WO2016106521A1 - 一种波长选择开关 - Google Patents

一种波长选择开关 Download PDF

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Publication number
WO2016106521A1
WO2016106521A1 PCT/CN2014/095399 CN2014095399W WO2016106521A1 WO 2016106521 A1 WO2016106521 A1 WO 2016106521A1 CN 2014095399 W CN2014095399 W CN 2014095399W WO 2016106521 A1 WO2016106521 A1 WO 2016106521A1
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Prior art keywords
lcos panel
port
light
wss
plane
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PCT/CN2014/095399
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English (en)
French (fr)
Inventor
宗良佳
赵晗
Original Assignee
华为技术有限公司
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Filing date
Publication date
Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to EP14909333.8A priority Critical patent/EP3232241B1/en
Priority to PCT/CN2014/095399 priority patent/WO2016106521A1/zh
Priority to CN201480084444.6A priority patent/CN107111063B/zh
Publication of WO2016106521A1 publication Critical patent/WO2016106521A1/zh
Priority to US15/636,941 priority patent/US9977190B2/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
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
    • 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
    • G02B6/29304—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 operating by diffraction, e.g. grating
    • G02B6/29305—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 operating by diffraction, e.g. grating as bulk element, i.e. free space arrangement external to a light guide
    • G02B6/2931—Diffractive element operating in reflection
    • 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
    • G02B6/29379—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 characterised by the function or use of the complete device
    • G02B6/29395—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 characterised by the function or use of the complete device configurable, e.g. tunable or reconfigurable
    • 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
    • G02B6/35—Optical coupling means having switching means
    • G02B6/351—Optical coupling means having switching means involving stationary waveguides with moving interposed optical elements
    • G02B6/3534—Optical coupling means having switching means involving stationary waveguides with moving interposed optical elements the optical element being diffractive, i.e. a grating
    • 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
    • G02B6/35—Optical coupling means having switching means
    • G02B6/354—Switching arrangements, i.e. number of input/output ports and interconnection types
    • G02B6/3544—2D constellations, i.e. with switching elements and switched beams located in a plane
    • G02B6/3548—1xN switch, i.e. one input and a selectable single output of N possible outputs
    • 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
    • G02B6/35—Optical coupling means having switching means
    • G02B6/3586—Control or adjustment details, e.g. calibrating
    • G02B6/3588—Control or adjustment details, e.g. calibrating of the processed beams, i.e. controlling during switching of orientation, alignment, or beam propagation properties such as intensity, size or shape
    • 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
    • G02F1/29—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 position or the direction of light beams, i.e. deflection
    • G02F1/31—Digital deflection, i.e. optical switching
    • 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
    • G02B6/35—Optical coupling means having switching means
    • G02B6/351—Optical coupling means having switching means involving stationary waveguides with moving interposed optical elements
    • G02B6/3512—Optical coupling means having switching means involving stationary waveguides with moving interposed optical elements the optical element being reflective, e.g. mirror
    • 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
    • G02B6/35—Optical coupling means having switching means
    • G02B6/354—Switching arrangements, i.e. number of input/output ports and interconnection types
    • G02B6/3554—3D constellations, i.e. with switching elements and switched beams located in a volume
    • G02B6/3556—NxM switch, i.e. regular arrays of switches elements of matrix type constellation
    • 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
    • G02B6/35—Optical coupling means having switching means
    • G02B6/354—Switching arrangements, i.e. number of input/output ports and interconnection types
    • G02B6/356—Switching arrangements, i.e. number of input/output ports and interconnection types in an optical cross-connect device, e.g. routing and switching aspects of interconnecting different paths propagating different wavelengths to (re)configure the various input and output links

Definitions

  • the present invention relates to the field of communications, and more particularly to a wavelength selective switch.
  • the bandwidth occupied by different signals is no longer limited to 50 GHz or an integer multiple of 50 GHz, but exists in the form of flexible grids (Flexgrid). Changes in the network structure are bound to match the various optical components, including the core switching device Wavelength Selective Switch (WSS).
  • WSS Wavelength Selective Switch
  • the early WSS was mainly an MEMS-based optical engine. However, due to the existence of a certain gap between the micro-mirrors in the MEMS system, when multiple micro-mirrors are required to achieve a wide-spectrum filtering, some pits will be generated between the spectra.
  • LCOS works by loading different voltages on different pixels of the LCOS. Due to the birefringence effect of the liquid crystal, different voltages will correspond to different phase delays, which can form a blazed grating (Blazed grating). )Structure. Since the diffraction angle of the blazed grating depends on the grating period of the blazed grating, it is only necessary to change the grating period corresponding to different positions on the LCOS, that is, the diffraction angle of the incident light can be controlled, so that the diffracted light is output at different ports of the WSS, thereby achieving wavelength selection. Switch function. Because there are millions of pixels on LCOS, and The gap between the pixels is also very small, so Flexgrid filtering can be implemented very flexibly without spectral gaps.
  • FIG. 1 is a schematic structural diagram of a WSS
  • FIG. 1 is a schematic diagram for explaining the cause of crosstalk, and the complete structure of the WSS is not completely drawn.
  • the light incident from the input port passes through a series of processing in the black box (which may include deflection processing, demultiplexing processing, etc.), and is incident on the LCOS panel.
  • the corresponding pixels on the LCOS are required according to the corresponding configuration.
  • the +1 order diffracted light is diffracted to the corresponding output port.
  • an embodiment of the present invention provides a wavelength selective switch.
  • Embodiments of the present invention provide a wavelength selective switch WSS, which includes an optical fiber array, a liquid crystal on silicon LCOS panel, and a lens component, the optical fiber array including a plurality of ports arranged in a row, the plurality of ports including an input port And a plurality of output ports, wherein the outermost two ports of the plurality of ports arranged in a row are respectively a first port and a second port, and an intersection line of the LCOS panel and the first plane is incident on the LCOS panel
  • the angle between the incident light is equal to (90- ⁇ ) degrees
  • the first plane is a plane where incident light incident on the LCOS panel and outgoing light exiting the LCOS panel, the wavelength of the incident light
  • the wavelengths of the emitted light are the same, the ⁇ is less than 15 degrees and the following conditions are met:
  • l 1 is a distance between the input port and the first port
  • l 2 is a distance between the input port and the second port
  • the first port and the (90- ⁇ ) An angle is located on the same side of the incident light
  • an angle between the second port and the (90- ⁇ ) degree is respectively located on two sides of the incident light
  • f is the lens component in the The focal length in a plane.
