Towards 1.55 µm GaAs based lasers using quantum dot bilayers

This paper reports on the use of quantum dot (QD) bilayers to extend the operating wavelength of GaAs based devices to 1.55 μm. We utilise a number of electrical and spectroscopic techniques to show how QD bilayers allow the realization of high quality laser devices beyond 1.3 μm. The introduction of InGaAs capping to the bilayers allows the further extension of the ground-state peak to 1.45 μm. Under high current densities carrier-carrier interaction broadens this peak, giving positive net modal gain in the 1.55 μm region.