Device for plasmonic nanoantenna beam phase shifter and redirector

Abstract

A pixel for producing an optical phase change is provided, the pixel comprising a transparent electrical insulator; a first electrical conductor disposed on the transparent electrical insulator, comprising an antenna assembly and a connector assembly; an electrical insulator disposed on the first electrical conductor; a transparent semiconductor disposed on the electrical insulator; and a second electrical conductor disposed on the transparent semiconductor. The transparent semiconductor is thick enough to prevent plasma resonance at the interface between the transparent semiconductor and the second electrical conductor.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit and priority of U.S. patent application No. 62 / 940,085, filed on November 25, 2019, entitled “Methods and Apparatus for Plasmonic Nanoantenna Beam Phase Shifters and Steering Devices,” and U.S. patent application No. 17 / 101,114, filed on November 23, 2020, entitled “Apparatus for Plasmonic Nanoantenna Beam Phase Shifters and Steering Devices,” which are incorporated by reference into this application. Technical Field

[0003] The present invention relates generally to optical and photonic devices and, more particularly, to a nanoscale material structure capable of shifting the phase of a beam of optical radiation. Background Art

[0004] Vehicles such as self-driving cars require improved sensors to detect their surroundings. LiDAR is a potential sensor technology in the market, but the use of LiDAR for the automotive market is challenging, the difficulty lies in how to steer the beam in a controlled direction away from the transmitter, or in how to control the interception direction of the beam on the receiver side (i.e., the direction in which the receiver is "looking" at the beam). Some implementations use mechanical moving parts, but these parts are bulky and may not be reliable when the vehicle is exposed to harsh mechanical and thermal environments. Therefore, there is still motivation in developing solid-state beam steering without moving parts.

[0005] A phased array is a beam-reflecting surface composed of pixels, each of which can apply a phase shift to a beam of electromagnetic radiation. If the size of the pixel is much smaller than the wavelength of the beam, the array can have large steering angles without creating multiple aliased beams. Another requirement for a phased array is that the pixels should only change the phase of the beam, not its amplitude. A change in the amplitude of the beam can cause distortion of the transmitted or captured light, thereby reducing the resolution of the steered beam and introducing stray light into the lidar. Ideally, the lidar transmitter should have a single beam that contrasts sharply with the stray light. Otherwise, it will not be possible to reliably illuminate and distinguish target objects in the scene.

[0006] This background information is provided to make known information believed by the applicant to be potentially relevant to the present invention. It is neither intended nor should be construed that any of the above information constitutes prior art against the present invention. Summary of the invention

[0007] The present invention relates to a nanoscale device that uses plasmon resonance to change the phase of a beam of incident optical radiation in response to an applied voltage without significantly affecting the amplitude of the beam. By combining a large number of devices into an array and applying a voltage pattern to each row of the array, different parts of the optical radiation beam can be controlled to experience different phase shifts, similar to a classical phased array.

[0008] The embodiment of the present invention aims to provide a pixel, which includes: a transparent electrical insulator (which may be a substrate or air); a first electrical conductor, which is arranged on the transparent electrical insulator, and the first electrical conductor includes an antenna component and a connector component; an electrical insulator, which is arranged on the first electrical conductor; a transparent semiconductor, which is arranged on the electrical insulator; and a second electrical conductor, which is arranged on the transparent semiconductor. The transparent semiconductor is thick enough to prevent the electrical insulator from exciting a plasma resonance at the interface with the first electrical conductor and the transparent semiconductor, and the plasma resonance occurs at the interface between the transparent semiconductor and the second electrical conductor.

[0009] In further or any of the above embodiments, the transparent semiconductor is sufficiently thick to prevent any joint plasmon resonance between a first set of interfaces between the first electrical conductor, the electrical insulator, and the transparent semiconductor and a second set of interfaces between the transparent semiconductor and the second electrical conductor.

[0010] In further or any of the above embodiments, the first electrical conductor, the electrical insulator, and the transparent semiconductor may support plasmon resonance after being excited by an incident light beam.

[0011] In further or any of the above embodiments, the first electrical conductor is partially or fully embedded in the electrical insulator.

[0012] In further or any of the above embodiments, the pixel comprises a second electrical insulator between the transparent semiconductor and the second electrical conductor.

[0013] In further or any of the above embodiments, the antenna assembly does not extend to the edge of the pixel, and an electrical connector assembly intersects the antenna assembly and extends to the edge of the pixel to enable external connection of the pixel.

[0014] In further or any of the above embodiments, the antenna assembly includes two lines separated by a gap and having a length shorter than the length of the pixel, the two lines being short enough not to overlap any portion of an adjacent intersection. The two lines intersect with corresponding connector assemblies extending to the edge of the pixel to enable external connection of the pixel. The connector assemblies extending on either side of the antenna may be short-circuited or connected to each other.

[0015] In further or any of the above embodiments, the antenna assembly is sized so that the pixel operates with light beams having wavelengths in the visible and infrared ranges.

[0016] In further or any of the above embodiments, the dimensions of the antenna assembly are selected to prevent significant interaction with adjacent pixels.

[0017] In further or any of the above embodiments, the transparent electrical insulator serves as a cladding for the remaining structure.

[0018] In further or any of the above embodiments, the antenna assembly functions as an antenna for optical radiation as well as a variable source of constant electrical potential.

[0019] In further or any of the above embodiments, the electrical insulator is thin enough so that an electric field from the antenna assembly is sensed by the transparent semiconductor.

[0020] In further or any of the above embodiments, the electrical insulator is thin enough to change the electric field of the antenna assembly, thereby changing the carrier density distribution in the transparent semiconductor.

[0021] In further or any of the above embodiments, the transparent semiconductor has a carrier density distribution that is affected by a field of the antenna assembly, the field including a static field and a time-varying field.

[0022] In further or any of the above embodiments, the second electrical conductor functions as a ground plane.

[0023] In further or any of the above embodiments, the antenna assembly, the electrical insulator, and the transparent semiconductor sustain plasmon resonance or electrical resonance when a beam of optical radiation is incident on the structure.

