Periodically focused modes in chains of dielectric spheres

Arash Darafsheh, Vasily N. Astratov

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56 Scopus citations


We show that, theoretically, Brewster angle conditions for transverse magnetic polarized rays can be periodically reproduced in chains of spheres with index n = √3 giving rise to lossless periodically focused modes with 2D period, where D is the sphere diameter. Using ray tracing for a spherical emitter with the diameter D we show that chains of spheres work as filters of such modes at 1.72 < n < 1.85. This leads to tapering of the focused beams combined with the reduction of their attenuation along the chain. Experimentally, the beam tapering effect was observed in chains of 300 m sapphire spheres with index ∼1.77 in visible.

Original languageEnglish
Article number061123
JournalApplied Physics Letters
Issue number6
StatePublished - Feb 6 2012


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