Integrated optical chip for augmented reality display and preparation method thereof

Abstract

The present invention discloses an integrated optical chip for augmented reality display and a preparation method thereof, belonging to the field of optoelectronics and display technology. The integrated optical chip includes a first end face coupler, a second end face coupler, and a third end face coupler, and the first end face coupler, the second end face coupler, and the third end face coupler are sequentially provided with a 2×2 multimode interference coupler, a microring filter, a 1×2 multimode interference coupler, an interlayer coupler, a thin-film lithium niobate phase shifter, a phase shifter control electrode, and a grating antenna array structure; wherein, the first end face coupler is used to couple an external red laser into the chip, the second end face coupler is used to couple an external blue laser into the chip, and the third end face coupler is used to couple an external green laser into the chip. This technical solution is used to solve the problem that the display system in the prior art is difficult to simultaneously meet the requirements of lightness, low power consumption, and high resolution.

Description

Technical Field

[0001] The present invention belongs to the field of optoelectronics and display technology, and particularly relates to an integrated optical chip for augmented reality display and a preparation method thereof. Background Art

[0002] Existing technologies mainly solve the above problems through optical waveguide technology, micro-display projection, holographic gratings and diffraction optical elements. Optical waveguide technology uses optical waveguide elements to realize the introduction and projection of optical signals, but the design of the waveguide has high requirements on the incident angle and uniformity of light. Micro-display projection realizes image projection by combining micro-displays (such as LCOS, DLP) with complex optical systems, but the systems are often large in size and difficult to use in thin and light AR devices, and the power consumption is relatively high. Technologies such as holographic gratings and diffraction optical elements can achieve efficient separation and reconstruction of optical paths, but in actual applications they are often affected by diffraction efficiency and speckle phenomena, and the display quality is not ideal.

[0003] Specifically, in augmented reality devices, traditional display systems struggle to simultaneously meet the requirements of lightweight, low power consumption, and high resolution. Existing optical systems, such as those using lens systems, prisms, or mirrors, are bulky and consume high power, limiting the portability and comfort of AR devices. Furthermore, traditional optical designs face bottlenecks in projection uniformity, clarity, and viewing angle range, making it difficult to achieve a high degree of integration with the real world. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide an integrated optical chip for augmented reality display and a preparation method thereof, so as to solve the problem that the display system in the prior art is difficult to simultaneously meet the requirements of lightness, low power consumption and high resolution.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides an integrated optical chip for augmented reality display, comprising a first end face coupler, a second end face coupler, and a third end face coupler, wherein the first end face coupler, the second end face coupler, and the third end face coupler are each sequentially provided with a 2×2 multimode interference coupler, a microring filter, three 1×2 multimode interference couplers, an interlayer coupler, a thin-film lithium niobate phase shifter, a phase shifter control electrode, and a grating antenna array structure;

[0007] Among them, the first end face coupler is used to couple external red laser into the chip, the second end face coupler is used to couple external blue laser into the chip, and the third end face coupler is used to couple external green laser into the chip. The 2×2 multimode interference coupler is used as a spectroscopic device to transmit the input laser to the microring filter and transmit the laser passing through the microring filter to the next level. The microring filter is used to filter the input laser. The three 1×2 multimode interference couplers are used as power dividers to divide the input laser into multiple beams. The interlayer coupler is used to couple the laser in the silicon nitride waveguide to the waveguide of the thin film lithium niobate. The phase shifter control electrode is the input pin of the thin film lithium niobate phase shifter, which is used to change the input voltage of the thin film lithium niobate phase shifter. The thin film lithium niobate phase shifter changes the phase in the waveguide through the electro-optical effect to achieve the purpose of phase shifting. The grating antenna array calculates the specific position of each antenna in the sparse array through an algorithm, thereby obtaining the optimal field of view angle and beam divergence angle for beam scanning.

[0008] Furthermore, the first end face coupler, the second end face coupler and the third end face coupler all adopt a Taper structure.

[0009] Furthermore, the 2×2 multimode interference coupler, the 1×2 multimode interference coupler and the microring filter are all made of silicon nitride material.

[0010] Furthermore, the lower layer of the interlayer coupler is a taper structure of silicon nitride material, and the upper layer is a taper structure of thin film lithium niobate material.

[0011] Furthermore, the phase shifter control electrode is made of gold or aluminum.

[0012] Furthermore, the grating antenna array structure includes three sub-arrays, corresponding to red, blue and green lasers respectively. The grating antennas in each sub-array can achieve large-angle scanning of light beams without grating lobes through sparse array arrangement. The three beams of light can be controlled with high precision in space. By controlling the light intensity of the input laser, the color display of any point within the field of view of the optical chip can be achieved.

