Designs for λ=1.55 µm GaN-Based Intersubband Laser Active Region

A systematic design of a GaN/AlGaN active region for a three-level intersubband laser emitting in the near-infrared is presented. The proposed system is based on a double coupled quantum well structure with the laser level energy separation corresponding to 1.55 µm (ΔE32~800 meV), a wavelength important for optical communications. The lower laser level depopulates mostly via longitudinal optical phonon resonance, requiring ΔE21~90 meV. The model for scattering rate calculations, including many-body carrier screening effects, was first tested by comparison with recent experimental measurements in GaN/AlGaN quantum wells, and a very good agreement was obtained. It was then employed to calculate the gain coefficient, a commonly used figure of merit for three level laser systems, and this in turn allowed the optimal structural parameters of GaN/AlGaN quantum well to be found.