Silicon-nanowire-based optical sensor by using Mach-Zehnder interferometer-coupled microring

Mach-Zehnder interferometer-coupled microring is demonstrated for optical sensing for the first time, with a high sensitivity (~111 nm /RIU), a high extinction ratio (>; 26 dB). The MZI-coupled microring sensor still has good performance when the reflective index of the ambient materials largely changes (1 <; n<; 1.538).