Thermal tunability of photonic bandgaps in photonic crystal fibers selectively filled with nematic liquid crystal

• Autor(a) principal: Franco, Marcos A.R.
• Data de Publicação: 2010
• Outros Autores: Patrício, Paulo S. [UNESP], Pitarello, Tânia R.
• Tipo de documento: Artigo de conferência
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://dx.doi.org/10.1117/12.868246; http://hdl.handle.net/11449/72061
• topic: Fiber optics; Liquid crystal; Microstructured optical fibers; Photonic bandgap; Photonic crystal fibers; Air holes; Band gap effects; Band gaps; Computational program; Hexagonal lattice; High Index materials; High-index; Hybrid photonic crystals; Index material; Low loss; Low-refractive-index materials; Micro-structured optical fibers; Nematic liquids; Optical modes; Optical propagation; Physical effects; Temperature changes; Thermally induced; Thermo-optic coefficients; Thermo-optical; Total internal reflections; Transmission spectrums; Tunabilities; Uniaxial media; Anisotropic media; Crystal whiskers; Energy gap; Fibers; Liquid crystals; Liquids; Metal cladding; Microstructure; Nematic liquid crystals; Optical fibers; Optical waveguides; Photonic bandgap fibers; Refractive index; Spontaneous emission; Photonic crystals

We address the bandgap effect and the thermo-optical response of high-index liquid crystal (LC) infiltrated in photonic crystal fibers (PCF) and in hybrid photonic crystal fibers (HPCF). The PCF and HPCF consist of solid-core microstructured optical fibers with hexagonal lattice of air-holes or holes filled with LC. The HPCF is built from the PCF design by changing its cladding microstructure only in a horizontal central line by including large holes filled with high-index material. The HPCF supports propagating optical modes by two physical effects: the modified total internal reflection (mTIR) and the photonic bandgap (PBG). Nevertheless conventional PCF propagates light by the mTIR effect if holes are filled with low refractive index material or by the bandgap effect if the microstructure of holes is filled with high refractive-index material. The presence of a line of holes with high-index LC determines that low-loss optical propagation only occurs on the bandgap condition. The considered nematic liquid crystal E7 is an anisotropic uniaxial media with large thermo-optic coefficient; consequently temperature changes cause remarkable shifts in the transmission spectrums allowing thermal tunability of the bandgaps. Photonic bandgap guidance and thermally induced changes in the transmission spectrum were numerically investigated by using a computational program based on the beam propagation method. © 2010 SPIE.