Optical waveguide packaging structure and packaging method

Abstract

The invention discloses an optical waveguide packaging structure and packaging method, and the structure comprises a waveguide substrate, a protection sheet, a grating structure, and an adhesive layer. The protection sheet and the waveguide substrate are oppositely arranged in a spaced mode, the protection sheet and the waveguide substrate are connected through an adhesive layer, and at least part of the edge of the protection sheet transversely expands outwards and exceeds the edge of the waveguide substrate; or at least part of the edge of the protection sheet is transversely shrunk inwards and shrunk into the edge of the waveguide substrate; or the edge of the protection sheet and the edge of the waveguide substrate are arranged in a staggered manner; the grating structure is arranged on the waveguide substrate, and the grating structure is located in the front projection plane of the protection sheet on the waveguide substrate. According to the optical waveguide packaging structure provided by the invention, the requirement on high adhesion performance of glue can be reduced, and meanwhile, the optical waveguide packaging structure has good anti-falling performance.

Description

Technical Field

[0001] The present invention relates to the field of optical waveguide technology, and in particular to an optical waveguide packaging structure and a packaging method. Background Art

[0002] The existing optical waveguide packaging solution generally involves coating a photoresist on a substrate and then imprinting a grating structure, and at the same time, bonding a protective sheet of the same size as the substrate to the substrate through adhesive. Although such a structure meets the processing requirements of the waveguide, after being assembled into a lens, when the lens falls, the impact force on the lens will be transmitted to the waveguide structure through the glue layer between the lens and the waveguide structure. There is usually a certain difference in the physical properties of the protective sheet and the waveguide substrate. Under the action of the impact force, the protective sheet and the waveguide substrate undergo different degrees of deformation, generating shear stress at the interface. When the shear force exceeds the adhesion strength between the protective sheet and the waveguide substrate, it will cause cracks at the interface of the waveguide structure, affecting the appearance and optical display effect of the product. Summary of the invention

[0003] In view of this, the present invention proposes an optical waveguide packaging structure and a packaging method, aiming to improve the anti-drop performance of the optical waveguide packaging structure and reduce the demand for higher glue adhesion performance.

[0004] The optical waveguide packaging structure proposed in the first aspect of the present invention includes: a waveguide substrate; a protective sheet, wherein the protective sheet and the waveguide substrate are arranged relative to each other and are connected to the waveguide substrate by an adhesive layer, and at least part of the edge of the protective sheet is laterally expanded and exceeds the edge of the waveguide substrate; or, at least part of the edge of the protective sheet is laterally retracted and retracted into the edge of the waveguide substrate; or, the edge of the protective sheet and the edge of the waveguide substrate are staggered with each other; and a grating structure, wherein the grating structure is arranged on the waveguide substrate and the grating structure is located within the orthographic projection plane of the protective sheet on the waveguide substrate.

[0005] It can be seen from the above technical scheme that in the optical waveguide packaging structure proposed in the first aspect of the present invention, the part of the protective sheet located within the surface of the waveguide substrate in the orthographic projection of the waveguide substrate belongs to the corresponding overlapping area of ​​the two. Then the protective sheet, waveguide substrate and adhesive layer encapsulate the grating structure in the corresponding overlapping area of ​​the waveguide substrate and the protective sheet, so that the grating structure is protected from damage by the external environment; when falling or being squeezed by external force, one of the components in the non-overlapping area between the protective sheet and the waveguide substrate is deformed, while the deformation amount in the overlapping area without force is relatively small. Since the anti-drop performance of the present application is good, there is no need to rely on glue with high adhesion requirements to bond the waveguide substrate and the protective sheet, thereby reducing the demand for high glue adhesion performance in the optical waveguide packaging structure.

[0006] In some embodiments, the protection sheet is arranged parallel to and spaced apart from the waveguide substrate, and the orthographic projection of at least part of the edge of the protection sheet on the surface where the waveguide substrate is located is located outside the contour of the waveguide substrate, so that at least part of the edge of the protection sheet expands laterally relative to the edge of the waveguide substrate.

[0007] In some embodiments, the protective sheet is arranged parallel to and spaced apart from the waveguide substrate, and the orthographic projection of at least part of the edge of the waveguide substrate on the surface where the protective sheet is located is located outside the contour of the protective sheet, so that at least part of the edge of the protective sheet is laterally retracted relative to the edge of the waveguide substrate.

[0008] In some embodiments, the protection sheet is arranged parallel to the waveguide substrate and spaced apart, a portion of the edge of the waveguide substrate has an orthographic projection on the surface where the protection sheet is located outside the outline of the protection sheet, and a portion of the edge of the protection sheet has an orthographic projection on the surface where the waveguide substrate is located outside the outline of the waveguide substrate, so that the edge of the protection sheet is staggered with the edge of the waveguide substrate.

[0009] In some embodiments, the area of ​​the region where the waveguide substrate and the protection sheet are offset accounts for 0.2% to 1% of the area of ​​the region where the waveguide substrate and the protection sheet are aligned and overlapped.

[0010] In some embodiments, the adhesive layer is coated on the area where the waveguide substrate and the protective sheet are overlapped, and the adhesive layer is arranged around the grating structure; and / or, the adhesive layer is coated on the area where the waveguide substrate and the protective sheet are overlapped, and the adhesive layer covers all the grating structures.

[0011] In some specific examples, the thickness of the adhesive layer is 1 to 3.5 times the thickness of the grating structure; and / or the bonding area between the adhesive layer and the waveguide substrate accounts for greater than or equal to 30% of the area of ​​the overlapping region between the waveguide substrate and the protective sheet.

[0012] In some embodiments, the material of the protective sheet is one or more of polycarbonate, acrylic, cycloolefin copolymer plastic or cycloolefin polymer; and / or, the material of the waveguide substrate is one or more of polycarbonate, acrylic, cycloolefin copolymer plastic or cycloolefin polymer.

[0013] The packaging method of the optical waveguide packaging structure proposed in the second aspect of the present invention includes the following steps: providing a waveguide substrate and a protective sheet; making a grating structure on one side of the waveguide substrate; coating a curable glue on the side of the waveguide substrate having the grating structure, and the curable glue is coated at least around the grating structure; attaching the protective sheet to the curable glue facing the waveguide substrate, and making at least part of the edge of the protective sheet laterally shrink inward, laterally expand outward, or staggered relative to the edge of the waveguide substrate; curing the curable glue to form a glue layer to obtain the optical waveguide packaging structure.

