Dr O’Callaghan received his PhD in 2002 from the Department of Physics in University College Cork under the topic of Spatial Coherence in Gain Profiled Semiconductor Lasers. He worked in the department of optoelectronics in Ulm, Germany, developing thermal management methods for VCSELs before returning to his native city of Cork to work at the Tyndall National Institute as a staff scientist. Since then, he has been involved in a wide range of projects from developing high brightness semiconductor lasers for photodynamic therapy to telecoms-based photonics devices, such as Mach-Zehnder modulators and etched facet tuneable lasers. For the past ten years, his research has mainly focused on the development of photonics-based devices for micro transfer printing, their integration into photonic integrated circuits, and the packaging rules required to standardise the adoption and integration of this technology in photonic integrated circuits.