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Nematicons and their electro-optic control: light localization and signal readdressing via reorientation in liquid crystals.

Piccardi A, Alberucci A, Assanto G - Int J Mol Sci (2013)

Bottom Line: Liquid crystals in the nematic phase exhibit substantial reorientation when the molecules are driven by electric fields of any frequencies.Nematicons can guide other light signals and interact with inhomogeneities and other beams.Moreover, they can be effectively deviated by using the electro-optic response of the medium, leading to several strategies for voltage-controlled reconfiguration of light-induced guided-wave circuits and signal readdressing.

View Article: PubMed Central - PubMed

Affiliation: Nonlinear Optics and OptoElectronics Lab (NooEL), University of Rome "Roma Tre", Via della Vasca Navale 84, Rome 00146, Italy. assanto@uniroma3.it.

ABSTRACT
Liquid crystals in the nematic phase exhibit substantial reorientation when the molecules are driven by electric fields of any frequencies. Exploiting such a response at optical frequencies, self-focusing supports transverse localization of light and the propagation of self-confined beams and waveguides, namely "nematicons". Nematicons can guide other light signals and interact with inhomogeneities and other beams. Moreover, they can be effectively deviated by using the electro-optic response of the medium, leading to several strategies for voltage-controlled reconfiguration of light-induced guided-wave circuits and signal readdressing. Hereby, we outline the main features of nematicons and review the outstanding progress achieved in the last twelve years on beam self-trapping and electro-optic readdressing.

Show MeSH
Beam propagation in three (undoped) NLC mixtures. As birefringence goes up, walk-off increases, whereas self-confinement is appreciable at lower powers. The rightmost graphs plot linear (dashed line) and nonlinear (solid line, corresponding to the highest excitation) output beam profiles across y.
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f4-ijms-14-19932: Beam propagation in three (undoped) NLC mixtures. As birefringence goes up, walk-off increases, whereas self-confinement is appreciable at lower powers. The rightmost graphs plot linear (dashed line) and nonlinear (solid line, corresponding to the highest excitation) output beam profiles across y.

Mentions: Experimental observations with various NLC mixtures, carried out to underline the role of material parameters, confirmed the theoretical predictions: Figure 4 shows the images acquired from three identical samples filled with distinct NLC, namely 1550, E7 and 1791A [26]. At λ = 1064 nm, they exhibit Δn = n// −n⊥ = 0.05, 0.2 and 0.4, respectively, all with n⊥ ≈ 1.5; consistently, the corresponding measured walk-off angles were δ = 2.5º, 6.5º and 12º, respectively. The input powers required for self-trapping were P = 45, 2 and 0.8 mW, respectively, i.e., the larger n2 is, the lower the excitation needed for nematicon formation.


Nematicons and their electro-optic control: light localization and signal readdressing via reorientation in liquid crystals.

Piccardi A, Alberucci A, Assanto G - Int J Mol Sci (2013)

Beam propagation in three (undoped) NLC mixtures. As birefringence goes up, walk-off increases, whereas self-confinement is appreciable at lower powers. The rightmost graphs plot linear (dashed line) and nonlinear (solid line, corresponding to the highest excitation) output beam profiles across y.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3821595&req=5

f4-ijms-14-19932: Beam propagation in three (undoped) NLC mixtures. As birefringence goes up, walk-off increases, whereas self-confinement is appreciable at lower powers. The rightmost graphs plot linear (dashed line) and nonlinear (solid line, corresponding to the highest excitation) output beam profiles across y.
Mentions: Experimental observations with various NLC mixtures, carried out to underline the role of material parameters, confirmed the theoretical predictions: Figure 4 shows the images acquired from three identical samples filled with distinct NLC, namely 1550, E7 and 1791A [26]. At λ = 1064 nm, they exhibit Δn = n// −n⊥ = 0.05, 0.2 and 0.4, respectively, all with n⊥ ≈ 1.5; consistently, the corresponding measured walk-off angles were δ = 2.5º, 6.5º and 12º, respectively. The input powers required for self-trapping were P = 45, 2 and 0.8 mW, respectively, i.e., the larger n2 is, the lower the excitation needed for nematicon formation.

Bottom Line: Liquid crystals in the nematic phase exhibit substantial reorientation when the molecules are driven by electric fields of any frequencies.Nematicons can guide other light signals and interact with inhomogeneities and other beams.Moreover, they can be effectively deviated by using the electro-optic response of the medium, leading to several strategies for voltage-controlled reconfiguration of light-induced guided-wave circuits and signal readdressing.

View Article: PubMed Central - PubMed

Affiliation: Nonlinear Optics and OptoElectronics Lab (NooEL), University of Rome "Roma Tre", Via della Vasca Navale 84, Rome 00146, Italy. assanto@uniroma3.it.

ABSTRACT
Liquid crystals in the nematic phase exhibit substantial reorientation when the molecules are driven by electric fields of any frequencies. Exploiting such a response at optical frequencies, self-focusing supports transverse localization of light and the propagation of self-confined beams and waveguides, namely "nematicons". Nematicons can guide other light signals and interact with inhomogeneities and other beams. Moreover, they can be effectively deviated by using the electro-optic response of the medium, leading to several strategies for voltage-controlled reconfiguration of light-induced guided-wave circuits and signal readdressing. Hereby, we outline the main features of nematicons and review the outstanding progress achieved in the last twelve years on beam self-trapping and electro-optic readdressing.

Show MeSH