阅读说明：本技术 光学装置和电子设备 (Optical device and electronic apparatus ) 是由 蒋楚豪 于 2021-08-10 设计创作，主要内容包括：本申请实施例提供一种光学装置和电子设备,光学装置包括：波导,包括相对的第一侧和第二侧；第一衍射光栅,设置于所述波导的第一侧；耦入光栅,设置于所述波导的第二侧,且与所述第一衍射光栅相对设置,所述耦入光栅和所述第一衍射光栅的色散相反；第二衍射光栅,设置于所述波导的第一侧；以及耦出光栅,设置于所述波导的第二侧,且与所述第二衍射光栅相对设置,所述耦出光栅和所述第二衍射光栅的色散相反。对耦入光栅及耦出光栅分别设置对应的色散补偿的光栅,可解决传统单片衍射波导所面临的缺色问题。(An embodiment of the present application provides an optical device and an electronic apparatus, the optical device including: a waveguide comprising opposing first and second sides; a first diffraction grating disposed on a first side of the waveguide; an incoupling grating disposed on a second side of the waveguide and opposite the first diffraction grating, the incoupling grating and the first diffraction grating having opposite dispersions; a second diffraction grating disposed on a first side of the waveguide; and an outcoupling grating disposed on a second side of the waveguide and disposed opposite the second diffraction grating, the outcoupling grating and the second diffraction grating having opposite dispersions. The grating with corresponding dispersion compensation is respectively arranged on the coupling-in grating and the coupling-out grating, so that the problem of color deficiency of the traditional monolithic diffraction waveguide can be solved.)

1. An optical device, comprising:

a waveguide comprising opposing first and second sides;

a first diffraction grating disposed on a first side of the waveguide;

an incoupling grating disposed on a second side of the waveguide and opposite the first diffraction grating, the incoupling grating and the first diffraction grating having opposite dispersions;

a second diffraction grating disposed on a first side of the waveguide; and

and the coupling-out grating is arranged on the second side of the waveguide and is opposite to the second diffraction grating, and the dispersion of the coupling-out grating is opposite to that of the second diffraction grating.

2. The optical device of claim 1, wherein the first diffraction grating is configured to disperse the incident first optical signal into a plurality of monochromatic optical signals;

the coupling grating is used for guiding the plurality of monochromatic light signals into a plurality of monochromatic light signals with the same reflection angle so as to enable the plurality of monochromatic light signals to be conducted in parallel in the waveguide;

the light coupling grating is used for guiding the plurality of monochromatic light signals to the second diffraction grating and intersecting the second diffraction grating;

the second diffraction grating is used for converging the plurality of the single-color light signals which are converged into a second light signal.

3. The optical device of claim 2, wherein the angle of reflection of the plurality of monochromatic light signals within the waveguide is less than a maximum critical angle for total internal reflection in the waveguide and greater than a minimum critical angle for total internal reflection in the waveguide.

4. The optical device as claimed in claim 2, further comprising a turning grating, wherein the waveguide is configured to transmit the plurality of monochromatic light signals guided by the coupling grating to the turning grating, and the turning grating is configured to diffract the plurality of monochromatic light signals into a single-direction expanded pupil beam and transmit the expanded pupil beam to the coupling grating through the waveguide.

5. The optical device according to claim 4, wherein the incoupling grating and the turning grating are disposed at one end of the waveguide and the outcoupling grating is disposed at the other end of the waveguide.

6. The optical device according to claim 1, characterized in that the area of the orthographic projection of the first diffraction grating on said first side is greater than or equal to the area of the orthographic projection of said incoupling grating on said first side; and/or

The area of the orthographic projection of the second diffraction grating on the first side is larger than or equal to the area of the orthographic projection of the coupling-out grating on the first side.

7. The optical device of claim 1, wherein the first diffraction grating comprises one or more bragg gratings; and/or

The second diffraction grating comprises one or more bragg gratings.

