Optical element and related device

Abstract

The embodiment of the invention discloses an optical element and a related device, which are used for reducing the manufacturing difficulty of a suspended metasurface structure. The optical element provided by the embodiment of the invention comprises a substrate layer, a metasurface layer, a two-dimensional material layer and a two-dimensional material protection layer which are sequentially arranged from bottom to top. The metasurface layer comprises dielectric units which are periodically arranged on the upper surface of the substrate layer. The two-dimensional material layer covers the metasurface layer, and adjacent dielectric units in the periodically arranged dielectric units, the upper surface of the substrate layer and the lower surface of the two-dimensional material layer form a cavity. The two-dimensional material serves as a supporting structure above the cavity and is used for guaranteeing the structural stability of the cavity. And the two-dimensional material protection layer grows above the two-dimensional material layer and is used for preventing the two-dimensional material layer from being damaged.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of optics, and in particular to an optical element and related devices. Background Art

[0002] Grating is an important device in the field of optics. Gratings are composed of periodically arranged high-refractive index media and low-refractive index media. In the optical design of gratings, the refractive index ratio between the high-refractive index medium and the low-refractive index medium of the grating is an important reference indicator in the design. In order to achieve better performance, a grating structure with a high refractive index ratio is usually designed, that is, the refractive index ratio between the grating media is higher.

[0003] The refractive index of air is 1, which is a medium with a low refractive index. Therefore, by using air as a low refractive index medium and selecting a combination of high refractive index medium materials, a grating with a high refractive index ratio can be prepared. This grating is called a suspended grating. The suspended grating structure includes periodically arranged high refractive index media, and the gaps between the high refractive index media are filled with air. Since part of the other media on the upper layer of the grating (usually the upper substrate) needs to be suspended in the air, it is called a suspended grating.

[0004] In the process of preparing a suspended grating structure, a bonding process is usually used to connect the grating to other media on the upper layer of the grating. Therefore, the preparation of the grating needs to meet the preparation conditions of the bonding process. Due to the high process complexity and low product yield of the bonding process, the grating is difficult to manufacture. Similarly, in addition to gratings, the bonding process is also used in the preparation process of other optical elements including suspended metasurface structures, which makes the manufacturing of suspended metasurface structures difficult. Summary of the invention

[0005] The embodiments of the present application provide an optical element and related devices for reducing the difficulty of manufacturing a suspended metasurface structure.

[0006] In a first aspect, an embodiment of the present application provides an optical element. The optical element includes: a substrate layer, a supersurface layer, a two-dimensional material layer, and a two-dimensional material protective layer arranged in sequence from bottom to top. Among them, the supersurface layer includes dielectric units periodically arranged on the upper surface of the substrate layer. The two-dimensional material layer covers the supersurface layer, and the adjacent dielectric units in the periodically arranged dielectric units, the upper surface of the substrate layer, and the lower surface of the two-dimensional material layer constitute a cavity. The two-dimensional material layer serves as a supporting structure above the cavity to ensure the structural stability of the cavity. The two-dimensional material protective layer grows above the two-dimensional material layer to prevent the two-dimensional material layer from being damaged.

[0007] In the embodiment of the present application, for the two-dimensional material layer, the layer relies on chemical bonds (such as covalent bonds) to link, and relies on van der Waals force to link with other layers (such as super surface layers), so that the layered structure of the two-dimensional material layer is relatively stable. Therefore, the two-dimensional material layer is used as a supporting structure above the cavity to ensure the structural stability of the cavity. The embodiment of the present application replaces the bonding technology by two-dimensional material transfer technology to achieve the link between the super surface layer and the two-dimensional material layer, so as to connect the super surface layer with the structure above the super surface layer. Compared with the bonding technology, the process of two-dimensional material transfer technology is relatively simple, and the growth process of preparing other structures (such as two-dimensional material protective layer and other layers above) above the two-dimensional material protective layer is also relatively simple, so the manufacturing difficulty of the suspended super surface structure can be reduced. Moreover, compared with the bonding process, the product yield of the two-dimensional material transfer technology is higher. Therefore, the optical element provided in the embodiment of the present application can also improve the product yield and reduce the manufacturing cost.

[0008] In an embodiment of the present application, during the process of transferring the two-dimensional material layer, the two-dimensional material protective layer can serve as a structural support for the two-dimensional material layer to prevent the two-dimensional material layer with a smaller thickness from being damaged during the process of transferring the two-dimensional material, thereby ensuring the layered structural integrity of the two-dimensional material layer.

[0009] It is worth noting that the up and down directions described in the embodiments of the present application refer to the up and down directions during the manufacturing process. During the actual use of the structure, the overall structure may be flipped, and the up and down directions will change accordingly, which will not be repeated here.

[0010] In an optional implementation, the optical element further includes a two-dimensional material protection layer. The two-dimensional material protection layer is grown on the two-dimensional material layer to prevent the two-dimensional material layer from being damaged and to ensure the integrity of the layered structure of the two-dimensional material layer.

[0011] In an optional implementation, the material of the two-dimensional material layer includes at least one of the following: graphene, hexagonal boron nitride, and a layered transition metal chalcogenide. The layered transition metal chalcogenide has a composition formula of AB, A includes at least one of Zr, Hf, V, Nb, Ta, Mo, W, Pd, and Pt, and B includes at least one of S, Se, and Te.

[0012] In an optional implementation, the material of the two-dimensional material layer includes at least one of the following: graphene, molybdenum disulfide, tungsten disulfide and molybdenum telluride.

[0013] Materials such as graphene, molybdenum disulfide, tungsten disulfide and molybdenum telluride have the characteristics of high strength, large band gap (for example, greater than or equal to 1 resistive volt), and large-area growth. The embodiments of the present application use these materials as materials for the two-dimensional material layer, which has the following advantages: Due to the high strength of the material, the two-dimensional material protective layer and the upper structure can be better supported, thereby improving the stability of the cavity structure. Due to the large band gap of the material, it has low absorption and high transparency to light in the communication band, so that the optical element can be used as a high-performance reflection, modulation and other elements in communication equipment. Since the material can be grown over a large area, the area of ​​the two-dimensional material layer is large enough to be compatible with the mainstream product size. For example, the mainstream optical chip size is 8 inches or 12 inches. Only by using materials that can be grown over a large area can the two-dimensional material layer be made into an area of ​​8 inches or 12 inches to adapt to the mainstream chip size. Optionally, materials grown over a large area can also be adapted to other product sizes, which is not limited in this application.

