Optical Modulators and Substrates with Micro- and / or Nano-Patterned Elements for Optical Modulation

Abstract

Some embodiments are directed to a transparent substrate for use in a light modulator. The substrate has at least one drive electrode applied to a first surface of the substrate. The drive electrode may be arranged in a pattern across the substrate and may receive an electrical potential to cause modulation of an optical property of the light modulator. A patterning element is applied to the surface of the substrate to modify the phase, amplitude, and / or polarization of light interacting with the substrate.

Description

[Technical Field]

[0001] The subject matter disclosed herein relates to a substrate for use in an optical modulator, a method for manufacturing a substrate, an optical modulator, a method for calibrating an optical modulator, a method for controlling an optical modulator, and a computer-readable medium. [Background technology]

[0002] A known light modulator is disclosed in WO2022023180, which is incorporated herein by reference. The known light modulator comprises a transparent or reflective substrate. A plurality of electrodes are applied to the substrate in a pattern across the substrate. A controller may apply a potential to the electrodes to obtain an electromagnetic field between the electrodes and provide electrophoretic movement of particles toward or away from the electrodes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2022 / 023180 [Patent Document 2] U.S. Patent No. 5,161,048 Summary of the Invention [Means for solving the problem]

[0004] It would be advantageous to have an improved light modulator. In particular, it would be advantageous to have an improved transparent substrate for use in a light modulator. In embodiments of the substrate, micro- and / or nano-patterned elements are applied to a surface of the substrate. The patterned elements modify the phase, amplitude, and / or polarization of light that interacts with the substrate. Light that interacts with the substrate includes light that passes through the surface. Light that interacts with the substrate may also include light that is reflected from the substrate.

[0005] The patterning element has a shape, e.g., a 2D or 3D shape parallel to the substrate, and a distribution selected to produce the desired optical modulation. The patterning element can be manufactured by patterning, which may include a process of creating nanostructures across the surface of a material, in this case, the substrate. The patterning element, in one embodiment, may be transparent or non-transparent. Transparent patterning elements have the advantage of a smaller reduction in transmittance, but the optical effect of the element may be smaller, for example, if the element has a small refractive index.

[0006] In addition to the patterned elements, at least one drive electrode may also be applied to the first surface of the substrate, the drive electrode being arranged in a pattern across the substrate. The electrode is arranged to receive an electrical potential, resulting in modulation of the optical properties of the light modulator. In particular, the light modulator may have an optical layer adjacent to the substrate. Particles in the optical layer may be under control of the electrode, for example, under electrophoretic control.

[0007] For example, metasurfaces formed by patterned elements allow for the correction of optical artifacts introduced by the presence of driving electrodes on a substrate. In particular, diffraction and / or rainbowing may be reduced by adding nanoelements. For example, metasurfaces may comprise thin-film coatings that create electromagnetic optics. Typically, metasurface designs are selected or optimized specifically for an electrode design. Using the same metasurface for electrodes with different patterns may not work well.

[0008] For example, metasurfaces formed by patterned elements could potentially correct artifacts as well as introduce optical effects, including 3D rendering, holograms, and possibly lenses with different focal points.

[0009] Metasurfaces are layers of subwavelength-scale nanostructures that can be used to design thin, optically functional devices. Various metasurface-based optical devices, also called planar optical devices, have been realized with distinct performance characteristics.

[0010] The nano-elements may be applied to the same surface of the substrate or to opposing surfaces of the substrate.

[0011] The nano-elements may be configured to reduce the reflection of the substrate and therefore improve the dark state of the light modulator, eg, deepen the black level.

[0012] Aspects of the presently disclosed subject matter further include a method of manufacturing a substrate, an optical modulator, a method of calibrating an optical modulator, a method of controlling an optical modulator, and a computer-readable medium.

[0013] Further details, aspects, and embodiments will now be described, by way of example only, with reference to the drawings, in which elements are illustrated for simplicity and clarity and have not necessarily been drawn to scale. In the figures, elements corresponding to elements already described may have the same reference numerals. [Brief explanation of the drawings]

[0014] [Figure 1a] 1A and 1B are schematic diagrams illustrating examples of embodiments of building blocks; [Figure 1b] 1A-1C are diagrams illustrating examples of embodiments of a substrate. [Figure 1c] 1A-1C are diagrams illustrating examples of embodiments of a substrate. [Figure 1d] 1A-1C are diagrams illustrating examples of embodiments of a substrate. [Figure 1e] 1A-1C are diagrams illustrating examples of embodiments of a substrate. [Figure 1f] 1A-1C are diagrams illustrating examples of embodiments of a substrate. [Figure 2a] 1A-1C are diagrams illustrating examples of embodiments of a substrate. [Figure 2b] 1A-1C are diagrams illustrating examples of embodiments of a substrate. [Figure 2c] 1A-1C are diagrams illustrating examples of embodiments of a substrate. [Figure 2d] 1A-1C are diagrams illustrating examples of embodiments of a substrate. [Figure 2e] 1A-1C are diagrams illustrating examples of embodiments of a substrate. [Figure 2f] 1A-1C are diagrams illustrating examples of embodiments of a substrate. [Figure 3a] 1A and 1B are diagrams illustrating examples of embodiments of optical modulators. [Figure 3b] 1A and 1B are diagrams illustrating examples of embodiments of optical modulators. [Figure 3c] 1 is a diagram illustrating a schematic example of an embodiment of a vehicle; [Figure 4a] 1A and 1B are diagrams illustrating an embodiment of an optical modulator. [Figure 4b] 1A and 1B are diagrams illustrating an embodiment of an optical modulator. [Figure 4c] 1A and 1B are diagrams illustrating an embodiment of an optical modulator. [Figure 5a] FIG. 1 is a diagram illustrating an example of an embodiment of an optical modulator. [Figure 5b] FIG. 1 is a diagram illustrating an example of an embodiment of an optical modulator. [Figure 5c] FIG. 1 is a diagram illustrating an example of an embodiment of an optical modulator. [Figure 6a] 1A and 1B are schematic diagrams illustrating an example embodiment of a transparent substrate for use in a light modulator. [Figure 6b] 1A and 1B are schematic diagrams illustrating an example embodiment of a transparent substrate for use in a light modulator. [Figure 6c.1] 1A and 1B are schematic diagrams illustrating an example embodiment of a transparent substrate for use in a light modulator. [Figure 6c.2] 1A and 1B are schematic diagrams illustrating an example embodiment of a transparent substrate for use in a light modulator. [Figure 6d.1] FIG. 10 is a schematic diagram of an example of a light modulator without a patterning element. [Figure 6d.2] 1A and 1B are schematic diagrams illustrating an example embodiment of a light modulator having patterned elements. [Figure 6e.1] 1A and 1B are schematic diagrams illustrating examples of light modulators having conductive patterned elements in an inactive state. [Figure 6e.2] 1A-1C are schematic diagrams illustrating examples of light modulators with conductive patterned elements in active states. [Figure 7a] 1A and 1B are schematic diagrams illustrating an example embodiment of a transparent substrate for use in a light modulator. [Figure 7b] 1A and 1B are schematic diagrams illustrating an example embodiment of a transparent substrate for use in a light modulator. [Figure 7c] 1A and 1B are schematic diagrams illustrating an example embodiment of a transparent substrate for use in a light modulator. [Figure 7d] 1A and 1B are schematic diagrams illustrating an example embodiment of a transparent substrate for use in a light modulator. [Figure 7e] 1A and 1B are schematic diagrams illustrating an example embodiment of a transparent substrate for use in a light modulator. [Figure 7f] 1A and 1B are schematic diagrams illustrating an example embodiment of a transparent substrate for use in a light modulator. [Figure 7g] 1A and 1B are schematic diagrams illustrating an example embodiment of a transparent substrate for use in a light modulator. [Figure 8a] 1A and 1B are schematic diagrams illustrating an example embodiment of a method for manufacturing a substrate, similar to that of an embodiment; [Figure 8b] 1A and 1B are schematic diagrams illustrating an example embodiment of a method for fabricating an optical modulator, similar to that of an embodiment; [Figure 8c] 1A and 1B are schematic diagrams illustrating an example embodiment of a method of operating an optical modulator, similar to that of an embodiment; [Figure 9a] 1 is a diagram illustrating a computer-readable medium having a writable portion containing a computer program according to an embodiment; [Figure 9b] FIG. 1 is a diagram that schematically illustrates a representation of a processor system according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] While the subject matter of the present disclosure is susceptible to embodiment in many different forms, one or more specific embodiments have been shown in the drawings and will be described in detail herein, with the understanding that the disclosure is to be considered as an exemplification of the principles of the subject matter of the present disclosure and is not intended to limit the disclosure to the specific embodiments shown and described.

[0016] In the following, for the sake of understanding, the elements of the embodiments are described in an operational state. However, it will be clear that each element is configured to perform the function described as being performed by the respective element. Furthermore, the subject matter of the present disclosure is not limited to the embodiments only, but also includes all other combinations of features described herein or recited in different dependent claims.

[0017] For example, a substrate for use in a light modulator, particularly in dynamic glazing, is disclosed. The substrate is transparent, and at least one drive electrode is applied to a surface of the substrate, the drive electrode extending in a pattern across the surface of the first substrate. Interestingly, when used in a light modulator, it is advantageous to have patterning elements applied to the surface of the substrate to modify, e.g., correct, light interacting with the substrate. The patterning elements are arranged in a pattern on the substrate. The pattern may be repeating, but this is not necessary. The pattern is created in accordance with the desired modulation of light provided by the patterning elements. For example, multiple patterning elements on a substrate can together form a metasurface.

[0018] There are many types of light modulators that use such substrates. Some known light modulators are based on electrophoretic principles. 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 arranged in a pattern across the substrate, and the plurality of interdigitated drive electrodes are alternately arranged relative to each other on the substrate. Having multiple interdigitated electrodes allows for local control over the electric field, enabling electrophoretic control of the particles.

[0019] Electrophoretic light modulators are described more broadly herein and are used as a motivational example. In one embodiment, the light modulator includes a first substrate and a second substrate. At least one of the first substrate and the second substrate may have patterned elements according to an embodiment. For example, the first and second substrates may be arranged with their inner surfaces facing each other. Using substrates according to an embodiment has the effect of reducing optical interference, for example. An optical layer is disposed between the first substrate and the second substrate. Drive electrodes are disposed to modulate an electric field within the optical layer. The optical layer includes a fluid containing particles, and the particles are charged or chargeable. The particles may move under the control of the electric field. For example, the controller may be configured to apply a potential to the drive electrodes to obtain an electromagnetic field at the drive electrodes, providing electrophoretic movement of the particles toward or away from one of the at least one drive electrodes, resulting in modulation of the optical properties of the light modulator.

[0020] In the following, several known light modulators are reviewed, illustrating some of the options in technology and electrodes. These known substrates can be advantageously modified by applying patterning elements. These examples also illustrate light modulators with different numbers of electrodes on the substrate.

[0021] International Patent Application WO2011012499(A1) (incorporated herein by reference) and International Patent Application WO2011131689 (incorporated herein by reference) disclose light modulators in the form of electrophoretic display devices, e.g., e-ink displays. A pixel of the display comprises a storage electrode and a field electrode, the storage electrode being disposed in a storage area away from an aperture area for storing charged particles, the field electrode occupying a field electrode area that is at least a portion of the aperture area of ​​the pixel, and the charged particles being 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 its surface to modify, e.g., correct, light interacting with the substrate.

[0022] U.S. Pat. No. 10,921,678, entitled "Electrophoretic device," which is 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 U.S. Pat. No. 10,921,678 may be replaced with a substrate according to one embodiment having one single electrode. For example, one embodiment includes a first transparent substrate having a field electrode and a second substrate facing the first substrate having a storage electrode. The first and second substrates enclose a pixel with fluid and particles. In use, an applied electromagnetic field to the field and storage electrodes provides movement of particles from the field and storage electrodes, and vice versa. The substrate may have patterned elements applied to its surface to modify, e.g., correct, light interacting with the substrate.

[0023] U.S. Pat. No. 8,054,535 (B2) (incorporated herein by reference) and U.S. Pat. No. 8,384,658 (B2) (incorporated herein by reference) show alternative examples of electrophoretic light modulators in which one of the two substrates has two patterned electrodes.

[0024] Patterned electrodes are also used in dielectrophoretic light modulators. For example, U.S. Patent Application No. 2005185104(A1), incorporated herein by reference, and U.S. Patent Application No. 20180239211(A1), incorporated herein by reference, show dielectrophoretic light modulators having substrates with patterned electrodes. Any of these cited electrophoretic or dielectrophoretic light modulators may be configured with patterned elements applied to the surface of the substrate to modify, e.g., correct, light interacting with the substrate.

[0025] The article "Reversible Metal Electrodeposition Devices: An Emerging Approach to Effective Light Modulation and Thermal Management," which is incorporated by reference, also shows substrates onto which patterned electrodes are applied, which may be advantageously arranged according to embodiments.

[0026] Embodiments of the substrate may be used in electrochromic devices (ECDs), which control optical properties such as optical transmission, absorption, reflection, and / or emittance in a continuous yet reversible manner by the application of voltage (electrochromism). This property allows electrochromic devices to be used for applications such as smart glass, electrochromic mirrors, and electrochromic display devices.

[0027] Electrochromic devices are described, for example, in the article "Silver grid electrodes for faster switching ITO-free electrochromic devices" by Antonio California et al., which is incorporated herein by reference, and which describes the preparation of electrochromic devices, in this case, electrochromic devices that are free of ITO.

[0028] Electrochromic devices use electrically conductive electrodes applied to a substrate. The cited paper uses a silver grid created using silver ink as the electrically conductive electrode. Electrochromic devices may include an electrochromic material. The cited paper uses poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). In electrochromic devices, at least one driving electrode, e.g., an electrically conductive electrode, is applied to a substrate. The driving electrodes are arranged in a pattern across the substrate. The cited paper discloses two different grid patterns: a regular hive and a regular ladder design. See Table 1 and Figure 3 of the cited paper.

[0029] In the cited paper, electrodes can be applied to a substrate by screen-printing polyethylene terephthalate (PET) onto the substrate. Electrodes are typically electrically conductive materials, such as metals or metal oxides. In the cited paper, silver ink was used to screen-print grids onto PET using a RokuPrint RP 2.2 instrument and a 180-wire mesh. The samples were allowed to dry in an oven at 130°C for 15 minutes. One or two layers of PEDOT:PSS SV3 were subsequently printed on top of these silver grids by screen printing. Patterned elements can be applied to the surface of the substrate to modify light interacting with the substrate, for example, to form a metasurface.

