Diffraction optical waveguide assembly and near-to-eye display device

Abstract

The invention provides a diffractive optical waveguide assembly and near-eye display equipment. The diffractive optical waveguide assembly comprises a polaroid, a coupling-in grating, a waveguide substrate and a rotary reflection assembly, the polaroid is arranged on the light incident side of the coupled grating; the coupling-in grating and the rotary reflection assembly are arranged on the two opposite sides of the waveguide substrate respectively. The first linearly polarized light transmitted by the polaroid is incident and coupled into the grating and then diffracts first 0-level diffracted light propagating towards the rotary reflection assembly; the rotary reflection assembly is used for converting the first 0-level diffracted light into second linearly polarized light and reflecting the second linearly polarized light to the coupling-in grating; the polarization direction of the second linearly polarized light is orthogonal to the polarization direction of the first linearly polarized light; the second linearly polarized light is coupled into the grating to diffract second 0-level diffracted light; and the polaroid is also used for reflecting the second 0-level diffraction light to the coupling-in grating. According to the scheme, the rotation reflection assembly is matched with the polaroid, two times of recycling of 0-level diffraction light is achieved, and therefore the light efficiency of the diffraction light waveguide assembly is improved.

Description

Technical Field

[0001] This application relates to the field of optical technologies, and in particular, to a diffractive optical waveguide component and a near-eye display device. Background Art

[0002] The diffractive optical waveguide is a core optical component of an Augmented Reality (AR) near-eye display system, which realizes the coupling-in, pupil expansion, and coupling-out of light through a surface grating. In traditional designs, the grating completes the guiding and expansion of light through first-order diffraction. In this process, only the +1st-order diffracted light or the -1st-order diffracted light enters the waveguide substrate and is repeatedly reflected to complete the guiding and expansion of light, while the 0th-order diffracted light is directly emitted from the waveguide substrate as a direct-through light. The 0th-order diffracted light directly emitted from the waveguide substrate is not utilized, becoming an energy loss source in the diffractive optical waveguide system, resulting in the light utilization efficiency of the diffractive optical waveguide. Summary of the Invention

[0003] This application provides a diffractive optical waveguide component and a near-eye display device, aiming to improve the light utilization efficiency of the diffractive optical waveguide component.

[0004] In a first aspect, this application provides a diffractive optical waveguide component, including: a polarizer, a coupling grating, a waveguide substrate, and a rotating reflection component; wherein:

[0005] The polarizer is disposed on the light incident side of the coupling grating;

[0006] The coupling grating and the rotating reflection component are respectively arranged on opposite sides of the waveguide substrate; the first linearly polarized light transmitted through the polarizer is incident on the coupling grating and diffracts into the first -1st-order diffracted light that propagates by total internal reflection in the waveguide substrate, and the first 0th-order diffracted light that propagates towards the rotating reflection component;

[0007] The rotating reflection component is configured to convert the first 0th-order diffracted light into a second linearly polarized light and reflect it to the coupling grating; wherein, the polarization direction of the second linearly polarized light is orthogonal to the polarization direction of the first linearly polarized light;

[0008] The second linearly polarized light diffracts through the coupling grating into the second +1st-order diffracted light that propagates by total internal reflection in the waveguide substrate, and the second 0th-order diffracted light; the polarizer is further configured to reflect the second 0th-order diffracted light to the coupling grating.

[0009] In the above technical scheme, the first 0th order diffraction light is reflected back to the coupling-in grating by a rotating reflection component to realize the first recovery of the 0th order diffraction light, and the second 0th order diffraction light is reflected back to the coupling-in grating by the rotating reflection component in cooperation with the polarizer to realize the second recovery of the 0th order diffraction light; the 0th order diffraction light loss of the diffraction light waveguide component is effectively reduced through the recovery of the 0th order diffraction light, thereby improving the optical efficiency of the diffraction light waveguide component.

[0010] In a possible implementation, the rotating reflective assembly includes a rotating plate and a reflector, wherein:

[0011] The rotating plate is located on a side of the waveguide substrate away from the coupling-in grating and is arranged opposite to the coupling-in grating, and the reflecting mirror is located on a side of the rotating plate away from the waveguide substrate;

[0012] The rotating plate is used to rotate the polarization direction of the light passing through the rotating plate by 45 degrees each time.

[0013] In a possible implementation, the rotating plate is a Faraday rotator.

