Browse Prior Art Database

Micromechanic Shutter Fiber-Optic Switch

IP.com Disclosure Number: IPCOM000111426D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 4 page(s) / 119K

Publishing Venue

IBM

Related People

Stadler, EE: AUTHOR

Abstract

This article describes an opaque shutter, as part of a silicon structure made by micromechanics processes, which is moved in and out of a gap in between two monomode fibers to interrupt and connect the light path. The opaque shutter may be constructed by an anisotropic etched, metallized (110) Si - wafer wall on a SiO[2] cantilever beam over a perpendicular side-wall pit. The cantilever beam's position can be changed by a voltage application between the metallization of the SiO[2] cantilever beam and the heavily doped Boron layer at the bottom of the pit under the cantilever beam.

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Micromechanic Shutter Fiber-Optic Switch

      This article describes an opaque shutter, as part of a silicon
structure made by micromechanics processes, which is moved in and out
of a gap in between two monomode fibers to interrupt and connect the
light path.  The opaque shutter may be constructed by an anisotropic
etched, metallized (110) Si - wafer wall on a SiO[2]  cantilever beam
over a perpendicular side-wall pit.  The cantilever beam's position
can be changed by a voltage application between the metallization of
the SiO[2]  cantilever beam and the heavily doped Boron layer at the
bottom of the pit under the cantilever beam.

      A normally-closed switch (Fig. 1) is constructed by placing the
2 fibers above the cantilever beam surface into channels that are
made by the isotropic etch process.  The normally-open switch is made
by placing the 2 fibers into pits oriented at 90º  to the
cantilever beam pit beneath the cantilever beam surface.  A voltage
connected to the cantilever beam pulls the beam into the pit so that
the light in the fiber above the surface can pass.  This same
condition will block the light, when the fibers are placed below the
surface.  Wire bonds are used to fix the optical fibers.  For
processing the proposed shutter the following process details should
be considered:

o   Basis for micromechanics switch is a (110) wafer, allowing
    perpenticular walls in one direction to process the shutter.

o   A thin top layer is heavily Boron doped.

o   70 &mu.m Si Epitaxy is added.

o   1 &mu.m SiO[2]  is added and personalised for the cantilever beam
    and pit.  The anisotropic etch will be done as last the etch
    step.  The cantilever beam has to be processed as a bridge on
    (110) wafers, the bridge becoming a beam after chip dicing.  The
    switch is made in pairs on the wafer.

o   55 &mu.m SiO[2]  Epitaxy is added.

o   A thin SiO[2]  etch stop to isotropically etch the area for the
    shutter and for the fiber placement channels.

o   A thin SiO[2]  layer is added to isotropicially etch the plateau
    for the fiber channels.

o   A thin SiO[2]  layer is added to isotropically etch the fiber
    channels.

o   A thin SiO[2]  layer is added to anisotropically etch the pit,
    shutter and bridge for the cantilever beam.

o   The cantilever beam and shutter are metallized.

o   The contacts are made for voltage connection and wire bonding to
    fix the optical fibers by wire bonds.

o   The wafer is cut into chips.

o   A chip is fixed in a package.

o   The optical fibers are mounted.

      Fig. 1 shows a cross-section of a nor...