[0030] Another example of an electrochromic device is given in U.S. Pat. No. 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 may include a transparent electrochromic film and an ion-conductive layer disposed between a pair of electrodes. A metal grid electrode is provided for the electrode. Figure 1 of the patent shows a metal grid according to the cited patent. To form a counter electrode, the metal grid is disposed adjacent to a second glass substrate.

[0031] For example, in embodiments of an electrochromic device, the electrochromic device may comprise a transparent substrate, an electrically conductive electrode member, a transparent electrochromic film in contact with the electrically conductive electrode member, an ion-conducting polymer in contact with the electrochromic film, and a patterned conductive electrode in contact with the ion-conducting polymer. The patterned conductive electrode may be in accordance with embodiments.

[0032] Substrates according to embodiments may be advantageously applied in several other technologies. For example, the light modulator may be a dielectrophoretic light modulator, as shown in, for example, U.S. Patent Application Publication No. 20050185104(A1), which is incorporated herein by reference. Substrates such as those according to embodiments may also be used in other electrowetting and OLED applications.

[0033] In OLEDs and electrowetting, electrodes are required on only one of the substrates. The substrate having the electrodes may depend on the embodiment.

[0034] In light modulator applications for glazing, both substrates are typically transparent. In other applications, such as televisions, e-readers, etc., only one substrate may be transparent.

[0035] In one embodiment, the substrate has patterning elements applied to a surface of the substrate to modify, eg, correct, light interacting with the substrate.

[0036] In Figures 1a-4c, the nano-elements are not visible in the figures.

[0037] Figure lb shows a schematic illustration of one example embodiment of a substrate. The substrate is particularly useful, for example, for use in a light modulator of the type described herein. A plurality of interdigitated drive electrodes are applied to the substrate across it. Two electrodes are shown in Figure lb.

[0038] An example of the use of the substrate is in an electrophoretic light modulator. Typically, an electrophoretic light modulator comprises at least two substrates, each having at least two drive electrodes. Although this is not required, for example, an electrophoretic light modulator may comprise a single substrate having two electrodes and an opposing substrate having one electrode. In either case, preferably, at least one of the substrates in the light modulator is a substrate according to the embodiment.

[0039] An embodiment of the light modulator includes a first substrate and a second substrate according to the embodiment. The first and second substrates are arranged with their inner surfaces facing each other. At least one drive electrode is applied to the inner surface of the first substrate. An optical layer is disposed between the first and second substrates. A controller is configured to apply an electric potential to the at least one drive electrode, which causes modulation of the optical properties of the light modulator. One or both of the first and second substrates are transparent and / or semi-transparent.

[0040] There are many different types of optical modulators that use at least one drive electrode applied to a substrate. Because light is transmitted through the substrate, interference is a common problem in the field of optical modulators. The optical layer and controller may be configured to modulate optical properties using effects that depend on the potential on the drive electrodes; examples include dielectrophoretic and electrophoretic effects. For example, an optical modulator may include modulation of particles disposed within the optical layer. The number of drive electrodes may range from one on a single substrate to multiple drive electrodes on one or both substrates.

[0041] The optical layer disposed between the first and second substrates may include, for example, particles suspended in a fluid, and the controller may be configured to apply an electric potential to the drive electrodes to move the particles and thus modulate the optical properties of the light modulator.

[0042] In embodiments, the particles include charged or chargeable particles, and the controller is configured to apply a potential to the drive electrodes to obtain an electromagnetic field that provides electrophoretic movement of the particles. In embodiments, the electromagnetic field is disposed between at least two drive electrodes disposed on the same substrate or disposed on different substrates.

[0043] In an embodiment, the particles comprise dielectric particles, and the controller is configured to apply a potential to the drive electrodes to apply an electric field gradient to the particles, allowing the particles to move under the action of dielectrophoretic forces.

[0044] The controller may apply an electrical signal to one or more of the drive electrodes. Embodiments that control the dielectrophoretic force may use signals that include DC and / or AC signals. Embodiments that control the electrophoretic force may use signals that include DC and / or AC signals.

[0045] FIG. 1b shows two drive electrodes on the same surface. The two drive electrodes are shown with two different dashed line styles in FIG. 1b. For example, there may be three or more electrodes on the same side of the substrate to facilitate finer 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 may be done by lithography, for example, using a mask that represents the electrode pattern. The electrodes may also be applied by embedding the electrodes into the substrate.

[0046] The drive electrodes are electrically connected, e.g., have the same potential everywhere. The drive electrodes may comprise drive buses and main lines. At least the main lines are interdigitated with main lines of further drive electrodes. Typically, the drive electrodes extend in substantially straight lines across the substrate, while the main lines are convoluted.

[0047] In an embodiment, each of the two substrates of the optical modulator has two electrodes disposed on its inner surface. However, as noted, multiple electrodes on one or both substrates are not required. For example, an embodiment of the optical modulator includes a first substrate and a second substrate. For example, the first substrate may include one drive electrode and the second substrate may include no drive electrodes. For example, the first substrate may include two drive electrodes and the second substrate may include one drive electrode. For example, the first substrate may include two drive electrodes and the second substrate may include two drive electrodes. For example, the first substrate may include three or more drive electrodes and the second substrate may include two or more drive electrodes.

[0048] However, an optical modulator in which each substrate includes two drive electrodes is used as a motivational example. A substrate design featuring two drive electrodes may be configured to have a single drive electrode, for example, by connecting the two drive electrodes or by removing one of the drive electrodes. Configuring the substrate in this manner may make the substrate suitable for use in different technologies.

[0049] Each of the multiple drive electrodes is arranged in a pattern across the substrate. The multiple drive electrodes are arranged alternately with respect to one another on the substrate. Typically, a drive electrode comprises 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 FIG. 1b, a first drive electrode comprises main lines 111-114, and a second drive electrode comprises main lines 121-124. Each drive electrode is driven by its own drive bus. FIG. 1b shows two drive buses: drive bus 110 and drive bus 120. The drive electrodes also serve to connect the main lines together. For example, in FIG. 1b, drive bus 110 drives and connects main lines 111-114, and drive bus 120 drives and connects main lines 121-124. There can be more main lines than the four shown in this example. The use of main lines is advantageous because it reduces the length of the electrodes, but it is not necessary. Although designs using only one main line per drive electrode are possible, it is advantageous to have multiple main lines.

[0050] The plurality of main lines of the first and second electrodes are alternately arranged with respect to each other on the substrate.

[0051] An inspiring application for substrates such as substrate 100 is in smart glazing, e.g., light modulators, which may be applied in domestic homes, offices, greenhouses, cars, and the like. The transparency or reflectivity level of smart glazing can be electrically adjusted. For example, in smart glazing, two substrates, such as substrate 100, are stacked with the surfaces on which two electrodes are applied facing each other. A fluid with particles is enclosed between the two substrates. Smart glazing embodiments are discussed further below. In embodiments, an electrode, e.g., two or more electrodes, is applied to one surface of each substrate. For example, to facilitate stacking of three or more substrates, one, two, or more electrodes may be present on the other surface of substrate 100.

[0052] Some embodiments below show examples of modulating transparency or reflectivity levels. Light modulators may be configured for other optical effects. For example, if desired, embodiments could be modified for different levels of translucency instead of different levels of transparency. If desired, the types of particles used in embodiments could be varied, e.g., for particles that differ in which wavelengths the particles absorb or reflect, and how specular or diffuse the reflection is. For example, in embodiments, light modulators can modulate different levels of reflection. Particles can also emit light. Stacking multiple optical layers further increases the possibilities.

[0053] Having two sets of alternating main lines is sufficient to provide an electrically configurable glazing, and the two alternating sets allow the electric field in any part of the substrate to be controlled, since two opposing electrodes bound that part from two opposing faces.

[0054] Interestingly, the pattern in which the drive electrodes extend across the substrate is made by a plurality of repeating building blocks. As shown in FIG. 1b, the drive electrodes on substrate 100 exhibit four blocks: blocks 141, 142, 143, and 144, all of which are substantially identical. The number of building blocks may be greater than four. The building blocks repeat across the substrate in both directions, for example, in a first direction 191, e.g., the x-direction shown horizontally in the figure, and in a second direction 192, e.g., the y-direction shown vertically in the figure. The use of building blocks is advantageous because it allows for fabrication using a stepper machine. The use of building blocks is not required.

[0055] For example, FIG. 1a schematically illustrates an example embodiment of a building block 140. The building block 140 comprises multiple interdigitated electrodes extending across the building block in at least two directions. Four electrodes are shown in FIG. 1a: electrodes 131-134. When a building block is repeated across a substrate in two directions, the electrodes within the building block will form drive electrodes, e.g., multiple main lines of drive electrodes. Note that building blocks are typically connected in a substrate electrode design tool. Typically, a building block comprises five or more electrode lines. For example, within the scope of embodiments, between eight and twelve main lines are used. The number of electrode lines, however, can be much higher. For example, a building block may comprise many short electrode lines near its edges, which connect to lines of other building blocks when the block is repeated. To account for such short derivatives, the number of lines may be increased, for example, to 50. Obviously, using larger building blocks may also increase the number of electrode lines. In embodiments, the number of electrode lines in a building block is between 8 and 50, or between 8 and 25, etc.

[0056] The drive electrodes formed by repeating building blocks are connected to a drive bus. Typically, electrode lines within a building block are connected to electrode lines in neighboring blocks by merging corresponding electrode lines; this is not required, but connection zones connecting corresponding electrode lines can be inserted between repeating building blocks.

[0057] This step allows multiple main lines to be connected together, thus forming a single drive electrode. Figure 1b shows two connection zones 119 and 129, where main lines belonging to the same drive electrode are connected to drive bus 110 and drive bus 120, respectively.

[0058] The electrodes shown in FIG. 1a are alternately dashed in the same dashed line style in FIG. 1b. In fact, it happens to be the case in this example that a particular electrode of a building block in FIG. 1a always ends up either within a first drive electrode or within a second electrode, as indicated by the dashed line style in this case. This is not necessarily the case, however. An electrode within a building block may end up as part of a first drive electrode or as part of a second drive electrode. This can change the pattern in which the building blocks repeat, for example, as a result of the parity of the number of electrodes within the building block.

[0059] For example, a particular pattern of repeating building blocks may be used for an optical modulator having two drive electrodes in which alternating main lines are assigned to two drive electrodes, however, the same pattern of repeating building blocks may be used for an optical modulator having three drive electrodes in which every adjacent set of three main lines is assigned to three drive electrodes.

[0060] Additionally, while the building blocks shown in FIG. 1a are square, this is not required. For example, the building blocks may be rectangular. In embodiments, the building block shape(s) may form a so-called tessellation. For example, the building blocks may be triangles, hexagons, or even combinations of plane-filling shapes.

[0061] As mentioned, Figures 1a and 1b are schematic. This is especially true for the depiction of the electrodes. The electrodes shown in Figure 1a are straight; however, in one embodiment, the electrodes on the building blocks are more intricate, e.g., curved. By adapting the shape of the electrodes, undesirable diffraction effects can be altered.

[0062] In an embodiment, a switchable mirror includes a light modulator according to an embodiment. For example, the switchable mirror includes a transparent substrate, an optical layer, and a reflective substrate. One or both of the substrates are according to an embodiment. The switchable mirror can be electrophoretic. Typically, each substrate has two electrodes, although this is not required.

[0063] FIG. 1c shows a schematic example of an embodiment of substrate 101. Substrate 101 is similar to substrate 100, except for how the main lines formed from the electrodes on the building blocks are connected to the drive buses. In FIG. 1a, connection zones are inserted between the repeating building blocks and drive buses 110 and 120. In the connection zones, main lines belonging to the same drive electrode are connected to the same drive bus. In FIG. 1c, the drive buses are directly adjacent to the building blocks. To avoid the drive buses having to connect to main lines of different drive electrodes, some of the building blocks are modified.

[0064] For example, building block 141 may be a copy of building block 140, but electrode 134 is shortened so that main line 122 (of which line 134 is a part) does not connect to bus 110. In Figure 1c, the building blocks are substantially the same, except that a disconnect has been introduced in some electrodes of the building block adjacent to the drive bus to avoid connecting the main line to the drive bus. All building blocks shown in Figure 1c are modified in this way, but in embodiments, the majority of building blocks, e.g., building blocks not adjacent to drive buses 110, 120, are not modified.

[0065] 1d schematically illustrates an example embodiment of the substrate 102. In an embodiment, the electrodes in the building blocks each connect the same opposing sides of the building blocks. This has the consequence that the main lines formed by the electrodes on the building blocks connect opposing sides of the substrate. In such a situation, for example, having only two drive buses, each extending along opposing sides of the substrate, is sufficient to connect and drive the drive electrodes.

[0066] However, it is not required that electrodes within a building block connect opposite sides of the building block. Typically, all electrodes within a building block will connect two sides of the building block, but it is not required that these two sides be opposite. The reason for this is that electrodes may be continued by the next building block. In such situations, most main lines will still connect the same two opposite sides, but at the edge of the substrate, this may not happen because there are no additional building blocks there to carry the electrodes forward. To allow for more complex electrode designs for building blocks, main lines may be connected to the drive bus from two sides, for example, two sides of the substrate adjacent to the same corner of the substrate.

[0067] FIG. 1d shows drive bus 110' extending along two edges of the substrate and drive bus 120' extending along the other two edges of the substrate.

[0068] An advantage of this configuration is that the drive busses can be created in the same plane. This is not necessary, however. The drive busses could connect from three or all four sides if desired, for example, to allow more design freedom for the building block. Various examples are provided herein.

[0069] It should be noted that drive electrodes, e.g., drive buses and / or main lines, are allowed to overlap. This is possible, for example, by providing a portion of dielectric material between the electrodes. For example, such overlapping electrodes may be partially or completely in different planes of the substrate.

[0070] For example, in an embodiment, a first drive electrode may be deposited. Then, a dielectric is locally deposited, and finally, a second drive electrode is deposited. The dielectric is disposed to cover at least points where the first and second electrodes intersect. Vias may be used for lower first drive electrodes, for example, to connect to the lower first drive electrodes. Depositing the drive electrodes may include depositing a drive bus.

[0071] Figure 1e shows a schematic example of one embodiment of the substrate 203. In Figure 1e, the building blocks have been copied multiple times.

