WO2022037151A1 - 空间光调制器和波长选择开关 - Google Patents

空间光调制器和波长选择开关 Download PDF

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Publication number
WO2022037151A1
WO2022037151A1 PCT/CN2021/095241 CN2021095241W WO2022037151A1 WO 2022037151 A1 WO2022037151 A1 WO 2022037151A1 CN 2021095241 W CN2021095241 W CN 2021095241W WO 2022037151 A1 WO2022037151 A1 WO 2022037151A1
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WIPO (PCT)
Prior art keywords
electrode
spatial light
electrodes
layer
light modulator
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PCT/CN2021/095241
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English (en)
French (fr)
Inventor
李腾浩
韩荦
向晖
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华为技术有限公司
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Priority to EP21857252.7A priority Critical patent/EP4191327A4/en
Publication of WO2022037151A1 publication Critical patent/WO2022037151A1/zh
Priority to US18/171,160 priority patent/US20230194909A1/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
    • G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
    • G02B6/29302—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means based on birefringence or polarisation, e.g. wavelength dependent birefringence, polarisation interferometers
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/0102—Constructional details, not otherwise provided for in this subclass
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/0121—Operation of devices; Circuit arrangements, not otherwise provided for in this subclass
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/03—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on ceramics or electro-optical crystals, e.g. exhibiting Pockels effect or Kerr effect
    • G02F1/0305—Constructional arrangements
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/03—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on ceramics or electro-optical crystals, e.g. exhibiting Pockels effect or Kerr effect
    • G02F1/0305—Constructional arrangements
    • G02F1/0316—Electrodes
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/03—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on ceramics or electro-optical crystals, e.g. exhibiting Pockels effect or Kerr effect
    • G02F1/0327—Operation of the cell; Circuit arrangements
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/061—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on electro-optical organic material
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2201/00—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00
    • G02F2201/12—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00 electrode
    • G02F2201/122—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00 electrode having a particular pattern
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2201/00—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00
    • G02F2201/12—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00 electrode
    • G02F2201/124—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00 electrode interdigital
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2203/00—Function characteristic
    • G02F2203/12—Function characteristic spatial light modulator
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2203/00—Function characteristic
    • G02F2203/50—Phase-only modulation

Definitions

  • the present application relates to the field of optical communication, in particular to a spatial light modulator and a wavelength selective switch.
  • Optical networks are continuing to evolve in the direction of large capacity, low latency, and intelligence.
  • Optical switching technologies such as ROADM (Reconfigurable Optical Add-Drop Multiplexer, Reconfigurable Optical Add-Drop Multiplexer) and OXC (Optical Cross-Connect, Optical Cross-Connect) not only support the current commercial optical network, but also realize the next generation One of the key technologies of optical network.
  • WSS Widelength selective switch, wavelength selective switch
  • Embodiments of the present application provide a spatial light modulator and a wavelength selective switch, which can achieve low insertion loss, high-efficiency light conversion and increase the duty ratio at the same time.
  • a spatial light modulator including a backplane, a phase adjustment unit, electrodes, and an electrical connection portion.
  • the backplane is equipped with a drive circuit.
  • the phase adjustment unit includes a lower cavity mirror, a cavity layer and an upper cavity mirror which are sequentially stacked on the back plate, and the lower cavity mirror is located between the cavity layer and the back plate.
  • the electrodes include a first electrode and a second electrode which are insulated from each other, the electrodes are located inside or on the surface of the phase adjustment unit, and are located on the side of the lower cavity mirror away from the back plate.
  • the electrodes and the phase adjustment unit form an integrated structure, and the electrodes are fabricated inside or on the surface of the phase adjustment unit during the process of manufacturing the phase adjustment unit, or the application can be used in the phase adjustment unit that has already been fabricated. Electrodes are provided on the surface.
  • the electrical connection part electrically connects the electrode and the drive circuit to form a drive electric field between the first electrode and the second electrode, adjust the refractive index of the phase adjustment unit, and then adjust the phase of the optical signal. modulation.
  • the electrodes are formed on the phase adjustment unit and located on the side of the lower cavity mirror away from the back plate, so that the electrodes and the phase adjustment unit are integrated into one body, that is, the arrangement of the electrodes does not occupy the space of the back plate around the phase adjustment unit, It is beneficial to improve the duty ratio of the spatial light modulator and save the space of the backplane.
  • the electrodes and the phase correction unit are usually arranged on the backplane separately, the electrodes are located around the phase correction unit, and the electrodes occupy the area around the phase adjustment unit on the backplane, which not only makes the spatial light
  • the modulator occupies a larger area of the backplane.
  • the driving electric field formed by the electrodes can only have a partial electric field acting on the phase correction unit, and part of the electric field is in the peripheral space of the phase correction unit and cannot act on the phase correction unit, so the voltage loaded on the electrodes needs to be greater than the phase correction unit. Adjusting the driving voltage required by the unit is not conducive to energy saving, and the driving efficiency is low.
  • the electrodes are directly fabricated on the phase adjustment unit, and the counter electrode only needs to be loaded with the driving voltage required by the phase adjustment unit, without the need for a large driving voltage, and has the advantages of small insertion loss, low power, and high-efficiency conversion.
  • the driving circuit, the phase adjusting unit, the electrode and the connecting portion together form a pixel unit
  • the spatial light modulator includes a plurality of the pixel units, and a plurality of The pixel units are distributed in an array, and the phase adjustment units of the adjacent pixel units are seamlessly connected.
  • a plurality of pixel units are closely arranged next to each other on the backplane, and the structure of the seamless connection between the phase adjustment units of the adjacent pixel units makes the spatial light modulator easy to achieve miniaturization
  • the seamless connection structure between adjacent phase adjustment units is also conducive to production. During the production process, the phase adjustment units of multiple pixel units distributed in the array are fabricated at the same time, and no phase adjustment is required after fabrication. Channels are dug between adjacent phase adjustment units, so that the manufacturing cost is low and the yield is high.
  • the phase adjustment unit in the spatial light modulator provided by the present application has a solid layer structure.
  • the phase adjustment unit is similar to an asymmetric FP (Fabry-Perot, Fabry-Perot) microcavity structure
  • the lower cavity mirror, the cavity layer and the upper cavity mirror of the phase adjustment unit also have a multi-layer structure (or film structure).
  • the lower cavity mirror is a reflective layer composed of a multi-layer structure (or a film structure) or a metal reflective layer, and its reflectivity is close to or equal to 1, and the corresponding layer structures between different pixels can be connected to the same layer.
  • a large-area reflective layer can be directly made, which can cover multiple pixel units distributed in an array, and the area corresponding to each pixel unit is the lower part of the pixel unit.
  • the materials of the cavity layer and the upper cavity mirror are materials with electro-optic effect, such as BTO (BaTiO3, Barium titanate, barium titanate), Si (silicon, such as Si nanomaterials), and the response rate of such materials is in the order of GHz.
  • phase adjustment unit of the FP microcavity structure In order to form the asymmetric structure of the phase adjustment unit of the FP microcavity structure, it can be formed by fabricating Si nanowires, nanometer micropillars and other structures on the surface of the upper cavity mirror, whereby the phase adjustment unit provided in this application can realize the optical signal The wavefront amplitude changes close to 0 for phase modulation.
  • the spatial light modulation unit provided by the present application can perform pure phase modulation on the optical signal without changing the light intensity.
  • the phase adjustment unit can be divided into a main area and an edge area.
  • the edge area is located at the periphery of the main area and surrounds the main area.
  • the main area is equivalent to the functional area of the phase adjustment unit.
  • the electrodes are arranged in the main area, and the electrical connection can be located in the edge area. .
  • the phase adjustment unit provided by the present application has an integrated structure, and the division of the main body area and the edge area does not mean that the phase adjustment unit can be divided into two parts.
  • the main body area is the area where the electrodes are arranged, which can be understood as The arrangement of electrodes cannot cover all areas of the phase adjusting unit, but the edge area should be reserved, that is, no electrodes are arranged in the edge area, but electrical connection parts can be arranged in the edge area.
  • the generated driving electric field is also located in the main body area, so only the refractive index of the main body area is changed, and the main body area adjusts the phase of the optical signal, while the edge area does not generate a driving electric field for the optical signal. influence.
  • the main regions of adjacent pixel units are separated by edge regions, so that the phase adjustment of the optical signal between adjacent pixel units will not cause crosstalk.
  • the electrodes may not only be arranged in the main body area, but also extend to the edge area.
  • the electrodes can only generate a driving electric field in the main body area when the electrodes are energized, which can also ensure the phase difference.
  • the driving electric field between adjacent pixel units is isolated, so that the phase adjustment of the optical signal between adjacent pixel units will not generate crosstalk.
  • the electrodes are made of light-transmitting material, so that the electrodes are arranged in the main body area without affecting the light transmittance of the main body area.
  • the electrodes may be in the form of nanowires.
  • the materials of the electrodes may be: doped Si.
  • the first electrode and the second electrode are integrated with the phase adjustment unit, and it can be understood that the first electrode and the second electrode are formed on the cavity layer of the phase adjustment unit and a certain layer structure of the upper cavity mirror.
  • the first electrode and the second electrode can obtain Si nanowires (the first electrode and the second electrode) by doping Si process and etching process in the process of fabricating the cavity layer and a certain layer structure of the upper cavity.
  • One of the first electrode and the second electrode is electrically connected to the reference voltage of the driving circuit, and the other is grounded, so that when a voltage is applied, a driving electric field is formed.
  • the material of the electrical connection part can be an opaque material, such as a metal material, the electrical connection part is arranged in the edge area, and the electrical connection part is an opaque material and will not affect the light transmittance of the phase adjustment unit.
  • the electrical connection portion may include a first electrical connection portion and a second electrical connection portion, the first electrical connection portion is electrically connected between the first electrode and the drive circuit, and the second electrical connection portion is electrically connected between the second electrode and the drive circuit .
  • the connection portion includes a pad and a conductive portion electrically connected between the pad and the driving circuit, the pad and the electrode may be located in the same layer structure, and the conductive portion may be in the form of a via lead.
  • a via hole can be formed between the layer structure where the pad is located and the backplane, and a metal wire or metal conductive column can be arranged in the via hole, or formed on the inner wall of the via hole by electroplating.
  • the metal layer constitutes the conduction part.
  • the electrodes are arranged on the first surface, that is, the first electrode and the second electrode are arranged coplanarly.
  • the phase adjusting unit includes a plurality of layer structures arranged in sequence, and the first surface is a surface of one of the layer structures.
  • the first surface may be a surface of the upper cavity mirror facing away from the cavity layer.
  • the lower cavity mirror, the cavity layer and the upper cavity mirror can all be a structure in which one or more layer structures are stacked in sequence. As long as the first surface is not arranged in the lower cavity mirror, it can be located in a certain layer structure of the cavity layer. , or a certain layer structure of the upper cavity mirror, or a layer structure between the cavity layer and the upper cavity mirror, or a layer structure on the side of the upper cavity mirror away from the cavity layer.
  • the electrodes are in an interdigitated electrode structure, specifically: the first electrode includes a first main line and at least two first branches extending from one side of the first main line, the first The second electrode includes a second main line and at least two second branches extending from one side of the second main line, the first main line and the second main line are arranged oppositely, the first branch and the second main line The two branches form an interdigitated structure.
  • the first branch and the second branch are linear.
  • the first branch and the second branch can be arranged in parallel and are both perpendicular to the first main line or the second main line.
  • the first branch and the second branch can also form an included angle with the first main line and the second main line.
  • the included angle is 90 degrees, it is the aforementioned vertical state, and the included angle can also be less than 90 degrees, such as 60 degrees, 75 degrees. degree, etc., which are not limited in this application.
  • the first branch and the second branch are in a curved shape, and their shapes may specifically be an S-shape, a C-shape, an arc shape, or other irregular curved shapes.
  • the electrical connection part includes a first connection part and a second connection part which are insulated and isolated from each other, the first connection part is connected to the first main line, and the second connection part is connected to the The second main line, the first connection part and the second connection part are arranged on opposite sides of the electrode.
  • the first connection part and the second connection part are located at the edge area of the phase adjustment unit, and the first connection part and the second connection head can be made of opaque materials, such as metal materials, and the opaque materials have cost Low advantage
  • the electrical connection part is arranged in the edge area, the edge area is the isolation area of the main body area between adjacent phase adjustment units, the electrodes do not form a driving electric field in this area, so the edge area does not need to transmit light, you can Light-tight electrical connections are provided in the edge region. In this way, the light transmittance of the main body region of the phase adjustment unit is ensured, the light transmittance is improved, and the low cost of the spatial light modulator can be realized.
  • the first electrode and the second electrode extend side by side from a first position on the first surface to a second position on the first surface synchronously. Insulation arrangement between the two electrodes.
  • the first electrode and the path in which the first electrode extends are in a zigzag shape, a serpentine shape or a spiral shape.
  • the path extended by the first electrode and the second electrode includes a plurality of continuous straight line segments, or a continuous curve.
  • both the first connection part and the second connection part of the electrical connection part can be located at the first position, and the first position is located at the position of the outer edge of the electrode.
  • the first position is located at the edge region of the phase adjustment unit.
