Optimization of chromatic SPR sensor of gas environment based on registration of reflected beam color: Modeling and experiment

Optical characteristics of a chromatic sensor for detecting gas media based on the surface plasmon-polariton resonance (SPR) effect were calculated during recording color spectrum responses of the reflected beam. At this, spectral characteristics of all the components of the optical system (radiation source, photodetectors and multilayer reflective structure) in the visible light range were taken into account. Based on these calculations, a method for assessing the hardware sensitivity of the SPR sensor to changes in the external environment characteristics (refractive index or permittivity) was proposed. A thin silver film on the base face of a prism in the Kretschmann geometry was used as a sensitive element for modeling and experimental investigations. This enabled a full-fledged SPR effect in the entire visible spectral range of 400…700 nm. Colorimetric registration of the reflection spectra using a color webcam with R, G, B output signals as the optical response was implemented.