Spontaneous and induced modulation instability in the presence of broadband spectra caused by the amplified spontaneous emission

Spontaneous and induced modulation instability (MI) in the presence of rather broadband spectra are shown in the conventional single-mode fiber (SMF) for the first time. The broadband spectra are caused by the amplified spontaneous emission (ASE) of the erbium-doped fiber amplifiers (EDFAs). The two kinds of MI are seeded by noise components and a probe beam which results from two EDFAs amplification, respectively. For the spontaneous MI, the MI threshold is shown to be ??170 mW, which contains the laser as well as the ASE component. For the induced MI, an idler beam appears and grows with the peak power of input pulses at first, and then multiple spectral peaks emerge.