An experimental setup for room temperature waveguide spectroscopy of self-assembled quantum dots

In this work we present the realization of an experimental setup to measure the absorption spectrum of low planar density active media in nanoscale devices. The experimental technique employs in-plane light transmission through a waveguide embedding the active medium. It has been applied to the investigation of the room temperature optical properties of low density self-assembled InGaAs/GaAs quantum dots (QDs), emitting around 1.3 mu m. A detailed analysis of the obtained spectra showed the occurrence of a Stokes shift which after inspection turned out to be related to the thermally activated carrier migration throughout the QD ensemble.