Patent Application
20230221462
This application claims priority to Chinese Patent Application No. 202220088595.0, filed on Jan. 13, 2022, the entire content of which is incorporated herein by reference.
The present disclosure relates to the technical field of metasurface technologies and, in particular, to metasurface optical device with tilted nano-structure units and optical apparatus.
Metasurface refers to an artificial two-dimensional material with the sizes of basic structure units smaller than the working wavelengths and in the order of nanometers in the near-infrared and visible band. Metasurface can realize flexible and effective control of the characteristics, such as polarization, amplitude, phase, propagation direction and mode, etc., of electromagnetic waves.
Metasurface is ultra-light, ultra-thin and multifunctional optical device. Compared with conventional optical devices, a metasurface optical device manufactured based on semiconductor technology has the advantages of excellent optical performance, small size, and high integration. Metasurface optical devices can be widely used in future portable and miniaturized devices, such as augmented reality wearable devices, virtual reality wearable devices, and mobile terminal lenses.
One aspect of the present disclosure provides a metasurface optical device. The metasurface optical device includes a substrate and a nano-structure layer disposed on the substrate. The nano-structure layer includes a plurality of nano-structure units. The plurality of nano-structure units extend in a direction away from the substrate, and central axes of the plurality of nano-structure units form corresponding angles with respect to a normal direction of the substrate, such that the plurality of nano-structure units are arranged obliquely relative to the substrate.
Another aspect of the present disclosure provides an optical apparatus. The optical apparatus includes a metasurface optical device. The metasurface optical device includes a substrate and a nano-structure layer disposed on the substrate. The nano-structure layer includes a plurality of nano-structure units. The plurality of nano-structure units extend in a direction away from the substrate, and central axes of the plurality of nano-structure units form corresponding angles with respect to a normal direction of the substrate, such that the plurality of nano-structure units are arranged obliquely relative to the substrate.
In the following, some example embodiments are described. As those skilled in the art would recognize, the described embodiments can be modified in various different manners, all without departing from the spirit or scope of the present disclosure. Accordingly, the drawings and descriptions are illustrative in nature and not limiting.
In the present disclosure, terms such as “first,” “second,” and “third” can be used to describe various elements, components, regions, layers, and/or parts. However, these elements, components, regions, layers, and/or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or part from another element, component, region, layer, or layer. Therefore, a first element, component, region, layer, or part discussed below can also be referred to as a second element, component, region, layer, or part, which does not constitute a departure from the teachings of the present disclosure.
A term specifying a relative spatial relationship, such as “below,” “beneath,” “lower,” “under,” “above,” or “higher,” can be used in the disclosure to describe the relationship of one or more elements or features relative to other one or more elements or features as illustrated in the drawings. These relative spatial terms are intended to also encompass different orientations of the device in use or operation in addition to the orientation shown in the drawings. For example, if the device in a drawing is turned over, an element described as “beneath,” “below,” or “under” another element or feature would then be “above” the other element or feature. Therefore, an example term such as “beneath” or “under” can encompass both above and below. Further, a term such as “before,” “in front of,” “after,” or “subsequently” can similarly be used, for example, to indicate the order in which light passes through the elements. A device can be oriented otherwise (e.g., being rotated by 90 degrees or being at another orientation) while the relative spatial terms used herein still apply. In addition, when a layer is referred to as being “between” two layers, it can be the only layer between the two layers, or there can be one or more intervening layers.
Terminology used in the disclosure is for the purpose of describing the embodiments only and is not intended to limit the present disclosure. As used herein, the terms “a,” “an,” and “the” in the singular form are intended to also include the plural form, unless the context clearly indicates otherwise. Terms such as “comprising” and/or “including” specify the presence of stated features, entities, steps, operations, elements, and/or parts, but do not exclude the existence or addition of one or more other features, integers, steps, operations, elements, parts, and/or combinations thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the listed items. The phrases “at least one of A and B” and “at least one of A or B” mean only A, only B, or both A and B.
When an element or layer is referred to as being “on,” “connected to,” “coupled to,” or “adjacent to” another element or layer, the element or layer can be directly on, directly connected to, directly coupled to, or directly adjacent to the other element or layer, or there can be one or more intervening elements or layers. In contrast, when an element or layer is referred to as being “directly on,” “directly connected to,” “directly coupled to,” or “directly adjacent to” another element or layer, then there is no intervening element or layer. “On” or “directly on” should not be interpreted as requiring that one layer completely covers the underlying layer.
