title: Dimensional variation tolerant silicon-on-insulator directional couplers.
abstract: We design silicon ridge/rib waveguide directional couplers which are simultaneously tolerant to width, height, coupling gap, and etch depth variations. Using wafer-scale measurements of structures fabricated in the IMEC Standard Passives process, we demonstrate the normalized standard deviation in the per-length coupling coefficient (a metric for the splitting ratio variation) of the variation-tolerant directional couplers is up to 4 times smaller than that of strip waveguide designs. The variation-tolerant couplers are also the most broadband and the deviation in the coupling coefficient shows the lowest spectral dependence.
authors.forename: Jared C
authors.initials: JC
authors.lastname: Mikkelsen
authors.forename: Wesley D
authors.initials: WD
authors.lastname: Sacher
authors.forename: Joyce K S
authors.initials: JK
authors.lastname: Poon