Modelling the sub-100 fs Dy3+: Fluoride fiber laser beyond 3 μm

Abstract

Generating ultrafast pulses in the mid-infrared (mid-IR) region around 3 μm is a scientific and technological frontier at present. In this work, we have investigated the sub-100 fs Dy3+: fluoride fiber laser generation beyond 3 μm regime via the hybrid mode-locking mechanism based on the semiconductor saturable absorber mirror (SESAM) and the nonlinear polarization rotation (NPR) method numerically. Compared with the single SESAM- and NPR-based mode-locking, the hybrid mode-locked Dy3+: fluoride fiber laser delivers much shorter pulses via the fast and slow mode-locking from the NPR and SESAM, respectively. When dispersion compensation is taken into the hybrid mode-locking, the ultrafast pulse of 94 fs with a corresponding time-bandwidth product (TBP) of 0.333 is achieved. In addition, laser performance optimizations are investigated. By optimizing the parameters of the gain fiber and SESAM, the shortest pulse duration of 85 fs can be obtained. The results represent a feasible solution and design guidelines for ultrafast mid-infrared fiber laser generation beyond 3 μm.