Optical waveguide and electronic device

Abstract

The application provides an optical waveguide and an electronic device. The optical waveguide comprises a waveguide substrate, and a coupling-in region and a coupling-out region are arranged on the side surface of the waveguide substrate. The coupling-in region is used for coupling light into the waveguide substrate, and the light is coupled out from the coupling-out region after reflection propagation inside the waveguide substrate. One of the coupling-in region and the coupling-out region is a positive dispersion region, and the other is a negative dispersion region. The dispersion generated after the light passes through the positive dispersion region is used for compensating the dispersion generated after the light passes through the negative dispersion region. The processing effects of the positive dispersion region and the negative dispersion region on light of different wavelengths can be mutually compensated, so that light of different wavelengths incident at the same incident angle can be emitted at a similar refraction angle. In this way, the light of different wavelengths can have a similar diffraction order when being coupled out, the energy of the light of different wavelengths coupled out is similar, and thus the picture effect of the electronic device is improved.

Description

Technical Field

[0001] This application belongs to the field of optical technology, and more specifically, relates to an optical waveguide and electronic device. Background Technology

[0002] Smart glasses have gained widespread popularity among consumers in recent years. Augmented reality (AR) glasses, in particular, can display virtual images using diffraction waveguide (DWG) technology. One approach is to reduce the overall weight of smart glasses by decreasing the number of waveguides within them. However, different wavelengths of light have varying energy levels after being coupled out of a single waveguide. To ensure image clarity, monochromatic light sources, such as a single shade of green, are typically used for information cues. However, this results in a monochromatic image, reducing the overall quality of the display. Utility Model Content

[0003] The purpose of this application is to provide an optical waveguide and electronic device to solve the technical problem in the prior art where light of different wavelengths has different energies after being coupled out of a single optical waveguide.

[0004] To achieve the above objectives, the technical solution adopted in this application is as follows:

[0005] In a first aspect, an optical waveguide is provided, comprising a waveguide substrate. A coupling-in region and a coupling-out region are disposed on the side of the waveguide substrate. The coupling-in region is used to couple light into the waveguide substrate, and the light is reflected and propagated within the waveguide substrate before being coupled out from the coupling-out region. One of the coupling-in region and the coupling-out region is a positive dispersion region, and the other is a negative dispersion region. The dispersion generated by light passing through the positive dispersion region is used to compensate for the dispersion generated by light passing through the negative dispersion region.

[0006] When light of different wavelengths is incident on the negative dispersion region at the same angle, the longer the wavelength of the light leaves the negative dispersion region, the larger the angle of refraction.

[0007] When light of different wavelengths is incident on the positive dispersion region at the same angle, the longer the wavelength of the light leaves the positive dispersion region, the smaller the angle of refraction.

[0008] In some embodiments, the grating in the positive dispersion region includes a plurality of first unit structures arranged sequentially on the side surface of the waveguide substrate, wherein the nth first unit structure among the plurality of first unit structures provides light with wavelength λ. Phase, the (n+1)th of the plurality of first unit structures provides for light rays with wavelength λ. Phase, It is inversely proportional to λ;

[0009] Where n≥1.

[0010] In some embodiments, the nth first unit structure among a plurality of first unit structures corresponds to a wavelength of λ. r The light provides Phase, and the nth first unit structure for wavelength λ b The light provides Phase;

[0011] The (n+1)th first unit structure in a plurality of first unit structures corresponds to a wavelength of λ. r The light provides Phase, and the (n+1)th first unit structure with wavelength λ b The light provides Phase;

[0012] Where, λ r ≠λ b ;

[0013]

[0014] In some embodiments, the effect of the positive dispersion region on light satisfies the following expression:

[0015]

[0016] Where, n ta Let n be the refractive index of the exiting medium in the positive dispersion region. ia Let θ be the refractive index of the incident medium within the positive dispersion region. ta θ is the angle at which light exits the positive dispersion region. ia P is the angle at which light is incident on the positive dispersion region. a It is the period of the first unit structure.

[0017] In some embodiments, the period P of the first unit structure a The wavelength range is 150–400 nm.

[0018] In some embodiments, the period P of the first unit structure a The wavelength range is 150–300 nm.

[0019] In some embodiments, the number of the first unit structures is 4 to 8 within one phase period length.

[0020] In some embodiments, the first unit structure is a metasurface structure.

[0021] In some embodiments, at least one dispersion correction region is further provided on the side of the waveguide substrate. Along the propagation direction of light in the optical waveguide, the dispersion correction region is disposed between the coupling-in region and the coupling-out region. A grating assembly is disposed in the dispersion correction region, and the grating assembly is used to change the total internal reflection angle of light of a preset wavelength in the waveguide substrate.

[0022] In some embodiments, the grating assembly includes a Bragg grating, a volume Bragg grating, and / or a polarizing volume holographic grating.

[0023] In some embodiments, the grating assembly includes a second grating and a third grating, the second grating and the third grating being arranged in a direction parallel to the side surface of the waveguide substrate, or the second grating and the third grating being stacked in a direction along the thickness direction of the waveguide substrate;

[0024] The second grating is used to change the total internal reflection angle of the first preset wavelength light on the waveguide substrate;

[0025] The third grating is used to change the total internal reflection angle of the second preset wavelength light on the waveguide substrate;

[0026] The wavelengths of the first preset wavelength light and the second preset wavelength light are not equal.

[0027] In some embodiments, the second grating includes a plurality of second unit structures disposed on the side of the waveguide substrate, the period of the second unit structures being 900–1400 nm; and / or,

[0028] The third grating includes a plurality of third unit structures arranged on the side of the waveguide substrate, the period of the third unit structure being 900–1400 nm.

[0029] In some embodiments, at least one turning region is further provided on the side of the waveguide substrate, the turning region being the positive dispersion region or the negative dispersion region, and a fourth grating is provided in the turning region, the fourth grating being used to change the propagation direction of light within the waveguide substrate;

[0030] Along the propagation direction of light within the optical waveguide, the deflection region is disposed between the coupling-in region and the coupling-out region. Alternatively, the deflection region is disposed on the side of the dispersion correction region closer to the coupling-in region.

[0031] In some embodiments, along the propagation direction of light within the optical waveguide, the deflection region is disposed on the side of the dispersion correction region near the coupling region, the edge of the dispersion correction region is arc-shaped, and the center of the arc-shaped surface coincides with the center of the deflection region.

[0032] In some embodiments, the width of the dispersion correction region satisfies the following expression:

[0033] w≤d×tanθ ic ,

[0034] Where w is the width of the dispersion correction region, d is the thickness of the waveguide substrate, and θ ic The angle at which light is incident on the dispersion correction zone.

[0035] In some embodiments, a fifth grating is disposed within the negative dispersion region. The fifth grating includes a plurality of fourth unit structures arranged sequentially on the side surface of the waveguide substrate, wherein the period P of the fourth unit structures is... b The wavelength range is 150–400 nm.

[0036] In some embodiments, the period P of the fourth unit structure b The wavelength range is 150–300 nm.

[0037] In some embodiments, the waveguide substrate includes a first substrate layer and a second substrate layer stacked together. The first substrate layer and the second substrate layer are each provided with a coupling-in region and a coupling-out region. The coupling-in region and the coupling-out region provided in the first substrate layer are respectively a first coupling-in region and a first coupling-out region. The coupling-in region and the coupling-out region provided in the second substrate layer are respectively a second coupling-in region and a second coupling-out region. Light rays coupled out from the second coupling-out region can pass through the first substrate layer and the first coupling-out region.

