Optimal Time-Domain Mixer

George C. Valley
The Aerospace Corporation

Thursday, November 4, 2010 at 3:00pm
Engr IV Maxwell Room 57-124

Abstract

We present results on an optical time-domain mixer that can be used to make a photonic analog-to-digital converter (ADC) or a digital demodulator for high-speed optical communications signals. In the basic mixer, a high frequency RF signal modulates a repetitively chirped optical carrier; this RF/optical waveform then is dispersed in one transverse dimension, and imaged onto a 2-dimensional transparency or spatial light modulator whose pixels are modulated with randomly chosen transmission or reflection coefficients (the optical mixing matrix). Following transmission through or reflection from the mixing matrix, the optical waveform from each row of the matrix is recombined and directed to a photodiode and electronics that integrate over the repetition period of the chirped source. Finally, each of these signals is digitized by an independent ADC sampling at a rate equal to the pulse repetition rate of the chirp source. A digital replica of the input RF signal can be recovered by digital signal processing from the digital output of the ADCs and the values of the transmission or reflection coefficients of the mixing matrix. The effective sampling rate is given by the number of pixels per row of the mixing matrix times the repetition rate of the chirp source while the effective resolution is controlled by the resolution of the electronic ADCs and the distortions introduced by the optical mixing process.

Biography

Pablo A. Parrilo received an Electronics Engineering undergraduate degree from the University of Buenos Aires, and a Ph.D. in Control and Dynamical Systems from the California Institute of Technology. He has held short-term visiting appointments at the University of California at Santa Barbara (Physics), Lund Institute of Technology (Automatic Control), and UC Berkeley (Mathematics). From October 2001 through September 2004, he was Assistant Professor of Analysis and Control Systems at the Automatic Control Laboratory of the Swiss Federal Institute of Technology (ETH Zurich). He is currently Professor of Electrical Engineering and Computer Science at the Massachusetts Institute of Technology, where he is also affiliated with the Laboratory for Information and Decision Systems (LIDS) and the Operations Research Center (ORC).

George C. Valley has an AB (1966) in physics from Dartmouth College and a PhD (1971) in physics from The University of Chicago. He worked at Cornell Aeronautical Laboratories (1972-1977) and Hughes Aircraft Company (1977-1999) and is now Senior Scientist at The Aerospace Corp (1999-present). He is a member of the American Physical Society and a Fellow of the Optical Society of America. Past research work has focused on nonlinear optics, optical solitons, photorefractive materials, free-space laser communication and wave propagation in random media. Current research interests include simulation of mixed signal integrated circuits, photonic analog-to-digital converters and applications of compressive sensing. He is author or co-author of over 100 publications and 15 patents.