  • the electrical connection portion may also be arranged at the second position; or the first electrical connection portion and the second electrical connection portion may be arranged at the first position and the second position, respectively. If the second position is set in the main body area of the phase adjusting unit, in order not to affect the light transmittance, the electrical connection part at the second position may be made of light-transmitting material.
  • the lower cavity mirror, the cavity layer, and the upper cavity mirror are sequentially stacked along a first direction
  • the first direction can be understood as a direction perpendicular to the back plate
  • the first electrode and the second electrode are alternately stacked in the first direction, that is, in this embodiment, the first electrode and the second electrode are not located in the same layer (referring to the same layer of the phase adjustment unit), but are formed in different layers of the phase adjustment unit.
  • each of the first electrode and the second electrode is a film layer structure, and is distributed in a certain layer of the cavity layer in a planar shape, or a certain layer of the upper cavity mirror.
  • Different electrodes are located in different layers, and adjacent electrodes are separated by an insulating layer, and the insulating layer is a certain layer of the phase adjusting unit, which can be an electro-optic medium.
  • the first electrodes and the second electrodes are alternately stacked, that is, the second electrode is arranged in the layer structure adjacent to one of the first electrodes, and the first electrode is arranged in the layer structure adjacent to one of the second electrodes. , one of the first electrodes can be sandwiched between two adjacent second electrodes.
  • the electrodes are located in the cavity layer.
  • the advantage of making the electrodes in the cavity layer is that the fabrication process is relatively simple, because the cavity layer is a single material, regardless of whether the transmittance or reflectivity is generated.
  • the transmittance is controlled by the material itself, not by
  • the electrode changes the structure of the cavity layer, it has little effect on the transmittance, because the transmittance is controlled by the material.
  • the electrode is located in the upper cavity mirror, and the principle of making the electrode in the upper cavity mirror is the same as the principle of making the electrode in the cavity layer.
  • the upper cavity mirror mainly forms an asymmetric structure, and the asymmetric structure is mainly formed on the top of the upper cavity mirror, that is, the surface of the upper cavity mirror facing away from the cavity layer.
  • some electrodes are located on the cavity layer, and some electrodes are located on the upper cavity mirror.
  • the specific structure of the electrical connection part may be: the electrical connection part includes a first connection part and a second connection part which are insulated and isolated from each other, the first electrode and the second electrode partially overlapped, a portion of the first electrode that does not overlap with the second electrode is connected to the first connecting portion, and a portion of the second electrode that does not overlap the first electrode is connected to the second connecting portion .
  • the number of the first electrodes is two or more, and the number of the second electrodes is two or more. Since an electric field will be generated when the first electrode and the second electrode are energized, if the number of electrodes is set to two or more, a small voltage can be used to generate the required electric field.
  • the number of the first electrode or the second electrode can be controlled to 2-3 layers, because if the number of layers is too large, for example, more than 3 layers, it is difficult to realize from the manufacturing point of view. Therefore, the maximum number of layers of electrodes is 6 layers, of which the first electrode is 3 layers, and the second electrode is 6 layers.
  • each layer of electrodes may include the following steps:
  • an electrode layer is formed on the surface of a certain layer of the phase adjustment unit by sputtering, and the material of the electrode layer can be doped silicon;
  • Photolithography process coating a photoresist layer on the electrode layer, and forming the photoresist layer into a preset pattern through the photolithography process;
  • the patterned electrodes are planarized, which can be realized by polishing, such as chemical mechanical polishing.
  • the number of layers of the first electrode and the second electrode is not necessarily the same, for example: in a possible implementation, the electrode includes one layer of the first electrode and two layers of the second electrode, or two layers of the second electrode and three layers of the first electrode .
  • the number of the first electrode and the second electrode can also be the same, for example, the number of the first electrode is one, and the number of the second electrode is one. Also one.
  • the number of the first electrode and the second electrode may also be two or more, and the number of the corresponding electrical connection parts may also increase accordingly.
  • the number of the first electrodes and the number of the second electrodes may also be different, for example, one first electrode and two second electrodes form an electrode structure.
  • the surface of the phase adjustment unit away from the back plate is provided with a protruding structure, that is, the protruding structure is formed on the topmost layer of the upper cavity mirror (that is, the layer of the upper cavity mirror away from the cavity layer), and also It can be understood that the protruding structure is located on the side of the upper cavity mirror away from the cavity layer, that is, the protruding structure is a structure independent of the upper cavity mirror.
  • the arrangement of the protruding structures enables the phase adjustment unit to form an asymmetric structure for suppressing the modulation of the intensity of the optical signal, so that the spatial light modulator provided by the present application is inclined to pure phase modulation.
  • the electrode is disposed on the surface of the upper cavity mirror away from the cavity layer, and the surface of the electrode is provided with a plurality of micro-column structures, and the micro-column structures are used to suppress the optical signal.
  • the intensity modulation of makes the spatial light modulator provided by this application tend to be purely phase-modulated.
  • the electrode is disposed on the surface of the upper cavity mirror facing away from the cavity layer, and an electro-optic medium is disposed between the first electrode and the second electrode, or the first An electro-optic medium is arranged between the electrode and the second electrode and on the periphery of the electrode.
  • electrodes are arranged on the surface of the upper cavity mirror away from the cavity layer.
  • the present application provides a wavelength selective switch, comprising an optical fiber array, a main lens, and the spatial light modulator described in any possible implementation manner of the first aspect, and the light beam found by the optical fiber array passes through the main lens Then, it is converted into collimated light, and the collimated light enters the spatial light modulator.
  • the spatial light collimator is used to reflect and deflect the collimated light to form reflected light, and the reflected light passes through the main light. Lenses are focused to the fiber array.
  • FIG. 1 is a schematic diagram of an optical switching node networking system
  • FIG. 2 is a schematic diagram of a wavelength selective switch provided by an embodiment of the present application.
  • FIG. 3 is a cross-sectional view of a backplane of a spatial light modulator provided by an embodiment of the present application
  • FIG. 4 is a plan view of a backplane of a spatial light modulator provided by an embodiment of the present application.
  • FIG. 5 is a cross-sectional view of a spatial light modulator provided by an embodiment of the present application.
  • FIG. 6 is a plan view of a spatial light modulator provided by an embodiment of the present application.
  • FIG. 7 is a schematic diagram of a spatial light modulator provided by an embodiment of the present application, which includes three phase adjustment units;
  • phase adjustment unit 8 is a schematic diagram of a spatial light modulator provided by an embodiment of the present application, which includes three phase adjustment units, and schematically expresses that the phase adjustment units include a multi-layer structure;
  • FIG. 9 is a schematic diagram of a spatial light modulator provided by an embodiment of the present application.
  • FIG. 10 is a schematic diagram of a spatial light modulator provided by an embodiment of the present application.
  • FIG. 11 is a schematic diagram of a spatial light modulator provided by an embodiment of the present application.
  • FIG. 12 is a schematic diagram of a spatial light modulator provided by an embodiment of the present application.
  • FIG. 13 is a schematic diagram of electrode distribution of a spatial light modulator provided by an embodiment of the present application.
  • FIG. 14 is a schematic diagram of electrode distribution of a spatial light modulator provided by an embodiment of the present application.
  • 15 is a schematic diagram of electrode distribution of a spatial light modulator provided by an embodiment of the present application.
  • 16 is a schematic diagram of a spatial light modulator provided by an embodiment of the present application.
  • FIG. 17 is a schematic diagram of a spatial light modulator provided by an embodiment of the present application.
  • FIG. 18 is a schematic diagram of an electrode part in a spatial light modulator provided by an embodiment of the present application, wherein a micro-pillar structure is provided on the electrode;
  • FIG. 19 is a schematic diagram of a spatial light modulator provided by an embodiment of the present application.
  • 20 is a schematic diagram of a multi-layer electrode structure of a spatial light modulator provided by an embodiment of the present application.
  • 21 is a schematic diagram of a spatial light modulator provided by an embodiment of the present application.
  • FIG. 22 is a schematic diagram of a spatial light modulator provided by an embodiment of the present application.
  • FIG. 23 is a schematic diagram of a spatial light modulator provided by an embodiment of the present application.
  • 24 is a schematic diagram of electric field distribution of an interdigital electrode structure of a spatial light modulator provided by an embodiment of the present application.
  • FIG. 25 is a schematic diagram of electric field distribution of electrodes of a multi-layer structure of a spatial light modulator provided by an embodiment of the present application.
  • an optical switching node networking system 1000 includes an upper and lower wavelength selective switch group 1 connected between the local A and the pass-through optical path B.
  • the upper and lower wavelength selective switch group 1 includes a plurality of wavelength selective switches connected in parallel between the local A and the pass-through optical path B.
  • the upper and lower wavelength selective switch 1' are used to download the optical signal of the specific wavelength passing through the optical path B to the local A, or upload the optical signal of the specific wavelength of the local A to the optical path B passing through.
  • Local A can be understood as the local computer room, which is equipped with boards, switches and other equipment.
  • the pass-through optical path B can be understood as an optical path formed by interconnecting multiple WSS100s. Each WSS100 is connected to other nodes via fiber 2.
  • the wavelength selective switch 100 can be applied to a ROADM (Reconfigurable Optical Add-Drop Multiplexer, reconfigurable optical add-drop multiplexer).
  • the wavelength selective switch 100 includes an optical fiber array 20 , a main lens 30 and a spatial light modulator 10 (Spatial Light Modulator, SLM).
  • the optical fiber array 20 includes input and output ports. As shown in FIG. 2 , one output port I and four input ports O1, O2, O3 and O4 are schematically represented, and the output port I and each input port O1, O2, O3 and O4 are schematically represented.
  • the position of the output port I can be designed according to the specific application scenario, and is not limited to the structure shown in FIG.
  • the optical signal emitted by the output port I is the incident light (that is, the part of the light between the fiber array 20 and the main lens 30 in FIG. 2, and the arrow points to the part of the light expressed by the solid line of the main lens 30), and the main lens 30 is used to convert the incident light.
  • the transformation is collimated light (ie, the part of the light between the main lens 30 and the spatial light modulator 10 in FIG. 2, and the arrow points to the part of the light indicated by the solid line of the spatial light modulator 10).
  • the spatial light modulator 10 is a phase-type SLM for changing the phase of an optical signal. After the collimated light enters the spatial light modulator 10, the spatial light modulator 10 reflects and deflects the light beam.
  • the deflected and reflected light is outgoing light (that is, the part of the light between the main lens 30 and the spatial light modulator 10 in FIG. 2 , and the arrow points to the part of the light represented by the dashed line of the main lens 30 ), and the outgoing light passes through the main lens 30, is focused coupled to input port O4.
  • the spatial light modulator provided in this application can also be used in other application scenarios, such as: N ⁇ N WSS, ADWSS, lidar, laser display and so on.
  • the spatial light modulator provided by the present application is a phase-type spatial light modulator, which adjusts the phase of the optical signal without changing the intensity of the optical signal.
  • FIG. 3 and FIG. 4 depict a schematic cross-sectional view and a schematic plan view of the backplane 110 , respectively
  • FIGS. 5 and 6 depict a schematic cross-sectional view and a schematic plan view of the spatial light modulator 10 , respectively.
  • the spatial light modulator 10 provided by the present application includes a backplane 110 and a pixel array 120 formed on the backplane.
  • a plurality of driving circuits 111 are arranged in the backplane 110 in an array.
  • the driving circuits 111 are arranged in M rows and N columns.
  • the driving circuit 111 is a circuit structure fabricated in the backplane 110 , and may be formed on a certain layer or some layer structures in the backplane 110 , or may be an individual electronic component embedded in the backplane 110 .
  • the backplane 110 may be a ceramic substrate or a substrate made of other materials.
  • the backplane 110 includes a front side S1 and a back side S2 arranged opposite to each other.
  • the front side S1 is used to form the pixel array 120 , and it can also be understood that the front side S1 is a surface for making a phase adjustment unit.
  • the front S1 is provided with an interface 112 electrically connected to the driving circuit 111 , each driving circuit 111 corresponds to two interfaces 112 , one of the interfaces 112 is electrically connected to the reference voltage of the driving circuit 111 , and the other interface 112 is electrically connected to the ground of the driving circuit 111 .
  • the interface 112 can be a pad structure, and the surface of the pad can be coplanar with the front surface S1, so that the front surface S1 is kept as a plane, and the pixel array 120 can be easily fabricated.
  • the pixel array 120 includes a plurality of pixel units 121 arranged in an array (for example, M rows and N columns). Adjacent pixel units 121 are seamlessly connected.
  • each pixel unit 121 includes a driving circuit 111 (located in the backplane 110 ), a phase adjusting unit 20 (formed on the front S1 of the backplane 110 ), an electrode 30 (formed on the backplane 110 ) phase adjustment unit 20) and an electrical connection 40 (formed in the phase adjustment unit 20).
  • the phase adjustment unit 20 has a solid layer structure. In terms of structure, adjacent phase adjustment units 20 are interconnected as a whole, and there is no gap between adjacent phase adjustment units 20, that is, a plurality of phase adjustment units 20 distributed in an array are placed next to each other on the front surface S1 of the backplane 110.
  • each phase adjusting unit 20 is formed through the same manufacturing steps, and each manufacturing step simultaneously forms a certain layer structure of all the phase adjusting units 20.
