Exciton fine-structure splitting of telecom-wavelength single quantum dots: Statistics and external strain tuning

In a charge-tunable device, we investigate the fine-structure splitting of neutral excitons in single long-wavelength (1.1 < λ < 1.3 μm) InGaAs quantum dots as a function of external uniaxial strain. Nominal fine-structure splittings between 16 and 136 μeV are measured and manipulated. We observe varied responses of the splitting to the external strain, including positive and negative tuning slopes, different tuning ranges, and linear and parabolic dependencies, indicating that these physical parameters depend strongly on the unique microscopic structure of the individual quantum dot. To better understand the experimental results, we apply a phenomenological model describing the exciton polarization and fine-structure splitting under uniaxial strain. The model predicts that, with an increased experimental strain tuning range, the fine structure can be effectively canceled for select telecom-wavelength dots using uniaxial strain. These results are promising for the generation of on-demand entangled photon pairs at telecom wavelengths.