Proposal of tunable Rydberg exciton maser.

We propose a continuous-mode solid-state maser based on Cu2O, where ensemble of highly excited Rydberg exciton states serves as a gain medium. We show that the system is highly tunable with an external electric field, allowing for a wide range of emission frequencies within terahertz range. Numerical simulations of the system dynamics are performed to optimize the conditions for efficient masing and estimate the emission power.