In the disclosure, description is made with reference to schematic illustrations of example embodiments (and intermediate structures). As such, changes of the illustrated shapes, for example, as a result of manufacturing techniques and/or tolerances, can be expected. Thus, embodiments of the present disclosure should not be interpreted as being limited to the specific shapes of regions illustrated in the drawings, but are to include deviations in shapes that result, for example, from manufacturing. Therefore, the regions illustrated in the drawings are schematic and their shapes are not intended to illustrate the actual shapes of the regions of the device and are not intended to limit the scope of the present disclosure.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this disclosure belongs. Terms such as those defined in commonly used dictionaries should be interpreted to have meanings consistent with their meanings in the relevant field and/or in the context of this disclosure, unless expressly defined otherwise herein.
As used herein, the term “substrate” can refer to the substrate of a diced wafer, or the substrate of an un-diced wafer. Similarly, the terms “chip” and “die” can be used interchangeably, unless such interchange would cause conflict. The term “layer” can include a thin film, and should not be interpreted to indicate a vertical or horizontal thickness, unless otherwise specified.
As shown in
The operation principle of the metasurface optical device 100 is as follows. When an incident light 108 enters the metasurface optical device, part of the light enters the plurality of nano-structure units 104 through the substrate 102, and another part of the light enters the dielectric protection material 106 through the substrate 102. Since the refractive index of the material of the plurality of nano-structure units 104 is greater than the refractive index of the dielectric protection material 106, the light entering the plurality of nano-structure units 104 mainly propagates inside the plurality of nano-structure units 104, and is modulated locally by different effective refractive indices. The light not entering the plurality of nano-structure units 104 passes directly through the dielectric protection material 106. In this way, the metasurface optical device 100 locally modulates the incident light 108 through the plurality of nano-structure units 104 with different effective refractive indices, and changes the properties, such as polarization, amplitude, phase, polarization mode, propagation direction, and propagation mode, of the incident light 108. As shown in
As shown in
However, some metasurface optical devices may have low transmission efficiency and low reflection efficiency, resulting in a substantial energy loss of the incident light. Further, some tilted gratings may perform only a single function, i.e., changing the propagation direction of the incident light.
The present disclosure provides a metasurface optical device and an optical apparatus including the metasurface optical device. In the metasurface optical device, a central axis of each of a plurality of nanostructure units on the substrate forms a certain angle with respect to a normal direction of the substrate, such that the plurality of nano-structure units are arranged obliquely relative to the substrate. Since the metasurface optical device consistent with the disclosure combines the advantages of versatile functions of metasurface optical devices and high transmission efficiency of tilted gratings, the metasurface optical device consistent with the disclosure can flexibly and effectively control and adjust the properties, such as phase, amplitude, polarization mode, propagation direction, and propagation mode, of the incident light, and at the same time, can improve the transmission efficiency or the reflection efficiency of the incident light.
In some embodiments, the metasurface optical device includes a substrate and a nano-structure layer on the substrate. The nano-structure layer includes a plurality of nano-structure units. The plurality of nano-structure units extend in a direction away from the substrate, and the central axes of the plurality of nano-structure units form corresponding angles with respect to the normal direction of the substrate, such that the plurality of nano-structure units are arranged obliquely relative to the substrate.
As shown in
In some embodiments, types of material of the substrate are not limited. For example, the substrate may include any one of glass, quartz, polymer, germanium, and plastic. Types of material of the nano-structure layer are not limited. For example, the nano-structure layer may include at least one of single crystal silicon, polycrystalline silicon, amorphous silicon, silicon carbide, titanium dioxide, silicon nitride, germanium, hafnium dioxide, or group III-V compounds. Among them, the group III-V compounds are compounds formed by boron, aluminum, gallium, or indium of group III, and nitrogen, phosphorus, arsenic, or antimony of group V in the periodic table of elements, such as gallium phosphide, gallium nitride, gallium arsenide, indium phosphide, etc.
