Optical transmission structure and method of manufacturing the same, display device

Abstract

This disclosure provides an optical transmission structure and its fabrication method, as well as a display device, belonging to the field of display technology. The optical transmission structure includes: an optical waveguide; a coupling grating located on a first surface of the optical waveguide and a coupling grating located on a second surface of the optical waveguide. The coupling grating is used to couple incident light into the optical waveguide; wherein the first surface and the second surface form a preset angle, such that a zero-order diffracted beam transmitted through the coupling grating into the optical waveguide undergoes total internal reflection within the optical waveguide; the coupling grating is used to couple out outgoing light from the optical waveguide. The technical solution of this disclosure can improve light energy utilization.

Description

Technical Field

[0001] This disclosure relates to the field of display technology, and in particular to an optical transmission structure and its manufacturing method, and a display device. Background Technology

[0002] Since the concept of the "metaverse" was proposed, virtual reality (VR) and augmented reality (AR) have gained more attention, with many technology companies increasing their R&D efforts in hopes of developing related consumer products as soon as possible. In the AR field, AR glasses have received the most attention, and their implementation methods are generally divided into geometric optics and diffraction optics solutions. Among these, diffraction optics solutions are favored by the industry due to their ability to produce thinner and more transparent products. Within diffraction optics solutions, surface relief grating (SRG) diffraction waveguides are currently a highly popular option due to their greater mass production capabilities.

[0003] SRG waveguide gratings mainly include rectangular gratings, tilted gratings, and blazed gratings. Among them, rectangular gratings are the most widely used grating type in the market due to their lowest fabrication difficulty. However, in related technologies, SRG waveguide gratings have low light utilization, resulting in low brightness of the final image reaching the human eye. Summary of the Invention

[0004] The technical problem to be solved by this disclosure is to provide an optical transmission structure and its manufacturing method, as well as a display device, which can improve the light energy utilization rate.

[0005] To address the aforementioned technical problems, the embodiments of this disclosure provide the following technical solutions:

[0006] On the one hand, an optical transmission structure is provided, comprising:

[0007] Optical waveguide;

[0008] A coupling grating is located on a first surface of the optical waveguide and a coupling grating is located on a second surface of the optical waveguide. The coupling grating is used to couple incident light into the optical waveguide.

[0009] The first surface and the second surface are at a preset angle, such that the zero-order diffracted beam transmitted to the optical waveguide via the coupling grating undergoes total internal reflection within the optical waveguide, and the coupling grating is used to couple the outgoing light out of the optical waveguide.

[0010] In some embodiments, the incident light rays are incident on the optical transmission structure perpendicular to the first surface.

[0011] In some embodiments, the incident light is an image light.

[0012] In some embodiments, the grating periods of the coupled-in grating and the coupled-out grating are the same.

[0013] In some embodiments, the coupled-in grating and / or the coupled-out grating are rectangular gratings with a period of 300-600 nm.

[0014] In some embodiments, the height of the rectangular grating is 30-500 nm.

[0015] In some embodiments, the optical waveguide includes:

[0016] Optical waveguide body;

[0017] A prism portion disposed on the second surface of the optical waveguide body, the prism portion including a first surface protruding from the optical waveguide body.

[0018] In some embodiments, the refractive index of the prism is n1, the refractive index of the optical waveguide body is n2, the incident angle of the zero-order diffracted beam on the optical waveguide body is θ1, and the refraction angle is θ2, where θ1 and θ2 satisfy:

[0019] n1sinθ1=n2sinθ2, where θ2≥θ c θ c The critical angle for total internal reflection of the optical waveguide body is given.

[0020] In some embodiments, L is the width of the prism portion in a first direction, which is parallel to the second surface and is the direction from the coupling grating to the coupling grating, S is the propagation step size of the zero-order diffracted beam in the optical waveguide body, S = 2dtanθ2, and L and S satisfy: L < S, where d is the thickness of the optical waveguide body.

[0021] In some embodiments, the value of n1 ranges from 1.5 to 2.0;

[0022] The value of n2 ranges from 1.5 to 2.0.

[0023] In some embodiments, n1 and n2 are equal.

[0024] In some embodiments, the optical waveguide includes:

[0025] An optical waveguide body, wherein the light-incident surface and the light-exit surface of the optical waveguide body form a preset angle; wherein the light-incident surface is the first surface, the light-exit surface is the second surface, and the preset angle is greater than the critical angle for total internal reflection of the optical waveguide body.

[0026] This disclosure also provides a display device including the optical transmission structure described above.

[0027] This disclosure also provides a method for fabricating an optical transmission structure, including:

[0028] Forming an optical waveguide;

[0029] A coupling grating is formed on the first surface of the optical waveguide, the coupling grating being used to couple incident light rays into the optical waveguide;

[0030] A coupling grating is formed on the second surface of the optical waveguide;

[0031] The first surface and the second surface are at a preset angle, such that the zero-order diffracted beam transmitted to the optical waveguide via the coupling grating undergoes total internal reflection within the optical waveguide, and the coupling grating is used to couple the outgoing light out of the optical waveguide.

