(12) United States Patent
`Aksyuk et al.
`
`US006204946B1
`US 6,204,946 B1
`Mar. 20, 2001
`
`(10) Patent N0.:
`(45) Date of Patent:
`
`RECONFIGURABLE WAVELENGTH
`DIVISION MULTIPLEX ADD/DROP DEVICE
`USING MICROMIRRORS
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`5,726,785 * 3/1998 Chawki et al. .................... .. 359/130
`
`
`
`5,812,291 * 9/1998 Bendelli et al. 5,926,300 * 7/1999 MiyakaWa et al. ................ .. 359/124
`
`* cited by examiner
`Primary Examiner—Kinfe-Michael Negash
`(57)
`ABSTRACT
`
`AWDM add/drop device for use in an optic communications
`system for adding and dropping optical Wavelengths from a
`multiple-Wavelength optical system. The device includes a
`set of lenses, a planar grating Wavelength multiplexer and a
`micromirror array switchable for individual Wavelengths of
`the multiple-Wavelength signal betWeen a transmit mode and
`a re?ect mode. The grating angularly demultiplexes a
`multiple-Wavelength optical signal in a ?rst direction and the
`individual Wavelengths are processed by the micromirror
`array and directed to the grating in a second direction. The
`micromirror array Will either re?ect select Wavelengths to a
`?rst port or transmit select Wavelengths to a second port. In
`a preferred embodiment, ports on a ?rst multiport circulator
`input the multiple-Wavelength optical signal to the WDM
`add/drop device and output the multiple-Wavelength optical
`signal from the WDM add/drop device. A second multiport
`circulator provides to-be-added Wavelengths to the WDM
`add/drop device and removes to-be-dropped Wavelengths
`from the WDM add/drop device.
`
`26 Claims, 2 Drawing Sheets
`
`(54)
`
`(75)
`
`Inventors: Vladimir A. Aksyuk, PiscataWay;
`David J. Bishop, Summit; Joseph E.
`Ford, Oakhurst; James A. Walker,
`Howell, all of NJ (US)
`
`(73)
`
`Assignee: Lucent Technologies Inc., Murray Hill,
`NJ (US)
`
`Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`(21)
`(22)
`
`(60)
`
`(51)
`
`(52)
`
`(58)
`
`Appl. No.: 08/968,935
`Filed:
`Nov. 12, 1997
`
`Related U.S. Application Data
`Provisional application No. 60/056,482, ?led on Aug. 21,
`1997.
`
`Int. Cl.7 .................................................... .. H04J 14/02
`
`U.S. Cl. ........................ .. 359/131; 359/124; 359/129;
`385/24
`
`Field of Search .......................... .. 359/124, 129—131,
`359/128; 385/24
`
`/10
`
`Petitioner Ciena Corp. et al.
`Exhibit 1017-1
`
`

`

`U.S. Patent
`
`Mar. 20, 2001
`
`Sheet 1 0f 2
`
`US 6,204,946 B1
`
`FIG. 1
`
`FIG. 2
`
`AQUEPEPEPWQJ
`
`32/
`
`Petitioner Ciena Corp. et al.
`Exhibit 1017-2
`
`

`

`U.S. Patent
`
`Mar. 20, 2001
`
`Sheet 2 of 2
`
`US 6,204,946 B1
`
`FIG‘. 3
`
`10
`
`I
`won REFLECT/TRANSMIT
`
`°1R°”L“°“
`
`Petitioner Ciena Corp. et al.
`Exhibit 1017-3
`
`

`

`US 6,204,946 B1
`
`1
`RECONFIGURABLE WAVELENGTH
`DIVISION MULTIPLEX ADD/DROP DEVICE
`USING MICROMIRRORS
`
`RELATED APPLICATION
`
`This application claims priority from US. Provisional
`Patent Application Ser. No. 60/056,482 Which Was ?led on
`Aug. 21, 1997.
