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1Quantitative ultrafast carrier imaging in perovskite microlaser with optical coherence microscopy
A. Popkova1*, M. Sirotin1, I. Soboleva1, A. Pushkarev2, S, Makarov23, V. Bessonov1, A. Fedyanin1
1-Lomonosov Moscow State University, Russian Federation
2- ITMO University, Russian Federation
3- Harbin Engineering University, China
* popkova@nanolab.phys.msu. ru
Lead halide perovskites are the promising materials for integrated photonics due to their low lasing threshold and broadband spectral tunability, as well as simple fabrication of small lasers by various cost-efficient approaches [1,2]. The perovskites have a high refractive index, which significantly changes under the action of free carrier generation [3]. At the same time, the spatiotemporal dynamics of carriers significantly affects the efficiency of laser generation and the quantum yield of fluorescence. Registration of ultrafast refractive index modulation (An) is an indispensable tool for studying light-matter interaction on fundamental and applied levels. With the development of nanophotonic devices new methods for ultrafast refractive index modulation visualization with high spatial and temporal resolution became of particular relevance.
In this work, we succeeded in implementing the pump-probe scheme with a probe in the form of an optical coherence microscopy (OCM) [4], which makes it possible to register changes in the refractive index with a resolution of 1 ps in time, 0.5 ^m in space, and An sensitivity of down to 10-3 RIU. The possibilities of the method are demonstrated on perovskite microcrystals, in which laser generation can be caused by a femtosecond pump pulse either illuminating the entire sample or acting locally, that makes it possible to study the spatial dynamics of a locally generated plasma cloud. With the help of the developed method, direct quantitative spatiotemporal visualization of the dynamics of carriers in a perovskite crystal during lasing is carried out, and the relaxation and diffusion constants are determined.
The work was performed under financial support of the Russian Science Foundation (grant No. 20-12-00371-n).
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