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Triple-helical nanowires by tomographic rotatory growth for chiral photonics.

Esposito M, Tasco V, Todisco F, Cuscunà M, Benedetti A, Sanvitto D, Passaseo A - Nat Commun (2015)

Bottom Line: Complex intertwined three dimensional structures such as multiple-helical nanowires could overcome these limitations, allowing the achievement of several chiro-optical effects combining chirality and isotropy.These three dimensional nanostructures show up to 37% of circular dichroism in a broad range (500-1,000 nm), with a high signal-to-noise ratio (up to 24 dB).Optical activity of up to 8° only due to the circular birefringence is also shown, tracing the way towards chiral photonic devices that can be integrated in optical nanocircuits to modulate the visible light polarization.

View Article: PubMed Central - PubMed

Affiliation: National Nanotechnology Laboratory-NNL, CNR-IMIP, VIA Arnesano, 73100 Lecce Italy.

ABSTRACT
Three dimensional helical chiral metamaterials resulted in effective manipulation of circularly polarized light in the visible infrared for advanced nanophotonics. Their potentialities are severely limited by the lack of full rotational symmetry preventing broadband operation, high signal-to-noise ratio and inducing high optical activity sensitivity to structure orientation. Complex intertwined three dimensional structures such as multiple-helical nanowires could overcome these limitations, allowing the achievement of several chiro-optical effects combining chirality and isotropy. Here we report three dimensional triple-helical nanowires, engineered by the innovative tomographic rotatory growth, on the basis of focused ion beam-induced deposition. These three dimensional nanostructures show up to 37% of circular dichroism in a broad range (500-1,000 nm), with a high signal-to-noise ratio (up to 24 dB). Optical activity of up to 8° only due to the circular birefringence is also shown, tracing the way towards chiral photonic devices that can be integrated in optical nanocircuits to modulate the visible light polarization.

No MeSH data available.


Related in: MedlinePlus

Dichroic selectivity of THNsCalculated dependence of THN circular dichroic properties on the two geometrical parameters (ED and VP):(a) bandwidth, (b) extinction ratio. A good combination of high extinction ratio and bandwidth is obtained for low values of VP (around 600 nm) and external diameter around 400 nm.
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Figure 2: Dichroic selectivity of THNsCalculated dependence of THN circular dichroic properties on the two geometrical parameters (ED and VP):(a) bandwidth, (b) extinction ratio. A good combination of high extinction ratio and bandwidth is obtained for low values of VP (around 600 nm) and external diameter around 400 nm.

Mentions: The structure design resulted from Finite Difference Time Domain (FDTD) simulations as a function of the two main geometrical parameters, VP and ED (figure 2), providing the best overlap between high extinction ratio (defined as TL / TR, amplitude contrast of the left circularly polarized (LCP) and right circularly polarized (RCP) transmissions respectively) and broad circular dichroic bandwidth (defined as the wavelength range where the extinction factor values exceeded 1), in the visible spectral range.


Triple-helical nanowires by tomographic rotatory growth for chiral photonics.

Esposito M, Tasco V, Todisco F, Cuscunà M, Benedetti A, Sanvitto D, Passaseo A - Nat Commun (2015)

Dichroic selectivity of THNsCalculated dependence of THN circular dichroic properties on the two geometrical parameters (ED and VP):(a) bandwidth, (b) extinction ratio. A good combination of high extinction ratio and bandwidth is obtained for low values of VP (around 600 nm) and external diameter around 400 nm.
© Copyright Policy - permissions-link
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4374152&req=5

Figure 2: Dichroic selectivity of THNsCalculated dependence of THN circular dichroic properties on the two geometrical parameters (ED and VP):(a) bandwidth, (b) extinction ratio. A good combination of high extinction ratio and bandwidth is obtained for low values of VP (around 600 nm) and external diameter around 400 nm.
Mentions: The structure design resulted from Finite Difference Time Domain (FDTD) simulations as a function of the two main geometrical parameters, VP and ED (figure 2), providing the best overlap between high extinction ratio (defined as TL / TR, amplitude contrast of the left circularly polarized (LCP) and right circularly polarized (RCP) transmissions respectively) and broad circular dichroic bandwidth (defined as the wavelength range where the extinction factor values exceeded 1), in the visible spectral range.

Bottom Line: Complex intertwined three dimensional structures such as multiple-helical nanowires could overcome these limitations, allowing the achievement of several chiro-optical effects combining chirality and isotropy.These three dimensional nanostructures show up to 37% of circular dichroism in a broad range (500-1,000 nm), with a high signal-to-noise ratio (up to 24 dB).Optical activity of up to 8° only due to the circular birefringence is also shown, tracing the way towards chiral photonic devices that can be integrated in optical nanocircuits to modulate the visible light polarization.

View Article: PubMed Central - PubMed

Affiliation: National Nanotechnology Laboratory-NNL, CNR-IMIP, VIA Arnesano, 73100 Lecce Italy.

ABSTRACT
Three dimensional helical chiral metamaterials resulted in effective manipulation of circularly polarized light in the visible infrared for advanced nanophotonics. Their potentialities are severely limited by the lack of full rotational symmetry preventing broadband operation, high signal-to-noise ratio and inducing high optical activity sensitivity to structure orientation. Complex intertwined three dimensional structures such as multiple-helical nanowires could overcome these limitations, allowing the achievement of several chiro-optical effects combining chirality and isotropy. Here we report three dimensional triple-helical nanowires, engineered by the innovative tomographic rotatory growth, on the basis of focused ion beam-induced deposition. These three dimensional nanostructures show up to 37% of circular dichroism in a broad range (500-1,000 nm), with a high signal-to-noise ratio (up to 24 dB). Optical activity of up to 8° only due to the circular birefringence is also shown, tracing the way towards chiral photonic devices that can be integrated in optical nanocircuits to modulate the visible light polarization.

No MeSH data available.


Related in: MedlinePlus