[0014] In a possible implementation, the rotating plate is a 1 / 4λ wave plate.

[0015] In a possible implementation manner, the coupling-in grating is in an elliptical shape, and the major axis of the ellipse is along the direction of the coupling-in grating pointing to the coupling-out grating;

[0016] The major axis of the ellipse satisfies:

[0017] L = R + 2*tan(a / 2);

[0018] Wherein, L is the length of the major axis of the ellipse, R is the length of the minor axis of the ellipse; and a is the field angle of the diffraction optical waveguide component in the major axis direction.

[0019] In a possible implementation, taking the end of the out-coupling grating whose long axis is far away from the diffractive optical waveguide component as the origin, the diffraction efficiency of the elliptical in-coupling grating along the long axis direction satisfies:

[0020]

[0021] Where d is the distance from the origin along the major axis, η d is the diffraction efficiency of the coupled grating at a distance d from the origin along the major axis, R is the minor axis length of the ellipse; a is the field angle of the diffraction optical waveguide component in the major axis direction, and η is the diffraction efficiency of the coupled grating at the origin.

[0022] In a possible implementation, the coupling-in grating is a blazed grating or a tilted grating.

[0023] In a possible implementation, when the coupling grating is a blazed grating, the blaze angle of the coupling grating is greater than 30 degrees.

[0024] In a possible implementation, when the coupling grating is a tilted grating, the tilt angle of the tilted grating is greater than 45 degrees.

[0025] In a second aspect, the present application provides a near-eye display device, including an optical engine, and any one of the above diffraction waveguide components disposed on the light-emitting side of the optical engine;

[0026] The optical engine is configured to emit polarized light having the same polarization direction as that of the polarizer.

[0027] In the above near-eye display device, the diffraction waveguide component uses a rotating reflection component to reflect the first zero-order diffracted light back to the coupling grating to achieve the first recycling of the zero-order diffracted light, and then cooperates with the polarizer through the rotating reflection component to reflect the second zero-order diffracted light back to the coupling grating to achieve the second recycling of the zero-order diffracted light; the two zero-order diffracted light recycling effectively reduces the zero-order diffracted light loss of the diffraction waveguide component, thereby improving the light efficiency of the diffraction waveguide component. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] To more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. The drawings herein are incorporated into the specification and form a part of this specification. These drawings show embodiments consistent with the present disclosure and, together with the specification, are used to illustrate the technical solutions of the present disclosure. It should be understood that the following drawings only show certain embodiments of the present disclosure and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0029] Figure 1 Schematic diagram of the overall diffraction waveguide component provided by the present application;

[0030] Figure 2 Schematic diagram of the coupling grating in the embodiment of the present application. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions, and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings.

[0032] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in one or more embodiments of this specification should have the ordinary meaning understood by those of ordinary skill in the art to which this disclosure pertains. The "first", "second" and similar terms used in one or more embodiments of this specification do not denote any order, quantity or importance, but are only used to distinguish different components. Words such as "including" or "comprising" mean that the elements or objects appearing before this word cover the elements or objects listed after this word and their equivalents, without excluding other elements or objects. Words such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right", etc. are only used to represent relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0033] To facilitate the understanding of the diffractive optical waveguide component provided in this application, its application scenario will be described first. The diffractive optical waveguide component provided in this application can be applied to a near-eye display device.

[0034] The diffractive optical waveguide is the core optical element of an augmented reality (AR) near-eye display system, which realizes the coupling in, pupil expansion, and coupling out of light through surface gratings. In traditional designs, the grating completes the guiding and expansion of light through first-order diffraction. In this process, only the +1-order diffracted light or -1-order diffracted light enters the waveguide substrate and is repeatedly reflected to complete the guiding and expansion of light, while the zero-order diffracted light is directly emitted from the waveguide substrate as direct light. The zero-order diffracted light directly emitted from the waveguide substrate is not utilized, becoming an energy loss source in the diffractive optical waveguide system, resulting in the light utilization efficiency of the diffractive optical waveguide.

[0035] Based on this, this application provides a diffractive optical waveguide component and a near-eye display device, aiming to improve the light utilization efficiency of the diffractive optical waveguide component. The diffractive optical waveguide component provided in the embodiments of this application will be specifically introduced below with reference to the accompanying drawings.

