Generic Wavelength-routed Optical Router (GWOR) based on grating-assisted vertical couplers for multilayer optical networks

A Generic Wavelength-routed Optical Router (GWOR) based on grating-assisted vertical couplers is proposed to be used as 4 × 4 routing matrix in multilayer optical networks. The device exploits, as basic building blocks, four vertical grating-assisted couplers made of three vertically stacked waveguides. The central waveguide is patterned with a periodic Bragg grating that guarantees the wavelength routing of the signal at the Bragg wavelength. The design and the analysis of the grating-assisted vertical couplers, performed by two different numerical methods, the Bidirectional Beam Propagation Method based on the Method of Lines (MoL-BBPM) and the Finite Difference Time Domain (FDTD) method, are reported. Moreover, the GWOR matrix is analyzed, with a very limited computational effort, by suitably composing the numerically calculated transmittances of the 2 × 2 elementary building blocks. The proposed GWOR matrix achieves low values of the insertion loss (i.e. maximum insertion loss IL=0.2 dB) and crosstalk below - 15 dB.