High-Efficiency, Near-Diffraction Limited, Dielectric Metasurface Lenses Based on Crystalline Titanium Dioxide at Visible Wavelengths

Liang, Yuanyuan; Liu, Hongzhan; Wang, Faqiang; Meng, Hongyun; Guo, Jianping; Li, Jinfeng; Wei, Zhongchao

doi:10.3390/nano8050288

Cited by 58 publications

(26 citation statements)

References 26 publications

(36 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Furthermore, to demonstrate the advantage of the hexagonal grid in such a design at the wide angle, we calculated focusing efficiencies at different angles by using different arrangements. The focusing efficiency is the fraction of incident light that passes through the metalens divided by the area of a circular iris on the focal plane with thrice the radius of the a FWHM spot size 34,35 . Table 1 presents the simulation results of different arrangements and a comparison between different arrangements of the focusing efficiencies of the wide-angle metalens at different angles.…”

Section: Discussionmentioning

confidence: 99%

Ultrawide-angle and high-efficiency metalens in hexagonal arrangement

Fan

Lin

2020

Sci Rep

View full text Add to dashboard Cite

Wide-angle optical systems play a vital role in imaging applications and have been researched for many years. In traditional lenses, attaining a wide field of view (FOV) by using a single optical component is difficult because these lenses have crucial aberrations. In this study, we developed a wide-angle metalens with a numerical aperture of 0.25 that provided a diffraction-limited FOV of over 170° for a wavelength of 532 nm without the need for image stitching or multiple lenses. The designed wide-angle metalens is free of aberration and polarization, and its full width of half maximum is close to the diffraction limit at all angles. Moreover, the metalens which is designed through a hexagonal arrangement exhibits higher focusing efficiency at all angles than most-seen square arrangement. The focusing efficiencies are as high as 82% at a normal incident and 45% at an incident of 85°. Compared with traditional optical components, the proposed metalens exhibits higher FOV and provides a more satisfactory image quality because of aberration correction. Because of the advantages of the proposed metalens, which are difficult to achieve for a traditional single lens, it has the potential to be applied in camera systems and virtual and augmented reality.

show abstract

Section: Discussionmentioning

confidence: 99%

Ultrawide-angle and high-efficiency metalens in hexagonal arrangement

Fan

Lin

2020

Sci Rep

View full text Add to dashboard Cite

show abstract

“…colloidal tio 2 nanoparticles. For the TiO 2 nanoparticles (NPs), a water-based colloidal solution (33)(34)(35)(36)(37) wt%; Sigma Aldrich) of a mixture of anatase and rutile TiO 2 NPs was used; the average size is ~ 50 nm, however larger particles, up to 150 nm, could be present (see Fig. S1 in the Supplementary Information).…”

Section: Methodsmentioning

confidence: 99%

“…utilized in solar cell devices such as dye-sensitized solar cells, polymer-inorganic hybrid solar cells, quantum dot-sensitized solar cells, and perovskite solar cells, 13 heterojunction solar cells with electron-selective TiO 2 contact, 18 photo electrochemical water splitting, 19 as part of (graded-index) anti-reflection layer coating(s), [20][21][22][23][24][25][26] quasi-periodic multilayer ARCs, 27 light manipulation metasurfaces, [28][29][30][31][32][33][34][35][36] and for light extraction in light emitting diodes (LEDs) [37][38][39] .…”

mentioning

confidence: 99%

Embossed Mie resonator arrays composed of compacted TiO2 nanoparticles for broadband anti-reflection in solar cells

Visser

Chen

Désières

et al. 2020

Sci Rep

View full text Add to dashboard Cite

Mie resonator arrays formed by embossing titanium dioxide (tio 2) nanoparticles (nps) from solution are investigated as optical coatings for anti-reflection applications. Compacted nanoparticle assemblies offer unique possibilities to tailor the effective refractive index (RI). Here, we demonstrate a simple table-top, low pressure, and low temperature method to fabricate structured optical coatings. TiO 2 nanostructures in the form of nanodisks support Mie resonances in the visible wavelength spectrum and exhibit strong forward scattering into the high index substrates, making them suitable as broadband anti-reflection coatings for solar cells. TiO 2 np-based nanodisk arrays are designed, fabricated, and characterized regarding their anti-reflection properties on Si, GaAs, and InP substrates and solar cells. Detailed finite-difference time-domain simulations are performed to optimize the tio 2 NP-based Mie resonator arrays for the broadband anti-reflection as well as to explain the measured reflectance spectra. The solar-weighted reflectance is used as a figure of merit (FoM). TiO 2 nanodisk arrays on Si show a FoM of ~ 7% in the 400-1,100 nm wavelength spectrum; similar values are obtained for GaAs and InP substrates. TiO 2 nanodisk arrays embossed directly on prefabricated planar single-junction Si, GaAs, and InP solar cells result in an appreciable increase (~ 1.3 times) in the short-circuit current densities. Recently, sub-wavelength dielectric Mie resonator arrays have been reported for applications such as omnidirectional broadband anti-reflection. 1,2 Si nanodisk arrays on Si substrates show low average surface reflectance over the visible-NIR wavelength region. 3 Surface reflection reduction 4-7 plays a major part in increasing the performance of solar cells. For inorganic semiconductor solar cell materials, e.g., Si and III-Vs, due to their high refractive indices (~ 3-4) the reflectance loss (~ 30-40%) is significant. To reduce this, the solar cell surface can either be structured directly or an additional (structured) optical coating can be used. Direct structuring of solar cells can degrade its performance due to process induced defects and surface recombination and invariably requires additional passivation procedures/coatings. Such issues become more significant for thin film solar cells (thickness of ~ 2 µm or less). These limitations may be overcome by depositing a structured optical layer instead. Anti-reflection coatings (ARCs) include commonly used traditional thin-film dielectrics (e.g., silicon dioxide (SiO 2) and silicon nitride (Si x N y)), metal nanoparticles, 8,9 and dielectric nanostructures 3,10,11. While thin film dielectrics are easier to fabricate, multilayers are often required to achieve broadband anti-reflection. Metallic nanoparticles suffer from parasitic absorption in the metal and the resonances are highly sensitive to the RI of the matrix below or around the nanoparticles. 12 High-index dielectric (e.g., Si) Mie resonator arrays placed on Si or substrates with similar refract...

show abstract

“…Metasurfaces have stirred up a spree of research interest in recent years due to their brilliant performance in the field of electromagnetic wave manipulation [1][2][3][4][5][6][7][8][9]. Metasurfaces are based on some well-designed subwavelength scale arrays of resonators to manipulate the amplitude, phase, propagation direction, and polarization of light to nanoscale resolution at an ease [10][11][12][13][14][15][16][17][18][19], making them an appropriate option for miniaturization and integration of photonic systems.…”

Section: Introductionmentioning

confidence: 99%

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

Kanwal

Wen

et al. 2020

Nanomaterials

View full text Add to dashboard Cite

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.

show abstract

High-Efficiency, Near-Diffraction Limited, Dielectric Metasurface Lenses Based on Crystalline Titanium Dioxide at Visible Wavelengths

Cited by 58 publications

References 26 publications

Ultrawide-angle and high-efficiency metalens in hexagonal arrangement

Ultrawide-angle and high-efficiency metalens in hexagonal arrangement

Embossed Mie resonator arrays composed of compacted TiO2 nanoparticles for broadband anti-reflection in solar cells

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

Contact Info

Product

Resources

About