CN113311522B - Optical asymmetric transmission structure and optical device - Google Patents
Optical asymmetric transmission structure and optical device Download PDFInfo
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- CN113311522B CN113311522B CN202110593145.7A CN202110593145A CN113311522B CN 113311522 B CN113311522 B CN 113311522B CN 202110593145 A CN202110593145 A CN 202110593145A CN 113311522 B CN113311522 B CN 113311522B
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- 229910052782 aluminium Inorganic materials 0.000 claims description 8
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 8
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Classifications
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- G—PHYSICS
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
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- G—PHYSICS
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/18—Diffraction gratings
- G02B5/1814—Diffraction gratings structurally combined with one or more further optical elements, e.g. lenses, mirrors, prisms or other diffraction gratings
- G02B5/1819—Plural gratings positioned on the same surface, e.g. array of gratings
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- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Diffracting Gratings Or Hologram Optical Elements (AREA)
- Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)
Abstract
The disclosure provides an optical asymmetric transmission structure and an optical device, which can solve the problems of lower optical asymmetric transmission efficiency and complex structure of the existing optical asymmetric transmission structure. The optical asymmetric transmission structure of the present disclosure includes: a first substrate and a plurality of grating units positioned on the first substrate; the grating unit includes: a metal layer; the thickness of the metal layer is less than or equal to 500 nanometers.
Description
Technical Field
The disclosure belongs to the technical field of optical devices, and in particular relates to an optical asymmetric transmission structure and an optical device.
Background
Asymmetric transmission of light (asymmetric light transmission, ALT) refers to the difference in transmittance measured when light is incident from both sides of the device, respectively. At present, the scheme for realizing asymmetric transmission of light is mainly based on optical nonreciprocal methods, such as magneto-optical effect, nonlinear optics, indirect interband photon transition, photoacoustic effect and the like. Optical non-reciprocity is an ideal solution because it enables the device to transmit any optical mode in one direction and filter the parallel-direction optical mode in the other direction with a polarizer.
However, the optical nonreciprocal scheme is not suitable for asymmetric transmission of natural light because of the requirement for polarization of the light itself, or the need for periodic modulation of the light, or the requirement for high light intensity. Secondly, most of the structures formed by adopting the optical nonreciprocal scheme are generally complex at present, are generally incompatible with the manufacturing process of the semiconductor device and the display panel due to the limitations of manufacturing materials and structures, have tiny structures, have high requirements on the processing progress, and further limit the compatibility of the structures with the manufacturing process of the semiconductor device and the display panel. Furthermore, structures formed using the current optical nonreciprocal schemes have difficulty in having a fairly broad bandwidth, with fewer devices operating in the visible band.
Disclosure of Invention
The present disclosure aims to solve at least one of the technical problems in the prior art, and provides an optical asymmetric transmission structure and an optical device.
In a first aspect, embodiments of the present disclosure provide an optical asymmetric transmission structure, including: a first substrate and a plurality of grating units positioned on the first substrate;
the grating unit includes: a metal layer; the thickness of the metal layer is less than or equal to 500 nanometers.
Optionally, the grating unit further comprises: a dielectric layer;
the dielectric layer is located between the first substrate and the metal layer.
Optionally, the orthographic projection of the metal layer on the first substrate at least partially overlaps with the orthographic projection of the dielectric layer on the first substrate.
Optionally, the orthographic projection of the metal layer on the first substrate falls within the orthographic projection of the dielectric layer on the first substrate.
Optionally, the center point of the metal layer is on the same line as the center point of the dielectric layer.
Optionally, the metal layer has a first bottom surface facing away from the first substrate and a second bottom surface opposite to the first bottom surface, and the dielectric layer has a third bottom surface facing away from the first substrate and a fourth bottom surface opposite to the third bottom surface;
the area of the first bottom surface is smaller than or equal to the area of the second bottom surface, the area of the second bottom surface is smaller than or equal to the area of the third bottom surface, and the area of the third bottom surface is smaller than or equal to the area of the fourth bottom surface.
