Die Eignung von Faser-Bragg-Gitter-(FBG)-Sensoren zur Messung ionisierender Strahlung wurde an einem Undulator des Elektronenspeicherrings BESSY II untersucht. Über einen Zeitraum von 20 Wochen wurde eine durch Strahlung verursachte Bragg-Wellenlängenänderung der FBG-Sensoren von 25pm gemessen, was einer Strahlendosis von 720 Gy entspricht.
The suitability of using fiber Bragg grating (FBG) sensors for the measurement of ionizing radiation on the electron storage ring BESSY II by measuring the Bragg wavelength shift caused by radiation was investigated. During a time period of 20 weeks a Bragg wavelength shift of 25pm caused by the ionizing radiation was measured by FBG sensors at the storage ring. This Bragg wavelength shift corresponds to a radiation dose value of 720 Gy.
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.