Tailoring of dispersion in silicon vertical slot waveguides

For applications in light modulation, biosensing and optical non-linearities on a silicon photonic platform, it is often advantageous to guide the modal power in the lower index cladding material whose properties are tailored for that particular application[ 1,2]. A convenient way of integrating such a scheme is the use of silicon slot waveguides, where two parallel rails, separated by a lower index slot region, confine a proportion of the modal power in the low index material. However, so far, little attention has been paid to the dispersion of the waveguides and the effect this will have on any guided wave processes. In this work we designed, fabricated and measured a range of slot waveguides on Silicon On Insulator (SOI) with varying rail and slot widths to assess their effects on the waveguide dispersion. Zero Group Velocity Dispersion (GVD) points are demonstrated along with a wide range of dispersion conditions that show a strong dependence on the slot waveguide geometry.