[0032] In some embodiments, forming the optical waveguide includes:

[0033] The optical waveguide body and the prism section are formed respectively;

[0034] The prism portion is attached to the second surface of the optical waveguide body, such that the first surface of the prism portion protrudes from the optical waveguide body.

[0035] In some embodiments, forming the optical waveguide includes:

[0036] Provide a waveguide substrate;

[0037] The waveguide substrate is cut to form an optical waveguide body and a prism portion located on a second surface of the optical waveguide body. The prism portion includes a first surface protruding from the optical waveguide body.

[0038] In some embodiments, forming a coupling grating on the first surface of the optical waveguide includes:

[0039] The coupling grating was fabricated on a flexible substrate using a nanoimprint method.

[0040] A flexible substrate carrying the coupling grating is attached to the waveguide coupling region of the first surface.

[0041] In some embodiments, forming a coupling grating on a second surface of the optical waveguide includes:

[0042] The coupled grating was fabricated on a flexible substrate using a nanoimprint method;

[0043] The flexible substrate carrying the coupling grating is attached to the waveguide coupling region of the second surface.

[0044] In some embodiments, forming the optical waveguide includes:

[0045] Provide a waveguide substrate;

[0046] The waveguide substrate is cut to form an optical waveguide body, and the light-incident surface and the light-exit surface of the optical waveguide body form a preset angle; wherein, the light-incident surface is the first surface, the light-exit surface is the second surface, and the preset angle is greater than the critical angle of total internal reflection of the optical waveguide body.

[0047] The embodiments disclosed herein have the following beneficial effects:

[0048] In the above scheme, the highest-energy zero-order diffraction beam is used as the information transmission carrier and transmitted by total internal reflection in the optical waveguide, which can improve the overall light energy utilization rate of the optical transmission structure. Attached Figure Description

[0049] Figure 1 This is a schematic diagram showing the distribution of diffraction efficiency of an existing rectangular grating;

[0050] Figure 2 and Figure 3 This is a schematic diagram of light propagation in an optical transmission structure according to an embodiment of the present disclosure;

[0051] Figure 4 This is a schematic diagram of light propagation in an optical transmission structure according to another embodiment of the present disclosure;

[0052] Figure 5 A schematic diagram of the process for fabricating an optical transmission structure according to an embodiment of this disclosure;

[0053] Figure 6 This is a schematic diagram of the process of fabricating a metal transition structure on a silicon substrate according to an embodiment of the present disclosure;

[0054] Figure 7 A schematic diagram illustrating the fabrication of an embossing template according to an embodiment of this disclosure;

[0055] Figure 8 This is a schematic diagram of a rectangular grating fabricated on a flexible substrate according to an embodiment of the present disclosure;

[0056] Figure 9 A schematic diagram of the process for fabricating an optical transmission structure according to another embodiment of this disclosure;

[0057] Figure 10 A schematic diagram illustrating the process of fabricating a prism section and a coupling grating according to an embodiment of this disclosure;

[0058] Figure 11 This is a schematic diagram of the process for fabricating a metal transition structure on a silicon substrate in yet another embodiment of the present disclosure;

[0059] Figure 12 A schematic diagram illustrating the fabrication of an embossing template according to yet another embodiment of this disclosure;

[0060] Figure 13A schematic diagram illustrating the fabrication of an optical waveguide body and a coupling grating according to yet another embodiment of this disclosure;

[0061] Figure 14 A schematic flowchart illustrating the fabrication of an optical transmission structure according to yet another embodiment of this disclosure;

[0062] Figure 15 A schematic flowchart illustrating the fabrication of an optical transmission structure according to another embodiment of this disclosure.

[0063] Figure Labels

[0064] 01 Optical waveguide body 03 Prism section

[0065] 02 Rectangular grating

[0066] 021 Coupled Grating

[0067] 022 Coupled-out grating

[0068] 011 Waveguide substrate

[0069] 012 First Transition Structure

[0070] 013 Optical waveguide

[0071] 04 Silicon substrate

[0072] 05 Metal Layer

[0073] 16 Photoresist

[0074] 051 Metal Transition Structure

[0075] 06 Imprinting template

[0076] 061 Groove

[0077] 07 Rigid substrate

[0078] 08 Adhesive layer

[0079] 09 Flexible substrate

[0080] 10 Grating material layers Detailed Implementation

[0081] To make the technical problems, technical solutions and advantages to be solved by the embodiments of this disclosure clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0082] In SRG AR displays, the highest energy percentages are found in the transmission T0 order (i.e., the zeroth order diffraction order) and the transmission T... ±1 First-order diffraction (i.e., positive first-order and negative first-order diffraction), where T +1 Diffraction orders are information transmission carriers. Figure 1A schematic diagram illustrating the working principle of AR glasses using a rectangular grating as the input and output gratings. Since the rectangular grating has a symmetrical structure, T... -1 and T +1 The diffraction efficiency of each diffraction order is equal (generally less than 20%), and much lower than that of the T0 order diffraction efficiency (generally around 60%), resulting in low light energy utilization and ultimately low brightness of the image entering the human eye.

