Broadband microwave emission from acoustically modulated gain-driven polaritons

Abstract

By integrating a cantilever into a gain-embedded cavity magnonics platform, we investigate the impact of mechanical vibrations on gain-driven polaritons. The cantilever’s modulation creates a series of Floquet states spaced by the mechanical vibration energy, leading to microwave frequency comb emission centered at 3.5 GHz, with comb spacing as narrow as a few kilohertz. When the modulation frequency drops below 1 kHz, where the modulation period significantly exceeds the emission coherence time (360μs), quasienergy level overlap results in broadband microwave emission. The emission bandwidth is determined by the combined effects of mechanical modulation of the cavity and magnon–photon coupling (i.e., detuning). These results highlight the potential of acoustic-frequency modulation in a gain-driven polariton system to precisely control microwave emission characteristics.