Direct observation of photonic jets and corresponding backscattering enhancement at microwave frequencies

We report the direct observation of photonic nanojets that emerged from the shadow side of a dielectric cylinder illuminated by plane waves in the microwave frequencies (8–13 GHz). Using our recently developed two-dimensional spatial field mapping system, we carried out a point-by-point measurement of both the phase and intensity of spatial electric field distribution inside and around scattering dielectric cylinders. The direct electric field maps confirm the subwavelength waist of the photonic jet. In addition, we also confirmed the superbackscattering enhancement induced by the presence of a particle much smaller than the initial focusing cylinder within the photonic jet.