On the performance of label-free biosensors based on vertical one-dimensional photonic crystal resonant cavities.

In this work three Fabry-Perot (FP) resonant cavities based on vertical silicon/air one-dimensional photonic crystals (1DPhCs) featuring different architectures and fluidic functionalities are designed, and the role of key design parameters on their ideal biosensing performance, i.e. surface sensitivity, limit of detection, range of linearity, is investigated. Numerical calculations of the transmission spectra of the 1DPhC FP resonant cavities using the Transfer Matrix Method (TMM), versus thickness of a biolayer simulating biomolecules (e.g. proteins) adsorbed on the 1DPhC FP cavity surfaces, show that biosensors with surface sensitivity up to 300 pm/nm, limit of detection down to 0.07 nm, and high linearity over the range 0-50 nm of biolayer thickness can be achieved.