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Exclusive Optical To Optical Cross Point Switch Using Semiconductor Laser Logic Gates

IP.com Disclosure Number: IPCOM000121774D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 3 page(s) / 115K

Publishing Venue

IBM

Related People

Chang, CS: AUTHOR [+2]

Abstract

Disclosed is a novel configuration of laser logic devices to create an n x n exclusive cross-point switch which has address control but only requires a small amount of interconnections. This configuration is expandable to large n due to the geometry and the use of monolithic integration. The device could be used for broadcast or exclusive addressing. That is, either one input can be sent to every output, or else no two inputs can be sent to the same output.

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Exclusive Optical To Optical Cross Point Switch Using Semiconductor
Laser Logic Gates

      Disclosed is a novel configuration of laser logic devices
to create an n x n exclusive cross-point switch which has address
control but only requires a small amount of interconnections.  This
configuration is expandable to large n due to the geometry and the
use of monolithic integration. The device could be used for broadcast
or exclusive addressing.  That is, either one input can be sent to
every output, or else no two inputs can be sent to the same output.

      Presently cross-point switches in computing systems perform
both the switching function and routing control electronically.
These switching schemes are limited in the data rates they can route
due to the limited distance-bandwidth of electrical signals.  In
order to increase modulation speeds, optical signals are now being
used for transmission between computers.  A cross-point switch which
can process optical signals is necessary to route these signals.

      Previous work converted an optical signal to an electrical
signal and performed the switching function in electronic circuits
[1].  The electrical signal was then converted to optical for
transmission on the fibers.  This switching scheme uses high-speed
GaAs circuits to achieve switching speeds on the order of 1 GHz and
is reconfigurable on a nanosecond time-scale.  Unfortunately, this
scheme is data rate-dependent due to the decreased bandwidth of the
electronic switching circuits.  If the data rate is increased, new
logic switches which can operate at the higher speed would have to be
incorporated.  This invention describes an optical cross-point switch
which is controlled electronically, configurable on a nanosecond
time-scale, and is data rate- independent due to the high bandwidth
of optical signal transmission.

      This design for an optical cross-point switch uses two separate
types of semiconductor devices.  The first device has one optical
input and either one or two optical outputs in the direction
perpendicular to the inputs.  An example of such devices are the
semiconductor laser logic gates developed by Tang et al [2-4].  These
gates take optical inputs and generate optical output signals which
mimic the input signals in the perpendicular directions provided the
proper control currents are applied.  If the laser logic gate
transmits light in line, it will also transmit light back along the
input waveguide.  For transmission in the perpendicular...