CN117761822A - Optical waveguide device and head-mounted display device - Google Patents

Abstract

The embodiment of the application discloses an optical waveguide device and head-mounted display equipment, wherein the optical waveguide device comprises a waveguide substrate, and a coupling-in grating and a coupling-out grating which are arranged on the waveguide substrate; the coupling-in grating at least comprises one-dimensional grating, and the period of the coupling-in grating in the grating vector direction is T0; the coupling-out grating comprises at least one two-dimensional grating, and the coupling-out grating has a first period T1 in a first direction and a second period T2 in a second direction perpendicular to the first direction; the first direction is the same as the grating vector direction of the coupling-in grating, and the first period T1 is adjusted to be the same as the period T0 of the coupling-in grating, so that the two-dimensional pupil expansion angle of the incident light vertically incident to the coupling-in grating is 90 °. One technical effect of the embodiments of the present application is to reduce light leakage and improve the light transmission effect of the optical waveguide device.

Description

Optical waveguide device and head-mounted display device

Technical Field

The application belongs to the technical field of optical devices, and particularly relates to an optical waveguide device and head-mounted display equipment.

Background

With the continuous development of AR technology, the application range of AR technology is gradually expanding. Diffractive optical waveguides are widely used in AR display devices. In the prior art, by arranging a turning area on a waveguide substrate and arranging a pupil expansion grating in the turning area, light propagating in the waveguide substrate is expanded and coupled out through a coupling-out area, but the light can spread the coupling-out area after passing through a section of transmission path in the pupil expansion process, and part of energy can be lost in the transmission process.

Disclosure of Invention

The embodiment of the application aims to provide a novel technical scheme of an optical waveguide device and a head-mounted display device.

According to a first aspect of embodiments of the present application, there is provided an optical waveguide device comprising a waveguide substrate, and an in-coupling grating and an out-coupling grating disposed on the waveguide substrate;

the coupling-in grating at least comprises one-dimensional grating, and the period of the coupling-in grating in the grating vector direction is T0; the coupling-in grating is used for coupling incident light into the waveguide substrate;

the coupling-out grating comprises at least one two-dimensional grating, and the coupling-out grating has a first period T1 in a first direction and a second period T2 in a second direction perpendicular to the first direction; the first direction is the same as the grating vector direction of the coupling-in grating, and the first period T1 is adjusted to be the same as the period T0 of the coupling-in grating, so that the two-dimensional pupil expansion angle of the incident light vertically incident to the coupling-in grating is 90 °.

Optionally, the coupling-out grating comprises a grating array formed by a plurality of grating units, wherein the grating units comprise at least two pairs of straight sides which are parallel and have different normal vectors.

Optionally, the grating unit is diamond-shaped.

Optionally, the period T0 of the coupling-in grating is 200nm-600nm, the first period T1 of the coupling-out grating is 200nm-600nm, and the second period T2 of the coupling-out grating is 150nm-700nm.

Optionally, the grating vector of the coupling-in grating is K0, the grating vectors of the coupling-out grating are K1 and K2, respectively, and the K0, K1 and K2 form a closed vector triangle.

Optionally, the coupling-in grating includes two symmetrically arranged one-dimensional gratings, and the two one-dimensional gratings are arranged at intervals, adjacent to each other or at least partially overlapped on the waveguide substrate.

Optionally, the in-coupling grating and the out-coupling grating are co-located on the same surface of the waveguide substrate to form a reflective diffractive optical waveguide; or,

the coupling-in grating and the coupling-out grating are respectively positioned on two surfaces opposite to the waveguide substrate to form a transmission type diffraction optical waveguide.

Optionally, at least one of the in-coupling grating and the out-coupling grating is a holographic grating or a photonic crystal grating.

Optionally, the out-coupling grating is provided as one or more.

According to a second aspect of embodiments of the present application, there is also provided a head-mounted display device including the optical waveguide device of the first aspect.

