Determination of threshold lasing mode of a topological laser based on the Haldane model

• Main Author: Kumar, Suraj
• Other Authors: Chong Yidong
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2021
• Subjects: Science::Physics::Optics and light
• Online Access: https://hdl.handle.net/10356/148578
• Institution: Nanyang Technological University

This paper describes an attempt to obtain the threshold lasing mode for a topological laser based on the Haldane model. In general resonant cavity structures in lasers are designed to have a high quality factor, which makes them prone to loss due to disorder. Topological lasers work around this by having topologically protected transport along the edge states which have been shown to perform well even with disorder. The laser is characterized by a lattice of resonators and a Hamiltonian that resembles a Haldane Hamiltonian with a linear loss term and a non-linear saturable gain term. We study two lattices: a small one to understand the general behavior and a large one to obtain a threshold mode as an example. We attempt to obtain the threshold lasing mode and threshold gain strength at which the net power becomes zero. We do this by solving a generalized eigenvalue problem to obtain the minimum pump strength at which we have threshold lasing. We then plot these intensity distributions over the lattice and interpret the results.