Intrinsic loss of few-mode fibers

We summarize theoretical formulae for determining the intrinsic loss of few-mode fibers and compare intrinsic losses among step-index and parabolic graded-index few-mode fibers (FMF) with different dopants, and with single-mode fibers (SMF). The low-loss characteristics of pure-silica-core FMFs, in comparison with SMFs, give rise to additional motivations for pursuing mode-division multiplexed transmission over parallel-SMF transmission, and quasi-single-mode (QSM) transmission over ultra-large-area SMF transmission.