4 × 4 Nonblocking Silicon Thermo-Optic Switches Based on Multimode Interferometers

We experimentally demonstrate a silicon 4 × 4 nonblocking thermo-optic (TO) switch using a generalized Mach-Zehnder interferometer constructed on multimode interferometers. All the 24 switching states for nonblocking switching are characterized. The device fabricated using CMOS technologies has a footprint of 2.8 × 0.65 mm
²
. The measured average on-chip insertion loss is 9 ± 2 dB and the crosstalk for all switching states is better than -12 dB. The average TO switching power consumption is 109 mW. The switching functionality is verified by transmission of a 40-Gb/s quadrature phase-shift keying optical signal.