8. An optical device according to any one of claims 1-7, wherein the waveguide comprises a first waveguide layer and a second waveguide layer stacked on top of each other, the first diffraction grating and the second diffraction grating being arranged on a side of the first waveguide layer facing away from the second waveguide layer, and the incoupling grating and the outcoupling grating being arranged on a side of the second waveguide layer facing away from the first waveguide layer.

9. An optical device as defined in claim 8, wherein the first waveguide layer and the second waveguide layer are adhesively bonded.

10. An electronic device, comprising:

a housing;

an optical device disposed within the housing, the optical device being as claimed in any one of claims 1-9.

Technical Field

The present application relates to the field of electronic technologies, and in particular, to an optical device and an electronic apparatus.

Background

Augmented Reality (AR) is a technology field which has attracted much attention in recent years, and an AR glasses product is one of the main implementation ways of AR, and its near-eye display system is to form a far virtual image by a series of optical imaging elements from pixels on a display and project the far virtual image into human eyes. AR glasses require perspective (See-through) to See both the real outside world and virtual information, so the imaging system cannot be kept in front of the line of sight. This requires the addition of one or a group of optical combiners to integrate the virtual information with the real scene in a "stacked" fashion. However, the AR glasses in the related art have a problem of color shortage.

Disclosure of Invention

The embodiment of the application provides an optical device and electronic equipment, which can solve the problem of color shortage in the optical signal transmission process.

An embodiment of the present application provides an optical device, which includes:

a waveguide comprising opposing first and second sides;

a first diffraction grating disposed on a first side of the waveguide;

an incoupling grating disposed on a second side of the waveguide and opposite the first diffraction grating, the incoupling grating and the first diffraction grating having opposite dispersions;

a second diffraction grating disposed on a first side of the waveguide; and

and the coupling-out grating is arranged on the second side of the waveguide and is opposite to the second diffraction grating, and the dispersion of the coupling-out grating is opposite to that of the second diffraction grating.

An embodiment of the present application further provides an electronic device, which includes:

a housing;

and the optical device is arranged in the shell and is the optical device.

In the optical device of this application embodiment, be provided with the first diffraction grating that dispersion is opposite and couple in grating and another dispersion is opposite second diffraction grating and couple out grating to couple in the grating with first diffraction grating sets up relatively, couple out the grating with second diffraction grating sets up relatively, sets up the grating of the corresponding dispersion compensation respectively to couple in grating and couple out grating, can solve the scarce look problem that traditional monolithic diffraction waveguide faced.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings used in the description of the embodiments will be briefly introduced below. It is obvious that the drawings in the following description are only some embodiments of the application, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.

For a more complete understanding of the present application and its advantages, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, wherein like reference numerals represent like parts in the following description.

Fig. 1 is a schematic view of a first structure of an optical device according to an embodiment of the present disclosure.

Fig. 2 is a schematic diagram of spectral and angular spectral characteristics of a bragg grating relative to a relief grating according to an embodiment of the present disclosure.

Fig. 3 is a schematic structural diagram of an optical device in the related art.

Fig. 4 is a schematic diagram of the optical transmission in k-space of the optical device shown in fig. 3.

Fig. 5 is a schematic diagram of a second structure of an optical device according to an embodiment of the present application.

Fig. 6 is a schematic diagram of the optical transmission in k-space of the optical device of fig. 5.

Fig. 7 is a schematic diagram illustrating a tilt angle of a grating period corresponding to incident light in the optical device of the present embodiment.

Fig. 8 is another schematic diagram of the optical device of fig. 5 with light transmission in k-space.

FIG. 9 is another schematic view of the optical device shown in FIG. 5.

Fig. 10 is a schematic diagram of a third structure of an optical device according to an embodiment of the present application.

Fig. 11 is a schematic diagram of the optical device of fig. 10 with light transmission in k-space.

Fig. 12 is a schematic diagram of a fourth structure of an optical device according to an embodiment of the present application.

Fig. 13 is a schematic structural diagram of an electronic device according to an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without inventive step, are within the scope of the present application.