[0024] In further or any of the above embodiments, a resonant frequency of the plasmon resonance may be varied by applying an electrical potential between the antenna assembly and the second electrical conductor.

[0025] In further or any of the above embodiments, when an incident beam of radiation is transmitted or reflected at the resonant layer, a phase of the incident beam of optical radiation is shifted, the shift being affected by a potential applied between the antenna assembly and the second electrical conductor.

[0026] In further or any of the above embodiments, a phase shift of a reflected or transmitted beam of optical radiation is affected by an electrical potential applied between the antenna assembly and the second electrical conductor.

[0027] In further or any of the above embodiments, the resonance of the structure is split into a pair of resonances, wherein a first resonance is mainly caused by optoelectronic interaction in the gap between two wires of the antenna, and a second resonance is mainly caused by optoelectronic interaction between the connector components.

[0028] In further or any of the above embodiments, the resonance of the structure is divided into a pair of resonances with different wavelengths through aging-fracture interaction between the antenna and the connector, wherein the first resonance is mainly caused by the optoelectronic interaction in the gap between the two wires of the antenna, and the second resonance is mainly caused by the optoelectronic interaction between the connector components.

[0029] In further or any of the above embodiments, the pixel may have a first resonance and a second resonance, the first resonance being primarily caused by optoelectronic interaction in a gap between two wires of the antenna and the second resonance being caused by optoelectronic interaction between the connector components.

[0030] In further or any of the above embodiments, the first resonance and the second resonance may be at different wavelengths, and the magnitude of the reflectivity or transmittance of a beam of optical radiation having a wavelength between the first resonance and the second resonance is not significantly affected by an electrical potential applied between the antenna assembly and the second electrical conductor.

[0031] In further or any of the above embodiments, a magnitude of reflectivity or transmittance of the beam of optical radiation is not significantly affected by an electrical potential applied between the antenna assembly and the second electrical conductor.

[0032] In further or any of the above embodiments, the resonance of the structure is split into a pair of resonances having different wavelengths by an aging fracture interaction between the antenna and the connector.

[0033] In further or any of the above embodiments, the relative strength, wavelength, and spectral width of the resonances may be such that there is a region of the optical spectrum where the amplitude of the optical reflection is substantially constant.

[0034] In further or any of the above embodiments, the relative strength, wavelength and spectral width of the resonances can be such that the magnitude of the reflectivity or transmittance of a beam of optical radiation having a wavelength between the first resonance and the second resonance is not significantly affected by the electrical potential applied between the antenna assembly and the second electrical conductor.

[0035] In further or any of the above embodiments, the relative intensity, wavelength and spectral width of the resonance can be such that there is an optical spectral region wherein an electric potential applied between the antenna assembly and the second electrical conductor significantly affects the reflection phase or transmission phase of the optical radiation beam, but does not affect the reflection amplitude or transmission amplitude of the optical radiation beam.

[0036] In further or any of the above embodiments, the second electrical conductor is thin enough to be transparent over a range of optical wavelengths.

[0037] In further or any of the above embodiments, the second electrical conductor is omitted and the transparent semiconductor functions as a ground plane.

[0038] In further or any of the above embodiments, the thickness, width and length of the material are selected to produce a reflection spectrum in which the reflectivity of at least one wavelength of light radiation is similar to the reflectivity of at least one wavelength of light radiation within a carrier density range corresponding to a phase shift range as wide as at least 90 degrees at any carrier density of the transparent semiconductor.

[0039] Other embodiments are directed to providing a pixel array comprising a plurality of pixels arranged in a plurality of rows. Each pixel of the plurality of pixels is connected in series in each of the plurality of rows. Each pixel of the plurality of pixels comprises: a transparent electrical insulator; a first electrical conductor disposed on the transparent electrical insulator; a first electrical conductor comprising an antenna assembly and a connector assembly; an electrical insulator disposed on the first electrical conductor; a transparent semiconductor disposed on the electrical insulator; and a second electrical conductor disposed on the transparent semiconductor. The transparent semiconductor is sufficiently thick to prevent a plasma resonance primarily located near the electrical insulator from having a significant intensity at an interface between the transparent semiconductor and the second electrical conductor.

[0040] In further or any of the above embodiments, each row in the plurality of rows is independent of each other. Each row in the plurality of rows is capable of applying a different potential such that the pattern of applied potentials controls a beam of optical radiation incident on the array without significantly changing its amplitude distribution.

[0041] In further or any of the above embodiments, the dimensions of the antenna assembly are selected to prevent significant diffraction or side lobes of the beam of optical radiation from the interaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Reflection of a beam of optical radiation from a passive mirror or an active mirror is shown.

[0043] Figure 2 Shown is the reflection of optical radiation from an active mirror according to an embodiment.

[0044] Figure 3 A close-up of the active mirror consisting of an array of active pixels is shown.

[0045] Figure 4 An active mirror consisting of an array of active pixel rows is shown.

[0046] Figure 5 A close-up of a cross section of a single pixel is shown.

[0047] Figure 6 An embodiment of a single pixel with a single branch antenna is shown.

[0048] Figure 7 An embodiment of a single pixel with a dual branch antenna is shown.

[0049] Figure 8 A cross-sectional configuration of a single pixel according to an embodiment is shown.

[0050] Fig. 9 A cross-sectional configuration of a single pixel according to another embodiment is shown.

[0051] Fig.10 A cross-sectional configuration of a single pixel according to another embodiment is shown.

[0052] Fig.11 A cross-sectional configuration of a single pixel according to another embodiment is shown.

[0053] Fig.12 The effect of gate voltage on the semiconductor carrier density distribution is shown.

[0054] Fig.13 An embodiment is shown when the reflected light beam is phase shifted by a certain amount.

[0055] Fig.14a The example embodiment shows different N pert (carrier density) or different t pert (thickness of the disturbance layer), |Γ| (reflectivity) and λ 0 (wavelength of the incident light beam).

