Robust high-Q filter with complete transmission by conjugated topological photonic crystals

High quality factor (High-Q) and transmission optical devices are required for various applications in the fields of physics and engineering. Critical for these applications is the realization of a structure with high-Q, complete transmission and small volume. A robust high-Q filter with complete transmission by conjugated topological photonic crystals (CTPC) is presented. The study shows that an ultra-high-Q of more than 10(8) with complete transmission is obtained by the CTPC with 2 μm long due to the excitation of conjugated topological edge-states (CTES). It is also found that even though the quality factor of resonances increases as the periodic number of multilayers increases, these resonances are still complete transmission. A novel concept of CTES is first proposed in this study and investigated the effect of its topological phenomenon on high quality factor via CTPC. We theoretically realize the robust high-Q and complete transmission in the CTPC, which is different from those in periodic, quasi-periodic, Fabry-Perot photonic crystals and traditional topological photonic crystals (TPC).