An optical device according to an embodiment of the present application is provided, and referring to fig. 1, fig. 1 is a schematic view illustrating a first structure of the optical device according to the embodiment of the present application. The optical device 10 comprises a waveguide 11, a first diffraction grating 12, an incoupling grating 14, a second diffraction grating 18 and an outcoupling grating 16. Waveguide 11 includes opposing first and second sides 112 and 114. A first diffraction grating 12 is arranged on a first side 112 of said waveguide 11. The incoupling grating 14 is arranged on the second side 114 of the waveguide 11 and opposite to the first diffraction grating 12, the dispersion of the incoupling grating 14 and the first diffraction grating 12 being opposite. A second diffraction grating 18 is arranged on a first side 112 of said waveguide 11. An outcoupling grating 16 is arranged on the second side 114 of the waveguide 11 and opposite to the second diffraction grating 18, the dispersion of the outcoupling grating 16 and the second diffraction grating 18 being opposite. The corresponding chromatic dispersion compensation gratings are respectively arranged on the coupling-in grating 14 and the coupling-out grating 16, so that the problem of color deficiency of the traditional monolithic diffraction waveguide 11 can be solved.

The first diffraction grating 12 is configured to disperse an incident first optical signal 22 into a plurality of monochromatic optical signals 24. The incoupling grating 14 is used for guiding the plurality of monochromatic light signals 24 into a plurality of monochromatic light signals 24 with the same reflection angle, so that the plurality of monochromatic light signals 24 are conducted in parallel in the waveguide 11. The outcoupling grating 16 is used for guiding a plurality of monochromatic light signals 24 to the second diffraction grating 18, and the monochromatic light signals meet at the second diffraction grating 18. The second diffraction grating 18 is used to converge the plurality of monochromatic optical signals 24 into a second optical signal 28.

Alternatively, the first and second diffraction gratings 12 and 18 may be Bragg gratings (VBGs). VBG is a diffractive device that uses holographic exposure techniques to form a periodic refractive index modulation on a photosensitive glass. Referring to fig. 2, fig. 2 is a schematic diagram of spectral and angular spectrum characteristics of a bragg grating relative to a relief grating according to an embodiment of the present disclosure. In fig. 2, the abscissa of graph (a) is wavelength and the ordinate is diffraction efficiency, and it can be seen that VBG diffracts only light of a specific wavelength with respect to the relief grating; in fig. 2, the abscissa of graph (b) is the incident angle and the ordinate is the diffraction efficiency, and it can be seen that VBG diffracts only light at a specific incident angle relative to the relief grating. In summary, the period parameter of the VBG can be adjusted to diffract only light with a specific wavelength incident at a specific angle, and the diffraction efficiency is high. Of course, the first diffraction grating 12 and the second diffraction grating 18 may be provided as other gratings as necessary. In other embodiments, the first and second diffraction gratings 12 and 18 may be replaced by a super-surface having a similar function.

The first diffraction grating 12 may include one or more bragg gratings and the second diffraction grating 18 may include one or more bragg gratings. The first 12 and second 18 diffraction gratings may be a plurality of multiplexed VBGs, each designed for a particular FOV and wavelength range, where the grating period of each VBG may be between 0.2 μm and 1.5 μm. For example, the first diffraction grating 12 may be three multiplexed VBGs for red, blue and green monochromatic light, respectively.

The first diffraction grating 12 and the second diffraction grating 18 may be arranged so as not to diffract the central wavelength of the incident light. The incoupling grating 14 may be a blazed, rectangular or slanted grating with a grating period of between 0.2 μm and 1.5 μm. The outcoupling grating 16 may be any two-dimensional grating, and the grating period on the bisector of the angle formed by the two basis vectors may be between 0.4 μm and 3 μm. The refractive index of the gratings and the waveguide 11 may be between 1.5 and 3 and the material may be silicon, plastic, glass, polymer or some combination of the above.

For a better understanding of the present embodiment, the following is exemplified.

For a bragg grating or a relief grating, light incident at the same angle and having different wavelengths is split into light rays having different diffraction angles due to the dispersion effect of the grating. Dispersion is understood to mean that the diffraction components of the grating for different wavelengths of light are of different magnitudes, resulting in different diffraction angles for different colors of light.

