Theory analysis of the optical mode localized sensing based on coupled ring resonators

Abstract

Based on Mason’s signal flow graph analysis, an analytical model of the optical mode localization based on coupled ring resonators is established. The correctness of the theoretical model is proved by simulation. High sensitivity and common-mode rejection can be achieved by evaluating the modal power ratio from resonant peaks as sensing output. Based on the four-port structure, two output spectrum with mode localization (asymmetric mode splitting) and symmetric mode splitting allows the high-sensitivity sensing and dual-channel calibration to be carried out simultaneously, which can reduce the sensing errors. Monte-Carlo analysis showed that fabrication imperfection changes less than 6% of the performance in 90% cases, thus the construction of practical sensors is possible with appropriate tuning. The optical mode localized sensing has advantages in sensitivity, accuracy, anti-aliasing compared with conventional micro-mechanical mode localized sensor. Various types of high-sensitive sensor can be constructed through coupling parametric perturbation with measurands in different physical domains.