Label‐Free Spontaneous Raman Sensing in Photonic Crystal Fibers with Nanomolar Sensitivity

An approach to significantly enhance spontaneous Raman sensitivity through the formation of a thin film via thermophoresis along with evaporation at facet hollow-core photonic crystal fiber is reported for first time. Sensitivity detection increased by more than 6 orders magnitude both organic and inorganic nanoparticles, facilitating search trace analytes in solution. Detection two alumina polystyrene, demonstrated down 392 nM without use surface-enhanced spectroscopy or other chemical-based procedures. This new thin-film deposition simplifies simultaneous analysis small compounds, previously arduous task using conventional Raman.