Optionally, the metal layer further has a first side connected to both the first bottom surface and the second bottom surface, and the dielectric layer further has a second side connected to both the third bottom surface and the fourth bottom surface;
the first side surface is provided with a first side edge and a second side edge which are oppositely arranged along the direction perpendicular to the first substrate; the second side surface is provided with a third side edge and a fourth side edge which are oppositely arranged along the direction perpendicular to the first substrate;
the joint of the first side edge and the third side edge is in arc connection or linear connection;
the connection part of the second side edge and the fourth side edge is arc-shaped connection or straight line connection.
Optionally, the material of the metal layer includes: one or more of aluminum, silver, or gold; the material of the dielectric layer includes: silicon nitride.
Optionally, the plurality of grating units are arranged in a triangular lattice arrangement, a tetragonal lattice arrangement or a hexagonal lattice arrangement.
Optionally, the optical asymmetric transmission structure further includes: a second substrate arranged opposite to the first substrate, and an anisotropic material positioned between the first substrate and the second substrate;
the anisotropic material is filled between the grating units and the second substrate.
Optionally, the anisotropic material comprises: a liquid crystal material.
Optionally, the optical asymmetric transmission structure further includes: a first electrode layer and a second electrode layer disposed opposite to each other;
the first electrode layer is positioned between the first substrate and the dielectric layer;
the second electrode layer is positioned on one side of the second substrate close to the first substrate;
the liquid crystal material is filled between the first electrode layer and the second electrode layer.
Optionally, the optical asymmetric transmission structure further includes: an alignment layer;
the alignment layer is positioned on one side of the second electrode layer, which is away from the second substrate.
In a second aspect, embodiments of the present disclosure provide an optical device comprising an optical asymmetric transmission structure as provided above.
Drawings
FIG. 1 is a schematic diagram of an exemplary optical asymmetric transmission structure;
FIG. 2a is a schematic diagram of the optical asymmetric transmission structure shown in FIG. 1;
FIG. 2b is a schematic diagram of the light asymmetric transmission structure shown in FIG. 1 in a daytime environment;
FIG. 2c is a schematic diagram of the light asymmetric transmission structure shown in FIG. 1 in a night environment;
fig. 3 is a schematic structural diagram of an optical asymmetric transmission structure according to an embodiment of the disclosure;
fig. 4 is a schematic structural diagram of another optical asymmetric transmission structure according to an embodiment of the disclosure;
FIG. 5 is a schematic diagram of a grating unit in the optical asymmetric transmission structure shown in FIG. 4;
FIG. 6a is a schematic diagram of an arrangement of grating units;
FIG. 6b is a schematic diagram illustrating another arrangement of grating units;
FIG. 7 is a schematic diagram of another optical asymmetric transmission structure according to an embodiment of the disclosure;
FIG. 8 is a schematic diagram of transmittance of an optical asymmetric transmission structure according to an embodiment of the present disclosure when no electric field is applied;
FIG. 9 is a schematic diagram showing transmittance of an optical asymmetric transmission structure according to an embodiment of the present disclosure when an electric field is applied;
fig. 10 is a process flow diagram of a preparation process of an optical asymmetric transmission structure according to an embodiment of the disclosure.
Detailed Description
In order that those skilled in the art will better understand the technical solutions of the present disclosure, the present disclosure will be described in further detail with reference to the accompanying drawings and detailed description.
Unless defined otherwise, technical or scientific terms used in this disclosure should be given the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure belongs. The terms "first," "second," and the like, as used in this disclosure, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. Likewise, the terms "a," "an," or "the" and similar terms do not denote a limitation of quantity, but rather denote the presence of at least one. The word "comprising" or "comprises", and the like, means that elements or items preceding the word are included in the element or item listed after the word and equivalents thereof, but does not exclude other elements or items. The terms "connected" or "connected," and the like, are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", etc. are used merely to indicate relative positional relationships, which may also be changed when the absolute position of the object to be described is changed.
