CN212540775U - Optical waveguide device and AR display apparatus - Google Patents
Optical waveguide device and AR display apparatus Download PDFInfo
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- CN212540775U CN212540775U CN202021683994.9U CN202021683994U CN212540775U CN 212540775 U CN212540775 U CN 212540775U CN 202021683994 U CN202021683994 U CN 202021683994U CN 212540775 U CN212540775 U CN 212540775U
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Abstract
The utility model discloses an optical waveguide device, which comprises a waveguide unit, an in-coupling grating arranged at the end part of the waveguide unit and an out-coupling grating arranged on the waveguide unit; the coupling grating is used for diffracting and coupling the projection light into the waveguide unit and enabling the projection light to be conducted in a total reflection mode in the waveguide unit, wherein a plurality of first inert metal nano layers distributed at intervals are arranged on the surface, irradiated by the projection light, of the coupling grating, and the first inert metal nano layers comprise tip structures. The plurality of first inert metal nano layers distributed at intervals are arranged on the grating surface of the coupling-in grating, so that the electric field of incident light waves is locally amplified, the energy of the coupling-in light waves diffracted by the coupling-in grating is improved, the diffraction efficiency of the coupling-in grating is improved, and the light energy use efficiency of the light waveguide device on projection light is improved to a certain degree. The application also provides an AR display device which has the beneficial effects.
Description
Technical Field
The utility model relates to an optical waveguide technical field especially relates to an optical waveguide device and AR display device.
Background
Augmented Reality (AR) is a sensory experience beyond reality, which is achieved by superimposing a computer-generated prompt message, a virtual object or a virtual scene into the real world through an optical system and sensing by human organs. AR technology is now widely used in gaming, retail, education, industry, and medical fields.
Optical waveguides are one of the key components in current conventional AR display devices. The optical waveguide realizes light propagation by utilizing grating coupling-in and coupling-out optical waveguides, and the coupling efficiency of the optical waveguide is determined by the diffraction efficiency of the coupling-in optical grating, so that the energy of the optical waves which can be coupled out from the optical waveguide is determined. The in-coupling grating diffraction efficiency limits the optical energy usage efficiency of the optical waveguide for the projection light.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing an optical waveguide device and AR display device has promoted the utilization ratio of optical waveguide device to the projection light of projection ray apparatus output, and then has promoted the demonstration luminance of projection picture.
In order to solve the above technical problem, the present invention provides an optical waveguide device, including a waveguide unit, an incoupling grating disposed at an end of the waveguide unit, and an outcoupling grating disposed on the waveguide unit;
the coupling grating is used for diffracting and coupling projection light into the waveguide unit and enabling the projection light to be conducted in the waveguide unit in a total reflection mode, wherein a plurality of first inert metal nano layers distributed at intervals are arranged on the surface, irradiated by the projection light, of the coupling grating, and the first inert metal nano layers comprise a sharp-end structure.
In an optional embodiment of the present application, each of the first inert metal nanolayers is periodically spaced at a predetermined pitch.
In an optional embodiment of the present application, the first inert metal nanolayer is disposed on a convex portion and/or a concave portion of the surface of the incoupling grating.
In an optional embodiment of the present application, a distribution period of the first noble metal nanolayer is equal to a grating period of the incoupling grating.
In an alternative embodiment of the present application, the thickness of the first noble metal nanolayer is between 5nm and 1000 nm; the size of the first inert metal nano layer in the direction from the coupled-in grating to the coupled-out grating is not more than the central wavelength of the projection light on the plane parallel to the coupled-in grating.
In an optional embodiment of the present application, the first noble metal nanolayer is one or more of a gold nanolayer, a silver nanolayer, or a platinum nanolayer.
In an optional embodiment of the present application, the coupling-out grating is a reflection diffraction grating, and the coupling-out grating is attached to the surface of the waveguide unit and is provided with a plurality of second inert metal nano layers distributed at intervals.
The application also provides an AR display device, which comprises the optical waveguide device and the projection light machine.
