Light modulator and substrate with micro and / or nano-patterned elements for optical modulation

Abstract

Some embodiments relate to a transparent substrate for an optical modulator. The substrate has at least one drive electrode that is applied to a first surface of the substrate. The drive electrodes may be arranged across the pattern of the substrate and may receive an electrical potential, resulting in modulation of an optical property of the light modulator. A patterned element is applied to the surface of the substrate to vary the phase, amplitude and / or polarization of light interacting with the substrate.

Description

Technical Field

[0001] The presently disclosed subject matter relates to a substrate for an optical modulator, a method of manufacturing the substrate, an optical modulator, a method of calibrating the optical modulator, a method of controlling the optical modulator, and a computer-readable medium. Background Art

[0002] Known optical modulators are disclosed in WO2022023180 (incorporated herein by reference). Known optical modulators include a transparent substrate or a reflective substrate. A plurality of electrodes are applied to the substrate in a pattern across the substrate. A controller can apply an electric potential to the electrodes to obtain an electromagnetic field between the electrodes, thereby providing electrophoretic movement of particles towards one electrode or providing electrophoretic movement of particles away from one electrode. Summary of the Invention

[0003] It would be advantageous to have an improved optical modulator. In particular, it would be advantageous to have an improved transparent substrate for an optical modulator. In one embodiment of the substrate, micro- and / or nano-patterned elements are applied to the surface of the substrate. The patterned elements alter the phase, amplitude, and / or polarization of light interacting with the substrate. Light interacting with the substrate includes light passing through the surface. Light interacting with the substrate may also include light reflected from the surface.

[0004] The patterned elements have a shape, for example, a 2D shape or a 3D shape parallel to the substrate, and have a distribution selected to achieve a desired optical modulation. The patterned elements can be manufactured by patterning, which may include a process of manufacturing nanostructures across the surface of a material (in this case, the substrate). In one embodiment, the patterned elements can be transparent or can be opaque. Transparent patterned elements have the advantage of a less reduced transmittance, although the optical effect of the elements may be small, for example if they have a small refractive index.

[0005] In addition to the patterned elements, at least one drive electrode can also be applied to a first surface of the substrate, the drive electrode being arranged in a pattern across the substrate. The electrodes are arranged to receive an electric potential to cause modulation of the optical properties of the optical modulator. In particular, the optical modulator can have an optical layer adjacent to the substrate. Particles in the optical layer can be under the control (e.g., electrophoretic control) of the electrodes.

[0006] Metasurfaces (e.g., metasurfaces formed by the patterned elements) allow correction of optical artifacts caused by the drive electrodes present on the substrate. In particular, diffraction and / or rainbow effects can be reduced by adding nano-elements. For example, a metasurface can include a thin film coating that produces electromagnetic optics. Typically, the metasurface design is specifically selected or optimized for the electrode design. Using the same metasurface for different patterns of electrodes may not work.

[0007] Metasurfaces (e.g., metasurfaces formed by patterned elements) may, in addition to correcting artifacts, also allow the introduction of optical effects. Optical effects include 3D rendering, holography, and lenses with potentially different foci.

[0008] A metasurface is a layer of nanostructures at the subwavelength scale that can be used to design thin optical functional devices. Multiple metasurface-based optical devices (also referred to as planar optical devices) have achieved unique performance.

[0009] Nanoscale elements can be applied to the same surface of the substrate or to opposite surfaces of the substrate.

[0010] The nanoscale elements can be arranged to reduce the reflection of the substrate, thereby improving the dark state of the light modulator, e.g., deepening the black level.

[0011] Aspects of the presently disclosed subject matter further include methods of fabricating a substrate, a light modulator, methods of calibrating a light modulator, methods of controlling a light modulator, and computer-readable media. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Further details, aspects, and embodiments will be described only by way of example and with reference to the drawings. The elements in the drawings are illustrated for simplicity and clarity and are not necessarily drawn to scale. In the drawings, elements corresponding to those already described may have the same reference numerals. In the drawings:

[0013] Figure 1a An embodiment of one of the building blocks is schematically shown,

[0014] Figure 1b An embodiment of one of the substrates is schematically shown,

[0015] Figure 1c An embodiment of one of the substrates is schematically shown,

[0016] Figure 1d An embodiment of one of the substrates is schematically shown,

[0017] Figure 1e An embodiment of one of the substrates is schematically shown,

[0018] Figure 1f An embodiment of one of the substrates is schematically shown,

[0019] Figures 2a to 2f An embodiment of one of the substrates is schematically shown,

[0020] Figure 3aAn embodiment schematically showing an implementation of an optical modulator

[0021] Figure 3b An embodiment schematically showing an implementation of an optical modulator

[0022] Figure 3c An embodiment schematically showing an implementation of an automobile

[0023] Figures 4a to 4c An implementation of an optical modulator is schematically shown

[0024] Figure 5a An embodiment schematically showing an implementation of an optical modulator

[0025] Figure 5b An embodiment schematically showing an implementation of an optical modulator

[0026] Figure 5c An embodiment schematically showing an implementation of an optical modulator

[0027] Figure 6a An embodiment schematically showing an implementation of a transparent substrate for an optical modulator

[0028] Figure 6b An embodiment schematically showing an implementation of a transparent substrate for an optical modulator

[0029] Figure 6c.1 An embodiment schematically showing an implementation of a transparent substrate for an optical modulator

[0030] Figure 6c.2 An embodiment schematically showing an implementation of a transparent substrate for an optical modulator

[0031] Figure 6d.1 An embodiment schematically showing an optical modulator without patterned elements

[0032] Figure 6d.2 An embodiment schematically showing an implementation of an optical modulator with patterned elements

[0033] Figure 6e.1 An embodiment schematically showing an optical modulator with conductive patterned elements in an inactive state

[0034] Figure 6e.2 An embodiment schematically showing an optical modulator with conductive patterned elements in an active state

[0035] Figures 7a to 7gAn embodiment of a transparent substrate for an optical modulator is schematically shown.

[0036] Figure 8a An embodiment of a method for manufacturing a substrate in an embodiment is schematically shown.

[0037] Figure 8b An embodiment of a method for manufacturing an optical modulator in an embodiment is schematically shown.

[0038] Figure 8c An embodiment of a method for operating an optical modulator in an embodiment is schematically shown.

[0039] Figure 9a A computer-readable medium having a writable portion is schematically shown, the writable portion including a computer program according to an embodiment.

[0040] Figure 9b A representation of a processor system according to an embodiment is schematically shown.

[0041] List of reference numerals

[0042] The following list of references and abbreviations is provided for ease of understanding the drawings and should not be construed as limiting the claims.

[0043] 10 Optical modulator

[0044] 11 First substrate

[0045] 12 Second substrate

[0046] 13, 13a, 13b Electrodes

[0047] 14, 14a, 14b Electrodes

[0048] 15 Fluid

[0049] 16 Controller

[0050] 30 Particles

[0051] 20 Automobile

[0052] 21 Optical modulator

[0053] 40 Optical modulator

[0054] 41 First substrate

[0055] 42 Second substrate

[0056] 43 Third substrate

[0057] 46 Controller

[0058] 100 - 102 Substrate

[0059] 110 - 114 Main Circuit

[0060] 121 - 124 Main Circuit

[0061] 131 - 134 Interdigitated Electrodes

[0062] 140 Building Block

[0063] 141 - 144 Building Block

[0064] 110, 120 Drive Bus

[0065] 110’, 120’ Drive Bus

[0066] 119, 129 Connection Area

[0067] 191, 192 Direction

[0068] 203 - 204 Substrate

[0069] 211 - 222 Building Block

[0070] 251 - 262 Building Block

[0071] 501, 502 Optical Modulator

[0072] 511, 512 Transparent Substrate

[0073] 521, 522 Drive Electrodes

[0074] 523 Particle

[0075] 524 Optical Layer

[0076] 531 Spacer

[0077] 541, 542 Patterned Elements

[0078] 543, 544

[0079] 601, 602 Substrate

[0080] 611, 612 Drive Electrodes

[0081] 621, 622 Patterned Elements

[0082] 631 Virtual Cutting Line

[0083] 632 Virtual Scale, 1 Micron

[0084] 642 Original Wavefront

[0085] 643 Optical modulator

[0086] 644 Aberrated wavefront

[0087] 645 Driving electrode

[0088] 653 Optical modulator

[0089] 654 Corrected wavefront

[0090] 655 Patterned element

[0091] 661 Height

[0092] 662 Diameter

[0093] 663 Distance between objects

[0094] 711 Transparent substrate

[0095] 712 Side of the optical layer

[0096] 721 Driving electrode

[0097] 745,746 Patterned element

[0098] 751,752,753 Coating

[0099] 1000,1001 Computer-readable medium

[0100] 1010 Writeable part

[0101] 1020 Computer program

[0102] 1110 Integrated circuit

[0103] 1120 Processing unit

[0104] 1122 Memory

[0105] 1124 Application-specific integrated circuit

[0106] 1126 Communication element

[0107] 1130 Interconnect

[0108] 1140 Processor system DETAILED DESCRIPTION

[0109] While the presently disclosed subject matter admits of many different forms of embodiments, one or more specific embodiments have been shown in the drawings and will be described in detail herein. It is to be understood that the present disclosure is to be considered an exemplification of the principles of the presently disclosed subject matter and is not intended to limit it to the specific embodiments shown and described.

[0110] In the following, for the sake of understanding, elements of the embodiments are described in the context of an operation. However, it will be apparent that the corresponding elements are arranged to perform the functions described as being performed by them. Furthermore, the presently disclosed subject matter is not limited to the embodiments, but also includes other combinations of features described herein or recited in the dependent claims that are different from each other.

[0111] The disclosed substrate is for example used in an optical modulator, in particular for dynamic glass. The substrate is transparent and at least one drive electrode is applied to one side of the substrate, the drive electrode extending in a pattern across this side of the first substrate. Interestingly, when used in an optical modulator, it is advantageous to apply a patterned element to the surface of the substrate to modify (e.g., correct) the light interacting with the substrate. The patterned element is arranged on the substrate in a pattern. The pattern may be repetitive, but this is not necessary. The pattern is created in a pattern according to the desired modulation of the light caused by the patterned element. For example, a plurality of patterned elements on the substrate may together form a metasurface.

[0112] There are many types of optical modulators using a substrate such as this. Some known optical modulators are based on the electrophoresis principle. For example, the substrate may include a plurality of interdigitated drive electrodes (e.g., two electrodes) applied to the substrate, each of the plurality of drive electrodes being arranged in a pattern across the substrate, and the plurality of interdigitated drive electrodes being arranged alternately relative to each other on the substrate. Having a plurality of interdigitated electrodes allows for local control of the electric field to achieve electrophoretic control of the particles.

[0113] The electrophoretic optical modulator is more broadly explained herein and is used as an illustrative example. In one embodiment, the optical modulator includes a first substrate and a second substrate. According to one embodiment, at least one of the first substrate and the second substrate may have a patterned element. For example, the first substrate and the second substrate may be arranged facing each other on the inside. Using the substrate according to one embodiment has the effect of reducing optical interference, for example. An optical layer is arranged between the first substrate and the second substrate. Drive electrodes are arranged to modulate the electric field in the optical layer. The optical layer includes a fluid, and the fluid includes particles, where the particles are charged or can be charged. The particles can be moved under the control of an electric field. For example, a controller may be configured to apply an electric potential to the drive electrodes to obtain an electromagnetic field at the drive electrodes, thereby providing electrophoretic movement of the particles towards or away from one of the at least one drive electrode, resulting in modulation of the optical properties of the optical modulator.

[0114] Several known optical modulators are reviewed below, showing some of the options in terms of technology and electrodes. These known substrates can be advantageously modified by applying patterned elements. These embodiments also show optical modulators with different numbers of electrodes on the substrate.

[0115] International Patent Applications WO2011012499A1 (incorporated herein by reference) and WO2011131689 (incorporated herein by reference) disclose light modulators in the form of electrophoretic display devices, such as electronic ink displays. The pixels of the display include a storage electrode and a field electrode. The storage electrode is arranged at a storage area to accumulate charged particles away from a hole area, and the field electrode occupies a field electrode area that is at least a part of the hole area of the pixel. The charged particles are movable between the storage electrode and the field electrode. In one embodiment, the two electrodes are applied on a single substrate. The substrate may have patterned elements applied to the surface of the substrate to change (e.g., correct) the light interacting with the substrate.

[0116] U.S. Patent 10921678, titled ‘Electrophoretic device’ (incorporated herein by reference), shows an electrophoretic device having only one patterned electrode on one of two substrates. For example, one substrate having an electrode according to US10921678 can be replaced with a substrate including a single electrode according to one embodiment. For example, one embodiment includes a first transparent substrate having a field electrode and a second substrate opposite the first substrate and having a storage electrode. The first substrate and the second substrate enclose a pixel having a fluid and particles. In use, an electromagnetic field applied to the field electrode and the storage electrode provides movement of the particles away from and towards the field electrode and the storage electrode. The substrate may have patterned elements applied to the surface of the substrate to change (e.g., correct) the light interacting with the substrate.

[0117] U.S. Patent 8054535B2 (incorporated herein by reference) and U.S. Patent 8384658B2 (incorporated herein by reference) show alternative embodiments of an electrophoretic light modulator in one of two substrates having two patterned electrodes.

[0118] Patterned electrodes are also used in dielectrophoretic light modulators. For example, U.S. Patent Applications US2005185104A1 (incorporated herein by reference) and US20180239211A1 (incorporated herein by reference) show dielectrophoretic light modulators having substrates with patterned electrodes. Any of these referenced electrophoretic light modulators or dielectrophoretic light modulators can be adapted to change (e.g., correct) the light interacting with the substrate by applying patterned elements to the substrate surface.

[0119] The paper "Reversible Metal Electrodeposition Devices: An Emerging Approach to Effective Light Modulation and Thermal Management" (incorporated by reference) also shows a substrate on which a patterned electrode is applied. The patterned electrode can be advantageously arranged according to one embodiment.

[0120] One embodiment of the substrate can be used in an electrochromic device (ECD). An electrochromic device (ECD) controls optical properties, such as optical transmission, absorption, reflection, and / or emission, in a continuous but reversible manner when a voltage is applied (electrochromism). This property enables electrochromic devices to be used in applications such as smart glass, electrochromic mirrors, and electrochromic display devices.

[0121] Electrochromic devices are described in, for example, the paper "Silver grid electrodes for faster switching ITO free electrochromic devices" by António California et al. (incorporated by reference). The paper describes the preparation of an electrochromic device, in this case, an electrochromic device without ITO.

[0122] Electrochromic devices use a conductive electrode applied to a substrate. The cited paper uses a silver grid made of silver ink as the conductive electrode. Electrochromic devices can include an electrochromic material. The cited paper uses poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). In an electrochromic device, at least one driving electrode (e.g., a conductive electrode) is applied to the substrate. The driving electrode is arranged in a pattern across the substrate. The cited paper discloses two different grid patterns: a conventional honeycomb design and a conventional stepped design. See Table 1 and Figure 3 of the cited paper.

