Light guide system and display device

Abstract

The utility model relates to a light guide system and a display device, the light guide system comprises an optical waveguide, a coupling-in grating and a polarization coupling-out assembly, and the coupling-in grating and the polarization coupling-out assembly are both arranged on the surface of the optical waveguide. The polarization out-coupling assembly comprises an out-coupling grating and a polarization conversion element. The orthographic projection of the polarization conversion element on the surface of the optical waveguide and the orthographic projection of the out-coupling grating on the surface of the optical waveguide are mutually overlapped. Laser enters the optical waveguide through the coupling-in grating to be propagated and is coupled out of the optical waveguide as first light and second light after being acted by the polarization coupling-out assembly, and the polarization states of the first light and the second light are different. The light guide system provided by the utility model effectively inhibits interference and improves image quality.

Description

Technical Field

[0001] This application relates to the technical field of light-emitting displays, and particularly relates to a light guide system and a display device. Background Art

[0002] Augmented reality is a display technology that collects real-world information in real time and combines virtual information, images, etc. with the real world. The micro-optical engine used in augmented reality devices is a device for generating image light. Currently, there are also many solutions for the optical engine in near-eye displays. The current mainstream ones include the DLP (Digital Light Processing) solution, the LCOS (Liquid Crystal on Silicon) solution, and the LBS (Laser Scanning) solution.

[0003] The LBS optical engine has the advantages of extremely small volume, high brightness, high contrast, less image retention, low power consumption, and longer battery life, etc. It is generally considered to be the most potential micro-projection display device. However, since the emitted light is linearly polarized laser light, its emitted light spot has the characteristic of coherence. Therefore, when using the LBS optical engine in combination with a diffractive waveguide sheet, due to the pupil expansion effect of the diffractive grating waveguide sheet on the light spot, the light spots that meet the three coherence conditions will produce severe interference, resulting in obvious interference observed within the viewing field and seriously damaging the image quality. Summary of the Utility Model

[0004] Embodiments of this application provide a light guide system and a display device.

[0005] In a first aspect, embodiments of this application provide a light guide system for conducting the laser emitted by a laser light source to a target position. The light guide system includes an optical waveguide, an input grating, and a polarization output component. Both the input grating and the polarization output component are disposed on the surface of the optical waveguide. The polarization output component includes an output grating and a polarization conversion element. The orthographic projection of the polarization conversion element on the surface of the optical waveguide overlaps with the orthographic projection of the output grating on the surface of the optical waveguide. The laser enters the optical waveguide through the input grating and propagates therein. After the action of the polarization output component, the laser is output from the optical waveguide as a first light ray and a second light ray, and the polarization states of the first light ray and the second light ray are different.

[0006] In some alternative embodiments, the optical waveguide has a first surface and a second surface disposed opposite to each other. Among them, the first surface is used to be disposed opposite to the laser light source. The input grating is a transmissive grating, and the input grating is disposed on the first surface; the output grating is a reflective grating, and the output grating is disposed on the second surface.

[0007] In some alternative embodiments, the polarization conversion element is disposed on the first surface; or the polarization conversion element is disposed on the second surface, and the polarization conversion element is stacked between the optical waveguide and the output grating.

[0008] In some alternative embodiments, the optical waveguide has a first surface and a second surface disposed opposite to each other, wherein the first surface is for being disposed opposite to the laser light source, the coupling grating is a transmissive grating, and the coupling grating is disposed on the first surface; the output coupling grating is a transmissive grating, the output coupling grating is disposed on the first surface, and the coupling grating and the output coupling grating are arranged at intervals along the light propagation direction defined by the optical waveguide.

[0009] In some alternative embodiments, the polarization conversion element is disposed on the first surface, and the polarization conversion element is stacked between the optical waveguide and the output coupling grating; or the polarization conversion element is disposed on the second surface.

[0010] In some alternative embodiments, the optical waveguide has a first surface and a second surface disposed opposite to each other, wherein the first surface is for being disposed opposite to the laser light source, the coupling grating is a reflective grating, the coupling grating is disposed on the second surface, the output coupling grating is a transmissive grating, and the output coupling grating is disposed on the first surface.

