$4\times 4$ Silicon Optical Switches Based on Double-Ring-Assisted Mach–Zehnder Interferometers

We present the experimental demonstration of a 4 × 4 silicon electro-optic (EO) switch fabric based on a Benes architecture. Double-ring-assisted Mach-Zehnder interferometers (DR-MZIs) are utilized as the basic switch elements. Silicon resistive microheaters and p-i-n diodes are embedded in both of the microrings of the DR-MZIs for low-loss thermo-optic (TO) phase correction and high-speed switching operation, respectively. The TO tuning power dissipated to align all resonances is 22.37 mW. The maximum EO tuning power required to switch all DR-MZIs is only 1.38 mW. The average on-chip insertion loss is in the range of 4-5.8 dB for all switching states. The transmission spectrum measurement shows that the device can perform switching in a ~ 35 -GHz spectral window with the worst crosstalk being -18.4 dB.