Properties of High-Tc Single Crystals as Natural Interferometers in the THz Frequency Range

We consider oblique incidence of (p)TM-polarized wave on the anisotropic superconducting slab, immersed on a dielectric media, such that its uniaxial (c) axis is perpendicular to the surfaces. The below and above plasma frequency transmissivity patterns are studied and several of its properties determined, within the context of the Maxwell-London theory. Below, the regime is attenuated for any incident angle, and there is a transmissivity maximum, quite pronounced in case of a very high external dielectric constant. Above, a propagative regime exists where the superconductor is a natural optical resonator, and we show here that the minimum of the transmission peaks are modulated by an envelope function associated to the Brewster condition. We propose this set-up to obtain light with an extremely small transverse wavelength inside the superconductor.