Fig. 1 is a schematic structural view of an exemplary optical asymmetric transmission structure, as shown in fig. 1, including: a substrate 101, a metal layer 102 on the substrate 101, and a protective layer 103 on a side of the metal layer 102 facing away from the substrate 101. The substrate 101 can be made of flexible materials or rigid materials, and mainly plays a role in supporting other film layers thereon; the metal layer 102 may be formed by an evaporation process, and the material thereof may be aluminum (Al); the protective layer 103 may be silicon dioxide (SiO 2 ) Is made to protect the metal layer 102 from oxidation of the metal layer 102. The surface of the metal layer 102 close to the protection layer 103 is smoother, has higher reflectivity, and the surface close to the substrate 101 is rougher, and has lower reflectivity. Fig. 2a is a schematic diagram of the optical asymmetric transmission structure shown in fig. 1, and as shown in fig. 2a, the optical asymmetric transmission structure may have a reflectivity of 70% and a transmittance of 20%. In practical applications, the metal layer 102 has a smooth surface facing outdoors and a rough surface facing indoors. As shown in fig. 2b, when the outdoor brightness is significantly higher than the indoor brightness, for example, in sunny days, the intensity of the outdoor light may be 200 nit (nit), the indoor light intensity is only 70nit, the intensity of the portion of the outdoor light reflected is 140nit, the intensity of the indoor light transmitted is only 14nit, and the intensity of the light reflected is significantly higher than that of the indoor lightThe intensity of the transmitted light is such that the reflected light completely masks the transmitted light intensity so that the user cannot see indoors when looking from outdoors to indoors. However, as shown in fig. 2c, when the outdoor brightness is lower than the indoor brightness, for example, at night, the intensity of the outdoor light is only 10nit, the intensity of the indoor light is 70nit, the intensity of the portion of the outdoor light reflected is only 7nit, the intensity of the indoor light transmitted is 10nit, the intensity of the light reflected by the outdoor light is substantially the same as the intensity of the light transmitted by the indoor light, so that the reflected light cannot completely mask the transmitted light intensity, and thus a good light asymmetric transmission effect cannot be achieved.
At present, the scheme for realizing asymmetric transmission of light is mainly based on optical nonreciprocal methods, such as magneto-optical effect, nonlinear optics, indirect interband photon transition, photoacoustic effect and the like. Optical non-reciprocity is an ideal solution because it enables the device to transmit any optical mode in one direction and filter the parallel-direction optical mode in the other direction with a polarizer. However, the optical nonreciprocal scheme is not suitable for asymmetric transmission of natural light because of the requirement for polarization of the light itself, or the need for periodic modulation of the light, or the requirement for high light intensity. Secondly, most of the structures formed by adopting the optical nonreciprocal scheme are generally complex at present, are generally incompatible with the manufacturing process of the semiconductor device and the display panel due to the limitations of manufacturing materials and structures, have tiny structures, have high requirements on the processing progress, and further limit the compatibility of the structures with the manufacturing process of the semiconductor device and the display panel. Furthermore, structures formed using the current optical nonreciprocal schemes have difficulty in having a fairly broad bandwidth, with fewer devices operating in the visible band.
In order to solve at least one of the above technical problems, an embodiment of the present disclosure provides an optical asymmetric transmission structure and an optical device, and the optical asymmetric transmission structure and the optical device provided by the embodiment of the present disclosure will be described in further detail below with reference to the accompanying drawings and detailed description.
In a first aspect, an embodiment of the present disclosure provides an optical asymmetric transmission structure, and fig. 3 is a schematic structural diagram of the optical asymmetric transmission structure provided in the embodiment of the present disclosure, as shown in fig. 3, where the optical asymmetric transmission structure includes: a first substrate 301 and a plurality of grating units 302 on the first substrate 301; the raster unit 302 includes: a metal layer 3021 (the metal layer 3021 is independent of the metal layer 102 shown in fig. 1); the thickness of the metal layer 3021 is less than or equal to 500 nanometers (nm).
The first substrate 301 may be made of a rigid material such as glass, and may effectively support other film layers thereon, and it may be appreciated that the first substrate 301 may also be made of a flexible material such as Polyimide (PI), and may effectively support other film layers, and may also avoid breakage of the whole optical asymmetric transmission structure during stretching and bending, so as to improve flexibility of the whole optical asymmetric transmission structure, and facilitate co-molding with other structures. In practical applications, the material of the first substrate 301 may be reasonably selected, which is not limited herein.
