Boosting Single‐Photon Extraction Efficiency in GaN Through Radiative Mode Conversion

Abstract Highly stable and bright single‐photon emitters at room temperature are fundamental components of quantum information technologies, which support advanced applications such as quantum computing, quantum communication, and quantum sensing. A key challenge in realizing these technologies is the creation of efficient single‐photon sources capable of emitting across a broad spectral range. While defect‐based materials such as diamond, SiC, 2D materials and III‐nitrides show significant promise, broadband single‐photon extraction remains a considerable obstacle, often restricted to narrow emission bands through the use of resonant cavities. In this work, a novel approach is introduced to enhance the broadband extraction efficiency of single photons from GaN, a versatile III‐nitride material. By directly patterning circular Bragg gratings with partially etched trenches onto the GaN surface, efficient radiation mode conversion, boosting single‐photon extraction over a wide spectral bandwidth, is achieved. Crucially, this method eliminates the need for resonant cavities, which rely on precise period control through photolithography to achieve narrow bandwidth resonant modes, thereby supporting efficient extraction from various randomly distributed defects across a broad spectral range. This approach represents a major improvement over previous techniques by offering a practical solution for broadband single‐photon extraction from GaN and opening new possibilities for versatile quantum technologies.