Patent ID: 6768857
Filing Date: 2004-07-27
Classification: G02B

Abstract:
A method for manufacturing an optical device with a defined total device stress (&sgr;10) and a therefrom resulting defined birefringence and a therefrom resulting defined optical polarization dependence, comprising:a first step of providing a lower cladding layer comprising an amorphous material, having a first refractive index (n3); a second step of providing above said lower cladding layer an upper cladding layer comprising an amorphous material that is tunable in its stress, having a second refractive index (n5); a third step of manufacturing between said lower cladding layer and said upper cladding layer an optical waveguide core comprising substantially SiOxNy, and having a third refractive index (n4) which is bigger than said first refractive index (n3) and than said second refractive index (n5), whereby after said third step said optical waveguide core has a waveguide core stress (&sgr;4); a fourth step of annealing said upper cladding layer by: i) keeping the upper cladding layer at a first temperature (T1) between 400 and 600Â° C. for a preparation time (tp) above 0.5 hours, ii) raising the temperature to a second temperature (T2) between 600 and 1280Â° C. with a heating rate (rh) between 5 and 20 K/min, iii) maintaining the second temperature (T2) for an annealing time (ta) between 2 and 5 hours, iv) lowering the temperature to a third temperature (T3) between 300 and 600Â° C. with a cooling rate (rc) between âˆ’0.5 and âˆ’10 K/min, and v) lowering the temperature to a fourth temperature (T4) above 10Â° C., whereby said upper cladding layer has a cladding layer stress (&sgr;5) which together with said waveguide core stress (&sgr;4) results in said total device stress (&sgr;10).