Integrated tunable optical add/drop filter for polarization and wavelength multiplexed signals

We propose and demonstrate an integrated tunable optical filter which is promising for reconfigurable optical add/drop multiplexer (ROADM) targeting polarization and wavelength multiplexed signals. The proposed filter is comprised of a polarization diversity scheme and two tunable microring resonators (MRRs). The polarization scheme is implemented by two dimensional (2D) grating couplers which are functioning as signals import, output and add/drop ports, while the MRRs are signals processing units. The add/drop function can be applied on either polarization tribute or any wavelength by controlling the resonate wavelengths of ring resonators. For demonstration, dual polarizations and four-wavelength signals are experimentally added and dropped with good performance and reasonable power penalties.