  • FIG. 8 schematically shows that each pixel unit 121 includes The multi-layer structure, and all the pixel units 121 have the same number of layers, and each layer is interconnected to form the same layer structure. It can be seen in particular that all the electrodes 30 are located on the same layer. This structure makes the manufacturing process simple and easy. Save production costs. In the present application, after the phase adjustment units 20 are fabricated on the backplane, there is no need to dig trenches between adjacent phase adjustment units 20 , resulting in low fabrication cost and high yield.
  • each pixel unit 121 Since the structure of each pixel unit 121 is the same, the detailed structure of one of the pixel units 121 will be described below.
  • the phase adjustment unit 20 includes a lower cavity mirror 21 , a cavity layer 22 and an upper cavity mirror 23 , which are sequentially stacked on the back plate 110 , and the lower cavity mirror 21 is located on the cavity layer 22 and the upper cavity mirror 23 . between the backplanes 110 .
  • the phase adjustment unit 20 in the spatial light modulator provided by the present application has a solid layer structure.
  • the phase adjustment unit 20 is an asymmetric FP (Fabry-Perot, Fabry-Perot) microcavity , wherein the lower cavity mirror 21 , the cavity layer 22 and the upper cavity mirror 23 are also structures having a multi-layer structure (or a membrane structure).
  • the lower cavity mirror 21 is a reflective layer composed of a multi-layer structure (or a film structure) or a metal reflective layer, the reflectivity of the lower cavity mirror 21 is close to or is 1, and the corresponding layer structures between different pixel units 121 can be connected to the same Floor. That is to say, in the process of fabricating the lower cavity mirror 21 on the backplane 110 , a large-area reflective layer can be directly formed, and the large-area reflective layer can cover a plurality of pixel units 121 distributed in an array. The part of the large-area reflective layer corresponding to 121 is the lower cavity mirror 21 of the pixel unit.
  • the materials of the cavity layer 22 and the upper cavity mirror 23 are materials with electro-optic effect, such as BTO (BaTiO3, Barium titanate, barium titanate), Si (silicon, such as Si nanomaterials), and the response rate of such materials is on the order of GHz .
  • the asymmetric FP microcavity structure can be formed by fabricating Si nanowires, nanometer micropillars and other structures on the surface of the upper cavity mirror 23 . By designing the structure of an asymmetric FP microcavity, phase modulation in which the wavefront amplitude variation of the optical signal is close to zero can be realized.
  • the spatial light modulation unit provided by the present application can perform pure phase modulation on the optical signal without changing the light intensity.
  • the phase adjustment unit 20 can be divided into a main area A and an edge area B.
  • the edge area B is located at the periphery of the main area A and surrounds the main area A.
  • the main area A is It is the part inside the dashed frame.
  • the main body area A is a square area
  • the edge area B surrounds the main body area A and is a frame-shaped area outside the main body area A.
  • the phase adjustment unit 20 provided in the present application has an integrated structure, and the division of the main body area A and the edge area B does not mean that the phase adjustment unit 20 can be divided into two parts. In one embodiment, it can be understood as: the main body area
  • the area A is the area where the electrodes 30 are arranged.
  • the setting of the electrodes 30 cannot cover all the areas of the phase adjustment unit 20, and the edge area B should be reserved. Electrical connection part 40 .
  • the main body area A is equivalent to the functional area of the phase adjustment unit 20, the electrodes 30 are arranged in the main body area A, and the electrical connection part 40 can be located in the edge area.
  • the generated driving electric field is also located in the main body area.
  • the electrodes 30 can also be arranged in the main body area A and the edge area B, the electrical connection parts 40 are located in the edge area, and the area between the electrical connection parts 40 is the main body area A.
  • the electrodes 30 When a voltage is applied, only the main body area A is present.
  • the inner part of the electrode 30 generates a driving electric field.
  • the electrodes 30 may not only be arranged in the main body area A, but the electrodes 30 may also extend to the edge area B. However, through the configuration of the electrical connection parts 40 , the electrodes 30 are only generated in the main body area A in the energized state.
  • the driving electric field can also ensure the isolation of the driving electric field between adjacent pixel units, so that the phase adjustment of the optical signal between adjacent pixel units will not generate crosstalk.
  • the electrode 30 includes a first electrode and a second electrode that are insulated from each other, the electrode 30 is located inside or on the surface of the phase adjustment unit 20, and the electrode 30 is located on the lower cavity mirror 21 away from the back plate 110.
  • One side; the electrode 30 may be formed in the phase adjustment unit 20, specifically, the electrode 30 may be fabricated at the same time in the process of manufacturing the phase adjustment unit 20, and the electrode 30 may be formed in a certain layer or some layers in the middle of the phase adjustment unit 20 , or formed on the surface layer of the phase adjustment unit 20 , or an electrode 30 may be disposed on the fabricated phase adjustment unit 20 .
  • the electrical connection part 40 includes a first electrical connection part 41 and a second electrical connection part 42 , the electrical connection part 40 is electrically connected to the electrode 30 and the driving circuit 111 , and the first electrical connection part 41 is electrically connected to the first electrode. and the driving circuit 111, the second electrical connection part 42 is electrically connected between the second electrode and the driving circuit 111, so as to form a driving electric field between the first electrode and the second electrode, and adjust the phase adjustment Refractive index of cell 20 .
  • the electrode 30 can be arranged in a single-layer structure, as shown in the embodiments shown in FIG. 9 to FIG. 12 .
  • the electrodes 30 are arranged on the first surface S1 , that is, they are coplanar.
  • the first electrodes and the second electrodes are fabricated on the same layer structure.
  • the phase adjustment unit 20 includes a plurality of layer structures stacked in sequence, and the first surface S1 is the surface of one of the layer structures.
  • the lower cavity mirror 21 , the cavity layer 22 and the upper cavity mirror 23 may all be a structure in which one or more layers are stacked in sequence, as long as the first surface S1 is not disposed in the lower cavity mirror 21 .
  • the first surface S1 may be located on the cavity layer 22 , and the position of the first surface S1 shown in FIG. 9 is the bottommost surface of the cavity layer 22 , that is, the surface of the cavity layer 22 adjacent to the lower cavity mirror 21 , Of course, the first surface S1 may also be the surface of other layers of the cavity layer 22 .
  • the electrode 30 is on the first surface S1, the electrode 30 may cover a partial area of the first surface S1, and the electrode 30 may also cover the entire area of the first surface S1.
  • the difference between this embodiment and the embodiment shown in FIG. 9 is that the first surface S1 is the surface of an intermediate layer of the cavity layer 22 , and the electrode 30 is located in the intermediate layer of the cavity layer 22 . .
  • the difference between this embodiment and the embodiment shown in FIG. 9 is that the first surface S1 is the bottommost surface of the upper cavity mirror 23 (that is, the surface of the upper cavity mirror 23 adjacent to the cavity layer 22 ) surface), the electrode 30 is located on the bottom layer of the upper cavity mirror 23.
  • the difference between this embodiment and the embodiment shown in FIG. 9 is that: the first surface S1 is the surface on which the top layer of the upper cavity mirror 23 is made, and the electrode 30 is located on the top layer of the upper cavity mirror 23 , that is, the electrode 30 is located in the layer structure on the side of the upper cavity mirror 23 facing away from the cavity layer 22 .
  • the specific structural form of the electrode 30 may be an interdigitated electrode structure, or a parallel line electrode structure.
  • a possible implementation of the electrode 30 in an interdigitated electrode structure is: referring to FIG. 13 , the electrode 30 is located in the main body region A, and the electrical connection portion 40 is located in the edge region B.
  • the electrode 30 includes a first electrode 31 and a second electrode 32, the electrical connection part 40 includes a first electrical connection part 41 and a second electrical connection part 42, and shown on the first surface S1 is the pad of the first electrical connection part 41 part and the pad part of the second electrical connection part 42, it can be understood that the first electrical connection part 41 also includes a conductive part (only the pad part is shown in FIG.
  • the first electrode 31 includes a first main line 311 and at least two first branches 312 extending from one side of the first main line 311, and the second electrode 32 includes a second main line 321 and a At least two second branches 322 extend from one side of the main line 321 .
  • the first main line 311 and the second main line 321 are disposed opposite to each other, and the first branch 312 and the second branch 322 form an interdigital structure.
  • the interdigital structure can be understood as: the first branch 312 is inserted into two adjacent Between the second branches 322 , the first branches 312 and the second branches 322 are alternately arranged, and the arrangement rule may be: one first branch 312 , one second branch 322 , one first branch 312 . . . In the embodiment shown in FIG. 13 , the number of the first branch 312 and the number of the second branch is five.
  • the first branch 312 and the second branch 322 are linear, and each first branch 312 is parallel to and partially overlapping with the adjacent second branch 322 .
  • the first branch 312 and the second branch 322 may be arranged in parallel and both are perpendicular to the first main line 311 or the second main line 321 .
  • the first branch 312 and the second branch 322 may form an included angle with the first main line 311 and the second main line 321 .
  • the included angle is 90 degrees, it is the aforementioned vertical state, and the included angle may also be less than 90 degrees, for example 60 degrees, 75 degrees, etc., which are not limited in this application.
  • the difference between the embodiment shown in FIG. 14 and the embodiment shown in FIG. 13 is that the first branch 312 and the second branch 322 are curved, and the shapes of the first branch 312 and the second branch 322 may be specifically S-shaped, C-shaped, curved, spiral or other irregular curved shapes.
  • first branch 312 and the second branch 322 may be a combination of multiple straight lines, such as an L-shape, or various solutions such as a combination of a straight line and a curve, which is not limited in this application.
  • the first connection portion 41 is connected to the first main line 311
  • the second connection portion 42 is connected to the second main line 321
  • the first connection portion 41 and the first main line 321 The two connecting portions 42 are distributed on opposite sides of the electrode 30 .
  • the first connecting portion 41 and the second connecting portion 42 are located in the edge region B of the phase adjusting unit 20, and the first connecting portion 41 and the second connecting portion 42 can be made of opaque materials, such as metal materials, The opaque material has the advantage of low cost.
  • the electrical connection part 40 is arranged in the edge area B, and the edge area B is the isolation area between the main body areas A between the adjacent phase adjustment units 20.
  • the driving electric field will not be formed in the edge region B, so the edge region B does not need to transmit light, and the opaque electrical connection part 40 can be arranged in the edge region B, so as to avoid disposing the opaque electrical connection part 40 in the main body
  • the transmittance of the main body area A of the phase adjusting unit 20 is ensured, the transmittance is improved, the isolation between adjacent phase adjusting units can be ensured, and the low cost of the spatial light modulator can be realized.
  • a possible implementation of the electrode 30 in a parallel line electrode structure is: referring to FIG. 15 , the first electrode 31 and the second electrode 32 extend side by side and synchronously from the first position L1 on the first surface S1 to the first At the second position L2 on the surface S1, an insulating space between the first electrode 31 and the second electrode 32 is provided.
  • the first electrode 31 and the second electrode 32 are both in the structure of one main line, and there are no other branches.
  • the present application can also add branch designs on the basis of the main line structure of the first electrode 31 and the second electrode 32 on the basis of the embodiment shown in FIG. 15 .
  • the extending paths of the first electrode 31 and the first electrode 32 are in a zigzag shape, a serpentine shape or a spiral shape.
  • the path extended by the first electrode 31 and the second electrode 32 includes a plurality of continuous straight line segments or continuous curved lines.
  • the first connection portion 41 and the second connection portion 42 of the electrical connection portion 40 can both be located at the first position L1 , and the first position L1 is located at the outer edge of the electrode 30 .
  • the first position L1 is located in the edge region B of the phase adjustment unit 20 .
  • the electrical connection part 40 can also be set at the second position L2. Since the second position L2 is in the main body area A, the electrical connection part 40 needs to be set in a light-transmitting state, or although the electrical connection part 40 is not The material is light-transmitting, but the size is suitable and will not affect the light transmittance of the main area A.
  • first electrical connection part 41 and the second electrical connection part 42 may be arranged at the first position L1 and the second position L2, respectively.
  • the numbers of the first electrodes 31 and the second electrodes 32 are the same, and both are one.
  • the number of the first electrodes 31 and the second electrodes 32 may also be at least two, for example, two first electrodes cooperate with two second electrodes, and the corresponding electrical connection parts The number of 40 can also be increased accordingly.
  • the number of the first electrodes 31 and the number of the second electrodes 32 may also be different, for example, one first electrode 31 and two second electrodes 32 form an electrode structure.
  • the electrode 30 is disposed on the surface of the upper cavity mirror 23 away from the cavity layer 22.
  • the electrode 30 is an interdigital electrode structure, and the specific structure is similar to the figure 13 shown in the embodiment.
  • the first electrode 31 and the second electrode 32 protrude from the top surface of the upper cavity mirror 23
  • the first electrical connection part 41 and the second electrical connection part 42 also protrude from the top of the upper cavity mirror 23 noodle.
  • the area between the first electrode 31 and the second electrode 32 and the surrounding area of the first electrode 31 and the second electrode 32 is air.
  • an electro-optic medium 50 is provided between the first electrode 31 and the second electrode 32, and the material of the electro-optic medium 50 can be: such as EO Polymer, LiNbO3, BTO, etc.
  • An electro-optic medium 50 may also be provided on the periphery of the first electrode 31 and the second electrode 32 .
  • the first electrical connection portion 41 and the second electrical connection portion 42 are also surrounded by the electro-optic medium 50 .
