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Department of Physics

Staff profile

Publication details for Prof Richard Abram

Brand, S, Kaliteevski, MA & Abram, RA (2009). Optical Tamm states above the bulk plasma frequency at a Bragg stack/metal interface. Physical Review B 79(8): 085416

Author(s) from Durham


We demonstrate theoretically that surface-plasmon polaritons, a form of
optical Tamm state, can occur at the interface between a metal and a
Bragg reflector at frequencies above the bulk plasma frequency of the
metal. The frequencies of the excitations are within the photonic band
gap of the Bragg reflector which provides the required evanescent decay
on that side of the interface. At finite in-plane wave vector, the low
value of the permittivity of the metal above its plasma frequency can
lead to an imaginary normal wave vector component in the metal, which
provides the localization on the other side of the interface. It is
proposed that the necessary conditions can be realized using a
GaAs/AlAs Bragg stack coated with a suitable conducting metal oxide
having a bulk plasma frequency of 1 eV, but the concept is valid for
other systems given an appropriate plasma frequency and photonic
band-gap structure. The dispersion relations of the plasmon polaritons
in the structures considered are calculated for both possible
polarizations, and it is shown how the excitations result in distinct
features in the predicted reflectivity spectra.