[0014] Optionally, in addition to the above materials, other transition metal sulfide compounds with high strength, large band gap, and large-area growth characteristics can also be used as materials for the two-dimensional material layer to obtain the above advantages.

[0015] In an optional implementation, the thickness of the two-dimensional material layer is d1, 0.3nm≤d1≤100nm.

[0016] In an optional implementation, 0.3 nm≤d1≤20 nm.

[0017] In the embodiment of the present application, the material of the two-dimensional material layer may absorb optical signals in certain communication bands (e.g., the 1060nm band). Reducing the thickness of the two-dimensional material layer to less than or equal to 20nm can reduce the absorption degree of the two-dimensional material layer on the optical signals in these communication bands, thereby improving the performance of the optical element.

[0018] Optionally, the thickness d1 of the two-dimensional material layer can be 5 nm, 6 nm, 10 nm, 12 nm, 15 nm, 18 nm, etc., which is not limited in the present application.

[0019] Optionally, the two-dimensional material layer may be a single layer or a few layers of two-dimensional material, which is not limited in the present application.

[0020] In an optional implementation, the material of the two-dimensional material protection layer includes at least one of the following: metal, semiconductor material and oxide.

[0021] In an optional implementation, the shape of the dielectric unit includes at least one of the following: a grating, a prism, a cylinder, an elliptical cylinder, a mesh, or a T-shaped column.

[0022] In an optional implementation, the thickness of the dielectric unit is d2, 10 nm≤d2≤10000 nm.

[0023] In an optional implementation, the thickness d2 of the dielectric unit may be in the range of 50 nm ≤ d2 ≤ 3000 nm.

[0024] The wavelength range of visible light is 390nm-780nm, the wavelength range of infrared is above 760nm, the commonly used wavelength of optical communication is 1550nm (1260nm-1675nm), and the wavelength range of mid-infrared is 3000nm-5000nm. In the embodiment of the present application, the thickness d2 of the dielectric unit is limited to 50nm≤d2≤3000nm, so that the thickness of the dielectric unit is around one-third of the target wavelength, and the optical element can be used as a sub-wavelength optical device of the target wavelength (wavelength range is 150nm-10000nm). Sub-wavelength optical devices only have zero-order reflection and diffraction for incident light, which can achieve functions such as suppressing higher-order modes and polarization selection. Therefore, it is used in scenes such as wide-spectrum high-reflection, high-pulse ratio lasers, hollow waveguide structures, slow light effect crystals, and femtosecond laser frequency modulation.

[0025] In an optional implementation manner, the material of the dielectric unit includes at least one of the following: metal, semiconductor material and oxide.

[0026] In an optional implementation, the distance between the upper surface of the two-dimensional material layer and the lower surface of the supersurface layer is r, 0.2nm≤r≤5nm.

[0027] In an embodiment of the present application, the upper surface of the two-dimensional material layer and the lower surface of the super surface layer are linked by van der Waals force (scope of action 0.2nm-5nm). Therefore, the bonding technology can be replaced by the two-dimensional material transfer technology to realize the link between the super surface layer and the two-dimensional material protective layer. Since the process of the two-dimensional material transfer technology is relatively simple compared to the bonding technology, and the growth process of preparing the two-dimensional material protective layer above the two-dimensional material layer is also relatively simple, it is possible to reduce the manufacturing difficulty of the suspended super surface structure. Moreover, compared to the bonding process, the product yield of the two-dimensional material transfer technology is higher. Therefore, the optical element provided in the embodiment of the present application can also improve the product yield and reduce the manufacturing cost.

[0028] In a second aspect, an embodiment of the present application provides an optical element. The optical element includes: a substrate layer, a supersurface layer, and a two-dimensional material layer arranged in sequence from bottom to top. The supersurface layer includes dielectric units periodically arranged on the upper surface of the substrate layer. The two-dimensional material layer covers the supersurface layer, and adjacent dielectric units in the periodically arranged dielectric units, the upper surface of the substrate layer, and the lower surface of the two-dimensional material layer constitute a cavity. The two-dimensional material layer serves as a supporting structure above the cavity to ensure the structural stability of the cavity. The band gap of the two-dimensional material layer is greater than or equal to 1 resistive volt, and the thickness is greater than or equal to 1 nm.

[0029] In an embodiment of the present application, a two-dimensional material layer is covered on the super surface layer as a support structure of the cavity. Since the band gap of the two-dimensional material layer is greater than or equal to 1 resistance volt, the light energy of the communication band can be reflected and transmitted by the two-dimensional material layer, so that the two-dimensional material layer has a small degree of light absorption of the communication band, and the optical element can have good optical properties. Since the thickness of the two-dimensional material layer is greater than or equal to 1nm, it is not easy to be damaged, and there is no need to set other structures on the two-dimensional material layer to protect the two-dimensional material layer, and the structure is simple.

[0030] In an optional implementation, the material of the two-dimensional material layer includes molybdenum disulfide.

[0031] In a third aspect, an embodiment of the present application provides an optical device, which includes a light-conducting element and the optical element described in the first aspect or the second aspect, wherein the light-conducting element is used to conduct the optical signal to the optical element, and the optical element is used to realize reflection, modulation or conduction of the optical signal.

[0032] In an optional implementation, the optical device is at least one of the following: a light emitting chip, a light receiving chip, a light modulating chip, a liquid crystal on silicon (LCOS) chip, and a microelectro mechanical system (MEMS).

[0033] In a fourth aspect, an embodiment of the present application provides an optical communication device, comprising an interface and the optical device described in the third aspect. The interface is used to connect an optical fiber and transmit an optical signal from the optical fiber to the optical device.