[0123] The electrode can be applied to the substrate by screen printing on the substrate. In the case of the cited paper, the substrate is polyethylene terephthalate (PET). Typically, the electrode is a conductive material, such as a metal or a metal oxide. In the cited paper, silver ink is used to screen print the grid on PET using a RokuPrint RP 2.2 apparatus and a 180 mesh screen. The samples are allowed to dry in an oven at 130 °C for 15 minutes. On top of these silver grids, one or two layers of PEDOT:PSS SV3 are subsequently printed by screen printing. Patterned elements can be applied to the substrate surface to alter the light interacting with the substrate, for example, to form a metasurface.

[0124] Another embodiment of an electrochromic device is given in U.S. Patent 5,161,048, entitled "Electrochromic window with metal grid counter electrode and acidic polyelectrolyte", which is incorporated herein by reference. For example, an electrochromic device can include a transparent electrochromic film and an ion-conductive layer disposed between a pair of electrodes. The metal grid electrode is distributed to the electrodes. FIG. 1 of the patent shows the metal grid according to the cited patent. To form the counter electrode, the metal grid is placed adjacent to the second glass substrate.

[0125] For example, in one embodiment of an electrochromic device, the electrochromic device can include a transparent substrate, a conductive electrode member, a transparent electrochromic film in contact with the conductive electrode member, an ion-conductive polymer in contact with the electrochromic film; and, a patterned conductive electrode in contact with the ion-conductive polymer. The patterned conductive electrode can be according to one embodiment.

[0126] The substrate according to one embodiment can be beneficially applied in several other technologies. For example, the light modulator can be a dielectrophoretic light modulator, such as that shown in US20050185104A1, which is incorporated herein by reference. The substrate as in one embodiment can also be used in other electrowetting and OLED applications.

[0127] In OLED and electrowetting, the electrodes need to be located on only one of the substrates in the substrate. The substrate with the electrodes can be according to one embodiment.

[0128] In the application of a light modulator for glass, typically both of the substrates are transparent. In other applications, such as in televisions, e-readers, etc., only one substrate can be transparent.

[0129] In one embodiment, the patterned elements that the substrate has are applied to the substrate surface to modify (e.g., correct) the light that interacts with the substrate.

[0130] In Figures 1a to 4c it, the nano-elements are not visible in the figure.

[0131] Figure 1b An embodiment of one embodiment of the substrate is schematically shown. The substrate is particularly useful in a light modulator (e.g., a light modulator as described herein). A plurality of interdigitated drive electrodes are applied to the substrate in a manner spanning the substrate. Figure 1b Shown therein are two electrodes.

[0132] An exemplary use of the substrate excitation is in an electrophoretic light modulator. Typically, an electrophoretic light modulator includes at least two substrates, each substrate having at least two drive electrodes; although this is not required, for example, an electrophoretic light modulator can include a single substrate with 2 electrodes and a relative substrate including 1 electrode. In any instance, preferably, at least one of the substrates in the light modulator is according to one embodiment.

[0133] One embodiment of a light modulator includes a first substrate and a second substrate according to one embodiment. The first substrate and the second substrate are arranged to face each other inwardly. At least one drive electrode is applied to the inner side of the first substrate. An optical layer is arranged between the first substrate and the second substrate. The controller is configured to apply an electric potential to at least one drive electrode, thereby causing modulation of the optical properties of the light modulator. One or both of the first substrate and the second substrate are transparent and / or translucent.

[0134] There are many different types of light modulators that use at least one drive electrode applied to a substrate. Since light passes through the substrate, interference is a common problem in the field of light modulators. The optical layer and the controller can be arranged to modulate the optical properties using effects that depend on the electric potential on the drive electrode; examples include dielectrophoretic effects and electrophoretic effects. For example, optical modulation can include modulation of particles arranged in the optical layer. The number of drive electrodes can range from one drive electrode on a single substrate to multiple drive electrodes on one or two substrates.

[0135] The optical layer arranged between the first substrate and the second substrate can include particles, such as particles suspended in a fluid. The controller can be configured to apply an electric potential to the drive electrodes to cause the particles to move, thereby modulating the optical properties of the light modulator.

[0136] In one embodiment, the particles include charged particles or particles that can be charged, and the controller is configured to apply an electric potential to the drive electrodes to obtain an electromagnetic field, thereby providing electrophoretic movement of the particles. In one embodiment, the electromagnetic field is arranged between at least two drive electrodes, and the at least two electrodes are arranged on the same substrate or on different substrates.

[0137] In one embodiment, the particles include dielectric particles, and the controller is configured to apply an electric potential to the drive electrodes to apply an electric field gradient to the particles, thereby enabling the particles to move under the action of dielectrophoretic forces.

[0138] The controller can apply an electrical signal to one or more of the drive electrodes. Embodiments for controlling dielectrophoretic forces can use signals including DC signals and / or AC signals. Embodiments for controlling electrophoretic forces can use signals including DC signals and / or AC signals.

[0139] Figure 1b Shown are two drive electrodes on the same surface. The two drive electrodes are Figure 1b indicated in two different dashed line styles in Figure 1b . There can be more than two electrodes on the same side of the substrate, for example to facilitate a more fine-grained control of the voltage difference across the substrate. The drive electrodes are applied to the same side of the substrate. Applying the electrodes to the substrate can be accomplished by lithographic means (e.g., using a mask representing the electrode pattern). The electrodes can also be applied by embedding them in the substrate.

[0140] The drive electrodes are electrically connected, e.g., the drive electrodes have the same electric potential everywhere. The drive electrodes can include drive buses and main lines. At least, the main line of one drive electrode and the main line of another drive electrode are interdigitated. Typically, the drive electrodes extend across the substrate in a substantially straight line, while the main lines are coiled.

[0141] In one embodiment, each of the two substrates of the optical modulator has two electrodes disposed at its inner surface. However, as mentioned, multiple electrodes on one or both substrates are not required. For example, one embodiment of the optical modulator includes a first substrate and a second substrate. For example, the first substrate can include one drive electrode and the second substrate can not include a drive electrode. For example, the first substrate can include two drive electrodes and the second substrate can include one drive electrode. For example, the first substrate can include two drive electrodes and the second substrate can include two drive electrodes. For example, the first substrate can include more than two drive electrodes and the second substrate can include two or more drive electrodes.

[0142] However, an optical modulator in which each substrate includes two drive electrodes is used as an exemplary embodiment. The design of the substrate characterized by two drive electrodes can be adapted to have a single drive electrode, e.g., by connecting the two drive electrodes or by removing one of the drive electrodes. Adapting the substrate in this way can make it suitable for use in different technologies.

[0143] Each of the multiple drive electrodes is arranged in a pattern across the substrate. The multiple drive electrodes are arranged alternately relative to each other on the substrate. Typically, the drive electrodes include multiple main lines, each of which extends across the substrate. The main lines of the drive electrodes are alternating, e.g., interdigitated. For example, in Figure 1b Figure 1b , the first drive electrode includes main lines 111 - 114, and the second drive electrode includes main lines 121 - 124. Each drive electrode is driven by its drive bus. Figure 1b Shown are two drive buses: drive bus 110 and drive bus 120. The drive electrodes are also used to connect the main lines together. For example, in Figure 1bIn this case, drive bus 110 drives and is connected to main lines 111 - 114; drive bus 120 drives and is connected to main lines 121 - 124. There may be more main lines than the four main lines shown in this embodiment. Using main lines is advantageous because it reduces the length of the electrodes, but it is not necessary. It is possible to design each drive electrode to use only one main line, although it is advantageous to have multiple ones.

[0144] The multiple main lines of the first electrode and the second electrode are alternately arranged relative to each other on the substrate.

[0145] One application of the substrate (such as substrate 100) is in smart glass (e.g., a light modulator), which can be applied in residences, offices, greenhouses, automobiles, etc. The transparency level or reflectivity level of the smart glass can be electrically adapted. For example, in smart glass, two substrates (such as substrate 100) will be stacked such that the sides with the two electrodes face each other. A fluid with particles is enclosed between the two substrates. Smart glass embodiments are further discussed below. In one embodiment, electrodes (e.g., two or more electrodes) are applied to one surface of each substrate. One, two, or more electrodes may also be present on the other surface of substrate 100, for example, to facilitate stacking three or more substrates.

[0146] Some of the following embodiments show examples of modulating the transparency level or reflectivity level. The light modulator can be adapted for other optical effects. For example, if desired, an embodiment can be modified for different levels of translucency instead of different levels of transparency. If desired, the type of particles used in an embodiment can be changed, for example, to particles that absorb or reflect different wavelengths, and to particles with different degrees of specular or diffuse reflection. For example, in one embodiment, the light modulator can modulate different reflection levels. The particles can also emit light. Stacking multiple optical layers further increases the possibilities.

[0147] Two sets of alternating main lines are sufficient to provide electrically adaptable glass; due to the two alternating sets, the electric field at any part of the substrate can be controlled because two opposing electrodes define parts from two opposing sides.

[0148] Interestingly, the pattern in which the drive electrodes extend across the substrate is created by multiple repeating building blocks. As Figure 1bAs shown, the drive electrodes on the substrate 100 are shown as four blocks: blocks 141, 142, 143, and 144, and the blocks are all substantially the same. The number of building blocks can be greater than four. The building blocks are repeated in two directions across the substrate (e.g., the first direction 191 (e.g., the x - direction shown horizontally in the figure) and the second direction 192 (e.g., the y - direction shown vertically in the figure)). Using building blocks is advantageous because it allows for manufacturing using a stepper; using building blocks is not mandatory.

[0149] For example, Figure 1a An embodiment of a building block 140 is schematically shown. The building block 140 includes a plurality of interdigital electrodes that extend across the building block in at least two directions. Figure 1a Four electrodes are shown: electrodes 131 - 134. When the building blocks are repeated in two directions across the substrate, the electrodes in the building blocks will form drive electrodes, for example, a plurality of main lines of the drive electrodes. Note that the building blocks are typically connected in a substrate electrode design tool. Typically, the building block includes more than four electrode lines. For example, in a series of embodiments, between 8 and 12 main lines are used. However, the number of electrode lines can be higher. For example, the building block can include many short electrode lines near the edges, and when the block is repeated, these short electrode lines are connected to the lines of other building blocks. Considering these short offshoots, the number of lines can increase to as high as, for example, 50. Obviously, when using larger building blocks, the number of electrode lines can also increase. In one embodiment, the number of electrode lines in the building block is between 8 and 50, or between 8 and 25, etc.

[0150] The drive electrodes formed by repeating the building blocks are connected to a drive bus. Typically, the electrode lines in the building blocks are connected to the electrode lines in adjacent blocks by merging the corresponding electrode lines; however, this is not necessary, and connection regions for connecting the corresponding electrode lines can be inserted between the repeated building blocks.

[0151] This step can connect a plurality of main lines together to form a single drive electrode. Figure 1b Two connection regions 119 and 129 are shown, where the main lines belonging to the same drive electrode are respectively connected to the drive bus 110 and the drive bus 120.

[0152] The Figure 1a shown electrodes are alternated in the same dashed - line style as Figure 1b the dashed - line style of Figure 1aThe specific electrodes of the building blocks will always terminate at the first driving electrode or the second electrode, as indicated by the dashed line style in this case, for example. However, this is not necessarily the case. The electrodes in the building blocks can be terminated as part of the first driving electrode or as part of the second driving electrode. This can change, for example, due to the parity of the number of electrodes in the building blocks, the pattern of building block repetition, etc.

[0153] For example, for a light modulator with two driving electrodes, a specific pattern of repeating building blocks can be used, where alternating main lines can be assigned to the two driving electrodes. However, for a light modulator with three driving electrodes, the same pattern of repeating building blocks can be used, where each next group of three main lines can be assigned to the three driving electrodes.

[0154] In addition, Figure 1a The building blocks shown in [[ ]] are square, but this is not necessary either. For example, the building blocks can be rectangular. In one embodiment, the building block shape can form a so-called tessellation. For example, the building blocks can be triangular, hexagonal, or even a combination of plane-filling shapes.

[0155] As described, Figure 1a and Figure 1b are schematic. This is especially the case for the depiction of the electrodes. Figure 1a The electrodes shown in [[ ]] are straight. However, in one embodiment, the electrodes on the building blocks are more curly, for example, bent. By adapting the shape of the electrodes, unwanted diffraction effects can be changed.

[0156] In one embodiment, the tunable mirror includes a light modulator according to one embodiment. For example, the tunable mirror includes a transparent substrate, an optical layer, and a reflective substrate. One or both of the substrates are according to one embodiment. The tunable mirror can be electrophoretic. Typically, each substrate has two electrodes, but this is not required.

[0157] Figure 1c An example of an embodiment of substrate 101 is schematically shown. Substrate 101 is similar to substrate 100, except for how the main lines formed by the electrodes on the building blocks are connected to the driving buses. In [[ ]] Figure 1a a connection region is inserted between the repeating building blocks and driving buses 110 and 120. In the connection region, the main lines belonging to the same driving electrode are connected to the same driving bus. In [[ ]] Figure 1c the driving buses are adjacent to the building blocks. To avoid the driving buses connecting to the main lines of different driving electrodes, some of the building blocks are modified.

[0158] For example, building block 141 can be a copy of building block 140, but the electrode 134 is shortened such that the main line 122 (with line 134 being part of main line 122) is not connected to the bus 110. In Figure 1c , the building blocks are substantially the same, except that breaks are introduced into some of the electrodes of the building blocks near the drive bus to avoid connecting the main line to the drive bus. Although Figure 1c all of the building blocks shown in

[0159] Figure 1d are modified in this way, in one embodiment, most of the building blocks will not be modified, such as those not adjacent to the drive buses 110, 120.

[0160] However, it is not required that the electrodes in the building blocks connect opposite sides of the building block. Although typically all of the electrodes in a building block will connect two sides of the building block, it is not required that these two sides be opposite. The reason for this is that the electrodes can be continued through the next building block. In this case, most of the main lines will still connect the same two opposite sides, but at the edges of the substrate, this may not occur because there are no additional building blocks to continue carrying the electrodes. To allow for more complex electrode designs on the building blocks, the main lines can be connected to the drive buses from both sides, such as two sides adjacent to the same corner of the substrate.

[0161] Figure 1d Shown in

[0162] are drive buses 110' extending along two sides of the substrate and drive buses 120' extending along two other sides of the substrate.

[0163] The advantage of this configuration is that the drive buses can be fabricated in the same plane. However, this is not necessary. If desired, the drive buses can be connected from three or four sides to, for example, further increase the design freedom of the building blocks. Multiple embodiments are given herein.

[0164] For example, in one embodiment, a first driving electrode may be provided. Then, a dielectric is provided locally, and finally a second driving electrode is provided. The dielectric is arranged to cover at least the intersection of the first electrode and the second electrode. Through-holes may be used for the lower first driving electrode, for example, to be used to connect to the lower first driving electrode. The provision of the driving electrode may include the provision of a driving bus.

