Design of asymmetrical directional couplers on ridge and strip SOI technology with high-dimensional variation tolerance.

The supermode analysis of asymmetrical directional couplers (ADC) based on SOI technology for strip and ridge structures at 1550 nm is herein reported, targeting to reduce ADC device fabrication requirements. The reported analysis based on supermodes permits us to assess the sensitivity of the ADC coupling efficiency by calculating the index difference between even and odd supermodes. Optimum designs have been found for 100 and 400 nm gaps, respectively, capable of converting and (de) multiplexing both TE0 and TE1 modes taking into account the width, gap, height, and slab thickness variations produced with respect to the nominal design. (C) 2018 Optical Society of America