Influence of Intra Cavity Attenuation on the Linewidth of an Erbium Doped Fiber Ring Laser

tunable erbium doped fiber ring laser is constructed by controlling the intra cavity loss without the use of wavelength selective filters. For a given pump power, the linewidth of such a filterless laser is a function of the intra cavity loss. The linewidth characteristics in the C and L bands are independently observed and analysed. The results of numerical simulations of fiber ring laser are used to analyse the linewidth characteristics observed in the C band. The characteristics in the L band are interpreted qualitatively through the spectral dependence of the threshold power. The linewidth characteristics of a filter-less modelocked fiber laser are also addressed.