Anti-light leakage diffractive optical waveguide apparatus and display device having same

Abstract

An anti-light leakage diffractive optical waveguide apparatus (100), comprising a waveguide substrate (100a), and an in-coupling grating (110) and an out-coupling grating (120) which are formed on the substrate (100a). The out-coupling grating (120) comprises a two-dimensional grating structure (120A) formed on one substrate surface (101) of the waveguide substrate (100a), the two-dimensional grating structure (120A) comprising a structure surface (11) extending along a direction parallel to the substrate surface (101), and a plurality of optical unit structures (10) arranged in an array along the structure surface (11), the optical unit structures (10) being columnar structures, an end face (10a) and a side wall (10b) which is connected between the end face (10a) and the structure surface (11) being formed on each optical unit structure (10), and the end faces (10a) being inclined with respect to the substrate surface (101). The anti-light leakage diffractive optical waveguide apparatus (100) modulates the depth / height direction of the two-dimensional grating structure (120A), facilitating the suppression of light leakage on the field-of-view side and improving the out-coupling efficiency of the diffractive optical waveguide to an observation window.

Description

Light leakage-proof diffraction optical waveguide device and display device having the same

[0001] This application claims the priority of the Chinese patent application filed with the China Patent Office on October 30, 2023, with application number 202311422501.4 and invention name “Anti-light leakage diffraction waveguide device and display device having the same”. Technical Field

[0002] The present invention relates to a display technology based on a diffraction light waveguide, in particular to a light leakage-proof diffraction light waveguide device and a display device having the light leakage-proof diffraction light waveguide device. Background Art

[0003] With the advancement of science and technology, AR (Augmented Reality) display technology, as a highly intelligent and portable display technology, is gradually becoming popular. Its main feature is that it overlays virtual images on real scenes, allowing people to view the real scene simultaneously with the virtual images. Diffractive waveguide devices have been widely used in AR displays. Diffractive waveguides have the advantages of being lightweight, highly dilating, and easy to mass-produce, making them a core component of AR display devices.

[0004] However, existing diffraction waveguide devices for display still have some problems, such as significant light leakage on the field of view side of the device. Figure 1 schematically illustrates the diffraction waveguide device in its display state, wherein the diffraction waveguide device includes a substrate S and an in-coupling grating 1 and an out-coupling grating 2 formed on the substrate. The in-coupling grating 1 couples the input light beam carrying image information from the optical engine LE into the waveguide substrate S and propagates it toward the out-coupling grating 2. The out-coupling grating 2 is used to couple light (as shown by the solid arrow in Figure 1) from the waveguide substrate to the out-coupling side (the side where the eye E is located in Figure 1). However, as shown by the dotted arrow in Figure 1, some light still exits toward the field of view side WS opposite the out-coupling side, causing the aforementioned light leakage problem. This light leakage results in significant energy loss, compromises privacy, and may affect people nearby.

[0005] Therefore, it is urgent to provide a diffraction light waveguide device with improved light leakage prevention performance.

[0006] Summary of the Invention

[0007] An object of the present invention is to provide a diffractive light waveguide device and a display apparatus having the diffractive light waveguide device, which effectively reduce light leakage of the diffractive light waveguide device on the viewing horizon side.

[0008] According to one aspect of the present invention, there is provided a light leakage prevention diffraction waveguide device, comprising a waveguide substrate and an incoupling grating and an outcoupling grating formed on the waveguide substrate, wherein

[0009] The incoupling grating is configured to couple an input light beam from outside the waveguide substrate into the waveguide substrate by diffraction and propagate the input light beam to the outcoupling grating by total internal reflection;

[0010] The outcoupling grating includes a two-dimensional grating structure formed on a substrate surface of the waveguide substrate, wherein the two-dimensional grating structure includes a structural surface extending in a direction parallel to the substrate surface and a plurality of optical unit structures arranged in an array along the structural surface, and is used to expand the light propagating therein in a plane parallel to the substrate surface by diffraction and simultaneously couple it out from the waveguide substrate, wherein the optical unit structure is a columnar structure and is formed with an end face and a side wall connected between the end face and the structural surface, wherein the end face is inclined relative to the substrate surface.

[0011] Advantageously, the tilt angle of the end faces of the plurality of optical unit structures of the two-dimensional grating structure relative to the substrate surface is in the range of 5° to 25°. Preferably, the tilt angle is in the range of 10° to 20°.

[0012] According to different embodiments of the present invention, the columnar structure may be a columnar convex structure or a columnar concave structure, and the end surface is the top surface of the convex structure or the bottom surface of the concave structure.

[0013] Advantageously, the sidewalls are perpendicular to the substrate surface.

[0014] Advantageously, the end surface includes at least one inclined surface inclined relative to the substrate surface, each inclined surface having a corresponding inclined direction, wherein the inclined direction is the direction in which a projection of a ray perpendicular to the inclined surface and pointing away from a side of the waveguide substrate on the substrate surface points; and

[0015] The two-dimensional grating structure includes a first region, and end faces of a plurality of the optical unit structures in the first region include inclined surfaces having the same first inclined orientation.

[0016] Advantageously, the end surfaces of the plurality of optical units in the first region are inclined in the same direction relative to the substrate surface.

[0017] Advantageously, the end surface of at least one of the optical unit structures in the first region comprises a plurality of inclined surfaces, and the plurality of inclined surfaces all have the first inclined orientation.

[0018] Advantageously, the array includes a plurality of rows perpendicular to the first direction formed by arranging the plurality of optical unit structures, the plurality of rows are arranged at a predetermined interval in the first direction, the optical unit structures are arranged in the rows with a period P, and the optical unit structures in two adjacent rows among the plurality of rows have a stagger s = P / n in a direction perpendicular to the first direction, where 1 < n ≤ 5, preferably n = 2; and the first tilt orientation is parallel to the first direction.

[0019] Advantageously, the output grating is a reflective output grating for coupling out at least a part of the light that propagates into the waveguide substrate by total reflection along the coupling-in direction through diffraction from the waveguide substrate toward the opposite side of the side where the output grating is located, and the first tilt orientation is the same as the coupling-in direction; or

[0020] The output grating is a transmissive output grating for coupling out at least a part of the light that propagates into the waveguide substrate by total reflection along the coupling-in direction through diffraction from the waveguide substrate toward the side where the output grating is located, and the first tilt orientation is opposite to the coupling-in direction.

[0021] According to some embodiments of the present invention, the two-dimensional grating structure further includes a second region, and the end faces of the plurality of optical unit structures in the second region include inclined planes having the same second tilt orientation, and the second tilt orientation is different from the first tilt orientation.

[0022] According to some embodiments of the present invention, the two-dimensional grating structure may further include a third region located between the first region and the second region, and the end faces of the plurality of optical unit structures in the third region include inclined planes having the same third tilt orientation, and the third tilt orientation is between the first tilt orientation and the second tilt orientation.

[0023] As an alternative or supplement, the two-dimensional grating structure may further include a third region located between the first region and the second region, and the end face of each optical unit structure in the third region includes both an inclined plane having the first tilt orientation and an inclined plane having the second tilt orientation.

[0024] Advantageously, the edge of the end face has a first point farthest from the substrate surface and a second point closest to the substrate surface, and the maximum distance Hi between the points on the intersection line of the virtual plane passing through the first point and the second point and perpendicular to the substrate surface and the line connecting the first point and the second point in the height direction perpendicular to the substrate surface satisfies: Hi ≤ H / 3, where H is the distance between the first point and the second point in the height direction.