[0014] It can be seen from the above technical solutions that the packaging method of the optical waveguide packaging structure proposed in the second aspect of the present invention can reliably package the grating structure, and the manufactured optical waveguide packaging structure has good reliability, good overall anti-drop performance, and low demand for high glue adhesion performance.

[0015] In some embodiments, the curable adhesive is cured by at least one of heat curing, pressure curing, or UV curing.

[0016] In some embodiments, for sensitive areas at the edge of the waveguide substrate and / or the protection sheet, the edge of the waveguide substrate and the edge of the protection sheet are non-overlappingly arranged during alignment, so that at least the edges corresponding to the sensitive areas are non-overlappingly arranged.

[0017] It should be understood that the above general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure of the embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained like these accompanying drawings without paying any creative work.

[0019] Figure 1 is a schematic structural diagram of an optical waveguide packaging structure in which the entire edge of the protection sheet exceeds the edge of the waveguide substrate in some embodiments of the present invention;

[0020] Figure 2 is a schematic structural diagram of an optical waveguide packaging structure proposed in some embodiments of the present invention in which the entire edge of the waveguide substrate exceeds the edge of the protection sheet;

[0021] Figure 3 is a schematic diagram of a structure in which a portion of the edge of a protection sheet in an optical waveguide packaging structure proposed by some embodiments of the present invention exceeds an edge of a waveguide substrate and a portion of the edge of a waveguide substrate exceeds an edge of a protection sheet;

[0022] Figure 4 It is a schematic diagram of a structure in which a portion of the edge of a waveguide substrate in an optical waveguide packaging structure proposed in some embodiments of the present invention exceeds the edge of a protective sheet, and the area where the waveguide substrate and the protective sheet are staggered is a sensitive area;

[0023] Figure 5 A schematic flow chart of a packaging method for an optical waveguide packaging structure according to some embodiments of the present invention.

[0024] Description of reference numerals:

[0025] 100. Optical waveguide packaging structure;

[0026] 10. waveguide substrate; 11. first edge;

[0027] 20. Adhesive layer;

[0028] 30. Grating structure;

[0029] 40. protective sheet; 41. second edge;

[0030] 200. Lenses. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, other embodiments obtained by ordinary technicians in this field without creative work are all within the scope of protection of the present invention.

[0032] It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in this application specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0033] It should be further understood that the term "and / or" used in the present specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0034] The waveguide substrate and the protective sheet of the existing optical waveguide packaging structure completely overlap, and a frame-mounted packaging structure or a fully fitted packaging structure is used in the overlapping area to protect the grating structure. The waveguide substrate and the protective sheet are both optical resin materials, but there are differences in the material formula and physical properties of the materials (such as hardness, elastic modulus, etc.). When subjected to external impact or collision, the deformation degree of the two materials is inconsistent, and shear stress is generated at the interface. When the shear stress exceeds the adhesion strength between them, it will cause the interface to crack. For example, when one of the protective sheet or the waveguide substrate is relatively hard and the other is relatively soft, when a collision occurs, the harder layer structure exerts a greater pressure on the softer layer structure, so that a greater stress is concentrated at the interface where the waveguide substrate and the protective sheet are bonded. If the stress is greater than the adhesion force, it is easy to cause cracking.

[0035] In view of this, an embodiment of the present invention provides an optical waveguide packaging structure 100, such as Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, it includes: a waveguide substrate 10, a protection sheet 40, a glue layer 20 and a grating structure 30.

[0036] The protective sheet 40 and the waveguide substrate 10 are arranged at a relative interval, and the protective sheet 40 and the waveguide substrate 10 are connected by the adhesive layer 20. At least part of the edge of the protective sheet 40 is laterally expanded and exceeds the edge of the waveguide substrate 10; or at least part of the edge of the protective sheet 40 is laterally contracted and contracted into the edge of the waveguide substrate 10, or the edge of the protective sheet 40 and the edge of the waveguide substrate 10 are arranged offset from each other. In other words, part of the edge of the protective sheet 40 can be offset from part of the edge of the waveguide substrate 10; the entire edge of the protective sheet 40 can be offset from the entire edge of the waveguide substrate 10; part of the edge of the waveguide substrate 10 can be offset from part of the edge of the protective sheet 40; the entire edge of the waveguide substrate 10 can be offset from the entire edge of the protective sheet 40. Regardless of the arrangement structure, the waveguide substrate 10 and the protective sheet 40 have overlapping areas that are aligned with each other and non-overlapping areas that are not aligned.

[0037] Further, the grating structure 30 is disposed on the waveguide substrate 10, and the grating structure 30 is located in the orthographic projection plane of the protection sheet 40 on the waveguide substrate 10. The grating structure 30 can be any grating structure 30, which is not limited here.

[0038] As can be seen from the above technical solution, in the optical waveguide packaging structure 100 proposed by the present invention, the portion of the protective sheet 40 located within the surface of the waveguide substrate 10 in the orthographic projection of the waveguide substrate 10 belongs to the corresponding overlapping area of ​​the two. Then, the protective sheet 40, the waveguide substrate 10 and the adhesive layer 20 encapsulate the grating structure 30 in the corresponding overlapping area of ​​the waveguide substrate 10 and the protective sheet 40, so that the grating structure 30 is protected from damage by the external environment; when it falls or is squeezed by external force, since there is a non-overlapping area between the protective sheet 40 and the waveguide substrate 10 , deformation will only occur in the lateral non-overlapping area of ​​one of the components, and the force generated by the deformation will not act on the other component in the non-overlapping area, while the deformation amount is relatively small in the overlapping area of ​​the adhesive. Therefore, compared with the completely overlapping structure, the contact area between the partially overlapping waveguide substrate 10 and the protective sheet 40 of the present invention is smaller, and the shear stress formed in the overlapping area is smaller. Then, the shear stress is less than the adhesion strength between the waveguide substrate 10 and the protective sheet 40, so that the adhesive area between the waveguide substrate 10 and the protective sheet 40 is not easy to crack.

