(12) United States Patent
`(10) Patent N0.:
`US 6,256,430 B1
`
`Jin et al.
`(45) Date of Patent:
`Jul. 3, 2001
`
`USOO6256430B1
`
`(54) OPTICAL CROSSCONNECT SYSTEM
`COMPRISING RECONFIGURABLE LIGHT-
`REFLECTING DEVICES
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`(75)
`
`Inventors: Sungho Jin, Millington; Neal Henry
`Thorsten, Lebanon, both of NJ (US)
`
`(73) Assignee: Agere Systems Inc., Miami Lakes, FL
`(US)
`
`( *) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(1),) by 0 days.
`
`(21) APPI- N05 09/191800
`(22)
`Filed:
`NOV. 23, 1998
`
`(51)
`
`Int (:17
`
`G02B 6/26
`
`.................................. 385/18; 385/17; 385/37
`(52) US. Cl.
`(58) Field of Search .................................. 385/16, 17, 18,
`385/20, 21, 22, 23, 37
`
`................................. 385/16
`8/1991 Benzoni
`5,042,889 *
`5,581,643 * 12/1996 WU ---------------
`385/18
`
`5,974,207 * 10/1999 Aksyuk et a1.
`385/24
`..
`5,999,546 * 12/1999 Espindola et a1.
`385/37
`
`................................ 385/37
`
`5,999,671 * 12/1999 Jin et a1.
`* cited by examiner
`Primary Examiner—Frank G. Font
`Assistant Examiner—Sang II. Nguyen
`(74) Attorney, Agent, or Firm—Lowenstein Sandler PC
`_
`ABSTRACT
`(37)
`In accordance With the invention, an optical switching
`device comprises a light-reflecting mirror containing a mag-
`netic component coupled to a substrate. One or more pro—
`grammable magnets are prov1ded for movmg the mirror by
`interacting with the magnetic component. The program-
`mable magnets move the mirrors between or among selected
`positions and then maintain the mirror position Without
`continuous power. Exemplary cross connects and 2x2
`'t h
`d
`'b d.
`SW” es are em 6
`9 Claims, 6 Drawing Sheets
`
`
`
`FNC 1020
`
`

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`US. Patent
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`Jul. 3, 2001
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`Sheet 1 0f 6
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`US 6,256,430 B1
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`

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`US. Patent
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`Jul. 3, 2001
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`Sheet 2 0f 6
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`US 6,256,430 B1
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`9 fl
`N .o
`
`g
`m y
`H 2
`LL
`
`H(OR3)
`
`9-:
`
`1:
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`co
`
`m g
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`LL
`
`FIG.2A
`
`

`

`US. Patent
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`Jul. 3, 2001
`
`Sheet 3 0f 6
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`US 6,256,430 B1
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`FIG. 3
`
`
`
`FIG.
`
`4A
`
`42D
`
`42A
`
`42C
`
`423
`
`

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`US. Patent
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`Jul. 3, 2001
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`Sheet 4 0f 6
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`US 6,256,430 B1
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`
`
`
`41C
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`410
`
`41A
`
`413
`
`

`

`US. Patent
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`Jul. 3, 2001
`
`Sheet 5 0f 6
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`US 6,256,430 B1
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`
`
` FIBER A (INPUT) “ g :10 X FIBERc (ourpun
`
`
`FIBERB (OUTPUT)
`:
`5
`FIBERB (INPUT)
`y ”Nu--
`
`
`
`FIBER C
`c,__L, :D
`FIBER A
`—>I:F ---------------------9:09
`
`FIBER B
`
`
`FIBER 0
`
`10
`
`

`

`US. Patent
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`Jul. 3, 2001
`
`Sheet 6 0f 6
`
`US 6,256,430 B1
`
`FIG. 7
`
`14
`
`
`
`
`
`FIBER C
`(INPUT)
`
`51
`
`
`
`
`FIBER D
`(OUTPUT)
`
`FIBER A .
`
`(INPUT)
`
`
`
`
`
`FIBER B
`(OUTPUT)
`
`

