Recently, the Future Optical Laboratory led by Academician Zhuang Songlin, Prof. Gu Fuxing published a paper titled “Direct-Bandgap Bilayer WSe2/Microsphere Monolithic Cavity for Low-Threshold Lasing” in Advanced Materials (IF: 30.849). Prof. Gu Fuxing and Associate Prof. Yu Jiaxing were the corresponding authors, and Yu and Dr. Xing Shuai were the first authors. The project design, experiment and simulation work of the research were finished by Future Optical Laboratory of USST.
Monolayer transition metal dichalcogenides (TMDs) have emerged as widely accepted 2D gain materials in the field of light sources owing to their direct bandgap and high photoluminescence quantum yield. However, the monolayer medium suffers from weak emission because only a single layer of molecules can absorb the pump energy. Moreover, the material degradation when transferring these fragile materials hinders their cooperation with the optical cavity further. In this study, for the first time, we directly grew single-domain bilayer WSe2 on silica microspheres, achieving a high-quality entirely wrapped WSe2/MS monolithic structure. During the deposition, large tensile strain is imposed on the bilayers and results in an ≈60-fold enhancement in the PL intensity. In addition, the thick material further deepens the interaction between the gain material and the cavity mode, leading to an increase in the confinement factor by 20-fold compared to that in previous cavities based on monolayers. Compared with previously reported MS lasers based on planar TMDs, these characteristics show great improvements. Owing to the above advantages, we achieve room-temperature lasing with a low threshold value of 0.72 W cm−2, nearly an order of magnitude lower than that of existing TMD lasers.
Link to the paper: https://www.usst.edu.cn/2022/0331/c35a45788/page.htm