8-channel wavelength division multiplexer based on multimode interference couplers

An 8-channel wavelength division multiplexer with 2-nm channel spacing at 1546 nm is proposed. The device is based on the self-imaging effect in multimode waveguides, and design analysis is carried out in a material system with refractive index contrast equal to 1.96%. Simulated loss is less than 0.75 dB for all channels, and the -1-dB and -3-dB full width are 0.75 nm and 1.3 nm, respectively. Crosstalk is below -13 dB in a 0.75-nm-wide window at the neighboring channels. Polarizing change corresponds to a wavelength shift of less than 0.1 nm.<>