Demultiplexed single-photon source with a quantum dot coupled to microresonator

The characteristics of a single-photon emitter based on a semiconductor quantum dot, such as their indistin-guishability and brightness, depend on the stability of the recombination channel, which can switch spontane-ously between exciton and trion. We show that dominant recombination through neutral exciton states can be achieved by careful control of the doping profile near an epitaxial InAs/GaAs quantum dot placed in a columnar microcavity with distributed Bragg reflectors. The Hong-Ou-Mandel experiments carried out in the fabricated device demonstrate the degree of indistinguishability of 91% of successively emitted single photons within 242 ns at an efficiency of 10% inside a single-mode optical fiber. The achieved brightness made it possible to implement spatio-temporal demultiplexing of photons in six independent spatial modes with an in-fiber gener-ation frequency of more than 0.1 Hz.