Coherent Förster resonance energy transfer: A new paradigm for electrically driven quantum dot random lasers.

The many distinct advantages of random lasers focused efforts on developing a breakthrough from optical pumping to electrical pumping. However, progress in these is limited due to high optical loss and low gain. In this work, we demonstrate an electrically pumped quantum dot (QD) random laser with visible emission based on a previously unexplored paradigm named coherent Forster resonance energy transfer (CFRET). In the CFRET process, when a coherent photonic mode is formed because of multiple scattering of the emitted light traveling in mixed donor and acceptor QDs, the donor QDs not only serve as scattering centers but are also enable coherent energy transfer to acceptor QDs. Therefore, the laser action can be easily achieved, and the lasing threshold is greatly reduced. Our approach of electrically pumped QD-based random lasers represents a substantial step toward a full-spectrum random laser for practical applications.