Applied Physics

Plasmons on Separate Paths

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Science  29 Jan 2010:
Vol. 327, Issue 5965, pp. 505
DOI: 10.1126/science.327.5965.505-d

In the quest for faster signal processing speeds there are essentially two approaches: shrink the size of the circuitry, or use light rather than electronic current as the information carrier. In the former approach, the operating frequency faces a fundamental upper limit of several tens of GHz due to the properties of the materials required in the design of current-based devices. Light, in contrast, offers the ultimate speed, but requires circuit size to remain on the order of its roughly micrometer-scale wavelength. Surface plasmons—light-induced electronic excitations near the surface of a metal/dielectric interface—offer the possibility of exploiting the speed and size virtues of the two approaches. However, exciting the plasmons is usually a resonant phenomenon, meaning that only one kind of plasmon can be excited at a particular wavelength. Williams et al. present a technique based on a designed array of annular holes on a textured copper surface that allows two tightly bound THz-induced plasmon modes to propagate independently, thus providing potential for a number of applications in chemical and biological sensing, security screening, and communications.

Appl. Phys. Lett. 96, 011101 (2010).

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