Interferometric pump-probe characterization of the nonlocal response of optically transparent ion implanted polymers

► The non-local response of Si ion implanted PMMA is interferometrically characterized. ► The light-absorbing ion-implanted surface layer is examined in reflection geometry. ► Laser pump-probe technique reveals strong laser-induced thermooptic effect. ► The material in the near-surface region exhibits a large thermal non-linearity. ► A strongly expressed non-locality in the millimeter scale is found.