Design of aluminum nitride metalens for broadband ultraviolet incidence routing

Guo, Linhao; Hu, Zhengyan; Wan, Rongqiao; Long, Linyun; Li, Tao; Yan, Jianchang; Lin, Yun; Zhang, Lei; Zhu, Wenhui; Wang, Liancheng

doi:10.1515/nanoph-2018-0151

Cited by 55 publications

(44 citation statements)

References 44 publications

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“…In the end, we compared our results with other references in terms of material platform, bandwidth, incident polarization, and NA; the comparison is shown in Table 1 . We noticed that some of these previous studies are not polarization insensitive [ 33 , 34 ] while others are not broadband [ 29 , 32 ], and compared to these studies the NA of our designed metalens is the highest as well.…”

Section: Design Results and Discussionmentioning

confidence: 71%

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Polarization Insensitive, Broadband, Near Diffraction-Limited Metalens in Ultraviolet Region

Kanwal

Wen

et al. 2020

Nanomaterials

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Metasurfaces in the ultraviolet spectrum have stirred up prevalent research interest due to the increasing demand for ultra-compact and wearable UV optical systems. The limitations of conventional plasmonic metasurfaces operating in transmission mode can be overcome by using a suitable dielectric material. A metalens holds promising wavefront engineering for various applications. Metalenses have developed a breakthrough technology in the advancement of integrated and miniaturized optical devices. However, metalenses utilizing the Pancharatnam–Berry (PB) phase or resonance tuning methodology are restricted to polarization dependence and for various applications, polarization-insensitive metalenses are highly desirable. We propose the design of a high-efficiency dielectric polarization-insensitive UV metalens utilizing cylindrical nanopillars with strong focusing ability, providing full phase delay in a broadband range of Ultraviolet light (270–380 nm). The designed metalens comprises Silicon nitride cylindrical nanopillars with spatially varying radii and offers outstanding polarization-insensitive operation in the broadband UV spectrum. It will significantly promote and boost the integration and miniaturization of the UV photonic devices by overcoming the use of Plasmonics structures that are vulnerable to the absorption and ohmic losses of the metals. The focusing efficiency of the designed metalens is as high as 40%.

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Section: Design Results and Discussionmentioning

confidence: 71%

“…However, due to insufficient phase delay, these lenses defocused at a short UV wavelength range [28][29][30][31][32], and these do not operate in the broadband UV spectrum. Moreover, they do not support the polarization independent operation of the reported metalens [28,33,34].…”

Section: Introductionmentioning

confidence: 70%

Polarization Insensitive, Broadband, Near Diffraction-Limited Metalens in Ultraviolet Region

Kanwal

Wen

et al. 2020

Nanomaterials

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“…As mentioned above, earlier reported work on the metalenses in the UV range is lean and they do not operate in a broadband UV spectrum, and hence are defocused on a small UV range. Moreover, the focusing efficiency and the polarization conversion efficiency of the unit cell is not as high as reported in our work [38,45,46]. Our design of a 2-D, dielectric UV metalens is based on silicon nitride Si 3 N 4 metasurface, exhibiting high efficiency with a full phase delay of 2π for the broadband UV range (250-400 nm) using PB phase.…”

Section: Introductionmentioning

confidence: 68%

“…The bandgap of traditional dielectric materials is narrow, causing high absorption losses in UV. Gallium nitride and titanium oxide have relatively large bandgaps but they are not appropriate to use in the targeted UV spectrum due to their higher absorption losses [46]. Si 3 N 4 has been chosen as the dielectric material for its high refractive index of about 2.3, an ultra-wide bandgap of about 5.1 eV, and its transparency window (k ≈ 0) for the UV spectrum of 250-400 nm [48].…”

Section: Methodsmentioning

confidence: 99%

“…Polarization conversion efficiency can be defined as the fraction of the optical power of the incident circular polarized light which is converted to the optical power of the transmitted inversed circular polarized light [46,51]. By carefully optimizing the unit cell parameters such as height, width, length and period of the nanorod maximum polarization conversion efficiency can be attained.…”

Section: Methodsmentioning

confidence: 99%

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High-Efficiency, Broadband, Near Diffraction-Limited, Dielectric Metalens in Ultraviolet Spectrum

