Highly sensitive 18 parallel multiplexing of ultra-compact integrated 1D photonic crystal sensor array based on silicon-on-insulator platform

We design a $1\times 8$ highly sensitive ultra-compact on-chip integrated sensor array consisting of a $1\times 8$ power splitter, eight one-dimensional photonic crystal slot nanobeam cavities (1DPC-SNCs) connected by additional 1D photonic crystal tapered nanobeam bandgap filters (1DPC-TNBF), and an $8\times 1$ power combiner. The performance of the device is numerically demonstrated by three-dimensional finite-difference-time-domain (3D-FDTD) method. The whole structure is lying on top of a $2~\mu \text{m}$ buried silicon oxide layer, while remaining high sensitivities (over 400 nm/RIU) of the eight sensors, simultaneously. The proposed 1DPC-SNCs can reach a high-quality factor of $3.6\times 10^{5}$ . On account of the additional band-stop filters and the $8\times 1$ power combiner, eight sensing segments interrogated simultaneously by one input and one output port is realized, with the ultra-compact footprint of $64\times 16\,\,\mu \text{m}^{2}$ ( $26\times 16\,\,\mu \text{m}^{2}$ in sensing region). Therefore, this design is a promising platform for realizing large-scale photonic integrated circuits with high integration density, especially for ultra-compact multiple on-chip sensing.