  • the electrode 30 is embedded in the electro-optic medium 50 , the top surface of the electrode 30 and the top surface of the electro-optic medium 50 may be coplanar, and the top surface of the electrode 30 may also protrude from the top surface of the electro-optic medium 50 .
  • “Top surface” refers to the surface of the electrode 30 and the electro-optic medium 50 away from the upper cavity mirror 23 .
  • the electrode 30 is arranged on the surface of the upper cavity mirror 23 away from the cavity layer 22 , and the electrode 30 is combined with the structure of the electro-optic medium 50 , while the electrode 30 is formed on the surface of the upper cavity mirror 23 , it can also have the “in the upper cavity mirror”.
  • the surface is provided with a protruding structure to realize the function corresponding to the "asymmetric structure", that is, the electrode 30 and the electro-optic medium 50 constitute an asymmetric structure, whereby in this embodiment, the phase adjustment unit 20 can realize only the phase adjustment of the optical signal, not the phase adjustment of the optical signal. Affects the strength of the light signal.
  • the embodiment shown in FIG. 17 can be specifically understood as: the upper cavity mirror 23 is a SiO2 layer with a thickness of 100 nm.
  • the upper cavity mirror 23 can be regarded as a layer-by-layer structure, and its material is a single SiO2,
  • the upper cavity mirror 23 can also be a multi-layer structure, and the materials of the two adjacent layers are different, for example, a layer of SiO2, a layer of doped Si, a layer of SiO2, and a layer of doped Si. ...something like this arrangement.
  • a doped Si layer with a thickness of 250 nm is formed on the surface of the upper cavity mirror 23 , the doped Si layer is used to make the electrode 30 , and the Si nanowires (ie the first branch and the second branch in the electrode 30 are obtained by etching the doped Si layer) part), its width is 200nm, its length is 1.8um, and the center-to-center spacing between adjacent nanowires is 400nm. Then fill the center space between adjacent nanowires with EO-Polymer, and completely fill the EO-Polymer between and around the Si nanowires. The EO-Polymer is also formed on the surface of the upper cavity mirror 23. The Si nanowires and the EO-Polymer together form the same layer.
  • Compartments are formed between adjacent nanowires, and the EO-Polymer polarization directions in adjacent compartments are opposite.
  • the Si nanowires with odd numbers (1, 3, 5) ie, the first branch of the first electrode
  • the Si nanowires with even numbers (2, 4, 6) ie the second branch of the second electrode
  • Si nanowires with even numbers (2, 4, 6) ie the second branch of the second electrode
  • the shape structure ie, the second main line of the second electrode
  • is connected ie, constitutes the second electrode), and is in contact with the top electrode of another metal via (ie, the pad of the second electrical connection portion).
  • the horizontal Si stripe structures (ie, the first main line and the second main line) have a width of 200 nm and a length of 2 um.
  • the distance between the Si nanowires with odd numbers (1, 3, 5) (ie, the first branch) and the horizontal upper Si stripe structure (ie, the second main line) is 100 nm; even numbers (2, 4, 6) ) of the Si nanowire (ie the second branch) and the horizontal underlying Si stripe structure (ie the first main line) with a distance of 100 nm.
  • FIGS. 18 and 19 when the electrode 30 is disposed on the surface of the upper cavity mirror 23 away from the cavity layer 22 , the surface of the electrode 30 is provided with a plurality of micro-pillar structures 60 , and the micro-pillar structures 60 are used to inhibit the The intensity modulation of the optical signal makes the spatial light modulator provided by this application tend to be purely phase-modulated.
  • FIG. 18 is a schematic plan view of disposing a micro-pillar structure 60 on the first electrode 31 and the second electrode 32 , wherein the first electrode 31 and the second electrode 32 are interdigitated electrode structures.
  • FIG. 19 is a structure with a micro-pillar structure 60 added on the basis of the embodiment of FIG. 17 . In the embodiment shown in FIG.
  • each micro-pillar structure 60 is in a square shape and is distributed on the branches of each electrode.
  • the micro-pillar structure 60 can also be in other shapes, such as cylindrical, spherical, and the like.
  • the micro-pillar structures 60 may be uniformly distributed on the electrode 30 .
  • the micro-pillar structures 60 on the electrode 30 may also be distributed in different areas with different densities. For example, the density of the micro-pillar structures 60 distributed near the central area of the phase adjustment unit is smaller than that of the micro-pillar structure 60 distributed near the edge area of the phase adjustment unit. The density of the micropillar structure 60 .
  • the first electrode 31 and the second electrode 32 of the electrode 30 of the single-layer structure may be nanowire structures, such as doped Si.
  • the phase adjustment unit may include a single-layer structure (eg, an interdigitated electrode structure and a parallel line electrode structure).
  • a single-layer structure eg, an interdigitated electrode structure and a parallel line electrode structure.
  • This application does not limit the number of layers of electrodes with a single-layer structure, that is, in a phase adjustment unit of a pixel unit, only one layer of electrodes with a single-layer structure may be included, and one layer of electrodes with a single-layer structure may be independent Work, generate a driving electric field, change the refraction efficiency of the phase correction unit, or the coupling efficiency, so as to adjust the phase of the reflected light.
  • the phase adjustment unit of a pixel unit may also include at least two-layer single-layer structure electrodes, each layer of the single-layer structure electrodes is independent of each other, and the multi-layer single-layer structure electrodes may be electrically connected to the same driving circuit.
  • the driving circuit can drive all the electrodes of the single-layer structure at the same time, and can also selectively drive part of the electrodes of the single-layer structure as required.
  • FIG. 24 Please refer to Figure 24 for the electric field distribution and refractive index change of the electrodes of the single-layer structure.
  • the figure on the left shows that one of the first electrode and the second electrode is connected to the reference voltage, and the other is A driving electric field is formed between the first electrode and the second electrode, and the line with arrows between the first electrode and the second electrode in the figure represents the electric field distribution.
  • the figure on the right is an enlarged schematic diagram of the dotted circle part of the figure on the left, and the refractive index ellipsoid is marked, which represents the change of the refractive index of the electro-optic medium of the phase adjustment unit. When no electricity is applied, the refractive index ellipsoid is basically a circle.
  • the refractive index of the electro-optic medium is n, when the electrode is electrified, the refractive index ellipsoid is elongated, and the refractive index of the electro-optic medium is n+ ⁇ n.
  • the arrangement of the electrodes 30 can also be designed as a multi-layer structure, see the respective embodiments shown in FIGS. 20 to 23 .
  • FIG. 20 is a schematic diagram of the electrode 30 of the multilayer structure.
  • the multi-layer here refers to at least two layers, and the first electrode 31 and the second electrode 32 are both planar and along the first direction (the direction indicated by the double-headed arrow in FIG. 20 ) ) are alternately stacked in sequence, the first direction is the direction in which the lower cavity mirror, the cavity layer and the upper cavity mirror are stacked in sequence, and the first direction can be understood as a direction perpendicular to the back plate.
  • the first electrode 31 and the second electrode 32 are not located in the same layer, but are formed in different layers of the phase adjustment unit.
  • each of the first electrode 31 and the second electrode 32 is a film layer structure, and is distributed in a certain layer of the cavity layer in a planar shape, or a certain layer of the upper cavity mirror. Different electrodes 30 are located at different layers. Moreover, the first electrodes 31 and the second electrodes 32 are alternately stacked, that is, the second electrode 32 is provided in the layer structure adjacent to one of the first electrodes 31, and one of the first electrodes 31 can be sandwiched adjacent to between the two second electrodes 32 .
  • the first electrical connection portion 41 is electrically connected to the first electrode 31
  • the second electrical connection portion 42 is electrically connected to the second electrode 32 . As shown in FIG.
  • the first electrode 31 and the second electrode 32 partially overlap, and the first electrode 31
  • the left edge region of the second electrode 32 does not overlap with the second electrode 32
  • the right edge region of the second electrode 32 does not overlap with the first electrode 31
  • the first connection part 41 is connected to the leftmost edge position of the first electrode 31
  • the second The connection portion is connected at the rightmost edge position of the second electrode 32 . It can be summarized as follows: the portion of the first electrode 30 that does not overlap with the second electrode 30 is connected to the first connection portion 41 , and the portion of the second electrode 30 that does not overlap the first electrode 30 is connected to the first connection portion 41 .
  • the second connecting portion 42 is described.
  • the first electrode 31 and the second electrode 32 may be layer structures parallel to each other.
  • the electrode 30 is located in the cavity layer 22 , and the first electrode 31 and the second electrode 32 are both disposed in the cavity layer 22 .
  • the advantage of fabricating the electrode 30 in the cavity layer 22 is that the fabrication process is relatively simple, because the cavity layer 22 is a single material, regardless of whether the transmittance or reflectivity is generated, for the cavity layer 22, the transmission is controlled by the material itself. The transmittance is not controlled by its specific structure. Although the electrode 30 changes the structure of the cavity layer 22, it has little effect on the transmittance because the transmittance is controlled by the material of the cavity layer 22 itself. The sizes of the lower cavity mirror 21 and the cavity layer 22 shown in FIG. 21 are different.
  • FIG. 21 only shows part of the cavity layer 22 and part of the upper cavity mirror 23 , and the display state in FIG. 21 does not represent the phase.
  • the sizes of the lower cavity mirror 21 and the cavity layer 22 in the adjustment unit are different.
  • the cavity layer 22 includes two layers of ITO thin films and LiNbO3 thin films, which are alternately stacked and distributed, specifically, one layer of LiNbO3 thin film, one layer of ITO thin film, and one layer of LiNbO3 thin film.
  • the number of layers of the cavity layer 22 may be three, four or more layers, and the materials of the adjacent two layers are different.
  • the ITO film is the electrode 30
  • the LiNbO3 film is the electro-optic medium between the electrodes 30 .
  • the thickness of each LiNbO3 film is 400 nm, and the thickness of each ITO film is 50 nm.
  • the length (perpendicular to the paper surface) of the ITO film is 4um, and the width (parallel to the paper surface) is 2um.
  • the ITO films with odd numbers (1, 3) (constituting the first electrode) are connected to the vertical metal through hole on the left (ie, the first electrical connection part); the ITO films with even numbers (2) (constituting the second electrode) are connected to The vertical metal through holes (ie, the second electrical connection parts) on the right side are connected to each other.
  • the area between the ITO films is defined as the interlayer, and the polarization directions of the LiNbO3 films between two adjacent layers are opposite.
  • the surface of the upper cavity mirror 23 facing away from the cavity layer 22 that is, the surface of the phase adjustment unit facing away from the back plate, is provided with a protruding structure 70 , that is, the protruding structure 70 is formed on the topmost layer of the upper cavity mirror 23 , It can also be understood that the protruding structure 70 is located on the side of the upper cavity mirror 23 away from the cavity layer 22 , that is, the protruding structure 70 is a structure independent of the upper cavity mirror 23 .
  • the arrangement of the protruding structure 70 makes the phase adjustment unit form an asymmetric structure for suppressing the modulation of the intensity of the optical signal, so that the spatial light modulator provided by the present application is inclined to pure phase modulation.
  • the protruding structure 70 shown in FIG. 21 is in the shape of a rectangular parallelepiped, and the protruding structure 70 can also be in other shapes, such as cylindrical shape, square shape, spherical shape and so on.
  • the first electrical connection portion 41 and the second electrical connection portion 42 are respectively located on opposite sides of the electrode 30 .
  • the electrode 30 includes two first electrodes 31 and two second electrodes 32 .
  • the electrode 30 is fabricated in the upper cavity mirror 23 , and the principle is the same as that of fabricating the electrode 30 in the cavity layer 22 .
  • the electrode 30 includes two first electrodes 31 and one second electrode 32 , the first electrical connection portion 41 is electrically connected to the two first electrodes 31 , and the second electrical connection portion 42 is electrically connected to one second electrode 32.
  • a protruding structure 70 is also provided on the surface of the upper cavity mirror 23 facing away from the cavity layer.
  • some electrodes 30 are fabricated in the cavity layer 22
  • some electrodes 32 are fabricated in the upper cavity mirror 23 .
  • the cavity layer 22 includes a first electrode 31 and a second electrode 32
  • the upper cavity mirror 23 also includes a first electrode 31 and a second electrode 32 .
  • the first electrical connection parts 41 are electrically connected to all the first electrodes 31
  • the second electrical connection parts 42 are electrically connected to all the second electrodes 32 .
  • a protruding structure 70 is also provided on the surface of the upper cavity mirror 23 facing away from the cavity layer.
  • the surface of the upper cavity mirror 23 away from the cavity layer 22 may also be provided with a protruding structure (similar to the protruding structure shown in FIG. 21-FIG. 23), and the function is also
  • the phase adjustment unit 20 it is used to suppress the modulation of the intensity of the optical signal, so that the spatial light modulator provided by the present application is inclined to pure phase modulation.
  • the number of the first electrodes 30 is two or more, and the number of the second electrodes 30 is two or more. Since the first electrode 30 and the second electrode 30 will generate an electric field when the first electrode 30 and the second electrode 30 are energized, if the number of the electrodes 30 is set to two or more, a smaller voltage can be used to generate the required electric field.
  • the number of the first electrodes 30 or the second electrodes 30 can be controlled to 2-3 layers, because if the number of layers is too large, for example, more than 3 layers, it is difficult to realize from the manufacturing point of view. Therefore, the maximum number of layers of the electrodes 30 may be 6 layers, wherein the first electrodes 30 are 3 layers, and the second electrodes 30 are 3 layers.