[0056] Fig.14b The example embodiment shows different N pert and t pert Under the condition of ∠Γ (the angle of the reflected light phase) of the device and λ 0 A curve graph of the relationship.

[0057] Fig.15 The geometric parameters of the pixel along its thickness and surface area are shown.

[0058] Fig.16 An embodiment is shown in which pixels are arranged in independent rows to form an array.

[0059] Fig.17 An array is shown in which a phase shift pattern is applied to steer the beam. DETAILED DESCRIPTION

[0060] As we all know, when a light beam is incident on a mirror, it will be reflected, and the reflection angle is the same as the angle of the incident light beam, and the reflection direction is perpendicular to the mirror. In order to redirect the incident light beam to a different angle, the mirror usually needs to be mechanically rotated.

[0061] Embodiments of the present invention relate to an electro-optical device that can be electronically tuned to steer or redirect an incident optical radiation beam to an exit direction at an angle relative to a surface of the device without mechanical intervention. The exit direction may be at an angle different from the angle of the incident beam.

[0062] According to an embodiment of the present invention, a beam of optical radiation can be redirected as a phased array comprising an array of pixels, each pixel array being capable of phase shifting the beam in response to an applied electrical potential.

[0063] In some embodiments of the invention, the device can reflect a light beam in an electrically tunable direction, thereby acting as an active mirror. In other embodiments, the device can transmit a light beam in an electrically tunable direction, thereby acting as an active phase plate.

[0064] Figure 1 It shows that in one embodiment of the present invention, a light beam 110 is incident on a mirror 120, and an outgoing light beam 130 is reflected at an angle 140 perpendicular to the surface, and the angle 140 is electronically tuned to be the same as the angle 150 of the incident light beam, for example simulating a common passive reflector.

[0065] Figure 2 2 shows an embodiment of the present invention, where a light beam 210 is incident on a reflector 220, and an outgoing light beam 230 is reflected at an angle 240 perpendicular to the surface, which angle 240 can be electronically tuned to be different from the angle 250 of the incident light beam. The solid lines across the light beams 110, 130, 210, 230 on both sides correspond to the optical phase front, while the dashed arrows indicate the propagation direction of the light beams.

[0066] An embodiment of the present invention includes a surface including an array of reflective pixels scaled for an optical wavelength, on which a light beam is incident, wherein each pixel can apply a phase shift to a portion of the light beam that interacts with it, causing the portion of the light beam to be reflected, with the direction of the reflection depending on the pattern of the phase shift applied to the portion of the light beam.

[0067] Although some optical phase-change pixels can be operated using plasma resonances in metal-insulator-metal (MIM) structures, the resonance of these MIM pixels is a combined mode of the nanoantenna and the ground plane, and the nanoantenna and the ground plane may require two voltages to control. Although the phase shift of the light beam leaving such a pixel can be tuned by controlling the applied voltage, this will also cause a change in the amplitude of the light beam. Therefore, the modulation of amplitude and phase is not independent. If the MIM pixels are set in a MIM array, the phase-shifted beam steering pattern is also applied to the MIM array, not only the beam is steered, but the amplitude profile of the beam is also modified. For some applications, a device that can control the light beam without introducing any amplitude modulation is required.

[0068] Figure 3 In one embodiment of the present invention, a surface includes an array of pixels 310, each of which can apply a phase shift to an incident light beam, and redirect the light beam as a whole according to the phase shift pattern applied to the light beam by the pixel. The cross section of the figure shows the pixel array 310. A close-up of an arbitrary size of a pixel column 320 is shown in the cross section on the right.

[0069] In an embodiment of the present invention, the pixels forming the array are electrically connected in one direction along the array and are independent of each other in another direction, so that all pixels in the same row are applied with the same potential, while the potentials of each row are independent of each other. For pixels that can shift the phase of the light beam, this type of arrangement is called a phased array. More specifically, it can also be called a one-dimensional phased array because the angle of the reflected light beam can only be rotated around 1 axis.

[0070] Figure 4 In the embodiment of the present invention, the pixels of the rows 410 along the X-axis are connected to each other and to a common potential, while the pixel columns 420 along the Z-axis are not connected to each other, so the potential of each row can be controlled independently. The potential on each row 410 can have a positive or negative polarity relative to the ground, or all the potentials can have the same polarity. Each potential is varied or electrically tuned in time to achieve beam control. Figure 4 The ground shown may be an absolute ground potential or may be offset by a DC voltage. In this embodiment, a light beam incident on the pixel array may be steered at an electrically tunable rotation angle about the x-axis.

[0071] In an embodiment of the present invention, each pixel may be a layered material structure, each layered material having specific conductive properties. The array as a whole may include a layered structure of materials, which is configured to, for example, include independent pixels. By ensuring that a sufficient distance, i.e., spacing, is maintained between pixels, the electromagnetic influence of adjacent pixels is negligible, thereby obtaining independence of the pixels from each other, except for pixels of voltage connectors. Each pixel includes an antenna, and the size of the pixel is comparable to the effective aperture of the antenna. It is known from antenna theory that the effective aperture of an antenna is generally larger than the physical range of the antenna. The effective aperture of an antenna is the area where the antenna exerts a significant electromagnetic influence. Therefore, in an embodiment of the present invention, the antenna in each pixel is smaller than the total area of ​​the pixel.

[0072] In an embodiment of the present invention, each pixel may be a structure that applies a phase shift to an incident beam of light radiation in response to an applied voltage potential.

