Optical device of waveguide type and its production method

A waveguide optical device comprising:

• a waveguide comprising a core layer and a guide layer, wherein said core layer and said guide layer are formed from semiconductors having zinc blend crystal structures;
• wherein:
• said waveguide comprises fundamental mode waveguides and a multimode waveguide which has a width greater than a width of said fundamental mode waveguides;
• said multimode waveguide includes side faces structured from one or more of:
• planes equivalent to a (100) plane of said semiconductors,
• planes forming an angle of inclination of 7° or less with planes equivalent to the (100) plane, in a direction parallel to a surface formed between said core layer and said guide layer;
• and
• planes forming an angle of inclination with planes equivalent to the (100) plane, in a direction normal to the surface formed between said core layer and said guide layer;
• and
• said waveguide optical device further comprises a semiconductor layer, wherein said multimode waveguide is embedded as a buried layer within said semiconductor layer.