[0039] Since the present application has good anti-drop performance, there is no need to rely on too much glue to bond the waveguide substrate 10 and the protection sheet 40, thereby reducing the demand for high adhesion performance of the glue in the optical waveguide packaging structure 100.

[0040] In summary, the optical waveguide packaging structure 100 proposed in the present invention can effectively protect the grating structure 30 by making appropriate improvements and clever designs on the optical waveguide packaging structure 100, and the entire optical waveguide packaging structure 100 does not need to rely on glue with high adhesion performance to improve the adhesion requirements between the waveguide substrate 10 and the protective sheet 40 when packaging the grating structure 30, and meets the packaging requirements for the grating structure 30. During the drop test, the performance was good.

[0041] It can be understood that, compared with the disadvantage of poor drop resistance of the optical waveguide packaging structure in the prior art, the optical waveguide packaging structure 100 of the present invention can achieve excellent drop resistance without the need for special glue with high adhesion performance.

[0042] For the convenience of description, the edge of the waveguide substrate 10 is hereinafter referred to as a first edge 11 , and the edge of the protection sheet 40 is hereinafter referred to as a second edge 41 .

[0043] In some embodiments, Figure 1As shown, the protection sheet 40 is arranged parallel to the waveguide substrate 10 and spaced apart, and the orthographic projection of at least part of the edge of the protection sheet 40 on the surface where the waveguide substrate 10 is located is located outside the contour of the waveguide substrate 10, so that at least part of the edge of the protection sheet 40 is laterally expanded relative to the edge of the waveguide substrate 10. In these examples, the second edge 41 of the protection sheet 40 is fully or partially extended outward, and is expanded relative to the waveguide substrate 10, so that at least part of the second edge 41 is expanded relative to the first edge 11 without being aligned; in these examples, when the entire second edge 41 of the protection sheet 40 is laterally expanded relative to the waveguide substrate 10, the entire first edge 11 of the waveguide substrate 10 is laterally retracted relative to the protection sheet 40, and at this time, the protection sheet 40 completely covers the entire waveguide substrate 10. Then, when the optical waveguide packaging structure 100 falls and touches the ground, the second edge 41 is preferentially stressed to achieve a larger deformation and stress absorption, while the relatively retracted first edge 11 and other parts of the grating structure 30 and the protective sheet 40 are almost unaffected by external forces and have a smaller deformation amount. Even if the stress at the edge is transmitted to the overlapping area, the stress is less than the bonding strength, and the glue layer 20 in the overlapping area does not crack, so that the projected part of the protective sheet 40 located within the contour of the waveguide substrate 10 always maintains a stably and reliably connected connection, thereby improving the overall anti-drop performance.

[0044] In a specific example, Figure 1 As shown, the bonding surface of the adhesive layer 20 and the waveguide substrate 10 accounts for 30% to 40% of the side of the waveguide substrate 10 facing the protective sheet 40, which can achieve a firm bond between the waveguide substrate 10 and the protective sheet 40, and reduce the adhesive performance requirements of the glue, thereby realizing a frame-mounted packaging structure. For example, the bonding surface of the adhesive layer 20 and the waveguide substrate 10 accounts for 30%, 35% or 40% of the side of the waveguide substrate 10 facing the protective sheet 40. Of course, in other examples, the adhesive layer 20 can be completely coated in the overlapping area between the waveguide substrate 10 and the protective sheet 40, that is, the adhesive layer 20 completely covers the area of ​​the waveguide substrate 10 within the positive projection of the protective sheet 40, thereby realizing a fully fitted packaging structure.

[0045] In some other embodiments, Figure 2As shown, the protective sheet 40 is arranged parallel to the waveguide substrate 10 and spaced apart, and the orthographic projection of at least part of the edge of the waveguide substrate 10 on the surface where the protective sheet 40 is located is located outside the outline of the protective sheet 40, so that at least part of the edge of the protective sheet 40 is laterally retracted relative to the edge of the waveguide substrate 10. Then, in these examples, all or part of the first edge 11 of the waveguide substrate 10 extends outward and expands relative to the protective sheet 40, so that at least part of the first edge 11 expands relative to the second edge 41 without alignment; that is, at least part of the second edge 41 of the protective sheet 40 is laterally retracted relative to the waveguide substrate 10. In these examples, when the entire second edge 41 of the protective sheet 40 is laterally retracted relative to the waveguide substrate 10, the entire first edge 11 of the waveguide substrate 10 is laterally expanded relative to the protective sheet 40, and at this time, the waveguide substrate 10 completely covers the entire protective sheet 40. Then, when the optical waveguide packaging structure 100 falls and touches the ground, the first edge 11 is preferentially stressed to achieve a larger deformation and stress absorption, while the relatively retracted second edge 41 and other parts of the grating structure 30 and the protective sheet 40 are almost unaffected by external forces and have a smaller deformation amount. Even if the stress at the edge is transmitted to the overlapping area, the stress is less than the bonding strength, and the glue layer 20 in the overlapping area does not crack, so that the projected part of the waveguide substrate 10 located within the outline of the protective sheet 40 always maintains a stable and reliable connection, thereby improving the overall anti-drop performance.

[0046] In a specific example, Figure 2 As shown, the bonding surface of the adhesive layer 20 and the protective sheet 40 accounts for 30% to 40% of the side of the protective sheet 40 facing the waveguide substrate 10, which can achieve a firm bond between the waveguide substrate 10 and the protective sheet 40, and can also reduce the adhesiveness requirements of the glue, thereby realizing a frame-mounted packaging structure. For example, the bonding surface of the adhesive layer 20 and the protective sheet 40 accounts for 30%, 32%, 35%, 37% or 40% of the side of the protective sheet 40 facing the waveguide substrate 10. Of course, in other examples, the adhesive layer 20 can be completely coated in the overlapping area between the waveguide substrate 10 and the protective sheet 40, that is, the adhesive layer 20 completely covers the area of ​​the protective sheet 40 within the positive projection of the waveguide substrate 10, thereby realizing a fully fitted packaging structure.

