InP-based single-photon sources operating at telecom C-band with increased extraction efficiency

TL;DR

This paper reports a highly efficient, telecom C-band single-photon source using InAs quantum dots embedded in InP, achieving record extraction efficiency suitable for quantum communication.

Contribution

It introduces a novel InP-based single-photon source with enhanced extraction efficiency at telecom wavelengths using a combined photonic structure.

Findings

Photon extraction efficiency of (13.3+/-2)% achieved

Emission wavelength around 1560 nm within telecom C-band

Quantum dots exhibit low multiphoton probability

Abstract

In this work we demonstrate a triggered single-photon source operating at the telecom C-band with photon extraction efficiency exceeding any reported values in this range. The non-classical light emission with low probability of the multiphoton events is realized with single InAs quantum dots (QDs) grown by molecular beam epitaxy and embedded directly in an InP matrix. Low QD spatial density on the order of 5x108 cm-2 to ~2x109 cm-2 and symmetric shape of these nanostructures together with spectral range of emission makes them relevant for quantum communication applications. The engineering of extraction efficiency is realized by combining a bottom distributed Bragg reflector consisting of 25 pairs of InP/In0.53Ga0.37Al0.1As layers and cylindrical photonic confinement structures. Realization of such technologically non-demanding approach even in a non-deterministic fashion results in photon extraction efficiency of (13.3+/-2)% into 0.4 numerical aperture detection optics at approx. 1560 nm emission wavelength, i.e., close to the center of the telecom C-band.