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Fiber lasers, owing to the high beam quality and super robustness, are widely used in fields from optical communications, fiber sensing, biomedicine to material processing. The use of glass fibers as the gain medium has, however, posed a strong obstacle for improving efficiency and, especially, achieving efficient lasing action in the mid‐infrared (MIR) region, because of the relatively large nonradiative energy loss. Here, the fabrication of a Tm3+‐doped tellurate glass‐ceramic (GC) fiber is demonstrated, which enables enhanced lasing action at ≈2 µm. Compared with the as‐prepared fiber, the optical conversion efficiency of GC fiber is increased from 8.8% to 14.1%. The microstructure and spectral characterization analyses suggest that the improvement of the laser performance in GC fiber is induced by the significant change of the local environment surrounding Tm3+ ions due to the formation of nanocrystals within the glass fibers. Moreover, the developed GC fiber also enables Q‐switched pulsed laser output at ≈2 µm with a pulse energy of 3.2 J and pulse width of 4.1 ns. The results demonstrated here may have strong implications in the development of MIR fiber lasers and the applications of GC fibers in MIR photonics. [ABSTRACT FROM AUTHOR]

Abstract: White lasers are promising illuminants for emerging visible light communication, which can overcome bottlenecks of lower energy conversion efficiencies and output powers in traditional white light‐emitting (WLE) diodes. However, optical gain materials for white lasers are suffering from great challenges of material growth and growth‐compatible cavity structure where lasing of all three elementary colors can be supported simultaneously. Here, an exquisite physical strategy is demonstrated to realize simultaneous red, green, and blue (RGB) upconversion (UC) photoluminescence for white light modulation for the first time, namely using dual lasers at 850 and 980 nm to stimulate easy‐fabricated glass ceramics (GCs) fiber laser materials (Pr3+ single‐doped germanium oxyfluoride GCs). It is shown that tailorable white light is much more sensitive to lower dopant concentration for GCs than that for glass. Furthermore, compared to glass, UC fluorescence intensities in GCs have approximately two orders of magnitude enhancement. The feasibility of the judicious dual‐lasers excitation tactic is validated for high efficacious RGB fluorescence emission for white light from Pr3+ single‐doped GCs via electronics transition dynamics and theoretical calculations. The white light emission from Pr3+ single‐doped GCs, adjusted by simultaneous dual‐lasers excitation, may open a novel door to develop white light GCs fiber lasers for application in future wireless communication. [ABSTRACT FROM AUTHOR]