Ultra-compact dual-mode mode-size converter for silicon photonic few-mode fiber interfaces

Fiber couplers usually take a lot of space on photonic integrated circuits due to the large mode-size mismatch between the waveguide and fiber, especially when a fiber with larger core is utilized, such as a few-mode fiber. We demonstrate experimentally that such challenge can be overcome by an ultr...

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Bibliographic Details
Published in:Optics express 2021-10, Vol.29 (21), p.33728-33740
Main Authors: Cheng, Lirong, Mao, Simei, Chen, Zhenmin, Wang, Yinghui, Zhao, Caiyue, Fu, H. Y.
Format: Article
Language:English
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Summary:Fiber couplers usually take a lot of space on photonic integrated circuits due to the large mode-size mismatch between the waveguide and fiber, especially when a fiber with larger core is utilized, such as a few-mode fiber. We demonstrate experimentally that such challenge can be overcome by an ultra-compact mode-size converter with a footprint of only 10 µm. Our device expands TE 0 and TE 1 waveguide modes simultaneously from a 1-µm wide strip waveguide to an 18-µm wide slab on a 220-nm thick silicon-on-insulator, with calculated losses of 0.75 dB and 0.68 dB, respectively. The fabricated device has a measured insertion loss of 1.02 dB for TE 0 mode and 1.59 dB for TE 1 mode. By connecting the ultra-compact converter with diffraction grating couplers, higher-order modes in a few-mode fiber can be generated with a compact footprint on-chip.
ISSN:1094-4087
1094-4087
DOI:10.1364/OE.438839