[0165] Figure 1e An example of an embodiment of the substrate 203 is schematically shown. In Figure 1e this, the building blocks have been replicated multiple times.

[0166] The building block 211 has been mirrored in the y-direction to form the building block 221. The building block 221 has been directly arranged at the bottom of the building block 211. The building block 211 has been mirrored in the x-direction to form the building block 212. The building block 212 has been directly arranged to the right of the building block 211. The building block 211 has been mirrored in both the x-direction and the y-direction to form the building block 222. For example, the mirroring may use one side of the building block as the mirror axis.

[0167] By mirroring the building blocks, it is ensured that the driving buses of the same driving electrode terminate close to each other on the substrate.

[0168] Figure 1f An example of an embodiment of the substrate 204 is schematically shown. In the substrate 204, the building blocks are repeated across the substrate in a different way. The building block 251 has been mirrored in the y-direction to form the building block 261. The building block 261 has been directly arranged at the bottom of the building block 251. The building block 251 has been point-reflected (e.g., rotated 180 degrees) to form the building block 252. The building block 252 has been directly arranged to the right of the building block 251. The building block 251 has been mirrored in the x-direction to form the building block 262.

[0169] Figures 2a - 2f An example of a substrate having interdigital electrodes is schematically shown. These may be embodied on a substrate having two electrodes, for example, by alternately connected electrodes. Figures 2a - 2d They may also be embodied on a substrate having multiple electrodes, for example, by sequentially connecting three or four or more electrodes.

[0170] Figure 2e and Figure 2f shows a design having two driving electrodes on the substrate surface. Either design can be modified to have only a single driving electrode on the substrate surface, for example, by removing one of the two driving electrodes. For example, such a modified design can be used in a light modulator using a substrate with a single electrode.

[0171] The designs shown can be implemented in a single plane without having crossing electrodes. Specifically, if these designs are connected to two drive buses, no crossing electrodes are required. When using more than two drive electrodes, or if a more complex electrode pattern is used, crossing of the electrodes may be used, or may even be necessary. However, such crossing is possible, for example, a dielectric material can be arranged between the electrodes at the position where two electrode lines cross. For example, such an insulator can be provided at the crossing position. For example, a first drive electrode is located in a first plane of the substrate, and a second drive electrode is located in a second plane of the substrate.

[0172] According to one embodiment, two substrates can be combined to form a light modulator. The light modulator is particularly suitable for glass. An exemplary embodiment of the light modulator is shown below.

[0173] Figure 3a An embodiment of the light modulator 10 that can be applied in smart glass is schematically shown.

[0174] Reference is made to patent application PCT / EP2020 / 052379, which is incorporated herein by reference; this application includes advantageous designs for light modulators, which can be further improved, for example, by including the electrodes, building blocks, and / or substrates explained herein.

[0175] The light modulator 10 is capable of electronically switching between a transparent state and a non-transparent state and between a non-transparent state and a transparent state, or between a reflective state and a non-reflective state and between a non-reflective state and a reflective state. The light modulator 10 includes a first substrate 11 and a second substrate 12 arranged opposite to each other. At least two electrodes are applied on the inner side of the first substrate 11: shown as electrodes 13a, 13b. These at least two electrodes are collectively referred to as electrode 13. At least two electrodes are applied on the inner side of the second substrate 12: shown as electrodes 14a, 14b. These at least two electrodes are collectively referred to as electrode 14.

[0176] A fluid 15 is provided between the substrates. The fluid includes particles 30 (e.g., nanoparticles and / or microparticles), wherein the particles are charged or can be charged. For example, the particles can inherently carry a charge on their surface. For example, the particles can be surrounded by charged molecules.

[0177] Depending on the applied electric field, the electrodes are arranged to drive the particles 30 towards or away from the electrodes. The optical properties, in particular the transparency or reflectivity of the light modulator, depend on the position of the particles 30 in the fluid. For example, connections can be provided for applying an electromagnetic field to the electrodes.

[0178] At least one but preferably two electrodes 13 and 14 are according to one embodiment, although they are schematically shown in the figure.

[0179] In one embodiment, at least one of the electrode pattern on the first substrate and the electrode pattern on the second substrate has a low computational pixelation noise metric that contributes to diffraction. Interestingly, the individual electrode patterns on the substrates may not meet the bounds of their pixelation noise metric, but their combination (i.e., their superposition) can. Since this is the pattern visible when looking through the light modulator, the low pixelation noise metric in the superposition will also contribute to low diffraction. Suitable bounds for the pattern on the first substrate and / or the second substrate or for the superposition include: less than 6.05%, or less than 5%, or less than 4%.

[0180] In one embodiment, substrates 11 and 12 are optically transparent outside the electrodes, typically >95% transparent at the relevant wavelengths, such as >99% transparent. When the electrodes are taken into account, the transparency is much lower, e.g., 70%. The term "optical" can relate to wavelengths visible to the human eye (from about 380 nm to about 750 nm) (where applicable), and can relate to a wider range of wavelengths including infrared (from about 750 nm to 1 μm) and ultraviolet (from about 10 nm to 380 nm) and sub - selections thereof (where applicable). In an exemplary embodiment of the light modulator, the substrate material is selected from glass and polymers.

[0181] In another embodiment, one substrate (such as the bottom substrate 12) can be reflective or partially reflective, while the top substrate 11 is transparent. The optical properties (especially the reflectivity of the light modulator) depend on the position of the particles 30 in the fluid. When the panel is in the (vertically - driven) on state, the particles will mostly be between the opposing electrodes of the two substrates so that incident light can pass relatively unimpeded through the transparent top substrate and the optical layer and be reflected or partially reflected on the bottom substrate.

[0182] The distance between the first substrate and the second substrate is typically less than 30 μm, such as 15 μm. In an exemplary embodiment of the light modulator, the distance between the first substrate and the second substrate is less than 500 μm, preferably less than 200 μm, preferably less than 100 μm, even more preferably less than 50 μm, such as less than 30 μm.

[0183] In one embodiment, the modulator may be disposed in a flexible polymer, and the remainder of the device may be disposed in glass. The glass may be rigid glass or flexible glass. If desired, a protective layer may be disposed on the substrate. If more than one color is provided, more than one layer of flexible polymer may be provided. The polymer may be polyethylene naphthalate (PEN), polyethylene terephthalate (PET) (optionally with a SiN layer), polyethylene (PE), etc. In another embodiment, the device may be disposed in at least one flexible polymer. Thus, the modulator may be attached to any surface, such as by using an adhesive.

[0184] Particles 30 may be adapted to absorb light and thereby prevent certain wavelengths from passing through. Particles 30 may reflect light; for example, the reflection may be specular reflection, diffuse reflection, or between specular and diffuse reflection. The particles may absorb some wavelengths and reflect other wavelengths. The particles may also or alternatively emit light, for example, using phosphorescence, fluorescence, etc. Even a fluid may emit light, and its emission rate is modulated by changing the position of the particles.

[0185] In an exemplary embodiment of the optical modulator, the size of the nanoparticles is from 20 nm to 1000 nm, preferably from 20 nm to 300 nm, more preferably less than 200 nm. In an exemplary embodiment of the optical modulator, the nanoparticles / microparticles may include a pigment coating and preferably include a core. In an exemplary embodiment of the optical modulator, the coating of the particles is made of a material selected from conductive materials and semiconductive materials.

[0186] In an exemplary embodiment of the optical modulator, the particles are adapted to absorb light having a wavelength from 10 nm to 1 mm, such as light having a wavelength from 400 nm to 800 nm, from 700 nm to 1 μm, and from 10 nm to 400 nm, and / or are adapted to absorb a portion of the light having a wavelength range falling within 10 nm to 1 mm (filter), and combinations of the above.

[0187] In an exemplary embodiment of the optical modulator, the particles are charged or can be charged. For example, the charge on the particles can be from 0.1 e to 10 e per particle (5*10 -7 to 0.1 C / m 2 ).

[0188] In an exemplary embodiment of the optical modulator, the amount of fluid present is from 1 g / m 2 to 1000 g / m 2 , preferably from 2 g / m 2 to 75 g / m 2 , more preferably from 20 g / m 2 to 50 g / m 2 , such as 30 g / m 2Up to 40 g / m 2 A great advantage of the layout of the present invention is that less fluid can be used, and similarly less particles can be used.

[0189] In an exemplary embodiment of the light modulator, the amount of particles present is from 0.01 g / m2 to 70 g / m 2 , preferably 0.02 g / m 2 to 10 g / m 2 , such as 0.1 g / m 2 to 3 g / m 2 .

[0190] In an exemplary embodiment of the light modulator, the color of the particles is selected from cyan, magenta, and yellow, and from black and white, and from combinations of the above.

[0191] In an exemplary embodiment of the light modulator, the fluid comprises one or more of a surfactant, an emulsifier, a polar compound, and a compound capable of forming hydrogen bonds.

[0192] Fluid 15 may be a non-polar fluid having a dielectric constant less than 15. In an exemplary embodiment of the light modulator, the relative permittivity εr of the fluid is less than 100, preferably less than 10, such as less than 5. In an exemplary embodiment of the light modulator, fluid 15 has a dynamic viscosity higher than 10 mPa·s.

[0193] Electrodes 13a, 13b and electrodes 14a, 14b are in fluid contact with the fluid. The fluid may be in direct contact with the electrodes, or in indirect contact with the electrodes, for example the fluid may contact a second medium to contact the electrodes, such as through a porous layer. In one embodiment, the electrodes cover from about 1% to 30% of the substrate surface. In one embodiment, the electrodes comprise a conductive material having a resistivity less than 100 nΩm (at 273 K; for comparison, typically used ITO has 105 nΩm), which is similar to a conductivity > 1*10 7 S / m) at 20 °C. In an embodiment of the light modulator, the electrodes comprise copper, silver, gold, aluminum, graphene, titanium, indium, and combinations of the above, preferably copper. The electrodes may be embedded in a polymer substrate in the form of micro-wires; for example, copper micro-wires.

[0194] A connection is used to apply an electromagnetic field to an electrode, where the applied electromagnetic field to the electrode provides for the movement of nanoparticles and microparticles from a first electrode to a second electrode and for the movement of nanoparticles and microparticles from the second electrode to the first electrode. A connection for applying an electromagnetic field to an electrode can be provided. For example, in an exemplary embodiment of an optical modulator, the current is between -100 μA and +100 μA, preferably between -30 μA and +30 μA, more preferably between -25 μA and +25 μA. For example, a power supplier can be electrically connected to at least two electrodes. The power supplier can be adapted to provide waveform power. At least one of the amplitude, frequency, and phase can be adapted to provide different states in the optical modulator. For example, an electrical controller can adapt multiple aspects of the power.

[0195] The optical modulator 10 can include one or more segments, where a segment is a single optically switchable entity and the size of the segment can be changed. The substrate encloses a volume, and the volume can be at least partially a segment.

[0196] The device can include a drive circuit that changes the appearance of an (individual) segment by applying an electromagnetic field. Thus, the appearance of the optical modulator or the appearance of one or more of its parts can be changed. For example, a segment can have an area of at least 1 mm 2 . This design allows for stacking to allow for more colors; for example, for full-color applications, a stack of two or three modulators can provide most or all of the colors respectively.

[0197] Having one or more segments allows the optical modulator to be locally controlled; this is advantageous for some applications but is not required. For smart glass, the optical modulator can be used with or without segments. For example, when applied in smart glass, the transparency or reflectivity can be locally controlled, such as blocking a sunspot without reducing the transparency or reflectivity of the entire window. A segment can be relatively large, such as having a diameter of at least 1 mm or at least 1 cm, etc.

[0198] In an exemplary embodiment of the optical modulator, the substrates (11, 12) are aligned and / or the electrodes (13, 14) are aligned. For example, the electrodes 13a, 13b and the electrodes 14a, 14b can be aligned relative to each other. In the aligned substrates, when viewed in a direction orthogonal to the substrates, the electrodes on different substrates are behind each other. When the optical modulator is disassembled and both substrates are arranged with the electrode faces up, the electrode patterns are mirror images of each other.

[0199] Aligning the substrates can increase the maximum transparency or maximum reflectivity of the light modulator. On the other hand, when selecting a light modulator for more criteria such as a transparency range or a reflectivity range, it may be better not to align or not fully align the two substrates. The light modulators can be stacked. For example, two stacked light modulators can be made of three substrates, where the middle substrate has electrodes on both of its surfaces. In one embodiment of the light modulator, optionally at least one of the substrates 11, 12 of the first light modulator is the same as at least one of the substrates 11, 12 of the second light modulator. For stacked modulators, alignment can also increase the maximum transparency or maximum reflectivity, but may be disadvantageous for other considerations (e.g., diffraction).

[0200] Figure 3b An embodiment of one implementation of the light modulator 40 is schematically shown. The light modulator 40 is similar to the light modulator 10, except that it includes a plurality of optical layers; in the illustrated embodiment, it includes two optical layers. There can be more than two optical layers. Each optical layer is arranged between two substrates. The light modulator 40 can be regarded as Figure 3a a stack of dual-substrate light modulators in. As shown, the light modulator 40 includes three substrates: a first substrate 41, a second substrate 42, and a third substrate 43. An optical layer is between the substrate 41 and the substrate 42, and an optical layer is between the substrate 42 and the substrate 43. The optical layers can be similar to the optical layers in the light modulator 10. The controller 46 is configured to control the current on the electrodes of the substrates. For example, in Figure 3b it, the controller 46 can be electrically connected to at least 8 (4 times 2 equals 8) electrodes.

[0201] Interestingly, the particles in the plurality of optical layers can be different such that the plurality of layers can be used to control multiple optical properties of the light modulator. For example, the particles located in different optical layers can absorb or reflect different wavelengths, e.g., can have different colors. This can be used to create different colors and / or different color intensities on the panel via the controller 46. For example, a four-substrate panel can have three optical layers with particles of different colors (e.g., cyan, yellow, and magenta) respectively. By controlling the transparency or reflectivity of different colors, a wide color spectrum can be created.

[0202] The substrate surfaces facing another substrate can be provided with two or more patterns, e.g., as in one embodiment. For example, the outer substrates 41 and 43 can receive electrodes only on the inner sides, while the inner substrate (e.g., substrate 42) can have electrodes on both sides.

[0203] The substrate 41 and the substrate 42 can be jointly regarded as one embodiment of the light modulator. Similarly, the substrate 42 and the substrate 43 can be jointly regarded as one embodiment of the light modulator.

[0204] Figure 3c An embodiment of an automobile 20 with a smart glass window 21 is schematically shown. This is an especially advantageous embodiment because during driving, the level of incident light changes frequently and rapidly. The advantage of using smart glass in an automobile is that by adjusting the transparency of the automobile window, the light level can be maintained at a constant level. In addition, the reduced diffraction effect improves safety because it reduces driver distraction. The automobile 20 may include a controller configured to control the transparency or reflectivity of the window 21.

