Optical waveguide structure and augmented-reality display apparatus

Abstract

Provided in the present application is an optical waveguide structure, comprising a first waveguide, a first in-coupling grating, and a first out-coupling grating. The first waveguide has a first surface and a second surface opposite each other, and is used for receiving sub-image light which has a first wavelength range and guiding same to propagate in a first direction. The first in-coupling grating is arranged on the first surface, and is used for receiving image light and coupling into the first waveguide the sub-image light which has the first wavelength range. A grating direction of the first in-coupling grating has a first included angle relative to the first direction. The first out-coupling grating is used for receiving and coupling out the sub-image light which has the first wavelength range and is emergent from the first waveguide, and a grating direction of the first out-coupling grating has a second included angle relative to the first direction. The first included angle and the second included angle are non-zero, and the grating direction of the first in-coupling grating is opposite to the grating direction of the first out-coupling grating. Further provided in the present application is an augmented-reality display apparatus comprising the optical waveguide structure.

Description

Optical waveguide structure and augmented reality display device Technical Field

[0001] This application relates to the field of augmented reality technology, and in particular to an optical waveguide structure and an augmented reality display device. Background Technology

[0002] With the development of technology, Augmented Reality (AR) technology has been applied to various fields, such as gaming, education, healthcare, and retail. AR display devices project computationally generated virtual images onto the user's eyes through a display module and waveguide structure, overlaying them onto the real space to create a fusion of virtual and reality. Currently, most commercially available AR display devices primarily use one-dimensional pupil expansion technology to extend the horizontal field of view, allowing the user's eyes to see the displayed image as they move laterally.

[0003] However, the aforementioned one-dimensional pupil expansion technology has difficulty expanding the vertical field of view. Furthermore, as the image light is transmitted from the input grating to the output grating, the image light includes sub-image light with different wavelength ranges. Light with different wavelength ranges will gradually deviate and shift away from the central axis of the optical waveguide structure, resulting in an incomplete display image received by the human eye in the vertical direction. When the user's eyes move in the vertical direction, the display image seen is incomplete, thereby reducing the vertical field of view and affecting the display effect. Summary of the Invention

[0004] The first aspect of this application provides an optical waveguide structure, comprising:

[0005] A first waveguide having opposing first and second surfaces for receiving and guiding sub-image light with a first wavelength range to propagate along a first direction;

[0006] A first coupling grating, disposed on the first surface, is used to receive image light and couple the sub-image light having a first wavelength range into the first waveguide. The grating direction of the first coupling grating has a first angle θ1 relative to the first direction.

[0007] A first output grating, together with a first input grating, is disposed on the first surface and arranged along the first direction. The first output grating is used to receive and couple out the sub-image light having a first wavelength range emitted from the first waveguide. The grating direction of the first output grating has a second angle θ2 relative to the first direction.

[0008] Wherein, the first included angle θ1 and the second included angle θ2 are not zero, and the grating direction of the first coupled-in grating is opposite to the grating direction of the first coupled-out grating.

[0009] The optical waveguide structure provided in this application embodiment, by setting a first coupling grating and a first coupling grating, wherein the grating directions of the first coupling grating and the first coupling grating are opposite, and the first angle between the grating direction of the first coupling grating and the first angle between the grating direction of the first coupling grating and the first direction is not zero, thereby making the grating directions of the first coupling grating and the first coupling grating have angles relative to the first direction, which can reduce the angle of deviation of sub-image light with a first wavelength range from the central axis of the optical waveguide structure during the transmission from the first coupling grating to the first coupling grating. By reducing the offset angle of sub-image light with a first wavelength range during its transmission from the first input grating to the first output grating, the field of view in the vertical direction perpendicular to the first direction can be increased without affecting the overall volume of the optical waveguide structure. When the optical waveguide structure is applied to an augmented reality display device, by increasing the field of view in the vertical direction perpendicular to the first direction, the user's eye can receive sub-image light with a first wavelength range in the vertical direction, so that the user's eye can see the displayed image more completely when moving in the vertical direction, thereby enhancing the display effect without affecting the overall volume of the augmented reality display device.

[0010] In one embodiment, the first included angle θ1 satisfies: -15°≤θ1<0°, 0°<θ1≤15°; the second included angle θ2 satisfies: -180°<θ2≤-165°, 165°≤θ2<180°.

[0011] In one embodiment, the optical waveguide structure further includes a second waveguide, a second coupling grating, and a second coupling out grating;

[0012] The second waveguide has opposing third and fourth surfaces, and is attached to one side of the first waveguide and covers the first coupling grating and the first coupling grating; the second waveguide is used to receive and guide sub-image light with a second wavelength range to propagate along the first direction;

[0013] A second coupling grating is disposed on the third surface for receiving and coupling the sub-image light with a second wavelength range into the second waveguide. The grating direction of the second coupling grating has a third angle θ3 relative to the first direction.

[0014] The second output grating and the second input grating are disposed on the third surface and are arranged along the first direction with the second input grating. The second output grating is used to receive and couple out the sub-image light with the second wavelength range emitted from the second waveguide. The grating direction of the second output grating has a fourth included angle θ4 relative to the first direction.

[0015] Wherein, the third included angle θ3 and the fourth included angle θ4 are not zero, and the grating direction of the second coupled-in grating is opposite to the grating direction of the second coupled-out grating.

