The geometrical theory of free-space radiative energy transfer is extended to include the case of partially coherent, radiating sources. For quasi-homogeneous sources an explicit formula for the generalized specific intensity that applies both inside and outside the source is given. Such sources are shown to radiate mainly according to classical theory, and the spectral energy flux density is given by the same expression everywhere. Outside the source only nonevanescent, traveling waves exist, and both the energy density function and the cross-spectral density function of the field are explicitly expressed in terms of the generalized specific intensity. Within a quasi-homogeneous-wave model all the energy expressions then reduce to those of classical theory. Inside the source there are also evanescent, standing waves, but their contributions to the cross-spectral density function and the energy expressions are shown to be negligible.
© 1992 Optical Society of America
Original Manuscript: June 28, 1991
Revised Manuscript: October 23, 1991
Manuscript Accepted: January 24, 1992
Published: September 1, 1992
Hans M. Pedersen, "Geometrical theory of fields radiated from three-dimensional, quasi-homogeneous sources," J. Opt. Soc. Am. A 9, 1626-1632 (1992)