Twisted light from topological chiral exceptional points in a nanolaser array
Abstract
We propose and experimentally demonstrate an orbital angular momentum (OAM) nanolaser array arranged in a ring geometry on an InP-based photonic crystal membrane. The device realizes a non-Hermitian extension of the Rice-Mele model, featuring alternating coupling strengths and imaginary on-site detunings. This configuration supports a symmetry-protected zero mode stabilized by non-Hermitian particle-hole symmetry, which enforces a uniform phase shift between adjacent nanolasers, establishing a coherent phase winding around the array. By adjusting the gain/loss contrast in a parity-time (PT)-like pumping scheme, the system can be tuned to a chiral exceptional point, where energy flows unidirectionally between nanocavities despite their reciprocal coupling. This symmetry-enforced, directional tunneling leads to far-field emission carrying non-zero OAM, providing a direct signature of the phase-structured lasing mode. Our results demonstrate a robust and scalable strategy for engineering compact, phase-locked laser arrays with controllable angular momentum output, and open new avenues for structured light generation in integrated photonic platforms.
Cite
@article{arxiv.2512.09388,
title = {Twisted light from topological chiral exceptional points in a nanolaser array},
author = {Kaiwen Ji and Melissa Hedir and Qi Zhong and Ramy El-Ganainy and Alejandro M. Yacomotti and Li Ge},
journal= {arXiv preprint arXiv:2512.09388},
year = {2025}
}