Metasurfaces integrated with a single-mode waveguide array for off-chip wavefront shaping

Chen, Siyu; Huang, Jianzhi; Yin, Shengqi; Milošević, Milan; Pi, Hailong; Yan, Jize; Chong, Harold M. H.; Fang, Xu

doi:10.1364/oe.488959

Cited by 6 publications

(4 citation statements)

References 49 publications

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“…All meta-waveguides, including both the phase gradient metawaveguides discussed in previous works [28] and the amplitude gradient meta-waveguides proposed here, are based on scattering a guided mode off chip using a series of meta-atoms. This scattering determines the off-chip wavefront shaping, but also leads to a detrimental shadowing effect [37]. As the residual intensity decreases further down the waveguide, the phase gradient approach always results in a limited effective aperture [28].…”

Section: Amplitude Gradient-based Metasurface Designmentioning

confidence: 99%

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Amplitude gradient-based metasurfaces for off-chip terahertz wavefront shaping

Lyu¹,

Huang²,

Yin³

et al. 2023

Photon. Res.

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Metasurfaces provide an effective technology platform for manipulating electromagnetic waves, and the existing design methods all highlight the importance of creating a gradient in the output phase across light scattering units. However, in the emerging research subfield of meta-waveguides where a metasurface is driven by guided modes, this phase gradient-oriented approach can only provide a very limited emission aperture, significantly affecting the application potential of such meta-waveguides. In this work, we propose a new design approach that exploits the difference between meta-atoms in their light scattering amplitude. By balancing this amplitude gradient in the meta-atoms against the intensity decay in the energy-feeding waveguide, a large effective aperture can be obtained. Based on this new design approach, three different wavefront shaping functionalities are numerically demonstrated here on multiple devices in the terahertz regime. They include beam expanders that radiate a plane wave, where the beam width can increase by more than 900 times as compared to the guided wave. They also include a metalens that generates a Bessel-beam focus with a width 0.59 times the wavelength, and vortex beam generators that emit light with a tunable topological charge that can reach −30. This amplitude gradient design approach could benefit a variety of off-chip light shaping applications such as remote sensing and 6G wireless communications.

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Section: Amplitude Gradient-based Metasurface Designmentioning

confidence: 99%

“…1), we can define a deflection angle α for the output light λ 0 with respect to the vertical z direction. This angle α can be expressed as [37] α arcsin λ 0 1…”

Section: Beam Expander As the First Functional Devicementioning

confidence: 99%

Amplitude gradient-based metasurfaces for off-chip terahertz wavefront shaping

Lyu¹,

Huang²,

Yin³

et al. 2023

Photon. Res.

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“…39−41 To mitigate the impact of inherent ohmic losses 42 in metal materials, subsequent works shift to dielectric waveguides to realize on-chip metasurfaces for holographic displays. Although single resonance phase modulation, 43,44 detour phase modulation, 30,32,45,46 and geometric phase modulation 34,47−49 have been verified in on-chip metasurfaces, the limitation of monotonic phase modulation inevitably introduces channel crosstalk in the process of implementing multidimensional multiplexing. Achieving independent control of phase and amplitude among different channels remains challenging, especially when facing illuminations from both free space and waveguide.…”

Section: Introductionmentioning

confidence: 99%

“…Incorporating metasurfaces into waveguide devices extends their applications, infusing fresh innovation into the realm of integrated optics; some typical applications are ultracompact wavelength or polarization demultiplexer, mode conversion, optical diodes, and radiation field control. − Based on the principle of resonance phase, on-chip focusing, beam steering, and polarization selection functions have been realized using metallic antennas. − To mitigate the impact of inherent ohmic losses in metal materials, subsequent works shift to dielectric waveguides to realize on-chip metasurfaces for holographic displays. Although single resonance phase modulation, , detour phase modulation, ,,, and geometric phase modulation ,− have been verified in on-chip metasurfaces, the limitation of monotonic phase modulation inevitably introduces channel crosstalk in the process of implementing multidimensional multiplexing. Achieving independent control of phase and amplitude among different channels remains challenging, especially when facing illuminations from both free space and waveguide.…”

Section: Introductionmentioning

confidence: 99%

Multifunctional Metasurface for Simultaneous Light Manipulation under Both Guided-Wave and Free-Space Incidence

Li,

Zhou,

et al. 2024

ACS Photonics

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Metasurfaces have outstanding capabilities in manipulating light, enabling functions such as focusing, vortex beam generation, and holography. Such versatile light manipulation, initially studied in free-space optics, has recently been explored in integrated photonics, with light control in waveguides. The ability to achieve multifunctional multiplexing stands is a significant advantage of metasurfaces, and investigating metasurfaces capable of simultaneously accommodating free-space light and guided waves holds the potential to enhance the information capacity and offer extensive application possibilities. However, research in this particular domain is limited, and achieving independent control of these two incident modes without introducing wavelength-dependent degrees of freedom remains a challenging frontier. To solve this problem, we combine the detour phase and resonant phase altogether into on-chip metasurfaces for the first time, which provides extra phase degrees of freedom for independent control of both on-ship and free-space channels. We propose and experimentally demonstrate this novel design with an on-chip multifunctional metasurface that enables the independent control of free-space light and guided waves without the need for introducing additional wavelength-related variables. By controlling the polarization of free-space light and incident direction of guided light, the designed device can achieve a recordhigh six-channel multifunctional multiplexing hologram and image display.

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Hypermultiplexed Off‐Chip Hologram by On‐Chip Integrated Metasurface

Liu,

Ma,

Zhang

et al. 2024

Advanced Optical Materials

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The waveguide‐integrated metasurface introduces a novel photonic chip capable of converting guided modes into free‐space light. This enables functions such as off‐chip beam focusing, steering, and imaging. The challenge lies in achieving hyper‐multiplexing across diverse parameters, including guided‐wave mode type, direction, polarization, and notably, multiple wavelengths. Here, a comprehensive end‐to‐end inverse design framework is introduced, rooted in a physical model, for the multifunctional design of on‐chip metasurfaces. This framework allows for metasurface optimization through a target‐field‐driven iteration process. A hypermultiplexed on‐chip metasurface capable of generating red‐green‐blue holograms at multiple target planes is demonstrated, with both independent and cooperative control over guided‐wave direction. Significantly, the proposed method streamlines the design process utilizing only the positions of meta‐atoms as the design variable. Nine independent holographic channels are demonstrated through a combination of wavelength and distance multiplexing. Moreover, by incorporating the excitation direction into the design, the metasurface produces a total of 36 distinct holograms. The robustness of these results against fabrication discrepancies is validated through 3D full‐wave electromagnetic simulations, aligning well with advanced manufacturing techniques. The research presents a universal design framework for the development of multifunctional on‐chip metasurfaces, opening up new avenues for a wide range of applications.

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Metasurfaces integrated with a single-mode waveguide array for off-chip wavefront shaping

Cited by 6 publications

References 49 publications

Amplitude gradient-based metasurfaces for off-chip terahertz wavefront shaping

Amplitude gradient-based metasurfaces for off-chip terahertz wavefront shaping

Multifunctional Metasurface for Simultaneous Light Manipulation under Both Guided-Wave and Free-Space Incidence

Hypermultiplexed Off‐Chip Hologram by On‐Chip Integrated Metasurface

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