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Exploration of novel topological lasing modes: their robustness and dynamics

Wong, Stephan 2022. Exploration of novel topological lasing modes: their robustness and dynamics. PhD Thesis, Cardiff University.
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Recently, topological photonics has been proven to be an attractive framework for manipulating the light in an extraordinary way. For instance, photonic topological insulators can exhibit modes that are robust against some defects such as fabrication imperfections, deformations and sharp bendings in waveguides. This thesis extends previous works on topological lasers by proposing new topological lasing modes, analysing the dynamic behaviours of those modes and adopting new topological classification methods with the aim to realise high-performance laser devices. In particular, I will cover some of my recent contributions in the research field, especially on topological edge modes in kagome photonic crystals, semiconductor topological laser cavities, and non-Hermitian topological bulk modes, as well as on a proposed data-driven approach for topological classification in topological insulator lasers. I will start with an all-dielectric reciprocal topological insulator based on the geometry of a kagome lattice, where I demonstrated broadband and highly efficient unidirectional photonic edge mode propagation for sharp bendings conserving the local symmetry. These topological edge modes working at telecommunication wavelengths will be used to construct semiconductor laser cavities insensitive to defects. In the topological cavity, I will show that two different regimes coexist where additional Fabry-Pérot modes are present in addition to the topological lasing modes. Finally, I will show how non-Hermiticity can give rise to new topological states. In particular, I will look at so-called topological bulk modes that arise from asymmetric couplings. In contrast to the topological edge modes, they are delocalised over the bulk while still being topologically protected. The topological bulk modes have been achieved in a two-dimensional kagome lattice, with rhombus geometry, by introducing an imaginary gauge field. I will show the possibility to achieve temporally stable, phase-locked broad area topological lasers in two-dimensional lattices. Further, I will propose a data-driven method in order to find new topological phases via reverse engineering.

Item Type: Thesis (PhD)
Date Type: Completion
Status: Unpublished
Schools: Physics and Astronomy
Subjects: Q Science > QC Physics
Uncontrolled Keywords: topological photonics, laser
Funders: Cardiff University
Date of First Compliant Deposit: 30 August 2022
Last Modified: 30 Aug 2022 09:40

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