Wide-range transmitting chalcogenide films and development of micro-components for infrared integrated optics applications

Development of micro-components for IR integrated optic devices requires the elaboration of IR waveguides. It is shown that amorphous chalcogenide films from the Ge-Se-Te system are well suited to such development. Thermal and optical characteristics of films elaborated by thermal co-evaporation are first measured. The Se-rich (> 60 at. %) region with a Ge content of about 25 at. % comprises films with a vitreous transition temperature, T sub()g larger than 400K, a high thermal stability ( Delta T > 100K) and a well-controlled refractive index, n, owing to a weak dependence of n with composition in this region. Films in this composition region are then profitably used to develop optical structures, such as straight or S-bend waveguides, spirals, Y-junction or Mach-Zehnder interferometer, by stacking and further etching of the films. The transmission region accessible to these structures lies from telecommunication wavelength up to 16-17 mu m. When a higher transmission region is required, the use of pure Ge-Te films is mandatory. A modal filter allowing a light rejection efficiency of 6.10 super(-5) to be a part of a spatial interferometer is then elaborated.