On-chip integrated system of Micro LED optical waveguide AR glasses

Abstract

The invention provides an on-chip integrated system of Micro LED optical waveguide AR glasses, and relates to the technical field of optical imaging, and the system comprises a dielectric substrate layer; the optical waveguide layer is arranged on the dielectric substrate layer; the nano-structure layer is located on the optical waveguide layer, and the nano-structure layer comprises a super-coupler and a guided wave driving metasurface; wherein the super coupler is composed of a polarization-independent unit structure and is used for coupling a collimation light beam vertically incident by the Micro LED into the optical waveguide layer at a set angle to form guided wave mode light; the guided wave driving metasurface is used for decoupling the guided wave mode light into a free space to form an adjustable light field. Efficient optical coupling and decoupling are achieved through the polarization-independent super coupler and the guided wave driving super surface, the one-to-one integrated design of the Micro LED and the strip-shaped waveguide is combined, the display effect and the size of the AR glasses are remarkably improved, optical crosstalk is eliminated, and the wearing comfort and the optical performance are enhanced.

Description

Technical Field

[0001] The present invention relates to the field of optical imaging technology, and particularly to an on-chip integrated system for a Micro LED optical waveguide AR glasses. Background Art

[0002] Augmented reality (AR) and virtual reality (VR) technologies have developed rapidly in recent years. As the core component of the near-eye display system, it plays a key role in achieving an immersive experience. In AR devices, the optical display system usually consists of a micro display screen and optical elements. Currently, most micro display screens use Micro LEDs. By using optical waveguide technology, the display screen and the imaging system can be moved to the top or side of the forehead. This design greatly reduces the obstruction of the optical system to the user's external vision and makes the weight distribution of the device more ergonomic, significantly improving the wearing experience.

[0003] However, there are some problems to be solved urgently in the existing AR glasses technology. In the coupling and decoupling links between free-space light and guided waves, traditional optical elements (such as prisms and gratings) are bulky, which not only limits the flexibility of optical operations but also makes it difficult to improve the integration of the entire system. Moreover, these traditional elements have limited functions and cannot meet the growing high-performance display requirements.

[0004] From the perspective of the process preparation of Micro LEDs, the existing coupling technology has high polarization requirements for Micro LEDs, which increases the complexity of the process preparation and causes energy loss during the polarization adjustment process, thereby affecting the display effect. In addition, due to the difficulty of achieving precise one-to-one coupling between Micro LEDs and optical waveguides in the existing technology, if the light of different Micro LEDs is coupled into the same waveguide, the crosstalk between them will seriously interfere with the display quality, resulting in a decrease in image clarity and color reproducibility.

[0005] In summary, the existing AR glasses technology has many deficiencies in optical coupling elements, Micro LED process preparation, and coupling accuracy. There is an urgent need for an innovative technical solution to solve these problems in order to improve the display performance and user experience of AR glasses. Summary of the Invention

[0006] Therefore, the embodiment of the present invention provides an on-chip integrated system for a Micro LED optical waveguide AR glasses, which is used to solve the problems in the existing technology that the coupling and decoupling optical elements between free-space light and guided waves are bulky, limit the freedom of optical operations and have limited functions, and the Micro LED process preparation has high complexity, large polarization adjustment loss, and easy crosstalk between different Micro LED lights coupled into the same waveguide, affecting the display effect.

[0007] To solve the above problems, an on-chip integrated system of a Micro LED optical waveguide AR glasses is provided in an embodiment of the present invention. The system includes: A dielectric substrate layer; An optical waveguide layer disposed on the dielectric substrate layer; A nanostructure layer located on the optical waveguide layer. The nanostructure layer includes a super-coupler and a waveguide driving metasurface; Wherein the super-coupler is composed of polarization-independent unit structures, and is used to couple the collimated light beam vertically incident by the Micro LED into the optical waveguide layer at a set angle to form a guided wave mode light; the waveguide driving metasurface is used to decouple the guided wave mode light into free space to form a controllable light field.

[0008] Preferably, the unit structure of the super-coupler includes a cylinder or a square column, and its size parameters are arranged by phase gradient, so that the vertically incident collimated light beam undergoes extraordinary refraction and satisfies the waveguide total reflection condition, realizing the coupling of free space light to guided wave mode light.

[0009] Preferably, the super-coupler and the Micro LED have a one-to-one correspondence relationship, and each Micro LED is independently coupled to the corresponding strip waveguide channel, and the strip waveguide channel is formed in the optical waveguide layer by etching to avoid crosstalk during light transmission.

