Date and Time Thur, Nov 20, 2014, 3:00 PM - 4:00 PM
Location SF B560
Host Xiao Sun

Dynamical Evolution of Information and Energy in Causal Dispersive Media

Ahmed Dorrah

Mojahedi Group, EM



Energy exchange between an electromagnetic pulse and dispersive media may result in complicated, yet interesting, phenomena in which the group velocity becomes abnormal (i.e. superluminal or negative). For such cases, signal velocity (velocity of detectable information) becomes debatable. In this talk, a systematic study is presented to quantify the detectable information content and calculate its speed in any dispersive medium while accounting for pulse reshaping effects and the noise generated in the medium and the detector system. Such analysis explores the fundamental limitations and capabilities of signaling in a broad range of fast (and slow light) systems.

Reference: Ahmed H. Dorrah, and Mo Mojahedi, “Velocity of detectable information in faster-than-light pulses,” Physical Review A, Vol. 90, 033822, 2014. [DOI:].


Ahmed graduated from the department of Electrical and Computer Engineering at Cairo University in June 2011. He then worked as a system design engineer in Newport Media Inc. (now part of Atmel corporation) before joining the Photonics group at UofT in September 2012. Since then, Ahmed has been working towards his M.A.Sc. degree under the supervision of Prof. Mo Mojahedi; where his research interests include: mapping the evolution of energy and information in causal dispersive media, with emphasis on utilizing superluminal effects to reduce signal detection latency in optical interconnects.​