Novel Design of Photonic Digital Sensors for Distinguishing Uniformly-Distributed Refractive Indices of Fluids

Abstract The authors propose a novel structure of k-level (k is an arbitrary integer) photonic digital sensor based on directional couplers with specific structural parameters. Its function is similar to an analog-to-digital converter (ADC) in electronic system, and capable of distinguishing 2k+1-1 discrete and uniformly-distributed refractive indices of the fluidic samples. In this paper, the principle of designing the photonic digital sensor is described, and the beam propagation method (BPM) simulation results are presented for demonstrating the validity of our design.