Optical waveguide device and augmented reality display equipment

Abstract

The invention discloses an optical waveguide device and augmented reality display equipment, relates to the technical field of optics, and is used for solving the problem that an existing optical waveguide is obvious in color cast. The optical waveguide device comprises a waveguide substrate, a coupling-in structure, a coupling-out structure and a diffraction structure. The diffraction structure enables light in the waveguide substrate to generate diffraction turning, and diffraction light with different diffraction angles is generated; the waveguide substrate comprises at least two waveguide layers, any two adjacent waveguide layers comprise a first waveguide layer and a second waveguide layer, and the first waveguide layer and the second waveguide layer have an interface, so that the diffracted light is partially reflected when incident to the interface from the first waveguide layer and the second waveguide layer, or the diffracted light is partially reflected when incident to the interface from the first waveguide layer, and the diffracted light is partially reflected when incident to the interface from the second waveguide layer. When the diffracted light enters the interface from the second waveguide layer, part of the diffracted light is partially reflected, the other part of the diffracted light is totally reflected, and the reflectivity of the interface to the diffracted light is in an increasing trend along with the increase of the incident angle of the diffracted light. The color uniformity can be improved, and the color cast phenomenon is weakened.

Description

Technical Field

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

[0002] Augmented Reality (AR) technology is a technology that integrates computer-generated virtual information with the real environment. It can dynamically overlay virtual information onto the real world in real time, thereby enhancing users' perception and understanding of the real world.

[0003] An optical waveguide is an optical device used in augmented reality near-eye display devices. It can project virtual images directly into the user's eyes while ensuring that the user's view of the real world is not obstructed. From an optical principle perspective, optical waveguides are mainly divided into arrayed waveguides and diffractive waveguides. Different types of optical waveguides differ in performance, cost, and application scenarios. Currently, there are representative products of both types of optical waveguides on the market.

[0004] Arrayed waveguides utilize geometric optics principles, where light is coupled in, enlarged, and coupled out through refraction or reflection. Diffracted waveguides, on the other hand, utilize diffraction optics principles, where light is coupled in, enlarged, and coupled out through diffraction. Their advantages include high yield and good display clarity, which can be mass-produced using nanoimprint technology. However, their disadvantages include low luminous efficiency, significant color shift, and severe forward light leakage. Summary of the Invention

[0005] The purpose of this invention is to provide an optical waveguide device and an augmented reality display device that can improve color uniformity, reduce color shift, and help improve display quality.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] An optical waveguide device includes a waveguide substrate, a coupling structure, a coupling structure, and a diffraction structure;

[0008] The waveguide substrate is provided with at least one of the coupling structures, which are used to allow incident light to enter the waveguide substrate and propagate within the waveguide substrate.

[0009] The waveguide substrate is provided with at least one of the diffraction structures, which are used to diffract and redirect the propagating light in the waveguide substrate, so that the diffracted light with different diffraction angles propagates in the waveguide substrate and towards the coupling structure.

[0010] The waveguide substrate includes at least two waveguide layers. Any two adjacent waveguide layers include a first waveguide layer and a second waveguide layer. The first waveguide layer and the second waveguide layer have an interface, such that when the diffracted light propagating in the waveguide substrate is incident from the first waveguide layer to the interface between the first waveguide layer and the second waveguide layer, it is partially reflected, and when the diffracted light propagating in the waveguide substrate is incident from the second waveguide layer to the interface between the first waveguide layer and the second waveguide layer, it is partially reflected.

[0011] Alternatively, the first waveguide layer and the second waveguide layer have an interface, such that when the diffracted light propagating in the waveguide substrate is incident from the first waveguide layer to the interface between the first waveguide layer and the second waveguide layer, it undergoes partial reflection, and when the diffracted light propagating in the waveguide substrate is incident from the second waveguide layer to the interface between the first waveguide layer and the second waveguide layer, a portion of the diffracted light undergoes partial reflection and another portion of the diffracted light undergoes total internal reflection.

[0012] The reflectivity of the interface to the diffracted light increases with the increase of the incident angle of the diffracted light.

[0013] The waveguide substrate is provided with at least one of the coupling structures, which are used to cause the diffracted light propagating in the waveguide substrate to exit out of the waveguide substrate.

[0014] In some embodiments, the diffraction structure includes a first diffraction optical structure and a second diffraction optical structure;

[0015] The coupling structure is used to allow incident light to enter the waveguide substrate and propagate along a first dimension within the waveguide substrate to the first diffraction optical structure. The first diffraction optical structure is used to diffract the propagating light within the waveguide substrate, causing diffracted light with different diffraction angles to propagate within the waveguide substrate and then turn to propagate along a second dimension towards the second diffraction optical structure. The second diffraction optical structure is used to diffract and turn the diffracted light with different diffraction angles propagating within the waveguide substrate towards the coupling structure.

[0016] In some embodiments, the waveguide substrate further includes a first region and a second region, the first region and the second region of the waveguide substrate are spliced ​​together, the coupling structure and the first diffractive optical structure are disposed in the first region of the waveguide substrate, and the second diffractive optical structure and the coupling structure are disposed in the second region of the waveguide substrate;

[0017] The splicing interface between the first region and the second region is parallel to the first dimensional direction, or the angle between the splicing interface between the first region and the second region and the first dimensional direction is greater than 0° and less than 90°, so that the light propagating in the waveguide matrix is ​​deviated from the splicing interface between the first region and the second region and continues to propagate along the first dimensional direction after being diffracted by the first diffractive optical structure.

[0018] Alternatively, the splicing interface between the first region and the second region is not parallel to the first dimensional direction, and a first film layer is provided at the splicing interface between the first region and the second region, so that the light propagating in the waveguide substrate, after being diffracted by the first diffractive optical structure, continues to propagate along the first dimensional direction, and is totally internally reflected when it is incident on the splicing interface.

[0019] In some embodiments, the waveguide substrate further includes a first region and a second region, the first region and the second region of the waveguide substrate are spliced ​​together, the coupling structure and the first diffractive optical structure are disposed in the first region of the waveguide substrate, the second diffractive optical structure and the coupling structure are disposed in the second region of the waveguide substrate, and the splicing interface of the first region and the second region is not parallel to the thickness direction of the waveguide substrate.

[0020] In some embodiments, a dielectric film is disposed at the interface between the first waveguide layer and the second waveguide layer. The dielectric film is a dielectric film with a single refractive index, and the refractive index of the dielectric film is less than the refractive index of the first waveguide layer and the refractive index of the second waveguide layer. The dielectric film satisfies the condition of suppressed total internal reflection.

[0021] In some embodiments, a dielectric film layer is disposed at the interface between the first waveguide layer and the second waveguide layer, the dielectric film layer comprising at least two films with different refractive indices stacked together.

[0022] In some embodiments, the reflectivity of the interface to the diffracted light satisfies the following relationship with the incident angle of the diffracted light:

[0023] As the incident angle of the diffracted light propagating in the waveguide substrate at the interface increases, the rate of change of the reflectivity of the interface to the diffracted light changes from a slow increase to a rapid increase, and then from a rapid increase to a slow decrease.

[0024] In some embodiments, the refractive index of the first waveguide layer is less than that of the second waveguide layer, so that when the diffracted light propagating in the waveguide substrate is incident from the first waveguide layer to the interface between the first waveguide layer and the second waveguide layer, a portion of the diffracted light is partially reflected and another portion of the diffracted light is totally reflected when the diffracted light propagating in the waveguide substrate is incident from the second waveguide layer to the interface between the first waveguide layer and the second waveguide layer.

[0025] In some embodiments, when the diffracted light propagating in the waveguide substrate is incident from the second waveguide layer to the interface between the first waveguide layer and the second waveguide layer, the diffracted light undergoes partial reflection when the incident angle of the diffracted light is less than a preset angle, and the diffracted light undergoes total internal reflection when the incident angle of the diffracted light is greater than or equal to the preset angle.

[0026] In some embodiments, the reflectivity of the interface to the diffracted light satisfies the following relationship with the incident angle of the diffracted light:

[0027] The reflectivity of the interface to the diffracted light with an incident angle between 0° and 30° is greater than 0 and less than 5%.

[0028] The reflectivity of the interface to the diffracted light with an incident angle between 30° and 50° is greater than or equal to 1% and less than 30%.

[0029] The reflectivity of the interface to the diffracted light with an incident angle between 50° and 90° is greater than or equal to 10% and less than or equal to 100%.

[0030] In some embodiments, the coupling structure includes a reflective surface, the reflective surface comprising: a first inclined surface formed on the waveguide substrate; and a first reflective film deposited on the first inclined surface, wherein the first reflective film is deposited on the first inclined surface after the first inclined surface is formed on the waveguide substrate.

