Dual-pump few-mode fiber optical parametric amplification: analytical model and optimization strategy

Abstract

The realization of long-haul mode-division multiplexing (MDM) transmission requires a matched optical amplifier with similar gain profiles among all guided modes. The fiber optical parametric amplifier (FOPA) has several attractive characteristics, including wideband, high gain, and fast transient response. Here, we demonstrate an analytical model for the dual-pump few-mode FOPA (FM-FOPA), by taking all types of intramodal and intermodal four-wave mixing (FWM) interactions arising in a highly nonlinear few-mode fiber (HN-FMF) into account. Meanwhile, we provide a detailed description of corresponding phase-matching conditions, including the effect of high-order dispersion coefficients up to the fourth order. Equipped with this tool, we outline the optimization strategy of the dual-pump FM-FOPA. Next, we design a graded-index HN-FMF to satisfy the dispersion requirements of the dual-pump FM-FOPA. Under the optimal HN-FMF design, the dual-pump FM-FOPA can simultaneously amplify two modes with the simultaneous features of wide bandwidth ( ∼ 35 n m ), high gain ( > 56.29 d B ), low differential mode gain (DMG) ( < 0.59 d B ), and low wavelength-dependent gain ripple (WDGR) ( < 1.92 d B ).