[0010] Preferably, the unit structure of the waveguide driving metasurface is designed by periodic displacement and phase mutation of nanocolumns, extracts the guided wave mode light and superimposes the transmitted cumulative phase, realizing arbitrary wavefront control of the decoupled light field.

[0011] Preferably, the refractive index of the material of the optical waveguide layer is higher than that of the dielectric substrate layer and the air cladding, satisfying the total reflection transmission condition of the guided wave mode light, and the waveguide thickness is limited to single-mode transmission.

[0012] Preferably, the nanostructure parameters of the super-coupler and the waveguide driving metasurface are optimized by a particle swarm algorithm or a genetic algorithm to improve the coupling efficiency and decoupling accuracy of the target wavelength.

[0013] Preferably, the optical waveguide layer is a strip waveguide array, and its arrangement mode is consistent with the geometric distribution of the Micro LED array, and each strip waveguide corresponds to a Micro LED light source.

[0014] Preferably, the waveguide driving metasurface and the super-coupler are separated and arranged in the nanostructure layer, and do not satisfy reciprocity, and only allow free space light to be unidirectionally coupled through the super-coupler, and the guided wave mode light is unidirectionally decoupled through the waveguide driving metasurface.

[0015] Preferably, the transmittance of the unit structure of the super-coupler is greater than a set threshold value, and its phase library covers the range from 0 to 2π, and the light field distribution is verified by finite-difference time-domain simulation.

[0016] Preferably, the decoupled light field of the waveguide-driven metasurface is used for holographic imaging or augmented reality display, and the light field regulation range covers the human eye field of view.

[0017] From the above technical solutions, it can be seen that the present invention application has the following beneficial effects: (1) The present invention utilizes the phase gradient metasurface composed of polarization-independent unit structures in the super-coupler to accurately couple the collimated light beam vertically incident on the Micro LED to the optical waveguide layer, and the waveguide-driven metasurface can realize arbitrary wavefront regulation and decoupling of the guided-wave mode light, effectively improving the light transmission and regulation efficiency, and ensuring the quality and clarity of the display screen.

[0018] (2) The super-coupler of the present invention has a one-to-one correspondence with the Micro LED, and each Micro LED is independently coupled to the corresponding strip waveguide channel, which is formed by etching in the optical waveguide layer, greatly avoiding the crosstalk problem in the light transmission process, making each optical path independent and stable, and enhancing the accuracy and stability of the display effect.

[0019] (3) The relevant structural parameters of the optical waveguide layer, super-coupler and waveguide-driven metasurface of the present invention can be optimized by particle swarm optimization algorithm, etc., and each component of the nanostructure layer is separated and arranged with unidirectionality. This design is not only convenient for flexible adjustment according to different requirements, but also can improve the coupling efficiency and decoupling accuracy of the target wavelength, and enhance the applicability and performance of the system. Description of the Drawings

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly describe the drawings required in the embodiments. By referring to the drawings, the features and advantages of the present invention will be more clearly understood. The drawings are schematic and should not be construed as limiting the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts. Among them: Figure 1 It is a schematic diagram of a chip-integrated system of a Micro LED optical waveguide AR glasses provided by the present invention; Figure 2 It is a schematic diagram of the structural principle of the super-coupler of the present invention; Figure 3 It is a schematic diagram of the structural principle of the waveguide-driven metasurface of the present invention; Figure 4 It is a schematic diagram of the structure of a chip-integrated system of a Micro LED optical waveguide AR glasses provided by the present invention.

[0021] Description of the reference numerals in the drawings: 1. dielectric substrate layer; 2. optical waveguide layer; 31. super coupler; 32. waveguide-driven metasurface. Specific embodiments

[0022] For a clearer understanding of the objectives, technical solutions, and advantages of the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0023] Embodiment 1:

[0024] To solve the problems in the prior art that the optical elements for coupling and decoupling between free-space light and guided waves (mode light) are bulky, restricting the freedom of optical operations and having limited functions, and that the Micro LED process has high preparation complexity, large adjustment polarization loss, and easy crosstalk between different Micro LEDs when coupling light into the same waveguide, affecting the display effect. As Figure 1 shown, the present invention proposes an on-chip integrated system for a Micro LED optical waveguide AR glasses, which system includes: A dielectric substrate layer 1; An optical waveguide layer 2, disposed on the dielectric substrate layer 1; A nanostructure layer, located on the optical waveguide layer 2, and the nanostructure layer includes a super coupler 31 and a waveguide-driven metasurface 32; Wherein the super coupler 31 is composed of polarization-independent unit structures and is used to couple the collimated light beam vertically incident from the Micro LED into the optical waveguide layer 2 at a set angle to form a guided wave mode light; the waveguide-driven metasurface 32 is used to decouple the guided wave mode light into free space to form a controllable light field.