[0034] In a fifth aspect, an embodiment of the present application provides a light display device, comprising a light source and the optical device described in the third aspect. The light source is used to emit target light, and the target light is transmitted to the optical device.

[0035] The target light may be natural light, full-color light, full-polarized light, etc., which is not limited in the present application. The optical device may conduct and modulate the target light to obtain display light.

[0036] The beneficial effects of the third to fifth aspects refer to the first and second aspects and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic diagram of the structure of the grating provided in this application;

[0038] Figure 2 A schematic diagram of the preparation process of the suspended grating provided in this application;

[0039] Figure 3 A schematic structural diagram of an optical element with a suspended structure provided in an embodiment of the present application;

[0040] Figure 4a A schematic diagram of the preparation process of an optical element provided in an embodiment of the present application;

[0041] Figure 4b Another schematic diagram of the structure of an optical element provided in an embodiment of the present application;

[0042] Figure 4c A schematic diagram of the structure of the substrate layer and the super surface layer provided in the embodiment of the present application;

[0043] Figure 5 A schematic diagram of the structure of an optical element provided in an embodiment of the present application without a two-dimensional material protective layer;

[0044] Figure 6 A schematic structural diagram of an optical element in which the dielectric unit provided in an embodiment of the present application is a long prism;

[0045] Figure 7 A schematic structural diagram of an optical element in which the dielectric unit provided in an embodiment of the present application is a prism;

[0046] Figure 8 A schematic structural diagram of an optical element in which the dielectric unit provided in an embodiment of the present application is a cylindrical optical element;

[0047] Fig. 9 A schematic diagram of the structure of a mesh optical element in which the dielectric unit provided in an embodiment of the present application is provided;

[0048] Fig.10 A schematic diagram of the structure of the modulator provided in this application;

[0049] Fig.11 A schematic diagram of the pulse ratio of an optical element provided in an embodiment of the present application. DETAILED DESCRIPTION

[0050] The embodiments of the present application are described below in conjunction with the accompanying drawings. Those skilled in the art will appreciate that, with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0051] The terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchanged in appropriate circumstances, which is only to describe the distinction mode adopted by the objects of the same attribute in the embodiments of the present application when describing. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, so that the process, method, system, product or equipment containing a series of units need not be limited to those units, but may include other units that are not clearly listed or inherent to these processes, methods, products or equipment. In addition, "at least one" refers to one or more, and "multiple" refers to two or more. "And / or", describes the association relationship of associated objects, indicating that three relationships can exist, for example, A and / or B, can represent: A exists alone, A and B exist simultaneously, and B exists alone, wherein A, B can be singular or plural. The character " / " generally represents that the associated objects before and after are a kind of "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, or c can mean: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or plural.

[0052] Optical diffraction grating (grating for short) is an important device in the field of optics and is widely used in holographic display, laser, detector and other optoelectronic devices. Figure 1 As shown, the grating consists of a periodically arranged high refractive index medium and a low refractive index medium.

[0053] The grating period is an important parameter of the grating, which indicates the length of the grating from one refractive index change point to the adjacent refractive index change point. If the grating period of the grating is smaller than the incident wavelength of the light signal, the grating is a sub-wavelength grating (SWG). The working period of the sub-wavelength grating SWG is smaller than the incident wavelength, and there is only zero-order reflection and diffraction for the incident light, which can achieve functions such as suppressing high-order modes and polarization selection. Therefore, compared with ordinary gratings, SWG has a higher spectral width and quality factor Q, as well as lower optical loss.

[0054] For example, in applications where gratings are used as optical high-reflection devices, in order to increase the grating's reflection spectrum bandwidth and reduce the thickness of the optical reflective layer, a common approach is to design a SWG with a high refractive index ratio between the grating media. Alternatively, in applications where gratings are used as an optical modulation structure, such as achieving narrow-linewidth single-mode lasers, a common approach is also to design a SWG structure with a high refractive index ratio, so that the quality factor Q value of the structural design is very high, thereby achieving narrow-linewidth single-mode lasers.

[0055] In a grating, the greater the refractive index ratio between the high refractive index medium and the low refractive index medium, the smaller the grating period. In order to prepare an AWG, a common method is to increase the refractive index ratio between the high refractive index medium and the low refractive index medium in the grating. Since the refractive index of air is 1, which is a medium with a relatively low refractive index, a suspended SWG structure has emerged. A suspended SWG includes periodically arranged high refractive index media, and the gaps between the high refractive index media are filled with air. Since part of the other media on the upper layer of the grating (usually the upper substrate) needs to be suspended in the air, it is called a suspended type. The suspended structure cannot achieve the connection between the grating and other media through ordinary growth processes. Therefore, in the preparation process of the suspended SWG, microelectromechanical systems (MEMS) bonding technology is usually used to fix the grating and other media on the upper layer of the grating.

[0056] like Figure 2 As shown, the specific preparation process of the suspended grating includes: preparing the grating on the substrate, and flattening the lower surface of the upper substrate (including but not limited to grinding, polishing and other treatments to ensure that the lower surface of the upper substrate meets the requirements of the bonding process for cleanliness, flatness and other requirements). Similarly, the upper surface of the grating must also be flattened to ensure that the upper surface of the grating meets the requirements of the bonding process for cleanliness, flatness and other requirements. Then, the upper substrate is bonded to the grating, and the grating and the upper substrate are bonded at high temperature. After the high-temperature bonding is completed, the upper surface of the upper substrate is flattened to reduce the thickness of the upper substrate.

[0057] On the one hand, the bonding process is highly complex (for example, in anodic bonding, an external electrode needs to be connected to the bonding interface during the bonding process, and the bonding interface needs to be heated to a high temperature of 300-400°C). On the other hand, the bonding process has high requirements on the cleanliness and flatness of the bonding interface (for example, the lower surface of the upper substrate and the upper surface of the grating mentioned above), resulting in low product yield. Therefore, the preparation of the grating by the bonding process needs to meet the complex preparation conditions of the bonding process, and the manufacturing difficulty of the grating is relatively high.