[0031] In some embodiments, the waveguide substrate includes a first waveguide substrate and a second waveguide substrate, wherein the first waveguide substrate is provided with the coupling-in structure, the coupling-out structure and the diffraction structure, and the second waveguide substrate is provided with the coupling-in structure, the coupling-out structure and the diffraction structure;

[0032] The diffraction structure of the first waveguide substrate includes a third diffraction optical structure and a fourth diffraction optical structure. The coupling structure of the first waveguide substrate is used to allow incident light to enter the waveguide substrate and propagate along the third dimension within the waveguide substrate to the third diffraction optical structure. The third diffraction optical structure is used to diffract the propagating light within the waveguide substrate, causing diffracted light with different diffraction angles to propagate within the waveguide substrate and then turn to propagate along the fourth dimension towards the fourth diffraction optical structure. The fourth diffraction optical structure is used to diffract and turn the diffracted light with different diffraction angles propagating within the waveguide substrate towards the coupling structure of the first waveguide substrate.

[0033] The first waveguide substrate includes a third region and a fourth region. The third region of the first waveguide substrate is provided with the coupling structure and the third diffraction optical structure, and the fourth region of the first waveguide substrate is provided with the fourth diffraction optical structure and the coupling structure.

[0034] The diffraction structure of the second waveguide substrate includes a fifth diffraction optical structure and a sixth diffraction optical structure. The coupling structure of the second waveguide substrate is used to allow incident light to enter the waveguide substrate and propagate along the fifth dimension within the waveguide substrate to the fifth diffraction optical structure. The fifth diffraction optical structure is used to diffract the propagating light within the waveguide substrate, causing diffracted light with different diffraction angles to propagate within the waveguide substrate and then turn to propagate along the sixth dimension towards the sixth diffraction optical structure. The sixth diffraction optical structure is used to diffract and turn the diffracted light with different diffraction angles propagating within the waveguide substrate towards the coupling structure.

[0035] The second waveguide substrate includes a fifth region and a sixth region. The fifth region of the second waveguide substrate is provided with the coupling structure and the fifth diffraction optical structure, and the sixth region of the second waveguide substrate is provided with the sixth diffraction optical structure and the coupling structure.

[0036] The first waveguide substrate and the second waveguide substrate are stacked, and the projection of the third region of the first waveguide substrate along the stacking direction coincides with the projection of the sixth region of the second waveguide substrate along the stacking direction. The projection of the fourth region of the first waveguide substrate along the stacking direction coincides with the projection of the fifth region of the second waveguide substrate along the stacking direction. The coupling structure, coupling structure, the third diffraction optical structure and the fourth diffraction optical structure of the first waveguide substrate are symmetrical to the coupling structure, coupling structure, fifth diffraction optical structure and sixth diffraction optical structure of the second waveguide substrate in sequence.

[0037] An augmented reality display device includes an optical engine module and an optical waveguide device as described in any of the above.

[0038] As can be seen from the above technical solution, the optical waveguide device provided by the present invention includes a waveguide substrate, a coupling structure, a coupling structure, and a diffraction structure; the coupling structure is used to allow incident light to enter the waveguide substrate for propagation within the waveguide substrate; the diffraction structure is used to diffract and redirect the propagating light within the waveguide substrate, causing diffracted light with different diffraction angles to propagate within the waveguide substrate and towards the coupling structure; the waveguide substrate includes at least two waveguide layers, and any two adjacent waveguide layers of the at least two waveguide layers include a first waveguide layer and a second waveguide layer, wherein the first waveguide layer and the second waveguide layer have The interface allows diffracted light propagating within the waveguide substrate to undergo partial reflection when incident from the first waveguide layer to the interface, and partial reflection when incident from the second waveguide layer to the interface; alternatively, it allows diffracted light propagating within the waveguide substrate to undergo partial reflection when incident from the first waveguide layer to the interface, and partial reflection and total internal reflection when incident from the second waveguide layer to the interface, with the reflectivity of the interface to the diffracted light increasing with the incident angle of the diffracted light; the coupling structure is used to allow diffracted light propagating within the waveguide substrate to exit outside the waveguide substrate.

[0039] The beneficial effect of this invention is that the waveguide substrate includes at least two waveguide layers, and any two adjacent waveguide layers have an interface. Since the reflectivity of the interface for diffracted light increases with the incident angle of the diffracted light, and diffracted light with a large diffraction angle has a larger incident angle when passing through the interface, its reflectivity is also larger. This results in more reflection of the diffracted light with a large diffraction angle when passing through the interface, allowing it to propagate more within the waveguide layer on the side where the diffracted light is incident. Conversely, diffracted light with a small diffraction angle has a smaller incident angle when passing through the interface, resulting in lower reflectivity. This allows more diffracted light with a small diffraction angle to be transmitted through the interface, enabling it to propagate throughout the entire waveguide substrate. Thus, the step size variation of diffracted light with different diffraction angles within the waveguide substrate can be relatively uniform, thereby avoiding significant color shift in the optical waveguide device and improving color uniformity.

[0040] The augmented reality display device of the present invention can improve color uniformity, reduce color shift, and help improve display quality. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1A top view of an optical waveguide device provided in the first embodiment;

[0043] Figure 2 for Figure 1 Side view of the optical waveguide device shown;

[0044] Figure 3 for Figure 1 The diagram shows the light propagation of the optical waveguide device.

[0045] Figure 4 A top view of an optical waveguide device provided in the second embodiment;

[0046] Figure 5 The top view of the optical waveguide device of the first embodiment after rotating the waveguide substrate and the established coordinate system about the Z-axis;

[0047] Figure 6 This is a partial side view of the optical waveguide device according to the first embodiment;

[0048] Figure 7 This is a schematic diagram illustrating the light propagation of the optical waveguide device according to the first embodiment, with various angles marked.

[0049] Figure 8 This is a top view of the finished optical waveguide device according to the first embodiment;

[0050] Figure 9 This is a schematic diagram of blue light propagation in a portion of the optical waveguide device according to the first embodiment;

[0051] Figure 10 This is a schematic diagram of red light propagation in a portion of the optical waveguide device according to the first embodiment;

[0052] Figure 11 The reflectivity curve of the optical waveguide device in the third embodiment when a dielectric film layer is disposed between the first waveguide layer and the second waveguide layer;

[0053] Figure 12 The reflectivity curve of the optical waveguide device in the fourth embodiment when a dielectric film layer is disposed between the first waveguide layer and the second waveguide layer;

[0054] Figure 13 A simulation diagram of the red light coupling spot when the first and second waveguide layers of the waveguide substrate of the optical waveguide device have the same refractive index and no dielectric film layer is set.

[0055] Figure 14 A simulation diagram of the coupling spot of red light when the waveguide substrate of the optical waveguide device of the fourth embodiment is provided with a first waveguide layer, a second waveguide layer and a dielectric film layer;

[0056] Figure 15The reflectivity curve of the optical waveguide device in the fifth embodiment when a dielectric film layer is disposed between the first waveguide layer and the second waveguide layer;

[0057] Figure 16 A simulation diagram of the coupling spot of red light when the waveguide substrate of the optical waveguide device of the fifth embodiment is provided with a first waveguide layer, a second waveguide layer and a dielectric film layer;

[0058] Figure 17 The optical waveguide device of the sixth embodiment includes the reflectivity curves of the first waveguide layer and the second waveguide layer;

[0059] Figure 18 A simulation diagram of the coupled-out spot of red light when the waveguide substrate of the optical waveguide device of the sixth embodiment is provided with a first waveguide layer and a second waveguide layer and the two have different refractive indices;

[0060] Figure 19 A side view of an optical waveguide device provided in the seventh embodiment;

[0061] Figure 20-1 A top view of the first waveguide substrate of an optical waveguide device provided in the eighth embodiment;

[0062] Figure 20-2 A top view of the second waveguide substrate of an optical waveguide device provided in the eighth embodiment;

[0063] Figure 20-3 A top view of an optical waveguide device provided in the eighth embodiment;

[0064] Figure 21 This is a schematic diagram of the reflecting surface and the beam-splitting surface of the optical waveguide device in the first embodiment.

[0065] The reference numerals in the accompanying drawings include:

[0066] 100-Waveguide substrate, 101-Reflecting surface, 102-First diffractive optical structure, 103-Second diffractive optical structure, 104-Brightness splitting surface, 105-First waveguide layer, 106-Second waveguide layer, 107-Dielectric film layer, 108-Third waveguide layer, 109-First dielectric film layer, 110-Second dielectric film layer, 111-Adhesive layer, 201-First region, 202-Second region, 203-Splicing interface;

[0067] 300 - First waveguide substrate, 301 - Third region, 302 - Fourth region, 303 - Coupled-in structure of the first waveguide substrate, 304 - Third diffractive optical structure, 305 - Fourth diffractive optical structure, 306 - Coupled-out structure of the first waveguide substrate;

[0068] 400 - Second waveguide substrate, 401 - Fifth region, 402 - Sixth region, 403 - Coupled structure of the second waveguide substrate, 404 - Fifth diffraction optical structure, 405 - Sixth diffraction optical structure, 406 - Coupled structure of the second waveguide substrate. Detailed Implementation

[0069] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0070] This embodiment provides an optical waveguide device, including a waveguide substrate, a coupling-in structure, a coupling-out structure, and a diffraction structure;

[0071] The waveguide substrate is provided with at least one of the coupling structures, which are used to allow incident light to enter the waveguide substrate and propagate within the waveguide substrate.