[0072] Building block 211 was mirrored in the y direction to form building block 221. Building block 221 was placed directly below building block 211. Building block 211 was mirrored in the x direction to form building block 212. Building block 212 was placed directly to the right of building block 211. Building block 211 was mirrored in the x direction as well as the y direction to form building block 222. For example, the mirroring may have an edge of the building block as the mirroring axis.

[0073] Mirroring the building blocks ensures that drive buses for the same drive electrode end up adjacent to each other on the substrate.

[0074] FIG. 1f schematically illustrates an example of one embodiment of substrate 204. In substrate 204, building blocks are repeated across the substrate in different ways. Building block 251 was mirrored in the y direction to form building block 261. Building block 261 was placed directly below building block 251. Building block 251 was point-reflected, e.g., rotated through 180 degrees, to form building block 252. Building block 252 was placed directly to the right of building block 251. Building block 251 was mirrored in the x direction to form building block 262.

[0075] Figures 2a-2f show schematic examples of substrates with interdigitated electrodes. These may be implemented on substrates with two electrodes, for example, by connecting the electrodes alternately. Figures 2a-2d may be implemented on substrates with multiple electrodes, for example, by connecting three or four or more electrodes in sequence.

[0076] Figures 2e and 2f show designs with two drive electrodes on the surface of the substrate. Either design could be modified to have only a single drive electrode on the surface of the substrate, for example, by removing one of the two drive electrodes. For example, such a modified design could be used in an optical modulator using a substrate with a single electrode.

[0077] The illustrated designs can be realized in a single plane without intersecting electrodes. In particular, when these designs are connected to two drive buses, intersecting electrodes are not required. When three or more drive electrodes are used, or when more complex electrode patterns are used, electrode intersecting may be used or even required. However, such intersecting is possible, for example, where two electrode lines intersect, and a dielectric material may be disposed between the electrodes. For example, such an insulator may be deposited at the intersecting location. For example, a first drive electrode is in a first plane of the substrate, and a second drive electrode is in a second plane of the substrate.

[0078] Two substrates according to the embodiments may be combined to form a light modulator, which is particularly suitable for glazing. Exemplary embodiments of the light modulator are shown below.

[0079] FIG. 3a shows schematically an embodiment of a light modulator 10 that may be applied in smart glazing.

[0080] Reference is made to patent application PCT / EP2020 / 052379, which is incorporated herein by reference, which application includes advantageous designs for modulators, which designs may be further improved, for example, by including electrodes, building blocks, and / or substrates as described herein.

[0081] The light modulator 10 can be electronically switched between a transparent state and a non-transparent state and vice versa, or between a reflective state and a non-reflective state and vice versa. The light modulator 10 comprises a first substrate 11 and a second substrate 12 arranged opposite each other. At least two electrodes are applied to the inner surface of the first substrate 11: electrodes 13a, 13b are shown. These at least two electrodes are collectively referred to as electrodes 13. At least two electrodes are applied to the inner surface of the second substrate 12: electrodes 14a, 14b are shown. These at least two electrodes are collectively referred to as electrodes 14.

[0082] A fluid 15 is provided between the substrates. The fluid contains particles 30, e.g., nanoparticles and / or microparticles, which are charged or chargeable. For example, the particles may inherently carry a charge on their surface. For example, the particles may be surrounded by charged molecules.

[0083] The electrodes are arranged to drive the particles 30 to move towards or away from the electrodes in response to an applied electric field. The optical properties of the light modulator, in particular its transparency or reflectivity, depend on the location of the particles 30 within the fluid. For example, connections may be provided to apply an electromagnetic field to the electrodes.

[0084] At least one electrode, but preferably both electrodes 13 and 14, depending on the embodiment, are shown schematically in the figures.

[0085] In an embodiment, at least one of the electrode patterns on the first substrate and the electrode pattern on the second substrate has a calculated low pixelated noise metric that contributes to diffraction. Interestingly, the electrode patterns on the substrates may not individually meet the bounds for their pixelated noise metric, but their combination, i.e., their superposition, may. Since this is the pattern that will be visible when viewed through the light modulator, a low pixelated noise metric in the superposition will also contribute to low diffraction. Suitable limits for the patterns on the first and / or second substrates or for the superposition include: less than 6.05%, 5%, or 4%.

[0086] In an example, substrate 11 and substrate 12 may be optically transparent outside the electrodes, typically >95% transparent, e.g., >99% transparent, at relevant wavelengths. Taking the electrodes into account, the transparency may be much lower, e.g., 70%. The term "optical" may relate to wavelengths visible to the human eye (approximately 380 nm-approximately 750 nm), where applicable, and may relate to a broader range of wavelengths, including infrared (approximately 750 nm-1 μm) and ultraviolet (approximately 10 nm-380 nm) and subselections thereof. In an exemplary embodiment of the optical modulator, the substrate material is selected from glass and polymer.

[0087] In another example, one substrate, such as the lower substrate 12, can be reflective or partially reflective, while the upper substrate 11 is transparent. The optical properties of the light modulator, in particular its reflectivity, depend on the location of the particles 30 within the fluid. When the panel is in the open state (vertical drive), the particles will be located approximately between the opposing electrodes of the two substrates, allowing incident light to pass relatively unimpeded through the transparent upper substrate and optical layer and be reflected or partially reflected on the lower substrate.

[0088] The distance between the first substrate and the second substrate is typically less than 30 μm, such as 15 μm. In exemplary embodiments of the optical 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.

[0089] In an example, the modulator may be made of a flexible polymer, and the rest of the device may be made of glass. The glass may be hard glass or flexible glass. If needed, a protective layer may be provided 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 a further example, the device may be made of at least one flexible polymer. Thus, the modulator may be attached to any surface, such as by using an adhesive.

[0090] The particles 30 may be configured to absorb light, thereby preventing certain wavelengths from passing through. The particles 30 may reflect light; for example, the reflection may be specular, diffuse, or somewhere in between. The particles may absorb some wavelengths and reflect others. The particles may also or instead emit light, for example, using phosphorescence, fluorescence, or the like. Even fluids may emit light, the emittance of which is modulated by changing the location of the particles.

[0091] In exemplary embodiments of the light modulator, the size of the nanoparticles is 20-1000 nm, preferably 20-300 nm, more preferably less than 200 nm. In exemplary embodiments of the light modulator, the nanoparticles / microparticles may include a coating on a pigment and preferably include a core. In exemplary embodiments of the light modulator, the coating of the particles is made from a material selected from conductive and semiconductive materials.

[0092] In exemplary embodiments of the light modulator, the particles are configured to absorb light having wavelengths of 10 nm-1 mm, e.g., 400-800 nm, 700 nm-1 μm, and 10-400 nm, and / or are configured to absorb portions of light having wavelength ranges (filters) falling within 10 nm-1 mm and combinations thereof.

[0093] In an exemplary embodiment of the light modulator, the particles are charged or chargeable. For example, the charge on the particles is between 0.1e and 10e (5*10) per particle. -7 -0.1C / m2).

[0094] In an exemplary embodiment of the light modulator, the fluid is present in an amount of 1-1000 g / m, preferably 2-75 g / m, more preferably 20-50 g / m, such as 30-40 g / m, etc. A major advantage is that with this layout, much less fluid and like particles can be used.

[0095] In an exemplary embodiment of the light modulator, the particles are present in an amount of 0.01-70 g / m 2 , preferably 0.02-10 g / m 2 , such as 0.1-3 g / m 2 .

[0096] In an exemplary embodiment of the light modulator, the particles have a color selected from cyan, magenta, and yellow, and from black and white, and combinations thereof.

[0097] In an exemplary embodiment of the light modulator, the fluid includes one or more of a surfactant, an emulsifier, a polar compound, and a compound capable of forming hydrogen bonds.

[0098] Fluid 15 may be a non-polar fluid having a dielectric constant less than 15. In an exemplary embodiment of the light modulator, the fluid has a relative dielectric constant εr less than 100, preferably less than 10, such as less than 5. In an exemplary embodiment of the light modulator, fluid 15 has a kinematic viscosity greater than 10 mPa.s.

[0099] 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 indirectly, e.g., the fluid may contact the second medium with the electrodes, such as through a porous layer. In embodiments, the electrodes cover about 1-30% of the substrate surface. In embodiments, the electrodes have an electrical conductivity (at 20°C) > 1 * 10 7 The electrodes may be electrically conductive materials having a resistivity of less than 100 nΩm (at 273 K; for comparison, typically used ITO has a resistivity of 105 nΩm), which is similar to S / m. In light modulator embodiments, the electrodes include copper, silver, gold, aluminum, graphene, titanium, indium, and combinations thereof, preferably copper. The electrodes may be in the form of microwires, e.g., copper microwires, embedded in a polymer-based substrate.

[0100] Connections for applying an electromagnetic field to the electrodes may be provided, and the electromagnetic field applied to the electrodes provides movement of nanoparticles and microparticles from the first electrode to the second electrode and vice versa. Connections for applying the electromagnetic field to the electrodes may be provided. For example, in an exemplary embodiment of the optical modulator, the current is -100 to +100 μA, preferably -30 to +30 μA, and more preferably -25 to +25 μA. For example, a power supply may be in electrical connection with at least two electrodes. The power supply may be configured to provide waveform power. At least one of amplitude, frequency, and phase may be configurable to provide different states within the optical modulator. For example, a controller may adapt the power aspect.

[0101] The light modulator 10 may comprise one or more segments, where a segment is a single optically switchable entity that may vary in size. The substrate at least partially encloses a volume that may be a segment.

[0102] The device may include a driver circuit for changing the appearance of the (individual) segments by applying an electromagnetic field. Thus, in turn, the appearance of the light modulator or one or more portions thereof may be altered. For example, the segments may be at least 1 mm 2 The design allows for stacking to allow for more colors, e.g., for a full color application, a stack of two or three modulators may provide most or all of the colors, respectively.

[0103] Having one or more segments allows the light modulator to be controlled locally, which is advantageous for some applications, but is not necessary. In smart glazing, the light modulator may be used with or without segments. For example, when applied in smart glazing, transparency or reflectivity may be controlled locally, for example, to prevent sun-patch without reducing the transparency or reflectivity of the entire window. The segments may be relatively large, for example, having a diameter of at least 1 mm or at least 1 cm.

[0104] In an exemplary embodiment of the light modulator, the substrates (11, 12) are aligned and / or the electrodes (13, 14) are aligned. For example, electrodes 13a, 13b and electrodes 14a, 14b may be aligned to face each other. In aligned substrates, the electrodes on different substrates line up when viewed in a direction perpendicular to the substrates. When the light modulator is disassembled and the substrates are placed together with the electrodes facing up, the electrode patterns are each a mirror image of the other.

[0105] Aligning the substrates may increase the maximum transparency or reflectivity of the light modulator, while when selecting a light modulator for more criteria, such as the range of transparency or reflectivity, it may be better not to align the two substrates or to align them completely. Light modulators may be stacked. For example, two stacked light modulators may be made from three substrates, with the middle substrate having electrodes on both surfaces. In light modulator embodiments, optionally, at least one substrate 11, 12 of a first light modulator is the same as the substrate 11, 12 of at least one second light modulator. In the case of stacked modulators, alignment may increase the maximum transparency or reflectivity, but may be detrimental to other considerations, such as diffraction.

[0106] FIG. 3b schematically illustrates an example embodiment of a light modulator 40. The light modulator 40 is similar to the light modulator 10, except that it includes multiple optical layers; two optical layers are shown in the example. There may be more than two optical layers. Each optical layer is disposed between two substrates. The light modulator 40, as in FIG. 3a, may be considered a stack of two-substrate light modulators. 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 located between the substrates 41 and 42, and an optical layer is located between the substrates 42 and 43. The optical layers may be similar to those of the light modulator 10. A controller 46 is configured to control the current on the electrodes of the substrates. For example, in FIG. 3b, the controller 46 may be electrically connected to at least 4×2=8 electrodes.

[0107] Interestingly, the particles in multiple optical layers can be different, allowing multiple layers to be used to control more of the optical properties of the light modulator. For example, particles in different optical layers can absorb or reflect at different wavelengths, e.g., different colors. This can be used by the controller 46 to create different colors and / or different color intensities on the panel. For example, a four-substrate panel could have three optical layers, each with different color particles, e.g., cyan, yellow, and magenta. By controlling the transparency or reflectivity of the different colors, a wide color spectrum can be created.

[0108] The surface of a substrate facing another substrate may be provided with more than one pattern, as in the case of, for example, embodiments, where outer substrates 41 and 43 may receive electrodes only on their inner faces, while an inner substrate, e.g., substrate 42, may have electrodes on both sides.

[0109] Both substrates 41 and 42 may be considered embodiments of an optical modulator. Similarly, both substrates 42 and 43 may be considered embodiments of an optical modulator.

[0110] FIG. 3c shows a schematic example of an embodiment of a car 20 having smart glazing for the window 21. This is a particularly advantageous embodiment because incident light levels can often change rapidly during driving. Using smart glazing in a car has the advantage that light levels can be maintained at a constant level by adjusting the transparency of the car's windows. Furthermore, reduced diffraction effects improve safety by reducing driver distraction. The car 20 may include a controller configured to control the transparency or reflectivity of the window 21.

[0111] Smart glazing can be used in other glazing applications as well, especially in buildings, offices, homes, greenhouses, and skylights, which are windows placed in the ceiling to allow sunlight to enter a room.

[0112] The optical modulator may have two optical states, for example, a transparent state and a non-transparent state or a reflective state and a non-reflective state. - switching to a second optical state, e.g. a non-transparent or non-reflective state, by creating an AC voltage on at least one of the first and second substrates and applying an AC current between at least the first and second electrodes on the first substrate and / or between the first and second electrodes on the second substrate; - switching to a first optical state, e.g. a transparent state or a reflective state, by creating an AC voltage between the first substrate and the second substrate and applying an AC current between a first electrode on the first substrate and a first electrode on the second substrate and / or between a second electrode on the first substrate and a second electrode on the second substrate; It can be configured as follows.

[0113] The electrode pattern on the first substrate is at least partially arranged in the same pattern as the second electrodes on the second substrate. Typically, the electrodes face each other, but the patterns of the first and second electrodes may be shifted relative to each other.

[0114] A protective coating may be provided on at least a portion of an inner surface area of ​​at least one of the first and second substrates.

