By a method for controlling the state of polarization (SOP) of an optical signal
transmitted through an optical waveguide, the waveguide is buried in a planar structure
and a plurality of stress-applying films, having variable stress, are placed on
the top of the structure. Preferably the stress-applying films comprise materials
that have thermal expansion coefficients different from that of the planar structure
or comprise materials with piezoelectric properties. In this way it is possible
to produce a cascaded series of optical elements with variable linear birefringence
in a planar optical waveguide. Moreover according to the invention it is possible,
by the method according to the invention, to manufacture optical components having
an active polarisation controller.
