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

Area of Science:

• Optoelectronics
• Sensor Technology
• Materials Science

Background:

• Surface Plasmon Resonance (SPR) sensors are crucial for detecting chemical and biological analytes.
• Light-Diffusing Optical Fibers (LDFs) offer unique light-delivery properties for sensing applications.
• Tapering is a common technique to enhance optical fiber sensor performance.

Purpose of the Study:

• To experimentally investigate the impact of tapering on LDFs used in SPR sensors.
• To evaluate the effect of taper ratio on sensor performance metrics.
• To explore alternative configurations for optimizing tapered LDF SPR sensors.

Main Methods:

• Experimental analysis of tapered LDFs in SPR sensor configurations.
• Measurement of bulk sensitivity and SPR spectral Full Width at Half Maximum (FWHM).
• Varied taper ratios to assess their influence on sensor characteristics.

Main Results:

• Tapering LDFs for SPR sensing significantly degrades bulk sensitivity, by up to 60%.
• A slight decrease in the SPR spectra's Full Width at Half Maximum (FWHM) was observed with tapering.
• The negative effects of tapering on sensitivity and FWHM become more pronounced with increasing taper ratio.

Conclusions:

• Tapering is detrimental to the bulk sensitivity of LDF-based SPR sensors.
• Using tapered LDFs as a post-sensing modal filter presents a viable strategy to balance sensitivity loss and FWHM reduction.
• Optimized configurations may leverage modal filtering to improve overall SPR sensor performance.