[0115] The drive signals applied to the drive electrodes typically have varying voltages. For example, the power supply may operate at an AC frequency to switch between transparent and non-transparent states. Such signals may have frequencies between 1-1000 Hz, for example. Balanced electrolytic currents may be achieved by continuously switching the polarity of oppositely charged electrodes on the first and second substrates and / or between the first and second substrates.

[0116] 4a-4b show schematic side views of an embodiment of a light modulator in use. Applying an electric field to electrodes on a substrate results in an electric force on the particles. Using this effect, the particles can move around, thereby resulting in different transparency or reflectivity states within the light modulator. A controller can control the electric field, e.g., its amplitude, frequency, and phase. In an embodiment, the controller is connected to at least four electrodes: two electrodes for each substrate. However, more electrodes may be used and connected to the controller; for example, three or more electrodes may be used for the substrates to better fine-tune the grayscaling and drive to a non-transparent or non-reflective state. Multiple electrodes may also be used to support multiple segments on the substrate.

[0117] Figure 4a shows the light modulator with no electric field applied, in which no electric force is yet applied to the particles 30 suspended in the fluid 15.

[0118] In the configuration shown in Figure 4a, the conductive electrode pattern disposed on the upper substrate is fully or substantially aligned with the conductive electrode pattern on the lower substrate. The conductive electrode pattern may be deposited on a transparent or (partially) reflective glass substrate, or may be embedded in a plastic substrate, etc.

[0119] Alignment between the upper and lower electrode patterns contributes to a wider range of achievable levels of transparency or reflectivity. However, alignment is not required, as similar effects can be achieved without alignment. A range of transparency or reflectivity can also be achieved without alignment.

[0120] Note that in these examples, reference is made to a top substrate and a bottom substrate to refer to the substrate that is higher or lower on the page. The same substrates could also be referred to as, for example, a front substrate and a back substrate, because in glazing applications, the substrates would be aligned vertically rather than horizontally.

[0121] FIG. 4b shows a light modulator in which, for example, at instance P1, a potential +V1 is applied to each microwire electrode on the upper substrate, while a negative voltage, e.g., −V1, is applied to each microwire electrode on the lower substrate. Thus, in this case, the same positive potential is applied to all electrodes 13, and the same negative potential is applied to electrode 14. The potential difference causes negatively charged particles to flow near the electrode on the upper substrate, where they substantially align with the upper electrode. As a result, if both the upper and lower substrates are transparent, the transparency of the light modulator 10 will increase. Similarly, for example, if the upper substrate is transparent and the lower substrate is reflective, the reflectivity of the light modulator 10 will increase. If the solution contains positively charged particles, those particles will flow near the electrode on the lower substrate, where they substantially align with the lower electrode.

[0122] Similar transparency or reflectivity can be achieved when, at a second time point P2 in the on state, the voltages on the upper and lower electrodes are reversed in contrast to time point P1. At time point P2, the voltages on each electrode on the upper substrate are now supplied with a negative potential -V1, while the voltages on the aligned electrodes on the lower substrate are supplied with a positive potential. This state is similar to the state shown in FIG. 4b, except that the upper and lower substrates are inverted. In this configuration, the transparency or reflectivity of the optical modulator 10 is also high.

[0123] Interestingly, by switching between a positive potential on the electrode of the upper substrate (and a negative potential on electrode 14), e.g., shown as electrode 13 in Figure 4b, and a positive potential on the electrode of the lower substrate, e.g., shown as electrode 14 in Figure 4b, transparency or reflectivity can be maintained while reducing corrosion damage to the electrodes. This AC electric field can be achieved by applying AC potentials to the upper and lower electrodes.

[0124] Applying a waveform is optional but useful for increasing the lifespan of light modulators by reducing corrosion. Corrosion can form, for example, when using copper electrodes because copper ions dissolve in the ionic fluid on one substrate and flow to the electrode on the opposing substrate, where they deposit. By applying a waveform, the copper ion transport direction is frequently reversed, thus reducing corrosion damage. Between two points P1 and P2, the corrosion current between the two substrates is balanced, or substantially balanced, e.g., by >95%. For example, as the corrosion rate of the electrode on the top plate occurs, there is a balancing deposition of copper on the bottom electrode between each time point P1 and vice versa at time point P2. Thus, particles continuously migrate or move between the top and bottom electrodes, and the light modulator or smart window is always in an on state, while the dynamic electrolytic current between the top and bottom electrodes is constant, resulting in no or negligible net loss of electrode material on the top and bottom electrodes.

[0125] FIG. 4c illustrates how a state of reduced transparency or reflectivity can be achieved. Alternating voltages are applied to the same substrate. For example, in an embodiment, as shown in FIG. 8c, a potential +V2 is applied to a first electrode, and the next adjacent electrode has an opposite potential −V2, etc. This can be achieved by applying a potential +V2 to electrode 13a and an opposite potential −V2 to electrode 13b. On an opposing substrate, a potential +V2 can be applied to electrode 14a and an opposite potential −V2 can be applied to electrode 14b. For example, the electrodes can be arranged so that the electrodes on the substrates are aligned, with an electrode on the upper substrate having a counter electrode on the lower substrate, and vice versa. For example, to reduce transparency or reflectivity, the counter electrodes can receive the same potential, while the neighboring electrodes receive opposite potentials. An embodiment is shown in FIG. 4c, where four electrodes are designated by reference numerals 13a, 13b, 14a, and 14b, and the rest of the electrodes continue in an alternating order.

[0126] By using this AC drive cycle between the top and bottom substrates, diagonal and transverse electric fields are generated between the two substrates, which results in random diffusion of the particles, thereby creating the closed state of the light modulator. As a result of this configuration, the particles move diagonally and transversely between the top and bottom substrates, and the diffusion of the particles into the visible aperture of the light modulator contributes to the closed, opaque state of the light modulator.

[0127] For the transparent state shown in Figure 4b, a waveform may be applied to the electrodes, for example, such that the electrodes shown in Figure 4b with a positive potential are negative, and vice versa. As in Figure 4b, applying a waveform between, for example, electrodes 13a and 13b and 14a and 14b reduces corrosion damage to the electrodes.

[0128] The AC drive cycle may be performed by using an interdigitated line configuration that combines upper and lower electrode configurations, such as those shown in plan view in Figures 1a, 1b, 2a-2f.

[0129] The degree to which the transparency or reflectivity increases or decreases in Figures 4b and 4c depends on the voltage difference and the frequency difference. Varying the voltage difference controls the amount by which the transparency or reflectivity increases or decreases, respectively. For example, a curve representing light transmittance versus voltage may be determined, e.g., measured. To obtain a particular level of light transmittance, e.g., a particular transparency, e.g., a particular grayscale level, a corresponding voltage, e.g., an AC voltage, may be applied. By interpolating the signals for the transparent state or the non-transparent state, a level between transparent and non-transparent may be obtained. Similarly, a curve representing light reflectance versus voltage may be determined, e.g., measured. To obtain a particular level of reflectivity, a corresponding voltage, e.g., an AC voltage, may be applied. By interpolating the signals for the reflective state or the non-reflective state, a level between reflective and non-reflective may be obtained.

[0130] Different electrode patterns may be used for the light modulator. Each electrode pattern may provide a range of grayscales, e.g., levels of transparency or reflectivity, that the light modulator can achieve. However, the specific range of grayscales for any particular electrode pattern may differ from another electrode pattern. In other words, different patterns may provide increased transparency or reflectivity or increased opacity, but the exact response to the drive signal depends on many factors, including the specific pattern used. The variation in the optical properties of the light modulator may have good resolution, e.g., less than 1 mm. Note that pixilation of the light modulator is not required to achieve different optical patterns, e.g., logos, that are visible in the light modulator.

[0131] This effect may be used to embed a visible image in a light modulator by locally modifying the electrode pattern on the substrate of the light modulator. For example, different electrode patterns may locally have grayscales that have a permanent grayscale offset relative to each other. For example, by locally modifying the electrode pattern or its pitch, the maximum transparency or reflectivity may be changed.

[0132] The result is areas on the light modulator with different intensities of grayscale, e.g., different grayscales or different intensities of coloration. The areas may, however, have the same color point. In embodiments, they may switch along with the rest of the window, albeit at different speeds. For example, even if the same voltage is applied to electrodes in two different areas, they may result in different transparency states, e.g., different transmission levels, due to the different electrode patterns. For example, a curve representing transmittance versus voltage may be shifted. For example, if the voltage control is changed in the same way in both areas, the light transmittance in both areas may change, but by different amounts. Areas may be made less responsive to drive signals by reducing the density of electrodes, and in particular, areas may be made not to switch at all, for example, by not applying electrodes within the area.

[0133] For example, electrode materials can be copper, aluminum, gold, indium-tin oxide (ITO), etc. ITO is transparent, while Cu / Al is reflective; therefore, different electrode materials can be used to achieve different appearances, regardless of the driving voltage. Similarly, different materials with different resistivities will produce different electric fields. For example, ITO will have a smaller electric field even when driven by the same voltage.

[0134] An embodiment of a method for modulating light includes applying an electric potential to a plurality of drive electrodes applied to two opposing substrates according to an embodiment of obtaining an electromagnetic field between the plurality of drive electrodes, to provide electrophoretic movement of particles toward or away from one drive electrode of the plurality of drive electrodes, resulting in modulation of light shining through the substrates, the two opposing substrates being as in one embodiment.

[0135] According to one embodiment, a light modulator is disclosed herein that includes a first substrate. For example, the first substrate may be transparent and have drive electrodes and patterned elements applied thereto. The drive electrodes may be configured for electrophoretic and / or dielectrophoretic control of particles within an optical layer of the light modulator.

[0136] The light modulator may include a second substrate. The second substrate may have a patterning element or may be a conventional substrate without a patterning element. Having a patterning element in at least one substrate, e.g., the first substrate, provides control over light diffraction and is an improvement over known light modulators. Having two substrates, e.g., the first substrate and the second substrate, with optically active elements provides even more control.

[0137] In one embodiment, the second substrate may be non-transparent, e.g., opaque. For example, such an embodiment may be used for a dynamic mirror or e-reading system. Typically, both the first and second substrates are transparent, particularly in smart glazing applications.

[0138] 5a shows a schematic diagram of an example embodiment of a light modulator 501. The light modulator 501 comprises 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. Within the optical layer 524 are particles 523 that affect the optical appearance of the light modulator. At least one drive electrode 521 is applied to the first substrate 511. The optical properties of the light modulator can be modified by applying an electric potential to the at least one drive electrode 521. In the example shown, at least one drive electrode 522 is also applied to the second substrate 512.

[0139] The light modulator is shown in a state where the particles are aligned with the electrodes. This typically corresponds to the most transparent state of the light modulator. In another state of the light modulator, the particles may be dispersed throughout the optical layer 524. This typically corresponds to the least transparent state of the light modulator. Depending on the properties of the particles, this could be an opaque state, for example, where they absorb light, or this could be a reflective state, for example, where they reflect light.

[0140] The surface of the substrate 511 or the substrate 512 that faces the optical layer 524 is called the first surface.

[0141] At least one drive electrode 521 is arranged in a pattern across the substrate 511. The at least one electrode 521 is arranged to receive an electrical potential, resulting in modulation of the optical properties of the light modulator. At least one drive electrode 522 is arranged in a pattern across the substrate 512. The at least one electrode 522 is arranged to receive an electrical potential, resulting in modulation of the optical properties of the light modulator.

[0142] In a preferred implementation of a preferred light modulator, such as the light modulator shown in Figure 5a, at least two drive electrodes are applied on a first substrate 511 and at least two drive electrodes are applied on a second substrate 512. In this preferred light modulator, particles 523 in the optical layer 524 are charged and are movable under electrophoretic forces that can be modified by electrodes on the substrates.

[0143] The patterning element 541 is applied to the surface of the substrate 511 to modify the phase, amplitude, and / or polarization of light interacting with the substrate. That is, the surface of the substrate 511 is configured to have optical properties that turn the substrate into a so-called metasurface. In this case, the patterning element 541 is applied to a second surface of the substrate 511, e.g., the surface opposite to the surface carrying at least one electrode 521. For example, the patterning element may be an optical element with a diameter of less than 1 micrometer parallel to the substrate. Patterning is the process of creating micro- and / or nanostructures across the surface of a material called a substrate.

[0144] Patterning elements 542 are applied to a surface of substrate 512 to modify the phase, amplitude, and / or polarization of light interacting with the substrate. That is, substrate 512 is similarly provided with a metasurface. In this case, patterning elements 542 are applied to a second surface of substrate 512, e.g., the surface opposite the surface carrying at least one electrode 522. While it is not necessary to have patterning elements 542 on the second substrate, this is advantageous as it provides greater control.

[0145] Micro- and / or nanopatterning is the process of creating nanostructures across the surface of a material, called the substrate.

[0146] Light modulator 501 further shows spacers 531. The spacers ensure that the light modulators remain a desired distance from one another. For example, the spacers may be made from the same material as the substrate, and several spacers may be distributed across the substrate. The spacers are optional; for example, instead of spacers, a border may be placed around the substrate to keep the substrates at a particular desired distance.

[0147] For example, an advantage of placing the nanoparticles on the second surface of the substrate rather than on the same side as the surface with the drive electrodes is that the distribution of the optical elements does not interfere with the photoelectrodes, and vice versa.

[0148] Figure 5b shows a schematic of an example embodiment of light modulator 502. Light modulator 502 is similar to light modulator 501, except that the patterned element, in this example, is located on the same side as the drive electrodes. Figure 5b shows patterned element 543 on a first surface of substrate 511. Figure 5b shows patterned element 544 on a first surface of substrate 512.

[0149] Having the patterning element on the same side as the surface allows the patterning element to face the optical layer, which protects the patterning element from damage, for example, abrasion.

[0150] In the example shown in Figure 5b, both substrates are provided with patterning elements, although it is not necessary that both substrates be so provided.

[0151] FIG. 5c shows a schematic example of one embodiment of a light modulator. The light modulator shown in FIG. 5c is the same as the light modulator in FIG. 5b, except that the position of the particles in the optical layer has been changed. This may be done by applying control signals to drive electrodes applied to electrodes on the substrate(s). Note that the optical effect of the patterning element may change as a result. There are various ways to handle this. The first option is to accept this effect. In this case, the patterning element may be optimized for the average case and / or commonly occurring situations, e.g., maximally transparent or maximally opaque. The second option is to similarly apply control signals to the patterning elements to modify their effect, e.g., to create a counter effect within the patterning element.

