Gain and absorption characteristics of bilayer quantum dot lasers beyond 1.3 μm

In this paper we report on the multi-section gain and absorption analysis of strain engineered molecular beam epitaxy (MBE) grown GaAs and InGaAs capped bilayers. The InGaAs capped bilayer quantum dot (QD) lasers extends the room temperature lasing wavelength to 1.45 μm. The spectral measurement of gain demonstrates that net modal gain is achieved beyond 1.5 μm at room temperature. Analysis of the temperature and current density dependence gain characteristics of a GaAs capped bilayer sample indicate that the temperature sensitivity of threshold current around room temperature is due to phonon assisted thermal escape of carriers from the QDs.