Kanwal

Wen

et al. 2020

Nanomaterials

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Ultraviolet (UV) optical devices have plenteous applications in the fields of nanofabrication, military, medical, sterilization, and others. Traditional optical components utilize gradual phase accumulation phenomena to alter the wave-front of the light, making them bulky, expensive, and inefficient. A dielectric metasurface could provide an auspicious approach to precisely control the amplitude, phase, and polarization of the incident light by abrupt, discrete phase changing with high efficiency due to low absorption losses. Metalenses, being one of the most attainable applications of metasurfaces, can extremely reduce the size and complexity of the optical systems. We present the design of a high-efficiency transmissive UV metalens operating in a broadband range of UV light (250-400 nm) with outstanding focusing characteristics. The polarization conversion efficiency of the nano-rod unit and the focusing efficiency of the metasurface are optimized to be as high as 96% and 77%, respectively. The off-axis focusing characteristics at different incident angles are also investigated. The designed metalens that is composed of silicon nitride nanorods will significantly uphold the advancement of UV photonic devices and can provide opportunities for the miniaturization and integration of the UV nanophotonics and its applications.

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Nanophotonic Color Routing

et al. 2021

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Similarly, refraction can sort out light in space following the Fresnel equation and created the spectrometer hundreds of years ago. [12,35] The interference of light is the main working mechanism of multilayer thin film filters. [36,37] Optical properties of microstructures (e.g., gratings) and device performance are usually sizedependent and thus bulky methods in the case of photovoltaics or display are not applicable for imaging, where the dimensions of the image sensor pixels are orders of magnitude smaller than solar cells and display units as shown in Figure 1b,d. It is not only interesting in science to study the fundamental physics in dispersive light manipulating in a scale down to a micron or sub-micron, but also extremely important to develop advanced spectral routing techniques with high-efficiency utilization of the full spectrum for applications such as high-resolution color imaging, [10,38] hyperspectral imaging, [41][42][43] on-chip spectroscopy, [13,[44][45][46][47][48] multi-channel data storage, [49][50][51] color computer-generated hologram, [52][53][54] light fidelity, [55] etc.Recently, nanophotonic spectral engineering technologies have being received tremendous attention and made significant progress. [13,[56][57][58][59][60][61][62] Plasmonic structures demonstrated a color encoding resolution as high as 100 000 dpi. [59] All dielectric metasurfaces presented structural colors with a gamut area of 181.5% of sRGB. [60] Colloid quantum dots were used to form a filter array for an on-chip spectrometer. [13] Sub-10 nm plasmonic resonance linewidth was demonstrated for optical sensing. [61] Reconfigurable spectral response was demonstrated by a combination of chemical and physical colors. [62] There are a number of published reviews on the topic of structural color techniques, which focus on the spectral filtering scheme. [63][64][65][66][67] The key issue of all these spectral filtering techniques is the same to pick out a certain wavelength band from a broadband light source, where efficiency and crosstalk are the main performance parameters. The color routing efficiency is associated with the brightness. The higher the efficiency, the brighter the image. For example, in the case of imaging and display, it is determined by the ratio of the received optical power in the target wavelength band over the whole incident power. Thus, in the case of a usual Bayer array with blue (R), green (G), blue (B) filters, [68] the maximum efficiency of the R pixel is considered to be only 25% (without consideration of unwanted crosstalk) because the light incident to other three pixels will not contribute to the R pixel. The spectral crosstalk is associated with the color purity. The lower the spectral crosstalk, the higher the Recent advances in low-dimensional materials and nanofabrication technologies have stimulated many breakthroughs in the field of nanophotonics such as metamaterials and plasmonics that provide efficient ways of light manipulation at a subwavelength scale. The representative structure-...

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Design of aluminum nitride metalens for broadband ultraviolet incidence routing

Cited by 55 publications

References 44 publications

Polarization Insensitive, Broadband, Near Diffraction-Limited Metalens in Ultraviolet Region

Polarization Insensitive, Broadband, Near Diffraction-Limited Metalens in Ultraviolet Region

High-Efficiency, Broadband, Near Diffraction-Limited, Dielectric Metalens in Ultraviolet Spectrum

Nanophotonic Color Routing

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