[0072] The waveguide substrate is provided with at least one of the diffraction structures, which are used to diffract and redirect the propagating light in the waveguide substrate, so that the diffracted light with different diffraction angles propagates in the waveguide substrate and towards the coupling structure.

[0073] The waveguide substrate includes at least two waveguide layers. Any two adjacent waveguide layers include a first waveguide layer and a second waveguide layer. The first waveguide layer and the second waveguide layer have an interface, such that when the diffracted light propagating in the waveguide substrate is incident from the first waveguide layer to the interface between the first waveguide layer and the second waveguide layer, it is partially reflected, and when the diffracted light propagating in the waveguide substrate is incident from the second waveguide layer to the interface between the first waveguide layer and the second waveguide layer, it is partially reflected.

[0074] Alternatively, the first waveguide layer and the second waveguide layer have an interface, such that when the diffracted light propagating in the waveguide substrate is incident from the first waveguide layer to the interface between the first waveguide layer and the second waveguide layer, it undergoes partial reflection, and when the diffracted light propagating in the waveguide substrate is incident from the second waveguide layer to the interface between the first waveguide layer and the second waveguide layer, a portion of the diffracted light undergoes partial reflection and another portion of the diffracted light undergoes total internal reflection.

[0075] The reflectivity of the interface to the diffracted light increases with the increase of the incident angle of the diffracted light.

[0076] The waveguide substrate is provided with at least one of the coupling structures, which are used to cause the diffracted light propagating in the waveguide substrate to exit out of the waveguide substrate.

[0077] Incident light is incident on the coupling structure of the optical waveguide device, which allows the incident light to enter the waveguide substrate. The light entering the waveguide substrate propagates within the waveguide substrate through total internal reflection.

[0078] The waveguide substrate is provided with at least one diffraction structure. The propagating light in the waveguide substrate propagates to the diffraction structure, and the diffraction structure causes the propagating light in the waveguide substrate to diffract and change direction, so that the diffracted light with different diffraction angles propagates in the waveguide substrate and propagates toward the coupling structure.

[0079] The interface between two adjacent waveguide layers refers to the interface where the two adjacent waveguide layers are in contact with each other. It includes two cases: one is where the two adjacent waveguide layers are in contact, and the interface between them is the interface formed by the two adjacent waveguide layers being bonded together; the other is where a dielectric layer exists between the two adjacent waveguide layers, and the interface between them is the interface where the two adjacent waveguide layers and the dielectric layer are bonded together.

[0080] When light entering the waveguide substrate propagates through total internal reflection, it passes through the interface between two adjacent waveguide layers. Since the light entering the waveguide substrate contains light of different wavelengths, the propagating light within the waveguide substrate undergoes diffraction through the diffraction structure. Different wavelengths of light diffract at different angles, resulting in diffracted light with different diffraction angles. This diffracted light continues to propagate within the waveguide substrate, passing through the interface between the two adjacent waveguide layers. The incident angle of the diffracted light refers to the angle at which the diffracted light strikes the interface. Different diffracted light at different angles will have different incident angles at the interface.

[0081] In this waveguide substrate, any two adjacent waveguide layers include a first waveguide layer and a second waveguide layer, which have an interface. When diffracted light propagating within the waveguide substrate is incident on the interface from either the first or second waveguide layer, it undergoes partial reflection. Alternatively, the first and second waveguide layers have an interface, and when diffracted light propagating within the waveguide substrate is incident on the interface from the first waveguide layer, it undergoes partial reflection; when incident on the interface from the second waveguide layer, a portion of the diffracted light undergoes partial reflection, and another portion undergoes total internal reflection. Partial reflection upon incident on the interface means that when the diffracted light is incident on the interface, at least part of the diffracted light is reflected from the interface, and at least part is transmitted through the interface.

[0082] Since the reflectivity of the interface for diffracted light increases with the incident angle of the diffracted light, diffracted light with a large diffraction angle has a larger incident angle when passing through the interface, resulting in a higher reflectivity. This causes more of the diffracted light with a large diffraction angle to be reflected when passing through the interface and to propagate more within the waveguide layer on the side where the diffracted light is incident. Conversely, diffracted light with a small diffraction angle has a smaller incident angle when passing through the interface, resulting in a lower reflectivity. This causes more of the diffracted light with a small diffraction angle to be transmitted when passing through the interface and to propagate throughout the waveguide substrate. In this way, the step size variation of diffracted light with different diffraction angles can be made more uniform within the waveguide substrate, thereby avoiding obvious color shift in the optical waveguide device and improving color uniformity.

[0083] In this embodiment, the coupling structure is not limited. In some embodiments, the coupling structure includes a reflecting surface disposed on the waveguide substrate, which at least partially reflects the incident light, allowing the reflected light to enter the waveguide substrate. In some embodiments, the coupling structure includes a refractive surface disposed on the waveguide substrate, which at least partially refracts the incident light into the waveguide substrate. The coupling structure may include a prism, which forms the refractive surface.

[0084] In this embodiment, the coupling structure is not limited. In some implementations, the coupling structure includes multiple parallel beam-splitting surfaces, which are used to eject diffracted light propagating within the waveguide substrate out of the waveguide substrate. The beam-splitting surfaces reflect, transmit, or refract the diffracted light propagating within the waveguide substrate, thereby achieving light coupling out of the waveguide substrate.

[0085] The diffraction structure causes the propagating light within the waveguide substrate to diffract and redirect, thereby expanding the pupil of the propagating light within the waveguide substrate. In some embodiments, the diffraction structure includes a first diffraction optical structure and a second diffraction optical structure;

[0086] The coupling structure is used to allow incident light to enter the waveguide substrate and propagate along the first dimension within the waveguide substrate to the first diffractive optical structure.

[0087] The first diffractive optical structure is used to diffract the propagating light in the waveguide substrate, so that the diffracted light with different diffraction angles propagates in the waveguide substrate and is turned to propagate along the second dimension direction, propagating towards the second diffractive optical structure. The second diffractive optical structure is used to diffract and turn the diffracted light with different diffraction angles propagating in the waveguide substrate, so that it propagates towards the coupling structure.

[0088] The first dimension is not parallel to the second dimension. Light propagating from the coupling structure to the first diffraction optical structure is diffracted by the first diffraction optical structure, resulting in diffracted light that redirects to propagate along the second dimension, while some light continues to propagate along the first dimension. The first diffraction optical structure can ensure that the energy of the diffracted light, after diffraction in the waveguide substrate, at different diffraction angles and redirected to propagate along the second dimension, is higher than the energy of the light propagating along the first dimension. In this embodiment, by setting a first diffraction optical structure and a second diffraction optical structure, the optical parameters of the first diffraction optical structure can be adjusted so that the energy of the diffracted light, after diffraction by the first diffraction optical structure and redirected to propagate along the second dimension, is higher than the energy of the light propagating along the first dimension. This allows most, or even all, of the light to propagate along the second dimension to the second diffraction optical structure and then to the coupling structure, reducing the energy of light entering the waveguide substrate through the coupling structure and directly propagating to the coupling structure after passing through the first diffraction optical structure. This reduces the bright band stray light phenomenon and improves imaging quality.

[0089] In some implementations, after light diffracts in the first diffraction optical structure, the diffraction efficiency of the diffraction order corresponding to the diffraction path in the second dimension is higher than that of the diffraction order corresponding to the diffraction path in the first dimension, so as to satisfy that the energy of the diffracted light that propagates from the coupling structure to the first diffraction optical structure and then turns to propagate in the second dimension after being diffracted by the first diffraction optical structure is higher than the energy of the light propagating along the first dimension.

[0090] For example, refer to Figure 1 and Figure 2 , Figure 1 This is a top view of an optical waveguide device provided in the first embodiment. Figure 2 for Figure 1 The diagram shows a side view of the optical waveguide device. As shown, the waveguide substrate 100 is provided with a reflective surface 101 and a first diffractive optical structure 102. Light is coupled into the waveguide substrate 100 through the reflective surface 101 and propagates within the waveguide substrate 100 via total internal reflection. When the propagating light reaches the first diffractive optical structure 102, diffraction occurs, causing part of the light to propagate towards the second diffractive optical structure 103, while the other part continues to propagate to the edge of the waveguide substrate 100 via total internal reflection. The waveguide substrate 100 is also provided with a second diffractive optical structure 103 and multiple beam-splitting surfaces 104. The second diffractive optical structure 103 diffracts the light, directing it towards the beam-splitting surfaces 104, while simultaneously expanding the pupil of the propagating light. The beam-splitting surfaces 104 couple the propagating light outward from the waveguide substrate 100 and into the human eye.

[0091] The upper and lower surfaces of the waveguide substrate 100 are parallel to each other, allowing light entering the waveguide substrate 100 to be totally reflected by the upper and lower surfaces. The waveguide substrate 100 can be made of a light-transmitting material.

[0092] The structure of the first diffractive optical structure 102 is not limited. The first diffractive optical structure 102 can be a grating, and can be, but is not limited to, an embossed grating or a holographic grating. The first diffractive optical structure 102 can be formed on one side of the waveguide substrate 100, or it can be formed inside the waveguide substrate 100.