[0152] FIG. 6a illustrates schematically an example of one embodiment of a transparent substrate 601 for use in a light modulator, such as light modulator 501, light modulator 502, or any other light modulator according to an embodiment.

[0153] Substrate 601 schematically shows two drive electrodes: drive electrode 611 and drive electrode 612. The two drive electrodes are arranged in an interdigitated pattern. Thus, local control over the electric field, and therefore over the electrophoretic movement of particles, can be exerted across the substrate. Metasurfaces are also applicable in other types of optical modulators.

[0154] 6a shows patterning elements. The patterning elements are arranged in a pattern across the substrate according to the particular optical effect desired. Also shown in FIG. 6a is a vertical section line 631. Light modulator 501 and light modulator 502 may be viewed as a cross section across line 631. Note that spacers 531 are not shown in FIG. 6a.

[0155] For example, the patterning elements shown in Figures 6a, 5a, 5b, and elsewhere are two-dimensional or three-dimensional objects with nanometric geometries. Typically, the patterning elements protrude from a surface. The shape and distribution of the patterning elements alter the optical properties of the substrate. This is sometimes referred to as a metasurface. The optical properties of a metasurface can be calculated using optical simulation software.

[0156] The patterning elements on the substrate may have a plurality of different sizes, different shapes, and / or different materials. For example, the patterning elements may be obtained by shifting a two-dimensional shape parallel to the substrate and away from the substrate surface in a third dimension. For example, the two-dimensional shape may be polygonal, circular, elliptical, and the like. The shape of the patterning elements may vary in three dimensions. The patterning elements may be cylindrical, elongated, and / or curved.

[0157] The patterning elements may extend from the surface and have a height of less than 1000 nanometers, preferably between 100 and 1000 nanometers, for example 600 nanometers.

[0158] For example, the light modulator may be configured for use within a defined spectral range, such as visible light. The patterning element may be transparent within the defined spectral range, e.g., transparent to visible light. The spectral range for visible light may be defined as 400-750 nm. The patterning element may be used to configure the spectral characteristics of the light modulator.

[0159] The patterning element may have a total transmittance within a defined spectral range greater than a threshold, e.g., at least 70%, e.g., at least 80%. The total transmittance of the patterning element may be in the range [x-5, x+5], where x is the total transmittance of the substrate.

[0160] Interestingly, the patterning element does not have to be transparent. In one embodiment, the patterning element has a total transmittance within the spectral range of at most 10%.

[0161] The spectral range may include infrared light, for example, having wavelengths between 750 nanometers and 1000 or 1500 nanometers. The spectral range may include visible light and infrared light, for example, having wavelengths between 400 nanometers and 1000 or 1500 nanometers.

[0162] The patterning element is positioned in the path of light passing through the substrate and optical layer. The patterning element optically affects the light, thereby affecting the optical properties of the light modulator. Thus, by configuring the shape and / or pattern of the patterning element, the optical properties of the light modulator can be modified. For example, the patterning element can change the wavefront of light reflected from or transmitted through the substrate.

[0163] FIG. 6b schematically illustrates an example embodiment of a transparent substrate 602 for use in a light modulator. The view in FIG. 6b is from the top. In FIG. 6b, patterning elements are visible, one of which has reference numeral 622. FIG. 6b is to scale; an imaginary scale of 1 micrometer is shown at reference numeral 632. The patterning element shown may be embodied in a transparent cylinder. A top circular view of the cylindrical pattern is seen in FIG. 6b. The pattern shown in FIG. 6b is detailed; in one embodiment, the pattern extends across the substrate. Further details regarding cylindrical patterns may be found in the paper "Flat optics with dispersion-engineered metasurfaces" by Wei Ting Chen et al., which is incorporated herein by reference. Table 1 in the latter paper also lists various materials suitable for metasurfaces, along with information on size and bandwidth.

[0164] Instead of a cylinder, the patterning element may have a variety of other shapes. For example, the top view of the patterning element may be V-shaped, as shown, for example, in the paper "Broadband Light Bending with Plasmonic Nanoantennas" by Xingjie Ni et al., which is incorporated herein by reference. This paper also describes a generalized version of Snell's law that allows for better control of light manipulation. Metasurfaces may be designed in which the theoretical predictions provided by the generalized Snell's law are in good agreement with experimental data.

[0165] Fabrication of metasurfaces may use various CMOS fabrication techniques. The paper "Large-area metasurface on CMOS-compatible fabrication platform: driving flat optics from lab to fab" by Nanxi Li et al., incorporated herein by reference, discusses mass-producible, low-cost metasurfaces over large areas that can be fabricated by commonly used semiconductor techniques, for example, by lithography steppers and scanners.

[0166] An example of a method for fabricating a metasurface is given in the article "High efficiency dielectric metasurfaces at visible wavelengths" by Robert C. Devlin et al., which is incorporated herein by reference. For example, Figure 2 of the article shows the fabrication process for a dielectric metasurface.

[0167] Figure 6c.1 shows a schematic example of an embodiment of a transparent substrate for use in a light modulator. Figure 6c.2 shows a schematic example of an embodiment of a transparent substrate for use in a light modulator. Figure 6c.1 shows a side view. Figure 6c.2 shows a top view of the same configuration as shown in Figure 6c.1. The figure shows a substrate with two of its patterned elements.

[0168] The patterned element has a 2D diameter, which is defined as the largest diameter in a two-dimensional cross section of the nanoelement parallel to the substrate. For example, the 2D diameter is the longest distance between any two points of the patterned element, where the two points are constrained to lie in the same plane parallel to the substrate. The 2D diameter is shown in the figure with reference numeral 662.

[0169] The patterning elements have a height defined as the maximum extension of the patterning element from the substrate, measured in a direction perpendicular to the substrate. The height of two patterning elements is indicated by reference numeral 661. Furthermore, the distance to the next closest element is indicated by numeral 663.

[0170] In one embodiment, the 2D diameter, height and nearest distance are related to the target frequency at which the patterning element is active.

[0171] For example, in one embodiment, the 2D diameter is at most 10 micrometers, at most 2 micrometers, at most 1 micrometer, or at most 500 nanometers.

[0172] For example, in one embodiment, the minimum distance between two patterning elements is at most 2 micrometers, at most 1 micrometer, or at most 500 nanometers. For example, in one embodiment, the minimum distance between two patterning elements is at least 10 nanometers, at least 50 nanometers, at least 100 nanometers, 200 nanometers, or 400 nanometers.

[0173] A patterning element is permitted to have a longer dimension if another dimension is shorter. For example, in one embodiment, the patterning element has at least two discontinuous edges, and the shortest distance between two points on each of the discontinuous edges is at most 2 micrometers, at most 1 micrometer, or at most 500 nanometers. For example, the patterning element may be polygonal, e.g., rectangular. A rectangle may have a short edge, e.g., less than the range shown, while the other edge is long, e.g., greater than 2 microns.

[0174] For example, in one embodiment, the patterning elements extend in at least two directions. For example, the two directions may form an angle between 30 and 150 degrees, between 60 and 120 degrees, e.g., about 90 degrees. For each direction, a longest distance may be identified, e.g., the longest distance between two points on the same patterning element. In one embodiment, the shorter of the two distances is at most 2 micrometers, at most 1 micrometer, or at most 500 nanometers. For example, the nanoelements may be oval in shape, longer than they are wide.

[0175] In one embodiment, the size of the patterning elements or their inter-object distance may be different. For example, in one embodiment, different optical effects may be desired at different locations on the light modulator. For example, in signage, a holographic effect may be desired in part of the light modulator, but not everywhere. Thus, small and large patterning elements, small or large inter-object distances may be mixed within the light modulator.

[0176] For example, in one embodiment, the height is at most 2 micrometers, at most 1 micrometer, or at most 500 nanometers, preferably between 100 and 1000 nanometers in height.

[0177] In one embodiment, the 2D diameter, height, and nearest distance are all at most 2 micrometers, at most 1 micrometer, or at most 500 nanometers.

[0178] The height of the patterning elements may be uniform, for example, the patterning elements may have a flat top parallel to the substrate. The patterning element on the left in Figure 6c.1 has a uniform height. The height of the patterning elements may be uniform across the substrate, for example, all patterning elements have the same height. The two patterning elements in Figure 6c.1 have the same height.

[0179] The height of the patterning element is typically much smaller than the height, e.g., thickness, of the substrate, although patterning elements may also be applied to thin substrates. For example, in one embodiment, the substrate has a thickness of 10 microns or more, while the patterning element has a height, e.g., less than 1 micron. For example, the substrate may be a plastic film. The thickness of the substrate may be at least 10 times the height of the patterning element. The ratio, however, is typically higher. In one embodiment, the thickness of the substrate may be, for example, at least 100 times or at least 1000 times the height of the patterning element.

[0180] Figures 6d.1 and 6d.2 illustrate the functionality of metasurfaces in the context of optical modulators.

[0181] FIG. 6d.1 shows a schematic example of a light modulator 643 without a patterning element.

[0182] A primary wavefront 642 is shown incident on the light modulator. For example, the light modulator may be smart glass, and the primary wavefront 642 may come from ambient light, such as sunlight. The light modulator 643, which is shown only schematically, may be of the type shown in FIGS. 4a-4c and 5a-5b, but without the patterning elements on the light modulator that create the metasurface. The light modulator 643 shows a cross section of drive electrodes arranged in a pattern on the substrates; in this case, electrodes are arranged on both substrates.

[0183] The electrode pattern has a distorting effect on the wavefront after it passes through the optical modulator 643. A 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 be similarly calculated using, for example, generalized Snell's law.

[0184] Figure 6d.2 illustrates a schematic example of one embodiment of an optical modulator 653 with patterned elements. The optical modulator of Figure 6d.2 is similar to the optical modulator of Figure 6d.1 except that it includes patterned elements that form a metasurface according to one embodiment.

[0185] A primary wavefront 642 is shown incident on the optical modulator. Optical modulator 644 uses the same drive electrodes as in FIG. 6d.1, but includes patterning elements extending across the substrates to form a metasurface on the optical modulator. One patterning element is shown with reference numeral 655. In this example, a patterning element is applied to one side of each substrate, in this case the side facing the optical layer of optical modulator 653. As shown herein, a metasurface may alternatively or similarly be formed on the surface facing away from the optical layer, and a metasurface may be formed on only one substrate or on more than two substrates.

[0186] The nanopatterned elements have an effect on the wavefront in addition to the effect of the driving electrodes. The elements may be selected to correct the wavefront, and Figure 6d.2 shows the corrected wavefront 654.

[0187] The pattern elements were selected in a computerized selection algorithm that calculates the effect on the primary wavefront 642 of the combination of drive electrodes and patterned elements. The location and / or shape of the patterned elements are modified in multiple iterations to minimize a loss function that includes one or more loss terms.

[0188] The loss term used in this case includes a distance term between the exiting wavefront and the normal primary incident wavefront. That is, any optical changes in the wavefront are minimized. For example, the minimization may be for a specific light frequency, or for multiple frequencies, e.g., representing visible sunlight. For example, the minimization may be for various angles of light. The severity of the optical artifacts may depend on the properties of the light, e.g., its direction and frequency(ies). By simulating for a range of conditions, a design that performs well overall may be chosen.

[0189] Thus, multiple candidate designs may be simulated for a range of conditions, e.g., different lighting conditions. A design is selected from the multiple candidate designs that has favorable simulated results, e.g., the lowest average loss across the conditions.

[0190] An additional or alternative loss term that may be used directly assesses the severity of known artifacts, such as rainbow effects and diffraction. Minimizing this loss term allows the light modulator to have an effect on the light, but the distracting element is reduced. Optimization may use hill climbing techniques such as simulated annealing.

[0191] To reduce computation time, in one embodiment, the pattern of patterning elements forming the metasurface may be optimized for a small area, e.g., a building block, which may be repeated across the substrate.

[0192] To reduce computation time, in one embodiment, patterning elements are selected from a predetermined set, for example, using a set of cylindrical or inverted V-shaped elements of a limited number of sizes. Optimizing the metasurface can now be simplified to selecting from a limited number of sizes and element locations. Therefore, optimization does not need to consider the entire range of possible sizes. A still further reduction in computation time may be obtained by restricting the element locations to a predetermined grid. A still further reduction in computation time can be obtained by restricting the possible rotations of the elements to a limited number of predetermined sizes. The latter optimization is not applicable to rotationally symmetric elements, e.g., cylinders, but can be used for polygonal shapes, e.g., inverted V-shaped elements.

[0193] The optimization may optimize the location of the electrodes along with the patterning elements, in which case the loss terms may include losses specific to the electrodes, such as how well the optical modulator performs, e.g., the speed and uniformity of state transitions.

[0194] In Figure 6d.2, the optimization aims to reduce the effect of the electrodes on the wavefront. This is not necessary, however, and the optimization may instead aim to introduce any desired modification to the wavefront. For example, in one embodiment, the patterning element is configured to modify the wavefront 642 of light passing through the substrate to generate a holographic image.

[0195] Patterning elements, e.g., subwavelength-scale geometric structures, can be tailored to create a wide range of optical functions. To create metasurface designs, e.g., patterns of patterning elements that provide a desired optical response, topology optimization may be used, e.g., using freeform metasurfaces. For example, topology optimization may use a local gradient-based optimizer, e.g., using an adjoint variables method. A local gradient-based topology optimizer takes an initial device design and iteratively improves it through perturbations, e.g., small changes to the geometric layout of the metasurface and / or patterning elements, to approach the desired optical response. Advantageously, the perturbations may be obtained using the adjoint variables method. This approach enables the creation of advanced metasurfaces with capabilities beyond those of existing design methods.

[0196] For example, gradient-based optimization may use the adjoint variable method. In this approach, a set of adjoint variables is introduced and used to calculate the gradient of the objective function with respect to the design variables. This gradient information is then used to make small adjustments to the design to improve the performance of the system. The objective function may include distortion parameters, such as diffraction and rainbow coloring, uniformity, and possibly a target grayscale. Optimization may also be combined with one or more distributions of particles, such as those that can be created by drive electrodes, as shown in Figures 5a-5c.

[0197] Topological optimization is further discussed in "Metagrating Topology Optimization" by J. Fan, which is incorporated by reference.