Here, the light is incident from the grating unit 302 and transmitted through the first substrate 301 to be defined as forward transmission, and the light is incident from the first substrate 301 and transmitted through the grating unit 302 to be defined as backward transmission. The metal layer 3021 in the plurality of grating units 302 has a thickness of less than or equal to 500nm, and may be arranged to form similar voids, and particularly when the voids are on the same order of magnitude as the wavelength of light, the metal layer 3021 in the grating units 302 may serve as a diffraction grating for light. When light is transmitted in the forward direction, bragg diffraction may occur when light is irradiated from the air to the metal layer 3021. At this time, a wave vector in a horizontal direction may be generated on the surface of the metal layer 3021, and may be coupled with the metal layer 3021 to form a surface plasmon (surface plasmon polaritons, SPP) mode, so that light may be effectively transmitted. When light is transmitted in the reverse direction, the light irradiates the metal layer 3021 from the first substrate 301, and has asymmetry when the light is transmitted in the forward direction, and a wave vector generated by the reverse direction cannot be coupled with the metal layer 3021 to form an SPP mode, so that the light cannot be transmitted effectively, and asymmetric transmission of the light is realized.
In the optical asymmetric transmission structure provided in the embodiment of the present disclosure, a plurality of grating units 302 formed by the metal layer 301 are disposed on the first substrate 301, and the grating units 301 may be used as diffraction gratings, so that bragg diffraction may occur when light is transmitted in forward direction and in reverse direction, so as to realize asymmetric transmission of light, so that the optical asymmetric transmission structure may not depend on optical polarization, and is suitable for asymmetric transmission of visible light in all bands, and meanwhile, shielding of light by using a polarizer is avoided, thereby ensuring effective transmittance of light. Furthermore, the structure of the optical asymmetric transmission structure provided by the embodiment is simpler, and the materials and the preparation process of the film layer and the materials and the preparation process of the semiconductor device and the display panel have better compatibility, so that the optical asymmetric transmission structure can be effectively integrated with the semiconductor device and the display panel, and the preparation and research cost can be saved.
Fig. 4 is a schematic structural diagram of another optical asymmetric transmission structure according to an embodiment of the disclosure, where the grating unit 302 further includes: dielectric layer 3022, dielectric layer 3022 being located between first substrate 301 and metal layer 3021.
When light is transmitted from the forward direction, the dielectric layer 3022 may form a waveguide mode while bragg diffraction is generated in the gap between the metal layers 3021, and the transmittance of the light may be further improved. When light is transmitted in the reverse direction, the dielectric layer and other film layers are not matched in refractive index, so that the light has an intense reflection effect, the transmittance of the light can be further reduced, and the asymmetric transmission effect of the light can be further improved.
Fig. 5 is a schematic structural diagram of a grating unit in the optical asymmetric transmission structure shown in fig. 4, and as shown in fig. 5, the front projection of the metal layer 3021 on the first substrate 301 at least partially overlaps with the front projection of the dielectric layer 3022 on the first substrate 301.
In practical applications, the metal layer 3021 and the dielectric layer 3022 may be stacked and at least partially overlapped, the dielectric layer 3022 may support the metal layer 3021, and when light is transmitted in the forward direction, most of the light may be irradiated to the metal layer 3021, so as to achieve bragg diffraction to a greater extent, and the dielectric layer 3022 may form a waveguide mode, so that the transmittance of the light may be further improved. When light is transmitted in the reverse direction, the dielectric layer 3022 can shield the light, so that most of the light irradiates the dielectric layer 3022, and the dielectric layer and other film layers have an intense reflection effect due to the mismatching of refractive indexes, so that the transmittance of the light can be further reduced, and the asymmetric transmission effect of the light can be further improved. The cross-sectional shapes of the metal layer 3021 and the dielectric layer 3022 in the direction parallel to the first substrate 301 may be circular, square, or other irregular shapes, and in the embodiment of the present disclosure, a circular shape will be described as an example, and when the cross-sectional shapes are other shapes, the principle thereof is similar thereto, and a description thereof will be omitted.
Further, as shown in fig. 5, the front projection of the metal layer 3021 on the first substrate 301 falls within the front projection of the dielectric layer 3022 on the first substrate 301.
