title: All-semiconductor plasmonic gratings for biosensing applications in the mid-infrared spectral range.
abstract: We propose 1D periodic, highly doped InAsSb gratings on GaSb substrates as biosensing platforms applicable for surface plasmon resonance and surface enhanced infrared absorption spectroscopies. Based on finite-difference time-domain simulations, the electric field enhancement and the sensitivity on refractive index variations are investigated for different grating geometries. The proposed, optimized system achieves sensitivities of 900 nm RIU-1. A clear red shift of the plasmon resonance as well as the enhancement of an absorption line are presented for 2 nm thin adlayers in simulations. We experimentally confirm the high sensitivity of the InAsSb grating by measurements of the wavelength shift induced by a 200 nm thin polymethylmethacrylate layer and demonstrate an enhancement of vibrational signals. A comparison to a gold grating with equivalent optical properties in the mid-infrared is performed. Our simulations and experimental results underline the interest in the alternative plasmonic material InAsSb for highly sensitive biosensors for the mid-infrared spectral range.
authors.forename: Franziska B
authors.initials: FB
authors.lastname: Barho
authors.forename: Fernando
authors.initials: F
authors.lastname: Gonzalez-Posada
authors.forename: Maria-José
authors.initials: MJ
authors.lastname: Milla-Rodrigo
authors.forename: Mario
authors.initials: M
authors.lastname: Bomers
authors.forename: Laurent
authors.initials: L
authors.lastname: Cerutti
authors.forename: Thierry
authors.initials: T
authors.lastname: Taliercio