`
`BACKGROUND OF THE INVENTION
`
`I. Field of the Invention
`This invention relates to optical devices for adding and
`dropping optical signals to an optical ?ber carrying existing
`optical signals Without interfering With the existing optical
`signals. More particularly, the present invention is directed
`to a Wavelength division multiplex add/drop optical device
`using a rnicrornirror array for transmitting and re?ecting
`optical signals in an optical communications system.
`II. Description of the Related Art
`In Wavelength division rnultiplexed optical netWorks it is
`increasingly important to be able to sWitch rnultiple inde
`pendent Wavelength signals into and out of a single ?ber
`Without disturbing the other channels. This task is presently
`accomplished by utiliZing an assembly of separate compo
`nents such as a pair of Wavelength dernultiplexers and a set
`of N tWo-by-tWo bypass exchange sWitches. As is knoWn,
`one of the Wavelength dernultiplexers, also knoWn as a
`router, separates a rnultifrequency optical input data signal
`into N rnultiple ?bers, With each ?ber carrying a single
`Wavelength. The bypass exchange sWitches accept the added
`and dropped channels. The other Wavelength rnultiplexer
`combines the existing Wavelengths With the added Wave
`lengths onto a single ?ber for transmission in the commu
`nications systern. Among the draWbacks of such a discrete
`cornponent approach, hoWever, are the cost and siZe of the
`individual components and the resulting overall cost and
`siZe of the system.
`
`SUMMARY OF THE INVENTION
`A Wavelength division rnultiplexed (WDM) transrnit/
`re?ect unit is disclosed for transmitting and re?ecting select
`Wavelengths of a rnultiWavelength optical signal onto optic
`?bers in an optic communications network. The transrnit/
`re?ect unit includes a lens positioned at a ?rst port and a
`second port for directing the incoming optical signal to a
`planar grating Wavelength rnultiplexer Which angularly dis
`perses the Wavelengths in the signal. Afocusing lens focuses
`the angularly dispersed Wavelengths for receipt by a rnicro
`rnirror array sWitchable betWeen a transrnitting mode and a
`re?ecting mode. The transrnitting rnode directs select Wave
`lengths of the incoming signal from one port to the other port
`and the re?ecting rnode directs an incoming signal from the
`?rst port back to the ?rst port.
`Arecon?gurable WDM add/drop device is also disclosed.
`The add/drop device employs a WDM transrnit/re?ect unit,
`of the type described above, Which is disposed betWeen ?rst
`and second 3-port circulators. The ?rst circulator interfaces
`With one port on the transrnit/re?ect unit and receives, from
`an input port, an input rnultiWavelength optical signal and
`outputs, to an output port, a rnultiWavelength optical signal.
`The second circulator interfaces With another port on the
`transrnit/re?ect unit. The second circulator receives, from.
`an add port, a Wavelength to be added to the rnultiWave
`length signal, and transmits, to a drop port, a Wavelength to
`be dropped from the rnultiWavelength signal.
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`55
`
`60
`
`65
`
`2
`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 for purposes of illustration and not as a
`de?nition of the limits of the invention, for Which reference
`should be made to the appended claims.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`In the draWings, Wherein like reference numerals denote
`sirnilar elements throughout the several vieWs:
`FIG. 1 is a diagrammatic representation of an optical
`transrnit/re?ect unit in accordance With the present inven
`tion;
`FIG. 2 depicts a single column rnicrornirror array;
`FIG. 3 is a block diagram of a WDM add/drop device in
`accordance With the present invention; and
`FIG. 4 depicts a dual colurnn rnicrornirror array.
`
`DETAILED DESCRIPTION OF THE
`PRESENTLY PREFERRED EMBODIMENTS
`
`The present invention utiliZes a rnodi?ed attenuation unit
`10 as shoWn in FIG. 1, Which is the subject of US. patent
`application Ser. No. 08/690,696 ?led on Jul. 31, 1996
`entitled “Attenuation Device For Wavelength Multiplexed
`Optical Fiber Cornrnunications”, the entirety of Which is
`incorporated by reference herein. As shoWn, unit 10 includes
`a planar grating Wavelength multiplexer 12 and a modulator
`array 14. Unit 10 has a ?rst port 16 Which receives optical
`signals from an optical ?ber 5 carrying rnultiple Wave
`lengths. The light frorn the optical ?ber 5 input at port 16 is
`collirnated by a collirnating lens 18 and is then diffracted by
`the planar grating 12 so that each Wavelength in the optical
`signal provided to port 16 is dispersed, ie the various
`Wavelengths leave the grating 12 at different angles from
`each other. The dispersed light is then focused by a lens 20
`onto the modulator array 14 to produce a column of spots,
`With each spot position in the column of spots corresponding
`to a particular Wavelength in the input signal.
