Passively mode-locked fiber laser with dispersion-imbalanced nonlinear loop mirrors

We propose a new laser scheme of passive mode locking where the nonlinear phase difference achieves nonreciprocal asymmetric imbalance of dispersion in a loop mirror. The dispersion-imbalanced nonlinear loop mirror (DINLM) is constructed with one segment of high anomalous dispersion and another segment of much lower dispersion. The pulses in clockwise direction disperse quickly and then remain broad in the second segment; on the other hand, pulses in counterclockwise direction remain short for the entire first segment and thus obtain a large amount of nonlinear phase shift.