An MMI-based demultiplexer with reduced cross-talk

The crosstalk of a multimode interference (MMI)-based demultiplexer is reduced by connecting appropriately designed cascaded MMI filters of high-order. Numerical results show that the designed demultiplexer greatly improves the bandwidth of 20 dB cross-talk loss and has an excellent performance in terms of the insertion loss and chromatic dispersion. Formed with commonly used MMI couplers, the present structure is much easier to implement than other structures.