Special Presentation: S. Chandrasekhar

    Tuesday, October 21, 2014 - 10:00am - 11:00am
    Franken Conference Room (Meinel 821)

    “Terabit Superchannels: Enabling Next-Generation Optical Transmission and Networking”


    Optical fiber transmission technologies with per-channel data rates beyond 100 gigabytes per second and up to one terabyte per second are being actively researched worldwide for next-generation transport systems to meet ever increasing capacity demands. To increase the overall network capacity of wavelength-division multiplexed systems, high spectral efficiency modulation formats in conjunction with advanced digital signal processing,  both at the transmitter and at the receiver with coherent digital reception, are key enablers. In order to achieve net information rates in the 400-gigabyte-per-second to one-terabyte-per-second range, clever synthesis and detection approaches are being pursued. One approach draws its strength from the power of parallel processing. In this approach, multiple optical carriers are modulated individually at relatively lower symbol rates and then combined to result in a multicarrier system delivering the desired net data rate. Net information rates from 400 gigabytes per second to 10 terabytes per second have been demonstrated using multicarrier schemes. This method exploits the benefits of mature technologies at lower speeds and uses optical parallelization in the frequency domain to achieve high aggregate data rates beyond the limits of the electronics. A second approach follows traditional methods, where the modulation rate (or equivalently the symbol rate) of a single carrier has been progressively increased up to 100 gigabaud with both quadrature phase-shift keying and 16-level quadrature amplitude modulation to achieve net information rates in excess of 600 gigabytes per second. This approach relies on ultrahigh-speed analog-to-digital converters with very high sampling rates to achieve the desired performance.

    This talk will review the different solutions that have been experimentally demonstrated, covering a range of approaches that include coherent optical orthogonal frequency division multiplexing, electronic prefiltering (Nyquist-prefiltered) single carrier, and high symbol rate modulation and reception. The talk will also briefly examine optical networking with superchannels in the emerging “flex-grid” re-configurable optical add-drop multiplexer architectures.

    Speaker Bio(s): 

    S. Chandrasekhar received a Ph.D. in physics from the University of Bombay in Bombay, India, in 1985. He joined Bell Labs in 1986. He initially worked on compound semiconductor devices for high-speed optoelectronic integrated circuits and later in WDM optical networking at 40 gigabytes per second and 100 gigabytes per second. His current interests include coherent optical transmission systems for high spectral efficiency transport and networking beyond 100 gigtabytes per second, multicarrier superchannels, and electronic digital signal processing for software-defined transponders. He is a distinguished member of technical staff at Bell Labs, a fellow of the IEEE, a member of the IEEE Photonics Society and a fellow of the Optical Society (OSA). He was awarded the 2000 IEEE Lasers and Electro-Optics Society Engineering Achievement and the 2014 OSA Engineering Excellence Award for his contributions to OEICs and WDM systems research.