Fabrication of arbitrarily narrow vertical dielectric slots in silicon waveguides

Slot waveguides are used for many photonic applications. However, existing fabrication techniques impose restrictions on the width of the slot region. Here we propose and experimentally demonstrate a fabrication process to realize an arbitrarily narrow vertical dielectric slot in a silicon waveguide. Using this fabrication method we have realized silicon slot waveguides with a 10 nm oxide slot region. The propagation loss of the fabricated slot waveguide was 1.36±0.3 dB/mm