[0016] The optical waveguide structure provided in this application embodiment, by setting a second waveguide, a second coupling grating, and a second coupling grating, can make the grating direction of the second coupling grating and the grating direction of the second coupling grating form an angle with respect to the first direction. This can reduce the angle of offset towards the central axis of the optical waveguide structure during the process of sub-image light with a second wavelength range being transmitted from the second coupling grating to the second coupling grating. In other words, it can reduce the offset angle during the process of sub-image light with the same or different wavelength ranges being transmitted from the second coupling grating to the second coupling grating. Thus, without affecting the overall volume of the optical waveguide structure, the field of view in the vertical direction perpendicular to the first direction can be increased.

[0017] In one embodiment, the third included angle θ3 satisfies: -15°≤θ3<0°, 0°<θ3≤15°; the fourth included angle θ4 satisfies: -180°<θ4≤-165°, 165°≤θ4<180°.

[0018] In one embodiment, the refractive index of the second waveguide is in the range of 1.3-2.5.

[0019] In one embodiment, the length of the grating period of the second coupled grating ranges from 0.1 μm to 10 μm; the length of the grating period of the second coupled grating ranges from 0.1 μm to 10 μm.

[0020] In one embodiment, the second coupled grating is either an amplitude grating or a phase grating; the second coupled grating is either an amplitude grating or a phase grating.

[0021] In one embodiment, the optical waveguide structure further includes a plurality of waveguides stacked on the first waveguide, and each waveguide has an insertion grating and an output grating disposed on its surface away from the first waveguide, the insertion grating and the output grating being arranged along the first direction; different waveguides are used to receive and guide sub-image light with the same wavelength range or different wavelength ranges to propagate along the first direction.

[0022] The grating direction of each of the coupled gratings has a non-zero angle relative to the first direction; the grating direction of each of the coupled gratings also has a non-zero angle relative to the first direction; the grating direction of each of the coupled gratings is opposite to the grating direction of each of the coupled gratings.

[0023] In one embodiment, the refractive index of the first waveguide is in the range of 1.3-2.5.

[0024] In one embodiment, the length of the grating period of the first coupled-in grating ranges from 0.1 μm to 10 μm; the length of the grating period of the first coupled-out grating ranges from 0.1 μm to 10 μm.

[0025] In one embodiment, the first coupled-in grating is either an amplitude grating or a phase grating; the first coupled-out grating is either an amplitude grating or a phase grating.

[0026] A second aspect of this application provides an augmented reality display device, comprising:

[0027] A display module, wherein the display module is used to emit image light; and

[0028] The optical waveguide structure described in any of the above embodiments is used to receive the image light.

[0029] In one embodiment, the image light includes multiple sub-image lights, each with a different wavelength range.

[0030] The augmented reality display device provided in this application embodiment, by setting the optical waveguide structure described in any of the above embodiments, has the grating direction of the first coupled grating opposite to that of the first coupled grating, and the first angle between the grating direction of the first coupled grating and the first angle between the grating direction of the first coupled grating and the first angle between the grating direction of the first coupled grating and the first angle between the grating direction of the first coupled grating and the first coupled grating having the first angle relative to the first direction. This reduces the angle between the grating direction of the first coupled grating and the grating direction of the first coupled grating and the first coupled grating having the first wavelength range and the light traveling from the first coupled grating to the first coupled grating towards the optical waveguide structure. The angle of offset of the central axis can reduce the offset angle of the sub-image light with the first wavelength range during the process of transmission from the first coupling grating to the first coupling grating. Thus, without affecting the overall volume of the optical waveguide structure, the field of view in the vertical direction perpendicular to the first direction can be increased. By increasing the field of view in the vertical direction perpendicular to the first direction, the user's eye can receive the sub-image light with the first wavelength range in the vertical direction. This allows the user's eye to see the displayed image more completely when moving in the vertical direction, thereby enhancing the display effect without affecting the overall volume of the augmented reality display device. Attached Figure Description

[0031] Figure 1 is a schematic diagram of an optical waveguide structure according to an embodiment of this application.

[0032] Figure 2 is a schematic diagram of the optical path of an optical waveguide structure according to an embodiment of this application.

[0033] Figure 3 is a schematic diagram of the first included angle and the second included angle according to an embodiment of this application.

[0034] Figure 4 is a spatial angular diagram of the grating direction of the first coupled-in grating and the grating direction of the first coupled-out grating according to an embodiment of this application.

[0035] Figure 5 is a schematic diagram of a pair of proportional optical waveguide structures of this application.

[0036] Figure 6 is a spatial angular diagram of the grating direction of the input grating and the grating direction of the output grating of a pair of proportional gratings in this application.

[0037] Figure 7 is a schematic diagram of the third and fourth included angles according to an embodiment of this application.

[0038] Figure 8 is a schematic diagram of an optical waveguide structure comprising multiple waveguides in one embodiment of this application.

[0039] Figure 9 is a schematic diagram of the optical path of an exposure system according to an embodiment of this application.

[0040] Figure 10 is a schematic diagram of an augmented reality display device according to an embodiment of this application.

[0041] Key component symbols: Optical waveguide structure 100; First waveguide 1; First surface 11; Second surface 12; Waveguide 2; Coupled-in grating 21; Coupled-out grating 23; First coupled-in grating 3; First coupled-out grating 4; Second waveguide 5; Third surface 51; Fourth surface 52; Second coupled-in grating 6; Second coupled-out grating 7; Grating directions K1, K2, K3, K4, Kn1, Kn2; Exposure optical path 700; Light source S1, S2; Grating film 71; Base 73; Beam splitter 74; Augmented reality display device 900; Display module 91; Image light L0; Sub-image light L00; Sub-image light with a first wavelength range L1; Sub-image light with a second wavelength range L2; Collimation module 93; First direction X; First included angle.θ1 Second included angle θ2 Third included angle θ3 Fourth included angle θ4 Offset angle θ Vector included angle θr Human eye visible area E

[0042] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0043] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0044] It should be noted that when a component is referred to as being "fixed to" or "mounted to" another component, it can be directly on the other component or there may be an intervening component. When a component is considered to be "set on" another component, it can be directly set on the other component or there may be an intervening component. The term "and / or" as used herein includes all and any combination of one or more of the associated listed items. The terminology used in this application's specification is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0045] To further illustrate the technical means and effects adopted by this application in achieving its intended purpose, the following detailed description of this application is provided in conjunction with the accompanying drawings and preferred embodiments.

