Noiselike pulses with a broadband spectrum generated from an erbium-doped fiber laser

An erbium-doped fiber laser that produces a train of intense noiselike pulses with a broadband spectrum and a short coherence length is reported. The noiselike behavior was observed in the amplitude as well as in the phase of the pulses. The maximum spectral width obtained was 44 nm. The high intensity and the short coherence length of the light were maintained even after propagation through a long dispersive fiber. A theoretical model indicates that this mode of operation can be explained by the internal birefringence of the laser cavity combined with a nonlinear transmission element and the gain response of the fiber amplifier.