Controlling complex III-V semiconductor microlasers
File(s)
Author(s)
Fischer, Anna
Type
Thesis
Abstract
Microscopic lasers are promising devices for a wide range of applications including optical data transmission, computing, sensing of molecules, and even biophotonic applications by insertion into living cells. In recent years, research into microcavities that go far beyond the standard Fabry-Perot (two opposite mirrors) type architecture has advanced rapidly. The aim of this thesis is the study of novel InP microlaser architectures, the underlying physical mechanisms, and their implementation in applications. In a first step to understand more complex systems, the coupling of two lasers formed by micron-sized InP hexagons is studied. When two of them are in close proximity, their modes couple, and it is explored how the interplay of light modes and illumination, defining the optical gain, leads to non-Hermitian modes, the formation of exceptional points, increased sensitivity, and enables switching applications. While coupled lasers can be tuned by illumination, coupling of many nanoparticles can lead to long-range effects, such as surface lattice resonances, where wavelengths are defined by the lattice spacing. Single-mode, large-area lasing in a hybrid photonic-plasmonic microlaser is demonstrated by placing a gold nanoparticle array on top of an InP slab waveguide. More complexity arises in structures where light can follow random paths. Light can travel in the edges of a network of connected InP waveguides and scatter at the connecting nodes, forming a plethora of modes by multiple scattering paths. These many spatially-distributed random lasing modes are highly sensitive to patterned illumination, making them ideal for physical machine learning processes. The developed network random laser system is capable of performing high-quality image processing enabling edge detection and image classification.
Version
Open Access
Date Issued
2024-07-03
Date Awarded
01/10/2024
License URL
Advisor
Sapienza, Riccardo
Moselund, Kirsten
Schmid, Heinz
Sponsor
European Commission
Grant Number
859841
Publisher Department
Physics
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)