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`U500650742 I 13 1
`
`(IE) United States Patent
`(l0) Patent No.:
`US 6,507,421 Bl
`
`Bishop et a].
`(45) Date of Patent:
`Jan. 14, 2003
`
`(54) OPTICAL MONITORINE FOR OXC FABRIC
`
`('5)
`
`Inventors: David Juhn Blshtap, Summit, NJ {US}:
`Randy Clinllm Giles. Whippany. NJ
`(US); ”3"“ Thflnjfls Nd'mns
`PlaIIISl-‘OFOI NJ (U5)
`
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`(73) Assignees: Lucent Technnlngles Int, Murray llill.
`NJ (US); Agent: Systems Guardian
`(30:13.. Orlando, FL (US)
`
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`“1“" b3” “x“mm“
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`( ‘ ) Notice:
`
`Subject Io an}.r disclaimer, Ihc lcrm of this
`palcm is cxlcnrlcd or adjusted under 35
`U.S.C. 154(h} by [I days.
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`Prl’WU‘ finll'a-‘Hl-"L’l'—[ 35'1“ Pascal
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`(T4) Arrrirnqv, Agent, or Firm—(Tnhen. i’nlitani, Lieberman
`(st Pavanc
`
`(2|) A 3 al. No: 09l4l4,62l
`H
`Filed:
`
`Oct. 8, [999
`
`(22)
`
`Inl. CL? _________________________________________________ HD4J 14“)“
`(5 I)
`(52) US. Cl.
`3,591,117; 359;“123; 3593.110;
`
`359_,e|34; 3593137; 359.5130; 359;]59; 335;”;
`385.318
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`359.3110. 134. 137. 13”, 139. 1592 335317.
`[8' 16‘ 2’4- 19' 26' 2" 32' 33
`References Cited
`Us. PM'L'N'I‘ DOCUMEN'IS
`
`(56)
`
`(57)
`
`ABSTRACT
`
`An uplicai cmmmnnucl (OXC) Fabric including an array of
`tiltablc mirrora a reflector and a plurality ol‘ optical fibers
`controls lhu pnsilinn of [he mirrors to optimim li'll: transfer
`0|? a signal holwccn an inpul oplical
`lilicr and an outpul
`uplical Iihur by muniloring [he optical signal at an oplical
`Iranslalinn unit
`in each of lhi:
`inpul optical fiber and [he
`oulpul optical libel—.1110 opticaltranslalion uniL‘s arc operable
`l‘nr regenerating the riplical signals transmitlud lhmugh [he
`.Ill'bcm.
`
`5.436.086 A -
`
`19-1905 Tsui
`
`335m
`
`11Clflims,2 Drawing-9110915
`
`
`200a
`1443
`MC
`200:
`100
`
`lOTU
`
` OXC FABRIC
`
`
`
`CONTROLLER
`
` 50
`
`JDS UNIPHASE CORPORATION
`JDS UNIPHASE CORPORATION
`Exhibit 1007, Page 1
`Exhibit 1007, Page 1
`
`

`

`US. Patent
`
`Jan. 14, 2003
`
`Sheet 1 of2
`
`US 6,507,421 B1
`
`D
`Lf')
`
`D
`ED
`
` CONTROLLER
`
`22c
`
`22b
`
`JDS UNIPHASE CORPORATION
`JDS UNIPHASE CORPORATION
`Exhibit 1007, Page 2
`Exhibit 1007, Page 2
`
`

`

`US. Patent
`
`Jan. 14, 2003
`
`Sheet 2 OH.
`
`US 6,507,421 Bl
`
`2000
`
`140
`
`D
`E
`
`14c
`
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`Lb
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`c.)
`
`C:
`“'3
`
`200::
`
`JDS UNIPHASE CORPORATION
`JDS UNIPHASE CORPORATION
`Exhibit 1007, Page 3
`Exhibit 1007, Page 3
`
`

