The irradiance of an atomic dipole transition -screened at microscopic distances from its origin- reveals
interesting details not always evident when dealing with light phenomena. The basis of this investigations are pure
classical. The HERTZ vector- formalism was used (BORN & WOLF). The special features of the electrodynamics
radiation behaviour of such an atomic transition solely became evident when generally made disregards were suspended.
However, the complexity of the originating equations forced one to treat the problem numerically. All computations were
done due to a dipole elongation of 0,1Å with an oscillation frequency corresponding to the YAG-laser wavelength, λY = 1,064 μm. Strikingly a Fourier analysis of the irradiance (Poynting vector) doesn't replicate this frequency, moreover, it reveals harmonics. Up to ~ 0,1 μm the fourth harmonic dominates, second harmonic is also appearing albeit at a minor amount.
Beyond 0,1 μm fourth and second harmonic exchange their appearance. Up to 100nm from the dipole centre sixth and
eighth harmonics are also present but at minor strengths.
Outside the source centre the optical field is perceived as light wave and practically, instead of the presumed YAG
wavelength, we measure double this frequency, namely green light.
At distances below 0,1 μm the fourth harmonic prevails being capable of performing a two photon absorption.