Response characteristic analysis of polarization maintaining fiber ring resonator with dual-coupler for sensing application

A polarization maintaining fiber ring resonator with dual-coupler (PMDC-FRR) for sensing application is presented in this paper. Polarization maintaining directional fiber couplers and fiber loop are employed to eliminate the polarization fading in the fiber ring resonator. Three important characteristic parameters associated with the sensing application, which are the visibility of the output intensities, the free spectral range and the finesse, are discussed as functions of the coupler coefficients and the fiber loop length in detail. In addition, the critical drive voltage of the tunable laser to keep the output intensities stable is also analyzed, when the fiber ring resonator with dual-coupler is utilized as fiber sensor with phase modulation. A PMDC-FRR is designed practically in experiment with the power coupling coefficients of 0.5 and the loop length of 22 m. The experimental results provide sufficient arguments for the theoretical predicts. The theoretical and experimental analysis results will be useful to the sensing application of the PMDC-FRR.

► Response characteristics of PMDC-FRR are investigated in theory and experiment.
► Output intensities correspond to the reflection and transmission intensity of FFPI.
► Effects of the loop length and coupler coefficients on characteristics are analyzed.
► Modulation amplitude must be larger than half value of FSR for steady visibilities.