Fiber-based unidirectional emission with enhanced extraction efficiency of a single quantum dot from an optimized structure

Abstract III-nitride materials play a significant role in adjusting the emission of quantum emitters. In quantum networks, photons are used as flying qubits, and Gallium nitride (GaN) semiconductor quantum dots (QDs) have shown powerful single photon emission characteristics. Due to the high refractive index contrast of the semiconductor quantum dots, the extraction efficiency is low. In this paper, we numerically simulate the unidirectional emission quantum dot of InGaN formed on the apex of a silver-coated GaN nano-pyramid structure using FDTD software, and the structure is optimized to form an enhancement of extraction efficiency at a wavelength of 520 nm, its extraction efficiency has been improved from 91.35% to 97.2%. Most of the extracted light from the quantum dots is directed to the bottom of the pyramid with high directivity and incident into the single-mode optical fiber. The new structure is expected to be applied to unidirectional, bright and high extraction efficiency quantum emitters in quantum communication systems.