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Organisationseinheit der BAM
- 8 Zerstörungsfreie Prüfung (21)
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- 3 Gefahrgutumschließungen; Energiespeicher (5)
- 3.2 Gefahrguttanks und Unfallmechanik (5)
- 8.1 Sensorik, mess- und prüftechnische Verfahren (5)
- 9 Komponentensicherheit (5)
- 9.6 Additive Fertigung metallischer Komponenten (5)
Eingeladener Vortrag
- nein (13)
Solution doping of commercial polymethyl methacrylate (PMMA) polymer optical fibers (POFs) is presented as a novel approach for preparation of custom cladding-doped POFs (CD-POFs). The presented method is based on a solution-mediated diffusion of dopant molecules into the fiber cladding upon soaking of POFs in a methanol-dopant solution. The method was tested on three different commercial POFs using Rhodamine B as a fluorescent dopant. The dynamics of the diffusion process was studied in order to optimize the doping procedure in terms of selection of the most suitable POF, doping time and conditions. Using the optimized procedure, longer segment of fluorescent CD-POF was prepared and its performance was characterized. Fiber’s potential for sensing and illumination applications was demonstrated and discussed. The proposed method represents a simple and cheap way for fabrication of custom, short to medium length CD-POFs with various dopants.
Solution doping of off-the-shelf plastic optical fibers (POFs) represents rather simple and cheap way for preparing custom cladding-doped POFs (CD-POFs) with short to medium lengths. CD-POFs are especially attractive for environmental sensing applications, but might be of interest for illumination task as well. In this work, the proposed doping technique is tested with three different commercial low-cost polymethyl methacrylate (PMMA) POFs; Eska CK-40 and Eska GK-40 from Mitsubishi Rayon and Raytela PGU-FB1000 from Toray. The aim of the work is to aid the selection of the most suitable fiber yielding highest optical quality of prepared CD-POFs. Firstly, the optimal doping times are determined for the individual fiber types using short fiber samples. Secondly, longer 10 m CD-POFs are prepared from all tested fibersusing the optimized doping procedure. Finally, attenuation of pristine POFs and prepared CD-POFs is measured using optical time domain reflectometry in order to characterize the impacts of the doping on fiber optical properties. In addition, the importance of post-doping drying procedure for CD-POF optical performance is investigated as well. The results suggest that, although doping of all tested fibers is generally feasible, Eska CK-40 is the most suitable candidate with regard to the Doping efficiency and fiber post-doping performance.
Gamma radiation induced effects in perfluorinated polymer optical fibers for sensing applications
(2015)
Radiation induced attenuation in perfluorinated polymer optical fiber was investigated as a potential mean for online. in situ gamma radiation monitoring. Spectral dependence of radiation induced attenuation was measured in the visible and near infrared range. Attenuation spectrum exhibits sharp increase both towards the ultraviolet and infrared side of the spectrum with 3 distinct peaks around 1400 nm. The fiber sensitivity to gamma radiation was further evaluated at two commonly used IR wavelengths (1310nm and l550nm} by pre- and post-irradiation optical time-domain reflectometry measurements. The examined fiber is sensitive up to lOO kGy of total absorbed dose with only minor saturation towards the large dose values. The influence of gamma radiation on the fiber mechanical properties was studied as well. Up to the maximal dose of 100 kGy, no significant deterioration of fiber strength and elasticity was observed.
Nonlinear propagation of ultrafast near infrared pulses in anomalous dispersion region of dual-core photonic crystal fiber was studied. Polarization tunable soliton-based nonlinear switching at multiple non-excitation wavelengths was demonstrated experimentally for fiber excitation by 100 fs pulses at 1650 nm. The highest-contrast switching was obtained with the fiber length of just 14 mm, which is significantly shorter compared to the conventional non-solitonic in-fiber switching based on nonlinear optical loop mirror. Advanced numerical simulations show good agreement with the experimental results, suggesting that the underlying dual-core soliton fission process supports nonlinear optical switching and simultaneous pulse compression to few-cycle durations at the level of 20 fs.
