KR20230049514A - Metaoptics and electric device including the same - Google Patents

Abstract

The present application relates to a meta-optical element and an electronic device containing the same. According to an exemplary embodiment of the present invention, a meta-optical element includes: a waveguide layer; a grating which diffracts incident light of a certain wavelength; a first electrode disposed below the grating; a second electrode disposed over the grating; and a dielectric layer which electrically insulates the first electrode and the second electrode. Therefore, the meta-optical element has a wide range of optical modulation and can operate at high speeds.

Description

Meta optical element and electronic device including the same {METAOPTICS AND ELECTRIC DEVICE INCLUDING THE SAME}

The present disclosure relates to a meta-optical device and an electronic device including the same.

Metasurfaces include artificial metastructures patterned into arbitrary sizes and shapes smaller than the wavelength. Each metastructure included in the metasurface exhibits predetermined characteristics in response to electromagnetic waves or sound waves applied to the metasurface. The metasurface can modulate the reflection phase or the transmission phase of light, so it can be used as an optical modulator.

In the prior art, refractive index modulation materials having high optical loss are used to construct the phase modulation array, and there is a disadvantage in that absorption loss is large due to the structural characteristics of the prior art. Accordingly, there is a problem in that efficient modulation is difficult due to a low Q-factor.

As one of the prior art, vanadium dioxide (VO ₂ ), which is one of the phase change materials between metal antennas, is used as a phase change material, and a current is applied to a gold (Au) antenna to change the phase of VO ₂ , and the phase is changed using this. falsified. However, since the prior art uses a metal reflector, a lot of optical absorption occurs, and as a result, the Q factor of the resonator is lowered. For example, the Q factor (resonant wavelength/full width at half-maximum (FWHM)) may range from about 5 to about 20. In the prior art, there is a problem in that the Q factor is small, and the maximum modulation phase at the resonance wavelength also has a small range of about 180 degrees.

A meta-optical element according to an exemplary embodiment modulates light non-mechanically, and may provide a meta-optical element having excellent performance.

A method of manufacturing a meta-optical device according to an exemplary embodiment may provide a method of manufacturing a meta-optical device including an active device.

A meta-optical element according to an exemplary embodiment is disposed on a waveguide layer including a first surface and a second surface facing the first surface, and a grating including a two-dimensional material, and a grating below the grating. It may include a plurality of meta units each including a disposed first electrode, a dielectric layer disposed on the lattice, and a second electrode disposed on the dielectric layer, and when a voltage is applied to the first electrode and the second electrode, the dielectric constant of the lattice This changes, and the reflectance for the incident light may change.

In addition, the change in the permittivity of the lattice is due to the change in the exciton density of the lattice, and the voltage may have a magnitude that generates exciton resonance of the lattice.

In addition, the gratings included in each of the plurality of meta units are disposed apart from each other in a first direction, and the waveguide layer reflects light diffracted by the grating between the first and second surfaces to change the first direction in which the gratings are arranged. It can be configured to guide the mode resonance (guided mode resonance) towards.

Also, the plurality of meta units may be arranged in a first direction and a second direction perpendicular to the first direction.

Alternatively, the light includes light of a first wavelength that is an exciton absorption wavelength of a material included in the grating and is a bonded mode resonance wavelength, and the period of the grating is smaller than the first wavelength so that high order mode diffraction (high order diffraction) may be blocked.

And, when the light of the second wavelength greater than the first wavelength is incident, the bonded mode resonance wavelength is blue-shifted (blue-shift), and when the light of the third wavelength smaller than the first wavelength is incident, the bonded mode resonance wavelength may be red-shifted.

In addition, the lattice includes at least one of graphene, transition metal dichalcogenide (TMDc), and a two-dimensional semiconductor material, and the wavelength of light may be 10 nm to 3000 μm.

For example, the grating includes tungsten disulfide (WS ₂ ), and the wavelength of light may be 600 nm to 630 nm.

Voltage may be independently applied to each of the plurality of meta units through the first electrode and the second electrode included in each of the plurality of meta units.

In addition, at least one of light reflectance and transmittance may have a difference of 20% or more between the case where voltage is applied and the case where voltage is not applied.

Also, the meta-optical element may have a Q-factor of 100 or more.

For example, the first electrode or the second electrode includes at least one of indium tin oxide (ITO), aluminum zinc oxide (AZO), indium zinc oxide (IZO), or indium gallium zinc oxide (IGZO), and the waveguide layer Silver may include at least one of silicon oxide (SiO ₂ ), hafnium oxide (HfO ₂ ), titanium oxide (TiO ₂ ), or aluminum oxide (Al ₂ O ₃ ).

In addition, the second electrode included in one meta-unit among the plurality of meta-units surrounds the upper and side surfaces of the lattice included in the meta-unit and may extend along the waveguide layer.

And, the waveguide layer may have at least one form of a slab, a ridge, a channel, a strip-loaded, a buried, or a photonic crystal.

In addition, the meta-optical device may be capable of electrical tuning.

A meta-optical element according to an exemplary embodiment may include a waveguide layer and a plurality of metaunits disposed on the waveguide layer, each including a lattice containing a two-dimensional material and an active element for applying a stimulus to the lattice, The lattices included in each of the plurality of metaunits are spaced apart, and when a voltage is applied to the lattice corresponding to the active element by the active element, the permittivity of the lattice may change and the reflectance of the incident light may change.

In addition, the active element generates exciton resonance in the two-dimensional material, electrical gating structure, optical stimulation structure, chemical reaction structure, magnetic field application structure, heating ) structure, or at least one of a mechanical deformation structure.

In addition, the plurality of metaunits may receive stimuli independently by active elements included in each of the plurality of metaunits.

Also, depending on whether the active element is stimulated, at least one of light reflectance and transmittance may have a difference of 20% or more, and the meta-optical element may have a Q factor of 100 or more.

An electronic device according to an exemplary embodiment may include the meta-optical element.

A meta-optical device according to an exemplary embodiment may provide a high Q factor meta-optical device using graphene, transition metal dichalcogenide (TMDc), or a two-dimensional material.

A meta-optical device according to an exemplary embodiment may provide a meta-optical device having a large change in grating characteristics, for example, reflectance or transmittance of a grating, by an external stimulus through an active structure.

A meta-optical device according to an exemplary embodiment may provide a meta-optical device that has a wide light modulation range and can operate at high speed.

The method for manufacturing a meta-optical device according to an exemplary embodiment may manufacture a meta-optical device including an active element.

1 is a cross-sectional view showing a meta-optical element according to an exemplary embodiment.
2 is a graph of a real part and an imaginary part of a dielectric constant according to an exciton resonance state of tungsten disulfide (WS ₂ ) that varies with wavelength.
3A is a cross-sectional view illustrating a meta-optical device according to an exemplary embodiment.
FIG. 3B is a perspective view of the meta-optical device of FIG. 3A.
4 is a conceptual diagram illustrating an optical path of light incident on a meta-optical element.
FIG. 5 is a reflectance graph and a phasor according to an exciton resonance state of WS ₂ that changes according to the wavelength of incident light of the meta-optical device of FIG. 3A.
6 is a transmittance graph and a phasor according to an exciton resonance state of WS ₂ that changes according to the wavelength of incident light of the meta-optical device of FIG. 3A.
7 is a cross-sectional view of a meta-optical device according to an exemplary embodiment for optical pumping.
8 is a conceptual diagram of a light pumping measurement set-up of a meta-optical device according to an exemplary embodiment.
FIG. 9A is a graph of experimental results showing scattering intensity according to an incident angle and a light wavelength when a pump beam is not irradiated in FIG. 8 .
9B is a simulation result graph showing light absorption according to an incident angle and a light wavelength when a pump beam is not irradiated in a TE mode.
9C is a graph of simulation results showing the incident angle θ _i , light wavelength, and light absorption when the pump beam is not irradiated in the TM mode.
FIG. 10 is an enlarged graph of secondary TM mode branches in the incident angle range of about 13 degrees to about 20 degrees and a wavelength band of about 590 nm to about 620 nm in FIG. 9A.
11A is an experimental graph showing line width change according to wavelength when a pump beam is not irradiated.
11B is a simulation graph showing a change in line width according to wavelength when a pump beam is irradiated and when it is not irradiated.
12 is a plan view showing meta units arranged in 2D.
13 is a graph showing the relative permittivity according to the wavelength of a grating including WS ₂ .
14A to 14E are diagrams illustrating a method of manufacturing a meta-optical element according to an exemplary embodiment.
15 is a photomicrograph showing a plan view of the manufactured meta-optical device.
16 is a conceptual diagram illustrating a beam steering device including a meta-optical device according to an exemplary embodiment.
17 is a conceptual diagram for explaining a beam steering device including a meta-optical device according to an exemplary embodiment.
18 is a block diagram for explaining an overall system of an electronic device including a beam steering device to which a meta-optical device is applied according to an exemplary embodiment.
19 and 20 are conceptual views illustrating cases in which a LiDAR device including a meta-optical element according to an exemplary embodiment is applied to a vehicle. 19 is a view viewed from the side, and FIG. 20 is a view viewed from above.
Fig. 21 is a block diagram showing a schematic configuration of an electronic device according to an exemplary embodiment.
FIG. 22 is a block diagram showing a schematic configuration of a camera module included in the electronic device of FIG. 21 as an example.
FIG. 23 is a block diagram showing a schematic configuration of a 3D sensor included in the electronic device of FIG. 21 .
Fig. 24 is a block diagram showing a schematic configuration of an electronic device according to an exemplary embodiment.
FIG. 25 is a block diagram showing a schematic configuration of an eye tracking sensor included in the electronic device of FIG. 24 .

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. The described embodiments are merely illustrative, and various modifications are possible from these embodiments. In the following drawings, the same reference numerals denote the same components, and the size of each component in the drawings may be exaggerated for clarity and convenience of description.

Hereinafter, what is described as "above" or "above" may include not only what is directly on top of contact but also what is on top of non-contact. Similarly, references to “below” or “below” may include directly under contact as well as under non-contact.

Expressions in the singular number include plural expressions unless the context clearly dictates otherwise. In addition, when a certain component is said to "include", this means that it may further include other components without excluding other components unless otherwise stated.

The use of the term “above” and similar denoting terms may correspond to both singular and plural.

The meaning of “connection” may include not only a physical connection, but also an optical connection, an electrical connection, and the like.

In addition, the use of all exemplary terms (for example, etc.) is simply for explaining technical ideas in detail, and the scope of rights is not limited due to these terms unless limited by claims.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. Terms are used only to distinguish one component from another.

The fact that length units such as height, depth, and thickness are substantially the same or the same may include differences within the error range recognized by those skilled in the art.

The term "and/or" can include any combination that includes one or more of the listed elements. Also, for example, the expression “at least one of A, B, or C” means one A, one B, one C, two including A and B, two including A and C, and one including B and C. It can mean including both, or all including A, B, and C.

A two-dimensional material may refer to a material in which atoms of several nanometers are arranged in one layer, that is, a crystalline material composed of one layer of atoms.

Meta-optics may mean an optical device including a metasurface.

A line of exciton on (on-exc.) in the figure may mean a state in which exciton absorption is possible or a state in which exciton resonance is possible, and a line of exciton off (off-exc.) in the figure indicates a state in which exciton absorption is suppressed, Alternatively, it may mean a state in which exciton resonance is suppressed.