[0198] Patterns of patterning elements, e.g., metasurfaces, may be used for various purposes. An important application is to correct the optical effect of electrodes. Like patterning elements, drive electrodes also affect the optical effect of optical modulators. Patterning elements can create an inverse optical effect compared to the optical effect created by the drive electrodes of the modulator, e.g., compensate for optical aberrations produced by the drive electrodes. For example, a common problem with substrates of the type shown in Figure 6a is diffraction, sometimes referred to as the rainbow effect. Patterning elements can offset the diffraction caused by the electrodes. The patterns shown in Figures 2a-2f experience diffraction to different degrees. For example, pattern 2f has much better properties in this regard than, e.g., the pattern in Figure 2b. Nevertheless, in both cases, adding patterning elements helps reduce the rainbow effect.

[0199] The patterned elements 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, scattering, and perturbation of light as it passes through or reflects off the substrate. Diffraction effects caused by the drive electrodes can be reduced by positioning the patterned elements to create an equal but opposite distortion.

[0200] In one embodiment, the patterning elements are configured to reduce, eg, minimize, light reflection, such that the opaque state of the light modulator is seen as a darker black due to the reduced reflection.

[0201] In one embodiment, the patterning elements are configured to focus incident light within the optical layer of the light modulator, which reduces artifacts. For example, in a light modulator comprising a first substrate, an optical layer, and a second substrate, the patterning elements on the first substrate and / or the second substrate may be positioned to focus incident light, e.g., light entering the first substrate and / or the second substrate from outside the light modulator, within the optical layer.

[0202] The patterning element may provide light wavelength control, filtering light passing through the substrate according to wavelength. The optical effect provided by the patterning element may be different for different wavelengths of light. The patterning element may provide light polarization control, manipulating linearly or circularly polarized light. For example, polarization may be affected by having a patterning element that is not rotationally symmetric. For example, rectangular, non-rectangular objects will affect the polarization of light.

[0203] In one embodiment, the patterning elements are fixed. For example, the elements may be applied onto the substrate from a fixed material with a predetermined shape. For example, the elements may be passive. This is not required, however. In one embodiment, the patterning elements introduce optical distortions that depend on an external factor, such as temperature, pressure, and / or an electric field. For example, the patterning elements may include a phase change material. For example, the patterning elements have a controllable shape. For example, U.S. Patent Application Publication No. 2021333575(A1) (incorporated by reference) discloses reversible phase change materials suitable for incorporation into metalenses.

[0204] For example, in one embodiment, the nano-elements may be electrically and / or temperature controlled, preferably independently from the electrodes. Preferably, the nano-elements may be independently controlled.

[0205] In one embodiment of the optical modulator, there is an interaction between the temperature of the optical modulator and the temperature-induced phase change of the metasurface.

[0206] The temperature of the light modulator may be changed by various means, for example, by a heating element, e.g., a heating wire, a micro-heating element. The paper "Modeling and fabrication of Pt micro-heaters built on alumina substrate" by Goran Miskovic shows a micro-heating element on a glass coated substrate, and is incorporated herein by reference.

[0207] Varying the shape of the patterning element provides greater control over how the wavefront is modified by the light modulator. For example, a patterning element having a variable shape may be arranged in different shapes, e.g., during operational use of the light modulator. This allows, for example, for the phase, amplitude, and / or polarization of light interacting with the substrate to be altered. For example, in one embodiment, the patterning element comprises a phase-change material having optical distortion that depends on an external factor, e.g., temperature, pressure, and / or electric field.

[0208] Figure 6e.1 shows a schematic example of a light modulator with conductive patterned elements in an inactive state. Figure 6e.2 shows a schematic example of a light modulator with conductive patterned elements in an active state. The substrates in these figures may be used as one of the substrates in a light modulator, e.g., an electrophoretic light modulator, of the type shown in any of Figures 3a-5b.

[0209] The patterning element is applied to a substrate, shown here from above in a plan view. The patterning element is shown as a rectangle. The patterning element is transparent, e.g., transparent to visible light or transparent in the target spectrum. As a result, the patterning element has a reduced optical effect; e.g., the patterning element may form a metasurface, but the effect may be relatively small. In particular, the patterning element may be positioned with a refractive index close to that of the substrate to further reduce the optical effect.

[0210] In one embodiment, a substrate, e.g., a first substrate, is used in a light modulator configured to allow particles to be aligned with patterned elements. While this may be done by placing drive electrodes near or beneath the patterned elements, a particularly advantageous way of doing this is by using conductive patterned elements. The conductive patterned elements may be supplied with an electric potential such that particles can be moved toward the conductive patterned elements, e.g., using electrophoretic forces. For example, a second substrate may have conductive patterned elements aligned with elements of the first substrate. For example, the elements of the second substrate may be arranged in a mirrored pattern relative to the pattern on the first substrate.

[0211] By applying an electric potential to the conductive patterning elements, the charged particles align with the conductive patterning elements. The effect is shown in Figure 6e.2. Previously, the patterning elements were transparent and had a smaller optical modulation effect; through the aligned particles, the transparency is reduced and the optical effect of the patterning elements is increased. In this way, a metasurface is created, the effect of which can be increased or decreased as desired.

[0212] The conductive patterned elements may be electrically controlled from the same drive electrodes used in the light modulator to modulate light. The conductive patterned elements may be electrically controlled from drive electrodes applied specifically for the conductive patterned elements.

[0213] Thus, in one embodiment, the patterning element may be conductive and configured to modulate particles, e.g., light-absorbing particles, e.g., particles that absorb light in a target spectrum, e.g., visible light. The optical properties of the patterning element are modulated. The patterning element may comprise ITO, e.g., patches of ITO.

[0214] In one embodiment, all or a portion of the patterning elements on the substrate are transparent and electrically conductive. For example, they may be transparent according to the absorption range targeted by the light modulator and / or the substrate. For example, the light modulator may be configured for use within a defined spectral range, such as visible light. The patterning elements may be transparent within the defined spectral range, e.g., transparent to visible light.

[0215] Furthermore, the optical parameters of these patterning elements may be close to the optical parameters of the substrate, particularly the refractive index. For example, the patterning elements may have a refractive index within 10% of the refractive index of the substrate.

[0216] The conductive patterned elements are configured to interact with particles in the optical layer of the light modulator.

[0217] The patterning elements are configured to receive an electrical potential to provide control over optical modulation in the light modulator. For example, the patterning elements may be individually electrically addressable, e.g., in a matrix addressing scheme. The patterning elements may be applied to the first surface in a regular grid covering at least a portion of the first surface, e.g., as part of a matrix addressing scheme. The matrix addressing may use separate electrodes from the drive electrodes. For example, the light modulator may be pixelated, with rows and columns addressing the patterning elements and, optionally, the drive electrodes. This allows for localized adaptation of the optical effect, and optionally, transparency.

[0218] The light modulator is configured to control the gray scale of the light modulator by modulating the position of the particles in the optical layer. This may be done by applying a control signal, e.g., an electrical control signal, to electrodes on the substrates. For example, in one embodiment, the two substrates each have at least two electrodes, so that the charged particles in the optical layer between the two substrates can be controlled, thereby achieving a controllable gray scale. For example, the signal may be an AC signal.

[0219] In one embodiment, the optical effect of the patterning element may be modulated in a light modulator. For example, the patterning element may be modulated by changing the temperature, for example, in a pattern comprising a phase change material. For example, the patterning element may be conductive, such that light absorbing particles in the optical layer may accumulate near the patterning element.

[0220] The light modulator may be configured to control the light modulator by applying a first control signal to the drive electrodes and a second control signal to the patterning element, in one embodiment the second control signal to the patterning element depends on a desired greyscale level set in the modulator, for example set by a user.

[0221] For example, signals may be obtained in a calibration phase before the operation phase. For example, the light modulator may be installed, perhaps at its final destination, e.g., in the form of smart glazing. A sensor, e.g., a camera, may be positioned to observe the effect of the light modulator. The sensor measurements may be used to modify the first control signal and / or the second control signal to reduce the occurrence of undesired phenomena, e.g., diffraction, rainbow phenomenon. For example, in the calibration phase, the light modulator may be driven over a range of the first control signal and the second control signal. For various signals, sensor measurements, e.g., images, are recorded. From the sensor measurements, optical parameters, in particular the gray scale, e.g., the transparency level of the light modulator, and distortion values, e.g., the observed amount of diffraction and / or rainbow phenomenon, are derived.

[0222] In one embodiment, information about the direction of incident light, e.g., sunlight, may be obtained from a GPS sensor, e.g., as part of a satnav device. This is particularly useful in vehicles, e.g., vehicles with smart glass. This information may also be obtained dynamically during operational use.

[0223] In one embodiment, for example, information regarding the orientation of the glass may be obtained by applying a sensor to the glass, for example, during a calibration phase. The sensor may be fixed, e.g., part of the smart glass package, but may also be temporary. In particular, the orientation information may be obtained by placing a smartphone flush against the glass. For example, an application on the smartphone may transfer the orientation information to a controller of the smart glass, e.g., a light modulator.

[0224] Orientation information is useful because the control signals for the patterning elements may depend on the current angle of the light.

[0225] An algorithm may be applied to the sensor values ​​and the calibration control signal to derive a model for the optical modulator from the sensor measurements, which model predicts the optical effect of the optical modulator and its current control signal. The model or algorithm may be computational, applying physical laws such as Snell's Law, but may advantageously instead be a machine learning model. For example, a neural network may be trained to predict the optical effect from the control signal and possibly other sensor values—the optical modulator may be equipped with sensors such as temperature and light sensors. From the sensor values ​​indicating the effect of a particular control signal, the algorithm learns which control signal to use to achieve the particular effect. After the calibration period, the camera may be removed. In one embodiment, the system may continue to learn and further optimize the model, for example, using user feedback or sensor measurements. Similarly, relatively slow changes in the environment will be automatically taken into account. The optical modulator may be manufactured independently of the environment in which it will ultimately be installed and operate, while still obtaining precise optical control. Control of the metasurface may depend on the angle and intensity of the incident light.

[0226] Thus, the first and second control signals can be stored and / or derived when needed. Depending on the current sensor values, for example, the current temperature and / or the current light level or angle, the appropriate control signal can be derived.

[0227] One embodiment of a method for calibrating an optical modulator includes: - Providing a light modulator, e.g. installing a light modulator. The light modulator may be installed in a fixed position, e.g. in a building, e.g. as smart glass in an office. The light modulator may be installed in a non-fixed position, e.g. in a vehicle, e.g. as smart glass in a car. - Obtaining information about the distortion and / or transparency of the light modulator from an image sensor observing the light modulator. For example, the image sensor may be a temporary image sensor installed to obtain information about the optical effect of the light modulator. For example, the image sensor may be a camera installed in front of the light modulator during the calibration phase. For example, the camera may be placed on a tripod. For example, the image sensor may be placed inside a room of a building in which the glass is placed. For example, the image sensor may be placed inside a vehicle in which the glass is placed. If the light modulator is not stationary, it may be moved during the calibration phase or part of it, for example by driving the vehicle in which the light modulator is installed, possibly while recording orientation information. - Driving a control signal for controlling the optical modulator in an operating phase.

[0228] During the calibration phase, multiple control signals for the drive electrodes and / or for the pattern elements may be applied. An image sensor may observe the effect. The effect may be summarized in distortion and transparency values, e.g., grayscale values. Control signals that provide a desired effect, e.g., a particular 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 capable model may be trained to predict the effect of the light modulator from the control signals. An advantageous control signal may be derived by trying multiple control signals in the trained model, e.g., by selecting a control signal with desired parameters.

[0229] In one embodiment, the calibration method further comprises obtaining information about the orientation of 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 satnav device, or a smartphone. The orientation sensor may be stand-alone. The orientation sensor may be temporary, e.g., applied only during a calibration phase. In one embodiment, the light modulator comprises the orientation sensor.

[0230] The orientation sensor and the image sensor may be configured to provide sensor data, eg measurements, eg image and / or orientation information, to a controller of the light modulator.

[0231] After the calibration phase, the light modulator may be controlled. A method of controlling the light modulator may include applying an electric potential to the drive electrodes to modulate an electromagnetic field in the optical layer, providing electrophoresis and / or dielectrophoresis of particles in the optical layer, and modulating light passing through the substrate. For example, the control signals applied to the drive electrodes may be control signals stored during the calibration phase. Patterning elements applied to the surface of the light modulator may alter the phase, amplitude, and / or polarization of light passing through the substrate.

[0232] The patterning elements may be passive, e.g., not configured to receive a control signal. In one embodiment, the patterning elements are active, e.g., configured to receive a control signal to modulate their optical effect. For example, the patterning elements may comprise a phase-change material having an optical distortion that depends on an external factor, e.g., temperature, pressure, and / or electric field, and the method includes modulating the external factor to modulate the optical distortion. The patterning elements may be conductive and configured such that their optical effect is modulated through particles selectively disposed on top of the patterning elements. The control method may include modulating an external factor, e.g., applying a control signal to modulate the optical distortion. The control signal may be stored in or derived from a calibration phase.

[0233] Patterning elements may be combined with coatings and applied to various surfaces of the substrate for various advantages. Figures 7a-7g all show substrates for use in light modulators. The substrates in the figures assume that ambient light is above the figure and that the optical layer is below the substrate. Only in Figure 7a is the side configured to face the optical layer indicated schematically by reference numeral 712, while Figures 7b-7g are oriented similarly. The bottom substrate can be obtained from any of Figures 7a-7g by mirroring it in the horizontal axis.

[0234] 7a shows a schematic example of one embodiment of a transparent substrate for use in a light modulator. The figure shows a transparent substrate 711.

[0235] The substrate 711 has two surfaces, a first surface configured to face towards the optical layers of the light modulator, this side of the substrate being indicated with reference numeral 712 .

[0236] Starting with substrate 711, a layer having patterning elements is applied to a first surface of substrate 711. One patterning element is indicated by reference numeral 745. The patterning elements are arranged to modify the phase, amplitude, and / or polarization of light that interacts with the substrate. Light that interacts with the substrate includes light that passes through the surface and / or light that reflects from the surface. For example, the patterning elements may be arranged to form a metasurface.

[0237] In this example, the patterning elements are coated with a patterning element coating 751. Coatings used in light modulators are typically transparent. Protective coating 751 prevents physical damage to the nano-elements.

[0238] The substrate 711 has at least one drive electrode applied to the substrate 711 on a first surface. One electrode has the reference numeral 721. All of the electrodes shown may form part of one connected electrode. In a preferred electrophoretic light modulator, at least two interdigitated electrodes are applied. The electrodes may be used to modulate the optical properties of the light modulator.

