WO2001029599A1 - 1xn commutateur a fibres optiques a base d'un systeme mecanique microelectrique - Google Patents

1xn commutateur a fibres optiques a base d'un systeme mecanique microelectrique Download PDF

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Publication number
WO2001029599A1
WO2001029599A1 PCT/US2000/028402 US0028402W WO0129599A1 WO 2001029599 A1 WO2001029599 A1 WO 2001029599A1 US 0028402 W US0028402 W US 0028402W WO 0129599 A1 WO0129599 A1 WO 0129599A1
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WO
WIPO (PCT)
Prior art keywords
optical
fiber
mirror
optical signal
switch
Prior art date
Application number
PCT/US2000/028402
Other languages
English (en)
Original Assignee
Laor, Herzel
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Laor, Herzel filed Critical Laor, Herzel
Priority to AU12032/01A priority Critical patent/AU1203201A/en
Publication of WO2001029599A1 publication Critical patent/WO2001029599A1/fr

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Classifications

    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24Coupling light guides
    • G02B6/26Optical coupling means
    • G02B6/35Optical coupling means having switching means
    • G02B6/3564Mechanical details of the actuation mechanism associated with the moving element or mounting mechanism details
    • G02B6/3582Housing means or package or arranging details of the switching elements, e.g. for thermal isolation
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24Coupling light guides
    • G02B6/26Optical coupling means
    • G02B6/35Optical coupling means having switching means
    • G02B6/351Optical coupling means having switching means involving stationary waveguides with moving interposed optical elements
    • G02B6/3512Optical coupling means having switching means involving stationary waveguides with moving interposed optical elements the optical element being reflective, e.g. mirror
    • G02B6/3518Optical coupling means having switching means involving stationary waveguides with moving interposed optical elements the optical element being reflective, e.g. mirror the reflective optical element being an intrinsic part of a MEMS device, i.e. fabricated together with the MEMS device
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24Coupling light guides
    • G02B6/26Optical coupling means
    • G02B6/35Optical coupling means having switching means
    • G02B6/354Switching arrangements, i.e. number of input/output ports and interconnection types
    • G02B6/35442D constellations, i.e. with switching elements and switched beams located in a plane
    • G02B6/35481xN switch, i.e. one input and a selectable single output of N possible outputs