In embodiments of the disclosure, a shape of the substrate is not limited. For example, the shape of the substrate may be a regular shape such as a circle, a square, a rectangle, a polygon, or the like. In some other examples, the shape of the substrate may be irregular. The shape of the substrate can be designed based on specific applications of the metasurface optical device.
In some embodiments, the obliquely arranged plurality of nano-structure units may be arranged in a regular manner on the substrate, such as an array arrangement, a circular arrangement, a triangular arrangement, a hexagonal arrangement, and the like. In some other embodiments, the obliquely arranged plurality of nano-structure units may be arranged in an irregular manner on the substrate, such as randomly arranged.
In some embodiments, the obliquely arranged plurality of nano-structure units may be arranged at a constant period on the substrate. As shown in
In some embodiments, the obliquely arranged plurality of nano-structure units may be arranged at non-constant periods on the substrate. Referring to
In some embodiments, the nano-structure layer includes a plurality of functional regions. Each functional region includes a corresponding subset of the plurality of nano-structure units. The plurality of nano-structure units are arranged such that the plurality of functional regions have different optical functions.
Referring again to
In the specification, phrases like “parameters B of a plurality of A's are not identical” mean that the plurality of A's are intentionally designed such that the parameters B of the plurality of A's formed by the manufacturing process are not all the same. Thus, these parameters B that are not all the same should not be interpreted as the result of errors in the manufacturing process, and vice versa. For example, “the dimensions of the plurality of nano-structure units in the direction perpendicular to the substrate are not completely same” means that the plurality of nano-structure units are designed in a way that their vertical dimensions are not all the same, and the difference in the vertical dimensions is not due to manufacturing process errors or measurement errors.
In some embodiments, different functional regions are different in at least one of the following aspects: angles between the central axes of the plurality of nano-structure units and the normal direction of the substrate; shapes of the orthogonal projections of the plurality of nano-structure units on the substrate; dimensions of the orthogonal projections of the plurality of nano-structure units on the substrate; dimensions of the orthogonal projections of the plurality of nano-structure units on the direction perpendicular to the substrate; arrangement periodicities of the plurality of nano-structure units on the substrate; arrangement patterns of the plurality of nano-structure units on the substrate; the orientations of the orthogonal projections of the plurality of nano-structure units on the substrate; or materials of the plurality of nano-structure units. Different functions in different regions may be configured flexibly and conveniently by adjusting the above parameters.
Structures and characteristics of nano-structure units in different functional regions will be further described below with reference to
In some embodiments, angles of the central axes of the nano-structure units in different functional regions relative to the normal direction of the substrate are different, that is, tilt angles of the nano-structure units are different. A tilt angle of a nano-structure unit is described with reference to
In some embodiments, the orthogonal projections of the plurality of nano-structure units in different functional regions on the substrate may have different shapes. Referring back to
In some embodiments, the orthogonal projections of the plurality of nano-structure units in different functional regions on the substrate may have different dimensions. As shown in
In some embodiments, the plurality of nano-structure units in different functional regions may have different dimensions in the direction perpendicular to the substrate. As shown in
In some embodiments, the plurality of nano-structure units in different functional regions on the substrate may have different periodicities. In one example, the plurality of nano-structure units in one region may be arranged periodically on the substrate, while the plurality of nano-structure units in the other region may not be arranged periodically on the substrate, such as the plurality of nano-structure units in the first functional region 310 and the second functional region 320 in
In some embodiments, the plurality of nano-structure units in different functional regions on the substrate may have different arrangement patterns. For example, the arrangement pattern of the plurality of nano-structure units in one functional region may be one of a rectangular pattern, a triangular pattern, a rhombus pattern, a hexagonal pattern, and a random arrangement pattern, etc., and the arrangement pattern of the plurality of nano-structure units in another functional region may be another one of a rectangular pattern, a triangular pattern, a rhombus pattern, a hexagonal pattern, and a random arrangement pattern, etc.
In some embodiments, the orthogonal projections of the plurality of nano-structure units on the substrate in different functional regions may have different orientations. For example, the orthogonal projections of the plurality of nano-structure units in one functional region on the substrate may be at an angle relative to a certain reference direction, and the orthogonal projection of the plurality of nano-structure units in another functional region on the substrate may be at another angle relative to the above reference direction.
