Abstract: An optical device with a defined total device stress (&sgr;10) and a therefrom resulting defined birefringence in order to obtain a well defined optical polarization dependence is proposed. It comprises a lower cladding layer (3) with a first refractive index (n3), thereon an upper cladding layer (5) with a second refractive index (n5) and between an optical waveguide core (4) with a third refractive index (n4) which is bigger than the first refractive index (n3) and the second refractive index (n5). The optical waveguide core (4) has a waveguide core stress (&sgr;4) resulting from the manufacturing process and the upper cladding layer (5) is manufactured to have an inherent cladding layer stress (&sgr;5) which together with the waveguide core stress (&sgr;4) results in the total device stress (&sgr;10).

Abstract: A singlemode lightwaveguide-coupling element is positioned between an initial waveguide section which there has a basic final width (W0f) and a final waveguide section which there has a basic initial width (Wn+1i) which is bigger than the basic final width (W0f). The lightwave directions of both waveguide sections are inclined at a predetermined total angle (&Dgr;&agr;) towards each other. Starting from the initial waveguide section, the lightwaveguide element comprises intermediate waveguide sections each of which at its end has a lightwave direction which is inclined towards the lightwave direction at its opposite end at an inclination angle (&Dgr;&agr;v), such that the sum of all inclination angles equals the predetermined total angle (&Dgr;&agr;).

Abstract: A singlemode lightwaveguide-coupling element is positioned between an initial waveguide section (10) which there has a basic final width (W0f) and a final waveguide section (30) which there has a basic initial width (Wn+1i) which is bigger than the basic final width (W0f). The lightwave directions of both waveguide sections are inclined at a predetermined total angle (&Dgr;&agr;) towards each other. Starting from the initial waveguide section, the lightwaveguide element comprises intermediate waveguide sections each of which at its end has a lightwave direction which is inclined towards the lightwave direction at its opposite end at an inclination angle (&Dgr;&agr;&ngr;), such that the sum of all inclination angles equals the predetermined total angle (&Dgr;&agr;).