Referring to fig. 3 and 4, in the related art, an incident field (colored light) is separated due to chromatic dispersion after being diffracted by a grating. The abscissa and the ordinate of the K space are Kx/K0 and Ky/K0 respectively, wherein Kx is the light loss of light in the x direction, Ky is the light loss of light in the y direction, K0 is the vacuum loss of light, the K space reflects the included angle between the light and the xy plane, the farther away from the zero point, the larger the included angle between the light and the normal of the xy plane is, and the obvious observation here can be seen that the incident color light at the same angle is divided into monochromatic lights at different angles. For example, the monochromatic light includes blue monochromatic light, green monochromatic light, and red monochromatic light, respectively, from small to large at an angle to the incident light.

The difference in dispersion between the red light of the maximum wavelength and the blue light of the minimum wavelength is:

where Λ in is the grating period of the incoupling grating, λ max is the maximum wavelength of the incident color light, and λ min is the minimum wavelength of the incident color light.

To improve the above phenomenon, please refer to fig. 5 and fig. 6, fig. 5 is a second structural diagram of the optical device according to the embodiment of the present application, and fig. 6 is a schematic diagram of optical transmission of the optical device shown in fig. 5 in k-space. The dispersion of the incoupling grating 14 in this embodiment can be calculated, and then a set of first diffraction gratings 12 (e.g., bragg gratings) with the dispersion opposite to that of the incoupling grating 14 is designed to compensate Δ K, so that each wavelength of light can be propagated at the same angle in the waveguide. For example, the dispersion difference of the first diffraction grating 12, which is dispersion-compensated by the incoupling grating 14, for each color is:

wherein, Λ maxin is the grating period corresponding to the incident light with the longest diffraction wavelength in the first diffraction grating, Λ minin is the grating period corresponding to the incident light with the shortest diffraction wavelength in the first diffraction grating, and λ max is the maximum wavelength of the incident colored lightλ min is the minimum wavelength of incident color light, i_maxinIs the grating period inclination angle i corresponding to the longest wavelength incident light diffracted in the first diffraction grating_mininThe grating period inclination angle corresponding to the incident light with the shortest diffraction wavelength in the first diffraction grating. Here, the compensation can be achieved if Δ K is equal to Δ K2.

The chromatic dispersion of the second diffraction grating 18 and the coupling-out grating 16 is opposite, and the grating period of the coupling-out grating 16 is Λ out, the grating period Λ out of the coupling-out grating 16 is parallel to or in the same direction as the grating period of the coupling-in grating 14, the maximum wavelength of the incident color light is λ max, and the minimum wavelength of the incident color light is λ min, then

There are:

wherein Λ maxout is a grating period corresponding to the longest-wavelength incident light diffracted in the second diffraction grating 18, Λ minout is a grating period corresponding to the shortest-wavelength incident light diffracted in the second diffraction grating 18, i_maxoutIs the grating period tilt angle, i, corresponding to the longest wavelength of incident light diffracted in the second diffraction grating 18_minoutThe grating period tilt angle corresponding to the shortest wavelength of the incident light diffracted in the second diffraction grating 18. The angle i is the tilt angle of the grating period corresponding to the incident light, please refer to fig. 7.

Since the bragg grating diffracts only light of a specific wavelength at a specific angle, the period of the bragg grating differs here for different wavelengths.

