Telecommunication Wavelength Single Photon Sources with Plasmonic Nanostructures

Abstract

Quantum networks need bright, fiber-compatible quantum light sources that work at room temperature; existing approaches are either probabilistic (bulk SPDC) or fast but cryogenic. This dissertation advances a plasmonic route to telecom-band quantum photonics in three parts. First, I show that solution-processed PbS/CdS core–shell quantum dots, when integrated into film-coupled plasmonic nanogap cavities, become ultrafast and stable single-photon emitters in the C-band: radiative lifetimes are shortened to 65 ps with directional out-coupling, clear antibunching g^((2) ) (0)<0., and single-photon rates up to ~12.6 MHz at 1550 nm. Second, I propose and validate a deterministic placement methodology—electron-beam-defined nanoholes for capillary assembly of emitters followed by aligned top-metal patterning—that yields ordered arrays and hotspot-registered cavities with tens-of-nanometers alignment and preliminary lifetime/Purcell enhancement maps. Third, I realize nanoscale SPDC by incorporating ultrathin (~4 nm) TiO2 nonlinear films into plasmonic metasurfaces and single nanopatch cavities, demonstrating polarization-selective photon-pair generation with cavity-defined signal/idler wavelengths (~1.1 µm/1.55 µm), linear pump scaling, and measurable signal–idler time correlations alongside bunching in individual channels. Together these results establish plasmon-enhanced, telecom-band quantum light sources that operate at room temperature and are compatible with on-chip integration; ongoing work targets higher coincidence-to-accidental ratios and fully heralded operation, en route to Bell-state generation on a nanoscale platform.