A highly uniform optical waveguide structure

Abstract

This invention relates to a highly uniform optical waveguide structure, comprising a waveguide substrate, an imprinted adhesive layer disposed on the waveguide substrate, an integrally formed imprinted grating structure disposed on the imprinted adhesive layer, and a high-refractive-index dielectric layer disposed on the imprinted grating structure. The waveguide substrate is sequentially divided into a coupling-in region, a transition region, and a coupling-out region along the beam propagation path. The grating teeth of the imprinted grating structure located in the transition region and / or the coupling-out region are inserted into the high-refractive-index dielectric layer, and the refractive index of the high-refractive-index dielectric layer exceeds the refractive index of the imprinted grating structure. This invention solves the problem of low diffraction efficiency caused by the excessively low refractive index of the imprinted adhesive in optical waveguide structures fabricated by nanoimprinting, and has the advantages of improving the optical efficiency and uniformity of the optical waveguide structure.

Description

Technical Field

[0001] This utility model relates to the technical field of optical components, and in particular to a highly uniform optical waveguide structure. Background Technology

[0002] With the development of AI, AR, as the best carrier of AI, is highly anticipated, and diffractive waveguides have gradually replaced arrayed waveguides and holographic waveguides as the mainstream approach for AR. Currently, the most common approach is to mass-produce diffractive waveguide modules using nanoimprinting. However, because the refractive index of the grating made of imprinted adhesive is between 1.5 and 1.9, the diffraction efficiency in the transition and coupling regions is very low, which severely inhibits the modulation of optical efficiency and uniformity.

[0003] Chinese Patent No. CN222748732U discloses a diffractive waveguide, comprising: a substrate; an etched grating region disposed on the substrate; and an imprinted layer, wherein the imprinted layer and the etched grating region are located on the same side surface of the substrate, and the etched grating region is filled and covered by the imprinted layer. The side surface of the imprinted layer away from the substrate has an embedded imprinted grating region, and the angle between the grating of the etched grating region and the substrate is different from the angle between the grating of the embedded imprinted grating region and the substrate.

[0004] The existing technical solutions mentioned above have the following drawbacks: In order to solve the problem of low efficiency of nanoimprinting in the transition and coupling regions, the above-mentioned diffraction waveguides improve diffraction efficiency by using nanoimprinting in the coupling region and combining etched gratings and imprinted layers in the coupling region. On the one hand, this solution has limited improvement on optical efficiency and uniformity, and on the other hand, it greatly increases the difficulty of design and processing, which is not conducive to large-scale manufacturing. Utility Model Content

[0005] The present invention aims to address the aforementioned shortcomings in the existing technology by providing a highly uniform optical waveguide structure. It solves the problem of low diffraction efficiency caused by the low refractive index of the imprinted adhesive in optical waveguide structures fabricated by nanoimprinting, and has the advantages of improving the optical efficiency and uniformity of the optical waveguide structure.

[0006] The above-mentioned objective of this utility model is achieved through the following technical solution:

[0007] A highly uniform optical waveguide structure includes a waveguide substrate, an imprinted adhesive layer disposed on the waveguide substrate, an integrally formed imprinted grating structure disposed on the imprinted adhesive layer, and a high refractive index dielectric layer disposed on the imprinted grating structure. The waveguide substrate is sequentially divided into a coupling-in region, a transition region, and a coupling-out region along the beam transmission path. The grating teeth of the imprinted grating structure located in the transition region and / or the coupling-out region are inserted into the high refractive index dielectric layer, and the refractive index of the high refractive index dielectric layer exceeds the refractive index of the imprinted grating structure.

[0008] The present invention is further configured such that the waveguide substrate is composed of optical glass, optical resin, or SiC.

[0009] The present invention is further configured such that the thickness of the waveguide substrate is 0.3~1.5mm.

[0010] The present invention is further configured such that the imprinting adhesive layer and the imprinting grating structure are composed of imprinting adhesive with a refractive index of 1.5 to 1.9.

[0011] The present invention is further configured such that the high refractive index medium layer is composed of optical glass, optical resin, Si3N4, TiO2, SiC, SiO2, MgF2, perfluoroalkene, polycarbonate, GaP, or GaS.

[0012] The present invention is further configured such that: in the coupling region, the thickness of the imprinted adhesive layer is 5~500nm, the grating tooth height of the imprinted grating structure is 10~500nm, the period is 250~500nm, the duty cycle is 20~100%, the blaze angle is 0~90°, and the anti-blaze angle is 0~90°.