`

`US 6,256,430 B1
`
`1
`OPTICAL CROSSCONNECT SYSTEM
`COMPRISING RECONFIGURABLE LIGHT-
`REFLECTING DEVICES
`
`FIELD OF THE INVENTION
`
`This invention pertains to improved optical switches for
`altering light transmission paths, and, in particular, to mag-
`netically programmable and latchable optical switches.
`BACKGROUND OF THE INVENTION
`
`In modern lightwave telecommunication systems such as
`wavelength-division-multiplexed (WDM) optical
`fiber
`systems, it is often necessary to switch the path of trans-
`mitted light. A number of different approaches have been
`utilized. Switching has been eifected by mechanical move-
`ment of optical fibers (see P. G. Hale et al., Electronic Lett.,
`vol. 12, p. 388,1976, and Y. Ohmori et al.,Appl. Optics, vol.
`17, p. 3531, 1978). Switching can also be based Faraday
`rotation (see M. Shirasaki et al., Appl. Optics, Vol. 23, p.
`3271, 1984).
`Switching based on reflecting mirrors is particularly
`attractive for communication systems but has not yet
`achieved its potential.
`(see Tanaka et a/. U.S. Pat. No.
`4,498,730, L. Y. Lin et al, IEEE Photonics Technology Lett.,
`Vol. 10, p. 525,1998, R. A. Miller et al., Optical Eng., Vol.
`36, p. 1399, 1997, and by J. W. Judy et al., Sensors and
`Actuators, Vol. A53, p. 392, 1996). Switches using reflecting
`mirrors are convenient
`in that they use free-space light
`transmission and are potentially expandable to a large-scale
`optical crossconnect system. They typically employ
`electrostatic, piezoelectric or electromagnetic actuation
`means to move or rotate the mirrors and alter the light paths.
`The problem with these devices is that they either require the
`use of continuous application of power to maintain the
`shifted mirror position or their position is unstable. For
`example electrostatic devices are prone to charge build up
`and leakage, and hence are very sensitive to environment.
`Accordingly there is a need for latchable optical switches in
`which power is not required once the light path is shifted to
`a desired direction and for which the latched position is
`stably maintained.
`SUMMARY OF THE INVENTION
`
`In accordance with the invention, an optical switching
`device comprises a light—reflecting mirror containing a mag—
`netic component movably coupled to a substrate. One or
`more programmable magnets are provided for moving the
`mirror by interacting with the magnetic component. The
`programmable magnets move the mirrors between or among
`selected positions and then maintain the mirror position
`without continuous power. Exemplary cross connects and
`2x2 switches are described.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The advantages, nature and additional features of the
`invention will appear more fully upon consideration of the
`illustrative embodiments described in the accompanying
`drawings. In the drawings:
`three-
`FIG. 1 schematically illustrates an exemplary,
`dimensionally programmable and latchable optical switch;
`FIGS. 2(a)—(c) a graphical representations, useful
`in
`understanding the invention, of mag tizati M (or correspond-
`ing mirror displacement 5 vs applied field curves for a
`latchable magnet;
`FIG. 3 schematically illustrates a cross-sectional view of
`programmable, free-space, optical switch with a plurality of
`light reflecting mirrors;
`
`10
`
`15
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`FIGS. 4(a) and 4(b)illustrate a programmable and latch-
`able optical cross connect system in two and three dimen-
`sions respectively;
`FIG. 5 illustrates an alternative programmable and latch-
`able optical switch;
`FIGS. 6(a)and 6(b) schematically illustrate a program-
`mable and latchable 2x2 optical switch; and
`FIG. 7 illustrates an alternative 2x2 optical switch.
`It is to be understood that these drawings are for purposes
`of illustrating the concepts of the invention and are not to
`scale. The same reference numerals are used to designate
`similar elements throughout the drawings.
`DETAILED DESCRIPTION
`
`Referring to the drawings, FIG. 1 schematically illustrates
`an exemplary programmable and latchable, light-reflecting
`switch 9 comprising a mirror 10 including a magnetizable
`component 11. The mirror is movably coupled to substrate
`12 by a movable support 13, and one or more programmable
`and latchable magnets 14 (here three magnets: 14A, 14B,
`and 14C) are provided for controlling the mirror position.
`Each programmable magnet 14 comprises a magnet com-
`ponent 15 and a controlling solenoid 16. The mirror 10
`changes the path of an incoming light signal, e.g., a beam
`from a laser or a waveguide,
`toward a desired output
`direction, such as to a specific waveguide channel, an optical
`amplifier or a photodetector.
`The mirror 10 can be completely reflective (e.g., made
`with a thick metallic coating on a substrate) or semi-
`transparent (e.g., made with a thin coating on a transparent
`substrate) allowing a part of the incoming light signal to pass
`and propagate straight. The mirrors can be macroscopic or
`microscopic in size depending on specific applications. They
`can be made by micromachining similar to the fabrication of
`microelectromechanical systems (MEMs). Each mirror is
`made magnetizable, either by attaching (e.g., epoxying) or
`depositing (as by sputtering or electroplating) at least one
`magnetizable component 11 on a portion of the front or
`backside surface of the mirror 10.
`
`The movable support 13 between the mirror 10 and the
`substrate 12 is prepared in such a way that the mirror is
`three—dimensionally movable. The support can allow tilting,
`rotating, sliding, or twisting displacement of the mirror
`light-reflecting plane. The support 13 can be a mechanical
`hinge, a spring, a ball and socket, or a resilient member such
`as an elastically compliant extension of the substrate.
`At least one programmable and latchable magnet is pro-
`vided in the vicinity of each mirror 10. The programmable
`magnet typically consists of an elongated magnet 15 with
`specific desired magnetization and demagnetization
`characteristics, and a solenoid 16 comprising a winding
`surrounding the magnet. The solenoid can be a pre-made
`winding on a bobin, insulated wires directly wound around
`the magnet 15, or a thin, lithographically-defined thin film
`conductor pattern helically placed around the magnet (with
`a thin insulating layer placed between the conductor and the
`magnet). The solenoid 16, upon passing a predetermined
`amount of electrical current, supplies a magnetic field which
`is then amplified by the elongated magnet 15. In operation,
`the magnetic field from each of the programmable magnets
`14A, 14B, 14C attracts or repels the mirror through mag-
`netostatic interaction with the magnetizable component 11
`placed on the mirror.
`FIGS. 2(a)—(c) are graphical illustrations useful in under-
`standing the programmable and latching behavior of the
`switch. They show M-H magnetic hysteresis loop charac-
`teristics.
`
`