[0093] The structure of the second diffractive optical structure 103 is not limited. The second diffractive optical structure 103 can be a grating, and can be, but is not limited to, an embossed grating or a holographic grating. The second diffractive optical structure 103 can be formed on one side of the waveguide substrate 100, or it can be formed within the waveguide substrate 100. The first diffractive optical structure 102 or the second diffractive optical structure 103 can improve the light efficiency and uniformity by optimizing the grating parameters through partitioning or by using a height-gradient grating.

[0094] In some embodiments, the waveguide substrate further includes a first region and a second region, which are joined together. The coupling structure and the first diffractive optical structure are disposed in the first region of the waveguide substrate, and the second diffractive optical structure and the coupling-out structure are disposed in the second region of the waveguide substrate. The splicing interface between the first and second regions is parallel to the first dimensional direction, or the angle between the splicing interface between the first and second regions and the first dimensional direction is greater than 0° and less than 90°, so that the splicing interface between the first and second regions deviates from the light propagating in the waveguide substrate after diffraction by the first diffractive optical structure and continuing to propagate along the first dimensional direction. In this way, the light propagating in the waveguide substrate after diffraction by the first diffractive optical structure and continuing to propagate along the first dimensional direction cannot propagate to the splicing interface between the first and second regions of the waveguide substrate, cannot pass through the splicing interface to reach the second region, and thus cannot propagate to the coupling-out structure. This prevents light entering the waveguide substrate through the coupling structure from directly propagating to the coupling-out structure after passing through the first diffractive optical structure, thereby reducing bright band stray light phenomena and improving imaging quality.

[0095] For example, refer to Figure 3 , Figure 3 for Figure 1The diagram illustrates the light propagation of an optical waveguide device. The dashed lines with arrows indicate the direction of light propagation. A Z-axis is established along the thickness direction of the waveguide substrate 100, and a three-dimensional Cartesian coordinate system (XYZ) is created. Light entering the waveguide substrate 100 from the reflecting surface 101 propagates along direction a and reaches the first diffraction optical structure 102. After diffraction by the first diffraction optical structure 102, diffracted light is diffracted and propagates along direction b, while some light continues to propagate along direction a. As shown, the interface 203 between the first region 201 and the second region 202 is not parallel to direction a. This prevents the light continuing to propagate along direction a after passing through the first diffraction optical structure 102 from reaching the interface 203, thus preventing it from reaching the second region 202 and ultimately the beam splitter 104. In practical applications, the angle between the interface 203 and the X-axis can be adjusted to meet the requirements. For example, the angle between the splicing interface 203 and the X-axis ranges from -40° to +40°.

[0096] In some embodiments, the waveguide substrate further includes a first region and a second region, which are spliced ​​together. The coupling structure and the first diffractive optical structure are disposed in the first region of the waveguide substrate, and the second diffractive optical structure and the coupling-out structure are disposed in the second region of the waveguide substrate. The splicing interface between the first region and the second region is not parallel to the first dimension, and a first film layer is disposed at the splicing interface. This allows light propagating in the waveguide substrate, after being diffracted by the first diffractive optical structure, to continue propagating along the first dimension, to undergo total internal reflection when incident on the splicing interface. Total internal reflection when light is incident on the splicing interface means that total internal reflection occurs when light is incident on the splicing interface. In this way, light propagating in the waveguide substrate, after being diffracted by the first diffractive optical structure, cannot pass through the splicing interface to reach the second region, and thus cannot propagate to the coupling-out structure. This prevents light entering the waveguide substrate through the coupling structure from directly propagating to the coupling-out structure after passing through the first diffractive optical structure, thereby reducing bright band stray light phenomena and improving imaging quality.

[0097] For example, refer to Figure 4 , Figure 4This is a top view of an optical waveguide device provided in the second embodiment. The dashed lines with arrows indicate the direction of light propagation. A Z-axis is established along the thickness direction of the waveguide substrate 100, and a three-dimensional Cartesian coordinate system (XYZ) is established. The propagating light entering the waveguide substrate 100 from the reflecting surface 101 propagates along direction c and reaches the first diffraction optical structure 102. After being diffracted by the first diffraction optical structure 102, part of the propagating light continues to propagate along direction c. As shown in the figure, the splicing interface 203 of the first region 201 and the second region 202 is not parallel to direction c and is provided with a first film layer. This causes the light that continues to propagate along direction c after passing through the first diffraction optical structure 102 to be incident on the splicing interface 203 and undergo total internal reflection, thus preventing it from reaching the second region 202 and consequently preventing it from propagating to the beam splitter 104.

[0098] In practical applications, the angle between the splicing interface 203 and the X-axis, as well as the refractive index of the first film layer, can be adjusted to ensure total internal reflection of light propagating along the first dimension after passing through the first diffraction optical structure 102 when it reaches the splicing interface 203. In some embodiments, the refractive index of the first film layer is less than the refractive index of the waveguide substrate 100. The first film layer can be an adhesive layer or a dielectric film, both of which are transparent materials. For example, Figure 4 The angle between the splicing interface 203 and the X-axis is -13°.

[0099] In some embodiments, the waveguide substrate further includes a first region and a second region, which are joined together. The coupling structure and the first diffractive optical structure are disposed in the first region of the waveguide substrate, and the second diffractive optical structure and the coupling-out structure are disposed in the second region of the waveguide substrate. The interface between the first and second regions is not parallel to the thickness direction of the waveguide substrate. The interface between the first and second regions of the waveguide substrate has a certain reflectivity for light propagating within the waveguide substrate, which can cause some light to be reflected at the interface and exit from the waveguide substrate, entering the human eye and forming stray light. In this embodiment, by setting the interface between the first and second regions of the waveguide substrate to be non-parallel to the thickness direction of the waveguide substrate, the angle between the interface and the thickness direction of the waveguide substrate can be adjusted to prevent reflected light generated at the interface from entering the human eye.

[0100] The effects of the first and second diffractive optical structures on the propagation of light are explained in detail below with reference to the accompanying drawings. Figure 5 , Figure 5 The first embodiment of the optical waveguide device is shown in a top view after rotating the waveguide substrate and the established coordinate system around the Z-axis.

[0101] Let θ be the angle between the projection of the incident light along the Y-axis onto the XZ plane and the Z-axis at any given field of view, and let θ be the angle between the projection of the incident light along the Z-axis onto the XY plane and the X-axis. If the incident light remains unchanged, and the waveguide substrate 100 and the established coordinate system are rotated clockwise by an angle η around the Z-axis, let the angle corresponding to the incident light after the rotation be (θ0, ... Then, based on geometric relationships, we can derive:

[0102] ;

[0103] .

[0104] like Figure 6 As shown, Figure 6 This is a partial side view of the optical waveguide device according to the first embodiment. The dashed lines in the figure indicate the direction of light propagation. Let the angle between the reflecting surface 101 and the surface of the waveguide substrate 100 be δ. The refractive index of the first waveguide layer 105 is n1, the refractive index of the second waveguide layer 106 is n2, and the incident light (θ0, After being coupled into the waveguide substrate 100, the light propagates towards the first diffractive optical structure 102 via total internal reflection. The angle between the projection of the propagating light onto the XY plane along the Z-axis within the first waveguide layer 105 and the X-axis is [value missing]. That is, the incident light (θ0, The spherical coordinates of the light propagating toward the first diffractive optical structure 102 within the first waveguide layer 105 after coupling into the waveguide substrate 100 are (θ1, θ2, θ3, θ4). ).

[0105] Based on geometric relationships, we can derive:

[0106] ;

[0107] .

[0108] Let the angle between the grating groove direction of the first diffractive optical structure 102 and the second diffractive optical structure 103 and the Y-axis be ρ, the grating period be d, and the propagating light (θ1, After encountering the first diffractive optical structure 102 within the second waveguide layer 106, diffraction occurs. Let the angle of the diffracted light be (θ2, The wavelength of the light is λ, and the angle between the projection of the diffracted light along the Z-axis onto the XY plane and the Y-axis is r, as shown below. Figure 7 As shown, Figure 7 This is a schematic diagram illustrating the propagation of light from the optical waveguide device of the first embodiment, showing the various angles. Based on diffraction relationships, we can obtain...

[0109] ;

[0110] ;

[0111] Therefore, we can conclude that:

[0112] ;

[0113] ;

[0114] .

