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A novel wavelength modulated optical fiber-based symmetrical long-range surface plasmon resonance (sLRSPR) biosensor with high quality factor (Q-F) of 56.70 RIU−1 and temperature self-reference was proposed and demonstrated. The multilayered architecture of the sLRSPR biosensor consisted of cladding/dielectric-buffer-layer (DBL)/Au-nanofilm/DBL/analyte, and the DBLs on both sides of the Au-nanofilm were identical, which greatly increased the matching degree of the permittivities of analyte and the DBL near cladding and reduced the loss of long-range surface plasmon-polaritons. Therefore, the sLRSPR sensor displayed excellent sensing performance, and its Q-F was 3.27-folds higher than that of the conventional SPR sensor. Furthermore, the sLRSPR sensor was employed as a biosensor for the measurement of average refractive index (RI) of cell, and the temperature-sensitive optical adsorption characteristic of the DBL was utilized to provide temperature self-reference for the RI measurement. The sLRSPR biosensor realized simultaneous measurement of RI and temperature at the exactly same location, which can eliminate the measurement error introduced by temperature to RI measurement. The sLRSPR biosensor proposed in this paper possessed higher detection precision and presented greatly promising application prospects in the field of biochemistry.

In this paper, we have fabricated and characterized a bimetallic optical fiber surface plasmon resonance (SPR) sensor, followed by molybdenum disulfide (MoS2) nanosheets have been coated on the surface of metal film. The performance of the sensor is discussed in terms of the sensitivity and the figure of merit (FOM) theoretically and experimentally. The effect of different thickness of Au/Ag film on the performance of the sensor was studied. The results indicate that the FOM of sensor with silver film is much higher than that with gold film, although gold film is conducive to the sensitivity improvement. Two types of sensors are fabricated, which are the sensor with silver layer and the sensor with bimetallic layers of silver and gold. The sensitivity of the sensor with silver film and the sensor with bimetallic layers are 2141 nm/RIU and 2487 nm/RIU, respectively; and the FOM values are 19.44 RIU−1 and 18.47 RIU−1, respectively. Then, it is theoretically confirmed that MoS2 has the potential to promote the sensitivity of SPR sensor, and the sensitivity is tuned by the number of layers of MoS2 nanosheets. MoS2 nanosheets successfully bridged the gold film with the help of chemical bonds. The sensitivity of the sensor with MoS2 nanosheets is 3061 nm/RIU, and its FOM value is 23.29 RIU−1.