[0011] In some alternative embodiments, the polarization conversion element is disposed on the first surface, and the polarization conversion element is stacked between the optical waveguide and the output coupling grating; or the polarization conversion element is disposed on the second surface.

[0012] In some alternative embodiments, the optical waveguide has a first surface and a second surface disposed opposite to each other, wherein the first surface is for being disposed opposite to the laser light source, the coupling grating is a reflective grating, the coupling grating is disposed on the second surface, the output coupling grating is a reflective grating, and the output coupling grating is disposed on the second surface.

[0013] In some alternative embodiments, the polarization conversion element is disposed on the first surface; or the polarization conversion element is disposed on the second surface, and the polarization conversion element is stacked between the optical waveguide and the output coupling grating.

[0014] In some alternative embodiments, the polarization conversion element is a quarter-wave plate.

[0015] In some alternative embodiments, the output coupling grating includes at least one of the following structures: a holographic grating, a relief grating.

[0016] In a second aspect, an embodiment of the present application further provides a display device, including a laser light source and the light guiding system according to any one of the above, the laser light source is configured to emit laser light, and the light guiding system is disposed on one side of the laser light source and on the optical path of the laser light.

[0017] When the light guide system provided by the embodiment of the present application is in use, compared with the prior art, a laser light source emits laser light, and the laser light is coupled into an optical waveguide through a coupling grating and propagates in the optical waveguide. After the action of a polarization coupling and output component, first light rays and second light rays with different polarization states are coupled out of the optical waveguide. Only two light beams with the same polarization state can interfere. The first light rays and the second light rays coupled out by the optical waveguide provided by the embodiment of the present application have different polarization states, which can effectively suppress the interference phenomenon in the optical waveguide and improve the quality of the image. Brief Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0019] Figure 1 It is a simplified structural schematic diagram of a display device provided by an embodiment of the present application.

[0020] Figure 2 is Figure 1 A simplified structural schematic diagram of another embodiment of the light guide system of the shown display device.

[0021] Figure 3 is Figure 1 A structural schematic diagram of an embodiment in which the coupling grating of the shown light guide system is a transmissive grating.

[0022] Figure 4 is Figure 3 A structural schematic diagram of another embodiment of the shown light guide system.

[0023] Figure 5 is Figure 1 A structural schematic diagram of an embodiment in which the coupling grating of the shown light guide system is a reflective grating.

[0024] Figure 6 is Figure 5 A structural schematic diagram of another embodiment of the shown light guide system.

[0025] Marking Explanation: 100, light guide system; 10, optical waveguide; 12, coupling region; 14, coupling and output region; 16, first surface; 17, side wall; 18, second surface; 30, polarization coupling and output component; 32, coupling grating; 34, polarization conversion element; 50, coupling device; 200, light source device; 201, light source; 300, display device; 301, display. Detailed Embodiments

[0026] To enable those skilled in the art to better understand the solution of this application, the following will clearly and completely describe the technical solutions in the embodiments of this application with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of protection of this application.

[0027] As used in the specification and claims, certain terms are used to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different terms to refer to the same component. The specification and claims do not use the difference in names as a way to distinguish components, but use the difference in functions of components as the criterion for distinction. As mentioned throughout the specification and claims, "including" is an open-ended term and should be interpreted as "including but not limited to"; "substantially" means that those skilled in the art can solve technical problems within a certain error range and basically achieve the technical effect.

[0028] Please refer to Figure 1 , the embodiment of this application provides a light source device 200, which is applied to a display device 300 and is used to generate a projection display image.

[0029] This specification does not limit the specific type of the display device 300. For example, the display device 300 can be applied to head-mounted displays (HMDs), head-up displays (HUDs), and other wearable glasses devices. Of course, the display device 300 can also be a projector. In this embodiment, the display device 300 includes a light source device 200 and a display 301. The light source device 200 includes a laser light source 201 and a light guiding system 100. Among them, the laser light source 201 is used to emit laser light, and the light guiding system 100 is arranged on one side of the laser light source 201 and is located on the optical path of the laser. The light guiding system 100 is used to conduct the laser light emitted by the laser light source 201 to the display 301. The optical waveguide of the light guiding system 100 is provided with an input area 12 and an output area 14. The input area 12 is located on the optical path of the laser light emitted by the laser light source 201. The display 301 is located on the optical path of the light output through the output area 14.