[0115] Based on the above derivation, it can be seen that if the angle (θ) of the incident light in any field of view is known, Given the wavelength λ, the refractive index n1 of the first waveguide layer 105, the refractive index n2 of the second waveguide layer 106, the angle δ of the reflecting surface 101, the rotation angle η of the waveguide substrate 100, the grating groove direction ρ and the grating period d of the first diffraction optical structure 102, the spherical coordinates (θ2, θ2, θ3) of the light after diffraction by the first diffraction optical structure 102 can be calculated using the above formulas. The rotation angle η and the light steering angle r of the waveguide substrate 100 are given. To achieve a single-chip full-color display, the above-mentioned parameters must ensure that θ2 satisfies arcsin(1 / n2) < θ2 < 90°. Simultaneously, to make the effective cut area of ​​the waveguide substrate 100 more conform to the shape of eyeglasses, the rotation angle η and the light steering angle r of the waveguide substrate 100 should satisfy η + r > 0. Based on this, the following ranges are further defined: the rotation angle η of the waveguide substrate 100 ≥ 0, the grating groove direction ρ satisfies 30° < ρ < 70°, and the grating period d satisfies 200 nm. <d<500nm。

[0116] For example, assuming the image source has a diagonal field of view of 40°, and the wavelengths of red, green, and blue are 617nm, 525nm, and 460nm respectively, and both the first waveguide layer 105 and the second waveguide layer 106 are made of glass with a refractive index of 1.91, such as TAFD25 ground glass, the angle δ of the reflecting surface 101 is 25.7°, the angle between the splicing interface 203 and the X-axis is 13°, the rotation angle η of the waveguide substrate 100 is 15°, the grating groove direction ρ is 52°, and the grating period d is 314nm, then the image source has a lateral field of view of 35.2° along the X-axis and a longitudinal field of view of 20.24° along the Y-axis. The central field of view is coupled perpendicularly to the surface of the waveguide substrate 100. The angles (θ, ...) of the four edge field rays are... The angles are (-17.6°, -10.12°), (-17.6°, 10.12°), (17.6°, 10.12°), and (17.6°, -10.12°), respectively. Based on the above formula, it can be derived that after rotating the waveguide substrate 100 and the established coordinate system clockwise around the Z-axis by an angle η, the corresponding angles for the four edge field rays are (θ0, ...). The spherical coordinates are (-14.59°, -14.28°), (-19.42°, 5.16°), (14.59°, 14.28°), and (19.42°, -5.16°), respectively. The wavelengths of the rays in the four edge fields of view are different, and the corresponding spherical coordinates are (θ2, θ2, θ3, θ4, θ5, θ6, θ7, θ8, θ9, θ1, θ2, θ3, θ8, θ9, θ1, θ2, θ3, θ4, θ5, θ6, θ7 ... The wavelengths of red, green, and blue are also different. Calculations show that the angular range covered by the four edge fields of view corresponding to the red, green, and blue wavelengths is 31.7° < θ2 < 74.5°, and the corresponding 17.8° < η + r < 50.6°. The optical waveguide device that can be finally made according to this design is as follows: Figure 8 As shown, Figure 8 This is a top view of the finished optical waveguide device according to the first embodiment. The relative positions of the coupling in and coupling out, as well as the overall shape of the optical waveguide device, are very similar to the shape of eyeglasses.

[0117] In some embodiments, a dielectric film is disposed at the interface between the first waveguide layer and the second waveguide layer. This dielectric film has a single refractive index, which is less than the refractive indices of both the first and second waveguide layers. The dielectric film satisfies the condition for suppressed total internal reflection. When a very thin, less dense medium exists between two optically denser media, and light rays are incident from one optically denser medium at an angle greater than the total internal reflection angle onto the thin layer of the less dense medium, some of the light rays will pass through the thin layer and enter the other optically denser medium. This optical phenomenon is called suppressed total internal reflection. Furthermore, the reflectivity of the light rays increases with the angle of incidence from one optically denser medium to the thin layer of the less dense medium. The condition for suppressed total internal reflection can be satisfied by selecting the refractive indices of the first waveguide layer, the second waveguide layer, and the dielectric film, and by adjusting their thicknesses.

[0118] In this embodiment, the interface between the first waveguide layer and the second waveguide layer can be considered as the interface between the first waveguide layer and the dielectric film layer, or the interface between the second waveguide layer and the dielectric film layer. Diffracted light incident from the first waveguide layer to the interface means the diffracted light is incident from the first waveguide layer to the interface between the first waveguide layer and the dielectric film layer. Diffracted light incident from the second waveguide layer to the interface means the diffracted light is incident from the second waveguide layer to the interface between the second waveguide layer and the dielectric film layer.

[0119] For example, refer to Figure 9 and Figure 10 , Figure 9 This is a schematic diagram of blue light propagation in a portion of the optical waveguide device according to the first embodiment. Figure 10 This is a schematic diagram of red light propagation in a portion of the optical waveguide device according to the first embodiment. Figure 9 The diagram shows the propagation of blue diffracted light generated after diffraction by the first diffractive optical element 102 within the waveguide substrate 100. The blue diffracted light has a small diffraction angle, and its incident angle is also small when it reaches the dielectric film layer 107. When the blue diffracted light enters the dielectric film layer 107 from the first waveguide layer 105 or the second waveguide layer 106, it is primarily transmitted, resulting in total internal reflection of most of the blue diffracted light between the upper surface of the first waveguide layer 105 and the lower surface of the second waveguide layer 106. Figure 10The diagram shows the propagation of red diffracted light generated after diffraction by the first diffractive optical element 102 within the waveguide substrate 100. The red diffracted light has a large diffraction angle and a large incident angle when it is incident on the dielectric film layer 107. When the red diffracted light is incident on the dielectric film layer 107 from the first waveguide layer 105 or the second waveguide layer 106, it is partially reflected and partially transmitted, which can reduce the step size of the red diffracted light within the waveguide substrate 100.

[0120] In some embodiments, a dielectric film layer is disposed at the interface between the first waveguide layer and the second waveguide layer. This dielectric film layer comprises at least two layers with different refractive indices stacked together, causing partial reflection of diffracted light propagating within the waveguide substrate when incident from the first waveguide layer to the interface, and partial reflection of diffracted light propagating within the waveguide substrate when incident from the second waveguide layer to the interface. Furthermore, the reflectivity of the interface to the diffracted light increases with the incident angle of the diffracted light. The above requirements can be met by selecting the refractive indices of the first and second waveguide layers and designing the film system using at least two layers with different refractive indices included in the dielectric film layer. The dielectric film layer may be, but is not limited to, SiO2, Al2O3, Ta2O5, HfO2, CeO2, or TiO2 film materials.

[0121] In some embodiments, the reflectivity of the interface to the diffracted light satisfies the following relationship with the incident angle of the diffracted light: the reflectivity of the interface to the diffracted light with an incident angle between 0° and 30° is greater than 0 and less than 5%; the reflectivity of the interface to the diffracted light with an incident angle between 30° and 50° is greater than or equal to 1% and less than 30%; the reflectivity of the interface to the diffracted light with an incident angle between 50° and 90° is greater than or equal to 10% and less than or equal to 100%.

[0122] For example, refer to Figure 2 The optical waveguide device shown has a dielectric film layer 107 disposed between the first waveguide layer 105 and the second waveguide layer 106. The dielectric film layer 107 is a SiO2 film layer with a low refractive index. The first waveguide layer 105 and the second waveguide layer 106 are both high refractive index glass sheets, such as TAFD25 ground glass sheets.

[0123] If the thickness of the dielectric film 107 (i.e., the SiO2 film) is much greater than the wavelength of visible light, then the first waveguide layer 105, the second waveguide layer 106, and the dielectric film 107 do not satisfy the condition for suppressed total internal reflection. (See reference...) Figure 11 , Figure 11The reflectance curve of the optical waveguide device in the third embodiment, where a dielectric film layer is disposed between the first waveguide layer and the second waveguide layer, is a reflectance curve for a wavelength of 525 nm. It can be seen that when light is incident from the first waveguide layer 105 or the second waveguide layer 106 onto the dielectric film layer 107, total internal reflection occurs at an incident angle of approximately 50°, but the reflectance fluctuates when the incident angle is less than 50°.

[0124] When the SiO2 film thickness is 50 nm, it is much smaller than the thickness of the first waveguide layer 105 and the second waveguide layer 106, thus satisfying the condition for suppressed total internal reflection. (See reference...) Figure 12 , Figure 12 The reflectance curve of the optical waveguide device in the fourth embodiment, where a dielectric film layer is disposed between the first and second waveguide layers, is a reflectance curve for a wavelength of 525 nm. It can be seen that light has a certain transmittance in the range of 50°-90°, a lower reflectance in the range of 0°-30°, and a higher reflectance in the range of 60°-90°. In the range of 30°-90°, the reflectance increases with the increase of the incident angle. The rate of change of reflectance in the range of 0°-90° changes from a slow increase to a rapid increase, and then from a rapid increase to a slow decrease. Using a single material for the dielectric film layer 107 has the following disadvantages: poor light transmittance... Figure 12 The reflectivity curve shows that the reflectivity is around 5% at 0°, which causes a transmittance loss in the waveguide substrate 100. Furthermore, the only optimizable parameter is the thickness, and the optimization space for uniformity is too small.

[0125] The thicknesses of the first waveguide layer 105 and the second waveguide layer 106 of the optical waveguide device can be specifically designed according to application requirements. For example, assuming the first waveguide layer 105 has a thickness of 1 mm, the second waveguide layer 106 has a thickness of 0.3 mm, and the dielectric film layer 107 is a SiO2 film layer with a thickness of 50 nm, covering the entire waveguide substrate 100. A simulation is performed using the edge field of view (-17.6°, -10.12°) with the largest step size of red light total internal reflection as an example, with a beam diameter of 1 mm, for comparison. Figure 13 and Figure 14 , Figure 13 This is a simulation diagram of the red light coupling spot when the refractive index system of the first and second waveguide layers of the waveguide substrate of an optical waveguide device is not provided with a dielectric film layer. Figure 14 This is a simulation diagram of the coupling spot of red light when the waveguide substrate of the optical waveguide device in the fourth embodiment is provided with a first waveguide layer, a second waveguide layer, and a dielectric film layer. A comparison shows that... Figure 13 The continuity of the emitted light spot is very poor. Figure 14 The continuity of the emitted light spot is improved.