[0038] Wherein, the first coupling-in region and the first coupling-out region are both positive dispersion regions, and the second coupling-in region and the second coupling-out region are both negative dispersion regions; or, the first coupling-in region and the first coupling-out region are both negative dispersion regions, and the second coupling-in region and the second coupling-out region are both positive dispersion regions.

[0039] In a second aspect, an electronic device is provided, including an optomechanical system and the aforementioned optical waveguide, wherein the light-emitting portion of the optomechanical system faces the coupling region of the optical waveguide.

[0040] The beneficial effect of the optical waveguide provided in this application is that the dispersion generated after light passes through the positive dispersion region can compensate for the dispersion generated after light passes through the negative dispersion region. In this way, the processing effects of the positive and negative dispersion regions on light of different wavelengths can compensate for each other, so that light of different wavelengths incident at the same incident angle can exit with similar refraction angles. Thus, light of different wavelengths can have similar diffraction numbers when coupled out, so that the energy of light of different wavelengths coupled out is similar, thereby improving the picture effect of electronic devices. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 Schematic diagram of the propagation of light of various wavelengths in an optical waveguide for related technologies Figure 1 ;

[0043] Figure 2 Schematic diagram of the propagation of light of various wavelengths in an optical waveguide for related technologies Figure 2 ;

[0044] Figure 3 For light in Figure 2 The wave vector distribution diagram shown is shown in the optical waveguide.

[0045] Figure 4 A schematic diagram of an optical waveguide provided in an embodiment of this application;

[0046] Figure 5 This is a schematic diagram of the dispersion compensation effect;

[0047] Figure 6 A schematic diagram of the positive dispersion region provided in the embodiments of this application;

[0048] Figure 7 A schematic diagram illustrating the phase provided by the positive dispersion region for different wavelengths of light in an embodiment of this application;

[0049] Figure 8 A schematic diagram of the first unit structure provided in the embodiments of this application;

[0050] Figure 9 A schematic diagram of an optical waveguide provided in yet another embodiment of this application;

[0051] Figure 10 A schematic diagram of the fourth unit structure provided in the embodiments of this application;

[0052] Figure 11 An exploded view of an optical waveguide provided in yet another embodiment of this application;

[0053] Figure 12 for Figure 11 The diagram shows how an optical waveguide processes light.

[0054] Figure 13 for Figure 4 The wave vector distribution diagram of the optical waveguide propagation is shown.

[0055] Figure 14 A schematic diagram of an optical waveguide provided in another embodiment of this application;

[0056] Figure 15 for Figure 13 The wave vector distribution diagram of the optical waveguide propagation is shown.

[0057] Figure 16 for Figure 11 The diagram shows the structure of the optical waveguide and the distribution of the propagating wave vector.

[0058] The following are the labeling elements in the figure:

[0059] Figures 1 to 3 :

[0060] 1' Waveguide substrate; 2' Coupled-in region; 3' Coupled-out region; 4' Turning region;

[0061] Figures 4 to 16 :

[0062] 1. Waveguide substrate; 11. First substrate layer; 12. Second substrate layer; 2. Coupling region; 21. First coupling region; 22. Second coupling region; 3. Coupling out region; 31. First coupling out region; 32. Second coupling out region; 4. Turning region; 5. Dispersion correction region;

[0063] 100. First unit structure;

[0064] 200. The fourth unit structure;

[0065] 300, grating assembly; 3001, second grating; 3002, third grating. Detailed Implementation

[0066] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0067] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0068] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0069] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, "multiple sets" means two or more sets, "multiple pieces" means two or more pieces, and "multiple" means one or more, unless otherwise explicitly specified.

[0070] Smart glasses with technologies such as augmented reality (AR), virtual reality (VR), and mixed reality (MR) have gained widespread popularity among consumers in recent years. Among them, the virtual images of AR glasses can be displayed using diffraction waveguide (DWG) technology.

[0071] Figure 1 Schematic diagram of the propagation of light of various wavelengths in an optical waveguide for related technologies Figure 1 ; Figure 2 Schematic diagram of the propagation of light of various wavelengths in an optical waveguide for related technologies Figure 2 ; Figure 3 For light in Figure 2 The diagram shows the wave vector distribution propagating in the optical waveguide.

[0072] Reference Figure 1 The optical waveguide includes a waveguide substrate 1', and the side of the waveguide substrate 1' is provided with a coupling region 2', a turning region 4', and a coupling out region 3'. For a full-color image, the propagation law of light of different wavelengths in the optical waveguide is as follows: Figure 1 , Figure 2 and Figure 3As shown, due to the diffraction and dispersion characteristics of the surface relief grating, light of different wavelengths propagates at different angles in the optical waveguide. When the incident angle of the light is the same, the longer the wavelength, the larger the exit angle. This results in different numbers of diffractions occurring on the surface relief grating for different wavelengths. Short-wavelength light undergoes more diffractions than long-wavelength light, and the more diffractions, the more coupling-outs. Therefore, long-wavelength light usually has lower energy after coupling-out, while short-wavelength light has higher energy after coupling-out. This significantly affects the color performance of a single optical waveguide.

[0073] In AR glasses, a single optical waveguide weighs approximately 5-10g. Related technologies suggest reducing the overall weight of smart glasses by decreasing the number of optical waveguides within them. Since different wavelengths of light have varying energy after coupling out of a single waveguide, a monochromatic light source, such as a single shade of green, is typically used as the light source for information cues to ensure image clarity. However, this approach results in a monochromatic image, reducing the overall quality of the display.

[0074] Based on this, embodiments of this application provide an optical waveguide and an electronic device. By introducing a positive dispersion region, the diffraction numbers of short-wavelength and long-wavelength light rays in a single optical waveguide are similar, thereby making the energy of the short-wavelength and long-wavelength light rays similar, thus improving the picture quality of the electronic device.

[0075] Figure 4 This is a schematic diagram of an optical waveguide provided in an embodiment of this application.

[0076] Reference Figure 4 This application provides an optical waveguide comprising a waveguide substrate 1. A coupling-in region 2 and a coupling-out region 3 are disposed on the side of the waveguide substrate 1. The coupling-in region 2 couples light into the waveguide substrate 1. After reflection and propagation within the waveguide substrate 1, the light exits from the coupling-out region 3. One of the coupling-in region 2 and the coupling-out region 3 is a positive dispersion region, and the other is a negative dispersion region. The dispersion generated by the light passing through the positive dispersion region is used to compensate for the dispersion generated by the light passing through the negative dispersion region. When light of different wavelengths is incident on the negative dispersion region at the same angle, the longer the wavelength of the light, the larger the angle of refraction when it leaves the negative dispersion region. Conversely, when light of different wavelengths is incident on the positive dispersion region at the same angle, the longer the wavelength of the light, the smaller the angle of refraction when it leaves the positive dispersion region.

[0077] It should be noted that light can be diffracted in the coupling region 2 and the coupling region 3 to enter and leave the waveguide substrate 1. Light entering the waveguide substrate 1 can undergo total internal reflection within the waveguide substrate 1.

