Abstract
Mode division multiplexing (MDM) technology provides a pathway to enhance channel capacity beyond wavelength division multiplexing, positioning it as a pivotal advancement for next generation optical communications. Mode filters are essential for the low-loss transmission of specific modes and the reduction of modal crosstalk, thereby enhancing the feasibility of MDM systems. Although suppressing high-order mode is relatively straightforward, effectively blocking low-order modes poses a more intricate challenge. In this paper, we introduce a high-order mode pass strategy, effectively blocking low-order modes using the unidirectional mode converters. Specifically, a TE1 high-order mode pass filter (HOMPF) is demonstrated on a silicon-on-insulator platform, utilizing a unique inverse-designed ultra-compact unidirectional TE0-TE1 mode converter. Experimental results show the TE1-TE1 insertion loss of the HOMPF of below 1.0 dB and an average TE0-TE0 extinction ratio of 36.8 dB (42.1 dB for 2-cascaded HOMPF) within the C-band range of 1525-1565 nm. Additionally, the scalability of the HOMPF structure is explored, with simulations demonstrating a TE2 HOMPF. The proposed HOMPFs feature simplicity, compactness, low loss, and high extinction ratio, making them promising components for mode manipulation in MDM systems.
Funder
National Natural Science Foundation of China
State Key Laboratory of Information Photonics and Optical Communications
Nature Science Basic Research Program of Shaanxi
Qin Chuang Yuan High-Level Innovative Entrepreneurial Talent Project
Fundamental Research Funds for the Central Universities