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In this work studies on propagation properties of a microstructured polymer optical fibre infiltrated with a nematic liquid crystal are presented. Specifically, the influence of an infiltration method on the LC molecular alignment inside fibre air-channels and, thus, on light guidance is discussed. Switching between propagation mechanisms, namely the transition from modified total internal reflection (mTIR) to the photonic bandgap effect obtained by varying external temperature is also demonstrated.
Content available remote Tunability of discrete diffraction in photonic liquid crystal fibres
In this paper theoretical and experimental results regarding discrete light propagation in photonic liquid crystal fibres (PLCFs) are presented. Particular interest is focused on tunability of the beam guidance obtained due to the variation in either external temperature or optical power (with assumption of thermal nonlinearity taking place in liquid crystals). Highly tunable (discrete) diffraction and thermal self-(de)focusing are studied and tested in experimental conditions. Specifically, spatial light localization and/or delocalization due to the change in tuning parameters are demonstrated, with possibility of discrete spatial (gap) soliton propagation in particular conditions. Results of numerical simulations (performed for the Gaussian beams of different widths and wavelengths) have been compared to those from experimental tests performed in the PLCFs of interest. Owning to the limit of experimental means, direct qualitative comparison was not quite accessible. Nevertheless, a qualitative agreement between theoretical and experimental data (obtained in analogous conditions) has been achieved, suggesting a compact and widely-accessible platform for the study of tunable linear (and nonlinear) discrete light propagation in two-dimensional systems. Proposed photonic structures are of a great potential for all-optical beam shaping and switching.
Content available remote Dispersion management in soft glass all-solid photonic crystal fibres
The development of all-solid photonic crystal fibres for nonlinear optics is an alternative approach to air-glass solid core photonic crystal fibres. The use of soft glasses ensures a high refractive index contrast (> 0.1) and a high nonlinear coefficient of the fibres. We report on the dispersion management capabilities in all-solid photonic crystal fibres taking into account four thermally matched glasses which can be jointly processed using the stack-and-draw fibre technique. We present structures with over 450 nm broadband flat normal dispersion and ultra-flat near zero anomalous dispersion below 5 ps/nm/km over 300 nm dedicated to supercontinuum generation with 1540 nm laser sources. The development of an all-solid photonic crystal fibre made of F2 and NC21 glasses is presented. The fibre is used to demonstrate supercontinuum generation in the range of 730–870 nm (150 nm) with flatness below 5 dB.
Content available remote Near infrared transmission in dual core lead silicate photonic crystal fibres
Photonic crystal fibres (PCF) can provide the high confinement needed to enable nonlinear optical processes to be studied in silicate fibre over short lengths without the need for large pulse energies. Additionally, the capillary stacking technique for PCF fabrication lends itself to the design of multiple core fibres and this capability has triggered much work into the properties of dual core PCF. In this paper, the effect of the dual core interaction on the nonlinear wavelength conversion is studied using a femtosecond oscillator in the near IR range. Effective supercontinuum generation in the range 1300-1700 nm is achieved in the anomalous dispersion regime.
In this paper, we report on the fabrication of the birefringent photonic crystal fibre with a photonic cladding composed of elliptical holes ordered in a rectangular lattice. Choice of such configuration allows obtaining birefringence in photonic crystal fibres. In this case two-fold rotational symmetry is achieved and the polarized orthogonal modes (HE11x and HE11y) are not degenerated. We discuss the influence of structural parameters including the ellipticity of the air holes and the aspect ratio of the rectangular lattice on the birefringence and on the modal properties of this glass-air microstructural fibre.
W artykule przedstawiono uzyskane włókno dwójłomne o anizotropii optycznej wywołanej eliptycznym kształtem elementów płaszcza fotonicznego i prostokątnym kształtem przekroju. Wyraźnie określona dwuosiowość prowadzi do dużych różnic efektywnych współczynników załamania dla dwóch podstawowych i ortogonalnie spolaryzowanych modów HE11x i HE11y. Dzięki temu mody te nie są zdegenerowane. Zależnie od parametrów strukturalnych włókna możliwe jest uzyskanie znacznych wartości dwójłomności. W artykule przedstawiono zarys technologii wytwarzania szklanych włókien tego typu, przedyskutowano wpływ parametrów strukturalnych na wartość dwójłomności i własności modowe oraz wyniki symulacji i pomiarów dla uzyskanego włókna.
We report about a novel kind of supercontinuum generation in a photonic crystal fibre in which the spectral broadening occurs only on the blue side of the pump wavelength. As a consequence a limit to the extent of the supercontinuum is set and thus a way for tailoring the broadened spectrum according to a peculiar application is provided. We present a theoretical explanation along with experimental data which are supported by the results of a set of numerical simulations.
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