23 May 2007 Tunable one-dimensional photonic crystal slabs
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Proceedings Volume 6593, Photonic Materials, Devices, and Applications II; 659314 (2007); doi: 10.1117/12.721985
Event: Microtechnologies for the New Millennium, 2007, Maspalomas, Gran Canaria, Spain
Abstract
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.
© (2007) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
R. Beccherelli, B. Bellini, D. Zografopoulos, E. Kriezis, "Tunable one-dimensional photonic crystal slabs", Proc. SPIE 6593, Photonic Materials, Devices, and Applications II, 659314 (23 May 2007); doi: 10.1117/12.721985; https://doi.org/10.1117/12.721985
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KEYWORDS
Silicon

Liquid crystals

Refractive index

Cladding

Photonic crystals

Semiconducting wafers

Glasses

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