[0126] For example, refer to Figure 2The optical waveguide device shown has a dielectric film layer 107 disposed between the first waveguide layer 105 and the second waveguide layer 106. The dielectric film layer 107 includes at least two films with different refractive indices, which are made of SiO2 and Ta2O5 materials. The total thickness of the dielectric film layer 107 is between 0-700nm. The parameters of the dielectric film layer 107 are shown in Table 1.

[0127] Table 1

[0128]

[0129] For reference Figure 15 , Figure 15 The reflectance curves of the optical waveguide device in the fifth embodiment, when a dielectric film layer is disposed between the first and second waveguide layers, include reflectance curves at 617nm, 525nm, and 460nm. It can be seen that the reflectance is less than 1% in the 0°-40° incident range, ensuring that adding the dielectric film layer 107 does not affect the transmittance of the waveguide substrate 100. For blue light, the total internal reflection angle range in the waveguide substrate 100 is 31.7° < θ2 < 54°, and the reflectance of the dielectric film layer 107 is very low. For red light, the total internal reflection angle range in the waveguide substrate 100 is 44° < θ2 < 74.5°; the larger the angle, the higher the reflectance. This significantly improves the continuity of beams with larger total internal reflection steps, while having little impact on beams with smaller total internal reflection steps, thereby significantly improving the color shift problem. Figure 16 This is a simulation diagram of the coupled-out spot of red light when the waveguide substrate of the optical waveguide device of the fifth embodiment is provided with a first waveguide layer, a second waveguide layer, and a dielectric film layer. The comparison shows that the continuity and uniformity of the coupled-out spot are significantly improved.

[0130] In some embodiments, the reflectivity of the interface to the diffracted light satisfies the following relationship with the incident angle of the diffracted light: as the incident angle of the diffracted light propagating in the waveguide substrate increases at the interface, the rate of change of the reflectivity of the interface to the diffracted light changes from a slow increase to a rapid increase, and then from a rapid increase to a slow decrease. That is, as the diffraction angle of the diffracted light increases, the incident angle of the diffracted light at the interface increases, and the rate of change of the reflectivity of the interface to the diffracted light initially increases relatively slowly, then increases sharply, and finally returns to a stable state. Thus, at small diffraction angles, the reflectivity is low and changes slowly; at intermediate diffraction angles, the reflectivity is moderate and changes relatively quickly; and at large diffraction angles, the reflectivity is high and changes slowly. This significantly improves the continuity of diffracted light at larger diffraction angles while having little impact on diffracted light at smaller diffraction angles, thereby significantly improving the color shift problem.

[0131] In some embodiments, the refractive index of the first waveguide layer is less than that of the second waveguide layer. This causes partial reflection of the diffracted light propagating within the waveguide substrate when it is incident from the first waveguide layer to the interface between the first and second waveguide layers. Conversely, when the diffracted light propagating within the waveguide substrate is incident from the second waveguide layer to the interface between the first and second waveguide layers, a portion of the diffracted light undergoes partial reflection, while another portion undergoes total internal reflection. The reflectivity of the interface for the diffracted light increases with the incident angle. The refractive index of the second waveguide layer is greater than that of the first waveguide layer. When light enters the first waveguide layer from the second waveguide layer, Fresnel reflection occurs at the interface. The larger the incident angle, the higher the reflectivity; light rays with angles greater than the total internal reflection angle will undergo total internal reflection.

[0132] In some embodiments, when the diffracted light propagating in the waveguide substrate is incident from the second waveguide layer to the interface between the first and second waveguide layers, partial reflection occurs when the incident angle of the diffracted light is less than a preset angle, and total internal reflection occurs when the incident angle of the diffracted light is greater than or equal to the preset angle. In some embodiments, when the diffracted light propagating in the waveguide substrate is incident from the second waveguide layer to the interface between the first and second waveguide layers, the reflectivity of the interface to the diffracted light satisfies the following relationship with the incident angle of the diffracted light: when the incident angle of the diffracted light is less than the preset angle, as the incident angle of the diffracted light at the interface increases, the rate of change of the reflectivity of the interface to the diffracted light changes from a slow increase to a rapid increase.

[0133] For example, the first waveguide layer 105 is made of a glass sheet with a refractive index of 1.7, such as an H-ZF11 glass sheet, and the second waveguide layer 106 is made of a glass sheet with a refractive index of 1.91, such as a TAFD25 glass sheet. Since the refractive index of the second waveguide layer 106 is higher than that of the first waveguide layer 105, diffracted light undergoes Fresnel reflection at the interface when it enters the first waveguide layer 105 from the second waveguide layer 106. The larger the angle, the higher the reflectivity. A portion of the light exceeding the total internal reflection angle undergoes total internal reflection, with a total internal reflection angle of 62.9°. When diffracted light enters the second waveguide layer 106 from the low-refractive-index first waveguide layer 105, it undergoes refraction. After refraction, the angle within the second waveguide layer 106 decreases, but total internal reflection is still satisfied. Therefore, diffracted light at different diffraction angles undergoes total internal reflection between the upper surface of the first waveguide layer 105 and the lower surface of the second waveguide layer 106, while simultaneously refracting and traversing back and forth at the interface between the first and second waveguide layers 105 and 106.

[0134] Assuming the image source has a diagonal field of view of 40°, and the wavelengths of red, green, and blue are 617nm, 525nm, and 460nm respectively, the angle δ of the reflecting surface 101 is 25.7°, the angle between the splicing interface 203 and the X-axis is 13°, the rotation angle η of the waveguide substrate 100 is 15°, the grating groove direction ρ is 52°, and the grating period d is 300nm, then the image source's lateral field of view along the X-axis is 35.2°, the longitudinal field of view along the Y-axis is 20.24°, and the central field of view is coupled perpendicularly to the surface of the waveguide substrate 100. Calculations show that the angular range of the red, green, and blue wavelengths within the first waveguide layer 105 is 41.7° < θ1 < 61.5°. Calculations also show that the angular range covered by the four edge field rays corresponding to the red, green, and blue wavelengths is 31.5° < θ2 < 79.1°, and correspondingly 10.4° < η + r < 50.7°. The blue light angle range is 31.5° < θ2 < 58.35°, and the red light angle range is 47.76° < θ2 < 79.1°.

[0135] For reference Figure 17 , Figure 17 The optical waveguide device of the sixth embodiment includes reflectance curves for a first waveguide layer and a second waveguide layer, which are reflectance curves for a wavelength of 525 nm. It can be seen that the total internal reflection angle is 62.9°, and the reflectance increases with the incident angle in the range of 0°-62.9°. When the first diffractive optical structure 102 is disposed on the second waveguide layer 106, the diffracted light in the range of 62.9°-79.1°, after being diffracted and redirected by the first diffractive optical structure 102, can only propagate through total internal reflection within the second waveguide layer 106. It can only propagate through total internal reflection simultaneously within both the first waveguide layer 105 and the second waveguide layer 106 after being diffracted and redirected by the second diffractive optical structure 103. That is, light with a relatively long total internal reflection step length in the pupil expansion direction of the second diffractive optical structure 103 is significantly shortened because it can only be totally reflected within the second waveguide layer 106, thereby significantly improving the color shift problem caused by the large difference in red, green, and blue light step lengths in the pupil expansion direction of the second diffractive optical structure 103. Taking the edge field of view with the largest red light total internal reflection step size (-17.6°, -10.12°) as an example, the simulation results are as follows: When both the first waveguide layer 105 and the second waveguide layer 106 are made of TAFD25 material and there is no dielectric film layer 107, the simulation results are as follows: Figure 13 As shown, the continuity of the coupled light spot is very poor. (For reference...) Figure 18 , Figure 18This is a simulation diagram of the coupled-out light spot of red light when the waveguide substrate of the optical waveguide device of the sixth embodiment has a first waveguide layer and a second waveguide layer with different refractive indices. The first waveguide layer 105 and the second waveguide layer 106 are made of H-ZF11 and TAFD25 materials respectively, and there is no dielectric film layer. The continuity of the coupled-out light spot is significantly better. The use of a low-refractive-index material for the first waveguide layer 105 can not only improve color shift, reduce material costs, and reduce the difficulty of manufacturing processes, but also significantly reduce the weight of the optical waveguide device.

[0136] Because high-refractive-index materials have a high density, this embodiment uses a low-refractive-index waveguide layer on one side to help reduce weight. For example, the density of TAFD25 glass is 4.56 g / cm³. 3 This would result in a relatively heavy overall optical waveguide device. Therefore, H-ZF11 glass with a refractive index of 1.7 and a density of 2.95 g / cm³ can be used. 3 .