With continued reference to fig. 5, when a first light signal 22 (e.g., a color incident light) enters the optical device 10, it is first diffracted by the first diffraction grating 12 to split three monochromatic light signals 24 (e.g., three monochromatic lights) of blue (24a), green (24b), and red (24c), and the three monochromatic lights are then diffracted and coupled into the incoupling grating 14 to become incoupling lights 25a, 25b, and 25c, since the chromatic dispersion of the first diffraction grating 12 and the incoupling grating 14 for the color lights are opposite, and thus the total internal reflection angles of the incoupling lights 25a, 25b, and 25c of three colors are the same, and the incoupling lights 25a, 25b, and 25c reach the incoupling grating 16 and become diffraction lights 26a, 26b, and 26 c. And because the chromatic dispersion of the second diffraction grating 18 and the coupling grating 16 is opposite to each other, the angles of the emergent light beams after the light beams 26a, 26b and 26c are diffracted by the second diffraction grating 18 are all equal, which means that the light beams 26a, 26b and 26c are recombined together to become the second optical signal 28 of the colored light beams, and the incident light beams are restored, so that the incident light beams are coupled out to human eyes, and a user can see the picture of the projection light machine. In the above process, since the first diffraction grating 12 and the second diffraction grating 18 only diffract light with a specific incident angle at a specific wavelength, no diffraction with any other light is performed except for diffracting the first optical signal 22 into monochromatic optical signals 24a, 24b, and 24c and diffracting the light 26a, 26b, and 26c into the second optical signal 28.

The angle of the reflection angle of the plurality of monochromatic light signals in the waveguide 11 is smaller than the maximum critical angle of total internal reflection in the waveguide 11 and larger than the minimum critical angle of total internal reflection in the waveguide 11. It is understood that the angle of the reflection angle within the waveguide 11 for the incoupled light rays 25a, 25b and 25c is smaller than the maximum critical angle for total internal reflection in the waveguide 11 and larger than the minimum critical angle for total internal reflection in the waveguide 11. Monochromatic light signals 24a, 24b and 24c, light 26a, 26b and 26c are similar to the incoupling light 25a, 25b and 25 c.

Referring to fig. 8, fig. 8 is another schematic diagram of the optical device shown in fig. 5 for transmitting light in k-space. The incident image light 311 is diffracted by the first diffraction grating 12 and then divided into three light rays 311a (red), 311B (green), and 311c (blue), and since the chromatic dispersion of the first diffraction grating 12 and the coupling grating 14 is opposite to that of the colored light, the light rays 311a, 311B, and 311c are uniformly changed into light rays 312 (corresponding to the same total internal reflection angle of the three-color light in the waveguide 11) due to the chromatic dispersion of the coupling grating 14 after being diffracted and coupled in by the coupling grating 14, and at this time, the light rays 312 are all within the ring a & B, which means that the light with different wavelengths can be transmitted in the waveguide 11 after being coupled in.

The light 312 has three paths to the outcoupler: 1. become pupil-expanded rays 313a, 313b and 313c and expand the pupil upward after interacting with the outcoupling grating 16, and then become pupil-expanded rays 311a, 311b and 311c to be outcoupled after interacting with the outcoupling grating 16 for the second time; 2. become pupil-expanded rays 314a, 314b and 314c and expand the pupil downward after interacting with the outcoupling grating 16, and then become pupil-expanded rays 311a, 311b and 311c outcoupled after interacting with the outcoupling grating 16 for the second time; 3. the light which has acted on the coupling-out grating 16 directly becomes the pupil-expanding light 311a, 311b, 311c and is coupled out, and the end result of the above three paths is the pupil-expanding light 311a, 311b, 311 c. After coupling out, the pupil-expanding light rays 311a, 311b, and 311c are diffracted by the second diffraction grating 18, and since the chromatic dispersion of the second diffraction grating 18 and the coupling-out grating 16 is opposite, the pupil-expanding light rays 311a, 311b, and 311c are diffracted by the second diffraction grating 18 and changed into the light rays 311 again, and the incident light rays are restored, so as to be coupled out to human eyes, and a user can see the picture of the projection light machine. It can be seen that, compared to the conventional two-dimensional diffraction waveguide structure, when the diffraction waveguides of the first diffraction grating 12 and the second diffraction grating 18 of the optical structure of the present embodiment transmit images, the coupled light and the pupil-expanding light are within the ring a & B, so that there is no color-missing problem.

Boundary B represents the minimum critical angle for total internal reflection of a light ray in the waveguide 11 and boundary a represents the maximum critical angle for total internal reflection of a light ray in the waveguide 11, i.e. only pictures within the rings a & B can be transmitted in the waveguide 11.

