Excitation of Bloch Surface Waves on an Optical Fiber Tip

摘要

The integration of structures supporting Bloch surface waves (BSWs) withrnoptical fibers is highly desirable, since it would enable the development ofrnhigh-figure-of-merit miniaturized all-fiber optrodes, opening new pathwaysrnwithin the “lab-on-fiber” roadmap. Here, the first experimental demonstrationrnof grating-assisted excitation of BSWs on the tip of single-mode fibersrnin the near-infrared region is provided. This is attained via fabrication ofrna 1D diffraction grating on the fiber facet, and subsequent deposition of arn1D photonic crystal. In spite of a resonance broadening due to grating-inducedrnmorphological perturbations, the measured Q-factor of 50 is still higherrnthan typical lab-on-tip plasmonic-probe benchmarks. With a view towardrnbiomolecular sensing, a surface sensitivity of 1.22 nm nm~(−1) of homogeneousrnoverlay deposited over the active region, which is in line with most plasmonicrnoptrodes largely used in connection with optical fibers, is evaluated. Thernresults also highlight the current limitations and the challenges to face forrnthe development of advanced BSW-based fiber-tip platforms for biologicalrnsensing applications.