[0046] Referring to Figures 1 and 2, the optical waveguide structure 100 of this embodiment includes a first waveguide 1, a first coupling grating 3, a first coupling grating 4, a second waveguide 5, a second coupling grating 6, and a second coupling grating 7. The first coupling grating 3 and the first coupling grating 4 are spaced apart on one side surface of the first waveguide 1. The second waveguide 5 is attached to the side of the first coupling grating 3 and the first coupling grating 4 away from the first waveguide 1. The second coupling grating 6 and the second coupling grating 7 are spaced apart on the side surface of the second waveguide 5 away from the first waveguide 1.

[0047] The first waveguide 1 is generally plate-shaped and has opposing first surfaces 11 and second surfaces 12, with the first surfaces 11 and 12 having generally rectangular outer contours. The first waveguide 1 extends along a first direction X, that is, the long side of the first surface 11 or the second surface 12 extends along the first direction X. The material of the first waveguide 1 is any one of transparent glass and plastic, such as any one of polyethylene terephthalate (PET), polycarbonate (PC), and polymethyl methacrylate (PMMA), without limitation in this application. The refractive index of the first waveguide 1 is in the range of 1.3-2.5, for example, the refractive index of the first waveguide 1 can be any value in the ranges of 1.3-1.5, 1.5-1.7, 1.7-1.9, 1.9-2.1, 2.1-2.3, and 2.3-2.5, without limitation in this application.

[0048] The first waveguide 1 is used to receive and guide a portion of the image light L0 incident from the first coupling grating 3 to propagate along the first direction X. Specifically, the first waveguide 1 is used to receive and guide a sub-image light L1 with a first wavelength range incident from the first coupling grating 3 to propagate along the first direction X. In this embodiment, the image light L0 includes multiple sub-image lights, each with a different wavelength range. Specifically, the image light L0 includes sub-image lights L1 and L2 with different wavelength ranges. For example, the sub-image light L1 with the first wavelength range can be red light, and the sub-image light L2 with the second wavelength range can be blue light. The first wavelength range can be 760nm-622nm, and the second wavelength range can be 450nm-435nm. In other embodiments, the image light L0 can also be monochromatic light, that is, the wavelength ranges of the sub-image light L1 and the sub-image light L2 are the same. This application does not impose any limitations. The first waveguide 1 is used to receive and guide the sub-image light L1 with a first wavelength range incident from the first coupling grating 3, and the second waveguide 5 is used to receive and guide the sub-image light L2 with a second wavelength range incident from the second coupling grating 6. In other embodiments, the image light L0 may also include a variety of sub-image lights with different wavelength ranges, and the first waveguide 1 and the second waveguide 5 may be used to receive and guide the sub-image light with one or more wavelength ranges incident from the first coupling grating 3 or the second coupling grating 6. This application does not impose any limitations.

[0049] Please refer to Figures 2 and 3 together. The first coupling grating 3 is disposed on the first surface 11 of the first waveguide 1. Specifically, the first coupling grating 3 can be bonded to the first surface 11 of the first waveguide 1 using optical adhesive. The first coupling grating 3 is used to receive and couple sub-image light L1 with a first wavelength range into the first waveguide 1. Specifically, when image light L0 including different wavelength ranges is incident on the first coupling grating 3, since the wavelength range of the sub-image light L1 with the first wavelength range is different from the wavelength range of the sub-image light L2 with the second wavelength range, the sub-image light L1 with the first wavelength range is incident on the first coupling grating 3, and the first coupling grating 3 receives and couples the sub-image light L1 with the first wavelength range into the first waveguide 1, while the sub-image light L2 with the second wavelength range passes through the first coupling grating 3 and is incident on the second coupling grating 6. In other embodiments, when the wavelength ranges of sub-image light L1 and sub-image light L2 are the same, a portion of image light L0 (sub-image light L1) is incident on the first coupling grating 3. The first coupling grating 3 receives the sub-image light L1 and couples it into the first waveguide 1. The sub-image light L1 is then coupled out to the human eye through the first coupling grating 4. A portion of image light L0 (sub-image light L2) is incident on the second coupling grating 6 through the first coupling grating 3. The second coupling grating 6 receives the sub-image light L2 and couples it into the second waveguide 5. The sub-image light L2 is then coupled out to the human eye through the second coupling grating 7. The light intensity incident on the first waveguide 1 and the second waveguide 5 can be adjusted by adjusting the diffraction efficiency of the first coupling grating 3, thereby adjusting the light intensity of the light emitted from the first coupling grating 4 and the second coupling grating 7, and thus improving the uniformity of the light intensity emitted from the optical waveguide structure 100.

[0050] Specifically, the first coupling grating 3 is a holographic diffraction grating, such as any one of an amplitude-type grating and a phase-type grating. The length of the grating period of the first coupling grating 3 ranges from 0.1 μm to 10 μm. For example, the length of the grating period of the first coupling grating 3 can be any value within the ranges of 0.1 μm-1 μm, 1 μm-3 μm, 3 μm-5 μm, 5 μm-7 μm, 7 μm-8 μm, and 8 μm-10 μm, and this application does not impose any restrictions.

