Silicon nitride based polarization-independent 4 × 4 optical matrix switch

A polarization-independent 4 × 4 optical matrix switch based on a 580-nm-thick silicon nitride platform is designed and experimentally demonstrated. The switch is composed of four 2 × 2 Mach-Zehnder interferometers, with each integrated with a pair of Ti/Pt resistive micro-heaters. Polarization-independent performance can be realized with the power consumption for a single switching operation of less than 130 mW. The measured rise/fall time of the switch upon electrical tuning is about 24.5/30.5 μs, corresponding to a maximum switching speed of about 20 kHz. The insertion loss is about 7.2 dB for transverse electric light or 5.7 dB for transverse magnetic wave, with a polarization dependent loss of about 0.65 dB. The device performance can be further optimized and even large-scale silicon nitride polarization-insensitive electro-optical matrix switches can be expected for future optical communication applications.