Scalable silicon-based mode-order converters assisted by tapered metal strip layer

Abstract

On-chip multimode applications require efficient mode sources with various different mode-orders, so the scalable mode-order converters would be preferred but they are still not available at present. Here, we propose a scalable silicon-based mode-order conversion scheme that can achieve the mode-order conversion from input fundamental TE mode to arbitrary output higher-order TE mode in a conversion length of only 2.5 μm. Four higher-order modes (TE1 ∼ TE4) are analyzed as examples with mode conversion efficiencies >90%, crosstalks <−12 dB and insertion losses <2.8 dB, respectively. Further, the working bandwidths are relatively broad and fabrication tolerances are calculated in detail. With these features, such device scheme would help generate a serious of higher-order modes in compact sizes which would address the requirements of on-chip multimode applications, e.g., improving the mode channel numbers of on-chip mode-division multiplexing.