`As explained more fully in the aforementioned US.
`patent application Ser. No. 08/690,696, rnodulator array 14
`has a re?ective surface and includes a column of variable
`attenuators positioned to coincide With the location of spots
`in the column of spots. The attenuators are re?ective rnicro
`rnechanical devices Whose re?ectivity can be electrically
`controlled. Each spot corresponding to each Wavelength in
`the focused signal is incident on a different attenuator, thus
`alloWing individual control of the transmitted intensity for
`each Wavelength. The rnodulator 14 is placed With its
`re?ective surface normal to the optical axis of the unit 10 so
`that the attenuated light re?ected from the modulator 14 can
`be collected and collirnated by a second pass through
`focusing and collirnating lens 20. Lens 20 is positioned such
`that the original incident beam (the beam travelling in the
`direction of arroWsA and B) illurninates a different region of
`the surface of lens 20 than the surface illuminated by the
`re?ected beam (the beam travelling in the direction of
`arroWs C and D). In other Words, there is no spatial over
`lapping of the re?ective beam with the incident beam on lens
`20.
`After the attenuated signals from rnodulator array 14 are
`collirnated by lens 20, the collirnated signals propagate back
`toWards the grating 12 Which then diffracts the light to
`combine all of the Wavelengths of the collirnated signals into
`the same angle and redirects the light toWards the input
`
`Petitioner Ciena Corp. et al.
`Exhibit 1017-4
`
`

`

`US 6,204,946 B1
`
`15
`
`25
`
`35
`
`3
`collimating lens 18. Since, as discussed above, the re?ected
`light is laterally displaced as a result of the position of lens
`20, a fold mirror 22 may be introduced to direct only the
`attenuated re?ected light into an output collimating lens 24
`Which is used to focus the light onto a separate output ?ber
`7 positioned at a second port 26. In such a con?guration, the
`multiple Wavelength attenuator unit 10 can be used as a
`functionally transmissive component. In other Words, light
`entering from one ?ber 5 through ?rst port 16 is affected by
`the modulator 14 and continues into a separate and distinct
`output ?ber 7 positioned at the second port 26.
`In accordance With the present invention, the attenuation
`unit 10 of FIG. 1 is modi?ed by replacing the modulator
`array 14 With a micromechanical mirror array; the somodi
`?ed unit 10 can then be used as a WDM transmit/re?ect
`sWitch operable in a re?ective mode and in a transmissive
`mode. In the transmissive mode, select Wavelengths are
`directed or transmitted from ?rst port 16 to second port 26.
`In the re?ective mode, select Wavelengths input at ?rst port
`16 are re?ected back to that same port. In particular, and
`With reference to FIG. 2, a micromechanical mirror array 30
`having a plurality of micromirror plates 32 arranged in a
`single column is shoWn. Mirror array 30 is designed so that
`each incoming optical Wavelength—Which, as explained
`above, is represented by a spot in a column of spots—
`illuminates a separate micromirror plate 32 in the micro
`mirror array. Each micromirror plate 32 can be electrically
`controlled to toggle betWeen tWo or more angular states so
`that each micromirror plate Will orient its corresponding
`re?ected Wavelength into one of tWo or more directions.
`In a preferred embodiment, the micromirror array 30 is
`designed With an appropriate micromirror plate pitch, tilt
`angle, and tilt axis such that in one state (“off”) the re?ected
`light is directed to the output collimating lens 24 and second
`port 26, and in the other mirror state (“on”) the light is
`re?ected back onto the same path by Which it entered the
`micromirror so that the light is returned to the ?rst colli
`mating lens 18 and directed back to the input ?ber through
`?rst port 16.