[0058] The bonding process is usually carried out in a high temperature environment of 300-400℃, which will bring many restrictions to the preparation of the grating. For example, in the high temperature environment of bonding, it is necessary to consider the thermal stress coefficient matching and lattice constant matching between the materials of different layers of the grating, or between the materials of the grating and other device joint surfaces, which limits the material of the grating. In addition, if it is necessary to prepare a device including a grating and an active device (for example, a modulator including a grating, where the active device is a modulation chip), the high temperature will cause damage to the active device during the high temperature bonding process of the grating.

[0059] Similarly, in addition to gratings, other metasurface structures can also be designed in a suspended manner to obtain sub-wavelength optical elements of the target wavelength to achieve functions such as suppression of high-order modes and polarization selection. In the preparation process of other optical elements including suspended metasurfaces, bonding processes are also used. The bonding process makes the manufacturing of suspended metasurface structures difficult.

[0060] In order to solve the above problems, the embodiments of the present application provide an optical element and related devices. The optical element provided in the embodiments of the present application uses two-dimensional material transfer technology to replace bonding to achieve the connection between the metasurface and the upper medium, thereby avoiding many problems caused by the bonding process and reducing the difficulty of manufacturing the suspended metasurface structure.

[0061] like Figure 3 As shown, the optical element 3000 (hereinafter referred to as the optical element 3000) provided in the embodiment of the present application and including a suspended metasurface structure includes: a substrate layer 3100, a metasurface layer 3200, a two-dimensional material layer 3300, and a two-dimensional material protective layer 3400. The substrate layer 3100, the metasurface layer 3200, the two-dimensional material layer 3300, and the two-dimensional material protective layer 3400 are arranged in sequence from bottom to top.

[0062] It is worth noting that the up and down directions described in the embodiments of the present application refer to the up and down directions during the manufacturing process. During the actual use of the structure, the overall structure may be flipped, and the up and down directions will change accordingly, which will not be repeated here.

[0063] Optionally, the material of the substrate layer 3100 may include silicon dioxide. In addition, the material of the substrate layer 3100 may also include other oxides, such as Al2O3, HfO2, ZnO, TiO2, etc., which is not limited in this application. In addition to oxides, the material of the substrate layer 3100 may also include metals (such as Au, Ag, Cu, Ni, Pd, Pt), semiconductor materials (which may be simple substances or composites, such as one or more of Al, Ga, In, C, Si, Ge, Sn, P, As, Sb), etc., which is not limited in this application. Optionally, the substrate layer 3100 may be a single layer material or a composite material, which is not limited in this application.

[0064] In the embodiment of the present application, the super surface layer 3200 is located above the substrate layer 3100. The super surface layer 3200 includes a plurality of dielectric units 3210, which are periodically arranged on the upper surface of the substrate layer 3100.

[0065] In an optional implementation, the material of the super surface layer 3200 is the same as that of the substrate layer 3100, and the substrate layer 3100 and the super surface layer 3200 can be distinguished by the distribution of the materials within the layer.

[0066] In the embodiment of the present application, the substrate layer 3100, the super surface layer 3200, the two-dimensional material layer 3300, etc. are arranged from bottom to top, and the embodiment of the present application defines this direction as the z-axis direction. On a reference plane perpendicular to the z-axis direction (see Figure 4b ) on the substrate layer 3100, the distribution of materials in the substrate layer 3100 is different from the distribution of materials in the super surface layer 3200.

[0067] For example Figure 4c As shown, Figure 4c for Figure 4b The cross-sectional view of the substrate layer 3100 and the super surface layer 3200. The x-axis is a dimension on the reference plane. The substrate layer 3100 is a whole block of SiO2 material (SiO2 is an example and does not limit the material), so the SiO2 of the substrate layer 3100 is continuously distributed in the x-axis direction. The super surface layer 3200 is composed of periodically distributed dielectric units 3210, and the SiO2 of the super surface layer 3200 is periodically distributed along the x-axis direction (the periodically distributed SiO2 is the dielectric unit 3210).

[0068] It is worth noting that, in addition to Figure 4c As shown, the material of the supersurface layer 3200 is periodically distributed along the x-axis direction on the reference plane. The material of the supersurface layer 3200 can also be periodically distributed along both the x-axis direction and the y-axis direction on the reference plane (i.e., multiple dielectric units 3210 are arranged in two dimensions on the reference plane), and this application does not limit this.

[0069] like Figure 4c As shown, there is a plane on the substrate layer 3100 and the super surface layer 3200, below which the material is continuously distributed, and above which the material is periodically distributed along the reference plane. The plane is the interface between the substrate layer 3100 and the super surface layer 3200, and is also the upper surface of the substrate layer 3100.

[0070] exist Figure 4c In the figure, the material of the substrate layer 3100 is the same as the material of the super surface layer 3200. Figure 4c This is just an example, and the material of the substrate layer 3100 may be different from the material of the super surface layer 3200. If the materials of the two layers are different, the interface of the different materials is the upper surface of the substrate layer 3100.

[0071] If the substrate layer 3100 includes multiple sub-layers (for example, a first SiO2 layer and a second SiO2 layer, wherein the first SiO2 layer is undoped and the second SiO2 layer is N-type doped SiO2), the substrate layer 3100 and the super surface layer 3200 can also be distinguished by the distribution of materials as described above. The situation where the super surface layer 3200 includes multiple sub-layers is similar and will not be described in detail here.

[0072] Optionally, a periodically arranged dielectric unit 3210 may be prepared on the substrate layer 3100 by a micro-nano processing process to obtain a super surface layer 3200. Specifically, another material (material B) may be covered on the substrate layer 3100 (material A), and the material B in a part of the area may be removed by etching, stripping, and the like. The area where the material B is removed will expose the material A (the exposed surface is the upper surface of the substrate layer 3100), and the remaining area is the dielectric unit 3210 periodically arranged on the upper surface of the substrate layer 3100.

