Interférence et modulation spectrale

Abstract

It has been shown by Mandel that the spectral density shows a cosine modulation with relative amplitude 2(Ī1 Ī2)1/2γ12(0)/(Ī1 + Ī2) when the optical path difference is much longer than the coherence length in a quite general superposition experiment of two quasi-monochromatic, polarized, and partially coherent beams of light. It is shown here that this is equally true for path differences smaller or equal to the coherence length. This conclusion is reached by considering the properly defined visibility of the modulation of the spectral density. Both aspects of the modulation of the spectral density are considered: modulation as a function of path difference for a fixed frequency ν0 and modulation as a function of frequency for a fixed path difference cT0.