Q-switched fiber lasers with controlled pulse shape

We report on the pulse shape of an actively Q-switched fiber laser. This master oscillator power amplifier architecture generates pulses with multiple peaks due to its intrinsic dynamics. Modeling and experimental results provide us a detailed understanding of the relative importance of the different time constants on the dynamics of the laser, which allows us to define optimized design parameters that lead to smooth and controlled pulse shapes. This solution is simple and robust; operation over a broad range of repetition rate and output power is achieved without any adjustment of the laser settings, and the corresponding variation of the optical performances is minimal.