[0073] Optionally, the material of the dielectric unit 3210 (which is also the material of the supersurface layer 3200) may include metals (such as Au, Ag, Cu, Ni, Pd, Pt), semiconductor materials (which may be simple substances or composites, such as one or more of Al, Ga, In, C, Si, Ge, SnP, As, Sb), oxides (such as SiO2, Al2O3, HfO2, ZnO, TiO2), etc., and the present application does not impose any restrictions on this.

[0074] Optionally, the thickness of the super surface layer 3200 may be 10 nm-10000 nm. That is, if the thickness of the dielectric unit 3210 is d2, then 10 nm≤d2≤10000 nm.

[0075] Optionally, the shape structure of the super surface layer 3200 can be a grating, a slanted grating, a blazed grating, etc., which is not limited in the present application. Optionally, the grating period of the super surface layer 3200 can be 100nm-100000nm, and the duty cycle can be 10%-90%.

[0076] The two-dimensional material layer 3300 covers the super surface layer 3200, and the adjacent dielectric units in the periodically arranged dielectric units 3210, the upper surface of the substrate layer 3100 and the lower surface of the two-dimensional material layer 3300 form a cavity. Figure 4b As shown, the adjacent dielectric units 3210 - 1 and 3210 - 2 , the upper surface of the substrate layer 3100 and the lower surface of the two-dimensional material layer 3300 form a cavity.

[0077] The two-dimensional material layer 3300 serves as a supporting structure above the cavity (i.e., a cover layer for supporting the cavity and other structures above the two-dimensional material layer 3300 ) to ensure the structural stability of the cavity.

[0078] The material of the two-dimensional material layer 3300 is a layered two-dimensional material. Two-dimensional materials refer to materials in which electrons can only move freely (in plane) on a non-nanoscale (1-100nm) in two dimensions, such as nanofilms, superlattices, quantum wells, etc. Two-dimensional materials were proposed in 2004 when the Geim team at the University of Manchester successfully separated a single atomic layer of graphite material, graphene.

[0079] Two-dimensional materials can include single-layer two-dimensional materials, few-layer two-dimensional materials and multi-layer two-dimensional materials. Among them, single-layer two-dimensional materials only include one layer of atoms, and the atoms are linked by chemical bonds (such as covalent bonds). Few-layer two-dimensional materials include two to ten layers of atoms, and the thickness of multi-layer two-dimensional materials is tens of nanometers. If it is a two-dimensional material with few layers or multiple layers, it is a structure stacked layer by layer. In each layer of material, the particles are linked by chemical bonds (such as covalent bonds). Between layers, they are linked by van der Waals forces.

[0080] The material of the two-dimensional material layer 3300 can be Figure 3 In addition, it can also be hexagonal boron nitride, or a layered transition metal chalcogenide (the composition formula is AB, where A is one or more of Zr, Hf, V, Nb, Ta, Mo, W, Pd, Pt, and B is one or more of S, Se, Te). Optionally, the thickness of the two-dimensional material layer 3300 can be 0.3nm-100nm.

[0081] During the preparation of the optical element 3000 , the connection between the supersurface layer 3200 and the upper surface of the two-dimensional material layer 3300 can be achieved through the two-dimensional material transfer technology.

[0082] The optical element 3000 further includes a two-dimensional material protective layer 3400. Figure 3 As shown, the two-dimensional material protection layer 3400 is grown on the two-dimensional material layer 3300. The two-dimensional material protection layer 3400 is used to prevent the two-dimensional material layer 3300 from being damaged and ensure the integrity of the layered structure of the two-dimensional material layer 3300.

[0083] Optionally, the material of the two-dimensional material protective layer 3400 may include SiO2. In addition, the material of the two-dimensional material protective layer 3400 may also include other oxides, such as Al2O3, HfO2, ZnO, TiO2, etc., which is not limited in this application. In addition to oxides, the material of the two-dimensional material protective layer 3400 may also include metals (such as Au, Ag, Cu, Ni, Pd, Pt), semiconductor materials (which may be simple substances or composites, such as one or more of Al, Ga, In, C, Si, Ge, Sn, P, As, Sb), etc., which is not limited in this application. Optionally, the two-dimensional material protective layer 3400 may be a single layer material or a composite material, which is not limited in this application.

[0084] The two-dimensional material protection layer 3400 can prevent the two-dimensional material layer 3300 from being damaged during the preparation process of the optical element 3000. Figure 4a As shown, in the process of preparing the optical element 3000, the super surface layer 3200 is prepared on the substrate layer 3100, and the two-dimensional material protection layer 3400 is grown on the two-dimensional material layer 3300. Then, in the process of transferring the two-dimensional material to the two-dimensional material layer 3300, the two-dimensional material protection layer 3400 can serve as a structural support for the two-dimensional material layer 3300, preventing the two-dimensional material layer 3300 with a smaller thickness from being damaged during the two-dimensional material transfer process, thereby ensuring the layered structural integrity of the two-dimensional material layer 3300.

[0085] During the two-dimensional material transfer process, glue needs to be applied to the upper surface of the two-dimensional material layer 3300 for easy operation. Figure 3 In the structure shown, glue is applied on the two-dimensional material protection layer 3400, and the residual glue generated during the transfer process can be removed by a plasma cleaning process on the two-dimensional material protection layer 3400. In addition, the two-dimensional material layer 3400 can also serve as a substrate for a higher layer, and other materials can be epitaxially grown on the two-dimensional material protection layer 3400 according to subsequent process requirements.

[0086] Optionally, after the two-dimensional material transfer is completed, the two-dimensional material protection layer 3400 can also serve as a structural support for the two-dimensional material layer 3300 to prevent the two-dimensional material layer 3300 from being deformed or damaged due to the extrusion of the upper material, thereby ensuring the structural stability of the cavity.