  • the WSS provided by the embodiment of the present invention can ensure that other diffracted lights other than the +1st order diffracted light do not enter any input port or output port without adding any additional components, thereby achieving crosstalk suppression at low cost.
  • FIG. 1 is a schematic diagram showing the principle of crosstalk generated by WSS in the prior art
  • FIG. 2 is a schematic structural diagram of a WSS according to an embodiment of the present invention.
  • FIG. 3 is a schematic view of a diffracted light exiting region of each stage according to an embodiment of the present invention.
  • FIG. 4 is a schematic diagram of a LCOS panel deflected by a wavelength direction as an axis according to an embodiment of the present invention
  • FIG. 5 is a schematic diagram of a LCOS panel according to an embodiment of the present invention with a port direction as an axis deflection;
  • FIG. 6 is a schematic diagram of a deflection critical state in a scheme in which an LCOS panel is deflected in a wavelength direction as an axis according to an embodiment of the present invention
  • FIG. 7 is a schematic diagram of a diffraction angle of a +1st order diffracted light in a scheme in which an LCOS panel is deflected by a wavelength direction as an axis of the present invention
  • FIG. 8 is a schematic diagram showing a diffraction angle of a +1st order diffracted light in a scheme in which an LCOS panel is deflected by a wavelength direction as an axis according to an embodiment of the present invention
  • FIG. 9 is a schematic diagram of a specific situation of a diffraction angle of a +1 order diffracted light in a scheme in which an LCOS panel is deflected in a wavelength direction as an axis of the present invention
  • FIG. 10 is a schematic diagram of a schematic diagram of a LCOS panel with a port direction as an axis deflection according to an embodiment of the present invention
  • FIG. 11 is still another schematic diagram of a scheme in which an LCOS panel is deflected with a port direction as an axis according to an embodiment of the present invention.
  • connection in the embodiment of the present invention refers to the connection on the optical path, and those skilled in the art may understand that the specific optical device may not necessarily have a physical contact relationship of substantial contact, but the optical devices are The spatial locations and their own device characteristics allow them to form a connection on the optical path.
  • the LCOS-based WSS mainly includes an optical fiber array for input and output, a deflection processing unit for deflection processing, a reflection member for reflecting light, and a lens unit for focusing light for decoupling.
  • Wave splitting and multiplexer, LCOS panel may also include an array of collimators for collimating light behind the fiber array.
  • the deflection processing component may include a beam deformation and polarization conversion component.
  • the lens component may be a lens or a combination of a plurality of lenses.
  • the splitting and multiplexing component may be a grating.
  • Fig. 2 is only a schematic view.
  • the light emitted from the lens member is parallel light rather than scattered light, and Fig. 2 only schematically illustrates that the respective wavelengths are developed in the horizontal direction to schematically draw corresponding light.
  • LCOS-based WSS is a mature technology, and the functions and spatial positional relationships of various components (including components not shown in the drawings) are well known.
  • the embodiment of the present invention only has LCOS that changes with respect to the conventional WSS.
  • the panel section is described in detail, and the other known components and positional relationships are no longer Narration. Meanwhile, for other LCOS-based WSSs other than FIG.
  • the embodiments of the present invention are equally applicable, and only corresponding changes are made to the corresponding LCOS panels, and the functions and positional relationships of other components of the WSS are left as they are.
  • the improved portions of the LCOS panel in the embodiments of the present invention are equally applicable.
  • the straight line formed by the optical fiber array is referred to as the port direction (ie, the vertical direction in FIG. 2) in the embodiment of the present invention, and the respective wavelengths of the light in FIG. 2 are dispersed by the demultiplexing device.
  • the direction of the embodiment is referred to as the wavelength direction (i.e., the horizontal direction in FIG. 2) in the embodiment of the present invention.
  • the existing LCOS-based WSS can realize spectral grid Flexgrid filtering.
  • LCOS when LCOS is used as an optical engine to load a grating, multiple diffraction orders are generated. Among them, the main light intensity level is +1 level, and the level is output as the outgoing light at the destination output port. At the same time, other levels of light will be output as crosstalk signals from other ports, causing co-channel crosstalk effects between WSS ports.
  • the crosstalk size is typically above -25 dB, and the system requires a crosstalk requirement of ⁇ -30 dB or less for a single WSS. Therefore, for existing LCOS-based WSS, it is necessary to find a way to suppress crosstalk.
  • the embodiment of the invention provides a scheme for effectively suppressing port crosstalk.
  • the output port plane of the WSS is divided into a +1 level signal light area and other level crosstalk light areas.
  • the white area in Figure 3 is a +1 order diffracted light area, and the circles in the figure represent the input and output ports on the fiber array.
  • the black areas and the gray areas other than the white areas in Fig. 3 are other order diffracted light distribution areas.
  • crosstalk can be effectively suppressed as long as the +1st order diffracted light falls on the corresponding output port output of the white area in the figure, and the corresponding other order diffracted light is output from the peripheral black or gray area outside the white area.
  • FIG. 4 only the fiber array, the lens component and the LCOS panel are schematically illustrated in FIG. 4, wherein the white and black regions correspond to the white and black in FIG.
  • the area is for illustrative purposes only and does not represent any device.
  • 4 corresponds to the schematic front view of FIG. 2.
  • the signal light is input through the input port in the fiber array, and after the exchange in the WSS, the +1 order diffracted light of the signal light needs to be from the white area in FIG. It is sent to the destination output port, and other levels of diffracted light are sent to the black area, that is, it does not enter any of the output ports, so that crosstalk is not caused.
  • the LCOS panel is oriented in the wavelength direction (horizontal direction in FIG. 2). A small angle of deflection was made.
  • FIG. 5 is a schematic top view corresponding to FIG. 2.
  • the +1 order diffracted light is returned to the corresponding destination in a vertical plane.
  • the output port, while the diffracted light of other orders is sent to the gray area, that is, it does not enter any output port, thereby effectively suppressing crosstalk.
  • the three solid lines returned in the figure represent +1 order diffracted light with different wavelengths at three wavelengths.
