Speaker
Description
As quantum technology gains more importance, single photon sources such as semiconductor quantum dots become more relevant. One of the advantages of using single photons as qubit is the ability of photons to bridge long distances, hence the reason they are also referred to as flying qubits. Bridging long distances can be achieved by utilizing silica fibers, a mature technology which constitutes the backbone of our telecommunication infrastructure. However, the single photons have to be coupled into an optical fiber first, which in turn may also lead to unwanted losses.
A new method to avoid these losses is to place optical fiber structures directly above the quantum dots for efficient coupling. In this work, we use a single mode fiber with a 3D printed lens at the fiber tip to investigate the coupling efficiency and sensitivity of the coupling in the spatial lateral and vertical direction. The fiber coupling is performed onto quantum dots embedded in circular Bragg gratings operating in the telecom C-Band. Moreover, these results are then compared to a bare single mode fiber without the 3D printed lens and a commercially available microscope objective. In terms of the overall fiber coupling efficiency, the lensed and bare fiber outperform the microscope objective by up to a factor of 2.9 corresponding to a measured count rate at the detectors of 0.44MHz and 1.11MHz, respectively. For the spatial sensitivity, the lensed (bare) fiber exhibit their maximum FWHMs of 1.25µm (4.95µm) and 3.56µm (37µm) in the lateral and vertical direction, respectively.
These results will play a key role in the future development of fiber-coupled sources of quantum light.