[0073] Figure 5 It is shown that in an embodiment of the present invention, the pixel 510 is a structure capable of shifting the phase of the incident light beam of optical radiation. The first layer encountered by the light beam is an insulating cladding 520, which is used to protect the inner layer but is transparent to the incident light beam. Optionally, the insulating cladding 520 can be air, which is transparent and acts as an insulator, but not as a protective layer. The second layer is a metal 530, which is used as an antenna to intercept part of the light beam and is also used as an electric field source to modify the charge density distribution of the semiconductor at the fourth layer 550. The term "metal" in this specification adopts the definition used by semiconductor device manufacturers, which includes classical metals and alloys (such as gold, aluminum, copper, silver, titanium and their alloys) and compounds with metallic properties (such as compounds such as titanium nitride and tantalum nitride, also known as barrier metals). The third layer is an insulator 540, which is used as a barrier layer to maintain an electric field that can adjust the charge density distribution of the semiconductor. The insulator 540 can be an oxide-based, or other suitable materials can be used. The fourth layer is a semiconductor 550, whose charge carrier density distribution can be modulated according to the external electric field from the antenna metal, and the electric resonance or plasma resonance in the antenna 530 can be sensed. The semiconductor 550 can be optically transparent to the light beam. The fifth layer is metal, which acts as a ground plane 560 to maintain the applied voltage while protecting the structure. The above field is generated by a gate voltage 570 applied between the antenna metal 530 and the ground plane metal 560. The ground plane metal 560 is connected to an electrical ground 580.

[0074] An embodiment of the present invention is described below, wherein: Figure 5 The materials and possible dimensions along the y-axis are identified in:

[0075] The first layer 520 may be silicon oxide (SiO 2 ) which is thick enough to act as a transparent insulating cladding covering the entire surface of the structure.

[0076] - The second layer 530 can be 50nm thick gold (Au) and is used as an antenna and connector to other pixels or field sources.

[0077] - The third layer 540 may be 5 nm thick aluminum oxide (Al 2 O 3 ), hafnium dioxide (HfO 2 ), hafnium aluminum oxide, nitride or oxynitride, used as an electrical barrier. The barrier layer must be thin enough to allow the fourth layer to sense the electric field, and it must also be transparent, or very thin to appear transparent.

[0078] - The fourth layer 550 can be 100 nm thick indium tin oxide (ITO) or aluminum doped zinc oxide (AZO) used as a transparent semiconductor, which is thick enough to couple to the antenna conductor without plasmon coupling to the ground plane conductor.

[0079] - The fifth layer 560 may be gold (Au) which is thick enough to act as a reflector and electrical ground.

[0080] In an embodiment of the present invention, each pixel includes a structure in which the antenna metal is a single branch along the z-axis and is placed on a connector.

[0081] Figure 6 In one embodiment of the present invention, a pixel 610 is shown comprising a single branch of antenna metal 620 passing through a single connector 630. The size of the pixel structure can be selected to be large enough so that any effect of the antenna along the xz plane is negligible outside the pixel boundary. The size of the pixel structure can also be selected to be small enough so that any diffraction of the beam and grating lobes caused by the pixel size is negligible. A phased array composed of such small-sized pixels is alias-free because it mainly directs the output light into a single beam without other aliased beams.

[0082] In an embodiment of the present invention, each pixel may include a structure in which the antenna metal is composed of two branches instead of one branch, each branch being placed on a different connector, thereby forming a dipole antenna, the gap of which produces a strong electric field enhancement along the antenna axis. The width of the gap between the two branches can be selected to adjust the functional characteristics of the pixel structure. Specifically, reducing the gap width can increase the magnitude of the reflection coefficient of the pixel, while increasing the gap width can increase the phase range of the reflection coefficient of the pixel.

[0083] Figure 7In an embodiment of the present invention, a pixel 710 includes a metal dipole antenna made of two branches 720, each branch 720 passing through a different connector 730. The gap 740 between the two branches can contain an electric field along the z-axis, which can be tuned using a potential applied to each metal. The size of the pixel is such that any effect of the metal dipole antenna is negligible outside the pixel boundary. For greater clarity, Figure 7 A single antenna with two branches 720 is shown, rather than two separate antennas.

[0084] In the case of a single branch antenna structure, the size of the pixel structure may be chosen to be large enough so that any effect of the antenna along the xz plane is negligible outside the pixel boundaries, and small enough so that any diffraction side lobes are negligible.

[0085] In addition to the above-described embodiments, embodiments of the present invention may include at least four different configurations of layer structures for pixels, as shown in cross-section along the x-axis. Figures 8 to 11 Any of these configurations can be used with Figure 6 or Figure 7 Layout to be used together.

[0086] Figure 8 FIG. 1 shows a cross section of a pixel in one embodiment of the present invention, which includes five layers, including an insulating cladding layer 810, an antenna metal 820, a single electric barrier layer 830 that embeds the antenna metal 820 in a transparent semiconductor 840, and a ground plane metal 850. The embedding produces a favorable effect because the electric field passing through the electric barrier layer 830 is not only on the flat surface of the antenna metal 820 (i.e., in the positive direction along the y-axis), but also at its ends (i.e., in the positive and negative directions along the x-axis). Therefore, a strong plasma effect is generated around multiple surfaces of the antenna metal 820, which increases the strength of the interaction. When with Figure 7 This is particularly advantageous when combined with a layout of 840 because there is a strong effect in the gap between the two antenna components, which is embedded in the transparent semiconductor 840.

[0087] Fig. 9 It shows that in one embodiment of the present invention, the pixel cross section includes five layers, namely, an insulating cladding layer 910, an antenna metal 920, a single electric barrier layer not embedded in the antenna metal 930, a transparent semiconductor 940 and a ground plane metal 950.

[0088] Fig.10It is shown that in one embodiment of the present invention, the pixel cross section includes six layers, including two electric blocking layers, one of which is embedded in the antenna metal. The structure includes: an insulating cladding layer 1010; an antenna metal 1020; an electric blocking layer 1030, which is transparent or very thin and looks transparent and is embedded in the antenna metal; a transparent semiconductor 1040; a second electric blocking layer 1050, which is also transparent or very thin and looks transparent; and a back metal 1060. In this embodiment, three potentials are applied. The first potential is applied to the antenna 1020, the second potential is applied to the transparent semiconductor 1040, and the third potential is applied to the back metal 1060. The back metal 1060 can be further patterned into an antenna structure, similar to the antenna structure of the antenna 1020, and is arranged parallel or perpendicular to the antenna 1020. Using the potential difference between the transparent semiconductor 1040 and the back metal 1060, a second plasma resonance can be generated at the interface of the transparent semiconductor 1040 and the insulator 1050. The geometric range of the first plasmon resonance and the second plasmon resonance along the y-axis direction is such that the first plasmon resonance and the second plasmon resonance do not substantially interact with each other. In this embodiment, the total phase change experienced by the incident light beam is the sum of the phase change caused by the first plasmon resonance and the phase change caused by the second plasmon resonance.

