Fig. 1. xy and yz dimensional diagram of a multimode waveguide

Fig. 2. Relationship between effective refractive index and waveguide width

Fig. 3. 1×2 MMI coupler

Fig. 4. Optical power distribution of MMI

Fig. 5. Coupling efficiency of multimode waveguide with different lengths

Fig. 6. Coupling efficiency of 1×2 MMI with different widths

Fig. 7. Schematic diagram of 1×2 taper MMI

Fig. 8. Comparison of coupling efficiency with and without taper

Fig. 9. Taper MMI area

Fig. 10. The coupling effective of taper MMI area