Towards terahertz-to-visible photon upconversion with single quantum dots-integrated nanoresonator

Abstract

Terahertz (THz) radiation offers a range of compelling applications such as virus sensing, nondestructive testing, vibrational spectroscopy of molecules, and wireless communication. Despite of its importance, its applications are limited by lack of THz detectors with high sensitivity, and broadband operation. In recent study, it was shown that quantum dots (QDs) exhibiting THz-driven luminescence via interdot charge transfer can offer a possible THz detection mechanism. Without accompanying external charge transport, THz-driven EL suggests field assisted charge generation and transport mechanisms between multiple QDs. In this thesis, without using multiple QDs, I demonstrate THz-to-visible photon upconversion in a single quantum dot regime by using sub-30 nm gap nanoresonator with CdSe/ZnS core-shell QD. Analyzing THz-field distribution and calculating tunneling currents from the metal layer to QDs using Fowler-Nordheim charge tunneling model, I was able to conclude the dynamics of charge transport of QDs inside the nanogap. This study on THz- driven luminescence indicates that achieving upconversion from THz to 1.5 𝜇𝑚 might also be possible by changing CdSe/ZnS QDs into suitable QDs that emit photons in the 1.5 𝜇𝑚 range. Consequently, this research could pave a way to developing THz (6G) to telecommunication (1.5 𝜇𝑚) wavelength upconversion device for upcoming telecommunication applications.