Xd. Zeng et al., FAR-FIELD RADIATION OF PLANAR GAUSSIAN SOURCES AND COMPARISON WITH SOLUTIONS BASED ON THE PARABOLIC APPROXIMATION, Applied optics, 36(10), 1997, pp. 2042-2047
Previous research on the Gaussian beam was restricted in scope because
of the paraxial assumption. Based on a rigorous solution of the Helmh
oltz equation, the radiation properties of a Gaussian source are reexa
mined. The results are different from what previous paraxial theory pr
edicted. It is shown that the commonly used concept of the Gaussian be
am and the separability of the field distribution along the two transv
erse axes may be misleading in certain conditions. Furthermore the the
oretical upper limit on the beam divergence angle is shown to be 65.5
degrees. (C) 1997 Optical Society of America.