[0083] The embodiments of this disclosure provide an optical transmission structure and its manufacturing method, as well as a display device, which can improve light energy utilization.

[0084] Embodiments of this disclosure provide an optical transmission structure, including:

[0085] Optical waveguide;

[0086] A coupling grating is located on a first surface of the optical waveguide and a coupling grating is located on a second surface of the optical waveguide. The coupling grating is used to couple incident light into the optical waveguide.

[0087] The first surface and the second surface are at a preset angle, such that the zero-order diffracted beam transmitted to the optical waveguide via the coupling grating undergoes total internal reflection within the optical waveguide, and the coupling grating is used to couple the outgoing light out of the optical waveguide.

[0088] In this embodiment, the highest-energy zero-order diffracted beam is used as the information transmission carrier and transmitted by total internal reflection within the optical waveguide, which can improve the overall light energy utilization of the optical transmission structure.

[0089] In some embodiments, the coupling grating and / or the coupling out grating are rectangular gratings. However, the coupling grating and / or the coupling out grating are not limited to rectangular gratings; they can also be other types of gratings, such as blazed gratings, tilted gratings, etc. When the coupling grating and / or the coupling out grating are rectangular gratings, the intrinsic characteristics of rectangular gratings result in the highest energy at the zero-order diffraction order (T0 order) (generally ≥60%), which is much higher than that at the T0 order. ±1 Diffraction order (T) ±1 With the same diffraction efficiency (generally ≤20%), the light efficiency can be increased by more than 3 times.

[0090] In a specific example, such as Figure 2 and Figure 3As shown, the optical waveguide includes: an optical waveguide body 01; and a prism portion 03 disposed on a second surface 01a of the optical waveguide body 01. The prism portion 03 includes a first surface 03b protruding from the optical waveguide body 01. The inclined surface of the prism portion 03 is on the same plane as the second surface 01a, thereby making the first surface 03b and the second surface 01a form a predetermined angle. The prism portion 03 and the optical waveguide body 01 can be an integral structure, or they can be two different structures bonded together.

[0091] like Figure 2 and Figure 3 As shown, the coupling grating 021 is disposed in the waveguide coupling region on the first surface 03b of the prism part 03, and the coupling grating 022 is disposed in the waveguide coupling region on the second surface 01a of the optical waveguide body 01. After light rays are incident on the coupling grating 021 in the waveguide coupling region, they are diffracted. The light rays diffracted by the coupling grating 021 are transmitted in the optical waveguide. After the light rays propagating in the optical waveguide are incident on the coupling grating 022 disposed in the waveguide coupling region, they are diffracted by the coupling grating 022 and then emitted.

[0092] The angle between the first surface 03b of the prism section 03 and the second surface 01a of the optical waveguide body 01 is θ1. Thus, when the incident light beam is perpendicular to the first surface 03b and enters the optical transmission structure, the incident angle of the zero-order diffracted beam entering the optical waveguide body 01 is θ1, and the refraction angle is θ2. θ1 and θ2 satisfy:

[0093] n1sinθ1=n2sinθ2, where θ2≥θ c θ c The critical angle for total internal reflection of the optical waveguide body is denoted as n1, which enables the zero-order diffracted beam to propagate through total internal reflection within the optical waveguide body 01. The refractive index of the prism is n1, and the refractive index of the optical waveguide body is n2. To ensure the transmission efficiency of the optical transmission structure, the value of n1 can range from 1.5 to 2.0; the value of n2 can also range from 1.5 to 2.0. n1 and n2 can be equal or unequal.

[0094] In some embodiments, such as Figure 4 As shown, the optical waveguide includes: an optical waveguide body 01; the light-incident surface and the light-exit surface of the optical waveguide body 01 form a preset angle; wherein, the light-incident surface is a first surface 01b, the light-exit surface is a second surface 01a, and the preset angle θ3 is greater than the critical angle for total internal reflection of the optical waveguide body 01.

[0095] like Figure 4As shown, a coupling grating 021 is disposed in the waveguide coupling region on the first surface 01b, and a coupling grating 022 is disposed in the waveguide coupling region on the second surface 01a of the optical waveguide body 01. After light rays are incident on the coupling grating 021 in the waveguide coupling region, they are diffracted. The light rays diffracted by the coupling grating 021 are transmitted in the optical waveguide. After the light rays propagating in the optical waveguide are incident on the coupling grating 022 disposed in the waveguide coupling region, they are diffracted by the coupling grating 022 and then emitted.