[0078] It should be noted that the angle of refraction when light leaves the positive / negative dispersion region refers to the angle between the direction of light exiting the positive / negative dispersion region and the direction of light entering the region. Since the wavelength of red light is longer than that of blue light, the angle of refraction of red light exiting the negative dispersion region is greater than that of blue light, and the angle of refraction of red light exiting the positive dispersion region is smaller than that of blue light. The statement that one of the insertion region 2 and the exit region 3 is a positive dispersion region, and the other is a negative dispersion region, means that when the insertion region 2 is a positive dispersion region, the exit region 3 is a negative dispersion region, and vice versa. The grating in the negative dispersion region can be a surface relief grating (SRG), while the grating in the positive dispersion region can be a non-surface relief grating.

[0079] When the coupling-in region 2 is a positive dispersion region and the coupling-out region 3 is a negative dispersion region, light rays are coupled into the waveguide substrate 1 through the positive dispersion region, propagate through reflection within the waveguide substrate 1, and then couple out through the negative dispersion region to leave the optical waveguide. When the coupling-in region 2 is a negative dispersion region and the coupling-out region 3 is a positive dispersion region, light rays are coupled into the waveguide substrate 1 through the negative dispersion region, propagate through reflection within the waveguide substrate 1, and then couple out through the positive dispersion region to leave the optical waveguide.

[0080] It should be noted that the waveguide substrate is generally sheet-shaped, and the coupling-in region 2 and coupling-out region 3 are disposed on the side with a larger area of ​​the waveguide substrate 1. In some embodiments, the coupling-in region 2 and coupling-out region 3 can be disposed on the same side of the waveguide substrate 1. In this case, the light entering the optical waveguide and the light leaving the optical waveguide propagate in opposite directions. In other embodiments, the coupling-in region 2 and coupling-out region 3 can be disposed on two opposite sides of the waveguide substrate 1. In this case, the light entering the optical waveguide and the light leaving the optical waveguide propagate in the same direction. In addition, the wave vector of the light entering the optical waveguide and the wave vector of the light leaving the optical waveguide are the same in magnitude.

[0081] Figure 5 This is a schematic diagram of the dispersion compensation effect.

[0082] Reference Figure 5 In (a), red and blue light enter the positive dispersion region at the same angle of incidence, and the exit angle of red light leaving the positive dispersion region is smaller than that of blue light leaving the positive dispersion region; see reference. Figure 5 In (b), red and blue light enter the negative dispersion region at the same angle of incidence, and the exit angle of red light leaving the negative dispersion region is greater than that of blue light leaving the negative dispersion region; see reference. Figure 5 In (c), the positive dispersion region and the negative dispersion region are integrated. The processing effects of the positive dispersion region and the negative dispersion region on red light and blue light can compensate for each other, so that red light and blue light that are incident at the same incident angle can exit at the same exit angle.

[0083] The optical waveguide provided in this application can compensate for the dispersion generated after light passes through the positive dispersion region. In this way, the processing effects of the positive and negative dispersion regions on light of different wavelengths can compensate for each other, so that light of different wavelengths incident at the same incident angle can exit with similar refraction angles. This allows light of different wavelengths to have similar diffraction numbers when coupled out, making the energy of light coupled out of different wavelengths similar, thereby improving the picture quality of electronic devices.

[0084] Figure 6 This is a schematic diagram of the positive dispersion region provided in an embodiment of this application.

[0085] Reference Figure 6 A first grating is disposed in the positive dispersion region. The first grating includes a plurality of first unit structures 100 arranged sequentially on the side of the waveguide substrate 1. The nth first unit structure 100 among the plurality of first unit structures 100 provides light with wavelength λ. Phase, the (n+1)th first unit structure 100 in the plurality of first unit structures 100 provides a wavelength of λ for light rays. Phase, It is inversely proportional to λ; where n≥1.

[0086] It should be noted that the side of the waveguide substrate 1 is parallel to the XY direction shown in the figure, and multiple first unit structures 100 can be arranged sequentially along the XY direction shown in the figure.

[0087] Inversely proportional to λ, longer wavelength light accumulates a smoother phase when propagating in the positive dispersion region, while shorter wavelength light accumulates a faster phase when propagating in the positive dispersion region. Thus, the refraction effect of the positive dispersion region on different wavelengths of light is the opposite of that of the negative dispersion region on different wavelengths. The positive and negative dispersion regions can compensate for the differences in the propagation of different wavelengths of light, reduce color shift caused by dispersion, and improve the image quality.

[0088] Figure 7 This is a schematic diagram illustrating the phase provided by the positive dispersion region for different wavelengths of light, as shown in the embodiments of this application. (Refer to...) Figure 6 and Figure 7 The nth first unit structure 100 in a plurality of first unit structures 100 pairs with wavelength λ r The light provides Phase, and the nth first unit structure 100 pairs of wavelengths of λ b The light provides Phase; the (n+1)th first unit structure 100 in a plurality of first unit structures 100 has a wavelength of λ.r The light provides Phase, and the (n+1)th first unit structure has 100 pairs of wavelengths of λ. b The light provides Phase; where λ r ≠λ b ;

[0089] This can represent the combined effect of multiple first unit structures 100, causing light of different wavelengths to produce different refraction angles, combined with... Inversely proportional to λ, the longer the wavelength of light, the smaller the angle of refraction produced when it passes through the positive dispersion region.

[0090] In this embodiment, the phase difference generated by the nth first unit structure 100 and the (n+1)th first unit structure 100 (two adjacent first unit structures 100) on the light rays Including phase dispersion and phase gradient, reference Figure 7 Phase dispersion refers to the phase difference provided by the nth first unit structure 100 and the (n+1)th first unit structure 100 for different wavelengths of light, i.e. The phase gradient refers to the phase difference between the nth first unit structure 100 and the (n+1)th first unit structure 100 (two adjacent first unit structures 100) for the same wavelength. It can be understood as Figure 7 The slope of the middle slope line.

[0091] In some embodiments, the effect of the positive dispersion region on light satisfies the following expression (1):

[0092]

[0093] Where, n ta Let n be the refractive index of the exiting medium in the positive dispersion region. ia Let θ be the refractive index of the incident medium within the positive dispersion region. ta θ is the angle at which light exits the positive dispersion region. ia P is the angle at which light is incident on the positive dispersion region. a It is the period of the first unit structure 100.

[0094] It should be noted that the effect of the positive dispersion region on light does not satisfy the general grating equation. The effect of the positive dispersion region on light is related not only to the period of the first unit structure 100, but also to the phase dispersion provided by the first unit structure 100. The expression (2) is as follows:

[0095]

[0096] Where N is the diffraction order of the grating in the positive dispersion region.

[0097] Generally speaking, the period of the positive dispersion region is very small relative to the incident wavelength, and no non-zero diffraction order will be generated. Therefore, expression (2) can simplify expression (1).

[0098] Furthermore, for light of the same wavelength, since the phase difference provided by two adjacent first unit structures 100 is constant, according to expression (1), the light of that wavelength will travel at a fixed angle θ. ta Launch and enter Figure 6 Total internal reflection propagates within the waveguide substrate 1. The first unit structure 100 provides different phases for different wavelengths of light. For example, when λ... r λ is the wavelength of red light. b When the wavelength is blue light, the nth first unit structure 100 will provide respectively and The phase, in the (n+1)th first unit structure 100, will respectively provide and phase, This means that red and blue light are emitted at different angles. Furthermore, because the positive dispersion region has… It is inversely proportional to λ, therefore the emission angle of blue light is greater than that of red light.