[0036] Refer to Figure 1 , Figure 1 is the overall schematic diagram of the diffractive optical waveguide component provided in this application. The diffractive optical waveguide component provided in this application includes a polarizer 1, an input grating 2, a waveguide substrate 3, and a rotating reflection component 4. Among them, the input grating 2 is disposed on the waveguide substrate 3 and is used to couple light into the waveguide substrate 3 and enable part of the light to be repeatedly reflected and propagated within the waveguide substrate 3. The polarizer 1 cooperates with the rotating reflection component 4 to realize the recycling of the zero-order diffracted light.

[0037] Specifically, the polarizer 1 is arranged on the light incident side of the coupling grating 2, and the rotating reflection component 4 and the coupling grating 2 are arranged on opposite sides of the waveguide substrate 3. For such a diffraction optical waveguide component, the light emitted by the optical engine 6 first irradiates the polarizer 1, and at least part of the light passes through the polarizer 1 and reaches the coupling grating 2. For convenience of description, the light that irradiates the polarizer 1 from the optical engine 6 and then passes through the polarizer 1 is called the first linearly polarized light 51. After the first linearly polarized light 51 is incident on the coupling grating 2, diffraction occurs, and the diffracted light includes -1st order diffracted light and 0th order diffracted light. For convenience of description, the -1st order diffracted light is named the first -1st order diffracted light, and the 0th order diffracted light is named the first 0th order diffracted light 52. After entering the waveguide substrate 3, the first -1st order diffracted light will totally internally reflect and propagate in the waveguide substrate 3 until it reaches the output grating for output imaging. The first 0th order diffracted light 52 will continue to propagate in the direction away from the coupling grating 2 along the direction of the first linearly polarized light 51 until it reaches the rotating reflection component 4.

[0038] After the first 0th order diffracted light 52 reaches the rotating reflection component 4, under the action of the rotating reflection component 4, the first 0th order diffracted light 52 will totally internally reflect and propagate in the direction towards the coupling grating 2, and at the same time, the polarization direction of the first 0th order diffracted light 52 will deflect by 90 degrees. For convenience of description, the first 0th order diffracted light 52 transformed by the rotating reflection component 4 as described above is named the second linearly polarized light 53, and the second linearly polarized light 53 will propagate towards the coupling grating 2; since the polarization direction of the first 0th order diffracted light 52 is the same as that of the first linearly polarized light 51, the polarization direction of the second linearly polarized light 53 is also polarized 90 degrees relative to the first linearly polarized light 51.

[0039] After the second linearly polarized light 53 is incident on the coupling grating 2, diffraction will also occur, and the diffracted light includes 1st order diffracted light and 0th order diffracted light. For convenience of description, the 1st order diffracted light is named the second 1st order diffracted light, and the 0th order diffracted light is named the second 0th order diffracted light 54. Among them, the second 1st order diffracted light will totally internally reflect and propagate in the waveguide substrate 3 and finally be output and imaged through the output grating, and the second 0th order diffracted light 54 will continue to propagate towards the polarizer 1 along the direction of the second linearly polarized light 53. Here, when the second linearly polarized light 53 is incident on the coupling grating 2, the recycling of the first 0th order diffracted light is completed for the first time.

[0040] The polarization direction of the second 0th-order diffracted light 54 is the same as that of the second linearly polarized light 53, and the polarization direction of the second linearly polarized light 53 is deflected by 90 degrees relative to the first linearly polarized light 51. That is to say, the polarization direction of the second 0th-order polarized light is polarized by 90 degrees relative to the polarization direction of the polarizer 1. In this way, when the second 0th-order polarized light is incident on the polarizer 1, it will be completely reflected and propagated towards the coupling grating 2. After the reflected second 0th-order polarized light is incident on the coupling grating 2, some of the diffracted light can be reflected and propagated in the waveguide substrate 3 and be coupled out and imaged by the coupling-out grating, thus realizing the recycling of the second 0th-order diffracted light.

