Optical waveguide lens

Abstract

The utility model relates to an optical waveguide lens, which comprises at least two glass substrates, an optical waveguide sheet arranged between two adjacent glass substrates, a grating structure arranged on at least one surface of the optical waveguide sheet, and a filling layer embedded in a grating gap of the grating structure, the optical waveguide sheet and the grating structure are made of silicon carbide, the filling layer is made of a low-refractive-index optical coating material, the outer side surfaces of the filling layer and the grating structure are approximately located on the same plane, and / or the filling layer covers the outer side surface of the grating structure. According to the optical waveguide lens, the low-refractive-index glass and the silicon carbide optical waveguide sheet are arranged in a staggered manner, and the air gap is filled with the low-refractive-index optical coating material, so that the obtained optical waveguide lens has the advantages of being light, thin, high in mechanical strength and good in stability while ensuring full-color imaging.

Description

Technical Field

[0001] The utility model relates to the technical field of optical elements, in particular to an optical waveguide lens. Background Art

[0002] Augmented reality technology, or AR technology, is to provide users with virtual information through images, videos, 3D models and other technologies while displaying real scenes, so as to achieve the ingenious integration of virtual information and the real world. It is the next detonation point of information technology, and augmented reality glasses may replace mobile phones as the next generation of collaborative computing platform. Among many AR optical display solutions, the relief grating waveguide uses a relief grating (SRG) instead of the traditional refractive reflective optical device (ROE) as the coupling, coupling and pupil expansion device in the optical waveguide solution. Due to its excellent performance, it is considered to be the most promising solution for consumer-grade AR glasses products. Existing optical waveguide lenses mainly use high-refractive index glass as the optical waveguide sheet and stack cover glass to protect the grating structure to reduce the impact of external factors on the grating structure, thereby extending the service life of the optical waveguide lens. However, this method of stacking multiple layers of high-refractive index glass and attaching an optical-mechanical circuit makes AR glasses bulky, affecting the user's experience of long-term wear. Therefore, in order to reduce the size and weight of AR glasses, the current main method is to reduce the thickness of the optical waveguide lens or change the cover glass to resin material to achieve the purpose of weight reduction and thinning.

[0003] At present, the optical waveguide lens solution of cover glass + optical waveguide structure + cover glass lens is to combine multiple layers of high refractive index glass sheets together by overlapping. The thickness of the high refractive index glass is about 0.5~1.0mm. There is an air gap of about 50~100μmm between the cover glass and the optical waveguide structure to ensure the full emission conditions required for light propagation. This structure will result in a thicker overall lens and a poor wearing experience. The thickness of the overall lens can be reduced by reducing the thickness of the cover glass or waveguide layer, but ultra-thinness will lead to a decrease in the mechanical strength of the lens, posing certain safety hazards. On this basis, the applicant recently proposed a solution of coating a low-refractive index resin material on the upper and lower surfaces of a silicon carbide optical waveguide structure, which can utilize the larger refractive index of silicon carbide to achieve a single-chip full-color function, thereby replacing the cover glass. This lens structure is of great significance for reducing the weight of the waveguide. In addition, coating the upper and lower surfaces of the silicon carbide waveguide with a low-refractive-index resin material can protect the waveguide without destroying the total reflection condition. However, since the resin material is an organic substance, it is sensitive to physical conditions such as light, temperature, and humidity. Long-term wearing will lead to problems such as reduced stability and discoloration of the lens surface. Utility Model Content

[0004] The problem to be solved by the utility model is to provide an optical waveguide lens in view of the above-mentioned deficiencies existing in the prior art. The optical waveguide lens solution of low refractive index glass + silicon carbide optical waveguide sheet + low refractive index glass and filling the air gap with low refractive index optical coating material solves the problems of low mechanical strength of the lens caused by the existing thinning cover glass method and poor stability of the lens caused by replacing the cover glass with resin material. While ensuring full-color imaging, it has the advantages of being light and thin.

