Optimisation of CVD Diamond for Applications in Room-Temperature Masers

Masers are the microwave analogue of lasers and can be operated as oscillators and amplifiers with quantum-limited noise performance. Despite their exceptionally low noise, conventional masers have historically been limited to niche applications in radio astronomy and deep-space communications due to their requirement for ultrahigh vacuums and cryogenic temperatures.<br/><br/>Recently masers capable of operating continuously at room temperature have been demonstrated using ensembles of nitrogen-vacancy (NV) centres in diamond, opening a route to the widespread use of masers across a range of new applications in telecommunications, medical imaging and quantum sensing.<br/><br/>In order to realise these broad applications it will be necessary to build miniaturised, portable diamond masers that can be readily integrated into existing standards but to date this has been limited by the highly homogeneous magnetic fields required for diamond masers to maintain coherence. Here we discuss strategies for relaxing the field-homogeneity requirement by optimising the material parameters of CVD-grown NV-diamond and present results benchmarking the performance of diamond masers using diamond gain media in which the concentrations of 13C nuclei and nitrogen-vacancy spins are varied. We conclude by discussing recent progress in the development of miniaturised diamond masers.