[0205] Smart glass can also be used in other glass applications, especially in locations where the amount of incident light is variable, such as buildings, offices, housing, greenhouses, and skylights. A skylight is a window arranged in a ceiling to allow sunlight to enter a room.

[0206] The light modulator can have two optical states, such as a transparent state and a non - transparent state, or a reflective state and a non - reflective state. The light modulator (e.g., light modulator 10 or light modulator 40) can be configured to:

[0207] - Switch to a second optical state (e.g., non - transparent state or non - reflective state) by creating an alternating voltage on at least one of the first substrate and the second substrate, applying an alternating current between at least a first electrode and a second electrode on the first substrate, and / or applying an alternating current between a first electrode and a second electrode on the second substrate, and

[0208] - Switch to a first optical state (e.g., transparent state or reflective state) by creating an alternating voltage between the first substrate and the second substrate, applying an alternating current between a first electrode on the first substrate and a first electrode on the second substrate, and / or applying an alternating current between a second electrode on the first substrate and a second electrode on the second substrate.

[0209] The electrode pattern on the first substrate is arranged at least partially in the same pattern as the second electrode on the second substrate. Typically, the electrodes face each other, but the pattern of the first electrode and the pattern of the second electrode can also be shifted relative to each other.

[0210] A protective coating can be provided on at least a part of the inner surface area of at least one of the first substrate and the second substrate.

[0211] The drive signal applied to the drive electrodes typically has a varying voltage. For example, the power supplier can operate at an AC frequency for switching to a transparent state or a non-transparent state. Such a signal can have a frequency, for example, between 1 Hz and 1000 Hz. By continuously switching the polarities of the electrodes with opposite charges on the first substrate and the second substrate and / or between the first substrate and the second substrate, a balanced electrolytic current can be obtained.

[0212] Figures 4a - 4b A side view of one embodiment of a light modulator in use is schematically shown. Applying an electric field to the electrodes on the substrate results in an electric force on the particles. Utilizing this effect, the particles can be moved back and forth, so different transparency or reflectivity states can be generated in the light modulator. The controller can control the electric field, for example, controlling the amplitude, frequency, and phase of the electric field. In one embodiment, the controller is connected to at least four electrodes: two electrodes for each substrate. However, more electrodes can be used and connected to the controller; for example, more than two electrodes can be used for the substrate to better fine-tune the gray scale and can be used to drive to a non-transparent state or a non-reflective state. Multiple electrodes can also be used to support multiple sections on the substrate.

[0213] Figure 4a The light modulator is shown without an electric field applied. In Figure 4a , no electric force has been applied to the particles 30 suspended in the fluid 15.

[0214] In Figure 4a In the configuration shown, the conductive electrode pattern arranged on the top substrate and the conductive electrode pattern on the bottom substrate are completely or substantially aligned. The conductive electrode pattern can be provided on a transparent or (partially) reflective glass substrate, or can be embedded in a plastic substrate, etc.

[0215] The alignment between the top electrode pattern and the bottom electrode pattern helps to broaden the range of achievable transparency levels or reflectivity levels. However, alignment is not necessary because similar effects can be obtained without alignment. In the case of non-alignment, a range of transparency or reflectivity can also be obtained.

[0216] Note that in these embodiments, referring to the top substrate and the bottom substrate refers to the higher substrate or the lower substrate on the page. The same substrates can also be referred to as, for example, the front substrate and the rear substrate because in glass applications, the substrates will be vertically aligned rather than horizontally aligned.

[0217] Figure 4bA light modulator is shown, where, for example, in instance P1, a positive potential +V1 is applied to each micro-wire electrode on the top substrate, while a negative voltage such as -V1 is applied to each micro-wire electrode on the bottom substrate. Thus, in this case, the same positive potential is applied to all electrodes 13, and the same negative potential is applied to electrodes 14. The potential difference causes negatively charged particles to flow near the electrodes on the top substrate, where the particles will generally align with the top electrodes. As a result, if both the top substrate and the bottom substrate are transparent, the transparency of the light modulator 10 will increase. Similarly, if, for example, the top substrate is transparent and the bottom substrate is reflective, the reflectivity of the light modulator 10 will increase. If the solution contains positively charged particles, they will flow near the electrodes on the bottom substrate, where those particles will generally align with the bottom electrodes.

[0218] In a second instance P2 of the on state (where the voltages of the top and bottom electrodes are opposite to those in instance P1), a similar transparency or reflectivity can be achieved. In instance P2, the voltage of each electrode on the top substrate is now supplied with a negative potential -V1, while the voltage of the aligned electrodes on the bottom substrate is supplied with a positive potential. This state is similar to Figure 4b the state shown in

[0219] Interestingly, by switching between the positive potential (and the negative potential on electrode 14) at the electrodes on the top substrate (e.g., Figure 4b the electrodes 13 shown in Figure 4b and the positive potential at the electrodes on the bottom substrate (e.g.,

[0220] The applied waveform is optional, but it is an effective measure to increase the lifespan of the optical modulator by reducing corrosion. For example, when using copper electrodes, corrosion may form because copper ions are dissolved in the ionic fluid at one substrate and flow to the electrode on the opposite substrate, where they deposit. By applying a waveform, the direction of copper ion transport is frequently interchanged, thereby reducing corrosion damage. Between two instances P1 and P2, the corrosion current between the two substrates is balanced, or substantially balanced, e.g., >95% balanced. For example, as the corrosion rate of the electrode on the top plate occurs, there is balanced copper deposition on the bottom electrode between each time instance P1 and P2 and between each time instance P2 and P1. Thus, particles continuously transition or migrate between the top electrode and the bottom electrode, and the optical modulator or smart window is always in the on state, while the dynamic electrolytic current between the top electrode and the bottom electrode is constant, so that there is no net loss of electrode material on the top substrate and the bottom substrate, or there is a negligible net loss of electrode material.

[0221] Figure 4c Shows how a reduced transparency state or reflectivity state can be obtained. An alternating current voltage is applied to the same substrate. For example, in one embodiment, a potential +V2 is applied to the first electrode, and the next adjacent electrode has the opposite potential -V2, etc., as Figure 8c shown. This can be obtained by applying a potential +V2 to electrode 13a and the opposite potential -V2 to electrode 13b. On the opposite substrate, a potential +V2 can be applied to electrode 14a, and the opposite potential -V2 can be applied to electrode 14b. For example, the electrodes can be arranged such that the electrodes on the substrate are aligned; the electrodes on the top substrate have electrodes opposite to those on the bottom substrate, and vice versa. For example, to reduce transparency or reflectivity, the opposite electrodes can receive the same potential, while the adjacent electrodes receive opposite potentials. One embodiment is shown in Figure 4c where four electrodes are indicated by reference numerals 13a, 13b, 14a, and 14b, and the remaining electrodes continue to alternate.

[0222] By using such an AC drive cycle between the top substrate and the bottom substrate, a diagonal electric field and a transverse electric field are generated between the two substrates, thereby causing disordered diffusion of the particles, and thus creating a closed state of the optical modulator. As a result of this configuration, the particles perform diagonal migration and transverse migration between the top substrate and the bottom substrate, and the diffusion of the particles into the visible pores of the optical modulator contributes to the closed state and the opaque state of the optical modulator.

[0223] Regarding Figure 4b the transparent state shown, a waveform can be applied to the electrodes such that, for example, Figure 4b the electrode with a positive potential shown inFigure 4b In this case, applying waveforms between, for example, electrodes 13a and 13b and between electrodes 14a and 14b can reduce corrosive damage to the electrodes.

[0224] By using an interdigital line configuration in combination with Figure 1a , Figure 1b , Figures 2a to 2f the top and bottom electrodes shown in the plan views such as etc., an AC driving cycle can be implemented.

[0225] Figure 4b and Figure 4c The degree of increase or decrease in transparency or reflectivity in depends on the voltage difference and the frequency difference. By changing the voltage difference, the amount of increase or decrease in transparency or reflectivity is controlled. For example, a curve representing the light transmittance relative to the voltage can be determined (e.g., measured). To obtain a specific light transmittance level (e.g., a specific transparency, e.g., a specific gray level), the corresponding voltage (e.g., an AC voltage) can be applied. By interpolating the transparent state signal or the non-transparent state signal, a level between transparent and non-transparent can be obtained. Similarly, a curve representing light reflection relative to the voltage can be determined (e.g., measured). To obtain a specific reflectivity level, the corresponding voltage (e.g., an AC voltage) can be applied. By interpolating the reflection state signal or the non-reflection state signal, a level between reflection and non-reflection can be obtained.

[0226] Different electrode patterns can be used for the light modulator. Each electrode pattern can provide a range of gray levels (e.g., transparency levels or reflectivity levels) that the light modulator can achieve. However, the specific gray level range of any particular electrode pattern can be different from that of another electrode pattern. In other words, although different patterns give increased transparency or reflectivity or increased opacity, the precise response to the drive signal depends on many factors (including the specific pattern used). The change in the optical properties of the light modulator can have a fine resolution (e.g., less than 1 mm). Note that pixelation of the light modulator is not required to achieve different optical patterns (e.g., logos) visible in the light modulator.

[0227] This effect can be used to embed a visible image in the light modulator by locally changing the electrode pattern on the substrate of the light modulator. For example, due to different electrode patterns, there can be gray levels with a permanent gray level offset relative to each other locally. For example, by locally changing the electrode pattern or its pitch, the maximum transparency or the maximum reflectivity can be changed.

[0228] As a result, regions on the light modulator have different gray-scale intensities (e.g., different grays) or different coloring intensities. However, the regions can have the same color points. In one embodiment, the regions can be switched together with the remainder of the window, although at different rates. For example, even if the same voltage is applied to electrodes in two different regions, they will result in different transparency states (e.g., different transmittance levels) due to different electrode patterns. For example, the curve representing transmittance versus voltage can be shifted. For example, if the voltage control is changed in the same way in two regions, the light transmittance in the two regions can change, but the amount of change is different. The regions can also reduce their response to the drive signal by reducing the density of the electrodes; in particular, the regions can be completely non-switched, for example, by not applying electrodes in the region.

[0229] For example, the electrode material can be copper, aluminum, gold, indium tin oxide (ITO), etc. ITO is transparent while Cu / Al is reflective, so different electrode materials can provide different appearances regardless of the drive voltage. Similarly, different materials have different resistances and will generate different electric fields. For example, even when driven with the same voltage, ITO will have a smaller electric field.

[0230] One embodiment of a method of modulating light includes applying an electric potential to a plurality of drive electrodes (in one embodiment, the plurality of drive electrodes are applied to two opposing substrates) to obtain an electromagnetic field between the plurality of drive electrodes, thereby providing electrophoretic movement of particles towards one of the plurality of drive electrodes or providing electrophoretic movement of particles away from one of the plurality of drive electrodes, and thereby causing modulation of light passing through the substrate, where the two opposing substrates are as in one embodiment.

[0231] The light modulator described herein includes a first substrate according to one embodiment. For example, the first substrate can be transparent and have drive electrodes and patterned elements applied to it. The drive electrodes can be configured for electrophoretic control and / or dielectrophoretic control of particles in the optical layer of the light modulator.

[0232] The light modulator can include a second substrate. The second substrate can also have patterned elements or can be a conventional substrate without patterned elements. Having patterned elements in at least one substrate (e.g., the first substrate) provides control of light diffraction and is an improvement over known light modulators. Having optical active elements on both substrates (e.g., the first substrate and the second substrate) also provides additional control.

[0233] In one embodiment, the second substrate can be non-transparent, e.g., opaque. For example, such an embodiment can be used in a dynamic mirror or an electronic reading system. Typically, especially in smart glass applications, both the first substrate and the second substrate are transparent.

[0234] Figure 5a An embodiment of a light modulator 501 is schematically shown. The light modulator 501 includes a first transparent substrate 511 and a second transparent substrate 512. An optical layer 524 extends between the first transparent substrate 511 and the second transparent substrate 512. Particles 523 are in the optical layer 524, and the particles 523 affect the optical appearance of the light modulator. At least one drive electrode 521 is applied on the first substrate 511. By applying an electric potential to at least one drive electrode 521, the optical properties of the light modulator can be modified. In the illustrated embodiment, at least one drive electrode 522 is also applied on the second substrate 512.

[0235] The illustrated light modulator is in a state where the particles and the electrodes are aligned. This typically corresponds to the most transparent state of the light modulator. In another state of the light modulator, the particles can be dispersed in the optical layer 524. This typically corresponds to the most opaque state of the light modulator. Depending on the properties of the particles, this can be an opaque state (e.g., absorbing light), or this can be a reflective state (e.g., reflecting light).

[0236] The surface of the substrate 511 or 512 that faces the optical layer 524 is referred to as the first surface.

[0237] At least one drive electrode 521 is arranged in a pattern across the substrate 511. At least one electrode 521 is arranged to receive an electric potential, thereby causing modulation of the optical properties of the light modulator. At least one drive electrode 522 is arranged in a pattern across the substrate 512. At least one electrode 522 is arranged to receive an electric potential, thereby causing modulation of the optical properties of the light modulator.

[0238] In a preferred light modulator, e.g., in Figure 5a the preferred embodiment of the light modulator shown in, at least two drive electrodes are applied on the first substrate 511, and at least two drive electrodes are applied on the second substrate 512. In this preferred light modulator, the particles 523 in the optical layer 524 are charged and movable under the action of an electrophoretic force, which can be modified by the electrodes on the substrates.

[0239] The patterned element 541 is applied to the surface of the substrate 511 to change the phase, amplitude, and / or polarization of light interacting with the substrate. That is, the surface of the substrate 511 is configured with optical properties, thereby turning the substrate into a so-called metasurface. In this case, the patterned element 541 is applied to the second surface of the substrate 511, for example, the surface opposite to the surface carrying at least one electrode 521. For example, the patterned element can be an optical element whose diameter parallel to the substrate is less than one micrometer. Patterning is the process of fabricating microstructures and / or nanostructures across the surface of a material (referred to as the substrate).

[0240] The patterned element 542 is applied to the surface of the substrate 512 to change the phase, amplitude, and / or polarization of light interacting with the substrate. That is, the substrate 512 is also provided with a metasurface. In this case, the patterned element 542 is applied to the second surface of the substrate 512, for example, the surface opposite to the surface carrying at least one electrode 522. It is not necessary to locate the patterned element 542 on a second substrate, although this is advantageous as it provides more control.

[0241] Micro - patterning and / or nano - patterning is the process of fabricating nanostructures across the surface of a material (referred to as the substrate).

[0242] The optical modulator 501 also shows spacers 531. The spacers ensure that the optical modulators are held at a desired distance from each other. For example, the spacers can be made of the same material as the substrate, and multiple spacers can be distributed across the substrate. The spacers are optional; for example, instead of spacers, a border can be arranged around the substrate to hold the substrate at a specific desired distance.

[0243] The advantage of arranging the nanoparticles on the second surface of the substrate (e.g., not on the same side as the surface with the driving electrodes) is that the distribution of the optical elements does not interfere with the optical electrodes and vice versa.