  • each layer of electrodes 30 can be as follows:
  • an electrode layer is formed on the surface of a certain layer of the phase adjustment unit by sputtering, and the material of the electrode layer can be doped silicon;
  • Photolithography process coating a photoresist layer on the electrode layer, and forming the photoresist layer into a preset pattern through the photolithography process;
  • the patterned electrodes are planarized, which can be realized by polishing, such as chemical mechanical polishing.
  • the electrode 30 includes one layer of the first electrodes 31 and two layers of the second electrodes 32 , or two layers of the second electrodes 32 and three-layer first electrodes 31 .
  • FIG. 25 schematically shows the structure of two layers of first electrodes and one layer of second electrodes, and the two layers of first electrodes are connected to the driving circuit The reference voltage of the second electrode of one layer is grounded. In the power-on state, a driving electric field is formed between the layers on both sides of the second electrode, and the direction of the driving electric field in the two layers is opposite.
  • the pad can be located in the same layer structure as the electrode 30, and the conductive part can be a via hole lead form.
  • via holes may be formed between the layer structure where the pads are located and the backplane 110, and metal wires or metal conductive pillars may be arranged in the via holes, or by electroplating, on the inner wall of the via holes A metal layer is formed to constitute a conductive portion.
  • the electrodes 30 and the electrical connection parts 40 of the electrodes 30 and the driving circuit are all integrated in the phase correction unit, that is, in the process of manufacturing the phase correction unit, the phase correction unit can be synchronized in the phase correction unit.
  • Electrodes 30 and electrical connections 40 are fabricated in-house.
  • the electrode 30 and the electrical connection part 40 do not need to be separately fabricated outside the step of fabricating the phase correction unit, nor do they separately occupy a space outside the phase correction unit.
  • the phase correction units can be seamlessly connected as a whole, and the electric field generated after the electrode 30 is energized is directly formed in the phase correction unit without loss, and a small voltage can be used to generate the required electric field strength.

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Abstract

一种空间光调制器(10)和波长选择开关(100)，空间光调制器(10)包括内设驱动电路(111)的背板(110)，相位调节单元(20)，电极(30)和电连接部(40)。相位调节单元(20)包括下腔镜(21)、腔层(22)和上腔镜(23)，下腔镜(21)位于腔层(22)和背板(110)之间。电极(30)包括第一电极(31)和第二电极(32)，电极(30)位于相位调节单元(20)的内部或表面，且位于下腔镜(21)背离背板(110)的一侧；电连接部(40)电连接电极(30)和驱动电路(111)，以在第一电极(31)和第二电极(32)之间形成驱动电场，调节相位调节单元(20)的折射率。能够实现低插损、高效率的光转换的同时提升占空比。

Description

空间光调制器和波长选择开关
本申请要求于2020年8月21日提交中国国家知识产权局、申请号为202010849168.5、申请名称为“空间光调制器和波长选择开关”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及光通信领域，特别是一种空间光调制器和波长选择开关。
背景技术
光网络正朝着大容量、低时延、智能化的方向持续发展演进。ROADM(Reconfigurable Optical Add-Drop Multiplexer，可重构光分插复用器)和OXC(Optical Cross-Connect，光交叉互连)等光交换技术不仅支撑了当前商用的光网络，而且是实现下一代光网络的关键技术之一。WSS(Wavelength selective switch，波长选择开关)作为OXC的核心器件，其端口/通道扩展具有迫切需求和现实价值。
随着端口/通道的扩展，如何实现低插损、高效率的光转换的同时提升占空比，使得空间光调制器和波长选择开关具小尺寸、高性能的优势，为业界发展的趋势。
发明内容
本申请实施例提供一种空间光调制器和波长选择开关，能够实现低插损、高效率的光转换的同时提升占空比。
为了实现上述目的，本申请实施方式采用如下技术方案：
第一方面，本申请实施例提供一种空间光调制器，包括背板、相位调节单元、电极和电连接部。背板内设驱动电路。相位调节单元包括依次层叠设置在所述背板上的下腔镜、腔层和上腔镜，所述下腔镜位于所述腔层和所述背板之间。电极包括彼此绝缘的第一电极和第二电极,所述电极位于相位调节单元的内部或表面，且位于所述下腔镜背离所述背板的一侧。具体而言，电极与所述相位调节单元形成为一体式结构，在制作相位调节单元的过程中将电极制作在相位调节单元的内部或表面，或者本申请可以在已经制作好的相位调节单元的表面上设置电极。电连接部电连接所述电极和所述驱动电路，以在所述第一电极和所述第二电极之间形成驱动电场，调节所述相位调节单元的折射率，进而对光信号的相位做调制。本申请通过将电极形成在相位调节单元上，并位于下腔镜背离背板的一侧，使得电极与相位调节单元结合为一体，即电极的设置不占用相位调节单元周围的背板的空间，有利于提升空间光调制器的占空比，节约背板的空间。
传统的空间光调制器的设计，通常会将电极与相位校正单元分开设置在背板上，电极位于相位校正单元的周围，电极占用背板上的相位调节单元周围的面积，这样不但使得空间光调制器所占的背板的面积较大。而且，电极所形成的驱动电场，只能有局部电场作用在相位校正单元上，部分电场在相位校正单元的外围空间，无法作用在相位校正单元上，这样加载在电极上的电压就需要大于相位调节单元需要的驱动电压，不利于节能，驱动效率低。
而本申请将电极直接制作在相位调节单元上，对电极只要加载相位调节单元所需的驱动电压即可，不需要较大的驱动电压，插损小，低功率，高效转换的优势。
一种可能的实施方式中,所述驱动电路、所述相位调节单元、所述电极及所述连接部共同构成一个像素单元,所述空间光调制器包括多个所述像素单元,且多个所述像素单元呈阵列分布,相邻的所述像素单元的所述相位调节单元之间无缝连接。本实施方式中，多个像素单元在背板上一个挨着一个地紧密排列，邻的所述像素单元的所述相位调节单元之间无缝连接的架构，使得空间光调制器容易实现小型化的设计，而且，相邻的相位调节单元之间的无缝连接的架构还有利于制作，制作的过程中，阵列分布的多个像素单元的相位调节单元同时制作，而且制作后不需要在相邻的相位调节单元之间挖设沟道，制作成本低，良率高。
本申请提供的空间光调制器中的相位调节单元的为固态的层结构架构，一种实施方式中，相位调节单元为类似非对称FP(Fabry-Perot，法布里-帕罗)微腔结构，相位调节单元的下腔镜、腔层和上腔镜也都为具有多层层结构(或膜结构)的架构。下腔镜为多层层结构(或膜结构)构成的反射层或为金属反射层，其反射率接近或为1，不同像素之间的对应层结构可连通为同一层。也就是说，在背板上制作下腔镜的过程中，可以直接做一层大面积的反射层，可以覆盖多个阵列分布的像素单元，每个像素单元对应的区域为该像素单元的下腔镜。腔层和上腔镜的材料为具有电光效应的材料，例如BTO(BaTiO3，Barium titanate，钛酸钡)、Si(硅，例如Si纳米材质)，此类材料的响应速率在GHz量级。为了形成FP微腔结构的相位调节单元的非对称架构，可以通过在上腔镜表面制作Si纳米线、纳米微柱等结构的方式形成，藉此，本申请提供的相位调节单元可以实现光信号的波前幅度变化接近0的相位调制。本申请提供的空间光调制单元能够对光信号进行纯相位调制，不改变光强度。
相位调节单元可以分为主体区域和边缘区域，边缘区域位于主体区域的外围，并包围主体区域，主体区域相当于相位调节单元的功能区域，电极设置在主体区域内，电连接部可以位于边缘区域。本申请提供的相位调节单元为一体式结构，其中的主体区域和边缘区域的划分并不意味着相位调节单元可以被分割为两部分，本实施方式强调主体区域是设置电极的区域，可以理解为将电极的设置不能覆盖相位调节单元的所有的区域，而要将边缘区域预留出来，即边缘区域不设置电极，但可以在边缘区域设置电连接部。对当为电极加载电压时，产生的驱动电场也位于主体区域内，这样只改变主体区域的折射率，主体区域对光信号进行相位调节，而边缘区域由于没有驱动电场，不会对光信号产生影响。这样，相邻的像素单元的主体区域之间通过边缘区域相隔，使得相邻的像素单元之间对光信号的相位调节不会产生串扰。
其它实施方式中，电极也可以不只布置在主体区域，电极也可以延伸至边缘区域，但是通过电连接部的配置，使得电极在通电的状态下，只在主体区域产生驱动电场，也能够保证相邻的像素单元之间的驱动电场的隔离，从而相邻的像素单元之间对光信号的相位调节不会产生串扰。
电极为透光材质，这样，电极设置在主体区域内不会影响主体区域的透光率。电极可以为纳米线的形式，一种具体实施方式中，电极的材料可以为：掺杂Si。本申请将第一电极和第二电极与相位调节单元制作为一体，可以理解为第一电极和第二电极形成于相位调节单元的腔层和上腔镜的某一层结构上。第一电极和第二电极可以在制作腔层和上腔的某一层结构的过程中，通过掺杂Si工艺及刻蚀工艺，得到Si纳米线(为第一电极和第二电极)。第一电极和第二电极之一者电连接驱动电路的参考电压，另一个接地，这样，加载电压的情况下，形成驱动电场。
电连接部的材质可以为不透光的材质，例如金属材质，电连接部设置在边缘区域，电连 接部为不透光的材料也不会影响相位调节单元的透光率。电连接部可以包括第一电连接部和第二电连接部，第一电连接部电连接在第一电极和驱动电路之间，第二电连接部电连接在第二电极和驱动电路之间。具体为，连接部包括焊盘和电连接在焊盘和驱动电路之间的传导部，焊盘可以与电极位于同一层结构中，传导部可以为过孔引线的形式。具体而言，制作过程中，可以在焊盘所在的层结构和背板之间形成过孔，在过孔内设金属导线，或者设置金属导电柱，或者通过电镀的方式，在过孔内壁形成金属层，构成传导部。