[0137] In this embodiment, the number of waveguide layers included in the optical waveguide device is not limited, and can be set according to application requirements in practical applications. In some embodiments, the at least two waveguide layers include a first waveguide layer, a second waveguide layer, and a third waveguide layer stacked sequentially. A first dielectric film layer is disposed at the interface between the first waveguide layer and the second waveguide layer, and a second dielectric film layer is disposed at the interface between the second waveguide layer and the third waveguide layer. When diffracted light propagating in the waveguide substrate is incident from the first waveguide layer or the second waveguide layer onto the first dielectric film layer, the diffracted light undergoes partial reflection, and the reflectivity of the diffracted light increases with the increase of the incident angle. When diffracted light propagating in the waveguide substrate is incident from the second waveguide layer or the third waveguide layer onto the second dielectric film layer, the diffracted light undergoes partial reflection, and the reflectivity of the diffracted light increases with the increase of the incident angle.

[0138] For example, refer to Figure 19 , Figure 19 This is a side view of an optical waveguide device provided in the seventh embodiment. As shown, the waveguide substrate 100 includes a first waveguide layer 105, a second waveguide layer 106, a third waveguide layer 108, a first dielectric film layer 109, and a second dielectric film layer 110. The first waveguide layer 105, the second waveguide layer 106, and the third waveguide layer 108 are stacked. The first dielectric film layer 109 is disposed between the first waveguide layer 105 and the second waveguide layer 106, and the second dielectric film layer 110 is disposed between the second waveguide layer 106 and the third waveguide layer 108. Specific embodiments of the first dielectric film layer 109 and the second dielectric film layer 110 can be found in the specific embodiments of the dielectric film layer 107 described above, and will not be repeated here. Figure 19The optical waveguide device shown is for illustrative purposes only. In other embodiments, the optical waveguide device may also include other numbers of waveguide layers and dielectric film layers, all of which are within the scope of protection of this invention.

[0139] In some embodiments, the waveguide substrate includes a first waveguide substrate and a second waveguide substrate, wherein the first waveguide substrate is provided with the coupling-in structure, the coupling-out structure and the diffraction structure, and the second waveguide substrate is provided with the coupling-in structure, the coupling-out structure and the diffraction structure;

[0140] The diffraction structure of the first waveguide substrate includes a third diffraction optical structure and a fourth diffraction optical structure. The coupling structure of the first waveguide substrate is used to allow incident light to enter the waveguide substrate and propagate along the third dimension within the waveguide substrate to the third diffraction optical structure. The third diffraction optical structure is used to diffract the propagating light within the waveguide substrate, causing diffracted light with different diffraction angles to propagate within the waveguide substrate and then turn to propagate along the fourth dimension towards the fourth diffraction optical structure. The fourth diffraction optical structure is used to diffract and turn the diffracted light with different diffraction angles propagating within the waveguide substrate towards the coupling structure of the first waveguide substrate.

[0141] The first waveguide substrate includes a third region and a fourth region. The third region of the first waveguide substrate is provided with the coupling structure and the third diffraction optical structure, and the fourth region of the first waveguide substrate is provided with the fourth diffraction optical structure and the coupling structure.

[0142] The diffraction structure of the second waveguide substrate includes a fifth diffraction optical structure and a sixth diffraction optical structure. The coupling structure of the second waveguide substrate is used to allow incident light to enter the waveguide substrate and propagate along the fifth dimension within the waveguide substrate to the fifth diffraction optical structure. The fifth diffraction optical structure is used to diffract the propagating light within the waveguide substrate, causing diffracted light with different diffraction angles to propagate within the waveguide substrate and then turn to propagate along the sixth dimension towards the sixth diffraction optical structure. The sixth diffraction optical structure is used to diffract and turn the diffracted light with different diffraction angles propagating within the waveguide substrate towards the coupling structure.

[0143] The second waveguide substrate includes a fifth region and a sixth region. The fifth region of the second waveguide substrate is provided with the coupling structure and the fifth diffraction optical structure, and the sixth region of the second waveguide substrate is provided with the sixth diffraction optical structure and the coupling structure.

[0144] The first waveguide substrate and the second waveguide substrate are stacked, and the projection of the third region of the first waveguide substrate along the stacking direction coincides with the projection of the sixth region of the second waveguide substrate along the stacking direction. The projection of the fourth region of the first waveguide substrate along the stacking direction coincides with the projection of the fifth region of the second waveguide substrate along the stacking direction. The coupling structure, coupling structure, the third diffraction optical structure and the fourth diffraction optical structure of the first waveguide substrate are symmetrical to the coupling structure, coupling structure, fifth diffraction optical structure and sixth diffraction optical structure of the second waveguide substrate in sequence.

[0145] For example, refer to Figures 20-1 to 20-3 As shown, Figure 20-1 This is a top view of the first waveguide substrate of an optical waveguide device provided in the eighth embodiment. Figure 20-2 This is a top view of the second waveguide substrate of an optical waveguide device provided in the eighth embodiment. Figure 20-3 This is a top view of an optical waveguide device provided in the eighth embodiment. The device is formed by stacking a first waveguide substrate 300 and a second waveguide substrate 400. The projection of the third region 301 of the first waveguide substrate 300 along the stacking direction coincides with the sixth region 402 of the second waveguide substrate 400, and the projection of the fourth region 302 of the first waveguide substrate 300 along the stacking direction coincides with the fifth region 401 of the second waveguide substrate 400. The coupling structure 303, coupling structure 306, third diffractive optical structure 304, and fourth diffractive optical structure 305 of the first waveguide substrate are symmetrical to the coupling structure 403, coupling structure 406, fifth diffractive optical structure 404, and sixth diffractive optical structure 405 of the second waveguide substrate, respectively. The coupled-out lights of the two waveguide substrates are complementary, enabling a larger field of view and eye-tracking range.

[0146] In some embodiments, the coupling structure includes a reflective surface, which comprises: a first inclined surface formed on the waveguide substrate; and a first reflective film deposited on the first inclined surface. In some embodiments, the beam-splitting surface includes: a second inclined surface formed on the waveguide substrate; and a second reflective film deposited on the second inclined surface. After fabricating the first inclined surface / second inclined surface with the same angle as the reflective surface / beam-splitting surface on the waveguide substrate, the first reflective film / second reflective film is deposited on the first inclined surface / second inclined surface. The reflective film can be a dielectric film or a metal film. In some embodiments, a protective block can be further attached to the reflective film. The protective block can be an adhesive-attached protective block with any refractive index, eliminating the need to control the bonding process precision. This embodiment solves the problems of processing angle precision, adhesive refractive index matching, and bonding process. Furthermore, since the adhesive line is on the non-light-transmitting path side of the first reflective surface, it also avoids the influence of surface defects at the adhesive line, improving product yield and display effect. Examples can be found by referring to... Figure 21 , Figure 21 This is a schematic diagram of the reflective surface and beam-splitting surface of the optical waveguide device in the first embodiment. For the reflective surface 101, after the first inclined surface is fabricated on the waveguide substrate 100, a first reflective film is deposited on the first inclined surface. Further, an adhesive layer 111 can be formed on the first reflective film to provide protection. The relative error between the angle of the reflective surface 101 and the angle of the beam-splitting surface 104 needs to be small; otherwise, ghosting will occur in the display, which greatly complicates the manufacturing process. The conventional manufacturing method for the coupling-in and coupling-out reflective surfaces is to first create an inclined surface with the same angle as the reflective surface, and then glue the reflector onto the inclined surface. This method requires ensuring that the refractive index of the adhesive matches that of the waveguide, and that the adhesive thickness is very uniform throughout the adhesive layer to ensure normal display. Both of these points are very difficult to achieve in actual manufacturing. For the adhesive, it is difficult to find an adhesive with reliable adhesion and a refractive index consistent with the waveguide, especially a high-refractive-index adhesive. For the bonding, it is difficult to ensure consistency when bonding on a very small inclined surface. Uneven adhesive thickness will cause changes in the angle of the reflective surface, affecting the display and reducing product yield. In addition to the two reasons mentioned above, there is an adhesive layer between the inclined surface and the reflective surface. Surface defects can occur at the junction of the waveguide's upper and lower surfaces and the adhesive layer in the finished product. Coupled light can be affected by these surface defects, resulting in ghosting and poor display quality. In this embodiment, the reflective surface and the beam-splitting surface adopt the aforementioned structure, solving the problems of processing angle accuracy, adhesive refractive index matching, and bonding process. Furthermore, since the adhesive line is on the non-light-transmitting path side of the reflective surface, the influence of surface defects at the adhesive line can be avoided, improving product yield and display effect.

[0147] This embodiment also provides an augmented reality display device, including an optical engine module and the optical waveguide device described in any of the above embodiments. The augmented reality display device of this embodiment can improve color uniformity, reduce color shift, and help improve display quality.

[0148] The optical waveguide device and augmented reality display device provided by the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the present invention.

