Long-Wavelength Multilayered InAs Quantum Dot Lasers

Abstract

In this paper, we describe the dependence of dot density per layer on laser performance for long-wavelength multilayered InAs quantum dot (QD) lasers. On the basis of the investigation of the undoped 12-QD lasers with a dot density per layer in the range of (1.4–3.0)×1010 cm-2, we found that lasers with nearly identical photoluminescence (PL) intensities and full width at half maximum (FWHM) have almost the same relationships between the threshold current density (Jth) and the mirror loss as well as nearly the same maximum mirror losses from which lasers can oscillate from the ground state (GS). Although the PL intensities increase to 2–30 times higher than those of the undoped lasers by applying p-type modulation doping, the maximum mirror losses from which lasers can oscillate from the GS are nearly the same as those of undoped lasers. These are probably due to the fact that the Jth of dot lasers fabricated by the self-assembly method are strongly dominated by the gain width, which is governed by the nonuniformity of QDs.