Definitions

  • the present invention relates in general to 1xN optical switches and, in particular, to 1xN switch designs employing dispersive or magnifying optics for reduced optical density at a switch mirror surface.
  • 1xN switches are used in a variety of applications including for example, display devices, communications networks and digital signaling.
  • 1xN switches include switches where an optical signal transmitted from a first fiber can be controllably directed to one or more output ports such as output fibers.
  • such switches include simple on/off switches as well as 1x2 switches, each of which have a broad range of applications.
  • 1xN switches include dual 1xN switches, a species of 2x2N switches where the two input fibers are switched in concert, and other multiples of 1xN switches. Specific implementations of such switches are discussed in more detail below.
  • optical 1xN switches have been implemented by moving the input and/or output fibers to accomplish the switching function or by moving a conventional mirror to selectively direct the optical signal from the input fiber to one or more output fibers.
  • the response time of the switch is limited due to the need to move elements that have significant mass.
  • construction of such switches is difficult due to the precise tolerances required in order to provide for proper alignment of the transmitted optical signal relative to the output fiber(s).
  • the cores of single mode optical fibers typically have a diameter of about 10 microns.
  • MEMS Microelectromechanical Systems
  • MEMS technology involves the use of small mechanical devices fabricated on a Silicon or other substrate together with electronic circuitry for actuating motion of the mechanical device.
  • 1xN switching the use of MEMS technology has been proposed for construction of a moveable mirror for executing the switching function. Because of the small size and mass of MEMS mirror designs, it is anticipated that faster 1xN switches may be achieved.
  • Existing MEMS mirrors range in size from 10 microns to 100 microns.
  • An example of such a MEMS mirror is the Digital Light Processing (DLP) chip manufactured by Texas Instruments, which may include up to one million mirrors. These chips are commonly used in display devices. Electrostatic forces actuate movement of each mirror.
  • DLP Digital Light Processing
  • designs such as Magel's result in a high concentration of optical energy on the mirror, e.g., on the order of 1 megawatt per square centimeter (1 MW/cm 2 ), which may damage the mirror.
  • the Magel design utilizes grazing incidence mirrors. Such mirrors have a reflectance that is dependent on the polarization of the optical signals, which may be problematic in fiber communication equipment.
  • the Magel design involves dimensioning and tolerances that may be difficult to achieve in practical manufacturing environments.
  • the present invention is directed to an optical 1xN switch design where in the input optical signal is controllably dispersed relative to a MEMS mirror utilized to implement the switching function.
  • the optical density of the signal incident on the MEMS mirror can be significantly reduced to accommodate the high power optical signals of modern fiber communication equipment with reduced risk of mirror damage, thereby potentially extending mirror life.
  • the increased signal diameter also relieves the required manufacturing tolerances to provide for more practical designs.
  • focusing optics are used to provide a magnified signal diameter at the MEMS mirror surface. Focusing optics include lenses or the like configured to form a converging output beam; that is, an output beam contained within an optical envelope that progressively narrows as the signal travels away from the optics.
  • An associated optical switch includes an input optical fiber, at least one output port, a MEMS mirror and focusing optics disposed between an end of the input fiber and the MEMS mirror, where the fiber end, focusing optics and MEMS mirror are configured such that the signal as incident on the MEMS mirror is magnified relative to the signal as emitted from the input fiber end.
  • the MEMS mirror is suitably dimensioned to receive the magnified optical signal.
  • magnification reduces the likelihood of mirror damage and facilitates switch construction.
  • unduly enlarging the mirror size can slow the response time of the switch.
  • the optical signal incident on the MEMS mirror is preferably magnified by a factor of between about 2x and 10x and, more preferably, by between about 4x and 6x, relative to the signal diameter at the input fiber end.
  • a magnification of 5x will result in a signal spot diameter of about 50 microns on the MEMS mirror surface for a typical single mode input fiber.
  • all of the signal energy may be received by a mirror having a width or diameter of about 60-70 microns.
  • the 5x magnification reduces the incident optical density by a factor of 25 while allowing for the use of a mirror that can achieve acceptable switching response times for many applications. Such dimensioning also facilitates practical switch manufacturing.
  • substantially collimating optics are used to provide an enlarged signal diameter at the MEMS mirror.
  • Collimating optics include lenses and the like configured such the light emitted from a point source exits the optics such that all rays are directed along substantially parallel paths. That is, the optics are configured and positioned so that the exiting rays are focused substantially at infinity.
  • collimating optics provide an output signal that defines a dispersive optical envelope that enlarges in diameter with increased distance from the optics.
  • collimating optics can be used in conjunction with MEMS mirrors having a width or diameter of about 500 microns to 1 millimeter in accordance with this aspect of the invention.
  • Such designs can achieve certain advantages as discussed above, although perhaps with increased response times relative to particular focused beam implementations.
  • a multiple 1xN switch is implemented using MEMS technology.
  • the switch includes at least a first input fiber associated with a first output fiber and a second input fiber associated with a second output fiber.
  • a MEMS mirror is operative for concerted direction of first and second optical signals from the respective first and second input fibers relative to the first and second output fibers to achieve dual switching functionality. It will be appreciated that more complicated designs involving more than two input fibers can be implemented in accordance with the present invention. Such multiple 1xN designs may be useful in a variety of contexts such as for reducing the required number of mirrors in certain display devices.