[0030] During operation, the laser light source 201 emits laser light, which enters the optical waveguide of the light guiding system 100 through the coupling-in region 12 and propagates within the optical waveguide of the light guiding system 100 at a certain angle. When the light beam is incident on the interface between the optical waveguide of the light guiding system 100 and air, total internal reflection occurs, which ensures that the light beam can propagate along a set path within the optical waveguide of the light guiding system 100 and thus reach the coupling-out region 14. Finally, it leaves the optical waveguide of the light guiding system 100 through the coupling-out region 14 and enters the display 301. The display 301 modulates the light beam and conducts the modulated light beam to the human eye.

[0031] In the description of the present application, it should be understood that the terms "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "inside", etc. indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0032] The present specification does not limit the specific type of the laser light source 201. For example, the laser light source 201 can adopt a linearly polarized laser, or a non-polarized light source such as an LED (light emitting diode), or a combination of other lasers and polarizers to collimate and homogenize the emitted light beam into a uniform light spot. The display 301 is used to generate an image source and control the pixel brightness in the image. The display 301 is a non-active light-emitting optical display device. The present specification does not limit the specific type of the display 301. For example, the display 301 can be an LCOS (liquid crystal on silicon) display panel, or an LCD (liquid crystal display).

[0033] The light guiding system 100 is used to constrain the propagation path of the laser emitted by the laser light source 201, and conduct the light emitted by the laser light source 201 to the target position. Herein, the "target position" can be the non-active light-emitting chip of the display device. In this embodiment, the "target position" is the surface of the display 301 close to the light guiding system 100. The light guiding system 100 may include an optical waveguide 10, an input grating 50, and a polarization output component 30. The above-mentioned input region 12 and output region 14 are provided on the surface of the optical waveguide 10. Both the input grating 50 and the polarization output component 30 are disposed on the surface of the optical waveguide 10. Among them, the input grating 50 is disposed in the output region 14. The polarization output component 30 includes an output grating 32 and a polarization conversion element 34. The output grating 32 is disposed in the output region 14, and the orthographic projection of the polarization conversion element 34 on the surface of the optical waveguide 10 overlaps with the orthographic projection of the output grating 32 on the surface of the optical waveguide 10. The laser enters the optical waveguide 10 through the input grating 50 and propagates along the light propagation direction X defined by the optical waveguide 10. After being acted on by the polarization output component 30, the laser is output from the optical waveguide 10 as a first light ray A and a second light ray B, and the polarization states of the first light ray A and the second light ray B are different. Both the first light ray A and the second light ray B are output through the output region 14 and are both emitted along the specified direction Z.

[0034] During use, the laser light source 201 emits a laser, the laser is coupled into the optical waveguide 10 through the input grating 50, and propagates along the light propagation direction X in the optical waveguide 10. After the laser in the optical waveguide 10 is acted on by the polarization output component 30, the laser is output from the optical waveguide 10 as a first light ray A and a second light ray B with different polarization states. The first light ray A and the second light ray B are output through the output region 14 and are emitted along the specified direction Z. Among them, the specified direction Z is perpendicular to the light propagation direction X. If the light propagation direction X is the length direction or the width direction of the optical waveguide 10, the specified direction Z may be the thickness direction of the optical waveguide 10. Only two light beams with the same polarization state can interfere. In the embodiment of the present application, the polarization states of the first light ray A and the second light ray B output from the optical waveguide 10 are different, which can effectively suppress the interference phenomenon in the optical waveguide 10 and improve the quality of the image.

[0035] In this embodiment, the optical waveguide 10 is a guiding structure for transmitting optical frequency electromagnetic waves composed of a light-transparent medium (such as quartz glass), and is a device for guiding waves to propagate therein. It is used to limit the propagation path of the light beam in space. When the propagation angle of the light beam satisfies the total reflection condition, it can only propagate in the optical waveguide 10. This specification does not limit the specific type of the optical waveguide 10, and the optical waveguide 10 can be made into a very thin and light flat glass form. In this embodiment, the optical waveguide 10 may be a glass plate 101. The refractive index of the glass plate 101 is n, the thickness is d, and the total reflection critical angle of the glass plate 101 is θ 0 = arcsin(n a / n), where, na is the refractive index of air. The larger the refractive index n of the optical waveguide 10, the critical angle θ of total internal reflection 0 is smaller. At this time, the angular range in which total internal reflection can occur within the optical waveguide 10 increases, increasing the design freedom.

