Condensed Matter Physics Seminar

2 p.m., Thursday, April 10, 2003
Room 1201, Physics Building

 Control of surface plasmons emitted from arrays of subwavelength aperture

Girsh Blumberg


Abstract:  Surface plasmons (SPs) are coherent fluctuations of electron charges on metallic surfaces. These collective charge density waves are characterized by intense mixed transverse and longitudinal electromagnetic fields, strongly localized at the metallic surface. Unlike collective electron oscillations in bulk materials, SPs can couple to propagating photons and therefore be used to trap and nano-focus enormous amounts of electromagnetic energy into very small volumes [1]. Recently, works on extraordinary optical transmission [2, 3] and light beaming [4] in sub-wavelength periodically structured metal films have reached particular prominence, suggesting a direction for fabricating optical devices that operate below the diffraction limit. Significant advances in this area may be possible if SPs can be controllably converted to and from free-space photons, and if their surface propagation can be intentionally directed. In this talk we demonstrate the controlled emission of coherent jets of SPs in a metallic array of subwavelength apertures. We manipulate the SP jet intensity and propagation direction by varying the wavelength, incidence angle, and polarization of the excitation photons. Also we demonstrate conversion of SPs back into light, and observe directional beaming of light from this device.

1. Pendry, J. Playing tricks with light. Science 285, 1687-1688 (1999).
2. Ebbesen, T. W., Lezec, H. J., Ghaemi, H. F., Thio, T. & Wolff, P. A. Extraordinary optical transmission through sub-wavelength hole arrays. Nature 391, 667-669 (1998).
3. Altewischer, E., van Exter, M. P. & Woerdman, J. P. Plasmon-assisted transmission of entangled photons. Nature 418, 304-306 (2002).
4. Lezec, H. J. et al. Beaming Light from a Subwavelength Aperture. Science 297, 820-822 (2002).

Host:  Greene
Back to Condensed Matter Physics Seminar Home Page