PhD defence by Asbjørn Moltke

Supervisors
Principal supervisor: Professor Ole Bang, Department of Electrical and Photonics Engineering, DTU, Denmark
Co-supervisor: Researcher Christian Rosenberg Petersen, Department of Electrical and Photonics Engineering, DTU, Denmark
Co-supervisor: Ass. Prof. Christos Markos, Department of Electrical and Photonics Engineering, DTU, Denmark

Evaluation Board
Examiner: Professor, John C. Travers, Heriot-Watt Uni, Edinburgh, UK
Examiner: Ass. Professor, Michael H. Frosz, Max Plank Inst, Erlangen, Germany

Chairman
Professor Peter Uhd Jepsen, Department of Electrical and Photonics Engineering, DTU,

Master of the Ceremony
Senior Researcher Jakob Janting

Abstract
Lasers are everywhere, and are an essential component in all types of equipment, ranging from household equipment to the most advanced research facilities. Surely, to cover so many areas they cannot all be the same; and indeed, they come in all shapes and sizes, often characterised by their colour, the wavelength. In fact, the laser precision with which they are monochromatic is in part what gives the accuracy. Say you need a different colour, or even multiple colours, what then? – do you have to buy a new every time? Luckily not! There is a white laser, the supercontinuum sources, which has laser precision and all colours at once.

Well…, not all. Ultra-violet (UV) lasers remains a challenge. Traditional lasers lack suitable materials to work in the UV, and the supercontinuum sources covering the visible colours struggle to reach the UV-colours. Those that do, the UV supercontinuum sources, struggle to deliver all the visible colours. This work presents a novel approach to UV supercontinuum sources, bringing UV supercontinuum sources one-step closer to their visible namesake. Demonstrating its capability on a high precision measuring technique for nanostructured samples, Scatterometry, goes to show that the technology is maturing – perhaps ready to leave its nest in our labs, and help tackling daily challenges in other labs, or even the real world.