Wherein the area of the orthographic projection of the first diffraction grating 12 on the first side 112 is greater than or equal to the area of the orthographic projection of the incoupling grating 14 on the first side 112; and/or the area of the orthographic projection of the second diffraction grating 18 on said first side 112 is larger than or equal to the area of the orthographic projection of said outcoupling grating 16 on said first side 112.

On the waveguide 11, a coupling-out grating 16/coupling-in grating 14 and a first diffraction grating 12/second diffraction grating 18 are disposed on the back and front sides with respect to the incident light, respectively. Wherein, the incoupling grating 14 and the first diffraction grating 12 are a group, the two gratings are overlapped on the XY plane, and the coverage area of the first diffraction grating 12 is larger than or equal to the incoupling grating 14 under normal condition; the coupling-out grating 16 and the second diffraction grating 18 are in a set, the two gratings are overlapped on the XY plane, and the coverage area of the second diffraction grating 18 is larger than or equal to that of the coupling-out grating 16 under the normal condition.

It should be noted that the above embodiments are only for illustrating the light rays with normal incidence (central field of view), and the present embodiment can achieve similar effects for the light rays with any angle of incidence.

Referring to fig. 9, fig. 9 is a schematic view of the optical device shown in fig. 5 from another angle. Wherein the first diffraction grating 12 can be relatively arranged at the middle position of the waveguide, and the area of the second diffraction grating 18 is larger.

Optionally, referring to fig. 10, fig. 10 is a schematic view of a third structure of an optical device according to an embodiment of the present application. The optical device may further include a turning grating 15, the waveguide 11 is configured to transmit the plurality of monochromatic light signals 24 guided by the coupling-in grating 14 to the turning grating 15, and the turning grating 15 is configured to diffract the plurality of monochromatic light signals 24 into a single-direction pupil-expanding beam and transmit the pupil-expanding beam to the coupling-out grating 16 through the waveguide 11. The incoupling grating 14 and the turning grating 15 are disposed on one side of the waveguide 11, and the outcoupling grating 16 is disposed on the other side of the waveguide 11.

Referring to fig. 11, fig. 11 is a schematic diagram illustrating light transmission in k-space of the optical device shown in fig. 10. The incident image light 411 is diffracted by the first diffraction grating 12 and divided into three light rays 411a (red), 411B (green) and 411c (blue), and since the chromatic dispersion of the first diffraction grating 12 and the coupling-in grating 14 is opposite to that of the colored light, the light rays 411a, 411B and 411c are uniformly changed into light rays 412 (corresponding to the same total internal reflection angle of the three-colored light in the waveguide 11) due to the chromatic dispersion of the coupling-in grating 14 after being diffracted and coupled in by the coupling-in grating 14, and it is noted that the light rays 412 are all within the ring a & B, which means that the light with different wavelengths can be transmitted in the waveguide 11 after being coupled in. The light ray 412 has only one path to the outcoupler: the pupil-expanding light beams 413a, 413b and 413c are diffracted by the turning grating 15 to become upward pupil-expanding light beams 413a, 413b and 413c, and are diffracted by the coupling-out grating 16 to become pupil-expanding light beams 411a, 411b and 411c, and are coupled out, and the pupil-expanding light beams 411a, 411b and 411c are diffracted by the second diffraction grating 18, and because the chromatic dispersion of the second diffraction grating 18 and the coupling-out grating 16 is opposite to that of the colored light, the pupil-expanding light beams 411a, 411b and 411c are diffracted by the second diffraction grating 18 to become light rays 411, and the incident light rays are restored, and are coupled out to human eyes, so that a user can see the picture of the projection light machine. It can be seen that, compared to the conventional two-dimensional diffractive waveguide, the one-dimensional diffractive waveguide structure based on VGB of the present embodiment transmits the image with the coupled light and the pupil-expanding light within the ring a & B, so that there is no color-lacking problem.

