Sensitivity-Enhanced Fiber Plasmonic Sensor Utilizing Molybdenum Disulfide Nanosheets

Molybdenum disulfide (MoS2), as a representative layered transition metal dichalcogenide material, possesses great potential applications in highly sensitive detection. In this paper, a sensitivity-enhanced surface plasmon resonance fiber sensor modified with an overlayer of MoS2 nanosheets is proposed and demonstrated. The sensitivity, which is related to the thickness of the MoS2 overlayer, can be tailored by the number of the deposition cycles. Benefiting from the large surface area, high refractive index, and unique optoelectronic properties, coating the MoS2 nanosheet overlayer on the gold film can efficiently improve the sensitivity. The highest sensitivity of 2153.9 nm/RIU was experimentally achieved by depositing the MoS2 nanosheets for two cycles, and it shows a sensitivity enhancement of 37.3%, compared to the case without the MoS2 overlayer. Moreover, it is found by experiments that the further deposition of MoS2 causes the decrease of sensitivity, indicating the existence of an optimized thickness for the MoS2 overlayer. The experimental results are interpreted and verified by numerical simulations accompanied with theoretical analysis.