[0025] As can be seen from the above technical solution, the present invention proposes a chip-integrated system for a Micro LED optical waveguide AR glasses. The super-coupler of the present invention is composed of a polarization-independent unit structure, which corresponds precisely one-to-one with the Micro LED. Through a unique phase gradient arrangement and strip waveguide channel design, it can not only efficiently couple the vertically incident collimated light beam into the optical waveguide layer, but also avoid optical crosstalk and ensure the accuracy of imaging. The refractive index of the optical waveguide layer material is carefully selected to be higher than that of the dielectric substrate layer and the air cladding layer, and it is restricted to single-mode transmission to ensure stable total reflection transmission of the guided-mode light and reduce interference. The guided-wave driving metasurface can achieve arbitrary wavefront control of the guided-mode light through the design of nano-column periodic displacement and phase mutation, decouple it precisely into free space, cover the human eye field of view, and is suitable for holographic imaging or augmented reality display. In addition, the nano-column structure parameters of the super-coupler and the guided-wave driving metasurface are optimized by means of particle swarm optimization algorithm and others to further improve the coupling efficiency and decoupling accuracy. The overall solution significantly improves the optical performance and display effect of the Micro LED optical waveguide AR glasses, bringing a better AR experience to users.

[0026] Further, the chip-integrated system of the Micro LED optical waveguide AR glasses of the present invention mainly consists of a dielectric substrate layer 1, an optical waveguide layer 2 and a nanostructure layer. The nanostructure layer is located above the optical waveguide layer 2 and includes a super-coupler 31 and a guided-wave driving metasurface 32.

[0027] In this embodiment, the super-coupler 31 is composed of polarization-independent unit structures, such as cylinders or square columns. Its design is based on the size of the Micro LED, aiming to couple the vertically incident collimated light beam of the Micro LED into the optical waveguide layer 2 at a set angle to form guided-mode light. During the design process, the unit structure is simulated using FDTD (finite-difference time-domain) simulation software. By changing parameters such as the period (P), diameter (D), and height (H) of the unit structure, the phase control of the incident light field is achieved. Arrangement is made according to the required phase to cause the vertically incident collimated light beam to undergo extraordinary refraction. When the transmission angle satisfies the waveguide total reflection condition, the free-space light can be coupled into the waveguide and transmitted in the fundamental mode (TE fundamental mode or TM fundamental mode), thus realizing the coupling of free-space light to guided-mode light.

[0028] To ensure the performance of the super-coupler 31, it is required that the transmittance of its unit structure is greater than a set threshold (set to 80% in this embodiment), and the phase library covers 0 to 2π. The light field distribution of the free-space light coupled into the waveguide by the super-coupler 31 can be obtained through FDTD simulation software to verify the rationality of its design. For example, in actual design, for a specific Micro LED, after multiple simulation optimizations, the period (P), diameter (D), and height (H) of the unit structure are determined to make the system achieve an ideal coupling effect.

[0029] As shown Figure 2 in the figure, the supercoupler 31 adopts the nanostructure of the phase gradient metasurface and can couple the linearly polarized light vertically incident in free space into the waveguide. The coupling principle and design basis of the supercoupler 31 are as follows: In the design of the supercoupler 31 of the integrated system on the Micro LED optical waveguide AR lens in this case, according to the generalized Snell's law, when the plane light incident from free space passes through the interface, the refraction angle and the incident angle need to satisfy a specific relationship, that is .

[0030] In the actual application scenario, when the free space light is vertically incident, that is, the incident angle , and the refraction angle and the refractive index of the waveguide The product of is equal to the effective refractive index of a certain waveguide mode ( ), the formula can be simplified to .

[0031] Based on this principle, when designing the unit structure of the supercoupler 31, as long as the phase gradient at the interface is reasonably controlled, the metasurface can realize the conversion of free space light to light of any waveguide mode. For example, in the design of the supercoupler 31 for a specific Micro LED light source and waveguide system, by accurately calculating and controlling the phase gradient, adjusting the size parameters of the unit structure of the supercoupler 31 (such as cylinders or square columns), and arranging them according to the phase gradient. The vertically incident collimated light beam undergoes extraordinary refraction, satisfying the total internal reflection condition of the waveguide, thus successfully realizing the efficient coupling of free space light to waveguide mode light.

