Integrated multimode interference couplers in silicon-on insulator

Silicon-on insulator (SOI) is an attractive platform for the fabrication of optoelectronic integrated circuit. Thin cladding layers (< 1.0 micrometer) can be used in SOI waveguide due to the large index step between Si and SiO2, making them compatible with the VLSI technology. Here we demonstrate the fabrication of 1 X 4 and 2 X 2 multimode interference (MMI) coupler based on SOI technology. Performances of the devices are analyzed. The minimum excess loss of the devices is about 1.8 dB. The devices show uniform power distribution.