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Integrated All-Optical Switching of Photonic Streams

IP.com Disclosure Number: IPCOM000116843D
Original Publication Date: 1995-Nov-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 6 page(s) / 159K

Publishing Venue

IBM

Related People

Bona, GL: AUTHOR [+3]

Abstract

Disclosed is an all-optical waveguide switch, as illustrated in Fig. 1, based on carefully engineered gain and absorption. The known switches based on this principle have up to now operated with InGaAsP semiconductor optical amplifiers, using carrier injection via electrodes in the gain sections of the waveguide legs (1). It is herein proposed to provide the gain function via planar waveguide amplifiers such as 'Er' sup + doped SiO sub 2. The key advantages are: 1. The optical routing function is performed all-optically, 2. the optical losses are compensated within the device, or even some gain is provided, allowing the design of essentially loss-less devices. 3.

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Integrated All-Optical Switching of Photonic Streams

      Disclosed is an all-optical waveguide switch, as illustrated in
Fig. 1, based on carefully engineered gain and absorption.  The known
switches based on this principle have up to now operated with InGaAsP
semiconductor optical amplifiers, using carrier injection via
electrodes in the gain sections of the waveguide legs (1).  It is
herein proposed to provide the gain function via planar waveguide
amplifiers such as 'Er' sup + doped SiO sub 2.  The key advantages
are:
  1.  The optical routing function is performed all-optically,
  2.  the optical losses are compensated within the device, or even
       some gain is provided, allowing the design of essentially
       loss-less devices.
  3.  The energy for the switching function is not generated in close
       proximity to the waveguide branches, like with semiconductor
       amplifiers, but a remote pump is used.  This allows a compact
       design of a switch matrix.
  4.  The devices can be realized in a wide variety of materials
       (glassy materials like Silicon-oxy/nitrides, III-V's such as
GaAs
       and InP, polymers), which can be doped with various elements
(Nd
       sup +, Pr sup +,'Er' sup +) to obtain optical gain in
different
       wavelength regions.

      As an example, the case of a SiO sub 2 based waveguide switch,
with 'Er' sup + ions as the gain-elements and pumped by 980nm lasers
is described.  A typical configuration can be an Y-junction shaped
structure, as shown in Fig. 1, with one input port (I) and two output
ports (O1 and O2).  Key elements are the local doping with an
optical-gain medium (such as the fluorescing ions 'Er' sup +, Nd sup
+) at selected areas in the waveguide, marked A1 and A2.  These areas
will act as optical amplification zones.  Two optical waveguide pump
lines 1 and 2 are configured to these amplifier areas in order to
provide optical pump light.  These pump lines can be in different
configurations like dual-ended, co-pumping, or counter-pumping to
accommodate various requirements in power, optical gain,
signal-to-noise
performance and layout.  Furthermore, the advantages of optical
pumping
are:
  1.  The pumping is done from a remotely located source, not
occupying
       real estate near the switch (allows a denser switch matrix);
  2.  The power dissipation in the pumped area is lower than in the
       case of a SOA (semiconductor optical amplifier).

By optical pumping of the appropriate amount of gain elements (e.g.,
'Er' sup + ion density) in the areas A1 and A2, optical amplification
can be provided in that particular output channel.  The waveguides
are designed such that the optical loss in an unpumped leg provides
an output signal below a given decision threshold.

      In case of optical pumping, the resulting optical gain
overcomes these waveguide losses, thus providing...