In some embodiments, the plurality of nano-structure units in different functional regions may be made of different materials. For example, the plurality of nano-structure units in one functional region may be made of one of single crystal silicon, polycrystalline silicon, amorphous silicon, silicon carbide, titanium dioxide, silicon nitride, germanium, hafnium dioxide, and group III-V compounds, etc., while the plurality of nano-structure units in another functional region may be made of another one of single crystal silicon, polycrystalline silicon, amorphous silicon, silicon carbide, titanium dioxide, silicon nitride, germanium, hafnium dioxide, and group III-V compounds, etc.
The following describes how different functional regions are configured with reference to
In some embodiments, for at least one functional region among a plurality of functional regions, the at least one functional region satisfies at least one of the following: angles of the central axes of the plurality of nano-structure units in the at least one functional region relative to the normal direction of the substrate are not completely same; shapes of the orthogonal projections of the plurality of nano-structure units in the at least one functional region on the substrate are not completely same; dimensions of the orthogonal projections of the plurality of nano-structure units in the at least one functional region on the substrate are not completely same; dimensions of the orthogonal projections of the plurality of nano-structure units in the at least one functional region on the direction perpendicular to the substrate are not completely same; arrangement periodicities of the plurality of nano-structure units in the at least one functional region on the substrate are not completely same; arrangement patterns of different subsets of the plurality of nano-structure units in the at least one functional region on the substrate are not completely same; orientations of the orthogonal projections of the plurality of nano-structure units in the at least one functional region on the substrate are not completely same; or materials of the plurality of nano-structure units in the at least one functional region are not completely same. By adjusting the above parameters, the function of the at least one functional region can be configured flexibly and conveniently.
In some embodiments, the angles of the central axes of the plurality of nano-structure units in one functional region relative to the normal direction of the substrate are not completely same, that is, the tilt angles of the plurality of nano-structure units are not completely same. Referring again to the third functional region 330 in
In some embodiments, the shapes of the orthogonal projections of the plurality of nano-structure units in a same functional region on the substrate may not be completely the same. Referring to the third functional region 330 in
In some embodiments, the dimensions of the orthogonal projections of the plurality of nano-structure units on the substrate in a same functional region may not be completely the same. Referring to the third functional region 330 in
In some embodiments, the dimensions of the plurality of nano-structure units in a same functional region in the direction perpendicular to the substrate may not be completely the same. Referring to the third functional region 330 in
In some embodiments, the arrangement periodicities of the plurality of nano-structure units in a same functional region on the substrate may be different. Referring to the third functional region 330 in
In some embodiments, the arrangement patterns of different subsets of the plurality of nano-structure units in a same functional region on the substrate may not be completely the same. For example, the arrangement pattern of one subset of the plurality of nano-structure units in one functional region may be one of a rectangular pattern, a triangular pattern, a rhombus pattern, a hexagonal pattern, and a random arrangement pattern, etc., and the arrangement pattern of another subset of the plurality of nano-structure units in the functional region may be another one of the rectangular pattern, the triangular pattern, the rhombus pattern, the hexagonal pattern, and the random arrangement pattern, etc.
In some embodiments, the orientations of the orthogonal projections of the plurality of nano-structure units in a same functional region on the substrate may not be completely the same. For example, the orthogonal projection of a subset of the plurality of nano-structure units in one functional region on the substrate may be at an angle relative to a certain reference direction, and the orthogonal projection of another subset of the plurality of nano-structure units in the functional region on the substrate may be at another angle relative to the above reference direction. Referring to the nano-structure unit 336 and the nano-structure unit 337 in the third functional region 330 in
In some embodiments, the materials of the plurality of nano-structure units in a same functional region may not be completely the same. For example, the material of a subset of the plurality of nano-structure units in one functional region on the substrate may be one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, silicon carbide, titanium dioxide, silicon nitride, germanium, hafnium dioxide, and group III-V compounds, etc. The material of another subset of the plurality of nano-structure units in the functional region may be another of monocrystalline silicon, polycrystalline silicon, amorphous silicon, silicon carbide, titanium dioxide, silicon nitride, germanium, hafnium dioxide, and group III-V compounds, etc.
