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Lasing in the ultraviolet has been observed in neodymium-doped fluorozirconate glass (ZBLAN) fibres at room temperature. For a cavity output coupling of < 0.1%, 74 µW of power was obtained at 381 nm (4D3/2 → 4I11/2 transition of Nd3+) when a 45 cm long fibre was pumped with 275 mW at a wavelength of nominally 590 nm.
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Funk et al. (1994) studied this question.
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