An efficient 1.46 mu m thulium fiber laser via a cascade process

Continuous wave (CW) lasing in a thulium-doped fluorozirconate fiber at 1.46 mu m with a 20% slope efficiency was observed. Simultaneous lasing at 1.86 mu m with 29% slope efficiency depopulates the normally long lived 1.46- mu m terminal level. It is shown that the cascade process can increase the slope efficiency eta /sub s/, of the 1.45- mu m transition by a factor of ten and the 1.86- mu m transition by a factor of eight. Calculations indicate that the CW laser thresholds decrease significantly.<
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