Theoretical analysis of a Q-switch erbium doped fiber laser

The performance of a Q-switch fiber laser with two fiber Bragg gratings as cavity mirrors was theoretically analyzed employing a set of rate equations for the ion populations and the photon flux inside the cavity. The model simulates the emission in the 1550 nm spectral region of an erbium-doped fiber laser pumped at 980 nm, where the temporal modulation is performed fixing one of the gratings to a piezoelectric (PZT) element. The temporal evolution of different frequency components is governed by the instantaneous overlap between both gratings. A frequency sweep that is observed in the output contributes to broaden temporally the pulse. Theoretical results are in coincidence with experimental values previously reported.