Technological implementation of a photonic Bier-Glas cavity

The generation of single-and entangled photon pairs is a critical component in the field of quantum information networks. Quantum dots embedded in micro-cavities are a promising realization capable to deliver such non-classical light. Here, we discuss the fabrication and functionality of a photonic Bier-Glas cavity. By design, this device architecture combines the ability to achieve Purcell enhancement characteristic for photonic micropillar structures with a broadband photonic mode of a vertical, tapered waveguide [1]. Such a low Q-factor microcavity supports broadband optical resonances and, therefore, it should allow for efficient extraction of entangled photon pairs. The cavity, which is characterized by a small mode volume, also promises significant enhancement of the quantum dot spontaneous emission due to Purcell effect. Our device is based on a MBE grown GaAs/AlGaAs heterostructure containing a low-density layer of InAs QDs grown with the partial capping and annealing technique. Careful optimization of the subsequent reactive ion etching step allows us to implement its characteristic Bier-Glas shape. Initial optical characterization verifies the presence of optical resonances, as well as pronounced, bright QD emission signals.