1 is a cross-sectional view showing a meta-optical device according to an exemplary embodiment, and FIG. 2 is a graph of a real part and an imaginary part of a dielectric constant according to an exciton resonance state of tungsten disulfide (WS ₂ ) that varies with wavelength. 3A is a cross-sectional view of a meta-optical device according to an exemplary embodiment, and FIG. 3B is a perspective view of the meta-optical device of FIG. 3A.

The meta-optical device 10 according to an exemplary embodiment includes a waveguide layer 100 and a grating 210 disposed on the waveguide layer 100 and diffracting incident light of a predetermined wavelength and applying a stimulus to the grating 210. It may include a plurality of meta units 200 each including an active element (AE) to apply. Stimuli are applied to each grating 210 corresponding to each active element AE by each active element AE to change the permittivity of each grating 210, and accordingly, the incidence of each grating 210 The reflectance for light can be changed. For example, the active element AE can generate exciton resonance in a two-dimensional material, and the change in permittivity of the lattice 210 is due to the change in exciton density of the lattice 210 it may have been The active element AE of the meta-optical device 10 according to an exemplary embodiment includes a first electrode 221 disposed below the grating 210, a dielectric layer 230 disposed above the grating 210, and a dielectric layer 230. ) may include a second electrode 222 disposed thereon. Each of the plurality of meta units 200 or each of the plurality of meta units 200 is included in the grid 210 included in each of the plurality of meta units 200 (or corresponding to each of the plurality of meta units 200) ) Voltage may be independently applied through the first electrode 221 and the second electrode 222 . By the grating 210 to which stimulation is applied by the active element AE, for example, by the grating 210 to which voltage is applied through the first electrode 221 and the second electrode 222, the meta-optical element The properties of (10) (e.g., reflectance or transmittance) may vary. For example, exciton resonance of a material including the grating 210 may be determined when a stimulus is applied to the grating 210 from the outside, and thus exciton density may be changed, and characteristics of the meta-optical device 10 may be changed. It can change. The meta-optical element 10 according to an exemplary embodiment may be implemented as an active element capable of modulating incident light by including an active element AE. For incident light of the same wavelength, the meta-optical element 10, which is an active element including an active element (AE), may provide a different output or different modulation characteristics than a meta-optical element, which is a passive element that does not include an active element (AE). can The meta-optical device 10 according to an exemplary embodiment may include an active structure capable of changing the characteristics of the meta-optical device 10 by applying a stimulus to the grating 210, and the characteristic change width is relatively It is possible to provide an optical element including a metasurface that has a wide modulation range of light, operates at high speed, and provides a high Q-factor, that is, the meta-optical element 10 .

Referring to FIG. 1 , a meta-optical device 10 according to an exemplary embodiment may include a substrate 50 . The substrate 50 may include a dielectric material or a semiconductor material, and may include, for example, silicon dioxide (SiO ₂ ), but is not limited thereto. A waveguide layer 100 may be disposed on the substrate 50 . The substrate 50 may remain even after the meta-optical device 10 is manufactured. However, it is not limited thereto, and the substrate 50 is used only during the manufacturing process of the meta-optical device 10 and may be removed after manufacturing the meta-optical device 10 . The substrate 50 may include a light-transmitting material having high transmittance in a predetermined wavelength range, for example, about 85% or more. The wavelength of incident light may be included in the predetermined wavelength range. For example, if the incident light belongs to the visible light range, the substrate 50 includes a light-transmissive material having a transmittance of about 85% or more in the visible light range, or a transparent material. can include Incident light belonging to the visible ray range is only an example, and incident light of deep UV to THz may be used without being limited thereto. For example, the wavelength of incident light may be about 10 nm to about 3000 μm.

The meta-optical device 10 according to an exemplary embodiment may include a waveguide layer 100 . The waveguide layer 100 may include an insulating material (dielectric material), and may constitute a light guide through which incident light proceeds in a guided mode. The waveguide layer 100 may include a first surface 110 on the waveguide layer 100 in contact with another medium, and may include a second surface 120 under the waveguide layer 100. The first surface 110 and the second surface 120 may face each other. The first surface 110 may indicate an upper surface of the waveguide layer 100 . The second surface 120 may refer to a surface located under the waveguide layer 100 and may be a surface in contact with another medium disposed under the waveguide layer 100 . If the metaunit 200 includes the substrate 50, the second surface 120 may be an interface between the waveguide layer 100 and the substrate 50. Alternatively, if the substrate 50 is removed from the formed meta unit 200, the second surface 120 may be an interface between the waveguide layer 100 and another medium such as air.

Incident light may be reflected on the first surface 110 and the second surface 120, and through this, the light guides mode resonance inside the waveguide layer 100, and the side of the waveguide layer 100 direction can be waved. At this time, the lateral direction may be a direction perpendicular to the thickness direction of the waveguide layer 100, or may be a direction parallel to the first direction in which the plurality of meta units 200 are disposed.

In the first surface 110 , light may be incident into the waveguide layer 100 from a first medium positioned on the waveguide layer 100 . Light incident on the first surface 110 may be refracted or diffracted. The refracted light may travel at a different angle with respect to the diffracted light and the normal line. Alternatively, light traveling from the first medium toward the waveguide layer 100 may be reflected by the first surface 110 . The incident light may be reflected or diffracted on the first surface 110 or may be refracted and transmitted through the first medium. The diffracted light may proceed at an angle different from that of the refracted light based on the normal line. In the second surface 120, the light may be refracted and incident to the second medium located under the waveguide layer 100. Alternatively, light from the second surface 120 may be reflected into the inside of the waveguide layer 100 toward the first surface 110 again. Light diffracted by the waveguide layer 100 may be reflected from the first surface 110 and the second surface 120 and guided in a first direction.

The waveguide layer 100 may include a light-transmitting material having high transmittance in a predetermined wavelength range, for example, about 85% or more. The predetermined wavelength range may include the wavelength of incident light. For example, if the incident light belongs to the visible light range, the waveguide layer 100 includes a light-transmitting material having a transmittance of about 85% or more in the visible light range, or is transparent. may contain substances. Incident light belonging to the visible ray range is only an example, and incident light of deep UV to THz may be used without being limited thereto.

The waveguide layer 100 may include an insulating material (dielectric material). The waveguide layer 100 may include at least one of an insulating silicon compound and an insulating metal compound. For example, at least one of silicon dioxide (SiO ₂ ), hafnium oxide (HfO ₂ ), titanium oxide (TiO ₂ ), aluminum oxide (Al ₂ O ₃ ), and silicon nitride (Si ₃ N ₄ ) may be included. The refractive index of the material included in the waveguide layer 100 may be greater than 1 and may be greater than the refractive index of the substrate 50 .

Light incident on the waveguide layer 100 can be guided in the lateral direction of the waveguide layer 100 with guided mode resonance, which means that the waveguide layer 100 constitutes a waveguide can do. The light pipe may have, for example, a slab, ridge, channel, strip-loaded, buried, or photonic crystal shape. While the light is bonded mode resonance along the waveguide, it may pass through the first surface 110 or the second surface 120 and enter the first medium or the second medium. For example, light may be guided inside the light pipe and pass through the second surface 120 to be transmitted to the substrate 50, where the substrate 50 may be the second medium. A component of the light transmitted into the medium through resonance in the interior and a component directly transmitted into the medium without diffraction may interfere with each other, and the transmission and reflection spectra may change depending on whether the interference is destructive interference or constructive interference. A detailed description of this will be described later.

The meta-optical element 10 according to an exemplary embodiment is disposed on the waveguide layer 100 and may include a plurality of meta-units 200 that modulate incident light of a predetermined wavelength. At least one of the plurality of meta units 200 includes a grating 210 that diffracts incident light, a first electrode 221 disposed under the grating 210, and a dielectric layer 230 disposed above the grating 210. , and may include a second electrode 222 disposed on the dielectric layer 230 .

The grating 210 may diffract light, and a portion of the diffracted light may resonate with the bonded mode along the waveguide layer 100. When light is incident at a predetermined angle, it is not diffracted by the grating 210 but is refracted to the waveguide layer 100 and incident light (light in the 0th diffraction mode, m=0) is emitted from the second surface 120. A component transmitted to the medium and a component transmitted from the second surface 120 to the second medium among the light diffracted by the grating 210, resonated, and then diffracted again (light in the 1st order diffraction mode, m=1) may cause interference. For example, when the two components cause destructive interference, transmission of light from the second surface 120 of the waveguide layer 100 to the second medium may be suppressed. In this case, reflectance of light on the first surface 110 may be relatively high. Alternatively, for example, when the two components cause constructive interference, the transmission of incident light on the second surface 120 of the waveguide layer 100 can be less suppressed, and thus, for the incident light on the first surface 110 The reflectance may be relatively low.

The lattice 210 included in each of the plurality of meta units 200 and the first electrode 221 in contact therewith may be spaced apart from each other. The period Λ of the lattice 210 included in each of the plurality of meta units 200 may be referred to as the period of the plurality of meta units 200 . The period (Λ) of the grating 210 shown in FIG. 1 is 300 nm, the height (t) of the meta unit 200 is 30 nm, the width (w) of the meta unit 200 is 83 nm, and the waveguide layer (100) may be 300 nm thick. The spaced apart gratings 210 may be periodically arranged, and the period Λ of the grating 210 may be smaller than the wavelength of incident light. For example, if the wavelength of incident light is about 610 nm to about 620 nm in air, the period Λ of the grating 210 may be smaller than the wavelength of incident light in air. For example, it may be about 10 nm to about 600 nm, but is not limited thereto. Alternatively, the period Λ of the grating 210 may be smaller than the wavelength of light in the waveguide layer 100 .

If the period Λ of the grating 210 is smaller than the wavelength of incident light, high order mode diffraction may be blocked when light is incident on the grating 210 . The higher-order diffraction mode may mean an n-order diffraction mode (here, an absolute value of n is an integer greater than 1). That is, the 0th order mode (0 ^th order mode, m = 0) mode (refracted mode without diffraction), -1 st order mode (-1 ^st order mode, m = -1) and 1st order diffraction mode (first order mode) mode, m = 1) can occur.

Each of the plurality of meta units 200 is disposed on the waveguide layer 100 and may have a predetermined height t. The predetermined height t of the meta unit 200 may be greater than the height of the lattice 210 . Among the upper surfaces of the waveguide layer 100, the height of the upper surface of the waveguide layer 100 is higher than that of the portion where the meta unit 200 is not disposed on the portion where the meta unit 200 is disposed, so that the protrusion may be disposed. A part or all of the protrusion formed of an insulating material included in the layer 100 may be included in the meta unit 200 . For example, the height t of the meta unit 200 may be about 5 nm to about 100 nm, but is not limited thereto.

Also, the width w of the meta unit 200 may be smaller than the wavelength of the incident light. For example, the width w of the meta unit 200 may be about 10 nm to about 500 nm, but is not limited thereto.