[0005] The above utility model object of the utility model is achieved through the following technical solutions:

[0006] A light waveguide lens comprises at least two glass substrates, a light waveguide sheet arranged between two adjacent glass substrates, a grating structure arranged on at least one surface of the light waveguide sheet, and a coating layer embedded in the grating gap of the grating structure, wherein the glass substrate is composed of low-refractive index glass, the light waveguide sheet and the grating structure are composed of silicon carbide, the coating layer is composed of a low-refractive index optical coating material, and the coating layer and the outer surface of the grating structure are approximately on the same plane, and / or the coating layer covers the outer surface of the grating structure.

[0007] By adopting the above technical solution, the optical waveguide sheet is preferably arranged between two adjacent glass substrates in a bonding manner, and low-refractive index glass is used to replace the original low-refractive index resin material, which not only thins the glass substrate to 50-100 μm without affecting the mechanical strength of the lens, but also directly eliminates the problems of poor stability and yellowing of the original resin material; at the same time, filling the grating gap of the grating structure with a low-refractive index optical coating material can further reduce rainbow patterns, and the surface of the grating structure after filling the coating layer is smooth, which is beneficial to improving the stability of the interlayer bonding; by adopting the above structure, by staggeredly arranging low-refractive index glass and silicon carbide optical waveguide sheets, and filling the air gap with a low-refractive index optical coating material, the optical waveguide lens obtained thereby has the advantages of being light, thin, high mechanical strength and good stability while ensuring full-color imaging.

[0008] The utility model is further configured as follows: the refractive index of the glass substrate is 1.40-1.60.

[0009] By adopting the above technical solution, the advantages of the lens being light and thin can be ensured.

[0010] The utility model is further configured as follows: the thickness of the glass substrate is 50-100 μm.

[0011] By adopting the above technical solution, the advantages of the lens being light and thin can be ensured.

[0012] The utility model is further configured as follows: the low refractive index glass of the glass substrate is optical glass or quartz sheet.

[0013] By adopting the above technical solution, the optical glass or quartz sheet is transparent in the visible light band, and in order to improve the transmittance and other optical properties, the optical glass or quartz sheet can be a sheet structure with an attached functional layer, for example, an anti-reflection layer is evaporated on the surface of the low refractive index glass without limitation.

[0014] The utility model is further configured as follows: the refractive index of the optical waveguide plate and the grating structure is 2.60-2.70.

[0015] By adopting the above technical solution, the advantages of the lens being light and thin and having high mechanical strength can be ensured.

[0016] The utility model is further configured as follows: the thickness of the optical waveguide sheet and the grating structure is 0.3-1.0 mm.

[0017] By adopting the above technical solution, the advantages of the lens being light and thin and having high mechanical strength can be ensured.

[0018] The utility model is further configured as follows: the surface of the optical waveguide sheet is arranged on the glass substrate by direct bonding, warm pressure bonding, and / or optical bonding.

[0019] By adopting the above technical solution, the advantages of the lens being light and thin, having high mechanical strength and good stability can be ensured.

[0020] The utility model is further configured as follows: the grating structure is a sub-wavelength grating structure composed of a plurality of straight-tooth gratings, oblique-tooth gratings, and / or blazed gratings and arranged in a one-dimensional or two-dimensional array.

[0021] By adopting the above technical solution, the advantages of the lens being light and thin, having high mechanical strength and good stability can be ensured.

[0022] The utility model is further configured that: the refractive index of the coating layer is below 2.00.

[0023] The adoption of the above technical solution is conducive to further reducing rainbow lines and improving bonding stability.

[0024] The utility model is further configured as follows: the coating layer is composed of silicon oxide or silicon nitride.

[0025] The adoption of the above technical solution is conducive to further reducing rainbow lines, while improving bonding stability and extending service life.

