Faculty Candidate Seminar

Slow Light in Semiconductors – Give Light a Brake

Pei Cheng (P.C.) Ku

Slow light, as the name implies, “brakes” the optical signal to a velocity that is only a small fraction of what it normally would be. Manipulation of optical signal velocity eliminates the need for unnecessary OEO conversions and enables the key “variable optical buffer” for future optical communications and information processing systems. In the past, slow light could only be achieved in atomic vapor and solid crystals. In this talk, I will present the first experimental demonstration of slow light in semiconductor materials. Using population oscillation in quantum wells, we successfully slowed down the light to about 6 miles per second, which is twice as fast as an orbiting space shuttle. The “slow down factor” in our semiconductor device ranges from 8000-31200 and can be controlled via modulation of the optical intensity from an external laser. This device also exhibits a bandwidth of 2GHz which is over a million times of what was observed in atomic vapors or solid crystals. At the end, I will compare different slow light mechanisms and discuss their fundamental limits in the realization of all-optical information processing.
Pei-Cheng (P.C.) Ku received his PhD from University of California at Berkeley in 2003 in Electrical Engineering and Computer Science. From 2003 to 2004, he was a postdoctoral researcher in the Center for Optoelectronic Nanostructured Semiconductor Technology at Berkeley, where his research focused on slow light and nano-photonic materials. He is currently working on chalcogenide memory with Intel D2 Research at Santa Clara, CA. His research interests include slow light, large scale photonic circuitry, novel electronic and photonic materials. He has authored over 25 journal and conference papers in the area of slow light and optoelectronic materials and physics. Dr. Ku is a recipient of the Berkeley Fellowship (1998-2003) and the Ross Tucker Memorial Award in Electronic Materials (2004).

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