The grating 210 may include a material whose characteristics may be changed by external stimuli. For example, the characteristics of the grating 210 may be at least one of a phase, permittivity, refractive index, reflectance, transmittance, or absorption of the grating 210, which is merely an example, and other physical properties, chemical properties, and optical properties. may be a characteristic. In order to change the characteristics of the lattice 210, an active element (AE) may be further included in the meta unit 200. For example, a state in which a material included in the lattice 210 can absorb excitons by an external stimulus (exciton resonance possible state), or a state in which absorption of excitons is suppressed (exciton resonance suppressed state). In addition, the phase of the material included in the grating 210 may be changed by an external stimulus. The grating 210 may include a material that is reversible to a characteristic change by the active element AE.

The lattice 210 may include a 2D material, and may include, for example, at least one of graphene, transition metal dichalcogenide (TMDc), or a 2D semiconductor material. For example, the lattice 210 may include transition metal dichalcogenides such as molybdenum disulfide (MoS ₂ ), molybdenum diselenide (MoSe ₂ ), molybdenum iteluride (MoTe ₂ ), and tungsten disulfide (WS ₂ ). , tungsten iselenide (WSe ₂ ), and tungsten istelluride (WTe ₂ ). Transition metal dichalcogenides may have different optical properties in a state in which exciton absorption is possible (or in a state in which exciton resonance is possible) and in a state in which exciton absorption is suppressed (or in a state in which exciton resonance is suppressed). there is. For example, at least one of permittivity, refractive index, transmittance, reflectance, or absorption may be different. According to FIG. 2 , in the case of WS ₂ , the real part of the permittivity in a state in which exciton absorption is possible and in a state in which exciton absorption is suppressed may be the same at a predetermined wavelength of about 613.7 nm. However, for light with a wavelength of less than about 613.7 nm, the real part of the permittivity of WS ₂ may be smaller in a state in which exciton absorption is possible than in a state in which exciton absorption is suppressed, and for light with a wavelength greater than about 613.7 nm, exciton absorption The real part of the permittivity of WS ₂ may be greater in a state in which is possible than in a state in which exciton absorption is suppressed. In this case, if the real part of the permittivity of the material in the first state is greater than that in the second state, it may mean that the refractive index in the first state is greater than the refractive index in the second state. In addition, the imaginary part of the permittivity of WS ₂ when exciton absorption is possible may be greater than the imaginary part of the permittivity of WS ₂ when exciton absorption is inhibited. In this case, if the imaginary part of the permittivity of the material in the first state is greater than that in the second state, it may mean that the light absorptivity in the first state is greater than the light absorptivity in the second state.

The lattices 210 included in each of the plurality of meta units 200 may be spaced apart from each other in the first direction, and each spaced lattice 210 may form a grating structure. Here, the first direction may be a direction substantially perpendicular to the thickness direction of the waveguide layer 100 . However, it is not limited to the above examples and may vary depending on the shape of the waveguide layer 100. Light diffracted and incident on the first surface 110 of the waveguide layer 100 may be reflected by the first surface 110 and the second surface 120 and guided in a first direction. The fact that the grids 210 included in each of the plurality of meta units 200 are spaced apart in the first direction may mean that the plurality of meta units 200 are arranged one-dimensionally. The meta-optical device 10 including a plurality of meta-units 200 in one dimension may steer a beam in a first direction in which the grating 210 is spaced apart. As in the above example, the plurality of meta units 200 may be arranged one-dimensionally, but is not limited thereto, and the plurality of meta units 200 may be arranged two-dimensionally. In this case, the plurality of meta units 200 may be arranged in a first direction and a second direction perpendicular to the first direction. That is, the lattice 210 included in each of the plurality of meta units 200 may be spaced apart from each other in the first direction and the second direction. In this case, the meta-optical element 10 including the plurality of two-dimensional meta-units 200 may steer the beam in the first direction and the second direction, which are directions in which the grating 210 is spaced apart. Here, the first direction may be a direction perpendicular to the second direction.

At least one of the plurality of metaunits 200 according to an exemplary embodiment may include an active element (AE) for applying a stimulus to the grating 210 . When a stimulus is applied to the grating 210 by the active element AE, the permittivity, refractive index, and absorptivity of the grating 210 may change, and accordingly, reflectance and transmittance of the meta-optical element 10 may change. there is. The stimulus applied by the active element AE may be, for example, electric field application, magnetic field application, voltage application, optical pumping, chemical reaction, temperature change (heating), mechanical deformation, and the like. The active element AE may be, for example, an electrical gating structure, an optical stimulation structure, a chemical reaction structure, a magnetic field application structure, a heating structure, or a mechanical deformation structure. there is.

The active element AE may change the characteristics of the grating 210 by applying a voltage, applying light, inducing a chemical reaction, applying a magnetic field, heating or cooling, or applying mechanical force to the grating 210 . For example, the reflectance and transmittance of the meta-optical device 10 for light of a predetermined wavelength by changing the properties (eg, dielectric constant, refractive index, absorptivity, exciton density) of the two-dimensional material included in the grating 210 , and/or change the absorption rate. However, the changing properties of the 2D material are not limited to the exemplary properties listed above, and other physical properties or chemical properties of the material may change. For example, electrical properties, optical properties, magnetic properties, thermal properties, crystal structural properties, etc. may change. Among the properties may include thermal conductivity, electrical conductivity, lattice constant, magnetoresistance, and the like. A change in the characteristics of the grating 210 through the active element AE may be reversible, but is not limited thereto.

Whether or not resonance of excitons included in the grating 210 is possible may be determined according to stimulation through the active elements AE of the plurality of metaunits 200 . When the active element AE is switched on, exciton absorption in the grating 210 can be suppressed (exciton resonance is suppressed), and when the active element AE is switched off, the grating 210 ), exciton absorption is possible (exciton resonance is possible). Exciton density can be controlled by appropriately adjusting the size of the stimulus through the active element (AE). Accordingly, it is possible to obtain intermediate state characteristics between the characteristic state of the lattice 210 and the characteristic state of the lattice 210 in the switched-off state at a specific threshold value (eg, when the exciton density is maximum) during the switched-on state. The feature may be applied to the meta-optical element 10 according to an exemplary embodiment and an electronic device including the meta-optical element 10 .

The active element AE may include, for example, a first electrode 221, a second electrode 222, and a dielectric layer 230 electrically insulating the first electrode 221 and the second electrode 222. can Here, the active element AE is an electrical gating structure, and may be a structure that applies a voltage to both ends of the grating 210 .

When the active element AE is included in the meta-optical device 10 according to an exemplary embodiment, the bonded mode resonance wavelength of light in the waveguide layer 100 of the meta-optical device 10 may be changed. Accordingly, it may be difficult to apply the optical characteristics of the passive meta-optical element not including the active element AE to the active meta-optical element 10 including the active element AE.

According to the exemplary embodiment of FIG. 3A , the period Λ of the grating 210 of the meta-optical element 10 is 300 nm, the height t of the meta unit 200 is 30 nm, and the width of the meta unit 200 is 30 nm. (w) is 83 nm, the thickness of the waveguide layer 100 is 300 nm, the thickness of the first electrode 221 and the second electrode 222 is 10 nm, and the thickness of the dielectric layer 230 is 15 nm. The grating 210 includes tungsten disulfide (WS ₂ ), the waveguide layer 100 includes silicon nitride (Si ₃ N ₄ ), the substrate 50 includes silicon dioxide (SiO ₂ ), and the first electrode 221 and the second electrode 222 include aluminum zinc oxide (AZO), and the dielectric layer 230 includes aluminum oxide (Al ₂ O ₃ ). In this case, the bonded mode resonance wavelength is about 615.8 nm. However, this can be changed by various factors such as the height (t) of the meta unit 200, the period (Λ) of the grating 210, and the thickness of the waveguide layer 100. In the above example, the bonded mode resonance wavelength of the meta-optical element 10 of the passive element without the first electrode 221, the second electrode 222, and the dielectric layer 230 may be about 613.7 nm, and this difference may be active This may be due to the difference in the presence or absence of elements. In other words, this change may be due to the addition of the active element (AE), in the above example, the condition of the bonded mode resonance (GMR) is changed by the added electrode layer and the dielectric layer 230. The change in this bonded mode resonance wavelength is exemplary, in addition to exciton absorption, or when suppressing exciton absorption, various properties such as permittivity, refractive index, reflectance and transmittance of the grating 210 are changed. can

Referring to FIGS. 3A and 3B , the plurality of meta-units 200 of the meta-optical element 10 according to the exemplary embodiment are active elements AE, and the first electrode 221 disposed under the grating 210 ), and the second electrode 222 disposed on the grid 210. The first electrode 221 , the second electrode 222 , and the dielectric layer 230 may constitute an active element AE capable of applying a voltage to the grating 210 . The grids 210 included in each of the plurality of meta units 200 may be disposed apart from each other, and the first electrodes 221 included in each of the plurality of meta units 200 may also be disposed apart from each other. The lattice 210 included in one of the plurality of meta units 200 and the first electrode 221 may contact each other. The grating 210 and the first electrode 221 included in one of the plurality of meta units 200 may correspond to each other on a one-to-one basis, and accordingly, a voltage may be independently applied to each of the plurality of meta units 200. . That is, since the voltage can be adjusted for each of the plurality of meta units 200, the meta optical element 10 according to the exemplary embodiment may be an active element capable of selectively applying voltage to each meta unit 200. .

The first electrodes 221 included in each of the plurality of meta units 200 may not be electrically connected to each other. The second electrode 222 may be disposed on the grid 210, and the second electrodes 222 included in each of the plurality of meta units 200 may be disposed spaced apart from each other. Alternatively, the second electrode 222 included in each of the plurality of meta units 200 may cover the upper surface and the side surface of the grating 210 and may be on the upper surface of the waveguide layer 100 in the first direction. can be extended and connected to each other. The upper surface of the grating 210 and the second electrode 222 surrounding the side of the grating 210 may reduce absorption or scattering of light obstructing the bonded mode resonance, and thus the bonded mode resonance may occur relatively well. can

The first electrode 221 and the second electrode 222 may be spaced apart from each other and may be electrically insulated from each other. A dielectric layer 230 for electrical insulation between the two layers may be disposed between the first electrode 221 and the second electrode 222 . A voltage may be applied to each of the first electrode 221 and the second electrode 222 , and a potential difference between the two electrode layers may be applied to the grating 210 . Due to the potential difference between the first electrode 221 and the second electrode 222, exciton absorption is suppressed in a state in which excitons of the material included in the lattice 210 can be absorbed (or in a state in which exciton resonance is possible) ( or a state in which exciton resonance is suppressed). Potential differences applied to each of the plurality of meta units 200 may be independent of each other.

The first electrode 221 and the second electrode 222 may be transparent conducting films (TCO) that have high optical transmittance and low electrical resistance, and are electrically conductive. For example, Indium Tin Oxide (ITO), Indium Zinc Oxide (IZO), Aluminum Zinc Oxide (AZO), Indium Gallium Zinc Oxide (IGZO), etc. can include In the examples of FIGS. 3A and 3B , the material included in the first electrode 221 and the second electrode 222 is AZO. The thickness of the first electrode 221 and the second electrode 222 disposed in FIGS. 3A and 3B may be about 10 nm. However, it is not limited thereto and may have a thickness of several nanometers to several tens of nanometers.

