Strong optical bistability in a simple L-band tunable erbium-doped fiber ring laser

We demonstrate strong optical bistability in a widely tunable L-band erbium-doped fiber ring laser pumped by a 980-nm laser diode. The bistable region is as much as 150-mW wide and can be controlled by the lasing wavelength or the length of erbium-doped fiber. The mechanism for the bistability is not typical cross gain saturation in a two-mode operation, but rather saturable absorption strongly enhanced in the proposed scheme.