`

`US 6,507,421 Bl
`
`1
`OI'I'ICAI. MONITORING FOR OXC FABRIC
`
`BACKGROUND ()1: T] [L-' INVEN'l'lON
`
`1. Field of the Invention
`
`The present invention relates to an Optical Crossconnect
`(OXC) fabric for connecting an optical signal in an input
`fiber to an output fiber and that
`includes an array of lit)
`fibers. an array of tiltablc mirrors, and a reflector.
`2. Description of the Related Art
`An Optical Crossconnect (OXC) device comprises an
`array of lenses, a corresponding array of mirrors, and a
`retleclor. An array of [i0 iibers which corresponds to the
`array of lenses is received in the device so that the array of
`mirrors corresponds to the array of 1th fibers. Each of the
`mirrors is tiltable about 2 axes for directing an input signal
`received from iLs corresponding lit) fiber (i.e. an input fiber)
`against the reflector to another mirror and to an output one
`of the lit) fibers, thereby signally connecting the input liber
`to the output fiber and functioning as a switch.
`To ensure proper positioning of the mirrors for optimizing
`the connection of the optical signal from the input IiO fiber
`to the output lit) fiber, optical taps are formed in each of the
`Ir'O fibers for monitoring the optical signals and ensuring
`that
`the output signal approximates the input signal. If a
`difference between the input and output signals exceeds a
`threshold value. the mirror positions are adjusted to optimize
`the output signal. A problem with this arrangement is that the
`optical laps direct a portion of the optical signal away from
`the lit-O fiber. Furthermore, OXCs typically include arrays of
`approximately 256 fibers and mirrors. Accordingly.
`the
`optical taps add considerable cost to the 0th because they
`are required for each of the lit) fibers.
`SUMMARY {)I’ THE lNVl-JN‘l'ION
`
`The present invention uses signals present in an optical
`translation unit to monitor the mirror position and maintain
`optimal performance of an optical crossconnect (OXC)
`device. After an optical signal is transmitted from iLs source
`to the OXC device, it is generally degraded from its original
`form and amplitude due to attenuation and other losses
`andior disturbances that
`it may receive or that are present
`along its path. For this reason, each [it] fiber includes an
`optical translation unit (BTU) which detects the incoming
`signal and regenerates the signal to iLs proper intensity and
`form. To accomplish this task. the OTU converts the optical
`signal to an electrical signal, performs the regeneration on
`the electrical signal. and transforms the regenerated electri—
`cal signal into an optical signal for continued transmission of
`the optical signal to the OXC fabric. Although the OTU is
`not a part of the OXC fabric and is typically controlled
`separately therefrom,
`the electrical signal present
`in the
`OTU can be used instead of an optical tap connected to the
`optical fiber to control
`the mirror position, because that
`electrical signal in the O'I‘U represents the optical signal that
`is transmitted to the OXC fabric. Since the presence of an
`OTU in the fibers is required to ensure signal quality, the use
`of the (”U for control of the mirror position reduces the
`number of required parts for the OXC and thereby does not
`significantly add to the cost of manufacture.
`Other objects and features of the present invention will
`become apparent from the following detailed description
`considered in conjunction with the accompanying drawings.
`It
`is to be understood, however.
`that
`the drawings are
`designed solely [or purposes of illustration and not as a
`
`2
`definition of the limits of the invention. for which reference
`should be made to the appended claims. It should he further