The beneficial effects of the embodiment of the application are that:

in this embodiment of the present invention, by setting the coupling-out grating including at least one two-dimensional grating, and adjusting the first period T1 of the coupling-out grating in the first direction to be the same as the period T0 of the coupling-in grating, the two-dimensional pupil expansion angle of the incident light vertically incident to the coupling-in grating is 90 ° so that when the light is transmitted to the coupling-out grating, diffraction can be directly performed on the surface of the waveguide substrate along the direction perpendicular to the incident light, thereby avoiding the pupil expansion area of the additional longitudinal transmission distance, reducing additional energy leakage, avoiding the additional setting of the pupil expansion area along the first direction, concentrating most of the energy of the light in the necessary coupling-out area, and improving the efficiency of the waveguide overall system.

Other features of the present application and its advantages will become apparent from the following detailed description of exemplary embodiments of the present application, which proceeds with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description, serve to explain the principles of the application.

FIG. 1 is an optical path diagram of an optical waveguide device provided in an embodiment of the present application;

FIG. 2 is a block diagram of an optical waveguide device according to an embodiment of the present application;

FIG. 3 is a second block diagram of an optical waveguide device according to an embodiment of the present disclosure;

FIG. 4 is a third block diagram of an optical waveguide device according to an embodiment of the present disclosure;

fig. 5 is a diagram illustrating a structure of an optical waveguide device according to an embodiment of the present application.

Reference numerals illustrate: 100. a waveguide substrate; 111. coupling into the grating; 121. coupling out the grating; 1201. a grating unit; 1001. a first diffracted light; 1002. a second diffracted light; 1003. a third diffracted light; 1004. a first light-out coupling; 1005. and fourth diffracting light.

Detailed Description

Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present application unless it is specifically stated otherwise.

The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the application, its application, or uses.

Techniques, methods, and apparatus known to one of ordinary skill in the relevant art may not be discussed in detail, but are intended to be part of the specification where appropriate.

In all examples shown and discussed herein, any specific values should be construed as merely illustrative, and not a limitation. Thus, other examples of exemplary embodiments may have different values.

It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further discussion thereof is necessary in subsequent figures.

An embodiment of the present application provides an optical waveguide device, referring to fig. 1, where the optical waveguide device includes a waveguide substrate 100, and an in-coupling grating 111 and an out-coupling grating 121 disposed on the waveguide substrate 100;

the coupling-in grating 111 comprises at least one-dimensional grating, the period of the coupling-in grating 111 in the grating vector direction is T0, and the coupling-in grating 111 is used for coupling incident light into the waveguide substrate 100;

the coupling-out grating 121 comprises at least one two-dimensional grating, the coupling-out grating 121 having a first period T1 in a first direction and a second period T2 in a second direction perpendicular to the first direction; the first direction is the same as the direction of the grating vector of the coupling-in grating 111, and the first period T1 is adjusted to be the same as the period T0 of the coupling-in grating 111, so that the two-dimensional pupil expansion angle of the incident light perpendicularly incident to the coupling-in grating 111 on the coupling-out grating 121 is 90 °.

In the optical waveguide device of the embodiment, the waveguide substrate 100 includes two first surfaces and two second surfaces disposed opposite to each other, and the in-coupling grating 111 and the out-coupling grating 121 may be disposed on at least one of the first surfaces and the second surfaces of the waveguide substrate 100. The arrangement of the in-coupling grating 111 and the out-coupling grating 121 on the waveguide substrate 100 is not limited in this embodiment, that is, the arrangement of the in-coupling grating 111 and the out-coupling grating 121 on the same surface, such as the first surface, of the waveguide substrate 100 is included but not limited to that shown in fig. 1.

