High-efficiency focusing metalens based on metagrating arrays

Jia Shi; Guanlong Wang; Longhuang Tang; Xiang Wang; Shaona Wang; Cuijuan Guo; Hua Bai; Pingjuan Niu; Jianquan Yao; Jidong Weng

doi:10.1364/PRJ.542798

Photonics Research, Volume. 13, Issue 2, 351(2025)

High-efficiency focusing metalens based on metagrating arrays

Jia Shi^1,2、*, Guanlong Wang¹, Longhuang Tang^3,4, Xiang Wang³, Shaona Wang¹, Cuijuan Guo¹, Hua Bai¹, Pingjuan Niu¹, Jianquan Yao², and Jidong Weng³

Author Affiliations

¹Tianjin Key Laboratory of Optoelectronic Detection Technology and System, School of Electronic and Information Engineering, Tiangong University, Tianjin 300387, China

²Key Laboratory of Opto-Electronics Information Technology (Ministry of Education), School of Precision Instruments and Opto-Electronic Engineering, Tianjin University, Tianjin 300072, China

³Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China

⁴e-mail: tanglonghuang@tju.edu.cn

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Figures & Tables(9)

$(a) The model of electromagnetic wave normal incidence into a metagrating array. (b) The schematic diagram of an asymmetric unit cell. (c) The bending angles of T−1 order with different diffraction periods Px. (d) The top view and (e) the section view of the schematic diagram of a metalens.$

Fig. 1. (a) The model of electromagnetic wave normal incidence into a metagrating array. (b) The schematic diagram of an asymmetric unit cell. (c) The bending angles of T−1 order with different diffraction periods Px. (d) The top view and (e) the section view of the schematic diagram of a metalens.

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$The schematic simulated electric field distributions of bending incident terahertz waves to different angles with different diffraction periods of 5.22 mm, 6.10 mm, 7.76 mm, and 16.47 mm. (a) Px1, (b) Px2, (c) Px3, and (d) Px4.$

Fig. 2. The schematic simulated electric field distributions of bending incident terahertz waves to different angles with different diffraction periods of 5.22 mm, 6.10 mm, 7.76 mm, and 16.47 mm. (a) Px1, (b) Px2, (c) Px3, and (d) Px4.

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$(a) The manipulation efficiency and (b) diffraction efficiency of T−1 order at different frequencies for the diffraction period Px2 with different parameters h and g. (c) The transmission spectra of different diffraction orders of diffraction period Px2. (d) The manipulation efficiency and (e) the diffraction efficiency of diffraction period Px2 with different geometrical parameters Δd, g, and h at 0.14 THz.$

Fig. 3. (a) The manipulation efficiency and (b) diffraction efficiency of T−1 order at different frequencies for the diffraction period Px2 with different parameters h and g. (c) The transmission spectra of different diffraction orders of diffraction period Px2. (d) The manipulation efficiency and (e) the diffraction efficiency of diffraction period Px2 with different geometrical parameters Δd, g, and h at 0.14 THz.

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$(a) The efficiencies of designed unit cells with the highest manipulation efficiency and (b) the highest diffraction efficiency optimization methods. (c) The simulated electric field distribution of the metalens with the highest manipulation efficiency and (d) the highest diffraction efficiency.$

Fig. 4. (a) The efficiencies of designed unit cells with the highest manipulation efficiency and (b) the highest diffraction efficiency optimization methods. (c) The simulated electric field distribution of the metalens with the highest manipulation efficiency and (d) the highest diffraction efficiency.

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$(a) The microscope images of fabricated metalenses with the metalens designed with the highest manipulation efficiency and (b) the highest diffraction efficiency. (c) The schematic diagram of the scanning transmission system for the characterization of the metalens. (d) The normalized intensity distributions of the focal spot measured by the knife-edge method in x−y plane of the metalens with the highest manipulation efficiency and (e) the metalens with the highest diffraction efficiency. (f) The experimental measurement normalized intensity distributions of the depth of focus along z-axis of the metalens with the highest manipulation efficiency and (g) the metalens with the highest diffraction efficiency.$

Fig. 5. (a) The microscope images of fabricated metalenses with the metalens designed with the highest manipulation efficiency and (b) the highest diffraction efficiency. (c) The schematic diagram of the scanning transmission system for the characterization of the metalens. (d) The normalized intensity distributions of the focal spot measured by the knife-edge method in x−y plane of the metalens with the highest manipulation efficiency and (e) the metalens with the highest diffraction efficiency. (f) The experimental measurement normalized intensity distributions of the depth of focus along z-axis of the metalens with the highest manipulation efficiency and (g) the metalens with the highest diffraction efficiency.

