Theory of chiral edge state lasing in a two-dimensional topological system

Understand

We theoretically study topological laser operation in a bosonic Harper-Hofstadter model featuring a saturable optical gain.

• Crucial consequences of the chirality of the lasing edge modes are highlighted, such as a sharp dependence of the lasing threshold on the geometrical shape of the amplifying region and the possibility of ultraslow relaxation times and of convectively unstable regimes.
• The different unstable regimes are characterized in terms of spatio-temporal structures sustained by noise and a strong amplification of a propagating probe beam is anticipated to occur in between the convective and the absolute (lasing) thresholds.
• The robustness of topological laser operation against static disorder is assessed.