Silicon Photonic Wavelength-Selective Switch Based on an Array of Adiabatic Elliptical-Microrings

A compact silicon photonic wavelength-selective switch (WSS) based on an array of elliptical microrings with adiabatically varied radii and widths is proposed and demonstrated experimentally. A 1×4 WSS is designed and realized by integrating four cells sharing the same bus waveguide. Particularly each cell contains four elliptical microring units corresponding to four wavelength-channels. For the fabricated WSS, the average excess loss at the output port of all the channels is measured to be less than 1 dB, while the crosstalk between adjacent channels is less than −20 dB. Leveraging the thermo-optic effect and fine wavelength-tuning linearity, precise alignment of the resonance peak can be implemented, enabling the selection of arbitrary wavelength-channel for any port. The fabricated WSS is used for realizing wavelength-selective data routing with 30 Gbps non-return-to-zero signals and open eye diagrams are obtained. The proposed architecture has excellent scalability, which can facilitate the development of reconfigurable optical add/drop multiplexers in wavelength-division-multiplexing systems, and is suitable for building large-scale optical data center interconnects.