一种可能的实施方式中，所述电极排布在第一面上，即第一电极和第二电极共面设置，在制作过程中，第一电极和第二电极制作在同一层的层结构上。所述相位调节单元包括多个依次层叠设置的层结构，所述第一面为其中一个所述层结构的表面。所述第一面可以为所述上腔镜背离所述腔层的表面。具体而言，下腔镜、腔层和上腔镜均可以为一层或多层的层结构依次层叠的架构，第一面只要不设置在下腔镜中，可以位于腔层的某一个层结构，或者上腔镜的某个层结构，或者腔层和上腔镜之间的层结构，或者上腔镜背离腔层的一侧的层结构。
一种可能的实施方式中，电极呈叉指电极架构，具体为：所述第一电极包括第一主线和从所述第一主线一侧延伸而出的至少两个第一分支，所述第二电极包括第二主线和从所述第二主线的一侧延伸而出的至少两个第二分支，所述第一主线和所述第二主线相对设置，所述第一分支和所述第二分支构成叉指架构。
一种可能的实施方式中，所述第一分支和所述第二分支呈直线状，具体而言，第一分支和第二分支可以平行设置且均垂直于第一主线或第二主线，第一分支和第二分支也可以与第一主线和第二主线之间形成夹角，夹角为90度的情况下为前述垂直的状态，夹角也可以为小于90度，例如60度、75度等，本申请不做限定。
一种可能的实施方式中，所述第一分支和所述第二分支呈曲线状，它们的形状具体可以为S形、C形、弧形、或其它不规则的曲线形状。
一种可能的实施方式中，所述电连接部包括彼此绝缘隔离的第一连接部和第二连接部，所述第一连接部连接至所述第一主线，所述第二连接部连接至所述第二主线，所述第一连接部和所述第二连接部分布在所述电极的相对的两侧。具体而言，第一连接部和第二连接部位于相位调节单元的边缘区域，第一连接部和第二连接头部可以为不透光的材质，例如金属材质，不透光的材质具有成本低的优势，将电连接部设置在边缘区域，边缘区域为相邻的相位调节单元之间的主体区域的隔离区，电极在此区域不形成驱动电场，因此边缘区域不需要透光，可以将不透光的电连接部设置在边缘区域。这样即保证相位调节单元的主体区域的透光率，提升透光率，又能够实现空间光调制器的低成本。
一种可能的实施方式中，所述第一电极和所述第二电极从所述第一面上的第一位置并排同步延伸至所述第一面上的第二位置，第一电极和第二电极之间绝缘设置。具体而言，所述第一电极和所述第一电极延伸的路径为回字形、蛇形或螺旋形。第一电极和第二电极延伸的路径包括多段连续相接的直线段、或者连续的曲线。此架构下，电连接部的第一连接部和第二连接部可以均位于所述第一位置,所述第一位置位于所述电极的外边缘的位置。第一位置位于相位调节单元的边缘区域。其它实施方式中，也可以将电连接部设置在第二位置；或者第一电连接部和第二电连接部分别布置在第一位置和第二位置。若第二位置设置在相位调节单元的主体区域，为了不影响透光性，位于第二位置的电连接部可以采用透光材料制作。
一种可能的实施方式中，所述下腔镜、所述腔层和所述上腔镜沿第一方向依次层叠设置，第一方向可以理解为垂直于背板的方向，所述第一电极和所述第二电极在所述第一方向上交 替层叠排布，即本实施方式中，第一电极和第二电极不是位于同一层(指的是相位调节单元的同一层)，而是形成在相位调节单元的不同的层中。可以理解为：对于每个第一电极和第二电极，均为膜层结构，呈面状分布在腔层的某一层内，或者上腔镜的某一层。不同的电极位于不同的层，相邻的电极之间通过绝缘层隔离，此绝缘层为相位调节单元的某一层，可以为电光介质。第一电极和第二电极交替层叠排布，即与其中一个第一电极相邻的层结构中设置的是第二电极，与其中一个第二电极相邻的层结构中设置的是第一电极，其中一个第一电极可以夹设在相邻的两个第二电极之间。
一种可能的实施方式中，所述电极位于所述腔层内。将电极制作在腔层内的好处是：制作工艺相对简单，因为腔层为单一材料，不用考虑是否产生透射率或反射率，对于腔层而言，是通过其材料本身控制透射率，不是通过其中的具体的结构控制，电极虽然改变腔层的结构，但对透射率影响较小，因为透射率通过材料控制。
一种可能的实施方式中，电极位于上腔镜内，将电极制作在上腔镜的原理同腔层制作电极的原理。上腔镜主要形成非对称结构，而非对称结构主要形成在上腔镜的顶部，即上腔镜背离腔层的表面。
一种实施方式中，部分电极位于腔层，部分电极位于上腔镜。
对于电极为多层结构的实施方式，电连接部的具体架构可以为：所述电连接部包括彼此绝缘隔离的第一连接部和第二连接部，所述第一电极和所述第二电极部分重叠，所述第一电极未与所述第二电极重叠的部分连接至所述第一连接部，所述第二电极未与所述第一电极重叠的部分连接至所述第二连接部。
一种可能的实施方式中，对于电极为多层的架构，所述第一电极的数量为两个或两个以上,所述第二电极的数量为两个或两个以上。由于第一电极和第二电极通电状态下会产生电场，将电极数量设置为两个或两个以上，可以使用较小的电压就能够产生需要的电场。可以将第一电极或第二电极的数量控制在2-3层，因为若层数太多，例如超过3层，从制作的角度来讲，较难实现。因此，电极最多的层数为6层，其中第一电极为3层，第二电极为6层。
每层电极的制作工艺可以包括如下步骤：
溅射工艺，通过溅射的方式在相位调节单元的某一层的表面制作电极层，电极层的材质可以为掺杂硅；
光刻工艺，在电极层上涂覆光刻胶层，并通过光刻工艺将光刻胶层形成预设图案；
刻蚀工艺，在电极层上形成所述预设图案；
平坦化工艺，对图案化的电极进行平坦化制作，具体可以通过抛光的方式实现，例如：化学机械抛光工艺。
第一电极和第二电极的层数不一定相同，例如：一种可能的实施方式中，电极包括一层第一电极和两层第二电极，或者两层第二电极和三层第一电极。
电极位于同一表面的实施方式中，即电极成形在第一面的实施方式中，第一电极和第二电极的数量也可以为相同的，例如第一电极的数量为一个，第二电极的数量亦为一个。第一电极和第二电极的数量也可以为两个或两个以上，对应的电连接部的数量也随之增加即可。第一电极的数量和第二电极的数量也可以不同，例如一个第一电极搭配两个第二电极构成电极架构。
一种可能的实施方式中，所述相位调节单元背离所述背板的表面设有突出结构，即突出结构形成在上腔镜的最顶层(即上腔镜背离腔层的一层)，也可以理解为，突出结构位于上腔 镜背离腔层的一侧，即突出结构为独立于上腔镜的结构。所述突出结构的设置使得相位调节单元构成非对称架构，用于抑制对光信号的强度的调制，使得本申请提供的空间光调制器倾向于纯相位调制。
一种可能的实施方式中，所述电极设置在所述上腔镜背离所述腔层的表面，所述电极的表面设有多个微柱结构，所述微柱结构用于抑制对光信号的强度调制，使得本申请提供的空间光调制器倾向于纯相位调制。
一种可能的实施方式中，所述电极设置在所述上腔镜背离所述腔层的表面，所述第一电极和所述第二电极之间设有电光介质，或者，所述第一电极和所述第二电极之间以及所述电极的外围均设电光介质。本实施方式将电极设置在上腔镜背离腔层的表面，通过电极结合电光介质的架构，在上腔镜的表面形成电极的同时，亦可以形成前述突出结构所具有的功能，即构成非对称结构，使得相位调节单元仅仅对光信号的相位调节，不影响光信号的强度。
第二方面，本申请提供一种波长选择开关，包括光纤阵列、主透镜和第一方面任意一种可能的实施方式所述的空间光调制器，所述光纤阵列发现的光束经过所述主透镜后变换为准直光，所述准直光进入所述空间光调制器，所述空间光准直器用于对所述准直光进行反射及偏转形成反射光，所述反射光经过所述主透镜聚集至所述光纤阵列。
附图说明
图1是光交换节点组网系统的示意图；
图2是本申请实施例提供的一种波长选择开关的示意图；
图3是本申请一种实施方式提供的空间光调制器的背板的剖视图；
图4是本申请一种实施方式提供的空间光调制器的背板的平面视图；
图5是本申请一种实施方式提供的空间光调制器的剖视图；
图6是本申请一种实施方式提供的空间光调制器的平面视图；
图7是本申请一种实施方式提供的空间光调制器的示意图，其中包括三个相位调节单元；
图8是本申请一种实施方式提供的空间光调制器的示意图，其中包括三个相位调节单元，且示意性地表达了相位调节单元包括多层层结构；
图9是本申请一种实施方式提供的空间光调制器的示意图；
图10是本申请一种实施方式提供的空间光调制器的示意图；
图11是本申请一种实施方式提供的空间光调制器的示意图；
图12是本申请一种实施方式提供的空间光调制器的示意图；
图13是本申请一种实施方式提供的空间光调制器的电极分布示意图；
图14是本申请一种实施方式提供的空间光调制器的电极分布示意图；
图15是本申请一种实施方式提供的空间光调制器的电极分布示意图；
图16是本申请一种实施方式提供的空间光调制器的示意图；
图17是本申请一种实施方式提供的空间光调制器的示意图；
图18是本申请一种实施方式提供的空间光调制器中的电极部分的示意图，其中电极上设有微柱结构；
图19是本申请一种实施方式提供的空间光调制器的示意图；
图20是本申请一种实施方式提供的空间光调制器的多层电极架构的示意图；
图21是本申请一种实施方式提供的空间光调制器的示意图；
图22是本申请一种实施方式提供的空间光调制器的示意图；
图23是本申请一种实施方式提供的空间光调制器的示意图；
图24是本申请一种实施方式提供的空间光调制器的叉指电极架构的电场分布示意图；
图25是本申请一种实施方式提供的空间光调制器的多层架构的电极的电场分布示意图。
具体实施方式
下面结合本申请实施例中的附图对本申请实施例进行描述。
本申请实施例提供的波长选择开关(Wavelength selective switch，WSS)应用于光交换节点组网系统。请参阅图1，光交换节点组网系统1000包括连接在本地A和穿通光路B之间的上下波长选择开关组1，上下波长选择开关组1包括多个并联在本地A和穿通光路B之间的上下波长选择开关1’。上下波长选择开关1’用于将穿光通路B的特定的波长的光信号下载至本地A，或者，把本地A的特定波长的光信号上传至穿通光路B。本地A可以理解为本地机房，机房内设板卡、交换机等设备。穿通光路B可以理解为多个WSS100互连构成的光路。每个WSS100通过光纤2连接至其它节点。
本申请实施例提供的一种波长选择开关可应用于ROADM(Reconfigurable Optical Add-Drop Multiplexer，可重构光分插复用器)中。请参阅图2，所述波长选择开关100包括光纤阵列20、主透镜30和空间光调制器10(Spatial Light Modulator，SLM)。光纤阵列20包括输入输出端口，如图2所示，示意性地表达了一个输出端口I和四个输入端口O1、O2、O3和O4，输出端口I和各输入端口O1、O2、O3和O4的位置可以根据具体的应用场景设计，不限于如图2所示的：输出端口I位于中间及输出端口I两侧各设两个输入端口的架构。输出端口I射出的光信号为入射光(即图2中光纤阵列20和主透镜30之间的，且箭头指向主透镜30的实线所表达的部分光线)，主透镜30用于将入射光变换为准直光(即图2中主透镜30和空间光调制器10之间的，且箭头指向空间光调制器10的实线所表达的部分光线)。空间光调制器10为相位型SLM，用于改变光信号的相位。准直光进入所述空间光调制器10后，空间光调制器10对光束进行反射及偏转。被偏转反射的光为出射光(即图2中主透镜30和空间光调制器10之间的，且箭头指向主透镜30的虚线所表达的部分光线)，所述出射光经过所述主透镜30，被聚焦耦合至输入端口O4。
本申请提供的空间光调制器还可以用于其它的应用场景，例如：N×N WSS、ADWSS、激光雷达、激光显示等等。
本申请提供的空间光调制器为相位型空间光调制器，针对光信号的相位做调节，不改变光信号的强度。如图3至图6所示，图3和图4分别描述了背板110的截面示意图和平面示意图，图5和图6分别描述了空间光调制器10的截面示意图和平面示意图。本申请提供的空间光调制器10包括背板110和形成于背板上的像素阵列120。
如图3和图4所示，背板110内设置多个呈阵列分布的驱动电路111，例如：驱动电路111呈M行N列的排列方式。驱动电路111为制作在背板110内的电路架构，可以形成在背板110内的某一层或某些层结构上，也可以为单独的电子元件内嵌在背板110中。背板110可以为陶瓷基板或其它材质的基板，背板110包括相对设置的正面S1和背面S2，正面S1用于形成像素阵列120，也可以理解为正面S1为制作相位调节单元的面。正面S1设有电连接驱动电路111的接口112，每个驱动电路111对应两个接口112，其中一个接口112电连接至驱动电路111的参考电压，另一个接口112电连接至驱动电路111的地。此接口112可以为 焊盘结构，焊盘的表面可以与正面S1共面，使得正面S1保持为平面，容易制作像素阵列120。
结合图5和图6，像素阵列120包括多个呈阵列分布(例如M行N列)的像素单元121，像素阵列120制作在背板110的正面S1，各像素单元121互连为一体，相邻的像素单元121之间无缝连接。
参阅图7和图8，各像素单元121的架构相同，各像素单元121包括驱动电路111(位于背板110内)、相位调节单元20(形成在背板110正面S1)、电极30(形成在相位调节单元20中)和电连接部40(形成在相位调节单元20中)。相位调节单元20为固态层结构架构。从结构方面讲，相邻的相位调节单元20互连为一体，相邻的相位调节单元20之间无间隙，即多个阵列分布的相位调节单元20在背板110的正面S1上一个挨着一个地紧密排列，使得空间光调制器10容易实现小型化的设计。从制作工艺方面讲，各相位调节单元20通过同样的制作步骤形成，每个制作步骤均同时形成所有的相位调节单元20的某一层结构，图8示意性地表达了各像素单元121均包括多层层结构，且所有的像素单元121的层数相同，且各层均互连形成同一层架构，特别可以看到，所有的电极30均位于同一层，这样的架构使得制作工艺简单容易，节约制作成本。本申请在背板上制作相位调节单元20后不需要在相邻的相位调节单元20之间挖设沟道，制作成本低，良率高。
