Single-photon and polarization-entangled photon emission from InAs quantum dots in the telecom C-band

We report on the optical properties of recently developed telecom-wavelength quantum dots based on the GaAs material system. In order to achieve the InAs quantum dot wavelength shift towards the telecom C-band, strain-relaxation with the help of an InGaAs metamorphic buffer is realized. The general emission properties of the quantum dot ensemble and single dots is analyzed, containing analysis of lifetime measurements and fine-structure splitting investigations. Single-photon emission is verified for excitation in continuous wave and pulsed mode. The generation of polarization-entangled photon pairs via the biexciton-exciton radiative cascade is shown, even for increasing time windows and time delays.