Cegep Garneau 1 article published in JoVE Engineering Automation of Mode Locking in a Nonlinear Polarization Rotation Fiber Laser through Output Polarization Measurements Michel Olivier1,2, Marc-Daniel Gagnon1, Joé Habel1 1Centre d'optique, photonique et laser, Université Laval, 2Département de physique, Cégep Garneau A protocol to detect and automate mode locking in a pre-adjusted nonlinear polarization rotation fiber laser is presented. The detection of a sudden change in the output polarization state when mode locking occurs is used to command the alignment of an intra-cavity polarization controller in order to find mode-locking conditions.