Miniature interrogator for multiplexed FBG strain sensors based on a thermally tunable microring resonator array

We present a high-resolution and miniature multi-wavelength Fiber Bragg Grating (FBG) interrogator based on a thermally tunable microring resonator (MRR) array. A phase detection method using dithering signals is exploited to generate an antisymmetric error signal curve, which is utilized for the feedback locking of the MRR with the FBG sensor. Dynamic strain sensing of both single FBG and multiple FBGs are experimentally demonstrated, with a dynamic strain resolution of 30 nε/√Hz over 100 Hz to 1 kHz. The proposed interrogator shows the great improvements in both resolution and wavelength accuracy compared with the reported MRR-based interrogators and is promising for scalable multiplexed sensing applications.