Abstract
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 Δα 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 Δα 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.
Highlights
High power semiconductor lasers have been of great interest to the industrial market for their wide applications, prompting enormous efforts in improving their performance
We investigated a fundamental model of broadlydistributed single-mode topological edge mode laser in the tight-binding approximation
We considered a sizable system consisted of 201 site resonators that potentially lead to a 10W-class laser by assuming that each resonator delivers ∼100 mW output power
Summary
High power semiconductor lasers have been of great interest to the industrial market for their wide applications, prompting enormous efforts in improving their performance. The designs of these structures tend to be highly delicate and sometimes significantly complicate the fabrication process of the device Such complexity in design may motivate to find a simpler scheme that enables high power single mode semiconductor lasers. There have been limited discussions for the application of topological edge modes for high power lasers by significantly expanding the mode profile in space. We consider a sizable array laser that supports a single zero-dimensional topological edge state distributed over a few hundreds of site resonators. We formulate this model based on the tight binding approximation. We deduce a possible direction of the device design for robust single mode lasing with high output power. We believe our results pave a new path toward single mode high power lasers based on topological photonics
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