Experimental study on chaos generation in an all-fiber erbium-doped fiber ring laser with a Mach-Zehnder interferometer

We experimentally study the chaotic behaviors in a compact all-fiber erbium-doped fiber ring laser (ED-FRL) with an added Mach-Zehnder interferometer (MZI) by using a phase-modulation method.A piezoelectric ceramic transducer (PZT) is incorporated in the MZI to introduce single-frequency phase modulation.The coexistence of intermittency and period-doubling bifurcation routes to chaos in the EDFRL system is observed by adjusting the modulation frequency or the phase modulation depth in the experiment.In addition, the EDFRL presents irregular multi-longitudinal-mode oscillation with a definite linear polarization when operating at intensity chaos state.