Two-dimensional transition metal dichalcogenides (TMDs) have very potential properties for sensing applications. Hence, a lossy-mode resonance (LMR) refractive index (RI) sensor based on TMDs- indium-tin-oxide (ITO) configuration is proposed for high imaging sensitivity. A significant advantage of the proposed LMR sensor is that can achieve sharp resonance curves for both the transverse electric (TE) and transverse magnetic (TM) polarizations while the traditional surface plasmon resonance (SPR) sensor can only support TM polarizations. Through theoretical analysis, we found that the imaging sensitivity can be improved to 6438 RIU-1 (ns=1.330) and 6695 RIU-1 (ns=1.340) for TE and TM polarizations, respectively. It is an existing improvement of about 85.84 times and 11.5 times correspond to the single ITO-based LMR sensor without TMDs, respectively. This article reveals the design rules of the LMR sensor after system research, which provides guidance for further research and applied in environmental monitoring, biomolecules inspection, and so on.

A novel dual-band reflective optical sensing method for simultaneous measurement of hemoglobin (Hb) concentration and temperature by hybrid guide-mode resonance (GMR)-topological photonic state (TPS) sensor was proposed. The dual-band reflection peaks can be explained by two different mechanisms: one is attributed to the excitation of GMR, and the other is due to the generation of TPS. The GMR worked as the sensing channel of Hb concentration because it is in direct contact with the Hb. Moreover, the TPS worked as the sensing channel of temperature. When the Hb concentration and temperature variation, the two reflection peaks would all shift, but with different sensitivities. Excellent biosensor performance can be obtained by systematically adjusting structural parameters such as grating period (P), grating width (W), grating height (h), and spacer layer thickness (d). Notably, by using the dual-wavelength matrix method, the cross-interference caused by temperature variation is eliminated. The results concluded that the Hb concentration sensitivity and the temperature sensitivity of the proposed sensor could reach 264.44 nm/RIU and 0.061 nm/°C, respectively. The proposed sensor provides a promising sensing strategy for multi-parameter sensing.

Dielectric metasurface based on bound states in the continuum (BICs) have attracted significant attention recently due to their unique characteristics, such as ultra-high quality factors (Q-factor), narrow linewidths, and enhanced light-matter interactions. In this paper, we proposed a novel sensor design for the simultaneous measurement of seawater salinity and temperature based on an asymmetric dimer dielectric metasurface. By calculating the transmission spectrum of the metasurface, we observe two transmission dips corresponding to the toroidal dipole (TD) and magnetic dipole (MD) resonances. Specifically, the TD resonance is governed by breaking the translational symmetry (TS) protected BICs, while the MD resonance is excited by breaking the reflection symmetry (RS) protected BIC. Both dips exhibit shifts in response to changes in the refractive index (RI) or the temperature. Simulation results reveal that the sensing sensitivities of the two dips to RI are 212.56 nm/RIU and 327.85 nm/RIU, respectively, while the sensitivities to temperature are 0.04 nm/°C and 0.05 nm/°C, respectively. We believe that this work is very beneficial for the design of optical sensors for multi-parameter measurement applications.