Negative Refraction Without Metamaterials?
| Date/Time: | Thursday, 03 Feb 2011 - Wednesday, 02 Feb 2011 |
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| Location: | PHYSICS 5 |
| Phone: | 515-441-0728 |
| Channel: | College of Liberal Arts and Sciences |
| Actions: | Download iCal/vCal | Email Reminder |
The refractive index, n, of a transparent material usually is found by measuring the angle of refraction and using Snell's law. To date n is always positive in such materials. For opaque materials, e.g., metals, one usually cannot make this measurement due to high absorption. All other methods of measuring the refractive index of a metal require taking a square root and the positive sign is universally chosen. The advent of metamaterials has shown that a negative refractive index, hence angle of refraction, is possible. It has been observed in metamaterials . In this talk I will describe measurements of refraction in the visible region by thin wedge-shaped Cu films that show that in the region dominated by quasi-free electrons (Drude region) the refraction is negative, while in the interband-transition region the refraction is positive. Possible mechanisms for this phenomenon will be discussed, but to date, there is no satisfying explanation.