2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/85749Motivated by recent experimental work by Folkenberg et al. we consider the effect of weak disorder in the air-hole lattice of small-core photonic crystal fibers. We find that the broken symmetry leads to higher-order modes which have generic intensity distributions resembling those found in standard fibers with elliptical cores. This explains why recently reported experimental higher-order mode profiles appear very different from those calculated numerically for ideal photonic crystal fibers with inversion and six-fold rotational symmetry. The splitting of the four higher-order modes into two groups fully correlates with the observation that these modes have different cut-offs.6 pages including 4 figures. To appear in J. Opt. A: Pure Appl. OptOpticstext