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`USUUt324-3507131
`
`(IE) United States Patent
`US 6,243,507 BI
`(l0) Patent No.:
`Goldstcin et at.
`
`(45) Date of Patent: Jun. 5, 2001
`
`(54) CONNECTION-VERIFICATION IN OPTICAL
`MEMS CROSSCONNECTS VIA MIRROR‘
`DITHER
`
`(75)
`
`Inventors: Evan Lee Golds‘luin, Princelon;
`Lih-Yunn Lin, Middletown: Leda
`Maria Lunardi, Marlboro. all of NJ
`(US)
`
`(73) Assignee: ATSIT Corp., New York. NY (US)
`
`( ‘ ) Notice:
`
`Subject to an).r disclaimer. the term of this
`patent
`is extended or adjusted under 35
`U.S.C. 154(1)) by [I days.
`
`(21) Appl. No: Mil-172,682
`(22)
`Filed:
`Dec. 27, 1999
`
`(66)
`
`Related US. Applicalinn Data
`Provisional application No. ritit|37_.84fl.
`lilccl on Jun.
`1990.
`
`'t‘.
`
`Int. Cl.7
`(51)
`(52) US. Cl.
`
`
`.......................... (1023 oil).
`
`__ 385(13; 385E”; 385.518;
`385K“)
`(58) Field of Search ............................ 385t'16-19, 12-14;
`359313. 333. 335: ZSUI'Zifi. 334
`
`(56)
`
`References Cited
`US. PATENT DOCUMENTS
`
`385341)
`811902 Dragon:
`5,136.6?1
`In! “102 Miller cl :1].
`3503495
`5,155,623
`
`. 2509111.]
`4;"[903 int: .....
`5,215.49?
`
`.. 385318
`Ufl‘l‘fi)
`I_in .
`'1,i1hll.l32
`(ioltislcill cl :ll.
`.
`6.144381 ‘ ”1’20”!
`.mfit'lti
`
`OTHER PU 111 JCA'I'IUNS
`
`I-i. Toshiyoshi at £11.. "Electrostatic Micro Torsion Mirrors for
`an Optical Switch Matrix," .toumni of Micm'iectrmtw-
`chanted! Systems, vol. 5. No. 4. Dec. 19%. pp, 231—237“.
`
`B. lichin el al.. "Mag.neticall)r Aeluated Miemmirrors for
`l-‘iher—(lptie Switching." Solid—Stale Sensor and Aclualor
`Workshop, [lillon Head, Soulh Carolina. Jun. 8—11, 1998,
`pp. 278—276.
`K. S. .l. Pisler el 31., "Microt‘abrieated Hinges." Sum-cry and
`Actuators, vol. A, No. 33 (1992). pp. 249—256.
`'1’. Akiyama at al_. "A Quantitative Analysis of Scratch Drive
`Actuator Using Buckling Motion," IEEE Workshop on
`Micro Electric.- Mechanical Systems; Amsterdam. The Neth-
`erlands. Jan. 29—1’el1. 2, 1995. pp. 310—315.
`R. '1‘. Chen at al.. "A Low Voltage Micmmaehincd Optical
`Switch By Stress—induced Bending." 12"“ IEELC interna—
`tional Conference (in Micro Electro Mechanical Systems,
`Orlando. Florida. .1 an. 17—21. 1999. 5 pages.
`(Tronos Integrated Mierosystems, lnc.. "three—Layer Poly-
`silicon Surface Micromaehinc l’mecss." Aug. 24. 1999, pp.
`1—8 (hltp:.t,"rrtems.t'ncnc.org).
`1.. Y. Lin cl
`31..
`"Free—Space Micromachined Optical
`Switches for (Jplieal Networking," Hill-'th'nttt-rtttt ofSeicctcd
`Epics in Quantum Kitten-(mics, vol. 5. No. 1,Jan..t'17eh. 1999,
`pp. 4—9.
`
`(List continued on next page.)
`I’rt'tttmjr t:'.mtttt'rter—l)arren Sehuhcrg
`Assistant Exmtiimlr—«Fayez Assai
`(57)
`ABSTRACT
`
`Integrated conneelion-verilieution system [or use in a micro-
`electromechanical system (MEMS) cmssmnnect device.
`The system uses application of a dithering signal such as a
`sinusoidal bias In an electrode plate associated with a
`micro-mirror switching element to dither the micro-mirror.
`The optical signal From the dithering micro—mirror is fed
`through a beam splitter. a portion of the optical signal thus
`being directed to a pholodeteelor. 11' intensityr modulation in
`the optical signal corresponding to the frequencyt of the
`dithering signal is detected by the photo-detector associated
`with the micro—mirror.
`Ihc conneclion path between [he
`desired input and output ports is Verified.
`
`1] Claims, 9 Drawing Sheets
`
`
`
`JDS UNIPHASE CORPORATION
`JDS UNIPHASE CORPORATION
`Exhibit 1022, Page 1
`Exhibit 1022, Page 1
`
`

