Hanscom Sigma Xi, The Scientific Research Society, Meeting

Tuesday, 8 February 2005

Refreshments: 1:15 - 1:30 P.M., Talk 1:30 - 2:30PM

AFRL/SNH Building 1128 Conference Room,

above parking lot (Steve Mittleman x4038)


Srinivas Sridhar

Vice-Provost for Research

Director, Electronic Materials Research Institute,

Arts and Sciences Distinguished Professor of Physics

Northeastern University, Boston.



In this talk I will give an overview of our nanomaterials program and our experimental and theoretical program exploring negative refraction at microwave frequencies, including focusing by flat lenses. Science cited this as one of the Breakthroughs of 2003.

We have demonstrated negative refraction in metallic and dielectric photonic crystal prisms. Although the trajectories of classical particles or rays is chaotic in these prisms, single beam propagation and negative refraction of waves is observed in certain frequency regimes, and is associated with left-handed electromagnetism. The experimentally observed anomalous wave propagation can be excellently described by band structure approaches and numerical simulations. The experiments demonstrate that tailor-made materials with refractive indices between -0.5 and +1 can be fabricated.

Another remarkable observation is that of focusing by a flat lens. While conventional optical lenses have curved surfaces, negative refraction enables the focusing of a divergent beam by flat surfaces. We have demonstrated the imaging of a microwave point source by a flat lens fabricated from a dielectric photonic crystal. We show that such a lens does not have an optical axis. Negative refraction and left-handed electromagnetism open the door to a variety of new applications from microwave to optical frequencies, such as flat slab lenses and the possibility of the "perfect" or "superlens" enabling imaging with sub-wavelength resolution. See http://sagar.physics.neu.edu (Work supported by National Science Foundation and the Air Force Research Laboratories, Hanscom.)


Srinivas Sridhar, presently Vice Provost for Research at Northeastern University, was appointed Arts and Sciences Distinguished Professor of Physics in 1998. He is the founding director of the university's Nanomedicine Consortium and heads the Electronic Materials Research Institute. His principal areas of research are Nanomaterials and Nanomedicine, Left-Handed Metamaterials and Quantum Chaos.