Efficient Quasi-Resonant, Polarization-Selective Excitation of GaN Quantum Emitters

Defect centers in gallium nitride (GaN) emerge as bright sources of single photons, which recently have been demonstrated to optically interface a localized spin. However, the structure and composition of these defects as well as their efficient excitation techniques have not been a subject of thorough studies. This work presents evidence that by tuning the excitation laser energy to specific resonance values, the excitation efficiency can be enhanced, resulting in a relative increase of photoluminescence intensity by up to an order of magnitude. The resonances can be selectively addressed with linearly polarized light, while the emission dipoles remain unchanged, enabling polarization-controlled enhancement. These results establish an efficient method of excitation for GaN-based emitters, thereby increasing the generation rate of photons. The data are consistent with excitation via localized vibrational modes (LVMs) associated with point-defect complexes, establishing a practical quasi-resonant route to brighter, polarization-addressable operation of GaN defect emitters and clarifying their energy-level structure.