40 Gbps in the Long Haul

All signs indicate that 2006 marked the end of the "bandwidth glut" for Long Haul (LH) and Ultra Long Haul (ULH) DWDM backbone networks. A virtual explosion in IP network traffic has required network operators to upgrade their core router networks to line rates of 40Gbps. A number of large North American operators have announced nationwide upgrades to their IP networks.

These network upgrades require corresponding upgrades to the current 10 Gbps DWDM backbone networks. Thanks to its narrow spectral width and tolerance to chromatic dispersion and optical filter distortion, StrataLight's 40 Gbps signal can be retrofitted into existing 10 Gbps DWDM optical channels, enabling Multi-Haul (simultaneous 10Gbps and 40Gbps on the same fiber) without the need for special 40 Gbps sub-bands. This compatibility with existing fiber types and 10 Gbps transport line systems effectively quadruples the capacity remaining on the original 10 Gbps DWDM span, and significantly delays fiber exhaust and the expenditure involved with lighting incremental fiber.

StrataLight offers both Phase Shaped Binary Transmission (PSBT) and Differential Phase Shift Keying (DPSK) modulation for these demanding applications. For metro, regional and LH networks, PSBT offers a cost-optimized solution with extremely high tolerance to cascaded ROADMs. For ULH and submarine applications with a longer reach requirement, DPSK offers an additional 3 dB of OSNR sensitivity that increases the reach and minimizes the need for regenerators.

At StrataLight, we have developed 40 Gbps line cards with modulation schemes that are performance and cost optimized for Metro through to ULH applications. The figure below illustrates the target applications for the two complementary modulation schemes implemented by StrataLight.

More information can be found under the technical paper and white paper sections of the public web site.