In this project, it has been tried to design the model of a laser for a use related to obtaining images in the study of the migration of cells. It is intended that this serve as an option that offers an alternative that is versatile and less costly to those used in microscopy research. As a result of the investigation of different design options, an optical fiber laser was chosen as these meet the requirements in terms of emission of short pulses and power levels suficient, while also having advantages such as compactness, low losses and the possibility of using diodes for pumping. To the project, I would like to include a brief theoretical review on different lasers and the concept of modeling, techniques of saturation absorbers have been explained and the theoretical model of a mode-locked in fiber optic-doped ring with Er. At the same time, several simulations of this have been carried out with the objective of furthering the study of the characteristics of this type of lasers.