Regensburg 2013 – scientific programme

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O: Fachverband Oberflächenphysik

O 7: Plasmonics and Nanooptics I

O 7.8: Talk

Monday, March 11, 2013, 12:15–12:30, H31

Using low-loss phase-change materials for IR antenna resonance tuning — •Ann-Katrin U. Michel, Tobias W. W. Maß, and Thomas Taubner — 1st Institute of Physics, RWTH Aachen University, Sommerfeldstraße 14, 52074 Aachen, Germany

Metallic nanoantennas are able to produce significantly enhanced and highly confined electromagnetic fields. The variation of nanorod material, geometry and substrate allows a wide tuning range of their resonance frequency.

We show a concept for resonance tuning of aluminum nanorods with defined geometry via variation of the refractive index n of an embedding medium. Phase-change materials (PCM) offer a huge contrast in n due to a phase transition from amorphous to crystalline state, which can be thermally triggered. Due to a negligible small imaginary part of the dielectric function of both phases, in the mid-IR resonance damping is avoided. Exemplary we used the two PCM InSb and Ge₃Sb₂Te₆ [1],which provide a huge contrast in n and a negligible small losses in the mid-IR spectral range. We present resonance tuning to lower as well as to higher wavenumbers with a maximum shift of about 11.5%, which is confirmed via FDTD simulations.

Since nanoantennas represent a model system for metamaterials, our study enable a variety of new applications for sensing, enhanced IR spectroscopy [2] and programmable optical nanostructures [3].

[1] Sittner et al. Phys. Status Solidi A 2012.

[2] Adato et al. PNAS 2009 106(46), 19227-19232.

[3] Xingjie Ni et al. Science 2012 335, 427.