`

`US 6,243,507 B]
`Page 2
`
`OTHER PU BLICKI'IONS
`
`I... Y. Lin el aL, "lligh—Densily Micrornachined l’nlygnn
`Optical Crossconnccls Exploiting Nclwork Connection-
`Symmclry." IEEE Phomm'cs Ir'bchnofagy Lawns; vol.
`lfl,
`N0. 10, Gel. 1998, pp. 1425—1427.
`E. L. (ioldstein cl 31., "NalionaI—Scale Nulworks Likely It!
`Be Opaquc." Lighnmvc, Feb. 1998, pp. 9]~95.
`f—K. Chan cl al., “A Novel Optical—Pam Sulacriiisorg.r
`Scheme for (Jplical Cross Connects in AJIUOpIica] 'l'ransporl
`
`Networks," IEEE I’horonfcs Ibchrioiugvlencra; v0]. 10, No.
`6, Jun. 1998, pp. 899—9fl].
`
`L. Y. Lin at 3L. "Optical Cmss—connccl [nlegralud Syslcsm
`(OCCIS): A Free—Spam: Micmmachinutl Moduli: for Signal
`and Switching Configuralion Manila-ring," Iii-IKE LEGS
`Siumner Topical Meeting: Oprica! MEMS, Monlercy, Cali-
`fornia, Jul. 20—22, 1998. 3 pages.
`
`* oiled by examiner
`
`JDS UNIPHASE CORPORATION
`JDS UNIPHASE CORPORATION
`Exhibit 1022, Page 2
`Exhibit 1022, Page 2
`
`

`

`US. Patent
`
`.Iun.5,20{)1
`
`Sheet 1 01'9
`
`US 6,243,507 B1
`
`FIG.
`
`1 J
`
`DS UNIPHASE CORPORATION
`JDS UNIPHASE CORPORATION
`Exhibit 1022, Page 3
`Exhibit 1022, Page 3
`
`

`

`US. Patent
`
`Jun.5,2001
`
`Sheet 2 of9
`
`US 6,243,507 Bl
`
`"MICRO-HINGES
`
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`JDS UNIPHASE CORPORATION
`JDS UNIPHASE CORPORATION
`Exhibit 1022, Page 4
`Exhibit 1022, Page 4
`
`

`

`US. Patent
`
`Jun.5,2001
`
`Sheet 3 of9
`
`US 6,243,507 Bl
`
`PLATE
`
`
` ELECTRODE
`SPRING-LATCH
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`
`JDS UNIPHASE CORPORATION
`JDS UNIPHASE CORPORATION
`Exhibit 1022, Page 5
`Exhibit 1022, Page 5
`
`

`

`US. Patent
`
`Jun.5,2001
`
`Sheet 4 of9
`
`US 6,243,507 Bl
`
`FIG. 4
`
`
`
`JDS UNIPHASE CORPORATION
`JDS UNIPHASE CORPORATION
`Exhibit 1022, Page 6
`Exhibit 1022, Page 6
`
`

`

`US. Patent
`
`Jun. 5, 2001
`
`Sheet 5 of 9
`
`US 6,243,507 B1
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`JDS UNIPHASE CORPORATION
`JDS UNIPHASE CORPORATION
`Exhibit 1022, Page 7
`Exhibit 1022, Page 7
`
`

`

`US. Patent
`
`Jun.5,2001
`
`Sheet 6 of9
`
`US 6,243,507 Bl
`
`FIG.
`
`6'
`
`RESPONSE
`(4H2. ZUmV/div)
`
`(2H2, 30‘!)
`
`BIAS
`VOLTAGE
`
`—500.00 ms
`
`0.000 s
`
`500.00 ms
`
`RESPONSE
`(120m.
`20mV/div)
`
`BIAS
`VOLTAGE
`
`(fiOHz. 30v)
`
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`
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`0.000 5
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`
`JDS UNIPHASE CORPORATION
`JDS UNIPHASE CORPORATION
`Exhibit 1022, Page 8
`Exhibit 1022, Page 8
`
`

