An optical antenna based on inverse design for arbitrary angle emission

Abstract

The application discloses an optical antenna based on reverse design arbitrary angle emission. The antenna adopts a silicon-on-insulator (SOI) structure, and comprises a silicon substrate, a dielectric buried oxygen layer (BOX) and an optical antenna. The optical antenna is composed of an input waveguide, a tapered waveguide and a reverse design radiation structure. A light source is input from a port, the dielectric buried oxygen layer is located above the silicon substrate, and the optical antenna is located above the buried oxygen layer. The application obtains a topologically optimized optical antenna through a reverse design method, can realize arbitrary angle beam pointing in free space, has good light spot quality, strong beam pointing property, and further reduces the light spot size compared with a traditional grating antenna. The optical antenna can be widely applied to the fields of laser radar, imaging, automatic driving and unmanned aerial vehicle, has the advantages of simple structure, reasonable design, miniaturization and integration, easy processing and manufacturing and the like, and is compatible with a CMOS process platform.

Description

Technical Field

[0001] This invention belongs to the field of large-scale integrated photonics technology, and particularly relates to an optical antenna based on reverse design for arbitrary angle emission. Background Technology

[0002] Currently, with the rapid development of large-scale integrated photonics technology, optical phased arrays (OPAs) based on optical antennas are an effective way to achieve highly integrated, stable, and low-cost beam control systems. Optical detection, ranging, and free-space optical communication all rely on the real-time, precise shaping and scanning of free-space beams. Integrated optical antennas are one of the key components of OPAs based on optical waveguides, providing compact, small, and lightweight scanning systems without complex mechanical moving parts, making them a key technology in fields such as lidar, autonomous driving, holographic projection, bio-imaging, augmented and virtual reality.

[0003] In nanophotonics, designing optimal structures requires calculating the optical responses of different structural combinations one by one. This iterative approach relies heavily on physical formulas and human experience, lacking design flexibility. Furthermore, if the optimization objective changes, all simulation designs must be completely rewritten – this is based on the forward design paradigm. In recent years, reverse design of nanophotonic devices has gained widespread attention as a more efficient method. This method, aided by reverse design algorithms, directly approximates the design objective by incorporating various physical optical response characteristics. Reverse design differs fundamentally from forward design; it is method-agnostic, aiming to solve physical problems using mathematical tools (artificial intelligence algorithms). It numerically defines the desired optical response (device function) as an objective function, and the optimization algorithm iteratively calculates structural parameters to maximize or minimize the objective function value. Reverse design offers numerous advantages: it is well-suited for photonic devices with complex functions that cannot be analytically solved; its method is agnostic, requiring no prior knowledge of physical principles, and offers extremely high design freedom. Therefore, reverse design has enormous potential and practical application value in the field of nanophotonics.

[0004] Currently, AI-based reverse engineering methods are widely used in nanophotonics research, including data transmission, nonlinear optics, singular and topological photonics, nanooptics, and metasurfaces. Due to the complexity of determining the objective function of the far-field beam of an optical antenna, few studies have combined reverse engineering with optical antennas to achieve arbitrary control of free-space beams. In recent years, with the continuous development of AI algorithms, some studies have proposed nanoscale universal transmitters and reverse-designed periodic grating structures to achieve beam control in free space. However, these methods all suffer from difficulties in fabrication and large device sizes, hindering their miniaturization and large-scale integration in nanophotonic systems (such as optical phased arrays). Summary of the Invention

[0005] Technical Problem: This invention proposes an optical antenna based on reverse design for arbitrary angle emission, which has subwavelength structural feature dimensions. It uses machine learning algorithms to reverse design the corresponding optical antenna topology to achieve beam pointing at any angle in free space. This solves the problems of existing methods, such as high processing and manufacturing difficulty and large device size, which are not conducive to its miniaturization and large-scale integration in nanophotonic systems (such as optical phased arrays).

[0006] Technical solution: The present invention provides an optical antenna based on reverse design for arbitrary angle transmission, which adopts a silicon-on-insulator (SOI) structure and includes a silicon substrate, a buried oxide layer, and an optical antenna.

[0007] Optical antennas include input waveguides, tapered waveguides, and reverse-designed radiating structures;

[0008] A dielectric buried oxide layer is placed on top of a silicon substrate. An optical antenna is placed on top of the dielectric buried oxide layer along the length of the waveguide layer. The optical antenna consists of an input waveguide, a tapered waveguide, and a reverse-designed radiation structure connected in sequence. The light source is injected from the input waveguide and mode matching is performed through the tapered waveguide. By solving the topology optimization problem of the reverse-designed radiation structure, beam emission is finally achieved in the reverse-designed radiation structure.

