Specular-reflection photonic hook generation under oblique illumination of a super-contrast dielectric microparticle

Abstract

The possibility of overcoming the critical condition for localized photonic nanojet (PNJ) upon plane optical wave diffraction at mesoscale dielectric particle, which is commonly known as ‘the refractive index contrast is less than two’, was recently reported in our works. To this end, the novel geometrical scheme of PNJ generation in ‘reflection mode’ was proposed recently based on a super-contrast microparticle placed near a flat mirror. In this paper, through the numerical FDTD calculations of optical near-field structure of 2D and 3D dielectric microparticles (cylinder, sphere) we extend our considerations to the case of oblique particle-at-mirror illumination and present new physical phenomena arising in the considered photonic geometry. Specifically, we report on the generation of a quasi-retrograde PNJ which follows the inclined particle illumination and propose a new principle for obtaining a curvilinear photonic flux in the form of a ‘specular-reflection photonic hook’ (s-Hook) in the opposite to the illuminated wavevector direction. Two different regimes of s-Hook formation are analyzed by changing the direction of light incidence on a dielectric particle and by flat mirror inclination. Self-bending property of PNJ at oblique illumination is investigated.