The work of Dong Yihang, a team master's student, on "Silicon-integrated high-speed mode and polarization switch-and-selector" has recently been accepted and published by the Journal of Semiconductor as a cover paper. This work was partially supported by the National Key R&D Program of China (2019YFB2203600), the National Natural Science Foundation of China (61975115/61835008/62035016), and the Shanghai Science and Technology Committee (2017SHZDZX03). The author proposed a high-speed mode and polarization switch based on a PN junction Mach-Zehnder structure on a silicon platform. This switch can route any of the four modes/polarization components (TE0, TE1, TM0, TM1) from any input port to any output port for both transmission and switching. The switch exhibits low loss and crosstalk and has a response time in the nanosecond range, providing an effective solution for increasing communication capacity in future high-speed optical networks. Furthermore, this solution can be easily extended to higher-order modes by using cascaded subwavelength gratings as directional couplers.
Abstract: On-chip optical communications are growingly aiming at multimode operation together with mode-division multiplexing to further increase the transmission capacity. Optical switches, which are capable of optical signals switching at the nodes, play a key role in optical networks. We demonstrate a 2 × 2 electro-optic Mach–Zehnder interferometer-based mode- and polarization-selective switch fabricated by standard complementary metal–oxide–semiconductor process. An electro optic tuner based on a PN-doped junction in one of the Mach–Zehnder interferometer arms enables dynamic switching in 11 ns. For all the channels, the overall insertion losses and inter-modal crosstalk values are below 9.03 and –15.86 dB at 1550 nm, respectively.
Paper DOI：10.1088/1674-4926/43/2/022301 Paper link