[0096] The angle between the first surface 01b and the second surface 01a of the optical waveguide body 01 is θ3, where θ3 ≥ θ c θ c The critical angle for total internal reflection of the optical waveguide body is such that when the incident light beam is perpendicular to the first surface 01b and incident on the optical transmission structure, the zero-order diffracted beam can be propagated by total internal reflection in the optical waveguide body 01.

[0097] In some embodiments, the incident light is image light, so the optical transmission structure can be applied in display devices such as AR helmets. The optical transmission structure can realize the transmission of image light and ensure the brightness of the image entering the human eye.

[0098] In some embodiments, the grating periods of the coupled-in grating 021 and the coupled-out grating 022 may be the same, but this embodiment does not limit this.

[0099] In this embodiment, higher transmission zero-order diffraction efficiency can be obtained by designing parameters such as the height and duty cycle of the grating, thereby further improving the overall optical efficiency of the optical transmission structure.

[0100] In some embodiments, the coupling grating and / or the coupling out grating are rectangular gratings, and the period of the rectangular grating can be 300-600 nm, such as 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, or other values. Different periods result in different diffraction efficiencies for the optical transmission structure; a higher diffraction efficiency can be obtained when the period of the rectangular grating is 300-600 nm.

[0101] The height of the rectangular grating can be 30-500 nm, such as 30 nm, 350 nm, 400 nm, 450 nm, 500 nm, or other values. The diffraction efficiency of the optical transmission structure varies with different heights; a higher diffraction efficiency can be obtained when the height of the rectangular grating is 30-500 nm.

[0102] In some embodiments, such as Figure 3As shown, L is the width of the prism portion in the first direction, which is parallel to the second surface 01a and is the direction from the coupling grating 021 to the coupling grating 022. S is the propagation step size of the zero-order diffracted beam in the optical waveguide body 01, S = 2dtanθ2, and L and S satisfy: L < S, where d is the thickness of the optical waveguide body 01. This avoids the prism portion 03 being too wide in the first direction, which would cause the zero-order diffracted beam to re-enter the prism portion 03 for propagation after entering the optical waveguide body 01, reducing the energy of the zero-order diffracted beam propagating in the optical waveguide body 01, and thus reducing the energy of the light coupled out of the coupling grating 022.

[0103] In this embodiment, the value of d can be 0.1m-5mm, such as 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, and 5mm, or other values. If the value of d is too large, the thickness of the optical transmission structure will be too large, which is not conducive to the thinning of the optical transmission structure; if the value of d is too small, it will affect the light transmission quality of the optical transmission structure. Therefore, the preferred value of d is 0.1m-5mm.

[0104] This disclosure also provides a display device including the optical transmission structure described above.

[0105] The display device includes, but is not limited to, components such as: a radio frequency unit, a network module, an audio output unit, an input unit, a sensor, a display unit, a user input unit, an interface unit, a memory, a processor, and a power supply. Those skilled in the art will understand that the structure of the display device described above does not constitute a limitation on the display device; the display device may include more or fewer of the aforementioned components, or combine certain components, or arrange different components. In the embodiments of this disclosure, the display device includes, but is not limited to, a monitor, a mobile phone, a tablet computer, a television set, a wearable electronic device, a navigation display device, etc.

[0106] Specifically, the display device in this embodiment can be a VR display device or an AR display device, such as AR glasses.

[0107] This disclosure also provides a method for fabricating an optical transmission structure, including:

[0108] Forming an optical waveguide;

[0109] A coupling grating is formed on the first surface of the optical waveguide, the coupling grating being used to couple incident light rays into the optical waveguide;

[0110] A coupling grating is formed on the second surface of the optical waveguide;

[0111] The first surface and the second surface are at a preset angle, such that the zero-order diffracted beam transmitted to the optical waveguide via the coupling grating undergoes total internal reflection within the optical waveguide, and the coupling grating is used to couple the outgoing light out of the optical waveguide.

[0112] In this embodiment, the highest-energy zero-order diffracted beam is used as the information transmission carrier and transmitted by total internal reflection within the optical waveguide, which can improve the overall light energy utilization of the optical transmission structure.

[0113] In some embodiments, the coupling grating and / or the coupling out grating are rectangular gratings. However, the coupling grating and / or the coupling out grating are not limited to rectangular gratings; they can also be other types of gratings, such as blazed gratings, tilted gratings, etc. When the coupling grating and / or the coupling out grating are rectangular gratings, the intrinsic characteristics of rectangular gratings result in the highest energy at the zero-order diffraction order (T0 order) (generally ≥60%), which is much higher than that at the T0 order. ±1 Diffraction order (T) ±1 With the same diffraction efficiency (generally ≤20%), the light efficiency can be increased by more than 3 times.