The orthographic projection of the metal layer 3021 on the first substrate 301 falls into the orthographic projection of the dielectric layer 3022 on the first substrate 301, so that the dielectric layer 3022 can completely shield the metal layer, when light is transmitted in a reverse direction, the dielectric layer 3022 can shield the light, so that the light can completely irradiate the dielectric layer 3022, and the dielectric layer and other film layers have an alternating reflection effect due to the fact that the refractive indexes of the dielectric layer and the other film layers are not matched, the transmittance of the light can be further reduced, and the asymmetric transmission effect of the light can be further improved.
Further, as shown in fig. 5, the center point of the metal layer 3021 and the center point of the dielectric layer 3022 are located on the same line.
The center point of the metal layer 3021 and the center point of the dielectric layer 3022 are located on the same straight line, so that the preparation process is convenient, the preparation process difficulty is reduced, and the preparation cost is saved.
In some embodiments, as shown in fig. 5, the metal layer 3021 has a first bottom surface facing away from the first substrate 301 and a second bottom surface disposed opposite the first bottom surface, and the dielectric layer 3022 has a third bottom surface facing away from the first substrate 301 and a fourth bottom surface disposed opposite the third bottom surface; the area of the first bottom surface is smaller than or equal to the area of the second bottom surface, the area of the second bottom surface is smaller than or equal to the area of the third bottom surface, and the area of the third bottom surface is smaller than or equal to the area of the fourth bottom surface.
Generally, the more symmetry planes a structure possesses, the higher its symmetry, and the higher the symmetry structure can realize asymmetric transmission of natural light, compared with a structure with fewer symmetry planes, which can be called as a high-symmetry structure. In the embodiment of the present disclosure, the cross-sectional shapes of the metal layer 3021 and the dielectric layer 3022 along the direction parallel to the first substrate 301 may be circular, wherein the area of the first bottom surface is smaller than or equal to the area of the second bottom surface, the area of the second bottom surface is smaller than or equal to the area of the third bottom surface, and the area of the third bottom surface is smaller than or equal to the area of the fourth bottom surface, so that the grating unit 302 formed by the metal layer 3021 and the dielectric layer 3022 may form a circular truncated cone or a cylindrical shape. Because the cylindrical shape or the truncated cone shape has innumerable symmetry planes, the whole grating unit 302 in the embodiment of the disclosure has a high symmetry structure, so that natural light can be asymmetrically transmitted, and meanwhile, the ratio of the light transmittance of forward transmission to the light transmittance of reverse transmission is high, so that the asymmetric transmission efficiency of light can be effectively improved. It is understood that the cross-sectional shapes of the metal layer 3021 and the dielectric layer 3022 along the direction parallel to the first substrate 301 may also be square, polygonal, etc., and the number of symmetry planes thereof is significantly less than that of the cylindrical shape or the truncated cone shape, and therefore, in the embodiment of the present disclosure, the cross-sections of the metal layer 3021 and the dielectric layer 3022 along the direction parallel to the first substrate 301 may be circular.
In some embodiments, as shown in fig. 5, the metal layer 3021 further has a first side connected to both the first bottom surface and the second bottom surface, and the dielectric layer 3022 further has a second side connected to both the third bottom surface and the fourth bottom surface; the first side surface is provided with a first side edge and a second side edge which are oppositely arranged along the direction vertical to the first substrate; the second side surface is provided with a third side edge and a fourth side edge which are oppositely arranged along the direction vertical to the first substrate; the joint of the first side edge and the third side edge is in arc connection or linear connection; the connection between the second side and the fourth side is an arc connection (not shown) or a straight line connection.
It should be noted that, the connection between the metal layer 3021 and the dielectric layer 3022 may be arc connection or straight connection, and when light is transmitted in the forward direction, bragg diffraction may occur at the gap between the metal layers 3021, so as to ensure the transmittance of the light. When light is transmitted in the reverse direction, the refractive indexes of the dielectric layer 3022 and other film layers are not matched, so that the light can be reflected, and the asymmetric transmission efficiency of the light is improved. Preferably, in order to facilitate the preparation, the connection part of the two can be arranged to be in linear connection, so that the difficulty of the preparation process is reduced, and the preparation cost is saved.
In some embodiments, the material of metal layer 3021 comprises: one or more of aluminum, silver, or gold; the material of the dielectric layer 3022 includes: silicon nitride.