[0041] Optionally, after the second 0th-order diffracted light 54 is incident on the coupling grating 2 through polarized light, it will diffract out a -1st-order diffracted light and a 0th-order diffracted light. Here, the -1st-order diffracted light is named the third -1st-order diffracted light, and the 0th-order diffracted light is named the third 0th-order diffracted light 55. Similar to the first 0th-order diffracted light 52, the third 0th-order diffracted light 55 will be converted into the third linearly polarized light 56 after passing through the rotation reflection component 4. The polarization direction of the third linearly polarized light 56 is 90 degrees different from the polarization direction of the second linearly polarized light 53, that is, the polarization direction of the third linearly polarized light 56 is 180 degrees different from the polarization direction of the light of the first polarizer 1. After the third linearly polarized light 56 is incident on the coupling grating 2, some of the diffracted light is totally reflected and propagated in the waveguide substrate 3 and imaged, realizing the third recycling of the 0th-order diffracted light and further improving the light efficiency of the diffractive waveguide component. And the 0th-order diffracted light diffracted again after the third linearly polarized light 56 is incident on the coupling grating 2 will escape through the polarizer 1 because its polarization direction is 180 degrees different from the polarization direction of the first linearly polarized light 51.

[0042] It should be noted that the above rotation reflection component 4 functions to deflect the polarization direction of all diffracted light by 90 degrees at the same time. This rotation reflection component 4 can be a single component to achieve the above two functions at the same time, or can be two or more components cooperating to achieve the above two functions.

[0043] In the above technical solution, the first 0th-order diffracted light 52 is reflected back to the coupling grating 2 by using the rotation reflection component 4 to realize the first recycling of the 0th-order diffracted light, and the second 0th-order diffracted light 54 is reflected back to the coupling grating 2 by the cooperation of the rotation reflection component 4 and the polarizer 1 to realize the second recycling of the 0th-order diffracted light; through the two recycling of the 0th-order diffracted light, the loss of the 0th-order diffracted light of the diffractive waveguide component is effectively reduced, thereby improving the light efficiency of the diffractive waveguide component.

[0044] As an alternative embodiment, the rotation reflection component 4 includes a rotating sheet 41 and a reflecting mirror 42. The rotating sheet 41 is used to rotate the polarization direction of the linearly polarized light passing through the rotating sheet 41 by 45 degrees each time. The reflecting mirror 42 is used for total diffraction of light. Specifically, the rotating sheet 41 is located on the side of the waveguide substrate 3 away from the coupling grating 2 and is arranged opposite to the coupling grating 2. The reflecting mirror 42 is located on the side of the rotating sheet 41 away from the waveguide substrate 3. That is, when the first zero-order diffracted light 52 is incident on the rotation reflection component 4, the first zero-order diffracted light 52 first passes through the rotating sheet 41, then reaches the reflecting mirror 42, is deflected in direction under the action of the reflecting mirror 42 and passes through the rotating sheet 41 for the second time, and then passes through the waveguide substrate to reach the coupling grating 2.

[0045] When the first zero-order diffracted light 52 passes through the rotating sheet 41 for the first time, the polarization direction of the first zero-order diffracted light 52 is deflected by 45 degrees; and the polarization direction of the light does not change during the reflection by the reflecting mirror 42; when the first zero-order diffracted light 52 passes through the rotating sheet 41 for the second time, its polarization direction is deflected by 45 degrees again. The first zero-order diffracted light 52 passes through the rotating sheet 41 twice, and the polarization direction of the first zero-order diffracted light 52 can be deflected by 90 degrees, and under the action of the reflecting mirror 42, the first zero-order diffracted light 52 propagates towards the coupling grating 2. After the first zero-order diffracted light 52 passes through the rotating sheet 41 for the second time, it is converted into the second linearly polarized light 53.

[0046] It should be noted that the reflecting mirror 42 in the present application can be a metal-coated reflecting mirror 42, a polarizing mirror orthogonal to the polarization direction of the first linearly polarized light 51, etc.; the rotating sheet 41 in the present application can be a 1 / 4λ wave plate, a Faraday rotator, a liquid crystal phase retarder, etc.

[0047] In this alternative embodiment, the combination of the rotating sheet 41 and the reflecting mirror 42 is used to achieve two functions of changing the light propagation direction and the polarization direction. Both the rotating sheet 41 and the reflecting mirror 42 are common optical devices, making the structure of the rotation reflection component 4 simple and the materials easy to obtain.