[0099] In some embodiments, the number of first unit structures 100 is 4 to 8 within one phase period length.

[0100] It should be noted that the (n+m)th first unit structure 100 among the multiple first unit structures 100 provides light with wavelength λ. Phase, where m≥1, when When equal to or approximately equal to 2π, the physical lengths of the center of the nth first unit structure 100 and the center of the (n+m)th first unit structure 100 are one phase period length as described above.

[0101] Within one phase period, the phase difference between two first unit structures 100 reaches 2π, meaning that light completes a "phase cycle" after passing through these first unit structures 100. This allows light to propagate with total internal reflection within the waveguide substrate 1 in a stable manner. Within one phase period, the number of first unit structures is limited to 4–8. This allows the number of first unit structures 100 to match the phase period, ensuring effective control of the light phase. Furthermore, it allows for a moderate density of the first unit structures 100, reducing manufacturing difficulty.

[0102] In some embodiments, the number of first unit structures 100 is 4 to 6 within one phase period length.

[0103] Within a phase period, the number of first unit structures 100 is 4 to 6. This allows the number of first unit structures 100 to match the phase period, ensuring effective control of the light phase. In addition, it also allows for a moderate density of first unit structures 100, reducing the difficulty of processing.

[0104] In some embodiments, the first unit structure 100 is a metasurface structure.

[0105] It should be noted that metasurfaces are artificially designed layered material structures with a thickness smaller than the wavelength of light. Based on their in-plane structure, metasurfaces can be divided into two types: one with microstructures possessing lateral subwavelength (scales smaller than the wavelength of light), and the other as a uniform film layer. Based on the type of wave being modulated, metasurfaces can be classified as optical metasurfaces, acoustic metasurfaces, mechanical metasurfaces, etc. Among these, optical metasurfaces are the most common type, as they can manipulate the polarization, phase, amplitude, and frequency characteristics of electromagnetic waves through subwavelength microstructures.

[0106] Metasurface structures have the following functions:

[0107] (1) Polarization control by metasurface structures. In terms of polarization, metasurface structures can realize functions such as polarization conversion, optical rotation, and vector beam generation.

[0108] (2) Amplitude modulation by metasurface structures. Metasurface structures can achieve asymmetric light transmission, anti-reflection, increased transmission, magnetic mirrors, and electromagnetically induced transparency-like effects (EIT-like effects).

[0109] (3) Frequency modulation of metasurface structures. The microstructures of metasurface structures can achieve strong local field enhancement under resonance conditions. Utilizing these local field enhancement effects, nonlinear signals or fluorescence signals can be enhanced. In the visible light band, different frequencies of light correspond to different colors. The frequency selectivity of metasurface structures can be used to realize structural colors. The colors we see in nature can be divided into two main categories based on their generation principles: one category is determined by the reflection, absorption, and scattering properties of materials, such as common pigments and the colors of plastic bags; the other category is determined by the structure of the substance, rather than the material used, i.e., structural colors, such as the colors of butterflies and certain fish. Using metasurface structures, the colors of metasurface structures can be freely modulated by changing the geometric parameters such as the size and shape of their structural units. This can be used in fields such as high-pixel imaging and visualized biosensing.

[0110] (4) Phase modulation by metasurface structures. Phase is a core property of electromagnetic waves. Equiphase surfaces determine the propagation direction of electromagnetic waves, and the phase of an image contains its three-dimensional information. By controlling the phase of electromagnetic waves, functions such as beam deflection, superlensing, super holography, vortex light generation, encoding, invisibility, and illusion can be realized.

[0111] (5) Combined manipulation of multiple degrees of freedom of electromagnetic waves by metasurface structures. Metasurface structures can simultaneously manipulate the phase, amplitude, polarization, and other degrees of freedom of electromagnetic waves. For example, by jointly manipulating the phase and amplitude of electromagnetic waves, three-dimensional super-holography can be realized; by jointly manipulating the phase and polarization of electromagnetic waves, vector vortex light can be realized; and by jointly manipulating the phase and frequency of electromagnetic waves, functions such as nonlinear superlenses can be realized.

[0112] (6) Modulation of waveguide modes by metasurface structures. The concept of "meta-optics" can be combined with various optical waveguide platforms. By integrating metasurfaces or metamaterials onto various optical waveguide structures, the optical signals in the waveguide can be flexibly and freely manipulated at the subwavelength scale. Using dielectric optical waveguide structures with metasurfaces integrated on the upper surface, multifunctional applications such as optical coupling, optical detection, polarization / wavelength demultiplexing, structured light excitation, waveguide mode conversion, on-chip optical signal conversion, optical neural networks, and optical routing can be realized.

[0113] When the first unit structure 100 adopts a metasurface structure, it can possess high-precision phase modulation capability at the subwavelength scale, achieving an inverse relationship between the phase difference and wavelength in the positive dispersion region, thereby enhancing wavelength selectivity and dispersion management. Furthermore, its compact structure can be used to reduce the optical waveguide volume, making it compatible with planar integration technology.

[0114] Figure 8 This is a schematic diagram of the first unit structure 100 provided in an embodiment of this application.

[0115] Reference Figure 6 and Figure 8 In some embodiments, the first unit structure 100 is columnar. Referring to... Figure 8 In (a), the first unit structure 100 can be a rectangular column; refer to Figure 8 In (b), the first unit structure 100 can be a hollow rectangular column; refer to Figure 8 In (c), the first unit structure 100 can be cylindrical; refer to Figure 8 In (d), the first unit structure 100 can be a hollow cylinder; refer to Figure 8 In (e), the first unit structure 100 can be an X-shaped column (the column cross-section is X-shaped).

[0116] It should be noted that the shape of the first unit structure 100 can be varied. Figure 8 This is merely a partial example of the shape of the first unit structure 100, and the embodiments of this application are not limited thereto. Furthermore, the shapes of the plurality of first unit structures 100 within the positive dispersion region can be the same, different, or partially the same and partially different. Additionally, the period P of the plurality of first unit structures 100 within the positive dispersion region... a They can be the same, or they can be different, or they can be partially the same and partially different.

[0117] It should be noted that the diameter of the column in the first unit structure 100 is D, where the diameter D is less than the period P of the first unit structure 100. a The diameter D of the cylinders of multiple first unit structures 100 within the positive dispersion region can be the same, different, or partially the same and partially different. The height H of the cylinders of the first unit structure 100 can be the same, different, or partially the same and partially different.

[0118] When the first unit structure 100 is cylindrical, its axisymmetric geometric characteristics can achieve subwavelength-scale phase modulation through precise adjustment of diameter and height, satisfying the inverse relationship between phase difference and wavelength in the positive dispersion region. The cylindrical structure is compatible with mass production processes such as photolithography and etching, with high processing yield and controllable dimensional accuracy. It can be efficiently vertically coupled with the waveguide substrate 1. Compared with irregular structures, it has significant advantages in terms of phase modulation freedom, polarization dependence, and processing cost.

[0119] In some embodiments, the material of the first unit structure 100 may be one of silicon, silicon oxide, titanium dioxide, and silicon nitride, or a combination of at least two of the above materials.

[0120] In some embodiments, the period P of the first unit structure 100 a The wavelength range is 150–400 nm.

