Fig. 1. (a) Dispersion relation of MIM waveguide. (b) The field profile (Hy) of the first four TM modes in a 700 nm wide waveguide.

Fig. 2. Schematic of the MMI-based crossing.

Fig. 3. Calculated throughput and crosstalk for MMI-based crossing as function of the MMI length Lm. Here, ws=100  nm and Wm=560  nm.

Fig. 4. Field distribution (Hy) at λ=1550  nm for (a) MIM-based crossing and (b) direct crossing. (c) Throughput (solid lines) and crosstalk (dashed lines) for MIM-based crossing (blue lines) and direct crossing (red lines).

Fig. 5. Fabrication tolerance of the proposed MMI-based crossing when there is an MMI waveguide width variation ΔWm.