Refractive index sensing performance demonstration of reflective microfiber long taper elaborated by silver and silicon nanoparticles using seawater samples

Abstract

A refractive index fiber probe has been proposed based on a long-tapered microfiber, which was obtained from a long single-mode microfiber by the oxyhydrogen-flame-scanning and stretching method using a multifunctional fiber tapering machine. This microfiber probe was used to detect the refractive index of seawater samples with different concentrations by demodulating the intensity of reflected light. The refractive index sensing performance of the long-tapered microfibers elaborated by the low refractive index UV glue distributing silver nanoparticles and silicon nanoparticles were experimentally demonstrated, compared and analyzed. More stable spectra and sensing performance was obtained for the silicon nanoparticles compared to that of silver nanoparticles. Although a high average refractive index sensitivity of 13.047 dBm R−1IU−1 was obtained for the long-tapered microfiber coated by two layers of silver nanoparticle UV films. However, the quality of the corresponding spectra was severely damaged, and the amplitude of light intensity at different wavelengths varied greatly. These problems can be well avoided for the silicon nanoparticle-decorated microfiber tapers, where the overall monotonic variation of the interference spectral intensity will greatly simplify the signal demodulation process and improve the reliability of the measurement results.