Fano line shapes generated by an excitonic layer in attenuated-total-reflection geometry and application to refractive-index sensing

Reflectance, transmittance, and absorptance spectra of the Kretschmann-Raether attenuated total reflection configuration consisting of a BK7 prism, a nonmetallic excitonic layer, and a surrounding medium are calculated. For angles of incidence below the critical angle of total reflection, the reflectance and transmittance spectra normalized to background spectra exhibit Fano line shapes. Under the total reflection condition, nearly perfect absorption is achieved. The Fano line shape of the normalized reflectance spectrum is found to depend strongly on the refractive index of the surrounding medium, thus opening up a scheme of refractive index detection based on line shape analyses.