[0047] In some other embodiments, such as Figure 3As shown, the protective sheet 40 is arranged parallel to the waveguide substrate 10 and spaced apart, the orthographic projection of a portion of the first edge 11 of the waveguide substrate 10 on the surface where the protective sheet 40 is located is located outside the outline of the protective sheet 40, and the orthographic projection of a portion of the second edge 41 of the protective sheet 40 on the surface where the waveguide substrate 10 is located is located outside the outline of the waveguide substrate 10, so that the edge of the protective sheet 40 is misaligned with the edge of the waveguide substrate 10. In these examples, the first edge 11 of the waveguide substrate 10 partially extends outward and expands relative to the protective sheet 40, so that the portion of the first edge 11 and the second edge 41 are misaligned and not aligned. The second edge 41 of the protective sheet 40 partially extends outward and expands relative to the waveguide substrate 10, so that the portion of the second edge 41 and the first edge 11 are misaligned and not aligned. Then, when the optical waveguide packaging structure 100 falls and touches the ground, the outward-expanded first edge 11 or the outward-expanded second edge 41 is subjected to stress first, achieving a larger deformation and absorbing stress, while the protective sheet 40, the waveguide substrate 10 and the grating structure 30 in the overlapping area are almost unaffected by the stress and have a smaller deformation. Even if the stress at the edge is transmitted to the overlapping area, the stress is less than the bonding strength, and the glue layer 20 in the overlapping area does not crack, maintaining a stable connection, thereby improving the overall anti-drop performance.

[0048] In some examples, a local misalignment is performed on the edge position of the waveguide substrate 10 or the protective sheet 40 corresponding to the sensitive area (the area with the grating structure 30 printed thereon). For example, for the sharp corner of the waveguide substrate 10, the area corresponding to the sharp corner is encapsulated with the coupled grating structure. In the present application, the part of the second edge 41 of the protective sheet 40 corresponding to the sharp corner can be expanded outward so that the orthographic projection of this part of the second edge 41 on the waveguide substrate 10 is located outside the contour of the waveguide substrate 10, that is, the orthographic projection of the sharp corner on the protective sheet 40 is located within the contour of the protective sheet 40, thereby realizing the anti-drop protection of the sharp corner and improving the anti-drop performance of this part.

[0049] Similarly, if Figure 4 As shown, for the edge position of another sensitive area (the area with the grating structure 30 printed thereon) corresponding to the protective sheet 40, the area corresponding to the sensitive area is encapsulated with a coupling-out grating structure, and the edge position of the first edge 11 of the waveguide substrate 10 corresponding to the sensitive area can be expanded outward so that the orthographic projection of this part of the first edge 11 on the protective sheet 40 is located outside the outline of the protective sheet 40, that is, the orthographic projection of the sensitive area on the waveguide substrate 10 is located within the outline of the waveguide substrate 10, thereby achieving anti-drop protection for the sensitive area and improving the anti-drop performance of this part.

[0050] In a specific example, the optical waveguide packaging structure 100 is sandwiched between two lenses 200, and the grating structure 30 includes a coupling-in grating and a coupling-out grating, wherein one grating structure 30 (such as the coupling-out grating) is located in an area closer to the middle of the overlapping portion of the protection sheet 40 and the waveguide substrate 10, and the other grating structure 30 (such as the coupling-in grating) is located in an area closer to the edge of the overlapping portion of the protection sheet 40 and the waveguide substrate 10. At this time, the portion of the optical waveguide packaging structure 100 at the coupling-in grating belongs to the sensitive area, and it is necessary to expand the edge of the waveguide substrate 10 at the sensitive area relative to the edge of the protective sheet 40, or to expand the edge of the protective sheet 40 at the sensitive area relative to the edge of the waveguide substrate 10, so as to achieve anti-drop protection for the coupling-in grating at the sensitive area.

[0051] In some embodiments, Figures 1 to 4 As shown, the area of ​​the region where the waveguide substrate 10 and the protective sheet 40 are offset accounts for 0.2% to 1% of the area of ​​the region where the waveguide substrate 10 and the protective sheet 40 are aligned and overlapped. It can be understood that when the area of ​​the region where the waveguide substrate 10 and the protective sheet 40 are offset accounts for 0.2% to 1% of the area of ​​the region where the two are aligned and overlapped, it can save materials while ensuring that the optical waveguide packaging structure 100 has excellent anti-drop performance. In other words, when the area ratio is less than 0.2%, the area of ​​the region where the waveguide substrate 10 and the protective sheet 40 are offset is too small, and there is still a high risk of cracking during the drop test; and when the area ratio is greater than 1%, the area of ​​the region where the waveguide substrate 10 and the protective sheet 40 are offset is too large, and the space required for arrangement is large, and more materials are consumed. For example, in the present invention, the area of ​​the region where the waveguide substrate 10 and the protective sheet 40 are offset accounts for 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1% of the area of ​​the region where the waveguide substrate 10 and the protective sheet 40 are aligned and overlapped, and can be adjusted as needed. The above-mentioned area ratio of the offset setting is particularly suitable for the case where both the waveguide substrate 10 and the protective sheet 40 are made of resin materials.

[0052] In some embodiments, Figure 1 and Figure 2As shown, the adhesive layer 20 is coated on the area where the waveguide substrate 10 and the protective sheet 40 are arranged in the center and overlap, and the adhesive layer 20 is arranged around the grating structure 30. In these examples, the adhesive layer 20 is only arranged on the area where the waveguide substrate 10 and the protective sheet 40 are arranged in the center and overlap, so as to prevent the adhesive layer 20 from being exposed; and the adhesive layer 20, the waveguide substrate 10 and the protective sheet 40 encapsulate the grating structure 30 in the area enclosed by the three, forming a frame-paste package, which reduces the amount of adhesive required to be used when the waveguide substrate 10 and the adhesive layer 20 of the present invention are connected. The optical waveguide packaging structure 100 of the present invention adopts the frame-paste package, and there is no need to use glue with higher adhesion performance, thereby reducing the adhesion requirements between the waveguide substrate 10 and the protective sheet 40.

[0053] In other examples, such as Figure 3 As shown, the adhesive layer 20 is coated on the area where the waveguide substrate 10 and the protective sheet 40 are aligned and overlapped, and the adhesive layer 20 covers all the grating structures 30. Thus, the waveguide substrate 10 and the protective sheet 40 can form an extremely strong connection, and the grating structure 30 is completely covered by the adhesive layer 20, which further improves the protection of the grating structure 30, so that the grating structure 30 is stably fixed on the waveguide substrate 10.

