Comprehensive investigation on chalcogenide thin film coated multimode optical fiber: Visible evanescent-wave absorption refractometer

In this work, a different insight into the absorption characteristics of chalcogenide thin film over visible-wavelength range is studied in detailed. A comparative study lossy mode resonance (LMR) dips stem from evanescent-wave theoretically and experimentally investigated towards refractive index measurement aqueous environment. The absorbing layer thermally evaporated arsenic trisulfide (As2S3) coated onto low OH etched optical fiber (ChOF) prepared. X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, were used to characterize chemical species, crystal structure, morphology degradation confirming As2S3, thin-film deposition on curved surface. LMR condition hinging adoption was comprehensively explored by referring spectra as function wavelength its thicknesses. Taking advantage absorptive features within visible spectral range, results verified that coating even subwavelength thickness As2S3 bare has ability provide liquid refractometer with versatile features. Our point new path for development LMR-based sensors, environmental or be combined integrated micro-photonics device biosensors.