Ultra Wideband Integrated 2x2 Optical Router Using Novel MMI Design

We propose a novel design of optical router or switch based on the multimode interference phenomenon in waveguide with parabolic index profile. A stair case index approximation of this index profile is utilized to facilitate the fabrication process. The fabrication of this profile is feasible through the current technology using multiple etching. A new design methodology is also proposed to ensure that the response of the stair case MMI (SCMMI) imitates the response of the parabolic MMI. In this methodology, a two-stage optimization procedure is exploited to obtain the optimal design. Gradient-based optimizers are utilized in these two stages exploiting the wide angle BPM. The required response gradient is efficiently obtained using the adjoint variable method. The proposed design has the ability to rout or switch any wavelength over a wide bandwidth.