Generation of an octave-spanning supercontinuum in highly nonlinear fibers pumped by noise-like pulses

Abstract

A supercontinuum generation system is developed, which consists of an erbium-doped fiber ring laser, an erbium-doped fiber amplifier, and a 100-m highly nonlinear fiber. Through nonlinear polarization rotation, the fiber ring laser generates a train of noise-like pulses in the form of repetitive picosecond pulse packets consisting of femtosecond noise-like fine temporal structures. The noise-like pulses are amplified before being sent into the highly nonlinear fiber. As a result, an octave-spanning supercontinuum from 1177 nm to 2449 nm is obtained, which has a 20-dB spectral width of 980 nm. Because of the nonlinearity of the fiber amplifier, the duration of the noise-like pulses is shortened while their average power is enhanced. However, the enhanced pulse energy makes the key contribution to the spectral broadening of the resulting spuercontinuum in this study since the highly nonlinear fiber is so long that the effect of the pulse compression on supercontinuum generation is weak.