Structured light beams constituted of incoming and outgoing waves

In the present work, we demonstrate that structured light beams are constituted by two traveling waves which transverse components are in opposite directions, that is, incoming and outgoing from the axis of propagation. These waves result from the complex sum of the two fundamental solutions of the transverse component of the spatial wave equation. After a partial obstruction of the beam, the incoming and outgoing waves can be easily observed during the self-healing process, providing a simple explanation of the phenomenon. Incoming and outgoing waves in Laguerre-Gauss beams are investigated analytically, numerically and experimentally. The proposed way to describe light beams might offer new insights into the phenomenon of diffraction.