Modulating surface plasmons with special optical effects in 2.5 dimensional nanowires and applications
Yi Fan Huang1, Surojit Chattopadhyay1*
1Institute of Biophotonics, National Yang Ming University, Taipei, Taiwan
* presenting author:Surojit Chattopadhyay,
Surface plasmon in gold and silver nanoparticles has been studied extensively for applications in optoelectronics, such as, surface enhanced Raman scattering (SERS), solar cells, bio-sensors and so on. The surface plasmon has been shown to depend predominantly on the dielectric constant (refractive index) of the metal and the embedding media, the particle size, and the free electron density in the metals. Research has hence focused on tailoring these above mentioned properties to alter the surface plasmons. In this presentation we will show how intrinsic optical effects in a supported 2.5 dimensional (2.5D) nanowire could influence the surface plasmons of silver nanoparticles distributed on its surface. Explicitly, we will describe leaky mode resonance (LMR), and optical standing waves (SWs) in the 2.5D nanowires by finite difference time domain (FDTD) calculations and proceed to show how these optical effects can alter the plasmonic scenario of the silver nanoparticles dispersed on the nanowire.1 Next, we will show experimentally, by preparing 2.5D nanowires and dispersing silver nanoparticles on them, that our model is self consistent and that any change in the refractive indices of the support (nanowire) would strongly affect the plasmonic performance of the hybrid (metal-dielectric) nanostructure. Later, we will show how the enhanced surface plasmon field could be utilized in molecular detection using SERS. Through a unique demonstration of plasmonic modulation by intrinsic optical effects in a nanowire we initiate a future oriented direction for sensitive SERS substrate preparation.
Acknowledgements: National Science Council- NSC-101-2112-M-010-003-MY3
1) Yi-Fan Huang et al., NPG Asia Materials 6, e123 (2014).

Keywords: Surface plasmons, Leaky mode resonance, Optical standing waves, SERS, FDTD