[0036] The optical waveguide 10 includes a first surface 16, a second surface 18, and a sidewall 17. The first surface 16 and the second surface 18 face away from each other. Among them, the first surface 16 can be arranged facing the laser light source 201, the second surface 18 can be arranged facing the display 301, and the sidewall 17 is connected between the first surface 16 and the second surface 18. In some other embodiments, the laser light source 201 and the display 301 can be arranged on the same side of the optical waveguide 10. For example, both the laser light source 201 and the display 301 can be located on the side of the optical waveguide 10 where the first surface 16 is provided, or on the side of the optical waveguide 10 where the second surface 18 is provided. In this embodiment, both the laser light source 201 and the display 301 are located on the side of the optical waveguide 10 where the first surface 16 is provided, and the first surface 16 is both the light incident surface and the light exit surface of the optical waveguide 10. The optical waveguide 10 can be presented in a flat plate shape as a whole. Therefore, the first surface 16 and the second surface 18 can be planes. In other embodiments, the optical waveguide 10 can be presented in a curved plate shape, and the first surface 16 and the second surface 18 can be a concave surface and a convex surface respectively; the outer shape of the optical waveguide 10 can be presented in a circular plate shape, and the first surface 16 and the second surface 18 can both be arc-shaped surfaces.

[0037] In this application, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" can explicitly or implicitly include at least one of such features. In the description of this application, "a plurality of" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0038] The input grating 50 is used to change the propagation angle of the laser light emitted by the laser light source 201, so that the propagation of the light beam in the optical waveguide 10 satisfies the total reflection condition. The output grating 32 is used to break the propagation of light in the optical waveguide 10 so that the light can be coupled out to the outside. This specification does not limit the specific types of the input grating 50 and the output grating 32. For example, the input grating 50 includes at least one of the following structures: a relief grating, a holographic grating. The output grating 32 can include at least one of the following structures: a holographic grating, a relief grating. A grating is a dispersion element that uses the interference and diffraction phenomena of light for spectral splitting. Among them, a holographic grating mainly uses the principle of optical coherent superposition. For example, by adjusting the complex term (time term), the peaks of two light wave trains are superposed, and the peaks and valleys are superposed to achieve a higher contrast in the coherent field. The relief grating solution has the advantages of a thin and light design structure, a high degree of design freedom, and a relatively low cost when combined with nanoimprinting. In this embodiment, the optical waveguide 10 also serves as the substrate of the input grating 50 and / or the output grating 32, so that the input grating 50 and / or the output grating 32 can be attached thereto.

[0039] This specification does not limit the specific methods of the coupling method of the input grating 50 and the output method of the output grating 32. Among them, the input grating 50 can be a transmissive grating for transmissive coupling or a reflective grating for reflective coupling. The output grating 32 can be a transmissive grating for transmissive output or a reflective grating for reflective output.

[0040] This specification does not limit the specific positions of the input grating 50 and the output grating 32. For example, the input grating 50 and the output grating 32 can be arranged on the same side of the optical waveguide 10, both arranged on the first surface 16 or the second surface 18. The input grating 50 can also be arranged on different sides of the optical waveguide 10 from the output grating 32. For example, the input grating 50 and the output grating 32 are respectively arranged on the first surface 16 and the second surface 18. Or, the input grating 50 and / or the output grating 32 can also be arranged on the side wall 17. The input grating 50 and the output grating 32 are arranged at intervals in the light propagation direction X. This specification does not limit the specific direction of the light propagation direction X. For example, the light propagation direction X can be the length direction of the optical waveguide 10 or the width direction of the optical waveguide 10. In this embodiment, the light propagation direction X is the length direction of the optical waveguide 10, and the specified direction Z is the thickness direction of the optical waveguide 10.

