Plasmonic analogue of electromagnetically induced transparency at the Drude damping limit

ARTICLES

PUBLISHED ONLINE: 5 JULY 2009 | DOI: http://www.nature.com/doifinder/10.1038/nmat2495

Web End =10.1038/NMAT2495

Plasmonic analogue of electromagnetically induced transparency at the Drude damping limit

Na Liu1, Lutz Langguth1, Thomas Weiss1, Jrgen Kstel2, Michael Fleischhauer2, Tilman Pfau3

and Harald Giessen1*

In atomic physics, the coherent coupling of a broad and a narrow resonance leads to quantum interference and provides the general recipe for electromagnetically induced transparency (EIT). A sharp resonance of nearly perfect transmission can arise within a broad absorption prole. These features show remarkable potential for slow light, novel sensors and low-loss metamaterials. In nanophotonics, plasmonic structures enable large eld strengths within small mode volumes. Therefore, combining EIT with nanoplasmonics would pave the way towards ultracompact sensors with extremely high sensitivity. Here, we experimentally demonstrate a nanoplasmonic analogue of EIT using a stacked optical metamaterial. A dipole antenna with a large radiatively broadened linewidth is coupled to an underlying quadrupole antenna, of which the narrow linewidth is solely limited by the fundamental non-radiative Drude damping. In accordance with EIT theory, we achieve a very narrow transparency window with high modulation depth owing to nearly complete suppression of radiative losses.

Electromagnetically induced transparency (EIT) is a quantum interference effect that reduces light absorption over a narrow spectral region in a coherently driven atomic system13.

Associated with the enhanced transmission is a drastic modification of the dispersive properties of the medium, which enables light to be slowed down substantially47. Recently, a lot of attention has been paid to the fact that EIT-like effects can occur in classical oscillator systems. Examples include coupled microresonators8, electric circuits9, a waveguide side-coupled to resonators10,11 and metallic structures12. In particular, the theoretical prediction of plasmon-induced transparency has been brought forward13. However, so far experimental attempts to realize these theoretical proposals in optical plasmonic systems have not been successful owing to difficulties associated with nanofabrication. Very recently, Fano resonances within an absorption band have been experimentally observed in non-optimized single plasmonic structures at optical frequencies14. The broad linewidth and small modulation depth of those resonances, however, severely hamper applications such as slowing down light, which requires an abrupt change in dispersion over a narrow spectral range, as well as sensing, where a sharp and pronounced spectral response is highly desired15.

Here, we provide the...