  • the LCOS panel is deflected at a small angle with the port direction (vertical direction in FIG. 2) as an axis, and the blazed grating structure on the LCOS panel is a tilted structure.
  • an embodiment of the present invention provides a wavelength selective switch WSS, where the WSS includes an optical fiber array, a liquid crystal LCOS panel, and a lens component, and the optical fiber array comprises a row. a plurality of ports, the plurality of ports including an input port and a plurality of output ports, wherein the outermost two ports of the plurality of ports arranged in a row are a first port and a second port, respectively, the LCOS panel and An angle between an intersection line of the first plane and incident light incident on the LCOS panel is equal to (90- ⁇ ) degrees, the first plane being incident light incident on the LCOS panel and exiting the LCOS panel a plane in which the light is incident, the wavelength of the incident light is the same as the wavelength of the emitted light, and the ⁇ is less than 15 degrees and satisfies the following conditions:
  • l 1 is a distance between the input port and the first port
  • l 2 is a distance between the input port and the second port
  • the first port and the (90- ⁇ ) An angle is located on the same side of the incident light
  • an angle between the second port and the (90- ⁇ ) degree is respectively located on two sides of the incident light
  • f is the lens component in the The focal length in a plane.
  • the focal lengths of the lens components in different directions may be the same or different.
  • the corresponding f refers to the focal length of the lens component in the port direction, that is, in the first plane. The focal length inside.
  • the B 1 is equal to ⁇ +arctan(l 3 /f), when the objective output port of the + 1st -order diffracted light and the (90- ⁇ ) degree are respectively located on both sides of the incident light
  • the B 1 is equal to ⁇ -arctan (l 3 /f)
  • the l 3 is a distance between the destination output port and the input port.
  • the ⁇ is less than 5 degrees.
  • the blazed grating structure on the LCOS panel is configured to adjust a diffraction angle of each of the diffracted lights in the emitted light, and the first plane is parallel to a line where the plurality of ports arranged in a row are located .
  • the WSS further includes a deflection processing component, a reflection component, and a wave splitting component.
  • the multiple ports of this embodiment may include one input port and multiple output ports, and may also include multiple input ports and multiple output ports.
  • the following embodiment takes an input port and a plurality of output ports as an example.
  • the case of each input port is the same as that of one input port and a plurality of output ports.
  • the input ports may be located in the middle of a plurality of ports arranged in a row, or may be located at both ends of a plurality of ports arranged in a row.
  • an embodiment of the present invention provides FIG.
  • Conventional LCOS panels are generally perpendicular to the incident light, while in Figure 6, the LCOS panel is at an angle of (90-theta) degrees to the incident light.
  • ⁇ needs to be greater than a certain value.
  • the ⁇ value of the critical condition is given, and only the deflection angle of the LCOS panel is greater than the ⁇ value, so that the +1 order diffracted light enters the corresponding destination output port of the optical fiber array, and the 0-order diffracted light and the +2 level The diffracted light is outside the white area.
  • Figure 6 shows a schematic diagram of the corresponding critical state, when the LCOS panel is at an angle of (90- ⁇ ) degrees with the incident light, because of the diffraction angle of the adjacent order diffracted light at a small angle diffraction angle.
  • l 1 is the distance between the input port and the leftmost outermost output port in FIG. 6, and l 2 is the distance between the input port and the rightmost outermost output port, and f is the lens component The focal length in the first plane.
  • the 0th-order diffracted light is obviously not sent to the output port, and the +2 order diffracted light is just transmitted to the outermost port on the left side. Therefore, as long as the corresponding ⁇ value is larger than this critical value, the +2 order diffracted light is sent to the black area in Fig. 6, and does not enter any port, thereby effectively achieving crosstalk suppression.
  • the ⁇ value should be selected as small as possible, and the general ⁇ value is not more than 15 degrees.
  • the value of ⁇ is no more than 10 degrees, or no more than 5 degrees, or no more than 3 degrees.
  • ⁇ is the incident angle of the incident light
  • B m is the diffraction angle of the m-th order diffracted light
  • B 1 is equal to ⁇ + arctan (l 3 /f).
  • the B 1 is equal to ⁇ -arctan (l 3 /f).
  • the l 3 is a distance between the destination output port and the input port.
  • the port of the WSS in the embodiment is 1 ⁇ 4, and the two ports on the left and right sides of the input port, the adjacent port spacing is 250 um; the focal length of the lens is 75 mm.
  • the port of the WSS in the embodiment is 1 ⁇ 4, and the two ports on the left and right sides of the input port, the adjacent port spacing is 250 um; the focal length of the lens is 75 mm.
  • f 75 mm
  • the value of the critical state of ⁇ is determined to be 0.573°. Then, according to the range of values of ⁇ , the specific value of ⁇ can be determined.
  • ⁇ can be set to 0.6°, and the LCOS panel is rotated to the corresponding angle.
  • the wavelength value is 1.55 um
  • the grating period of the structure is: 56.2um; 63.9um; 88um; 109.6um.
  • the grating period of the stroboscopic grating structure on the LCOS panel corresponding to different wavelengths and different output ports can be obtained, and the output port, wavelength, and grating period are output.
  • the WSS wavelength selection switching function can be realized.
  • the pixel of a particular wavelength of input light input from a particular input port is incident on the LCOS panel.
  • the pixel or a plurality of pixels is a collection of a series of liquid crystals. Due to the birefringence effect of the liquid crystal, a blazed grating structure is formed under the action of an applied voltage. The grating period of the blazed grating structure can be adjusted by adjusting the corresponding applied voltage.
  • the grating diffraction equation ⁇ ⁇ /(sin ⁇ +sinB 1 )
  • the incident light wavelength ⁇ , and the incident angle ⁇ are all determined, the corresponding +1 order diffraction angle is the desired diffraction of the signal light.
  • the angle B 1 also determines that the diffracted light exiting is returned to the fiber array output through the lens component.
  • the +1st-order diffracted light has a corresponding displacement on the straight line where the optical fiber array is located, and the displacement can be adjusted by adjusting the corresponding applied voltage.
  • the diffracted light can be correspondingly The destination output port output.
  • the WSS provided by the embodiment of the invention does not need to add any additional components, and only needs to deflect the position of the LCOS panel to ensure that other diffracted lights other than the +1 order diffracted light do not enter any input port or output port. Thus, crosstalk suppression is achieved at low cost.