[0051] In this embodiment, the first coupling grating 3 is a grating with periodic alternating bright and dark stripes on its surface; in other embodiments, the first coupling grating 3 may also be other gratings with periodic structures, or the first coupling grating 3 may be a grating with periodic changes in refractive index, and this application does not impose any limitations. Specifically, the plurality of alternating bright and dark stripes of the first coupling grating 3 are approximately parallel, and the grating direction is perpendicular to the extension direction of the stripes, which also refers to the direction of the grating arrangement on the first coupling grating 3, and is also the periodic direction of the grating, that is, the direction of the grating extension order, which is also the vector direction of the grating projection on the first surface 11; the grating direction K1 of the first coupling grating 3 has a first angle θ1 relative to the first direction X. The first included angle θ1 satisfies: -15° ≤ θ1 < 0°, 0° < θ1 ≤ 15°; for example, the first included angle θ1 can be any value within the ranges of -15° ≤ θ1 ≤ -10°, -10° ≤ θ1 < 0°, 0° < θ1 ≤ 10°, and 10° ≤ θ1 ≤ 15°, and this application does not impose any restrictions. By setting the first included angle θ1 to satisfy the above range, while offsetting the offset of a portion of the sub-image light L1 with the first wavelength range at the emission position of the first coupling grating 4 relative to the central axis of the first waveguide 1, it is possible to prevent the sub-image light L1 with the first wavelength range from being excessively offset, thereby preventing offset errors.

[0052] The first coupling-in grating 3 and the first coupling-out grating 4 are arranged along the first direction X. The first coupling-out grating 4 is disposed on the first surface 11 at a distance from the first coupling-in grating 3. The first coupling-out grating 4 can be bonded to the first surface 11 of the first waveguide 1 using optical adhesive. The first coupling-out grating 4 is used to receive and couple out sub-image light L1 with a first wavelength range emitted from the first waveguide 1. Specifically, the first coupling-out grating 4 is a holographic diffraction grating, for example, the first coupling-out grating 4 can be any one of an amplitude-type grating and a phase-type grating.

[0053] In this embodiment, the first coupling grating 4 is a grating with periodic alternating bright and dark stripes on its surface; in other embodiments, the first coupling grating 4 may also be other gratings with periodic structures, or the first coupling grating 4 may be a grating with periodic changes in refractive index, and this application does not impose any limitations. The length of the grating period of the first coupling grating 4 ranges from 0.1 μm to 10 μm. For example, the length of the grating period of the first coupling grating 4 can be any value within the ranges of 0.1 μm-1 μm, 1 μm-3 μm, 3 μm-5 μm, 5 μm-7 μm, 7 μm-8 μm, and 8 μm-10 μm, and this application does not impose any limitations.

[0054] The grating direction K2 of the first output grating 4 is parallel to the grating direction K1 of the first input grating 3, and the grating direction K1 of the first input grating 3 is opposite to the grating direction K2 of the first output grating 4. The grating direction K2 of the first output grating 4 has a second included angle θ2 relative to the first direction X. The second included angle θ2 satisfies: -180°<θ2≤-165°, 165°≤θ2<180°; for example, the second included angle θ2 can be any value in the range of -180°<θ2≤-170°, -170°≤θ2≤-165°, 165°≤θ2≤170°, and 170°≤θ2<180°, as long as the grating direction K2 of the first output grating 4 is parallel to the grating direction K1 of the first input grating 3, that is, the magnitude of the first included angle θ1 and the magnitude of the second included angle θ2 are equal. This application does not impose any restrictions. By setting the second included angle θ2 to satisfy the above range, it is possible to offset the offset of a portion of the sub-image light L1 with the first wavelength range at the emission position of the first coupling grating 4 relative to the central axis of the first waveguide 1, while also preventing the sub-image light L1 with the first wavelength range from being excessively offset, thereby generating an offset error.

[0055] To ensure that the grating direction K2 of the first output grating 4 is parallel to the grating direction K1 of the first input grating 3, when the first included angle θ1 is negative, the second included angle θ2 is positive; in other embodiments, when the first included angle θ1 is positive, the second included angle θ2 can also be negative, and this application does not impose any restrictions.

[0056] Specifically, both the first included angle θ1 and the second included angle θ2 are non-zero, meaning that the grating direction K1 of the first coupled-in grating 3 has an angle relative to the first direction X, and the grating direction K2 of the first coupled-out grating 4 has an angle relative to the first direction X. Please refer to Figure 4, which is a spatial angular diagram of the grating direction K1 of the first coupled-in grating 3 and the grating direction K2 of the first coupled-out grating 4 in an embodiment of this application. Figure 4 schematically illustrates the cases where the first included angle θ1 is 3° or the second included angle θ2 is -177°. The grating direction K1 of the first coupled-in grating 3 is parallel to the grating direction K2 of the first coupled-out grating 4, meaning that the magnitudes of the first included angle θ1 and the second included angle θ2 are equal. The angle between the extension direction of the first coupled-in grating 3 grating direction K1 and the extension direction of the first coupled-out grating 4 grating direction K2 in the first direction X is defined as the vector angle θr.

[0057] Please refer to Figures 5 and 6 together. In a pair of proportional waveguide structures, the first angle θ1 and the second angle θ2 are both zero. That is, the grating direction of the coupled grating is parallel to the first direction X, and the grating direction of the coupled grating is parallel to the first direction X. When light travels from the coupled grating to the coupled grating, the light gradually shifts away from the central axis of the waveguide structure. In other words, the exit position of the light will have an offset angle θ relative to the first direction X. Please refer to Figure 6. Figure 6 is a spatial diagram of the angles of the grating directions of the coupled grating and the coupled grating in the comparative example. In the comparative example, since the first angle θ1 and the second angle θ2 are both zero, the vector angle θr between the extension direction of the coupled grating and the extension direction of the coupled grating and the first direction X is also 0. Due to the existence of the offset angle θ, light rays emitted in the vertical direction perpendicular to the first direction X cannot be received in the visible area E of the human eye.