`Thus, as explained above, by replacing modulator 14 in
`the attenuation unit 10 of FIG. 1 With mirror array 30, there
`is formed a WDM transmit/re?ect unit that can operate in a
`transmissive mode and in a re?ective mode. The WDM
`sWitch may be placed in an optical ?ber path carrying
`multiple Wavelengths to selectively re?ect or transmit each
`individual Wavelength, depending on a set of electrical
`control signals applied to the mirror array plates 32. The
`response time of the WDM sWitch is determined by the
`mirror array 30, i.e. by the toggle time for the individual
`micromirror plates 32.
`In general, it is possible for the WDM sWitch 10 to operate
`in three states, namely
`to re?ect a signal input at port 16
`back to port 16, (ii) to transmit a signal input at port 16 to
`port 26 and vice versa; and (iii) to re?ect a signal input at
`port 26 back to port 26. In the transmissive mode Wherein
`the mirror array 30 is set to transmit a particular Wavelength
`from one port to the other, light at the particular Wavelength
`Which enters ?ber port 16 Will be carried to ?ber port 26.
`Similarly, and because of the symmetrical property of the
`optical path, light at that particular Wavelength Which enters
`?ber port 26 Will be transmitted to ?ber port 16. In a
`re?ective mode, hoWever, the reversible property of the
`optical path is not present because the angle of the micro
`mirror Which re?ects one incident beam Will cause light
`from the other port. to be re?ected at an angle of tWice the
`original incident angle. Therefore, When the WDM transmit/
`re?ect unit of FIG. 1 operates in a re?ective mode to re?ect
`
`45
`
`55
`
`65
`
`4
`a particular Wavelength, light at the particular Wavelength
`Which enters ?ber port 16 Will be re?ected back to ?ber port
`16, i.e. Will not be transmitted to ?ber port 26. When, on the
`other hand, light at the particular Wavelength enters ?ber
`port 26, the signal Will not re?ect back to ?ber port 26.
`In accordance With the present invention, the modi?ed
`tWo state transmit/re?ect unit 10 is used as an element of a
`WDM add/drop device 40, as illustrated, by Way of example,
`in FIG. 3. As there shoWn, the WDM transmit/re?ect unit 10,
`i.e. the attenuator shoWn in FIG. 1 With mirror array 30 (FIG.
`2) substituted for modulator 14, is placed betWeen a ?rst and
`a second 3-port optical circulator 42, 44. A 3-port optical
`circulator is a commercially available device Which transfers
`an input signal at port C1 to port C2, and Which transfers an
`input signal at port C2 to port C3. The ?rst circulator 42
`receives a WDM input data stream 46 and passes it to port
`1 (corresponding to the ?rst port 16 in FIG. 1) on the WDM
`transmit/re?ect unit 10. For Wavelengths Which are to be
`carried Without change (i.e. Wavelengths neither added nor
`dropped), the corresponding micromirrors in sWitch 10 are
`set to re?ect ?rst port 16, i.e. to re?ect those Wavelengths
`back to ?rst port 16. The re?ected signals enter circulator 42
`through port C2 and are carried by the circulator to port C3,
`Where they continue in the optical netWork as a WDM output
`data stream 48.
`In the transmissive mode, the inventive WDM add/drop
`device 40 is con?gured to add a Wavelength to the WDM
`input 46 only When a Wavelength is dropped. Thus, in the
`transmissive mode, unit 10 is activated to pass or transmit
`through its second port the Wavelength to be dropped to
`circulator 44 and to pass or transmit the Wavelength to be
`added from circulator 44 to circulator 42. In particular, the
`transmitted (to-be-dropped) Wavelength leaves unit 10
`through its ?ber port 2 and enters the second circulator 44
`through its port C2, and leaves the circulator through a ?ber
`connected to circulator port C3. A router 50 connected to
`port C3 can be included for WDM demultiplexing so that the
`dropped Wavelength may be directed into separate ?bers, as
`is knoWn in the art to, for example, direct the dropped
`Wavelength to doWnstream optical netWork units. Wave
`lengths that are to be added are provided to an input router
`52 Which multiplexes the Wavelengths to a single ?ber
`connected to port Cl of circulator 44. The incoming (to-be
`added) Wavelengths at port Cl of circulator 44 Will be
`transmitted by device 10, i.e. by activating the mirror plate
`32 corresponding to the added Wavelength to transmit the
`added Wavelength. The transmitted added Wavelength is
`then combined onto the WDM output signal 48.
