Metal plasmonic assisted silicon-based TE0-to-TM1 mode-order converter with 3.5 μm length

Abstract

Faced with the increasing capacity requirements of on-chip optical interconnects, multiplexing technologies are emerging as attractive solutions. For the on-chip mode-division-multiplexing (MDM) transmission, the development of key mode conversion components takes dominance. Here, we propose a compact and efficient silicon-based TE0-to-TM1 mode-order converter, where a designed and optimized polygonal metal layer is deposited on the top surface of the input/output silicon nanowire. Due to the introduction of metal plasmonic effect and used segmental optimization ways for the top metal layer, the mode-order conversion length has been greatly shortened to only 3.5 μm. By analyzing the top metal layer pattern on the silicon nanowire in detail, we have achieved a silicon-based TE0-to-TM1 mode-order converter with its modal conversion efficiency, crosstalk and insertion loss of 94.2%, <−17 dB and <2.7 dB, respectively at the wavelength of 1.55 μm. Meanwhile, the device working bandwidth and fabrication tolerance of some key structural parameters are also studied. Further, the proposed device scheme can contribute to the development of other on-chip mode-order converters. Based upon these characteristics, we believe such device scheme could help to increase the transmission capacity of on-chip compact MDM systems by adding TM-polarized mode channels.