`understood that the drawings are not necessarily drawn to
`SCalc and that, unless otherwise indicated. they are merely
`intended to conceptually illustrate the structures and proce-
`dures described herein.
`
`BRIEF [)ESCRlP'l‘lfiN [)l: 'l'lllE. IJRAWINGS
`
`Ill
`
`[5
`
`In the drawings. wherein like reference characters denote
`similar elements throughout the several views:
`FIG.
`1
`is an elevated perspective view of an Optical
`Crossconnect {(JXC) according to the present invention; and
`FIG. 2 is a block diagram showing the control arrange-
`ment for the present invention.
`DETAILED DESCRIPTION 01" THE
`CURRENTLY PREFERRED EMBODIMENTS
`
`(Trossconncct (OXC)
`Referring to FIG. 1. an Optical
`fabric 100 comprises an array of imaging lenses 10, a mirror
`array 20, and a reflector 30.
`'lhc OXC 100 is typically
`formed using Micro Electro—Mechanical Systems (MEMS)
`technology. The array ol'irnaging lenses It} comprises lenses
`lZn—lld respectively aligned with U0 fibers 14n—14d. The
`mirror array 20 includes a plurality of mirrors 22m22d
`respectively corresponding to the lr'O fibers l4n—l4n‘. The
`lenses Ila—12d respectively correspond to the HO fibers
`l4rr~l4d for
`locussing the optical signals transmitted
`between the NO fibers Ida-140' and the respective mirrors
`2241—2241 of the mirror array 20. To simplify the drawing and
`for ease of explanation of its operation, the ()Xf.‘ fabric [00
`of FIG. 1 is shown as having four liO fiber and mirrors.
`However, the OXC fabric may include any number of liO
`fibers and mirrors and more typically includes a toxin array
`of 256 fiber and mirrors.
`L-‘ach mirror 22n—22d oi' the mirror array 20 is connected
`to a controller 5|] which controls the tilt of the mirrors for
`routing a signal from one IiO fiber to another. The mirrors
`2.2a—22d are formed using MEMS technology with a two
`axis flexure gimbal mount via torsion springs 25 so that each
`mirror nit—225i can be tilted +i—5 degrees on each axis in
`response to a voltage signal. For example, if an input signal
`on liO fiber 14:? is to be routed to ”0 fiber He, the mirrors
`22:: and 22c are tilted so that the signal is reflected oil" of
`mirror 22:: and directed toward reflector 30, reflected off the
`reflector and directed toward mirror 22c. and reflected olfol'
`mirror 22c and directed to the [£0 fiber 140. This particular
`routing example is depicted in FIG. 1. In this manner, any
`two lr‘O fibers may be signally connected.
`FIG. 2 is a block diagram showing the connection of the
`[£0 fibers I‘M—14d to the OXC fabric 100. Each of the lit)
`fibers Mir—14d may be used as either an input fiber or an
`output fiber. However, as a practical matter some are defined
`as input fibers and others as output fibers. In FIG. 2. lit)
`libers 14c and 14b are input fibers and the [KO fibers 14c and
`14d are output fibers. Before entering the 0X(‘ Fabric 100,
`each input
`lit) fiber 140—14!) runs through a respective
`()ptical Translation Unit (UTU) ZMt—ZCHJb which is con—
`nectcd to the controller 50. The primary function of the O'I‘U
`200n—2fll3b is to act as a buffer elentent for the optical signal
`and, more specifically, as a regeneration unit for regenerat—
`ing the optical signal in the fiber. When an optical signal
`travels through a long length of optical fiber.
`the original
`optical signal is attenuated and may be adversely affected in
`other ways such, for example, as via a phase shift and-“or a
`frequency variation due to various external
`influences.
`Accordingly, the DTU Zflfla—Zflflb on the input “0 fibers
`
`3t]
`
`40
`
`45
`
`St]
`
`55
`
`till
`
`65
`
`JDS UNIPHASE CORPORATION
`JDS UNIPHASE CORPORATION
`Exhibit 1007, Page 4
`Exhibit 1007, Page 4
`
`

