Ultra-Sensitive Refractive Index Sensors Based on Bloch Surface Waves With Transition Metal Dichalcogenides

Bloch surface wave (BSW) sensors are considered to be a great candidate to replace the conventional surface plasmon resonance (SPR) sensors. In this paper, a high performance refractive index sensor based on BSW resonance in the truncated one-dimensional photonic crystal (1DPC) has been theoretically confirmed using transition metal dichalcogenides (TMDCs). The impact of four different two-dimensional TMDCs nanosheets on the sensors are studied, with which the state of art sensitivity of wavelength-interrogation has been achieved. Specifically, with MoSe
₂
, WSe
₂
, MoS
₂
, and WS
₂
nanosheets, the measured figure of merit (FOM) are 732.1/RIU, 733.0/RIU, 730.5/RIU, and 700.7/RIU, respectively. To our knowledge, this is the best performance achieved so far compared to the existing BSW and SPR sensors. Besides, the impact of the 1DPC period and the number of TMDCs layers were discussed in detail. In addition, at the interface of TiO
₂
and TMDCs, it is found that the electric intensity is enhanced by nearly 7 times compared to the initial intensity, which also results in an increased evanescent depth in the sensing medium. The high sensitivity sensors proposed in this paper can be applied in the field of biological and chemical sensing.