High power high repetition rate supercontinuum generation in graded-index multimode fibers

摘要

Graded-index multimode fibers can handle high average powers and featureunique nonlinear dynamics due to spatio-temporal evolution of the light inside.We report on generation of octave-spanning spectrally flat supercontinua ingraded-index multimode fibers using a compact, ytterbium-doped all-fiber lasersystem. Supercontinua with output powers as high as $\sim$4 W and 2 MHzrepetition rate obtained with more than 1 $\mu$m spectral bandwidth. Evolutionof supercontinuum is investigated by studying the effect of launch power,repetition rate, fiber length and core size. Numerical simulations areperformed to investigate underlying nonlinear dynamics in details andcalculated results are well-aligned with experimental spectra. To the best ofour knowledge, this the highest average power and repetition supercontinuumsource ever reported in a standard graded-index multimode silica fiber