Birefringence trimming of integrated optical devices by elevated heating
The present invention relates to a method for trimming birefringence of an integrated optical device with at least one waveguide having a birefringence characteristic, comprising the steps of providing at least one electrode on top of the waveguide, and applying power equal to or above a predetermined power level to said at least one electrode for causing a change of the refractive indices of the waveguide.
1. A method for trimming birefringence of an integrated optical device with at least one waveguide having a birefringence characteristic, comprising the steps:
providing at least one electrode on top of the waveguide; and
applying power equal to or above a predetermined power level to said at least one electrode to heat a region of the waveguide for causing an irreversible birefringence change of the waveguide.
2. The method of claim 1 , characterized in that said integrated optical device is an optical filter device.
3. The method of claim 2 , characterized in that said integrated optical device is a thermo optical device.
4. The method of claim 3 , characterized in that said optical filter is a Mach-Zehnder Interferometer or a ring resonator.
5. The method of claim 1 , characterized by the step:
measuring the birefringence change, preferably with said at least one electrode by supplying electrical power to said electrode.
6. The method of claim 1 , characterized in that said predetermined power level is 0.8 W/mm.
7. The method of claim 1 , characterized in that said electrode is provided as a metal electrode, preferably as a chromium heater electrode.
8. The method of claim 1 , wherein the heat causes a change of a stress distribution in the waveguide.
9. The method of claim 1 , wherein the region of the waveguide is below the at least one electrode.
10. The method of claim 1 , wherein the region of the waveguide is heated to a temperature of more than 200° C.
11. An optical device for switching or filtering light passing through a waveguide having a birefringence characteristic, wherein the waveguide has been treated by providing at least one electrode on top of the waveguide and applying power equal to or above a predetermined power level to said at least one electrode to heat a region of the waveguide for causing an irreversible birefringence change of the waveguide.
12. The optical device of claim 11 , characterized in that said waveguide has a core layer sandwiched between a cladding layer, wherein both layers are made of a silica based material and the cladding is highly doped with a material adapted to balance stresses for TE and TM polarization modes.
13. The optical device of claim 11 , characterized in that it is a Mach-Zehnder interferometer.
14. The optical device of claim 11 , characterized in that it is a ring resonator.