Optical light controlled band edge switch

We study a mechanism of the light-by-light control, based on changing the refractive index of the narrow-band layers in a semiconductor photonic band gap structures (PBGS). This changing is caused by the contribution of the non-equilibrium charge carriers generated by the controlling radiation. We 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 the little changes of the layers refractive indexes at the band gap edge of PBGS cause essential change of the transmission characteristics. The modulation depth of the controlled light of more than 90% is achieved for the PBGS based on GaAs at the wavelength 1.5 μm under the controlling light power equal to 5.9 kW/cm². 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