[0013] Furthermore, the grating antenna array structure can be optimally estimated using a genetic algorithm.

[0014] A method for preparing an integrated optical chip for augmented reality display comprises the following steps:

[0015] (1) Take a silicon wafer and planarize the top surface of the silicon wafer through the CMP process;

[0016] (2) Depositing a layer of silicon dioxide on the silicon wafer through a CVD process, and then planarizing the upper surface through a CMP process;

[0017] (3) depositing silicon nitride on the wafer surface by LPCVD or PECVD;

[0018] (4) Preparation of silicon nitride waveguide by photoresist coating, exposure, development, and etching;

[0019] (5) A layer of silicon dioxide is then deposited on the wafer by a CVD process, and the upper surface is planarized by a CMP process;

[0020] (6) On lithium niobate substrate, high dose H + Or He + Implant, define the cleavage plane on the desired film, then bond it to the wafer via adhesive BCB or direct bonding, and finally use thermal annealing to split the substrate along the cleavage plane to complete the bonding of thin film lithium niobate on the wafer;

[0021] (7) Fabrication of a thin-film lithium niobate waveguide by photoresist coating, exposure, development, and etching;

[0022] (8) Depositing a layer of silicon dioxide on the silicon wafer by CVD process, and then planarizing the upper surface by CMP process;

[0023] (9) The window opening required for metal layer deposition is completed through the processes of photoresist coating, exposure, development, and etching;

[0024] (10) The metal electrodes are prepared by electroplating or sputtering.

[0025] The beneficial effects of the present invention are:

[0026] (1) The optical integrated chip in this technical solution has efficient and precise optical imaging and projection functions to enhance the display effect of AR devices and meet the requirements of higher resolution, wide viewing angle, miniaturization and low power consumption;

[0027] (2) The chip in this technical solution can greatly improve the integration of augmented reality display devices, making the integration more planar and the structure simpler.

[0028] Other advantages, objectives and features of the present invention will be described in the following description and will be apparent to those skilled in the art to some extent, or those skilled in the art can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to make the purpose, technical solutions and beneficial effects of the present invention more clear, the present invention provides the following drawings for illustration:

[0030] Figure 1 Schematic diagram of the architecture of the integrated optical chip of the present invention;

[0031] Figure 2 is a longitudinal schematic diagram of an interlayer coupler according to the present invention;

[0032] Figure 3 Schematic diagram of the longitudinal structure of the integrated optical chip of the present invention;

[0033] Figure 4 Schematic diagram of the preparation process of the integrated optical chip of the present invention.

[0034] The following are marked in the accompanying drawings:

[0035] 1. First end-face coupler; 2. 2×2 multimode interference coupler; 3. Microring filter; 4. 1×2 multimode interference coupler; 5. Interlayer coupler; 6. Thin-film lithium niobate phase shifter; 7. Grating antenna array structure; 8. Phase shifter control electrode; 9. Second end-face coupler; 10. Third end-face coupler. DETAILED DESCRIPTION

[0036] like Figures 1 to 4 As shown, the present invention provides an integrated optical chip for augmented reality display, and the chip architecture of the integrated optical chip is as follows Figure 1 As shown, it specifically includes a first end face coupler 1, a second end face coupler 9 and a third end face coupler 10. After the first end face coupler 1, the second end face coupler 9 and the third end face coupler 10, a 2×2 multimode interference coupler 2, a microring filter 3, a 1×2 multimode interference coupler 4, an interlayer coupler 5, a thin film lithium niobate phase shifter 6, a phase shifter control electrode 8 and a grating antenna array structure 7 are sequentially provided along the optical path;

[0037] Among them, the first end face coupler 1: couples the external red laser into the chip; the second end face coupler 9: couples the external blue laser into the chip; the third end face coupler 10: couples the external green laser into the chip; 2×2MMI structure (multi-mode interference coupler): a spectrometer, after the light passes through the filter structure, it returns to the next level; micro-ring filter 3: filters the input laser through resonance to achieve a narrow-band beam, which can make the wavelength of the subsequent laser cleaner and more concentrated, which is conducive to achieving high-definition display; 1×2MMI (multi-mode interference coupler): as a power divider, the light is evenly divided into 2 beams. In this specific embodiment, three 1×2MMIs are set, and finally the light is evenly divided into multiple beams ( Figure 1 4 bundles are shown), and the specific layout is as follows Figure 1As shown; interlayer coupler 5 (Taper structure): couples the laser in the silicon nitride waveguide to the waveguide of thin film lithium niobate through the interlayer coupler 5; electrode of the phase shifter: the input pin of the phase shifter control voltage, and applying voltage can change the phase of the laser in the waveguide; thin film lithium niobate phase shifter 6: ridge waveguide structure, which can change the phase in the waveguide through the electro-optical effect of lithium niobate, thereby achieving the effect of phase shifting; grating antenna array structure 7: an array composed of grating antennas, and the specific position of each antenna in the sparse array can be calculated by an algorithm (such as a genetic algorithm), so as to achieve the optimal field of view angle and beam divergence angle of the light beam scanning. By changing the phase in each antenna unit, the coherence intensity between the antennas can be controlled in the far field, thereby realizing the scanning of the light beam. In this scheme, there are 3 antenna arrays, corresponding to red light, blue light, and green light respectively. The 3 laser beams can be controlled to scan at any point in space and within the field of view angle, and the display purpose is achieved through rapid scanning.

