguide model, and a uniform waveguide grating antenna model is formed by combining material parameters and structure size parameters of the uniform waveguide grating antenna, the material parameters of the uniform waveguide grating antenna include the refractive index of the material, and the structure size parameters of the uniform waveguide grating antenna include the length and width of the uniform waveguide grating antenna, the grating period, the width of the grating grooves, the number of grating grooves, and the duty cycle; when the width of the grating groove in the uniform waveguide grating antenna model is optimized according to the far-field radiation pattern of the uniform waveguide grating antenna model, the length and the width of the uniform waveguide grating antenna, the number of the grating grooves and the duty ratio are preset fixed values, and the grating period is twice the width of the grating groove.
10. A grating antenna, characterized in that it is obtained by a method for designing a grating antenna according to any one of claims 1 to 9.
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| US20020122623A1 (en) * | 1999-06-30 | 2002-09-05 | Nec Corporation | Temperature-independent arrayed waveguide grating device |
| US20130209036A1 (en) * | 2010-11-09 | 2013-08-15 | NIT Electronics Corporation | Optical waveguide and arrayed waveguide grating |
| US20150346340A1 (en) * | 2013-01-08 | 2015-12-03 | Ami YAACOBI | Optical phased arrays |
| CN111220965A (en) * | 2020-01-20 | 2020-06-02 | 清华大学 | Multi-beam surface emitting waveguide phased array |
| CN111399114A (en) * | 2020-04-02 | 2020-07-10 | 中国科学院微电子研究所 | Design method of grating antenna |
| CN111596499A (en) * | 2020-06-17 | 2020-08-28 | 中国科学院微电子研究所 | Waveguide grating antenna construction method and device |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20020122623A1 (en) * | 1999-06-30 | 2002-09-05 | Nec Corporation | Temperature-independent arrayed waveguide grating device |
| US20130209036A1 (en) * | 2010-11-09 | 2013-08-15 | NIT Electronics Corporation | Optical waveguide and arrayed waveguide grating |
| US20150346340A1 (en) * | 2013-01-08 | 2015-12-03 | Ami YAACOBI | Optical phased arrays |
| CN111220965A (en) * | 2020-01-20 | 2020-06-02 | 清华大学 | Multi-beam surface emitting waveguide phased array |
| CN111399114A (en) * | 2020-04-02 | 2020-07-10 | 中国科学院微电子研究所 | Design method of grating antenna |
| CN111596499A (en) * | 2020-06-17 | 2020-08-28 | 中国科学院微电子研究所 | Waveguide grating antenna construction method and device |
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