Referring to FIGS. 3A and 3B , the plurality of meta units 200 may include a dielectric layer 230 . The dielectric layer 230 may electrically insulate the first electrode 221 and the second electrode 222 . A dielectric layer may be disposed between the first electrode 221 and the second electrode 222 . Dielectric layers 230 included in each of the plurality of meta units 200 may be spaced apart from each other. Alternatively, the dielectric layer 230 included in each of the plurality of meta units 200 may cover the top and side surfaces of the grating 210 and extend to the top surface of the waveguide layer 100 to be connected to each other. The second electrode 222 may also cover the side surface of the grating 210 and may extend on the top surface of the waveguide layer 100 in the first direction and be connected to each other. When extending to the upper surface of the waveguide layer 100 , the dielectric layer 230 may extend and be disposed along the lower portion of the extending second electrode 222 .

The dielectric layer 230 includes a dielectric material, and may include, for example, silicon oxide (SiO ₂ ), hafnium oxide (HfO ₂ ), titanium oxide (TiO ₂ ), aluminum oxide (Al ₂ O ₃ ), and the like. In the examples of FIGS. 3A and 3B , the material included in the dielectric layer 230 is Al ₂ O ₃ , and Al ₂ O ₃ has a breakdown field as high as 7 MV/cm. It may be suitable for the dielectric layer 230 because it has high dielectric strength. The thickness of the dielectric layer 230 of FIGS. 3A and 3B may be about 15 nm. However, it is not limited thereto and may have a thickness of several nanometers to several tens of nanometers.

The meta-optical device 10 according to an exemplary embodiment may be an active device including a grating 210 layer and an active element AE. As described above, since the active element includes the active element AE, even if it has the same grating 210 as the passive element, its physical characteristics, eg, optical characteristics, may be different from those of the passive element. In addition, by modifying the characteristics of the grating 210 with the active element (AE), some of the plurality of meta units 200 or each of the plurality of meta units 200 may be tuned. As shown in FIGS. 3A and 3B , when a voltage application structure including a first electrode 221 and a second electrode 222 is included as an active element (AE), a grid 210 of a plurality of meta units 200 Each can be electrically tuned independently.

Next, the optical path according to the bonded mode resonance (GMR) will be described.

4 is a conceptual diagram illustrating an optical path of light incident on a meta-optical element. 5 is a reflectance graph and a phasor according to an exciton resonance state of WS ₂ that varies according to the wavelength of incident light of the meta-optical element of FIG. 3A, and FIG. _2. Transmittance graph and phasor according to the exciton resonance state.

According to FIG. 4 , the waveguide layer LA3 may include a first surface on which the lattice structure LA2 is formed, and may include a second surface in contact with the second medium LA4. A portion of light i incident on the grating structure LA2 at an incident angle θ _i may be transmitted through the first surface of the waveguide layer LA3 without diffraction (0th-order diffraction mode, m=0). Since the refractive index (n ₃ ) of the waveguide layer LA3 is greater than the refractive index (n ₁ ) of the first medium LA1 above the grating structure LA2 , the angle of refraction θ _t may be smaller than the angle of incidence θ _i . Light transmitted without diffraction (t ₁ ) may cross the waveguide layer (LA3) and be refracted on the second surface to pass through the waveguide layer (LA3), and the exited light (t ₂ ) may pass through the lower part of the waveguide layer (LA3). It may be incident to the second medium LA4. Also, a portion of light s ₁ incident to the grating structure LA2 may be diffracted by the grating structure LA2 on the first surface of the waveguide layer LA3. The diffraction angle Ψ may be different from the refraction angle θ _t . The diffracted light (s ₁ ) is coupled to the guided mode (guided mode) can be coupled (coupling) and guided in the lateral direction of the waveguide layer 100 (LA3), this guided mode resonance (guided mode resonance, GMR ) is called Light traveling in the lateral direction in this bonded mode may be slightly emitted from the first surface or the second surface (slightly leak out). Of the light (s ₁ ) to bond mode resonance, the light (s ₂ ) emitted from the second surface may be incident to the second medium (LA4) under the waveguide layer (LA3), and the waveguide layer (LA3) without diffraction Of the light t ₁ incident to the light t 1 , which is refracted on the second surface and exits to the medium LA4 , it may interfere with the light t ₂ . At this time, the diffraction angle θ _s with respect to the normal of the light (s ₂ ) diffracted on the first surface while bonded mode resonance at a specific angle or a specific angle range may be substantially the same as the refraction angle θ _t . A portion of the light i incident on the grating structure LA2 at an incident angle θ _i may be reflected from the first surface. A reflection angle θ _r of light r reflected from the first surface may be equal to an incident angle θ _i , and light may be modulated upon reflection.

3A, 3B, 5 and 6, the meta-optical element 10, as an active element AE, includes a first electrode 221 for applying a voltage to the grating 210, a first It may include two electrodes 222 . When the active element (AE) is included in the meta-optical device 10 according to an exemplary embodiment, the bonded mode resonance wavelength of the material included in the grating 210 of the active element (AE) may change. Therefore, it is difficult to apply the optical characteristics of the passive meta-optical element not including the active element AE to the active meta-optical element 10 including the active element AE. For example, if the active element AE includes the first electrode 221, the second electrode 222, and the dielectric layer 230, the first electrode 221, the second electrode 222, and the dielectric layer 230 This may be because the bonded mode resonance condition is changed by ).

For example, when the meta-optical device 10 includes the waveguide layer 100 and the grating 210 including WS ₂ and does not include an active element AE, the resonant wavelength of WS ₂ is about 613.7 nm , and the meta-optical element 10 includes a waveguide layer 100 including WS ₂ , a grating 210, and an electrode layer and a dielectric layer 230 capable of giving a potential difference to the grating 210, FIG. 5 And, as shown in FIG. 6, the resonant wavelength of WS ₂ may change to about 615.8 nm. The change of the resonant wavelength is only an example, and in addition to this, various properties such as permittivity, refractive index, reflectance, and transmittance may be changed when exciton absorption or exciton absorption is suppressed.

2 to 3B, 5, and 6, when an external stimulus is applied to the grating 210 and absorption of excitons of WS ₂ is suppressed, the imaginary part of the dielectric constant of WS ₂ ranges including a predetermined wavelength may have a relative value of 5 or less in . In this case, WS2 has a relatively low light absorption at a predetermined wavelength, the bonded mode resonance of light in the waveguide layer 100 may not be hindered. When the light is bonded mode resonance, the phase difference between the light emitted from the second surface 120 and the light refracted from the second surface 120 is (2n + 1) * π (rad) (where n is an integer of 1 or more) ), and in this case, the two lights cause destructive interference so that transmission through the second surface 120 can be suppressed. According to FIG. 5, it can be confirmed that the solid line reflectance graph has a peak upward at a predetermined wavelength according to the result of suppression of transmission, and according to FIG. 6, the solid line transmittance graph dips downward in a range near a predetermined wavelength It can be confirmed that it has

When an external stimulus is not applied to the grating 210, and excitons of a material included in the grating 210 (eg, WS ₂ ) can be absorbed, according to FIG. 2, the imaginary part of the dielectric constant of WS ₂ is a predetermined wavelength may have a relatively large value of about 20 or more. In this case, WS ₂ may absorb light of a predetermined wavelength, the bonded mode resonance is hindered by the light absorption, and the resonance may be weakened or may not occur. Due to this, destructive interference between light and light directly transmitted through the meta-optical element 10 may not occur due to this bonded mode resonance, and may not be the transmission suppression described above. In addition, since resonance does not occur, reflectance may be lowered due to high light absorption. According to FIG. 5, it can be confirmed that the chain line reflectance graph has a downward dip at a predetermined wavelength as light absorption occurs, and according to FIG. 6, the chain line transmittance graph has a downward dip near a predetermined wavelength, but the light absorption increases Thus, it can be confirmed that the depth of the dip is smaller and the profile of the dip is broader than the solid line transmittance graph.

In addition, according to the reflectance phasor of FIG. 5 , a phasor (solid line) when exciton absorption is suppressed and a phasor (dashed line) when exciton absorption is possible can be confirmed. A point of the phasor when exciton absorption is suppressed at a wavelength of about 615.8 nm may be located farthest from the circle, which may mean a reflectance peak. One point of the phasor in which exciton absorption is possible at a wavelength of about 615.8 nm may be located relatively close to the circle.

In addition, according to the transmittance phasors of FIG. 6 , a phasor (solid line) when exciton absorption is suppressed and a phasor (dashed line) when exciton absorption is possible can be confirmed. A point of the phasor when exciton absorption is suppressed at a wavelength of about 615.8 nm may be located closest to the circle, which may indicate a reflectance dip. When exciton absorption is possible at a wavelength having a minute difference of about 0.5 nm or less from about 615.8 nm, a point of the phasor may be located closest to the circle, which may mean a reflectance dip.

At least one of reflectance or transmittance for a predetermined wavelength of the grating 210 corresponding to each active element AE according to whether the active element AE included in the meta-optical device 10 according to an exemplary embodiment is stimulated It can have a difference of more than 20%.

5 and 6, the reflectance of the meta-optical device 10 including the first electrode 221, the second electrode 222, and the dielectric layer 230 according to an exemplary embodiment of the incident light is There may be a difference of 20% or more between when a predetermined voltage is applied and when no voltage is applied, or transmittance of incident light of the meta-optical element 10 when a predetermined voltage is applied and when no voltage is applied. It can have a difference of more than 20%. 5 and 6, the reflectance is about 40% when exciton absorption of WS ₂ is suppressed at a wavelength of about 615.8 nm, and the reflectance is about 10% when exciton absorption of WS ₂ is possible, which is about 30% can have a difference. In addition, the transmittance is about 10% when exciton absorption of WS ₂ is suppressed at a wavelength of about 615.8 nm, and the transmittance is about 55% when exciton absorption of WS ₂ is possible, which may have a difference of 20% or more. When the difference in reflectance or transmittance before and after the characteristic change of the grating 210 is sufficiently large, it can serve as a good optical modulator providing a large modulation phase difference at a resonance wavelength. A value between the minimum reflectance and the maximum reflectance of the meta-optical element 10 according to the change in permittivity of the grating 210 may be implemented by the above-described intermediate state, and similarly, the minimum reflectance of the meta-optical element 10 A value between the transmittance and the maximum transmittance may be implemented by the intermediate state described above.

The Q-factor of reflectance and transmittance can be calculated through Equation (1) as follows.

은 공진 파장이고,

은 반치전폭(full width at half maximum, FWHM)이다. 격자(210)가 포함하는 물질의 엑시톤 억제 시에, 상기 물질에 대한 광 흡수가 줄어들어, 가이디드 모드 공진이 일어날 수 있고, 또한 상쇄 간섭이 일어날 수 있으므로, Q 인자가 증가될 수 있다. 높은 Q 인자를 가진 메타 광학 소자(10)는 공진 파장에서 큰 변조 위상차를 제공하며, 광 손실이 적은 좋은 광 변조기로 역할을 할 수 있다.In Equation (1) above

is the resonant wavelength,

is the full width at half maximum (FWHM). Upon suppression of excitons of a material including the grating 210, light absorption for the material is reduced, bonded mode resonance may occur, and destructive interference may occur, so the Q factor may be increased. The meta-optical device 10 having a high Q factor provides a large modulation phase difference at a resonant wavelength and can serve as a good optical modulator with low optical loss.

