Harmonic and anharmonic oscillator electron models for the energy description of the Al-x Ga1-x As / GaAs heterostructures are proposed. The one and polyoscillator optical functions (the real and the imaginary part of the dielectric function and the refractive index, the optical conductivity, the absorption coefficient, the loss function, the corrected loss function, the reflectance factor) of GaAs, AlAs, AlGaAs, Al-x Ga1-x As between 0 and 25 eV are presented. This model provides the optical functions determined on a wavelength-by-wavelength basis, without having to resort to the Kramers-Kronig transformation. The energy parameters (the valence electron plasma, effective plasma, natural, effective natural, dielectric maximum and minimum, radiant friction, local internal field energies) of the heterostructures are computed. The corrected loss functions of GaAs, AlAs are dominated by peaks, with maxima near 15.62 eV and 15.31 eV, accordingly. It can be assigned to a collective excitation of all valence electrons. The role of the plasma oscillations are proved. The potential barriers between semicionductor phases are overcome by the plasma mode energies. In view of experimental results, the reversible separate oscillator decomposition of the energy functions is conducted by this approach. The latent local districts are revealed in the heterostructures.