The utility model provides an optical waveguide device, which comprises a waveguide unit, an in-coupling grating arranged at the end part of the waveguide unit, and an out-coupling grating arranged on the waveguide unit; the coupling grating is used for diffracting and coupling the projection light into the waveguide unit and enabling the projection light to be conducted in a total reflection mode in the waveguide unit, wherein a plurality of first inert metal nano layers distributed at intervals are arranged on the surface, irradiated by the projection light, of the coupling grating, and the first inert metal nano layers comprise tip structures.
In the optical waveguide device of the application, a plurality of first inert metal nano-layers distributed at intervals are arranged on the surface of the grating coupled into the grating, the first inert metal nano-layers comprise tip structures, the tip structures of the first inert metal nano-layers have a local amplification effect on the electric field of incident light waves, the energy of the light waves coupled into the grating by diffraction is further improved, the diffraction efficiency of the coupled-into grating is improved, and the light energy use efficiency of the optical waveguide device on projection light is improved to a certain degree.
The application also provides an AR display device which has the beneficial effects.
Drawings
In order to clearly illustrate the embodiments or technical solutions of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a schematic structural diagram of an optical waveguide device provided in an embodiment of the present application;
FIG. 2a is a schematic partial structure diagram of a first noble metal nanolayer on an incoupling grating according to an embodiment of the present application;
FIG. 2b is a schematic diagram of another partial structure of a first noble metal nanolayer coupled onto a grating according to an embodiment of the present application;
fig. 2c is another partial structural diagram of the first noble metal nanolayer on the incoupling grating according to the embodiment of the present application.
Detailed Description
At present, gratings such as an embossed grating and a volume holographic grating are commonly used as coupling gratings in an optical waveguide, but the embossed grating has low diffraction efficiency, and the volume holographic grating has high local diffraction efficiency, but only shows high diffraction efficiency for a specific wavelength and shows low average diffraction efficiency on a broad spectrum due to strong wavelength selectivity.
In the AR display device, it is obvious that the spectral range of the projection light is wide, that is, it is difficult to achieve a high diffraction efficiency of the projection light of all the wavelength bands projected by the projector.
Therefore, the technical scheme of the light energy utilization rate of the projection light output by the optical waveguide to the projection light machine can be improved.
In order to make the technical field better understand the solution of the present invention, the following detailed description of the present invention is provided with reference to the accompanying drawings and the detailed description. It is to be understood that the embodiments described are only some embodiments of the invention, and not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
As shown in fig. 1 to 2c, fig. 1 is a schematic structural diagram of an optical waveguide device provided in an embodiment of the present application, and fig. 2a to 2c are schematic structural diagrams of three different local structures of a first inert metal nanolayer on an incoupling grating provided in an embodiment of the present application, where the optical waveguide device may include:
the optical waveguide comprises a waveguide unit 1, an incoupling grating 2 arranged at the end part of the waveguide unit 1 and an outcoupling grating 3 arranged on the waveguide unit 1;
the coupling-in grating 2 is used for diffracting the projection light and coupling the projection light into the waveguide unit 1, and the projection light is totally reflected and conducted in the waveguide unit 1;
wherein, a plurality of first inert metal nano-layers 21 are arranged on the surface of the incoupling grating 2 receiving the projection light irradiation at intervals, and the first inert metal nano-layers 21 comprise tip structures.
It should be noted that the tip structure of the first noble metal nanolayers 21 referred to in this embodiment is relative to the optical wave electric field, and is not limited to the tips of the sawtooth structure, and each first noble metal nanolayer 21 itself may have a smaller size, and the edge relative to the optical wave electric field is the tip structure.
For example, the first inert metal nanolayer 21 itself is a circular sheet with a radius of 200nm, and although there may be no definite tip point, the light wave electric field with respect to the projected light also corresponds to a tip structure, and local amplification of the electric field can be achieved.
Optionally, the thickness of the first inert metal nanolayer 21 is 5nm to 1000 nm; the dimension of the first inert metal nanolayer 21 in the direction from the incoupling grating to the outcoupling grating on the plane parallel to the incoupling grating is not more than the central wavelength of the projection light.
