Abstract

We demonstrate surface plasmon resonance (SPR) sensing based on the polarization dependence of extraordinary optical transmission through a biaxial nanohole array. This structure provides the benefit of having two nearly-degenerate periodicities in a single array that can be individually probed by varying polarization. This enables spectral diversity, even when using a single wavelength laser source; for a suitable wavelength, one polarization has increased transmission and the orthogonal polarization has reduced transmission. By monitoring both polarizations, surface-sensitive refractive index induced intensity variations can be separated from other effects, such as absorption, scattering and detected intensity fluctuations. This is particular useful to the on-going microfluidic integration of nanohole SPR, where the light source must be transmitted through the microfluidic channel and it is cost-effective to have an efficient semiconductor laser source and intensity detector.

© 2009 IEEE