Optically controlled GaAs-GaAlAs photonic band gap structure

We study a mechanism of light-by-light control, based on changing the refractive index of the narrow-band layers in a semiconductor photonic band gap structure (PBGS). This change is caused by the contribution of the non-equilibrium charge carriers generated by the controlling radiation. We theoretically show that this mechanism can be efficient if an optimal controlling light wavelength is taken near the proper absorption edge of the narrow-band semiconductor layers, since small changes of the layer refractive indices at the band gap edge of a PBGS cause essential change of the transmission characteristics. A modulation depth of the controlled light of more than 90% is achieved for a PBGS based on GaAs at the wavelength 1.54×10 -6 m under the controlling light power equal to 5×10 7 W m -2 . The inertia of the mechanism considered is determined by the lifetime of the non-equilibrium charge carriers in semiconductor layers and is equal to 10 -7 s in our case.