Integrated Resonant Unit of Metasurfaces for Broadband Efficiency and Phase Manipulation

Metalens, a prominent application of two-dimensional metasurfaces, has demonstrated powerful abilities even beyond traditional optical lenses. By manipulating the phase distribution of metalens composed of appropriately arranged nanoscale building blocks, the wavefront of incident wave can be controlled based on Huygens principle, thus achieving the desired reflected and transmitted wave for many different purposes. Metalenses will lead a revolution in optical imaging due to its flat nature and compact size, multispectral acquisition and even off-axis focusing. Here, we review the recent progress of metalenses presenting excellent properties, with a focus on the imaging application using these metalenses. We firstly discuss the mechanism for achieving metalenses with high efficiency, large numerical aperture, controlling the chromatic dispersion or monochromatic aberrations and large area fabrication. Then, we review several important imaging applications including wide-band focusing imaging, polarization dependent imaging, light field imaging and some other significant imaging systems in different areas. Finally, we make a conclusion with an outlook on the future development and challenges of this developing research field.

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“…4(a) and (b) [61] and in the visible wavelength range of 400 nm to 667 nm in Fig. 4(c) and (d) [62] with Fig. 4(e) and (f).…”

Section: Achromatic Metalensesmentioning

confidence: 67%

Imaging based on metalenses

et al. 2020

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“…In Figure 12B, GaN nano-posts and its inverse structures are used to realize various phase dispersions [141]. In addition to the aforementioned studies, visible metalenses with silicon nitride [142] or aluminum [144] have also been reported.…”

Section: Continuous-band Metalensesmentioning

confidence: 95%

“…After the demonstration of the broadband metalens with 60 nm bandwidth in the visible regime [139], many studies on broadband metalenses have been conducted in various frequency regimes such as the visible [11,[140][141][142][143][144], infrared [124,[145][146][147], and terahertz regimes [148]. Figures 12A,B show visible broadband metalenses using titanium dioxide (TiO 2 ) and gallium nitride, respectively [11,141].…”

Section: Continuous-band Metalensesmentioning

confidence: 99%

Broadband metamaterials and metasurfaces: a review from the perspectives of materials and devices

Jung

Park

et al. 2020

Nanophotonics

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AbstractMetamaterials can possess extraordinary properties not readily available in nature. While most of the early metamaterials had narrow frequency bandwidth of operation, many recent works have focused on how to implement exotic properties and functions over broad bandwidth for practical applications. Here, we provide two definitions of broadband operation in terms of effective material properties and device functionality, suitable for describing materials and devices, respectively, and overview existing broadband metamaterial designs in such two categories. Broadband metamaterials with nearly constant effective material properties are discussed in the materials part, and broadband absorbers, lens, and hologram devices based on metamaterials and metasurfaces are discussed in the devices part.

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“…Based on the geometric phase or Huygens type designs, it is considered as the critical component for the orbital angular momentum (OAM) optical devices . It has also provided many unique opportunities to fabricate optical devices never existed before, such as the optical cloak, negative refractive interface, high‐efficiency holography, achromatic metalens, and generation of vortex beams . In spite of its superior features, these metasurfaces can hardly achieve same transfer efficiency as the classic optical materials (transfer efficiency defined from the previous literature as the intensity of the signal over the incident wave) .…”

Section: Introductionmentioning

confidence: 99%

Total Reflection Metasurface with Pure Modulated Signal

Chen

Hong

2018

Advanced Optical Materials

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fabrication facilities or complicated optical design and its transfer efficiency is still challenging to apply to most metasurfaces. [4,19,20] Dielectric metasurfaces have shown many advantages. However, due to the fabrication technology, many geometrical metasurfaces designed for the multiplexing, [5] hologram, [19] beam shaping, [21] and active emission control [22] are based on the metallic design and transmission mode. These designs are fundamentally limited by the diffraction efficiency of the nanoantennas. (summary of the metasurface efficiency can be found in the Supporting Information). The low transfer efficiency leads to a large drawback of the metasurface design: the zero-order intensity is mixed into the output signal, which is due to the unmodulated light. Optical devices require clean and pure output signals. For this reason, optical filters and other components are required to eliminate the noise in almost every experiment. [2,4,5,16,[19][20][21][22] However, one of the ultimate goals for metasurface is to achieve light modulation with an all-in-one ultrathin device, which can replace the bulky and complicated conventional components. These extra noise-reduction measures sacrifice the unique advantages of metasurfaces, reduce the reliability, and greatly limit its functionality in the region close to the metasurface, which becomes a primary weakness compared to classic optical components. In the pursuit to replace the classic optical components with metasurfaces, it becomes a fundamental challenge that requires a novel solution. It is also a barrier for future applications, such as integrated photonics and super-resolution supercritical lens. [10,[23][24][25] In this work, we present design principles for the first self-filtering metasurface with pure modulated light. Via the unprecedented control of the wavefront, it is possible to modify the internal total reflection as a barrier to block the unmodulated light. Unmodulated light contributes most of the noise. In our scheme, these noises are totally reflected at the interface so only the pure modulated light can transmit and propagate. [26] Thus, it is convenient to denote this functional device as Total Reflection Metasurface (TRM). TRM has many advantages to approach the goal of all-in-one metasurfaces. Such self-filtering functional device is insensitive to light polarization. Normal metasurface system requires the polarizer, metasurface, and optical filter to function. TRM integrates these components into an ultrathin design that can be directly plug-to-use. Without the help of extra components, the quality of the component can exceed its classic optical counterparts. Furthermore, based on the concept of TRM, we design an optical cavity strategy to Metasurface has been proposed as one critical platform for orbital angular momentum (OAM) multiplexing. While metasurfaces have unique advantages to achieve light modulation with an ultrathin 2D layer, the relatively low transfer efficiency is a primary drawback. Such weakness leads to the mixing of...

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Integrated Resonant Unit of Metasurfaces for Broadband Efficiency and Phase Manipulation

Cited by 70 publications

References 43 publications

Imaging based on metalenses

Imaging based on metalenses

Broadband metamaterials and metasurfaces: a review from the perspectives of materials and devices

Total Reflection Metasurface with Pure Modulated Signal

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