Dresden 2003 – scientific programme
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HL: Halbleiterphysik
HL 28: Photonische Kristalle
HL 28.2: Talk
Tuesday, March 25, 2003, 18:00–18:15, POT/81
Radiative decay and dephasing in plasmonic bandgap structures — •V. Malyarchuk1, C. Lienau1, D. J. Park2, Y. C. Yoon2 und D. S. Kim2 — 1Max-Born-Institut, Berlin, Germany — 2Seoul National University, Seoul, Korea
Plasmonic bandgap structures have been of much interest lately since enhanced light transmission has been discovered. Transmission spectra of periodic nanohole arrays in metal films show strong resonances corresponding to SP excitations on either side of the metal film. So far, the microscopic origin of the linewidth of these peaks has not yet been clarified. In this contribution, we study the coherence length of surface plasmons directly in the spatial domain, with sub-100 nm resolution. SP are resonantly excited at the metal-air interface of a first nano-hole array. This mode propagates over a flat metal surface until it encounters a second nanohole array. Its decay inside the array is probed by near-field microscopy [1] and is a direct measure of the SP coherence length Lc inside the array. At wavelengths of about 800 nm, Lc is about 1.5 µm. This short coherence length is consistent with SP polarization decay times of about 10 fs, measured in fs transmission experiments. It translates into a 100 meV linewidth of the transmission spectra, as observed experimentally. From the wavelength and hole size dependence of the dephasing time we deduce that a Rayleigh-like scattering of SP eigenmodes of the bandgap structure by the periodic array hole array is the microscopic origin of the SP damping and of the linewidths of the transmission peaks.
[1] S. C. Hohng et al., Appl. Phys. Lett. 81, 3239 (2002)