- or why photon echoes are cool
Seminar by
Prof. Kelvin Wagner
Optoelectronic Computing Systems Center
University of Colorado, Boulder
Abstract: The historical highlights of optical signal processing will be briefly reviewed and compared to the dramtic progress but inevitable limitations of electronics. This will motivate our work applying coherent optics and spectral holography in spectral hole burning media to wideband signal processing problems. Spectral hole burning in inhomogeneously-broadened, rare-earth doped crystals cooled to cryogenic temperatures has long held the promise of a vast potential for information storage. This potential is based on the high spectral resolution obtainable across broad, multi-Ghz inhomogeneous bandwidths, yielding millions of spectral channels, while simultaneoulsy exploiting the spatial holographic resolution for massive spatial parallelism.
In this talk, we explore instead the application of these capabilities of spatial-spectral holography to wideband optical processing for applications in RF and LIDAR signal processing. We show how the spectral features that can be burned into the inhomogeneous absorption profile allow the simple implementation of an ultrawideband RF spectrum analyzer. Then we show how the swept frequency readout of the spectral gratings recorded in the inhomogeneous absorption profile as the intereference between a reference waveform and a delayed return allows the implementation of wideband radar and lidar processors.
Finally, we discuss how the spatial domain allows the processing of arrays of signals from RF antenna arrays, or the routing and dispersion compensation of speckled outputs from multimode fibers.
Bio: KELVIN WAGNER is a professor at the University of Colorado in Boulder in the Electrical and Computer Engineering Department. He received the B.S. in Applied Physics from Caltech in 1981 and the M.S. and Ph.D. in Electrical Engineering from Caltech in 1982 and 1987, respectively.
Professor Wagner's research interests include photonic computing architectures, spatial-spectral holography, optical neural networks, optical signal processing, and optical devices and physics for these systems.