title: Monolithically integrated mid-infrared lab-on-a-chip using plasmonics and quantum cascade structures.
abstract: The increasing demand of rapid sensing and diagnosis in remote areas requires the development of compact and cost-effective mid-infrared sensing devices. So far, all miniaturization concepts have been demonstrated with discrete optical components. Here we present a monolithically integrated sensor based on mid-infrared absorption spectroscopy. A bi-functional quantum cascade laser/detector is used, where, by changing the applied bias, the device switches between laser and detector operation. The interaction with chemicals in a liquid is resolved via a dielectric-loaded surface plasmon polariton waveguide. The thin dielectric layer enhances the confinement and enables efficient end-fire coupling from and to the laser and detector. The unamplified detector signal shows a slope of 1.8-7 μV per p.p.m., which demonstrates the capability to reach p.p.m. accuracy over a wide range of concentrations (0-60%). Without any hybrid integration or subwavelength patterning, our approach allows a straightforward and cost-saving fabrication.
authors.affiliation: Institute for Solid State Electronics and Center for Micro- and Nanostructures, Vienna University of Technology, Vienna 1040, Austria.
authors.forename: Benedikt
authors.initials: B
authors.lastname: Schwarz
authors.affiliation: Institute for Solid State Electronics and Center for Micro- and Nanostructures, Vienna University of Technology, Vienna 1040, Austria.
authors.forename: Peter
authors.initials: P
authors.lastname: Reininger
authors.affiliation: Institute for Solid State Electronics and Center for Micro- and Nanostructures, Vienna University of Technology, Vienna 1040, Austria.
authors.forename: Daniela
authors.initials: D
authors.lastname: Ristanić
authors.affiliation: Institute for Solid State Electronics and Center for Micro- and Nanostructures, Vienna University of Technology, Vienna 1040, Austria.
authors.forename: Hermann
authors.initials: H
authors.lastname: Detz
authors.affiliation: Institute for Solid State Electronics and Center for Micro- and Nanostructures, Vienna University of Technology, Vienna 1040, Austria.
authors.forename: Aaron Maxwell
authors.initials: AM
authors.lastname: Andrews
authors.affiliation: Institute for Solid State Electronics and Center for Micro- and Nanostructures, Vienna University of Technology, Vienna 1040, Austria.
authors.forename: Werner
authors.initials: W
authors.lastname: Schrenk
authors.affiliation: Institute for Solid State Electronics and Center for Micro- and Nanostructures, Vienna University of Technology, Vienna 1040, Austria.
authors.forename: Gottfried
authors.initials: G
authors.lastname: Strasser
mesh_terms: D004867:Equipment Design; D008027:Light; D008904:Miniaturization; D055096:Optical Devices; D013055:Spectrophotometry, Infrared; D017550:Spectroscopy, Fourier Transform Infrared / Q000295:instrumentation*; D020349:Surface Plasmon Resonance / Q000295:instrumentation*