  We have developed a function which describes SiPM response in both small
signal and highly saturated regimes. The function includes the reactivation of
SiPM pixels during a single input light pulse, and results in an approximately
linear increase of SiPM response in the highly saturated regime, as observed in
real SiPMs. This article shows that the function can accurately describe the
measured response of real SiPM devices over a wide range of signal intensities.
