In spite of a small and indirect bandgap, silicon features properties that are potentially very attractive for optical applications. The unsurpassed level of impurity control leads to suppression of nonradiative recombination paths and provides for a very long minority carrier lifetime. Up to the present, observation of an optical memory effect has not been reported for crystalline silicon (c-Si). In contrast, it has been observed in GaAs and GaN. In this study, we have used c-Si doped with erbium (Er) ions, since the trivalent Er3+ ion emits at a wavelength of 1.54 μm that is suitable for telecommunication applications. In a two-color experiment, utilizing a Nd:YAG pulse excitation as a writing beam and a free-electron laser (FEL) as a reading beam, we revealed that Si exhibits optical memory and afterglow effects at low temperatures T<50 K. Both effects are, in fact, manifestations of the properties of Si itself, conveniently revealed by the optical dopant. Detailed investigations of the FEL-induced emission at 1.54 μm show that this excitation mechanism is governed by the release of a single type of charge carrier. This implies that hole and electron capture events necessary for the Er excitation could, in principle, be separated in time. Therefore it appears possible to combine optical and electrical write/read procedures for the reported memory effect.