[0058] Please refer to Figures 1 and 2 again. The optical waveguide structure 100 provided in this embodiment of the application, by setting the first angle θ1 between the grating direction K1 of the first coupling grating 3 and the first angle θ2 between the grating direction K2 of the first coupling grating 4 and the first direction X, is not zero. That is, the angles between the extension directions of the grating directions of the first coupling grating 3 and the first coupling grating 4 and the first direction X are not zero, i.e., the vector angle θr is also not zero. When the sub-image light L1 with the first wavelength range gradually shifts away from the central axis of the optical waveguide structure 100 in different directions, that is, when the sub-image light L1 with the first wavelength range generates a shift angle θ relative to the first direction X at the emission position of the first coupling grating 4, due to the... The presence of the angle θr can offset part of the effect of the offset angle θ that the sub-image light L1 with the first wavelength range will have at the emission position of the first coupling grating 4 relative to the first direction X. That is, the actual offset angle of the sub-image light L1 with the first wavelength range at the emission position of the first coupling grating 4 relative to the first direction X is θ-θr. The magnitude of θ-θr is smaller than the field of view angle in the vertical direction perpendicular to the first direction X received by the human eye's visible area E. This allows the human eye's visible area E to receive the sub-image light L1 with the first wavelength range emitted in the vertical direction perpendicular to the first direction X. Thus, without affecting the overall volume of the optical waveguide structure 100, the field of view angle in the vertical direction perpendicular to the first direction X can be increased.

[0059] Please refer to Figures 1, 2, and 7 together. The second waveguide 5 is generally plate-shaped and has opposing third surfaces 51 and fourth surfaces 52. The third surfaces 51 and fourth surfaces 52 have generally rectangular outer contours. The second waveguide 5 is attached to one side of the first waveguide 1 and covers the first coupling grating 3 and the first coupling grating 4; that is, the fourth surface 52 is attached to the side of the first coupling grating 3 and the first coupling grating 4 away from the first waveguide 1. The second waveguide 5 also extends along the first direction X, that is, the long side of the third surface 51 or the fourth surface 52 extends along the first direction X. The second waveguide 5 is used to receive and guide the sub-image light L2 with a second wavelength range incident from the second coupling grating 6. The material of the second waveguide 5 is any one of transparent glass and plastic, such as any one of PET, PC, and PMMA, which is not limited in this application. The refractive index of the second waveguide 5 is in the range of 1.3-2.5. For example, the refractive index of the second waveguide 5 can be any value in the range of 1.3-1.5, 1.5-1.7, 1.7-1.9, 1.9-2.1, 2.1-2.3 and 2.3-2.5. This application does not impose any restrictions.

[0060] The second coupling grating 6 is disposed on the third surface 51. Specifically, the second coupling grating 6 can be bonded to the third surface 51 of the second waveguide 5 using optical adhesive. The second coupling grating 6 is used to receive and couple sub-image light L2 with a second wavelength range into the second waveguide 5. Specifically, when image light L0 with different wavelength ranges is incident on the second coupling grating 6, since the wavelength range of sub-image light L1 with a first wavelength range is different from the wavelength range of sub-image light L2 with a second wavelength range, sub-image light L1 with a first wavelength range is incident on the first coupling grating 3, while sub-image light L2 with a second wavelength range passes through the first coupling grating 3 and is incident on the second coupling grating 6. In other embodiments, when the wavelength ranges of sub-image light L1 and sub-image light L2 are the same, a portion of image light L0 (sub-image light L1) is incident on the first coupling grating 3. The first coupling grating 3 receives the sub-image light L1 and couples it into the first waveguide 1. The sub-image light L1 is then coupled out to the human eye through the first coupling grating 4. A portion of image light L0 (sub-image light L2) is incident on the second coupling grating 6 through the first coupling grating 3. The second coupling grating 6 receives the sub-image light L2 and couples it into the second waveguide 5. The sub-image light L2 is then coupled out to the human eye through the second coupling grating 7. The light intensity incident on the first waveguide 1 and the second waveguide 5 can be adjusted by adjusting the diffraction efficiency of the first coupling grating 3, thereby adjusting the light intensity of the light emitted from the first coupling grating 4 and the second coupling grating 7, and thus improving the uniformity of the light intensity emitted from the optical waveguide structure 100.

[0061] Specifically, the second coupling grating 6 is a holographic diffraction grating. For example, the second coupling grating 6 can be any one of an amplitude-type grating and a phase-type grating. In this embodiment, the second coupling grating 6 is a grating with periodic alternating bright and dark stripes on its surface. In other embodiments, the second coupling grating 6 can also be other gratings with periodic structures, or the second coupling grating 6 can be a grating with a periodic change in refractive index. This application does not impose any limitations. The length of the grating period of the second coupling grating 6 ranges from 0.1 μm to 10 μm. For example, the length of the grating period of the second coupling grating 6 can be any value within the ranges of 0.1 μm-1 μm, 1 μm-3 μm, 3 μm-5 μm, 5 μm-7 μm, 7 μm-8 μm, and 8 μm-10 μm. This application does not impose any limitations.