In some embodiments, the shapes of the plurality of functional regions may not be completely the same, and/or the areas of the plurality of functional regions may not be completely the same. Referring to the first functional region 310, the second functional region 320, and the third functional region 330 in
In some embodiments, the plurality of functional regions are arranged in an array on the substrate, including but not limited to a rectangular array, a triangular array, a hexagonal array, and the like. In some other embodiments, the plurality of functional regions are sequentially arranged on the substrate along a circumferential direction of a circle. As shown in
In some embodiments, the plurality of nano-structure units may be nanopillars, i.e., columnar structures protruding from the substrate. In some other embodiments, the plurality of nano-structure units in a plurality of photonic crystal units may also be nanoholes, that is, a plurality of hole structures formed in a dielectric protection material. The plurality of hole structures may be filled with, for example, air.
In some embodiments, a surface of the substrate facing away from the nano-structure layer and/or a surface of the substrate facing toward the nano-structure layer may be covered with a reflective layer. In some embodiments, the reflective layer may completely cover one side of the substrate where the nano-structure units are arranged, and may be disposed between the plurality of nano-structure units and the substrate. In some other embodiments, the reflective layer may completely cover the other side of the substrate, that is, completely cover the side of the substrate where no nano-structure unit is arranged.
In the present disclosure, a type of the reflective layer is not limited. In some embodiments, the reflective layer may be one of a metal reflective layer, a dielectric reflective layer, and a metal-dielectric reflective layer with relatively high reflectivity. For example, the reflective layer is the metal reflective layer, and the material of the metal reflective layer may be a metal material with a large extinction coefficient, a high reflectivity, and stable optical properties, such as gold, silver, copper, chromium, platinum, aluminum, etc. In another example, the reflective layer is the dielectric reflective layer, and the material of the dielectric reflective layer is not limited. The reflective layer may include at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, silicon carbide, titanium dioxide, silicon nitride, germanium, hafnium dioxide, or group III-V compounds. Among them, the group III-V compounds are compounds formed by one or more of boron, aluminum, gallium, and indium of group III in the periodic table of elements, and one or more of nitrogen, phosphorus, arsenic, and antimony of group V in the periodic table of elements, such as gallium phosphide, gallium nitride, gallium arsenide, indium phosphide, etc. In another example, the reflective layer is the metal-dielectric reflective layer, that is, a dielectric layer is covered on the metal reflective layer for protection. The material of the dielectric protective layer may be a dielectric material such as silicon monoxide, magnesium fluoride, silicon dioxide, and aluminum oxide. By adding the reflective layer with high reflectivity, the metasurface optical device of the present disclosure can be used as a reflective component, reflecting back locally modulated light by the plurality of nano-structure units instead of letting the locally modulated light pass through the metasurface optical device.
In some other embodiments, the reflective layer may be a grating or a dielectric material layer. In this scenario, when a light enters the metasurface optical device in the present disclosure, the light is neither completely transmitted nor fully reflected. Rather, a portion of the light is transmitted through the metasurface optical device, and another portion of the light is reflected back. A ratio of transmitted portion of the light over the reflected portion of the light may be adjusted according to actual usage requirements. In one example, 80% of the light may be transmitted and 20% of the light may be reflected. In another example, 20% of the light may be transmitted and 80% of the light may be reflected. In another example, 50% of the light may be transmitted and 50% of the light may be reflected. When the reflective layer is a grating (the grating is surrounded by a dielectric material to flatten surfaces of the grating, and the reflective layer includes a multilayer grating), a refractive index of the grating, a refractive index of the material between adjacent layers of the grating, and a thickness of each layer of the grating, etc. may be changed to adjust the ratio of the transmitted portion of the light over the reflected portion of the light. When the reflective layer is a dielectric material layer, the ratio of the transmitted portion of the light over the reflected portion of the light may be adjusted by changing the material refractive index difference between the dielectric material layer and the substrate.
The present disclosure also provides an optical apparatus. As shown in
The specification provides many different embodiments or examples that can be used to implement the present disclosure. It should be understood that these different embodiments or examples are merely exemplary and are not intended to limit the scope of the present disclosure in any way. Those skilled in the art can conceive of various changes or substitutions based on the description in the specification of the present disclosure, and these should be covered within the scope of the present disclosure. Therefore, the scope of the present disclosure should be defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202220088595.0 | Jan 2022 | CN | national |
