A large-scale single-mode array laser based on a topological edge mode

TL;DR

This paper theoretically analyzes a large-scale topological edge mode laser, demonstrating conditions for stable single-mode operation in a 100-resonator array, and assesses robustness against disorder and long-range interactions.

Contribution

It introduces a model for large-scale topological lasers with hundreds of resonators, evaluating stability and robustness, advancing the development of high-power single-mode topological lasers.

Findings

Threshold gain difference of about 2 cm$^{-1}$ for stable lasing

Stronger coupling and lower losses improve stability

Robustness against disorders and long-range interactions

Abstract

Topological lasers have been intensively investigated as a strong candidate for robust single-mode lasers. A typical topological laser employs a single-mode topological edge state, which appears deterministically in a designed topological bandgap and exhibits robustness to disorder. These properties seem to be highly attractive in pursuit of high power lasers capable of single mode operation. In this paper, we theoretically analyze a large-scale single-mode laser based on a topological edge state. We consider a sizable array laser consisting of a few hundreds of site resonators, which support a single topological edge mode broadly distributed among the resonators. We build a basic model describing the laser using the tight binding approximation and evaluate the stability of single mode lasing based on the threshold gain difference $\Delta\alpha$ between the first-lasing edge mode and the second-lasing competing bulk mode. Our calculations demonstrate that stronger couplings between the cavities and lower losses are advantageous for achieving stable operation of the device. When assuming an average coupling of 100 cm$^{-1}$ between site resonators and other realistic parameters, the threshold gain difference $\Delta\alpha$ can reach about 2 cm$^{-1}$, which would be sufficient for stable single mode lasing using a conventional semiconductor laser architecture. We also consider the effects of possible disorders and long-range interactions to assess the robustness of the laser under non-ideal situations. These results lay the groundwork for developing single-mode high-power topological lasers.