[0244] Figure 5b An embodiment of an optical modulator 502 is schematically shown. The optical modulator 502 is similar to the optical modulator 501, except that in this embodiment, the patterned element is arranged on the same dimensions as the driving electrode. Figure 5b The patterned element 543 on the first surface of the substrate 511 is shown. Figure 5b The patterned element 544 on the first surface of the substrate 512 is shown.

[0245] Locating the patterned element on the same side as the surface allows the patterned element to face the optical layer. This protects the patterned element from damage, such as abrasion.

[0246] In Figure 5bIn the illustrated embodiment, patterned elements are provided on both substrates, but such an arrangement of the two substrates is not necessary.

[0247] Figure 5c An embodiment of an implementation of a light modulator is schematically illustrated. Figure 5c The illustrated light modulator is identical to the light modulator in Figure 5b , except that the positions of the particles in the optical layer have been changed. This can be achieved by applying a control signal to the drive electrodes, which are applied to the electrodes of the substrate. Note that as a result, the optical effect of the patterned elements can be changed. There are various ways to handle this situation. The first option is to accept this effect. In this case, the patterned elements can be optimized for the average case and / or common cases, such as maximum transparency, maximum opacity. The second option is to apply the control signal to the patterned elements as well, to modify their effect, for example to create a canceling effect in the patterned elements.

[0248] Figure 6a An embodiment of a transparent substrate 601 for a light modulator (e.g., light modulator 501, light modulator 502, or any other light modulator according to an implementation) is schematically illustrated.

[0249] Substrate 601 schematically shows two drive electrodes: drive electrode 611 and drive electrode 612. These two drive electrodes are arranged in an interdigitated pattern. Thus, local control of the electric field can be applied across the substrate, thereby locally controlling the electrophoretic movement of the particles. The metasurface can also be applied to other types of light modulators.

[0250] Figure 6a Shown therein are the patterned elements. The patterned elements are arranged in a pattern across the substrate according to the specific optical effect desired. Figure 6a Also shown is a virtual cut line 631. Light modulators 501 and 502 can be considered as cross-sections across line 631. Note that the spacer 531 is not shown in Figure 6a .

[0251] For example Figure 6a , Figure 5a , Figure 5b and the patterned elements shown elsewhere are two-dimensional or three-dimensional objects with nanometric geometries. Typically, the patterned elements protrude from the surface. The shape and distribution of the patterned elements change the optical properties of the substrate. This is sometimes referred to as a metasurface. The optical properties of the metasurface can be calculated using optical simulation software.

[0252] The patterned elements on the substrate can have a variety of different sizes, different shapes, and / or different materials. For example, the patterned elements can be obtained by displacing a two-dimensional shape parallel to the substrate into a three-dimensional space away from the substrate surface. For example, the two-dimensional shape can be a polygon, a circle, an ellipse, and so on. The shape of the patterned elements can be changed in the three-dimensional space. The patterned elements can be cylindrical, elongated, and / or curved.

[0253] The patterned elements can extend from the surface and have a height of less than 1000 nanometers. Preferably, the height is between 100 nanometers and 1000 nanometers, such as 600 nanometers.

[0254] For example, the light modulator can be arranged to be used within a defined spectral range (such as visible light). The patterned elements can be transparent within the defined spectral range, for example, transparent to visible light. The spectral range of visible light can be defined as 400nm - 750nm. The patterned elements can be used to configure the spectral properties of the light modulator.

[0255] The total transmittance of the patterned elements within the defined spectral range can be greater than a threshold, for example, at least 70%, for example, at least 80%. The total transmittance of the patterned elements can be in the range of [x - 5, x + 5], where x is the total transmittance of the substrate.

[0256] Interestingly, the patterned elements do not need to be transparent. In one embodiment, the total transmittance of the patterned elements within the spectral range is at most 10%.

[0257] The spectral range can include infrared light, for example, having a wavelength between 750 nanometers and 1000 nanometers or 1500 nanometers. The spectral range can include visible light and infrared light, for example, having a wavelength between 400 nanometers and 1000 nanometers or 1500 nanometers.

[0258] The patterned elements are placed in the optical path through the substrate and the optical layer. Since the patterned elements have an optical effect on light, they affect the optical properties of the light modulator. Therefore, by arranging the shape and / or pattern of the patterned elements, the optical properties of the light modulator can be changed. For example, the patterned elements can change the wavefront of the light reflected from the substrate or the wavefront of the light transmitted through the substrate.

[0259] Figure 6b An embodiment of a transparent substrate 602 for a light modulator is schematically shown. Figure 6b The view is from the top. In Figure 6b visible are the patterned elements; one of the patterned elements has the reference numeral 622. Figure 6bis too large; a virtual scale of 1 micron is shown at reference numeral 632. The patterned element shown can be embodied as a transparent cylinder. The top circular view of the cylindrical pattern is visible in Figure 6b is visible. Figure 6b The pattern shown is a detail; the pattern extends across a substrate in one embodiment. Additional details regarding the cylindrical pattern can be found in the paper “Flat optics with dispersion-engineered Metasurfaces” by WeiTing Chen et al., which is incorporated herein by reference. Table 1 of the latter paper also shows various materials suitable for metasurfaces and information regarding dimensions and bandwidths.

[0260] Instead of a cylinder, the patterned element can have a variety of other shapes. For example, the top view of the patterned element can be V-shaped, such as that shown in the paper “Broadband Light Bending with Plasmonic Nanoantennas” by Xingjie Ni et al., which is incorporated herein by reference. This paper also explains a generalized form of Snell's law, which allows for better control of light manipulation. Metasurfaces can be designed such that the theoretical predictions given by the generalized Snell's law match the experimental data well.

[0261] A variety of CMOS fabrication techniques can be used to fabricate metasurfaces. The paper “Large-area metasurface on CMOS-compatible fabrication platform: driving flat optics from lab to fab” by Nanxi Li et al. (which is incorporated herein by reference) discusses large-scale producible, low-cost, large-area metasurfaces that can be fabricated using common semiconductor techniques (e.g., with a lithography stepper and scanner).

[0262] An embodiment of a method for fabricating a metasurface is given in the paper “High-efficiency dielectric metasurfaces at visible wavelengths” by Robert C. Devlin et al. (which is incorporated herein by reference). For example, FIG. 2 of the latter paper shows the fabrication process of a dielectric metasurface.

[0263] Figure 6c.1 An embodiment of an implementation of a transparent substrate for an optical modulator is schematically shown. Figure 6c.2 An embodiment of an implementation of a transparent substrate for an optical modulator is schematically shown.Figure 6c.1 A side view is shown. Figure 6c.1 A top view is shown that has the same configuration as Figure 6c.1 the configuration shown. A substrate having two patterned elements is shown in the figure.

[0264] The patterned element has a 2D diameter, which is defined as the maximum diameter in a two-dimensional cross-section of the substrate parallel to the nanoelement. For example, the 2D diameter is the maximum distance between any two points of the patterned element, where the two points are restricted to lie in the same plane parallel to the substrate. The 2D diameter is indicated by reference numeral 662 in the figure.

[0265] The patterned element has a height, which is defined as the maximum extent of the patterned element measured in a direction perpendicular to the substrate from the substrate. The height of the two patterned elements is indicated by reference numeral 661. In addition, the distance to the next nearest element is indicated by the number 663.

[0266] In one embodiment, the 2D diameter, height, and nearest distance are related to a target frequency at which the patterned element is active.

[0267] For example, in one embodiment, the 2D diameter is at most 10 microns, at most 2 microns, at most 1 micron, or at most 500 nanometers.

[0268] For example, in one embodiment, the minimum distance between the two patterned elements is at most 2 microns, at most 1 micron, or at most 500 nanometers. For example, in one embodiment, the minimum distance between the two patterned elements is at least 10 nanometers, at least 50 nanometers, at least 100 nanometers, 200 nanometers, or 400 nanometers.

[0269] If one dimension of the patterned element is small, the patterned element is allowed to have a longer other dimension. For example, in one embodiment, the patterned element has at least two non-continuous edges, and the minimum distance between two points on a corresponding one of the non-continuous edges is at most 2 microns, at most 1 micron, or at most 500 nanometers. For example, the patterned element can be a polygon, such as a rectangle. The rectangle can have a short edge, such as less than the indicated range, while the other edge can be longer, such as longer than 2 microns.

[0270] For example, in one embodiment, the patterned element extends in at least two directions. For example, the two directions can form an angle between 30 and 150 degrees, an angle between 60 and 120 degrees, for example an angle of about 90 degrees. For each direction, the longest distance can be identified, for example the longest distance between two points in the same patterned element. In one embodiment, the shorter of the two distances is at most 2 microns, at most 1 micron, or at most 500 nanometers. For example, the nanoelement can be an ellipse with a length greater than its width.

[0271] In one embodiment, the sizes of the patterned elements or the distances between their objects can be different. For example, in one embodiment, different optical effects can be desired at different positions of the light modulator. For example, in a logo, a holographic effect may be desired in a part of the light modulator, but not at every position. Thus, small patterned elements and large patterned elements, small inter-object distances or large inter-object distances can be mixed in the light modulator.

[0272] For example, in one embodiment, the height is at most 2 microns, at most 1 micron, or at most 500 nanometers, and preferably, the height is between 100 nanometers and 1000 nanometers.

[0273] In one embodiment, the 2D diameter, height, and closest distance are all at most 2 microns, at most 1 micron, or at most 500 nanometers.

[0274] The height of the patterned element can be uniform; for example, the patterned element can have a flat top parallel to the substrate. Figure 6c.1 The patterned elements on the left side in have a uniform height. The height of the patterned elements can also be uniform across the substrate; for example, all patterned elements have the same height. Figure 6c.1 The two patterned elements in have the same height.

[0275] The height of the patterned element is typically much smaller than the height (e.g., thickness) of the substrate, although the patterned element can also be applied to a thin substrate. For example, in one embodiment, the substrate has a thickness of 10 microns or greater, while the patterned element has a height of less than 1 micron, for example. For example, the substrate can be a plastic film. The thickness of the substrate can be at least 10 times the height of the patterned element. However, the ratio is typically higher. In one embodiment, the thickness of the substrate can be, for example, at least 100 times or at least 1000 times the height of the patterned element.

[0276] Figure 6d.1 and 6d.2 illustrates the function of the metasurface in the context of a light modulator.

[0277] Figure 6d.1An embodiment of a light modulator 643 without patterned elements is schematically shown.

[0278] Shown is the original wavefront 642 incident on the light modulator. For example, the light modulator can be smart glass, and the original wavefront 642 can be from ambient light, such as sunlight. The light modulator 643, indicated only schematically, can be of the Figures 4a - 4c , Figures 5a - 5b type shown, but without the patterned elements that create a metasurface on the light modulator. Shown in the light modulator 643 is a cross-section of drive electrodes arranged in a pattern on a substrate; in this case, the electrodes are arranged on two substrates.

[0279] After the wavefront has passed through the light modulator 643, the pattern of the electrodes has a distorting effect on the wavefront. The distorted wavefront 644 is shown in Figure 6d.1 . The distortion is visible in optical artifacts such as rainbow effects and diffraction. The distortion can also be calculated using the generalized Snell's law.

[0280] Figure 6d.2 An embodiment of an implementation of a light modulator 653 with patterned elements is schematically shown. Figure 6d.2 The light modulator in Figure 6d.1 is similar to the light modulator in

[0281] , except that it includes patterned elements forming a metasurface according to an implementation. Figure 6d.1 Shown is the original wavefront 642 incident on the light modulator. The light modulator 644 uses the same drive electrodes as

[0282] but includes patterned elements extending across the substrate to form a metasurface on the light modulator. One patterned element is shown by reference numeral 655. In this embodiment, the patterned elements are applied on one side of each substrate, in this case on the side facing the optical layer of the light modulator 653. As shown herein, the metasurface can alternatively or equally be formed on a surface remote from the optical layer; the metasurface can be formed on only one substrate, or on more than two substrates. Figure 6d.2 Shown is the corrected wavefront 654.

[0283] The patterned elements have been selected in a computerized selection algorithm. The algorithm calculates the effect of the combination of the drive electrodes and the patterned elements on the original wavefront 642. The position and / or shape of the patterned elements are modified in multiple iterations to minimize a loss function (including one or more loss terms).

[0284] The loss term used in this case includes the distance term between the outgoing wavefront and the normal original incoming wavefront. That is, any optical changes in the wavefront are minimized. For example, the minimization can be for a specific light frequency or for multiple light frequencies, such as representing visible sunlight. For example, the minimization can be for light at multiple angles. The severity of optical artifacts can depend on the properties of the light, such as its direction and frequency. By performing simulations under a series of conditions, a design with generally good performance can be selected.

[0285] Therefore, multiple candidate designs can be simulated for a series of conditions (e.g., different light conditions). A design with preferred simulation results is selected from the multiple candidate designs, such as the design with the lowest average loss under multiple conditions.

[0286] The loss term (which can be used or additionally or alternatively) directly evaluates the severity of known artifacts (e.g., rainbow effect and diffraction). Minimizing this loss term allows the optical modulator to affect the light but reduces interfering factors. Optimization can use hill-climbing techniques such as simulated annealing.

[0287] To reduce the computation time, in one embodiment, the pattern of the patterned elements forming the metasurface can be optimized for a small area (e.g., building blocks), which can be repeated across the substrate.

[0288] To reduce the computation time, in one embodiment, the patterned elements are selected from a predetermined group with a limited number of sizes, such as using a group of cylindrical or V-shaped elements. Optimizing the metasurface can now be reduced to selecting from a finite number of element sizes and element positions. Therefore, the optimization does not need to consider all possible size ranges. Further reduction of the computation time can be obtained by restricting the positions of the elements to a predetermined grid. Further reduction of the computation time can be obtained by restricting the possible rotations of the elements to a finite number of predetermined sizes. The latter optimization is not applicable to curl-symmetric elements (e.g., cylinders), but can be used for polygonal shapes (e.g., V-shaped elements).

[0289] The optimization can also optimize the positions of the electrodes along with the positions of the patterned elements. In this case, the loss term can also include losses specific to the electrodes, such as how well the optical modulator operates, such as speed and consistency of state transitions.

[0290] In Figure 6d.2 , the optimization aims to reduce the influence of the electrodes on the wavefront. However, this is not necessary; alternatively, the optimization can aim to introduce any desired changes into the wavefront. For example, in one embodiment, the patterned elements are configured to change the wavefront 642 of the light passing through the substrate, thereby generating a holographic image.

[0291] Patterning elements (e.g., sub-wavelength scale geometries) can be customized to produce a wide range of optical functions. To produce a metasurface design (e.g., the pattern of patterning elements that gives a desired optical response), topology optimization can be employed, such as using free-form metasurfaces. For example, topology optimization can use a local gradient-based optimizer, such as using the adjoint variable method. The local gradient-based topology optimizer takes an initial device design and iteratively improves it by perturbations (e.g., making small changes to the geometric layout of the metasurface and / or patterning elements) to approach the desired optical response. Advantageously, the perturbations can be obtained using the adjoint variable method. This method allows the creation of advanced metasurfaces with capabilities beyond those of existing design methods.

