Filtering Properties of Photonic Crystal Dual-Channel Tunable Filter Containing Superconducting Defects

In this work, we analyze filtering properties in a photonic crystal (PC) dual-channel tunable filter. The filter structure containing twin superconducting thin films is denoted as (1/2)MS1(2/1)NS2(1/2)M. Here, 1 and 2 are dielectrics of SrTiO3 and Al2O3, respectively. S1 and S2 are two high-temperature superconducting thin films taken to be the typical system, YBa2Cu3O7−x. The two channel frequencies can be designed to locate within the photonic band gap (PBG) of the original PC (1/2)M. Channel frequencies can be significantly changed by changing N, the stack number of the center PC. With the use of superconducting defects, channel frequencies are temperature-dependent, that is, the filter is thermally tunable. The proposed filter structure is of technical use in superconducting photonic applications at terahertz frequency.