[0025] Advantageously, the edge of the end face has a first point farthest from the substrate surface and a second point closest to the substrate surface, and on the intersection of a virtual plane passing through the first point and the second point and perpendicular to the substrate surface and the end face, from the first point to the second point, the distance between each point and the substrate surface gradually decreases or remains the same.

[0026] Advantageously, the tilt angle of each inclined surface of the end surfaces of the plurality of optical unit structures of the two-dimensional grating structure relative to the substrate surface is in the range of 5° to 30°.

[0027] Advantageously, a projection shape of the optical unit structure on the surface of the substrate is a longitudinal shape extending in the first direction.

[0028] According to different embodiments of the present invention, the longitudinal shape may be a rhombus, a curved rhombus, a double rhombus, a curved double rhombus, or an oval.

[0029] A projected shape of the optical unit structure on the surface of the substrate may be symmetrical or asymmetrical with respect to the first direction.

[0030] According to another aspect of the present invention, there is provided a display device comprising the light leakage preventing diffraction optical waveguide as described above.

[0031] According to some embodiments of the present invention, the display device is a near-eye display device and includes a lens and a frame for holding the lens close to the eye, the lens including the anti-light leakage diffraction optical waveguide.

[0032] Advantageously, the display device is an augmented reality display device or a virtual reality display device.

[0033] According to an embodiment of the present invention, in the outcoupling grating of the anti-light leakage diffraction optical waveguide device, the grating unit structure of the two-dimensional grating structure is constructed to have an end face inclined relative to the surface of the waveguide substrate, thereby forming a modulation of the depth / height direction of the two-dimensional grating, which is beneficial to suppressing light leakage on the field of view side and improving the outcoupling efficiency of the diffraction light waveguide to the observation window. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0035] FIG1 schematically illustrates the light leakage problem of a diffraction light waveguide device during display;

[0036] FIG2 is a schematic plan view of a diffraction waveguide device for preventing light leakage according to a first embodiment of the present invention;

[0037] 3 is a schematic diagram of an example of an optical unit structure that can be used in a diffraction optical waveguide device for preventing light leakage according to an embodiment of the present invention;

[0038] FIG4 is a partial cross-sectional schematic diagram of a different example of a light leakage prevention diffraction waveguide device according to the first embodiment of the present invention, taken along the xz plane, wherein the optical unit structure of the two-dimensional grating structure of the outcoupling grating is a columnar protrusion structure, and the top surface of the protrusion structure has an inclination angle of 0°;

[0039] FIG5 is a partial cross-sectional schematic diagram of a different example of a light leakage prevention diffraction waveguide device according to the first embodiment of the present invention, taken along the xz plane, wherein the optical unit structure of the two-dimensional grating structure of the outcoupling grating is a columnar concave hole structure, and the bottom surface of the concave hole structure has an inclination angle of 0°;

[0040] FIG6 is a partial cross-sectional schematic diagram of a different example of a light leakage prevention diffraction waveguide device according to the first embodiment of the present invention, taken along the xz plane, wherein the end face of the optical unit structure of the two-dimensional grating structure of the outcoupling grating has an inclined azimuth angle of 180°;

[0041] FIG7 schematically shows different examples of optical unit structures, wherein an end face of the optical unit structure includes one or more inclined surfaces;

[0042] FIG8 schematically shows an example of an optical unit structure array of a two-dimensional grating structure of an outcoupling grating in a light leakage prevention diffraction waveguide device according to an embodiment of the present invention;

[0043] FIG9 shows schematic cross-sectional views of three optical unit structures used in Data Example 1, taken along the xz plane, and related tilt azimuth views;

[0044] FIG10 is a graph showing how the zero-order reflection efficiency of a two-dimensional grating structure with different optical unit structures varies with the field of view angle / incident angle in Data Example 1;

[0045] FIG11 is a graph showing how the outcoupling efficiency of a two-dimensional grating structure with different optical unit structures varies with the field of view angle / incident angle in Data Example 1;

[0046] FIG12 shows schematic cross-sectional views of three optical unit structures used in Data Example 2, taken along the xz plane, and related tilt azimuth views;

[0047] FIG13 is a graph showing how the outcoupling efficiency of a two-dimensional grating structure with different optical unit structures varies with the field of view angle / incident angle in Data Example 2;

[0048] FIG14 is a graph showing how the reflective outcoupling efficiency varies with the field of view angle / incident angle after light splitting on both sides of a two-dimensional grating structure using optical unit structures with different tilt and pitch angles in Data Example 3;

[0049] FIG15 is a graph showing how the reflective outcoupling efficiency of the two-dimensional grating structure using optical unit structures with different tilt and pitch angles varies with the field of view angle / incident angle in Data Example 3;

[0050] FIG16 is a schematic plan view of a diffraction waveguide device for preventing light leakage according to a second embodiment of the present invention, showing that the two-dimensional grating structure of the outcoupling grating includes a first region and a second region;

[0051] FIG17 is a schematic plan view of a diffraction waveguide device for preventing light leakage according to a third embodiment of the present invention, showing that the two-dimensional grating structure of the outcoupling grating includes first to third regions;

[0052] Figure 18 is a planar schematic diagram of an anti-leakage light diffraction waveguide device according to a variant of embodiment three of the present invention, which shows that the two-dimensional grating structure of the outcoupling grating includes first to third regions, and the incoupling grating is offset relative to the outcoupling grating. DETAILED DESCRIPTION

[0053] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to explain the relevant invention and are not intended to limit the invention. For ease of description, only portions relevant to the invention are shown in the accompanying drawings. It should be noted that the embodiments and features in the embodiments of this application may be combined with each other unless there is a conflict.

[0054] FIG2 is a schematic plan view illustrating an example of a diffraction waveguide device 100 for preventing light leakage according to a first embodiment of the present invention. As shown in FIG2 , the diffraction waveguide device 100 for preventing light leakage according to the first embodiment of the present invention includes a waveguide substrate 100a and an incoupling grating 110 and an outcoupling grating 120 formed on the waveguide substrate 100a.

[0055] The incoupling grating 110 is configured to couple an input light beam from outside the waveguide substrate 100a into the waveguide substrate 100a by diffraction and propagate the light beam to the outcoupling grating 120 by total internal reflection. In the example shown in FIG2 , the direction of light propagating from the incoupling grating 110 toward the incoupling grating 120 (i.e., the incoupling direction) is indicated by arrow IN in FIG2 . In the context of this application, for the sake of clarity and brevity, the orientation of the incoupling direction within the xy plane parallel to the substrate surface 101 is represented by an azimuth angle αin, and the azimuth angle αin is determined to be 0° as a reference for the azimuth angle within the xy plane, as shown in the azimuth diagram within the dashed box on the left side of FIG2 .

[0056] The outcoupling grating 120 comprises a two-dimensional grating structure 120A formed on a substrate surface 101 of a waveguide substrate 100a. For ease of reference, a schematic, enlarged view of the two-dimensional grating structure 120A is provided in the dashed box on the right side of FIG2 . As shown, the two-dimensional grating structure 120A includes a structure surface 11 (see FIG4 , FIG5 , and FIG6 ) extending in a direction parallel to the substrate surface 101 (including the x- and y-directions) and a plurality of optical unit structures 10 arranged in an array along the structure surface 11. The structure 11 is configured to diffract light propagating therein, diffracting the light within the xy plane parallel to the substrate surface 101 and simultaneously coupling the light out of the waveguide substrate 100a.

