Darafsheh A, Astratov VN. Periodically focused modes in chains of dielectric spheres.
APPLIED PHYSICS LETTERS 2012;
100:61123-611234. [PMID:
22396621 PMCID:
PMC3293362 DOI:
10.1063/1.3684246]
[Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2011] [Accepted: 01/24/2012] [Indexed: 05/13/2023]
Abstract
We show that, theoretically, Brewster angle conditions for transverse magnetic polarized rays can be periodically reproduced in chains of spheres with index n = [Formula: see text] 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 μm sapphire spheres with index ∼1.77 in visible.
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