[0292] For example, gradient-based optimization can use the adjoint variable method. In this method, a set of adjoint variables is introduced and used to compute the gradient of the objective function with respect to the design variables. Then, this gradient information is used to make small adjustments to the design to improve the performance of the system. The objective function can include aberration parameters such as diffraction and rainbow effects, consistency, and possibly the target gray level. The optimization can be combined with one or more distributions of particles, such as can be produced with drive electrodes, for example Figures 5a - 5c as shown.

[0293] Topology optimization is further discussed in J.Fan's 'Metagrating Topology Optimization' (incorporated by reference).

[0294] The pattern of the patterning element (e.g., metasurface) can be used for a variety of purposes. An important application is to correct the optical effects of the electrodes. Like the patterning element, the drive electrodes also affect the optical effects of the modulator. The patterning element can create an optical effect opposite to that created by the drive electrodes of the modulator, such as compensating for the optical aberrations generated by the drive electrodes. For example, Figure 6a a common problem with substrates of the type shown is diffraction, sometimes referred to as the rainbow effect. The patterning element can cancel the diffraction caused by the electrodes. Figures 2a - 2f The patterns shown have different degrees of diffraction. For example, in this regard, pattern 2f has much better properties than, for example Figure 2b the pattern shown. However, in both cases, adding the patterning element helps reduce the rainbow effect.

[0295] The patterning element can be configured to compensate for various optical artifacts of the light modulator. The optical artifacts can be one or more of the following group: diffraction, refraction, light scattering, perturbations when light passes through or reflects from the substrate. The diffraction effect caused by the drive electrodes can be reduced by arranging the patterning element to create an equal but opposite aberration.

[0296] In one embodiment, the patterned element is configured to reduce (e.g., minimize) light reflection. In this way, due to the reduced reflection, the opaque state of the light modulator is seen as a deeper black.

[0297] In one embodiment, the patterned element is configured to focus the incident light on the inner side of the optical layer of the light modulator. This reduces artifacts. For example, in a light modulator including a first substrate, an optical layer, and a second substrate, the patterned element on the first substrate and / or the second substrate can be arranged to focus the incident light on the inner side of the optical layer (e.g., the light irradiated onto the first substrate and / or the second substrate from outside the light modulator).

[0298] The patterned element can provide light wavelength control, thereby filtering the light passing through the substrate according to the wavelength. For lights of different wavelengths, the optical effects provided by the patterned element may be different. The patterned element can provide light polarization control to manipulate linear polarization or circular polarization. For example, polarization is affected by a patterned element with non-rotational symmetry, e.g., a rectangular, non-square object affects polarization.

[0299] In one embodiment, the patterned element is fixed. For example, the element can be applied to the substrate in a predetermined shape by a fixed material. For example, the element is passive. Although this is not necessary. In one embodiment, the patterned element introduces optical distortion depending on external factors such as temperature, pressure, and / or electric field. For example, the patterned element can include a phase change material. For example, the patterned element has a controllable shape. For example, the patent application US2021333575A1 (incorporated herein by reference) discloses a reversible phase change material suitable for being incorporated into a meta-lens.

[0300] For example, in one embodiment, the nano-elements can be controlled, preferably electrically controlled independently of the electrodes, and / or can be controlled by temperature. Preferably, the nano-elements can be independently controlled.

[0301] In one embodiment of the light modulator, there is an interaction between the temperature of the light modulator and the phase change of the metasurface due to the temperature.

[0302] The temperature in the light modulator can be changed in various ways, such as heating elements, such as heating wires, micro-heating elements. The paper “Modeling and fabrication of Pt micro-heaters built on alumina Substrate” by Goran Miskovic shows micro-heating elements on a glass-coated substrate; the paper is included herein by reference.

[0303] By changing the shape of the patterned element, control over the way the light modulator modifies the wavefront can be obtained. For example, a patterned element with a shape that can be changed can be arranged in different shapes, for example, during the operation of the light modulator. This allows, for example, changing the phase, amplitude, and / or polarization of the light interacting with the substrate. For example, in one embodiment, the patterned element includes a phase change material that has an optical distortion depending on external factors such as temperature, pressure, and / or an electric field.

[0304] Figure 6e.1 An embodiment of a light modulator with a conductive patterned element in an inactive state is schematically shown. Figure 6e.2 An embodiment of a light modulator with a conductive patterned element in an active state is schematically shown. The substrate in these figures can be used as one of the substrates in a light modulator, for example, an electrophoretic light modulator, such as Figures 3a - 5b of the type shown in any of them.

[0305] The patterned element is applied to the substrate, shown here from the top in a plan view. The patterned element is shown as rectangular. The patterned element is transparent, for example, transparent to visible light or transparent in the target spectrum. As a result, the patterned element has a reduced optical effect. For example, they can form a metasurface, but its effect may be relatively small. In particular, the patterned element can be arranged to have a refractive index close to that of the substrate to further reduce the optical effect.

[0306] In one embodiment, a substrate (e.g., a first substrate) is used in a light modulator configured such that particles can be aligned with the patterned element. This can be achieved by arranging drive electrodes near or below the patterned element, but a particularly advantageous way to achieve this is to use a conductive patterned element. The conductive patterned element can be supplied with an electric potential so that particles can be moved towards the conductive patterned element, for example, using an electrophoretic force. For example, the second substrate can have a conductive patterned element aligned with the element of the first substrate. For example, the element of the second substrate can be arranged as a mirror image pattern with respect to the pattern on the first substrate.

[0307] By applying an electric potential to the conductive patterned element, charged particles are aligned with the conductive patterned element. This effect is shown in Figure 6e.2 Although the previous patterned element was transparent and had a small optical modulation effect, by aligning the particles, the transparency is reduced and the optical effect of the patterned element is increased. In this way, a metasurface is created, and the effect of the metasurface can be increased or decreased according to the desire.

[0308] The conductive patterned element can be electrically controlled by the same drive electrodes used in the light modulator to modulate light. The conductive patterned element can be electrically controlled by drive electrodes specifically applied for the conductive patterned element.

[0309] Thus, in one embodiment, the patterned element can be conductive and arranged to modulate particles, such as light-absorbing particles, for example particles that absorb light in a target spectrum (e.g., visible light). The optical properties of the patterned element can be modulated. The patterned element can include ITO, such as an ITO patch.

[0310] In one embodiment, all or part of the patterned elements on the substrate are transparent and conductive patterned elements. For example, they can be transparent in accordance with the transparency of the absorption range targeted by the light modulator and / or the substrate. For example, the light modulator can be arranged to be used within a defined spectral range (such as visible light). The patterned element can be transparent within a defined spectral range, for example transparent to visible light.

[0311] Furthermore, the optical parameters of these patterned elements can be close to the optical parameters of the substrate, especially the refractive index. For example, the refractive index of the patterned element can be within 10% of the refractive index of the substrate.

[0312] The conductive patterned element is configured to interact with the particles in the optical layer of the light modulator.

[0313] The patterned element is arranged to receive an electric potential to provide control of the optical modulation in the light modulator. For example, the patterned element is independently electrically addressable, such as in a row-column addressing scheme. The patterned element can be applied on the first surface in a regular grid (the regular grid covering at least a part of the first surface, such as in a regular grid as part of a row-column addressing scheme). Row-column addressing can use electrodes separate from the drive electrodes. For example, the light modulator can be pixelated, with rows and columns addressing the patterned elements and optionally the drive electrodes. This allows for local adaptation of the optical effect and optionally local adaptation of the transparency.

[0314] The light modulator is configured to control the gray level of the light modulator by modulating the position of the particles in the optical layer. This can be achieved by applying a control signal (e.g., an electrical control signal) to the electrodes on the substrate. For example, in one embodiment, each of the two substrates has at least two electrodes such that the charged particles in the optical layer between the two substrates can be controlled to obtain a controllable gray level. For example, the signal can be an AC signal.

[0315] In one embodiment, the optical effect of the patterned element can also be modulated in a light modulator. For example, the patterned element can be modulated by changing the temperature, such as in a pattern including a phase change material. For example, the patterned element can be conductive so that light-absorbing particles in the optical layer can accumulate near the patterned element.

[0316] The light modulator can be configured to control the light modulator by applying a first control signal to a drive electrode and a second control signal to the patterned element. In one embodiment, the second control signal for the patterned element depends on a desired gray level setting within the modulator, such as set by a user.

[0317] For example, the signal can be obtained during a calibration phase prior to the operation phase. For example, the light modulator can be installed at its final destination, such as in the form of smart glass. A sensor (e.g., a camera) can be arranged to observe the effect of the light modulator. The sensor measurements can be used to modify the first control signal and / or the second control signal to reduce the occurrence of unwanted phenomena (e.g., diffraction, rainbow effect). For example, during the calibration phase, the light modulator can be driven by a series of first control signals and second control signals. The sensor measurements of the multiple signals are recorded, such as images. Optical parameters are derived from the sensor measurements, especially the gray level (e.g., the transparency level of the light modulator) and the distortion value (e.g., the amount of observed diffraction and / or rainbow effect).

[0318] In one embodiment, information about the direction of incident light (e.g., sunlight) can be obtained from a GPS sensor (e.g., as part of a satellite navigation device). This is particularly useful in an automobile (e.g., an automobile with smart glass). This information can be obtained dynamically during operation.

[0319] In one embodiment, information about the glass orientation can be obtained, for example, by applying a sensor to the glass (e.g., during the calibration phase). The sensor can be fixed, such as part of a smart glass package. However, it can also be temporary. In particular, the orientation information can be obtained by placing a smartphone flat on the glass. For example, an app on the smartphone can forward the orientation information to the controller of the smart glass, such as the light modulator.

[0320] The orientation information is useful because the control signal for the patterned element can depend on the current angle of the light.

[0321] The algorithm can be applied to sensor values and calibration control signals, for example, to derive a model of the optical modulator from sensor measurements that predict the optical effects of the optical modulator and its current control signal. The model or algorithm can be computational, for example, applying physical laws such as Snell's law, but advantageously can alternatively be a machine learning model. For example, a neural network can be trained to predict the optical effects based on the control signal and possibly other sensor values, and the optical modulator can be equipped with sensors such as temperature sensors and light sensors. From the sensor values showing the effects of specific control signals, the algorithm learns which control signal to use to obtain a specific effect. After the calibration period, the camera can be removed. In one embodiment, the system can continue to learn and further optimize the model, for example, using user feedback or sensor measurements. Additionally, relatively slow changes in the environment are automatically taken into account. The optical modulator can be manufactured independent of the environment in which it will ultimately be installed and operated while still achieving fine optical control. The control of the metasurface can depend on the angle and intensity of the incident light.

[0322] Accordingly, the first control signal and the second control signal can be stored or derived when needed. Depending on the current sensor values (e.g., current temperature and / or current light level or light angle), an appropriate control signal can be derived.

[0323] One embodiment of a method for calibrating an optical modulator includes:

[0324] - Providing an optical modulator, for example, installing the optical modulator. The optical modulator can be installed in a fixed position, such as smart glass in a building (e.g., an office). The optical modulator can be installed in a non-fixed position, such as smart glass in a vehicle (e.g., a car).

[0325] - Obtaining information about the distortion and / or transparency of the optical modulator from an image sensor observing the optical modulator. For example, the image sensor can be a temporary image sensor installed to obtain information about the optical effects of the optical modulator. For example, the image sensor can be a camera placed in front of the optical modulator during the calibration phase. For example, the camera can be placed on a tripod. For example, the image sensor can be placed inside a room in a building where the glass is located. For example, the image sensor can be placed inside a vehicle where the glass is located. If the optical modulator is non-fixed, the optical modulator can be moved (e.g., by driving the vehicle in which the optical modulator is installed) during or as part of the calibration phase, possibly while recording orientation information.

[0326] - Deriving a control signal for controlling the optical modulator during the operating phase.

[0327] During the calibration phase, multiple control signals for driving electrodes and / or for patterning elements may be applied. The image sensor may observe their effects. The effects may be summarized as distortion values and transparency values (e.g., gray values). The control signals providing the desired effects (e.g., specific transparency and low distortion) may be stored. New control signals may be derived from the stored control signals, e.g., by interpolation. A machine learning model may be trained to predict the effects of the light modulator based on the control signals. Advantageous control signals may be derived by trying multiple control signals in the trained model, e.g., selecting the control signals with desired parameters.

[0328] In one embodiment, the calibration method further includes obtaining orientation information about the light modulator from an orientation sensor applied to the light modulator. For example, the orientation sensor may be shared with a GPS device (e.g., a satellite navigation device or a smartphone). The orientation sensor may also be separate. The orientation sensor may be temporary, e.g., applied only during the calibration phase. In one embodiment, the light modulator includes an orientation sensor.

[0329] The orientation sensor and the image sensor may be configured to provide sensor data (e.g., measurements, e.g., information about the image and / or orientation) to the controller of the light modulator.

[0330] After the calibration phase, the light modulator may be controlled. The method of controlling the light modulator may include: applying an electric potential to the driving electrode, modulating the electromagnetic field in the optical layer, providing electrophoresis and / or dielectrophoresis of particles in the optical layer, modulating the light passing through the substrate. For example, the control signal applied to the driving electrode may be the control signal stored during the calibration phase. The control signal applied to the patterning elements on the surface of the light modulator may change the phase, amplitude, and / or polarization of the light passing through the substrate.

[0331] The patterning elements may be passive, e.g., may not be configured to receive control signals. In one embodiment, the patterning elements are active, e.g., configured to receive control signals to modulate their optical effects. For example, the patterning elements may include phase change materials having optical distortion depending on external factors such as temperature, pressure, and / or electric field, and the method includes modulating the external factors so as to modulate the optical distortion. The patterning elements may be conductive and arranged to modulate their optical effects through particles selectively arranged on top of the patterning elements. The control method may include modulating the external factors, e.g., applying a control signal, to modulate the optical distortion. The control signal may be stored in the calibration phase or derived from the calibration phase.

[0332] The patterning elements may be combined with a coating and may be applied to multiple surfaces of the substrate, with multiple advantages. All Figures 7a - 7gBoth show a substrate for an optical modulator. The substrate in the figure assumes that the ambient light is above the figure and the optical layer is below the substrate. Only in Figure 7a is the side configured to be oriented towards the optical layer schematically indicated by reference numeral 712, while Figures 7b - 7g is oriented in the same way. The bottom substrate can be obtained from either of Figures 7a - 7g by mirroring it about the horizontal axis.

[0333] Figure 7a An embodiment of an embodiment of a transparent substrate for an optical modulator is schematically shown. The figure shows the transparent substrate 711.

[0334] The substrate 711 has two surfaces; the first surface is configured to be oriented towards the optical layer of the optical modulator; this side of the substrate is indicated by reference numeral 712.

[0335] Starting from the substrate 711, a layer having patterned elements is applied to the first surface of the substrate 711. One patterned element is indicated by reference numeral 745. The patterned elements are arranged to change the phase, amplitude, and / or polarization of the light interacting with the substrate. The light interacting with the substrate includes the light passing through the surface and / or the light reflected from the surface. For example, the patterned elements can be arranged to form a metasurface.

