Patent ID: 8295656

Claim:
A method for compensating the polarization-dependent shift of the center frequency of an optical filter, the filter comprising an interferometer which comprises at least an upper and a lower arm, at least one of these arms comprising at least one waveguide, and at least one half-wave plate being arranged in the at least one waveguide of the interferometer wherein the method comprises the step of bringing at least a section of the at least one waveguide on the right and left of the half-wave plate to a pre-selectable temperature, wherein at least one section on the right of the half-wave plate is brought to a first temperature T 1 and at least one section on the left of the half-wave plate is brought to a second temperature T 2 wherein the at least one sections to the right and left of the half-wave plate each exhibit the equal length δ/1 and the first and second temperatures T 1 and T 2 satisfy the following condition: T 2 −T 1 =( B res /B WG )*Δ T Proc *(L/δ|1), wherein B res : denotes the birefringence corresponding to the residual polarization-dependent frequency shift B wo : denotes the birefringence of the waveguide, ΔT Proc : denotes the difference between the final temperature of a production process of the interferometer and the ambient temperature; L: is the length of the waveguide; and δ|1: is the length of the at least one section to the right and left of the half-wave plate.