FAR-FIELD RADIATION OF PLANAR GAUSSIAN SOURCES AND COMPARISON WITH SOLUTIONS BASED ON THE PARABOLIC APPROXIMATION

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.