[0336] In this embodiment, the patterned elements are coated in a coating 751 of the patterned elements. The coatings used in the optical modulator are typically transparent. The protective coating 751 prevents physical damage to the nano-elements.

[0337] The substrate 711 has at least one drive electrode applied to its first surface. One electrode has the reference numeral 721. The electrodes shown can all form part of a connected electrode. In a preferred electrophoretic optical modulator, at least two interdigitated electrodes are applied. The electrodes can be used to modulate the optical properties of the optical modulator.

[0338] In this embodiment, starting from the substrate, a coating having patterned elements is applied, followed by a pattern of drive electrodes. In this embodiment, no coating is applied to the electrodes. In this arrangement, the electrodes form a fluid contact with the optical layer. In this arrangement, the patterning of the nano-elements and the electrodes can be determined independently of the positions of the nano-elements and the electrodes relative to each other.

[0339] Figure 7b An embodiment of an embodiment of a transparent substrate for an optical modulator is schematically shown. The substrate is similar to the Figure 7a substrate, except that in this embodiment, a coating 752 for the drive electrodes is applied. In this arrangement, the electrodes do not form a direct fluid contact with the optical layer. Both coatings 751 and 752 are typically non-conductive and transparent.

[0340] The protective coating 752 prevents contaminants (such as particles, fibers, rocks, chunks, granules, etc.) present in the optical layer from coming into direct contact with the electrodes. These contaminants can be formed in various ways, such as by the aggregation of smaller particles, static electricity, entrapment between electrodes, etc. The contaminants can cause short circuits between electrodes on the opposing substrates, short circuits between adjacent electrodes on the same substrate, and can cause physical damage to the electrodes themselves, or any combination of the above. In one embodiment, the protective coating prevents physical damage to the electrodes and short circuits between the electrodes.

[0341] Figure 7c An example of an embodiment of a transparent substrate for an optical modulator is schematically shown. The substrate is similar to Figure 7a the substrate, except that in this example, both the nano-elements and the electrodes are applied to the same layer of the substrate. This arrangement is thinner compared to, for example, Figure 7b . Now the position of the nano-elements is selected depending on the electrodes. For example, no nano-elements can be placed at the positions where the electrodes are placed. The combined coating 753 for driving the electrodes and the patterning elements is applied to the nano-elements and the electrodes.

[0342] Figure 7d An example of an embodiment of a transparent substrate for an optical modulator is schematically shown. In this example, the nano-elements and the electrodes are applied on opposite surfaces of the substrate 711. The nano-elements are applied on the second surface of the substrate 711, away from the optical layer. The electrodes are applied on the first surface of the substrate 711, facing the optical layer.

[0343] In this example, the coating 751 for patterning the elements is applied, rather than the coating on the electrodes.

[0344] Figure 7e An example of an embodiment of a transparent substrate for an optical modulator is schematically shown. This substrate is similar to Figure 7d , except that the coating 752 for driving the electrodes is also applied to the first surface.

[0345] Figure 7f An example of an embodiment of a transparent substrate for an optical modulator is schematically shown. In this example, the patterning elements are applied on both surfaces of the substrate. Figure 7f Shown in sequence are the first layer of nano-elements, the substrate 711, the second layer of nano-elements in the coating 751, and the driving electrodes in the coating 752. In one embodiment, the coating 751 is also applied on the second surface of the substrate.

[0346] Figure 7gAn embodiment of a transparent substrate for an optical modulator is schematically shown. Figure 7g Similar to Figure 7f except that no coating is applied to the electrodes. A coating 751 may additionally be applied on the second surface, for example to protect the nano-elements.

[0347] In some embodiments, the protective coatings (e.g., coatings 751, 752, and / or 753) provide additional optical effects for the device. In some embodiments, this is an independent optical effect. In some embodiments, this is an optical effect in cooperation with the electro-optical effect of the device. For all optical wavelengths, or for a portion of the electromagnetic spectrum (such as, UV, visible light, and / or IR), these can be, for example, reflection, anti-reflection, diffuse reflection, and / or anti-diffraction effects. The protective coating material can be selected to have a refractive index that differs sufficiently from the refractive index of the fluid solvent to generate significant light refraction. For example, a protective coating made of silicon nitride with an optical refractive index of 3 can be combined with a fluid solvent with an optical refractive index below 2. The refractive index difference will induce refraction of the incident light, and the change in the light direction follows Snell's law. Thus, the optical modulator can direct the incident light to a specific designed direction. This effect can be combined with the specific shape and topology of the patterned protective coating to refract the light in multiple directions, thereby enhancing light scattering or light fog. Similarly, different protective coatings from the same substrate or from different substrates can enhance specific optical paths or light scattering.

[0348] For more information on coatings, reference is made to PCT / EP2022 / 066713 of the same applicant, for example, coatings for protecting electrodes, although similar coatings can be applied to the nano-elements.

[0349] Depending on the material or combination of materials selected, the protective coating can be applied using a variety of techniques known in the art, such as sputtering, molecular beam epitaxy, pulsed laser deposition, electron beam evaporation, chemical vapor deposition, atomic layer deposition, spin coating, flexographic printing coating, dip coating, spray coating, inkjet printing, slot coating, and combinations thereof.

[0350] Figure 8a An embodiment of a method 810 for manufacturing a substrate in an embodiment is schematically shown. Method 810 includes:

[0351] - Providing 811 the substrate,

[0352] - Applying 812 the drive electrodes to the first surface of the substrate, arranging the substrate for the optical modulator,

[0353] - Apply the patterned element 813 to the surface of the substrate, and arrange the substrate with the metasurface; the surface to which the patterned element is applied can be the first surface of the substrate or the second surface of the substrate opposite to the first surface. Application 812 and application 813 can be carried out simultaneously. Application 813 of the patterned element can be carried out before application 812.

[0354] Figure 8b An embodiment of a method 820 for manufacturing an optical modulator in one embodiment is schematically shown. The method 820 includes:

[0355] - Provide 821 a first substrate and a second substrate according to one embodiment (e.g., according to method 810). The second substrate may or may not have electrodes and / or patterned elements applied thereto.

[0356] - Apply 822 an optical layer between the first substrate and the second substrate,

[0357] - Seal the sides of the first substrate and the second substrate.

[0358] Figure 8c An embodiment of a method 830 for operating an optical modulator in one embodiment is schematically shown. The method 830 includes:

[0359] - Apply 831 an electric potential to the driving electrode to modulate the electromagnetic field in the optical layer, provide electrophoresis and / or dielectrophoresis of the particles in the optical layer, and modulate the light passing through the substrate,

[0360] - Change 832 the phase, amplitude, and / or polarization of the light passing through the substrate by means of the patterned element applied to the substrate surface.

[0361] The patterned element optionally includes a phase change material having an optical distortion depending on external factors such as temperature, pressure, and / or electric field. The method 830 may optionally further include modulating the external factors to modulate the optical distortion.

[0362] The following numbered list of clauses are some embodiments and have been separately contemplated. They are embodiments of the implementation.

[0363] Substrate

[0364] Clause 1. A transparent substrate for an optical modulator, the substrate comprising:

[0365] - At least one driving electrode (111 - 114, 121 - 124) applied to the first surface of the substrate, the driving electrodes being arranged in a pattern across the substrate, the electrodes being arranged to receive an electric potential, thereby causing modulation of the optical properties of the light modulator, wherein micro - patterned elements and / or nano - patterned elements are applied to the surface of the substrate, thereby changing the phase, amplitude, and / or polarization of light interacting with the substrate.

[0366] Clause 2. The substrate according to clause 1, wherein:

[0367] - The patterned element has a maximum diameter in a two - dimensional cross - section parallel to the substrate of the nano - element, the diameter being at most 2 microns, at most 1 micron, or at most 500 nanometers, and / or

[0368] - The minimum distance between two patterned elements is at most 2 microns, at most 1 micron, or at most 500 nanometers, and / or

[0369] - The minimum distance between two patterned elements is at least 100 nanometers, 200 nanometers, or 400 nanometers.

[0370] Clause 3. The substrate according to clause 1 or 2, wherein the patterned elements form a metasurface.

[0371] Clause 3.1. The substrate according to any one of the preceding clauses, wherein the patterned elements on the substrate have a plurality of different sizes, different shapes, and / or different materials.

[0372] Clause 4. The substrate according to any one of the preceding clauses, wherein the patterned elements extend from the surface and have a height of less than 1000 nanometers, preferably having a height between 100 nanometers and 1000 nanometers.

[0373] Clause 5. The substrate according to any one of the preceding clauses, wherein the patterned elements are applied to the first surface and / or wherein the patterned elements are applied to the second surface opposite the first surface.

[0374] Clause 6. The substrate according to any one of the preceding clauses, wherein the patterned elements are configured to compensate for optical artifacts of the light modulator.

[0375] Clause 7. The substrate according to clause 6, wherein the optical artifact is any one of the following: diffraction, refraction, light scattering, perturbation when light passes through the substrate, or light reflects from the substrate.

[0376] Clause 8. The substrate according to any one of the preceding clauses, wherein the patterned elements are configured to create a diffraction effect opposite to the diffraction effect created by the driving electrodes of the modulator.

[0377] Clause 9. A substrate as described in any of the preceding clauses, wherein the patterned element provides optical wavelength control to filter light passing through the substrate according to the wavelength.

[0378] Clause 10. A substrate as described in any of the preceding clauses, wherein the patterned element changes the wavefront of light passing through the substrate to generate a holographic image.

[0379] Clause 11. A substrate as described in any of the preceding clauses, wherein the patterned element changes the wavefront of light reflected through the substrate and compensates for the optical aberration generated by the drive electrode.

[0380] Clause 12. A substrate as described in any of the preceding clauses, wherein the patterned element provides optical polarization control to manipulate linear polarization or circular polarization.

[0381] Clause 12.1 A substrate as described in any of the preceding clauses, wherein the patterned element is passive (e.g., cannot be controlled by external factors) or active (e.g., can be controlled by external factors).

[0382] Clause 13. A substrate as described in any of the preceding clauses, wherein the patterned element includes elements with controllable shapes arranged to provide control over changing the phase, amplitude, and / or polarization of light interacting with the substrate.

[0383] Clause 14. A substrate as described in any of the preceding clauses, wherein the light modulator is arranged to be used within a defined spectral range, and the patterned element has a total transmittance of at most 10% within the spectral range.

[0384] Clause 15. A substrate as described in any of the preceding clauses, wherein the patterned element includes a phase change material having optical distortion depending on external factors such as temperature, pressure, and / or electric field.

[0385] Clause 16. A substrate for a light modulator, a substrate as described in any of Clauses 1 - 15, wherein the pattern of the drive electrode across the substrate includes a plurality of repeating building blocks.

[0386] Clause 15. A substrate as described in any of the preceding clauses, wherein:

[0387] - The building blocks repeat across the substrate in at least two directions, and / or

[0388] - A plurality of different building blocks repeat across the substrate in one or two directions.

[0389] Clause 16. A substrate as described in any of the preceding clauses, wherein at least one drive bus for each drive electrode of at least one drive electrode is arranged on the substrate to drive the drive electrode, wherein:

[0390] - At least one driving bus for each driving electrode is arranged at one side of the substrate to drive the driving electrode, and / or

[0391] - The driving bus is arranged only at one side of the substrate, and / or

[0392] - The driving bus is arranged between building blocks covering the substrate.

[0393] Clause 17. The substrate as described in any one of the foregoing clauses, wherein the substrate is non-rectangular.

[0394] Clause 18. The substrate for an optical modulator as described in any one of the foregoing clauses, wherein at least one driving electrode comprises a plurality of driving electrodes,

[0395] - The plurality of driving electrodes (111 - 114, 121 - 124) are interdigital, each of the plurality of driving electrodes is arranged in a pattern across the substrate, and the plurality of interdigital driving electrodes are arranged alternately with respect to each other on the substrate, and the pattern of the plurality of driving electrodes across the substrate comprises a plurality of repeating building blocks.

[0396] Clause 19. The substrate for an optical modulator as described in Clause 18, wherein the building block comprises:

[0397] - A plurality of interdigital electrodes extend across the building block in at least two directions, and the interdigital electrodes in the building block form a driving electrode. For at least one electrode among the plurality of interdigital electrodes in the building block, the maximum length between any two points on the electrode measured along the electrode in the building block is at least 2 times the diagonal length of the building block unit.

[0398] Clause 20. The substrate for an optical modulator as described in any one of the foregoing clauses, wherein the at least one driving electrode comprises a plurality of driving electrodes, wherein:

[0399] - The shortest distance from any point in the substrate to the first driving electrode and the second driving electrode is lower than a threshold value, and / or

[0400] - The sum of the shortest distances from any point in the substrate to the first driving electrode and the second driving electrode is lower than a first threshold value, and / or higher than a second threshold value, and / or

[0401] - The distance from a point on the first driving electrode to a point on the second driving electrode is at least a second threshold value, and / or

[0402] - The horizontal dimension and / or the vertical dimension of the building block is at least 10 times the sum of the electrode line width and the electrode distance.

[0403] Optical modulator

[0404] Clause 21. An optical modulator includes a first substrate and a second substrate as described in any one of Clauses 1-20, and an optical layer extending between the first substrate and the second substrate. The optical properties of the optical modulator can be modified by applying an electric potential to at least a driving electrode.

[0405] Clause 22. An optical modulator includes:

[0406] - A first substrate and a second substrate, at least one of the first substrate and the second substrate being provided with a patterned element, such as a patterned element according to one embodiment, such as a patterned element according to Clauses 1-20. At least one of the first substrate and the second substrate is arranged such that the inner sides thereof face each other. The first substrate is transparent, and at least one driving electrode is applied to the inner side of the first substrate. The driving electrode extends in a pattern across the inner side of the first substrate.

[0407] - An optical layer located between the first substrate and the second substrate, the optical layer including a fluid, and the fluid including particles.

[0408] - A controller configured to apply an electric potential to at least one driving electrode to obtain an electromagnetic field, thereby providing movement of the particles towards the driving electrode or providing movement of the particles away from the driving electrode, and further causing modulation of the optical properties of the optical modulator.

[0409] Clause 23. The optical modulator according to any one of the preceding clauses, wherein at least one driving electrode includes an ITO electrode.

[0410] Clause 24. The optical modulator according to any one of the preceding clauses, wherein the particles are charged or can be charged, and the controller is configured to apply an electric potential to the driving electrode to obtain an electromagnetic field, thereby providing electrophoretic movement of the particles towards the driving electrode or providing electrophoretic movement of the particles away from the driving electrode, and further causing modulation of the optical properties of the optical modulator.

[0411] Clause 24.1. The optical modulator according to any one of Clauses 21-24, wherein a plurality of interdigital driving electrodes are arranged across each of the inner sides of the first substrate and the second substrate, and the controller is configured to apply an electrical signal to the plurality of electrodes to obtain an electric field between the plurality of electrodes, thereby providing electrophoretic movement of the particles, and further causing modulation of the optical properties of the optical modulator.

