Silicon photonic guided mode resonance filter for evanescent field molecular sensing

We present experimental and theoretical results of label-free molecular sensing with the TM mode of a 0.22 μm thick silicon slab waveguide used in a guided mode resonance configuration. Due to the strong overlap of the evanescent field of the waveguide mode with a molecular layer attached to the surface, these sensors exhibit high sensitivity, while their fabrication and packaging requirements are minimal. Experimentally, we demonstrate a resonance wavelength shift of ~1 nm when a monolayer of streptavidin is attached to the surface, in good agreement with calculations based on rigorous coupled wave analysis. © 2009 Optical Society of America.