[0026] In summary, the beneficial technical effect of the utility model is as follows: by staggeredly arranging low-refractive-index glass and silicon carbide optical waveguide sheets and filling the air gap with low-refractive-index optical coating materials, the optical waveguide lens thus obtained has the advantages of being light, thin, having high mechanical strength and good stability while ensuring full-color imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic structural diagram of the optical waveguide lens of Example 1 of the utility model.

[0028] Figure 2 It is a schematic structural diagram of the optical waveguide lens of Example 4 of the utility model.

[0029] Figure 3 It is a schematic structural diagram of the optical waveguide lens of Example 7 of the utility model.

[0030] In the figure, 1. glass substrate; 2. optical waveguide; 3. grating structure; 4. filling layer. DETAILED DESCRIPTION

[0031] In order to make the technical means, creative features, objectives and functions achieved by the present invention clearer and easier to understand, the present invention is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0032] Example 1: Reference Figure 1 , is a light waveguide lens disclosed by the utility model, comprising a pair of glass substrates, a light waveguide sheet disposed between the pair of glass substrates, a grating structure disposed on one surface of the light waveguide sheet, and a filling layer embedded in the grating gap of the grating structure. By staggeredly arranging low-refractive index glass and silicon carbide light waveguide sheets, and filling the air gap with low-refractive index optical coating materials, the light waveguide lens obtained thereby has the advantages of being light, thin, high in mechanical strength, and good in stability while ensuring full-color imaging.

[0033] The glass substrate is composed of low-refractive index glass with a refractive index of 1.40 and a thickness of 50μm. The low-refractive index glass of the glass substrate is optical glass, and the low-refractive index glass is transparent in the visible light band. Using low-refractive index glass to replace the original low-refractive index resin material not only reduces the glass substrate to 50μm without affecting the mechanical strength of the lens, but also directly eliminates the problems of poor stability and yellowing of the original resin material.

[0034] The optical waveguide and grating structure are composed of a silicon carbide wafer with a refractive index of 2.60 and a thickness of 0.3 mm. The surface of the optical waveguide is set on the glass substrate by high-temperature bonding; the grating structure is a sub-wavelength grating structure composed of multiple straight tooth gratings and arranged in a one-dimensional array. After the high-temperature bonding of the optical waveguide and the underlying glass substrate is completed, a grating structure is prepared on the surface of the optical waveguide, including coupling-in, turning and coupling-out areas, so that the light from the projection optical machine continues to expand the pupil after passing through the grating structure and finally forms an image in front of the human eye, forming a virtual image.

[0035] The filling layer is composed of a low-refractive-index optical coating material with a refractive index below 2.00, and the low-refractive-index optical coating material of the filling layer is silicon oxide; the filling layer and the outer surface of the grating structure are approximately on the same plane. Filling the grating gap of the grating structure with a low-refractive-index optical coating material can further reduce rainbow lines, and at the same time, the surface of the grating structure after filling the coating layer is smooth, which is conducive to improving the stability of the interlayer bonding.

[0036] The implementation principle of this embodiment is:

[0037] S1 substrate preparation: RCA cleaning method is used to clean high refractive index glass and silicon carbide wafers respectively, and O2 plasma is used to pre-treat the two bonded surfaces to improve the hydrophilicity of the surface, thereby obtaining a glass substrate and an optical waveguide.

[0038] S2 high temperature bonding, the glass substrate and the optical waveguide sheet are bonded in a manner that the bonding surfaces are opposite to each other, and are directly bonded from the center to the edge. High temperature annealing is performed to further improve the bonding strength to obtain a composite substrate;

[0039] S3 grating fabrication uses electron beam lithography (EBL), photolithography, or nanoimprinting techniques to pattern the grating on the surface of the optical waveguide on the composite substrate, and then uses reactive ion etching (RIE), plasma etching (ICP), reactive ion beam etching (RIBE), etc. to transfer the patterned grating pattern to the optical waveguide to obtain a grating structure;

[0040] S4 coating, filling silicon oxide on the surface of the optical waveguide by coating to obtain a coating layer;

[0041] S5 high temperature bonding, repeat S2, and bond another glass substrate to the surface of the optical waveguide plate with the grating structure.