[0032] In addition, it is worth noting that The positive and negative signs of the term determine the coupling direction, which needs to be carefully considered in the actual design process to ensure that the light is coupled into the waveguide in the expected direction, laying a foundation for the subsequent waveguide mode light transmission and decoupling display.

[0033] In this embodiment, the waveguide-driven metasurface 32 is used to decouple the waveguide mode light into free space to form a controllable light field. Its unit structure is designed by the periodic displacement and phase mutation of nanocolumns. During the transmission of the waveguide mode light, with 2π as the period, different phases of light are extracted through the displacement of the nanocolumns within the period, and then the cumulative phase of the transmitted light is superimposed to realize the arbitrary wavefront control of the decoupled light field.

[0034] As shown Figure 3 in the figure, assuming that the initial phase of the incident waveguide mode light is , when the waveguide mode light passes through the first nanocolumn, the phase of the coupled light decoupled into free space becomes , where represents the phase mutation provided by the first nanocolumn. As the guided-mode light propagates a distance and reaches the position of the second nanocolumn, the phase of the light coupled from the second nanocolumn to free space is , is the propagation constant of the guided-mode light, is the phase change caused by the phase accumulation during the transmission process. Let the initial phase , and the initial position x = 0, then the total phase of the coupled light at different x positions is . It can be clearly seen from the above formula that the total phase of the light coupled into free space consists of two parts: the phase mutations provided by the meta-atoms at different x positions; the phase accumulation of the guided-mode light during the transmission process. By reasonably designing the parameters and displacements of the nanocolumns, the phase distribution of the decoupled light field can be precisely regulated to meet the requirements of holographic imaging or augmented reality display, and the light field regulation range covers the human eye field of view.

[0035] In this embodiment, the optical waveguide layer 2 is disposed on the dielectric substrate layer 1, and its material refractive index is higher than that of the dielectric substrate layer 1 and the air cladding. This is to meet the total reflection transmission condition of the guided-mode light and ensure the stable transmission of light in the waveguide. When selecting the material of the optical waveguide layer 2, the transmission loss and dispersion characteristics of different materials for light of different bands need to be considered. At the same time, the waveguide thickness is limited to single-mode transmission to reduce the interference between modes and ensure the stability of the display effect. The performance of the waveguide and coupler is accurately modeled by the FDE (Finite Difference Eigenmode) simulation of AnsysLumerical to determine the appropriate waveguide thickness and other structural parameters.

[0036] Further, the preparation and optimization process of the system of the present invention includes: (1) Preparation of the strip waveguide array: According to the arrangement of the Micro LED array, photolithography and etching are performed on the optical waveguide layer 2 to form a strip waveguide array. As Figure 4 shown, each strip waveguide corresponds to a Micro LED light source, and its arrangement is consistent with the geometric distribution of the Micro LED array. In this way, each Micro LED is independently coupled to the corresponding strip waveguide channel, avoiding crosstalk during the light transmission process and ensuring the clarity and accuracy of the display.

[0037] (2)Fabrication of the nanostructure layer: In the nanostructure layer, according to the requirements of coupling Micro LEDs into the optical waveguide and decoupling and modulating the guided wave, the super-coupler 31 and the guided-wave driving metasurface 32 are fabricated respectively. The super-coupler 31 and the guided-wave driving metasurface 32 are arranged separately in the nanostructure layer and do not satisfy reciprocity. Only the free-space light is allowed to be unidirectionally coupled through the super-coupler 31, and the guided-wave mode light is unidirectionally decoupled through the guided-wave driving metasurface 32. During the fabrication process, through processes such as photolithography and etching, the size, shape, and position of the nanocolumns are precisely controlled to ensure that their performance meets the design requirements.

[0038] (3)Optimization of structural parameters: The nanocolumn structural parameters of the super-coupler 31 and the guided-wave driving metasurface 32 are optimized by optimization algorithms such as the particle swarm algorithm or the genetic algorithm. Taking the particle swarm algorithm as an example, during the optimization process, the coupling efficiency and decoupling accuracy are used as the optimization objectives, and the parameters such as the size, shape, and spacing of the nanocolumns are continuously adjusted. After multiple iterative calculations, the optimal parameter combination is found to improve the coupling efficiency and decoupling accuracy of the target wavelength and further enhance the display effect of the system.

