We discuss the origin of near- to mid-infrared emissions in Bi-doped oxide glasses recently reported [Opt. Lett. 37, 4260 (2012)]. Our detailed analysis indicates that the near- to mid-infrared emissions in the range of 1200–3000 nm peaking at , 2650, and 2700 nm do not result from Bi active centers in the oxide matrix but are due to the selective atmospheric absorption of thermal radiation induced by laser irradiation.
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