A recent experimental study of pump-probe process on material Sr_(1-y)NbO_(3+δ) shows an optical switching that reduces the reflectance up to nearly 100%. Here, we propose a simple model to explain that phenomenon. We hypothesize that the reflectance reduction is caused by correlation effects arising from the electron-electron scatterings accompanying the decrease in the number of electrons in conduction band as the electrons are excited to the higher band during pump-ON period. In this preliminary study, we use a one-dimensional tight-binding model, and phenomenologically add to the model an artificial self energy associated with the presence of electron-electron interactions. We use Green function method to solve our model, calculate the optical response functions, and eventually the reflectance as a function of the photon frequency. Our calculation results highlight the necessity of correlation effects to enable the reduction of reflectance at the probe photon frequency during the pump-probe process.
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