For example, if the direction of the coupling-in grating pointing to the coupling-out grating is set to be a first direction on a plane parallel to the coupling-in grating, the first inert metal nano layer may be a strip-shaped metal nano layer perpendicular to the first direction, and the width dimension in the first direction is smaller than the central wavelength of the projection light; the first noble metal nanolayer 21 may also be a cubic structure with side dimensions smaller than the center wavelength of the projected light.
Generally, the shape of the tip can be formed by setting the shape and size of the first noble metal nanolayer 21, and the specific shape and structure of the first noble metal nanolayer 21 are not limited in this application.
As shown in fig. 1, the projection light carrying the virtual image information in the projection light engine 4 is incident into the waveguide unit 1 and is diffracted at the interface between the waveguide unit 1 and the coupling grating 2, so that the diffracted projection light is totally reflected and conducted inside the waveguide unit 1; when the projection light in the waveguide unit 1 is incident on the interface between the coupling grating 3 and the waveguide unit 1, one part of the projection light can be reflected and the other part can be diffracted, so that the light of the reflected part is continuously transmitted in the waveguide unit 1 by total reflection, and the projection light of the diffracted part can be coupled out of the waveguide unit 1 and captured by human eyes to form a projection display image.
Light waves belong to electromagnetic waves, and the conduction of projection light can be regarded as the conduction of electric field energy and magnetic field energy. In this embodiment, a plurality of first inert metal nano-layers 21 are disposed at intervals on the incoupling grating 2, and when the projection light irradiates the surface of the incoupling grating 2, the metal nanoparticles on the surface of the first inert metal nano-layers 21 can generate surface plasmon resonance elements. When the size of the first noble metal nanolayer 21 is in the sub-wavelength level (the wavelength is the central wavelength of the projection light), the free electrons inside the surface plasmon resonance element resonate with the light wave of the projection light, so that a new electric field is generated by the oscillation of the free electrons, the new electric field also forms light waves in the space, and the generated light waves can enhance the local light intensity near the surface of the first noble metal nanolayer 21 to a great extent. The first inert metal nanolayer can be equivalently considered to simultaneously amplify the local electric field of the coupled-out grating, focus the light wave electric field which is more uniformly distributed in the original free space in the coupled-in grating 2 and increase the total energy of the light wave electric field of the projection light coupled into the coupled-in grating 2. The incoupling grating 2 itself has the function of amplifying the electric field in a particular direction. Due to the influence of the periodic structure of the incoupling grating 2, the incoupling grating 2 can amplify the light wave electric field energy in the diffraction direction in a coherent constructive manner of the light wave electric field, and the incoupling grating 2 can reduce the light wave electric field energy in the non-diffraction direction in a coherent destructive manner of the light wave electric field. The locally amplified electric field formed by the surface plasmon elements of the first inert metal nanolayer 21 in the coupled-in grating 2 has no special directionality, but increases the total amount of the electric field energy of the light wave coupled into the grating 2. The coupling-in grating 2 releases the locally amplified light wave electric field into the space in the diffraction direction of the grating to form diffraction light with larger energy.
In addition, the amplification effect of the first inert metal nanolayer 21 on the local optical wave electric field is closely related to the scale of the first inert metal nanolayer 21. Within a certain spatial volume range, the more sharp the position, the more obvious the local light amplification is on the first inert metal nanolayer 21; there is no or very little local light amplification on the large area, large scale first noble metal nanolayer 21. Therefore, when the first inert metal nano-layer 21 is disposed on the surface of the incoupling grating 2, the first inert metal nano-layer 21 is discontinuously disposed on the surface of the incoupling grating 2 in a small area. The first inert metal nanolayers 21 have dimensions on the order of sub-wavelength in the length and width dimensions, and the first inert metal nanolayers 21 are spaced apart. Therefore, the sub-wavelength first noble metal nano-layer 21 has a strong local light amplification effect, and a certain space provides a certain free space for local light intensity, so as to avoid the secondary influence of the adjacent first noble metal nano-layer 21. It can be equivalently considered that the first inert metal nanolayer 21 can wholly amplify the local electric field coupled into the grating 2, and focus the electric field distributed more uniformly in the original free space into the grating 2, thereby increasing the total amount of electric field energy coupled into the grating 2. Therefore, compared with the conventional incoupling grating, the incoupling grating 2 plated with the first noble metal nano-layer 21 enhances the beam energy in the diffraction direction, and the ratio of the beam energy in the diffraction direction to the total incident electric field energy is the diffraction efficiency of the incoupling grating 2, so the incoupling grating 2 plated with the first noble metal nano-layer 21 has higher diffraction efficiency.
