Transient response of a gain-driven polariton

The development of gain-driven polaritons offers a fresh approach to enhancing solid-state microwave sources and amplifiers, apart from the traditional concept of the maser. Despite their potential, these polaritons are governed by intricate dynamics that remain largely unexplored, impeding practical applications. The authors employ time-domain measurements to investigate the transient response of gain-driven polaritons, revealing distinct dynamical behaviors: damping, zero damping, and antidamping. This insight could impact the engineering of ultrafast polaritonic devices tailored for coherent microwave and optical applications.