Rapid Detection of Biological and Chemical Contaminants in Water with Evanescent field Coherent-Surface-Enhanced Raman Spectroscopy

A novel sensor based upon Coherent-Surface-Enhanced Raman scattering (CSERS) is being proposed for rapid detection of biological and chemical contaminants in water. The main characteristic of this sensor is a periodic array of metal nanoparticles deposited on the surface of an optical fiber waveguide. The nanoparticles will be in a periodic array by nanolithography techniques that are currently being evaluated. This single waveguide will transport the exciting laser radiation by the total internal reflection. The evanescent field at the interface (waveguide/water) will interact with biological and chemical contaminant molecules adsorbed onto or near the surface of the metal nanoparticles producing the Raman shifted signal coherently amplified by the propagating coherent surface plasmons. These CSERS signals will be formed in the waveguide and will be directed to an innovative compact spectrometer. An integrated processor will identify contaminant traces in water. The sensor will work as an attached device to a portable/handheld Raman identification system developed by Senspex. This sensor also will convert, using a coupling device, a normal Raman system or Raman probe into a CSERS system.