Optical fiber sensors as the primary element in the protection of critical infrastructure especially in optoelectronic transmission lines

The security systems of the wide area objects are dominated by fiber optic sensors, used primarily to perimeter protection as well as to the protection of vast objects such as pipelines. Critical infrastructure objects are not only industrial facilities but also the transmission lines. Authors present the sensor systems compared to sensors for extensive object security currently available on the market. The designed systems, such as double interferometer system as well as more and more popular QKD systems are sensors with distributed sensing field. These systems, described by authors in many publications, are excellent solutions for the protection of wide area infrastructural objects. Presented fiber sensors, besides sabotage detection also offer the possibility of locating the disturbance along many kilometers of the zone. The solution presented in this paper was designed to adapt well known solutions to the physical protection of the transmission line without interfering with the transmitted data. According to the knowledge of potential threats of fiber optic telecommunications, the authors present methods of protecting fiber optics telecommunication cable, and present their own solutions and describe their application possibilities

3D printed diffractive terahertz lenses

[EN] A 3D printer was used to realize custom-made diffractive THz lenses. After testing several materials, phase binary lenses with periodic and aperiodic radial profiles were designed and constructed in polyamide material to work at 0.625 THz. The nonconventional focusing properties of such lenses were assessed by computing and measuring their axial point spread function (PSF). Our results demonstrate that inexpensive 3D printed THz diffractive lenses can be reliably used in focusing and imaging THz systems. Diffractive THz lenses with unprecedented features, such as extended depth of focus or bifocalization, have been demonstrated.Ministerio de Economia y Competitividad (MINECO) (FIS2011-23175); Generalitat Valenciana (PROMETEOII/2014/072); National Center for Research and Development in Poland (LIDER/020/319/L-5/13/NCBR/2014).Furlan, WD.; Ferrando Martín, V.; Monsoriu Serra, JA.; Zagrajek, P.; Czerwinska, E.; Szustakowski, M. (2016). 3D printed diffractive terahertz lenses. Optics Letters. 41(8):1748-1751. https://doi.org/10.1364/OL.41.001748S1748175141

Terahertz and Raman spectra of non-centrosymmetrical organic molecular crystals

The terahertz waves have been applied to the spectroscopy of molecular crystals. The group based on hybrid organic–inorganic crystals like triglycine zinc chloride, triglycine sulphate, triglycine selenate, diglycine hydrobromide, diglycine hydrochloride, diglycine lithium nitrate, glycine lithium nitrate has been considered. The dispersion relation phonon–polariton have been shown between 10 cm1 and 80 cm1 for diglycine lithium nitrate, triglycine zinc chloride, and diglycine hydrobromide