[0041] In this embodiment, the first surface 16 is arranged opposite to the laser light source 201, and the first surface 16 is the light incident surface of the optical waveguide 10. As an example, please refer to Figure 1, the input grating 50 is a transmissive grating, the input grating 50 is disposed on the first surface 16, the output grating 32 is a reflective grating, and the output grating 32 is disposed on the second surface 18. The laser is incident from the input grating 50 on the first surface 16, is coupled into the optical waveguide 10 through the transmission of the input grating 50, and propagates along the optical propagation direction X to the output grating 32 on the second surface 18. The output grating 32 couples out the laser from the first surface 16 in a reflective coupling-out manner.

[0042] The polarization conversion element 34 is disposed on one side of the optical waveguide 10, and is used to change the polarization state of the laser. In this embodiment, the polarization conversion element 34 is a quarter-wave plate. The quarter-wave plate is also called a "quarter-wave retarder plate", and is a birefringent single-crystal wave plate with a certain thickness. When light is incident normally and transmitted through the quarter-wave plate, the phase difference between the ordinary light and the extraordinary light is equal to π / 2 or an odd multiple thereof. Such a wafer is called a quarter-wave plate or a 1 / 4 wave plate. In the optical path, the quarter-wave plate 40 is often used to change linearly polarized light into circularly polarized light or elliptically polarized light, or to change circularly polarized light or elliptically polarized light into linearly polarized light. The quarter-wave plate is easy to manufacture, has a small thickness and a light weight, and can be well applied to near-eye displays. The laser is linearly polarized light, and both the first light ray A and the second light ray B formed by the conversion of the linearly polarized light under the action of the quarter-wave plate are circularly polarized light or elliptically polarized light.

[0043] This specification does not limit the specific position of the polarization conversion element 34 on the optical waveguide 10. For example, the polarization conversion element 34 can be disposed on the first surface 16; or, the polarization conversion element 34 can also be disposed on the second surface 18, and the polarization conversion element 34 is stacked between the optical waveguide 10 and the output grating 32.

[0044] As an example, the polarization conversion element 34 and the output grating 32 are respectively disposed on opposite sides of the optical waveguide 10. The polarization conversion element 34 is disposed on the first surface 16 and is located on the optical path of the output grating 32 for reflecting and coupling out light. The projection of the polarization conversion element 34 on one side surface of the optical waveguide 10 coincides with the projection of the output grating 32 on one side surface of the optical waveguide 10, or the projection of the output grating 32 on one side surface of the optical waveguide 10 falls within the projection of the polarization conversion element 34 on one side surface of the optical waveguide 10. In this example, the output grating 32 can be a relief grating or a holographic grating.

[0045] This specification does not limit the specific polarization states of the first light ray A and the second light ray B coupled out by the optical waveguide 10. As an example, the polarization rotation directions of the polarization states of the first light ray A and the second light ray B are opposite. For example, if the polarization state of the first light ray A is right-handed polarization, then the polarization state of the second light ray B is left-handed polarization; or, if the polarization state of the first light ray A is left-handed polarization, then the polarization state of the second light ray B is right-handed polarization.

[0046] The laser is linearly polarized light. Taking the example of P-polarized light (hereinafter referred to as P-light) being coupled into the optical waveguide 10, the P-light propagates along the light propagation direction X to the polarization coupler 30. The P-light propagates to the coupler grating 32, and the coupler grating 32 reflects the P-light to couple it out from the first surface 16. The P-light propagates to the quarter-wave plate (polarization coupler element 32) on the first surface 16, and is converted into the first ray A (right-handed polarization) through the quarter-wave plate and propagates to the target position. The refractive index of the quarter-wave plate is greater than that of air. Part of the P-light is incident on the quarter-wave plate at an angle greater than the total reflection angle and is reflected back into the optical waveguide 10. That is, after passing through the quarter-wave plate twice, the P-light is converted into S-light (S-polarized light, whose polarization direction is perpendicular to that of the P-light). The S-light continues to propagate in the optical waveguide 10. The S-light reaches the coupler grating 32 and is reflected and coupled out to the quarter-wave plate again, and is converted into the second ray B (left-handed polarization) through the quarter-wave plate and propagates to the target position. Part of the S-light is reflected back into the optical waveguide 10 after reaching the quarter-wave plate. That is, after passing through the quarter-wave plate twice, the S-light is converted into P-light. The P-light propagates to the coupler grating 32, is reflected and coupled out of the optical waveguide 10 by the coupler grating 32, and then is converted into the first ray A (right-handed polarization) again through the quarter-wave plate and propagates to the target position.