[0121] The period P of the first unit structure 100 a With a setting of 150–400 nm, the wavelength and refraction angle of light in the positive dispersion region can be precisely controlled. It is also compatible with mass production processes such as ultraviolet lithography, resulting in high processing yield and low cost.

[0122] In some embodiments, the period P of the first unit structure 100 a The wavelength range is 150–300 nm.

[0123] The period P of the first unit structure 100 aSetting it to 150-400nm allows for more precise control of the relationship between the wavelength of light and the angle of refraction in the positive dispersion region, improving dispersion compensation between the positive and negative dispersion regions and thus enhancing the image quality.

[0124] Reference Figure 4 In some embodiments, at least one dispersion correction region 5 is also provided on the side of the waveguide substrate 1. Along the propagation direction of light in the optical waveguide, the dispersion correction region 5 is located between the coupling-in region 2 and the coupling-out region 3. A grating assembly 300 is provided in the dispersion correction region 5. The grating assembly 300 is used to change the total internal reflection angle of the preset wavelength light in the waveguide substrate 1.

[0125] It should be noted that when there is one dispersion correction region 5, in some embodiments, the coupling-in region 2 and the coupling-out region 3 are located on the same side of the waveguide substrate 1. In this embodiment, the dispersion correction region 5 can be located on the same side of the waveguide substrate 1 as the coupling-in region 2 and the coupling-out region 3, or it can be located on the opposite side of the waveguide substrate 1. In other embodiments, the coupling-in region 2 and the coupling-out region 3 are respectively located on opposite sides of the waveguide substrate 1, and the dispersion correction region 5 can be on the same side as the coupling-in region 2 or the coupling-out region 3. When there are two or more dispersion correction regions 5, the two dispersion correction regions 5 can be located on the same side of the waveguide substrate 1 or on the opposite side of the waveguide substrate 1. This application embodiment does not impose any restrictions on this.

[0126] It should be noted that preset wavelength light refers to light of a single wavelength (or a wavelength within a relatively narrow bandwidth). For example, preset wavelength light can refer to red light (wavelength of 620-760nm), blue light (wavelength of 400-495nm), green light (wavelength of 500nm-560nm), etc.

[0127] The dispersion correction zone 5 can change the total internal reflection angle of light of a specific wavelength in the waveguide, which can accurately compensate for the refraction angle deviation caused by dispersion of different wavelengths of light, reduce image distortion, balance the brightness difference of multicolor light, and improve the picture effect.

[0128] In some embodiments, the grating assembly 300 includes a Bragg grating, a volume Bragg grating, and / or a polarizing volume holographic grating.

[0129] It should be noted that the grating assembly 300 contains multiple gratings, which can be Bragg gratings, volume Bragg gratings, or polarizing volume holographic gratings. These gratings can be of the same type (e.g., all gratings are Bragg gratings or volume Bragg gratings) or different types (e.g., some gratings are Bragg gratings, another part are polarizing volume holographic gratings, and yet another part are volume Bragg gratings).

[0130] Bragg gratings, based on their periodic structure, can generate strong reflections of specific wavelengths of light, accurately filtering and adjusting the total internal reflection angle of preset wavelengths to effectively correct dispersion. Volume Bragg gratings, based on a three-dimensional periodic structure within a volume, achieve high angular selectivity and wavelength resolution, enabling dispersion compensation through large-angle light manipulation and a wide spectrum. Polarization volume holographic gratings can utilize polarization characteristics to independently control light of different polarization states, reducing optical loss and crosstalk, and enhancing the polarization compatibility of optical waveguides. These three technologies can be used individually or in combination, thus meeting the dispersion correction needs of different scenarios while improving the optical performance of optical waveguides.

[0131] In some embodiments, the grating assembly 300 includes a second grating 3001 and a third grating 3002, which are arranged along a direction parallel to the side surface of the waveguide substrate 1, or stacked along the thickness direction of the waveguide substrate 1. The second grating 3001 is used to change the total internal reflection angle of the first preset wavelength light in the waveguide substrate 1; the third grating 3002 is used to change the total internal reflection angle of the second preset wavelength light in the waveguide substrate 1, wherein the wavelengths of the first preset wavelength light and the second preset wavelength light are not equal.

[0132] It should be noted that the second grating 3001 can be the aforementioned Bragg grating, volume Bragg grating, or polarizing volume holographic grating, and the third grating 3002 can also be the aforementioned Bragg grating, volume Bragg grating, or polarizing volume holographic grating. The second grating 3001 and the third grating 3002 can be arranged parallel to each other on the surface of the waveguide substrate 1, or they can be stacked on the surface of the waveguide substrate 1.

[0133] It should be noted that the wavelengths of the first preset wavelength light and the second preset wavelength light are not equal. For example, the first preset wavelength light can be red light (wavelength of 620-760nm), and the second preset wavelength light can be blue light (wavelength of 400-495nm). Of course, in other embodiments, the first preset wavelength light and the second preset wavelength light can also be light of other wavelengths, and this application embodiment does not impose any limitations on this.

[0134] By setting up a second grating 3001 and a third grating 3002, the total internal reflection angle can be adjusted independently for different preset wavelengths of light. This can accurately compensate for the dispersion deviation of each wavelength of light, balance the brightness difference, and reduce image distortion.

[0135] In some embodiments, the second grating 3001 includes a plurality of second unit structures arranged on the side of the waveguide substrate 1, the period of the second unit structures being 900–1400 nm.

[0136] The second unit structure of the second grating 3001 is set with a period of 900-1400nm, which can form efficient coupling with visible light to achieve precise dispersion correction and optical signal optimization.

[0137] In some embodiments, the third grating 3002 includes a plurality of third unit structures arranged on the side of the waveguide substrate 1, the period of the third unit structures being 900–1400 nm.

[0138] It should be noted that the periods of the second grating 3001 and the third grating 3002 can be the same or different.

[0139] The third unit structure of the third grating 3002 has a period of 900-1400nm, which can form efficient coupling with visible light to achieve precise dispersion correction and optical signal optimization.

[0140] In some embodiments, at least one turning region 4 is also provided on the side of the waveguide substrate 1. The turning region 4 is a positive dispersion region or a negative dispersion region. A fourth grating is provided in the turning region 4. The fourth grating is used to change the propagation direction of light in the waveguide substrate 1. Along the propagation direction of light in the optical waveguide, the turning region 4 is located between the coupling-in region 2 and the coupling-out region 3. The turning region 4 is located on the side of the dispersion correction region 5 near the coupling-in region 2, or the turning region 4 is located on the side of the dispersion correction region 5 near the coupling-in region 2.

[0141] A turning region 4 is set on the side of the waveguide substrate 1 between the coupling region 2 and the coupling region 3. The light propagation direction is changed by the grating inside the turning region, which can adjust the optical path direction in the optical waveguide, increase the number of total internal reflections and the flexibility of the propagation path. At the same time, by coordinating with the position of the dispersion correction region 5, the order of angular deviation compensation for different wavelengths of light can be optimized. For example, the optical path direction can be initially adjusted by the turning region 4 and the wavelength can be separated by using dispersion characteristics. Then, the dispersion correction region 5 can provide precise compensation. Alternatively, the optical path angle can be fixed by first correcting and then turning the turning region. In the end, the optical field distribution can be made uniform, the field of view can be expanded and the multi-wavelength light can be coordinated and controlled, thereby improving the dispersion management accuracy.

