A design of triplexer based on a 2×2 butterfly MMI coupler and a directional coupler using silicon waveguides

A novel ultra-compact triplexer is designed by basing it on a combination of a 2×2 generalized interference-multimode interference (GI-MMI) coupler. The MMI is formed into linear butterfly shape and a directional coupler using silicon rib waveguides. Firstly, the 2×2 MMI coupler is designed to separate the wavelength 1490 nm into one port and wavelengths of 1310 nm and 1550 nm into another port. Then a directional coupler is used to drop wavelengths of 1310 nm and 1550 nm to output ports individually. Numerical simulations with three-dimensional Beam Propagation Method (BPM) are utilized to design and optimize the operation of the proposed triplexer.