120° Hybrid for Bimodal Interferometers

An 120° hybrid for bimodal interferometers in the 220 nm silicon-on-insulator technology is presented. Three output signals enable an unambiguous phase detection over a 360°-range as well as a constant sensitivity. The length of the hybrid is only 190 μm with a simulated excess loss of 0.16 dB. Measurements combined with digital signal processing verify the functionality of a fabricated 120° hybrid.