Topological photonic crystal temperature sensor in dual nanobeam configuration

Topological photonics aims to generate a revolution of technological advances related to the generation of highly efficient photonic devices. However, the variety of platforms used to carry out such a revolution is still limited and challenging for industrial production, making it imperative to generate simple and powerful topological photonic devices. In this work, we have proposed the ultra-compact design of a highly efficient temperature sensor based on a dual nanobeam configuration containing a topological photonic crystal. Importantly, the topological photonic crystal was designed within a higher-order bandgap, unlike conventional topological photonic crystal designs that usually use the bands of the fundamental modes. We have achieved the opening of Dirac points in the upper bands by means of a translation operation that breaks the inversion symmetry in both trivial and non-trivial configurations. With these features, it is easy to generate zero-dimensional edge states with a large effective modal volume that allows to easily acquire Fano resonance effects. The sharp topological Fano resonance profile allows the photonic system to perform under multifunctional operability, working in a coarse and wide dynamic range, as well as in an ultra-fine short dynamic range. In this regard, the wide dynamic range has a spectral sensitivity of 0.226 nm/°C and the ultra-fine range has a transmittance sensitivity of 820%/°C with quality factors of 1.1 × 105. The results of this research pave the way to the generation of multifunctional photonic sensing devices with robust topological states against disturbances in the higher mode bands.