`With reference noW to FIG. 4, a preferred embodiment of
`the micromirror array 30 is depicted. As shoWn, the micro
`mirror array has tWo columns of mirrors 32‘ separated by
`loW re?ectivity surround 33. The mirrors are deposited on
`plates suspended betWeen pivots 34 so as to enable them to
`tilt about an axis. In the preferred embodiment, the tilt axis
`is chosen so as to provide maximum coupling and minimum
`crosstalk. The mirror position is controlled by a voltage
`applied to electrodes 35 connected to individually addressed
`electrical pads (not shoWn) located beloW the mirrors. An
`electrostatic force that is generated by the applied voltage
`betWeen the pads and the mirrors 32‘ de?ects the addressed
`mirror to one of the tWo angular states.
`The WDM add/drop device 40 can be used to simulta
`neously process more than one multifrequency optical sig
`nal. For example, and again With reference to FIG. 1,
`multiple ?bers each carrying a multifrequency signal can be
`coupled to ports 16 and 26. As Will be readily apparent from
`the foregoing discussion, each optical signal carried by each
`
`Petitioner Ciena Corp. et al.
`Exhibit 1017-5
`
`

`

`US 6,204,946 B1
`
`10
`
`15
`
`5
`optical ?ber Will produce a corresponding column of spots,
`With the position of each spot in each column corresponding
`to a particular Wavelength. Thus, a pair of input ?bers placed
`side-by-side Will create tWo parallel roWs of spots at the
`micromechanical mirror array 30. By con?guring microme
`chanical mirror array 30 so that it contains multiple columns
`of mirrors as for example shoWn in FIG. 4, ie a mirror
`column for each column of spots, multiple optical signals
`can be simultaneously processed by the micromechanical
`mirror array 30 through a single WDM add/drop device 40.
`In other Words, a single set of lenses 18, 20 and 24, and a
`single planar grating 12, all sharing a common alignment,
`can be used in accordance With the invention to simulta
`neously process multiple multifrequency optical signals.
`In optical ?ber components, it is generally important to
`minimiZe the polariZation dependence loss. HoWever, the
`diffraction grating 12 used to separate the Wavelengths tends
`to have a different diffraction ef?ciency for horiZontal and
`for vertical input polariZation. This variation can be large,
`especially for gratings With a relatively ?ne spatial fre
`quency of several hundred lines per millimeter or more. One
`Way to minimiZe the net polariZation dependence is to pass
`the polariZation dependent element in both directions With a
`90 degree polariZation rotation betWeen the passes. In this
`manner, the signal on the ?rst pass experiences a ?rst
`polariZation loss and the return signal experiences a second
`polariZation loss. The result is that any input polariZation
`Will experience the average loss.
`Any ?ber-coupled component can be rendered polariZa
`tion independent in this manner provided that it can be
`doubled, Where the polariZation rotation can be accom
`plished by an appropriate ?ber-coupled device. In the optical
`system of FIG. 1, the grating 12 is the only component that
`is polariZation dependent, and it is already double passed in
`that the optical signal is re?ected from the grating in a
`forWard direction as shoWn by arroWs A and B, and in a
`reverse or return direction as shoWn by arroWs C and D. By
`placing a polariZation rotating element 56 into the system, as
`for example betWeen the grating 12 and lens 20, the losses
`are averaged in a single round trip through the device 10.
