Optical reflective metasurfaces based on mirror-coupled slot antennas

Sven Ebel; Yadong Deng; Mario Hentschel; Chao Meng; Sören im Sande; Harald Giessen; Fei Ding; Sergey I. Bozhevolnyi

doi:10.1117/1.APN.2.1.016005

Journals >Advanced Photonics Nexus >Volume 2 >Issue 1 >Page 016005 > Article

Advanced Photonics Nexus
Vol. 2, Issue 1, 016005 (2023)

Optical reflective metasurfaces based on mirror-coupled slot antennas

Sven Ebel^1、2, Yadong Deng¹, Mario Hentschel³, Chao Meng¹, Sören im Sande¹, Harald Giessen³, Fei Ding^1、*, and Sergey I. Bozhevolnyi^1、*

Author Affiliations

¹University of Southern Denmark, Center for Nano Optics, Odense, Denmark

²Kiel University, Institute for Experimental and Applied Physics, Kiel, Germany

³University of Stuttgart, Research Center SCoPE, 4th Physics Institute, Stuttgart, Germany

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DOI: 10.1117/1.APN.2.1.016005 Cite this Article Set citation alerts

Sven Ebel, Yadong Deng, Mario Hentschel, Chao Meng, Sören im Sande, Harald Giessen, Fei Ding, Sergey I. Bozhevolnyi. Optical reflective metasurfaces based on mirror-coupled slot antennas[J]. Advanced Photonics Nexus, 2023, 2(1): 016005 Copy Citation Text

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(a) Schematic of the basic MCSA unit cell consisting of a slot antenna on top of an SiO2 spacer and an Au mirror. (b) Numerically calculated complex reflection coefficients as a function of the slot antenna lateral dimensions at the design wavelength of λ=785 nm upon TM polarization. The SiO2 spacer thickness is set to ts=130 nm. The amplitude |rxx| is visualized by the color map, while the dashed blue lines are the contours of the reflection phase φxx ascending by a 20-deg phase step. (c) Cross-sectional electric field distributions in different cutting planes for the slot antenna with Lx=40 nm and Ly=150 nm at λ=785 nm. The selected cutting planes display the mode profiles within the center of the slot antenna in the top Au layer. The color bars are chosen for illustrating the mode amplitude profiles of the Ex-component, while arrows indicate the electric field vectors at a representative moment of time.

Fig. 1. (a) Schematic of the basic MCSA unit cell consisting of a slot antenna on top of an

{SiO}_{2}

spacer and an Au mirror. (b) Numerically calculated complex reflection coefficients as a function of the slot antenna lateral dimensions at the design wavelength of

λ = 785 nm

upon TM polarization. The

{SiO}_{2}

spacer thickness is set to

t_{s} = 130 nm

. The amplitude

| r_{x x} |

is visualized by the color map, while the dashed blue lines are the contours of the reflection phase

φ_{x x}

ascending by a 20-deg phase step. (c) Cross-sectional electric field distributions in different cutting planes for the slot antenna with

L_{x} = 40 nm

and

L_{y} = 150 nm

λ = 785 nm

. The selected cutting planes display the mode profiles within the center of the slot antenna in the top Au layer. The color bars are chosen for illustrating the mode amplitude profiles of the

E_{x}

-component, while arrows indicate the electric field vectors at a representative moment of time.

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(a), (b) Numerically calculated complex reflection coefficients as a function of the slot antenna’s lateral dimensions at the design wavelength of λ=785 nm upon TM polarization. The amplitude |rxx| is visualized by the color map, while the dashed blue lines are the contours of the reflection phase φxx ascending by (a) a 20-deg phase step and (b) a 10-deg phase step. The SiO2 spacer thickness is set to ts=50 nm in (a) and ts=10 nm in (b). (c), (d) Cross-sectional electric field distributions in different cutting planes for the slot antenna at λ=785 nm. The selected cutting planes display the mode profiles within the center of the slot antenna in the top Au layer. The color bars are chosen for illustrating the mode amplitude profiles of the Ex-component, while arrows indicate the electric field vectors at a representative moment of time. (c) The SiO2 spacer thickness is set to ts=50 nm and the slot-antenna dimensions are Lx=40 nm and Ly=150 nm. (d) The SiO2 spacer thickness is set to ts=10 nm and the slot-antenna dimensions are Lx=150 nm and Ly=230 nm.

