Chip‐Scale Terahertz Sensing Driven by Supercoupling Induced Transparency in Topological Cavities

ABSTRACT

Chip‐scale terahertz (THz) sensors enable nondestructive, low‐photon‐energy probing of material‐specific vibrational, phononic, and dielectric responses within compact integrated platforms. However, their sensitivity remains limited by the weak interactions between THz waves and analytes. Here, we present an on‐chip THz topological sensor driven by supercoupling induced transparency (SIT) in coupled topological edge state cavities (TESCs). The interference between a leaky TESC and a guided TESC generates a sharp transparency window that combines strong field confinement with steep dispersion and a pronounced slow‐light effect. These features simultaneously enhance the spatial overlap between the THz field and the analyte and extend their interaction time, thereby enhancing the resulting spectral shifts and group‐delay variations. Using Kapton films of varying thicknesses as analytes, the topological SIT sensor achieves a frequency‐thickness sensitivity of 183 GHz mm ⁻¹ and a group delay‐thickness sensitivity of 67 ns mm ⁻¹ . This work establishes SIT as an effective mechanism for enhancing light‐matter interactions in chip‐scale THz systems, offering a promising route toward integrated sensors for thin‐film metrology, nondestructive inspection, and biochemical detection.