Symmetrical waveguide devices fabricated by direct UV writing

Power splitters and directional couplers fabricated by direct UV writing in index matched silica-on-silicon samples can suffer from an asymmetrical device performance, even though the UV writing is carried out in a symmetrical fashion. This effect originates from a reduced photosensitivity in the vicinity of previous exposed areas. The imbalance can be counteracted by an appropriate reduction of the applied scan velocity in areas, where a previous scan has been carried out nearby.