Loss-driven topological transitions in lasing

TL;DR

This paper demonstrates experimentally and theoretically how tuning the scale of a hexamer plasmonic lattice induces topological transitions in lasing modes, driven by loss and characterized by changes in topological charge and mode quality.

Contribution

It introduces a novel loss-driven topological transition in plasmonic lasing modes, linking mode quality, topological charge, and lattice scale in a unified framework.

Findings

Lasing occurs in a hexamer plasmonic lattice with polarization winding changes.

Lasing modes are identified as quasi-BICs with topological charges 0, 1, or 2.

Mode Q-factors depend on lattice scale, with higher Q modes lasing.

Abstract

We experimentally observe lasing in a hexamer plasmonic lattice and find that when tuning the scale of the unit cell, the polarization winding of the emission changes. By a theoretical analysis we identify the lasing modes as quasi bound states in continuum (quasi-BICs) of topological charges of zero, one or two. A T-matrix simulation of the structure reveals that the mode quality(Q)-factors depend on the scale of the unit cell, with highest-Q modes favored by lasing. The system thus shows a loss-driven transition between lasing in modes of trivial and high-order topological charge.