Integrated optical device

A process for manufacturing an integrated optical device, comprising:

• forming on a substrate a first and a second integrated waveguides each comprising a core and a cladding, a section of the first waveguide and a section of the second waveguide being arranged so as to be in optical coupling relationship;
• forming along the first waveguide section and the second waveguide section at least one respective first and second modulated refractive index regions each comprising at least one pair of regions having a first refractive index n1 and, respectively, a second refractive index n2 greater than the first, said regions being adjacent to each other along the respective waveguide section,
• said forming the at least one pair of regions comprising cutting away a portion of the respective waveguide section for defining a gap between two adjacent portions of the respective waveguide section, said gap extending for at least the entire cross-section of the core of the respective waveguide section;
• and
• making the percentage difference Δn=100×(n2/n1−1) [%] between said first and second refractive indexes greater than 1.5%.