Abstract
The first aim of this paper is to make the connection between complex source method (CSM) and Plane Wave Spectrum (PWS) clear. As a consequence, the paper also presents the PWS of 2D complex beams which completes the description of these solutions. This fact allows us to give straightforward relations between beam parameters and spatial confinement in order to know how to model a typical laser beam as a complex beam, which is a desirable fact since such a solution fulfills the wave equation instead of the paraxial wave equation as typical Gaussian beams do.