Method of fabricating an optical integrated circuit

A method of fabricating an optical integrated circuit comprising at least one etched and buried BRS waveguide coupled to at least one etched but not buried ridge waveguide, said method comprising the following steps:

• a- forming on a substrate at least a first area and a second area respectively comprising a first guide layer and a second guide layer, said first and second guide layers being buried and butt coupled,
• b- forming a first mask on said first and second areas to define the imprint of said BRS and ridge waveguides,
• c- protecting said second area with a second mask and etching said first area to define said BRS waveguide,
• d- removing said second mask and growing a layer on the surface of the two areas to form a confinement layer burying said BRS guide in said first area and a top layer in said second area, and
• e- protecting said first area by a third mask, etching away said top layer formed in said second area and then using said first mask to etch said second area and define said ridge waveguide.