In certain materials, the spontaneous spreading of a laser beam ( owing to diffraction) can be compensated for by the interplay of optical intensity and material nonlinearity. The resulting nondiffracting beams are called 'spatial solitons' (refs 1 - 3), and they have been observed in various bulk media(4-6). In nematic liquid crystals(7-9), solitons can be produced at milliwatt power levels(10-12) and have been investigated for both practical applications(13) and as a means of exploring fundamental aspects of light interactions with soft matter(14,15). Spatial solitons effectively operate as waveguides, and so can be considered as a means of channelling optical information along the self-sustaining filament. But actual steering of these solitons within the medium has proved more problematic, being limited to tilts of just a fraction of a degree(16-20). Here we report the results of an experimental and theoretical investigation of voltage-controlled 'walk-off' and steering of self-localized light in nematic liquid crystals. We find not only that the propagation direction of individual spatial solitons can be tuned by several degrees, but also that an array of direction-tunable solitons can be generated by modulation instability(21-25). Such control capabilities might find application in reconfigurable optical interconnects, optical tweezers and optical surgical techniques.
M., P., C., C., Assanto, G., A., D.L., C., U. (2004). Routing of Highly Anisotropic Spatial Solitons and Modulational Instability in liquid crystals. NATURE, 432(7018), 733-737 [10.1038/nature03101].
Routing of Highly Anisotropic Spatial Solitons and Modulational Instability in liquid crystals
ASSANTO, GAETANO;
2004-01-01
Abstract
In certain materials, the spontaneous spreading of a laser beam ( owing to diffraction) can be compensated for by the interplay of optical intensity and material nonlinearity. The resulting nondiffracting beams are called 'spatial solitons' (refs 1 - 3), and they have been observed in various bulk media(4-6). In nematic liquid crystals(7-9), solitons can be produced at milliwatt power levels(10-12) and have been investigated for both practical applications(13) and as a means of exploring fundamental aspects of light interactions with soft matter(14,15). Spatial solitons effectively operate as waveguides, and so can be considered as a means of channelling optical information along the self-sustaining filament. But actual steering of these solitons within the medium has proved more problematic, being limited to tilts of just a fraction of a degree(16-20). Here we report the results of an experimental and theoretical investigation of voltage-controlled 'walk-off' and steering of self-localized light in nematic liquid crystals. We find not only that the propagation direction of individual spatial solitons can be tuned by several degrees, but also that an array of direction-tunable solitons can be generated by modulation instability(21-25). Such control capabilities might find application in reconfigurable optical interconnects, optical tweezers and optical surgical techniques.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