[0013] The present invention is further configured such that: in the transition zone, the thickness of the imprinted adhesive layer is 5~500nm, the height of the grating teeth of the imprinted grating structure is 10~500nm, the period is 250~500nm, the duty cycle is 20~100%, the blaze angle is 0~90°, and the anti-blaze angle is 0~90°.

[0014] The present invention is further configured such that the thickness of the high refractive index dielectric layer in the transition region is 50~650nm.

[0015] The present invention is further configured such that: in the coupling region, the thickness of the imprinted adhesive layer is 5~500nm, the height of the grating teeth of the imprinted grating structure is 10~500nm, the period is 250~500nm, the duty cycle is 20~100%, the blaze angle is 0~90°, and the anti-blaze angle is 0~90°.

[0016] The present invention is further configured such that the thickness of the high refractive index dielectric layer in the coupling region is 50~650nm.

[0017] In summary, the beneficial technical effects of this utility model are as follows:

[0018] 1. This utility model, through the structural design of "imprinted adhesive layer - imprinted grating structure - high refractive index dielectric layer", significantly modulates the diffraction efficiency of red and blue light in the transition region and coupling region, FOV-1 and FOV-5. It solves the problem of low diffraction efficiency caused by the low refractive index of the imprinted adhesive in the optical waveguide structure fabricated by nanoimprinting. It also breaks through the constraint of the consistency of the diffraction efficiency variation law of red and blue light with parameter changes under the same FOV. All of these are beneficial to the uniform modulation and light efficiency improvement of full-color waveguide.

[0019] 2. This invention also achieves precise control over the diffraction efficiency of red and blue light at different field angles by setting imprinted adhesive layers and high-refractive-index dielectric layers of different thicknesses in the transition and coupling regions, as well as an imprinted grating structure with specific parameters. This design not only improves diffraction efficiency but also enhances the stability and reliability of the optical waveguide structure, laying a solid foundation for the widespread application of full-color waveguides. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the optical waveguide structure of Embodiment 1 of this utility model.

[0021] Figure 2 This is a partial structural schematic diagram of the optical waveguide structure of Embodiment 2 of this utility model.

[0022] Figure 3 These are diffraction efficiency diagrams of the optical waveguide structures in the transition region of embodiments 3-9 and comparative examples 1-7 of this utility model.

[0023] Figure 4 These are diffraction efficiency diagrams of the optical waveguide structures in the coupling region of embodiments 10-16 and comparative examples 8-14 of this utility model.

[0024] In the figure, 1 is the waveguide substrate; 11 is the coupling region; 12 is the transition region; 13 is the coupling region; 2 is the imprinted adhesive layer; 3 is the imprinted grating structure; and 4 is the high refractive index dielectric layer. Detailed Implementation

[0025] To make the technical means, creative features, objectives and effects of this utility model clearer and easier to understand, the present utility model will be further described below in conjunction with the accompanying drawings and specific embodiments. Example

[0026] Example 1: Refer to Figure 1This invention discloses a highly uniform optical waveguide structure, comprising a waveguide substrate 1, an imprinted adhesive layer 2 disposed on the waveguide substrate 1, an imprinted grating structure 3 integrally formed on the imprinted adhesive layer 2 using nanoimprinting technology, and a high-refractive-index dielectric layer 4 disposed on the imprinted grating structure 3. The waveguide substrate 1 is sequentially divided into a coupling region 11, a transition region 12, and a coupling region 13 along the beam transmission path. The grating teeth of the imprinted grating structure 3 located in the transition region 12 and the coupling region 13 are inserted into the high-refractive-index dielectric layer 4, and the refractive index of the high-refractive-index dielectric layer 4 exceeds the refractive index of the imprinted grating structure 3, thereby modulating the FOV-1 and FOV-5 diffraction efficiencies of the red and blue light in the transition region 12 and the coupling region 13.

[0027] Example 2: Refer to Figure 2 This invention discloses a highly uniform optical waveguide structure, which differs from Embodiment 1 in that the waveguide substrate 1 is composed of optical glass with a refractive index of 2.0 and a thickness of 0.7 mm, the imprinted adhesive layer 2 and the imprinted grating structure 3 are composed of imprinted adhesive with a refractive index of 1.5, and the high refractive index dielectric layer 4 is composed of optical resin with a refractive index of 2.0.

