Method for manufacturing strip optical waveguides

Method of manufacturing a strip optical waveguide entirely based on polymer materials comprising the following steps:

• depositing onto a semiconductor substrate a lower layer of low refractive index buffer polymer which is thereafter stabilized and dried and then cured at a temperature close to the glass transition temperature of said polymer;
• depositing a guiding polymer adapted to be formed subsequently into strips onto said lower layer followed by curing to stabilize said guiding polymer without degrading its properties;
• depositing a layer of silicon nitride (Si.sub.3 N.sub.4);
• deposing a photosensitive resin and then transferring the geometry of said strips to said resin by photolithography;
• selectively etching said silicon nitride layer with CF.sub.4 plasma, said strips being protected by said photosensitive resin;
• selectively etching said photosensitive resin and said guiding polymer at the locations where the latter is not protected by said silicon nitride layer;
• etching said polymer until said lower buffer polymer layer is exposed;
• etching said silicon nitride layer protecting said guiding polymer strips;
• depositing an upper layer of low index buffer polymer onto the resulting structure which is then cured at a temperature similar to that used to stabilize said guiding polymer.