Aarhus University Seal / Aarhus Universitets segl

Microwaves from an Optical Chip – Towards Faster Data Connections

PhD defence, Friday 27 September 2019. Lars Nielsen.

2019.09.27 | Sunitha Satkunam

Lars Nielsen

A microscope image of a PIC, which holds 16 mode-locked lasers. A mode-locked laser is a subpart of the photonic microwave oscillator. The total size of the PIC is 4x4.6 mm2.

During his studies, Lars Nielsen has investigated the possibilities of downscaling a stable microwave oscillator. Compact microwave oscillators, such as quartz-based oscillators, already exist, but they are limited in performance - this limits the number of applications. The fabrication of optical chips, the so-called photonic integrated circuits (PICs), has evolved significantly during the recent years, and is now established as a mature technology. On a PIC, which is typically around a few (tens of) mm2 in size, light is generated and manipulated to mimic a specific functionality. This could be directional control of the light in lidars, gas spectroscopy, and the encoding of bits on light from a laser.

Lars Nielsen has utilized the fundamental advantages of PICs, such as low optical loss and compactness, to downscale the size of already existing stable microwave oscillators – the so-called photonic microwave oscillators. He has identified different issues that arise when doing this, and proposed different solutions to these, such as an implementation of a chip-scale laser that is expected to be insensitive to light reflections. Moreover, he has analyzed the perspectives of a specific PIC platform, and showed that the implementation of a chip-scale photonic microwave oscillator is feasible.  However, to achieve state of the art performance, he also shows that a significant optimization of several components is needed. His results are the first on the way to a compact high quality microwave oscillator, which can benefit applications such as wireless data connections and Doppler radars.

The PhD degree was completed at the Department of Engineering, Science and Technology, Aarhus University.

This résumé was prepared by the PhD student.

Time: Friday 27 September 2019 at 13:00
Place: Building 5125, room 408 , Finlandsgade 22, Aarhus N,, Department of Engineering, Aarhus University
Title of PhD thesis: Microwave Photonic Oscillators Integrated on an Optical Chip
Contact information: Lars Nielsen, e-mail: ln@eng.au.dk, tel.: +4593508475/+4522412687
Members of the assessment committee:
Professor Daan Lenstra, Department of Electrical Engineering, Eindhoven University of Technology, The Netherlands
Professor Kresten Yvind, Department of Photonics Engineering, Technical University of Denmark, Denmark
Professor Preben Kidmose (chair), Department of Engineering, Aarhus University
Main supervisor:
Associate Professor Martijn Heck, Department of Engineering, Aarhus University
Language: The PhD dissertation will be defended in English

The defence is public.
The PhD thesis is available for reading at the Graduate School of Science and Technology/GSST, Ny Munkegade 120, building 1521, 8000 Aarhus C.

PhD defence
12183 / i43