[0142] Figure 9 This is a schematic diagram of an optical waveguide provided in yet another embodiment of this application.

[0143] Reference Figure 9 In some embodiments, along the propagation direction of light within the optical waveguide, the deflection region 4 is disposed on the side of the dispersion correction region 5 near the coupling region 2, the edge of the dispersion correction region 5 is arc-shaped, and the center of the arc-shaped surface coincides with the center of the deflection region 4.

[0144] It is understandable that the coupled image has a certain divergence angle, and when light of each wavelength leaves the turning region 4, the light rays will form a certain divergence angle in the plane of the waveguide substrate 1. By making the edge of the dispersion correction region 5 an arc surface, and aligning the center of the arc surface with the center of the turning region 4, light can be allowed to enter the dispersion correction region 5 only once, effectively reducing stray light and improving the efficiency of light processing.

[0145] Reference Figure 4 The width of the dispersion correction region 5 satisfies the following expression:

[0146] w≤d×tanθ ic ,

[0147] Where w is the width of the dispersion correction region 5, d is the thickness of the waveguide substrate 1, and θ ic The angle at which the light is incident on the dispersion correction zone 5.

[0148] The width w of the dispersion correction region 5 satisfies w ≤ d × tanθ ic The lateral dimension of the dispersion correction zone 5 can be precisely defined by the thickness of the waveguide substrate 1 and the incident angle of the light, ensuring that the light always meets the total internal reflection condition when propagating in the zone, avoiding total internal reflection failure caused by energy leakage and dispersion; at the same time, it can optimize the overall compactness of the optical waveguide structure and reduce the overall size.

[0149] In the embodiments of this application, the width w of the dispersion correction region 5 is much smaller than the widths of the coupling region 2, the coupling region 3, and the turning region 4.

[0150] Figure 10 This is a schematic diagram of the fourth unit structure 200 provided in an embodiment of this application.

[0151] Reference Figure 10 In some embodiments, a fifth grating is disposed in the negative dispersion region. The fifth grating includes a plurality of fourth unit structures 200 arranged sequentially on the side of the waveguide substrate 1, and the period P of the fourth unit structures 200 is... b The wavelength range is 150–400 nm.

[0152] It should be noted that the shape of the fourth unit structure 200 can be varied. Figure 10 The fourth unit structure 200 may be a partial alternative shape, and the fourth unit structure 200 may also be in the form of other than Figure 10 Other shapes besides those described herein are not limited to the embodiments of this application.

[0153] The fourth unit structure in the negative dispersion region has a period of 200 periods, P. bWith a period set to 150–400 nm, this period falls within the subwavelength range, enabling different wavelengths of light to exhibit refractive characteristics opposite to positive dispersion. Specifically, longer wavelengths have a larger refraction angle, while shorter wavelengths have a smaller refraction angle, accurately compensating for system dispersion. Compared to larger periods, this range reduces higher-order diffraction interference, lowers optical field clutter and energy loss, and improves optical transmission efficiency. Furthermore, this period is compatible with mainstream photolithography processes, reducing processing difficulty and cost, ensuring structural precision and stability, and facilitating efficient integration with the waveguide substrate.

[0154] In some embodiments, the period P of the fourth unit structure 200 b The wavelength range is 150–300 nm.

[0155] The fourth unit structure in the negative dispersion region has a period of 200 periods, P. b Setting the wavelength to 150–300 nm can significantly enhance the negative dispersion effect in the negative dispersion region, complementing the positive dispersion region and achieving dispersion neutralization across the entire wavelength range. This period excites only a single diffraction order, effectively suppressing optical field disorder and improving optical field uniformity.

[0156] Figure 11 An exploded view of an optical waveguide provided in yet another embodiment of this application; Figure 12 for Figure 11 The diagram shows how an optical waveguide processes light.

[0157] Reference Figure 11 and Figure 12 In some embodiments, the waveguide substrate 1 includes a first substrate layer 11 and a second substrate layer 12 stacked together. The sides of the first substrate layer 11 and the sides of the second substrate layer 12 are provided with coupling-in regions and coupling-out regions. The coupling-in regions and coupling-out regions provided in the first substrate layer 11 are respectively the first coupling-in region 21 and the first coupling-out region 31, and the coupling-in regions and coupling-out regions provided in the second substrate layer 12 are respectively the second coupling-in region 22 and the second coupling-out region 32. The light rays coupled out from the second coupling-out region 32 can pass through the first substrate layer 11 and the first coupling-out region 31. The first coupling-in region 21 and the first coupling-out region 31 are both positive dispersion regions, and the second coupling-in region 22 and the second coupling-out region 32 are both negative dispersion regions, or the first coupling-in region 21 and the first coupling-out region 31 are both negative dispersion regions, and the second coupling-in region 22 and the second coupling-out region 32 are both positive dispersion regions.

[0158] It should be noted that the first coupling-in region 21 and the first coupling-out region 31 of the first substrate 11 are both positive dispersion regions or both negative dispersion regions, and the second coupling-in region 22 and the second coupling-out region 32 of the second substrate 12 are both negative dispersion regions or both positive dispersion regions. When the first coupling-in region 21 and the first coupling-out region 31 of the first substrate 11 are both positive dispersion regions, the second coupling-in region 22 and the second coupling-out region 32 of the second substrate 12 are both negative dispersion regions. When the first coupling-in region 21 and the first coupling-out region 31 of the first substrate 11 are both negative dispersion regions, the second coupling-in region 22 and the second coupling-out region 32 of the second substrate 12 are both positive dispersion regions.

[0159] It should be noted that the first substrate layer 11 and the second substrate layer 12 are stacked. The orthographic projection of the second substrate layer 12 onto the surface of the first substrate layer 11 coincides with the first substrate layer 11. The orthographic projection of the second coupling region 22 onto the surface of the first substrate layer 11 coincides with the first coupling region 21. The orthographic projection of the second coupling region 32 onto the surface of the first substrate layer 11 coincides with the first coupling region 31. In this way, the light rays coupled from the second coupling region 32 can pass through the first substrate layer 11 and the first coupling region 31, and the light rays coupled from the second coupling region 32 and the light rays coupled from the first coupling region 31 can be integrated together.

[0160] When the waveguide substrate 1 employs a stacked first substrate layer 11 and a second substrate layer 12, and the coupling-in and coupling-out regions of each substrate layer are both positive or negative dispersion regions, a complementary dispersion compensation mechanism can be formed, precisely controlling the total internal reflection angle and propagation path of light of different wavelengths. Furthermore, although the light emitted from each substrate layer exhibits color inhomogeneity, the superposition of the emitted light from two substrate layers can make the total emitted energy of different wavelengths approximately similar, thereby achieving dispersion compensation across multiple substrate layers.

[0161] The following examples will further illustrate this point.

[0162] Reference Figure 4 , Figure 4 The optical waveguide shown includes a coupling region 2, a turning region 4, a dispersion correction region 5, and a coupling out region 3 disposed on the side of the waveguide substrate 1. The coupling region 2 and the turning region 4 are positive dispersion regions, and the coupling out region 3 is a negative dispersion region. The period of the first unit structure 100 within the coupling region 2 is P. a The period of the grating in the dispersion correction region 5 is P. c The period of the fourth unit structure 200 in coupling region 3 is P. b The vector directions of coupling region 2, turning region 4, dispersion correction region 5, and coupling region 3 are θ1, θ2, θ3, and θ4, respectively. (The positive angle is a rotation in the counterclockwise direction shown in the figure, with the positive X-axis as the reference). For a one-dimensional periodic structure, the vector direction is the direction in which the structure undergoes periodic changes, i.e., the X-axis direction in the figure.

