ITTC Project

PMD Characterization on an Active Fiber Link

Project Award Date: 05-01-1999


The purposes of this research are to learn more about the dynamics of adaptive PMD compensation, and to validate the principles and effectiveness of a PMD compensation approach developed recently by the researchers at ITTC.

Polarization-mode dispersion (PMD) may be a dominant barrier to expanding the throughput of an optical fiber link by increasing the per-channel data rate. As PMD is a time-varying, random process, characterization of the link's PMD requires continuous observation over long time periods. Current commercially available PMD measurement techniques require that the fiber under test be taken out of servicemaking PMD characterization on a link within an active network expensive! A technique developed recently at KU involves the direct estimation of the link's PMD componentsi.e., the differential group delay (DGD) and the principal states of polarization (PSPs). Estimates of these parameters are derived directly from the signal, so the fiber may remain in service and no additional signals are introduced on the fiber.

The first step in this research is development of dedicated hardware to implement our first-order PMD adaptive compensation system. We will refine our original design and build an adaptive PMD compensation system that can estimate and track the DGD and PSPs within seconds, using dedicated RF and digital signal processing to reduce the time constant in the feedback loop.

The next step is long-term operation of this system on the KU-TIOC WDM link to collect data on DGD and PSP variations over time. The data collected from this link will be analyzed to identify trends and patterns that may provide insight into the factors that are driving the PMD fluctuations. For example, other researchers have asserted that the PMD characteristics change most dramatically during sunrise/sunset events.

Data collected on this project will provide critical (but currently unavailable) information on the variability of DGD and PSP. These data are essential not only for gaining a better understanding of PMD (what factors influence it, how fast does it fluctuate, when does it change the fastest, etc.), but also for enhancing the design of efficient adaptive compensation systems. To our knowledge, the analysis technique developed in conjunction with our PMD compensation scheme is the only approach to obtain such data.


Faculty Investigator(s): Christopher Allen (PI), Kenneth Demarest, Rongqing Hui

Student Investigator(s): Pradeep Kondamuri, Arun Prasad Chimata, Ashvini Ganesh

Project Sponsors

Primary Sponsor(s): Sprint

Partner with ITTC

The Information and Telecommunication Technology Center at the University of Kansas has developed several assistance policies that enhance interactions between the Center and local, Kansas, or national companies. 

ITTC assistance includes initial free consulting (normally one to five hours). If additional support is needed, ITTC will offer one of the following approaches: 

Sponsored Research Agreement

Individuals and organizations can enter into agreements with KUCR/ITTC and provide funds for sponsored research to be performed at ITTC with the assistance of faculty, staff and students.

Licensing and Royalty/Equity Agreement

An ITTC goal is the development of investment-grade technologies for transfer to, and marketing by, local, Kansas, and national businesses. To enhance this process, the Center has developed flexible policies that allow for licensing, royalty, and equity arrangements to meet both the needs of ITTC and the company.

Commercialization Development

Companies with a technology need that can be satisfied with ITTC's resources can look to us for assistance. We can develop a relationship with interested partners that will provide for the development of a technology suited for commercialization.

ITTC Resource Access

ITTC resources, including computers and software systems, may be made available to Kansas companies in accordance with the Center's mission and applicable Regents and University policies.

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