In summary, in the optical waveguide device of the present application, the first inert metal nano-layer 21 can effectively improve the overall diffraction efficiency of the incoupling grating 2, that is, the energy of the projection light in the incoupling waveguide unit 1 is improved, thereby improving the brightness and light energy of the image entering human eyes.
As mentioned above, the first inert metal nanolayers 21 in this application are arranged at intervals, and since the coherent constructive process of the coupled grating 2 keeps the same optical field energy distribution and the same optical field phase distribution in different grating period segments, so as to obtain a good interference result, and ensure the stability of the diffraction efficiency between different grating period segments, the first inert metal nanolayers 21 can be arranged at intervals according to a predetermined interval on the surface of the coupled grating 2, so that the local light intensity generated by the first inert metal nanolayers 21 also has periodicity, and each grating period segment also has the same optical field energy distribution and optical field phase distribution. This same optical field distribution will have a stable, uniform diffraction efficiency under coherent constructive effects of the incoupling grating 2.
It is understood that the spacing between the adjacent first noble metal nanolayers 21 in this embodiment refers to the pitch of the adjacent first noble metal nanolayers 21 in the plane parallel to the surface of the incoupling grating 2, and the pitch of each first noble metal nanolayer 21 in the direction perpendicular to the incoupling grating 2 is related to the grating structure of the surface of the incoupling grating 2.
The incoupling grating in this embodiment may be an embossed grating or may be a volume holographic grating. Take a relief grating as an example. Since the grating period of the incoupling grating 2 is also of the sub-wavelength order, the grating period of the incoupling grating 2 and the distribution period of the first noble metal nanolayer 21 can be set to be the same. In the simplest manner, as shown in fig. 2a to 2c, the first inert metal nano layer 21 is disposed on the convex portion or the concave portion of the surface of the coupling grating 2, or the first inert metal nano layer 21 may be disposed on the surface of the convex portion and the concave portion of the surface of the coupling grating 2, as long as the size of the first inert metal nano layer 21 is in the sub-nanometer level, and the specific distribution manner of the first inert metal nano layer 21 is not particularly limited in this application.
In addition, the first inert metal nanolayer 21 may adopt one or more nanolayers of a gold nanolayer, a silver nanolayer, or a platinum nanolayer, which is not particularly limited in this application.
As described above, the projection light coupled into the waveguide unit 1 through the incoupling grating 2 needs to be incident to the interface between the waveguide unit 1 and the outcoupling grating 3 through multiple total reflections, and part of the projection light is diffracted and coupled out to human eyes through the diffraction effect of the outcoupling grating 3. If the outcoupling grating 3 is a reflective diffraction grating rather than a transmissive diffraction grating, as shown in fig. 1, the projection light diffracted by the outcoupling grating 3 needs to be transmitted and emitted to the human eye through the waveguide element 1 again, and when the projection light is diffracted by the outcoupling grating 3, a part of the light is also transmitted and coupled out of the waveguide unit 1 from the outcoupling grating 3, which causes energy loss, so that second inert metal nano-layers may be disposed on the surface of the outcoupling grating 3 at intervals, and the size and working principle of the second inert metal nano-layer and the first inert metal nano-layer 21 are similar, which is not described in detail in this embodiment.
However, since the coupling-in grating 2 and the coupling-out grating 3 have different diffraction efficiency requirements, the distribution interval between the respective second noble metal nanolayers and the distribution interval between the first noble metal nanolayers 21 are not the same. For the outcoupling grating 3, the outcoupling effect of the entire outcoupling grating 3 can be optimized by changing the parameters of the second noble metal nanolayer such as the area size, the shape, the interval, the kind, and the like, and designing gratings with different diffraction efficiencies, which will not be discussed in detail herein.
