Planar metal-semiconductor Yagi-Uda type antennas for tunable narrow-linewidth quantum dot emitters
Tunable photonic architectures that improve the extraction efficiency of light from embedded epitaxial quantum dots across a wide spectral range are key enablers for developing bright sources of single and indistinguishable photons. In this study, we experimentally demonstrate planar multilayer antenna structures consisting of epitaxially grown AlGaAs and InGaAs membranes containing quantum dots sandwiched between metallic Au (or Ag) reflector and director layers together with Al$_2$O$_3$ spacer layers. We show that the linewidths and fine-structure splitting of the neutral exciton emission remain comparable to those measured in the corresponding unprocessed samples, demonstrating that the fabrication process preserves the optical quality of the emitters. In addition to broadband operation, we demonstrate that the planar architecture is compatible with electrical tuning via integrated diode structures, and strain tuning using piezoelectric actuators. In spite of limitations related to optical losses in the ultrathin metallic layers, the demonstrated fabrication simplicity, scalability, and compatibility with tunable quantum emitters establish planar antennas as a promising platform for solid-state quantum photonic devices.