[0089] Fig.11 It is shown that in one embodiment of the present invention, the pixel cross section includes six layers, including two oxide layers, and neither oxide layer is embedded with antenna metal. The structure includes: an insulating cladding layer 1110; an antenna metal 1120; an electric barrier layer 1130, which is transparent or very thin and looks transparent and is embedded with antenna metal; a transparent semiconductor 1140; a second electric barrier layer 1150, which is also transparent or very thin and looks transparent; and a ground plane metal 1160. In this embodiment, three potentials are applied. The first potential is applied to the antenna 1120, the second potential is applied to the transparent semiconductor 1140, and the third potential is applied to the back metal 1160. The back metal 1160 can be further patterned into an antenna structure, similar to the antenna structure of the antenna 1120, and is arranged parallel or perpendicular to the antenna 1120. Using the potential difference between the transparent semiconductor 1140 and the back metal 1160, a second plasma resonance can be generated at the interface of the transparent semiconductor 1140 and the insulator 1150. The geometric range of the first plasmon resonance and the second plasmon resonance along the y-axis direction is such that the first plasmon resonance and the second plasmon resonance do not substantially interact with each other. In this embodiment, the total phase change experienced by the incident light beam is the sum of the phase change caused by the first plasmon resonance and the phase change caused by the second plasmon resonance.

[0090] In alternative embodiments, the ground plane metal 560, 850, 950, 1060, 1160 may be thin enough to allow light to pass through. In these embodiments, the pixel may be used for transmission, and the cladding 520, 810, 910, 1010, 1110 may be the first layer or the last layer encountered by the incident light beam, depending on whether the light beam is incident from the reverse y-axis or the front y-axis. In other alternative embodiments, the ground plane metal 560, 850, 950 may be omitted, and the semiconductor 550, 840, 940 may perform the function of the ground plane. In these embodiments, the pixel may be used for transmission, and the cladding 520, 810, 910 may be the first layer or the last layer encountered by the incident light beam, depending on whether the light beam is incident from the reverse y-axis or the front y-axis.

[0091] In the embodiment of the present invention, the xz plane layout of the pixel may include a single-branch antenna 620 or a double-branch antenna 720, and its y-axis cross-sectional structure may include Figures 8 to 11 Any of the four cross-sections described in the embodiment constitutes at least eight embodiments specified herein. The dimensions in each embodiment can be adjusted at the nanometer level to determine how the structure affects the phase and amplitude of a light beam with a selected wavelength under different electric potentials.

[0092] In an embodiment of the present invention, when a voltage is applied to the metal antenna, a potential well can be generated in a few nanometers adjacent to the transparent conductor to modulate the density of electric carriers in the well. These carriers can change the refractive index of the transparent conductor in the well region.

[0093] Fig.12 FIG. 1 shows that in one embodiment of the present invention, the carrier density of the transparent semiconductor 1210 near the antenna 1220 is modulated by an applied potential across the barrier layer 1240, which is referred to as the gate voltage V gate 1230. The applied potential creates a potential well. The potential well and improved carrier density are represented by dashed line 1250. The potential well is used to change the accumulation of charge carriers at the interface of the transparent semiconductor 1210 and the electrical insulator 1240 by pulling (i.e., accumulating) carriers from the body of the transparent semiconductor 1210 or pushing (i.e., consuming) carriers toward the body of the transparent semiconductor 1210. When the transparent semiconductor 1210 is n-type, the main carrier type is electrons. At this time, positive potentials accumulate carriers and negative potentials consume carriers at the interface. Depending on the type of transparent semiconductor 1210, positive voltage, zero voltage and negative voltage can also be mixed to achieve the movement of electrons and / or holes. The type of transparent semiconductor 1210 (defined as the natural density of electrons and holes) may be affected by doping, chemical composition, stoichiometry and temperature. In particular, the concentration of oxygen doping may affect the type. It should be understood that Fig.12The operating principles within and around the electric blocking layer 1240 are the operating principles within and around each of the insulators 540, 830, 930, 1030, 1050, 1130, 1150 and their respective adjacent metals and transparent semiconductors.

[0094] In an embodiment of the present invention, when a light radiation beam is incident on a metal antenna and the frequency of the light beam is similar to the plasma resonance frequency of the antenna, the interaction may excite the plasma resonance.

[0095] In an embodiment of the present invention, the plasmon resonance can be changed by changing the carrier density in the transparent semiconductor near the antenna.

[0096] In an embodiment of the present invention, the thickness of the transparent semiconductor is sufficient to prevent the ground plane metal or the back side metal from sensing the plasmon resonance.

[0097] In embodiments of the present invention, the application of a voltage can affect a beam of optical radiation in at least two measurable ways. First, the application of a voltage can change the reflectivity or transmittance of the beam. Second, the application of a voltage can affect the phase shift of the beam. The modulation of the reflectivity or transmittance and the phase shift depends on the applied voltage. The modulation in both cases depends on the geometric parameters of the structure.

[0098] Fig.13 It shows an embodiment of the invention where a single pixel 1310 applies an arbitrary phase shift to an incident beam 1320 of optical radiation. A reflected beam 1330 is phase shifted 1340 by a certain amount between -180° and +180°, where a -180° phase shift has the same effect as a +180° phase shift on the beam.

