Photoinduced absorption in thulium-doped ZBLAN fibers

Abstract

We report on the observation of photoinduced absorption in four different thulium-doped ZBLAN fibers exposed to 1.12-μm light. The darkening rate is shown to follow a fourth-power dependence on the pumping intensity and a strong dependence on the Tm3+ concentration. The photoinduced absorption is observed mainly in the UV–visible part of the spectrum but extends slightly beyond 1 μm in the near-infrared.