[0087] like Figure 4a As shown, during the preparation of the optical element 3000, the super surface layer 3200 can be prepared on the substrate layer 3100 by a micro-nano process, and the two-dimensional material protective layer 3400 can be grown on the two-dimensional material layer 3300 by a growth process. Then, the lower surface of the two-dimensional material layer 3300 is linked to the upper surface of the super surface layer 3200 by a two-dimensional material transfer technology. Micro-nano technology, growth technology, two-dimensional material transfer technology and other technologies have low requirements for the preparation environment (no high temperature requirements such as bonding process are required), and the process is also relatively simple. If it is necessary to prepare other layers above the two-dimensional material protective layer 3400, it can be achieved by a simple growth process.

[0088] In the embodiment of the present application, for the two-dimensional material layer 3300, the layer relies on chemical bonds to link, and the layer relies on van der Waals force (range of action is 0.2nm≤r≤5nm) to link with other layers (such as the super surface layer 3200), so that the layered structure of the two-dimensional material is relatively stable. Therefore, the two-dimensional material layer 3300 is used as a supporting structure above the cavity to ensure the structural stability of the cavity. The embodiment of the present application replaces the bonding technology by the two-dimensional material transfer technology to achieve the link between the super surface layer 3200 and the two-dimensional material layer 3300 above the super surface layer 3200, so as to connect the super surface layer 3200 with the structure above the super surface layer 3200. Compared with the bonding technology, the process of the two-dimensional material transfer technology is relatively simple, and the growth process of preparing other structures (such as the two-dimensional material protective layer and other layers above) above the two-dimensional material protective layer 3400 is also relatively simple, so the manufacturing difficulty of the suspended super surface structure can be reduced. Moreover, compared with the bonding process, the product yield of the two-dimensional material transfer technology is higher. Therefore, the optical element 3000 provided in the embodiment of the present application can also improve product yield and reduce manufacturing costs.

[0089] Since the optical element 3000 provided in the embodiment of the present application does not require a bonding process for connection, the preparation environment does not require high temperature, and there is no need to consider the matching of thermal stress coefficients between different layers of materials; and, the surface of the two-dimensional material has no dangling bonds, and the materials of adjacent layers (such as the two-dimensional material protective layer 3400 and the supersurface layer 3200) are connected by van der Waals forces, so there is no need to consider the lattice constant matching between different layers of materials.

[0090] That is to say, the optical element 3000 provided in the embodiment of the present application relaxes the restrictions on the matching of thermal stress coefficients and lattice constants between different layers of materials, thereby expanding the range of material selection. Thus, more functions and better effects can be achieved through new materials or new material combinations (i.e., materials or material combinations that were previously limited by the high temperature environment of the bonding process and could not be used). In addition, since the preparation process does not require high temperature, damage to active devices caused by high temperature can be avoided.

[0091] In some optional implementations, the material of the two-dimensional material layer 3300 may include at least one of the following: graphene, molybdenum disulfide, tungsten disulfide, and molybdenum telluride.

[0092] Materials such as graphene, molybdenum disulfide, tungsten disulfide and molybdenum telluride have the characteristics of high strength, large band gap (for example, greater than or equal to 1 volt), large-area growth, etc. The present application embodiment uses these materials as materials for the two-dimensional material layer 3300, which has the following advantages:

[0093] Due to the high strength of these materials, they can better support the upper structure (such as the two-dimensional material protection layer 3400 and the upper structure), thereby improving the stability of the cavity structure.

[0094] Since these materials have large band gaps, more light energy in the communication band can be reflected and transmitted by the two-dimensional material layer 3300. Therefore, the two-dimensional material layer 3300 has low absorption and high transparency to light in the communication band, which makes the optical performance of the optical element 3000 better. The optical element 3000 can be used as a high-performance reflection, modulation and other element in communication equipment.

[0095] Since these materials can be grown over a large area, the area of ​​the two-dimensional material layer 3300 is large enough to be compatible with the mainstream product size. For example, the mainstream optical chip size is 8 inches or 12 inches. Only by using the above materials that can be grown over a large area can the two-dimensional material layer 3300 be made into an area of ​​8 inches or 12 inches to adapt to the mainstream chip size. Optionally, the above materials that can be grown over a large area can also be adapted to other product sizes, which is not limited in this application.

[0096] Optionally, in addition to the above materials, other transition metal sulfide compounds with the characteristics of high strength, large band gap and large-area growth can also be used as the material of the two-dimensional material layer 3300 to obtain the above advantages.

[0097] Optionally, the band gap of the material of the two-dimensional material protection layer 3400 may also be greater than or equal to 1 volt to reduce the absorption of light in the communication band by the two-dimensional material protection layer 3400, so that the optical performance of the optical element 3000 is better.

[0098] In the embodiment of the present application, the thickness of the two-dimensional material layer 3300 is d1, 0.3nm≤d1≤100nm. In some optional implementations, d1≤20nm.

[0099] In the embodiment of the present application, the material of the two-dimensional material layer 3300 may absorb optical signals in certain communication bands (e.g., 1060 nm band). Reducing the thickness of the two-dimensional material layer 3300 to less than or equal to 20 nm can reduce the absorption degree of the two-dimensional material layer 3300 on optical signals in these communication bands, thereby improving the performance of the optical element 3000.

[0100] Optionally, the thickness d1 of the two-dimensional material layer 3300 may be 5 nm, 6 nm, 10 nm, 12 nm, 15 nm, 18 nm, etc., which is not limited in the present application.

[0101] In some optional implementations, the thickness d2 of the dielectric unit 3210 may be in the range of 50 nm ≤ d2 ≤ 3000 nm.

[0102] The wavelength range of visible light is 390nm-780nm, the wavelength range of infrared is above 760nm, the commonly used wavelength of optical communication is 1550nm (1260nm-1675nm), and the wavelength range of mid-infrared is 3000nm-5000nm. In the embodiment of the present application, the thickness d2 of the dielectric unit 3210 is limited to 50nm≤d2≤3000nm, so that the thickness of the dielectric unit 3210 is near one-third of the target wavelength, and the optical element 3000 can be used as a sub-wavelength optical device of the target wavelength (wavelength range is 150nm-10000nm). Sub-wavelength optical devices only have zero-order reflection and diffraction for the incident light (of the target wavelength), which can achieve functions such as suppressing high-order modes and polarization selection. Therefore, it is used in scenes such as wide-spectrum high-reflection and high-pulse ratio lasers, hollow waveguide structures, slow light effect crystals, and femtosecond laser frequency modulation.

