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.
@article{arxiv.2302.10811,
title = {Maser Threshold Characterization by Resonator Q-Factor Tuning},
author = {Christoph W. Zollitsch and Stefan Ruloff and Yan Fett and Haakon T. A. Wiedemann and Rudolf Richter and Jonathan D. Breeze and Christopher W. M. Kay},
journal= {arXiv preprint arXiv:2302.10811},
year = {2023}
}