Continuous-Wave Room-Temperature Masers, using NV-Centers in Diamond

The concepts of microwave amplification by stimulated emission of radiation (MASER) were developed in the late 1950s, in conjunction with its optical counterpart the laser. While the Laser found applications in many fields, ranging from fundamental science to industry and everyday life, the applications of the maser were highly specialized e.g., for deep-space communications and astronomy. This was due to the extreme operating conditions of the first masers, requiring cryogenic temperatures and high vacuum environments. However, the maser’s excellent low-noise microwave amplification properties still make it an attractive candidate for a broad range of microwave applications. To this end, the recent realization of a continuous-wave room temperature maser, using NV-centers in diamond, invigorated the Maser as an intriguing platform for microwave research and development [1].



Here, we characterize the operating space of a diamond NV-center maser system. Key for the continuous emission of microwave photons is a level inversion, in addition to a high-quality, low mode-volume microwave resonator to enhance the spontaneous emission of the NV-center spin ensemble. We investigate the performance of the maser system as a function of level inversion and resonator quality-factor and construct a phase diagram, identifying the operating parameter space and discuss the optimal working points and pathways for optimization.



[1] Jonathan D. Breeze et al., Nature, Volume 555, 493, 2018