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Low polarization-dependent-loss double-layer grating coupler for three-dimensional photonic integration

Low polarization-dependent-loss double-layer grating coupler for three-dimensional photonic integration
Low polarization-dependent-loss double-layer grating coupler for three-dimensional photonic integration
Dense integration of silicon photonic devices is the key enabling technology for next-generation high-performance computers. In this paper, we propose a double-layer grating coupler for the future multi-layer photonic integrated system. With a pair of one-dimensional (1-D) gratings orthogonally vertical-stacked, the device can couple light between single-mode fiber and two separate waveguide layers, realizing polarization splitting and rotation in different layers simultaneously. Benefiting from the perfectly vertical coupling scheme and optimal fiber position (OFP) overlapping design, the coupling efficiency peak of the upper and lower grating are calculated to be 28% and 25% respectively. Assisted with a DBR bottom mirror, the coupling efficiency of the two gratings can be further enhanced to 33.2% and 28.9% respectively. For real application, the misalignment tolerance on grating overlapping and the incidence angle are carefully investigated. To achieve power balance between the two grating layers, the impact of top cladding thickness is analyzed and an optimized thickness of 0.6 µm is chosen. From the simulation result of a back-to-back DLGC circuit, the coupling performance shows considerable robustness to the input polarization state and the PDL is under 0.5 dB within the wavelength range from 1536 nm to 1558 nm. Such a device can be a very promising solution to achieve polarization-independent coupling in the future three-dimensional (3-D) high density photonic integrated circuits.
0030-4018
247-254
Zhang, Zanyun
7d5e0026-6f42-4bc6-b7d7-d8f814307f8c
Zhu, Hua
2f054f54-940c-42bb-a681-0400d55d3ae1
Cheng, Qian
53938597-7e9c-4003-bf85-b193b4232710
Huang, Beiju
ce385b4e-2ef7-41fb-a568-2ada9e13cdd3
Cheng, Chuantong
d16546a7-69f1-430b-aaf4-f3d9a7bbc452
Li, Hongqiang
61fdb586-d85b-405f-b15f-a920f7a8e95c
Chen, Hongda
eec58f53-9d2c-40b3-9710-ae3518844270
Zhang, Zanyun
7d5e0026-6f42-4bc6-b7d7-d8f814307f8c
Zhu, Hua
2f054f54-940c-42bb-a681-0400d55d3ae1
Cheng, Qian
53938597-7e9c-4003-bf85-b193b4232710
Huang, Beiju
ce385b4e-2ef7-41fb-a568-2ada9e13cdd3
Cheng, Chuantong
d16546a7-69f1-430b-aaf4-f3d9a7bbc452
Li, Hongqiang
61fdb586-d85b-405f-b15f-a920f7a8e95c
Chen, Hongda
eec58f53-9d2c-40b3-9710-ae3518844270

Zhang, Zanyun, Zhu, Hua, Cheng, Qian, Huang, Beiju, Cheng, Chuantong, Li, Hongqiang and Chen, Hongda (2019) Low polarization-dependent-loss double-layer grating coupler for three-dimensional photonic integration. Optics Communications, 445, 247-254. (doi:10.1016/j.optcom.2019.04.034).

Record type: Article

Abstract

Dense integration of silicon photonic devices is the key enabling technology for next-generation high-performance computers. In this paper, we propose a double-layer grating coupler for the future multi-layer photonic integrated system. With a pair of one-dimensional (1-D) gratings orthogonally vertical-stacked, the device can couple light between single-mode fiber and two separate waveguide layers, realizing polarization splitting and rotation in different layers simultaneously. Benefiting from the perfectly vertical coupling scheme and optimal fiber position (OFP) overlapping design, the coupling efficiency peak of the upper and lower grating are calculated to be 28% and 25% respectively. Assisted with a DBR bottom mirror, the coupling efficiency of the two gratings can be further enhanced to 33.2% and 28.9% respectively. For real application, the misalignment tolerance on grating overlapping and the incidence angle are carefully investigated. To achieve power balance between the two grating layers, the impact of top cladding thickness is analyzed and an optimized thickness of 0.6 µm is chosen. From the simulation result of a back-to-back DLGC circuit, the coupling performance shows considerable robustness to the input polarization state and the PDL is under 0.5 dB within the wavelength range from 1536 nm to 1558 nm. Such a device can be a very promising solution to achieve polarization-independent coupling in the future three-dimensional (3-D) high density photonic integrated circuits.

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More information

Accepted/In Press date: 8 April 2019
e-pub ahead of print date: 20 April 2019
Published date: 15 August 2019
Additional Information: Zanyun Zhang was an academic Visitor in the Nanophotonics Group (ZIPN) with prof N.I.Zheludev

Identifiers

Local EPrints ID: 446850
URI: http://eprints.soton.ac.uk/id/eprint/446850
ISSN: 0030-4018
PURE UUID: ada03177-3b24-40c7-a37e-bba8fc96a774

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Date deposited: 24 Feb 2021 17:31
Last modified: 16 Mar 2024 08:22

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Contributors

Author: Zanyun Zhang
Author: Hua Zhu
Author: Qian Cheng
Author: Beiju Huang
Author: Chuantong Cheng
Author: Hongqiang Li
Author: Hongda Chen

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