The optical waveguide device of the embodiments of the present application, which is coupled into the grating 111, comprises at least one-dimensional grating. That is, including but not limited to that shown in fig. 2, the incoupling grating 111 is composed of one-dimensional grating. Also included, but not limited to, is shown in fig. 3, the incoupling grating 111 is comprised of two one-dimensional gratings. Of course, the coupling-in grating 111 may also consist of a one-dimensional grating and a two-dimensional grating. The specific structure of the coupling-in grating 111 is not limited in this application, as long as the coupling-in grating 111 can couple incident light into the waveguide substrate 100.

The incoupling grating 111 has a grating vector in a direction, for example, perpendicular to the grating lines, which is the direction in which the incoupling grating 111 periodically varies, the length of which is equal to the inverse of the grating period of the incoupling grating 111.

The optical waveguide device of the embodiments of the present application, the outcoupling grating 121 comprises at least one two-dimensional grating. That is, including but not limited to that shown in fig. 1, the out-coupling grating 121 is composed of one two-dimensional grating. Of course, the coupling-out grating 121 may also consist of a two-dimensional grating and a one-dimensional grating.

The coupling-out grating 121 has two grating vectors in different directions, which are perpendicular to each other, or may be any set angle. For example, the out-coupling gratings 121 are periodically distributed in both the horizontal and vertical directions.

In the embodiment of the present application, the period of the coupling-in grating 111 in the grating vector direction is T0, the coupling-out grating 121 has a first period T1 in the first direction, and the coupling-out grating 121 has a second period T2 in the second direction, wherein the second direction is perpendicular to the first direction, and the first direction is the same as the grating vector direction of the coupling-in grating 111, and in the first direction, the period T1 of the coupling-out grating 121 is preferably the same as the period T0 of the coupling-in grating 111, so that the two-dimensional pupil expansion angle of the incident light perpendicularly incident to the coupling-in grating 111 in the coupling-out grating 121 is 90 °.

In a specific embodiment, the period T0 of the coupling-in grating 111 is 200nm-600nm, the first period T1 of the coupling-out grating 121 is 200nm-600nm, and the second period T2 of the coupling-out grating 121 is 150nm-700nm. The light coupled out by the coupling-out grating 121 can completely spread the human eyes, so that the light efficiency utilization rate is improved, and the light-emitting device is suitable for most users and can enable the users to obtain better immersion experience.

Referring to fig. 1, a coupling-in grating 111 and a coupling-out grating 121 are disposed on a waveguide substrate 100, and the coupling-in grating 111 and the coupling-out grating 121 are distributed on the same side surface of the waveguide substrate 100. Taking the structure of the coupling-out grating 121 shown in fig. 1 as an example, the description of the light propagation path is given here by taking pupil-expanding coupling-out of light as an example. Specifically:

an external light is perpendicularly incident to the coupling-in grating 111, and the coupling-in grating 111 couples the light into the waveguide substrate 100, generating a first diffracted light 1001 propagating toward the coupling-out grating 121. When the first diffracted light 1001 is incident on the coupling-out grating 121, the second diffracted light 1002 and the third diffracted light 1003 symmetrically propagating to two sides are generated, and the first coupled-out light 1004 is coupled out. The first diffracted light 1001 continues to propagate in the original direction in the waveguide substrate 100. The angles between the second diffracted ray 1002, the third diffracted ray 1003 and the first diffracted ray 1001 are all 90 °.

The second diffracted light 1002 continues to propagate in the original direction in the waveguide substrate 100, and when the second diffracted light 102 is again incident on the coupling-out grating 121, a fourth diffracted light 1005 is generated and coupled out. The diffraction direction of the fourth diffracted ray 1005 is the same as the first diffracted ray 1001 (both shown in fig. 1 are parallel to each other). And, the second diffracted light 1002 continues to propagate in the original direction within the waveguide substrate 100. Light rays such as the first diffracted light ray 1001 and the fourth diffracted light ray 1005 continue to propagate forward to repeat the foregoing actions, and finally the extended light rays passing through the coupling-out grating 121 will fill the coupling-out area for viewing by human eyes.

