λ³/1000 plasmonic nanocavities for biosensing fabricated by soft UV nanoimprint lithography.

Cattoni, Andrea; Ghenuche, Petru; Haghiri-Gosnet, Anne-Marie; Decanini, Dominique; Chen, Jing; Pelouard, Jean-Luc; Collin, Stéphane · Nano Lett · 2011

basic_science · Level V

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Abstract

Arrays of plasmonic nanocavities with very low volumes, down to λ(3)/1000, have been fabricated by soft UV nanoimprint lithography. Nearly perfect omnidirectional absorption (3-70°) is demonstrated for the fundamental mode of the cavity (λ ≃ 1.15 μm). The second-order mode exhibits a sharper resonance with strong angular dependence and total optical absorption when the critical coupling condition is fulfilled (45-50°, λ ≃ 750 nm). It leads to high refractive index sensitivity (405 nm/RIU) and figure of merit (∼21) and offers new perspectives for efficient biosensing experiments in ultralow volumes.

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