`

`US. Patent
`
`Jun.5,2001
`
`Sheet 1' of9
`
`US 6,243,507 Bl
`
`RESPONSE
`[IBDHL
`20mV/div)
`
`Bus
`VOLTAGE
`
`-25.000 ms
`
`0.000 5
`
`25.000 ms
`
`(sum, 30%.!)
`
`
`
`RESPONSE
`(zoom,
`20mV/div)
`
`BIAS
`VOLTAGE
`(100Hz, 30V)
`
`-25.000 ms
`
`0.000 5
`
`25.000 ms
`
`JDS UNIPHASE CORPORATION
`JDS UNIPHASE CORPORATION
`Exhibit 1022, Page 9
`Exhibit 1022, Page 9
`
`

`

`US. Patent
`
`Jun.5,2001
`
`Sheet 8 of9
`
`US 6,243,507 Bl
`
`FIG. 10
`
`RESPONSE
`(4H2,
`20mV/div]
`
`BIAS
`VOLTAGE
`
`-500.00 rns
`
`0.000 s
`
`500.00 ms
`
`
`(2H1, 20V)
`(2Hz, 30v)
`
`RESPONSE
`(4H1.
`20mV/div)
`
`EIAS
`VOLTAGE
`
`-500.00 rns
`
`0.000 s
`
`500.00 ms
`
`JDS UNIPHASE CORPORATION
`JDS UNIPHASE CORPORATION
`Exhibit 1022, Page 10
`Exhibit 1022, Page 10
`
`

`

`US. Patent
`
`Jun.5,2001
`
`Sheet 9 of9
`
`US 6,243,507 Bl
`
`FIG. 12
`
`RESPONSE
`(4H2,
`20mV/div)
`
`(2H2, 41w)
`
`BIAS
`VOLTAGE
`
`-500.00 ms
`
`0.000 s
`
`500.00 ms
`
`JDS UNIPHASE CORPORATION
`JDS UNIPHASE CORPORATION
`Exhibit 1022, Page 11
`Exhibit 1022, Page 11
`
`

