A polymer-based functional pattern on one-dimensional photonic crystals for photon sorting of fluorescence radiation.

In this work we introduce the use of a patterned polymer-based surface functionalization of a one-dimensional photonic crystal (1DPC) for controlling the emission direction of fluorescent proteins (ptA) via coupling to a set of two Bloch Surface Waves (BSW). Each BSW dispersion branch relates to a micrometric region on the patterned 1DPC, characterized by a well defined chemical characteristic. We report on the enhanced and spatially selective excitation of fluorescent ptA, and on the spatially-resolved detection of polarized emitted radiation coupled to specific BSW modes. As a result, we provide an optical multiplexing technique for the angular separation of fluorescence radiated from micrometric regions having different surface properties, even in the case the emitting labels are spectrally identical. This working principle can be advantageously extended to a multi-step nanometric relief structure for self-referencing biosensing or frequency-multiplexed fluorescence detection.