In response to the Comment, we show that Engholm et al. [Opt. Lett. 33, 1216 (2008)] misinterpret the absorption peak at 230 nm and reach mistaken conclusions that contradict their experimental results. Differences in compositions and fabrication details mean that their results are only marginally relevant to our experiments [Opt. Lett. 32, 1626 (2007)]. The excitation of electrons to a charge-transfer band around 230 nm in Yb-doped aluminosilicate glasses leads to conversion from Yb, which, in our opinion, is more likely to account for photobleaching rather than photodarkening
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