[0099] In an embodiment of the present invention, the structural parameters of the pixel can be selected so that for a selected wavelength, the range of applied potentials can shift the phase of the light beam from almost -180 degrees to 180 degrees without significantly affecting the transmittance or reflectance. Fig.14a and Fig.14b Described in Fig.14a and Fig.14b Shown with Figure 7 The spectrum of the device is consistent with the structure of a dipole antenna with two branches. Fig.14a It is shown that for different N pert (Carrier density in the disturbance layer) 1430 and different t pert (thickness of the disturbance layer) 1440, |Γ| (magnitude of γ, reflectivity) 1410 and λ 0 (wavelength of incident light)1420. Fig.14b It is shown that for different N pert 1430 and t pert1440, the ∠Γ (reflected optical phase) 1450 of the device and λ 0 1420. In this structure, the electrical connector in the pixel can interact with the antenna to split the plasmon resonance of the antenna into two non-degenerate (different wavelength) resonances. The first resonance is supported by the antenna and is tuned primarily by the optoelectronic interaction in the gap 740 of the nanoantenna, while the second resonance is supported primarily by the connector component 730. Advantageously, at the operating wavelength λ c At 1480, the interaction between the pair of resonances causes a change in the carrier density 1430 in the transparent semiconductor region immediately adjacent to the dipole antenna to cause a change in the optical phase, while the optical amplitude 1410 is substantially unchanged. c 1480 is between the wavelengths of the first resonance and the second resonance. Fig.14a In the example, there are resonances 1460 and 1470 at approximately 1430 nm and 1600 nm, respectively. The optimal operating wavelength λ c 1480 is at about 1550 nm where the amplitude 1465 of the reflectivity 1410 is constant, while the optical phase 1450, which is dependent on the carrier density 1430, changes. This is advantageous for efficient operation of the phased array, since changes in the optical amplitude may cause distortion and loss of the output beam. Fig.14a and Fig.14b It is drawn according to the material and geometric parameters of this embodiment.

[0100] Fig.15 It shows that in the embodiment of the present invention, the geometric parameters of the pixel have been selected so that the phase of the 1550nm beam can be moved to almost any value between -180 and 180 for the range of applied voltage potentials, while the reflectivity changes by only 9%. The parameters of this embodiment are:

[0101] -Thickness of antenna metal 1510: 50nm

[0102] -Thickness of the electrical blocking layer 1520: 5nm

[0103] -Thickness of transparent semiconductor 1530: 44nm

[0104] - Length of antenna metal 1540: 194nm

[0105] -Width of antenna metal 1550: 50nm

[0106] -Width of antenna metal connector 1560: 50nm

[0107] - Distance from one antenna to another along the connector metal (pitch) 1570: 500nm

[0108] - Location of antenna branch where connector metal passes through 1580: 58nm

[0109] - In case of dipole antenna, the gap between the two antenna metals 1590: 30nm

[0110] In an embodiment of the present invention, pixels may be electrically connected to each other through connectors 630 or 730 to form rows, and rows of similar pixels may be placed adjacent to each other to form an array.

[0111] Fig.16 It is shown that in an embodiment of the present invention, rows 1610 of similar pixels along the x-axis are placed adjacent to each other along the z-axis 1620 to form an array in the xz plane.

[0112] In an embodiment of the present invention, different voltage potentials may be applied to rows of similar pixels so that each row applies a different phase shift to a portion of the incident light beam. The voltage potentials applied to rows of pixels may be selected so that the phase shift applied to one row is different from the phase shift applied to an adjacent row, and the difference in the phase shifts applied to any two adjacent rows is the same.

[0113] In such Figure 7 In some embodiments using dual-branch antenna 720, two connector assemblies 730 can be electrically connected to each other or shorted so that both branches can be controlled or electrically tuned in the same manner. In other embodiments, the two branches can be controlled independently.

[0114] Fig.17 It shows that in the embodiment of the present invention, the phase shift difference applied by any two adjacent connected pixel rows is 72°:

[0115] A gate voltage 1705 of -3.0 V may be applied to the first row 1610 of connected pixels, shifting the phase of that row of light beams by 180° 1715.

[0116] - A gate voltage 1720 of -0.5V may be applied to the second row of connected pixels, thereby shifting the phase of this row of light beams by 180° - 72° = 108° 1725.

[0117] - A gate voltage of -1.1 V 1730 may be applied to the third row of connected pixels, shifting the phase of this row of light beams by 108° - 72° = 36° 1735.

[0118] - A gate voltage of -1.8V 1740 may be applied to the fourth row of connected pixels, shifting the phase of this row of light beams by 36° - 72° = -36° 1745.

[0119] - A gate voltage of 3.0V 1750 may be applied to the fifth row of connected pixels, shifting the phase of that row of light beams by -36° - 72° = -180° 1755.

[0120] - Subsequent gate voltages along the z-axis can be applied in a repeating pattern, covering the entire array of pixel rows.

[0121] In the embodiment of the present invention, Fig.17 As shown, when a repeating phase shift pattern is applied to a row of pixels along the z-axis, the reflected or transmitted light beam is steered along the yz plane.

[0122] In an embodiment of the present invention, the pattern of applied voltage and the corresponding phase shift can be modulated to steer an incident light beam within a range of output directions.

[0123] In embodiments of the present invention, independent patterns of applied voltages may be used to add layers, for example to replicate structures and steer in the xy plane as well as the xz plane.

[0124] The embodiment of the present invention aims to provide a pixel, which includes a transparent electrical insulator (which can be a substrate or air); a first electrical conductor, which is arranged on the transparent electrical insulator, and the first electrical conductor includes an antenna component and a connector component; an electrical insulator, which is arranged on the first electrical conductor; a transparent semiconductor, which is arranged on the electrical insulator; and a second electrical conductor, which is arranged on the transparent semiconductor. The transparent semiconductor is thick enough to prevent the electrical insulator from exciting a plasma resonance at the interface with the first electrical conductor and the transparent semiconductor, and the plasma resonance occurs at the interface between the transparent semiconductor and the second electrical conductor.