[0009] Multiple square cell slots were fully etched onto the reverse-designed radial structure.

[0010] The topology optimization problem of the reverse-designed radial structure is solved using an artificial intelligence-based reverse design algorithm. The objective function is updated iteratively through square etching to finally generate the optimal topology solution of the reverse-designed radial structure.

[0011] Furthermore, the material of the dielectric buried oxide layer is silicon dioxide.

[0012] Furthermore, the input waveguide, tapered waveguide, and reverse-designed radiation structure are made of silicon or similar light-guiding materials.

[0013] Furthermore, the overall shape of the tapered waveguide is trapezoidal, and the angle between the two sidewalls depends on the length of the tapered waveguide.

[0014] Furthermore, the square unit slots of the reverse-designed radial structure have a length of 0.1–0.5 μm and a width of 0.1–0.5 μm.

[0015] Furthermore, the width of the input waveguide is 0.5 μm.

[0016] Furthermore, the reverse-designed radiation module has a length of 5–10 μm and a width of 5–10 μm.

[0017] Furthermore, the height of the optical antenna is 0.22 μm.

[0018] The working principle is as follows: The main body of this optical antenna, which is based on reverse design for arbitrary angle emission, adopts a silicon-on-insulator (SOI) structure, which can achieve good device isolation. A buried oxide layer is placed on top of the silicon substrate, and mode confinement is performed by an input waveguide located above the buried oxide layer. For a fixed incident light wavelength, after numerically calculating the target far-field beam function, a reverse design algorithm based on artificial intelligence (machine learning) is used to perform square etching on the initial structure of the optical antenna, and iterative optimization is performed through successive cyclic search to finally obtain an optical antenna topology that conforms to the direction of the target beam. This enables the antenna to emit beams at arbitrary angles in free space.

[0019] Considering only the waveguide fundamental mode as the light source input, multiple optical antennas were designed as simulation examples. In this type of optical antenna emitting at arbitrary angles, beam pointing with a tilt angle (θ) of approximately -14.1° and a horizontal angle (φ) of 45° was achieved at an incident light wavelength of 1530nm; at 1540nm, the same beam pointing angle (θ) was achieved; at 1550nm, a beam pointing angle (θ) of 10° and a horizontal angle (φ) of 0° was achieved; at 1560nm, a beam pointing angle (θ) of approximately 14.1° and a horizontal angle (φ) of -45° was achieved; and at 1570nm, a beam pointing angle (θ) of approximately -14.1° and a horizontal angle (φ) of -45° was achieved. The designed optical antenna exhibits a single beam pattern in the far field with energy concentrated at the center, achieving good beam pointing and further reducing the beam size compared to grating antennas. Furthermore, the resulting optical antenna array possesses phase-tuning capability, demonstrating excellent far-field radiation performance.

[0020] Beneficial Effects: Compared to existing technologies, this invention expands upon traditional optical antennas through reverse design research to achieve diverse and complex antenna functions. The optical antenna employs a silicon-on-insulator (SOI) structure compatible with CMOS processes, using an input waveguide for mode confinement. For a specific incident light wavelength, a machine learning-based reverse design algorithm is used to optimize the initial structure of the optical antenna, ultimately obtaining an antenna topology that conforms to the far-field objective function. Simulation results show that the optimized topology can achieve arbitrary beam pointing angles in free space for a given far-field objective function. The beam directivity is strong, and the spot size is further reduced. Furthermore, the resulting optical antenna array possesses phase tuning capability, meaning that horizontal beam scanning can be achieved by adjusting the phase difference between array element channels. It also boasts advantages such as ease of fabrication, device miniaturization, and suitability for large-scale system integration. Attached Figure Description

[0021] Figure 1 This is a flowchart illustrating the reverse design of the arbitrary-angle optical antenna of the present invention.

[0022] Figure 2 This is a top view schematic diagram of the optical antenna of the present invention;

[0023] Figure 3 This is a schematic cross-sectional view of the optical antenna of the present invention;

[0024] Figure 4 This is a side view of the optical antenna of the present invention;

[0025] Figure 5 This represents the cross-sectional mode field distribution of the optical antenna at any angle according to the present invention.

[0026] Figure 6 This is a far-field beam distribution diagram of the arbitrary-angle optical antenna of the present invention with reverse design optimization when the incident light wavelength is 1550nm.

[0027] Figure 7 This invention presents the topology optimized by reverse design for the arbitrary-angle optical antenna when the incident light wavelength is 1530nm, and the corresponding far-field beam distribution.