[0057] FIG3 schematically illustrates an example of an optical unit structure that can be used in a diffraction waveguide device for preventing light leakage according to an embodiment of the present invention. As shown in FIG3 , optical unit structure 10 is a columnar structure having an end face 10 a and a sidewall 10 b connecting end face 10 a and structure surface 11. Furthermore, end face 10 a is tilted relative to the xy plane and, therefore, relative to substrate surface 101.

[0058] The units of scale in the x-direction, y-direction, and direction perpendicular to the xy plane (i.e., z-direction) shown in FIG3 are in nanometers. However, it should be understood that the dimensions shown in FIG3 are merely exemplary and schematic, and are not intended to limit the implementation and protection scope of the present invention in any sense.

[0059] In the example shown in FIG3 , the optical unit structure 10 is shown as having a columnar protrusion structure, but the present invention is not limited thereto. In different examples, in the anti-light leakage diffraction waveguide device according to embodiments of the present invention, the optical unit structure 10 may also have a columnar concave hole structure, or may be a combination of a columnar protrusion structure and a columnar concave hole structure. In the present application, the end surface 10a of the optical unit structure 10 may be the top surface of the columnar protrusion structure and / or the bottom surface of the columnar concave hole structure.

[0060] When the optical unit structure 10 is a columnar recessed hole structure, the end face 10a of the optical unit structure 10 is the bottom surface of the columnar recessed hole structure, and the side wall 10b is the surface connected between the bottom surface and the structure surface 11; and according to an embodiment of the present invention, the bottom surface 10a is inclined relative to the substrate surface 101.

[0061] In the anti-light leakage diffraction waveguide device according to an embodiment of the present invention, in the two-dimensional grating structure of the outcoupling grating, the grating unit structure is constructed to have an end face inclined relative to the surface of the waveguide substrate, thereby forming a modulation of the depth / height direction of the two-dimensional grating, which is beneficial to suppressing light leakage on the field of view side and improving the outcoupling efficiency of the diffraction light waveguide to the observation window.

[0062] Advantageously, in the light leakage prevention diffraction waveguide device according to embodiments of the present invention, the axial direction of the columnar structure of the optical unit structure 10 can be perpendicular to the substrate surface 101. In particular, in some implementations, the sidewall 10b of the optical unit structure 10 can be perpendicular to the substrate surface 101. This facilitates the design and fabrication of the optical unit structure 10. Here, "perpendicular" is intended to cover slight deviations in the axial direction of the sidewall or the entire columnar structure from the normal to the substrate surface 101 due to fabrication process limitations.

[0063] In the examples shown in Figures 2 and 3 , the tilt angle α of the end face 10a of the optical unit structure 10 relative to the substrate surface 101 is represented by α = 180°, meaning that the tilt angle of the end face 10a is opposite to the coupling direction IN. As will be described in more detail below with reference to various examples shown in the accompanying drawings, the "tilt angle" of an end face of an optical unit structure or an inclined surface included therein, in this application, refers to the direction in which a ray perpendicular to the end face or inclined surface and directed away from the waveguide substrate is projected onto the plane of the substrate surface.

[0064] It should be understood that the tilt azimuth angle α shown in FIG. 2 and FIG. 3 is merely exemplary and non-limiting. In different embodiments of the present invention, according to different application requirements, the tilt azimuth angle α can be designed and constructed to have a different relative relationship with the azimuth angle αin of the coupling direction IN. For example, it can be the same as the azimuth angle αin or tilted at a different angle relative to the latter.

[0065] Next, several types of examples of the diffraction waveguide device for preventing light leakage according to the first embodiment of the present invention will be described with reference to FIG. 4 to FIG. 6 .

[0066] Figure 4 is a schematic partial cross-sectional view taken along the xz plane of different examples of the anti-light leakage diffraction waveguide device according to the first embodiment of the present invention, wherein the optical unit structure of the two-dimensional grating structure of the outcoupling grating is a columnar protrusion structure, and the top surface of the protrusion structure has an inclination azimuth angle of 0°.

[0067] Specifically, in the example shown in FIG4 , the substrate surface 101 of the waveguide substrate 100a coincides with the structure surface 11 of the two-dimensional grating structure. In other examples, a dielectric structure (e.g., composed of the same material as the optical unit structures) may be formed between the plurality of optical unit structures 10 and the substrate surface 101 of the waveguide substrate 100a, with the surface of the dielectric structure constituting the structure surface 11 of the two-dimensional grating structure.

[0068] As shown in Figures (a) and (b) of Figure 4, the optical unit structure 10 as a cylindrical protrusion includes an end face 10a (the top surface of the cylindrical protrusion) and a side wall 10b formed between the end face 10a and the structure surface 11, and the projection direction of the ray N perpendicular to the end face 10a and pointing to the side away from the waveguide substrate 100a on the substrate surface 101 is consistent with the coupling direction (the direction from left to right in the drawing of Figure 4), that is, the tilt azimuth angle α of the end face 10a relative to the substrate surface 101 is 0°.

[0069] Graph (a) of FIG4 illustrates a diffractive optical waveguide device including a transmissive outcoupling grating, wherein light propagating through total internal reflection within the waveguide substrate 100a into the outcoupling grating / optical unit structure 10 is primarily coupled out of the waveguide substrate 100a by transmitting through the outcoupling grating. Specifically, the outcoupling grating is configured to couple at least a portion of the light propagating through the waveguide substrate in the incoupling direction by total internal reflection out of the waveguide substrate through diffraction, with the outcoupling side of the diffractive optical waveguide device being located on the side where the outcoupling grating / optical unit structure 10 is located (the upper side as shown in graph (a)).

[0070] Figure (b) of FIG4 shows a diffraction optical waveguide device including a reflective outcoupling grating, wherein light propagating through total internal reflection in the waveguide substrate 100a to the outcoupling grating / optical unit structure 10 is mainly coupled out from the waveguide substrate 100a by being reflected at the outcoupling grating, that is, the outcoupling side of the diffraction optical waveguide device is located on the opposite side to the side where the outcoupling grating / optical unit structure 10 is located (the lower side shown in Figure (b)).

[0071] For the sake of intuitiveness, FIG. 4 ( c ) shows the tilt azimuth / azimuth angle of the end face 10 a of the optical unit structure 10 in the examples shown in FIG. 4 ( a ) and ( b ).

[0072] Figure 5 is a partial cross-sectional schematic diagram of some other examples of the anti-leakage light diffraction waveguide device according to the first embodiment of the present invention, which is cut along the xz plane, wherein the optical unit structure of the two-dimensional grating structure of the outcoupling grating is a columnar concave hole structure, and the bottom surface of the concave hole structure has an inclination azimuth angle of 0°.

[0073] Specifically, in the example shown in FIG5 , the two-dimensional grating structure includes a dielectric layer M formed on a substrate surface 101 of a waveguide substrate 100a, and optical unit structures 10 comprising a columnar recessed hole structure formed in the dielectric layer M. In this case, the upper surface of the dielectric layer M constitutes the structural surface 11 of the two-dimensional grating structure. In other examples, the plurality of optical unit structures 10 may be recessed hole structures formed directly on the substrate surface 101 of the waveguide substrate 100a (e.g., formed by an etching process); in this case, the substrate surface 101 constitutes the structural surface 11 of the two-dimensional grating structure.