[0125] In further or any of the above embodiments, the transparent semiconductor is sufficiently thick to prevent any joint plasmon resonances between a first set of interfaces between the first electrical conductor, the electrical insulator, and the transparent semiconductor and a second set of interfaces between the transparent semiconductor and the second electrical conductor.

[0126] In further or any of the above embodiments, the first electrical conductor, the electrical insulator, and the transparent semiconductor can support plasmon resonance after being excited by an incident light beam.

[0127] In further or any of the above embodiments, the first electrical conductor is partially or fully embedded in the electrical insulator.

[0128] In further or any of the above embodiments, the pixel includes a second electrical insulator between the transparent semiconductor and the second electrical conductor.

[0129] In further or any of the above embodiments, the antenna assembly does not extend to the edge of the pixel, and the electrical connector assembly intersects the antenna assembly and extends to the edge of the pixel to enable external connection of the pixel.

[0130] In further or any of the above embodiments, the antenna assembly includes two lines separated by a gap and having a length shorter than the length of the pixel, the two lines being short enough not to overlap any portion of an adjacent intersection. The two lines intersect with corresponding connector assemblies extending to the edge of the pixel to achieve external connection of the pixel. The connector assemblies extending on both sides of the antenna may be short-circuited or connected to each other.

[0131] In further or any of the above embodiments, the dimensions of the antenna assembly are selected so that the pixel operates with light beams having wavelengths in the visible and infrared ranges.

[0132] In further or any of the above embodiments, the dimensions of the antenna assembly are selected to prevent significant interaction with adjacent pixels.

[0133] In further or any of the above embodiments, the transparent electrical insulator serves as a cladding for the remaining structure.

[0134] In further or any of the above embodiments, the antenna assembly functions as an antenna for optical radiation as well as a variable source of constant electrical potential.

[0135] In further or any of the above embodiments, the electrical insulator is sufficiently thin so that the electric field from the antenna assembly is sensed by the transparent semiconductor.

[0136] In further or any of the above embodiments, the electrical insulator is thin enough to change the electric field of the antenna assembly, thereby changing the carrier density distribution in the transparent semiconductor.

[0137] In further or any of the above embodiments, the transparent semiconductor has a carrier density distribution affected by a field of the antenna assembly, the field including a static field and a time-varying field.

[0138] In further or any of the above embodiments, the second electrical conductor functions as a ground plane.

[0139] In further or any of the above embodiments, the antenna assembly, the electrical insulator, and the transparent semiconductor sustain a plasmon resonance when a beam of optical radiation is incident on the structure.

[0140] In further or any of the above embodiments, a resonant frequency of the plasmon resonance may be altered by applying an electrical potential between the antenna assembly and the second electrical conductor.

[0141] In further or any of the above embodiments, when an incident beam of optical radiation is transmitted or reflected at the resonant layer, a phase shift of the incident beam of optical radiation is affected by a potential applied between the antenna assembly and the second electrical conductor.

[0142] In further or any of the above embodiments, a phase shift of a reflected or transmitted beam of optical radiation is affected by an electrical potential applied between the antenna assembly and the second electrical conductor.

[0143] In further or any of the above embodiments, the resonance of the structure is split into a pair of resonances, wherein a first resonance is primarily caused by optoelectronic interaction in the gap between the two wires of the antenna and a second resonance is primarily caused by optoelectronic interaction between the connector components.

[0144] In further or any of the above embodiments, the resonance of the structure is divided into a pair of resonances with different wavelengths through aging-fracture interaction between the antenna and the connector, wherein the first resonance is mainly caused by the optoelectronic interaction in the gap between the two wires of the antenna, and the second resonance is mainly caused by the optoelectronic interaction between the connector components.

[0145] In further or any of the above embodiments, the pixel may have a first resonance and a second resonance, the first resonance being primarily caused by optoelectronic interaction in a gap between two wires of the antenna and the second resonance being caused by optoelectronic interaction between the connector components.

[0146] In further or any of the above embodiments, the first resonance and the second resonance may be at different wavelengths, and the magnitude of the reflectivity or transmittance of the light beam of optical radiation having a wavelength between the first resonance and the second resonance is not significantly affected by the electric potential applied between the antenna assembly and the second electrical conductor.

[0147] In further or any of the above embodiments, a magnitude of reflectivity or transmittance of the beam of optical radiation is not significantly affected by an electrical potential applied between the antenna assembly and the second electrical conductor.

[0148] In further or any of the above embodiments, the resonance of the structure is split into a pair of resonances having different wavelengths by an aging fracture interaction between the antenna and the connector.

[0149] In further or any of the above embodiments, the relative strength, wavelength, and spectral width of the resonance may be such that there is a region of the optical spectrum where the amplitude of the optical reflection is substantially constant.

[0150] In further or any of the above embodiments, the relative strength, wavelength and spectral width of the resonance can be such that the magnitude of the reflectivity or transmittance of a beam of optical radiation having a wavelength between the first resonance and the second resonance is not significantly affected by the electrical potential applied between the antenna assembly and the second electrical conductor.

[0151] In further or any of the above embodiments, the relative strength, wavelength and spectral width of the resonance can be such that there is a region of the optical spectrum wherein an electric potential applied between the antenna assembly and the second electrical conductor significantly affects the reflection phase or transmission phase of the optical radiation beam, but does not affect the reflection amplitude or transmission amplitude of the optical radiation beam.

[0152] In further or any of the above embodiments, the second electrical conductor is thin enough to be transparent over a range of optical wavelengths.

[0153] In further or any of the above embodiments, the second electrical conductor is omitted and the transparent semiconductor serves as a ground plane.

[0154] In further or any of the above embodiments, the thickness, width and length of the material are selected to produce a reflection spectrum in which the reflectivity of at least one wavelength of light radiation is similar to the reflectivity of at least one wavelength of light radiation within a carrier density range corresponding to a phase shift range as wide as at least 90 degrees at any carrier density of the transparent semiconductor.