`

`US 6,243,507 Bl
`
`1
`CONNECTION-VERIFICATION IN OPTICAL
`MEMS CROSKONNECTS VIA MIRROR-
`DITHER
`
`'l‘his nonprovisional application claims the benefit of
`US. Provisional Application No. (at)! 131840, filed .lun, it,
`1999.
`
`BACKGROUND OF THE INVENI‘ION
`1. Field of Invent ion
`This invention relates to a connection verification system
`in an optical micro-electro-tnechanical system (MEMS)
`crossconnect device.
`2. Description ol‘ Related Art
`Optical crossconnecLs (UXCs) have emerged as a prom-
`ising means of carrying out optical—layer provisioning and
`restoration in future, high-capacity WDM (wavelength-
`division multiplexing) networks
`As technologies for optical switching advance, enhancing
`the networking functionality of OXCs has become increas-
`ingly important. and doing so via integrated and low-cost
`approaches becomes particularly desirable. One important
`requirement
`for the OXC is connection-verification for
`network surveillance. That is, it
`is desired to verify that an
`optical signal is being properly switched and carried within
`the system to the desired output port or fiber.
`What is still desired is a simple, cost-effective connection
`verification system for use in a MEMS optical crossconnect
`network.
`
`SUMMARY ()1“ THE [NVEN'I‘ION
`
`is therefore an object of the invention to develop a
`[I
`connection path verification system [or use in the MEMS
`OXC.
`'lltis and other objects are achieved by the present inven-
`tion that achieves connection path verification via integrated
`pilot-tone coding schemes utilizing micro-mirror dithering
`in the MEMS crossconnect.
`In one aspect of the invention, the invention relates to a
`connection verification system comprising a micro—mirror
`having an optical signal
`input side and an optical signal
`output side, the micro—mirror connected to a substrate, an
`electrode plate in association with the micro-mirror and
`capable of dithering the micro-mirror upon application of a
`dithering signal to the electrode plate, a beam splitter located
`on the substrate at
`the optical signal output side of the
`micro-mirror, and a photodetector positioned beneath the
`beam splitter.
`In a further aspect ol'thc invention, the invention relates
`to a connection verification system of an optical micro-
`electro-rnechanical crossconnect device, comprising at least
`one input port and at least one output port, a micro-mirror
`having an optical signal
`input side and an optical signal
`output side, the micro-mirror connected to a substrate, the
`micro-mirror being positioned on the substrate at a 45° angle
`to an incoming optical signal from one of the at least one
`input ports and at a point of intersection ofa path from the
`one input port and one of the at least one output ports, an
`electrode plate in association with the micro-mirror and
`capable of dithering the micro-mirror upon application ot‘a
`dithering signal to the electrode plate, a beam splitter located
`on the substrate at
`the optical signal output side of the
`micro-mirror, and a photodetector positioned beneath the
`beam splitter.
`In a still
`l‘urther aspect of the invention, the invention
`relates to a method of verifying the connection path of an
`
`5
`
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`
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`
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`
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`
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`
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`
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`
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`
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`optical signal from an input port to a desired output port,
`comprising switching an optical signal from the input port to
`the desired output port with a micro—mirror having an optical
`signal
`input side and an optical signal output side,
`the
`micro-mirror connected to a substrate, applying a dithering
`signal to an electrode plate in association with the micro-
`t'nirror to dither the micro—mirror. and splitting the optical
`signal on the optical signal output side of the micro—mirror
`into a detection portion and an output portion with a beam
`splitter located on the substrate at the optical signal output
`side of the micro-mirror,
`the beam splitter directing the
`detection portion of the optical signal to a photodetector
`located beneath the beam splitter. The connection path is
`verified when the photodetector detects alterations in inten-
`sity of the detection portion of the optical signal correspond-
`ing to the dithering signal applied to the electrrxle plate.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is an illustration of the mirror-dither scheme for
`pilot—tone coding and on—chip signal monitoring in the
`free—space MEMS ()XC of the invention.
`FIG. 2 is a SEM (scanning electron microscope) photo-
`graph of a free—rotating hinged micro—mirror in a free—space
`MEMS OXC of the invention.
`
`FIG. 3 is a 1‘5le photograph of the micro-switch mirror
`with an integrated electrode.
`l-‘lti. 4 is a schematic diagram of a microactualed frec~
`rotating switch mirror.
`FIG. 5 is a SEM photograph of the beam-splitter;
`photodetector monitor module of the invention.
`FIGS. 6—9 are frequency responses of the micro-mirror at
`various frequencies and hiaseS. while FIGS. 10—12 are
`frequency responses ol‘ the miero~ntirror at various biases,
`the upper traces representing signals from the photodetector,
`the lower traces representing biases on the electrode.
`DETAILED DESCRIPTION OF PREFERRED
`EMBODIMENTS
`
`there is access to the bit
`In a conventional network,
`streams traveling within the system. This enables easy
`manipulation of a bit stream, for example by turning signals
`on and olI to represent bits, in order to verify that the bit
`stream is being switched to the proper output port. The
`methodology was simple and straightfonvard.
`However, this conventional technology cannot be utilized
`in optical crossconnect systems because access to the system
`as in the conventional technology is not available. That is, in
`conventional electronic systems,
`information can be
`manipulated at the bit level because of the devices used in
`such a system. l-Iowever, in optical crossconnect systems,
`the equipment
`includes lenses. etc,
`that do not afford
`manipulation of bits. As a result, it is not possible in optical
`crosswnnect systems to look at information bib; and deter—
`mine therefrom whal
`they are connected to. Thus, new
`connection verification technology must be developed in
`order to conlirm that the switches within the optical cross—
`connecl are properly connecting an input optical signal to
`the desired output port.
`An optical path supervisory scheme has been proposed in
`C-K. Chan, E. Kong, F. Tong and I..—K. Chen, "A Novel
`Optical-Path Supervisory Scheme For Optical Cross Con-
`nects in All-Optical Transport Networks". [EL-‘15 l’hotonics
`Tech. t.ett., vol. to, pages 899—9llt (1998). In this scheme,
`use is made of periodic characteristics of arrayedm
`waveguide-gratings. Although adequate,
`this scheme is
`
`JDS UNIPHASE CORPORATION
`JDS UNIPHASE CORPORATION
`Exhibit 1022, Page 12
`Exhibit 1022, Page 12
`
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`

