Method and appertaining pair of mask patterns for fabricating, with the application of double masking, integrated optical waveguide structures

摘要

An alignment-tolerant fabrication of a waveguide structure having a symmetrical component structure and an asymmetrical component structure such as an asymmetrical X junction, with the aid of the technique of double masking is presented. The entire waveguide structure is defined by two different mask patterns (p1, p2) which are applied successively and in a mutually overlapping position. The two mask patterns are aligned with respect to one another according to alignment directions parallel (z-axis) and perpendicular (x-axis) to the axis of symmetry of the symmetrical component structure. Each mask pattern comprises a first asymmetrical component pattern (32;35) and a second asymmetrical component pattern (31,33; 34,36). The first component patterns (32 and 35) each define a separate portion of the asymmetrical component structure. The second component patterns ((31,33) and (34,36)) are mirror images of one another and comprise component shapes (33;36) which depend on a predefined alignment accuracy (w1) in the alignment direction perpendicular (x-axis) to the axis of symmetry.