High-power 813-nm Tm-doped ZBLAN fiber MOPA with signal-light photodarkening suppression.

The photodarkening suppression effect of an 813-nm -doped ZBLAN fiber amplifier has been investigated. We have experimentally observed that a photodarkened fiber can be bleached by an 813-nm light and that the photoinduced loss during the amplifier operation is effectively suppressed with the help of the high-power signal. To the best of our knowledge, this is the first investigation of the photodarkening suppression by using a higher power signal in -doped fiber amplifiers.