`US 6,243,507 Bl
`
`3
`cumbersome in terms of the hardware required. The scheme
`requires a specific arrayed-waveguide grating and requires
`additional tillers to be used.
`Micro-electromechanical system {MEMS} technology,
`due to iLs unique capability of integrating optical, electrical
`and mechanical elements on a single chip, holds strong
`advantages for implementing multiple functionalities in
`integrated form.
`Free-space MEMS optical switches aiming at large-scale
`switch fabrics have been demonstrated using various
`approaches. See, for example. [1) ll.
`'loshiyoshi and ll.
`Fujita, "Electrostatic Micro Torsion Mirrors for an Optical
`Switch Matrix", J. Microelectromechanical Systems, vol. 5,
`no. 4, pp. 231—337, 1996, (2) L. Y. Lin, E. L. Gotdstein, and
`R. W. 'l‘kach, "Free-Space Microlnachined Optical Switches
`for Optical Networking", [Hill J. Selected Topics in Quan—
`turn Electronics: Special Issue on Microoptoelectromechani—
`cal Systems (MOEMS), vol. 5, no. 1, pp. 4-9, 1999, {3) L.
`Y. Lin, E. L. Gotdstein, J. M. Simmons. and R. W. Tttach,
`"lligh—I)ensity Micrornachincd Polygon Optical Crosscon—
`nects Exploiting Network Connection Symmetry", [EEE
`Photonics Tech. l_ett., vol. 10, pages 1425—1427 (1998), (4)
`R. T. Chen, H. Nguyen, and M. C. Wu, "A Low Voltage
`Micromachined Optical Switch by Stress-Induced
`Bending“, 12th IEEE International Conference on Micro
`Electro Mechanical Systems, Orlando, Fla.,
`.lan. 17—21.
`1999. and (5) B. Behin. K. Y. Lau. and R. S. Muller,
`"Magnetically Actuated Micromirrors for F iber-Opt ic
`Switching", Solid-Slate Sensor and Actuator Workshop,
`Hilton Head Island, S.(.‘., Jun. 8“] 1, 1998, each incorporated
`by reference herein in their cntireties.
`U .5. Pat. No. 5,960,132 describes an optical switch device
`that is actuated between reflective and non—reflective states.
`US. application No. 091473724 entitled "Angular-Precision
`Enhancement
`In Free-Space Micromachincd Optical
`Switches“ and based on ProvisionalApptication No. 60.31311,
`838 (filed Jun. 7’, 1999), describes free-space MEMS cross-
`connect optical switches that
`include mechanical angular
`alignment enhancement structures. This patent and
`co-pending application are both incorporated herein by
`reference in their entireties. The present
`invention may
`utilize the optical switches described in the 132 patent
`andr'or
`the DES-pending application. with or without
`the
`additional mechanical angular alignment enhancement
`structures of the cit-pending application. Of course, any
`other suitable switch mirror scheme may also be used.
`In free-space MEMS crossconnects, micromachined mir-
`rors are utilized as the switching elements These may be. for
`example, free-rotating mirrors as just discussed.
`Optical switches function to switch an optical signal from
`an input port 5, e.g., an input fiber, to an output port 55, c.g.,
`an output liber when in the reflective position. The switches
`are located within an open, free space. The size of the matrix
`of incoming and outgoing fibers is NXM, with N and M
`being any integer greater
`than 1. Optical micro-mirror
`switching elements are typically positioned at a 45° angle to
`the direction of an incoming optical beam from an input port
`in matrix configuration, and located at the points of inter—
`section of the paths of each input port and each output port.
`Incoming optical beams may he directed to the desired
`output port through use of the micro-mirror optical switches.
`Other configurations, for example polygonal, are possible.
`When all incoming optical signal is not to be redirected by
`a particular micro-mirror, the micro-mirror remains in its
`rest position, which is horizontal to the substrate upon which
`the micro-mirror is rrtou ntcd, or at least out of the plane of
`
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`
`[5
`
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`
`40
`
