Room Temperature Fiber-Coupled single-photon devices based on Colloidal Quantum Dots and SiV centers in Back Excited Nanoantennas

TL;DR

This paper presents a novel room-temperature, fiber-coupled single-photon source using a hybrid nanoantenna that enables efficient back-excitation and direct fiber coupling, advancing on-chip quantum photonics integration.

Contribution

The work introduces a hybrid metal-dielectric bullseye nanoantenna design that allows for back-excitation and efficient photon collection from single emitters at room temperature.

Findings

Achieved ~70% collection efficiency at NA 0.5

Demonstrated coupling with colloidal quantum dots and SiV centers

Enabled direct fiber coupling without additional optics

Abstract

We demonstrate an important step towards on chip integration of single photon sources operating at room temperature fiber coupling of a directional quantum emitter with back-excitation. Directionality is achieved with a hybrid metal-dielectric bullseye antenna, while back-excitation is permitted by placement of the emitter at or in a sub-wavelength hole positioned at the bullseye center. Overall, the unique design enables a direct laser excitation from the back of the on-chip device and very efficient coupling of the highly collimated photon emission to either low numerical aperture (NA) free space optics or directly to an optical fiber from the front. To show the versatility of the concept, we fabricate devices containing either a colloidal quantum dot or a silicon-vacancy center containing nanodiamond, which are accurately coupled to the nano-antenna using two different nano-positioning methods. Both back-excited devices display front collection efficiencies of about 70 % at NAs as low as 0.5. Moreover, the combination of back-excitation with forward low-NA directionality enables direct coupling of the emitted photons into a proximal optical fiber without the need of any coupling optics, thereby facilitating and greatly simplifying future integration.