Optimization of Fiber Ring Resonator Transmission Spectrum Based on Multi-Beam Interference Theory and Transfer Matrix Theory

Polarization maintaining fiber(PMF) effectively reduces mode splitting and back scattering interference compared to Single Mode Fiber(SMF) in the Fiber Ring Resonator(FRR). In traditional reflection PMF-FRR(RPMF-FRR) structure, classic theoretical model suggests that the orthogonal mode loss difference of the coupler, i.e. the phase difference between the output light field at the cross end and through end of the coupler is
$\pi /2$
, however, in practical research, this angle is often less than
$\pi /2$
, which will generate resonance curve asymmetric and severely exacerbate systems instability centered on PMF-FRR. To address this issue, based on the multi-beam interference theory, this article establishes a new mathematical theoretical model and demonstrate a transmission PMF-FRR(TPMF-FRR) with two couplers, the symmetry error has been dwindle to 0.8%, which is a huge improvement compared to 11% of traditional reflection PMF-FRR(RPMF-FRR). Furthermore, different construction methods of TPMF-FRR were studied through theoretical analysis and experimental verification based on the transfer matrix theory, provide guidance for further optimizing the transmission spectrum. The findings contribute to enhance the system precision centered on FRR.