[0028] Figure 8 This invention presents the topology optimized by reverse design for the arbitrary-angle optical antenna when the incident light wavelength is 1540nm, and the corresponding far-field beam distribution.

[0029] Figure 9 This invention presents the topology optimized by reverse design for the arbitrary-angle optical antenna when the incident light wavelength is 1560nm, and the corresponding far-field beam distribution.

[0030] Figure 10This invention presents the topology optimized by reverse design for the arbitrary-angle optical antenna when the incident light wavelength is 1570nm, and the corresponding far-field beam distribution.

[0031] Figure 11 (a) is a schematic diagram of the arbitrary angle optical antenna array of the present invention and a far-field beam distribution diagram corresponding to the array element phase difference of 0° when the incident light wavelength is 1550nm.

[0032] Figure 11 (b) is a schematic diagram of the arbitrary angle optical antenna array of the present invention and a far-field beam distribution diagram corresponding to an array element phase difference of -120° when the incident light wavelength is 1550nm.

[0033] Figure 11 (c) is a schematic diagram of the optical antenna array at any angle of the present invention and a far-field beam distribution diagram corresponding to an array element phase difference of 120° when the incident light wavelength is 1550nm.

[0034] The markings in the diagram are as follows: 1. Silicon substrate; 2. Dielectric buried oxide layer; 3. Input waveguide; 4. Tapered waveguide; 5. Reverse-designed radiating structure. Detailed Implementation

[0035] The invention will now be further explained with reference to the accompanying drawings.

[0036] like Figure 1 The diagram shown is a flowchart of the reverse engineering method for an arbitrary-angle optical antenna according to the present invention. The reverse engineering method for an arbitrary-angle optical antenna according to the present invention includes the following steps:

[0037] S1: Construct the initial structural model of the optical antenna;

[0038] In this step, the constructed initial optical antenna structure consists of an input waveguide 3, a tapered waveguide 4, and a reverse-designed radiating structure 5. The input waveguide 3 has a width of 0.5 μm, and the reverse-designed radiating structure 5 has dimensions of 7 μm × 5 μm. At this stage, the optical antenna structure has not been etched and does not possess any far-field beam pointing capability.

[0039] S2: Based on the constructed structural model, the antenna is reverse-engineered using a topology optimization method based on a direct search binary algorithm: For a given far-field beam objective function, the digital material density distribution within the design area is obtained by reversing the two-dimensional material matrix that constitutes the initial structure of the optical antenna by setting it to 0 or 1, and iterating iteratively.

[0040] In this step, the purpose of reverse design is to enable the optical antenna to point the beam at any angle in free space. The objective function of reverse design is to obtain the orientation information of the far-field spot of the optical antenna in free space, including the tilt angle and horizontal angle, at a specific incident light wavelength. Iterative topology optimization of the optical antenna structure is performed using a direct binary search algorithm. Here, "0" represents no etching, and "1" represents etching, with the etched shape being a square groove with dimensions of 0.25μm × 0.25μm.

[0041] S3: Finally, the optimal structure of the optical antenna is obtained by square etching based on the binary distribution of the two-dimensional matrix (0 or 1) of the material density;

[0042] In this step, square etching is performed based on the material density matrix with binary distribution optimized by the algorithm to obtain the final optical antenna topology that conforms to the far-field objective function.

[0043] like Figure 2 , Figure 3 , Figure 4 The optical antenna shown is based on reverse design for arbitrary angle transmission and includes a silicon substrate 1, a dielectric buried oxide layer 2, and an optical antenna.

[0044] The optical antenna consists of an input waveguide 3, a tapered waveguide 4, and a reverse-designed radiating structure 5. Incident light propagates along the x-direction and, after passing through the optical antenna structure, is emitted into the far field along the z-direction.

[0045] As a simulation example, machine learning algorithms were used to optimize multiple optical antennas that emit at arbitrary angles, including achieving beam pointing at different angles in free space under different incident light wavelengths (1530nm, 1540nm, 1550nm, 1560nm, 1570nm), resulting in the following illustrated results.

[0046] like Figure 5 As shown, the cross-sectional mode distribution of an optical antenna emitting at an arbitrary angle reveals that the waveguide modes are well confined within the input waveguide, with almost no mode leakage.

[0047] like Figure 6 As shown, the far-field beam distribution of an optical antenna emitting at an arbitrary angle, with an incident light wavelength of 1550 nm, is optimized through reverse design. It can be seen that since the specified target angle of the far-field beam is θ = 10° and φ = 0°, meaning it has no horizontal deflection and conforms to spatial symmetry, the algorithm also performs symmetrical design on its structure, ultimately achieving emission at a specified beam angle in free space with good beam quality and no obvious sidelobes.