`

`US 6,507,421 Bl
`
`3
`l4rr-l4b eonverLs the received optical signal into an elec-
`trical signal, regenerates the electrical signal back to its
`original intensity and form, and converts the regenerated
`electrical signal back into an optical signal. The regenerated
`signal is then transmitted to the 0tht‘abric100.’lhe output
`L’U libers Bic-14d also have respective OTUs ZWCmZBDd
`which perform the same function. If some degradation of the
`signal occurs in the OXC, the OTU 200e, 2000' will clean-up
`the signal by restoring the correct intensity and form before
`the signal is transmitted externally.
`As stated above, the mirror positions are controlled by a
`controller 50 in response to a routing command 60 from an
`external source. Basically. the routing command instructs
`the controller as to which output fiber to connect to an input
`fiber. The routing command 60 may be a leading command
`received on an input fiber or may be received from some
`other external source. Upon receipt of the command, the
`controller 50 performs a coarse adjustment of the mirrors to
`put the mirrors into proper position. However. to optimize
`the position of the mirrors so that
`the optical signal
`is
`optimally connected between the input fiber and the output
`fiber, the positions of the mirrors are monitored. This is
`accomplished indirectly by monitoring and comparing the
`optical signals in the input liber and output Iiher. For this
`purpose,
`the controller 50 is connected to the O'l'Us
`200a~200d and the controller monitors the signal sent to the
`(JXC' fabric in the input fiber and the signal exiting the OXC
`fabric in the output liber. More specifically, the controller 50
`is connected to the electrical signal present in each (J'I‘U
`which represents the optical signal that is sent to. in the case
`of the input fiber l4n—I4h. or received front, in the case of
`the output fiber [dc—14d, the OXC 100. The controller 50
`then compares the input signal to the output signal. [f the
`difference between the values of the optical signal
`in the
`output fiber and the input liber exceeds a threshold value, the
`controller 50 adjusts the position of the mirrors in an attempt
`to correct or minimize the ditference between the signals.
`As mentioned above, the OTUs 200n—200d are required
`components in an OXC 1110 for assuring signal quality.
`Accordingly, connecting the controller 50 to the OTU to
`provide the control signal for determining the correct mirror
`position does not require the addition of any further com—
`ponean to thc OXC fabric 100.
`FIG. 2 additionally shows a detailed view of O'I'U 200.6
`on the input fiber 14!: of the lit) fibers and a detailed view
`ofU'l'U 2001:! on the output fiber Md. Each OTU lulu—200d
`includes an Optical-to-Elcctrical converter 202, a regenera-
`tion device 204, and an Electrical-to-Optical converter 206.
`The connection in the ('J'I'Us 200(1—2005 of the input fibers
`14a, 14b is made at the point at which the electrical signal
`is connected to the Electrical-to-Optical converter 206. An
`electrical connection in the O'l'Us 2000—2001:l of the output
`fiber 14c, 140‘ is made at the point at which the electrical
`signal
`is connected to the Optical—to—Electrical converter
`202. The electrical signals are thereby connected to the
`controller 50 and monitored for each HO fiber. Accordingly,
`when an optical signal is being transmitted from one fiber to
`another in the OXC, the controller 50 monitors the signals
`in the input and output fibers to delerrnine if the signal is
`being optimally transmitted and to adjust the mirrors accord-
`ingly.
`Thus, while there have shown and described and pointed
`out fu ndamental novel features of the invention as applied to
`preferred embodiments thereof,
`it will be understood that
`various omissions and substitutions and changes in the form
`and details of the devices illustrated, and in their operation.
`may be made by those skilled in the art without departing
`
`llil
`
`[5
`
`3t]
`
`40
`
`45
`
`SE]
`
`55
`
`(ill
`
`65
`
`4
`from the spirit of the invention. For example, it is expressly
`intended that all combinations of those elements andfor
`method steps which perform substantially the same function
`in substantially the same way to achieve the same results are
`within the scope of the invention. Moreover. it should he
`recognized that structures andt'or elements andr'or method
`steps shown andror described in connection with any dis—
`closed form or embodiment of the invention may be incor-
`porated in any other disclosed or described or suggested
`form or embodiment as a general matter ofdesign choice. It
`is the intention, therefore, to be limited only as indicated by
`the scope of the claims appended hereto.
`We claim:
`1. An optical crossconnect device. comprising:
`an input fiber;
`an output fiber;
`an array of tiltable mirrors comprising a plurality of
`mirrors, each mirror being tiltable about at
`least one
`tilting axis for directing a signal received from said
`input fiber to said output fiber:
`a controller Operativcly connected to said array of tiitablc
`mirrors for positioning said mirror of said array of
`tiltable mirrors about said at least one tilting axis so that
`an input signal received from said input fiber is directed
`toward said output fiber; and
`an input bufi‘er connected to said input liber and an output
`bulIer connected to said output fiber, said controller
`being connected to said input buffer and to said output
`buffer for monitoring an input optical signal transmitted
`from said input fiber to said array of mirrors and for
`monitoring an output optical signal received by said
`output fiber from said array of mirrors, and said con-
`troller being operatively connected to said array of
`mirrors for operativcly adjusting a position of said
`minor of said array of mirrors in response to a moni—
`tored difference between said input optical signal
`in
`said input buffer and said output optical signal in said
`output bulfcr.
`2. The device of claim 1, wherein said input buffer
`comprises an input optical translation unit connected to said
`input fiber for regenerating an optical signal in said input
`fiber and said output butter mmprises an output optical
`translation unit
`for regenerating an optical signal
`in said
`output fiber.
`3. The device of claim 2, wherein each of said input
`optical translation device and said output optical translation
`device comprises an optical-to-eleclrical converter for con-
`verting an optical signal to an electrical signal, a regenera-
`tion unit for receiving the electrical signal and regenerating
`the electrical signal. and an electrical-to-optica] converter to
`converting the regenerated signal back to an optical signal.
`4. The device of claim 3. wherein said controller is
`connected to said electrical signal
`in said input optical
`translation device between said regeneration unit and said
`clectrical-to-optical converter and said controller is con-
`neeted to said electrical signal in said output optical trans—
`lation device between said optical—to—electrical converter
`and said regeneration unit.
`5. The device of claim 1, wherein said input fiber com-
`prises an array of input fibers and said output fiber comprises
`an array of output fibers.
`6. The device of claim I, wherein said array of liltahle
`mirrors comprises a plurality of tiltable mirrors. each of said
`tiltable mirrors being rotatable about two relatively perpen-
`dicular axes.
`T. The device of claim I, wherein said controller is
`connected for receiving a routing command and includes
`
`JDS UNIPHASE CORPORATION
`JDS UNIPHASE CORPORATION
`Exhibit 1007, Page 5
`Exhibit 1007, Page 5
`
`

