Modulation instability in CW erbium-doped fiber ring lasers

Summary form only given. Modulation instability in optical fibers is known to lead to CW radiation break-up through the interplay of anomalous dispersion and fiber nonlinearity. We show that this type of instability is responsible for the multimode instability and consequent linewidth broadening observed in an erbium-doped fiber ring laser. In fact, the nonlinear wave mixing, occurring through the Kerr nonlinearity of the fiber, gives rise to a growing instability characterized by a gain bandwidth covering several longitudinal modes of the cavity.