Differential mode group delay measurement for few-mode fibers based on cepstrum analysis

The differential mode group delay (DMGD) among various modes in few-mode fibers (FMFs) is a critical parameter for characterizing FMFs' channels. Therefore, achieving a convenient, fast, and accurate measurement of DMGD across the entire communication band for different modes is essential. In this work, we propose a novel, to the best of our knowledge, cepstrum-based method for DMGD measurement in FMFs. A comparative study of the proposal with the conventional correlation method reveals that both methods exhibit similar accuracy, while the cepstrum approach offers higher computational efficiency. Furthermore, in contrast to the optical time-domain reflectometry (OTDR) and broadband estimation methods, the proposed method enables assessment of the wavelength dependence of DMGD with high accuracy.