Observations of near-zero linewidth enhancement factor in a quantum-well coupled quantum-dot laser

Abstract

Amplified spontaneous emission (ASE) measurements of a quantum-well coupled quantum-dot (QW–QD) laser are investigated in our experimental study. Fabry–Perot ASE spectrum taken below threshold of this device allows the extraction of gain, index of refraction change, and linewidth enhancement factor. Our experimental study includes continuous wave and pulsed measurements. The QW–QD laser consists of an auxiliary QW which assists in carrier collection while tunneling of carriers takes place from the well to the dot region. Our experimental analysis reveals a low linewidth enhancement factor of 0.15 over a flat spectrum for these GaAs–InGaAs–InAs QW–QD lasers.