Alcatel-Lucent closes OFC with trials to increase capacity and robustness of optical networks

MARCH 30, 2007 -- Alcatel-Lucent (search for Alcatel-Lucent) has announced that it has successfully demonstrated the potential for upgrading existing 40-Gbit/sec transparent long-haul transport networks to 100-Gbit/sec Ethernet; the use of coherent detection instead of conventional direct detection for resistance to fiber impairments at 40 Gbits/sec; the ability to receive and convert serial 107-Gbit/sec optical data into lower-rate data streams; and reportedly the first WDM transmission of channels based on serial binary modulation format exploiting full electronics time-domain division multiplexing (search for ETDM). The optical networking experiments were presented this week in several post-deadline papers by Alcatel-Lucent's Bell Labs (search for Bell Labs) and Research and Innovation teams at OFC/NFOEC 2007 in Anaheim, CA.

In the first experiment, Alcatel-Lucent's Bell Labs researchers in New Jersey successfully transmitted 10 closely spaced 100-Gbit/sec WDM data channels over a 1,200-km optical transmission distance in a systems experiment that included six optical add/drop nodes like those used in today's transparent mesh networks. Using this design, the researchers achieved an "unprecedented" spectral efficiency of 1 bit per second per Hertz (bit/sec/Hz) over the 1,200-km distance using only a single polarization of light. These results, the researchers conclude, demonstrate the practicality of effectively doubling the throughput of today's commercially deployed optical networks, using WDM channel spacings that are typical of existing and deployed 40-Gbit networks using optical and electronic components developed for the 40-Gbit market.

Also demonstrated and presented in a post-deadline paper was a project by researchers at Alcatel-Lucent's Paris-based Research and Innovation center on the use of coherent detection to contain distortion and dispersion, which happen when sending WDM channels at 40 Gbits/sec over links designed for 10 Gbits/sec. The use of coherent detection instead of conventional direct detection makes the introduction of promising techniques easier, such as using polarization division multiplexing on top of WDM, making it possible to generate data at 40 Gbits/sec with just 10-Gbit/sec rate. Based on this approach, the team reports, an ultralong transmission over 4,080 km has been demonstrated for the first time, highlighting "unmatched resistance" to fiber impairments, namely polarization-mode dispersion and chromatic dispersion, when compared to all other 40-Gbit/sec proposed solutions.

In a third post-deadline paper, Bell Labs researchers also demonstrated the ability to receive and convert serial 107-Gbit/sec optical data into lower-rate data streams with the first fully integrated 107-Gbit/sec demultiplexing optical receiver. Alcatel-Lucent says the optical receiver is unique in that it integrates a 100-Gbit/sec photodetector with a 1:2 electronic demultiplexer in a single high-speed package. At such high speeds, packaging these two components in an integrated fashion allows for higher performance compared to having separate photodetector and demultiplexer modules. The company believes this is "a significant step toward the commercial realization of 100-Gbit/sec serial transmission systems," with a compact receiver that transforms ultrahigh-speed optical signals to data rates that are more manageable in the electrical domain.

In a fourth post-deadline paper, Alcatel-Lucent's Research and Innovation researchers from Stuttgart demonstrated the WDM transmission of 10 channels, each carrying 107-Gbit/sec bit-rate information over 480 km. After a recent single-channel demonstration, this is said to be the first WDM transmission of channels based on serial binary modulation format exploiting full electronics time-domain division multiplexing (ETDM), both at the transmitter and receiver sides. It is based on advanced research electronic circuits operating at the full line rate. This approach, complementary to the previous ones, prepares the longer-term introduction of 100-Gbit/sec systems, concludes Alcatel-Lucent.

Visit Alcatel-Lucent