Single- and Twin-Photons Emitted from Fiber-Coupled Quantum Dots in a Distributed Bragg Reflector Cavity

Nanomaterials (Basel). 2022 Apr 5;12(7):1219. doi: 10.3390/nano12071219.

Abstract

In this work, we develop single-mode fiber devices of an InAs/GaAs quantum dot (QD) by bonding a fiber array with large smooth facet, small core, and small numerical aperture to QDs in a distributed Bragg reflector planar cavity with vertical light extraction that prove mode overlap and efficient output for plug-and-play stable use and extensive study. Modulated Si doping as electron reservoir builds electric field and level tunnel coupling to reduce fine-structure splitting (FSS) and populate dominant XX and higher excitons XX+ and XXX. Epoxy package thermal stress induces light hole (lh) with various behaviors related to the donor field: lh h1 confined with more anisotropy shows an additional XZ line (its space to the traditional X lines reflects the field intensity) and larger FSS; lh h2 delocalized to wetting layer shows a fast h2-h1 decay; lh h2 confined shows D3h symmetric higher excitons with slow h2-h1 decay and more confined h1 to raise h1-h1 Coulomb interaction.

Keywords: InAs quantum dot; fine structure splitting; light hole level; photon pair; polarization correlation; single-mode fiber coupling; thermal stress.