[0412] Clause 24.2. The optical modulator according to any one of Clauses 21-24.1, the optical modulator being configured to:

[0413] - Switch to the non-transparent state by creating an alternating voltage on at least one of the first substrate and the second substrate, applying an alternating current between at least a first electrode and a second electrode on the first substrate, and / or applying an alternating current between a first electrode and a second electrode on the second substrate;

[0414] - Switch to the transparent state by creating an alternating voltage between the first substrate and the second substrate, applying an alternating current between a first electrode on the first substrate and a first electrode on the second substrate, and / or applying an alternating current between a second electrode on the first substrate and a second electrode on the second substrate.

[0415] Clause 24.3. The optical modulator as described in Clauses 21 - 24.2, wherein the electrical signal is an AC electrical signal.

[0416] Clause 24.4. The optical modulator according to any one of the preceding clauses, wherein the particles are charged or capable of being charged, and wherein the particles are moved due to the electrophoretic force.

[0417] Clause 25. The optical modulator according to any one of the preceding clauses, wherein the particles are charged or capable of being charged, and wherein the particles are moved due to the electrophoretic force.

[0418] Clause 26. The optical modulator according to any one of the preceding clauses, wherein the driving electrode is a wire electrode, for example, wherein the wire electrode extends along the longitudinal direction and along the transverse direction, and wherein at least at a partial portion of the wire electrode, the extension in the longitudinal direction is at least 10 times, more preferably at least 100 times, the extension in the transverse direction.

[0419] Clause 27. The optical modulator according to any one of the preceding clauses has:

[0420] - A transparent state and a non-transparent state, and / or

[0421] - A reflective state and a non-reflective state,

[0422] The optical modulator is configured to switch between states by modulating the current applied between one or more driving electrodes on the first substrate and optionally one or more driving electrodes on the second substrate.

[0423] Clause 28. The optical modulator according to any one of the preceding clauses, wherein:

[0424] - Provide an electrical signal as an alternating current (AC) in one or more electrodes, or

[0425] - An electrical signal is provided as a direct current (DC) in one or more electrodes, where the voltage is periodically reversed.

[0426] Clause 29. The optical modulator as described in any one of the preceding clauses, wherein the first substrate and the second substrate are transparent.

[0427] Clause 30. The optical modulator as described in any one of the preceding clauses, wherein one of the first substrate and the second substrate is transparent, and one of the first substrate and the second substrate is reflective or partially reflective.

[0428] Clause 31. The optical modulator as described in any one of the preceding clauses, wherein one or more electrodes comprise a plurality of interleaved mesh electrodes,

[0429] - The plurality of interleaved mesh electrodes extend in a two-dimensional pattern across the first substrate and across the second substrate, and two of the mesh electrodes among the plurality of mesh electrodes on the substrate cross at a plurality of crossing points distributed across the substrate.

[0430] Clause 32. The optical modulator as described in any one of the preceding clauses, wherein:

[0431] - The particles are nanoparticles and / or microparticles, and / or

[0432] - The particles are adapted to absorb light,

[0433] - The particles are pigment particles.

[0434] Clause 33. The optical modulator as described in any one of the preceding clauses, wherein at least two electrodes comprise a conductive material having a resistivity less than 100 nΩm at 273K.

[0435] Clause 34. The optical modulator as described in any one of the preceding clauses, wherein the electrodes are in fluid contact with the fluid, or wherein the electrodes are separated from the fluid, for example by a coating.

[0436] Clause 35. The optical modulator as described in any one of the preceding clauses, wherein the electrodes applied to the substrate cover 1% - 30% of the substrate surface.

[0437] Clause 36. The optical modulator as described in any one of the preceding clauses, wherein the electric potential operates at an AC frequency of 10 - 100 Hz for switching to the transparent state, and / or the electric potential operates at an AC frequency of less than 1 Hz for switching to the non-transparent state.

[0438] Clause 37. The optical modulator as described in any one of the preceding clauses, wherein the size of the nanoparticles is 10 - 1000 nm, preferably 100 - 500 nm.

[0439] Clause 38. A light modulator as described in any of the preceding clauses, wherein the particles are adapted to absorb light having a wavelength of 10 nanometers to 1 micrometer.

[0440] Clause 39. A light modulator as described in any of the preceding clauses, wherein the distance between the first substrate and the second substrate is less than 500 μm.

[0441] Clause 40. A light modulator as described in any of the preceding clauses, wherein the dynamic viscosity of the fluid is 500 mPa·s or less.

[0442] Clause 41. A light modulator as described in any of the preceding clauses, wherein the relative dielectric constant ε of the fluid r is less than 100.

[0443] Method

[0444] Clause 42. A method of modulating light, comprising:

[0445] - Applying an electric potential to one or more drive electrodes, the one or more drive electrodes being applied to one or two opposing substrates to obtain an electromagnetic field between the drive electrodes, thereby providing electrophoretic movement of the particles towards one of the plurality of drive electrodes or providing electrophoretic movement of the particles away from one of the plurality of drive electrodes, and thereby causing modulation of light irradiating through the substrate, wherein at least one or both of the two opposing substrates are substrates as described in any of the preceding clauses.

[0446] Clause 43. The method of modulating light according to Clause 42, comprising using an alternating current having two phases, wherein the electric potential is between -220 V and +220 V, and the current is between -100 μA and +100 μA.

[0447] Clause 44. A transient or non-transient computer-readable medium comprising data representing instructions that, when executed by a processor system, cause the processor system to perform the method according to Clause 42 or 43.

[0448] Figure 9aA computer-readable medium 1000 is shown having a writable portion 1010 that includes a computer program 1020, and a computer-readable medium 1001 having a writable portion. The computer program 1020 includes instructions for causing a processor system to run an optical modulator method according to one embodiment. For example, the processor system may be connected to an optical modulator. The computer program 1020 may be implemented on the computer-readable medium 1000 as a physical mark or by magnetization of the computer-readable medium 1000. However, any other suitable embodiment may also be contemplated. In addition, it will be understood that although the computer-readable medium 1000 is shown herein as an optical disk, the computer-readable medium 1000 may be any suitable computer-readable medium, such as a hard disk, solid-state memory, flash memory, etc., and may be non-recordable or recordable. The computer program 1020 includes instructions for causing the processor system to perform the optical modulator method.

[0449] Figure 9b A processor system 1140 for a controller of an optical modulator according to one embodiment is shown in a schematic representation. The processor system includes one or more integrated circuits 1110. Figure 9b The architecture of one or more of the integrated circuits 1110 is schematically shown in. The circuit 1110 includes a processing unit 1120 (e.g., a CPU) that is used to run computer program components to perform a method and / or implement its modules or units according to one embodiment. The circuit 1110 includes a memory 1122 that is used to store programming code, data, etc. A portion of the memory 1122 may be read-only. The circuit 1110 may include communication elements 1126, e.g., an antenna, a connector, or both, or the like. The circuit 1110 may include an application-specific integrated circuit 1124 that is used to perform some or all of the processing defined in the method. The processor 1120, the memory 1122, the application-specific IC 1124, and the communication element 1126 may be connected to each other via an interconnect 1130 (e.g., a bus). The processor system 1110 may be arranged for contact communication and / or non-contact communication, using an antenna and / or a connector, respectively.

[0450] For example, in one embodiment, the processor system 1140, such as a device, may include a processor circuit and a storage circuit, and the processor is arranged to execute software stored in the memory circuit. For example, the processor circuit may be an Intel Core i7 processor, an ARM Cortex-R8, etc. In one embodiment, the processor circuit may be an ARM Cortex M0. The memory circuit may be a ROM circuit, or a non-volatile memory such as a flash memory. The memory circuit may be a volatile memory such as an SRAM memory. In the latter case, the device may include a non-volatile software interface (e.g., a hard disk, a network interface, etc.), and the non-volatile software interface is arranged to provide software.

[0451] A controller for an optical modulator (e.g., controlling the voltage applied to an electrode) may include a processor circuit, but may also include or alternatively include a state machine.

[0452] It should be noted that the embodiments mentioned above illustrate rather than limit the subject matter of the present disclosure, and those skilled in the art will be able to design many alternative embodiments.

[0453] In a claim, any reference numeral placed in parentheses shall not be construed as limiting the claim. The use of the verb “comprise” and its variants does not exclude the presence of elements or steps other than those stated in the claim. The article “a” or “an” preceding an element does not exclude the presence of a plurality of such elements. When an expression such as “at least one” is placed before a list of elements, it means selecting all elements or any subset of elements from the list. For example, the expression “at least one of A, B, and C” should be understood to include only A, only B, only C, both A and B, both A and C, both B and C, or all of A, B, and C. The subject matter of the present disclosure may be implemented by hardware including several different elements, and by a properly programmed computer. In a device claim enumerating several parts, several of these parts may be implemented by the same hardware item. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0454] In a claim, the reference numerals in parentheses refer to the reference symbols in the figures of the exemplary embodiments or the formulas of the embodiments, thereby enhancing the understandability of the claim. These reference numerals shall not be construed as limiting the claim.

Claims

1. A transparent substrate for an optical modulator, the substrate comprising: - at least one drive electrode (111 - 114, 121 - 124), the at least one drive electrode being applied to a first surface of the substrate, the drive electrode being arranged in a pattern across the substrate, the electrode being arranged to receive an electric potential to cause modulation of an optical property of the optical modulator, wherein nano - patterned elements and / or micro - patterned elements are applied to the surface of the substrate to change the phase, amplitude, and / or polarization of light interacting with the substrate, and wherein the patterned elements are arranged to compensate for optical artifacts of the optical modulator caused by the drive electrode.

2. The substrate according to claim 1, wherein: - the patterned element has a maximum diameter in a two - dimensional cross - section parallel to the substrate, the diameter being at most 10 microns, at most 2 microns, at most 1 micron, or at most 500 nanometers, and / or - the minimum distance between two patterned elements is at most 2 microns, at most 1 micron, at most 500 nanometers, and / or - the minimum distance between two patterned elements is at least 10 nanometers, at least 50 nanometers, at least 100 nanometers, 200 nanometers, or 400 nanometers, - the patterned element has at least two non - continuous edges, and the minimum distance between two points on a corresponding one of the non - continuous edges is at most 2 microns, at most 1 micron, or at most 500 nanometers.

3. The substrate according to claim 1 or 2, wherein the patterned elements form a metasurface.

4. The substrate according to any one of the preceding claims, wherein the patterned element extends from the surface and has a maximum height in a direction perpendicular to the substrate, the height being at most 2 microns, at most 1 micron, or at most 500 nanometers, preferably the height being between 100 nanometers and 1000 nanometers.

5. The substrate according to any one of the preceding claims, wherein the patterned element is applied to the first surface, and / or wherein the patterned element is applied to a second surface opposite the first surface.

6. The substrate according to any one of the preceding claims, wherein the optical artifact is any one of the following: diffraction, refraction, light scattering, perturbation when light passes through or reflects from the substrate.

7. The substrate according to any one of the preceding claims, wherein the patterned element is configured to create a diffraction effect opposite to the diffraction effect created by the drive electrode of the modulator.

8. The substrate according to any one of the preceding claims, wherein the patterned element provides light wavelength control to filter light passing through the substrate according to wavelength.

9. The substrate according to any one of the preceding claims, wherein the patterned element changes the wavefront of light passing through the substrate to generate a holographic image.

10. The substrate according to any one of the preceding claims, wherein the patterned element changes the wavefront of light reflected through the substrate and compensates for optical aberrations generated by the drive electrode.

11. The substrate according to any one of the preceding claims, wherein the patterned element provides optical polarization control to manipulate linear polarization or circular polarization.

12. The substrate according to any one of the preceding claims, wherein the patterned element comprises an element with a controllable shape, and the element with the controllable shape is arranged to provide control over changing the phase, amplitude, and / or polarization of light interacting with the substrate.

13. The substrate according to any one of the preceding claims, wherein the light modulator is arranged to be used within a defined spectral range, and the patterned element has a total transmittance of at most 10% within the spectral range.

14. The substrate according to any one of the preceding claims, wherein the patterned element comprises a phase change material, and the phase change material has an optical distortion depending on external factors such as temperature, pressure, and / or electric field.

15. The substrate according to any one of the preceding claims, wherein the patterned element on the substrate comprises a transparent and conductive patterned element, and the patterned element is arranged to receive an electric potential to provide control over optical modulation in the light modulator.

16. The substrate according to claim 15, wherein the patterned element is configured to interact with particles in the optical layer of the light modulator.

17. The substrate according to any one of claims 15 - 16, wherein the patterned element is independently electrically addressable.

18. The substrate according to claim 17, wherein the patterned element is applied on the first surface in a regular grid, and the regular grid covers at least a part of the first surface.

19. A method of manufacturing a substrate according to any one of the preceding claims, comprising: - providing the substrate, - applying the driving electrode to the first surface of the substrate, - applying the patterned element to the surface of the substrate.

20. A light modulator, comprising: The first substrate according to any one of claims 1 - 18; and, a second substrate; An optical layer extending between the first substrate and the second substrate, and the optical properties of the light modulator can be modified by applying an electric potential to at least the driving electrode.

21. The light modulator according to claim 20, wherein the optical layer comprises charged particles, the patterned element on the first substrate comprises a transparent and conductive patterned element, and the light modulator is configured to apply an electric potential to the conductive patterned element to cause the charged particles to align with the conductive patterned element, thereby modulating the optical properties of the patterned element.

22. The light modulator according to any one of claims 20 and 21, wherein the patterned element is arranged to focus light irradiating on the first substrate inside the optical layer.

23. A method of calibrating a light modulator, the light modulator being the light modulator according to any one of claims 20 - 22, the method comprising: - providing the light modulator, - obtaining information about the distortion and / or transparency of the light modulator from an image sensor observing the light modulator, - Derive a control signal for controlling the optical modulator during the operation phase.

24. The method according to claim 23, further comprising: - Obtain information about the orientation of the optical modulator from an orientation sensor applied to the optical modulator.

25. A method for controlling an optical modulator, the optical modulator being the optical modulator according to any one of claims 20-22, the method comprising: Apply an electric potential to the drive electrode; Modulate the electromagnetic field in the optical layer; Provide electrophoresis and / or dielectrophoresis of the particles in the optical layer; modulate the light passing through the substrate, wherein the phase, amplitude, and / or polarization of the light passing through the substrate are also changed by a patterned element applied to the surface of the substrate.

26. The method for controlling an optical modulator according to claim 25, wherein the patterned element comprises a phase change material having an optical distortion depending on external factors such as temperature, pressure, and / or an electric field, and / or wherein the patterned element is conductive and has an optical distortion depending on external factors including an electric potential, the method comprising modulating the external factors to modulate the optical distortion.

27. A transient or non-transient computer-readable medium (1000) comprising data (1020) representing instructions that, when executed by a processor system, cause the processor system to perform any one of the methods according to claims 23-26.

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