Compact two-mode (de)multiplexer based on symmetric Y-junction and multimode interference waveguides.

A compact two-mode (de)multiplexer [(DE)MUX] based on symmetric Y-junction and multimode interference (MMI) waveguides was designed by 3D beam propagation method (BPM). The phase evolution in the structure was discussed in detail. Simulations show that the optical bandwidth is as large as 100 nm (1500 nm ~1600 nm). The two-mode (DE)MUX is very compact compared with the other kind of mode (DE)MUX. The length of the structure is only 48.8 μm. Simulation also shows the fabrication tolerance is as large as ± 75 nm.