Photonic crystal slab sensor with enhanced surface area

In this work, we demonstrate improved molecular detection sensitivity for silicon slab photonic crystal cavities by introducing multiplehole defects (MHDs), which increase the surface area available for labelfree detection without degrading the quality factor. Compared to photonic crystals with L3 defects, adding MHDs into photonic crystal cavities enabled a 44% increase in detection sensitivity towards small refractive index perturbations due to surface monolayer attachment of a small aminosilane molecule. Also, photonic crystals with MHDs exhibited 18% higher detection sensitivity for bulk refractive index changes.