Fig. 3: Maser cavity design and resonance characterisation.

a Simulation image of SrTiO3 (light purple) inside the maser cavity (yellow). Plot of magnetic field density with directional arrows (red), implemented with electric wall boundary condition, setting tangential electric field components to zero and incorporating a boundary gap to minimise back reflections. SrTiO3 z-axis cutting plane displaying high concentration across the location of the PcPTP crystal gain medium. b Measured reflection coefficient (S11) using the cavity coupling loop exhibiting a resonant dip at 1.4493 GHz.