Infrared sensor for water pollution and monitoring

Development of Mid-infrared sensors for the detection of biochemical molecules is a challenge of great importance. Mid-infrared range (4000 400 cm(-1)) contains the absorption bands related to the vibrations of organic molecules (nitrates, hydrocarbons, pesticides, etc.). Chalcogenide glasses are an important class of amorphous materials appropriate for sensing applications. Indeed, they are mainly studied and used for their wide transparency in the infrared range (up to 15 [nu for selenide glasses) and high refractive index (between 2 and 3). The aim of this study is to synthesize and characterize chalcogenide thin films for developing mid-IR optical waveguides. Therefore, two (GeSe2)100,(Sb2Se3) chalcogenide glasses, where x=10 and 50 were chosen for their good mid-IR transparency, high stability against crystallization and their refractive index contrast suitable for mid-IR waveguiding. Chalcogenide glasses were prepared using the conventional melting and quenching method and then used for RF magnetron sputtering deposition. Sputtered thin films were characterized in order to determine dispersion of refractive index in UV-Vis-NIR-MIR. Obtained results were used for the simulation of the optical design in mid-infrared (2 = 7.7 [nu). Selenide ridge waveguide were prepared by RIE-ICP dry etching process. Single-mode propagation at 7.7 [nu was observed. Optical losses of 0.7 0.3 and 2.5 0.1 dB.cm(-1) were measured in near-infrared (2 = 1.55 pm) and mid infrared (2 = 7.7 nm), respectively. Achieved results are promising for the fabrication of an integrated optical sensor operating in the mid-infrared.