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`travel of the optical signal. However, if an optical signal is
`to be redirected by the micro-mirror, the micro-mirror is
`movcdtraiscd to its reflective position, which is a predeter-
`mined position and preferably is, for example, as close to
`perpendicular, i.e., 90°, from the substrate as possible.
`The micro-mirrors of the invention may be made of any
`conventional material. For example, the micro-mirrors may
`be polysilioon. optional coated with a highly reflective metal
`such as gold or CrMu, for example as in It. 't‘oshiyoshi and
`II. Fajita, supra.
`The micro—mirror, hinge and staple may be formed by any
`conventional process.
`rl‘he micro-mirrors are preferably
`formed by surface-micromachining, for example as in the
`well-known MUMl’sT'“ (the multi-user MEMS) process
`described in. for example, L. Y. Lin, L". l.. Goldstcin and R.
`W. ‘l‘kach, "Free—Space Micrornachined Optical Switches
`for Optical Networking", IEEE Journal of Selected Topics in
`Quantum Electronics. vol. 5, no. 1, pp. 4—9, Januaryx'
`February 1999 and K. S.J. Pister, M. W. Judy,S. R. Burgett,
`and R. S. Fearing, "Microl'ahricated Hinges," Sensors and
`Actuators A, vol. 33, pp. 249—356, 1992, both incorporated
`herein by reference in their entireties.
`ln MUMPS“. a
`polysilicon is used as the structural material. a deposited
`oxide (980) is used for the sacrificial layers, and silicon
`nitride is used as an electrical isolation layer between the
`silicon substrate and the polysilicon layers. The polysilicon
`layers are referrer] to as poly-(l, poly-1 and poly-2.
`FIGS. 2, 3 and 4 show a preferred mirror switch of the
`invention. The micro-mirror 20 is mounted within it frame,
`which frame is connected to the substrate 15 by free-rotating
`micro-hinges 30. The hinges 30 include one or more hinge
`pins 22 and one or more hinge staples 24. Pushrods 26 are
`connected at one end to the mirror (mirror frame) and at the
`opposite end to the translation stage 18.
`Scratch-drive actuators (SDAs) 45 are preferably
`employed to move the translation stage. SDAs are
`conventional, and thus an extensive discussion of the func—
`tion of the SDAs is not necessary herein. For a discussion of
`the formation and function of SDAs see. for example, T.
`Akiyama and It. Fajita, "A Quantitative Analysis of Scratch
`Drive Actuator Using Buckling Motion," in lEEE Workshop
`on Micro Electro Mechanical Systems, Amsterdam,
`the
`Netherlands, Jan. 29—Feb. 2, 1995, incorporated herein by
`reference in its entirety. For purposes of explaining the
`Functioning of the hinged micro-mirrors of the present
`invention, it is suflicient to note that through application of
`an appropriate voltage to the SDA,
`the SDA can be
`deformed or moved to a certain extent, which defon‘nation
`or movement is used to move the translation stage a trans-
`lation distance corresponding to the extent of deformation.
`Movement of the translation stage in turn causes the push-
`rods to act upon the mirror frame and rotate it up to a
`predetermined position or angle From the substrate, typically
`the 90° position discussed above.
`FIG. 1 shown; the micro—mirror dither scheme for pilot-
`tone coding and on-chip signal monitoring in the free-space
`MEMS OXC ofthe invention. In this scheme. an electrode
`plate 10 is associated with the micro—mirror 20.
`The electrode plate is made of any suitable material.
`Preferably,
`the electrode plate is also a surface-
`micromachined polysilicon integrally formed during the
`MUMPS process.
`In this way, the electrode plate can be
`formed with the micro-mirror. The electrode plate may be
`formed from, for example. the poly-1 layer. The electrode
`plate may be integral with the micro-mirror, or it may be
`formed to separately more, for example rotate via hinge
`joints, the same as the micro-mirror.
`
`JDS UNIPHASE CORPORATION
`JDS UNIPHASE CORPORATION
`Exhibit 1022, Page 13
`Exhibit 1022, Page 13
`
`

