Programmable Extreme Chirality in the Visible by Helix-Shaped Metamaterial Platform

Esposito, Marco; Tasco, V.; Todisco, Francesco; Cuscunà, Massimo; Benedetti, Alessio; Scuderi, M.; Nicotra, Giuseppe; Passaseo, A.

doi:10.1021/acs.nanolett.6b02583

Cited by 75 publications

(95 citation statements)

References 44 publications

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“…[99] This metallic element shows a resonant chiral behavior, indicating the formation of a lightinteracting plasmonic dipole moment, with the consequent formation of two opposite dichroic bands in the visible. When two or more unit metallic elements are vertically stacked as shown in Figure 11, where the loop number N has been varied from 0.5 to 1.5, thanks to the high level of control enabled by FIBID technique, the two dichroic bandwidths can be increased with respect to the ones of the half-pitch structure (Figure 11a).…”

Section: Optical Activity Of Micro/nanohelices By Focused Ion And/or mentioning

confidence: 99%

“…[99] In such structures, chiral activity results from the combination of high refractive index contrast medium with the 3D nanoscale chiral arrangement of (see section 2.3). As displayed in Figure 16g, where the transmission curves of the dielectric structures are reported, the 3-fold symmetry still holds the bisignated CD spectrum, induced by the material polarizability, and leaves unaffected the bandwidth, with trend similar to single helix structures in the same material, because of the missing dipole-dipole plasmon interaction, as detailed in ref.…”

Section: Multiple Helix Nanowire (Mhn) Designsmentioning

confidence: 99%

“…As displayed in Figure 16g, where the transmission curves of the dielectric structures are reported, the 3-fold symmetry still holds the bisignated CD spectrum, induced by the material polarizability, and leaves unaffected the bandwidth, with trend similar to single helix structures in the same material, because of the missing dipole-dipole plasmon interaction, as detailed in ref. [99]. Circular birefringence has been also analyzed by optical rotatory dispersion (ORD) on the THN Pt array.…”

Section: Multiple Helix Nanowire (Mhn) Designsmentioning

confidence: 99%

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Materials and 3D Designs of Helix Nanostructures for Chirality at Optical Frequencies

Passaseo

Esposito

Cuscunà

et al. 2017

Advanced Optical Materials

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The capability to fully control the chiro‐optical properties of metamaterials has drawn considerable attention due to developments in metamaterial fabrication techniques and a deeper understanding of the light–matter interaction, enabling a number of applications from integrated photonics to life sciences. From simple geometrical studies on single helix shaped metamaterials, both the design complexity and nanofabrication capability are steadily increasing allowing to extend their properties to the visible regime and beyond. In this work, helix‐shaped micro‐ and nanostructures are reviewed, which have the possibility to modulate their optical response in the linear regime at optical frequencies by spatial arrangement or by constitutive material. An overview of different theories describing the general optical operation of chiral media and a discussion on experimental results obtained by the state‐of‐the‐art helix structures realized by different fabrication techniques is provided. Finally, advanced designs for improved functionality envisaged to match practical applications or to enable new optical multifunctionalities are compared. Even if many applications have been envisaged only theoretically, the continuous effort and progress shown by the research community engaged in this field suggests that helical chiral metamaterials could represent a disruptive breakthrough for advanced optical devices.

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Section: Optical Activity Of Micro/nanohelices By Focused Ion And/or mentioning

confidence: 99%

Section: Multiple Helix Nanowire (Mhn) Designsmentioning

confidence: 99%

Section: Multiple Helix Nanowire (Mhn) Designsmentioning

confidence: 99%

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Materials and 3D Designs of Helix Nanostructures for Chirality at Optical Frequencies

Passaseo

Esposito

Cuscunà

et al. 2017

Advanced Optical Materials

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“…( b ) Schematic view of the substrate laying beneath the helices layer. It consists of a GaN/AlGaN heterostructure where a two dimensional electron gas allows for charge effect management during the helices growth by FIBID 10, 24 . All the heterostructure is epitaxially grown on a thick (380 micron) Al2O3 substrate.…”

Section: Sample Description and Experimental Measurementsmentioning

confidence: 99%

Precise detection of circular dichroism in a cluster of nano-helices by photoacoustic measurements