`One such optical element that can accomplish at least an
`approximate 90 degree polariZation rotation is, by Way of
`example, a quarter Wave plate having an appropriate angular
`orientation With respect to the grating 12. With this simple
`addition, the polariZation dependent losses of the WDM
`45
`add/drop sWitch 40 can be reduced.
`Although the preferred embodiments are described here
`inabove using speci?c optical elements such as a collimating
`and focusing lens 20 and a dispersion grating 12 to disperse
`and focus Wavelengths of a multiple-Wavelength optical
`signal, other optical elements can be used to perform this
`function Without departing from the scope of the present
`invention. For example, a diffractive optical element such as
`an off-axis holographic lens can be used to perform both
`imaging and dispersing. For such elements, there is no need
`for a collimator lens and a collimated beam Would not be
`required. Alternatively, a sequence of volume holographic
`elements can be used Which each element diffracting a single
`Wavelength toWards the micromirror array 30 at a distinct
`angle. Furthermore, a superimposed volume hologram can
`be used Where multiple distinct holograms are recorded in a
`single volume in individually direct distinct Wavelengths.
`Lastly, a sequence of multilayer dielectric thin ?lm mirrors
`can be employed With each mirror designed to re?ect only
`a selected subset of Wavelengths into a particular angle.
`Thus, While there have shoWn and described and pointed
`out fundamental novel features of the invention as applied to
`
`55
`
`6
`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
`from the spirit of the invention. For example, it is expressly
`intended that all combinations of those elements Which
`perform substantially the same function in substantially the
`same Way to achieve the same results are Within the scope
`of the invention. It is the intention, therefore, to be limited
`only as indicated by the scope of the claims appended
`hereto.
`We claim:
`1. A WDM transmit/re?ect unit for selectively transmit
`ting a select Wavelength of a multiple-Wavelength optical
`signal from at least one ?rst optic ?ber to at least one second
`optic ?ber and re?ecting the select Wavelength from the at
`least one ?rst optic ?ber back to the at least one ?rst optic
`?ber, said unit comprising:
`a ?rst port for receiving the multiple-Wavelength optical
`signal from the at least one ?rst optic ?ber;
`a ?rst lens for collimating the received multiple
`Wavelength optical signal;
`means for angularly displacing from each other individual
`ones of the multiple Wavelengths in the collimated
`multiple-Wavelength optical signal When the multiple
`Wavelength optical signal is travelling in a ?rst
`direction, and for angularly combining the individual
`Wavelengths of the multiple-Wavelength optical signal
`When the multiple-Wavelength optical signal is travel
`ling in a second direction;
`a second lens for focusing the angularly displaced Wave
`lengths When the multiple-Wavelength signal is travel
`ling in the ?rst direction and for collimating the
`multiple-Wavelength signal When the multiple
`Wavelength signal is travelling in the second direction;
`a micromirror array for receiving the multiple-Wavelength
`signal from the second lens and selectively sWitchable
`betWeen a transmission mode for transmitting the select
`Wavelength to the at least one second optic ?ber and a
`re?ection mode for re?ecting the select Wavelength to
`the at least one ?rst optic ?ber;
`a second port connected to the second ?ber for receiving
`the de?ected angularly combined optical signal from
`said angularly displacing means When the array is in the
`transmit mode; and
`a third lens positioned betWeen said grating and said
`second port for focusing the angularly combined
`multiple-Wavelength signal onto said second port for
`receipt by the second ?ber.
`2. The WDM transmit/re?ect unit of claim 1, Wherein
`When said micromirror array is in said transmission mode,
`and When a second multiple-Wavelength signal is present at
`said second port, the second multiple-Wavelength signal is
`transmitted to said ?rst port.
`3. The WDM transmit/re?ect unit of claim 1, Wherein said
`micromirror array comprises a plurality of mirror plates,
`With each plate positioned for receiving one of the individual
`Wavelengths of said multiple-Wavelength signal.
`4. The WDM transmit/re?ect unit of claim 3, Wherein
`each mirror plate is responsive to an electrical signal for
`selectively activating each plate betWeen the transmission
`mode and the re?ection mode.
