Sulphide GaxGe25−xSb10S65(x=,5) sputtered films: Fabrication and optical characterizations of planar and rib optical waveguides

We report the fabrication and the physical and optical characterizations of sulphide GaxGe25−xSb10S65(x=0,5) rib waveguides. High quality films fabricated on SiO2/Si wafer substrates were obtained using the sputtering magnetron rf deposition method. The slab waveguides obtained without annealing present propagation losses of about 0.6 dB/cm at 1550 nm. These optical losses are not important for implementation in optical devices based on silicon-on-insulator or polymer, for instance, atomic force microscopy measurements revealed low interface roughness between the different media (substrate/film and film/air). Reactive ion etching was used to pattern rib waveguides between 2 and 300 μm wide. The parameters were optimized to obtain a dry etching process that had low surface roughness, vertical sidewalls, etch depth of more than 1 μm, and reasonable etching rate. This technique was used to fabricate Y optical junctions for optical interconnections on chalcogenide amorphous films. Their optical transmission was demonstrated by optical near field of guided modes and optical losses were measured and discussed.