[0163] Figure 13 for Figure 4 The diagram shows the wave vector distribution of the optical waveguide propagation.

[0164] Reference Figure 13 , Figure 13 In the diagram, (a) represents the transmission process of light in the coupling region 2 and the deflection region 4. Figure 13 (b) in the diagram represents the transmission process of light in the dispersion correction region 5. Figure 13 (c) in the figure represents the transmission process of light in the coupling region 3.

[0165] refer to Figure 4 and Figure 13 Light rays from the optomechanical system of the electronic device are coupled into the optical waveguide after entering region 2, deflected in region 4 and dilated in the -y direction, chromatic aberration corrected in region 5, and coupled out in region 3 and dilated in the -x direction. The dispersion compensation process is illustrated by the example of red and blue light both entering the waveguide at 0°, propagating within it. Assume the wavelengths of the red and blue light are λ... r and λ b If the refractive index of waveguide substrate 1 is n, then the incident angles of red and blue light when entering coupling region 3 are... and The following conditions must be met:

[0166]

[0167] in, and Corresponding to Figure 13 (c) shows the angle of light rays represented by the centers of the red and blue light rectangles. The incident angles of red and blue light entering the dispersion correction zone 5. and The following conditions must be met:

[0168]

[0169] in, and Corresponding to Figure 13 The angle of light represented by the center of the red and blue light rectangles in (b) of the diagram.

[0170] It can be seen that when red and blue light first enter the dispersion correction region 5, the propagation angle of red light is the smallest, and that of blue light is the largest. Therefore, the number of pupil dilations before red light enters the dispersion correction region 5 is greater than that of blue light. After the light interacts with the dispersion correction region 5, the propagation angle of red light leaving the region 5 will be smaller than that of blue light. Therefore, when the light propagates in the coupling region 3, the number of pupil dilations for blue light will be greater than that for red light. Since pupil dilation and coupling occur simultaneously within the coupling region 3, the final number of coupling out for red and blue light is approximately the same.

[0171] To ensure that the propagation angle of red light is minimized and that of blue light is maximized when red and blue light first enter the dispersion correction region 5, and that the pupil dilation times for red light are greater than those for blue light, positive dispersion needs to be introduced into the coupling region 2 and the reversal region 4. If the angles at which red and blue light are incident on the coupling region 2 and the reversal region 4 are respectively... (Since the angle of incidence of the light was initially defined as 0° in this example, therefore) If the above angles satisfy the following relationship:

[0172]

[0173]

[0174] From the above equation, we can obtain the phase dispersion gradient provided by the positive dispersion coupling region 2 and the turning region 4. The following conditions must be met:

[0175]

[0176] This means that the phase dispersion gradient values ​​provided by coupling region 2 and transition region 4 are not unique, that is, there are countless possible values. Figure 7 The combinations of slope values ​​shown can satisfy the functional requirements of optical waveguides in the positive dispersion region. Each combination corresponds to a specific optical waveguide design.

[0177] The dispersion compensation process for light rays at other angles is the same as described above, and will not be repeated here in the embodiments of this application. Due to the phase dispersion gradient It is only related to the wavelength and not to the angle of incidence of the light, so the same optical waveguide design can automatically work for light rays at any angle of incidence.

[0178] Furthermore, it's important to note that although the pupil expansion directions of the positive and negative dispersion regions are orthogonal, considering the image's definite field of view and the optical engine's definite exit pupil size, the image brightness across all wavelengths is relatively uniform after pupil expansion through the positive and negative dispersion regions. Alternatively, the pupil expansion directions of the positive and negative dispersion regions can be made non-orthogonal, which also ensures uniform image brightness across all wavelengths after dispersion compensation.

[0179] Figure 9 The basic structure and regional composition of the optical waveguide shown are similar to Figure 4 The optical waveguides shown are similar, the difference being that... Figure 9 The dispersion correction region 5 of the optical waveguide shown has a curved edge, and its width w is much smaller than that of other regions. If the angle at which light is incident on the dispersion correction region 5 is... Then the width w of the dispersion correction region 5 satisfies:

[0180]

[0181] Where d is the waveguide thickness.

[0182] Furthermore, the boundary of the dispersion correction zone 5 is curved, and its boundary can be an arc surface located on a circle with the radius determined by the maximum angular ray emitted from the center point of the deflection zone 4.

[0183] Figure 14 A schematic diagram of an optical waveguide provided in another embodiment of this application; Figure 15 for Figure 13 The diagram shows the wave vector distribution of the optical waveguide propagation.

[0184] Reference Figure 14 In some embodiments, the optical waveguide may have multiple turning regions 4 and dispersion correction regions 5, wherein, Figure 14 The optical waveguide shown has two turning regions 4 and two dispersion correction regions 5. Figure 14 The optical waveguide shown has a positive dispersion region (coupled-in region 2) and two folding regions (4), while the output region (3) is a negative dispersion region. (Refer to...) Figure 15 , Figure 13 In the diagram, (a) represents the transmission process of light in the coupling region 2 and the deflection region 4. Figure 13 (b) in the figure represents the transmission process of light in the coupling region 3.

[0185] In this embodiment, an optical waveguide has multiple turning regions 4 and multiple dispersion correction regions 5. As long as the wave vector of the outgoing light is the same in magnitude and direction as that of the incident light (coupled in and coupled out are located on opposite sides of the optical waveguide) or opposite (coupled in and coupled out are located on the same side of the optical waveguide) after all possible changes in wave vector, dispersion compensation can be achieved.

[0186] Figure 16 for Figure 11 The diagram shows the structure of the optical waveguide and the distribution of the propagating wave vector.

[0187] Reference Figure 11 and Figure 16 The waveguide substrate 1 includes a first substrate layer 11 and a second substrate layer 12. Figure 16The optical waveguide shown may not require the dispersion correction region 5. For example, Figure 16 In this context, (a) can represent the first substrate 11 and the first coupling-in region 21 and the first coupling-out region 31 disposed on the side of the first substrate 11, wherein the first coupling-in region 21 and the first coupling-out region 31 are both positive dispersion regions. Figure 16 (b) in the image represents the light rays in the image. Figure 16 The propagation wave vector distribution diagram in (a) is shown. Figure 16 (c) in the figure can represent the second substrate 12 and the second coupling region 22 and the second coupling region 32 disposed on the side of the second substrate 12, wherein the second coupling region 22 and the second coupling region 32 are both negative dispersion regions. Figure 16 (d) in the figure represents the light ray at... Figure 16 The propagation wave vector distribution diagram in (c) is shown.

[0188] Figure 11 The first substrate layer 11 of the optical waveguide shown contains only a positive dispersion region, while the second substrate layer 12 contains only a negative dispersion region. Although the coupled rays from each substrate layer exhibit color inhomogeneity, meaning that the diffraction and coupling times differ for different wavelengths, the superposition of the coupled rays from the two substrate layers can make the total coupled energy of different wavelengths approximately similar, thereby achieving dispersion compensation between multiple layers.

[0189] This application also provides an electronic device, including an optomechanism and an optical waveguide in any of the above embodiments, wherein the light-emitting part of the optomechanism faces the coupling region 2 of the optical waveguide.

