Planar Surface Plasmonic Resonance Light Coupling via Transmission Diffraction Gratings for Chemical Optical Sensors

Abstract In this paper, a sensor containing light coupled with plasmon-polariton waves using surface plasmon resonance (SPR) structure through a volume diffraction transmission grating was investigated. A film of amorphous chalcogenide materials such as As 2 S 3 was used. In amorphous films, photoinduced changes in the refractive index were achieved by irradiation with coherent light of recording laser with a wavelength of λ r = 532 nm. The developed physical model made it possible to determine some operating parameters of the SPR structure, such as the incidence angle, grating tilt angle, and grating period. The diffraction gratings were fabricated by the holographic interferometric method and have an efficiency of 62%. The fringe tilt should be 6.75° for SPR with an air environment and 12.3° for SPR with an aqueous environment if the angle of light incidence on the structure was chosen to be 30°. The SPR structure is planar, and the angular interrogation is carried out from the back side, which is an advantage since the analyte does not necessarily have to be optically homogeneous and free from absorption.