Waveguide-Enhanced Surface Plasmons for Ultrasensitive SERS Detection

Abstract

We design an ultrasensitive surface-enhanced Raman scattering (SERS) substrate based on waveguide-enhanced surface plasmons (SPs). An optical waveguide was exploited to concentrate and restrict the electromagnetic (EM) energy of the incident light, and Ag nanoparticles that were assembled on the waveguide surface were used to enhance the EM field further by means of SP resonance. The enhancement factor (EF) of the incident EM field can reach 103 on the two sides of nanoparticles, and a 108–1012 EF of SERS is expected. This waveguide-assisted isolated nanoparticle substrate can reach a comparable SERS enhancement capability to that of gap-type SERS hot spots. In addition, this SERS substrate is applicable to the SERS detection of large molecules (biomacromolecules etc.), which cannot be placed in traditional gap-type hot spots.