Edge diffraction effect on a photonic hook generated by a dielectric microbar

Dielectric particles with the dimensions of a few laser wavelengths (mesowavelength-scale) and broken symmetry of optical properties (shape and permittivity) can manipulate light on a subwavelength spatial scale and create a clearly curved, highly localized, and intense light beam—a photonic hook (PH). PH properties depend essentially on the result of the interference of secondary wave sources formed at the exit surface of the scattering particle and mainly on light diffraction at particle edges. Using full-wave numerical simulations, we study the peculiarities of PH formation by a commonly used rectangular microbar with asymmetric properties when one of the transverse spatial dimensions (specifically, along the wave polarization) is changed. We show that the influence of edge diffraction can cause PH intensity to change with increasing dielectric bar length and even distort its spatial shape. Our analysis demonstrates that this effect of edge diffraction on the PH parameters is significant as long as the bar thickness is less than about 10 λ . Particles of a greater extent can be formally considered as a flat 2D structure, yielding PH properties equivalent to those obtained from the full-wave 3D simulation.