Narrow-waisted Gaussian beam discretization for short-pulse radiation fromone-dimensional large apertures

In this paper, we develop a Gabor-based Gaussian Beam (GB) algorithm for re presenting two-dimensional (2-D) radiation from finite aperture distributio ns with short-pulse excitation in the time domain (TD). The work extends pr evious results using 2-D frequency-domain (FD) narrow-waisted Gaussian beam s [1]. The FD algorithm evolves from the rigorous Kirchhoff integration ove r the aperture distribution, which is then parameterized via the discrete G abor basis and evaluated asymptotically for high frequencies to furnish the GB propagators to the observer. The TD results are obtained by Fourier inv ersion from the FD and yield pulsed beams (PB). We describe the resulting T D algorithm for several aperture distributions, ranging from simple linearl y phased (linear delay) to arbitrary time delay profiles; the latter accomm odate the important case of focusing TD aperture fields. For modulated puls es with Gaussian envelopes, we compute accurate closed form analytic soluti ons, which have been calibrated against numerical reference data. Our resul ts confirm that the previously established utility of the Gabor-based narro w-waisted FD-GB algorithm for radiation from distributed apertures [1] rema ins intact in the TD.