Tropic touts CD measurement capabilities

JANUARY 29, 2007 � ROADM supplier Tropic Networks (search for Tropic Networks) claims that a combination of three technologies enables them to measure chromatic dispersion in fiber networks in addition to identifying wavelengths and measuring and adapting to fiber loss.

Tropic Networks says the three technologies are Wavelength Tracker tagging and decoding technology; full C-band tunable transponders; and a colorless add/drop capability on its WSS ROADM modules.

Chromatic dispersion limits the optical network reach and data rate that the network can support. Therefore, determining and compensating for chromatic dispersion is a critical step in the building of geographically large and high data rate optical networks, says the company.

"This breakthrough is significant in so many ways" said Rob Lane, vice president, sales and marketing. "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. Our customers will experience faster network and service provisioning times, resulting in faster time to revenue and a drop in network costs and spares inventory".

"Traditional methods of accurately compensating for chromatic dispersion typically involve measuring every fiber span in an optical network individually using external dispersion measurement equipment, and applying pre-defined bulk dispersion compensation modules at pre-determined points in the optical network. This makes the existing methods of measuring and compensating for chromatic dispersion expensive, inefficient, intrusive, and labor intensive" said Ben Bacque, vice president, research and development. "More recently, 40-Gbit/sec transponder suppliers have been developing per-transponder tunable dispersion compensation, which drives up transponder costs. This new Wavelength Tracker capability is unique, in that it will allow us to use lower-cost transponders at both 10 Gbits/sec and 40 Gbits/sec. It is the next step in the evolution of our Wavelength Tracker technology. We have moved the application from its first use as a simple passive wavelength monitoring function, to its use in our closed-loop automated loss adaptation and power control functions, and now we are able to fully characterize the plant for both loss and chromatic dispersion, all using the same Wavelength Tracker hardware that is already in-service. This new capability will be implemented in an upcoming software release based on existing, proven and deployed hardware."

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