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This page contains a single entry from the blog posted on September 10, 2008 2:48 PM.

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Seminar: Wednesday, September 10, 2008 at 3:30pm

Linearized Electrooptic Phase Modulation for Microwave-Photonic Signal Transmission
Dr. Tom Murphy
Department of Electrical and Computer Engineering
University of Maryland College Park

Anyone who travels has likely heard the following warning: “FAA regulations prohibit the use of portable electronic devices during takeoff or landing.” The modern aircraft contains an ever-growing array of electronic sensors used in navigation and communication. At the same, time, we have seen a rapid explosion not only in the number of handheld electronic appliances carried by passengers, but also in their frequencies of operation. This has lead to growing concern that electromagnetic radiation from such devices could interfere with navigation and communication.

One potential solution to this problem is to replace the coaxial cables and wires normally used to transmit electronic signals in the aircraft with optical fibers. Compared to coaxial cables, optical fibers are smaller, lighter, and less expensive. The bandwidth available in a single fiber is large enough to accommodate the data from thousands of coaxial cables, and the loss in optical fiber is negligible in comparison to coaxial cables, especially at microwave frequencies. Most importantly, optical fibers are completely immune to electromagnetic interference, which makes them especially attractive for avionic sensor networks. The key challenge is to find a ways to modulate and demodulate analog microwave signals onto an optical carrier without distorting or impairing the microwave signal.

In this talk, I will discuss our recent research on using phase modulation instead of more commonly-used intensity modulation to impose a microwave signal on an optical carrier. To date, there has been very little research on developing low-distortion linearized phase-modulation systems. Unlike earlier intensity-modulation schemes, which often required multiple interconnected modulators or signal pre-distortion, our system is unique in that it uses only a single electrooptic phase modulator driven by an unmodified input signal, and could entirely eliminate the third-order intermodulation distortion that usually limits the dynamic range.

Location: Physics Bldg., Room 401
Coffee: 3:15 p.m.

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