Fig. 2. (a), (b) Numerically calculated complex reflection coefficients as a function of the slot antenna’s lateral dimensions at the design wavelength of

λ = 785 nm

upon TM polarization. The amplitude

| r_{x x} |

is visualized by the color map, while the dashed blue lines are the contours of the reflection phase

φ_{x x}

ascending by (a) a 20-deg phase step and (b) a 10-deg phase step. The

{SiO}_{2}

spacer thickness is set to

t_{s} = 50 nm

in (a) and

t_{s} = 10 nm

in (b). (c), (d) Cross-sectional electric field distributions in different cutting planes for the slot antenna at

λ = 785 nm

. The selected cutting planes display the mode profiles within the center of the slot antenna in the top Au layer. The color bars are chosen for illustrating the mode amplitude profiles of the

E_{x}

-component, while arrows indicate the electric field vectors at a representative moment of time. (c) The

{SiO}_{2}

spacer thickness is set to

t_{s} = 50 nm

and the slot-antenna dimensions are

L_{x} = 40 nm

and

L_{y} = 150 nm

. (d) The

{SiO}_{2}

spacer thickness is set to

t_{s} = 10 nm

and the slot-antenna dimensions are

L_{x} = 150 nm

and

L_{y} = 230 nm

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$Theoretical performance of the beam-steering MCSA metasurfaces that reflect the normal incident TM-polarized light into the +1 diffraction order for supercells consisting of (a) pair, (b) triple, and (c) quadruple identical MCSA meta-atoms. The left columns display the simulated diffraction efficiencies of different orders as a function of wavelength. The right columns show the electrical field distributions at the x–y plane cut from the center of the top slot-antenna layer at the wavelength of λ=785 nm.$

Fig. 3. Theoretical performance of the beam-steering MCSA metasurfaces that reflect the normal incident TM-polarized light into the +1 diffraction order for supercells consisting of (a) pair, (b) triple, and (c) quadruple identical MCSA meta-atoms. The left columns display the simulated diffraction efficiencies of different orders as a function of wavelength. The right columns show the electrical field distributions at the

x – y

plane cut from the center of the top slot-antenna layer at the wavelength of

λ = 785 nm

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$(a) Schematic illustration of the MCSA reflective metasurface for beam steering. (b) SEM images of the fabricated beam-steering metasurface. The lower image depicts the fabricated supercells. (c) Simulated (solid lines) and experimental (dots with error bars) diffraction efficiencies of different orders as a function of wavelength for TM incident light. The error bars denote the standard deviation of the measured data of four metasurface samples. The inset image shows the diffracted light spots at λ=790 nm, whose intensity has been adjusted for the visualization.$

Fig. 4. (a) Schematic illustration of the MCSA reflective metasurface for beam steering. (b) SEM images of the fabricated beam-steering metasurface. The lower image depicts the fabricated supercells. (c) Simulated (solid lines) and experimental (dots with error bars) diffraction efficiencies of different orders as a function of wavelength for TM incident light. The error bars denote the standard deviation of the measured data of four metasurface samples. The inset image shows the diffracted light spots at

λ = 790 nm

, whose intensity has been adjusted for the visualization.

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$(a) Schematic illustration of the MCSA reflective metasurface for beam splitting. (b) SEM images of the fabricated beam-splitting metasurface. The lower image shows the designed and fabricated supercells. (c) Simulated (solid lines) and experimental (dots with error bars) diffraction efficiencies of different orders as a function of wavelength for TM incident light. The error bars denote the standard deviation of the measured data of four metasurface samples. The inset image shows the diffracted light spots at λ=790 nm, whose intensity has been adjusted for the visualization.$

Fig. 5. (a) Schematic illustration of the MCSA reflective metasurface for beam splitting. (b) SEM images of the fabricated beam-splitting metasurface. The lower image shows the designed and fabricated supercells. (c) Simulated (solid lines) and experimental (dots with error bars) diffraction efficiencies of different orders as a function of wavelength for TM incident light. The error bars denote the standard deviation of the measured data of four metasurface samples. The inset image shows the diffracted light spots at