Quasi-periodic route to chaos in erbium-doped fiber laser

We present experimental evidence of quasiperiodic route to chaos in erbium-doped fiber laser operating simultaneously at 1.550 μm and 1.536 μm. Starting from a CW state for high pumping rates the system becomes T-periodic, 2T-periodic, 3T-periodic and chaotic for decreasing pumping ratios. The low-frequency spectra shows two fundamental frequencies. The nT-periodic regimes correspond to a frequency locking of the low frequency on a subharmonic of the high frequency. An adapted model based on the rate equations is numerically investigated and leads to a good qualitative agreement with the experimental data