The third diffracted light 1003 has the same diffraction behavior as the second diffracted light 1002. Can exhibit a symmetrical state. Finally, after the light rays are pupil-expanded by the left and right coupling-out gratings 121, the emergent light rays will be spread over the coupling-out area for human eyes to watch. Therefore, the visual angle of a user can be enlarged, and the light efficiency utilization rate can be improved.

The waveguide substrate 100 is provided with an outcoupling region, in which an outcoupling grating 121 is arranged, wherein the outcoupling region is generally a rectangular region, and the outcoupling region comprises a longitudinal axis along a first direction and a transverse axis along a second direction. In the prior art, in the grating structure with the two-dimensional pupil expansion angle smaller than 90 degrees, in the light propagation process, in order to completely cover the area corresponding to the transverse axis, a longitudinal distance needs to be propagated along the first direction. Therefore, the light energy leakage in the transmission process is caused, the light efficiency of the optical waveguide device is reduced, in addition, a pupil expansion area for expanding the light along the first direction is required to be arranged, the utilization rate of the coupling-out area is low, and under the same coupling-out effect, a coupling-out area with a larger area is required to be arranged.

In the optical waveguide device of the embodiment of the present application, the first period T1 is adjusted to be the same as the period T0 of the coupling-in grating 111, so that the two-dimensional pupil expansion angle of the incident light vertically incident to the coupling-in grating 111 is 90 ° in the coupling-out grating 121, and thus when the light is transmitted to the coupling-out grating 121, the whole coupling-out area can be directly paved transversely along the second direction, and the viewing area of human eyes can be paved as full as possible. Therefore, extra energy leakage is reduced, the additional arrangement of a pupil expansion area along the first direction is avoided, and most of energy of light is concentrated in a necessary coupling-out area, so that the efficiency of the waveguide overall system is improved.

Referring to fig. 2-3, in the embodiment of the present application, the coupling-out grating includes a grating array formed by a plurality of grating units, where the grating unit 1201 includes at least two pairs of straight sides that are parallel and have different normal vectors.

In the embodiment of the present application, the coupling-out grating 121 may include, for example, a plurality of grating units 1201 (i.e., the smallest repeating unit in the grating array), and the plurality of grating units 1201 may form a grating array having a set shape, and the shape of the formed grating array is not limited in this application.

The grating unit 1201 comprises at least two pairs of straight sides that are parallel and have different normal vectors, that is, including but not limited to the case where the grating unit 1201 comprises two pairs of straight sides that are parallel and have different directions. In the optical waveguide device of the embodiment of the present application, referring to fig. 2, the grating unit 1201 has a diamond shape.

Note that, the grating unit 1201 is not limited to having two pairs of straight sides with different parallel normal vectors forming a quadrangle, but may include three pairs of straight sides with different parallel normal vectors forming a hexagon, and the like, which is not limited in the embodiment of the present application.

In addition, the grating unit 1201 includes a plurality of pairs of straight sides which are parallel and have different normal vectors, and it is also possible to form the grating unit 1201 including a plurality of grating patterns, including but not limited to the grating unit 1201 shown in fig. 3 being two diamond-shaped grating patterns. The specific structure of the grating unit 1201 is not limited in the present application, and a plurality of pairs of straight sides which are parallel and have different normal vectors may form the grating unit 1201 composed of one grating pattern, or may form the grating unit 1201 composed of a plurality of grating patterns.

In this embodiment of the present application, by setting at least two pairs of grating units 1201 with straight sides parallel to each other and different normal vectors, pupil expansion is performed on the light rays propagating in the waveguide substrate 100 in two dimension directions, so that the light rays exiting through the coupling-out grating 121 can be spread on the coupling-out area for viewing by human eyes, thus the visual range of the user is enlarged, which is beneficial to improving the optical transmission efficiency of the optical module, and the immersion feeling of the user when using the optical waveguide device can be improved.

