  The choice of the most suitable analytic photoionization model in solids is a
challenging task with no default solution. Here we show how the best formalism
can be determined based on the waveform of the pulse reflected by a sample due
to photoionized almost-free electrons in the conduction band. For a typical
case of diamond, we compare three simple models and benchmark them against
highly accurate first-principle TDDFT simulation, by analysing the fit between
the reflected pulses in time and frequency domain. For the aims of this paper,
we have developed a software package, called PIGLET, for the FDTD simulation of
photoionization-governed propagation, which is now freely available for the
scientific community. Furthermore, we show that due to interband contributions
for very short sub-10-fs pulses a semi-classical description based on any
analytical photoionization model fail to provide an adequate description.
