  InAs semiconductor quantum dots (QDs) emitting in the near infrared are
promising platforms for on-demand single-photon sources and spin-photon
interfaces. However, the realization of quantum-photonic nanodevices emitting
in the second and third telecom windows with similar performance remains an
open challenge. Here, we report an optimized heterostructure design for QDs
emitting in the O- and C-bands grown by means of molecular beam epitaxy. The
InAs QDs are grown on compositionally graded InGaAs buffers, which act as
virtual substrates, and are embedded in mostly relaxed active regions.
Reciprocal space maps of the indium profiles and optical absorption spectra are
used to optimize In0.22Ga0.78As and In0.30Ga0.70As active regions, accounting
for the chosen indium grading profile. This approach results in a tunable QD
photoluminescence (PL) emission from 1200 up to 1600 nm. Power and polarization
dependent micro-PL measurements performed at 4 K reveal exciton-biexciton
complexes from quantum dots emitting in the telecom O- and C-bands. The
presented study establishes a flexible platform that can be an essential
component for advanced photonic devices based on InAs/GaAs that serve as
building blocks for future quantum networks.
