Broadband 4 $\times$ 4 Nonblocking Silicon Electrooptic Switches Based on Mach–Zehnder Interferometers

We report a broadband 4 × 4 nonblocking optical switch with Mach-Zehnder interferometers (MZIs) as switch elements on a silicon platform. Silicon resistive heaters are used for phase error correction of MZI arms with total thermooptic power consumption of 33.7 mW. Fast switching is enabled by p-i-n diodes, with average electrooptic tuning power of 14.3 mW for the 24 essential switching states as required for nonblocking routing. The average on-chip insertion loss is 5.8-7.7 dB and crosstalk better than -12 dB at wavelength of 1550 nm. Optical transmission experiments using a high-throughput 50 Gb/s quadrature phase-shift keying (QPSK) optical signal reveal that no significant deterioration is observed on constellation diagrams.