`

`US 6,507,421 Bl
`
`5
`means for coarsely adjusting said mirrors of said array of
`mirrors in response to said routing command and for finely
`adjusting a position of said minors of said array of mirrors
`in response to the monitored difference between said input
`optical signal in said input buffer and said output optical
`signal in said output buffer.
`8. The device of claim 1. further comprising a reflector,
`wherein said liltable minors are positionable so that
`the
`input signal received from said input fiber is directed toward
`said output fiber via said rellector.
`9. A method of controlling a mirror position in a optical
`erossconneet fabric comprising an array of tiltablc mirrors.
`said optical crossconneet fabric receiving a plurality of NO
`fibers each including an optical translation unit for regen-
`erating an optical signal, wherein said tiltahle mirrors are
`operable for directing the optical signal from an input one of
`the plurality of U0 fibers to an output one of the plurality of
`HO tibers, said method of controlling a mirror position
`comprising the steps of:
`monitoring a level of an optical signal being transmitted '
`to the array of tiltable mirrors in the optical translation
`unit from the input one of the plurality of fibers;
`monitoring a level of an optical signal directed from the
`array of tiltable mirrors in the optical translation lLtnit to
`the output one of the plurality of fibers;
`comparing the monitored input optical signal to the moni-
`tored output optical signal
`to calculate a difference
`between the monitored input optical signal and the
`monitored output optical signal;
`
`ill
`
`[5
`
`6
`determining whether the calculated difference between
`the monitored input optical signal and the monitored
`output optical signal is greater than a predetermined
`threshold level; and
`adjusting the array of mirrors to minimize the calculated
`difierencc between the monitored input optical signal
`and the monitored output optical signal if it is deter-
`mined in said step of determining that the calculated
`(inference between the monitored input optical signal
`and the monitored output optical signal is greater than
`the threshold level.
`III. The method of claim 9, wherein the optical translation
`uniLs each include an optical-to-electrical converter
`for
`converting the optical signal
`into an electrical signal, and
`wherein each of said steps of monitoring a level of an optical
`signal from the input one of the plurality of fibers and of
`monitoring a lcvc] of an optical signal directed to the output
`one of the plurality of fibers includes monitoring the elec-
`trical signal in the optical translation units.
`11. The method of claim 9. wherein said step of adjusting
`the array of mirrors comprises coarsely adjusting the array
`of mirrors in response to an external routing command and
`finely adjusting said array of mirrors in response to the
`calculated difference between the monitored input optical
`signal and the monitored output optical signal.
`'0‘
`d!
`it!
`til
`it
`
`JDS UNIPHASE CORPORATION
`JDS UNIPHASE CORPORATION
`Exhibit 1007, Page 6
`Exhibit 1007, Page 6
`
`