Inside view

For the first time, a microdisc laser capable of both up and down wavelength conversion has been demonstrated by IBM. Jens Hofrichter from IBM Research - Zurich tells us how this has advanced the silicon photonics field approaches for on-chip light sources, in particular using microdisc lasers as the workhorse. Our focus, and also the focus of TU Eindhoven, in the project is on the exploitation of these fascinating devices for on-chip optical signal processing. IMEC/Ghent University, with its extensive expertise in microdisc laser manufacturing, concentrated on the fabrication of the devices using the high-quality epitaxial material provided by CNRS/INL in Lyon. A key feature of the epi material that we used is the tunnel junction, which has good electrical properties and circumvents highly doped p-side contacts, which are the main contribution to absorption and thus to a low optical output power.