[0038] In one practicable embodiment, the first end face coupler 1, the second end face coupler 9 and the third end face coupler 10 all adopt a Taper structure. In the field of optoelectronic integration, the Taper structure can be used to achieve transitions between waveguides of different widths, and can also convert polarization modes through cross-sectional transitions. For example, the Taper structure can be used in a grating coupler or an end face coupler to achieve mode conversion and energy coupling.

[0039] In one practicable manner, the 2×2 multimode interference coupler 2 , the 1×2 multimode interference coupler 4 , and the microring filter 3 are all made of silicon nitride material.

[0040] In one practicable manner, Figure 2 As shown, the lower layer of the interlayer coupler 5 is a taper structure of silicon nitride material, and the upper layer is a taper structure of thin film lithium niobate material.

[0041] The interlayer coupler 5 has a tapered structure, meaning the waveguide tapers gradually. Through mode and phase matching, the laser light in the silicon nitride waveguide is coupled to the thin-film lithium niobate waveguide. While phase shifting in silicon nitride waveguides consumes considerable power and is difficult, thin-film lithium niobate utilizes the electro-optic effect, offering high phase shift efficiency and low power consumption. Because visible light is not within the silicon's transparent window, the electro-optic effect of silicon can be eliminated. Thin-film lithium niobate is currently the best choice.

[0042] In an practicable manner, the phase shifter control electrode 8 is made of gold or aluminum, preferably aluminum, which has a relatively low cost.

[0043] In one feasible embodiment, the grating antenna array structure 7 includes three sub-arrays, corresponding to red, blue, and green lasers respectively. The grating antennas in each sub-array can realize large-angle scanning of light beams without grating lobes through sparse array arrangement. The three beams of light can be controlled with high precision in space. By controlling the intensity of the input laser, the color display of any point within the field of view of the optical chip can be achieved.

[0044] This design can reduce the coupling crosstalk between array elements. In this structure, the three beams of light can be controlled with high precision in space. By controlling the light intensity of the input laser, the color display of any point within the field of view of the optical chip can be achieved. This means that by precisely controlling the light intensity of each sub-array, display effects of different colors can be created within the field of view, thereby achieving the generation of color images. The application of this technology can greatly improve the performance of display technology, especially in applications that require precise color control and large-angle scanning, such as augmented reality (AR), virtual reality (VR), and optical communications. In summary, the grating antenna array structure 7, through its unique design, can achieve precise control of the red, blue, and green lasers, and thus achieve color display at any point within the field of view of the optical chip, which is of great significance for improving the performance of optical display and communication technologies.

[0045] In one practicable manner, the grating antenna array structure may be optimally estimated using a genetic algorithm.

[0046] A method for preparing an integrated optical chip for augmented reality display comprises the following steps:

[0047] (1) Take a silicon wafer and flatten the top surface of the silicon wafer through the CMP process;

[0048] (2) A layer of silicon dioxide is then deposited on the silicon wafer through a CVD process, and the upper surface is planarized through a CMP process;

[0049] (3) Silicon nitride is then deposited on the wafer surface by LPCVD or PECVD (LPCVD is generally selected for lower waveguide loss);

[0050] (4) Preparation of silicon nitride waveguide by photoresist coating, exposure, development, etching and other processes;

[0051] (5) Then a layer of silicon dioxide is deposited on the wafer by a CVD process, and then the upper surface is flattened by a CMP process;

[0052] (6) On a high-quality lithium niobate substrate, a high-dose H + Or (He +) ion implantation, first defining the cleavage plane at the desired film thickness, then bonding to the wafer via adhesive BCB or direct bonding, and then using thermal annealing to split the substrate along the cleavage plane to complete the bonding of thin film lithium niobate on the wafer;

[0053] (7) Then, the thin film lithium niobate layer waveguide is prepared by processes such as photoresist coating, exposure, development, and etching;

[0054] (8) Then, a layer of silicon dioxide is deposited on the silicon wafer by a CVD process, and then the upper surface is flattened by a CMP process;

[0055] (9) Then, the window opening required for metal layer deposition is completed through processes such as photoresist coating, exposure, development, and etching;

[0056] (10) Finally, electroplating or sputtering is used or metal electrodes are prepared.