`

`US 6,256,430 B1
`
`3
`FIG. 2(a) illustrates a “square” hysteresis loop. With
`magnets exhibiting a square hysteresis loop, one can make
`bistable devices that switch between two magnetization
`levels, e.g., a mirror position corresponding to zero magnetic
`force and a saturation displacement position achieved with
`the maximum magnetic force. The zero magnetic force is
`achieved by applying an AC or DC demagnetizing field. The
`saturation displacement is achieved by a DC pulse current
`sufficient to saturate the magnets. However, for continuous
`tuning of the mirror position in any X, y or z direction, the
`square loop characteristic is not always desirable as the steep
`side of the curve in FIG. 2(a) can pose a control problem
`when a certain intermediate fiber displacement (6) is desired.
`FIG. 2(b) illustrates a skewed hysteresis loop. For ease of
`control, the M-H and 6-H loop can be skewed as shown in
`FIG. 2(b). This is achieved by increasing the selfdemagne-
`tizing field of the magnets e.g., by either increasing effective
`diameter of the magnet, reducing the length (and thus
`decreasing the magnet length-to-diameter aspect ratio), or
`by subdividing the magnet
`length with inserted gaps
`between divided magnet parts. The optimal skewing of the
`loop is as illustrated in FIG. 2(b), i.e., the remanent mag-
`netization or the remanent mirror displacement when the
`applied field is removed is still essentially the same as the
`saturation value (at least 90%), and the onset field of rapid
`decrease of M or 5 when the field is reversed is near zero
`
`field and preferably in the range of :50% the coercive force,
`even more preferably in the range of 110% of the coercive
`force (Hc). The desired degree of skewing of the loop is
`preferably a maximum loop shift by 50%4150% of Hc.
`FIG. 2(C) illustrates an excessively skewed hysteresis
`loop. An excessive skewing of the M-H or o-H loop is not
`desirable as this causes a deterioration of thc latchability of
`the fiber displacement. Such a deterioration in latchable
`displacement is indicated by arrows in FIG. 2(C).
`For applied magnetic fields of H1 and H2, the correspond-
`ing magnetization is latchably retained after the field is
`removed, and the corresponding displacement of the mirror
`position, 61 and 62, is also latchably retained. Therefore the
`device can be operated after actuation without continuous
`power. The degree of mirror displacement is altered and
`latchcd by changing the magnetization in the programmable
`magnets. This can be achieved by either increasing the
`applied field or by demagnetizing first and remagnetizing to
`a new field level. For example,
`to shift from 51 to 52 an
`applied field of H2 is used. To shift the mirror position from
`62 back to 51, a reverse polarity magnetic field is utilized.
`The magnitude of the field is selected so that the magneti—
`zation is reduced to the level corresponding to the displace-
`ment 51. When this field is removed the displacement 51 is
`latched. For magnetization of the magnets using a solenoid,
`a pulse field (a pulse current in the solenoid) can conve-
`niently be used for high-speed, low-power operation. The
`desired duration or speed of the pulse field is typically in the
`range of 10—10"6 seconds, preferably 10—10"4 seconds. The
`shape of the current pulse applied can be sinusoidal, rect-
`angular or irregular.
`The preferred programmable magnet materials for the
`latchable mirror devices are those whose magnetic proper-
`ties are modifiable by a pulse magnetic field. Some examples
`of suitable magnets are Fe—Cr—Co, Fe—Al—Ni—Co
`(Alnico), Cu—Ni—Fe (Cunife), and Co—Fe—V
`(Vicalloy). The desired range of the coercivity for the
`programmable magnet is typically below 500 Oe and pref-
`erably below 100 Oe for the ease of programming by
