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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.

Fe/Sn-codoped In2O3 powders and films are prepared by a vacuum annealing process and a pulsed laser deposition technique, respectively. The structural and magnetic properties of the samples are investigated. The obvious room-temperature ferromagnetism is observed in both (In0.92Fe0.05Sn0.03)(2)O-3 powders and films, but their magnetic behaviors are very different. The ferromagnetism of the vacuum-annealed powders is partially due to precipitated Fe3O4 impurity. By contrast, the ferromagnetism of the films is intrinsic and does not originate from any magnetic impurity, as confirmed by the extensive x-ray absorption spectroscopy and magnetization studies.

Fe-doped In2O3 thin films are deposited on sapphire substrates using pulsed laser ablation. The effects of Fe concentration and oxygen partial pressure on the structure, magnetism and transport properties of (In1−xFex)2O3 films are studied systematically. A detailed analysis of the structural properties suggests the substitution of Fe dopant ions with mixture valences and rules out the presence of clusters and secondary phases as the source of ferromagnetism. Systematic investigations of transport properties for (In1−xFex)2O3 films with a wide range of carrier densities reveal that they occur in both metallic and insulating regimes. The insulating films exhibit variable range hopping at low temperatures and show temperature dependent ferromagnetism, which can be explained by bound magnetic polarons mechanism. For the metallic films, the carrier densities play a crucial role in their robust ferromagnetism and the resistivity and magnetization are independent of temperature; the carrier-mediated exchange me...

Mn and Cr-doped In2O3 films with Sn codoping were deposited on sapphire substrate by pulsed laser deposition. The ferromagnetism of Mn-doped In2O3 films shows reversible behavior, which can be switched between “on” and “off” states by controlling the carrier density via varying Sn concentration. The enhanced ferromagnetism in Cr-doped In2O3 films is observed due to the significant increase in the carrier density with Sn doping, and the saturation magnetization can reach 2.10 μB/Cr. Most importantly, both of the experiment results reveal that the carrier density and the net spin are two crucial factors for producing and tuning ferromagnetism.