Effective surface impedance for a superconductor-semiconductor superlattice at mid-infrared frequency

The effective surface impedance for a superconductor-semiconductor superlattice at mid-infrared frequency is calculated based on the transfer matrix method together with the enhanced two-fluid model for the high-temperature superconductor. We first investigate the effective surface resistance and surface reactance in the case of normal incidence. We find that there is a critical thickness for superconductor film such that a minimum loss is attained. We next study the effective surface impedance under the oblique incidence. The calculated effective surface impedance indicates that the angle-dependent feature is only seen for the single period. However, it does not rely on the number of periods when the period is greater than two and, in the meantime, the surface resistance is nearly unchanged as a function of the angle of incidence.