`remagnetization using solenoid pulse field. The coercivity is
`typically above 10 Oe and preferably above 30 Oe for
`
`10
`
`15
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`4
`maintaining the stability of the remanent magnetization and
`also for stability against demagnetization due to stray mag-
`netic fields. For satisfactory latchability of the shifted mirror
`position when the field is removed,
`the programmable
`magnet should preferably have a parallelogram-shaped mag-
`netization hysteresis loop with the squareness ratio (defined
`as
`a
`ratio of rcmancnt magnetization/saturation
`magnetization) of at least 0.85, preferably at least 0.90, even
`more preferably at least 0.95. For ease of control, the loop
`is desirably skewed by at least 50% of Hc. Mechanically
`
`ductile and easily formable or machineable magnet alloys
`such as Fe Cr Co, Cu Ni
`Fe, Co
`Fe V are particu-
`larly desirable for shaping into desired rod—like geometry
`shown in FIG. 1. Stable permanent magnets with high
`coercive forces (e.g., Hc>1000 Oe), such as Sm—Co,
`Nd—Fe—B ,or Ba ferrite, are less desirable (unless modi-
`fied to exhibit lower coercive forces) because of the diffi-
`culty in reprogramming the remanent magnetization using
`desirably low magnetic field.
`Apreferred magnet material is Fe—28%Cr—7%Co alloy
`which is deformation aged to yield a M-H loop with HC of
`70 Oe. The M-II loop is skewed by about 60 Oe, producing
`a M-H loop similar to FIG. 2(b).
`The number of programmable magnets 14A, 14B, 14C
`can be one, two, three or even more than three, depending
`on the nature of the device and the required degree of
`freedom for mirror repositioning. In general, three program—
`mable magnets or more are preferred in order to provide a
`three dimensional degree of freedom in the movement of the
`mirror. However, use of spring components or
`two-
`dimensional confinement of mirror movement can reduce
`the number of programmable magnets.
`A feedback system (not shown) can optionally be utilized
`to control the precise mirror position shift. Positional infor-
`mation can be used to activate additional, incremental, or
`reduced pulse current to one or more of the solenoids so as
`to obtain a revised latchable magnetization level and mirror
`position. This feedback and adjustment process can be
`repeated a number of times, if necessary, until the desired
`mirror position or angle is achieved.
`The optical switch can also be utilized for intentional
`misalignment of light so as to completely cut off the optical
`information from the light path (basically serving as an
`on-off switch). It can also be used to partially misalign the
`paths to provide a desired level of signal
`intensity to
`receiving optical path (thus serving as a latchable
`attenuator). The performance of the switch as a latchable
`attenuator depends on the control provided by the program-
`mable and latchable magnets.
`The magnetic component 11 attached or deposited on the
`mirror (preferably on the backside) can be made of a
`permanent magnet material such as Nd—Fe—B, Sm—Co,
`Al—Ni—Co, Fe—Cr—Co or Ba—ferrite. Alternatively, the
`magnetic component can be made of a soft magnetic mate-
`rial such as Ni—Fe (permalloy), Si-steel or metglas mate-
`rial. If a permanent magnet material is employed, magnetic
`attraction to as well as magnetic repulsion from the pro-
`grammable magnet can be utilized to induce a two-way
`movement of the mirror.
`
`the mirror 10 can take a 45
`As exemplary operation,
`degree inclined angle as the default position in the absence
`of actuation of any of the three programmable magnets 14A,
`14B, 14C. If the programmable and latchable magnets 14A
`and 14B are evenly magnetized, the mirror will be magneti-
`cally attracted and bend toward right to be more upright. If
`they are unequally magnetized, the mirror will bend to the
`
`