[0114] In a specific example, such as Figure 2 and Figure 3 As shown, the optical waveguide includes: an optical waveguide body 01; and a prism portion 03 disposed on a second surface 01a of the optical waveguide body 01. The prism portion 03 includes a first surface 03b protruding from the optical waveguide body 01. The inclined surface of the prism portion 03 is on the same plane as the second surface 01a, thereby making the first surface 03b and the second surface 01a form a predetermined angle. The prism portion 03 and the optical waveguide body 01 can be an integral structure, or they can be two different structures bonded together.

[0115] like Figure 2 and Figure 3 As shown, the coupling grating 021 is disposed in the waveguide coupling region on the first surface 03b of the prism part 03, and the coupling grating 022 is disposed in the waveguide coupling region on the second surface 01a of the optical waveguide body 01. After light rays are incident on the coupling grating 021 in the waveguide coupling region, they are diffracted. The light rays diffracted by the coupling grating 021 are transmitted in the optical waveguide. After the light rays propagating in the optical waveguide are incident on the coupling grating 022 disposed in the waveguide coupling region, they are diffracted by the coupling grating 022 and then emitted.

[0116] The angle between the first surface 03b of the prism section 03 and the second surface 01a of the optical waveguide body 01 is θ1. Thus, when the incident light beam is perpendicular to the first surface 03b and enters the optical transmission structure, the incident angle of the zero-order diffracted beam entering the optical waveguide body 01 is θ1, and the refraction angle is θ2. θ1 and θ2 satisfy:

[0117] n1sinθ1=n2sinθ2, where θ2≥θ c θ c The critical angle for total internal reflection of the optical waveguide body is denoted as n1, which enables the zero-order diffracted beam to propagate through total internal reflection within the optical waveguide body 01. The refractive index of the prism is n1, and the refractive index of the optical waveguide body is n2. To ensure the transmission efficiency of the optical transmission structure, the value of n1 can range from 1.5 to 2.0; the value of n2 can also range from 1.5 to 2.0. n1 and n2 can be equal or unequal.

[0118] In some embodiments, such as Figure 4 As shown, the optical waveguide includes: an optical waveguide body 01; the light-incident surface and the light-exit surface of the optical waveguide body 01 form a preset angle; wherein, the light-incident surface is a first surface 01b, the light-exit surface is a second surface 01a, and the preset angle θ3 is greater than the critical angle for total internal reflection of the optical waveguide body 01.

[0119] like Figure 4 As shown, a coupling grating 021 is disposed in the waveguide coupling region on the first surface 01b, and a coupling grating 022 is disposed in the waveguide coupling region on the second surface 01a of the optical waveguide body 01. After light rays are incident on the coupling grating 021 in the waveguide coupling region, they are diffracted. The light rays diffracted by the coupling grating 021 are transmitted in the optical waveguide. After the light rays propagating in the optical waveguide are incident on the coupling grating 022 disposed in the waveguide coupling region, they are diffracted by the coupling grating 022 and then emitted.

[0120] The angle between the first surface 01b and the second surface 01a of the optical waveguide body 01 is θ3, where θ3 ≥ θ c θ c The critical angle for total internal reflection of the optical waveguide body is such that when the incident light beam is perpendicular to the first surface 01b and incident on the optical transmission structure, the zero-order diffracted beam can be propagated by total internal reflection in the optical waveguide body 01.

[0121] In some embodiments, such as Figure 3 As shown, L is the width of the prism portion in the first direction, which is parallel to the second surface 01a and is the direction from the coupling grating 021 to the coupling grating 022. S is the propagation step size of the zero-order diffracted beam in the optical waveguide body 01, S = 2dtanθ2, and L and S satisfy: L < S, where d is the thickness of the optical waveguide body 01. This avoids the prism portion 03 being too wide in the first direction, which would cause the zero-order diffracted beam to re-enter the prism portion 03 for propagation after entering the optical waveguide body 01, reducing the energy of the zero-order diffracted beam propagating in the optical waveguide body 01, and thus reducing the energy of the light coupled out of the coupling grating 022.

[0122] The following is combined Figures 4-15 The optical transmission structure of this disclosure will be further described in detail with specific embodiments.

[0123] In some embodiments, such as Figure 4 As shown, a waveguide substrate of suitable thickness can be provided; the waveguide substrate is cut to form an optical waveguide body 01, with a preset angle between the light-incident surface and the light-exit surface of the optical waveguide body; wherein the light-incident surface is the first surface 01b, the light-exit surface is the second surface 01a, and the preset angle is greater than the critical angle for total internal reflection of the optical waveguide body 01. In some embodiments, when the refractive indices of the optical waveguide body 01 and the prism portion 03 are equal, a waveguide substrate of suitable thickness can be provided; the waveguide substrate is cut to form an optical waveguide body and a prism portion located on the second surface of the optical waveguide body, the prism portion including a portion protruding from the first surface of the optical waveguide body.

