The paper gives a short description of light guidance mechanisms of index-guided photonic-crystal fibres. The results of numerical analyses of photonic-crystal fibres with a suspended core are presented. Such fibres are planned to be applied for investigation of magneto-optic effects in gaseous media.
The photonic-crystal fibre with a suspended core was analyzed in order to explain possibilities of its using in investigation of electrooptic and magnetooptic effects occurring in the molecules of gas passed into air holes in the fibre. As results from numerical analysis, even 20% of electromagnetic optical energy can be propagating in the area of the air holes. The obtained results indicate the possibility of scanning the electrooptic and magnetooptic effects in photonic-crystal fibres with a suspended core in the case of considerable diminishing of the core (even below 1 µm) or in the case of light applying with its larger wavelengths.
We analyze coupling and propagation of light through a suspended-core microstructured optical fiber. It is experimentally demonstrated that light-coupling efficiency and mode distribution strongly depend on relative position of the fiber's core and a light beam and light polarization. The experimental results are supported with numerical simulations. The developed numerical model confirmed all the observed dependences.
On-site detection and initial identification of chemical warfare agents (CWAs) remain difficult despite the many available devices designed for this type of analysis. Devices using well-established analytical techniques such as ion mobility spectrometry, gas chromatography coupled with mass spectrometry, or flame photometry, in addition to unquestionable advantages, also have some limitations (complexity, high unit cost, lack of selectivity). One of the emerging techniques of CWA detection is based on acoustic wave sensors, among which surface acoustic wave (SAW) devices and quartz crystal microbalances (QCM) are of particular importance. These devices allow for the construction of undemanding and affordable gas sensors whose selectivity, sensitivity, and other metrological parameters can be tailored by application of particular coating material. This review article presents the current state of knowledge and achievements in the field of SAW and QCM-based gas sensors used for the detection of blister agents as well as simulants of these substances. The scope of the review covers the detection of blister agents and their simulants only, as in the available literature no similar paper was found, in contrast to the detection of nerve agents. The article includes description of the principles of operation of acoustic wave sensors, a critical review of individual studies and solutions, and discusses development prospects of this analytical technique in the field of blister agent detection.
One of the most important problems with regard to the Surface Acoustic Wave (SAW) gas sensors technology is the deposition of chemosensitive films exhibiting desirable chemical and physical properties. The electrospraying technology seems to be a very promising method of the film deposition in this case. It allows the chemosensitive layers to be obtained out of almost any chemicals and their mixtures in a controllable way. The process gives the possibility to generate specific films with properties unattainable if other methods were to be applied. For example, it allows to deposit solutions of polymers and suspensions of solids in polymer solutions which can degrade in the process of thermal evaporation deposition.The paper describes the results of experiments with electrospraying technique in order to obtain Nafion films. The influence of the process parameters on film sensitivity has been studied.
On-site detection of chemical warfare agents (CWAs) can be performed by various analytical techniques. Devices using well-established techniques such as ion mobility spectrometry, flame photometry, infrared and Raman spectroscopy or mass spectrometry (usually combined with gas chromatography) are quite complex and expensive to purchase and operate. For this reason, other solutions based on analytical techniques well suited to portable devices are still being sought. Analyzers based on simple semiconductor sensors may be a potential alternative to the currently used CWA field detectors. In sensors of this type, the conductivity of the semiconductor layer changes upon interaction with the analyte. Metal oxides (both in the form of polycrystalline powders and various nanostructures), organic semiconductors, carbon nanostructures, silicon and various composites that are a combination of these materials are used as a semiconductor material. The selectivity of a single oxide sensor can be adjusted to specific analytes within certain limits by using the appropriate semiconductor material and sensitizers. This review presents the current state of knowledge and achievements in the field of semiconductor sensors for CWA detection. The article describes the principles of operation of semiconductor sensors, discusses individual solutions used for CWA detection present in the scientific literature and makes a critical comparison of them. The prospects for the development and practical application of this analytical technique in CWA field analysis are also discussed.
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