Terahertz multichannel filters based on the use of triadic-Cantor-set semiconductor photonic crystal

In this work, we study the terahertz multichannel filtering properties based on a stage 3 triadic-Cantor-set semiconductor photonic crystal. Here, we use the semiconductor of n-InSb so that transmission responses have three regions. Two regions with frequencies well above and below the resonant frequency, the permittivity functions are nearly a positive constant. In these two regions, transmittance responses within a photonic band gap have two groups of defect modes with numbers of Np and Np − 1, respectively. Additionally, at frequency just slightly greater than the resonant frequency, the permittivity function of n-InSb is negative and it is found that there are many transmission modes. A new gap called the longitudinal plasmon polariton gap is also produced and its gap width is widened as Np increases.