[0124] Specifically, such as Figure 5 As shown in Figure a, a waveguide material of suitable thickness is selected as the waveguide substrate 011; as... Figure 5 As shown in b, the waveguide substrate 011 is cut into a first transition structure 012 using diamond cutting or laser cutting methods. The first transition structure 012 is an integral part composed of the optical waveguide body and the prism portion; as shown in... Figure 5 As shown in c, the coupling grating 022 is fabricated on the first transition structure 012 by cutting and grinding; as... Figure 5 As shown in d, the optical transmission structure of this embodiment can be obtained by preparing the coupling grating 021 on the first transition structure 012 through cutting and grinding.

[0125] In some embodiments, when the refractive index of the optical waveguide body is equal to that of the prism portion, an optical transmission structure can also be formed by a bonding process. Forming the optical waveguide includes: forming an optical waveguide body and a prism portion respectively; attaching the prism portion to a second surface of the optical waveguide body, such that the first surface of the prism portion protrudes from the optical waveguide body. Then, the coupling grating is fabricated on a flexible substrate using a nanoimprint method; the flexible substrate carrying the coupling grating is attached to the waveguide coupling region of the first surface. The decoupling grating is fabricated on a flexible substrate using a nanoimprint method; the flexible substrate carrying the decoupling grating is attached to the waveguide decoupling region of the second surface.

[0126] Specifically, such as Figure 6 As shown in Figure a, a metal layer 05 and photoresist 16 are formed on a silicon substrate 04, wherein the metal layer 05 can be made of Mo; as shown in Figure a. Figure 6 As shown in b, the photoresist 16 is exposed and developed to form a pattern of the photoresist 16; as Figure 6As shown in Figure c, the metal layer 05 is etched using the pattern of photoresist 16 as a mask to form a metal transition structure 051.

[0127] After that, as Figure 7 a and Figure 7 As shown in b, a UV photoresist is formed on a silicon substrate 04 with a metal transition structure 051, and after curing the UV photoresist, an imprinting template 06 is formed; as shown in b. Figure 7 As shown in Figure c, the silicon substrate 04 with the metal transition structure 051 is removed to obtain an imprint template 06 with a groove 061, wherein the shape of the groove 061 matches the shape of the metal transition structure 051.

[0128] After that, as Figure 8 As shown in Figure a, an adhesive layer 08, a flexible substrate 09, and a grating material layer 10 are formed on a rigid substrate 07. The rigid substrate 07 can be a quartz substrate or a glass substrate, the flexible substrate 09 can be a polyimide film, and the grating material layer 10 can be an imprinting adhesive. Figure 8 As shown in b, the imprinting template 06 with grooves 061 is pressed onto the grating material layer 10; as Figure 8 As shown in c, after removing the imprinting template 06 with the groove 061 formed thereon, the grating material layer 10 is formed into a rectangular grating 02 that matches the shape of the groove 061; as Figure 8 As shown in d, the rigid substrate 07 and the adhesive layer 08 are removed by laser ablation to obtain a flexible substrate 09 carrying a rectangular grating 02.

[0129] Then, as Figure 9 As shown in Figure a, a waveguide material of suitable thickness is selected as the waveguide substrate 011; as... Figure 9 As shown in b, the waveguide substrate 011 is cut into a first transition structure 012 using diamond cutting or laser cutting methods. The first transition structure 012 is an integral part composed of the optical waveguide body and the prism portion; as shown in... Figure 9 As shown in c, rectangular gratings 02 with different grating parameters are attached to the waveguide coupling-in region and the waveguide coupling-out region by a bonding process to obtain the optical transmission structure of this embodiment.

[0130] In some embodiments, when the refractive index of the optical waveguide body is not equal to the refractive index of the prism, an optical transmission structure can be formed by bonding process.

[0131] Specifically, such as Figure 6 As shown in Figure a, a metal layer 05 and photoresist 16 are formed on a silicon substrate 04, wherein the metal layer 05 can be made of Mo; as shown in Figure a. Figure 6 As shown in b, the photoresist 16 is exposed and developed to form a pattern of the photoresist 16; as Figure 6As shown in Figure c, the metal layer 05 is etched using the pattern of photoresist 16 as a mask to form a metal transition structure 051.

[0132] After that, as Figure 7 a and Figure 7 As shown in b, a UV photoresist is formed on a silicon substrate 04 with a metal transition structure 051, and after curing the UV photoresist, an imprinting template 06 is formed; as shown in b. Figure 7 As shown in Figure c, the silicon substrate 04 with the metal transition structure 051 is removed to obtain an imprint template 06 with a groove 061, wherein the shape of the groove 061 matches the shape of the metal transition structure 051.

[0133] After that, as Figure 10 As shown in Figure a, a grating material layer 10 is formed on a rigid substrate 07, wherein the rigid substrate 07 can be a quartz substrate or a glass substrate, and the grating material layer 10 can be made of imprinting adhesive; as shown in Figure a. Figure 10 As shown in b, the imprinting template 06 with grooves 061 is pressed onto the grating material layer 10; as Figure 10 As shown in c, after removing the imprinting template 06 with the groove 061 formed thereon, the grating material layer 10 is formed into a coupling grating 021 that matches the shape of the groove 061; as Figure 10 As shown in d, a rigid substrate 07 on which a coupling grating 021 is formed is laser-cut to obtain a prism portion 03 and a coupling grating 021.