[0074] As shown in Figures (a) and (b) of Figure 5, the optical unit structure 10 as a cylindrical recess includes an end face 10a (the bottom surface of the cylindrical recess) and a sidewall 10b formed between the end face 10a and the structure surface 11, and the projection direction of the ray N perpendicular to the end face 10a and pointing to the side away from the waveguide substrate 100a on the substrate surface 101 is consistent with the coupling direction (the direction from left to right in the drawing of Figure 5), that is, the tilt azimuth angle α of the end face 10a relative to the substrate surface 101 is 0°.

[0075] Similar to FIG4 , FIG5 (a) and (b) respectively show a diffraction optical waveguide device including a transmissive outcoupling grating and a diffraction optical waveguide device including a reflective outcoupling grating, which are not described in detail here.

[0076] Furthermore, graph (c) of FIG. 5 shows the tilt azimuth / azimuth angle of the end face 10 a of the optical unit structure 10 in the examples shown in graphs (a) and (b).

[0077] 6 is a schematic partial cross-sectional view taken along the xz plane of yet another different example of the anti-light leakage diffraction waveguide device according to the first embodiment of the present invention, wherein the end face of the optical unit structure of the two-dimensional grating structure of the outcoupling grating has an inclined azimuth angle of 180°.

[0078] In the example shown in FIG6 (a), the optical unit structure 10 is a cylindrical protrusion structure, while in the example shown in FIG6 (b), the optical unit structure 10 is a cylindrical concave hole structure. In both examples (a) and (b), the projection direction of a ray N perpendicular to the end face 10a of the optical unit structure 10 and directed away from the waveguide substrate 100a on the substrate surface 101 is opposite to the coupling direction (from left to right in FIG6 ). That is, the tilt azimuth angle α of the end face 10a relative to the substrate surface 101 is 180°. FIG6 (c) shows this tilt azimuth angle of the end face 10a in the examples shown in FIG6 (a) and (b).

[0079] Although not specifically shown in the figure, those skilled in the art can understand based on the above content that the outcoupling grating shown in Figures (a) and (b) of Figure 6 can be used as a transmission outcoupling grating or as a reflection outcoupling grating.

[0080] Next, various examples of optical unit structures that can be used in a diffraction waveguide device for preventing light leakage according to embodiments of the present invention will be described with reference to FIG7 , wherein the end faces of the optical unit structures include one or more inclined surfaces. FIG7 schematically illustrates cross-sectional views of various optical unit structures taken along a vertical plane (a plane containing the z-axis) at the tilt azimuth angle of the optical unit structures.

[0081] For illustrative purposes only, the optical unit structures shown in FIG7 are all cylindrical protrusion structures, but the present invention is not limited in this respect. That is, in other examples according to the present invention, the optical unit structure shown in FIG7 , whose end surface includes one or more inclined surfaces, can also be implemented as a cylindrical concave hole structure.

[0082] In Figure 7, the end faces of the optical unit structures shown in Figures (a) and (a') are integrally formed as an inclined surface with respect to the substrate surface. The optical unit structure shown in Figure (a') differs from the structure shown in Figure (a) in that the end face of the former partially intersects with the structure surface (see Figures 4 to 6 and the related descriptions), resulting in the sidewalls of the optical unit structure being formed only over a portion of the circumference of the optical unit structure. It should be understood that the present invention is intended to cover situations where the sidewalls are formed only over a portion of the circumference of the optical unit structure.

[0083] Furthermore, as shown in FIG7 (a), the angle formed by the end face of the optical unit structure as a whole relative to the substrate surface is denoted as a tilt pitch angle θ. Preferably, the tilt pitch angle θ is in the range of 5° to 25°; more preferably, the tilt pitch angle θ is in the range of 10° to 20°.

[0084] Figures (b), (c) and (d) of Figure 7 show that the end face of the optical unit structure may include more than one inclined surface. Different inclined surfaces in the optical unit structure may have the same tilt orientation / azimuth angle. These inclined surfaces may have different pitch angles θ relative to the substrate surface. i Preferably, the pitch angle of each inclined surface relative to the substrate surface is in the range of 5° to 30°.

[0085] In the examples shown in Figures (b), (c), and (d) of Figure 7 , the edge of the end face has a first point P1 farthest from the substrate surface and a second point P2 closest to the substrate surface. The line connecting the first point P1 and the second point P2 (shown as a dotted line in the figure) forms an angle with the substrate surface (a plane parallel to the substrate surface is schematically indicated by a center line in the figure); in this application, this angle is equivalent to the tilt pitch angle of the end face relative to the substrate surface. Preferably, the angle is in the range of 5° to 25°; more preferably, the pitch angle θ is in the range of 10° to 20°.

[0086] Preferably, the maximum distance Hi between each point on the intersection line of a virtual plane passing through the first point P1 and the second point P2 and perpendicular to the substrate surface and the end face and the connecting line in the height direction perpendicular to the substrate surface satisfies: Hi≤H / 3, where H is the distance between the first point P1 and the second point P2 in the height direction (z direction).

[0087] In addition, as shown in FIGS. 7(b), (c), and (d), on the intersection line of the virtual plane passing through the first point P1 and the second point P2 and perpendicular to the substrate surface and the end face, the distances from each point to the substrate surface gradually decrease or remain the same starting from the first point P1 and the second point P2.

[0088] FIGS. 7(b'), (c'), and (d') show an optical unit structure similar to that shown in FIGS. 7(b), (c), and (d), where the end face includes an inclined plane arranged. The difference is only that: the end face of the optical unit structure shown in FIGS. 7(b'), (c'), and (d') further includes a plane 10a-1, and the points in this plane 10a-1 have the maximum distance relative to the structure surface (see FIGS. 2, 4, and 5). Designing the end face 10a to include such a plane 10a-1 can help reduce the processing difficulty of the end face 10a; or in some other cases, such a plane 10a-1 is formed in the end face 10a due to process limitations.

[0089] In an advantageous implementation, the end face of at least one optical unit structure in at least one region of the two-dimensional grating structure includes a plurality of inclined planes, and all the plurality of inclined planes have the same inclination orientation / azimuth angle.

[0090] FIG. 8 schematically shows an example of an array of optical unit structures of a two-dimensional grating structure of an outcoupling grating in a light-leakage prevention diffraction optical waveguide device according to an embodiment of the present invention. As shown in FIG. 8(a), the array of optical unit structures of the two-dimensional grating structure 120A includes a plurality of rows perpendicular to the first direction (e.g., the x direction) formed by arranging a plurality of optical unit structures 10. The plurality of rows are arranged at a predetermined interval D in the first direction. The optical unit structures 10 are arranged at a period P in each row, and the optical unit structures 10 in two adjacent rows among the plurality of rows have a misalignment s = P / n in the direction perpendicular to the first direction (e.g., the y direction), where 1 < n ≤ 5. Preferably, as shown in FIG. 8, n = 2 and s = P / 2. According to this embodiment, preferably, the inclination orientation of the end face of the optical unit structure in the two-dimensional grating structure 120A is parallel to the first direction.

