Maser Threshold Characterization by Resonator Q-Factor Tuning

TL;DR

This paper investigates how the quality factor of the resonator and spin level-inversion influence the operation of a room-temperature diamond NV$^-$ center maser, aiming to optimize its continuous microwave emission capabilities.

Contribution

It introduces an optimized setup for maser characterization, focusing on the interplay of resonator Q-factor and spin inversion, to identify optimal operating conditions.

Findings

Identified the parameter space for effective maser operation.

Highlighted the importance of resonator Q-factor and spin inversion degree.

Provided guidelines for maximal continuous microwave emission.

Abstract

Whereas the laser is nowadays an ubiquitous technology, applications for its microwave analogue, the maser, remain highly specialized, despite the excellent low-noise microwave amplification properties. The widespread application of masers is typically limited by the need of cryogenic temperatures. The recent realization of a continuous-wave room-temperature maser, using NV$^-$ centers in diamond, is a first step towards establishing the maser as a potential platform for microwave research and development, yet its design is far from optimal. Here, we design and construct an optimized setup able to characterize the operating space of a maser using NV$^-$ centers. We focus on the interplay of two key parameters for emission of microwave photons: the quality factor of the microwave resonator and the degree of spin level-inversion. We characterize the performance of the maser as a function of these two parameters, identifying the parameter space of operation and highlighting the requirements for maximal continuous microwave emission.