SPR sensor based on a bi-diffractive grating

We report a surface plasmon resonance (SPR) sensor based on two-plasmon-spectroscopy on a special bi-diffractive grating and investigate its ability to distinguish contributions to sensor response due to surface refractive index changes (i.e. binding) and due to refractive index changes in the whole sample. Theoretical analysis yielding an estimate of an error of such decomposition is presented and used to compare performance of this sensor to that of an alternative approach based on simultaneous excitation of short-range and long-range surface plasmons on a thin metallic layer.