Waveguides based on Te2As3Se5 thick films for spatial interferometry

Planar waveguides were obtained by deposition of Te2As3Se5 films on polished As2S3 glass substrates by RF-sputtering or thermal evaporation. The RF-sputtered films were porous and had a column-like structure. By contrast, the thermal evaporated films were homogeneous and dense. They were adhesive, transparent up to 18 μm and characterized by a refractive index of 2.821 ± 0.005 at 10.6 μm. M-lines measurements highlighted the existence of several guided mode lines, proving that the manufactured structures behaved as waveguides. The geometry of the film was modified by physical or reactive ion etching. Some quasi vertical ribs up to 2.11 μm in depth were etched by reactive ion etching under a CF4/O2 atmosphere.