In practical applications, the metal layer 3021 may be made of a metal material or an alloy material, such as aluminum, silver, or gold, or an alloy including one or more of aluminum, silver, or gold, and may be a single-layer or multi-layer structure, such as a multi-metal layer stack, such as gold, aluminum, gold three-layer metal layer stack, or the like, and the dielectric layer 3022 may be made of an insulating material, such as silicon nitride. It is understood that the metal layer 3021 and the dielectric layer 3022 may be made of other materials, and the materials may be reasonably selected according to actual needs, which are not listed here.
In some embodiments, the plurality of grating elements 302 are in a triangular lattice arrangement, a tetragonal lattice arrangement, or a hexagonal lattice arrangement.
The arrangement of the plurality of grating units 302 may be varied, for example, a triangular lattice arrangement as shown in fig. 6a, a tetragonal lattice arrangement as shown in fig. 6b, or a hexagonal lattice arrangement (not shown). It is understood that other periodic arrangements of the grating elements 302 may be used, with periods of 300nm to 1000nm, to meet the conditions for bragg diffraction. The implementation principle is similar to that of the above arrangement, and will not be described in detail here. For ease of preparation, in the embodiments of the present disclosure and in the following description, a tetragonal lattice arrangement as shown in fig. 6b will be exemplified.
Fig. 7 is a schematic structural diagram of another optical asymmetric transmission structure according to an embodiment of the disclosure, where, as shown in fig. 7, the optical asymmetric transmission structure further includes: a second substrate 303 arranged opposite to the first substrate 301, and an anisotropic material 304 between the first substrate 301 and the second substrate 303; anisotropic material 304 fills between adjacent grating units 302 and between grating units 302 and second substrate 303.
The refractive index of the anisotropic material 304 has a certain difference along with the difference of the directions, that is, the direction of the anisotropic material 304 can be changed by changing the arrangement direction of the anisotropic material 304 by applying an external force, so as to change the refractive index thereof. The refractive index of the anisotropic material 304 is smaller than that of the dielectric layer 3022 in any direction, and when light is transmitted reversely, the direction of the anisotropic material 304 can be adjusted, so that the refractive index of the anisotropic material 304 is larger than that of the dielectric layer 3022, and the refractive index matching degree of the anisotropic material 304 and the dielectric layer 3022 is lower, thus the reflection effect of the light can be increased, and the transmittance of the light can be reduced. Alternatively, the direction of the anisotropic material may be adjusted so that the refractive index of the anisotropic material 304 is closer to the refractive index of the dielectric layer 3022, and the refractive index matching degree of the two is higher, so that the reflection effect of light can be reduced, and the transmittance of light can be improved, so that the light asymmetric transmission performance of the overall light asymmetric transmission structure is tunable.
In some embodiments, anisotropic material 304 includes: a liquid crystal material.
Specifically, the anisotropic material 304 may be a liquid crystal material, and the refractive index of the liquid crystal material is different in different deflection directions, for example, the refractive index of the liquid crystal material E7 is 1.74 when aligned perpendicular to the first substrate 301, and is 1.52 when aligned parallel to the first substrate 301. It will be appreciated that other materials of variable refractive index may be selected and are not listed herein.
In some embodiments, as shown in fig. 7, the optical asymmetric transmission structure further includes: a first electrode layer 305 and a second electrode layer 306 disposed opposite to each other; the first electrode layer 305 is located between the first substrate 301 and the dielectric layer 3022; the second electrode layer 306 is located on one side of the second substrate 303 close to the first substrate 301; the liquid crystal material is filled between the first electrode layer 305 and the second electrode layer 306.
In practical applications, the first electrode layer 305 and the second electrode layer 306 may apply different voltage signals, and an electric field is generated between them to drive the liquid crystal material between them to deflect, so that the liquid crystal material has different refractive indexes, so as to realize tunability of the optical asymmetric transmission performance of the overall optical asymmetric transmission structure.
In some embodiments, as shown in fig. 7, the optical asymmetric transmission structure further includes: an alignment layer 307; the alignment layer 307 is located on a side of the second electrode layer 306 facing away from the second substrate 303.