[0054] Of course, the present invention can adjust the amount of the adhesive layer 20 as needed to achieve the desired effect.

[0055] In some specific examples, the thickness of the adhesive layer 20 is 1 to 3.5 times the thickness of the grating structure 30. For example, the thickness of the adhesive layer 20 is 1, 1.5, 2, 2.5, 3 or 3.5 times the thickness of the grating structure 30, so that the adhesive layer 20 can, while bonding the waveguide substrate 10 and the protective sheet 40, buffer the influence of stress caused by external impact force to a certain extent, thereby effectively preventing the protective sheet 40 from squeezing the grating structure 30, so that the grating structure 30 is arranged in a certain space, can work stably, is not easy to deform, has an appropriate overall structure thickness, is easy to arrange, and has a small optical path deviation when light passes through the adhesive layer 20, thereby ensuring accurate transmission of optical signals inside the optical waveguide packaging structure 100 and ensuring imaging quality. That is to say, if the thickness of the adhesive layer 20 is too small, smaller than the thickness of the grating structure 30, the grating structure 30 will be squeezed when the waveguide substrate 10 and the protective sheet 40 are bonded; if the thickness of the adhesive layer 20 is too large, greater than 3.5 times the thickness of the grating structure 30, the amount of adhesive required is too much, the entire optical waveguide packaging structure 100 is too thick, the weight of the overall structure increases, and light will be refracted, reflected, etc. when passing through the adhesive layer 20, resulting in a larger optical path deviation inside the optical waveguide packaging structure 100, which will reduce the optical efficiency of the diffraction optical waveguide, causing the loss of optical signals or the degradation of imaging quality.

[0056] In some specific examples, the bonding area between the adhesive layer 20 and the waveguide substrate 10 accounts for more than or equal to 30% of the area of ​​the overlapping area between the waveguide substrate 10 and the protective sheet 40. It can be understood that when the bonding area between the adhesive layer 20 and the waveguide substrate 10 accounts for too small an area of ​​the overlapping area between the waveguide substrate 10 and the protective sheet 40, which is less than 30%, the bonding between the waveguide substrate 10 and the protective sheet 40 will be weak, and the structure of the entire optical waveguide packaging structure 100 will be unstable. When the bonding area between the adhesive layer 20 and the waveguide substrate 10 accounts for more than or equal to 30% of the area of ​​the overlapping area between the waveguide substrate 10 and the protective sheet 40, the amount of glue used can be small while ensuring the overall structure of the optical waveguide packaging structure 100 is stable, and the adhesive performance requirements of the glue are low. For instance, in some specific examples, the bonding area between the adhesive layer 20 and the waveguide substrate 10 accounts for 30%, 35%, 40%, 45%, 50%, 55%, 60%, 80%, 100% of the overlapping area of ​​the waveguide substrate 10 and the protective sheet 40.

[0057] In the present invention, the bonding area between the adhesive layer 20 and the waveguide substrate 10 can account for 30% to 40% of the area of ​​the region where the waveguide substrate 10 and the protective sheet 40 are aligned and overlapped, thereby realizing a frame-mounted packaging structure.

[0058] In the present invention, when the bonding area between the adhesive layer 20 and the waveguide substrate 10 accounts for 100% of the area of ​​the region where the waveguide substrate 10 and the protective sheet 40 are aligned and overlapped, a fully fitted packaging structure is achieved. For the fully fitted packaging structure, the grating structure 30 between the waveguide substrate 10 and the protective sheet 40 of the present invention is covered by the entire adhesive layer 20. When stress is transmitted to the surface of the optical waveguide packaging structure 100, the stress can be quickly dispersed along the entire adhesive layer 20, and the structure of the entire optical waveguide packaging structure 100 is more stable, and cracks are not easy to form between the waveguide substrate 10 and the protective sheet 40. In some embodiments, the material of the protective sheet 40 is one or more of polycarbonate, acrylic, cycloolefin copolymer plastic, or cycloolefin polymer.

[0059] In some examples, the material of the waveguide substrate 10 is one or more of polycarbonate, acrylic, cyclic olefin copolymer plastic, or cyclic olefin polymer.

[0060] The protective sheet 40 and the waveguide substrate 10 made of the above materials have good transparency, are light in weight, have certain mechanical strength and toughness, are not easily broken by external forces, are convenient for packaging the grating structure 30, and can also effectively protect the grating structure 30.

[0061] For example, when polycarbonate (PC) is used, it is colorless, transparent, heat-resistant, impact-resistant, low-priced and easy to obtain. When acrylic (PMMA, polymethyl methacrylate) is used, it has high permeability, good toughness, high hardness, is not easy to break, and is easy to bond. When cycloolefin copolymer plastics (COC plastics) are used, it has high transparency, excellent low-temperature impact resistance and elasticity. When cycloolefin polymer (COP) is used, it has the characteristics of high transparency, high gloss, high water vapor barrier, high rigidity and high strength and excellent chemical resistance. Of course, the material selection of the protective film 40 and the waveguide substrate 10 of the present invention is not limited to the above-mentioned material types, and can also be other polymer materials with similar properties.

[0062] The packaging method of the optical waveguide packaging structure 100 of the present invention is described below.

[0063] like Figure 5 As shown, the packaging method of the optical waveguide packaging structure 100 proposed by the present invention includes the following steps:

[0064] S10, providing a waveguide substrate 10 and a protective sheet 40. The materials of the waveguide substrate 10 and the protective sheet 40 are as described above, and are not described here in detail. In addition, the sizes of the waveguide substrate 10 and the protective sheet 40 can be the same or different, and are not limited here. The thickness of the waveguide substrate 10 and the protective sheet 40 can also be adjusted according to actual needs.

[0065] S20, fabricating a grating structure 30 on one side of the waveguide substrate 10. The grating structure 30 here can be one or more required types of gratings such as an in-coupling grating, an out-coupling grating, a transmission grating, a reflection grating, etc. The thickness and size of the grating structure 30 can be adjusted according to actual needs.

