Photonic Band Gap Materials: Semiconductors of Light

Abstract

Photonic Band Gap (PBG) materials are artificial, periodic, dielectrics that enable engineering of the most fundamental properties of electromagnetic waves. These properties include the laws of refraction, diffraction, and spontaneous emission of light. Unlike traditional semiconductors that rely on the propagation of electrons through an atomic lattice, PBG materials execute their novel functions through selective trapping or "localization of light" using engineered defects within the dielectric lattice. Unlike traditional wave-guides that confine light in a high refractive index medium using total internal reflection, a PBG micro-chip may consist of air-wave-guides operating using the principle of "light localization" for confinement of light along a low refractive index path. Unlike electronic micro-circuitry, each air-wave-guide path can simultaneously conduct hundreds of wavelength channels of information, throughout a 3D micro-chip. Three dimensional (3D) PBG materials offer a unique opportunity for simultaneously (i) synthesizing micron-scale 3D optical circuits that do not suffer from diffractive losses and (ii) engineering the electromagnetic vacuum density of states in this 3D optical micro-chip. This combined capability opens a new frontier in integrated optics as well as the basic science of radiation-matter interactions. This is of great practical importance for all-optical communications and information processing.

We review recent approaches to micro-fabrication of photonic crystals with a large 3D PBG centered near 1.5 microns. These include self-assembly, glancing angle deposition methods and optical lithography in a polymer photo-resist, followed by replication with silicon. We consider, finally the placement or infiltration of quantum dots within a 3D PBG material for active device applications. The optical micro-chip allows the engineering of very large and abrupt changes in the local electromagnetic density of states as a function of frequency in the vicinity of the quantum dots. This leads to unprecedented frequency selective control of spontaneous emission, novel low threshold nonlinear optical effects, and possibility of
all-optical transistor action.

Speaker Biography

Sajeev John is a University Professor at the University of Toronto and Government of Canada Research Chair holder. He received his Bachelors degree in physics in 1979 from the Massachusetts Institute of Technology and his Ph.D. in physics at Harvard University in 1984. His Ph.D. work at Harvard introduced the theory of classical wave localization in disordered systems and in particular the localization of light in strongly scattering dielectrics. From 1984 ­1986 he was a NSERC postdoctoral fellow at the University of Pennsylvania as well as a laboratory consultant to the Corporate Research Science Laboratories of Exxon Research and Engineering from 1985-1989.

From 1986-1989 he was an assistant professor of physics at Princeton University. While at Princeton, he co-invented (1987) the concept of photonic band gap materials. He was a laboratory consultant to Bell Communications Research (Red Bank, NJ) in 1989. In the fall of 1989 he joined the senior physics faculty at the University of Toronto. He has been a principal investigator for Photonics Research Ontario, a Canadian center of excellence and is an associate member of the Canadian Institute for Advanced Research.

Dr. John received the 1996 Herzberg Medal of the Canadian Association of Physicists, the first ever McLean Fellowship of the University of Toronto in 1996, the 1997 Steacie Prize in Science and Engineering of the National Research Council of Canada, the 2004 Rutherford Medal of the Royal Society, and the first ever Brockhouse Canada Prize in 2004. He has also received the Killam Fellowship of the Canada Council, the Guggenheim Fellowship (USA), the Japan Society for the Promotion of Science Fellowship, and the Humboldt Senior Scientist Award (Germany). He is a Fellow of the American Physical Society, the Optical Society of America, the Royal Society of Canada, and the Max-Planck Society of Germany.

Most significantly, Professor John is the winner of the 2001 King Faisal International Prize in Science, which he shared with C. N. Yang. He is also the first ever winner of Canada's Platinum Medal for Science and Medicine in 2002.