Integrated optical chip for augmented reality display and preparation method thereof

Abstract

The invention discloses an integrated optical chip for augmented reality display and a preparation method thereof, and belongs to the technical field of optoelectronics and display. The integrated optical chip comprises a first end face coupler, a second end face coupler and a third end face coupler. 2 * 2 multi-mode interference couplers, micro-ring filters, 1 * 2 multi-mode interference couplers, interlayer couplers, film lithium niobate phase shifters, phase shifter control electrodes and grating antenna array structures are sequentially arranged behind the first end face coupler, the second end face coupler and the third end face coupler; wherein the first end face coupler is used for coupling external red laser into the chip, the second end face coupler is used for coupling external blue laser into the chip, and the third end face coupler is used for coupling external green laser into the chip. The technical scheme is used for solving the problem that a display system in the prior art is difficult to meet the requirements of lightness, thinness, low power consumption and high resolution at the same time.

Description

Technical Field

[0001] The present invention belongs to the field of optoelectronics and display technology, and in particular 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, microdisplay projection, holographic gratings and diffractive 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. Microdisplay projection realizes image projection by cooperating with a microdisplay (such as LCOS, DLP) and a complex optical system, but the system is often large in size, difficult to use in thin and light AR devices, and the power consumption is relatively high. Technologies such as holographic gratings and diffractive optical elements can achieve efficient separation and reconstruction of optical paths, but in practical applications they are often affected by diffraction efficiency and speckle phenomena, and the display quality is not ideal.

[0003] That is, in augmented reality devices, traditional display systems are difficult to simultaneously meet the requirements of thinness, low power consumption, and high resolution. Existing optical systems, such as lens groups, prisms, or reflector combinations, are bulky and consume high power, limiting the portability and wearing comfort of AR devices. In addition, traditional optical designs also have bottlenecks in projection uniformity, clarity, and viewing angle range, making it difficult to achieve a high degree of integration with the real environment. Summary of the invention

[0004] In view of this, an object of the present invention is to provide an integrated optical chip for augmented reality display and a method for preparing the same, 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 discloses an integrated optical chip for augmented reality display, the integrated optical chip 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 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 the external red laser into the chip, the second end face coupler is used to couple the external blue laser into the chip, and the third end face coupler is used to couple the 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 of the 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 antenna 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 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 upper surface of the silicon wafer through the CMP process;

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

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

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

[0019] (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;

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

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

[0022] (8) depositing a layer of silicon dioxide on the silicon wafer by a CVD process, and then planarizing the upper surface by a 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 electrode is 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 accurate optical imaging and projection functions to improve 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 may be taught from the practice of the present invention. The objectives and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0030] Figure 1 It is a schematic diagram of the architecture of the integrated optical chip of the present invention;

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

[0032] Figure 3 It is a schematic diagram of the longitudinal structure of the integrated optical chip of the present invention;

[0033] Figure 4 It is a 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 Figure 1 to Figure 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, and 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 arranged along the optical path after the first end face coupler 1, the second end face coupler 9 and the third end face coupler 10;

[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 spectroscopic device, after the light passes through the filter structure, it returns to the next level; micro-ring filter 3: through resonance, the input laser is filtered to achieve a narrow-band beam, which can make the wavelength of the subsequent laser cleaner and more concentrated, which is conducive to the realization of high-definition display; 1×2MMI (multi-mode interference coupler): as a power divider, the light is evenly divided into 2 beams. In this specific implementation, 3 1×2MMIs are set to finally evenly divide the light 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 the thin film lithium niobate through the interlayer coupler 5; electrode of the phase shifter: the input pin of the phase shifter control voltage, and the applied 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 control between the antennas can be achieved 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, respectively, and the display purpose is achieved through rapid scanning.

[0038] In one practicable manner, 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, if 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 Taper structure, that is, the waveguide gradually narrows, and the laser in the silicon nitride waveguide is coupled to the waveguide of the thin-film lithium niobate through mode and phase matching. Because the power consumption and difficulty of phase shifting in silicon nitride waveguides are relatively large, thin-film lithium niobate has an electro-optical effect, high phase shift efficiency and low power consumption. Because visible light is not within the transparent window of silicon, the electro-optical effect of silicon materials can also be avoided. Thin-film lithium niobate is currently the best choice.

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

[0043] In one feasible manner, 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 a 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, 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 an 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 planarize the upper surface of the silicon wafer through the CMP process;

[0048] (2) 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;

[0049] (3) Then, silicon nitride is deposited on the surface of the wafer by LPCVD or PECVD (LPCVD is generally selected because of lower waveguide loss);

[0050] (4) Preparation of silicon nitride layer waveguide is completed through processes such as photoresist coating, exposure, development, and etching;

[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 +) ion implantation, first define the cleavage plane at the desired film thickness, then bond to the wafer by adhesive BCB or direct bonding, and then use 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 planarized 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 to prepare metal electrodes.

[0057] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. 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 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 micro-ring 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 material of the phase shifter control electrode (8) is 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 light beams 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. A 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 upper surface of the silicon wafer through the CMP process; (2) Depositing a layer of silicon dioxide on the silicon wafer by CVD process, and then planarizing the upper surface by CMP process; (3) depositing silicon nitride on the surface of the wafer by LPCVD or PECVD; (4) Preparation of silicon nitride layer waveguide is completed by photoresist coating, exposure, development, and etching processes; (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; (6) On a lithium niobate substrate, a high dose of H + Or He + Implant, define the cleavage plane on the desired film, then bond to the wafer by adhesive BCB or direct bonding, and finally cleave the substrate along the cleavage plane by thermal annealing to complete the bonding of thin film lithium niobate on the wafer; (7) Preparation of thin-film lithium niobate waveguides by photoresist coating, exposure, development and etching; (8) depositing a layer of silicon dioxide on the silicon wafer by a CVD process, and then planarizing the upper surface by a 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 electrode is prepared by electroplating or sputtering.

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