[0047] In the light propagation direction X, the first beam of light coupled out from the optical waveguide 10 to the target position is the first ray A with right-handed polarization, the second beam of light is the second ray B with left-handed polarization, and the third beam of light is again the first ray A with right-handed polarization, and so on. The light rays coupled out from the optical waveguide 10 to the target position are the first ray A and the second ray B alternating, that is, right-handed polarization and left-handed polarization alternating, effectively suppressing the interference phenomenon in the optical waveguide 10 and improving the quality of the image. Further, the quarter-wave plate increases the optical path difference between the coupled-out lights with the same polarization state (such as the first beam and the third beam with the same right-handed polarization above) to twice the original value, reducing the possibility of interference and further improving the quality of the image.

[0048] As another example, a polarization conversion element 34 is disposed on the second surface 18, and the polarization conversion element 34 is stacked between the optical waveguide 10 and the output grating 32. Taking the case where P-polarized light is coupled into the optical waveguide 10 as an example, the P-polarized light is coupled into the optical waveguide 10 through the transmissive input grating 50 on the first surface 16, and propagates along the light propagation direction X to the polarization output assembly 30 on the second surface 18. A quarter-wave plate (polarization conversion element 34) is stacked between the optical waveguide 10 and the output grating 32. The P-polarized light propagates through the quarter-wave plate to the output grating 32, and is output from the first surface 16 by the output grating 32 in a reflection output manner. During the output process, the P-polarized light passes through the quarter-wave plate again. After passing through the quarter-wave plate twice, the P-polarized light is converted into S-polarized light (the first light ray A). Part of the S-polarized light is not output from the optical waveguide 10 and continues to propagate in the optical waveguide 10. The S-polarized light passes through the quarter-wave plate and is reflected and output by the output grating 32. During the output process, the S-polarized light passes through the quarter-wave plate again. After passing through the quarter-wave plate twice, the S-polarized light is converted into P-polarized light (the second light ray B). Part of the P-polarized light is not output from the optical waveguide 10 and continues to propagate in the optical waveguide 10. The P-polarized light passes through the quarter-wave plate and is reflected and output by the output grating 32. During the output process, the P-polarized light passes through the quarter-wave plate again. After passing through the quarter-wave plate twice, the P-polarized light is converted into S-polarized light (the first light ray A) again.

[0049] In the light propagation direction X, the first beam of light (the first light ray A) output from the optical waveguide 10 to the target position is S-polarized light, the second beam of light (the second light ray B) is P-polarized light, and the third beam of light (the first light ray A) is S-polarized light again, and so on. The light rays output from the optical waveguide 10 to the target position are the first light ray A and the second light ray B alternating, that is, the S-polarized light and the P-polarized light alternating, effectively suppressing the interference phenomenon in the optical waveguide 10 and improving the quality of the image. Further, the quarter-wave plate increases the optical path difference between the output light with the same polarization state (such as the first light beam and the third light beam which are both P-polarized light above) to twice the original, reducing the possibility of interference and further improving the quality of the image.

[0050] The polarization conversion element 34 can also be a half-wave plate. As an example, the half-wave plate can be stacked on the side of the output grating 32 away from the optical waveguide 10, and a plurality of half-wave plates are provided. The plurality of half-wave plates are arranged at intervals along the light propagation direction on the output grating 32. Taking the case where the laser is linearly polarized light and P-polarized light is coupled into the optical waveguide 10 as an example, the P-polarized light propagates along the light propagation direction X to the polarization output assembly 30. The P-polarized light propagates to the output grating 32 and is output as the first light ray A in the position without the half-wave plate, and is converted into S-polarized light and output as the second light ray B in the position with the half-wave plate.

[0051] In some other embodiments, please refer to Figure 3, the input grating 50 is a transmissive grating, the input grating 50 is disposed on the first surface 16, the output grating 32 is also a transmissive grating, and the output grating 32 is also disposed on the first surface 16. The laser is incident from the input grating 50 on the first surface 16, is coupled into the optical waveguide 10 through the transmission of the input grating 50, and propagates along the optical propagation direction X to the output grating 32 on the first surface 16. The output grating 32 couples out the laser from the first surface 16 in a transmissive coupling-out manner.