  • the ⁇ is less than 5 degrees, and may be, for example, 1 degree, 1.5 degrees, 2 degrees, 3 degrees, or 4 degrees.
  • the blazed grating structure on the LCOS panel is used to adjust a diffraction angle of each of the diffracted lights in the exiting light, and the first plane is parallel to the straight line.
  • the WSS further includes a deflection processing component, a reflection component, and a wave splitting component.
  • the LCOS panel is deflected at a small angle with the port direction (vertical direction in FIG. 2) as an axis, and the blazed grating structure on the LCOS panel is a tilted structure.
  • FIG. 10 corresponds to FIG.
  • the white frame and the gray frame behind the fiber array in Fig. 10 correspond to the white frame and the gray frame in Fig. 3, and do not represent any devices, and are only used to illustrate the diffracted light exit range.
  • the LCOS panel performs a ⁇ degree rotation with the port direction as the axis (the vertical direction in Fig. 2). If only the rotation of the LCOS panel is performed without other processing, all of the diffracted light should be emitted in the direction of the 0th order diffracted light in FIG.
  • part (a) is for indicating the case of diffracted light of each stage returned at the fiber array port in the conventional WSS.
  • the LCOS panel in part (a) does not undergo any deflection, and the LCOS-like blazed grating is not disposed on the LCOS.
  • the levels shown in part (b) of Figure 11 are obtained from the ray array port.
  • the diffracted light is emitted. If only the LCOS panel is deflected without modifying the blazed grating structure on a conventional LCOS panel, the diffracted diffracted light of each stage as shown in part (c) of Figure 11 can be obtained from the ray array port.
  • the LCOS panel is rotated, and the strobo-like grating structure on the LCOS panel is modified accordingly, so that the parts of the ray array port can be obtained as shown in part (d) of FIG. Diffracted light.
  • the +1 order diffracted light is outputted from the corresponding port, and the other orders of diffracted light avoids the respective ports in the fiber array, thereby effectively suppressing crosstalk. Further, by adjusting the grating period of the stroboscopic grating structure in the port direction on the LCOS panel, the displacement of the corresponding +1 order diffracted light in the port direction can be adjusted, thereby allowing the +1 order diffracted light to be used for the corresponding purpose. Output port output.
  • an angle between the LCOS panel and the first plane is equal to (90- ⁇ ) degrees, and the first plane is incident light incident on the LCOS panel and +1 order diffraction of the LCOS panel.
  • the plane where the light is located That is, the LCOS panel in Fig. 10 is deflected by the angle ⁇ .