[0066] S30, coating a curable adhesive on the side of the waveguide substrate 10 having the grating structure 30, and the curable adhesive is coated at least around the grating structure 30. The amount of curable adhesive applied can be adjusted according to actual needs, and at least not less than 30% of the centerable overlap area of ​​the waveguide substrate 10 and the protective sheet 40 to ensure the final bonding effect. The coating thickness of the curable adhesive should not be less than the thickness of the grating structure 30.

[0067] S40, attach the protection sheet 40 to the curable adhesive facing the waveguide substrate 10, and make at least part of the edge of the protection sheet 40 laterally shrink inward, expand outward, or stagger relative to the edge of the waveguide substrate 10. The position of the staggered setting can be selected according to actual needs.

[0068] For example, edge sensitive areas of the waveguide substrate 10 and / or the protective sheet 40 may be selected, such as Figure 4The protective sheet 40 shown in the figure corresponds to the edge position of the sensitive area (the area where the grating structure 30 is imprinted). When aligned, the edge of the waveguide substrate 10 and the edge of the protective sheet 40 form a non-overlapping arrangement, so that at least the edge position of the waveguide substrate 10 and / or the protective sheet 40 at the corresponding sensitive area forms a non-overlapping arrangement.

[0069] S50, curing the curable adhesive to form an adhesive layer 20, and obtaining the optical waveguide packaging structure 100. The curable adhesive here is cured by at least one of heat curing, pressure curing or ultraviolet curing. Thus, when the curable adhesive is cured, the waveguide substrate 10 and the protective sheet 40 are bonded together, and the grating structure 30 is packaged.

[0070] From the above, it can be seen from the above technical scheme that the packaging method of the optical waveguide packaging structure 100 proposed in the present invention can reliably package the grating structure 30, and the manufactured optical waveguide packaging structure 100 has good reliability, good overall anti-drop performance, and low demand for high glue adhesion performance.

[0071] The optical waveguide packaging structure 100 and the packaging method thereof of the present invention are further described below in conjunction with specific embodiments.

[0072] Implementation Case 1

[0073] An optical waveguide packaging structure 100, such as Figure 1 As shown, it includes a waveguide substrate 10, a protective sheet 40, an adhesive layer 20 and a grating structure 30. Among them, the protective sheet 40 and the waveguide substrate 10 are arranged at intervals relative to each other and in parallel, and the protective sheet 40 and the waveguide substrate 10 are connected through the adhesive layer 20. The orthographic projection of the edge of the protective sheet 40 on the surface where the waveguide substrate 10 is located is located outside the contour of the waveguide substrate 10, so that the entire edge of the protective sheet 40 is laterally expanded relative to the waveguide substrate 10. The grating structure 30 is arranged on the waveguide substrate 10, and the grating structure 30 is located in the orthographic projection plane of the protective sheet 40 on the waveguide substrate 10. The area of ​​the region where the waveguide substrate 10 and the protective sheet 40 are staggered accounts for 0.6% of the area of ​​the region where the waveguide substrate 10 and the protective sheet 40 are arranged in a centering overlap. The thickness of the adhesive layer 20 is 3 times the thickness of the grating structure 30. PMMA is selected for the waveguide substrate 10, and PC is selected for the protective sheet 40.

[0074] A packaging method for an optical waveguide packaging structure 100 comprises the following steps:

[0075] S10, providing a waveguide substrate 10 and a protective sheet 40 of different sizes, wherein the size of the protective sheet 40 is larger than that of the waveguide substrate 10. The waveguide substrate 10 is made of PMMA, and the protective sheet 40 is made of PC.

[0076] S20 , manufacturing a grating structure 30 on one side of the waveguide substrate 10 , wherein the grating structure 30 avoids an edge position of the waveguide substrate 10 .

[0077] S30. Coat a curable glue on the side of the waveguide substrate 10 having the grating structure 30. The thickness of the curable glue is 3 times the thickness of the grating structure 30. The curable glue is coated around the grating structure 30 and fills the edge of the waveguide substrate 10 with the curable glue. The area filled with the curable glue accounts for 30% of the area of ​​the waveguide substrate 10 (that is, the area filled with the curable glue accounts for 30% of the area of ​​the region where the waveguide substrate 10 and the protective sheet 40 overlap).

[0078] S40 , attaching the protection sheet 40 to the curable adhesive facing the waveguide substrate 10 , and making the entire edge of the protection sheet 40 expand outward relative to the edge of the waveguide substrate 10 , so that the protection sheet 40 can completely cover the waveguide substrate 10 .

[0079] S50 , UV-curing the curable adhesive to form an adhesive layer 20 , thereby obtaining an optical waveguide packaging structure 100 .

[0080] Implementation Case 2

[0081] An optical waveguide packaging structure 100, such as Figure 2 As shown, it includes a waveguide substrate 10, a protective sheet 40, an adhesive layer 20 and a grating structure 30. Among them, the protective sheet 40 and the waveguide substrate 10 are arranged at intervals relative to each other and in parallel, and the protective sheet 40 and the waveguide substrate 10 are connected by the adhesive layer 20. The orthographic projection of the edge of the waveguide substrate 10 on the surface where the protective sheet 40 is located is located outside the outline of the protective sheet 40, so that the entire edge of the protective sheet 40 is laterally retracted relative to the edge of the waveguide substrate 10. The grating structure 30 is arranged on the waveguide substrate 10, and the grating structure 30 is located in the orthographic projection plane of the protective sheet 40 on the waveguide substrate 10. The area of ​​the region where the waveguide substrate 10 and the protective sheet 40 are misaligned accounts for 0.8% of the area of ​​the region where the waveguide substrate 10 and the protective sheet 40 are aligned and overlapped. The thickness of the adhesive layer 20 is 3.3 times the thickness of the grating structure 30. The waveguide substrate 10 uses PC, and the protective sheet 40 uses COC.

[0082] A packaging method for an optical waveguide packaging structure 100 comprises the following steps:

[0083] S10, providing a waveguide substrate 10 and a protective sheet 40 of different sizes, wherein the size of the waveguide substrate 10 is larger than that of the protective sheet 40. The waveguide substrate 10 is made of PC, and the protective sheet 40 is made of COC.