由于各像素单元121的架构相同，如下将其中一个像素单元121的细节架构展开描述。
参阅图9至图12，相位调节单元20包括依次层叠设置在所述背板110上的下腔镜21、腔层22和上腔镜23，所述下腔镜21位于所述腔层22和所述背板110之间。本申请提供的空间光调制器中的相位调节单元20的为固态的层结构架构，一种实施方式中，相位调节单元20为非对称FP(Fabry-Perot，法布里-帕罗)微腔，其中的下腔镜21、腔层22和上腔镜23也都为具有多层层结构(或膜结构)的架构。下腔镜21为多层层结构(或膜结构)构成的反射层或为金属反射层，下腔镜21的反射率接近或为1，不同像素单元121之间的对应层结构可连通为同一层。也就是说，在背板110上制作下腔镜21的过程中，可以直接做一层大面积的反射层，此大面积的反射层可以覆盖多个阵列分布的像素单元121，每个像素单元121对应的大面积的反射层的部分区域为该像素单元的下腔镜21。腔层22和上腔镜23的材料为具有电光效应的材料，例如BTO(BaTiO3，Barium titanate，钛酸钡)、Si(硅，例如Si纳米材质)，此类材料的响应速率在GHz量级。可以通过在上腔镜23表面制作Si纳米线、纳米微柱等结构的方式形成非对称FP微腔结构。通过设计非对称FP微腔的结构，可以实现光信号的波前幅度变化接近0的相位调制。本申请提供的空间光调制单元能够对光信号进行纯相位调制，不改变光强度。
参阅图5和图6，相位调节单元20可以分为主体区域A和边缘区域B，边缘区域B位于主体区域A的外围，并包围主体区域A，如图5和图6所示，主体区域A为虚线框内的部分，图6可以看出，主体区域A为方形的区域，边缘区域B围绕主体区域A，为主体区域A外部的框形区域。
本申请提供的相位调节单元20为一体式结构，其中的主体区域A和边缘区域B的划分并不意味着相位调节单元20可以被分割为两部分，一种实施方式中，可以理解为：主体区域A是设置电极30的区域，电极30的设置不能覆盖相位调节单元20的所有的区域，而要将边缘区域B预留出来，即边缘区域B不设置电极30，但可以在边缘区域B设置电连接部40。
主体区域A相当于相位调节单元20的功能区域，电极30设置在主体区域A内，电连接部40可以位于边缘区域，当为电极加载电压时，产生的驱动电场也位于主体区域内，这样只 改变主体区域的折射率，主体区域对光信号进行相位调节，而边缘区域由于没有驱动电场，不会对光信号产生影响。这样，相邻的像素单元的主体区域之间通过边缘区域相隔，使得相邻的像素单元之间对光信号的相位调节不会产生串扰。其它的实施方式中，电极30也可以设置在主体区域A和边缘区域B，电连接部40位于边缘区域，电连接部40之间的区域为主体区域A，当加载电压时，只有主体区域A内的部分电极30产生驱动电场。总之，本申请要保证驱动电场分布在主体区域A内，而边缘区域B内不分布驱动电场，这样使得相邻的像素单元之间的驱动电场是彼此隔离的，防止相邻的像素单元之间对光信号产生串扰。
其它实施方式中，电极30也可以不只布置在主体区域A，电极30也可以延伸至边缘区域B，但是通过电连接部40的配置，使得电极30在通电的状态下，只在主体区域A产生驱动电场，也能够保证相邻的像素单元之间的驱动电场的隔离，从而相邻的像素单元之间对光信号的相位调节不会产生串扰。
所述电极30包括彼此绝缘的第一电极和第二电极,所述电极30位于所述相位调节单元20的内部或表面，所述电极30位于所述下腔镜21背离所述背板110的一侧；电极30可以形成于相位调节单元20，具体而言，在制作相位调节单元20的过程中可以同时制作电极30，电极30形成在相位调节单元20中间的某一层或某些层中，或者形成在相位调节单元20的表层，也可以在制作好的相位调节单元20上设置电极30。所述电连接部40包括第一电连接部41和第二电连接部42，电连接部40电连接所述电极30和所述驱动电路111，第一电连接部41电连接在第一电极和驱动电路111之间，第二电连接部42电连接在第二电极和驱动电路111之间，以在所述第一电极和所述第二电极之间形成驱动电场，调节所述相位调节单元20的折射率。
对于电极30的设置，可以设置为单层架构，如图9至图12所示实施例。
对于单层架构的电极30，可以理解为，电极30排布在第一面S1上，即共面设置，在制作过程中，第一电极和第二电极制作在同一层的层结构上。所述相位调节单元20包括多个依次层叠设置的层结构，第一面S1为其中一个所述层结构的表面。具体而言，下腔镜21、腔层22和上腔镜23均可以为一层或多层的层结构依次层叠的架构，第一面S1只要不设置在下腔镜21中。
如图9所示，第一面S1可以位于腔层22，图9所示的第一面S1的位置为制作腔层22的最底层的表面，即腔层22邻接下腔镜21的表面，当然，第一面S1也可以为腔层22的其它层的表面。电极30在第一面S1上，电极30可以覆盖第一面S1的部分区域，电极30也可以覆盖第一面S1的全部区域。
如图10所示的实施例，此实施例与图9所示的实施例的区别在于：第一面S1为制作腔层22的某个中间层的表面，电极30位于腔层22的中间层。
如图11所示的实施例，此实施例与图9所示的实施例的区别在于：第一面S1为制作上腔镜23的最底层的表面(即上腔镜23邻接腔层22的表面)，电极30位于上腔镜23的底层。
如图12所示的实施例，此实施例与图9所示的实施例的区别在于：第一面S1为制作上腔镜23顶层的表面，电极30位于上腔镜23的顶层，即电极30位于上腔镜23背离腔层22的一侧的层结构中。
对于单层架构的电极30，电极30的具体结构形态可以为叉指电极架构，或者，平行线电极架构。
电极30呈叉指电极架构的一种可能的实施方式为：参阅图13，电极30位于主体区域A 中，电连接部40位于边缘区域B中。电极30包括第一电极31和第二电极32，电连接部40包括第一电连接部41和第二电连接部42，在第一面S1上显示的为第一电连接部41的焊盘部分及第二电连接部42的焊盘部分，可以理解的是，第一电连接部41还包括传导部(图13只显示了焊盘部分，未显示传导部)在垂直于第一面S1的方向连接在焊盘和驱动电路之间，同样第二电连接部42还包括传导部在垂直于第一面S1的方向电连接在焊盘和驱动电路之间。所述第一电极31包括第一主线311和从所述第一主线311一侧延伸而出的至少两个第一分支312，所述第二电极32包括第二主线321和从所述第二主线321的一侧延伸而出的至少两个第二分支322。所述第一主线311和所述第二主线321相对设置，所述第一分支312和所述第二分支322构成叉指架构，叉指结构可以理解为：第一分支312插入相邻的两个第二分支322之间，第一分支312和第二分支322交替排列，排列规律可以为：一个第一分支312、一个第二分支322、一个第一分支312……。图13所示的实施例中，第一分支312和第二分支的数量均为五个。所述第一分支312和所述第二分支322呈直线状，每个第一分支312与相邻的第二分支322平行且部分重叠。具体而言，第一分支312和第二分支322可以平行设置且均垂直于第一主线311或第二主线321。
第一分支312和第二分支322可以与第一主线311和第二主线321之间形成夹角，夹角为90度的情况下为前述垂直的状态，夹角也可以为小于90度，例如60度、75度等，本申请不做限定。
参阅图14，图14所示的实施方式与图13所示的实施方式的区别在于：第一分支312和第二分支322呈曲线状，第一分支312和第二分支322的形状具体可以为S形、C形、弧形、螺旋形或其它不规则的曲线形状。
其它实施方式中，第一分支312和第二分支322可以为多段直线的组合，例如L形，或者直线和曲线的组合等各种方案，本申请不做限定。
参阅图13和图14，所述第一连接部41连接至所述第一主线311，所述第二连接部42连接至所述第二主线321，所述第一连接部41和所述第二连接部42分布在所述电极30的相对的两侧。具体而言，第一连接部41和第二连接部42位于相位调节单元20的边缘区域B内，第一连接部41和第二连接头部42可以为不透光的材质，例如金属材质，不透光的材质具有成本低的优势，将电连接部40设置在边缘区域B，边缘区域B为相邻的相位调节单元20之间的主体区域A之间的隔离区，电极30通电状态下，边缘区域B内不会形成驱动电场，因此边缘区域B不需要透光，可以将不透光的电连接部40设置在边缘区域B，避免了将不透光的电连接部40设置在主体区域A内，这样即保证相位调节单元20的主体区域A的透光率，提升透光率，又能够保证相邻的相位调节单元之间的隔离，以及实现空间光调制器的低成本。
电极30呈平行线电极架构的一种可能的实施方式为：参阅图15，第一电极31和第二电极32从所述第一面S1上的第一位置L1并排同步延伸至所述第一面S1上的第二位置L2，第一电极31和第二电极32之间绝缘间隔。图15所示的实施方式中，第一电极31和第二电极32均为一条主线的架构，不存在其它的分支。为了满足驱动电场的需求，本申请也可以在图15所示的实施方式的基础上，在第一电极31和第二电极32的主线架构的基础上增加分支的设计。具体而言，所述第一电极31和所述第一电极32延伸的路径为回字形、蛇形或螺旋形。第一电极31和第二电极32延伸的路径包括多段连续相接的直线段、或者连续的曲线。此架构下，电连接部40的第一连接部41和第二连接部42可以均位于所述第一位置L1,所述第一位置L1位于所述电极30的外边缘的位置。第一位置L1位于相位调节单元20的边缘区域B 内。
其它实施方式中，也可以将电连接部40设置在第二位置L2，由于第二位置L2在主体区域A内，需要将电连接部40设置为透光状态，或者电连接部40虽然为不透光材质，但尺寸合适，不会影响主体区域A的透光率。
其它实施方式中，第一电连接部41和第二电连接部42可以分别布置在第一位置L1和第二位置L2。
图13至图15所示的实施方式中，第一电极31和第二电极32的数量是相同的，均为一个。其它实施方式中，对于共面的单层电极架构，第一电极31和第二电极32的数量也可以为至少两个，例如两个第一电极配合两个第二电极，对应的电连接部40的数量也随之增加即可。或者，第一电极31的数量和第二电极32的数量也可以不同，例如一个第一电极31搭配两个第二电极32构成电极架构。
参阅图16，一种可能的实施方式中,所述电极30设置在所述上腔镜23背离所述腔层22的表面，本实施方式中，电极30为叉指电极架构，具体结构类似图13所示的实施例。图16所示的实施方式中，第一电极31和第二电极32突出于上腔镜23的顶面，第一电连接部41和第二电连接部42也突出于上腔镜23的顶面。第一电极31和第二电极32之间及第一电极31和第二电极32的周围区域为空气。
参阅图17，本实施方式与图16所示的实施方式的区别在于：所述第一电极31和所述第二电极32之间设有电光介质50,电光介质50的材料可以为：如EO Polymer、LiNbO3、BTO等。所述第一电极31和所述第二电极32的外围也可以设置电光介质50。本实施方式中，第一电连接部41和第二电连接部42亦被电光介质50包围。可以理解为电极30嵌入电光介质50内，电极30的顶面和电光介质50的顶面可以共面，电极30的顶面也可以突出于电光介质50的顶面。“顶面”指的是电极30和电光介质50远离上腔镜23的表面。本实施方式将电极30设置在上腔镜23背离腔层22的表面，通过电极30结合电光介质50的架构，在上腔镜23的表面形成电极30的同时，亦可以具有“在上腔镜表面设置突出结构以实现非对称结构”对应的功能，即电极30和电光介质50构成了非对称结构，藉此，本实施方式中，相位调节单元20能够实现仅对光信号的相位调节，不影响光信号的强度。
图17所示的实施方式，具体可以理解为：上腔镜23为厚度为100nm的SiO2层，本实施方式中，上腔镜23可以看作是一层层结构，其材料为单一的SiO2，其它实施方式中，上腔镜23也可以为多层层结构，相邻的两层的材料不同，例如一层SiO2层、一层掺杂Si层、一层SiO2层、一层掺杂Si层……类似这样的排列。在上腔镜23的表面形成厚度为250nm的掺杂Si层，掺杂Si层用于制作电极30，掺杂Si层刻蚀得到Si纳米线(即电极30中的第一分支和第二分支部分)，其宽度为200nm，长度为1.8um，相邻纳米线间的中心间隔为400nm。再在相邻纳米线间的中心间隔填充EO-Polymer，将EO-Polymer完整填充于Si纳米线之间和外围，EO-Polymer亦形成在上腔镜23的表面，Si纳米线和EO-Polymer共同形成同一层。相邻纳米线之间形成隔间，相邻的隔间内的EO-Polymer极化方向相反。奇数序号(1,3,5)的Si纳米线(即第一电极的第一分支)通过水平的下方Si条形结构(即第一电极的第一主线)连接(即构成第一电极)，并接触到金属过孔的顶电极(即第一电连接部的焊盘)；偶数序号(2,4,6)的Si纳米线(即第二电极的第二分支)通过水平的上方Si条形结构(即第二电极的第二主线)连接(即构成第二电极)，并接触到另一个金属过孔的顶电极(即第二电连接部的焊盘)。水平的Si条形结构(即第一主线和第二主线)的宽度为200nm，长度为2um。为 了避免短路，奇数序号(1,3,5)的Si纳米线(即第一分支)与水平的上方Si条形结构(即第二主线)的间距为100nm；偶数序号(2,4,6)的Si纳米线(即第二分支)与水平的下方Si条形结构(即第一主线)的间距为100nm。
