Compact and power-efficient 3 × 3 silicon photonic interferometer thermo-optic switch

A thermo-optic 3 × 3 interferometer switch is proposed and demonstrated experimentally on silicon photonic platform. The switch is composed of two 3 × 3 multi-mode interferometer (MMI) and three interferometer arms equipped with spiral thermo-optic phase shifters (STOPS). The switching operation of the device is successfully demonstrated by heating the STOPS. For the fabricated optical switch, experimental measurements indicate that the excess losses at all output ports are approximately 3 dB and a maximum crosstalk of about 52 dB among different output ports is achieved at 1543.3 nm. The operating bandwidth, which is defined as the 3 dB optical bandwidth of the transmission passband at the ON state, is about 250 GHz. Furthermore, thanks to the well-designed STOPS, the maximum power consumption of the fabricated optical switch is about 4.6 mW, while the footprint is as small as 0.4 mm². The device has potential in configurable large scale on-chip optical switch fabrics.