Polarization-dependent output states of a fiber laser with nonlinear polarization rotation

A fiber laser with two different polarization-dependent output states is demonstrated. On the one hand, intensity-dependent loss in a nonlinear optical loop mirror, induced by nonlinear polarization rotation, can balance mode competition of a homogeneous broadening gain medium, and thus allows for stable room-temperature multiwavelength generation. On the other hand, intensity-dependent transmission can act as an equivalent saturable absorber, which results in passive mode locking of the fiber laser. It may thus serve two functions: passive mode locking and multiwavelength emission.