A double-Gaussian model and the Schmidt modes are found for the biphoton wave function characterizing spontaneous parametric down-conversion with the degenerate collinear phase-matching of the type I and with a pulsed pump. The obtained results are valid for all durations of the pump pulses, short, long and intermediately long.
@article{arxiv.0906.3273,
title = {Gaussian modeling and Schmidt modes of SPDS biphoton states},
author = {M. V. Fedorov and Yu. M. Mikhailova and P. A. Volkov},
journal= {arXiv preprint arXiv:0906.3273},
year = {2015}
}