Tunable one-dimensional photonic crystal slabs

Beccherelli, Romeo and Bellini , Bob and Zografopoulos, Dimitrios C. and Kriezis, Emmanouil E. (2007) Tunable one-dimensional photonic crystal slabs. In: Photonic Materials, Devices, and Applications II. Proceedings of the society of photo-optical instrumention engineers (SPIE), 6593 . Spie-Int Soc Optical Engineering, Bellingham, WA 98227-0010 USA , pp. 1-13. ISBN 978-0-8194-6721-8

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A 1D photonic crystal slab based on preferential etching of commercially available silicon-on-insulator wafers is presented. Compared to dry etching, anisotropic wet etching is more tolerant to errors as it is self-stopping on crystallographic {111} planes and it produces a more precise geometry with symmetries and homothetic properties, with surface roughness close to 1 nm. The resulting grooves are infiltrated by low viscosity liquid crystal having large positive optical anisotropy. The use of slanted grooves provides advantages: first of all the complete filling of slanted grooves is simplified when compared to vertical walls structures. Furthermore alignment is significantly facilitated. Indeed the liquid crystal molecules tend to align with their long axis along the submicron grooves. Therefore by forcing reorientation out of a rest position, the liquid crystal presents a choice of refractive indices to the propagating optical field. The liquid crystal behavior is simulated by a finite element method, and coupled to a finite difference time domain method. We investigate different photonic crystal configurations. Large tunability of bandgap edge for TE polarization is demonstrated when switching the liquid crystal with an applied voltage. We have also studied the use of the same device geometry as a very compact microfluidic refractometric sensor.

Item Type: Book Section
Subjects: 600 Tecnologia - Scienze applicate > 620 Ingegneria e attivita' affini
Depositing User: Danilo Dezzi
Date Deposited: 21 Dec 2012 12:59
Last Modified: 12 Mar 2013 14:43
URI: http://eprints.bice.rm.cnr.it/id/eprint/4438

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