Ultra-High-Capacity Optical Communications and Networking: Signal Processing for High-Data-Rate Optical Communications Systems

University Of Maryland Baltimore County, Baltimore MD

Investigators

Abstract

Proposal #0123409 Adali, Tulay U of Maryland-Baltimore County Within the last fifteen years, the maximum data rate that a backbone communications line can handle has grown by five orders of magnitude. A key enabling technology for this impressive growth has been the advent of commercial wavelength-division-multiplexed systems that has allowed systems designers to fill the available bandwidth far more efficiently than in the past. Recently, the physical impairments in the optical fiber transmission lines have become the major factors limiting the obtainable data rates. The chromatic dispersion, fiber nonlinearities, polarization effects, and amplified spontaneous emission noise from the amplifiers, all interact limiting the data rates and/or transmission distances. Polarization mode dispersion (PMD), in particular, introduces intersymbol and intercarrier interference and is the primary limitation in increasing transmission rates and distances in installed terrestrial fiber systems. Though it has been noted that signal processing approaches hold great promise for mitigating PMD and other impairments in optical communications systems, the area is still in its infancy, and the current activity in the area is limited to ``off-the-shelf'' techniques that do not take into account characteristics of the optical domain, thus unable to truly take advantage of the possibilities that signal processing offer. By bringing in expertise from two complementary research areas: signal processing for communications and optical communications, this research develops effective electrical domain (post-detection) approaches for optical communications by taking into account the physical properties of the optical transmission medium. The investigators introduce a new class of receiver structures for optical communications that exploit polarization diversity and study their performance by accurate modeling of the physical phenomena and using efficient simulation techniques that they have developed. The two research groups have expertise in both areas relevant to the proposed work: (1) theoretical and computational study and modeling of optical communication systems and (2) development of error compensation/mitigation techniques for communications. Their collaboration within the last couple of years has demonstrated the potential of solutions developed with this approach for significant performance gains in optical communications systems. An important additional benefit of the project is establishing meaningful communication between the two research communities and the emphasis on the importance of their full collaboration. The research also offers the potential for a more unified view of communications systems.