PhD defence by Søren Engelberth Hansen

Abstract

Spectrometers on a chip present an opportunity to make sensors smaller and lower cost than with present-day technologies. This opens up possibilities for various applications such as portable medical diagnostics, environmental monitoring, assessing material strength, evaluating food quality, and more. In collaboration with industry partners in the NEXUS project, our primary goal is to develop chip-scale spectrometers specifically designed for analyzing protein, fat, and moisture levels in milk. Making scalable and affordable chip-scale spectrometers can contribute to improving monitoring and quality control in the dairy industry — assisting in better products, more efficient production, and reduction of food waste on a global scale.

This Ph.D. project focuses on advancing photonic circuit components tailored for chip-scale spectrometer development. The main goals include designing and refining critical components like grating couplers, power splitters, and lenses, utilizing both traditional design methods and advanced inverse design through topology optimization.

A key aspect of the research is the development of photonic packaging solutions. Given the complexities of integrating small-scale spectrometer chips into existing systems in an affordable and scalable manner, the project investigates various packaging designs and strategies. This includes making prototypes with fiber arrays for coupling light using conventional practices as well as a chip-scale packaging and encapsulation concept - featuring backside coupling with inverse-designed grating couplers and metalenses.

The research advancements in photonic circuitry and coupling strategies can drive chip-scale spectrometers towards market-ready applications and benefit other applications, as the various components are building blocks for many nanophotonic devices.

Supervisors

• Principal supervisor: Professor Søren Stobbe, DTU Electro, Denmark
• Co-supervisor: Associate Professor Rasmus Ellebæk Christiansen, DTU Electro, Denmark
• Co-supervisor: Postdoc Guillermo Arregui, EPFL, Switzerland

Evaluation Board

• Professor Niels Gregersen, DTU Electro, Denmark
• Professor Kristinn Björgvin Gylfason, KTH, Sweden
• Associate Professor Jörg Helge Müller, Niels Bohr Institute, Copenhagen University, Denmark

Master of the Ceremony

• Senior Researcher Mikkel Heuck, DTU Electro, Denmark