Ultra-Compact Mode-Division Multiplexed Photonic Integrated Circuit for Dual Polarizations

• Published in: Journal of lightwave technology Vol. 39; no. 18; pp. 5925 - 5932
• Main Authors: Liu, Yingjie, Wang, Zi, Liu, Yilin, Wang, Xi, Guo, Xiaoyuan, Li, Dongliang, Yao, Yong, Song, Qinghai, Du, Jiangbing, He, Zuyuan, Xu, Ke
• Format: Journal Article
• Language: English
• Published: New York IEEE 15.09.2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Crosstalk; Demultiplexers; Dual polarization (waves); dual-polarization; Insertion loss; Integrated circuits; Large scale integration; mode (de)multiplexer; multimode; Multiplexing; Optical communication; Optical device fabrication; Optical polarization; Optical waveguides; photonic integrated circuits; Photonics; Polarization; Power; Power splitters; Silicon; Silicon compounds; silicon photonics; Waveguides
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2021.3092941

Polarization and mode division multiplexing are powerful tools for large-capacity parallel optical communications. Dual-polarization and mode-division multiplexed silicon photonic integrated circuit with ultra-small footprint is proposed and experimentally demonstrated. The circuits consist of a mode multiplexer, 3-dB power splitter and two demultiplexers which can simultaneously handle TE 0 , TE 1 , TM 0 and TM 1 mode. Compared with conventional device structure, the device footprint is scaled down via pixelated waveguide meta-structure. The mode multiplexer and the splitter have a footprint of only 6.8 μm × 6 μm and 6 μm × 5.25 μm, respectively. The fabrication tolerance on the nanohole size variations are studied, and the fabricated devices are systematically characterized. The measured insertion losses of the multiplexer and 3-dB power splitter are below 1.4 dB and 4.5 dB for all four modes within the wavelength range from 1530 nm-1570 nm. In the meantime, the measured maximum inter-mode cross talk is below -15 dB over a 30 nm bandwidth. The experimental results also indicate the power imbalance of the splitter is within 0.4 dB from 1530 nm-1570 nm. Since the demonstrated polarization and mode handling devices via pixelated meta-structures occupy significantly smaller chip area than conventional wisdoms, this work shows the potential for large scale and dense integration of polarization and mode division multiplexing system on photonic chip.