High color purity and color rendition of 2D luminescent materials have long been pursued for applications in low-dimensional lighting, display, biolabeling, and laser. However, the reported photoluminescence (PL) linewidth of most 2D luminescent materials is about dozens of meV. Herein, a brand-new luminescent system of 2D rare earth (RE) material EuOCl (1.1 nm) with ultra-narrow linewidth (1.2 meV) at room temperature is successfully synthesized via chemical vapor deposition (CVD). The linewidth of EuOCl flakes at room temperature is even narrower than most 2D luminescent materials and heterostructures detected at below 10 K. Impressively, the as-synthesized EuOCl flakes show abnormal temperature-dependent photoluminescent properties, which is absolutely different from the relatively stable 4f–4f transitions in RE owing to shielding from outer shell electrons. J-mixing effect has been successfully applied for this phenomenon. Undoubtedly, luminescent 2D EuOCl flakes will open new territory for the applications of 2D RE materials in the 2D luminescent areas, especially for the applications at room temperature.
Yongbao Xiao,Jinzhong Zhu,Ludong Kuang,Yao Ji,Qilai Zhao,Changsheng Yang,Weichao Wang
Single-frequency fiber lasers (SFFLs) are of pivotal importance across optical communication , scientific research and national defense due to their excellent beam quality, long coherent length and low noise. However, the development of high-gain rare-earth-doped glass fibers, which are the key medium used in the SFFLs, remains a critical scientific challenge. To address this issue, we design and fabricate a single-mode fluoro-sulfo-phosphate-based Er 3 + /Yb 3 + -codoped glass fiber (denoted as FSP-EYDF). The gain properties and laser performance of the FSP-EYDF have been investigated comprehensively. The results show that the small signal gain coefficient of the home-made FSP-EYDF can reach 4.7 dB/cm at 1535 nm, which is three times higher than that of the silica glass fiber. A short piece of FSP-EYDF with a length of only 1.6 cm has been utilized as a gain medium to support an SFFL operating at 1534.4 nm, which has a threshold of ∼ 18 mW and a linewidth of 3.15 kHz. This study indicates that high-gain FSP fibers are promising candidates for compact low-threshold narrow-linewidth SFFLs.
The whispering gallery mode (WGM) microcavity has a high-quality factor and small mode volume, for the property of confining photons in a small volume for a long time, which enhances the light-matter interaction. Combining with quantum dots that act as gain medium, it can realize low-threshold and narrow-linewidth microlasers with excellent performance. However, achieving conventional whispering gallery mode lasers still requires complex preparation conditions. Here, we report a narrow linewidth whispering gallery mode lasing from all-inorganic perovskite quantum dots (CsPbBr 3 QDs), illustrating facile and cost-effective properties. CsPbBr 3 QDs with excellent properties were synthesized by hot injection method and used as gain media for lasers, and microspheres as optical resonators . The whispering gallery mode laser with a quality factor Q of 4791 and a narrow linewidth of 0.11 nm was obtained at room temperature. The WGM microlaser achieved by this paper could be a great application prospects in biotechnology.
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