In this embodiment, the grating vector of the coupling-in grating 111 is K0, the grating vectors of the coupling-out grating are K1 and K2, respectively, and the K0, K1 and K2 form a closed vector triangle.

By defining the relationship between the grating vectors of the coupling-in grating 111 and the coupling-out grating 121, the emission angle of the light during coupling-out and the incident angle of the light during coupling-in grating 111 can be ensured to be consistent, chromatic dispersion of the light during propagation can be reduced, the diffraction efficiency of the light can be improved, the waste of the light can be reduced, and the definition of the coupled-out light can be improved.

It should be noted that, in the embodiment of the present application, the number of the coupling-out gratings 121 is not limited to one, but may be two or more. The sum of the vectors of the in-coupling grating 111 and the respective out-coupling grating 121 should satisfy the vector sum as 0.

In this embodiment, the coupling-in grating 111 includes two symmetrically disposed one-dimensional gratings, and the two one-dimensional gratings are disposed at intervals, adjacent to each other, or at least partially overlapped on the waveguide substrate 100.

For example, referring to fig. 4, the coupling-in grating 111 is formed by two symmetrical one-dimensional gratings, and the two one-dimensional gratings may be partially overlapped or completely separated or completely overlapped or adjacently disposed, so that the field angle FOV of the optical waveguide device may be enlarged, and a user may obtain a good immersion experience when using the optical waveguide device for visual experience.

It should be noted that the overlapping refers to overlapping of the two or more coupling-out gratings 121 in the thickness direction of the waveguide substrate 100. The thickness direction of the waveguide substrate 100, i.e. the direction perpendicular to the first surface and the second surface of the waveguide substrate 100.

In addition, referring to fig. 4-5, the position setting of the coupling-in grating 111 is more flexible, and as shown in fig. 4, the coupling-in grating 111 may be disposed on the symmetry axis of the coupling-out grating 121. As shown in fig. 5, the coupling-in grating 111 may be disposed at an off-axis position of the coupling-out grating 121. The arrangement position of the coupling-in grating 111 is not limited in the present application, as long as the coupling of light into the waveguide substrate 100 can be achieved.

In this embodiment, the coupling-in grating 111 and the coupling-out grating 121 are co-located on the same surface of the waveguide substrate 100 to form a reflective diffraction optical waveguide; or,

the in-coupling grating 111 and the out-coupling grating 121 are respectively located on two surfaces opposite to the waveguide substrate 100 to form a transmissive diffraction optical waveguide.

The optical waveguide device can be flexibly designed as a reflective diffraction optical waveguide or a transmissive diffraction optical waveguide according to requirements, and the specific type of the optical waveguide device is not limited in the embodiment of the application.

In this embodiment, at least one of the in-coupling grating 111 and the out-coupling grating is a holographic grating or a photonic crystal grating.

Wherein, the holographic grating is a grating manufactured by adopting a holographic technique. The optical holographic technology mainly uses the optical coherence superposition principle, namely simply by adjusting complex terms (time terms), so that the peak value of two light wave trains is superposed, and the peak Gu Diejia is obtained, thereby achieving the technology that the coherent field has higher contrast. The coupling-in grating 111 and/or the coupling-out grating 121 manufactured by adopting the holographic grating processing can not generate ghost light when performing light diffraction, the generated stray light is small, and the resolution of the obtained graph light is higher.

Photonic crystal gratings are regular optical structures fabricated from a periodic arrangement of media of different refractive indices. Such materials, because of their photonic band gap, are capable of blocking photons of a specific frequency, thereby affecting the movement of the photons. The coupling-in grating 111 and/or the coupling-out grating 121 manufactured by adopting photonic crystal processing can realize the selection of the wavelength of light, and improve the diffraction effect of the grating.

In this embodiment, the coupling-out grating 121 is one or more.