The alignment layer 307 may anchor the liquid crystal material such that the liquid crystal material is fixed at a certain initial angle when no electric field is applied, thereby avoiding light leakage caused by disordered liquid crystal arrangement. In practical applications, the alignment layer 307 may be made of Polyimide (PI).
The performance of the optical asymmetric transmission structure provided by the embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Specifically, in the optical asymmetric transmission structure, the grating unit 302 is in a truncated cone shape, and adopts a tetragonal lattice arrangement, wherein the dielectric layers 3022 are formed by silicon nitride, the diameter of the first bottom surface is 500nm, the diameter of the second bottom surface is 300nm, the thickness is 550nm, and the distance between adjacent dielectric layers 3022 is 600nm; the metal layer 3021 is formed using aluminum, the third bottom surface has a diameter of 300nm, the fourth bottom surface has a diameter of 200nm, the thickness of 125nm, the materials of the first substrate 301 and the second substrate 303 are glass, and the anisotropic material 304 is a liquid crystal material E7.
Fig. 8 is a schematic diagram of transmittance of the light asymmetric transmission structure provided in the embodiment of the disclosure when no electric field is applied, as shown in fig. 8, when no voltage is applied to both the first electrode layer 305 and the second electrode layer 306, the liquid crystal material E7 is arranged horizontally, and its refractive index is 1.52. When light is transmitted from the forward direction, the light transmittance of the whole light asymmetric transmission structure is about 0.7, and when light is transmitted from the reverse direction, the light transmittance of the whole light asymmetric transmission structure is about 0.2.
Fig. 9 is a schematic diagram of transmittance of the optical asymmetric transmission structure according to the embodiment of the disclosure when an electric field is applied, as shown in fig. 9, when voltages are applied to the first electrode layer 305 and the second electrode layer 306, the liquid crystal material E7 is vertically arranged, and its refractive index is 1.74. When light is transmitted from the forward direction, the light transmittance of the whole light asymmetric transmission structure is about 0.7, and when light is transmitted from the reverse direction, the light transmittance of the whole light asymmetric transmission structure is about 0.4. It can be seen that, due to the effect of the liquid crystal material E7, when light is transmitted in a reverse direction, the light transmittance of the whole optical asymmetric transmission structure can be adjusted between 0.2 and 0.4, so as to realize tunability of the optical asymmetric transmission performance of the whole optical asymmetric transmission structure.
The following will illustrate a process for preparing an optical asymmetric transmission structure according to an embodiment of the present disclosure with reference to the accompanying drawings. Fig. 10 is a flowchart of a process for preparing an optical asymmetric transmission structure according to an embodiment of the disclosure, as shown in fig. 10 and fig. 7, where the process for preparing an optical asymmetric transmission structure includes the following steps:
s1, depositing a layer of ITO on a first substrate 301 by adopting a sputtering process to form a first electrode layer 305, wherein the first substrate 301 can be glass.
S2, forming two sacrificial layers on the first electrode layer 305 by adopting a spin coating process;
s3, etching the corresponding positions of the sacrificial layer through an etching process to form a containing part capable of containing the grating unit 302;
s4, forming a dielectric layer 3022 and a metal layer 3021 on the sacrificial layer and in the accommodating portion by adopting a vapor deposition and sputtering process, and stripping off the redundant dielectric layer 3022 and metal layer 3021 and the sacrificial layer to form the grating unit 302;
s5, depositing a layer of ITO on the second substrate 303 by adopting a sputtering process to form a second electrode layer 306, wherein the second substrate 303 can be glass.
S6, forming a phase matching layer 307 on the second electrode layer 306 by adopting a spin coating process.
S7, two parts are formed through S4 and S6 to be attached to the box, and anisotropic material 304, such as liquid crystal material, is filled in the box. Thus, a complete optical asymmetric transmission structure as shown in fig. 7 is formed.
According to the preparation process flow of the optical asymmetric transmission structure, the optical asymmetric transmission structure provided by the embodiment of the disclosure has a simple structure, the preparation process can be completely compatible with the preparation process of the semiconductor device and the display panel, and the existing process for preparing the semiconductor device or the display panel can be adopted for preparation, so that the optical asymmetric transmission device is convenient to integrate with the semiconductor device and the display panel, and the preparation and research and development costs can be saved.