The meta-optical element 10 according to the exemplary embodiments of FIGS. 3A, 3B, 5, and 6 may have a Q factor of hundreds to thousands. For example, the Q factor of the meta-optical device 10 according to the exemplary embodiment may be 100 or more. The Q factor for transmittance in FIG. 6 has a very high value of about 1000, and the Q factor for reflectance may also be high in the same way as the Q factor for transmittance. For example, the Q factor for reflectance can have a value of about 300 to about 1500. However, it is not limited thereto, and the Q factor of reflectance or Q factor of transmittance may have a high value of 1000 or more.

In this way, the meta-optical device 10 according to an exemplary embodiment modulates the amplitude and/or phase of reflected light and/or transmitted light according to whether or not a stimulus is applied to the grating 210 through the active element AE. It is possible to provide a meta optical element 10 that can be provided. In addition, the meta-optical device 10 according to an exemplary embodiment can provide an optical modulator with a wide light modulation range, high-speed operation, and a high Q factor.

7 is a cross-sectional view of a meta-optical device according to an exemplary embodiment for optical pumping, and FIG. 8 is a conceptual diagram of an optical pumping measurement set-up of the meta-optical device according to an exemplary embodiment.

The characteristics of the grating 210 included in the meta-optical device 30 according to the exemplary embodiment may be changed through stimulation such as optical pumping. 7 may be a structure of a meta-optical device 30 according to an exemplary embodiment for light pumping, the waveguide layer 100 includes silicon nitride (Si ₃ N ₄ ), and the grating 210 is tungsten disulfide ( WS ₂ ), and the dielectric layer 230 may include aluminum oxide (Al ₂ O ₃ ). In addition, the substrate 60 may be disposed under the waveguide layer 100 and the dielectric layer 230 . The substrate 60 may include a light-transmitting material. For example, the substrate 60 may be a quartz substrate containing silicon dioxide (SiO ₂ ). In this case, the plurality of meta units 200 may include one protrusion of the substrate 60 , and the lattice 210 may be disposed in contact with one protrusion of the substrate 60 . Also, the grating 210 and the waveguide layer 100 may be separated by a dielectric layer 230. In the above example, light may be incident into the waveguide layer 100 through the substrate 60 .

Since optical pumping is used, the active element AE may include a light source instead of an electrode layer. The waveguide layer 100 may have a thickness at which incident light can be focused well, and this thickness may be appropriately selected. Light may be emitted after staying in the waveguide layer 100 as much as Q / 2π during resonance in the bonded mode, and the interaction of the light and the grating 210 may be as much as (λQ) / (2πn _g ). Here, λ is the wavelength of light, and n _g is the group index of the bonded mode light. If the grating 210 having a group refractive index has a nanometer-level thin structure, a high Q value can be obtained, and the interaction between light and the grating 210 can be increased by this amount. In the meta-optical element 30 of FIG. 7, the thickness of the protruding part of the waveguide layer 100 on which the meta unit 200 is disposed is set to 50 nm, and the radiation Q factor and the absorption Q factor are almost similar values can be matched with Under these conditions, when the light resonates, the reflectance or transmittance can be almost zero or a very small value, and accordingly, the scattering characteristics of the exciton absorption-capable state and the exciton-absorption inhibition state can be efficiently modulated. The thickness of the protruding portion is exemplary, and the thickness of the protruding portion may be appropriately selected according to various conditions.

Optical characteristics of the meta-optical device 30 according to the exemplary embodiment may be measured using pump/probe spectroscopy. In the experimental examples of FIGS. 7 and 8 , the grating 210 of the meta-optical element 30 may include WS ₂ , and the waveguide layer 100 may include silicon nitride (Si ₃ N ₄ ), and the waveguide layer The thickness of (100) may be about 300 nm, the dielectric layer 230 may include aluminum oxide (Al ₂ O ₃ ), and the thickness of the dielectric layer 230 may be about 5 nm. In the experimental examples of FIGS. 7 and 8 , a pump beam (B1) may be irradiated at an incident angle θ _p inclined by about 5.3 degrees in the vertical direction of the meta-optical element 30, and the pump beam (B1) may have a wavelength of about 532 nm, and the intensity of the pump beam B1 may be about 300 mW/mm ² . The bonded mode resonance wavelength of the meta-optical element 30 of FIGS. 7 and 8 may be about 615 nm. However, it is not limited thereto, and the intensity of the wavelength of the pump beam (B1), the intensity of the pump beam (B1), or the bonded mode resonance wavelength may vary depending on the configuration of the meta-optical element (30).

The pump beam B1 may serve to excite a sample (eg, the meta-optical device 30) to which the pump beam B1 is irradiated, and, for example, the grating 210 of the meta-optical device 30. ) can suppress the exciton absorption of the material containing it. Conversely, when the pump beam B1 is not irradiated, exciton absorption may be possible. A light source irradiating the pump beam B1 is one of the active elements AE, and may correspond to the first electrode 221 and the second electrode 222 described above, and light pumping through the pump beam B1 is an electrode layer. It can correspond to giving a potential difference using A probe beam B2 may be used to monitor changes in optical properties (eg, reflectance or transmittance, etc.) of the sample induced by the pump beam B1. The probe beam B2 may be incident on the meta-optical device 30 at an incident angle θ _i . The probe beam B2 comes from a super continuum light source, and thus may include light of various wavelengths. The probe beam B2 may pass through the first polarizer POL1 having a thickness direction of the meta-optical element 30 and a direction of about -45 degrees before entering the meta-optical element 30 . The probe beam B2 that has passed through the first polarizer POL1 may include both a transverse electric (TE-pol) mode and a transverse magnetic (TM-pol) mode. Light emitted after interacting with the meta optical element 30 may pass through the second polarizer POL2 having a direction of about 45 degrees to the thickness direction of the meta unit 200 . Since the directions of the first polarizer POL1 and the second polarizer POL2 are different from each other by 90 degrees, the component (0th-order diffraction mode, m=0) that passes directly without interacting with the meta-optical element 30 in the light It can be removed from light detection. Accordingly, scattering intensity according to the wavelength and the incident angle of the probe beam B2 may be measured.

9A is a graph of experimental results showing the scattering intensity according to the incident angle and light wavelength when the pump beam is not irradiated in FIG. 8, and FIG. It is a simulation result graph showing absorption, and FIG. 9c is a simulation result graph showing the incident angle θ _i , light wavelength, and light absorption when the pump beam is not irradiated in TM mode.

Referring to FIG. 9A, several branches showing strong scattering intensity can be identified, and each branch represents an n-order TE mode (n is an integer greater than or equal to 1) or an m-order TM mode (m is an integer greater than or equal to 1). can 9A shows a first order TE mode branch, a second order TE mode branch, a first order TM mode branch, and a second order TM mode branch. It is possible to check the scattering peak (peak) according to each wavelength according to different angles of incidence through the branch, the larger the scattering size may mean that a larger amount of light is scattered by the bonded mode resonance. The secondary TE mode branch has an incident angle of 17 degrees in the wavelength band of about 615 nm corresponding to the exciton of WS ₂ , and for incident light, exciton absorption is possible, and in this case, the scattering peak near the bonded mode resonance wavelength It can be seen that the linewidth of increases. In FIG. 9B , a branch representing TE mode absorption can be identified, and in FIG. 9C , a branch representing TM mode absorption can be identified. Here, in the second TE mode branch, light absorption may well occur in a wavelength band of about 615 nm corresponding to an absorption wavelength of an exciton of WS ₂ . As light absorption increases, resonance may not occur well. 9b and 9c, it can be seen that light absorption is high at a wavelength of about 615 nm regardless of the incident angle. This may be because the exciton resonance wavelength of the material included in the grating 210 of the meta-optical device 30 is around 615 nm. The second-order TE mode branch may be overlapped with exciton absorption (exciton resonance) in the wavelength band of about 615 nm, resulting in an increase in line width at an incident angle of about 17 degrees.

FIG. 10 is an enlarged graph of a secondary TM mode branch in the incident angle range of about 13 degrees to about 20 degrees and a wavelength band of about 590 nm to about 620 nm in FIG. 9A, and FIG. 11B is a simulation graph showing linewidth change according to wavelength when a pump beam is irradiated and when it is not irradiated.

In FIG. 11A , each dot may represent a line width value for light having different wavelengths and/or incident angles. 10 to 11B, when the pump beam B1 is not irradiated and the incident angle of the probe beam B2 is about 17 degrees, the secondary TM mode branch and exciton absorption may overlap. Here, exciton absorption is possible so that bonded mode resonance and exciton absorption (exciton resonance) can occur together, and whether exciton absorption is possible or whether exciton absorption is inhibited can be controlled by stimulation through an active element (AE). When exciton absorption is possible, the line width of the light absorption and scattering peak may increase, and in this case, the line width of the scattering peak may be about 4 nm to about 6 nm. Absorption by exciton resonance can increase the non-radiative decay. Conversely, when the pump beam (B1) is irradiated, exciton absorption is suppressed (exciton resonance is suppressed), light absorption can be reduced at a predetermined wavelength as confirmed in FIG. 2, and bonded mode resonance can occur better . As the absorption of excitons is suppressed, the line width may be lower than when the exciton is absorbed, and the change rate of the line width may be very low. For example, the line width of the scattering peak may be about 0.5 nm to about 1.5 nm. Accordingly, the meta optical element 30 having a high Q factor can be implemented. The line width when the pump beam B1 is irradiated may be smaller than the line width when the pump beam B1 is not irradiated.

As described above, using the light pumping structure, an exciton absorption enabled/suppressed state may be implemented depending on whether the pump beam B1 is irradiated, and through this, the optical characteristics, reflectance, or transmittance of the meta optical element 30 may be adjusted. The meta-optical element 30 according to an exemplary embodiment may be implemented as an active element by including a light pumping structure having a light source as an active element AE, has a wide light modulation range, can operate at high speed, and has a high An optical modulator having a Q factor may be provided.

12 is a plan view showing meta units arranged in 2D.

Referring to FIG. 12 , when the meta units 200 of the meta optical element 10 according to the exemplary embodiment are arranged one-dimensionally, the plurality of meta units 200 are reflected in a direction (first direction) in which they are arranged. light can be modulated. When the meta units 200 are arranged two-dimensionally, light reflected in two directions (a first direction and a second direction) of the meta unit 200 may be modulated. In this case, the two directions may be perpendicular to each other, and the two directions may be perpendicular to the thickness direction of the meta-optical element 10 .

13 is a graph showing the relative permittivity according to the wavelength of a grating including WS ₂ .

Referring to FIG. 13 , the refractive index of a material included in the grating 210 may be changed due to an exciton absorption enabled state or an exciton absorption inhibited state, and a resonant wavelength may be shifted according to the refractive index change. In a region having a wavelength greater than about 615 nm, which is the exciton resonance wavelength (blue-shift region), the real part of the dielectric constant in the exciton absorption enabled state may be greater than the real part of the dielectric constant in the exciton absorption inhibited state. . Accordingly, in the blue shift region, when exciton absorption is suppressed by applying a stimulus, the refractive index of the grating 210 including WS ₂ may be lowered. As the refractive index is lowered, the bonded mode resonance wavelength may be reduced, that is, the resonance wavelength may be blue-shifted.

