Double-groove rectangular gratings for high-efficiency wideband vertical coupling in planar-integrated optical systems

Guoqing Ma; Changhe Zhou; Yongfang Xie; Ge Jin; Rongwei Zhu; Jin Zhang; Junjie Yu; Guohai Situ

doi:10.3788/COL202220.090501

Journals >Chinese Optics Letters >Volume 20 >Issue 9 >Page 090501 > Article

Chinese Optics Letters
Vol. 20, Issue 9, 090501 (2022)

Double-groove rectangular gratings for high-efficiency wideband vertical coupling in planar-integrated optical systems

Guoqing Ma^1、2, Changhe Zhou^1、2, Yongfang Xie³, Ge Jin³, Rongwei Zhu^1、2, Jin Zhang¹, Junjie Yu^1、2、*, and Guohai Situ^1、2、**

Author Affiliations

¹Laboratory of Information Optics and Optoelectronic Technology, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China

²Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China

³Institute of Photonics Technology, Jinan University, Guangzhou 510000, China

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DOI: 10.3788/COL202220.090501 Cite this Article Set citation alerts

Guoqing Ma, Changhe Zhou, Yongfang Xie, Ge Jin, Rongwei Zhu, Jin Zhang, Junjie Yu, Guohai Situ. Double-groove rectangular gratings for high-efficiency wideband vertical coupling in planar-integrated optical systems[J]. Chinese Optics Letters, 2022, 20(9): 090501 Copy Citation Text

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Schematic diagram of the grating coupler based on the double-groove structure. The green arrow represents the polarization direction, port #1 represents the reflective 1st order, and ports #2, #3, and #4 represent the transmitted +1st, 0th, and −1st orders, respectively.

Fig. 1. Schematic diagram of the grating coupler based on the double-groove structure. The green arrow represents the polarization direction, port #1 represents the reflective 1st order, and ports #2, #3, and #4 represent the transmitted +1st, 0th, and −1st orders, respectively.

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Simulation results of the electric field inside the substrate with the double-groove grating coupler when the Gaussian wave from a single-mode fiber is normally incident with TE polarization. The inset (in the red box) is the enlarged electric field distribution within the grating region.

Fig. 2. Simulation results of the electric field inside the substrate with the double-groove grating coupler when the Gaussian wave from a single-mode fiber is normally incident with TE polarization. The inset (in the red box) is the enlarged electric field distribution within the grating region.

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Fig. 3. Relationship between the coupling efficiency calculated by the RCWA, SA algorithms as well as FEM, and the working wavelength λ (a) in the C band and (b) in the C+L band, and (c) electric field distribution diagram at the central wavelength of λ = 1550 nm.

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Fig. 4. Simulation results of 1000 samples of the grating couplers based on the Monte Carlo method. The average efficiencies of the couplers in the (a) C and (b) C+L bands for these 1000 samples; statistical distributions of the efficiency of these 1000 samples in the (c) C and (d) C+L bands.

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Band	$h_{1}$ (µm)	$h_{2}$ (µm)	$x_{1}$ (µm)	$x_{2}$ (µm)	$x_{3}$ (µm)	$Λ$ (µm)	$η_{TE}^{- 1}$ (%)	$η_{TE}^{1}$ (%)
C (1535–1565 nm)	0.331	0.29	0.147	0.873	1.109	1.467	97.3	1.5
C+L (1535–1625 nm)	0.341	0.27	0.148	0.893	1.137	1.476	92.8	1.6

Table 1. Structure Parameters and Diffraction Efficiencies of Two Double-Groove Grating Couplers Optimized for TE Polarization Working in the C and C+L Bands, Respectively