We simulate the tuning of reflectance of a one-dimensional photonic crystal (PC) by means of charge injection. The PC is constituted from highly doped silicon layers alternating with silicon oxide layers. The wavelength of the light is assumed to be the important communications wavelength of 1.54 μm. A realistic simulation shows that sensitive tuning, and switching as well, can be achieved for an impurity density ~1019/cm3 even for superlattices only a few periods long. The reflectance results are satisfactorily interpreted in terms of photonic band structurecalculations.