PhD defence by Lars Emil Gutt

Title: Integrated Optical Time Lenses for Passive Optical Networks

Supervisors
Principal supervisor: Professor Leif Katsuo Oxenløwe, Department of Electrical and Photonics Engineering, DTU, Denmark
Co-supervisor: Senior Researcher Peter Girouard, Department of Electrical and Photonics Engineering, DTU, Denmark

Evaluation Board
Senior Researcher Mikkel Heuck, Department of Electrical and Photonics Engineering, DTU, Denmark
Professor Bart Kuyken, Ghent University, Belgium
Associate Professor Nicolas Volet, Aarhus University, Denmark

Master of the Ceremony
Associate Professor Michael Galili, Department of Electrical and Photonics Engineering, DTU, Denmark

Abstract
As more and more consumers gain access to high-speed internet and as each of these consumers require larger bandwidths, the energy consumption of the internet is rising exponentially. This rise in energy consumption in turn corresponds to the internet being a driver of ever-increasing emissions of greenhouse gases. Passive optical networks (PONs) are an integral part of the physical infrastructure of the internet, where they act as last mile networks. Unfortunately, this type of network is inherently energy inefficient due to how the data signals are divided to the respective receivers in the network. Based on a type of device called an optical time lens, a new type of network called a Lens-PON can be created, which potentially allows for much more efficient transmission of data. At its present stage, Lens-PONs require bulky and inefficient devices constructed using large amounts of optical fiber. Our goal is to integrate the main parts of a Lens-PON on photonic integrated chips, which would massively reduce its size and improve its efficiency to a point where it becomes a viable alternative to traditional PONs. This PhD thesis details the advance that have been made towards realizing a fully integrated Lens-PON, mainly focusing on methods of lowering the optical losses of the circuit needed for this.