In a second aspect, embodiments of the present disclosure provide an optical device comprising an optical asymmetric transmission structure as provided above. The optical device can be applied to scenes such as glass of buildings, automobiles and trains, and the like, and can realize asymmetric transmission of light. The implementation principle and technical effect of the optical device may refer to the above discussion of the technical effect of the display panel, and will not be repeated herein.
It is to be understood that the above embodiments are merely exemplary embodiments employed to illustrate the principles of the present disclosure, however, the present disclosure is not limited thereto. Various modifications and improvements may be made by those skilled in the art without departing from the spirit and substance of the disclosure, and are also considered to be within the scope of the disclosure.
Claims (11)
1. An optical asymmetric transmission structure, comprising: a first substrate and a plurality of grating units positioned on the first substrate;
the grating unit includes: a metal layer; the thickness of the metal layer is less than or equal to 500 nanometers;
the grating unit further includes: a dielectric layer;
the dielectric layer is positioned between the first substrate and the metal layer;
the material of the metal layer comprises: one or more of aluminum, silver, or gold; the material of the dielectric layer includes: silicon nitride;
the metal layer is provided with a first bottom surface deviating from the first substrate and a second bottom surface opposite to the first bottom surface, and the dielectric layer is provided with a third bottom surface deviating from the first substrate and a fourth bottom surface opposite to the third bottom surface;
the area of the first bottom surface is smaller than or equal to the area of the second bottom surface, the area of the second bottom surface is smaller than or equal to the area of the third bottom surface, and the area of the third bottom surface is smaller than or equal to the area of the fourth bottom surface;
when light is transmitted in the forward direction, bragg diffraction occurs at the gap positions between the metal layers; the dielectric layer reflects light when the light is transmitted in reverse.
2. The optically asymmetric transmission structure of claim 1 wherein the orthographic projection of the metal layer onto the first substrate at least partially overlaps the orthographic projection of the dielectric layer onto the first substrate.
3. The optical asymmetric transmission structure of claim 2 wherein the orthographic projection of the metal layer onto the first substrate falls within the orthographic projection of the dielectric layer onto the first substrate.
4. A light asymmetric transmission structure as claimed in claim 3 wherein the center point of the metal layer is collinear with the center point of the dielectric layer.
5. The optical asymmetric transmission structure as recited in claim 1 wherein the metal layer further has a first side connected to both the first bottom surface and the second bottom surface, and the dielectric layer further has a second side connected to both the third bottom surface and the fourth bottom surface;
the first side surface is provided with a first side edge and a second side edge which are oppositely arranged along the direction perpendicular to the first substrate; the second side surface is provided with a third side edge and a fourth side edge which are oppositely arranged along the direction perpendicular to the first substrate;
the joint of the first side edge and the third side edge is in arc connection or linear connection;
the connection part of the second side edge and the fourth side edge is arc-shaped connection or straight line connection.
6. The optical asymmetric transmission structure of claim 1 wherein the plurality of grating elements are in a triangular lattice arrangement, a tetragonal lattice arrangement, or a hexagonal lattice arrangement.
7. The optical asymmetric transmission structure as recited in claim 1, further comprising: a second substrate arranged opposite to the first substrate, and an anisotropic material positioned between the first substrate and the second substrate;
the anisotropic material is filled between the grating units and the second substrate.
8. The optically asymmetric transmission structure of claim 7 wherein the anisotropic material comprises: a liquid crystal material.
9. The optical asymmetric transmission structure as recited in claim 8, further comprising: a first electrode layer and a second electrode layer disposed opposite to each other;
the first electrode layer is positioned between the first substrate and the dielectric layer;
the second electrode layer is positioned on one side of the second substrate close to the first substrate;
the liquid crystal material is filled between the first electrode layer and the second electrode layer.
10. The optical asymmetric transmission structure as recited in claim 9, further comprising: an alignment layer;
the alignment layer is positioned on one side of the second electrode layer, which is away from the second substrate.
11. An optical device comprising an optically asymmetric transmission structure as claimed in any one of claims 1 to 10.
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| CN102681078A (en) * | 2012-06-06 | 2012-09-19 | 昆山龙腾光电有限公司 | Grating polarizer |
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