[0084] S20 , manufacturing a grating structure 30 on one side of the waveguide substrate 10 , wherein the grating structure 30 avoids an edge position of the waveguide substrate 10 .

[0085] S30. Coat a curable glue on the side of the waveguide substrate 10 having the grating structure 30. The thickness of the curable glue is 3.3 times the thickness of the grating structure 30. The curable glue is coated around the grating structure 30, and the curable glue leaves an edge area of ​​the waveguide substrate 10. The curable glue is filled in the area of ​​the waveguide substrate 10 closer to the grating structure 30. The area filled with the curable glue accounts for 30% of the area of ​​the protective sheet 40 (that is, the area filled with the curable glue accounts for 30% of the area of ​​the region where the waveguide substrate 10 and the protective sheet 40 overlap).

[0086] S40, attach the protection sheet 40 onto the curable adhesive facing the waveguide substrate 10, and make the edge of the protection sheet 40 located within the contour of the waveguide substrate 10, and the edge of the protection sheet 40 is covered with the curable adhesive, so that the entire edge of the protection sheet 40 is laterally retracted relative to the waveguide substrate 10, and the waveguide substrate 10 can completely cover the protection sheet 40.

[0087] S50 , thermally curing the curable adhesive to form an adhesive layer 20 , thereby obtaining an optical waveguide packaging structure 100 .

[0088] Implementation Case 3

[0089] An optical waveguide packaging structure 100, such as Figure 3 As shown, it includes a waveguide substrate 10, a protective sheet 40, a glue layer 20 and a grating structure 30. The protective sheet 40 and the waveguide substrate 10 are arranged at intervals relative to each other and are arranged at intervals in parallel. The protective sheet 40 and the waveguide substrate 10 are connected through the glue layer 20. The orthographic projection of a part of the first edge 11 of the waveguide substrate 10 on the surface where the protective sheet 40 is located is located outside the outline of the protective sheet 40, and the orthographic projection of a part of the second edge 41 of the protective sheet 40 on the surface where the waveguide substrate 10 is located is located outside the outline of the waveguide substrate 10, so that the edge of the protective sheet 40 is misaligned with the edge of the waveguide substrate 10. The grating structure 30 is arranged on the waveguide substrate 10, and the grating structure 30 is located in the orthographic projection plane of the protective sheet 40 on the waveguide substrate 10. The area of ​​the region where the waveguide substrate 10 and the protective sheet 40 are misaligned accounts for 1.0% of the area of ​​the region where the waveguide substrate 10 and the protective sheet 40 are arranged in a centering overlap. The thickness of the glue layer 20 is 3.5 times the thickness of the grating structure 30. The waveguide substrate 10 is made of PMMA, and the protection sheet 40 is made of COP.

[0090] A packaging method for an optical waveguide packaging structure 100 comprises the following steps:

[0091] S10, providing a waveguide substrate 10 and a protective sheet 40 of substantially the same size. The waveguide substrate 10 is made of PMMA, and the protective sheet 40 is made of COP.

[0092] S20 , manufacturing a grating structure 30 on one side of the waveguide substrate 10 , wherein the grating structure 30 avoids an edge position of the waveguide substrate 10 .

[0093] S30. Apply curable glue on one side of the waveguide substrate 10 having the grating structure 30. The thickness of the curable glue is twice the thickness of the grating structure 30. The curable glue covers the grating structure 30. The curable glue also completely covers the area where the protective sheet 40 and the waveguide substrate 10 are to be overlapped and aligned. The area filled with the curable glue accounts for 100% of the area where the waveguide substrate 10 and the protective sheet 40 are overlapped.

[0094] S40, attach the protection sheet 40 to the curable adhesive facing the waveguide substrate 10, and make a part of the second edge 41 of the protection sheet 40 outside the outline of the waveguide substrate 10, and make a part of the first edge 11 of the waveguide substrate 10 outside the outline of the protection sheet 40, and the area where the protection sheet 40 and the waveguide substrate 10 are aligned and overlapped is covered with the curable adhesive, so that the edge of the protection sheet 40 and the edge of the waveguide substrate 10 are offset from each other.

[0095] S50 , pressure-curing the curable adhesive to form an adhesive layer 20 , thereby obtaining an optical waveguide packaging structure 100 .

[0096] Implementation Case 4

[0097] An optical waveguide packaging structure 100, such as Figure 4 As shown, it includes a waveguide substrate 10, a protective sheet 40, a glue layer 20 and a grating structure 30. Among them, the protective sheet 40 and the waveguide substrate 10 are arranged at intervals relative to each other and arranged in parallel, and the protective sheet 40 and the waveguide substrate 10 are connected through the glue layer 20. The orthographic projection of part of the first edge 11 of the waveguide substrate 10 on the surface where the protective sheet 40 is located is located outside the contour of the second edge 41 of the protective sheet 40, and is located outside the contour of the sensitive area of ​​the protective sheet 40, so that part of the edge of the protective sheet 40 is misaligned with the edge of the waveguide substrate 10. The grating structure 30 is arranged on the waveguide substrate 10, and the grating structure 30 is located in the orthographic projection plane of the protective sheet 40 on the waveguide substrate 10. The area of ​​the region where the waveguide substrate 10 and the protective sheet 40 are misaligned accounts for 0.2% of the area of ​​the region where the waveguide substrate 10 and the protective sheet 40 are arranged in a centering overlap. The thickness of the glue layer 20 is 1.2 times the thickness of the grating structure 30. The waveguide substrate 10 uses PC, and the protective sheet 40 uses COP.

[0098] A packaging method for an optical waveguide packaging structure 100 comprises the following steps:

[0099] S10, providing a waveguide substrate 10 and a protective sheet 40 of different sizes, wherein the size of the waveguide substrate 10 is larger than that of the protective sheet 40. The waveguide substrate 10 is made of PC, and the protective sheet 40 is made of COP.

[0100] S20 , manufacturing a grating structure 30 on one side of the waveguide substrate 10 , wherein the grating structure 30 avoids an edge position of the waveguide substrate 10 .

