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Abstract: Four types of photonic crystal fibres (PCFs) with different structures and values of birefringence have been evaluated and cross-compared in terms of their corresponding characteristics and sensitivities to lateral force (or pressure), considering this as a function of fibre orientation and the magnitude of the applied external force, as the basis of an all-fibre sensor system. In addition, the force/pressure sensitivities of different pairs of these PCFs when they were fusion-spliced together were evaluated and cross-compared. To obtain an optimum output from these systems, a polarization controller is used in a fibre loop mirror configuration to ensure that a fusion-spliced pair of PCFs is created having the same birefringence angle. The results obtained show that PCFs of low birefringence (Low-Bi) are more sensitive than those of high birefringence (Hi-Bi), although the former require a greater length to achieve a similar effect due to the birefringence. Compared to conventional, non-PCF Hi-Bi fibres (e.g. Panda and Bow-Tie fibres), PCFs demonstrate a much lower temperature sensitivity, allowing them to be well suited to measuring force, pressure and mass in real time (when the temperature is varying) by using a fibre loop mirror (FLM) configuration. In addition, the results obtained show that the sensitivity of the fusion-spliced fibre pairs is lower than that of a single PCF with low and medium birefringence, but more sensitive than that of a single PCF with high birefringence. [Copyright &y& Elsevier]

• In this work, we study a ferroelectric liquid crystal (FLC) cell as a phase-only modulator. The novelty of the approach is the use of a FLC cell with a large switching rotation angle close to 90° instead of the typical value used in display applications, which is less than 45 ∘. • We show that when the LC layer is a half-wave retarder, this device provides a binary π phase modulation for any input state of polarization and with maximum light conversion efficiency, thus being useful even for unpolarized light. This situation is not possible with the common nematic LC modulators or with standard FLC modulators of smaller rotation angles. • The main physico-chemical properties of the liquid crystalline mixture used to fabricate the FLC modulator are studied. In addition, we perform a reverse engineering procedure aimed at verifying the modulator's physical parameters and the binary π -phase modulation. In this work a ferroelectric liquid crystal (FLC) modulator with a non-standard large switching rotation angle, close to 90 ∘ , is fabricated and characterized. The modulator acts as a switchable wave-plate with an in-plane rotation of the principal axis under the action of a bipolar voltage. In the ideal situation of half-wave retardance, the device is shown to behave as a binary π phase modulator independently of the input state of polarization. We provide physico-chemical properties of the liquid crystalline mixture used to fabricate the FLC modulator with such large switching angle. The characterization method of the device optical properties is presented, which allows the localization of the two LC stable states, the unambiguous determination of the rotation angle, and the evaluation of the spectral retardance function. We demonstrate the polarization-independent π phase shift using an adapted Young's type interferometer for real-time measurements, where we further analyze the operational frequency limits of the device. This FLC operational mode can be exploited to produce binary-phase polarization-independent diffractive optical elements. [ABSTRACT FROM AUTHOR]

In searching for new functional self-assembling materials a multicomponent ferroelectric liquid crystalline mixtures with features appropriate for utilization in photonic and electro-optic devices have been designed. Designed mixtures are composed of bicyclic pyrimidine achiral compounds and chiral dopants with an oligophenyl rigid core and two homochiral terminal chains. Basic mesomorphic, electro-optical and structural properties have been carefully studied and discussed. For several mixtures stable enantiotropic ferroelectric phase with very good alignment and desired functional features in surface stabilized geometry have been found. Based on these properties and computational as well as conformational analysis of chiral dopants, the structure-property relations have been established and analysed. Unlabelled Image • Mixtures of olighophenyl chiral dopants and achiral mixture have been designed. • The structure–property correlations for designed mixtures have been established. • Desired tilt angle, low viscosity and spontaneous polarization are observed. • Good electro-optical performance of SSFLC structure are achieved. • The designed mixtures can be used for functional optoelectronic and photonic devices. [ABSTRACT FROM AUTHOR]

Polymeric materials are widely used because of their variety and modification ability. Multifunctional acrylates deserve special attention due to their feasibility of photopolymer development. We reported a new class of polymers produced by photopolymerization using VIS and UV radiation. Monomer mixtures consist of monomers, photo-initiators and co-initiators for VIS or monomers and photo-initiators for UV photopolymerization. One selected monomer was used in each mixture i.e. DTMPTA—trimethylolpropane tetraacrylate, TMPTA—trimethylolpropane triacrylate or TCDMA—tricyclodecanedimethanol diacrylate. Silicone oil terminated by hydroxyl groups—(OH–TSO) was used as the adjuvant sorption material. To characterise the physicochemical properties of obtained materials, instrumental analysis methods were applied. By using chromatographic analysis, it was shown experimentally that the new photopolymer materials have a high sorptive capacity and increased sorption selectivity towards selected organosulfur and organophosphorus compounds. This could result in the use of these new materials as sorption fibers used during solid-phase microextraction (SPME). Image 1 • Multifunctional acrylic monomers were used to produce new sorption materials. • Photopolymerization with light of different wavelengths was used. • Two different light sources were used during the polymerization. • Polymers have great sorption properties in relation to selected CWAs simulants. • These developed photopolymers could be used as SPME fiber coatings. [ABSTRACT FROM AUTHOR]