`

`US 6,243,507 Bi
`
`5
`As the electrode plate is preferably matte of poiysiiieon,
`it is conductive. The electrode plate contacts the polysilicon
`hinge staples. A source providing the dithering signal to the
`electrode plate can be connected via conductive. e.g.. poly—
`si].icon or gold, wiring to either the electrode plate or the
`hinge staples. The conductive wiring is also preferably
`formed photolilhographically during the MUMPS formation
`process.
`1 to
`Although the electrode plate is illustrated in FIG.
`extend around the exterior of the micro—mirror, any suitable
`configuration of the electrode plate can he used. The only
`requirement is that the electrode plate must be capable of
`dithering the micro-mirror when a dithering signal is applied
`to the electrode plate.
`At the 90” position. i.e.. the vertical. reflective or active
`switch position, the micro-mirror can perform small angle
`modulation under external force. That is. the micro—mirror
`can be rnadc to vary slightly in angle from its designed
`position to the incoming optical signal, e.g., 90° to the
`incoming optical signal. The direction of modulation is
`shown in MG. 1.
`repetitive, back—and-forlh small angle
`Dithcring.
`i.e.,
`modulation. of the micro-mirror is effected in the invention
`through application of a dithering signal
`to the electrode
`plate. The only requirement of thc dithering signal is that it
`must be capable of inducing small angular variations in the
`micro-mirror which can be detected by a photodetector. The
`dithering signal may be. for example. a sinusoidal bias or a
`sinusoidal pilot tone. Most preferably, the dithering signal is
`a sinusoidal bias. A sinusoidal bias causes the micro-mirror
`to dither at frequencies corresponding to the sinusoidal bias.
`(in the output side of the micro~mirror optical switch. a
`polysilicon plate 30 is positioned at a 45° angle to both the
`substrate and the optical signal output
`from the micro-
`mirror. This polysilicon plate also is preferably a surface-
`rnicromachjned polysiiicon. The poiysilicon plate may be
`fixed to the substrate in the 45" position by any suitable
`means. For example. as shown in FIG. 5, the polysilicon
`plate may include appropriate vertical and side supports to
`ensure the fixing of the position of the polysiiicon plate.
`The polysilicon plate functions as a beam splitter. A
`portion of the optical signal output from the micro—mirror is
`reflected by the poiysilicon plate beam splitter to a photo-
`detector located under the polysilicon plate and upon the
`substrate. This is illustrated in FIG. 1. The beam splitter.t
`photodctector monitor module is shown in FIG. 5. The beam
`splitter may be formed of any suitable material. polysilicon
`merely being an illustrative example.
`"lite photodeteclor is preferably formed by. for example,
`hybrid-integrating the photodetector into the system by wire
`bonding as explained in 1.. Y. Lin, L. M. Lunardi and ii. i...
`(.ioidstein, "Optical Cross-Connect
`integrated System
`(OCC‘IS): A Free-Space Micromachined Module For Signal
`And Switching Configuration Monitoring".
`iEEE LEOS
`Summer Topical Meeting: Optical MEMS, Monterey, Calif.
`Jul. 30—32, 1998.
`incorporated by reference herein in its
`entirety.
`In particular,
`the pholodcteclor may bc soldcr
`mounted on the substrate of the free-space micro-mirror
`chip.
`Small angular variations of the micro—mirror as a result of
`the dithering signal applied to the electrode plate are trans—
`formed into intensity modulation of the detected optical
`from the photodclector. Due to the high angular sensitivity
`ofsingle-mode optics. the resulting modulation efficiency is
`quite high. By modulating the angle of the actuated micro-
`mirror with various frequencies, a pilotmlone signal carrying
`
`10
`
`[5
`
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`
`40
`
`45
`
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`
`$5
`
`of]
`
`65
`
`6
`the connection-path information can therefore be impressed
`on the optical signal.
`In other words, the dithering of the micro-mirror results in
`a detectable variation in the intensity of the optical beam
`arriving at the photodctector from the polysilicon plate beam
`splitter. The detection of this variation by the photodeteclor
`can verify that the switching of the optical beam within the
`MEMS OXC occurred successfully. If an input optical signal
`is desired to be sent to a selected output port, verification of
`the switching to that output port can be done in this scheme.
`If variation in the intensity of a pilot tonc sent from the input
`port
`is registered at the photodctector associated with the
`optical switching element feeding the selected output pon,
`then the necessary switching is properly occurring.
`To measure the bandwidth and sensitivity of the hinged
`micro—mirmrs, sinusoidal signals with various frequencies
`and amplitudes are applied to the electrode. The modulated
`output electrical signal from the photodetector is then cap-
`tured by an oscilloscope. FIGS. 6—9 show the frequency
`response of the micro—mirror at 4, [20, too and 200 ilz.
`respectively under 30 V bias. The upper traces represent
`signals from the photodeteclor; the lower traces represent
`biases on the electrode.
`
`Various frequency responses between 4 and 200 H7. have
`been measured. The intensity-maiulalion frequency of sig-
`nais from the photodetector is twice the bias frequency, as
`the mirror-angle is optimined when there is no bias. The
`responses rcrrtain similar between 4 and [20 Hz, and start to
`decrease as the frequency rises above 120 Hz. At 200 Hz, the
`response begins to show signs of more complex coupling
`into the micromechanical structure. as shown in I-'l(i. 9.
`”Thus, the frequency applied to the electrode plate is pref-
`erably kept between 4 and 200 Hz, most preferably between
`4 and 120 Ill for the current micro—mirror. The bandwidth
`can be increased by modifying the design of the micro-
`mirror.
`
`The responses of thc micro—mirror under various bias
`amplitudes are also measured. FIGS. 10 to 12 show the
`results of 20 V, 30 V and 40V biases, respectively. The
`results may suggest that the maximum angular variation of
`the micro—mirror is restricted by its mechanical stntcture.
`The bias amplitude is preferably maintained between 10 and
`St} V, most preferably between 20 and 40 V for the current
`micro-mirror.
`In all cases, the intensity variation of the optical signal at
`the output of the switch fabric is expected to permit accept-
`able monitoring performance without imposing bit errors in
`transponder-based WDM networks.
`free—space
`A pilot—lone—based encoding scheme it's
`MEMS—bascd optical crossoonnccts is thus achieved. The
`scheme utilizes free-rotating switch mirrors with dither
`electrode plates and integrated micro-optics. Through this
`scheme. connection verification within the MEMS OXC can
`be readily and mstclfeclively achieved.
`What is claimed is:
`1. A connection verification system comprising
`a micro~mirror having an optical signal input side and an
`optical signal output side, the micro-mirror connected
`to a substrate.
`an electrode plate in association with the micro-mirror
`and capable of dithering the micro-mirror upon appli-
`cation of a dithering signal to the electrode plate,
`a beam splitter located on the substrate at
`the optical
`signal output side of the micro-mirror, and
`a pholodetector positioned beneath the beam splitter.
`
`JDS UNIPHASE CORPORATION
`JDS UNIPHASE CORPORATION
`Exhibit 1022, Page 14
`Exhibit 1022, Page 14
`
`

