title: Far-field radiation of planar Gaussian sources and comparison with solutions based on the parabolic approximation.
abstract: Previous research on the Gaussian beam was restricted in scope because of the paraxial assumption. Based on a rigorous solution of the Helmholtz equation, the radiation properties of a Gaussian source are reexamined. The results are different from what previous paraxial theory predicted. It is shown that the commonly used concept of the Gaussian beam and the separability of the field distribution along the two transverse axes may be misleading in certain conditions. Furthermore the theoretical upper limit on the beam divergence angle is shown to be 65.5 degrees .
authors.forename: X
authors.initials: X
authors.lastname: Zeng
authors.forename: C
authors.initials: C
authors.lastname: Liang
authors.forename: Y
authors.initials: Y
authors.lastname: An