  • the WSS provided by the embodiment of the invention does not need to add any additional components, and only needs to deflect the position of the LCOS panel and configure the corresponding blazed grating structure to ensure other diffractions other than the +1 order diffracted light. Light does not enter any input port or output port, thereby achieving crosstalk suppression at low cost.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Nonlinear Science (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Liquid Crystal (AREA)
  • Optical Couplings Of Light Guides (AREA)
  • Mechanical Light Control Or Optical Switches (AREA)

Abstract

本发明实施例提供的WSS，无需增加任何额外部件，仅需对LCOS面板进行相应的旋转，即可保证除+1级次衍射光外的其他衍射光不会进入任何输入端口或输出端口，从而低成本地实现了串扰抑制。

Description

一种波长选择开关 技术领域
本发明涉及通信领域，更具体地，涉及一种波长选择开关。
背景技术
网络流量的持续增长，推动波分复用系统的单通道比特速率从十多年前的10G逐渐发展到40G、100G乃至未来的400G以及1T。对于单通道速率为100G以下的网络系统，传统的50GHz频谱间隔能够满足需求。然而，当比特速率达到400G、1T乃至更高时，其占有的频谱宽度将超过50GHz。因此，在现有网络中，当承载一个400G及以上速率的信号时，需要将一个高速率的信号分成多个低速率的信号，例如将一个400G的信号分成四个100G的信号，每一个100G的信号均用固定的50GHz频带来承载。这在网络实现上虽然行得通，但与一个连续的400G信号相比，势必会造成频谱利用率的下降。
因此，为了提高网络频谱资源利用率，一种全新的网络应运而生——“可变带宽光网络”。其中，不同信号所占的带宽不再局限于50GHz或者是50GHz的整数倍，而是以灵活间隔(Flexgrid)的形式存在。网络结构的改变势必需要各个光学组件与之相配，这其中就包括核心交换器件波长选择开关(Wavelength Selective Switch，WSS)。早期的WSS主要为基于微机电系统的光学引擎，但由于微机电系统中各个微镜之间存在着一定的间隙，当需要多个微镜实现一个宽谱滤波时，频谱之间会产生一些凹槽，因此无法满足滤波谱宽的“Flexgrid”需求。鉴于此，业界提出了一种新的基于硅基液晶(Liquid Crystal On Silicon LCOS)的光学引擎。由于LCOS可以实现“Flexgrid”滤波功能，逐渐成为一项主流技术。
LCOS的工作原理是通过在LCOS的不同像素点(pixel)上加载不同的电压，由于液晶的双折射效应，不同的电压将对应不同的相位延迟量，从而可以形成一个类似于闪耀光栅(Blazed grating)的结构。因为闪耀光栅的衍射角度取决于闪耀光栅的光栅周期，所以只需改变LCOS上不同位置对应的光栅周期，即可以控制入射光的衍射角度，使得衍射光在WSS的不同端口输出，从而实现波长选择开关功能。由于LCOS上有数百万个像素点，并且 像素点之间的间隙也非常小，因此可以非常灵活的实现Flexgrid滤波功能，同时不会存在光谱间隙。
然而，由于LCOS的工作原理是基于衍射效应，在获得我们需要的衍射光的同时，由于相位误差的存在，还会产生一些高阶衍射级次。如图1所示，图1为一个WSS的结构示意图，图1是为了说明串扰产生原因的示意图，未完全画出WSS的完整结构。图1中，从输入端口入射的光经过黑框中一系列处理(可以包括偏转处理、分波合波处理等)后，入射到LCOS面板上，LCOS上相应的像素点根据相应的配置把需要的+1级衍射光衍射到相应的输出端口。然而，这种情况下，其他衍射级的光有可能进入其他输出端口。这些衍射光，如0级、-1级、+2级等衍射光，进入相应的输入端口后，可能会造成后续光链路的串扰。比如，图1中，当+1级衍射光需要从输出端口3输出时，其他几个衍射级次可能会作为串扰光从其他几个端口输出，从而形成同频串扰，而这部分信号一旦进入相应的输出端口后难以消除，对系统性能带来影响。因此，为了提升基于LCOS的WSS的系统性能，必须找到一个解决方案，实现对串扰信号的有效抑制。
发明内容
有鉴于此，本发明实施例提供一种波长选择开关。
本发明实施例提供了一种波长选择开关WSS，所述WSS包括光纤阵列、硅基液晶LCOS面板和透镜部件，所述光纤阵列包括排成一列的多个端口，所述多个端口包括输入端口和多个输出端口，所述排成一列的多个端口的最外侧的两个端口分别为第一端口和第二端口,所述LCOS面板和第一平面的相交线与入射所述LCOS面板的入射光之间的夹角等于(90-θ)度，所述第一平面为入射所述LCOS面板的入射光与出射所述LCOS面板的出射光所在的平面，所述入射光的波长与所述出射光的波长相同，所述θ小于15度且满足以下条件：
Figure PCTCN2014095399-appb-000001
其中l1为所述输入端口与所述第一端口之间的距离，l2为所述输入端口与所述第二端口之间的距离，所述第一端口与所述(90-θ)度夹角位于所述入射光的同一侧，所述第二端口与所述(90-θ)度夹角分别位于所述入 射光的两侧，所述f为所述透镜部件在所述第一平面内的焦距。
本发明实施例提供又一种波长选择开关WSS，所述WSS包括光纤阵列、硅基液晶LCOS面板和透镜部件，所述光纤阵列包括输入端口和多个输出端口，所述输入端口和所述多个输出端口位于一条直线上，所述LCOS面板和第一平面的之间的夹角等于(90-θ)度，所述第一平面为入射所述LCOS面板的入射光与出射所述LCOS面板的+1级衍射光所在的平面；所述LCOS面板上类闪耀光栅结构的与所述直线垂直方向上的光栅周期∧1满足以下条件：∧1＝λ/2sinθ；所述LCOS面板上类闪耀光栅结构的与所述直线平行方向上的光栅周期∧2满足以下条件：∧2＝λ/(l/f)；其中，所述λ为所述入射光的波长，所述l为所述输入端口和目的输出端口之间的距离，所述f为所述透镜部件在所述第一平面内的焦距。
本发明实施例提供的WSS，无需增加任何额外部件，即可保证除+1级次衍射光外的其他衍射光不会进入任何输入端口或输出端口，从而低成本地实现了串扰抑制。
附图说明
为了更清楚地说明本发明实施例的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是现有技术中WSS产生串扰的原理示意图；
