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 arerepresented as a spatially localized high-intensity region o n the shadow sideof a particle-lens, with a background to medium refractive index contrast of1.3–1.7 while illuminated by a plane wave. Here, a photonic jet is discoveredin the opposing plane wave propagation direction and lies in the area in theupper boundary of a near-unity refractive index sphere on a high refractiveindex dielectric substrate. The redistribution of the power flow is i nhibitedduring the reflected wave passing the near-unity refractive index sphere. Thishas led to a unique effect on the focus position and shape of the producedphotonic jet in reflection mode which can be maximally maintained near thesphere regardless of the modulation of the refractive index for the dielectricsubstrate material.