Coupled-cavity lasers are generally reduced by a plane wave treatment of th
e various mirror pairs, even though laser optics is rather based on beams h
aving a finite lateral extent. We show that this method is questionable by
investigating the reflectivity and transmission of a Fabry-Perot Interferom
eter when the input is a TEM,,, TEM,,, and TEM,, beams, in the multi-freque
ncy case. (C) 2000 Published by Elsevier Science B.V.