[0028] In the coupling region 11, the thickness of the imprinted adhesive layer 2 is 10 nm, and the grating tooth height of the imprinted grating structure 3 is 250 nm, the period is 385 nm, the duty cycle is 100%, the blaze angle is 33°, and the anti-blaze angle is 90°.

[0029] In the transition region 12, the thickness of the imprinted adhesive layer 2 is 50 nm, the grating structure 3 has a grating tooth height of 87 nm, a period of 288 nm, a duty cycle of 70%, a blaze angle of 23.34°, an anti-blaze angle of 90°, and a thickness of 633 nm for the high refractive index dielectric layer 4.

[0030] In the coupling region 13, the thickness of the imprinted adhesive layer 2 is 40 nm, the grating structure 3 has a grating tooth height of 250 nm, a period of 350 nm, a duty cycle of 70%, a blaze angle of 45.58°, an anti-blaze angle of 90°, and a thickness of 500 nm for the high refractive index dielectric layer 4.

[0031] Examples 3-9: This invention discloses a high-uniformity optical waveguide structure. The difference from Example 1 is that the grating structure 3 is only located in the transition region 12 where the grating teeth are inserted into the high-refractive-index dielectric layer 4. In the transition region 12, the duty cycles of the grating structure 3 are 40, 50, 60, 70, 80, 90, and 100%, respectively.

[0032] Examples 10-16: This invention discloses a high-uniformity optical waveguide structure. The difference from Example 1 is that the imprinted grating structure 3 is only located in the coupling region 13 where the grating teeth are inserted into the high-refractive-index dielectric layer 4. In the coupling region 13, the duty cycles of the imprinted grating structure 3 are 40, 50, 60, 70, 80, 90, and 100%, respectively.

[0033] Examples 17-19: These are high-uniformity optical waveguide structures disclosed in this utility model. The difference from Example 1 is that the waveguide substrate 1 is composed of optical glass with a refractive index of 2.0, optical resin, and SiC, respectively.

[0034] Examples 20-29: This invention discloses a highly uniform optical waveguide structure. The difference from Example 1 is that the high refractive index dielectric layer 4 is composed of optical glass with a refractive index of 2.0, Si3N4, TiO2, SiC, SiO2, MgF2, perfluoroalkene, polycarbonate, GaP, and GaS, respectively.

[0035] Examples 30-34: These are high-uniformity optical waveguide structures disclosed in this utility model. The difference from Example 1 is that the coupling region 11, the transition region 12, and the coupling region 13 have the same period, which are 250nm, 350nm, 450nm, and 500nm, respectively.

[0036] Examples 35-40: These are high-uniformity optical waveguide structures disclosed in this utility model. The difference from Example 1 is that the refractive indices of the imprinted adhesive layer 2 are 1.5, 1.6, 1.7, 1.8, and 1.9, respectively. Comparative Example

[0037] Comparative Examples 1-7: These are high-uniformity optical waveguide structures disclosed in this utility model. The difference between them and Examples 3-9 is that the transition region 12 does not have a high-refractive-index dielectric layer 4.

[0038] Comparative Examples 8-14: These are high-uniformity optical waveguide structures disclosed in this utility model. The difference between them and Examples 10-16 is that the coupling region 13 does not have a high-refractive-index dielectric layer 4.

[0039] Performance testing

[0040] Experimental Example 1: Using a 30° FOV and an aspect ratio of 16:9, the diffraction efficiency of the optical waveguide structures in Examples 3-9 and Comparative Examples 1-7 in the transition region 12 was tested. The results are as follows: Figure 3 As shown. From Figure 3(Left) It can be seen that without the high refractive index dielectric layer 4, the modulation amplitude of red light FOV-1 is 0.04~0.08%, and the modulation amplitude of FOV-5 is 0.45~0.77%. For blue light, the modulation amplitude of FOV-1 is 0.30~0.56%, and the modulation amplitude of FOV-5 is 0.91~1.40%. From... Figure 3 (Right) It can be seen that with the high refractive index dielectric layer 4, the modulation amplitude of red light FOV-1 is 6.00~87.41%, the modulation amplitude of FOV-5 is 0.13~2.91%, and the modulation amplitude of blue light FOV-1 is 8.09~12.66%, and the modulation amplitude of FOV-5 is 1.36~8.07%. In contrast, with the high refractive index dielectric layer 4, the modulation amplitude of diffraction efficiency is much greater than that of the simple imprinted grating structure 3, and it breaks through the constraint that the diffraction efficiency of red and blue light changes with parameter variations under the same FOV is consistent. This is beneficial to the uniform modulation and optical efficiency improvement of the full-color waveguide.

