Hybrid guided space-time optical modes in unpatterned films

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Publicado en:Nature Communications vol. 11, no. 1 (2020)
Autor principal: Abbas, Shiri
Otros Autores: Yessenov Murat, Webster, Scott, Schepler, Kenneth L, Abouraddy, Ayman F
Publicado:
Nature Publishing Group
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Acceso en línea:Citation/Abstract
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Resumen:Light is confined transversely and delivered axially in a waveguide. However, waveguides are lossy static structures whose modal characteristics are fundamentally determined by their boundary conditions. Here we show that unpatterned planar waveguides can provide low-loss two-dimensional waveguiding by using space-time wave packets, which are unique one-dimensional propagation-invariant pulsed optical beams. We observe hybrid guided space-time modes that are index-guided in one transverse dimension and localized along the unbounded dimension. We confirm that these fields enable overriding the boundary conditions by varying post-fabrication the group index of the fundamental mode in a 2-μm-thick, 25-mm-long silica film, achieved by modifying the field’s spatio-temporal structure. Tunability of the group index over an unprecedented range from 1.26 to 1.77 is verified while maintaining a spectrally flat zero-dispersion profile. Our work paves the way to utilizing space-time wave packets in on-chip platforms, and enable phase-matching strategies that circumvent restrictions due to intrinsic material properties.Waveguides typically function by using boundary conditions to contain light. Here, the authors show that by using space-time wavepackets, light can be guided in an unpatterned planar waveguide as the field remains localized along the unbounded dimension.
ISSN:2041-1723
DOI:10.1038/s41467-020-20009-2
Fuente:Health & Medical Collection