Differentiation between changes in liquid refractive index and surface adsorbed molecular thickness using SOI wire waveguide ring resonator biosensor arrays

For silicon wire based ring resonator biosensors, we investigate the simultaneous retrieval of changes in the cladding-liquid refractive index and adsorbed molecular-film thickness by monitoring the resonance shifts of sensors operating in the TE and TM polarizations, respectively. Taking into account typical core-size variations in silicon photonic wires, the retrieval inaccuracies of less than 15% are obtained for both the liquid index and molecular thickness. © 2012 OSA.