[0134] After that, as Figure 11 As shown in Figure a, a metal layer 05 and photoresist 16 are formed on a silicon substrate 04, wherein the metal layer 05 can be made of Mo; as shown in Figure a. Figure 11 As shown in b, the photoresist 16 is exposed and developed to form a pattern of the photoresist 16; as Figure 11 As shown in Figure c, the metal layer 05 is etched using the pattern of photoresist 16 as a mask to form a metal transition structure 051.

[0135] After that, as Figure 12 a and Figure 12 As shown in b, a UV photoresist is formed on a silicon substrate 04 with a metal transition structure 051, and after curing the UV photoresist, an imprinting template 06 is formed; as shown in b. Figure 12 As shown in Figure c, the silicon substrate 04 with the metal transition structure 051 is removed to obtain an imprint template 06 with a groove 061, wherein the shape of the groove 061 matches the shape of the metal transition structure 051.

[0136] After that, as Figure 13 As shown in Figure a, an optical waveguide body 01 and a grating material layer 10 are formed; as... Figure 13 As shown in b, the imprinting template 06 with grooves 061 is pressed onto the grating material layer 10; as Figure 13As shown in c, after removing the imprint template 06 with the groove 061 formed thereon, the grating material layer 10 is formed into a coupling grating 022 that matches the shape of the groove 061.

[0137] After that, as Figure 14 As shown, the optical transmission structure of this embodiment can be obtained by bonding the prism part 03 with the coupling grating 021 to the optical waveguide body 01 with the coupling grating 022 with adhesive.

[0138] In some embodiments, when the refractive index of the optical waveguide body is not equal to the refractive index of the prism, an optical transmission structure can be formed by a cutting process.

[0139] Specifically, such as Figure 6 As shown in Figure a, a metal layer 05 and photoresist 16 are formed on a silicon substrate 04, wherein the metal layer 05 can be made of Mo; as shown in Figure a. Figure 6 As shown in b, the photoresist 16 is exposed and developed to form a pattern of the photoresist 16; as Figure 6 As shown in Figure c, the metal layer 05 is etched using the pattern of photoresist 16 as a mask to form a metal transition structure 051.

[0140] After that, as Figure 7 a and Figure 7 As shown in b, a UV photoresist is formed on a silicon substrate 04 with a metal transition structure 051, and after curing the UV photoresist, an imprinting template 06 is formed; as shown in b. Figure 7 As shown in Figure c, the silicon substrate 04 with the metal transition structure 051 is removed to obtain an imprint template 06 with a groove 061, wherein the shape of the groove 061 matches the shape of the metal transition structure 051.

[0141] After that, as Figure 8 As shown in Figure a, an adhesive layer 08, a flexible substrate 09, and a grating material layer 10 are formed on a rigid substrate 07. The rigid substrate 07 can be a quartz substrate or a glass substrate, the flexible substrate 09 can be a polyimide film, and the grating material layer 10 can be an imprinting adhesive. Figure 8 As shown in b, the imprinting template 06 with grooves 061 is pressed onto the grating material layer 10; as Figure 8 As shown in c, after removing the imprinting template 06 with the groove 061 formed thereon, the grating material layer 10 is formed into a rectangular grating 02 that matches the shape of the groove 061; as Figure 8 As shown in d, the rigid substrate 07 and the adhesive layer 08 are removed by laser ablation to obtain a flexible substrate 09 carrying a rectangular grating 02.

[0142] like Figure 15As shown in Figure a, a rigid substrate 07 is provided. The rigid substrate 07 can be a quartz substrate or a glass substrate. Multiple prism portions 03 are obtained by cutting the rigid substrate 07. Figure 15 As shown in Figure b, the prism part 03 is bonded to the optical waveguide body 01 using adhesive; as... Figure 15 As shown in Figure c, rectangular gratings 02 with different grating parameters are attached to the waveguide coupling region of the prism part 03 and the waveguide coupling region of the optical waveguide body 01 through a bonding process to obtain the following... Figure 15 The optical transmission structure of this embodiment is shown in d.

[0143] This embodiment utilizes the transmission zero-order diffraction beam, which has the highest diffraction efficiency of a rectangular grating, as the information transmission carrier, instead of the conventional transmission first-order diffraction beam, thereby significantly improving the overall optical efficiency of the optical transmission structure.

[0144] In the various method embodiments of this disclosure, the sequence numbers of each step are not intended to limit the order of the steps. For those skilled in the art, any changes in the order of the steps are within the scope of protection of this disclosure without any creative effort.

[0145] It should be noted that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, since the embodiments are basically similar to the product embodiments, the descriptions are relatively simple, and the relevant parts can be referred to the descriptions of the product embodiments.