Benedetti

Alam

Esposito

et al. 2017

Sci Rep

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Compact samples of nano-helices built by means of a focused ion beam technology with large bandwidth and high dichroism for circular polarization are promising for the construction of built-in-chip sensors, where the ideal transducer must be sufficiently confined without compromising its filtering ability. Direct all-optical measurements revealed the sample's dichroic character with insufficient details because of scattering and diffraction interference. On the other hand, photoacoustic measurements resulted to be a possible alternative investigation, since they directly deal with absorbed power and allow to get clear evidences of the differential selection for the two opposite polarization states. Multilevel numerical simulations confirmed the experimental results, proving once again the reliability of photoacoustic technique and the versatility of this class of dichroic artificial materials.In the last years, the ultimate nanofabrication frontier represented by 3D nanostructures is generating promising and versatile novel nano-photonics devices. In particular, 3D nanostructures with broken symmetry enable exciting complex interactions with chiral light, generating the typical forms of the optical activity, such as the optical rotation (OR), i.e., the polarization plane rotation of the incident light, and the circular dichroism (CD) 1, 2 , i.e., the different absorption levels for left and right circularly polarized (CP) waves 3 . Among the possible 3D chiral geometries, the helix architecture represents, because of its intrinsic chirality, an effective choice to manifest detectable chiral effects [4][5][6][7][8] . However, the engineering of the chiro-optical properties, such as the frequency as well as the absorbed and scattered portions of left-and right-handed circularly polarized light, requires the full control on the geometrical and spatial parameters and on material composition of the 3D nanostructures. Hence, great efforts have been made to develop flexible nanofabrication techniques for the realization of helical based structures with nanometer accuracy 9 . Recently, focused ion and electron beam induced deposition (FIBID/FEBID) have demonstrated the effective capability to tailor helical nanostructures as a function of application-driven chiro-optical properties 10-14 , leading to the nanometer scale controlled fabrication of helix-shaped metal and dielectric nanostructures, organized in dense and ordered arrays of few micron area. Moreover, the FIBID/FEBID approach is particularly suitable for the building and the spatial localization of compact nano-devices as parts of embedded systems, such as built-in-chip sensors and integrated optoelectronic filters, where it is of key importance the integration of nanostructured materials onto small areas.When dealing with 3D nanostructured samples with limited patterned area, commonly used all optical (AO) measurements, though requiring low power levels of inspecting light, are heavily altered by the electromagnetic (e.m.) field escaping from the un-patterned...

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“…[22][23][24][25][26][27][28][29] This surge is partly fueled by the overall inefficiency of current techniques in separation of racemic mixtures of chiral biomolecules. [30,31] These remarkable works further motivated the development of the sorting of chiral objects using a chiral light. It should be noted that a programmable chirooptical response in the visible range has been experimentally demonstrated using helix-shaped metamaterial.…”

Section: Introductionmentioning

confidence: 99%

Switching of Giant Lateral Force on Sub‐10 nm Particle Using Phase‐Change Nanoantenna

Cao

Bao

Mao

2018

Advcd Theory and Sims

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We numerically show that a giant lateral optical force (LOF) acting on sub-10 nm non-chiral particles can be obtained using a dipole-quadrupole (DQ) Fano resonance (FR). This DQ-FR is excited by an asymmetric plasmonic bowtie nanoantenna array (BNA), which is based on a Au/Ge 2 Sb 2 Te 5 /Au trilayer. The LOF behaves in a direction in which the incident light has neither a spin-orbit coupling nor any wave propagation. Analytical theory reveals that the LOF originates from the "hotspot" established by the DQ-FR in the asymmetric BNA. The direction of DQ-FR induced LOF is reversibly switched with the phase transition of Ge 2 Sb 2 Te 5 , which in turn pushes the achiral nanoparticle sideways in the opposite direction. A photo thermal model is used to study the temporal variation of the temperature of the Ge 2 Sb 2 Te 5 film to show the potential for transiting the Ge 2 Sb 2 Te 5 phase. Particularly, the design of hybrid nanostructure integrating a ground metal mirror can excite a strong magnetic resonance, which enhances the DQ-FR induced LOF and reduces the Brownian motion effect on the nanoparticles. Hence, our scheme leads to a rapid and stable transportation of nanoparticles with radii as small as 10 nm.

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Programmable Extreme Chirality in the Visible by Helix-Shaped Metamaterial Platform

Cited by 75 publications

References 44 publications

Materials and 3D Designs of Helix Nanostructures for Chirality at Optical Frequencies

Materials and 3D Designs of Helix Nanostructures for Chirality at Optical Frequencies

Precise detection of circular dichroism in a cluster of nano-helices by photoacoustic measurements

Switching of Giant Lateral Force on Sub‐10 nm Particle Using Phase‐Change Nanoantenna

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