`

`US 6,243,507 Bl
`
`7
`2. The connection verification system according to claim
`I. wherein the system is within an optical microelectro-
`mechanical crossconncct device.
`3. The connection verification system according to claim
`2, wherein the optical microcleclro-rnechanical crosscon-
`nect device includes at least one input port and at least one
`output port, the micro—mirror being located on the substrate
`in a line of travel or an incoming optical signal from one of
`the at least one input ports and at a point of intersection of
`a path from the one input port and one of the at least one
`output ports when in a reflective position.
`4. The connection verification system according to claim
`1, wherein the electrode plate is connected to a source of the
`dithering signal via conductive wiring.
`5. The connection verification system according to claim
`1. wherein the micro—mirror is connected to the substrate via
`hinge joints permitting free rotation of the micro—mirror.
`6. The connection verification system according to claim
`I, wherein one or more of the micro-mirror, the electrode
`plate and the beam splitter are comprised of a surface-
`micromachined polysilicon.
`7. A connection verification system of an optical micro-
`electro-mechanical crossconneet device. comprising
`at least one input port and at least one output port,
`a micro—mirror For one of the at least one input ports and
`having an optical signal input side and an optical signal
`output side, the micro-mirror connected to a substrate,
`and capable of being moved to a reflective position so
`as to switch an incoming optical signal front the one
`input port
`to a predetermined output port when the
`micro-mirror is in a reflective position,
`
`5
`
`10
`
`[5
`
`8
`an electrode plate in association with the micro-mirror
`and capable of dithering the micro-mirror upon appli-
`cation of a dithering signal to the electrode plate,
`a beam splitter located on the substrate at
`the optical
`signal output side of the micro-mirror, and
`a pholodetector positioned beneath the beam splitter.
`8. A method of verifying the connection path of an optical
`signal from an input port to a desired output port, comprising
`switching an optical signal from the input port
`to the
`desired output port with a micro—mirror having an
`optical signal input side and an optical signal output
`side, the micro-mirror connected to a substrate.
`applying a dithering signal to an electrode plate in asso—
`ciation with the micro~mirror to dither the micro
`mirror, and
`splitting the optical signal on the optical signal output side
`of the micro-mirror into :1 detection portion and an
`output portion with a beam splitter located on the
`substrate at the optical signal output side of the micro-
`mirror, the beam splitter directing the detection portion
`to a photodetector located beneath the beam splitter.
`9. The method according to claim 8. wherein the dithering
`signal is a sinusoidal bias.
`Ill. The method according to claim 8. wherein the con-
`neetion path is verified when the photodetector detects
`alterations in intensin of the detection portion ofthe optical
`beam corresponding to the dithering signal applied to the
`electrode plate.
`11. The method according to claim 8. wherein the optical
`signal from the input port includes a pilot tone.
`
`JDS UNIPHASE CORPORATION
`JDS UNIPHASE CORPORATION
`Exhibit 1022, Page 15
`Exhibit 1022, Page 15
`
`