[0239] In this example, starting with the substrate, a coating with patterned elements is applied followed by a pattern of drive electrodes. In this example, no coating is applied to the electrodes. In this configuration, the electrodes make fluid contact with the optical layer. In this configuration, the patterning of the nano-elements and electrodes can be determined independently of each other's locations.

[0240] Figure 7b shows a schematic diagram of an example embodiment of a transparent substrate for use in a light modulator. The substrate is similar to that of Figure 7a, except that a coating 752 for the drive electrodes is applied in this example. In this configuration, the electrodes do not make direct fluidic contact with the optical layer. Both coatings 751 and 752 are typically non-conductive and transparent.

[0241] The protective coating 752 prevents direct contact between contaminants, such as grains of sand, fibers, pebbles, clumps, particles, etc., present in the optical layer and the electrodes. These contaminants can form in a variety of ways, such as by agglomeration of smaller particles, static electricity, entrapment between electrodes, etc. The contaminants can cause short circuits between electrodes on opposing substrates, between adjacent electrodes on the same substrate, physical damage to the electrodes themselves, or any combination of these. In one embodiment, the protective coating prevents both physical damage to the electrodes and short circuits between electrodes.

[0242] Figure 7c shows a schematic diagram of an example embodiment of a transparent substrate for use in a light modulator. The substrate is similar to that of Figure 7a, except that both the nanoelements and electrodes are applied to the substrate in the same layer in this example. This configuration is thinner compared to, for example, Figure 7b. The selection of locations for the nanoelements here depends on the electrodes; for example, the nanoelements cannot be positioned where the electrodes are positioned. A combination coating 753 for the driving electrodes and patterned element coating is applied to both the nanoelements and the electrodes.

[0243] 7d shows a schematic example of one embodiment of a transparent substrate for use in a light modulator. In this example, nano-elements and electrodes are applied to opposing surfaces of the substrate 711. The nano-elements are applied to the second surface of the substrate 711, facing away from the optical layer. The electrodes are applied to the first surface of the substrate 711, facing towards the optical layer.

[0244] In this example, a coating 751 for the patterning element is applied, but no coating is applied over the electrodes.

[0245] Figure 7e shows a schematic diagram of an example embodiment of a transparent substrate for use in a light modulator, similar to Figure 7d, except that a coating 752 for the drive electrodes is also applied to the first surface.

[0246] Figure 7f shows a schematic diagram of an example embodiment of a transparent substrate for use in a light modulator. In this example, patterned elements are applied to both surfaces of the substrate. Figure 7f shows, in that order, a first layer of nanoelements, substrate 711, a second layer of nanoelements in coating 751, and actuation electrodes in coating 752. In one embodiment, coating 751 is also applied to the second surface of the substrate.

[0247] Figure 7g shows a schematic diagram of an example embodiment of a transparent substrate for use in a light modulator. Figure 7g is similar to Figure 7f, except that no coating is applied to the electrodes. A coating 751 may further be applied to the second surface, for example, to protect the nano-elements.

[0248] In some embodiments, the protective coatings, e.g., coatings 751, 752, and / or 753, provide additional optical functions to the device. In some embodiments, this is an independent optical function. In some embodiments, this is an optical function that cooperates with the electro-optical effect of the device. These can be, for example, reflective, anti-reflective, diffusive, and / or anti-diffractive effects for all wavelengths of light or for portions of the electromagnetic spectrum, such as the UV, visible, and / or IR. The protective coating material can be selected to have a refractive index sufficiently different from that of the fluid solvent to produce significant optical refraction. For example, a protective coating made of silicon nitride, which has an optical refractive index of 3, can be combined with a fluid solvent having an optical refractive index less than 2. The refractive index difference induces refraction of incident light, changing its direction according to Snell's law. The optical modulator can then direct the incident light in a specific, designed direction. This effect, combined with the specific shape and topography of the patterned protective coating, can refract light in multiple directions, thus increasing optical diffusion or haze. Similarly, different protective coatings from the same or different substrates are possible to enhance specific light paths or diffusion.

[0249] For more information on coatings, for example to protect electrodes, reference is made to PCT / EP2022 / 066713 of the same applicant, but similar coatings can be applied to nano-elements.

[0250] Depending on the material or combination of materials chosen, the protective coating may 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 coating, dip coating, spray coating, inkjet printing, slit coating, and combinations thereof.

[0251] 8a illustrates, in a simplified manner, an example embodiment of a method 810 for manufacturing a substrate, as in one embodiment. - providing a substrate 811; - applying 812 drive electrodes to a first surface of the substrate to position the substrate for the light modulator; - applying 813 a patterning element to a surface of a substrate, including disposing a substrate having a metasurface, where the surface to which the patterning element is applied can be the first surface or a second surface of the substrate opposite the first surface. Applying 812 and 813 can be performed simultaneously. Applying 813 can be performed before applying 812.

[0252] 8b shows a schematic diagram of an example embodiment of a method 820 for fabricating an optical modulator, as in one embodiment. The method 820 includes: - Providing 821 a first substrate and a second substrate according to one embodiment, for example according to method 810. The second substrate may or may not have electrodes and / or patterned elements applied to the second substrate. - applying an optical layer between the first and second substrates 822; - Sealing the faces of the first substrate and the second substrate.

[0253] 8c illustrates, in a simplified manner, an example embodiment of a method 830 for operating an optical modulator, as in one embodiment. The method 830 includes: applying 831 an electric potential to the driving electrodes to modulate the electromagnetic field in the optical layer, providing electrophoresis and / or dielectrophoresis of particles in the optical layer and modulating light passing through the substrate; - modifying the phase, amplitude, and / or polarization of light passing through the substrate by patterning elements applied to the surface of the substrate 832;

[0254] The patterning element may optionally include a phase change material having an optical distortion that depends on an external factor, for example, temperature, pressure, and / or an electric field. Method 830 may optionally further include modulating the external factor to modulate the optical distortion.

[0255] The following list of numbered clauses are examples and each is contemplated as an example of an embodiment.

[0256] substrate Clause 1. A transparent substrate for use in an optical modulator, comprising: - a substrate comprising at least one actuation electrode (111-114, 121-124) applied to a first surface of the substrate, the actuation electrodes being arranged in a pattern across the substrate, the electrodes being arranged to receive an electrical potential resulting in modulation of the optical properties of the light modulator, and micro- and / or nano-patterned elements being applied to the surface of the substrate and modifying the phase, amplitude, and / or polarization of light interacting with the substrate.

[0257] Article 2. - the patterned elements have a maximum diameter in a two-dimensional cross section parallel to the substrate of the nanoelement, the diameter being at most 2 micrometers, at most 1 micrometer, or at most 500 nanometers; and / or the minimum distance between two patterning elements is at most 2 micrometers, at most 1 micrometer, or at most 500 nanometers; and / or The substrate of clause 1, wherein the minimum distance between two patterned elements is at least 100 nanometers, 200 nanometers, or 400 nanometers.

[0258] Clause 3. The substrate of clause 1 or 2, wherein the patterned elements form a metasurface.

[0259] Clause 3.1. The substrate of any one of clauses 1 to 3, wherein the patterned elements on the substrate have a plurality of different sizes, different shapes, and / or different materials.

[0260] Clause 4. The substrate of any one of clauses 1 to 3.1, wherein the patterning elements extend from the surface and have a height of less than 1000 nanometers, preferably between 100 and 1000 nanometers.

[0261] Clause 5. The substrate of any one of clauses 1 to 4, wherein the patterning element is applied to a first substrate and / or the patterning element is applied to a second substrate opposite the first substrate.

[0262] Clause 6. The substrate of any one of clauses 1 to 5, wherein the patterning element is configured to compensate for optical artifacts of the light modulator.

[0263] Clause 7. The substrate of clause 6, wherein the optical artifact is any one of diffraction, refraction, light scattering, and perturbation of light as it passes through or is reflected from the substrate.

[0264] Clause 8. A substrate according to any one of clauses 1 to 7, wherein the patterning elements are configured to produce an inverse diffraction effect compared to the diffraction effect produced by the drive electrodes of the modulator.

[0265] Clause 9. The substrate of any one of clauses 1 to 8, wherein the patterning element provides optical wavelength control to filter light passing through the substrate according to wavelength.

[0266] Clause 10. The substrate of any one of clauses 1 to 9, wherein the patterning element modifies the wavefront of light passing through the substrate to generate a holographic image.

[0267] Clause 11. The substrate of any one of clauses 1 to 10, wherein the patterning element modifies the wavefront of light reflected through the substrate to compensate for optical aberrations produced by the drive electrodes.

[0268] Clause 12. The substrate of any one of clauses 1 to 11, wherein the patterning element provides light polarization control to manipulate linearly or circularly polarized light.

[0269] Clause 12.1. A substrate according to any one of clauses 1 to 12, wherein the patterning element is passive, e.g., not controllable by an external factor, or active, e.g., controllable by an external factor.

[0270] Clause 13. The substrate of any one of clauses 1 to 12.1, wherein the patterning elements comprise controllably shaped elements configured to provide control over altering the phase, amplitude, and / or polarization of light interacting with the substrate.

[0271] Clause 14. A substrate according to any one of clauses 1 to 13, wherein the light modulator is configured for use within a defined spectral range and the patterning element has a total transmittance within the spectral range of at most 10%.

[0272] Clause 15. The substrate of any one of clauses 1 to 14, wherein the patterning element comprises a phase change material having an optical distortion that depends on an external factor, for example, temperature, pressure, and / or electric field.

[0273] Clause 16. A substrate for use in an optical modulator according to any one of clauses 1 to 15, wherein the pattern of drive electrodes across the substrate comprises a plurality of repeating building blocks.

[0274] Article 15. - the building blocks repeat across the substrate in at least two directions, and / or - A substrate according to any one of clauses 1 to 16, wherein a plurality of different building blocks repeats across the substrate in one or two directions.

[0275] Clause 16. At least one drive bus is disposed on the substrate for each drive electrode of the at least one drive electrode; - at least one drive bus is disposed on the surface of the substrate for each drive electrode to drive the drive electrode; and / or - the drive bus is only located on the surface of the substrate; and / or - The substrate according to any one of clauses 1 to 15, wherein the drive buses are arranged between the building blocks covering the substrate.

[0276] Clause 17. The substrate of any one of clauses 1 to 16, wherein the substrate is non-rectangular.

[0277] Clause 18. A substrate for use in an optical modulator according to any one of clauses 1 to 17, wherein at least one drive electrode comprises a plurality of drive electrodes; - a substrate, wherein the plurality of drive electrodes (111-114, 121-124) are interdigitated, each of the plurality of drive electrodes being arranged in a pattern across the substrate, the plurality of interdigitated drive electrodes being arranged in an alternating manner relative to one another on the substrate, and the pattern of the plurality of drive electrodes across the substrate comprising a plurality of repeating building blocks.

[0278] Article 19. Building blocks - A substrate for use in an optical modulator according to clause 18, comprising a plurality of interdigitated electrodes extending in at least two directions across the building block, an interdigitated electrode in a building block forming a drive electrode for at least one electrode in the plurality of interdigitated electrodes in the building block, and the maximum length between any two points on said electrodes measured along said electrodes in a building block is at least twice the length of a diagonal of a building block unit.

[0279] Clause 20. At least one drive electrode comprises a plurality of drive electrodes; - the closest distance from any point in the substrate to the first drive electrode and the closest distance to the second drive electrode are less than a threshold value; and / or - the sum of the closest distance to the first drive electrode and the closest distance to the second drive electrode from any point in the substrate is less than a first threshold and / or greater than a second threshold; and / or - the distance from a point on the first drive electrode to a point on the second drive electrode is at least a second threshold value; and / or 20. A substrate for use in a light modulator according to any one of clauses 18 to 19, wherein the horizontal and / or vertical size of the building blocks is at least 10 times the sum of the electrode line width and the electrode distance.

[0280] Optical Modulator Clause 21. An optical modulator comprising a first substrate and a second substrate according to any one of clauses 1 to 20, wherein an optical layer extends between the first and second substrates, and wherein the optical properties of the optical modulator are modifiable by applying an electric potential to at least the drive electrodes.

[0281] Clause 22. An optical modulator comprising: a first substrate and a second substrate, at least one of which is provided with a patterning element, e.g. according to clauses 1 to 20, e.g. according to an embodiment, and at least one of which is arranged with inner faces facing each other, the first substrate being transparent, and at least one actuation electrode is applied to the inner face of the first substrate, the actuation electrode extending in a pattern across the inner face of the first substrate; an optical layer disposed between the first substrate and the second substrate, the optical layer comprising a fluid containing particles; a controller configured to apply a potential to the at least one drive electrode to obtain an electromagnetic field, providing movement of particles toward or away from the drive electrode, and resulting in modulation of an optical property of the light modulator; An optical modulator comprising:

[0282] Clause 23. The light modulator of clause 21 or 22, wherein at least one drive electrode comprises an ITO electrode.

[0283] Clause 24. An optical modulator according to any one of clauses 21 to 23, wherein the particles are charged or chargeable, and the controller is configured to apply a potential to the drive electrodes to obtain an electromagnetic field, providing electrophoretic movement of the particles towards the drive electrodes, resulting in modulation of the optical properties of the optical modulator.

[0284] Clause 24.1. An optical modulator described in any one of clauses 21 to 24, wherein a plurality of interdigitated drive electrodes are arranged across each of the inner surfaces 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, provide electrophoretic movement of particles, and result in modulation of the optical properties of the optical modulator.

[0285] Article 24.2. The optical modulator - switched to a non-transparent state by creating an AC voltage across at least one of the first and second substrates and applying an AC current between at least the first and second electrodes on the first substrate and / or the first and second electrodes on the second substrate; - an optical modulator according to any one of clauses 21 to 24.1, configured to be switched to a transparent state by creating an AC voltage between the first substrate and the second substrate and applying an AC current between a first electrode on the first substrate and a first electrode on the second substrate and / or between a second electrode on the first substrate and a second electrode on the second substrate.

[0286] Clause 24.3. An optical modulator according to clauses 21 to 24.2, wherein the electrical signal is an AC signal.

[0287] Clause 24.4. A light modulator according to any one of clauses 21 to 24.3, wherein the particles are electrically charged or chargeable and the particles move due to electrophoretic forces.

[0288] Clause 25. A light modulator according to any one of clauses 21 to 24.4, wherein the particles are electrically charged or chargeable and the particles move due to electrophoretic forces.