In a region having a wavelength smaller than about 615 nm, which is the exciton resonance wavelength (red-shift region), the real part of the dielectric constant in the exciton absorption enabled state may be smaller than the dielectric constant in the exciton absorption inhibited state. . Therefore, in the red shift region, when exciton absorption is suppressed by applying a stimulus, the refractive index of the grating 210 including WS ₂ may be increased. As the refractive index decreases, the bonded mode resonance wavelength may increase, that is, the resonance wavelength may be red-shifted.

14A to 14E are diagrams illustrating a method of manufacturing a meta-optical device according to an exemplary embodiment, and FIG. 15 is a photomicrograph showing a plan view of the manufactured meta-optical device.

A method of manufacturing a meta-optical device 10 according to an exemplary embodiment includes depositing a waveguide layer 100 on a substrate 50, depositing a first electrode 221 on the waveguide layer 100, Transferring the lattice material layer 210l including the lattice material onto the first electrode 221, patterning the lattice material layer to form a lattice structure, depositing a capping layer on the lattice structure, and capping It may include depositing a second electrode 222 on the layer.

According to FIG. 14A , a waveguide layer 100 may be deposited on a prepared substrate 50 . The waveguide layer 100 may be deposited using at least one of several deposition methods, for example, physical vapor deposition (PVD), chemical vapor deposition (CVD), and plasma chemical vapor deposition. Deposition methods such as (Plasma Enhanced Chemical Vapor Deposition, PECVD) and Atomic Layer Deposition (ALD) may be used.

According to FIG. 14B , a first electrode 221 may be deposited on the waveguide layer 100 . The first electrode 221 may be deposited using at least one of several deposition methods, and the exemplary deposition method described above may be used.

Referring to FIG. 14C , the grid material layer 210l may be transferred on the first electrode 221 . The transfer may be deposited using at least one of several deposition methods, and the exemplary deposition methods described above may be used. Alternatively, a precursor film of the grid material may be transferred to the grid material layer 210l through spin coating or the like combined with another material. However, it is not limited thereto and various transfer methods may be used.

Referring to FIG. 14D , a lattice structure including a lattice 210 may be formed by patterning a lattice material layer. In order to pattern the grid material layer 210l, lithography, an etching technique, or the like may be used. Lithography includes, for example, photolithography, and after a photo mask or the like is disposed, light may be emitted in a direction perpendicular to the substrate 50 to form a desired pattern structure. Alternatively, the etching technique may include, for example, dry etching, wet etching, or reactive ion etching (RIE). A desired pattern structure may be formed using etching. However, it is not limited to the above-described example, and a lattice structure may be formed using various patterning methods.

In the step of patterning the lattice structure to form the lattice structure, the lattice material layer and the first electrode 221 may be removed except for a portion where the lattice 210 is formed. In addition, a portion of the waveguide layer 100 may be removed except for a portion where the grating 210 is formed. A lattice structure in which the period Λ between each lattice 210, the height t of each meta unit 200, and/or the width w of each meta unit 200 is constant may be formed. However, it is not limited thereto, and one region may be formed such that at least one of the period (Λ) between the grids 210, the height (t) of the meta unit 200, or the width (w) of the meta unit 200 is different. may be

According to FIG. 14E , the capping layer and the second electrode 222 may be sequentially deposited. The capping layer may be a layer including a dielectric material and may serve to electrically insulate the first electrode 221 and the second electrode 222 . The capping layer and the second electrode 222 may be deposited using at least one of several deposition methods, and the exemplary deposition method described above may be used.

A meta-optical device 10 including a nanostructure as shown in FIG. 15 can be manufactured through the method of manufacturing the meta-optical device 10 illustrated in FIGS. According to FIG. 15 , the period Λ of the manufactured meta-optical device 10 may be about 300 nm to about 400 nm. However, the period Λ of the manufactured meta-optical element 10 is not limited to the above range.

16 is a conceptual diagram illustrating a beam steering device including a meta-optical device according to an exemplary embodiment.

Referring to FIG. 16 , a beam may be steered in a one-dimensional direction using a beam steering element 1000A. That is, the beam may be steered in the first direction DD1 toward a predetermined object OBJ. The beam steering device 1000A may include a one-dimensional array of a plurality of meta-optical devices 10 and 30 according to example embodiments.

17 is a conceptual diagram for explaining a beam steering device including a meta-optical device according to an exemplary embodiment.

Referring to FIG. 17 , a beam may be steered in a two-dimensional direction using a beam steering element 1000B. That is, the beam may be steered toward a predetermined object OBJ in the first direction DD1 and in the second direction DD2 perpendicular thereto. The beam steering device 1000B may include a two-dimensional array of a plurality of meta-optical devices 10 and 30 according to example embodiments. The beam steering elements 1000A and 1000B described with reference to FIGS. 16 and 17 may be a non-mechanical beam scanning apparatus.

18 is a block diagram for explaining an overall system of an electronic device including a beam steering device to which a meta-optical device is applied according to an exemplary embodiment.

Referring to FIG. 18 , the electronic device A1 may include a beam steering element 1000 . The beam steering device 1000 may include meta-optical devices 10 and 30 according to the exemplary embodiments described with reference to FIGS. 1 to 15 . The electronic device A1 may include a light source unit within the beam steering element 1000 or may include a light source unit provided separately from the beam steering element 1000 . The electronic device A1 may include a detector 1100 for detecting light steered by the beam steering device 1000 and reflected by a subject (not shown). The detection unit 1100 may include a plurality of light detection elements and may further include other optical members. In addition, the electronic device A1 may further include a circuit unit 1200 connected to at least one of the beam steering element 1000 and the detection unit 1100 . The circuit unit 1200 may include an arithmetic unit that acquires and calculates data, and may further include a driving unit and a control unit. In addition, the circuit unit 1200 may further include a power supply unit and a memory.

18 illustrates a case where the electronic device A1 includes the beam steering element 1000 and the detection unit 1100 in one device, but the beam steering element 1000 and the detection unit 1100 are not provided as one device. Instead, it may be provided separately in a separate device. In addition, the circuit unit 1200 may be connected to the beam steering element 1000 or the detection unit 1100 through wireless communication without being wired. In addition, the configuration of FIG. 18 may be variously changed.

The meta-optical elements 10 and 30 according to the embodiment described above or a beam steering element including the same may be applied to various electronic devices. For example, the beam steering element may be applied to a Light Detection And Ranging (LiDAR) device. The LiDAR device may be a phase-shift device or a time-of-flight (TOF) device. In addition, the meta-optical element 10, 30 or a beam steering element including the same according to the embodiment is a smart phone, a wearable device (such as a glasses-type device implementing augmented reality and virtual reality), the Internet of Things (IoT) Devices, home appliances, tablet PCs (Personal Computers), PDAs (Personal Digital Assistants), PMPs (Portable Multimedia Players), navigation, drones, robots, unmanned vehicles, autonomous vehicles, advanced driver assistance systems ( It can be mounted on electronic devices such as Advanced Drivers Assistance System (ADAS).

19 and 20 are conceptual views illustrating cases in which a LiDAR device including a meta-optical device according to an exemplary embodiment is applied to a vehicle. 19 is a view viewed from the side, and FIG. 20 is a view viewed from above.

Referring to FIG. 19 , a LiDAR device 71 may be applied to a vehicle 70 , and information on a subject 80 may be obtained using the LiDAR device 71 . The vehicle 70 may be an automobile having an autonomous driving function. An object or person in the direction in which the vehicle 70 is moving, that is, the subject 80 may be detected using the LiDAR device 71 . In addition, the distance to the subject 80 can be measured using information such as a time difference between the transmission signal and the detection signal. Also, as shown in FIG. 20 , information on a nearby subject 81 and a distant subject 82 within a scanning range may be acquired.

The meta-optical elements 10 and 30 according to various embodiments may be applied to various electronic devices other than LiDAR. For example, if the meta-optical elements 10 and 30 according to various embodiments are used, 3-dimensional information of space and subject can be acquired through scanning, so it can be applied to a 3-dimensional image acquisition device or a 3-dimensional camera. . In addition, the meta-optical elements 10 and 30 may be applied to a holographic display device and a structured light generating device. In addition, the meta-optical elements 10 and 30 may be applied to various optical components/devices such as various beam scanning devices, hologram generating devices, light coupling devices, variable focus lenses, and depth sensors. In addition, the meta-optical elements 10 and 30 can be applied to various fields in which a "meta surface" or a "meta structure" is used. In addition, the meta-optical elements 10 and 30 according to the exemplary embodiment and the electronic device including them may be applied for various purposes in various optical and electronic device fields.

Fig. 21 is a block diagram showing a schematic configuration of an electronic device according to an exemplary embodiment.

Referring to FIG. 21 , in a network environment 2200, an electronic device 2201 communicates with another electronic device 2202 through a first network 2298 (such as a short-distance wireless communication network) or through a second network 2299. It may communicate with another electronic device 2204 and/or server 2208 via (a long-distance wireless communication network, etc.). The electronic device 2201 may communicate with the electronic device 2204 through the server 2208 . The electronic device 2201 includes a processor 2220, a memory 2230, an input device 2250, an audio output device 2255, a display device 2260, an audio module 2270, a sensor module 2210, and an interface 2277. ), haptic module 2279, camera module 2280, power management module 2288, battery 2289, communication module 2290, subscriber identification module 2296, and/or antenna module 2297. can In the electronic device 2201, some of these components (such as the display device 2260) may be omitted or other components may be added. Some of these components can be implemented as a single integrated circuit. For example, the fingerprint sensor 2211 of the sensor module 2210, an iris sensor, or an illumination sensor may be implemented by being embedded in the display device 2260 (display, etc.).

The processor 2220 may execute software (program 2240, etc.) to control one or a plurality of other components (hardware, software components, etc.) of the electronic device 2201 connected to the processor 2220, and , various data processing or calculations can be performed. As part of data processing or computation, processor 2220 loads commands and/or data received from other components (sensor module 2210, communication module 2290, etc.) into volatile memory 2232 and Commands and/or data stored in 2232 may be processed, and resulting data may be stored in non-volatile memory 2234. The processor 2220 includes a main processor 2221 (central processing unit, application processor, etc.) and a secondary processor 2223 (graphics processing unit, image signal processor, sensor hub processor, communication processor, etc.) can include The auxiliary processor 2223 may use less power than the main processor 2221 and perform specialized functions.

The secondary processor 2223 may take the place of the main processor 2221 while the main processor 2221 is in an inactive state (sleep state), or the main processor 2221 while the main processor 2221 is in an active state (application execution state). Together with the processor 2221, functions and/or states related to some of the components (display device 2260, sensor module 2210, communication module 2290, etc.) of the electronic device 2201 may be controlled. can The auxiliary processor 2223 (image signal processor, communication processor, etc.) may be implemented as a part of other functionally related components (camera module 2280, communication module 2290, etc.).

The memory 2230 may store various data required by components (processor 2220, sensor module 2276, etc.) of the electronic device 2201. Data may include, for example, input data and/or output data for software (such as program 2240) and instructions related thereto. The memory 2230 may include a volatile memory 2232 and/or a non-volatile memory 2234 .

The program 2240 may be stored as software in the memory 2230 and may include an operating system 2242 , middleware 2244 , and/or applications 2246 .