  • Fig. 1 is a perceptive view showing a common design of a conventional MEMS mirror
  • Fig. 2 is a cut-away view of a 1x2 switch in accordance with the present invention.
  • Fig. 3 shows one switching position of the switch of Fig. 2;
  • Fig. 4 is a perspective view, partially cut-away, of the switch of Figs.2-
  • Fig. 5a is a bottom view showing the lens plane of the switch of Figs. 2- 4;
  • Fig. 5b is a bottom view showing the lens plane of an alternative embodiment of a 1x2 in accordance with the present invention.
  • Fig. 6 is a bottom view showing the lens plane of a dual 1x2 switch in accordance with the present invention.
  • Fig. 7 shows various perimeters of a magnifying beam configuration in accordance with the present invention.
  • the present invention is directed to MEMS-based 1xN switch designs employing a dispersed or magnified optical beam for reducing the optical density incident on the mirror and simplifying construction by relaxing positioning tolerances. It will be appreciated that such designs can be beneficially used in a variety of 1xN switching contexts. In the following description, the invention is set forth in the context of certain exemplary embodiments relating to on/off and 1x2 switch implementations.
  • Fig. 1 shows a common design for a MEMS mirror system 100.
  • a Silicon chip 102 or other substrate is coated with successive layers of material, typically including metallic and other sacrificial material layers, that are later etched or otherwise configured to leave the mirror 104, hinges 108 and posts 106.
  • the mirror 104 may rotate about the torsion hinges 108 until one side rests on the chip surface.
  • other bi-stable, multi-positionable or analog mirrors may be deflectable without contacting the chip surface so as to avoid stiction concerns.
  • An electrostatic force can be applied to actuate deflection of the mirror 104. The electrostatic actuating mechanism is not shown.
  • the size of the chip 102 is approximately 1 mm x 1 mm.
  • the mirror 104 may be between 10 and 100 microns on a side (the drawing is not to scale).
  • Fig. 2 shows a cut-away of a 1x2 switch 200 built according to the present invention. Fibers a, b and c are each terminated with a lens 202. The lenses 202 focus the respective fiber core on the MEMS mirror 204 to a magnified spot. Thus, the optics 202 effectively provide an enlarged image of the fiber core on the mirror 204. As noted above, it is desirable to magnify the beam to reduce the optical intensity incident on the mirror 204 and simplify construction. However, unduly increasing the mirror dimensions may slow the response time of the switch 200.
  • the optical beam is preferably magnified such that the beam diameter at the mirror 204 is between about 2 times and 10 times as great and, more preferably, between about 4 times and 6 times as great as the diameter of the beam exiting the fiber.
  • the lenses 202 may be common Graded Index (GRIN) lenses as manufactured by Nippon Sheet Glass Company, and bonded to the fiber.
  • the fibers may be laser welded to a lens 202, or otherwise adhesively bonded to the lens 202.
  • the fiber-lens combinations are assembled to the lens carrier by glue, laser welding or soldering. Laser welding or soldering allows for hermetic sealing of the mirror surroundings, extending mirror life and enabling operation in harsh environment.
  • a magnification of the beam by, for example, 5 times enables easy assembly, since the optical spot only needs to be aligned to the center of the mirror 204 within an accuracy of few microns. All three fiber-lens assemblies are aligned to the center of the mirror 204.
  • a 5x magnification also results in a reduction of the Numerical Aperture (N.A.) at the mirror 204, essentially creating a beam angle smaller by factor of five at the mirror 204. This allows for a longer path length between the lenses 202 and the mirror 204, and smaller angles between the lenses 202 as seen from the mirror 204. Smaller angles between the mirror 204 result in less polarization dependent reflection by the mirror 204, as desired for communications applications, because reflection is near the mirror normal.
  • MEMS mirrors provide a bi-stable mirror with the rest position in one of the tilted positions described above or having a mirror that latches to the last tilted position. Such MEMS mirrors may be used to create bi-stable, latching switches or switches that return to a pre-defined connection when electrical control is lost.
  • Fig. 4 is an isometric view of the 1x2 switch 200 of Figs. 2-3.
  • the electrical wiring required to operate the mirror 204 is not shown.
  • Fig. 5 shows the switch 200 as seen from the lenses 202.
  • the position of an axis perpendicular to the mirror surface at its center is shown at its intersection with the plane of the lenses 202.
  • the axis 500 is shown for each of the two switched positions.
  • the offset configuration of the figure 5b may be used.
  • Fig. 6 shows a construction of dual 1x2 switch 600, viewed from the perspective of the lenses 602.
  • Fibers ⁇ a,b,c ⁇ constitute one 1x2 switch and fibers ⁇ d,e,f ⁇ constitute the second 1x2 switch.
  • One mirror with axis positions as shown serves both switches so that switching is accomplished in concert.
  • More complex structures may be assembled involving multiple 1x2 switches serviced by one MEMS mirror. Simpler designs may utilize only 2 fibers for an on-off fiber switch.
  • Fig. 7 illustrates the optical magnification of the lens 700.
  • the lens 700 is drawn as a thin lens, and a thin lens approximation will be used in the following analysis.
  • a ray trace may be performed as will be understood by skilled artisans. The following definitions apply for the formulas set forth below:
  • the N.A. m defines the minimum angular separation of the lenses relative to the mirror, and the minimum angular movement of the mirror. In such designs, the actual mirror is preferably between about 60-70 microns to provide for minimum light loss without unnecessarily increasing the mirror size. In this regard, a mirror of about 65 microns in diameter will reflect 99% of the light.
  • D could be made equal to L. With common existing lenses, D may be between 500 microns and 1 mm. Since the mirror in such a design is reflecting nearly collimated light, a very flat mirror is required. Such mirrors are available, but are much slower to operate compared to the smaller mirrors. These mirrors are usually operated electromechanically due to the large size, requiring larger energy to operate then the smaller mirrors.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Mechanical Light Control Or Optical Switches (AREA)