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$(a) The experimental configuration of transmission terahertz imaging system. (b), (c) The transmitted terahertz image of the marked area of USAF 1951 test chart demonstrated by the metalens with the highest manipulation efficiency, and with (d), (e) the highest diffraction efficiency. (f) Normalized distribution of intensity along the white dashed line of the longitudinal and (g) transverse signals with the highest manipulation and diffraction efficiencies in the transmitted image.$

Fig. 6. (a) The experimental configuration of transmission terahertz imaging system. (b), (c) The transmitted terahertz image of the marked area of USAF 1951 test chart demonstrated by the metalens with the highest manipulation efficiency, and with (d), (e) the highest diffraction efficiency. (f) Normalized distribution of intensity along the white dashed line of the longitudinal and (g) transverse signals with the highest manipulation and diffraction efficiencies in the transmitted image.

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Table 1. Design Parameters of Each Diffraction Period with Two Optimization Methods

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Table 1. Design Parameters of Each Diffraction Period with Two Optimization Methods

	Unit Cell	$P_{x}$ (mm)	$n$	$d_{1}$ (mm)	$Δ d$ (mm)	$h$ (mm)	$g$ (mm)
Metalens with the highest manipulation efficiency	$P_{x 1}$	5.22	2	1	0.6	2.6	0.7
	$P_{x 2}$	6.10	2	1	0.5	2.7	1
	$P_{x 3}$	7.76	2	1	0.7	2.7	0.8
	$P_{x 4}$	16.47	8	0.5	0.2	2.8	0.3
Metalens with the highest diffraction efficiency	$P_{x 1}$	5.22	2	1	0.6	2.5	0.5
	$P_{x 2}$	6.10	2	1	0.5	2.6	0.9
	$P_{x 3}$	7.76	2	1	0.7	2.5	0.5
	$P_{x 4}$	16.47	8	0.5	0.2	2.9	0.2

Table 2. Statistical Analysis of the Fabrication Errors

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Table 2. Statistical Analysis of the Fabrication Errors

	Unit Cell	$d_{1}$ (μm)		$Δ d$ (μm)		$g$ (μm)
	Unit Cell	Design	Fabrication Error	Design	Fabrication Error	Design	Fabrication Error
Metalens with the highest manipulation efficiency	$P_{x 1}$	1000	$\pm 24.6$	600	$\pm 19.1$	700	$\pm 32.6$
	$P_{x 2}$	1000	$\pm 36.9$	500	$\pm 21.6$	1000	$\pm 38.5$
	$P_{x 3}$	1000	$\pm 32.3$	700	$\pm 29.1$	800	$\pm 34.2$
	$P_{x 4}$	500	$\pm 35.1$	200	$\pm 27.6$	300	$\pm 32.4$
Metalens with the highest diffraction efficiency	$P_{x 1}$	1000	$\pm 28.4$	600	$\pm 18.5$	500	$\pm 25.4$
	$P_{x 2}$	1000	$\pm 30.6$	500	$\pm 28.7$	900	$\pm 29.3$
	$P_{x 3}$	1000	$\pm 26.6$	700	$\pm 38.3$	500	$\pm 30.0$
	$P_{x 4}$	500	$\pm 39.1$	200	$\pm 21.6$	200	$\pm 36.4$

Table 3. Performance Comparison with Some Published Results

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Table 3. Performance Comparison with Some Published Results

Reference	Materials	Diffraction Efficiency	Manipulation Efficiency	DOF	Focal Spot Diameter
[42]	$Si / {SiO}_{2}$	47.2%	34.9%	$7.89 λ$	$1.11 λ$
[59]	Si	-	35%	$23 λ$	$\sim 2.3 λ$
[60]	Si	-	75.3%	$4.8 λ$	$\sim 0.97 λ$
[61]	$Si / {SiO}_{2}$	-	43.1%	$1.23 λ$	$\sim 1 λ$
[62]	$Au / {SiO}_{2}$	-	61.62%	-	$\sim 1.73 λ$
[63]	Graphene/Si	-	-	$\sim 8.54 λ$	$1.72 λ$
[64]	Si	-	95%	$\sim 3.2 λ$	$1.48 λ$
[65]	Si	-	$< 90 %$	-	$1.15 λ$
[66]	Si	-	60%	$\sim 21.3 λ$	$1.01 λ$
Metalens 1 (this work)	Resin	58.3%	98.1%	$22.7 λ$	$0.93 λ$
Metalens 2 (this work)	Resin	62.5%	94.6%	$24.6 λ$	$0.91 λ$

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Jia Shi, Guanlong Wang, Longhuang Tang, Xiang Wang, Shaona Wang, Cuijuan Guo, Hua Bai, Pingjuan Niu, Jianquan Yao, Jidong Weng, "High-efficiency focusing metalens based on metagrating arrays," Photonics Res. 13, 351 (2025)

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Paper Information

Category:

Received: Sep. 20, 2024

Accepted: Nov. 13, 2024

Published Online: Jan. 16, 2025

The Author Email: Jia Shi (shijia@tiangong.edu.cn)

DOI:10.1364/PRJ.542798

Topics

laser devices and laser physics

Lasers and Laser Optics

Laser physics

laser manufacturing

Instrumentation, Measurement and Metrology