Effects of Reabsorption due to Surface Concentration in Highly Resonant Photonic Crystal Fluorescence Biosensors

Photonic crystal enhanced fluorescence biosensors have been proposed as a novel immunodiagnostic tool, due to the increased fluorescence excitation rates and angular redistribution of the emission. Among these, purely dielectric one-dimensional photonic crystals (1DPC) sustaining Bloch surface waves (BSW) at their truncation edge have recently attracted much interest. We report for the first time on the time-resolved experimental study of the effects of excess reabsorption of the BSW coupled fluorescence in the near-infrared range around 800 nm. Temporally and angularly resolved measurements of the BSW coupled fluorescence emission permit putting into evidence a strong reabsorption of the fluorescence emission when using highly resonant 1DPC. The results suggest that, when designing 1DPC sustaining BSW for quantitative diagnostic assays, it is necessary to choose a compromise quality factor, to exploit the features arising from the electromagnetic field enhancement while avoiding reabsorption.