Intermodal cross-phase modulation enabling all-optical temporal and spatial shaping in few-mode fibers

Schnack M, Lüpken NM, Fallnich C

Abstract

We present a concept using intermodal cross-phase modulation to enable all-optical temporal, spatial, and spatio-temporal pulse shaping inside a few-mode fiber. The pulse shaping is achieved by all-optically tuning a fiber-based, inline Mach--Zehnder interferometer, which uses two transverse modes of the fiber as interferometer pathways and long-period gratings for mode coupling. We explore the shaping capabilities of such a two-mode Mach--Zehnder interferometer and compare simulations based on the multimode generalized nonlinear Schrödinger equation to a simplified model based on the analytical description of intermodal cross-phase modulation. Such an approximated description reduces computation times from hours to less than a minute and proves to be valid for most scenarios, enabling fast and easy prediction of the shaping functionality in such devices.