Wave phase analysis for computing density of states, group velocityand lateral shift in a 1D quasiperiodic structure containing layers ofuniaxial medium and SiO2

In this paper, by considering wave phase analysis, the density of modes, group velocity, and lateral shift in one-dimensional multilayer are theoretically computed by using the transfer matrix method in the terahertz domain. The proposed structure is based on the Fibonacci sequence constituted of uniaxial indefinite medium and SiO2 layers. It is found that for both TE and TM beams, around an angle of 90o, the lateral shift is highly negative, while it is positive at the rest of the angles. Also, for non-vertical angles, a positive peak is observed about an angle of 60o (near the Brewster angle). Our numerical analysis shows that at angles less than about 10o, the lateral shift is negative for the TM mode. It is shown that for both polarizations the density of states (the group velocity) has maximum (minimum) value near the band gap edges, while inside the band gap it becomes minimum (maximum). Superluminal and subluminal cases can be defined here.