[0052] The polarization conversion element 34 can be disposed on the first surface 16, and the polarization conversion element 34 is stacked between the optical waveguide 10 and the output grating 32; alternatively, the polarization conversion element 34 can also be disposed on the second surface 18.

[0053] When the polarization conversion element 34 is disposed on the second surface 18, taking the example of P-polarized light being coupled into the optical waveguide 10, the P light is coupled into the optical waveguide 10 through the transmissive input grating 50 on the first surface 16, and propagates along the optical propagation direction X to the polarization output component 30 on the second surface 18. The P light is directly coupled out as the first light ray A through the transmissive output grating 32 on the first surface 16. Part of the P light is not coupled out of the optical waveguide 10 and continues to propagate in the optical waveguide 10, and propagates to the quarter-wave plate (polarization conversion element 34) on the second surface 18. The refractive index of the quarter-wave plate is greater than the refractive index of air, and the incident angle of part of the P light on the quarter-wave plate is greater than the total reflection angle and is reflected back into the optical waveguide 10, that is, after passing through the quarter-wave plate twice, the P light is converted into S light, and the S light propagates to the output grating 32 and is coupled out as the second light ray B.

[0054] As another example, please refer to Figure 4 , when the polarization conversion element 34 is disposed on the first surface 16, the polarization conversion element 34 is stacked between the optical waveguide 10 and the output grating 32. The P light is coupled into the optical waveguide 10 and is coupled out as the first light ray A (right-handed polarization) through the transmissive output grating 32 after being converted by the quarter-wave plate on the first surface 16. Part of the P light is not coupled out of the optical waveguide 10 and continues to propagate in the optical waveguide 10 after passing through the quarter-wave plate. At this time, the P light is converted into S light after passing through the quarter-wave plate twice. The S light propagates in the optical waveguide 10 to the quarter-wave plate on the first surface 16, is converted by the quarter-wave plate, and is coupled out by the output grating 32 as the second light ray B (left-handed polarization).

[0055] In other embodiments, the coupling grating 50 may also be a reflective grating. As an example, the coupling grating 50 is a reflective grating, the coupling grating 50 is disposed on the second surface 18, the output coupling grating 32 is a transmissive grating, and the output coupling grating 32 is disposed on the first surface 16. The laser is incident from the first surface 16, propagates to the reflective coupling grating 50 on the second surface 18, is reflected by the coupling grating 50 and coupled into the optical waveguide 10, propagates along the optical propagation direction X to the output coupling grating 32 on the first surface 16, and the output coupling grating 32 couples out the laser from the first surface 16 in a transmissive coupling manner.

[0056] In this example, referring to Figure 5 , the polarization conversion element 34 may be disposed on the first surface 16, and the polarization conversion element 34 is stacked between the optical waveguide 10 and the output coupling grating 32; or, referring to Figure 6 , the polarization conversion element 34 may also be disposed on the second surface 18.

[0057] As another example, the coupling grating 50 is a reflective grating, the coupling grating 50 is disposed on the second surface 18, the output coupling grating 32 is also a reflective grating, and the output coupling grating 32 is also disposed on the second surface 18. The laser is incident from the first surface 16, propagates to the reflective coupling grating 50 on the second surface 18, is reflected by the coupling grating 50 and coupled into the optical waveguide 10, propagates along the optical propagation direction X to the output coupling grating 32 on the first surface 18, and the output coupling grating 32 couples out the laser from the first surface 16 in a reflective coupling manner. In this example, the polarization conversion element 34 may be disposed on the first surface 16; the polarization conversion element 34 may also be disposed on the second surface 18, and the polarization conversion element 34 is stacked between the optical waveguide 10 and the output coupling grating 32.