[0048] As an alternative embodiment, for the above rotation reflection component 4, the rotating sheet 41 can be a Faraday rotator. Based on the magneto-optical effect, the Faraday rotator can deflect the deflection direction of the linearly polarized light passing through the Faraday rotator by 45 degrees, and the Faraday rotator has non-reciprocity. No matter from which side of the Faraday rotator the light is incident, the polarization direction of the light can be deflected in one direction, just suitable for the situation where the light needs to be incident on the rotating sheet 41 in the reverse direction after passing through the reflecting mirror 42 in this embodiment. Moreover, the Faraday rotator can relatively easily obtain broad-spectrum characteristics, can adapt to light of multiple wavelengths, and the light loss of the Faraday rotator is small, which is beneficial to improving the light efficiency of the diffractive optical waveguide component.

[0049] As an alternative implementation, for the above-mentioned rotating reflection component 4, the rotating sheet 41 can also be a 1 / 4λ wave plate. When the rotating sheet 41 is a 1 / 4λ wave plate, to ensure the requirement of converting the first zero-order diffracted light 52 into the second linearly polarized light 53, it is necessary to set the fast axis of the 1 / 4λ wave plate to be at 45 degrees to the polarization direction of the first zero-order diffracted light 52.

[0050] The first zero-order diffracted light 52 is linearly polarized light. After passing through the 1 / 4λ wave plate, the first zero-order diffracted light 52 can be converted into circularly polarized light. After passing through the mirror 42, the rotation direction of the circularly polarized light will be reversed; the circularly polarized light with the reversed rotation direction passes through the 1 / 4λ wave plate again, and the circularly polarized light is converted into the second linearly polarized light 53, and the polarization direction of the second linearly polarized light 53 is orthogonal to the polarization direction of the first linearly polarized light 51. It should be noted that when using a 1 / 4λ wave plate as the rotating sheet 41, the mirror 42 cannot be a polarization mirror orthogonal to the polarization direction of the first linearly polarized light 51. Using a 1 / 4λ wave plate as the rotating sheet 41 has the characteristics of anti-electromagnetic interference and the advantage of low cost.

[0051] Refer to Figure 2 , Figure 2 which is a schematic diagram of the coupling grating in the embodiment of the present application. As an alternative implementation, when specifically setting the coupling grating 2, the shape of the coupling grating 2 is an ellipse, and the long axis of the ellipse points in the direction of the coupling grating 2 towards the output grating;

[0052] The long axis of the ellipse satisfies:

[0053] L = R + 2 * tan(a / 2) (1)

[0054] where L is the length of the long axis of the ellipse, R is the length of the short axis of the ellipse; a is the field of view angle of the diffractive optical waveguide component in the long axis direction.

[0055] It should be noted that in the diffractive optical waveguide component of the traditional design, the shape of the coupling grating 2 is usually circular, and the diameter of the circular coupling grating 2 is related to multiple factors such as the diameter of the incident light beam, the propagation length of the light in the waveguide, and the field of view angle of the diffractive optical waveguide component for light output imaging. Here, the length of the short axis of the ellipse can directly inherit the diameter of the circular coupling grating 2 in the traditional design, but the long axis of the ellipse can be regarded as being formed by stretching the diameter of the circular coupling grating 2 in the traditional design. By setting the coupling grating 2 as an ellipse and the length of the long axis satisfying the above formula, the area of the coupling grating 2 for receiving and recycling the zero-order diffracted light can be increased, thereby increasing the recycling amount of the zero-order diffracted light, and further increasing the light efficiency of the diffractive optical waveguide component.

[0056] As an alternative implementation, with the end of the long axis far from the output grating of the diffractive optical waveguide component as the origin 21, along the long axis direction, the diffraction efficiency of the elliptical coupling grating 2 satisfies:

[0057]

[0058] where d is the distance from the origin 21 along the long axis direction, and η d is the diffraction efficiency of the grating 2 coupled into at a distance d from the origin 21 along the long axis direction, R is the length of the minor axis of the ellipse; a is the field of view angle of the diffractive optical waveguide component in the long axis direction, and η is the diffraction efficiency of the grating 2 coupled into at the origin 21.

[0059] It should be noted that here R can still inherit the diameter of the circular grating 2 in the traditional design, and η can follow the diffraction efficiency of the circular grating 2 in the traditional design.

[0060] As can be seen from the above, after the light is incident on the grating 2 for the first time, the first - 1 order diffracted light will be totally reflected repeatedly in the waveguide substrate 3 and propagate in the direction away from the origin 21. For the light coupled into the grating 2 on the side close to the origin 21, the first - 1 order diffracted light diffracted from these lights has a chance to irradiate one end of the principle origin 21 of the grating 2 during repeated reflections in the waveguide substrate 3. When the first - 1 order diffracted light irradiates the grating 2 again, it is easy to cause the second coupling of the first - 1 order diffracted light, thus causing light energy loss and reducing the light efficiency of the diffractive optical waveguide component.

