Effect of the azimuthal orientation on the performance of grating-coupled surface-plasmon resonance biosensors.

The effect of azimuthal orientation on the electromagnetic coupling of surface plasmons with the incident and diffracted light of a grating-coupled surface-plasmon resonance (GC-SPR) biosensor is investigated, and its practical implications are explored. For this purpose a GC-SPR biosensor model is considered, and well-established rigorous coupled-wave analysis is used. Numerical results indicate significant variations in surface-plasmon resonance characteristics in connection with the interaction between surface-plasmon polaritons associated with multiple-order diffraction. The results are discussed as they relate to applications that require minimal rotation sensitivity.