Optical characterization at 7.7 μm of an integrated platform based on chalcogenide waveguides for sensing applications in the mid-infrared
Résumé
A selenide integrated platform working in the mid-infrared was designed, fabricated and optically characterized at 7.7 μm. Ge-Sb-Se multilayered structures were deposited by RF magnetron sputtering. Using i-line photolithography and fluorine-based reactive ion etching, ridge waveguides were processed as Y-junction, spiral and S-shape waveguides. Single-mode optical propagation at 7.7 μm was observed by optical near-field imaging and optical propagation losses of 2.5dB/cm are measured. Limits of detection of 14.2 ppm and 1.6 ppm for methane and nitrous oxide, respectively, could be potentially measured by using this platform as an evanescent field sensor. Hence, these technological, experimental and theoretical results represent a first step towards the development of an integrated optical sensor operating in the mid-infrared wavelength range. © 2016 Optical Society of America.
Mots clés
Photolithography
Reactive ion etching
Waveguides
Nitrogen oxides
Magnetron sputtering
Light propagation
Infrared devices
Germanium
Evanescent fields
Multi-layered structure
Mid-infrared wavelength ranges
Optical characterization
Evanescent field sensor
Optical propagation loss
Integrated optical sensors
Sensing applications
rf-Magnetron sputtering
Ridge waveguides