Revealing the invariance of vectorial structured light in complex media

Optical aberrations place fundamental limits on the achievable resolution with focusing and imaging. In the context of structured light, optical imperfections and misalignments and perturbing media such as turbulent air, underwater and optical fibre distort the amplitude and phase of the light’s spatial pattern. Here we show that polarization inhomogeneity that defines vectorial structured light is immune to all such perturbations, provided they are unitary. As an example, we study the robustness of vector vortex beams propagating through highly aberrated systems, demonstrating that the inhomogeneous nature of polarization remains unaltered even as the medium itself changes. The unitary nature of the channel allows us to undo this change through a simple lossless operation. This approach paves the way to the versatile application of vectorial structured light, even through non-ideal optical systems, crucial in applications such as imaging and optical communication across noisy channels. Structured light is shown to be robust against unitary perturbations.