Thin Shallow-Ridge Silicon-on-Insulator Waveguide Transitions and Tapers

We analyze transitions from low-loss “magic” width to strongly radiating “anti-magic” width thin, shallow-ridge silicon-on-insulator waveguides operating in the transverse magnetic mode, using a vector eigenmode expansion method. It is shown that the transition produces a beam of transverse electric (TE) radiation with a pattern, which is strongly dependent on the geometry of the transition. It is shown that controlled, highly coherent, and low-divergence TE beam can be emitted from a relatively compact linear taper. Methods for side lobe suppression are also analyzed and avenues for more sophisticated beam shaping are identified drawing inspiration from leaky wave antennas.