[0155] Other embodiments are directed to providing a pixel array comprising a plurality of pixels arranged in a plurality of rows. Each of the plurality of pixels is connected in series in each of the plurality of rows. Each of the plurality of pixels comprises: a transparent electrical insulator; a first electrical conductor disposed on the transparent electrical insulator; the first electrical conductor comprising an antenna assembly and a connector assembly; an electrical insulator disposed on the first electrical conductor; a transparent semiconductor disposed on the electrical insulator; and a second electrical conductor disposed on the transparent semiconductor. The transparent semiconductor is sufficiently thick to prevent a plasma resonance primarily located near the electrical insulator from having a significant intensity at an interface between the transparent semiconductor and the second electrical conductor.

[0156] In further or any of the above embodiments, each row in the plurality of rows is independent of each other. Each row in the plurality of rows is capable of applying a different potential such that the pattern of applied potentials controls the optical radiation beam incident on the array without significantly changing its amplitude distribution.

[0157] In further or any of the above embodiments, the dimensions of the antenna assembly are selected to prevent significant diffraction or side lobes from interacting optical radiation beams.

[0158] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Claims

1. A pixel comprising: Transparent electrical insulator; a first electrical conductor disposed on the transparent electrical insulator, the first electrical conductor comprising an antenna assembly and a connector assembly; an electrical insulator disposed on the first electrical conductor; a transparent semiconductor disposed on the electrical insulator; as well as a second electrical conductor disposed on the transparent semiconductor; wherein the transparent semiconductor is thick enough to prevent plasma resonance from occurring at the interface between the transparent semiconductor and the second electrical conductor; The antenna assembly includes two lines separated by a gap, the total length of the two lines is shorter than the length of the pixel, and the two lines respectively intersect with corresponding connector assemblies extending to the edge of the pixel to achieve external connection of the pixel; The electrical insulator is thin enough to change the electric field of the antenna component, thereby changing the carrier density distribution in the transparent semiconductor.

2. The pixel according to claim 1, wherein: The transparent semiconductor is thick enough to prevent joint plasmon resonance between the following two sets of interfaces: a first set of interfaces between the first electrical conductor, the electrical insulator, and the transparent semiconductor; and A second set of interfaces between the transparent semiconductor and the second electrical conductor.

3. The pixel according to claim 1 or 2, wherein: The first electrical conductor, the electrical insulator and the transparent semiconductor support plasmon resonance after being excited by an incident light beam.

4. The pixel according to claim 1 or 2, wherein: The first electrical conductor is at least partially embedded in the electrical insulator.

5. The pixel of claim 1 or 2, further comprising a second electrical insulator between the transparent semiconductor and the second electrical conductor.

6. The pixel according to claim 1 or 2, wherein: The antenna component does not extend to the edge of the pixel, and the connector component intersects the antenna component and extends to the edge of the pixel to achieve external connection of the pixel.

7. The pixel according to claim 1 or 2, wherein: The antenna assembly acts as an antenna for optical radiation as well as a variable source of constant electrical potential.

8. The pixel according to claim 1 or 2, wherein: The second electrical conductor serves as a ground plane.

9. The pixel according to claim 1 or 2, wherein: The antenna assembly, the electrical insulator, and the transparent semiconductor sustain a plasmon resonance or an electrical resonance when a beam of optical radiation is incident on the structure.

10. The pixel according to claim 9, wherein: A resonant frequency of the plasmon resonance is changed by applying an electrical potential between the antenna assembly and the second electrical conductor.

11. The pixel according to any one of claims 1, 2, and 10, wherein: When an incident beam of optical radiation is transmitted or reflected at the resonant layer, a phase of the incident beam of optical radiation is shifted, the shift being affected by a potential applied between the antenna assembly and the second electrical conductor.

12. The pixel according to any one of claims 1, 2, and 10, having a first resonance and a second resonance, wherein the first resonance is mainly caused by the photoelectric interaction in the gap between the two lines of the antenna, and the second resonance is mainly caused by the photoelectric interaction between the connector components.

13. The pixel according to claim 12, wherein: The first resonance and the second resonance are at different wavelengths, and a magnitude of a reflectivity or a transmittance of a beam of optical radiation having a wavelength between the first resonance and the second resonance is not significantly affected by an electrical potential applied between the antenna assembly and the second electrical conductor.

14. The pixel according to any one of claims 1, 2, 10, and 13, wherein: The second electrical conductor is thin enough to be transparent over a range of optical wavelengths.

15. The pixel according to any one of claims 1, 2, 10, and 13, wherein: The second electrical conductor is omitted and the transparent semiconductor serves as a ground plane.

16. A pixel array comprising: a plurality of pixels arranged in a plurality of rows, each pixel of the plurality of pixels being connected in series in each of the plurality of rows; Each pixel of the plurality of pixels comprises: Transparent electrical insulator; a first electrical conductor disposed on the transparent electrical insulator, the first electrical conductor comprising an antenna assembly and a connector assembly; an electrical insulator disposed on the first electrical conductor; a transparent semiconductor disposed on the electrical insulator; and a second electrical conductor disposed on the transparent semiconductor; wherein the transparent semiconductor is thick enough to prevent plasma resonance from occurring at the interface between the transparent semiconductor and the second electrical conductor; The antenna assembly includes two lines separated by a gap, the total length of the two lines is shorter than the length of the pixel, and the two lines respectively intersect with corresponding connector assemblies extending to the edge of the pixel to achieve external connection of the pixel; The electrical insulator is thin enough to change the electric field of the antenna component, thereby changing the carrier density distribution in the transparent semiconductor.

17. The pixel array according to claim 16, wherein: Each of the plurality of rows is independent of the others and each of the plurality of rows is capable of having a different potential applied thereto such that the pattern of applied potentials controls the beam of optical radiation incident on the array without significantly changing its amplitude distribution.

18. The pixel array according to claim 16 or 17, wherein: The dimensions of the antenna assembly are selected to prevent significant diffraction or side lobes of the beams of optical radiation from the interaction.

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