[0042] Embodiment 2 is an optical waveguide lens disclosed in the present invention. The difference from Embodiment 1 is that the glass substrate is composed of a low-refractive-index glass with a refractive index of 1.40-1.60 and a thickness of 50-100 μm.

[0043] Embodiment 3 is an optical waveguide lens disclosed in the present invention. The difference from Embodiment 1 is that the glass substrate is composed of a low-refractive-index glass with a refractive index of 1.40-1.60 and a thickness of 50-100 μm.

[0044] Example 4: Reference Figure 2 , is an optical waveguide lens disclosed in the utility model, which is different from Example 1 in that the low-refractive-index glass of the glass substrate is a quartz sheet, and in order to improve the transmittance and other optical properties, the low-refractive-index glass can be a sheet structure with a functional layer attached, and in this embodiment, an anti-reflection layer is evaporated on the surface of the quartz sheet.

[0045] Embodiment 5 is an optical waveguide lens disclosed in the present invention. The difference from Embodiment 1 is that the optical waveguide sheet and the grating structure are composed of a silicon carbide wafer with a refractive index of 2.70 and a thickness of 1.0 mm.

[0046] Embodiment 6 is an optical waveguide lens disclosed by the present utility model, which is different from Embodiment 1 in that the low refractive index optical coating material of the filling layer is silicon nitride.

[0047] Example 7: Reference Figure 3 , is an optical waveguide lens disclosed in the utility model, which is different from Example 1 in that the filling layer covers the outer surface of the grating structure, and the surface of the filling layer is arranged on the glass substrate by high-temperature bonding.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the utility model, which should be included in the scope of the claims of the utility model.

Claims

1. An optical waveguide lens, characterized in that: The invention comprises at least two glass substrates, an optical waveguide sheet arranged between two adjacent glass substrates, a grating structure arranged on at least one surface of the optical waveguide sheet, and a coating layer embedded in the grating gap of the grating structure, wherein the glass substrate is composed of low-refractive index glass, the optical waveguide sheet and the grating structure are composed of silicon carbide, the coating layer is composed of a low-refractive index optical coating material, and the coating layer and the outer surface of the grating structure are approximately on the same plane, and / or the coating layer covers the outer surface of the grating structure.

2. The optical waveguide lens according to claim 1, characterized in that: The refractive index of the glass substrate is 1.40-1.

60.

3. The optical waveguide lens according to claim 2, characterized in that: The thickness of the glass substrate is 50-100 μm.

4. The optical waveguide lens according to claim 3, characterized in that: The low refractive index glass of the glass substrate is optical glass or quartz plate.

5. The optical waveguide lens according to claim 1, characterized in that: The refractive index of the optical waveguide plate and the grating structure is 2.60-2.

70.

6. The optical waveguide lens according to claim 5, characterized in that: The thickness of the optical waveguide plate and the grating structure is 0.3-1.0 mm.

7. The optical waveguide lens according to claim 1, characterized in that: The surface of the optical waveguide sheet is arranged on the glass substrate by direct bonding, warm pressure bonding, and / or optical bonding.

8. The optical waveguide lens according to claim 1, characterized in that: The grating structure is a sub-wavelength grating structure composed of a plurality of straight-tooth gratings, slanted-tooth gratings, and / or blazed gratings and arranged in a one-dimensional or two-dimensional array.

9. The optical waveguide lens according to claim 1, characterized in that: The refractive index of the coating layer is below 2.

00.

10. The optical waveguide lens according to claim 9, characterized in that: The coating layer is composed of silicon oxide or silicon nitride.

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