图2是本发明实施例提供的WSS的结构示意图；
图3是本发明实施例提供的各级衍射光出射区域的示意图；
图4是本发明实施例提供的LCOS面板以波长方向为轴偏转的方案示意图；
图5是本发明实施例提供的LCOS面板以端口方向为轴偏转的方案示意图；
图6是本发明实施例提供的LCOS面板以波长方向为轴偏转的方案中，偏转临界状态示意图；
图7是本发明实施例提供的LCOS面板以波长方向为轴偏转的方案中，+1级衍射光衍射角示意图；
图8是本发明实施例提供的LCOS面板以波长方向为轴偏转的方案中，+1级衍射光衍射角示意图；
图9是本发明实施例提供的LCOS面板以波长方向为轴偏转的方案中，+1级衍射光衍射角的一种具体情形的示意图；
图10是本发明实施例提供的LCOS面板以端口方向为轴偏转的方案原理示意图；
图11是本发明实施例提供的LCOS面板以端口方向为轴偏转的方案又一原理示意图。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
本发明提供一种基于LCOS的波长选择开关，能有效抑制串扰衍射光。值得注意的是，本发明实施例中的“连接”是指光路上的连接，本领域技术人员可以理解，具体的光器件可能不一定具有实质的接触性的物理连接关系，但是这些光器件的空间位置和它们本身的器件特性让它们构成一种光路上的连接关系。
如图2所示，基于LCOS的WSS主要包括用于输入输出的光纤阵列，用于偏转处理的偏转处理部件，用于反射光的反射部件，用于聚焦光的透镜部件，用于分波合波的分波合波部件，LCOS面板。可选的，WSS还可以包括位于光纤阵列之后的用于准直光的准直器阵列。可选的，所述偏转处理部件可以包括光束变形和偏振转换组件。可选的，所述透镜部件可以是一个透镜或者多个透镜的组合。可选的，所述分波合波部件可以是光栅。
图2仅为示意图，事实上，从透镜部件出射的光为平行光而不是散射光，图2仅为说明各个波长在水平方向上展开而示意性地画了相应的光线。基于LCOS的WSS是成熟的技术，图中的各个部件(包括图中未画出的部件)的功能和空间位置关系都是公知的，本发明实施例只对相对于传统的WSS有变化的LCOS面板部分进行详细描述，对其他已知的部件和位置关系不再 赘述。同时，对于图2之外的其他的基于LCOS的WSS，本发明实施例同样适用，只需对相应的LCOS面板进行相应的更改，对于WSS的其他部件的功能和位置关系保持原样即可。此外，对于未来可能出现的其他结构的WSS，本发明实施例中对于LCOS面板的改进部分同样适用。
图2中，光纤阵列所形成的直线，本发明实施例中称之为端口方向(即图2中的竖直方向)，而相应的图2中各个波长光经过分波合波器件后散开的方向，本发明实施例中称之为波长方向(即图2中的水平方向)。
对于传统的WSS的结构，多篇专利，如公开号为US8437634 B2、US20140023316 A1、WO2014027204 A1、CN203311035 U、CN102879864 B等专利对此均有涉及，这些专利的内容也结合于这片专利中。
现有的基于LCOS的WSS可以实现光谱信号Flexgrid滤波，然而采用LCOS作为光学引擎加载光栅时，会产生多个衍射级次。其中，主要的光强级次为+1级，该级次作为出射光在目的输出端口进行输出。与此同时，其他级次的光将作为串扰信号从其他端口输出，从而引起WSS端口间的同频串扰效应。该串扰大小通常在-25dB以上，而系统对于单个WSS的串扰要求通常为<-30dB甚至更低。因此，针对现有的基于LCOS的WSS，需要找到一个抑制串扰的方法。
本发明实施例提出一种有效抑制端口串扰的方案。如图3所示，将WSS的输出端口平面分为+1级信号光区域以及其他级次串扰光区域。图3中白色区域为+1级衍射光区域，图中圆圈代表光纤阵列上的输入输出端口。图3中的除了白色区域之外的黑色区域及灰色区域为其他级次衍射光分布区域。理论上讲，只要+1级衍射光落在图中白色区域的相应输出端口输出，而相应的其他级衍射光从白色区域以外的外围黑色或灰色区域输出，即可有效抑制串扰。
在一种实施方式中，如图4所示，图4中仅示意性地画出了光纤阵列、透镜部件和LCOS面板，其中白、黑两个区域对应于图3中的白、黑两个区域，仅用于阐述说明，不代表任何器件。图4相当于图2的示意性的正视图，图4中，信号光通过光纤阵列中的输入端口输入，在WSS中经过交换之后，信号光的+1级衍射光需从图4中白色区域输往目的输出端口，而其他级衍射光会输往黑色区域，即不会进入任何一个输出端口，从而不会造成串扰。在本发明实施方式中，LCOS面板以波长方向(图2中的水平方向)为轴进 行了小角度的偏转。
在又一种实施方式中，如图5所示，图5中仅示意性地画出了光纤阵列、分波合波部件、透镜部件和LCOS面板，其中白、灰两个区域对应于图3中的白、灰两个区域，仅用于阐述说明，不代表任何器件。图5中相当于图2的示意性的俯视图，图5中可以看出，从光纤阵列输出的光经过WSS内部的光交换后，+1级衍射光在竖直平面内返回输往相应的目的输出端口，而其他级次的衍射光输往灰色区域，即不会进入任何输出端口，从而有效抑制串扰。图中三条返回的实线代表波长3个波长不同的+1级衍射光。在本发明实施方式中，LCOS面板以端口方向(图2中的竖直方向)为轴进行了小角度的偏转，且LCOS面板上的类闪耀光栅结构为倾斜结构。
具体的，与图4中的实施方式相对应的，本发明实施例提供一种波长选择开关WSS，所述WSS包括光纤阵列、硅基液晶LCOS面板和透镜部件，所述光纤阵列包括排成一列的多个端口，所述多个端口包括输入端口和多个输出端口，所述排成一列的多个端口的最外侧的两个端口分别为第一端口和第二端口,所述LCOS面板和第一平面的相交线与入射所述LCOS面板的入射光之间的夹角等于(90-θ)度，所述第一平面为入射所述LCOS面板的入射光与出射所述LCOS面板的出射光所在的平面，所述入射光的波长与所述出射光的波长相同，所述θ小于15度且满足以下条件：
Figure PCTCN2014095399-appb-000002
其中l1为所述输入端口与所述第一端口之间的距离，l2为所述输入端口与所述第二端口之间的距离，所述第一端口与所述(90-θ)度夹角位于所述入射光的同一侧，所述第二端口与所述(90-θ)度夹角分别位于所述入射光的两侧，所述f为所述透镜部件在所述第一平面内的焦距。值得说明的是，透镜部件在不同方向上的焦距有可能相同，也有可能不同，在本发明所有实施方式中，相应的f是指透镜部件在端口方向的焦距，也即在所述第一平面内的焦距。
具体的，所述LCOS面板上的类闪耀光栅结构的光栅周期∧满足以下条件：∧＝λ/(sinθ+sinB1)，所述B1为所述出射光中的+1级衍射光的衍射角，所述λ为所述入射光和所述出射光的波长，其中，当所述+1级衍射光的目的输 出端口与所述(90-θ)度夹角位于所述入射光的同一侧时，所述B1等于θ+arctan(l3/f)，当所述+1级衍射光的目的输出端口与所述(90-θ)度夹角分别位于所述入射光的两侧时，所述B1等于θ-arctan(l3/f)，所述l3为所述目的输出端口与所述输入端口之间的距离。
