An all-inorganic perovskite micro/nano-structure has been demonstrated by a collaborative team of researchers from Shanghai Institute of Optics and Fine Mechanics of the Chinese Academy of Sciences (CAS), Shanghai Institute of Technical Physics of CAS and Nanjing Xiaozhuang University, that is believed to be a promising candidate for achieving high-performance nano-lasers.

Semiconductor nano-lasers with high spectral purity and stability, namely single-mode nano-lasers, are very desirable in color laser display, on-chip optical communication and computing. To date, most of reported nano-lasers exhibit multi-mode structure resulting from in-homogeneous gain saturation, while the realization of high-quality single-mode laser is very challenging and is largely limited by the cavity structure and the properties of the gain medium.

The team explained that the Goldschmidt tolerance factor t of many structures is lower than the threshold value (t~0.8) for realizing an all-inorganic perovskite of the ABX3 form, resulting in few alternatives for A cation. Rubidium, the neighbor element of cesium, is another potential choice for the A cation to gain all-inorganic perovskites. Moreover, RbPbBr3 perovskites may exhibit novel photonic and optoelectronic properties and help understand the structure-property relationship of perovskite.

According to the study, all-inorganic perovskite RbPbBr3 micro-spheres fabricated through a chemical vapor deposition process had a regularly spherical shape, smooth surface and strong photo-luminescence emission at ~464 nm.



These micro-spheres could function as optical cavity and a gain media to achieve single-mode nano-laser. Under the pumping of a 400 nm femtosecond laser, high-quality single-mode laser was realized in an individual RbPbBr3 micro-sphere (D~1.2 μm) with a narrow linewidth and low lasing threshold.

Also, broadband high-quality single-mode nano-laser from 475-540 nm could be obtained by tuning the cavity size and the molar ratio of rubidium and cesium anions. Theoretical simulations using the finite domain time difference solution showed strong optical confinement of RbPbBr3 spherical micro-cavity, that was why most micro-sphere nano-laser exhibited excellent performance.

The work demonstrated a new gain medium for achieving high-quality single-mode nano-lasers, and provided a new platform to explore the structure-property relationship of perovskite family.

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