[0062] The grating direction K3 of the second input grating 6 is opposite to the grating direction K4 of the second output grating 7. The grating direction K3 of the second input grating 6 has a third angle θ3 relative to the first direction X. The third angle θ3 satisfies: -15°≤θ3<0°, 0°<θ3≤15°; for example, the third angle θ3 can be any value in the range of -15°≤θ3≤-10°, -10°≤θ3<0°, 0°<θ3≤10°, and 10°≤θ3≤15°, and this application does not impose any restrictions.

[0063] The second input grating 6 and the second output grating 7 are arranged along the first direction X. The second output grating 7 is spaced apart from the second input grating 6 on the third surface 51. Specifically, the second output grating 7 can be bonded to the third surface 51 of the second waveguide 5 using optical adhesive. The second output grating 7 is used to receive and couple out the sub-image light L2 emitted from the second waveguide 5. Specifically, the second output grating 7 is a holographic diffraction grating, which can be either an amplitude-type grating or a phase-type grating. For example, the second output grating 7 can be an amplitude-type grating. In this embodiment, the second output grating 7 is a grating with periodic alternating bright and dark stripes on its surface. In other embodiments, the second output grating 7 can also be other gratings with periodic structures, or the second output grating 7 can be a grating with a periodic change in refractive index. This application is not limited to these embodiments. The length of the grating period of the second output grating 7 ranges from 0.1 μm to 10 μm. For example, the length of the grating period of the second coupling grating 7 can be any value in the range of 0.1μm-1μm, 1μm-3μm, 3μm-5μm, 5μm-7μm, 7μm-8μm and 8μm-10μm, and this application does not impose any restrictions.

[0064] The grating direction K4 of the second output grating 7 has a fourth included angle θ4 relative to the first direction X. The fourth included angle θ4 satisfies: -180° < θ4 ≤ -165°, 165° ≤ θ4 < 180°; for example, the fourth included angle θ4 can be any value in the range of -180° < θ4 ≤ -170°, -170° ≤ θ4 ≤ -165°, 165° ≤ θ4 ≤ 170°, and 170° ≤ θ4 < 180°, as long as the grating direction K4 of the second output grating 7 is opposite to the grating direction K3 of the second input grating 6, and the signs of the fourth included angle θ4 and the second included angle θ2 are opposite, that is, the grating direction K1 of the first input grating 3 and the grating direction K2 of the first output grating 4 are opposite, which is not limited in this application. To prevent interference between the sub-image light L1 emitted from the first coupling grating 4 and the sub-image light L2 emitted from the second coupling grating 7, in this embodiment, the first included angle θ1 is negative, the second included angle θ2 is positive, the third included angle θ3 is positive, and the fourth included angle θ4 is negative. In other embodiments, the first included angle θ1 is positive, the second included angle θ2 is negative, the third included angle θ3 is negative, and the fourth included angle θ4 is positive; this application does not impose any limitations.

[0065] Please refer to Figures 2, 4, and 7 together. Similarly, the angle between the extension direction of the second input grating 6 and the extension direction of the second output grating 7 and the first direction X is defined as the vector angle θr. The optical waveguide structure 100 provided in this embodiment sets the third angle θ3 of the second input grating 6 relative to the first direction X and the fourth angle θ4 of the second output grating 7 relative to the first direction X to be non-zero. That is, the angle between the extension direction of the second input grating 6 and the extension direction of the second output grating 7 and the first direction X is not 0, i.e., the vector angle θr is also not 0. When the sub-image light L2 with a second wavelength range gradually shifts away from the central axis of the optical waveguide structure 100, i.e., when the sub-image light L2 with a second wavelength range has an offset angle θ relative to the first direction X at the exit position of the second output grating 7, the vector angle θr... The existence of this technology can offset the effect of a partial offset angle θ that occurs at the emission position of the sub-image light L2 with the second wavelength range relative to the first direction X at the second coupling grating 7. That is, the actual offset angle of the sub-image light L2 with the second wavelength range at the emission position of the second coupling grating 7 relative to the first direction X is θ-θr. The magnitude of θ-θr is smaller than the field of view angle in the vertical direction perpendicular to the first direction X received by the human eye's visible area E. This allows the human eye's visible area E to receive the sub-image light L2 with the second wavelength range emitted in the vertical direction perpendicular to the first direction X. Thus, without affecting the overall volume of the optical waveguide structure 100, the field of view angle in the vertical direction perpendicular to the first direction X can be increased.

[0066] The optical waveguide structure 100 provided in this application embodiment, by setting a second waveguide 5, a second coupling grating 6, and a second coupling grating 7, can make the grating direction K3 of the second coupling grating 6 and the grating direction K4 of the second coupling grating 7 have an angle relative to the first direction X. This can reduce the angle of offset towards the central axis of the optical waveguide structure 100 during the process of the sub-image light L2 with the second wavelength range being transmitted from the second coupling grating 6 to the second coupling grating 7. That is, it can reduce the offset angle θ of the sub-image light (sub-image light L1 with the first wavelength range and sub-image light L2 with the second wavelength range, the first wavelength range and the second wavelength range being the same or different) being transmitted from the second coupling grating 6 to the second coupling grating 7. Thus, without affecting the overall volume of the optical waveguide structure 100, the field of view in the vertical direction perpendicular to the first direction X can be increased.

[0067] Referring to Figure 8, in one embodiment, the optical waveguide structure 100 may further include a plurality of waveguides 2 stacked on the first waveguide 1. Each waveguide 2 has a coupling grating 21 and a coupling grating 23 disposed on its surface away from the first waveguide 1. The coupling grating 21 and the coupling grating 23 are arranged along the first direction X. Different waveguides 2 are used to receive and guide sub-image light L00 with different wavelength ranges to propagate along the first direction X.

