Optical add/drop multiplexers based on X-crossing vertical coupler filters

A simple optical add/drop multiplexer (OADM) based on a X-crossing InGaAsP-InP vertical coupler filter is demonstrated. Laterally separated input and output waveguides and the X-crossing arrangement are achieved using wafer bonding. A sidelobe level of -26 dB and a coupling efficiency of 97% with the central wavelength at 1.56 μm were measured for an OADM with an X-crossing angle of 0.25.