Single-longitudinal-mode fiber ring lasers with a saturation-level-controlled saturable absorber

Single-longitudinal-mode (SLM) operation characteristics of an erbium-doped fiber (EDF) ring laser with an EDF saturable absorber have been measured and compared under two different-wavelength control-pump cases. The main EDF ring cavity was pumped with a conventional 977-nm-wavelength gain-pump laser diode, the EDF saturable absorber section attached to the main cavity via an optical circulator was pumped with a control-pump-laser beam of either 980-nm or 1531.9-nm wavelength to deliver the ring-laser output of 1541.4-nm wavelength. Our experimental results indicate that the control-pump-laser beam in the 1530-nm-wavelength region provides higher output power and wider wavelength range of the SLM operation of the ring laser than that in the 980-nm-wavelength region does.