[0058] When the light guiding system 100 provided in the embodiment of the present application is used, the laser light source 201 emits laser light, the laser light is coupled into the optical waveguide 10 through the coupling grating 50, and propagates along the optical propagation direction X in the optical waveguide 10. After the laser light in the optical waveguide 10 acts on the polarization output coupling component 30, the first light ray A and the second light ray B with different polarization states are coupled out from the optical waveguide 10, and the first light ray A and the second light ray B are coupled out through the output coupling area 14 and emitted along the specified direction Z. Wherein, the specified direction Z is perpendicular to the optical propagation direction X. If the optical propagation direction X is the length direction or the width direction of the optical waveguide 10, the specified direction Z may be the thickness direction of the optical waveguide 10. Only two light beams with the same polarization state can interfere. The polarization states of the first light ray A and the second light ray B coupled out from the optical waveguide 10 in the embodiment of the present application are different, which can effectively suppress the interference phenomenon in the optical waveguide 10 and improve the quality of the image.

[0059] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A light guide system, characterized in that: Used to transmit the laser light emitted by the laser light source to the target position, the light guiding system includes an optical waveguide, an in-coupling grating and a polarization out-coupling component, wherein: The coupling-in grating and the polarization coupling-out component are both arranged on the surface of the optical waveguide; The polarization outcoupling component comprises an outcoupling grating and a polarization conversion element, wherein the orthographic projection of the polarization conversion element on the surface of the optical waveguide overlaps with the orthographic projection of the outcoupling grating on the surface of the optical waveguide; The laser enters the optical waveguide through the coupling-in grating to propagate, and is coupled out of the optical waveguide as a first light ray and a second light ray after being acted upon by the polarization coupling-out component. The first light ray and the second light ray have different polarization states.

2. The light guide system according to claim 1, characterized in that The optical waveguide has a first surface and a second surface that are arranged opposite to each other, wherein the first surface is used to be arranged opposite to the laser light source, the coupling-in grating is a transmission grating, and the coupling-in grating is arranged on the first surface; the coupling-out grating is a reflection grating, and the coupling-out grating is arranged on the second surface.

3. The light guide system according to claim 2, characterized in that: The polarization conversion element is disposed on the first surface; or The polarization conversion element is disposed on the second surface, and the polarization conversion element is stacked between the optical waveguide and the outcoupling grating.

4. The light guide system according to claim 1, wherein: The optical waveguide has a first surface and a second surface that are arranged opposite to each other, wherein the first surface is used to be arranged opposite to the laser light source, the coupling-in grating is a transmission grating, and the coupling-in grating is arranged on the first surface; the coupling-out grating is a transmission grating, and the coupling-out grating is arranged on the first surface, and the coupling-in grating and the coupling-out grating are arranged at intervals along the light propagation direction defined by the optical waveguide.

5. The light guide system according to claim 4, characterized in that: The polarization conversion element is disposed on the first surface, and the polarization conversion element is stacked between the optical waveguide and the outcoupling grating; or The polarization conversion element is disposed on the second surface.

6. The light guide system according to claim 1, wherein: The optical waveguide has a first surface and a second surface arranged in opposite directions, wherein the first surface is used to be arranged opposite to the laser light source, the coupling-in grating is a reflective grating arranged on the second surface, and the coupling-out grating is a transmission grating arranged on the first surface.

7. The light guide system according to claim 6, characterized in that: The polarization conversion element is disposed on the first surface, and the polarization conversion element is stacked between the optical waveguide and the outcoupling grating; or The polarization conversion element is disposed on the second surface.

8. The light guide system according to claim 1, wherein: The optical waveguide has a first surface and a second surface arranged in opposite directions, wherein the first surface is used to be arranged opposite to the laser light source, the coupling-in grating is a reflective grating arranged on the second surface, and the coupling-out grating is a reflective grating arranged on the second surface.

9. The light guide system according to claim 8, characterized in that: The polarization conversion element is disposed on the first surface; or The polarization conversion element is disposed on the second surface, and the polarization conversion element is stacked between the optical waveguide and the outcoupling grating.

10. The light guide system according to any one of claims 1 to 9, characterized in that: The polarization conversion element is a quarter wave plate.

11. The light guide system according to any one of claims 1 to 9, characterized in that: The outcoupling grating comprises at least one of the following structures: a holographic grating and a relief grating.

12. A display device, characterized in that: include: A laser light source, used for emitting laser; And the light guiding system according to any one of claims 1 to 11, wherein the light guiding system is arranged on one side of the laser light source and is located on the optical path of the laser.

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