[0103] In the embodiment of the present application, the thickness of the two-dimensional material layer 3300 can be increased to make the two-dimensional material layer 3300 less prone to damage, so that there is no need to set other structures above the two-dimensional material layer 3300 to protect the two-dimensional material layer 3300. The specific structure is as follows Figure 5 As shown. The adjacent dielectric units 3210 in the super surface layer 3200, the upper surface of the substrate layer 3100 and the lower surface of the two-dimensional material layer 3300 form a cavity, and the two-dimensional material layer 3300 serves as a support structure above the cavity to ensure the structural stability of the cavity. In this structure, the band gap of the two-dimensional material layer 3300 is greater than or equal to 1 volt, and the thickness d1 is greater than or equal to 1 nm.

[0104] In the embodiment of the present application, a two-dimensional material layer 3300 is covered on the super surface layer 3200 as a support structure of the cavity. Since the band gap of the two-dimensional material layer 3300 is greater than or equal to 1 volt, the light energy of the communication band can be reflected and transmitted by the two-dimensional material layer 3300, so that the two-dimensional material layer 3300 has a small degree of light absorption of the communication band, and the optical element 3000 can have good optical properties. Since the thickness of the two-dimensional material layer 3300 is greater than or equal to 1nm, it is not easy to be damaged, and there is no need to set other structures on the two-dimensional material layer 3300 to protect the two-dimensional material layer 3300, and the structure is simple.

[0105] In an optional implementation, the material of the two-dimensional material layer 3300 includes molybdenum disulfide. It is worth noting that, in addition to molybdenum disulfide, the material of the two-dimensional material protection layer 3300 can also be changed to other two-dimensional materials with larger band gaps, thereby increasing the thickness of the two-dimensional material protection layer 3300, which is not limited in this application.

[0106] In the embodiment of the present application, the shape of the dielectric unit 3210 in the super surface layer 3200 is not limited.

[0107] Optionally, the medium unit 3210 may be Figure 6 The long prism shown, Figure 7 The prism-shaped structures shown are regular quadrangular prisms (or other prism structures, such as cuboids, rhombus prisms, etc.) etc. The optical element 3000 based on the dielectric unit 3210 structure can be used as some photonic crystal devices, such as slow light crystals.

[0108] Optionally, the medium unit 3210 may be Figure 6 As shown in FIG. 1 , the upper surface of the substrate layer 3100 is arranged in one dimension, or as shown in FIG. Figures 7 to 9 As shown, they are arranged in two dimensions on the upper surface of the substrate layer 3100, but this application does not limit this.

[0109] Optionally, the medium unit 3210 may be Figure 8 The optical element 3000 based on the dielectric unit 3210 structure can be used as some photonic crystal devices, such as polarization optical devices, planar optical devices, etc., which is not limited in the present application.

[0110] Optionally, the medium unit 3210 may be Fig. 9 The optical element 3000 based on the dielectric unit 3210 structure can be used as some photonic crystal devices, such as polarization optical devices, planar optical devices, etc., which is not limited in this application.

[0111] Optionally, the medium unit 3210 may also be a T-shaped column, etc., which is not limited in the present application.

[0112] The present application also provides an optical device, which includes a light-conducting element and Figures 3 to 9 The optical element 3000 of any embodiment of the present invention is used for transmitting the optical signal to the optical element 3000, and the optical element 3000 is used for realizing reflection, modulation or transmission of the optical signal.

[0113] Optionally, the optical device may be a light emitting chip, a light receiving chip, a light modulating chip, a liquid crystal on silicon (LCOS) chip, a micro-electromechanical system (MEMS), etc., which is not limited in the present application.

[0114] In some optical devices, a reflective layer is required to reflect a light beam of a target wavelength. Fig.10 The modulator shown uses the bottom Al electrode as a reflective layer. The reflectivity of the Al layer in the 1550 band (i.e., the target wavelength) is 95%-98%, resulting in loss of the target wavelength light beam. There is a certain gap between the Al electrodes, and the duty cycle formed by the gap (for example, 90%) will also cause loss of the target wavelength light beam. In addition, the refractive index of the SiO2 layer and the SiN layer above the Al electrode is different, which also introduces diffraction loss (about 5% for a pair of adjacent interfaces). In summary, the overall optical insertion loss of the modulator is approximately 1-0.95*0.95*0.98*0.9=20.4%.

[0115] If the optical element 3000 provided in the embodiment of the present application is added Fig.10 The SiN layer and the liquid crystal layer in the grating serve as the reflective layer of the modulator. Due to the optical design of the optical element 3000, by adjusting the thickness, period, duty cycle and other parameters of the grating, a reflectivity of nearly 100% for the target wavelength light beam can be achieved. Fig.10 The original product shown (for example, the GAEA-2 4K LCOS SLM model product of Holoeye, USA) has an overall optical intensity loss of nearly 28% in the 1550nm band due to the filling coefficient between small pixels and the optical diffraction between pixel electrodes. By adding the optical element 3000 provided in the embodiment of the present application, the incident light no longer enters the underlying Al layer, thereby causing optical intensity loss. Under the same conditions, the reflectivity of the target wavelength of the modulator can be increased to nearly 100%, and the overall optical intensity loss is reduced to about 0%.

[0116] As described above, the optical element 3000 provided in the embodiment of the present application can achieve a reflectivity of nearly 100%, so it can be used as a reflective layer in various optical devices. In addition to being used in the modulator as described in the above embodiment, it can also be used in optical switching engines, on-chip light sources, holographic projections (such as augmented reality (AR), virtual reality technology (VR)), hollow core waveguides and other optical devices that require wide-spectrum reflection functions, as well as high-power femtosecond lasers, supercontinuum lasers and other fields, and this application does not limit this.