The input device 2250 may receive a command and/or data to be used by a component (such as the processor 2220) of the electronic device 2201 from the outside of the electronic device 2201 (such as a user). The input device 2250 may include a microphone, mouse, keyboard, and/or digital pen (such as a stylus pen).

The sound output device 2255 may output sound signals to the outside of the electronic device 2201 . The audio output device 2255 may include a speaker and/or a receiver. The speaker can be used for general purposes, such as multimedia playback or recording playback, and the receiver can be used to receive an incoming call. The receiver may be incorporated as a part of the speaker or implemented as an independent separate device.

The display device 2260 can visually provide information to the outside of the electronic device 2201 . The display device 2260 may include a display, a hologram device, or a projector and a control circuit for controlling the device. The display device 2260 may include a touch circuitry set to sense a touch and/or a sensor circuit (such as a pressure sensor) set to measure the strength of a force generated by a touch.

The audio module 2270 may convert sound into an electrical signal or vice versa. The audio module 2270 obtains sound through the input device 2250, the sound output device 2255, and/or another electronic device connected directly or wirelessly to the electronic device 2201 (such as the electronic device 2102). ) may output sound through a speaker and/or a headphone.

The sensor module 2210 detects an operating state (power, temperature, etc.) of the electronic device 2201 or an external environmental state (user state, etc.), and generates an electrical signal and/or data value corresponding to the detected state. can do. The sensor module 2210 may include a fingerprint sensor 2211, an acceleration sensor 2212, a position sensor 2213, a 3D sensor 2214, and the like, in addition to an iris sensor, a gyro sensor, an air pressure sensor, and a magnetic sensor. , a grip sensor, a proximity sensor, a color sensor, an IR (Infrared) sensor, a biological sensor, a temperature sensor, a humidity sensor, and/or an illuminance sensor.

The 3D sensor 2214 irradiates a predetermined light to an object and analyzes the light reflected from the object to sense the shape and motion of the object. Either one can be provided.

The interface 2277 may support one or more specified protocols that may be used to directly or wirelessly connect the electronic device 2201 to another electronic device (e.g., the electronic device 2102). The interface 2277 may include a high definition multimedia interface (HDMI), a universal serial bus (USB) interface, an SD card interface, and/or an audio interface.

The connection terminal 2278 may include a connector through which the electronic device 2201 may be physically connected to another electronic device (e.g., the electronic device 2102). The connection terminal 2278 may include an HDMI connector, a USB connector, an SD card connector, and/or an audio connector (such as a headphone connector).

The haptic module 2279 may convert electrical signals into mechanical stimuli (vibration, movement, etc.) or electrical stimuli that the user can perceive through tactile or kinesthetic senses. The haptic module 2279 may include a motor, a piezoelectric element, and/or an electrical stimulation device.

The camera module 2280 may capture still images and moving images. The camera module 2280 may include a lens assembly including one or more lenses, image sensors, image signal processors, and/or flashes. A lens assembly included in the camera module 2280 may collect light emitted from a subject that is an object of image capture, and any one of the meta-optical elements 10 and 30 according to the above-described embodiments may be included in the lens assembly. can be included

The power management module 2288 may manage power supplied to the electronic device 2201 . The power management module 2288 may be implemented as part of a Power Management Integrated Circuit (PMIC).

The battery 2289 may supply power to components of the electronic device 2201 . The battery 2289 may include a non-rechargeable primary cell, a rechargeable secondary cell, and/or a fuel cell.

The communication module 2290 establishes a direct (wired) communication channel and / or wireless communication channel between the electronic device 2201 and other electronic devices (electronic device 2102, electronic device 2104, server 2108, etc.), And it can support communication through the established communication channel. The communication module 2290 may include one or more communication processors that operate independently of the processor 2220 (application processor, etc.) and support direct communication and/or wireless communication. The communication module 2290 includes a wireless communication module 2292 (cellular communication module, short-range wireless communication module, GNSS (Global Navigation Satellite System, etc.) communication module) and/or wired communication module 2294 (Local Area Network (LAN) communication). module, power line communication module, etc.). Among these communication modules, the corresponding communication module is a first network 2298 (a local area communication network such as Bluetooth, WiFi Direct, or IrDA (Infrared Data Association)) or a second network 2299 (cellular network, Internet, or computer network (LAN). , WAN, etc.) to communicate with other electronic devices. These various types of communication modules may be integrated into one component (single chip, etc.) or implemented as a plurality of separate components (multiple chips). The wireless communication module 2292 uses the subscriber information (International Mobile Subscriber Identifier (IMSI), etc.) stored in the subscriber identification module 2296 within a communication network such as the first network 2298 and/or the second network 2299. The electronic device 2201 can be identified and authenticated.

The antenna module 2297 may transmit or receive signals and/or power to the outside (other electronic devices, etc.). The antenna may include a radiator made of a conductive pattern formed on a substrate (PCB, etc.). The antenna module 2297 may include one or a plurality of antennas. When a plurality of antennas are included, an antenna suitable for a communication method used in a communication network such as the first network 2298 and/or the second network 2299 is selected from among the plurality of antennas by the communication module 2290. can Signals and/or power may be transmitted or received between the communication module 2290 and other electronic devices through the selected antenna. In addition to the antenna, other parts (RFIC, etc.) may be included as part of the antenna module 2297.

Some of the components are connected to each other through communication methods (bus, GPIO (General Purpose Input and Output), SPI (Serial Peripheral Interface), MIPI (Mobile Industry Processor Interface), etc.) and signal (command, data, etc.) ) are interchangeable.

Commands or data may be transmitted or received between the electronic device 2201 and the external electronic device 2204 through the server 2108 connected to the second network 2299 . The other electronic devices 2202 and 2204 may be the same as the electronic device 2201 or different types of devices. All or part of the operations executed in the electronic device 2201 may be executed in one or more of the other electronic devices 2202 , 2204 , and 2208 . For example, when the electronic device 2201 needs to perform a function or service, it requests one or more other electronic devices to perform some or all of the function or service instead of executing the function or service by itself. can One or more other electronic devices receiving the request may execute an additional function or service related to the request and deliver the result of the execution to the electronic device 2201 . To this end, cloud computing, distributed computing, and/or client-server computing technologies may be used.

22 is a block diagram showing a schematic configuration of a camera module included in the electronic device of FIG. 21 as an example.

Referring to FIG. 22 , a camera module 2280 includes a lens assembly 2310, a flash 2320, an image sensor 2330, an image stabilizer 2340, a memory 2350 (buffer memory, etc.), and/or an image signal. A processor 2360 may be included. The lens assembly 2310 may collect light emitted from a subject, which is an image capturing target, and may include any one of the meta-optical elements 10 and 30 described above. The lens assembly 2310 may include one or more refractive lenses and a light modulator. The light modulator included therein may be designed as a lens having a predetermined phase profile and having a compensation structure to reduce phase discontinuity. The lens assembly 2310 including such an optical modulator may realize desired optical performance and have a short optical length.

The camera module 2280 may further include actuators. For example, the actuator may drive positions of lens elements constituting the lens assembly 2310 for zooming and/or autofocus (AF) and may adjust a separation distance between the lens elements.

The camera module 2280 may include a plurality of lens assemblies 2310, and in this case, the camera module 2280 may be a dual camera, a 360 degree camera, or a spherical camera. Some of the plurality of lens assemblies 2310 may have the same lens properties (angle of view, focal length, auto focus, F number, optical zoom, etc.) or different lens properties. The lens assembly 2310 may include a wide-angle lens or a telephoto lens.

The flash 2320 may emit light used to enhance light emitted or reflected from a subject. The flash 2320 may include one or more light emitting diodes (Red-Green-Blue (RGB) LED, White LED, Infrared LED, Ultraviolet LED, etc.), and/or a Xenon Lamp. The image sensor 2330 may obtain an image corresponding to the subject by converting light emitted or reflected from the subject and transmitted through the lens assembly 2310 into an electrical signal. The image sensor 2330 may include one or a plurality of sensors selected from among image sensors having different properties, such as an RGB sensor, a black and white (BW) sensor, an IR sensor, or a UV sensor. Each of the sensors included in the image sensor 2330 may be implemented as a Charged Coupled Device (CCD) sensor and/or a Complementary Metal Oxide Semiconductor (CMOS) sensor.

The image stabilizer 2340 moves one or a plurality of lenses or image sensors 2330 included in the lens assembly 2310 in a specific direction in response to movement of the camera module 2280 or the electronic device 2301 including the same. Alternatively, the operation characteristics of the image sensor 2330 may be controlled (adjustment of read-out timing, etc.) so that negative effects caused by motion may be compensated for. The image stabilizer 2340 detects the movement of the camera module 2280 or the electronic device 2301 using a gyro sensor (not shown) or an acceleration sensor (not shown) disposed inside or outside the camera module 2280. can The image stabilizer 2340 may be implemented optically.

The memory 2350 may store some or all data of an image acquired through the image sensor 2330 for a next image processing task. For example, when a plurality of images are acquired at high speed, the acquired original data (Bayer-patterned data, high-resolution data, etc.) is stored in the memory 2350, only low-resolution images are displayed, and then selected (user selection, etc.) It can be used to cause the original data of the image to be passed to the image signal processor 2360. The memory 2350 may be integrated into the memory 2230 of the electronic device 2201 or may be configured as a separate memory operated independently.

The image signal processor 2360 may perform one or more image processes on an image acquired through the image sensor 2330 or image data stored in the memory 2350 . One or more image processing may include depth map generation, 3D modeling, panorama generation, feature point extraction, image synthesis, and/or image compensation (noise reduction, resolution adjustment, brightness adjustment, blurring, sharpening ( sharpening, softening, etc.). The image signal processor 2360 may perform control (exposure time control, read-out timing control, etc.) for elements included in the camera module 2280 (such as the image sensor 2330). Images processed by the image signal processor 2360 are stored again in the memory 2350 for further processing or are stored in the external components of the camera module 2280 (memory 2230, display device 2260, electronic device 2202). , the electronic device 2204, the server 2208, etc.). The image signal processor 2360 may be integrated into the processor 2220 or may be configured as a separate processor that operates independently of the processor 2220. When the image signal processor 2360 is configured as a separate processor from the processor 2220, the image processed by the image signal processor 2360 undergoes additional image processing by the processor 2220 and then displays the display device 2260. can be displayed through

The electronic device 2201 may include a plurality of camera modules 2280 each having different properties or functions. In this case, one of the plurality of camera modules 2280 may be a wide-angle camera and the other may be a telephoto camera. Similarly, one of the plurality of camera modules 2280 may be a front camera and the other may be a rear camera.

FIG. 23 is a block diagram showing a schematic configuration of a 3D sensor included in the electronic device of FIG. 21 .

The 3D sensor 2214 senses the shape, motion, etc. of the object by irradiating a predetermined light onto the object and receiving and analyzing light reflected from the object. The 3D sensor 2214 includes a light source 2420, a light modulator 2410, a light detector 2430, a signal processor 2440, and a memory 2450. As the light modulator 2410, any one of the meta-optical elements 10 and 30 according to the above-described embodiments may be employed, and a target phase delay profile may be set to function as a beam deflector or a beam shaper.

