Telecom wavelength single quantum dots with very small excitonic fine-structure splitting

TL;DR

This paper demonstrates the growth of symmetric InAs/InP quantum dots emitting at telecom wavelengths with ultra-small fine-structure splitting, showing enhanced photoluminescence and clear excitonic features suitable for quantum communication.

Contribution

It reports the first systematic growth and characterization of telecom wavelength quantum dots with ultra-small fine-structure splitting and high emission quality.

Findings

Achieved ~2 μeV excitonic fine-structure splitting.

Observed tenfold PL intensity enhancement.

Resolved exciton, biexciton, and dark exciton emissions.

Abstract

We report on molecular beam epitaxy growth of symmetric InAs/InP quantum dots (QDs) emitting at telecom C-band (1.55 $\mu$m) with ultra-small excitonic fine-structure splitting of ~2 $\mu$eV. The QDs are grown on distributed Bragg reflector and systematically characterized by micro-photoluminescence ($\mu$-PL) measurements. One order of magnitude of QD PL intensity enhancement is observed in comparison with as-grown samples. Combination of power-dependent and polarization-resolved measurements reveal background-free exciton, biexciton and dark exciton emission with resolution-limited linewidth below 35 $\mu$eV and biexciton binding energy of ~1 meV. The results are confirmed by statistical measurements of about 20 QDs.