[0091] In addition, as shown in FIG. 8, the projected shape of the optical unit structure 10 on the substrate surface (equivalent to the projected shape in the x-y plane) is a longitudinally elongated shape elongated in the first direction. Among them, in the example shown in FIG. 8(a), the optical unit structure 10 has a rhombic projected shape, and FIGS. 8(b) and (c) further show that the optical unit structure has projected shapes of a curved rhombus and a curved double rhombus. "Double rhombus" refers to the outer contour shape formed by partial overlap of two rhombuses with the same shape and orientation in their longitudinal directions. Also, for example, in some other examples, the longitudinally elongated projected shape of the optical unit structure can also be an ellipse / oval, or can be the "pine nut" shape as shown in FIG. 2.

[0092] It should be understood that although the projected shape of the optical unit structure 10 on the substrate surface shown in the figure is symmetrical about the first direction, the present invention is not limited in this regard, and such a projected shape may also be asymmetrical about the first direction.

[0093] Referring back to the anti-light leakage diffraction waveguide device 100 according to the first embodiment of the present invention shown in FIG2 , the outcoupling grating 120 comprises a two-dimensional grating structure 120A. According to the first embodiment, the end faces 10a of the plurality of optical unit structures 10 in the two-dimensional grating structure 120A comprise inclined surfaces having the same tilt orientation / azimuth angle.

[0094] Advantageously, the end faces 10a of the multiple optical elements 10 in the two-dimensional grating structure 120A can be tilted in the same direction relative to the substrate surface. Here, "tilted in the same direction" means that both the azimuth and elevation angles of the tilt are the same. This configuration facilitates the fabrication of the diffractive optical waveguide device, thereby improving yield and reducing costs.

[0095] Advantageously, the outcoupling grating 120 is used to couple at least a portion of the light propagating into the waveguide substrate 100a along the coupling direction IN by total reflection out of the waveguide substrate 100a by diffraction, and the above-mentioned same tilt orientation of the end faces 10a of the multiple optical unit structures 10 can be the same as the coupling direction IN.

[0096] Furthermore, in some implementations, it may be advantageous to configure the outcoupling grating 120 as a reflective outcoupling grating, which means that the outcoupling grating couples light out of the waveguide substrate toward the side opposite to the side where the outcoupling grating is located.

[0097] The technical effects of the light leakage preventing diffraction waveguide device according to the embodiment of the present invention will be described below through data examples.

[0098] (Data Example 1)

[0099] In Data Example 1, simulations were performed on the reflective and transmissive outcoupling efficiencies of a two-dimensional grating structure comprising three different optical unit structures. These two-dimensional grating structures have the array structure shown in Figure 8 (a), where the arrangement period P = 485 nm, D = 420 nm, and n = 2. The projection of the optical unit structure onto the substrate surface is a diamond shape, with the longitudinal direction of the diamond parallel to the first direction of the array and parallel to the incoupling direction IN of light propagating into the outcoupling grating / two-dimensional grating structure.

[0100] FIG9 shows schematic cross-sectional views taken along the xz plane and related tilt azimuth / azimuth angle diagrams of the three optical unit structures used in Data Example 1. As shown in FIG9 , the three optical unit structures are all columnar concave hole structures, wherein: the optical unit structure 10′ shown in FIG1a is a non-slant structure, and its projection shape on the substrate surface has a rhombus side length of 260nm, a vertex angle of 60°, and a depth h0=65nm; the optical unit structure 10A shown in FIG1b has the same projection shape on the substrate surface as the structure 10′, but has a slope 1 structure, wherein the tilt azimuth angle of the end face is 0° (see FIG1b′), and the upstream end of the end face along the coupling direction is opposite to the upstream end. For the depth h1 of the structure surface 11 = 25 nm, the depth h2 of the downstream end relative to the structure surface 11 = 105 nm; the projection shape of the optical unit structure 10B shown in Figure (1c) on the substrate surface is the same as that of the structure 10', but has a bevel 2 structure, wherein the inclination azimuth angle of the end face is 180° (see Figure (1c')), wherein the depth h1 of the upstream end of the end face along the coupling direction relative to the structure surface 11 = 105 nm, and the depth h2 of the downstream end relative to the structure surface 11 = 25 nm.

[0101] In Data Example 1, the concave hole structures of the optical unit structures 10', 10A, and 10B are constructed to have substantially the same volume. This means that the zero-order reflection outcoupling efficiency of light when passing through the two-dimensional outcoupling gratings formed by them is substantially the same. Specifically, see Figure 10, a graph showing the variation of the zero-order reflection efficiency of the two-dimensional grating structure using different optical unit structures as a function of the field of view angle / incident angle in Data Example 1. Under the condition that the zero-order reflection efficiency is substantially the same, the outcoupling efficiency of the two-dimensional grating structure composed of three different optical unit structures is simulated and compared in Data Example 1.

[0102] The wavelength used in the simulation calculation of Data Example 1 is 522 nm, and the incident angle of the light incident on the out-coupling grating / two-dimensional grating structure by total internal reflection in the waveguide substrate 100a is (See the angles in Figures 4 and 5 ) is in the range of 33°-50°.

[0103] Figure 11 shows a graph of the outcoupling efficiency of the two-dimensional grating structure using different optical unit structures as a function of the field of view angle / incident angle in Data Example 1. Referring to Figure 11 , the simulation results for Data Example 1 show that the transmission outcoupling efficiency and reflection outcoupling efficiency of the two-dimensional grating structure corresponding to the optical unit structure 10' without a bevel are relatively close, with the ratio of the average reflection outcoupling efficiency to the average transmission outcoupling efficiency at each incident angle being approximately 1.36. The ratio of the average reflection outcoupling efficiency to the average transmission outcoupling efficiency of the two-dimensional grating structure corresponding to the optical unit structure 10A with a bevel 1 structure is as high as 3.39. The ratio of the average reflection outcoupling efficiency to the average transmission outcoupling efficiency of the two-dimensional grating structure corresponding to the optical unit structure 10B with a bevel 2 structure is approximately 0.51, or in other words, the ratio of its average transmission outcoupling efficiency to its average reflection outcoupling efficiency is approximately 1.96.

[0104] For ease of reference, the parameters related to the outcoupling efficiency corresponding to the above-mentioned optical unit structures in Data Example 1 are listed in Table 1 below.

[0105] Table 1

[0106] Combining the contents shown in Figure 11 and Table 1, it can be seen that the optical unit structure 10A with the bevel 1 structure greatly improves the reflective outcoupling efficiency and reduces the transmissive outcoupling efficiency, and can be used as a reflective outcoupling grating to improve the efficiency of light entering the observation window, while greatly reducing the light leakage of the diffraction optical waveguide device to the field of view side (opposite to the outcoupling side); the optical unit structure 10B with the bevel 2 structure is suitable for use as a transmissive outcoupling grating, which can improve the efficiency of light entering the observation window and significantly reduce the light leakage on the field of view side.

[0107] (Data Example 2)

[0108] In Data Example 2, simulations were performed on the reflective and transmissive outcoupling efficiencies of a two-dimensional grating structure comprising three different optical unit structures. These two-dimensional grating structures have the array structure shown in Figure 8 (a), where the arrangement period P = 485 nm, D = 420 nm, and n = 2. The projection of the optical unit structure onto the substrate surface is a diamond shape, with the longitudinal direction of the diamond parallel to the first direction of the array and parallel to the incoupling direction IN of light propagating into the outcoupling grating / two-dimensional grating structure.