[0146] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as “comprising” or “including” mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as “connected” or “linked” are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as “upper,” “lower,” “left,” and “right” are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described objects changes.

[0147] It is understandable that when a component such as a layer, film, region, or substrate is referred to as being "above" or "below" another component, the component may be "directly" located "above" or "below" the other component, or there may be intermediate components present.

[0148] In the description of the above embodiments, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0149] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. An optical transmission structure, characterized by, The optical transmission structure comprises: an optical waveguide; an in-coupling grating on a first surface of the optical waveguide and an out-coupling grating on a second surface of the optical waveguide, the in-coupling grating being configured to in-couple an incident light into the optical waveguide, the in-coupling grating and the out-coupling grating being rectangular gratings; wherein the first surface and the second surface are at a preset angle, such that a zero-order diffraction beam transmitted into the optical waveguide via the in-coupling grating is totally reflected in the optical waveguide, and the out-coupling grating is configured to out-couple an emergent light from the optical waveguide. The optical waveguide comprises: an optical waveguide body; a prism portion provided on a second surface of the optical waveguide body, the prism portion comprising a first surface protruding from the optical waveguide body; a refractive index of the prism portion is n1, a refractive index of the optical waveguide body is n2, an incident angle of the zero-order diffraction beam incident on the optical waveguide body is θ1, and a refraction angle is θ2, θ1 and θ2 satisfy: n1sinθ1=n2sinθ2, where θ2≥θ c , θ c is the critical angle of total reflection for the optical waveguide body; L is a width of the prism portion in a first direction, the first direction being parallel to the second surface and being a direction from the in-coupling grating to the out-coupling grating, S is a transmission step length of the zero-order diffraction beam in the optical waveguide body, S = 2d tan θ2, L and S satisfy: L < S, wherein d is a thickness of the optical waveguide body.

2. The optical transmission structure according to claim 1, characterized in that, The incident light is incident on the optical transmission structure perpendicularly to the first surface.

3. The optical transmission structure of claim 1, wherein, The incident light is image light.

4. The optical transmission structure of claim 1, wherein, The grating periods of the in-coupling grating and the out-coupling grating are the same.

5. The optical transmission structure of claim 1, wherein, The period of the rectangular grating is 300-600 nm.

6. The optical transmission structure of claim 5, wherein, The height of the rectangular grating is 30-500 nm.

7. The optical transmission structure of claim 1, wherein, n1 is in a range of 1.5-2.0; n2 is in a range of 1.5-2.

0.

8. The optical transmission structure of claim 1, wherein, n1 is equal to n2.

9. A display device, characterized by comprising: The optical transmission structure comprises any one of claims 1-8.

10. A method of manufacturing an optical transmission structure, applied to the optical transmission structure according to any one of claims 1 to 8, characterized in that, The optical transmission structure comprises: forming an optical waveguide; forming an in-coupling grating on a first surface of the optical waveguide, the in-coupling grating being configured to in-couple an incident light into the optical waveguide, the in-coupling grating and the out-coupling grating being rectangular gratings; forming an out-coupling grating on a second surface of the optical waveguide; wherein the first surface and the second surface are at a preset angle, such that a zero-order diffraction beam transmitted into the optical waveguide via the in-coupling grating is totally reflected in the optical waveguide, and the out-coupling grating is configured to out-couple an emergent light from the optical waveguide.

11. The method of fabricating an optical transmission structure according to claim 10, wherein, The forming of the optical waveguide comprises: forming an optical waveguide body and a prism portion respectively; attaching the prism portion on a second surface of the optical waveguide body, such that the first surface of the prism portion protrudes from the optical waveguide body.

12. The method of claim 10, wherein The forming of the optical waveguide comprises: providing a waveguide substrate; cutting the waveguide substrate to form an optical waveguide body and a prism portion on a second surface of the optical waveguide body, the prism portion comprising a first surface protruding from the optical waveguide body.

13. The method of claim 10, wherein: The forming of the in-coupling grating on the first surface of the optical waveguide comprises: fabricating the in-coupling grating on a flexible substrate by a nano-imprinting method; attaching the flexible substrate carrying the in-coupling grating on a waveguide in-coupling area of the first surface.

14. The method of claim 10, wherein forming an out-coupling grating on a second surface of the optical waveguide comprises: fabricating the out-coupling grating on a flexible substrate by a nano-imprinting method; attaching the flexible substrate carrying the out-coupling grating on a waveguide out-coupling region of the second surface.

15. The method of claim 10, wherein: forming the optical waveguide comprises: providing a waveguide substrate; cutting the waveguide substrate to form an optical waveguide body, an incident surface of the optical waveguide body and an exit surface of the optical waveguide body form a preset angle; wherein the incident surface is the first surface, the exit surface is the second surface, and the preset angle is greater than a total reflection critical angle of the optical waveguide body.

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