Fernandez-Corbaton I.,Institute of Nanotechnology |
Nanz S.,Institute For Theoretische Festkorperphysik |
Alaee R.,Institute For Theoretische Festkorperphysik |
Rockstuhl C.,Institute of Nanotechnology |
Rockstuhl C.,Institute For Theoretische Festkorperphysik
Optics Express | Year: 2015
The multipolar decomposition of current distributions is used in many branches of physics. Here, we obtain new exact expressions for the dipolar moments of a localized electric current distribution. The typical integrals for the dipole moments of electromagnetically small sources are recovered as the lowest order terms of the new expressions in a series expansion with respect to the size of the source. All the higher order terms can be easily obtained. We also provide exact and approximated expressions for dipoles that radiate a definite polarization handedness (helicity). Formally, the new exact expressions are only marginally more complex than their lowest order approximations. © 2015 Optical Society of America.