Photonic Hook Main Properties

Abstract

The study of accelerating Airy-family beams has made significant progress, not only in terms of numerical and experimental investigations but also in conjunction with many potential applications. However, the curvature of such beams (and hence their acceleration) is usually greater than the wavelength. Relatively recently, a new type of localized wave beam with subwavelength curvature, called the photonic hook (PH), was discovered. This photonic hook is a curved high-intensity focus by, for example, a wavelength-scaled dielectric cuboid topped with a wedge prism (Janus particle) illuminated by a plane wave – an interesting situation combines diffraction with prism refraction, which adds a newfound degree of simplicity. The difference between the phase velocity and the interference of the waves inside the particle causes the phenomenon of focus bending. It is important that in the PH, there is an inflexion where the curved beam changes its propagating direction. This property is not possessed by Airy-like beams family. Amazingly, the mesoscale dielectric Janus particle, with broken shape or refractive index symmetry or broken symmetry of illuminating wave, is used to generate the photonic hook – emerging from its shadow-side surface. Moreover – PH has unique features – the radius of curvature is less than the wavelength; this is the smallest curvature radius of electromagnetic waves ever reported today. Although the curved profile evokes a similarity with Airy beams, in contrast to Airy beams there are no curved sidelobes. In this chapter, we discussed the key properties of PH based on full-wave simulations confirmed by experimental research of a scale model. The principal possibility of exotic looped shape of localized field and photonic trajectories is also briefly discussed. Using the photonic hook, the resolution of optical scanning systems can be improved to develop optomechanical tweezers for moving nanoparticles, cells, bacteria, and viruses along curved paths and around transparent obstacles. These unique properties of photonic jets and hooks combine to afford important applications for low-loss waveguiding, subdiffraction-resolution nanopatterning, and nanolithography.