Deterioration of Bismuth-Doped fiber lasers performance induced by blue and green laser light launched into cladding

Abstract

For the first time, we demonstrate the photobleaching process of bismuth-related active centers (BACs) induced by blue and green laser radiation launched into the cladding of an active fiber having the low-refractive index polymer coating. The changes in small-signal loss spectra of the exposed Bi-doped fibers are presented and analyzed. Temporal evolution of luminescence intensity of BACs is measured for different powers of bleaching light. The effect of bleaching on Bi-doped fiber laser characteristics was studied. It was found that time-to-destruction of Bi-doped fiber laser varies in dependence on the power and wavelength of the used bleaching light. In particular, the blue laser radiation launched into the active fiber cladding for a timespan of almost 10 sec can completely disable the operation of a bismuth laser at 1.71 µm. We estimated the efficiency of bleaching process in Bi-doped fiber under blue laser irradiation.