Simulation of Kerr Lens Modelocking Behavior in Sagittal Plane

Abstract

Femtosecond oscillator is first step to generate femtosecond laser pulse. Simulation of the laser beam behavior in the oscillator cavity, especially in the gain medium is essential to realize and optimize the oscillator output pulse characteristics. In this work, at first we simulate the laser beam propagation in a folded cavity with curved mirrors in symmetric and asymmetric designs using the ABCD ray tracing technique for a Gaussian beam shape to achieve influence of Kerr lens modelocking in sagittal plane. We use split-step method to obtain the beam intensity changes in the ti:sa rod and shooting method to calculate the beam spot size on the first cavity mirror. In following the influence of the gain medium position changes on the size and position of the beam waist and also on the misalignment sensitivity parameter for the sagittal plane is simulated. Furthermore the misalignment sensitivity parameter and the size and position of the beam waist are not identical for the beams in the sagittal plane, therefore to actualize an optimum design it is necessary to simulate the beam propagation in plane which is not usually considered in early design because of complication of the simulation.