When the plurality of the coupling-out gratings 121 are provided, each of the coupling-out gratings 121 has a first period T1 in a first direction, and the coupling-out gratings 121 have a second period T2 in a second direction, wherein the second direction is perpendicular to the first direction, and the first direction is identical to the grating vector direction of the coupling-in grating 111, and in the first direction, the period T1 of the coupling-out grating 121 is preferably designed to be identical to the period T0 of the coupling-in grating 111.

It should be noted that, the plurality of out-coupling gratings 121 may be disposed on the same side surface of the waveguide substrate 100, or may be disposed on different side surfaces of the waveguide substrate, and the position of the out-coupling gratings 121 on the waveguide substrate 100 is not limited in this application, so long as the two-dimensional pupil expansion angle of the out-coupling gratings 121 for the incident light vertically incident to the in-coupling gratings 111 is 90 °.

The application also provides a head mounted display device comprising the optical waveguide device as described above.

For example, the head-mounted display apparatus includes a housing, and two optical waveguide devices disposed within the housing, which may correspond to the left and right eyes of a user, respectively.

The head-mounted display device of the embodiment of the application may be, for example, an augmented reality display device, such as AR glasses or AR helmets.

Although specific embodiments of the present application have been described in detail by way of example, it will be appreciated by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present application. It will be appreciated by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the present application. The scope of the application is defined by the appended claims.

Claims (10)

1. An optical waveguide device, characterized by comprising a waveguide substrate (100), and an in-coupling grating (111) and an out-coupling grating (121) arranged on the waveguide substrate (100);

the coupling-in grating (111) comprises at least one-dimensional grating, and the period of the coupling-in grating (111) in the grating vector direction is T0; the coupling-in grating (111) is used for coupling incident light into the waveguide substrate (100);

the out-coupling grating (121) comprises at least one two-dimensional grating, the out-coupling grating (121) having a first period T1 in a first direction and a second period T2 in a second direction perpendicular to the first direction; the first direction is the same as the grating vector direction of the coupling-in grating (111), and the first period T1 is adjusted to be the same as the period T0 of the coupling-in grating (111) so that the two-dimensional pupil expansion angle of the incident light vertically incident to the coupling-in grating (111) on the coupling-out grating (121) is 90 °.

2. The optical waveguide device according to claim 1, characterized in that the out-coupling grating (121) comprises a grating array of a plurality of grating units (1201), wherein the grating units (1201) comprise at least two pairs of straight sides which are parallel and differ in normal vector.

3. The optical waveguide device according to claim 2, wherein the grating elements (1201) are diamond-shaped.

4. The optical waveguide device according to claim 1, characterized in that the period T0 of the incoupling grating (111) is 200-600 nm, the first period T1 of the incoupling grating (121) is 200-600 nm, and the second period T2 of the incoupling grating (121) is 150-700 nm.

5. The optical waveguide device according to claim 1, characterized in that the grating vector of the coupling-in grating (111) is K0, the grating vectors of the coupling-out grating (121) are K1, K2, respectively, the K0, K1 and K2 constituting a closed vector triangle.

6. The optical waveguide device according to claim 1, characterized in that the incoupling grating (111) comprises at least two one-dimensional gratings, and that the at least two one-dimensional gratings are arranged at intervals, adjacently or at least partially overlapping on the waveguide substrate (100).

7. The optical waveguide device according to claim 1, characterized in that the in-coupling grating (111) and the out-coupling grating (121) are co-located on the same surface of the waveguide substrate (100) to form a reflective diffractive optical waveguide; or,

the in-coupling grating (111) and the out-coupling grating (121) are respectively located on two surfaces opposite to the waveguide substrate (100) to form a transmissive diffraction optical waveguide.

8. The optical waveguide device according to claim 1, characterized in that at least one of the in-coupling grating (111) and the out-coupling grating (121) is a holographic grating or a photonic crystal grating.

9. The optical waveguide device according to any of claims 1-8, characterized in that the out-coupling grating (121) is provided in one or more.

10. A head-mounted display device comprising the optical waveguide device of any one of claims 1 to 9.