[0057] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. An integrated optical chip for augmented reality display, characterized in that: The integrated optical chip comprises a first end face coupler (1), a second end face coupler (9) and a third end face coupler (10), wherein the first end face coupler (1), the second end face coupler (9) and the third end face coupler (10) are sequentially provided with a 2×2 multimode interference coupler (2), a microring filter (3), three 1×2 multimode interference couplers (4), an interlayer coupler (5), a thin film lithium niobate phase shifter (6), a phase shifter control electrode (8) and a grating antenna array structure (7); The first end face coupler (1) is used to couple an external red laser into the chip, the second end face coupler (9) is used to couple an external blue laser into the chip, and the third end face coupler (10) is used to couple an external green laser into the chip; the 2×2 multimode interference coupler (2) is used as a light splitting device to transmit the input laser to the microring filter (3) and transmit the laser passing through the microring filter (3) to the next level; the microring filter (3) is used to filter the input laser; the three 1×2 multimode interference couplers (4 ) is used as a power divider to divide the input laser into multiple beams; the interlayer coupler (5) is used to couple the laser in the silicon nitride waveguide to the waveguide of the thin film lithium niobate; the phase shifter control electrode (8) is the input pin of the thin film lithium niobate phase shifter (6), which is used to change the input voltage of the thin film lithium niobate phase shifter (6); the thin film lithium niobate phase shifter (6) changes the phase in the waveguide through the electro-optical effect to achieve the purpose of phase shifting, and the grating antenna array structure (7) calculates the specific position of each antenna in the sparse array through an algorithm, thereby obtaining the optimal field of view angle and beam divergence angle of the light beam scanning.

2. The integrated optical chip for augmented reality display according to claim 1, characterized in that: The first end face coupler (1), the second end face coupler (9) and the third end face coupler (10) all adopt a Taper structure.

3. The integrated optical chip for augmented reality display according to claim 1, characterized in that: The 2×2 multimode interference coupler (2), the 1×2 multimode interference coupler (4) and the microring filter (3) are all made of silicon nitride material.

4. The integrated optical chip for augmented reality display according to claim 1, characterized in that: The lower layer of the interlayer coupler (5) is a taper structure made of silicon nitride material, and the upper layer is a taper structure made of thin film lithium niobate material.

5. The integrated optical chip for augmented reality display according to claim 1, characterized in that: The phase shifter control electrode (8) is made of gold or aluminum.

6. The integrated optical chip for augmented reality display according to claim 1, characterized in that: The grating antenna array structure (7) includes three sub-arrays, corresponding to red, blue and green lasers respectively. The grating antennas in each sub-array can realize large-angle scanning of light beams without grating lobes through sparse array arrangement. The three beams of light can be controlled with high precision in space. By controlling the light intensity of the input laser, the color display of any point within the field of view of the optical chip can be realized.

7. The integrated optical chip for augmented reality display according to claim 1, characterized in that: The grating antenna array structure (7) can be optimally estimated using a genetic algorithm.

8. The method for preparing an integrated optical chip for augmented reality display according to any one of claims 1 to 7, characterized in that: The steps include: (1) Take a silicon wafer and planarize the top surface of the silicon wafer through the CMP process; (2) Depositing a layer of silicon dioxide on the silicon wafer through a CVD process, and then flattening the upper surface through a CMP process; (3) depositing silicon nitride on the wafer surface by LPCVD or PECVD; (4) Preparation of silicon nitride waveguide by photoresist coating, exposure, development, and etching; (5) A layer of silicon dioxide is then deposited on the wafer by a CVD process, and the upper surface is planarized by a CMP process; (6) On lithium niobate substrate, high dose H + Or He + Implant, define the cleavage plane on the desired film, then bond it to the wafer via adhesive BCB or direct bonding, and finally use thermal annealing to split the substrate along the cleavage plane to complete the bonding of thin film lithium niobate on the wafer; (7) The thin film lithium niobate waveguide is prepared by applying photoresist, exposing, developing and etching; (8) Depositing a layer of silicon dioxide on the silicon wafer by CVD process, and then planarizing the upper surface by CMP process; (9) The window opening required for metal layer deposition is completed through the processes of photoresist coating, exposure, development, and etching; (10) The metal electrodes are prepared by electroplating or sputtering.

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