Numerical modeling of passive duplexers using the finite-element method

A new technique is presented for the design and characterization of passive duplexers employing multimode interference-based devices with two-dimensional confinement using silica-on-silicon technology. The size of the device is compared with that from previously published results, based on directional couplers, and the proposed design is shown to be shorter. The polarization and the cross-talk properties of such multimode interference-based devices have also been verified as being satisfactory.