Experimental studies on exciton-polaritons in Metal-Organic Framework microcrystals leading to efficient inversionless lasing
ABSTRACT :
Exciton-polaritons are quasiparticles formed when a sufficiently strong interaction is maintained between electron-hole pairs (excitons) inside a material and photonic modes of an optical microcavity. Only a few attempts have so far been made towards investigating the intriguing aspects of the Physics of exiton-polaritons and towards exploring their potential for technological applications such as inversionless lasers, polariton routers and polariton transistors. A cost-effective and large-scale implementation of such quantum devices at room temperature is mainly hindered by the complex and sophisticated growth techniques involved in the fabrication of a high-quality exciton-polariton microcavity. In this context, we report an extremely simple realization of exciton-polaritons in single-crystalline microplates of a layered Metal-Organic Framework (MOF), which can be synthesized through a facile solvothermal approach. Such a MOF microplate naturally acts as both excitonic-material and optical microcavity, and hence eliminates the costly, time-consuming fabrication process of a high-quality polariton microcavity. With a combination of experiments and theoretical modelling, we demonstrate that exciton-polaritons are formed at room temperature, making use of the strong coupling between Fabry-Perot cavity modes formed inherently by two parallel surfaces of a microplate and Frenkel excitons provided by the 2D layers of dye molecular linkers in the MOF. Flexibility in rational selection of dye linkers for synthesizing such MOFs renders a large-scale, low-cost production of solid-state and micro-sized, exciton-polaritonic devices operating in the visible and near infrared (NIR) range. Our work introduces MOF as a new class of potential materials to explore polariton-related quantum phenomena in a cost-effective manner.