[0101] S30. Coat a curable glue on the side of the waveguide substrate 10 having the grating structure 30. The thickness of the curable glue is 1.2 times the thickness of the grating structure 30. The curable glue is coated around the grating structure 30, and the curable glue leaves a portion of the edge area of ​​the waveguide substrate 10 to be staggered. The area filled with the curable glue accounts for 30% of the area of ​​the protective sheet 40 (that is, the area filled with the curable glue accounts for 30% of the area of ​​the region where the waveguide substrate 10 and the protective sheet 40 overlap).

[0102] S40, attach the protection sheet 40 to the curable glue facing the waveguide substrate 10, and make the second edge 41 of the sensitive area of ​​the protection sheet 40 located within the contour of the waveguide substrate 10, and the edges of the protection sheet 40 are all covered with the curable glue, so that the second edge 41 of the protection sheet 40 located in the sensitive area is laterally retracted relative to the first edge 11 of the waveguide substrate 10 at this location.

[0103] S50 , UV-curing the curable adhesive to form an adhesive layer 20 , thereby obtaining an optical waveguide packaging structure 100 .

[0104] The products of the optical waveguide packaging structure 100 of Examples 1-4 of the present invention were subjected to a 1.8m drop test, and under the same test conditions, a comparative example (regardless of whether it is a frame-mounted packaging structure or a fully-fitted packaging structure) in which the edge of the waveguide substrate 10 and the edge of the protective sheet 40 are completely aligned and overlapped, the grating structure 30 is arranged between the waveguide substrate 10 and the protective sheet 40, and the edge of the protective sheet 40 and the waveguide substrate 10 are bonded by adhesive was tested. Finally, the comparative example failed to pass the 1.8m drop test, and its edges cracked and deformed after falling; while the products in Examples 1-4 of the present invention can pass the 1.8m drop test, and the edges of the products in each embodiment can absorb the deformation caused by the drop after falling, the edges do not crack or the probability of cracking is extremely small, and the comparative example has excellent drop resistance and good optical waveguide working reliability.

[0105] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. An optical waveguide packaging structure, characterized in that: include: waveguide substrate; A protection sheet, wherein the protection sheet and the waveguide substrate are arranged relative to each other and are spaced apart from each other, and the protection sheet and the waveguide substrate are connected by an adhesive layer, and at least a portion of the edge of the protection sheet is laterally expanded and exceeds the edge of the waveguide substrate; or at least a portion of the edge of the protection sheet is laterally contracted and contracted into the edge of the waveguide substrate; or the edge of the protection sheet and the edge of the waveguide substrate are arranged in a staggered manner; A grating structure is provided on the waveguide substrate, and the grating structure is located within the orthographic projection plane of the protection sheet on the waveguide substrate.

2. The optical waveguide packaging structure according to claim 1, characterized in that: The protection sheet is arranged parallel to and spaced from the waveguide substrate, and at least part of the edge of the protection sheet has its orthographic projection on the surface where the waveguide substrate is located outside the contour of the waveguide substrate, so that at least part of the edge of the protection sheet expands laterally relative to the edge of the waveguide substrate.

3. The optical waveguide packaging structure according to claim 1, characterized in that: The protection sheet is arranged parallel to and spaced from the waveguide substrate, and the orthographic projection of at least part of the edge of the waveguide substrate on the surface where the protection sheet is located is located outside the contour of the protection sheet, so that at least part of the edge of the protection sheet is laterally retracted relative to the edge of the waveguide substrate.

4. The optical waveguide packaging structure according to claim 1, wherein: The protection sheet is arranged parallel to the waveguide substrate and spaced apart, the orthographic projection of part of the edge of the waveguide substrate on the surface where the protection sheet is located is located outside the outline of the protection sheet, and the orthographic projection of part of the edge of the protection sheet on the surface where the waveguide substrate is located is located outside the outline of the waveguide substrate, so that the edge of the protection sheet and the edge of the waveguide substrate are staggered.

5. The optical waveguide packaging structure according to any one of claims 1 to 4, characterized in that: The area of ​​the region where the waveguide substrate and the protection sheet are staggered accounts for 0.2% to 1% of the area of ​​the region where the waveguide substrate and the protection sheet are aligned and overlapped.

6. The optical waveguide package structure according to any one of claims 1 to 4, characterized in that: The adhesive layer is coated on the region where the waveguide substrate and the protective sheet are centrally arranged and overlapped, and the adhesive layer is arranged around the grating structure; or, The adhesive layer is coated on the area where the waveguide substrate and the protection sheet are centrally arranged and overlapped, and the adhesive layer covers all the grating structures.

7. The optical waveguide packaging structure according to claim 6, characterized in that: The thickness of the glue layer is 1 to 3.5 times the thickness of the grating structure; and / or, The bonding area between the adhesive layer and the waveguide substrate accounts for more than or equal to 30% of the area of ​​the region where the waveguide substrate and the protection sheet are centrally overlapped.

8. The optical waveguide packaging structure according to claim 1, wherein: The material of the protective film is one or more of polycarbonate, acrylic, cycloolefin copolymer plastic or cycloolefin polymer; and / or the material of the waveguide substrate is one or more of polycarbonate, acrylic, cycloolefin copolymer plastic or cycloolefin polymer.

9. A packaging method for an optical waveguide packaging structure according to any one of claims 1 to 8, characterized in that: The steps include: Providing a waveguide substrate and a protective sheet; Fabricating a grating structure on one side of the waveguide substrate; Applying a curable adhesive on one side of the waveguide substrate having the grating structure, wherein the curable adhesive is at least applied around the grating structure; Attach the protection sheet to the curable adhesive facing the waveguide substrate, and make at least part of the edge of the protection sheet laterally shrink inward, expand outward, or be staggered relative to the edge of the waveguide substrate; The curable adhesive is cured to form an adhesive layer to obtain the optical waveguide packaging structure.

10. The packaging method of the optical waveguide packaging structure according to claim 9, characterized in that: The curable adhesive is cured by at least one of heat curing, pressure curing or UV curing.

11. The packaging method of the optical waveguide packaging structure according to claim 9, characterized in that: For the sensitive area at the edge of the waveguide substrate and / or the protection sheet, the edge of the waveguide substrate and the edge of the protection sheet are arranged non-overlappingly during alignment, so that at least the edges at the corresponding sensitive areas are arranged non-overlappingly.

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