`

`US 6,256,430 B1
`
`5
`right but also with some torsional displacement allowing the
`mirror to take a different light-reflecting angle. If only the
`programmable magnet 14C is actuated, the mirror will bend
`downward, the degree of which is controlled by the latchable
`magnetization induced in the magnet 14C. If the program-
`mable magnets 14A and 14B are unevenly magnetized at the
`same time 14C is magnetized, the downward mirror move-
`ment will occur with some angle twist, giving rise to a varied
`light-reflecting angle. Thus the mirror can take up many
`different reflecting angles in three dimensions.
`FIG. 3 is a schematic cross-sectional View of a two
`dimensional array of programmable optical switches. An
`array 30 of light-reflecting mirrors 10A, 10B,
`.
`.
`. are
`mounted on a common substrate 12 such as a silicon
`substrate. An array 31A of programmable magnets 14A,
`14B, .
`.
`.
`, at least one magnet for each mirror (and preferably
`three magnets for each mirror if a three-dimensional control
`is desired), are mounted on separate holders 32. The magnets
`can be as small as a fine wire, and the respective solenoids
`can be either wound directly on the magnet wire or pre-madc
`and slipped onto the wire. In a preferred embodiment, two
`such magnet arrays, one as the upper array 31A and the other
`as the lower array 31B (magnets 14A‘, 14B', .
`.
`. ) beneath
`the substrate are pre-assembled, brought close to the sub-
`strate 12, and aligned for ease of device construction.
`Alternatively, utilizing mirror supports 13 having spring
`force for counter-balancing force, only one set of magnet
`arrays, either 31A or 31B, may be used for mirror recon-
`figuration.
`FIG. 4(a) shows a two-dimensional optical cross connect
`40 comprising an array of optical input paths 41A, 41B , .
`.
`.
`,
`an array of output paths 42A, 42B ,
`.
`.
`. and an array of
`programmable, latchable mirrors 10 similar to FIG. 1. Typi-
`cally the inputs and outputs are respective linear arrays and
`the mirrors are disposed in a two—dimensional array. The
`programmable magnets are not shown for simplicity of
`description. The input optical signals from various input
`light sources 41 A, 41B ,
`.
`.
`. such as lasers, fibers, planar
`wave guides, amplifiers, are sent into the optical switching
`cross connect 40, and are reflected by programmable and
`latchable mirrors 10 toward desired output signal lines 42A,
`42B ,
`.
`.
`. Light focusing lenses (not shown) may optionally
`be utilized for improved optical coupling to the receiving
`lines.
`
`FIG. 4b shows an analogous three-dimensional cross
`connect. The arrangement of input and output lines com-
`bined with magnetically programmable mirrors 10 conve-
`niently allows the optical signals to be reflected to any of the
`six faces of a cube-shaped crossconnect system for three-
`dimensional, high—capacity optical routing. The crosscon—
`nect system can be optionally designed to be reversible in
`that
`the direction of the optical signal flow can be the
`opposite of what
`is shown in FIG. 4(b) for additional
`flexibility of light trallic control.
`FIG. 5 schematically illustrates an alternative program-
`mable and latchable optical switch 50. An optical input line
`41 (e.g., fiber, planar waveguide, laser, etc) can be arranged
`in an essentially parallel manner together with output lines
`42A, 42B. Each line is tipped with a focusing lens 51.
`Alternatively, each of the output lines 42A, 42B can be
`positioned at appropriately tilted orientation so as to receive
`the reflected light signal directly in line with the output line
`orientation, with a minimal use of light focusing lenses. The
`magnetic tuning and latching of the mirror 10 allows the
`input beam to be selectively rerouted to one of the output
`lines. The mirror 10 can be an isolated body with a flat
`geometry and can be magnetically tilted, rotated or twisted
`so that the optical signal is reflected to a desired transmission
`line.
`
`10
`
`15
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`6
`Alternatively one can employ a cylinder configuration
`with a flat-end mirror surface positioned at a tilted angle
`with respect to the cylinder axis, with the cylinder magneti-
`cally rotated around its axis so that the reflected beam is
