Unlocking dual-function sensing via topological edge and corner states

Topological corner states (TCSs) enable localized energy at on-demand corners of a system and inherent defect immunity, making them highly promising for various applications such as communication, integrated optics, and sensing. However, traditional TCS-based sensors are designed for single-function detection, lacking the capability for multifunctional sensing. In this Letter, we propose a dual-function sensor that leverages TCSs within a composite photonic structure. Herein, the excitation of TCSs arises from near-field coupling assisted by topological edge states. By utilizing dual-band TCSs, the proposed sensor exhibits wavelength shifts in response to refractive index (RI) and temperature, achieving salinity sensitivity of 0.04 THz/‰ and temperature sensitivity of 0.021 THz/°C. This work establishes a new, to the best of our knowledge, paradigm for multifunctional sensing, paving the way for ultra-compact on-chip nanophotonic devices.