InP/InGaAsP wafer-bonded vertically coupled X-crossing multiple channel optical add-drop multiplexer

A vertically coupled InP/InGaAsP crossed waveguide optical add-drop multiplexer (OADM) has been realized through the use of wafer bonding. Designed for signals in the 1550-nm range, this novel device requires only a single epitaxial growth and illustrates the use of vertical optical interconnects for the three-dimensional routing of optical signals. To our knowledge, it is also one of the first optical vertically coupled devices with no horizontally coupled counterpart.