Fig. 1. (a) Schematic configuration of the sandwiched structure; field distributions for the (b) quasi-TE and (c) quasi-TM fundamental mode in a sandwiched waveguide ( ).

Fig. 2. Schematic configuration of the demultiplexer structure: (a) Top view; (b) cross section of the MMI waveguide.

Fig. 3. Beat length as a function of n (SiN_x) when the MMI width W_MMI is: (a) 3 µm; (b) 4 µm; (c) 5 µm.

Fig. 4. n(SiN_x) as functions of W_MMI when the demultiplexer is polarization-insensitive.

Fig. 5. (a) and (b) M as functions of W_MMI when the demultiplexer is polarization-insensitive.

Fig. 6. R as functions of W_MMI.

Fig. 7. Field distributions of the MMI demultiplexer: (a) Quasi-TE mode, at 1310 nm; (b) quasi-TM mode, at 1310 nm; (c) quasi-TE mode, at 1550 nm; (d) quasi-TM mode, at 1550 nm.

Fig. 8. Output powers (normalized to the input power) from Port2 and Port3 as the wavelength varies: (a) 1310 nm band; (b) 1550 nm band.

Fig. 9. Performance parameters as functions of L_MMI: (a) IL; (b) CT.

Fig. 10. Performance of parameters as functions of h(SiN_x): (a) IL; (b) CT.