DBR based cavities in strained Ge microbridge on 200 mm Germanium-On-Insulator (GeOI) substrates: towards CMOS compatible laser applications

Germanium based lasers are envisioned as potential sources in silicon photonics since its first demonstration using highly doped but only marginally strained layers [1]. To reach a direct band-gap in the Ge and thus a more efficient gain–medium, high tensile strain is currently investigated by several research groups [2-3]. High uniaxial tensile strain can be injected in Ge by membrane structuration [4]. In this work, we present such highly strained Ge micro-bridges embedded in an optical cavity fabricated from 200 mm Germanium-On-Insulator (GeOI) substrates. The substrates are made by Smart-Cut™ technology and are developed for this purpose to enhance the rupture strain limit of the germanium. Laser design modelling, membrane processing, and our first experimental results will be presented in detail.