CHARACTERIZATION AND OPTIMIZATION CRITERIA FOR FILTERLESS ERBIUM-DOPED FIBER LASERS

The emission wavelength of a unidirectional ring erbium-doped fiber laser (EDFL) with no filters has been characterized. A measurement of the emission and the absorption erbium-doped fiber cross sections together with a theoretical model based on the solution of the rate equations for the ring laser shows that the laser emission wavelength depends on the cold-cavity losses or on the active fiber length and dopant concentration. The threshold pump power, the output power, and the slope efficiency of the EDFL have been measured and theoretically evaluated versus cold-cavity loss and active fiber length. A simple relation among loss, active fiber length, and dopant concentration that permits the design of the cavity with the maximum slope efficiency has been found.