It should be noted that, in this embodiment, the chromatic dispersion of the color light of the first diffraction grating and the coupling-in grating is opposite, and if the grating period of the coupling-in grating is Λ in, the maximum wavelength of the incident color light is λ max, and the minimum wavelength of the incident color light is λ min, then:

wherein, Λ maxin is the grating period corresponding to the incident light with the longest diffraction wavelength in the first diffraction grating, Λ minin is the grating period corresponding to the incident light with the shortest diffraction wavelength in the first diffraction grating, λ max is the maximum wavelength of the incident colored light, λ min is the minimum wavelength of the incident colored light, i_maxinIs the grating period inclination angle i corresponding to the longest wavelength incident light diffracted in the first diffraction grating_mininThe grating period inclination angle corresponding to the incident light with the shortest diffraction wavelength in the first diffraction grating

The chromatic dispersion of the second diffraction grating and the coupling-out grating is opposite, and the grating period of the coupling-out grating is Λ out, the grating period Λ out of the coupling-out grating is parallel to or in the same direction as the grating period of the coupling-in grating 14, the maximum wavelength of the incident chromatic light is λ max, and the minimum wavelength of the incident chromatic light is λ min, then:

wherein, Λ maxout is the second diffractionThe grating period corresponding to the longest-wavelength incident light diffracted in the grating 18, Λ minout is the grating period corresponding to the shortest-wavelength incident light diffracted in the second diffraction grating 18, i_maxoutIs the grating period tilt angle, i, corresponding to the longest wavelength of incident light diffracted in the second diffraction grating 18_minoutThe grating period tilt angle corresponding to the shortest wavelength of the incident light diffracted in the second diffraction grating 18.

The incoupling grating 14 may be a blazed, rectangular or slanted grating with a grating period of between 0.2 μm and 1.5 μm. The outcoupling grating 16 may be a blazed, rectangular or slanted grating and the grating period Λ in may be between 0.2 μm and 1.5 μm. The turning grating 22 may be a blazed grating, a rectangular grating or a tilted grating, and the grating period Λ in may be between 0.2 μm and 1.5 μm. The refractive index of each of the gratings and the waveguide 10 may be 1.5 to 3 and the material may be silicon, plastic, glass, polymer or some combination of the above.

Referring to fig. 12, fig. 12 is a schematic diagram illustrating a fourth structure of an optical device according to an embodiment of the present application. The main difference between this implementation and the above described embodiments is the waveguide. In this embodiment, the waveguide 11 includes a first waveguide layer 116 and a second waveguide layer 118 stacked together, the first diffraction grating 12 and the second diffraction grating 18 are disposed on a side of the first waveguide layer 116 away from the second waveguide layer 118, and the coupling-in grating 14 and the coupling-out grating 16 are disposed on a side of the second waveguide layer 118 away from the first waveguide layer 116.

This poses a significant process challenge due to the need to fabricate grating structures on both sides of the monolithic waveguide 11. Therefore, in this embodiment, waveguide 11 is divided into two layers, i.e., first waveguide layer 116 and second waveguide layer 118, and first waveguide layer 116 and second waveguide layer 118 are bonded together by glue. In this way, the two first waveguide layers 116 and the second waveguide layers 118 may be first patterned with corresponding grating structures on a single surface and then bonded together, which may reduce the process difficulty.

An embodiment of the present application further provides an electronic device, where the electronic device includes a housing and an optical device, the optical device is disposed in the housing, the optical device is the optical device in any of the above embodiments, and a structure of the optical device is not described herein again.

Exemplarily, as shown in fig. 13, the electronic device 100 may be smart glasses, and the electronic device 100 includes the optical apparatus 10. The smart glasses may be AR glasses or VR glasses or other smart glasses. Of course, the electronic device may also be a wearable device such as an intelligent helmet, or other devices having a waveguide structure

The optical device and the electronic device provided by the embodiments of the present application are described in detail above, and the principles and embodiments of the present application are described herein by applying specific examples, and the description of the embodiments is only used to help understanding the method and the core concept of the present application; meanwhile, for those skilled in the art, according to the idea of the present application, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present application.