Integration of short gold nanoparticles chain on SOI waveguide toward compact integrated biosensors

We demonstrate the integration of short metal nanoparticle chains (L approximate to 700nm) supporting localized surface plasmons in Silicon On Insulator (SOI) waveguides at telecom wavelengths. Nanoparticles are deposited on the waveguide top and excited through the evanescent field of the TE waveguide modes. Finite difference time domain calculations and waveguide transmission measurements reveal that almost all the TE mode energy can be transferred to nanoparticle chains at resonance. It is also shown that the transmission spectrum is very sensitive to the molecular environment of nanoparticles, thus opening the way towards ultra-compact sensors in guided plasmonics on SOI. An experimental demonstration is reported with octadecanthiol molecules for a detection volume as small as 0.26 attoliter. (C) 2010 Optical Society of America