`5. The WDM transmit/re?ect unit of claim 3, Wherein
`each mirror plate is responsive to an electrical signal for
`selectively reorienting each plate betWeen the transmission
`mode and the re?ection mode.
`
`25
`
`35
`
`65
`
`Petitioner Ciena Corp. et al.
`Exhibit 1017-6
`
`

`

`US 6,204,946 B1
`
`15
`
`7
`6. The WDM transrnit/re?ect unit of claim 3, wherein said
`rnicrornirror array has a vertical axis, Wherein each rnirror
`plate has a vertical axis, and each said rnirror plates is
`arranged so that its vertical axis is angularly offset from the
`vertical axis of said rnirror array.
`7. The WDM transrnit/re?ect unit of claim 6, Wherein
`each said rnirror plate of the rnicrornirror array is selectively
`rotatable about its axis to transmit or re?ect select Wave
`lengths of the rnultiple-Wavelength optical signal.
`8. The WDM transrnit/re?ect unit of claim 1, Wherein said
`angularly displacing means comprises a grating.
`9. The WDM transrnit/re?ect unit of claim 3, Wherein said
`plural rnirror plates are arranged in a column.
`10. The WDM transrnit/re?ect unit of claim 3, Wherein the
`at least one ?rst optic ?ber comprises a ?rst plurality of optic
`?bers, each providing a rnultiple-Wavelength optical signal
`to said ?rst port, Wherein the at least one second optic ?ber
`comprises a second plurality of optic ?bers, equal in number
`to the plurality of ?rst optic ?bers and each of the second
`optic ?bers receiving an angularly cornbined de?ected
`rnultiple-Wavelength signal from said second port, and
`Wherein said plural rnirror plates are arranged to form a
`plurality of columns of said rnirror plates equal in number of
`columns to the plurality of optic ?bers in the ?rst plurality
`of optic ?bers, and Wherein each said column of mirror
`plates comprises a plural number of mirror plates at least
`equal to the multiple Wavelengths in each rnultiple Wave
`length optical signal.
`11. The WDM transrnit/re?ect unit of claim 1, further
`comprising a de?ecting elernent positioned betWeen said
`angularly displacing means and said third lens for de?ecting
`the angularly cornbined rnultiple-Wavelength signal to the at
`least one second optic ?ber When the array is in the trans
`rnitting mode.
`12. The WDM transrnit/re?ect unit of claim 1, further
`comprising a polariZation dependent optical cornponent
`positioned betWeen said angularly displacing means and said
`second lens.
`13. The WDM transrnit/re?ect unit of claim 12, Wherein
`said polariZation dependent optical cornponent comprises a
`quarter-Wave plate.
`14. A WDM add/drop device for adding Wavelengths to
`and dropping Wavelengths from a rnultiple-Wavelength opti
`cal signal in an optical communication system, comprising:
`an input port for receiving a WDM rnultiple-Wavelength
`input optical signal from at least one ?rst optic ?ber;
`an output port for outputting a WDM rnultiple
`Wavelength output optical signal to at least one second
`optic ?ber;
`a WDM add port for receiving as an input an add
`Wavelength to be added to the rnultiple-Wavelength
`optical signal;
`a WDM transrnit/re?ect unit having a ?rst port and a
`second port for transmitting one of the multiple Wave
`lengths of the rnultiple-Wavelength signal from the ?rst
`port to the second port in a ?rst direction, for trans
`rnitting the added Wavelength from the second port to
`the ?rst port in a second direction, and for re?ecting
`one of the multiple Wavelengths of the multiple
`Wavelength signal from the ?rst port back to the ?rst
`port;
`a ?rst rnultiport circulator disposed betWeen said WDM
`input port, said WDM output port and said ?rst port of
`said WDM transrnit/re?ect unit, said circulator being
`operable for receiving the WDM rnultiple-Wavelength
`input signal from said input port and providing the
`65
`WDM input signal to said ?rst port of said WDM
`transrnit/re?ect unit and for receiving the WDM
`
`25
`
`35
`
`45
`
`55
`
`8
`rnultiple-Wavelength signal re?ected by said WDM
`transrnit/re?ect unit and the added Wavelength trans
`rnitted by said WDM transrnit/re?ect unit and provid
`ing the received re?ected WDM rnultiple-Wavelength
`signal and added Wavelength to said output port;
`a WDM drop port for outputting from the WDM input
`signal, one of the multiple Wavelengths dropped from
`the WDM rnultiple-Wavelength optical signal transmit
`ted by said WDM transrnit/re?ect unit; and
`a second circulator disposed betWeen said WDM add port,
`said WDM drop port and said second port of said
`WDM transrnit/re?ect unit for forWarding one of the
`multiple transrnitted Wavelengths from the WDM
`transrnit/re?ect unit to said WDM drop port and for
`forWarding the WDM added Wavelength from said
`WDM add port to said second port of said WDM
`transrnit/re?ect unit.