[0190] It should be noted that electronic devices can be AR glasses, virtual reality (VR) glasses, extended reality (XR) glasses, artificial intelligence (AI) glasses, or mixed reality (MR) glasses, etc.

[0191] It should be noted that the optical waveguides in AR / VR devices are used in near-eye display systems (such as Microsoft HoloLens and Magic Leap). The light image generated by the micro-projection chip is coupled into the optical waveguide and transmitted to the human eye through total internal reflection, realizing a thin, wide field of view virtual image overlay (replacing the traditional mirror solution).

[0192] Since the positive and negative dispersion regions of the optical waveguide in any of the above embodiments can compensate for each other in processing light of different wavelengths, the energy coupled out by light of different wavelengths is similar. Therefore, electronic devices containing this optical waveguide can display multi-color images with good image quality.

[0193] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An optical waveguide, characterized in that, The system includes a waveguide substrate, with a coupling-in region and a coupling-out region disposed on its side. The coupling-in region couples light into the waveguide substrate, and the light propagates through reflection within the waveguide substrate before exiting from the coupling-out region. One of the coupling-in region and the coupling-out region is a positive dispersion region, and the other is a negative dispersion region. The dispersion generated by light passing through the positive dispersion region is used to compensate for the dispersion generated by light passing through the negative dispersion region. When light of different wavelengths is incident on the negative dispersion region at the same angle, the longer the wavelength of the light leaves the negative dispersion region, the larger the angle of refraction. When light of different wavelengths is incident on the positive dispersion region at the same angle, the longer the wavelength of the light leaves the positive dispersion region, the smaller the angle of refraction.

2. The optical waveguide as described in claim 1, characterized in that, A first grating is disposed within the positive dispersion region. The first grating comprises a plurality of first unit structures arranged sequentially on the side surface of the waveguide substrate. The nth first unit structure among the plurality of first unit structures provides light with wavelength λ. Phase, the (n+1)th of the plurality of first unit structures provides for light rays with wavelength λ. Phase, It is inversely proportional to λ; Where n≥1.

3. The optical waveguide as described in claim 2, characterized in that, The nth first unit structure in a plurality of first unit structures is for wavelength λ r The light provides Phase, and the nth first unit structure for wavelength λ b The light provides Phase; The (n+1)th first unit structure in a plurality of first unit structures corresponds to a wavelength of λ. r The light provides Phase, and the (n+1)th first unit structure with wavelength λ b The light provides Phase; Where, λ r ≠λ b ; 4. The optical waveguide as described in claim 3, characterized in that, The effect of the positive dispersion region on light satisfies the following expression: Where, n ta Let n be the refractive index of the exiting medium in the positive dispersion region. ia Let θ be the refractive index of the incident medium within the positive dispersion region. ta θ is the angle at which light exits the positive dispersion region. ia P is the angle at which light is incident on the positive dispersion region. a It is the period of the first unit structure.

5. The optical waveguide as described in claim 2, characterized in that, The period P of the first unit structure a The wavelength range is 150–400 nm.

6. The optical waveguide as described in claim 5, characterized in that, The period P of the first unit structure a The wavelength range is 150–300 nm.

7. The optical waveguide as described in claim 2, characterized in that, Within one phase period, the number of the first unit structures is 4 to 8.

8. The optical waveguide as described in claim 2, characterized in that, The first unit structure is a metasurface structure.

9. The optical waveguide according to any one of claims 1-8, characterized in that, At least one dispersion correction region is also provided on the side of the waveguide substrate. Along the propagation direction of light in the optical waveguide, the dispersion correction region is located between the coupling-in region and the coupling-out region. A grating assembly is provided in the dispersion correction region. The grating assembly is used to change the total internal reflection angle of light of a preset wavelength in the waveguide substrate.

10. The optical waveguide as described in claim 9, characterized in that, The grating assembly includes a Bragg grating, a volume Bragg grating, and / or a polarizing volume holographic grating.

11. The optical waveguide as described in claim 9, characterized in that, The grating assembly includes a second grating and a third grating, the second grating and the third grating being arranged in a direction parallel to the side surface of the waveguide substrate, or the second grating and the third grating being stacked in a direction along the thickness of the waveguide substrate; The second grating is used to change the total internal reflection angle of the first preset wavelength light on the waveguide substrate; The third grating is used to change the total internal reflection angle of the second preset wavelength light on the waveguide substrate; The wavelengths of the first preset wavelength light and the second preset wavelength light are not equal.

12. The optical waveguide as described in claim 11, characterized in that, The second grating includes a plurality of second unit structures arranged on the side of the waveguide substrate, the period of the second unit structures being 900–1400 nm; and / or, The third grating includes a plurality of third unit structures arranged on the side of the waveguide substrate, the period of the third unit structure being 900–1400 nm.

13. The optical waveguide as described in claim 9, characterized in that, The waveguide substrate is further provided with at least one turning region on its side, the turning region being either the positive dispersion region or the negative dispersion region, and a fourth grating is provided within the turning region, the fourth grating being used to change the propagation direction of light within the waveguide substrate; Along the propagation direction of light within the optical waveguide, the deflection region is disposed between the coupling-in region and the coupling-out region. Alternatively, the deflection region is disposed on the side of the dispersion correction region closer to the coupling-in region.

14. The optical waveguide as described in claim 13, characterized in that, Along the propagation direction of light within the optical waveguide, the deflection region is located on the side of the dispersion correction region near the coupling region, the edge of the dispersion correction region is arc-shaped, and the center of the arc-shaped surface coincides with the center of the deflection region.

15. The optical waveguide as described in claim 9, characterized in that, The width of the dispersion correction region satisfies the following expression: w≤d×tanθ ic , Where w is the width of the dispersion correction region, d is the thickness of the waveguide substrate, and θ ic The angle at which light is incident on the dispersion correction zone.

16. The optical waveguide according to any one of claims 1-8, characterized in that, A fifth grating is disposed within the negative dispersion region. The fifth grating comprises multiple fourth unit structures arranged sequentially on the side surface of the waveguide substrate, wherein the period P of the fourth unit structure is... b The wavelength range is 150–400 nm.

17. The optical waveguide as described in claim 16, characterized in that, The period P of the fourth unit structure b The wavelength range is 150–300 nm.

18. The optical waveguide according to any one of claims 1-8, characterized in that, The waveguide substrate includes a first substrate layer and a second substrate layer stacked together. The first substrate layer and the second substrate layer are each provided with a coupling-in region and a coupling-out region. The coupling-in region and the coupling-out region provided in the first substrate layer are respectively a first coupling-in region and a first coupling-out region. The coupling-in region and the coupling-out region provided in the second substrate layer are respectively a second coupling-in region and a second coupling-out region. Light rays coupled out from the second coupling-out region can pass through the first substrate layer and the first coupling-out region. Wherein, the first coupling-in region and the first coupling-out region are both positive dispersion regions, and the second coupling-in region and the second coupling-out region are both negative dispersion regions; or, the first coupling-in region and the first coupling-out region are both negative dispersion regions, and the second coupling-in region and the second coupling-out region are both positive dispersion regions.

19. An electronic device comprising an optomechanic, characterized in that, It also includes an optical waveguide as described in any one of claims 1-18, wherein the light-emitting portion of the optomechanism faces the coupling region of the optical waveguide.

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