[0068] Each of the coupled-in gratings 21 has a non-zero angle Kn1 relative to the first direction X. Each of the coupled-out gratings 23 also has a non-zero angle Kn2 relative to the first direction X. The grating directions Kn1 and Kn2 of each coupled-in grating 21 are opposite. The optical waveguide structure 100 provided in this application embodiment, through multiple waveguides 2 stacked on the first waveguide 1, allows the grating direction Kn1 of each coupled grating 21 and the grating direction Kn2 of each coupled grating 23 to have a non-zero angle relative to the first direction X. This can reduce the angle of offset towards the central axis of the optical waveguide structure 100 during the process of sub-image light L00 with different wavelength ranges being transmitted from coupled grating 21 to coupled grating 23. In other words, it can reduce the offset angle θ of sub-image light L00 with different wavelength ranges being transmitted from coupled grating 21 to coupled grating 23. Thus, without affecting the overall volume of the optical waveguide structure 100, the field of view in the vertical direction perpendicular to the first direction X can be increased.

[0069] In other embodiments, if the image light L0 only includes a sub-image light L0 with a wavelength range, the optical waveguide structure 100 may only include a first waveguide 1, a first coupling grating 3, and a first coupling grating 4, and this application does not impose any restrictions.

[0070] Please refer to Figures 1 and 9 together. Figure 9 shows an exposure optical path 700 used to fabricate any one of the following holographic diffraction gratings in the embodiments of this application: the first coupling grating 3 and the first coupling grating 4, or the second coupling grating 6 and the second coupling grating 7. The light source S1 or S2 passes through a beam splitter 74 sequentially to become two sub-beams of equal intensity. Each sub-beam is reflected by a mirror and then incident on the grating film 71. The two sub-beams interfere on the grating film 71, forming interference fringes. Since the base 73 fixing the grating film 71 is rotatable, the parallel angle of the interference fringes formed on the grating film 71 can be adjusted, i.e., the grating direction of the formed holographic diffraction grating can be adjusted. This allows for simultaneous exposure to obtain the first coupling grating 3 and the first coupling grating 4, or the second coupling grating 6 and the second coupling grating 7.

[0071] The optical waveguide structure 100 provided in this application embodiment, by setting a first coupling grating 3 and a first coupling grating 4, wherein the grating direction K1 of the first coupling grating 3 is parallel to the grating direction K2 of the first coupling grating 4, and the grating directions K1 of the first coupling grating 3 and K2 of the first coupling grating 4 are opposite, and the first angle θ1 of the grating direction K1 of the first coupling grating 3 relative to the first direction X and the second angle θ2 of the grating direction K2 of the first coupling grating 4 relative to the first direction X are not zero, can increase the size of the angle between the grating direction K2 of the first coupling grating 3 or the first coupling grating 4 and the first direction X, thereby reducing the direction of the sub-image light L1 with the first wavelength range from the first coupling grating 3 to the first coupling grating 4. The angle of offset of the central axis of the waveguide structure 100 can reduce the offset angle of the sub-image light L1 with the first wavelength range during its transmission from the first coupling grating 3 to the first coupling grating 4. Thus, without affecting the overall volume of the waveguide structure 100, the field of view in the vertical direction perpendicular to the first direction X can be increased. When the waveguide structure 100 is applied to the augmented reality display device 900, by increasing the field of view in the vertical direction perpendicular to the first direction X, the user's eye can receive the sub-image light L1 with the first wavelength range in the vertical direction. This allows the user's eye to see the displayed image when moving in the vertical direction, thereby enhancing the display effect without affecting the overall volume of the augmented reality display device 900.

[0072] Referring to Figures 2 and 10, the augmented reality display device 900 of this application embodiment includes a display module 91 and an optical waveguide structure 100 of any of the above embodiments. The display module 91 is used to emit image light L0, which contains multiple sub-image lights, each with a different wavelength range. Specifically, the image light L0 includes the wavelength range of sub-image light L1 with a first wavelength range and sub-image light L2 with a second wavelength range. For example, sub-image light L1 with the first wavelength range can be red light, and sub-image light L2 with the second wavelength range can be blue light. In this embodiment, since the wavelength ranges of sub-image light L1 with the first wavelength range and sub-image light L2 with the second wavelength range are different, sub-image light L1 with the first wavelength range is incident on the first coupling grating 3. The first coupling grating 3 receives and couples sub-image light L1 with the first wavelength range into the first waveguide 1, while sub-image light L2 with the second wavelength range passes through the first coupling grating 3 and is incident on the second coupling grating 6. In other embodiments, when the wavelength ranges of sub-image light L1 and sub-image light L2 are the same, a portion of image light L0 (sub-image light L1) is incident on the first coupling grating 3, the first coupling grating 3 receives the sub-image light L1 and couples it into the first waveguide 1, and the sub-image light L1 is then coupled out to the human eye through the first coupling grating 4; a portion of image light L0 (sub-image light L2) is incident on the second coupling grating 6 through the first coupling grating 3, the second coupling grating 6 receives the sub-image light L2 and couples it into the second waveguide 5, and the sub-image light L2 is then coupled out to the human eye through the second coupling grating 7.

[0073] Specifically, the display module 91 can be a display using DLP (Digital Light Processor) display mode, or it can be a light-emitting diode panel, such as a miniature organic light-emitting diode panel or a miniature light-emitting diode panel; this application does not impose any limitations. The augmented reality display device 900 also includes a collimation module 93, which is disposed on the light-emitting side of the display module 91. The collimation module 93 is used to converge the image light L0 and transmit the image light L0 to the optical waveguide structure 100.

