PhD defence by Evangelos Dimopoulos

Title:  Electrically-driven Photonic Crystal Lasers

Supervisors
Principal supervisor: Professor Jesper Mørk, DTU Electro Denmark
Co-supervisor: Professor Kresten Yvind, DTU Electro Denmark 
Co-supervisor: Senior Researcher Yi Yu, DTU Electro Denmark

Evaluation Board
Associate Professor Peter Tidemand-Lichtenberg, DTU Electro, Denmark
Professor Johan-Peter Reithmaier, Universität Kassel, Germany
Professor Fabrice Raineri, Université Côte d’Azur, France

Master of the Ceremony
Senior Researcher Elizaveta Semenova, DTU Electro, Denmark

Abstract
The rising demand for integrated optical communication and data processing solutions is fueling the advancement of on-chip photonic components that are ultra-compact and energyefficient.

A critical element of this endeavor is the development of high-performance smallfootprint light sources that can be integrated onto silicon. Among various on-chip sources, heterogeneously-integrated photonic crystal lasers are gaining momentum as a promising solution for on-chip applications.

This thesis is focused on the demonstration and investigation of electrically-driven photonic crystal nanolasers based on the InP-on-Si platform. The properties of the photonic crystal laser cavities are investigated, focusing on the disorder- and doping-induced optical losses. The static and dynamic properties of the nanolasers are studied. Importantly, the current leakage was identified as the primary performance-limiting factor. Pushing for even greater miniaturization, lasers with ultra-small active regions were fabricated, achieving a sub-μA threshold current – the lowest laser threshold to date. The thesis concludes with the study of the Fano laser, a novel type of photonic crystal laser.