[0039] Furthermore, the working process of the system of the present invention is as follows: The collimated light beam emitted by the Micro LED is vertically incident on the corresponding super-coupler 31. The super-coupler 31 couples the light beam into the optical waveguide layer 2 to form a guided-wave mode light. The guided-wave mode light propagates in the waveguide and is decoupled into the free space after reaching the guided-wave driving metasurface 32, forming a controllable light field. This light field is received by both eyes and is used for holographic imaging or augmented reality display. During the whole process, the incident position of the Micro LED, the unit nanocolumn structure (size, shape, spacing) of the super-coupler 31, etc. are optimized to improve the coupling efficiency and ensure the display effect. For example, in an actual application scenario, when a user wears AR glasses to view a virtual scene, the light emitted by the Micro LED is coupled into the waveguide through the super-coupler 31 and then decoupled into the free space by the guided-wave driving metasurface 32, forming a clear and realistic virtual image that appears in front of the user's eyes, realizing an immersive augmented reality experience.

[0040] In summary, the on-chip integrated system of the Micro LED optical waveguide AR glasses of the present invention effectively solves the deficiencies of the prior art through unique structural design, fabrication process, and parameter optimization, significantly improves the display effect of Micro LEDs in the application of optical waveguide AR glasses, and has important practical value and market prospects.

[0041] Obviously, the above embodiments are merely examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation manners here. And the obvious changes or modifications derived therefrom still fall within the protection scope of the present invention.

Claims

1. An on-chip integrated system for a Micro LED optical waveguide AR glasses, characterized in that, Comprising: A dielectric substrate layer; An optical waveguide layer disposed on the dielectric substrate layer; A nanostructure layer located on the optical waveguide layer, the nanostructure layer comprising a supercoupler and a waveguide-driven metasurface; Wherein the supercoupler is composed of polarization-independent unit structures, and is used to couple the collimated light beam vertically incident from the Micro LED into the optical waveguide layer at a set angle to form guided-mode light; the waveguide-driven metasurface is used to decouple the guided-mode light into free space to form a controllable light field.

2. The on-chip integrated system of the Micro LED optical waveguide AR glasses according to claim 1, characterized in that, The unit structure of the supercoupler includes a cylinder or a square column, and its size parameters are arranged by phase gradient, so that the vertically incident collimated light beam undergoes extraordinary refraction and satisfies the waveguide total reflection condition, realizing the coupling of free-space light to guided-mode light.

3. The on-chip integrated system of the Micro LED optical waveguide AR glasses according to claim 1, characterized in that, The supercoupler and the Micro LED have a one-to-one correspondence relationship, and each Micro LED is independently coupled to the corresponding strip waveguide channel, and the strip waveguide channel is formed in the optical waveguide layer by etching to avoid crosstalk during light transmission.

4. The on-chip integrated system of the Micro LED optical waveguide AR glasses according to claim 1, characterized in that The unit structure of the waveguide-driven metasurface designs the periodic displacement and phase mutation of the nanocolumns, extracts the guided-mode light and superimposes the transmitted cumulative phase to realize arbitrary wavefront control of the decoupled light field.

5. The on-chip integrated system of the Micro LED optical waveguide AR glasses according to claim 1, characterized in that, The refractive index of the material of the optical waveguide layer is higher than that of the dielectric substrate layer and the air cladding, satisfying the total reflection transmission condition of the guided-mode light, and the waveguide thickness is limited to single-mode transmission.

6. The on-chip integrated system of the Micro LED optical waveguide AR glasses according to claim 1, characterized in that The nanocolumn structure parameters of the supercoupler and the waveguide-driven metasurface are optimized by a particle swarm algorithm or a genetic algorithm to improve the coupling efficiency and decoupling accuracy of the target wavelength.

7. The on-chip integrated system of the Micro LED optical waveguide AR glasses according to claim 1, characterized in that, The optical waveguide layer is a strip waveguide array, and its arrangement mode is consistent with the geometric distribution of the Micro LED array, and each strip waveguide corresponds to a Micro LED light source.

8. The on-chip integrated system of the Micro LED optical waveguide AR glasses according to claim 1, characterized in that, The waveguide-driven metasurface and the supercoupler are separated and arranged in the nanostructure layer, and do not satisfy reciprocity. Only free-space light is allowed to be unidirectionally coupled through the supercoupler, and the guided-mode light is unidirectionally decoupled through the waveguide-driven metasurface.

9. The on-chip integrated system of the Micro LED optical waveguide AR glasses according to claim 1, characterized in that, The transmittance of the unit structure of the supercoupler is greater than a set threshold, and its phase library covers the range from 0 to 2π, and the light field distribution is verified by finite-difference time-domain simulation.

10. The on-chip integrated system of the Micro LED optical waveguide AR glasses according to claim 1, characterized in that, The decoupled light field of the waveguide-driven metasurface is used for holographic imaging or augmented reality display, and the light field control range covers the human eye field of view.

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