On-chip silicon photonic controllable 2\u2009×\u20092 four-mode waveguide switch

Abstract

Multimode optical switch is a key component of mode division multiplexing in modern high-speed optical signal processing. In this paper, we introduce for the first time a novel 2\u2009×\u20092 multimode switch design and demonstrate in the proof-of-concept. The device composes of four Y-multijunctions and 2\u2009×\u20092 multimode interference coupler using silicon-on-insulator material with four controllable phase shifters. The shifters operate using thermo-optic effects utilizing Ti heaters enabling simultaneous switching of the optical signal between the output ports on four quasi-transverse electric modes with the electric power consumption is in order of 22.5 mW and the switching time is 5.4\xa0µs. The multimode switch exhibits a low insertion loss and a low crosstalk below −\u20093\xa0dB and −\u200919\xa0dB, respectively, in 50\xa0nm bandwidth in the third telecom window from 1525 to 1575\xa0nm. With a compact footprint of 10\xa0µm\u2009×\u2009960\xa0µm, this device exhibits a relatively large width tolerance of\u2009±\u200920\xa0nm and a height tolerance of\u2009±\u200910\xa0nm. Furthermore, the conceptual principle of the proposed multimode switch can be reconfigurable and scalable in multifunctional on-chip mode-division multiplexing optical interconnects.