可选的，所述θ小于5度。
具体的，所述LCOS面板上的类闪耀光栅结构用于调节所述出射光中的各级衍射光的衍射角，且所述第一平面平行于所述排成一列的多个端口所在的直线。
具体的，所述WSS还包括偏转处理部件、反射部件、分波合波部件。
可选的，本实施例的多个端口可以包括一个输入端口和多个输出端口，也可以包括多个输入端口和多个输出端口。下面的实施例以一个输入端口和多个输出端口的为例，对于多个输入端口和多个输出端口的情况，每个输入端口的情况与一个输入端口和多个输出端口的情况相同。输入端口可以位于排成一列的多个端口的中间，也可以位于排成一列的多个端口的两端的位置。
为清楚说明图4中的实施例的具体实现原理，本发明实施例提供图6。传统的LCOS面板一般与入射光垂直，而在图6中，LCOS面板与入射光成(90-θ)度的夹角。欲使得+1级衍射光进入光纤阵列的相应目的输出端口，而0级衍射光和+2级衍射光位于白色区域之外，θ需大于一定值。本发明实施例给出临界条件的θ值，只需LCOS面板的偏转角度大于该θ值，即可保证+1级衍射光进入光纤阵列的相应目的输出端口，而0级衍射光和+2级衍射光位于白色区域之外。
图6给出了相应的临界状态的示意图，当LCOS面板与入射光之间呈(90-θ)度的夹角，因为在小角度衍射角的情况下，相邻级次衍射光的衍射角间隔相等，即+2级衍射光与+1级衍射光之间的夹角α+β，应当等于+1级衍射光与0级衍射光之间的夹角2θ-β。即α+β＝2θ-β，故θ＝α/2+β，而α＝arctan(l1/f)，β＝arctan(l2/f)，故临界的
Figure PCTCN2014095399-appb-000003
其中l1为所述输入端口与图6中左侧最外侧输出端口之间的距离，l2为所述输入端口与右侧最外侧输出端口之间的距离，所述f为所述透镜部件在 所述第一平面内的焦距。
在这种临界状态下，0级衍射光显然是不会输往输出端口，而+2级衍射光正好输往左侧最外侧的端口。所以只要相应的θ值大于这个临界值，+2级衍射光就会输往图6中黑色区域，不会进入任何端口，从而有效地实现了串扰抑制。
在大于该临界值的范围内，应当选择尽量小的θ值，一般θ值不大于15度。优选的，θ值不大于10度，或者不大于5度，或者不大于3度。
在本发明实施例的WSS结构中，可以通过光栅方程∧(sinθ+sinBm)＝mλ确定输往不同端口时对应的LCOS面板上类闪耀光栅结构的光栅周期∧。光栅方程中，θ为入射光的的入射角，Bm为第m级衍射光的衍射角，λ为相应的光波长。因为需要的光信号为+1级衍射光，故上述光栅方程变为∧(sinθ+sinB1)＝λ，可得∧＝λ/(sinθ+sinB1)。如图7所示，如果光信号需输往的目的输出端口与所述(90-θ)度夹角位于所述入射光的同一侧时,B1等于θ+arctan(l3/f)。当所述+1级衍射光的目的输出端口与所述(90-θ)度夹角分别位于所述入射光的两侧时，所述B1等于θ-arctan(l3/f)。所述l3为所述目的输出端口与所述输入端口之间的距离。
下面以1×4 WSS为例，说明如何实现高衍射级次光的串扰抑制。
如图9所示，实施例中的WSS的端口为1×4，输入端口左右各两个端口，相邻端口间距为250um；透镜焦距为75mm。这里选择将LCOS沿顺时针旋转的方式。
显然，本实施方式中，l1＝l2＝500um，f＝75mm，根据
Figure PCTCN2014095399-appb-000004
可得，确定θ的临界状态的值为0.573°。接着，根据θ的取值范围，即可确定具体的θ值大小，这里可将θ设置为0.6°，将LCOS面板旋转至相应角度。
然后，根据各端口位置以及θ值大小，取波长值为1.55um，通过光栅衍射方程∧＝λ/(sinθ+sinB1)得到从左到右的4个输出端口对应的LCOS面板上类闪耀光栅结构的光栅周期分别为：56.2um；63.9um；88um；109.6um。
通过取不同的波长值，即可得到不同波长、不同输出端口所所对应的LCOS面板上类闪耀光栅结构的光栅周期，将输出端口、波长、光栅周期的 对应情况导入LCOS芯片，即可实现WSS波长选择切换功能。
本领域技术人员清楚地知道，对于既定的WSS结构，从特定输入端口输入的特定波长的入射光入射到LCOS面板上的像素点(pixel)是固定的。该像素点或者多个像素点的是一系列液晶的集合，由于液晶的双折射效应，在外加电压的作用下会形成类闪耀光栅结构。通过调节相应的外加电压，即可调节该类闪耀光栅结构的光栅周期。通过上述的光栅衍射方程∧＝λ/(sinθ+sinB1)可知，一旦光栅周期∧、入射光波长λ、入射角θ都确定后，相应的+1级衍射角即所需要的信号光的衍射角B1也就确定，出射的衍射光通过透镜部件重新回到光纤阵列输出。相对于入射光，该+1级衍射光在光纤阵列所在的直线上产生相应的位移，通过调节相应的外加电压，即可调节该位移大小，当外加电压合适时，该衍射光即可从相应的目的输出端口输出。
本发明实施例提供的WSS，无需增加任何额外部件，只需将LCOS面板的位置进行相应的偏转，即可保证除+1级次衍射光外的其他衍射光不会进入任何输入端口或输出端口，从而低成本地实现了串扰抑制。
对应于图5，本发明实施例提供又一种基于LCOS的WSS，该WSS包括光纤阵列、硅基液晶LCOS面板和透镜部件，所述光纤阵列包括输入端口和多个输出端口，所述输入端口和所述多个输出端口位于一条直线上，所述LCOS面板和第一平面的之间的夹角等于(90-θ)度，所述第一平面为入射所述LCOS面板的入射光与出射所述LCOS面板的+1级衍射光所在的平面；所述LCOS面板上类闪耀光栅结构的与所述直线垂直方向上的光栅周期∧1满足以下条件：∧1＝λ/2sinθ；所述LCOS面板上类闪耀光栅结构的与所述直线平行方向上的光栅周期∧2满足以下条件：∧2＝λ/(l/f)；其中，所述λ为所述入射光的波长，所述l为所述输入端口和目的输出端口之间的距离，所述f为所述透镜部件在所述第一平面内的焦距。
可选的，所述θ小于5度，比如可为1度、1.5度、2度、3度或4度等。
具体的，所述LCOS面板上的类闪耀光栅结构用于调节所述出射光中的各级衍射光的衍射角，且所述第一平面平行于所述直线。
具体的，所述WSS还包括偏转处理部件、反射部件、分波合波部件。
在本发明实施方式中，LCOS面板以端口方向(图2中的竖直方向)为轴进行了小角度的偏转，且LCOS面板上的类闪耀光栅结构为倾斜结构。
如图10所示，图10与图5对应。图10中的光纤阵列后方的白色框和灰色框对应于图3中的白色框和灰色框，不代表任何器件，仅用于说明衍射光出射范围。图10中LCOS面板以端口方向为轴(图2中的竖直方向)进行一个θ度的旋转。如果只进行LCOS面板的旋转而不做其他处理，所有的衍射光应该都是沿图10中0级衍射光方向出射。本发明实施例中，为了使得+1级衍射光能沿着入射光所在的平面返回到相应的目的输出端口，除了对LCOS面板进行一个θ度的旋转外，还需要配置用于调节+1级衍射光在波长方向上位移的类闪耀光栅结构。当然，与此同时，还需要配置用于调节+1级衍射光在端口方向位移的类闪耀光栅结构，以用于适配+1级衍射光出射的目的输出端口。这两种类闪耀光栅的综合效果就是，LCOS面板的上实际类闪耀光栅结构是倾斜的。
