Experimental observation of vector geometric parametric instability
Phys. Rev. A 114, 043522 – Published 16 October, 2026
DOI: https://doi.org/10.1103/ttc3-gxnt
Abstract
We report an observation of vector geometric parametric instabilities (GPI) in a single-mode birefringent photonic crystal fiber. While GPI is typically associated with multimode dynamics in graded-index fibers, we show that the beating of two orthogonally polarized modes is sufficient to trigger the instability. The resulting sidebands arise from a quasi-phase-matched parametric process mediated by a longitudinal index grating induced by polarization-mode coupling. A simple model yields generalized phase-matching conditions in good agreement with experiments and simulations. These results establish GPI as a universal mechanism extending to single-mode nonlinear systems.