参阅图18和图19，电极30设置在上腔镜23背离腔层22的表面的情况下，所述电极30的表面设有多个微柱结构60，所述微柱结构60用于抑制对光信号的强度调制，使得本申请提供的空间光调制器倾向于纯相位调制。图18为在第一电极31和第二电极32设置微柱结构60的平面示意图，其中第一电极31和第二电极32为叉指电极架构。图19为在图17的实施方式的基础上，增加了微柱结构60的架构。图19所示的实施方式中，各微柱结构60呈方块状，分布在各电极的分支上，微柱结构60也可以为其它的形状，例如圆柱形、球形等。一种实施方式中，微柱结构60在电极30上可以均匀分布。其它实施方式中，微柱结构60在电极30上也可以为不同的区域具有不同的密度的分布方式，例如靠近相位调节单元中心区域分布的微柱结构60的密度小于靠近相位调节单元边缘区域的微柱结构60的密度。
单层架构的电极30的第一电极31和第二电极32可以为纳米线结构，材料如掺杂Si。
前述实施方式中，相位调节单元内可以包括一层单层架构的架构(例如叉指电极架构和平行线电极架构)。本申请并不限定单层架构的电极的层数做限定，也就是说，在一个像素单元的相位调节单元内，可以只包括一层单层架构的电极，一层单层架构的电极可以独立工作，产生驱动电场，改变相位校正单元的折射效率，或耦合效率，从而调节反射光的相位。在一个像素单元的相位调节单元内也可以包括至少两层单层架构的电极，每层单层架构的电极彼此独立，多层单层架构的电极可以电连接至同一个驱动电路。驱动电路可以同时驱动所有的单层架构的电极，也可以根据需要选择性地驱动部分单层架构的电极。
单层架构的电极的电场分布及折射率变化，请参阅图24，其中左侧的图表示了第一电极和第二电极之一者连接至参考电压，另一个接地，通电状态下，在第一电极和第二电极之间形成驱动电场，图中第一电极和第二电极之间带箭头的线表示的是电场分布。右侧的图为左侧图的虚线圈部分的放大示意图，并标示了折射率椭球，表示相位调节单元的电光介质的折射率的变化，不加电时，折射率椭球基本上呈圆形，如右图虚线表示的圆形部分，电光介质折射率为n，电极通电状态下，折射率椭球被拉长，电光介质折射率为n+δn。
对于电极30的设置，也可以设计为多层架构，参阅图20至图23所示各实施方式。
图20为多层架构的电极30的示意图。对于多层架构的电极30，这里的多层指的是至少两层，而且第一电极31和第二电极32均呈面状，且沿第一方向(如图20中双向箭头所指示的方向)依次交替层叠排布，第一方向为下腔镜、所述腔层和上腔镜依次层叠排列的方向，第一方向可以理解为垂直于背板的方向。第一电极31和第二电极32不是位于同一层，而是形成在相位调节单元的不同的层中。可以理解为：对于每个第一电极31和第二电极32，均为膜层结构，呈面状分布在腔层的某一层内，或者上腔镜的某一层。不同的电极30位于不同的层。而且，第一电极31和第二电极32交替层叠排布，即与其中一个第一电极31相邻的层结构中设置的是第二电极32，其中一个第一电极31可以夹设在相邻的两个第二电极32之间。第一电连接部41电连接至第一电极31，第二电连接部42电连接至第二电极32，如图20所示，第一电极31和第二电极32部分重叠，第一电极31的左侧边缘区域未与第二电极32重叠，第二电极32右侧边缘区域未与第一电极31重叠，第一连接部41连接在第一电极31的最左侧的边缘位置，第二连接部连接在第二电极32的最右侧的边缘位置。概括为：所述第一电极30未与所述第二电极30重叠的部分连接至所述第一连接部41，所述第二电极30未与 所述第一电极30重叠的部分连接至所述第二连接部42。第一电极31和第二电极32可以为相互平行的层结构。
参阅图21，一种可能的实施方式中,所述电极30位于所述腔层22内，第一电极31和第二电极32均设置在腔层22内。将电极30制作在腔层22内的好处是：制作工艺相对简单，因为腔层22为单一材料，不用考虑是否产生透射率或反射率，对于腔层22而言，是通过其材料本身控制透射率，不是通过其中的具体的结构控制，电极30虽然改变腔层22的结构，但对透射率影响较小，因为透射率通过腔层22本身的材料控制的。图21所示的下腔镜21和腔层22的尺寸不同，为了显示电极30的结构，图21只显示了部分腔层22和部分上腔镜23，图21中的显示状态并不代表相位调节单元中的下腔镜21和腔层22的尺寸是不同的。
图21所示的实施方式中，一种具体的架构为：腔层22包括交替层叠分布且分别为两层的ITO薄膜和LiNbO3薄膜，具体为一层LiNbO3薄膜、一层ITO薄膜、一层LiNbO3薄膜、一层ITO薄膜，这样的交替层叠分布，其它实施方式中，腔层22的层数可以为三层、四层或更多的层数，相邻两层的材质不同。其中的ITO薄膜为电极30，LiNbO3薄膜为电极30之间的电光介质。每层LiNbO3薄膜的厚度为400nm，每层ITO薄膜的厚度为50nm。ITO薄膜的长度(垂直于纸面)为4um，宽度(平行于纸面)为2um。奇数序号(1,3)的ITO薄膜(构成第一电极)与左侧垂直的金属通孔(即第一电连接部)相连通；偶数序号(2)的ITO薄膜(构成第二电极)与右侧垂直的金属通孔(即第二电连接部)相连通。ITO薄膜之间的区域定义为层间，相邻两层间的LiNbO3薄膜的极化方向相反。
图21所示的实施方式中，上腔镜23背离腔层22的表面，即相位调节单元背离背板的表面，设有突出结构70，即突出结构70形成在上腔镜23的最顶层，也可以理解为，突出结构70位于上腔镜23背离腔层22的一侧，即突出结构70为独立于上腔镜23的结构。所述突出结构70的设置使得相位调节单元构成非对称架构，用于抑制对光信号的强度的调制，使得本申请提供的空间光调制器倾向于纯相位调制。图21中所示的突出结构70为长方体状，突出结构70也可以为其它形态，例如圆柱状，方块状，球状等等。图21所示的实施方式中，第一电连接部41和第二电连接部42分别位于电极30相对的两侧。本实施方式中，电极30包括两个第一电极31和两个第二电极32。
参阅图22，本实施方式将电极30制作在上腔镜23内，原理同腔层22制作电极30的原理。本实施方式中，电极30包括两个第一电极31和一个第二电极32，第一电连接部41电连接至两个第一电极31，第二电连接部42电连接至一个第二电极32。与图21所示的实施方式相同，本实施方式中，上腔镜23背离腔层的表面亦设有突出结构70。
参阅图23，本实施方式将部分电极30制作在腔层22内，部分电极32制作在上腔镜23内。具体而言，如图23所示，腔层22内包括一层第一电极31和一层第二电极32，上腔镜23内也包括一层第一电极31和一层第二电极32。第一电连接部41电连接至所有的第一电极31，第二电连接部42电连接至所有的第二电极32。与图21所示的实施方式相同，本实施方式中，上腔镜23背离腔层的表面亦设有突出结构70。
对于单层电极架构，且电极30位于非上腔镜23表层(即单层架构的电极30设置在上腔镜23内的某一层、或腔层22内的某一层、或上腔镜23和腔层22之间的某一层)的实施方式中，上腔镜23背离腔层22的表面亦可以设有突出结构(类似图21-图23所示的突出结构)，作用亦是为了使得相位调节单元20构成非对称架构，用于抑制对光信号的强度的调制，使得本申请提供的空间光调制器倾向于纯相位调制。
一种可能的实施方式中,对于电极30为多层的架构，所述第一电极30的数量为两个或两个以上,所述第二电极30的数量为两个或两个以上。由于第一电极30和第二电极30通电状态下会产生电场，将电极30数量设置为两个或两个以上，可以使用较小的电压就能够产生需要的电场。可以将第一电极30或第二电极30的数量控制在2-3层，因为若层数太多，例如超过3层，从制作的角度来讲，较难实现。因此，电极30最多的层数可以为6层，其中第一电极30为3层，第二电极30为3层。
每层电极30的制作工艺可以为：
溅射工艺，通过溅射的方式在相位调节单元的某一层的表面制作电极层，电极层的材质可以为掺杂硅；
光刻工艺，在电极层上涂覆光刻胶层，并通过光刻工艺将光刻胶层形成预设图案；
刻蚀工艺，在电极层上形成所述预设图案；
平坦化工艺，对图案化的电极进行平坦化制作，具体可以通过抛光的方式实现，例如：化学机械抛光工艺。
第一电极31和第二电极32的层数不一定相同，例如：一种可能的实施方式中，电极30包括一层第一电极31和两层第二电极32，或者两层第二电极32和三层第一电极31。
多层架构的电极30的电场分布及折射率变化示意图，请参阅图25，图25示意性地表达了两层第一电极和一层第二电极的架构，两层第一电极连接至驱动电路的参考电压，一层第二电极接地，通电状态下，第二电极两侧的层间内形成驱动电场，且这两个层间内的驱动电场方向相反。
对于第一电连接部41和第二电连接部42，包括焊盘和连接在焊盘和驱动电路之间的传导部，焊盘可以与电极30位于同一层结构中，传导部可以为过孔引线的形式。具体而言，制作过程中，可以在焊盘所在的层结构和背板110之间形成过孔，在过孔内设金属导线，或者设置金属导电柱，或者通过电镀的方式，在过孔内壁形成金属层，构成传导部。
本申请提供的空间光调制器中，电极30和电连接电极30和驱动电路的电连接部40均与集成在相位校正单元内，即在制作相位校正单元的过程中，能够同步在相位校正单元内制作出电极30和电连接部40。电极30和电连接部40无需在制作相位校正单元的步骤之外单独制作，也不单独占用相位校正单元之外的空间。这样的情况下，相位校正单元之间可以无缝连接为一整体，而且，电极30通电后产生的电场直接形成在相位校正单元内，无损耗，可以使用较小的电压即可以产生需要的电场强度。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以所述权利要求的保护范围为准。

Claims (16)

  1. 一种空间光调制器，其特征在于，包括：
    背板，内设驱动电路；
    相位调节单元，包括依次层叠设置在所述背板上的下腔镜、腔层和上腔镜，所述下腔镜位于所述腔层和所述背板之间；
    电极，包括彼此绝缘的第一电极和第二电极,所述电极位于所述相位调节单元的内部或表面，且位于所述下腔镜背离所述背板的一侧；和
    电连接部，电连接所述电极和所述驱动电路，以在所述第一电极和所述第二电极之间形成驱动电场，调节所述相位调节单元的折射率。
  2. 根据权利要求1所述的空间光调制器,其特征在于,所述驱动电路、所述相位调节单元、所述电极及所述连接部共同构成一个像素单元,所述空间光调制器包括多个所述像素单元,且多个所述像素单元呈阵列分布,相邻的所述像素单元的所述相位调节单元之间无缝连接。
  3. 根据权利要求1或2所述的空间光调制器，其特征在于，所述电极排布在第一面上，
    所述第一面为所述上腔镜背离所述腔层的表面；或者
    所述相位调节单元包括多个依次层叠设置的层结构，所述第一面为其中一个所述层结构的表面。
  4. 根据权利要求3所述的空间光调制器，其特征在于，所述第一电极包括第一主线和从所述第一主线一侧延伸而出的至少两个第一分支，所述第二电极包括第二主线和从所述第二主线的一侧延伸而出的至少两个第二分支，所述第一主线和所述第二主线相对设置，所述第一分支和所述第二分支构成叉指架构。
  5. 根据权利要求4所述的空间光调制器，其特征在于，所述第一分支和所述第二分支呈直线状；或，所述第一分支和所述第二分支呈曲线状。
  6. 根据权利要求4所述的空间光调制器，其特征在于，所述电连接部包括彼此绝缘隔离的第一连接部和第二连接部，所述第一连接部连接至所述第一主线，所述第二连接部连接至所述第二主线，所述第一连接部和所述第二连接部分布在所述电极的相对的两侧。
  7. 根据权利要求3所述的空间光调制器，其特征在于，所述第一电极和所述第二电极从所述第一面上的第一位置并排同步延伸至所述第一面上的第二位置。
  8. 根据权利要求7所述的空间光调制器，其特征在于，所述电连接部包括彼此绝缘隔离的第一连接部和第二连接部，
    所述第一连接部和所述第二连接部均位于所述第一位置,所述第一位置位于所述电极的外边缘的位置。
  9. 根据权利要求1或2所述的空间光调制器，其特征在于，所述下腔镜、所述腔层和所述上腔镜沿第一方向依次层叠设置，所述第一电极和所述第二电极在所述第一方向上交替层叠排布。
  10. 根据权利要求9所述的空间光调制器，其特征在于，所述电极位于所述腔层内。
  11. 根据权利要求9所述的空间光调制器，其特征在于，所述电连接部包括彼此绝缘隔离的第一连接部和第二连接部，所述第一电极和所述第二电极部分重叠，所述第一电极未与所述第二电极重叠的部分连接至所述第一连接部，所述第二电极未与所述第一电极重叠的部分连接至所述第二连接部。
  12. 根据权利要求9所述的空间光调制器，其特征在于，所述第一电极的数量为两个或两个以上，所述第二电极的数量为两个或两个以上。
  13. 根据权利要求9所述的空间光调制器，其特征在于，所述相位调节单元背离所述背板的表面设有突出结构，所述突出结构用于抑制对光信号的强度调制。
  14. 根据权利要求1或2所述的空间光调制器，其特征在于，所述电极设置在所述上腔镜背离所述腔层的表面，所述电极的表面设有多个微柱结构，所述微柱结构用于抑制对光信号的强度调制。
  15. 根据权利要求1或2所述的空间光调制器，其特征在于，所述电极设置在所述上腔镜背离所述腔层的表面，所述第一电极和所述第二电极之间设有电光介质，或者，所述第一电极和所述第二电极之间以及所述电极的外围均设电光介质。
  16. 一种波长选择开关，其特征在于，包括光纤阵列、主透镜和如权利要求1-15任意一项所述的空间光调制器，所述光纤阵列发现的光束经过所述主透镜后变换为准直光，所述准直光进入所述空间光调制器，所述空间光准直器用于对所述准直光进行反射及偏转形成反射光，所述反射光经过所述主透镜聚集至所述光纤阵列。
PCT/CN2021/095241 2020-08-21 2021-05-21 空间光调制器和波长选择开关 WO2022037151A1 (zh)

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