Method for controlling the polarization of an optical signal and an optical component for polarization control of light in planar waveguides

1. Method for controlling the polarization of an optical signal transmitted through an optical waveguide core, comprising the steps of burying the optical waveguide core in a planar structure, and placing a plurality of stress-applying films on a surface of the structure in an asymmetrical manner with respect to the surface normal to the waveguide core and selectably operative to dynamically control the stress originating from said stress-applying films, so as to dynamically control the state of polarization applied to an optical signal passing through the waveguide core.

2. Method according to claim 1 , characterized in that said asymmetrical manner comprises placing said stress-applying films such that a well defined angle is created between principal axes of each variable birefringent waveguide segment.

3. Method according to claim 1 , characterized in that said stress-applying films comprise materials having a thermal expansion coefficient different from that of the underlying structure.

4. Method according to claim 1 , characterized in that said stress-applying films comprise a piezo-electric material.

5. Method according to claim 1 , characterized in that the stress-applying film comprises a gold layer having an electrical resistivity deposited on top of a chromium adhesion layer.

6. Method according to claim 1 , characterized in that the stress-applying film comprises a metal layer having an electrical resistivity on top of a layer of amorphous silicon.

7. Method according to claim 1 , characterized in arranging the films in groups each of which constitute a separate element for controlling waveguide birefringence.

8. An optical component comprising a polarization controller having an optical waveguide core buried in a planar structure, wherein a plurality of stress-applying films is placed on a surface of the structure in an asymmetrical manner with respect to a surface normal to the waveguide core and wherein at least one of the stress-applying films is selectably operative to dynamically control the stress originating from the at least one stress-applying films in response to a control signal applied to the at least one stress-applying film, so as to dynamically control the state of polarization of an optical signal transmitted through the waveguide core.

9. An optical component according to claim 8 , characterised in a substrate on which a glass buffer layer is deposited, said glass layer on its top has a glass topcladding with a buried waveguide core produced by a deposit-etch process, said glass topcladding on its top has a number of stress-applying films.

10. An optical component according to claim 8 , characterised in a substrate into which buried waveguide cores are produced by ion exchange, said substrate on its top has a number of stress-applying films.

11. An optical component according to claim 8 characterised in a substrate on which a layered glass structure is deposited, into which buried waveguide cores are produced UV-writing, said layered glass structure on its top has a numbers of stress-applying films.

12. An optical component according to claim 8 characterised in a substrate on which a polymer waveguide structure is produced, said polymer waveguide structure on its top has a number of stress-applying films.

13. An optical component according to claim 8 comprising a waveguide structure with a neglible inherent waveguide birefringence.

14. An optical component comprising a polarization controller prepared by the method according to claim 1 .