Petermann factor divergence at exceptional points

Ascertain whether the Petermann factor diverges at exceptional points in non-Hermitian photonic resonant systems.

Background

The Petermann factor quantifies mode non-orthogonality and is linked to excess noise and sensitivity in non-Hermitian resonators. Its behavior near EPs has important implications for sensing and lasing systems that exploit EP physics.

In the paper’s introduction, the authors explicitly identify the status of Petermann factor divergence at EPs as an open problem, highlighting ongoing uncertainty in the field that their sensitivity-computation framework helps to investigate but does not resolve.