Design of side-coupled cascaded photonic crystal sensors array with ultra-high figure of merit

we propose a side-coupled cascaded photonic crystal sensors array (SCCPhCSA) with ultra-high figure of merit (FOM). The design consists of a photonic crystal waveguide (PCW) with changed lattice constants and three cascaded dumbbell-like resonant cavities (DLRCs) are side-coupled to the PCW. The result of finite-different time-domain (FDTD) simulation indicates that each sensing unit of the sensors array possesses a high quality factor (Q) of ~70,000 and high sensitivity up to 260 nm/RIU, resulting in FOM of ~12,000. To our best knowledge, this value is optimized for photonic crystal sensors array by now and it means our design is a promising candidate for large degree of multiplexing sensing.