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Updated: May 24, 2026

Development of Whispering Gallery Mode Polymeric Micro-optical Electric Field Sensors
Published on: January 29, 2013
Periodically focused modes in chains of dielectric spheres
Arash Darafsheh1, Vasily N Astratov
1Department of Physics and Optical Science, Center for Optoelectronics and Optical Communications, University of North Carolina at Charlotte, Charlotte, North Carolina 28223-0001, USA.
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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