Generating Loss Dependent Bifid Dips of Optical Carrier Based Microwave With Self-Feedback Anti-Symmetric Coupled Fiber Ring Resonator

A self-feedback anti-symmetric coupled fiber ring resonator (SACFRR) is proposed and demonstrated to generate the distinctive loss dependent bifid dips. The universal derivation of the ring resonators in both lightwave and optical carrier based microwave domains considering different conditions including attenuation, coupling and self-feedback is systematically elaborated, which is applicable to diverse ring resonator configurations. The lightwave and optical carrier based microwave experience different phase evolution during the cross-coupling procedure, thereby causing very different output. The anti-symmetric coupling strategy is creatively introduced into the ring resonator, which dominates the splitting of the original resonance dip for the optical carrier based microwave interferometry (OCMI). And OCMI shows the noticeable bifid dips within the lower envelope which receives less attention before. By performing the measurement of temperature and bend-induced loss, the bifid dips based demodulation of OCMI is employed to present the property of SACFRR and compared with the conventional upper envelope based demodulation, contributing to the utilization of lower envelope information. The temperature sensitivity is 521.4 kHz/$^{\circ }$C at 3.05 GHz and the bend-induced loss sensitivity is 24.845 MHz/turn (diameter of 2.30 cm) at 10 turns where is adjacent to the critical point of bifid dips merging. The proposed scheme provides an extraordinary design avenue which can be extended to diverse ring resonators in both photonic integrated circuits and fiber links for exploring compelling functions.