Photonic Jet by a Near-Unity-Refractive-Index Sphere on a Dielectric Substrate with High Index Contrast

Photonic jets are normally generated in transmission mode and are represented as a spatially localized high-intensity region on the shadow side of a particle-lens, with a background to medium refractive index contrast of 1.3-1.7 while illuminated by a plane wave. Here, a photonic jet is discovered in the opposing plane wave propagation direction and lies in the area in the upper boundary of a near-unity refractive index sphere on a high refractive index dielectric substrate. The redistribution of the power flow is inhibited during the reflected wave passing the near-unity refractive index sphere. This has led to a unique effect on the focus position and shape of the produced photonic jet in reflection mode which can be maximally maintained near the sphere regardless of the modulation of the refractive index for the dielectric substrate material.