Wide-Angle Low-Loss 1×2 Multimode Interference Optical Power Divider with Tilted Input and Output Waveguides

Multimode interference (MMI) coupler with tilted input/output waveguides is proposed. By the self-imaging theory of MMI couplers, the output fields at the end of the multimode region have tilted phase fronts and automatically propagate toward the branching waveguides. The waveguides with layered structure and vertical sidewalls are used to simulate the proposed device. The excess loss is only 0.24 dB even though the branch angle is 20 degrees.