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Add-After-Drop Concept with Individual Add and Drop Optimisation

IP.com Disclosure Number: IPCOM000123412D
Original Publication Date: 1998-Nov-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 3 page(s) / 93K

Publishing Venue

IBM

Related People

Horst, F: AUTHOR [+5]

Abstract

The optical add/drop concept in all-optical Wavelength Division Multiplexing (WDM) networks has gained considerable interest in the last few years. In a WDM optical network, data is carried in various (at least 2) wavelength channels that are multiplexed in one fibre. The optical add/drop concept is of high interest because it avoids the need to process all data as would be required in an electronic network. The data stream of interest is simply extracted with a passive optical component which is bit rate and protocol transparent. Transit traffic is optically bypassed. This publication describes a novel design concept of an optical add/drop component.

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Add-After-Drop Concept with Individual Add and Drop Optimisation

   1.  Introduction

   The optical add/drop concept in all-optical Wavelength
Division Multiplexing (WDM) networks has gained considerable
interest in the last few years.  In a WDM optical network, data is
carried in various (at least 2) wavelength channels that are
multiplexed in one fibre.  The optical add/drop concept is of high
interest because it avoids the need to process all data as would be
required in an electronic network.  The data stream of interest is
simply extracted with a passive optical component which is bit rate
and protocol transparent.  Transit traffic is optically bypassed.
This publication describes a novel design concept of an optical
add/drop component.

   2.  The optical add/drop concept

   A conventional add/drop design, as depicted in Fig. 1, has
two input ports.  The main stream input and the add port which
respectively are labelled as 'input' and 'add'.  The two output
ports are for the drop and main stream outgoing traffic which are
labelled 'drop' and 'output'.  A wavelength lambda sub dois dropped
from the wavelength cumb lambda sub l '...' lambda sub N and the
wavelength lambda sub di is added.  Mostly lambda sub di = lambda sub
do will hold.

   A design as shown above is critical in the sense that all
wavelengths that are not fully transferred to the desired port, will
give rise to crosstalk (XT).  This is clear most dramatically in the
add to drop path.  If the add signal is not completely coupled into
the main output stream, the non-coupled power will deteriorate the
drop signal.  If the drop signal is not dropped completely, the rest
of the power will remain in the main stream and find its way in the
system.

   3.  The add-after-drop drop concept

   The issues relat...