[0074] The augmented reality display device 900 provided in this application embodiment, by setting an optical waveguide structure 100 in any of the above embodiments, wherein the first angle θ1 between the grating direction K1 of the first coupled grating 3 and the first angle θ2 between the grating direction K2 of the first coupled grating 4 and the first direction X are not zero, and the grating directions K1 of the first coupled grating 3 and K2 of the first coupled grating 4 are opposite, can make the grating directions K1 of the first coupled grating 3 and K2 of the first coupled grating 4 have an angle with respect to the first direction X, thereby reducing the distance of the sub-image light L1 with the first wavelength range from the first wavelength range. The angle at which the input grating 3 deflects towards the central axis of the optical waveguide structure 100 during the transmission of light from the first input grating 3 to the first output grating 4 can reduce the deflection angle of the sub-image light L1 with the first wavelength range during the transmission from the first input grating 3 to the first output grating 4. This increases the field of view in the vertical direction perpendicular to the first direction X. By increasing the field of view in the vertical direction perpendicular to the first direction X, the user's eye can receive the sub-image light L1 with the first wavelength range in the vertical direction, so that the user's eye can see the displayed image when moving in the vertical direction. This enhances the display effect without affecting the overall volume.

[0075] The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of this application should not depart from the spirit and scope of the technical solutions of this application.

Claims

1. An optical waveguide structure, characterized in that, include: A first waveguide having opposing first and second surfaces for receiving and guiding sub-image light with a first wavelength range to propagate along a first direction; A first coupling grating, disposed on the first surface, is used to receive and couple the sub-image light having a first wavelength range into the first waveguide. The grating direction of the first coupling grating has a first angle θ1 relative to the first direction. A first output grating, together with a first input grating, is disposed on the first surface and arranged along the first direction. The first output grating is used to receive and couple out the sub-image light having a first wavelength range emitted from the first waveguide. The grating direction of the first output grating has a second angle θ2 relative to the first direction. Wherein, the first included angle θ1 and the second included angle θ2 are not zero, and the grating direction of the first coupled-in grating is opposite to the grating direction of the first coupled-out grating.

2. The optical waveguide structure as described in claim 1, characterized in that, The first included angle θ1 satisfies: -15°≤θ1<0°, 0°<θ1≤15°; The second included angle θ2 satisfies: -180°<θ2≤-165°, 165°≤θ2<180°.

3. The optical waveguide structure as described in claim 1, characterized in that, The optical waveguide structure also includes a second waveguide, a second coupling grating, and a second coupling out grating; The second waveguide has opposing third and fourth surfaces, and is attached to one side of the first waveguide and covers the first coupling grating and the first coupling grating; the second waveguide is used to receive and guide sub-image light with a second wavelength range to propagate along the first direction; A second coupling grating is disposed on the third surface for receiving and coupling the sub-image light with a second wavelength range into the second waveguide. The grating direction of the second coupling grating has a third angle θ3 relative to the first direction. The second output grating and the second input grating are disposed on the third surface and are arranged along the first direction with the second input grating. The second output grating is used to receive and couple out the sub-image light with the second wavelength range emitted from the second waveguide. The grating direction of the second output grating has a fourth included angle θ4 relative to the first direction. Wherein, the third included angle θ3 and the fourth included angle θ4 are not zero, and the grating direction of the second coupled-in grating is opposite to the grating direction of the second coupled-out grating.

4. The optical waveguide structure as described in claim 3, characterized in that, The third included angle θ3 satisfies: -15°≤θ3<0°, 0°<θ3≤15°; the fourth included angle θ4 satisfies: -180°<θ4≤-165°, 165°≤θ4<180°.

5. The optical waveguide structure as described in claim 3, characterized in that, The refractive index of the second waveguide ranges from 1.3 to 2.

5.

6. The optical waveguide structure as described in claim 3, characterized in that, The length of the grating period of the second coupled-in grating ranges from 0.1 μm to 10 μm; the length of the grating period of the second coupled-out grating ranges from 0.1 μm to 10 μm.

7. The optical waveguide structure as described in claim 3, characterized in that, The second coupled-in grating is either an amplitude grating or a phase grating; the second coupled-out grating is either an amplitude grating or a phase grating.

8. The optical waveguide structure as described in claim 1, characterized in that, The optical waveguide structure further includes multiple waveguides stacked on the first waveguide. Each waveguide has an input grating and an output grating on its surface away from the first waveguide. The input grating and the output grating are arranged along the first direction. Different waveguides are used to receive and guide sub-image light with the same wavelength range or different wavelength ranges to propagate along the first direction. Each of the coupled-in gratings has a non-zero angle relative to the first direction in its grating direction; each of the coupled-out gratings also has a non-zero angle relative to the first direction in its grating direction; the grating directions of each coupled-in grating and each coupled-out grating are opposite.

9. The optical waveguide structure as described in claim 1, characterized in that, The refractive index of the first waveguide is in the range of 1.3-2.

5.

10. The optical waveguide structure as described in claim 1, characterized in that, The length of the grating period of the first coupled-in grating ranges from 0.1 μm to 10 μm; the length of the grating period of the first coupled-out grating ranges from 0.1 μm to 10 μm.

11. The optical waveguide structure as described in claim 1, characterized in that, The first coupled-in grating is either an amplitude grating or a phase grating; the first coupled-out grating is either an amplitude grating or a phase grating.

12. An augmented reality display device, characterized in that, include: The display module is used to emit image light; as well as The optical waveguide structure according to any one of claims 1-11, wherein the optical waveguide structure is used to receive the image light.

13. The augmented reality display device as claimed in claim 12, characterized in that, The image light includes multiple sub-image lights, each with a different wavelength range.

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