Transition from near-field to far-field region in nondiffractive beams

The generation of nondiffractive beams has been widely investigated in recent years due to their intriguing properties in terms of focusing, limited diffraction, and self-healing features. However, the behavior of such beams as they transition from the near-field to the far-field region has been overlooked. For this reason, the evolution of a Bessel-beam distribution from near- to far-field distances from the aperture plane has been investigated in this work. In particular, a resonant Bessel-beam launcher is here studied through a leaky-wave approach, providing the first fully vectorial analysis of a Bessel-beam near-to far-field transition.