Negative Index of Refraction Betsey Mathew

Mathematically What is n?

Permittivity Describes how affects the material electrically  can be… –Positive (dielectric) –Negative (metal)

Permeability Describes how affects the material magnetically  can be… –Positive (ferromagnet) –Negative? (we’ll look more at this later)

Mathematically What makes a negative n? So if  and  are both negative then  r and  r are negative as well

What is a NIM/LHM? NIM: Negative Index of refraction Material –Any material that has a –n –Must have –ε and –μ LHM: Left Handed Material

Veselago Russian Physicist First theorized about NIMs in 1968 Thought that NIMs would exhibit left- handed tendencies Thought that they would follow Snell’s law These theories couldn’t be tested…no –μ materials existed

Split-Ring Resonators Pendry’s Cylinder –Uses Faraday’s law to induce current –Capacitance keeps current flowing – –Found H ave and B ave

Split-Ring Resonators

Experiment 1 Design

Experiment 1 Results

Experiment 2 Design

Experiment 2 Results Snell’s law holds –For n t <0, θ t <0

Experiment 2 Conclusions NIM n i Air n t θtθt θiθi

Experiment 3 Design

Experiment 3 Results We indeed see Snell’s law in action The numerical predictions match the data—we understand what’s going on!

Experiment 3 Results

Experiment 3 Conclusions Snell’s law does indeed hold in NIMs The value of n follows predicted curves

Overall Discoveries About LHMs Since 1999 SRRs can be used to create –μ eff SRRs can have varying values of –μ eff depending on frequency When combined with wires, SRRs form LHMs These LHMs can be treated as a homogenous isotropic material Snell’s Law holds for these LHMs

Possible Applications Pendry perfect lens Antennas Imaging with super-resolution Microwave devices Dispersion-compensating interconnects Radar

Current Obstacles Resonance frequencies for –μ eff in SRRs are very high (GHz and THz) There are huge power losses that as yet cannot be overcome

Sources Shelby, R. A., D. R. Smith, S. Schultz. “Experimental Verification of a Negative Index of Refraction” Science Vol. 292 April 2001 Parazzoli, C. G., R. B. Greegor, K. Li, B. E. C. Koltenbah, and M. Tanielian. “Experimental Verification and Simulation of Negative Index of Refraction using Snell’s Law” Physical Review Letters Vol. 90, No. 10. March 2003 Smith, D. R., Willie J. Padilla, D. C. Vier, S. C. Nemat-Nasser, and S. Schultz. “Composite Medium with Simultaneously Negative Permeability and Permittivity” Physical Review Letters Vol. 84, No. 18. May 2000 Pendry, J. B., A. J. Holden, D. J. Robbins and W. J. Stewart. “Magnetism from conductors and enhanced nonlinear phenomena” IEEE Transactions on Microwave Theory and Techniques, Vol. 47, No. 11. November 1999 Hecht, Eugene. Optics, Fourth Ed. Addison Wesley, Griffiths, David J. Introduction to Electrodynamics. Prentice Hall, 1999

The End