Optical network element for compensating dispersion-related propagation effects

Abstract

A network element (5) for use in a wavelength division multiplex (WDM) optical transmission system (1). The WDM optical transmission system (1) comprises at least one demultiplexing means (5c) adapted to demultiplex a received WDM signal into constituent wavelength channels carrying tributary signals with at least a first and at least a second data rate (DR1, DR2). The optical transmission system (1) further comprises at least one first dispersion compensating module (5e) connected with the demultiplexing means for receiving constituent wavelength channels carrying tributary signals having said first data rate (DR1). Furthermore, the optical transmission system comprises at least one bypass bypassing the first dispersion compensating module and connected with the demultiplexing means for receiving constituent wavelength channels carrying tributary signals having said second data rate (DR2). In this way, dispersion compensation of said first data rate constituent wavelength channels can be significantly improved while avoiding detrimental effects on said second data rate constituent wavelength channels.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram of an optical transmission system in accordance with the present invention;

FIG. 2 is a schematic block diagram of a first embodiment of the network element in accordance with the present invention;

FIG. 3 is a schematic block diagram of a second embodiment of the network element in accordance with the present invention;

FIG. 4 is a detailed block diagram of a third embodiment of the network element in accordance with the present invention;

FIG. 5 is a diagram illustrating the concept of wavelength-shifting constituent wavelength channels with higher bit rate used in an embodiment of the method in accordance with the present invention;

FIG. 6 is a block diagram of a fourth embodiment of the network element in accordance with the present invention having higher connectivity;

FIG. 7 is a diagram for illustrating the evolution of cumulated dispersion along the transmission link in an optical transmission system in accordance with the present invention; and

FIG. 8 is a block diagram of a fifth embodiment of the network element in accordance with the present invention.

Claims

1. A network element for use in a Wavelength Division Multiplex optical transmission system, comprising: at least one demultiplexing means adapted to demultiplex a received wavelength division multiplex signal into constituent wavelength channels carrying tributary signals with at least a first and at least a second data rate,at least one first Dispersion Compensating Module connected with the demultiplexing means for receiving constituent wavelength channels carrying tributary signals having said first data rate,at least one bypass bypassing the first dispersion compensating module and connected with the demultiplexing means for receiving constituent wavelength channels carrying tributary signals having said second data rate.

2. The network element of claim 1, wherein the first dispersion compensating module is at least one of a Gires-Tournois Dispersion Compensating Module, a Virtually Imaged Phased Array, a ring resonator, and a fibre Bragg grating.

3. The network element of claim 1, further comprising at least one multiplexing means for adding tributary signals of said first and/or second data rates.

4. The network element of claim 3, wherein the multiplexing means is connected with said bypass.

5. The network element of claim 1, further comprising a second dispersion compensating module arranged in said bypass.

6. The network element of claim 5, wherein said second dispersion compensating module is a Dispersion Compensating Fibre.

7. The network element of claim 5, further comprising at least one further demultiplexing means for dropping tributary signals of said first and/or second data rates.

8. A Wavelength Division Multiplex optical transmission system, comprising: at least one source of wavelength division multiplex optical signal having constituent wavelength channels which carry tributary signals with at least a first and at least a second data rate,a number of optical fibre spans for propagating said optical signals,at least one node for connecting a number of optical fibre spans, said node comprising the network element of claim 1.

9. The optical transmission system of claim 8, wherein the constituent wavelength channels associated with the first data rate have a first bandwidth and wherein the constituent wavelength channels associated with the second data rate have a second bandwidth different from the first bandwidth, and wherein respective characteristic wavelengths of the constituent wavelength channels associated with the second data rate are shifted relative to a periodic comb of the constituent wavelength channels associated with the first data rate.

10. A method of compensating dispersion-related propagation effects on optical wavelength division multiplex signals, said optical signals having constituent wavelength channels which carry tributary signals with at least a first and at least a second data rate, wherein the optical signals are demultiplexed into their constituent wavelength channels, wherein tributary signals of said first data rate are routed to a dispersion compensating module, in particular a Gires-Tournois Dispersion Compensating Module, while tributary signals of said second data rate are routed to bypass said dispersion compensating module.