[0109] FIG12 shows schematic cross-sectional views of the three optical unit structures used in Data Example 2, taken along the xz plane, and diagrams of the relevant tilting orientations. As shown in FIG12 , the three optical unit structures are all columnar protrusion structures, wherein: the optical unit structure 10″ shown in FIG2a is a structure without a bevel, and the rhombus side length of its projection shape on the substrate surface is 220nm, the top angle is 60°, and the height h0=70nm; the optical unit structure 10A′ shown in FIG2b has the same projection shape on the substrate surface as the structure 10″, but has a bevel 1 structure, wherein the tilting azimuth angle of the end face is 0° (see FIG2b′), and the upstream end of the end face along the coupling direction is 0°. The depth h1 relative to the structure surface 11 is 106 nm, and the depth h2 of the downstream end relative to the structure surface 11 is 34 nm; the projection shape of the optical unit structure 10B' shown in Figure (2c) on the substrate surface is the same as that of the structure 10", but has a slope 2 structure, wherein the inclination azimuth angle of the end face is 180° (see Figure (2c')), wherein the depth h1 of the upstream end of the end face along the coupling direction relative to the structure surface 11 is 34 nm, and the depth h2 of the downstream end relative to the structure surface 11 is 106 nm.

[0110] In Data Example 2, the concave hole structures of the optical unit structures 10", 10A' and 10B' are constructed to have basically the same volume. This means that the coupling efficiency of zero-order reflection when light passes through the two-dimensional coupling gratings formed by them is basically the same. Under the condition that the zero-order reflection efficiency is basically the same, the coupling efficiency of the two-dimensional grating structure composed of three different optical unit structures is simulated and compared in Data Example 2.

[0111] The wavelength used in the simulation calculation of Data Example 2 is 522 nm, and the incident angle of the light incident on the out-coupling grating / two-dimensional grating structure by total internal reflection in the waveguide substrate 100a is In the range of 33°-50°.

[0112] FIG13 shows a graph showing how the outcoupling efficiency of the two-dimensional grating structure using different optical unit structures in Data Example 2 changes with the field of view angle / incident angle. Referring to FIG13 , the simulation results of Data Example 2 show that the ratio of the average reflection outcoupling efficiency to the average transmission outcoupling efficiency at various incident angles of the two-dimensional grating structure corresponding to the optical unit structure 10" without a bevel is approximately 1.32; the ratio of the average reflection outcoupling efficiency to the average transmission outcoupling efficiency of the two-dimensional grating structure corresponding to the optical unit structure 10A' with a bevel 1 structure is as high as 2.13; the ratio of the average reflection outcoupling efficiency to the average transmission outcoupling efficiency of the two-dimensional grating structure corresponding to the optical unit structure 10B' with a bevel 2 structure is approximately 0.83, or in other words, the ratio of its average transmission outcoupling efficiency to its average reflection outcoupling efficiency is approximately 1.20.

[0113] For ease of reference, the parameters related to the outcoupling efficiency corresponding to the above-mentioned optical unit structures in Data Example 2 are listed in Table 2 below.

[0114] Table 2

[0115] Combining FIG13 and the contents shown in Table 2, it can be seen that the optical unit structure 10A′ with the bevel 1 structure significantly improves the reflective outcoupling efficiency and reduces the transmissive outcoupling efficiency, and can be used as a reflective outcoupling grating to improve the efficiency of light entering the observation window, while significantly reducing the light leakage of the diffraction optical waveguide device to the field of view side (opposite to the outcoupling side); the optical unit structure 10B′ with the bevel 2 structure is suitable for use as a transmissive outcoupling grating, which can improve the efficiency of light entering the observation window and reduce the light leakage on the field of view side.

[0116] (Data Example 3)

[0117] Data Example 3 was designed to further investigate the effect of the tilted pitch angle of the optical unit structure's end face on the outcoupling efficiency, specifically its effect on the recoupling efficiency after the two-dimensional grating's biaxial light splitting. In Data Example 3, using a two-dimensional grating as a reflective outcoupling grating as an example, simulations were performed to investigate both the outcoupling efficiency before biaxial light splitting (hereinafter referred to as "reflective outcoupling efficiency") and the recoupling efficiency after biaxial light splitting.

[0118] Specifically, Data Example 3 simulates the reflection outcoupling efficiency and the recoupling efficiency after two-sided light splitting of a two-dimensional grating structure composed of an optical unit structure (hereinafter referred to as "no bevel," "5° bevel," "10° bevel," "15° bevel," "20° bevel," "25° bevel," and "30° bevel") with an end facet tilt azimuth angle α of 0° and a tilt pitch angle θ (see angle θ shown in Figures 4, 5, and 7) of 0°, 5°, 10°, 15°, 20°, 25°, and 30°, respectively. For the sake of simplicity and clarity, only an optical unit structure with a cylindrical concave hole structure containing a single bevel on the end face is used as an example.

[0119] The two-dimensional grating structure in Data Example 3 has the array structure shown in graph (a) of Figure 8 , where the arrangement period P = 485 nm, D = 420 nm, and n = 2. The projection of the optical unit structure onto the substrate surface is a rhombus, with a side length of 200 nm and a vertex angle of 60°. The longitudinal direction of the rhombus is parallel to the first direction of the array and to the coupling direction IN of light propagating into the outcoupling grating / two-dimensional grating structure. Furthermore, the average depth of the different optical unit structures is 100 nm.

[0120] For a two-dimensional outcoupling grating in a diffractive waveguide device, the recoupling efficiency after double-sided diffraction splitting significantly impacts the overall outcoupling efficiency and brightness uniformity within the field of view. Figure 14 shows a plot of the reflective outcoupling efficiency of the two-dimensional grating structure in Data Example 3 after double-sided splitting as a function of the field of view angle / incident angle. As shown in Figure 14, the simulation results show that as the tilt angle θ increases from 0° to 15°, the average recoupling efficiency after double-sided splitting corresponding to the two-dimensional grating structure gradually increases. The average recoupling efficiency after double-sided splitting corresponding to the 15° bevel is the highest overall. As the tilt angle θ increases from 15° to 30°, the average recoupling efficiency after double-sided splitting corresponding to the two-dimensional grating structure gradually decreases. The average recoupling efficiency after double-sided splitting after the 25° bevel is lower than that of the structure without the bevel over the local field of view incident angle range, while the average recoupling efficiency of the structure with a 30° bevel decreases compared to the other structures. Therefore, from the perspective of improving the average re-coupling efficiency after splitting on both sides, it is beneficial for the pitch angle θ of the end face of the optical unit structure to be in the range of 5° to 25°; preferably, the pitch angle θ is in the range of 5° to 20°, and more preferably in the range of 10° to 20°.

[0121] Figure 15 is a graph showing the reflection outcoupling efficiency of a two-dimensional grating structure using optical unit structures with different tilt and pitch angles as compared to the field of view angle / incident angle in Data Example 3. As can be seen from Figure 15, the optical unit structure with a beveled surface is beneficial for improving the reflection outcoupling efficiency. Furthermore, as the tilt and pitch angle θ increases from 0° to 30°, the reflection outcoupling efficiency first increases and then decreases (the curve position first rises and then decreases). The 20° bevel has the highest overall reflection outcoupling efficiency, and the 5°, 10°, 15°, 20°, and 30° bevels all have higher reflection outcoupling efficiencies than the non-beveled structure. Accordingly, from the perspective of improving the reflection outcoupling efficiency, it is advantageous for the pitch angle θ of the end face of the optical unit structure to be within the range of 5° to 30°. Preferably, the pitch angle θ is within the range of 10° to 25°, and more preferably, within the range of 15° to 25°.

