Optical metamaterials: from superlensing to negative refraction

Date: 
Monday, April 23, 2007 (All day)
Speaker: 
Dr. Gennady Shvets
Speaker's Institution: 
University of Texas at Austin

The wavelength of light places a natural limit on the resolution of an optical system. Overcoming this limit and constructing a “super-lens” is one of the main motivations of the recently emerged area of Negative Index Meta-materials (NIMs) with negative dielectric permittivity e and magnetic permeability m While several designs of optical NIMs based on antenna-type resonances have been recently put forward, the key challenge remains: how to miniaturize a unit cell of a NIM to be much smaller than the wavelength. A new approach to miniaturizing NIMs based on resonant plasmonic nanostructures and the corresponding super-lens will be described.  Even when m > 0, near-field super-lensing is possible with e < 0 materials. Experimental demonstration of a near-field super-lens in the mid-infrared (around 11 microns) range will be described. The lens is implemented using crystalline SiC films that have remarkable infrared properties: they support surface polaritons with less damping than most metals. Two demonstrations of super-lensing with  l/20 spatial resolution will be demonstrated: (a) using FTIR microscopy, and (b) by direct near-field probing with NSOM. Both amplitude and phase-sensitive imaging is demonstrated. It is also demonstrated that super-lensing can be used for deep sub-surface imaging.  We will also describe our recent experimental and theoretical work on extraordinary optical transmission and absorption through subwavelength hole array in mid-IR and describe possible applications to developing highly efficient sources of tunable thermal radiation.