Microlaser Output from Rare‐Earth Ion‐Doped Nanocrystal‐in‐Glass Microcavities

Abstract Nanocrystallized glass ceramics (NGCs) are important optical materials, but few studies have focused on their laser actions. Here, by precipitation of NaYF₄ nanocrystals enriched with Er³⁺ ions in an oxide glass matrix, great enhancement of the luminescence properties for the NGC microspheres is realized. By carefully matching the refractive index of the glass matrix with that of the NaYF₄ nanocrystals and controlling the size and distribution of the precipitated nanocrystals, the absorption and Rayleigh scattering losses that are harmful to quality (Q) factors are efficiently suppressed. As a result, the NGC microsphere cavities present ultrahigh Q factors up to 10⁶ (@ 1610 nm), which is slightly lower than that of the microsphere cavities made by precursor glass. Moreover, single mode whispering gallery modes (WGMs) lasing from the NGC microsphere cavities for the first time is successfully realized. Compared with the microsphere cavity based on glass, the NGC microsphere cavity exhibits large enhancement of the pumping efficiency by more than 7 times and a decrease in the threshold by more than 2.5 times. The results demonstrated here suggest a novel method for improving the laser output performances of microcavities, which may have potential applications in areas of photonics and optical communication.