[0122] Taking into account the average outcoupling efficiency before and after splitting on both sides, the tilt pitch angle θ of the optical unit structure is advantageously in the range of 5° to 25°, preferably in the range of 10° to 20°, and more preferably in the range of 15° to 20°.

[0123] In addition, considering the implementation method in which the end face of the optical unit structure shown in Figure 7 includes a combination of multiple inclined surfaces, more optimization freedom for each coupling-out efficiency can be provided by adjusting the tilt and pitch angles of the multiple inclined surfaces, thereby further optimizing the light utilization efficiency and display uniformity of the diffraction optical waveguide device.

[0124] FIG16 schematically illustrates a plan view of an example of a light leakage prevention diffraction waveguide device 200 according to a second embodiment of the present invention. As shown in FIG16 , the light leakage prevention diffraction waveguide device 200 includes a waveguide substrate 200a, an incoupling grating 210, and an outcoupling grating 220 formed on the waveguide substrate 200a. The outcoupling grating 220 includes a two-dimensional grating structure 220A formed on a substrate surface 201 of the waveguide substrate 200a. The light leakage prevention diffraction waveguide device 200 can have a substantially identical structure to the light leakage prevention diffraction waveguide device 100 according to the first embodiment of the present invention. The similarities are not further described here; the differences are described in detail below.

[0125] According to the second embodiment of the present invention, as shown in FIG16 , the two-dimensional grating structure 220A may include a first region R1 and second regions R21 and R22. The end faces of the multiple optical unit structures in the first region R1 include inclined surfaces having the same tilt azimuth angle α1 (corresponding to the "first tilt azimuth"). The end faces of the multiple optical unit structures in the second region R21 include inclined surfaces having the same tilt azimuth angle α21. The end faces of the multiple optical unit structures in the second region R22 include inclined surfaces having the same tilt azimuth angle α22. The tilt azimuth angles α21 and α22 (corresponding to the "second tilt azimuth") are different from the tilt azimuth angle α1. In some other examples, the two-dimensional grating structure 220A may include only one of the second regions R21 and R22. Based on the anti-light leakage diffraction waveguide device according to the second embodiment, the outcoupling efficiency in the corresponding region can be adjusted by adjusting the tilt azimuth angles of the end faces of the optical unit structures in different regions of the two-dimensional grating structure 220A, thereby meeting different performance requirements.

[0126] Advantageously, the end faces of the multiple optical unit structures in the first region R1 include multiple inclined surfaces, and the multiple inclined surfaces have the same tilt azimuth angle α1; and / or, the end faces of the multiple optical unit structures in each second region R21 / R22 include multiple inclined surfaces, and the multiple inclined surfaces have the same tilt azimuth angle α21 / α21.

[0127] Advantageously, the end faces of the multiple optical unit structures in the first region R1 can be tilted in the same direction relative to the substrate surface; and / or, the end faces of the multiple optical unit structures in each second region R21, R22 can be tilted in the same direction relative to the substrate surface.

[0128] Advantageously, the outcoupling grating 220 is a reflective outcoupling grating, and the tilt azimuth angle α1 is the same as the azimuth angle αin of the coupling direction IN (see FIG. 2 ) along which light propagates from the coupling grating 210 to the outcoupling grating 220 (ie, the first tilt azimuth is the same as the coupling direction).

[0129] Advantageously, the outcoupling grating 220 is a transmissive outcoupling grating, and the tilt azimuth angle α1 differs from the azimuth angle αin of the coupling direction IN (see FIG. 2 ) by 180° (ie, the first tilt azimuth is opposite to the coupling direction).

[0130] Advantageously, the tilt azimuth angles α21 / α21 are each deflected by 50°-70°, preferably 60°, in opposite directions relative to the tilt azimuth angle α1 .

[0131] FIG17 is a schematic plan view of a light leakage prevention diffraction waveguide device 300 according to a third embodiment of the present invention. As shown in FIG17 , the light leakage prevention diffraction waveguide device 300 includes a waveguide substrate 300a, an incoupling grating 310, and an outcoupling grating 320 formed on the waveguide substrate 300a. The outcoupling grating 320 includes a two-dimensional grating structure 320A formed on a substrate surface 301 of the waveguide substrate 300a.

[0132] The anti-light leakage diffraction waveguide device 300 has substantially the same structure as the diffraction waveguide device 200 according to the second embodiment, except that the two-dimensional grating structure 320A further includes third regions R31 and R32 located between the first region R1 and the second regions R21 and R22.

[0133] In the example shown in Figure 17, the end faces of multiple optical unit structures in the third region R31 include inclined surfaces with the same tilt azimuth angle α31 (corresponding to the "third tilt orientation"), and the end faces of multiple optical unit structures in the third region R32 include inclined surfaces with the same tilt azimuth angle α32 (corresponding to the "third tilt orientation"), the tilt azimuth angle α31 is between the tilt azimuth angle α1 and the tilt azimuth angle α21, and the tilt azimuth angle α32 is between the tilt azimuth angle α1 and the tilt azimuth angle α22.

[0134] In other examples, the end surface of each optical unit structure in the third region R31 includes a slope having an inclination angle α1 and a slope having an inclination angle α21, and the end surface of each optical unit structure in the third region R32 includes a slope having an inclination angle α1 and a slope having an inclination angle α22.

[0135] According to the third embodiment of the present invention, by configuring the optical unit structure in the third region to have the above-mentioned end face tilt azimuth angle feature, more degrees of freedom in adjusting the outcoupling efficiency and other optical performances can be provided.

[0136] FIG18 is a schematic plan view of a light leakage-preventing diffraction waveguide device 300' according to a variant of the third embodiment of the present invention. The diffraction waveguide device 300' can have a structure substantially identical to the diffraction waveguide device 300 shown in FIG17 , differing only in that the incoupling grating 310' in the diffraction waveguide device 300 is offset to the left relative to the outcoupling grating 320'. Accordingly, the two-dimensional grating structure 320'A of the outcoupling grating 320' is configured to include a first region R1, a second region R2 located to one side of the first region R1, and a third region R3 located between the first and second regions R1 and R2. The optical unit structures in the first, second, and third regions R3 can have the same or similar inclined end face structures as those described above with reference to FIG2 through FIG17 , and are not further described here.

[0137] Although the outcoupling grating of the anti-light leakage diffraction optical waveguide device according to an embodiment of the present invention is described in the drawings and the above text as including a two-dimensional grating structure, it should be understood that the present invention is not limited to the case where the outcoupling grating only includes a two-dimensional grating structure; in other embodiments or examples, the outcoupling grating may further include a one-dimensional grating, for example, a one-dimensional grating arranged on both sides of the two-dimensional grating structure in a direction perpendicular to the coupling direction.

[0138] Light waveguide devices according to embodiments of the present invention can be used in display devices. Such display devices, for example, are near-eye display devices, which include lenses and a frame for holding the lenses close to the eyes. The lenses may include the light waveguide devices according to embodiments of the present invention described above. Preferably, the display device may be an augmented reality display device or a virtual reality display device.