`directed to one of the circularly arranged transmission lines
`around the input line.
`FIG. 6(a) shows a 2x2 optical switch 60 (programmable
`magnets not shown). The switch 60 comprises at least two
`pairs of aligned optical paths, e.g. fibers A and C form one
`aligned pair and fibers B and D,
`the other. The switch
`controls transmission among a plurality of fiber paths A, B,
`C, D. Depending on how the 4 mirrors 10 are magnetically
`arranged,
`the switch may operate as a reflection mode
`optical connection of fiber A to fiber B and fiber D to fiber
`C Alternatively as illustrated in FIG. 6(b), the switch may
`operate as a transmission mode connection of fiber Ato fiber
`C and fiber D to fiber B.
`
`FIG. 7 illustrates an alternative 2>2 optical switch 70
`comprising only one magnetically programmable mirror 10.
`Fiber B and fiber C are positioned slightly off-centered to
`accommodate the mirror thickness for a reflective-mode,
`beam connection of fiber A to B and fiber C to D. This
`displacement also prevents the collision of the two light
`beams when the mirror 10 (dashed sketched) is displaced out
`of the beam paths and the switch is operated in a
`transmission-mode,beam connection. Transmission mode
`provides connection of fiberAto D and fiber C to B. One or
`more light focusing lenses (or mirrors) may be utilized to
`move the beam from the input fiber C toward the output fiber
`B.
`
`It is to be understood that the above-described embodi-
`ments are illustrative of only a few of many possible specific
`embodiments which can represent applications of the inven-
`tion. Numerous and varied other arrangements can be made
`by those skilled in the art without departing from the spirit
`and scope of the invention.
`What is claimed:
`
`1. An optical switching device comprising:
`at least one optical input path;
`at least one optical output path; and
`disposed between said input path and said output path, an
`optical switch comprising a light-reflecting mirror
`including a magnetic component, said mirror movably
`coupled to a substrate, and at least one programmable,
`latchable magnet for interacting with said magnetic
`component to move said mirror between a first position
`reflecting light from said input path to said output path
`and at least a second position reflecting light from said
`input path away from said output path, said program-
`mable magnet maintaining said mirror positions with-
`out continuous power.
`2. The switching device of claim 1 wherein said optical
`input path comprises an optical fiber.
`3. The switching device of claim 1 wherein said at least
`one optical input path comprises a plurality of optical fibers.
`4. The switching device of claim 1 wherein said at least
`one optical input path comprises a plurality of optical fibers.
`5. The switching device of claim 1 wherein said mirror is
`movably coupled to said substrate by a resilient support
`member.
`6. The switching device of claim 1 wherein said second
`position is misaligned with said optical output path to
`attenuate the signal to said output path.
`7. The switching device of claim 1 wherein said at least
`one optical output path comprises a first output path and a
`second output path and said mirror in the said second
`position reflects light from said input path to said second
`output path.
`
`

`

`US 6,256,430 B1
`
`7
`8. An optical crossconnect switching device comprising:
`
`8
`9. The cross connect switching device of claim 8 wherein:
`
`an array 0f optical input paths;
`an array of optical output paths;
`disposed between said input and output path arrays, an
`array of light reflecting mirrors, each mirror including
`a magnetic component and movably mounted on a
`substrate, and,
`for each mirror, one or more
`programmable, latchable magnets for moving said mir-
`ror by interaction with said magnetic component,
`whereby the position of the mirror can be controlled 10
`without continuous power.
`
`5
`
`said array of optical input paths comprises a linear array
`of optical fibers;
`
`said array of optical output paths comprises a linear array
`of optical fibers; and
`
`said array of light reflecting mirrors comprises a two
`.
`.
`.
`.
`dlmensmnal array 0f sald m1rr0rs.
`
`*
`
`*
`
`*
`
`*
`
`*
`
`