Triple threshold transitions and strong polariton interaction in 2D layered Metal-Organic Framework microplates.

Room-temperature interaction between light-matter hybrid particles such as exciton-polaritons under extremely low-pump plays a crucial role in future coherent quantum light sources. However, the practical and scalable realization of coherent quantum light sources operating under low-pump remains a challenge because of the insufficient polariton interaction strength. Here, at room temperature, we demonstrate a very large polariton interaction strength, g ≈ 128  ± 21 μeVμm 2 realized in a 2D nano-layered Metal-Organic Framework (MOF). As a result, a polariton lasing at an extremely-low pump fluence of P 1 ≈ 0.01  ± 0.0015  μJcm -2 (first threshold) was observed. Interestingly, as pump fluencies increase to P 2 ≈ 0.031  ± 0.003  μJcm -2  (second threshold), a spontaneous transition to a polariton breakdown region occurred, which was not reported before. Finally, an ordinary photon lasing occurred at P 3 ≈ 0.11  ± 0.077  μJcm -2 (third threshold), or above. Our experiments and statistical model reveal new insights on the transition mechanisms characterized by three distinct optical regions. This work introduces MOF as a new type of quantum material, with their naturally formed polariton cavities, as a cost-effective and scalable solution to build micro-scale coherent quantum light sources and polaritonic devices. This article is protected by copyright. All rights reserved.