[0048] like Figure 7As shown, the topology of the optical antenna at any angle is optimized by reverse design when the incident light wavelength is 1530nm, and the corresponding far-field beam distribution are shown. The final far-field beam target is: θ≈-14.1°, φ=45°; Figure 8 As shown, the topology of the optical antenna at any angle is optimized by reverse design when the incident light wavelength is 1540nm, and the corresponding far-field beam distribution are shown. The final far-field beam target is: θ≈14.1°, φ=45°; Figure 9 As shown, the topology of the optical antenna at any angle is optimized by reverse design when the incident light wavelength is 1560nm, and the corresponding far-field beam distribution are shown. The final far-field beam target is: θ≈14.1°, φ=-45°; Figure 10 As shown, the optical antenna at any angle exhibits a reverse-engineered optimized topology and corresponding far-field beam distribution at an incident light wavelength of 1570 nm. The final far-field beam target is θ≈-14.1°, φ=-45°. It can be seen that the algorithm employs an asymmetric design structure due to the deflection of the emitted beam in both the horizontal and vertical directions. Under different incident light wavelengths, the optical antenna can ultimately achieve beam pointing at a specified target angle and exhibits excellent far-field emission performance.

[0049] like Figure 11 (a) Figure 11 (b) Figure 11 As shown in (c), the schematic diagram of the optical antenna array at any angle and the far-field beam distribution under different element phase differences at an incident light wavelength of 1550 nm demonstrate that, compared to a single-channel antenna, the beam size is reduced in the horizontal direction while the beam intensity is further improved. Furthermore, by adjusting the phase difference between adjacent waveguides in the optical antenna array, horizontal beam deflection and scanning can be achieved. With an element phase difference of ±120°, a 60° horizontal scan of the far-field beam in free space can be achieved without the generation of grating lobes, exhibiting good beam directivity. This further proves the accuracy of the simulation and the rationality and robustness of the algorithm.

[0050] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An optical antenna based on reverse design for arbitrary angle transmission, characterized in that, The silicon-on-insulator (SOI) structure is adopted, including a silicon substrate (1), a dielectric buried oxide layer (2), and an optical antenna; The optical antenna includes an input waveguide (3), a tapered waveguide (4), and a reverse-designed radiation structure (5); A dielectric buried oxide layer (2) is disposed on the silicon substrate (1). An optical antenna is disposed on the dielectric buried oxide layer (2) along the length of the waveguide layer. The optical antenna is composed of an input waveguide (3), a tapered waveguide (4), and a reverse-designed radiation structure (5) connected in sequence. The light source is injected from the input waveguide (3) and mode matching is performed through the tapered waveguide (4). By solving the topology optimization problem of the reverse-designed radiation structure (5), the beam is finally emitted in the reverse-designed radiation structure (5). Multiple square unit slots are fully etched on the reverse-designed radial structure (5); The topology optimization problem of the reverse-designed radiating structure (5) is solved by a reverse design algorithm based on artificial intelligence, and the objective function is updated iteratively by means of square etching, so as to finally generate the optimal topology solution of the reverse-designed radiating structure (5).

2. The optical antenna based on reverse design for arbitrary angle transmission according to claim 1, characterized in that, The material of the buried oxide layer (2) is silicon dioxide.

3. The optical antenna based on reverse design for arbitrary angle transmission according to claim 1, characterized in that, The input waveguide (3), tapered waveguide (4), and reverse-designed radiation structure (5) are made of silicon or similar light-guiding materials.

4. The optical antenna based on reverse design for arbitrary angle transmission according to claim 1, characterized in that, The overall shape of the tapered waveguide (4) is trapezoidal, and the angle of the two side walls depends on the length of the tapered waveguide (4).

5. The optical antenna based on reverse design for arbitrary angle transmission according to claim 1, characterized in that, The square unit slot of the reverse-designed radial structure (5) has a length of 0.1 to 0.5 μm and a width of 0.1 to 0.5 μm.

6. The optical antenna based on reverse design for arbitrary angle transmission according to claim 1, characterized in that, The width of the input waveguide (3) is 0.5 μm.

7. The optical antenna based on reverse design for arbitrary angle transmission according to claim 1, characterized in that, The reverse-designed radiating structure (5) has a length of 5-10 μm and a width of 5-10 μm.

8. The optical antenna based on reverse design for arbitrary angle transmission according to claim 1, characterized in that, The height of the optical antenna is 0.22 μm.

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