Ring core fiber: a novel design of PCF for SERS sensing (Conference Presentation)

Abstract

Surface enhanced Raman spectroscopy (SERS) allows sensitive detection of analytes, thanks to their vibrational Raman spectra. Planar SERS substrates often lack the reliability in measurement due to larger variations in signal intensity contributed by irregularities in nanostructures. In this context, photonic crystal fibers (PCFs) that combine excellent light guiding properties and the possibility to incorporate nanostructures and liquid or gas analytes into their axially aligned air holes, offer tremendous promise as an opto-fluidic SERS platform. Such sensors possess the enormous signal enhancement inherent to SERS and the flexibility of optical fibers. In addition, PCFs offer improved reproducibility, repeatability and sensitivity in measurement compared to planar substrates, due to the larger volume of interaction between the guided light and the analyte, and to highly reliable light couplings into the fiber core. Here, we present a novel design of PCF called ring core fiber (RCF), which is specifically engineered to further increase the interaction area in order to improve the sensitivity and reliability of the sensor. Preliminary experimental results showed that sensitivity of SERS sensing is improved by 115% compared to the best SuC-PCFs. Ongoing numerical simulations indicate that by further optimizing the dimensions of the ring, sensitivity could be improved by at least one order of magnitude with RCF. We envision that this new design with increased sensitivity and measurement reliability could be the next major step towards a clinically viable liquid biopsy fiber probe.