Definitions of Coherence Time, Coherence Area and Coherence Volume for Superposed Coherent and Chaotic Radiation

Definitions of the coherence time, coherence area and coherence volume are proposed for superposed coherent and chaotic radiation, such as laser radiation above the threshold, on the basis of the photon statistics of the radiation. Such definitions may contribute to a unified judgment of the coherence properties of the radiation in any order, while the definitions usually used are connected with interferometric measurements of the second-order coherence properties. A close relationship to the definitions proposed earlier in the literature for chaotic radiation is shown.