Remote sensing by plasmonic transport

Arrays of periodically disposed silver nanowires embedded in alumina were shown to be capable of conducting plasmons excited by laser illuminating one end of the array to its opposite end where surface-enhanced Raman of molecules resident among the tips of the nanowires was excited. The SERS signals, in turn, excited plasmons which propagated back to the originally illuminated ends of the nanowires where they emitted light signals that were collected and spectroscopically dispersed, in essence creating a sensor capable of exciting and collecting SERS remotely. For nanowire arrays with interwire gaps of ~11 nm and lengths of ~3.3 μm (i.e., after a ~6.6 μm round trip) the SERS signals obtained by remote sensing were rather strong, ~5% the intensity of those obtained by exciting the molecules resident among the nanowire tips directly.