`15. The WDM add/drop device of claim 14, Wherein said
`WDM transrnit/re?ect unit further comprises a rnicrornirror
`array having a plurality of mirror plates, With each plate
`positioned for receiving one of the Wavelengths of said
`rnultiple-Wavelength input optical signal, and means for
`optical Wavelength dernultiplexing of the multiple Wave
`length signal onto said plurality of mirror plates.
`16. The WDM add/drop device of claim 15, Wherein each
`rnirror plate in said rnicrornirror array is responsive to an
`electrical signal for selectively activating each plate betWeen
`transmission and re?ection modes of the WDM transrnit/
`re?ect unit.
`17. The WDM add/drop device of claim 15, Wherein each
`rnirror plate in said rnicrornirror array is responsive to an
`electrical signal for selectively reorienting each plate
`betWeen a transmission mode and a re?ection mode.
`18. The WDM add/drop device of claim 15, Wherein said
`rnicrornirror array has a vertical axis, Wherein each rnirror
`plate has a vertical axis, and Wherein each said rnirror plate
`is arranged so that its vertical axis is angularly offset from
`the vertical axis of said rnirror array.
`19. The WDM add/drop device of claim 15, Wherein each
`said rnirror plates of the rnicrornirror array is selectively
`rotatable about its axis to transmit or re?ect select Wave
`lengths of the rnultiple-Wavelength optical signal.
`20. The WDM add/drop device of claim 15, Wherein said
`plural rnirror plates are arranged in a column.
`21. The WDM add/drop device of claim 15, Wherein said
`?rst port comprises a ?rst port on a multiple port circulator
`and said second port comprises a second port on said
`rnultiple port circulator, Wherein the at least one ?rst optic
`?ber comprises a ?rst plurality of optic ?bers, each provid
`ing a rnultiple-Wavelength optical signal to said ?rst port,
`Wherein the at least one second optic ?ber comprises a
`second plurality of optic ?bers, equal in number to the
`plurality of ?rst optic ?bers and each of the second optic
`?bers receiving an output rnultiple-Wavelength optical sig
`nal from said second port, and Wherein said plural rnirror
`plates are arranged to form a plurality of columns of said
`rnirror plates equal in number of columns to the plurality of
`optic ?bers in the ?rst plurality of optic ?bers, and Wherein
`each said column of mirror plates comprises a plural number
`of mirror plates at least equal to the multiple Wavelengths in
`each rnultiple-Wavelength optical signal.
`22. AWDM transrnit/re?ect unit for selectively transrnit
`ting a select Wavelength of a rnultiple-Wavelength optical
`signal from a ?rst optic ?ber to a second optic ?ber and
`re?ecting the select Wavelength from the ?rst optic ?ber
`back to the ?rst optic ?ber, said unit comprising:
`a ?rst port for receiving the rnultiple-Wavelength optical
`signal from the ?rst ?ber;
`
`Petitioner Ciena Corp. et al.
`Exhibit 1017-7
`
`

`

`US 6,204,946 B1
`
`means for angularly displacing from each other individual
`ones of the multiple Wavelengths in the multiple
`Wavelength optical signal When the multiple
`Wavelength optical signal is travelling in a ?rst