Gamma-radiation enhancement of sensing properties of FBGs in a few-mode polymer CYTOP fiber

Abstract

We investigate the effect of γ-radiation on temperature (T) and relative humidity (RH) sensitivities of polymer perfluorinated fiber Bragg gratings (FBGs). To this aim, different γ-radiation doses (80, 120, 160, and 520 kGy) were applied to a set of FBGs. We show that irradiated FBGs demonstrate an RH sensitivity rise with the received dose: from 13.3 pm/%RH for a pristine FBG up to 56.8 pm/%RH for a 520-kGy dose at 30℃. In contrast, T sensitivity decreases with radiation dose with a subsequent change of sign from positive to negative. Therefore, by experimental interpolation, T sensitivity can be eliminated at around a 160-kGy dose. This opens the possibility of designing an RH sensor with enhanced sensitivity, which at the same time is insensitive to T.

Power Flow in Multimode Graded-Index Microstructured Polymer Optical Fibers

“…POF has the benefit of an easy connection and a large core, which could be an economic solution for the in-home network. Different kinds of materials are implemented for POF fabrication, such as polymethyl methacrylate (PMMA) [ 3 , 4 ], polydimethylsiloxane (PDMS) [ 5 , 6 ], polycarbonate (PC) [ 7 , 8 ], polystyrene (PS) [ 9 , 10 ], perfluorinated polymer (commercially known as CYTOP ® (AGC, Inc., Tokyo, Japan) [ 11 , 12 ], cycloolefin polymer (commercially known as ZEONEX ® *ZEON (Corporation, Tokyo, Japan)) [ 13 , 14 ], and cycloolefin copolymer (commercially known as TOPAS ® ) (TOPAS Advanced Polymers, Farmington Hills, MI, USA) [ 15 , 16 ]. The flexibility of POF material allows for the production of POFs with varying specifications or materials to meet the needs of various applications.…”

Temperature and RH response of polymer CYTOP FBG treated by gamma radiation

“…In our previous works [7][8][9], we demonstrated that gamma radiation treatment changes the climatic properties of CYTOP FBGs: we observed a rise of the RH sensitivity with received dose and a decrease of temperature sensitivity with subsequent change of sign from positive to negative. Among irradiation doses, which we applied in the experiment, the dose of 200 kGy provided the closest to zero temperature sensitivity of the irradiated FBGs [7,8]. This case is prospective for RH sensing since temperature cross-sensitivity can be eliminated.…”

“…However, practical realization of RH sensors requires temperature crosssensitivity elimination. A certain optimal fiber pre-strain [6] and gamma irradiation of FBGs of up to optimal dose [7][8][9] are potential solutions recently proposed for CYTOP ® FBGs.…”

Elimination of temperature cross-sensitivity for polymer FBG-based humidity sensor by gamma radiation treatment

“…Taking the above into account, we excluded the sensitivity of the FBG with a 520 kGy received dose from a linear approximation. Irradiated FBGs demonstrate not only a decrease of temperature sensitivity, but also a rise of RH sensitivity [22]. It rises from 13.3 pm/%RH for pristine FBG up to 56.8 pm/%RH for the case of 520 kGy dose.…”

“…Recently, we tested irradiated FBGs in the environmental chamber and we found that gamma radiation increases the sensitivity of perfluorinated FBGs to relative humidity (RH) and decreases their temperature sensitivity. In particular, among the applied dosed of 80, 120, 160 and 520 kGy, the FBG irradiated up to 160 kGy demonstrated the closest to zero temperature sensitivity [22]. This case is attractive for RH sensing since the temperature cross-sensitivity is minimized.…”