LENGTH-DEPENDENT STATIC-PROPERTIES OF ND-DOPED FIBER-LASERS - OPTICALFEEDBACK EFFECTS

Nd-doped fibre lasers of various lengths have been used in external ca vity configurations. The influence of an effective feedback beam on th e static properties of the laser output-intensity shows a clear depend ence on fibre-length, owing to gain saturation effects and to residual loss mechanisms other than resonant absorption (these include Rayleig h diffusion, localized impurities, etc.). A different influence of the back-coupled signal on the forward and backward beams which propagate inside the fibre medium is demonstrated. A simple model based on a st andard rate-equation analysis is shown to describe the observed fibre- length-dependent properties.