下面将具体结合图11对本发明实施例的方案及原理进行说明。图11中，黑点表示各级衍射光，圆圈表示光纤阵列处的端口，数字表示各个衍射光的级次。如图11所示，(a)部分用于表示传统的WSS中光纤阵列端口处返回的各级衍射光的情形。(a)部分中的LCOS面板不进行任何偏转，同时LCOS上也不配置波长方向位移的类闪耀光栅。如果对LCOS的类闪耀光栅结构进行一个偏转，或者说配置倾斜的类闪耀光栅结构，而不对LCOS面板进行偏转，则从光线阵列端口处可得到如图11中(b)部分所示的各级出射衍射光。如果仅对LCOS面板进行偏转，而不对传统的LCOS面板上的类闪耀光栅结构进行改动，则从光线阵列端口处可得到如图11中(c)部分所示的各级出射衍射光。本发明实施例中，既对LCOS面板进行旋转，同时对LCOS面板上的类闪耀光栅结构进行相应改动，从而使得从光线阵列端口处可得到如图11中(d)部分嗾使的各级出射衍射光。
从图11(d)可以看出，+1级衍射光正好从相应的端口输出，而其他级衍射光则避开了光纤阵列中的各个端口，从而有效抑制了串扰。进一步的，通过对LCOS面板上端口方向的类闪耀光栅结构的光栅周期进行调节，即可调节相应的+1级衍射光在端口方向上的位移，从而可让+1级衍射光从相应的目的输出端口输出。
具体的，所述LCOS面板和第一平面的之间的夹角等于(90-θ)度，所述第一平面为入射所述LCOS面板的入射光与出射所述LCOS面板的+1级衍射光所在的平面。也就是说，图10中LCOS面板偏转了θ度角。这时， 为了+1级衍射光能够从所述第一平面出射，相应的波长方向的衍射角应当为θ度，故根据光栅方程∧1(sinθ+sinBm)＝mλ，LCOS面板上类闪耀光栅结构的与所述直线垂直方向上的光栅周期∧1满足以下条件：∧1＝λ/2sinθ，此处光栅方程中的m等于1，+1级衍射光的衍射角Bm＝B1＝θ。这样，即可保证+1级衍射光从光纤阵列多个端口所在的直线方向输出。进一步的，为了调节+1级衍射光在端口方向的位移，根据光栅方程∧2(sinφ+sinBm)＝mλ，LCOS面板上类闪耀光栅结构的与所述直线平行方向上的光栅周期∧2满足以下条件：∧2＝λ/(l/f)，此处φ为入射光在端口方向的入射角，其值等于0，m等于1，又因为目的输出端口与输入端口之间的距离l远远小于f，故有sinBm＝sinB1＝tan B1＝l/f。
具体LCOS面板上的类闪耀光栅结构的光栅周期的配置方法，参见上述之描述，这里不再赘述。
本发明实施例提供的WSS，无需增加任何额外部件，只需将LCOS面板的位置进行相应的偏转并对相应的类闪耀光栅结构进行配置，即可保证除+1级次衍射光外的其他衍射光不会进入任何输入端口或输出端口，从而低成本地实现了串扰抑制。
以上所述，仅为本发明的具体实施方式，但本发明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发明揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本发明的保护范围之内。因此，本发明的保护范围应以所述权利要求的保护范围为准。

Claims (9)

  1. 一种波长选择开关WSS，所述WSS包括光纤阵列、硅基液晶LCOS面板和透镜部件，所述光纤阵列包括排成一列的多个端口，所述多个端口包括输入端口和多个输出端口，所述排成一列的多个端口的最外侧的两个端口分别为第一端口和第二端口,其特征在于：
    所述LCOS面板和第一平面的相交线与入射所述LCOS面板的入射光之间的夹角等于(90-θ)度，所述第一平面为入射所述LCOS面板的入射光与出射所述LCOS面板的出射光所在的平面，所述入射光的波长与所述出射光的波长相同，所述θ小于15度且满足以下条件：
    Figure PCTCN2014095399-appb-100001
    其中l1为所述输入端口与所述第一端口之间的距离，l2为所述输入端口与所述第二端口之间的距离，所述第一端口与所述(90-θ)度夹角位于所述入射光的同一侧，所述第二端口与所述(90-θ)度夹角分别位于所述入射光的两侧，所述f为所述透镜部件在所述第一平面内的焦距。
  2. 根据权利要求1所述的WSS，其特征在于，所述LCOS面板上的类闪耀光栅结构的光栅周期∧满足以下条件：
    ∧＝λ/(sinθ+sinB1)
    所述B1为所述出射光中的+1级衍射光的衍射角，所述λ为所述入射光和所述出射光的波长，其中，当所述+1级衍射光的目的输出端口与所述(90-θ)度夹角位于所述入射光的同一侧时，所述B1等于θ+arctan(l3/f)，当所述+1级衍射光的目的输出端口与所述(90-θ)度夹角分别位于所述入射光的两侧时，所述B1等于θ-arctan(l3/f)，所述l3为所述目的输出端口与所述输入端口之间的距离。
  3. 根据权利要求1或2所述的WSS，其特征在于：
    所述θ小于5度。
  4. 根据权利要求1至3任一所述的WSS，其特征在于：
    所述LCOS面板上的类闪耀光栅结构用于调节所述出射光中的各级衍 射光的衍射角，且所述第一平面平行于所述排成一列的多个端口所在的直线。
  5. 根据权利要求1所述的WSS，其特征在于：
    所述WSS还包括偏转处理部件、反射部件、分波合波部件。
  6. 一种波长选择开关WSS，所述WSS包括光纤阵列、硅基液晶LCOS面板和透镜部件，所述光纤阵列包括输入端口和多个输出端口，所述输入端口和所述多个输出端口位于一条直线上，其特征在于：
    所述LCOS面板和第一平面的之间的夹角等于(90-θ)度，所述第一平面为入射所述LCOS面板的入射光与出射所述LCOS面板的+1级衍射光所在的平面；
    所述LCOS面板上类闪耀光栅结构的与所述直线垂直方向上的光栅周期∧1满足以下条件：∧1＝λ/2sinθ；
    所述LCOS面板上类闪耀光栅结构的与所述直线平行方向上的光栅周期∧2满足以下条件：∧2＝λ/(l/f)；
    其中，所述λ为所述入射光的波长，所述l为所述输入端口和目的输出端口之间的距离，所述f为所述透镜部件在所述第一平面内的焦距。
  7. 根据权利要求6所述的WSS，其特征在于，
    所述θ小于5度。
  8. 根据权利要求6或7所述的WSS，其特征在于：
    所述LCOS面板上的类闪耀光栅结构用于调节所述出射光中的各级衍射光的衍射角，且所述第一平面平行于所述直线。
  9. 根据权利要求6至8任一所述的WSS，其特征在于：
    所述WSS还包括偏转处理部件、反射部件、分波合波部件。
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