Tropic Measures Chromatic Dispersion in Metro Optical Networks

Tropic Networks, which specializes in metro regional ROADM systems, announced a new means to measure chromatic dispersion in fiber networks. The new Wavelength Tracker technology enables Tropic to characterize the loss characteristics of each wavelength across an entire network, providing carriers with a chromatic dispersion map of their networks and enabling them to adapt as needed. Chromatic dispersion limits the optical network reach and data rate that the network can support. The issue becomes increasing critical at higher transmission, especially 40 Gbps.



Tropic Networks already offered the capability to uniquely identify wavelengths (including multiple instances of the same ITU grid wavelength) and provide colorless add/drops on its ROADM modules.



"Having the ability to measure and adjust automatically for chromatic dispersion in-service will reduce network costs as the need for wide-range, per-wavelength tunable compensation is eliminated. It will enable the use of lower-cost, pluggable DWDM XFPs on directly-connected client devices that have lower dispersion tolerances. It will allow for automatic network "tuning" as we move to broader optical mesh deployments and to 40G transmission speeds," said Rob Lane, Vice President, Sales and Marketing.



Tropic noted that traditional methods of accurately compensating for chromatic dispersion typically involve measuring every fiber span in a optical network individually using external dispersion measurement equipment, and applying pre-defined bulk dispersion compensation modules at pre-determined points in the optical network. More recently, 40 Gbps transponder suppliers have been developing per-transponder tunable dispersion compensation, which drives up transponder costs.



New software for Tropic's existing hardware measures the difference in the arrival time of wavelengths through the fiber. This enables Tropic to fully characterize the plant for both loss and chromatic dispersion, thereby allowing the use lower-cost transponders at both 10 Gbpss and 40 Gbps.

http://www.tropicnetworks.com