[0117] Optionally, the optical element 3000 provided in the embodiment of the present application can also realize modulation of optical signals through the metasurface layer 3200, and thus can be applied to optical devices in scenarios such as pulse width modulation and photonic crystals.

[0118] Optionally, the optical element 3000 provided in the embodiment of the present application can also conduct signals of a specific wavelength, and thus can be used as a waveguide structure.

[0119] In some scenarios (such as single-mode laser, photonic crystal fiber technology, femtosecond laser, etc.), the output pulse width and output power of the laser are very important indicators. The optical element 3000 and the corresponding optical device provided in the embodiment of the present application are applied in these scenarios. Since the optical element 3000 is a suspended structure, the quality factor Q value of the optical element 3000 is higher, and a narrower laser output pulse width can be achieved, thereby achieving a smaller noise floor and a higher laser pulse ratio. For example Fig.11 represents the pulse ratio of the optical element 3000 provided in the embodiment of the present application. The horizontal axis is the wavelength, and the vertical axis is the normalized intensity obtained by performing intensity normalization processing on the light intensity. Fig.11 It can be seen that the optical element 3000 provided in the embodiment of the present application can increase the pulse ratio from the conventional nm level to the pm level.

[0120] The embodiment of the present application also provides an optical communication device, which includes an interface and the above-mentioned optical device, wherein the interface is used to connect an optical fiber and transmit an optical signal from the optical fiber to the above-mentioned optical device.

[0121] The embodiment of the present application further provides a light display device, which includes a light source and the above-mentioned optical device, wherein the light source is used to emit target light, and the target light is transmitted to the above-mentioned optical device.

[0122] Optionally, the target light may be natural light, full-color light, full-polarized light, etc., which is not limited in the present application. The optical device may conduct and modulate the target light, thereby obtaining display light of the optical display device.

[0123] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0124] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0125] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0126] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0127] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk and other media that can store program code.

Claims

1. An optical element, characterized in that: include: A substrate layer, a supersurface layer, a two-dimensional material layer, and a two-dimensional material protection layer are arranged in sequence from bottom to top; The super surface layer includes dielectric units periodically arranged on the upper surface of the substrate layer; The two-dimensional material layer covers the super surface layer, the adjacent dielectric units in the periodically arranged dielectric units, the upper surface of the substrate layer and the lower surface of the two-dimensional material layer form a cavity, and the two-dimensional material layer serves as a supporting structure above the cavity to ensure the structural stability of the cavity; The two-dimensional material protection layer is grown on the two-dimensional material layer to prevent the two-dimensional material layer from being damaged.

2. The optical element according to claim 1, characterized in that The material of the two-dimensional material layer includes at least one of the following: graphene, hexagonal boron nitride and layered transition metal chalcogenide; Among them, the composition formula of the layered transition metal chalcogenide compound is AB, A includes at least one of Zr, Hf, V, Nb, Ta, Mo, W, Pd, and Pt, and B includes at least one of S, Se, and Te.

3. The optical element according to claim 2, characterized in that The material of the two-dimensional material layer includes at least one of the following: Graphene, molybdenum disulfide, tungsten disulfide, and molybdenum telluride.

4. The optical element according to any one of claims 1 to 3, characterized in that The thickness of the two-dimensional material layer is d1, 0.3nm≤d1≤100nm.

5. The optical element according to claim 4, characterized in that 0.3nm≤d1≤20nm.

6. The optical element according to any one of claims 1 to 5, characterized in that The material of the two-dimensional material protection layer includes at least one of the following: metal, semiconductor material and oxide.

7. The optical element according to claim 6, characterized in that The band gap of the material of the two-dimensional material protection layer is greater than or equal to 1 resistive volt.

8. The optical element according to any one of claims 1 to 7, characterized in that The shape of the medium unit includes at least one of the following: Prism, cylinder, elliptical column, mesh, T-shaped column.

9. The optical element according to claim 8, characterized in that The dielectric units are arranged one-dimensionally or two-dimensionally on the plane.

10. The optical element according to any one of claims 1 to 9, characterized in that: The thickness of the dielectric unit is d2, 10nm≤d2≤10000nm.

11. The optical element according to claim 10, characterized in that 50nm≤d2≤3000nm.

12. The optical element according to any one of claims 1 to 11, characterized in that The material of the dielectric unit includes at least one of the following: metal, semiconductor material and oxide.

13. The optical element according to any one of claims 1 to 12, characterized in that The distance between the upper surface of the two-dimensional material layer and the lower surface of the super surface layer is r, 0.2nm≤r≤5nm.

14. An optical element, characterized in that: include: The substrate layer, the supersurface layer, and the two-dimensional material layer are arranged in order from bottom to top; The super surface layer includes dielectric units periodically arranged on the upper surface of the substrate layer; The two-dimensional material layer covers the super surface layer, the adjacent dielectric units in the periodically arranged dielectric units, the upper surface of the substrate layer and the lower surface of the two-dimensional material layer form a cavity, and the two-dimensional material layer serves as a supporting structure above the cavity to ensure the structural stability of the cavity; The band gap of the two-dimensional material layer is greater than or equal to 1 ohm volt, and the thickness is greater than or equal to 1 nm.

15. The optical element according to claim 14, characterized in that The material of the two-dimensional material layer includes molybdenum disulfide.

16. An optical device, characterized in that: comprising a light-conducting element and an optical element as claimed in any one of claims 1 to 15; The light-conducting element is used to conduct the light signal to the optical element, and the optical element is used to reflect, modulate or conduct the light signal.

17. The optical device according to claim 16, characterized in that: The optical device is at least one of the following: Light transmitting chips, light receiving chips, light modulating chips, liquid crystal on silicon (LCOS) chips and micro-electromechanical systems (MEMS).

18. An optical communication device, characterized in that: An optical device comprising an interface and claim 16 or 17; The interface is used to connect to an optical fiber and transmit an optical signal from the optical fiber to the optical device.

19. An optical display device, characterized in that: comprising a light source and the optical device according to claim 16 or 17; The light source is used to emit target light, and the target light is transmitted to the optical device.

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