Integrated optical device with reduced waveguide birefringence

A method of fabricating an integrated optical component comprising the steps of:

• providing a substrate, at least a face of the substrate having a first cladding layer disposed thereon;
• forming a core material layer on the first cladding layer;
• forming a plurality of different optical devices on the substrate, each device comprising a plurality of waveguides, each waveguide comprising a waveguide core formed in the core material layer and disposed on a respective mesa formation formed in the first cladding layer;
• wherein
• the method includes the step of selecting an optimum height for the mesa formations in a first said optical device so as to achieve a desired level of waveguide birefringence in said first device, and optimizing the waveguide birefringence of at least one other said optical device so as to obtain a required level of waveguide birefringence in the integrated optical component;
• and
• forming all the waveguides in one said device to have a different height of mesa formation to the waveguides in at least one other said device, wherein the respective mesa heights in at least two said optical devices are selected so that the waveguide birefringence in one said device is of substantially equal magnitude but opposite sign to the waveguide birefringence in the other said device.