Infrared absorption by laterally modulated two-dimensional electron systems

We present model calculations of far-infrared absorption by the combined system of a grating coupler plus a laterally modulated two-dimensional electron gas. The response of the electron gas to the optical fields has been determined in a companion paper and the grating is described as a planar sheet with alternating strips of different conductivity. By varying parameters for the strength and period of the modulation the fractional change of transmission through the system is examined in different response regimes. We find that a single peak can dominate the spectra in certain limits although the physical origin of this peak varies. It can arise from a single intersubband transition or be due to either running or confined plasmon modes. In the crossover regions between these limits there is no simple behavior in the spectra.