[0289] Clause 26. An optical modulator according to any one of clauses 21 to 25, wherein the drive electrodes are line electrodes, for example, the line electrodes extend along the vertical direction and along the horizontal direction, the extensions being at least 10 times, more preferably at least 100 times, longer in the vertical direction than the horizontal extensions, at least in localized portions of the line electrodes.

[0290] Article 27. - Transparent and non-transparent states, and / or - Has reflective and non-reflective states, 27. An optical modulator according to any one of clauses 21 to 26, wherein the optical modulator is configured to switch between states by modulating current between one or more drive electrodes applied on a first substrate and optionally one or more drive electrodes applied on a second substrate.

[0291] Article 28. - the electrical signal is provided as an alternating current (AC) at one or more electrodes, or - An optical modulator according to any one of clauses 21 to 27, wherein the electrical signal is provided as a direct current (DC) at one or more electrodes, the voltage being reversed periodically.

[0292] Clause 29. An optical modulator according to any one of clauses 21 to 28, wherein the first substrate and the second substrate are transparent.

[0293] Clause 30. An optical modulator according to any one of clauses 21 to 29, 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.

[0294] Clause 31. One or more of the electrodes comprises a plurality of interlaced mesh electrodes; - An optical modulator according to any one of clauses 21 to 30, wherein a plurality of interlaced mesh electrodes extend in a two-dimensional pattern across the first substrate and across the second substrate, and two mesh electrodes of the plurality of mesh electrodes on a substrate intersect at a plurality of intersection points spread across the substrates.

[0295] Article 32. - the particles are nanoparticles and / or microparticles, and / or - the particles are configured to absorb light; - A light modulator according to any one of clauses 21 to 31, wherein the particles are pigment particles.

[0296] Clause 33. An optical modulator according to any one of clauses 21 to 32, wherein at least two electrodes comprise an electrically conductive material having a resistivity of less than 100nΩm at 273K.

[0297] Clause 34. A light modulator according to any one of clauses 21 to 33, wherein the electrodes are in fluid contact with the fluid or the electrodes are separated from the fluid, for example by a coating.

[0298] Clause 35. An optical modulator according to any one of clauses 21 to 34, wherein the electrodes applied to the substrate cover 1-30% of the substrate surface.

[0299] Clause 36. An optical modulator according to any one of clauses 21 to 35, wherein the potential operates at an AC frequency of 10-100 Hz to switch to the transparent state and / or at an AC frequency of less than 1 Hz to switch to the non-transparent state.

[0300] Clause 37. A light modulator according to any one of clauses 21 to 36, wherein the size of the nanoparticles is 10-1000 nm, preferably 100-500 nm.

[0301] Clause 38. An optical modulator according to any one of clauses 21 to 37, wherein the particles are configured to absorb light having a wavelength of 10 nm-1 micron.

[0302] Clause 39. An optical modulator according to any one of clauses 21 to 38, wherein the distance between the first substrate and the second substrate is less than 500 μm.

[0303] Clause 40. An optical modulator according to any one of clauses 21 to 39, wherein the dynamic viscosity of the fluid is 500 mPa.s or less.

[0304] Clause 41. The fluid has a relative dielectric constant ε less than 100. r 41. The optical modulator of any one of clauses 21 to 40, comprising:

[0305] method Clause 42. A method for modulating light, comprising: - applying an electric potential to one or more drive electrodes applied to one or two opposing substrates, thereby obtaining an electromagnetic field between the drive electrodes and providing electrophoretic movement of particles towards or away from one drive electrode of the plurality of drive electrodes, resulting in modulation of light shining through the substrates, wherein at least one or both of the two opposing substrates are as defined in any one of the preceding claims.

[0306] Clause 43. A method of modulating light according to clause 42, comprising using an alternating current having two phases, with a potential between -220V and +220V and a current between -100µA and +100µA.

[0307] Clause 44. A transitory or non-transitory computer-readable medium containing data representing instructions that, when executed by a processor system, cause the processor system to perform the method described in clause 42 or 43.

[0308] FIG. 9a illustrates a computer-readable medium 1000 having a writable portion 1010 containing a computer program 1020, and a computer-readable medium 1001 having a writable portion containing a computer program. The computer program 1020, according to one embodiment, includes instructions for causing a processor system to operate a light modulator. For example, the processor system may be connected to a light modulator panel. The computer program 1020 may be embodied as a physical mark on the computer-readable medium 1000 or by magnetization of the computer-readable medium 1000. However, other suitable embodiments are contemplated. Furthermore, while the computer-readable medium 1000 is illustrated here as an optical disk, it will be appreciated that the computer-readable medium 1000 may be any suitable computer-readable medium, such as a hard disk, solid-state memory, flash memory, or the like, and may be non-recordable or recordable. The computer program 1020 includes instructions for causing a processor system to perform the light modulator method.

[0309] FIG. 9b shows a schematic diagram of a processor system 1140 according to an embodiment of a controller for an optical modulator. The processor system includes one or more integrated circuits 1110. The architecture of the one or more integrated circuits 1110 is shown schematically in FIG. 9b. The circuit 1110 includes a processing unit 1120, e.g., a CPU, for executing computer program components for performing methods according to embodiments and / or implementing modules or units thereof. The circuit 1110 includes a memory 1122 for storing programming code, data, etc. A portion of the memory 1122 may be read-only. The circuit 1110 may include a communication element 1126, e.g., an antenna, a connector, or both, and the like. The circuit 1110 may include a dedicated integrated circuit 1124 for performing some or all of the processing defined in the methods. The processor 1120, the memory 1122, the dedicated 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 configured for contact and / or contactless communication using an antenna and / or connector, respectively.

[0310] For example, in an embodiment, the processor system 1140, e.g., a device, may include a processor circuit and a memory circuit, where the processor is configured to execute software stored in the memory circuit. For example, the processor circuit may be an Intel Core i7 processor, an ARM Cortex-R8, or the like. In an embodiment, the processor circuit may be an ARM Cortex M0. The memory circuit may be a ROM circuit or a non-volatile memory, e.g., a flash memory. The memory circuit may be a volatile memory, e.g., an SRAM memory. In the latter case, the device may include a non-volatile software interface, e.g., a hard drive, a network interface, or the like, configured to provide the software.

[0311] For example, a controller for a light modulator for controlling the voltages applied to the electrodes may comprise a processor circuit, but may also or alternatively comprise a state machine.

[0312] It should be noted that the above-described embodiments illustrate rather than limit the subject matter disclosed herein, and that those skilled in the art will be able to design many alternative embodiments.

[0313] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. When preceding a list of elements, phrases such as "at least one of" refer to the selection of all or any subset of the elements from the list. For example, the phrase "at least one of A, B, and C" should be understood as including A only, B only, C only, both A and B, both A and C, both B and C, or all of A, B, and C. The presently disclosed subject matter may be implemented by hardware comprising several distinct elements and by a suitably programmed computer. In a device claim enumerating several parts, several of these parts may be embodied by one and the same item of hardware. 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.

[0314] In the claims, references in parentheses refer to reference signs in the drawings that illustrate the embodiments or to formulas of the embodiments, and thus enhance the comprehension of the claims. These references shall not be construed as limiting the claims.

[0315] Explanation of Reference Symbols The following list of references and abbreviations is provided to facilitate interpretation of the drawings and shall not be construed as limiting the claims. [Explanation of symbols]

[0316] 10 Optical Modulator 11 First substrate 12 Second board 13, 13a, 13b electrode 14, 14a, 14b electrode 15 Fluid 16 Controllers 30 particles 20 cars 21 Optical Modulator 40 Optical Modulator 41 First substrate 42 Second board 43 Third Board 46 Controller 100-102 PCB 111-114 Main Line 121-124 Main Line 131-134 Interdigitated electrodes 140 Building Blocks 141-144 Building Blocks 110, 120 Drive Bus 110', 120' drive bus 119, 129 Connection Zone 191, 192 direction 203-204 PCB 211-222 Building Blocks 251-262 Building Blocks 501, 502 Optical modulator 511, 512 Transparent substrate 521, 522 Drive electrodes 523 particles 524 Optical layer 531 Spacer 541, 542, 543, 544 Patterned elements 601, 602 board 611,612 Drive electrode 621, 622 Patterned elements 631 Virtual Cutting Line 632 Virtual scale, 1 micrometer 642 Primary Wavefront 643 Optical Modulator 644 Distorted Wavefront 645 Drive Electrode 653 Optical Modulator 654 corrected wavefront 655 Patterned Elements 661 height 662 diameter 663 Object Distance 711 Transparent substrate 712 Optical layer surface 721 Drive Electrode 745, 746 Patterned layer 751, 752, 753 Coating 1000, 1001 Computer-readable medium 1010 Writable area 1020 Computer Program 1110 Integrated Circuit(s) 1120 Processing Unit 1122 memory 1124 dedicated integrated circuits 1126 Communication Elements 1130 Interconnect 1140 Processor System

Claims

1. 1. A transparent substrate for use in an optical modulator, comprising: - a substrate comprising at least one drive electrode (111-114, 121-124) applied to a first surface of the substrate, the drive electrodes being arranged in a pattern across the substrate, the electrodes being arranged to receive an electrical potential and resulting in modulation of the optical properties of the light modulator, nano- and / or micro-patterned elements being applied to the surface of the substrate and modifying the phase, amplitude and / or polarization of light interacting with the substrate, the patterned elements being arranged to compensate for optical artifacts of the light modulator introduced by the drive electrodes.

2. the patterning elements have a maximum diameter in a two-dimensional cross section parallel to the substrate, the diameter being at most 10 micrometers, at most 2 micrometers, at most 1 micrometer, or at most 500 nanometers; and / or the minimum distance between two patterning elements is at most 2 micrometers, at most 1 micrometer, at most 500 nanometers, and / or the minimum distance between two patterning elements is at least 10 nanometers, at least 50 nanometers, at least 100 nanometers, 200 nanometers, or 400 nanometers; - The substrate of claim 1, wherein the patterning element has at least two non-contiguous edges, and the shortest distance between two points on each of the non-contiguous edges is at most 2 micrometers, at most 1 micrometer, or at most 500 nanometers.

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

4. 4. The substrate of claim 1, wherein the patterning elements extend from the surface and have a maximum height in a direction perpendicular to the substrate, the height being at most 2 micrometers, at most 1 micrometer, or at most 500 nanometers, preferably between 100 nanometers and 1000 nanometers.

5. 5. The substrate of claim 1, wherein the patterning element is applied to a first substrate and / or the patterning element is applied to a second substrate opposite the first substrate.

6. 6. The substrate of claim 1, wherein the optical artifact is any one of diffraction, refraction, light scattering, and perturbation of light as it passes through or is reflected from the substrate.

7. A substrate according to any preceding claim, wherein the patterning elements are configured to produce an inverse diffraction effect compared to the diffraction effect produced by the drive electrodes of the modulator.

8. 8. The substrate of claim 1, wherein the patterning element provides optical wavelength control to filter light passing through the substrate according to wavelength.

9. 9. The substrate of claim 1, wherein the patterning element modifies a wavefront of light passing through the substrate to generate a holographic image.

10. 10. The substrate of claim 1, wherein the patterning element modifies a wavefront of light reflected through the substrate to compensate for optical aberrations produced by the drive electrodes.

11. The substrate of claim 1 , wherein the patterning element provides light polarization control to manipulate linearly or circularly polarized light.

12. 12. The substrate of claim 1 , wherein the patterning elements comprise controllably shaped elements configured to provide control over altering the phase, amplitude, and / or polarization of light interacting with the substrate.

13. 13. The substrate of claim 1, wherein the light modulator is configured for use within a defined spectral range and the patterning element has a total transmittance within the spectral range of at most 10%.

14. 14. The substrate of claim 1, wherein the patterning element comprises a phase change material having an optical distortion that depends on an external factor, for example temperature, pressure, and / or an electric field.

15. 15. The substrate of claim 1, wherein the patterning element on the substrate comprises a transparent, electrically conductive patterning element, the patterning element configured to receive an electrical potential to provide control over optical modulation in the light modulator.

16. The substrate of claim 15 , wherein the patterning elements are configured to interact with particles in an optical layer of a light modulator.

17. 17. The substrate of claim 15 or 16, wherein the patterning elements are individually electrically addressable.

18. The substrate of claim 17 , wherein the patterning elements are applied to the first surface in a regular grid that covers at least a portion of the first surface.

19. A method for manufacturing a substrate according to any one of claims 1 to 18, comprising the steps of: - providing a substrate; applying a drive electrode to a first surface of the substrate; - applying a patterning element to the surface of the substrate; A method comprising:

20. 19. An optical modulator comprising a first substrate according to any one of claims 1 to 18, a second substrate, and an optical layer extending between the first and second substrates, wherein the optical properties of the optical modulator are modifiable by applying an electric potential to at least the drive electrodes.

21. 21. The light modulator of claim 20, wherein the optical layer comprises charged particles, the patterning elements on the first substrate comprise transparent, electrically conductive patterning elements, and the light modulator is configured to apply an electric potential to the conductive patterning elements to align the charged particles to the conductive patterning elements, thus modulating the optical properties of the patterning elements.

22. 22. The light modulator of claim 20, wherein the patterning element is configured to focus light incident on the first substrate within the optical layer.

23. 23. A method for calibrating an optical modulator according to any one of claims 20 to 22, comprising the steps of: - providing an optical modulator; obtaining information about the distortion and / or transparency of the light modulator from an image sensor observing the light modulator; deriving control signals for controlling the optical modulator in the operating phase; A method comprising:

24. - Obtaining information about the orientation of the optical modulator from an orientation sensor applied to the optical modulator.

24. The method of claim 23, further comprising:

25. 23. A method of controlling an optical modulator, the optical modulator being an optical modulator according to any one of claims 20 to 22, comprising applying an electric potential to the drive electrodes to modulate an electromagnetic field in the optical layer, providing electrophoresis and / or dielectrophoresis of particles in the optical layer, and modulating light passing through the substrate, wherein the phase, amplitude, and / or polarization of the light passing through the substrate is further modified by patterned elements applied to the surface of the substrate.

26. 26. A method of controlling an optical modulator according to claim 25, wherein the patterning element comprises a phase change material having an optical distortion that depends on an external factor, such as temperature, pressure, and / or an electric field, and / or the patterning element is conductive and has an optical distortion that depends on an external factor including an electric potential, and the method comprises modulating the external factor to modulate the optical distortion.

27. A transitory or non-transitory 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 described in claims 23 to 26.

Images