The light source 2420 emits light to be used for analyzing the shape or position of an object. The light source 2420 may include a light source that generates and emits light of a small wavelength. The light source 2420 is a laser diode (LD), a light emitting diode (LED), or a super luminescent diode (SLD) that generates and irradiates light of a wavelength band suitable for analyzing the position and shape of an object, for example, light of an infrared band wavelength. A light source may be included. The light source 2420 may be a tunable laser diode. The light source 2420 may generate and emit light of a plurality of different wavelength bands. The light source 2420 may generate and emit pulsed light or continuous light.

The light modulator 2410 modulates light emitted from the light source 2420 and transmits the modulated light to an object. When the light modulator 2410 is a beam deflector, the light modulator 2410 may deflect incident light in a predetermined direction to direct it toward an object. When the light modulator 2410 is a beam shaper, the light modulator 2410 modulates the incident light to have a distribution having a predetermined pattern. The light modulator 2410 may form structured light suitable for 3D shape analysis.

As described above, the optical modulator 2410 may implement a continuous phase delay profile by setting the phase delay variance (∂φ/∂λ) to 0, a positive number, or a negative number. Accordingly, it is possible to perform achromatic light modulation without wavelength variation. Alternatively, the deviation according to the wavelength may be strengthened, and the deflection direction may be different for each wavelength, or a different beam pattern may be formed for each wavelength to be irradiated to the target object.

The photodetector 2430 receives the reflected light of the light irradiated to the object via the light modulator 2410 . The photodetector 24430 may include an array of a plurality of sensors for sensing light or may include only one sensor.

The signal processing unit 2440 may analyze the shape of the object by processing the signal sensed by the light detection unit 2430 . The signal processing unit 2440 may analyze the 3D shape including the depth position of the object.

For 3D shape analysis, an operation for measuring the time of flight of light may be performed. Various algorithms can be used to measure the optical time-of-flight. For example, in the direct time measurement method, a distance is obtained by projecting pulsed light onto an object and measuring the time for the light to return after being reflected by the object with a timer. In the correlation method, pulsed light is projected onto an object and a distance is measured from brightness of reflected light reflected from the object and returned. The phase delay measurement method is a method of projecting continuous wave light such as a sine wave onto an object and detecting a phase difference of reflected light that is reflected back and converting it into a distance.

When the structured light is irradiated to the object, the depth position of the object may be calculated from a result of comparison with a pattern change of the structured light reflected from the object, that is, an incident structured light pattern. Depth information of the object may be extracted by tracking a pattern change for each coordinate of the structured light reflected from the object, and 3D information related to the shape and motion of the object may be extracted therefrom.

The memory 2450 may store programs and other data required for operation of the signal processing unit 2440 .

An operation result of the signal processing unit 2440, that is, information on the shape and position of the object may be transmitted to another unit within the electronic device 2200 or to another electronic device. For example, this information may be used by applications 2246 stored in memory 2230 . Another electronic device to which the result is transmitted may be a display device or a printer that outputs the result. In addition, self-driving devices such as unmanned cars, self-driving cars, robots, and drones, smart phones, smart watches, mobile phones, personal digital assistants (PDAs), laptops, PCs, and various wearables (wearable) devices, other mobile or non-mobile computing devices, and Internet of Things devices, but are not limited thereto.

Fig. 24 is a block diagram showing a schematic configuration of an electronic device according to an exemplary embodiment.

The electronic device 3000 of FIG. 24 may be a glasses-type augmented reality (AR) device. The electronic device 3000 includes a display engine 3400, a processor 3300, an eye tracking sensor 3100, an interface 3500, and a memory 3220.

The processor 3300 may control overall operations of the augmented reality device including the display engine 3400 by driving an operating system or an application program, and may process and calculate various data including image data. For example, the processor 3300 may process image data including a left eye virtual image and a right eye virtual image rendered to have binocular parallax.

The interface 3500 inputs and outputs data or operation commands from the outside, and may include, for example, a user interface such as a touch pad, a controller, and operation buttons that can be operated by a user. The interface 3500 includes a wired communication module such as a USB module or a wireless communication module such as Bluetooth, and may receive user manipulation information or data of a virtual image transmitted from an interface included in an external device through them.

The memory 3200 may include built-in memory such as volatile memory or non-volatile memory. The memory 3200 may store various data, programs or applications for driving and controlling the augmented reality device under the control of the processor 3300 and input/output signals or data of virtual images.

The display engine 3400 is configured to generate light of a virtual image by receiving image data generated by the processor 3300, and includes a left eye optical engine 3410 and a right eye optical engine 3420. Each of the left eye optical engine 3410 and the right eye optical engine 3420 is composed of a light source that outputs light and a display panel that forms a virtual image using light output from the light source, and has the same function as a small projector. The light source can be implemented with, for example, LED, and the display panel can be implemented with, for example, Liquid Crystal on Silicon (LCoS).

The gaze tracking sensor 3100 may be mounted at a location where a pupil of a user wearing an augmented reality device may be tracked, and may transmit a signal corresponding to information on the gaze of the user to the processor 3100 . The gaze tracking sensor 3100 may detect gaze information such as a gaze direction toward which the user's eyes are directed, a pupil position of the user's eyes, or coordinates of a central point of the pupil. The processor 3300 may determine an eye movement type based on the user's eye gaze information detected by the gaze tracking sensor 3100 . For example, the processor 3300 performs fixation to look at a certain place, pursuit to follow a moving object, and quick gaze from one gaze point to another based on gaze information obtained from the gaze tracking sensor. It is possible to determine various types of gaze movement including a saccade in which the gaze moves.

FIG. 25 is a block diagram showing a schematic configuration of an eye tracking sensor included in the electronic device of FIG. 24 .

The gaze tracking sensor 3100 includes an illumination optical unit 3110, a detection optical unit 3120, a signal processing unit 3150, and a memory 3160. The illumination optical unit 3110 may include a light source that radiates light, for example, infrared light, to a location of an object (the user's eye). The detection optical unit 3150 detects the reflected light and may include a meta lens 3130 and a sensor unit 3140. The signal processing unit 3150 calculates the pupil position of the user's eye from the result sensed by the detection optical unit 3120.

As the meta lens 3130, any one of the meta optical elements 10 and 30 according to the above-described embodiments, a combination thereof, or a modified example may be used. The meta lens 3130 may condense light from an object onto the sensor unit 3140 . In the gaze tracking sensor 3100 positioned very close to the user's eyes, an incident angle of light incident on the sensor unit 3140 may be greater than, for example, 30 degrees or greater. The meta lens 3130 has a structure including a compensation region and reduces efficiency degradation even for light having a large incident angle. Accordingly, accuracy of gaze tracking may be increased.

The glasses-type device may be used as a glasses-type virtual reality (VR) device as well as an augmented reality (AR) device, and may track a user's gaze with respect to a VR image provided from the device.

The above-described meta-optical elements 10 and 30 and the electronic device including them have been described with reference to the embodiment shown in the drawings, but this is merely an example, and various modifications can be made from this to those skilled in the art. and other equivalent embodiments are possible. Therefore, the disclosed embodiments should be considered from an illustrative rather than a limiting point of view. The scope of this specification is shown in the claims rather than the foregoing description, and all differences within the equivalent range should be construed as being included.

10,30: meta-optical element 50,60: substrate
100: waveguide layer 110: first surface
120: second side 200: multiple metaunits
210 grid 221 first electrode
222: second electrode 230: dielectric layer
Λ: period t: height of metaunit
w: the width of the metaunit
AE: active element

Claims (20)

a waveguide layer including a first surface and a second surface facing the first surface; and
It is disposed on the waveguide layer and includes a grating including a two-dimensional material, a first electrode disposed under the grating, a dielectric layer disposed above the grating, and a second electrode disposed on the dielectric layer, respectively. A plurality of meta units; including,
A meta-optical device in which a permittivity of the grating is changed and a reflectance of incident light is changed when a voltage is applied to the first electrode and the second electrode. According to claim 1,
The change in the permittivity of the lattice is due to a change in the exciton density of the lattice,
The meta-optical element of claim 1, wherein the voltage has a size that generates exciton resonance of the lattice. According to claim 1,
The grids included in each of the plurality of meta units are spaced apart from each other in a first direction,
The waveguide layer is a meta-optical element configured such that the light diffracted by the grating is reflected between the first surface and the second surface to form guided mode resonance toward a first direction in which the grating is arranged . According to claim 3,
The plurality of meta units,
Meta-optical elements arranged in the first direction and in a second direction perpendicular to the first direction. According to claim 3,
The light includes light of a first wavelength that is an exciton absorption wavelength of a material included in the grating and is a bonded mode resonance wavelength,
The meta-optical element in which the period of the grating is smaller than the first wavelength and high order mode diffraction is blocked. According to claim 5,
When light of a second wavelength greater than the first wavelength is incident, the bonded mode resonance wavelength is blue-shifted,
When light of a third wavelength smaller than the first wavelength is incident, the meta-optical element in which the bonded mode resonance wavelength is red-shifted (red-shift). According to claim 1,
The lattice includes at least one of graphene, transition metal dichalcogenide (TMDc), and a two-dimensional semiconductor material,
The wavelength of the light is 10 nm to 3000 μm meta-optical device. According to claim 1,
The grid includes tungsten disulfide (WS ₂ ),
The wavelength of the light is 600 nm to 630 nm meta-optical device. According to claim 1,
Each of the plurality of meta units,
A meta-optical element to which voltages are independently applied through the first electrode and the second electrode included in each of the plurality of meta-units. According to claim 9,
At least one of the reflectance or transmittance of the light has a difference of 20% or more between a case where a voltage is applied and a case where a voltage is not applied. According to claim 1,
The meta-optical element has a Q-factor of 100 or more. According to claim 1,
The first electrode or the second electrode,
at least one of indium tin oxide (ITO), aluminum zinc oxide (AZO), indium zinc oxide (IZO), or indium gallium zinc oxide (IGZO);
The waveguide layer includes at least one of silicon oxide (SiO ₂ ), hafnium oxide (HfO ₂ ), titanium oxide (TiO ₂ ), or aluminum oxide (Al ₂ O ₃ ). According to claim 1,
A second electrode included in one meta-unit among the plurality of meta-units surrounds the upper and side surfaces of the lattice included in the one meta-unit;
A meta-optical element extending along the waveguide layer. According to claim 1,
The waveguide layer,
A meta-optical element in the form of at least one of a slab, ridge, channel, strip-loaded, buried, or photonic crystal. According to claim 1,
The meta-optical element is a meta-optical element capable of electrical tuning. waveguide layer; and
A plurality of metaunits disposed on the waveguide layer and each including a lattice comprising a two-dimensional material and an active element for applying a stimulus to the lattice;
When a stimulus is applied to the grating corresponding to the active element by the active element, the permittivity of the grating changes and the reflectance of incident light changes. According to claim 16,
The active element is
Generating exciton resonance in the two-dimensional material,
A meta-optical device including at least one of an electrical gating structure, an optical stimulation structure, a chemical reaction structure, a magnetic field application structure, a heating structure, and a mechanical deformation structure. According to claim 16,
The plurality of meta units,
A meta-optical element to which stimuli are independently applied by the active element included in each of the plurality of meta-units. According to claim 16,
Depending on whether the active element is stimulated, at least one of the reflectance or transmittance for the light has a difference of 20% or more,
The meta-optical element has a Q factor of 100 or more. An electronic device comprising a; meta-optical element according to any one of claims 1 to 19.

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