Chalcogenide Circuits For The Realization Of Co2 Micro-Sensors Operating At 4.23 Mu M

In a context where the control of gases becomes important in a wide range of applications - health care, industry, housing, transportation, environment - we have in sight the realization of infrared optical micro-sensors. In particular, we wish to develop an optical micro-sensor operating at the wavelength 4.23 mu m, wavelength corresponding to an absorption band of carbon dioxide, the main greenhouse gas.The first step consists in manufacturing straight waveguides that were capable of operating at this wavelength. They are obtained by stacking and etching layers of the ternary system Ge-Se-Te. The waveguides opto-geometrical parameters such as refractive indices, thicknesses of the layers, etching depth and waveguide core width are set through a design process to obtain a single mode behaviour at 4.23 mu m. After fabrication, straight waveguides are optically characterized at lambda = 4.23 mu m on a bench dedicated to the study. The second step consists in designing circuits such as Y-junctions or Mach-Zehnder interferometers, still being able to operate at lambda = 4.23 mu m, whereas the last step consists in studying the possibility of integrating a CO2-sensitive layer to the circuits, in order to fabricate a micro-sensor.As this stage, straight waveguides were fabricated and proved to transmit light at lambda = 4.23 mu m, with propagation losses at about 1.3 dBcm(-1). Y-junctions and Mach-Zehnder interferometers are under fabrication, and possible sensitive layers are under investigation.