[0061] As can be seen from the above formula (2), gradually moving away from the origin 21 along the long axis direction, the diffraction efficiency of the grating 2 gradually decreases. In this way, the phase matching condition between the first - 1 order diffracted light diffracted from the light coupled into at one end close to the origin 21 and the grating 2 at the other end away from the origin 21 can be destroyed as much as possible, thereby reducing the second coupling of the first - 1 order diffracted light and improving the light efficiency of the diffractive optical waveguide component. And according to the calculation, when the diffraction efficiency of the grating 2 changes according to the constraint of formula (2), better light efficiency can be obtained.

[0062] It should be noted that the method of changing the diffraction efficiency of the grating 2 in the embodiments of the present application may include, but is not limited to, changing the grating width and height, etc. Specifically, the grating 2 with gradually changing diffraction efficiency can be produced by electron beam lithography, nanoimprinting and other methods.

[0063] Optionally, when specifically setting the change of the diffraction efficiency of the grating 2, the diffraction efficiency of the grating 2 can be set to change continuously along the long axis, or the diffraction efficiency of the grating 2 can be set to change step - by - step along the long axis. By setting the diffraction efficiency of the grating 2 to change step - by - step along the long axis, the process difficulty can be reduced and the production efficiency can be improved.

[0064] As an alternative embodiment, the coupling grating 2 is a blazed grating or a tilted grating. The coupling grating 2 or the tilted grating has a large spectral splitting ratio, which can improve the optical efficiency of the diffractive optical waveguide component. For a diffractive optical waveguide component with a traditional design, a partial 0th-order diffracted light can be recovered by adding a reflector on the opposite side of the coupling grating 2. However, in a traditional design, if a blazed grating or a tilted grating is used, most of the light will propagate away from the output grating after the 0th-order diffracted light reflected by the mirror 42 re-enters the coupling grating 2, resulting in a reduction in the recovery efficiency of the 0th-order diffracted light. In this application, the rotation reflection component 4 is combined with the polarizer 1, which can increase the second recovery of the 0th-order diffracted light, thereby improving the recovery efficiency of the 0th-order diffracted light and further improving the optical efficiency of the diffractive optical waveguide component.

[0065] As an alternative embodiment, when the coupling grating 2 is a blazed grating, the blaze angle of the coupling grating 2 is greater than 30 degrees, specifically, it can be 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, etc. The blaze angle of the blazed grating being greater than 30 degrees can enable the blazed grating to have a large spectral splitting ratio, thereby improving the coupling efficiency of light. At the same time, in combination with the polarizing mirror and the rotation reflection component 4, a better recovery efficiency of the 0th-order diffracted light can also be obtained, thereby further improving the optical efficiency of the diffractive optical waveguide component.

[0066] As an alternative embodiment, when the coupling grating 2 is a tilted grating, the tilt angle of the tilted grating is greater than 45 degrees. The tilt angle of the tilted grating being greater than 30 degrees can enable the tilted grating to have a large spectral splitting ratio, thereby improving the coupling efficiency of light. At the same time, in combination with the polarizing mirror and the rotation reflection component 4, a better recovery efficiency of the 0th-order diffracted light can also be obtained, thereby further improving the optical efficiency of the diffractive optical waveguide component.

[0067] Currently, the coupling diffraction efficiency of a diffractive optical waveguide component with a traditional design is about 1 / 3. Through theoretical calculation, by using the polarizer 1 in combination with the rotation reflection component 4 to recover the 0th-order diffracted light three times, the coupling diffraction efficiency of the diffractive optical waveguide component can be increased by about 30%. When further combined with setting the coupling grating 2 as a blazed grating or a tilted grating, the coupling diffraction efficiency of the diffractive optical waveguide component can be increased by about 50%.

[0068] The embodiment of this application also provides a near-eye display device, including an optical engine 6, and any one of the above-mentioned diffractive optical waveguide components arranged on the light output side of the optical engine 6;

[0069] The optical engine 6 is used to emit polarized light with the same polarization direction as that of the polarizer 1.