Abstract

L'invention porte sur un 1xN commutateur à fibres optiques (200) qui est construit à l'aide d'un miroir à système mécanique microélectrique (204) afin de réaliser la commutation. Les extrémités des fibres sont grossies sur le miroir (204) afin de réduire la concentration de la puissance optique au niveau du miroir. Le commutateur (200) a une faible sensibilité par rapport à la polarisation du fait d'une réflexion proche de la perpendiculaire du miroir (204). De plus, le diamètre agrandi du faisceau au niveau de la surface du miroir assouplit les tolérances de fabrication afin d'obtenir un modèle plus pratique.
PCT/US2000/028402 1999-10-15 2000-10-13 1xn commutateur a fibres optiques a base d'un systeme mecanique microelectrique WO2001029599A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU12032/01A AU1203201A (en) 1999-10-15 2000-10-13 Mems based 1xn fiber optics switch

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US15982799P 1999-10-15 1999-10-15
US60/159,827 1999-10-15

Publications (1)

Publication Number Publication Date
WO2001029599A1 true WO2001029599A1 (fr) 2001-04-26

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PCT/US2000/028402 WO2001029599A1 (fr) 1999-10-15 2000-10-13 1xn commutateur a fibres optiques a base d'un systeme mecanique microelectrique
PCT/US2000/028724 WO2001029584A2 (fr) 1999-10-15 2000-10-16 Commutateur a fibres optiques 1xn a systemes mecaniques microelectriques

Family Applications After (1)

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PCT/US2000/028724 WO2001029584A2 (fr) 1999-10-15 2000-10-16 Commutateur a fibres optiques 1xn a systemes mecaniques microelectriques

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WO (2) WO2001029599A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6836585B2 (en) * 2001-08-06 2004-12-28 Fiberyard, Inc. Photonic switch

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106019490A (zh) * 2016-08-01 2016-10-12 中国电子科技集团公司第三十四研究所 一种1×n通道的mems光开关模块

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5841917A (en) * 1997-01-31 1998-11-24 Hewlett-Packard Company Optical cross-connect switch using a pin grid actuator
US5960132A (en) * 1997-09-09 1999-09-28 At&T Corp. Fiber-optic free-space micromachined matrix switches

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5199088A (en) * 1991-12-31 1993-03-30 Texas Instruments Incorporated Fiber optic switch with spatial light modulator device
US6137941A (en) * 1998-09-03 2000-10-24 Lucent Technologies, Inc. Variable optical attenuator

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5841917A (en) * 1997-01-31 1998-11-24 Hewlett-Packard Company Optical cross-connect switch using a pin grid actuator
US5960132A (en) * 1997-09-09 1999-09-28 At&T Corp. Fiber-optic free-space micromachined matrix switches

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6836585B2 (en) * 2001-08-06 2004-12-28 Fiberyard, Inc. Photonic switch

Also Published As

Publication number Publication date
AU1203201A (en) 2001-04-30
WO2001029584A2 (fr) 2001-04-26
WO2001029584A3 (fr) 2001-09-13
AU1210701A (en) 2001-04-30

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