The paper presents the first complex study of Gamma radiation effects on a low-loss perfluorinated polymer optical fiber (PF-POF) based on Cytop® polymer. Influence of gamma radiation on fiber’s optical, mechanical and climatic performance is investigated. The radiation-induced attenuation (RIA) in the visible and near-infrared region (0.4 μm-1.7 mm) is measured and its origins are discussed. Besides attenuation increase, radiation is also shown to decrease the thermal degradation stability of the fiber and to increase its susceptibility to water. With regard to complex fiber transmission performance upon irradiation, the optimal operation wavelength region of PF-POF-based systems intended for use in Radiation environments is determined to be around 1.1 μm. On the other hand, the investigated fiber holds potential for low-cost RIA-based optical fiber dosimetry applications with sensitivity as high as 260 dBm⁻¹/kGy in the visible region.
Impact of gamma radiation on transmission of a commercial Cytop polymer optical fibre (Lucina, Asahi Glass Company) is investigated. Spectral dependence of radiation induced attenuation in the investigated fibre is measured in the VIS-NIR spectral region. Besides attenuation increase, radiation is found to increase fibre susceptibility to water as well. While pristine Cytop fibre is rather humidity insensitive, strong humidity related absorption in the NIR region is observed after fibre irradiation. Selective irradiation of separate fibre sections is proposed as a way of fibre humidity sensitization and quasi-distributed water detection is demonstrated using optical time domain reflectometry at 1310 nm.
The sensitivity of low-loss perfluorinated polymer optical fiber (PF-POF) to gamma radiation is investigated for on-line radiation monitoring purposes. The radiation-induced attenuation (RIA) of a commercial PF-POF based on Cytop material is measured in the visible spectral region. The fiber RIA shows strong wavelength dependence with rapid increase towards the blue side of the spectrum. The wide range of radiation sensitivities is available via careful selection of appropriate monitoring wavelength. The accessible sensitivities span from 1.6 ± 0.2 dBm-1/kGy measured at 750 nm to 18.3 ± 0.7 dBm-1/kGy measured at 420 nm. The fairly high radiation sensitivity as well as its wide tunability makes the fiber a promising candidate for a broad range of applications.
In this work, the potential of fiber Bragg gratings (FBGs) in low-loss perfluorinated polymer optical fibers (PF-POFs) is explored. The FBG is femtosecond-inscribed in a commercial multi-mode (MM) PF-POF based on Cytop® polymer. Femtosecond inscription leads to creation of a highly saturated grating with a number of higher order reflection Peaks visible throughout the visible and near-infrared spectral region. For 2 mm long FBG having a pitch of 2.2895 μm, a total of nine higher-order MM reflection bands are visible spanning from 1548 nm (4th order) to 520 nm (12th order). Strain sensitivity was measured for 6 peak bands in 500-900 nm region, where relatively low cost CCD based spectrometers and broadband LEDs are available. Strain sensitivity increases almost linearly with increasing initial peak wavelength, growing from 4.82 ± 0.02 nm/% measured for 12th order peak at 517 nm to 8.12 ± 0.04 nm/% measured for 7th order peak at 883 nm. These values correspond to roughly 20 % higher sensitivity than silica FBGs exhibit in this spectral range. The gratings in PF-POFs combine the higher strain sensitivity and low-loss operation while maintaining the mechanical advantages of polymer optical fibers. Therefore, they hold a high potential for considerable broadening of polymer optical fiber Bragg gratings application range.
Humidity is one of principal environmental parameters that plays an important role in various application areas. Using measurement of strain induced in an optical fiber by a water swellable coating represents a promising approach for realization of distributed humidity sensing (DHS). In this work, humidity and temperature response of four different commercial PI-coated fibers and four tight-buffered (TB) fibers is investigated with the aim of evaluating their potential for development of DHS in context of water ingress sensor for high-voltage power cable splices. PI-coated fibers exhibited close-to-linear humidity and temperature response. While the temperature response is relatively coating-independent, magnitude of humidity response was broadly correlated to the relative fiber-to-coating thickness ratio. In contrast, both humidity and temperature response of TB fibers is strongly influenced by buffer type, with Leoni TB900L fiber with Hytrel buffer exhibiting largest humidity and temperature sensitivity. While the response of tight-buffered fibers is generally nonlinear, roughly three-times higher humidity response can be achieved with TB900L compared to the most sensitive PI-coated fiber. Using the TB fiber can be, therefore, advantageous for simpler water detection applications, such as one targeted in this study, when larger sensitivity is more important than the linear response of the sensor.