Collecting Telecom Photons From Circular Bragg Gratings Using Optical Fibers and 3D Printed Micro‐Lenses

Deterministic sources of quantum light are becoming increasingly relevant in the development of quantum communication, particularly in deployed fiber networks. Therefore, efficient fiber‐coupled sources at telecom wavelength are highly sought after. With this goal in mind, the fiber coupling performance of quantum dots is systematically investigated in optical resonators under three experimental configurations. For the first time coupling efficiency and sensitivity are quantified to spatial displacement for single‐mode fibers with 3D printed optics on their tip, and benchmark their behavior over a commercial cleaved‐cut fiber and a standard optical setup. The reduction of the required optical elements when operating with a lensed or a bare fiber allows for an increased end‐to‐end efficiency over a standard setup. For the perspective of realizing a mechanically stable fiber‐coupled source, the spatial tolerance is precisely quantified to fiber‐cavity misalignment, observing less than count rate drop for several micrometers displacement. In the spirit of precise quantification and reproducibility, the experiments are performed on multiple photonic resonators. These results will play a key role in the future development of fiber‐coupled sources of quantum light.