Claims

1. An optical waveguide device, characterized in that, This includes waveguide substrate, coupling structure, coupling structure, and diffraction structure; The waveguide substrate is provided with at least one of the coupling structures, which are used to allow incident light to enter the waveguide substrate and propagate within the waveguide substrate. The waveguide substrate is provided with at least one of the diffraction structures, which are used to diffract and redirect the propagating light in the waveguide substrate, so that the diffracted light with different diffraction angles propagates in the waveguide substrate and towards the coupling structure. The waveguide substrate includes at least two waveguide layers. Any two adjacent waveguide layers include a first waveguide layer and a second waveguide layer. The first waveguide layer and the second waveguide layer have an interface, such that when the diffracted light propagating in the waveguide substrate is incident from the first waveguide layer to the interface between the first waveguide layer and the second waveguide layer, it is partially reflected, and when the diffracted light propagating in the waveguide substrate is incident from the second waveguide layer to the interface between the first waveguide layer and the second waveguide layer, it is partially reflected. Alternatively, the first waveguide layer and the second waveguide layer have an interface, such that when the diffracted light propagating in the waveguide substrate is incident from the first waveguide layer to the interface between the first waveguide layer and the second waveguide layer, it undergoes partial reflection, and when the diffracted light propagating in the waveguide substrate is incident from the second waveguide layer to the interface between the first waveguide layer and the second waveguide layer, a portion of the diffracted light undergoes partial reflection and another portion of the diffracted light undergoes total internal reflection. The reflectivity of the interface to the diffracted light increases with the increase of the incident angle of the diffracted light. The waveguide substrate is provided with at least one of the coupling structures, which are used to cause the diffracted light propagating in the waveguide substrate to exit out of the waveguide substrate.

2. The optical waveguide device according to claim 1, characterized in that, The diffraction structure includes a first diffraction optical structure and a second diffraction optical structure; The coupling structure is used to allow incident light to enter the waveguide substrate and propagate along a first dimension within the waveguide substrate to the first diffraction optical structure. The first diffraction optical structure is used to diffract the propagating light within the waveguide substrate, causing diffracted light with different diffraction angles to propagate within the waveguide substrate and then turn to propagate along a second dimension towards the second diffraction optical structure. The second diffraction optical structure is used to diffract and turn the diffracted light with different diffraction angles propagating within the waveguide substrate towards the coupling structure.

3. The optical waveguide device according to claim 2, characterized in that, The waveguide substrate further includes a first region and a second region, the first region and the second region of the waveguide substrate are spliced ​​together, the coupling structure and the first diffractive optical structure are disposed in the first region of the waveguide substrate, and the second diffractive optical structure and the coupling structure are disposed in the second region of the waveguide substrate; The splicing interface between the first region and the second region is parallel to the first dimensional direction, or the angle between the splicing interface between the first region and the second region and the first dimensional direction is greater than 0° and less than 90°, so that the light propagating in the waveguide matrix is ​​deviated from the splicing interface between the first region and the second region and continues to propagate along the first dimensional direction after being diffracted by the first diffractive optical structure. Alternatively, the splicing interface between the first region and the second region is not parallel to the first dimensional direction, and a first film layer is provided at the splicing interface between the first region and the second region, so that the light propagating in the waveguide substrate, after being diffracted by the first diffractive optical structure, continues to propagate along the first dimensional direction, and is totally internally reflected when it is incident on the splicing interface.

4. The optical waveguide device according to claim 2, characterized in that, The waveguide substrate further includes a first region and a second region, the first region and the second region of the waveguide substrate are spliced ​​together, the coupling structure and the first diffractive optical structure are disposed in the first region of the waveguide substrate, the second diffractive optical structure and the coupling structure are disposed in the second region of the waveguide substrate, and the splicing interface of the first region and the second region is not parallel to the thickness direction of the waveguide substrate.

5. The optical waveguide device according to claim 1, characterized in that, A dielectric film is disposed at the interface between the first waveguide layer and the second waveguide layer. The dielectric film is a dielectric film with a single refractive index, and the refractive index of the dielectric film is less than the refractive index of the first waveguide layer and the refractive index of the second waveguide layer. The dielectric film satisfies the condition of suppressed total internal reflection.

6. The optical waveguide device according to claim 1, characterized in that, A dielectric film layer is disposed at the interface between the first waveguide layer and the second waveguide layer, the dielectric film layer comprising at least two films with different refractive indices stacked together.

7. The optical waveguide device according to claim 5 or 6, characterized in that, The reflectivity of the interface to the diffracted light and the incident angle of the diffracted light satisfy the following relationship: As the incident angle of the diffracted light propagating in the waveguide substrate at the interface increases, the rate of change of the reflectivity of the interface to the diffracted light changes from a slow increase to a rapid increase, and then from a rapid increase to a slow decrease.

8. The optical waveguide device according to claim 1, characterized in that, The refractive index of the first waveguide layer is less than that of the second waveguide layer, so that when the diffracted light propagating in the waveguide substrate is incident from the first waveguide layer to the interface between the first waveguide layer and the second waveguide layer, it undergoes partial reflection. When the diffracted light propagating in the waveguide substrate is incident from the second waveguide layer to the interface between the first waveguide layer and the second waveguide layer, a portion of the diffracted light undergoes partial reflection and another portion of the diffracted light undergoes total internal reflection.

9. The optical waveguide device according to claim 8, characterized in that, When the diffracted light propagating in the waveguide substrate is incident from the second waveguide layer to the interface between the first waveguide layer and the second waveguide layer, the diffracted light undergoes partial reflection when the incident angle of the diffracted light is less than a preset angle, and undergoes total internal reflection when the incident angle of the diffracted light is greater than or equal to the preset angle.

10. The optical waveguide device according to claim 1, characterized in that, The reflectivity of the interface to the diffracted light and the incident angle of the diffracted light satisfy the following relationship: The reflectivity of the interface to the diffracted light with an incident angle between 0° and 30° is greater than 0 and less than 5%. The reflectivity of the interface to the diffracted light with an incident angle between 30° and 50° is greater than or equal to 1% and less than 30%. The reflectivity of the interface to the diffracted light with an incident angle between 50° and 90° is greater than or equal to 10% and less than or equal to 100%.

11. The optical waveguide device according to claim 1, characterized in that, The coupling structure includes a reflective surface, which includes: a first inclined surface formed on the waveguide substrate; and a first reflective film deposited on the first inclined surface. The first reflective film is deposited on the first inclined surface after the first inclined surface is formed on the waveguide substrate.

12. The optical waveguide device according to claim 1, characterized in that, The waveguide substrate includes a first waveguide substrate and a second waveguide substrate. The first waveguide substrate is provided with the coupling-in structure, the coupling-out structure and the diffraction structure, and the second waveguide substrate is provided with the coupling-in structure, the coupling-out structure and the diffraction structure. The diffraction structure of the first waveguide substrate includes a third diffraction optical structure and a fourth diffraction optical structure. The coupling structure of the first waveguide substrate is used to allow incident light to enter the waveguide substrate and propagate along the third dimension within the waveguide substrate to the third diffraction optical structure. The third diffraction optical structure is used to diffract the propagating light within the waveguide substrate, causing diffracted light with different diffraction angles to propagate within the waveguide substrate and then turn to propagate along the fourth dimension towards the fourth diffraction optical structure. The fourth diffraction optical structure is used to diffract and turn the diffracted light with different diffraction angles propagating within the waveguide substrate towards the coupling structure of the first waveguide substrate. The first waveguide substrate includes a third region and a fourth region. The third region of the first waveguide substrate is provided with the coupling structure and the third diffraction optical structure, and the fourth region of the first waveguide substrate is provided with the fourth diffraction optical structure and the coupling structure. The diffraction structure of the second waveguide substrate includes a fifth diffraction optical structure and a sixth diffraction optical structure. The coupling structure of the second waveguide substrate is used to allow incident light to enter the waveguide substrate and propagate along the fifth dimension within the waveguide substrate to the fifth diffraction optical structure. The fifth diffraction optical structure is used to diffract the propagating light within the waveguide substrate, causing diffracted light with different diffraction angles to propagate within the waveguide substrate and then turn to propagate along the sixth dimension towards the sixth diffraction optical structure. The sixth diffraction optical structure is used to diffract and turn the diffracted light with different diffraction angles propagating within the waveguide substrate towards the coupling structure. The second waveguide substrate includes a fifth region and a sixth region. The fifth region of the second waveguide substrate is provided with the coupling structure and the fifth diffraction optical structure, and the sixth region of the second waveguide substrate is provided with the sixth diffraction optical structure and the coupling structure. The first waveguide substrate and the second waveguide substrate are stacked, and the projection of the third region of the first waveguide substrate along the stacking direction coincides with the projection of the sixth region of the second waveguide substrate along the stacking direction. The projection of the fourth region of the first waveguide substrate along the stacking direction coincides with the projection of the fifth region of the second waveguide substrate along the stacking direction. The coupling structure, coupling structure, the third diffraction optical structure and the fourth diffraction optical structure of the first waveguide substrate are symmetrical to the coupling structure, coupling structure, fifth diffraction optical structure and sixth diffraction optical structure of the second waveguide substrate in sequence.

13. An augmented reality display device, characterized in that, It includes an optomechanical module and an optical waveguide device as described in any one of claims 1 to 12.

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