Principles of operation of a passively mode-locked fiber ring laser and 3D mapping of ultra-short pulses

In this article, we study the operation and basic elements in a passively mode-locked fiber ring laser (PML-FRL), emphasizing the saturable absorber (SA) effect seen as a nonlinear filter in transmission, which is produced by the non-linear polarization rotation (NPR) and a linear polarizer. Besides, we employ a technique of 3D mapping measurements for characterizing ultra-short pulse dynamics.