[0041] Experimental Example 2: Using a 30° FOV and an aspect ratio of 16:9, the diffraction efficiency of the optical waveguide structures in the coupling region 13 of Examples 10-16 and Comparative Examples 8-14 was tested. The results are as follows: Figure 4 As shown. From Figure 4 (Left) It can be seen that, without the high refractive index dielectric layer 4, the modulation amplitude of red light FOV-1 is 0.37~0.73%, and the modulation amplitude of FOV-5 is 1.80~3.10%. For blue light, the modulation amplitude of FOV-1 is 1.65~3.81%, and the modulation amplitude of FOV-5 is 11.66~33.37%. From... Figure 4 (Right) It can be seen that with the high refractive index dielectric layer 4, the modulation amplitude of red light FOV-1 is 0.78~21.68%, the modulation amplitude of FOV-5 is 9.73~30.22%, and the modulation amplitude of blue light FOV-1 is 11.05~23.89%, and the modulation amplitude of FOV-5 is 7.66~43.3%. In contrast, with the high refractive index dielectric layer 4, the modulation amplitude of diffraction efficiency is much greater than that of the simple imprinted grating structure 3, and it breaks through the constraint that the diffraction efficiency of red and blue light changes with parameter variations under the same FOV is consistent. This is beneficial to the uniform modulation and optical efficiency improvement of the full-color waveguide.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this utility model without departing from the spirit and scope of the technical solutions of this utility model, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A high uniformity optical waveguide structure, characterized by: The device includes a waveguide substrate (1), an imprinted adhesive layer (2) disposed on the waveguide substrate (1), an integrally formed imprinted grating structure (3) disposed on the imprinted adhesive layer (2), and a high refractive index dielectric layer (4) disposed on the imprinted grating structure (3). The waveguide substrate (1) is divided into a coupling-in region (11), a turning region (12), and a coupling-out region (13) along the beam transmission path. The grating teeth of the imprinted grating structure (3) located in the turning region (12) and / or the coupling-out region (13) are inserted into the high refractive index dielectric layer (4), and the refractive index of the high refractive index dielectric layer (4) exceeds the refractive index of the imprinted grating structure (3).

2. A high uniformity optical waveguide structure according to claim 1, wherein: The waveguide substrate (1) is composed of optical glass, optical resin, or SiC.

3. A high uniformity optical waveguide structure according to claim 2, wherein: The thickness of the waveguide substrate (1) is 0.3~1.5mm.

4. A high uniformity optical waveguide structure as claimed in claim 1, wherein: The imprinting adhesive layer (2) and the imprinting grating structure (3) are composed of imprinting adhesive with a refractive index of 1.5 to 1.

9.

5. A high uniformity optical waveguide structure according to claim 4, wherein: The high refractive index dielectric layer (4) is composed of optical glass, optical resin, Si3N4, TiO2, SiC, SiO2, MgF2, perfluoroalkene, polycarbonate, GaP, or GaS.

6. A high uniformity optical waveguide structure according to claim 5, wherein: In the coupling region (11), the thickness of the imprinted adhesive layer (2) is 5~500nm, the grating tooth height of the imprinted grating structure (3) is 10~500nm, the period is 250~500nm, the duty cycle is 20~100%, the blaze angle is 0~90°, and the anti-blaze angle is 0~90°.

7. A high uniformity optical waveguide structure as claimed in claim 5, wherein: In the transition region (12), the thickness of the imprinted adhesive layer (2) is 5~500nm, the grating tooth height of the imprinted grating structure (3) is 10~500nm, the period is 250~500nm, the duty cycle is 20~100%, the blaze angle is 0~90°, and the anti-blaze angle is 0~90°.

8. A high uniformity optical waveguide structure according to claim 7, wherein: In the transition region (12), the thickness of the high refractive index dielectric layer (4) is 50~650 nm.

9. A highly uniform optical waveguide structure according to claim 5, characterized in that: In the coupling region (13), the thickness of the imprinted adhesive layer (2) is 5~500nm, the grating tooth height of the imprinted grating structure (3) is 10~500nm, the period is 250~500nm, the duty cycle is 20~100%, the blaze angle is 0~90°, and the anti-blaze angle is 0~90°.

10. A highly uniform optical waveguide structure according to claim 9, characterized in that: In the coupling region (13), the thickness of the high refractive index dielectric layer (4) is 50~650 nm.

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