Theoretical study of transparent peaks in a topological waveguide-cavity coupled system

All-optical analogues of electromagnetically induced transparency (EIT) and Autler–Townes splitting (ATS) have been investigated on various platforms due to its wide applications in optical devices. This theoretical study suggests an immune scheme to fabrication disorders based on the topological waveguide that couples with two cavities. On the one hand, the topological waveguide is immune to local disorders and can tolerate moderate global ones due to bulk gaps of photonic crystals. On the other hand, the global disorders are utilized to induce a frequency splitting between the two cavities, which is responsible for transparent peaks in transmission spectra. Moreover, the maximum tolerated disorders are theoretically analyzed, indicating that fabrication disorders in such a scheme can be used to design EIT or ATS.