[0070] In the above near-eye display device, the diffractive waveguide assembly uses the rotating reflection assembly 4 to reflect the first zero-order diffracted light 52 back into the grating 2 to achieve the first recovery of the zero-order diffracted light, and then cooperates with the polarizer 1 through the rotating reflection assembly 4 to reflect the second zero-order diffracted light 54 back into the grating 2 to achieve the second recovery of the zero-order diffracted light; the two recoveries of the zero-order diffracted light effectively reduce the loss of the zero-order diffracted light of the diffractive waveguide assembly, thereby improving the light efficiency of the diffractive waveguide assembly.

[0071] One or more embodiments of this specification are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of this specification shall be included within the protection scope of this disclosure.

[0072] The above is only the specific implementation manner of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art within the technical scope disclosed in this application can easily think of changes or substitutions, which should all be covered within the protection scope of this application. Therefore, the protection scope of this application shall be subject to the protection scope of the claims.

Claims

1. A diffractive optical waveguide component, characterized in that, include: A polarizer, an in-coupling grating, a waveguide substrate, and a rotating reflective assembly; wherein: The polarizer is disposed on the light incident side of the coupling-in grating; The coupling-in grating and the rotating reflective component are arranged on opposite sides of the waveguide substrate; the first linearly polarized light transmitted through the polarizer is incident on the coupling-in grating and then diffracted to produce first-1 order diffracted light that enters the waveguide substrate and propagates by total reflection, and first 0 order diffracted light that propagates toward the rotating reflective component; The rotating reflection component is used to convert the first 0th order diffraction light into a second linear polarized light and reflect it to the coupling grating; wherein the polarization direction of the second linear polarized light is orthogonal to the polarization direction of the first linear polarized light; The second linearly polarized light is diffracted by the coupling-in grating to produce a second first-order diffracted light that is totally reflected and propagates in the waveguide substrate, and a second zeroth-order diffracted light; the polarizer is also used to reflect the second zeroth-order diffracted light to the coupling-in grating.

2. The diffractive optical waveguide component according to claim 1, characterized in that The rotating reflective assembly comprises a rotating plate and a reflector, wherein: The rotating plate is located on a side of the waveguide substrate away from the coupling-in grating and is arranged opposite to the coupling-in grating, and the reflecting mirror is located on a side of the rotating plate away from the waveguide substrate; The rotating plate is used to rotate the polarization direction of the light passing through the rotating plate by 45 degrees each time.

3. The diffractive optical waveguide component according to claim 2, wherein, The rotating plate is a Faraday rotator.

4. The diffractive optical waveguide component according to claim 2, wherein The rotating plate is a 1 / 4λ wave plate.

5. The diffractive optical waveguide component according to claim 1, characterized in that, The coupling-in grating is in the shape of an ellipse, and the major axis of the ellipse points along the coupling-in grating to the direction of the coupling-out grating; The major axis of the ellipse satisfies: L = R + 2*tan(a / 2); Wherein, L is the length of the major axis of the ellipse, R is the length of the minor axis of the ellipse; and a is the field angle of the diffraction optical waveguide component in the major axis direction.

6. The diffractive optical waveguide component according to claim 5, wherein Taking the end of the out-coupling grating whose long axis is far away from the diffraction waveguide component as the origin, the diffraction efficiency of the elliptical in-coupling grating along the long axis direction satisfies: where d is the distance from the origin along the long axis direction, and η d is the diffraction efficiency of the grating coupled in at a distance d from the origin along the long axis direction, R is the length of the minor axis of the ellipse; a is the field of view angle of the diffractive optical waveguide component in the long axis direction, and η is the diffraction efficiency of the grating coupled in at the origin.

7. The diffractive optical waveguide component according to any one of claims 1 to 6, characterized in that The coupling-in grating is a blazed grating or a tilted grating.

8. The diffractive optical waveguide component according to claim 7, characterized in that, When the coupling-in grating is a blazed grating, the blaze angle of the coupling-in grating is greater than 30 degrees.

9. The diffractive optical waveguide component according to claim 7, characterized in that, When the coupling-in grating is a tilted grating, the tilt angle of the tilted grating is greater than 45 degrees.

10. A near-eye display device, characterized in that, It comprises an optical machine, and a diffractive optical waveguide component as claimed in any one of claims 1 to 9 arranged on the light output side of the optical machine; The optical machine is used to emit polarized light having the same polarization direction as that of the polarizer.

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