[0139] The anti-light leakage diffraction light waveguide according to embodiments of the present invention can be applied to a display device. Such a display device can be a near-eye display device, comprising a lens and a frame for holding the lens close to the eye, wherein the lens may include the anti-light leakage diffraction light waveguide. Preferably, the display device is an augmented reality display device or a virtual reality display device.

[0140] The above description is merely a preferred embodiment of the present application and an illustration of the technical principles employed. Those skilled in the art should understand that the scope of the invention herein is not limited to the technical solutions formed by the specific combination of the above-mentioned technical features, but also encompasses other technical solutions formed by any combination of the above-mentioned technical features or their equivalents without departing from the inventive concept. For example, a technical solution formed by replacing the above-mentioned features with (but not limited to) technical features having similar functions disclosed in this application.

Claims

1. A light-leakage-proof diffractive optical waveguide device, comprising a waveguide substrate and an input grating and an output grating formed on the waveguide substrate, wherein the input grating is configured to couple an input light beam from outside the waveguide substrate into the waveguide substrate by diffraction and propagate it to the output grating through total internal reflection; The out-coupling grating comprises a two-dimensional grating structure formed on a substrate surface of the waveguide substrate, wherein the two-dimensional grating structure comprises a structure surface extending in a direction parallel to the substrate surface and a plurality of optical unit structures arranged in an array along the structure surface, and is used to expand the light propagating therein in a plane parallel to the substrate surface by diffraction and couple it out from the waveguide substrate at the same time, wherein the optical unit structure is a columnar structure and is formed with an end face and a side wall connected between the end face and the structure surface, wherein, the end face is inclined with respect to the substrate surface.

2. The light leakage preventing diffraction optical waveguide device according to claim 1, wherein: The inclination pitch angle of the end faces of the plurality of optical unit structures of the two-dimensional grating structure with respect to the substrate surface is in the range of 5° to 25°.

3. The light leakage preventing diffraction optical waveguide device according to claim 1, wherein: The inclination pitch angle is in the range of 10° to 20°.

4. The light leakage preventing diffraction optical waveguide device according to claim 1, wherein: The columnar structure is a columnar convex structure or a columnar concave hole structure, and the end face is the top surface of the convex structure or the bottom surface of the concave hole structure.

5. The light leakage preventing diffraction optical waveguide device according to claim 1, wherein: The side wall is perpendicular to the substrate surface.

6. The light leakage preventing diffraction optical waveguide device according to claim 1, wherein: The end face includes at least one inclined surface inclined with respect to the substrate surface, and each inclined surface has a corresponding inclination azimuth, and the inclination azimuth is the direction pointed by the projection of a ray perpendicular to the inclined surface and pointing away from the waveguide substrate on the substrate surface; and the two-dimensional grating structure includes a first region, and the end faces of the plurality of optical unit structures in the first region include inclined surfaces having the same first inclination azimuth.

7. The light leakage preventing diffraction optical waveguide device according to claim 6, wherein: The end faces of the plurality of optical units in the first region are inclined in the same direction with respect to the substrate surface.

8. The light leakage preventing diffraction optical waveguide device according to claim 6, wherein: The end face of at least one of the optical unit structures in the first region includes a plurality of inclined surfaces, and the plurality of inclined surfaces all have the first inclination azimuth.

9. The light leakage preventing diffraction optical waveguide device according to claim 6, wherein: The array includes a plurality of rows perpendicular to the first direction formed by arranging the plurality of optical unit structures, the plurality of rows are arranged at a predetermined interval in the first direction, the optical unit structures are arranged in the rows with a period P, and the optical unit structures in two adjacent rows among the plurality of rows are offset by s = P / n in a direction perpendicular to the first direction, where 1 < n ≤ 5; and the first inclination azimuth is parallel to the first direction.

10. The light leakage preventing diffraction optical waveguide device according to claim 9, wherein: n＝2。 11. The light leakage preventing diffraction optical waveguide device according to claim 6, wherein: The output grating is a reflective output grating, configured to couple at least a part of the light that propagates into it in the waveguide substrate through total internal reflection along the input direction out of the waveguide substrate by diffraction toward the opposite side of the side where the output grating is located, and the first inclination azimuth is the same as the input direction; or The output grating is a transmissive output grating, configured to couple at least a part of the light that propagates into it in the waveguide substrate through total internal reflection along the input direction out of the waveguide substrate by diffraction toward the side where the output grating is located, and the first inclination azimuth is opposite to the input direction.

12. The light leakage preventing diffraction optical waveguide device according to claim 6, wherein: The two-dimensional grating structure further includes a second region, and the end faces of the plurality of optical unit structures in the second region include inclined surfaces having the same second inclination azimuth, and the second inclination azimuth is different from the first inclination azimuth.

13. The light leakage preventing diffraction optical waveguide device according to claim 12, wherein: The two-dimensional grating structure also includes a third region located between the first region and the second region, and the end faces of the plurality of optical unit structures in the third region include inclined surfaces having the same third tilt orientation, and the third tilt orientation is between the first tilt orientation and the second tilt orientation.

14. The light leakage preventing diffraction optical waveguide device according to claim 12, wherein: The two-dimensional grating structure further includes a third region located between the first region and the second region, and an end surface of each of the optical unit structures in the third region includes both an inclined surface with a first inclined orientation and an inclined surface with a second inclined orientation.

15. The light leakage preventing diffraction optical waveguide device according to any one of claims 6 to 14, wherein: The edge of the end face has a first point farthest from the substrate surface and a second point closest to the substrate surface, and the maximum distance H between each point on the intersection line of the virtual plane passing through the first point and the second point and perpendicular to the substrate surface and the end face and the line connecting the first point and the second point in the height direction perpendicular to the substrate surface is i Satisfaction: H i ≤H / 3, where H is the distance between the first point and the second point in the height direction.

16. The light leakage preventing diffraction optical waveguide device according to any one of claims 6 to 14, wherein: The edge of the end face has a first point farthest from the substrate surface and a second point closest to the substrate surface, and on an intersection line of a virtual plane passing through the first point and the second point and perpendicular to the substrate surface and the end face, from the first point to the second point, the distance between each point and the substrate surface gradually decreases or remains the same.

17. The light leakage preventing diffraction optical waveguide device according to any one of claims 1 to 14, wherein: The tilt angle of each inclined surface of the end surfaces of the multiple optical unit structures of the two-dimensional grating structure relative to the substrate surface is in the range of 5° to 30°.

18. The light leakage preventing diffraction optical waveguide device according to claim 9, wherein: The projection shape of the optical unit structure on the surface of the substrate is a longitudinal shape extending in the first direction.

19. The light leakage preventing diffraction optical waveguide device according to claim 18, wherein: The longitudinal shape is a rhombus, a curved rhombus, a double rhombus, a curved double rhombus or an oval.

20. The light leakage preventing diffraction optical waveguide device according to claim 18, wherein: The projection shape of the optical unit structure on the surface of the substrate is symmetrical or asymmetrical with respect to the first direction.

21. A display device comprising the light leakage preventing diffraction optical waveguide according to any one of claims 1 to 20.

22. The display device according to claim 21, wherein: The display device is a near-eye display device and includes a lens and a frame for holding the lens close to the eye, the lens including the anti-light leakage diffraction optical waveguide.

23. The display device according to claim 21 or 22, wherein: The display device is an augmented reality display device or a virtual reality display device.

Images