The application also provides AR display equipment, and the AR display equipment comprises the optical waveguide device and the projection light machine.
The inert metal nano layer is arranged on the coupling grating 2 in the optical waveguide device in the embodiment, so that the projection light of the projection optical machine 4 incident to the optical waveguide device is amplified to local light waves due to the inert metal nano layer on the coupling grating 2, the diffraction efficiency of the coupling grating 2 to the projection light is improved, the utilization rate of the optical waveguide device to the projection light of the projection optical machine 4 is further improved, a virtual image output by the AR display device is brighter and clearer, and the good display effect of the AR display device is ensured.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Furthermore, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include elements inherent in the list. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element. In addition, parts of the above technical solutions provided in the embodiments of the present application, which are consistent with the implementation principles of corresponding technical solutions in the prior art, are not described in detail so as to avoid redundant description.
The embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same or similar parts among the embodiments are referred to each other. The principles and embodiments of the present invention have been explained herein using specific examples, and the above descriptions of the embodiments are only used to help understand the method and its core ideas of the present invention. It should be noted that, for those skilled in the art, without departing from the principle of the present invention, the present invention can be further modified and modified, and such modifications and modifications also fall within the protection scope of the appended claims.
Claims (8)
1. An optical waveguide device comprising a waveguide unit, an incoupling grating provided at an end of the waveguide unit, an outcoupling grating provided on the waveguide unit;
the coupling grating is used for diffracting and coupling projection light into the waveguide unit and enabling the projection light to be conducted in the waveguide unit in a total reflection mode, wherein a plurality of first inert metal nano layers distributed at intervals are arranged on the surface, irradiated by the projection light, of the coupling grating, and the first inert metal nano layers comprise a pointed end structure.
2. The optical waveguide device according to claim 1 wherein each of said first noble metal nanolayers is periodically spaced at a predetermined pitch.
3. The optical waveguide device according to claim 2, wherein the first noble metal nanolayer is disposed on raised and/or recessed portions of the surface of the incoupling grating.
4. The optical waveguide device of claim 2 wherein the first noble metal nanolayer has a period of distribution equal to the grating period of the incoupling grating.
5. The optical waveguide device according to claim 2 wherein the thickness of said first noble metal nanolayer being between 5nm and 1000 nm; the first inert metal nano layer is arranged on a plane parallel to the position of the coupled-in grating, and the size of the coupled-in grating in the direction towards the coupled-out grating is not larger than the central wavelength of the projection light.
6. The optical waveguide device according to claim 1 wherein said first noble metal nanolayer being one or more nanolayers of a gold nanolayer, a silver nanolayer, or a platinum nanolayer.
7. The optical waveguide device according to any of claims 1 to 6, wherein the outcoupling grating is a reflective diffraction grating, and a plurality of second noble metal nanolayers are disposed at intervals on the surface of the outcoupling grating, which is attached to the waveguide unit.
8. An AR display apparatus comprising the light guide device according to any one of claims 1 to 7 and a projector light machine.
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| CN202021683994.9U CN212540775U (en) | 2020-08-13 | 2020-08-13 | Optical waveguide device and AR display apparatus |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114527536A (en) * | 2022-03-04 | 2022-05-24 | 深圳珑璟光电科技有限公司 | Optical waveguide, manufacturing method thereof and head-up display |
| CN115166885A (en) * | 2022-09-09 | 2022-10-11 | 荣耀终端有限公司 | Diffraction grating structure, preparation method, imaging device and head-mounted equipment |
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2020
- 2020-08-13 CN CN202021683994.9U patent/CN212540775U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114527536A (en) * | 2022-03-04 | 2022-05-24 | 深圳珑璟光电科技有限公司 | Optical waveguide, manufacturing method thereof and head-up display |
| CN115166885A (en) * | 2022-09-09 | 2022-10-11 | 荣耀终端有限公司 | Diffraction grating structure, preparation method, imaging device and head-mounted equipment |
| CN115166885B (en) * | 2022-09-09 | 2023-02-17 | 荣耀终端有限公司 | Diffraction grating structure, preparation method, imaging device and head-mounted equipment |
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