Single quantum emitters such as epitaxial quantum dots are integral components of quantum light sources, such as single-photon and entangled-photon pair sources. Quantum dot sources can simultaneously achieve high brightness and high purity due to their high radiative efficiency and anharmonic energy level structure. However, to realize high effective brightness for downstream applications, it can be important that the quantum dot emission be efficiently coupled to an optical fiber. In practice, this can be challenging because nanophotonic geometries, which are often used to enhance the quantum dot emission and extract it from the surrounding semiconductor environment, do not always produce emission patterns that are amenable for such fiber coupling.
In a recent paper, we demonstrate a flexible approach for addressing this challenge, based on a 3D printing technique called direct laser writing (DLW). We show how polymer waveguides can be fabricated on the surface of devices containing epitaxial quantum dots, and how the quantum dot emission is naturally coupled to the polymer waveguide mode, whose spatial distribution is naturally matched to that of an optical fiber. We show this both for waveguides fabricated on unpatterned quantum dot material and for geometries containing metallic nanorings, which have previously been used to enhance quantum dot emission. Going forward, we anticipate that these 3D-printed structure can be flexibly incorporated on various nanophotonic geometries. This will enable the enhanced light-matter interaction provided by typical top-down fabricated devices (such as nanophotonic cavities) to be augmented by effective funneling of quantum dot emission provided by the 3D-printed polymer waveguides.
This work is part of special collection on 'Recent Advances in Photonic Quantum Technologies.'
Ref: Direct‐Laser‐Written Polymer Nanowire Waveguides for Broadband Single Photon Collection from Epitaxial Quantum Dots into a Gaussian‐like Mode, E. F. Perez, C. Haws, M. Davanco, J. Song, L. Sapienza, and K. Srinivasan, Advanced Quantum Technologies, 2300149, (2023)