The Role of Tapered Light-Diffusing Fibers in Plasmonic Sensor Configurations

In this work, we experimentally analyzed the effect of tapering in light-diffusing optical fibers (LDFs) when employed as surface plasmon resonance (SPR)-based sensors. Although tapering is commonly adopted to enhance the performance of plasmonic optical fiber sensors, we have demonstrated that in the case of plasmonic sensors based on LDFs, the tapering produces a significant worsening of the bulk sensitivity (roughly 60% in the worst case), against a slight decrease in the full width at half maximum (FWHM) of the SPR spectra. Furthermore, we have demonstrated that these aspects become more pronounced when the taper ratio increases. Secondly, we have established that a possible alternative exists in using the tapered LDF as a modal filter after the sensible region. In such a case, we have determined that a good trade-off between the loss in sensitivity and the FWHM decrease could be reached.

Automated summary

In this study, the effect of tapering in light-diffusing optical fibers (LDFs) for surface plasmon resonance (SPR)-based sensors was experimentally analyzed. It was demonstrated that tapering could significantly worsen the bulk sensitivity of plasmonic sensors based on LDFs, while only slightly decreasing the full width at half maximum of the SPR spectra. Furthermore, it was found that using the tapered LDF as a modal filter after the sensible region could provide a good balance between sensitivity loss and FWHM decrease.