Electric and magnetic dipolar response of Germanium spheres: Interference effects, scattering anisotropy and optical forces

Thecoherentcombinationofelectricandmagneticresponsesisthebasisoftheelectro- magnetic behavior of new engineered metamaterials. The basic constituents of their meta-atoms usually have metallic character and consequently high absorption losses. Based on standard "Mie" scattering theory, we found that there is a wide window in the near-infrared (wavelengths 1t o 3μm), where light scattering by lossless submicrometer Ge spherical particles is fully described by their induced electric and magnetic dipoles. The interference between electric and magneticdipolarfieldsisshowntoleadtoanisotropicangulardistributionsofscatteredintensity, including zero backward and almost zero forward scattered intensities at specific wavelengths, which until recently was theoretically established only for hypothetically postulated magnetodi- electric spheres. Although the scattering cross section at zero backward or forward scattering is exactly the same, radiation pressure forces are a factor of 3 higher in the zero forward condition.