Online Gamma Radiation Monitoring Using Few-Mode Polymer CYTOP Fiber Bragg Gratings

Area of Science:

• Materials Science
• Optoelectronics
• Radiation Physics

Background:

• Fiber Bragg gratings (FBGs) are crucial optical sensors.
• Polymer optical fibers offer unique properties but their radiation response is less understood.
• FBGs in polymer fibers are potential candidates for radiation dosimetry.

Purpose of the Study:

• To investigate the gamma radiation response of FBGs inscribed in a few-mode polymer optical fiber (CYTOP core).
• To determine the sensitivity and recovery characteristics of these FBGs under gamma irradiation.
• To assess the suitability of CYTOP FBGs for gamma radiation dosimetry applications.

Main Methods:

• Inscribing FBGs in a few-mode polymer optical fiber with a CYTOP core and XYLEX overclad.
• Exposing four FBGs to gamma radiation at a dose rate of 5.3 kGy/h across four sessions.
• Measuring Bragg wavelength shifts and reflection power changes as a function of radiation dose.
• Analyzing the effect of temperature on FBG sensitivity and recovery.

Main Results:

• FBGs exhibited a linear Bragg wavelength shift with increasing gamma radiation dose.
• Mean sensitivity was -3.95 pm/kGy at 43 °C, increasing to -10.6 pm/kGy at 58 °C.
• Partial recovery of FBGs was observed post-irradiation, with recovery increasing with dose.
• Reflection power decreased with dose due to radiation-induced attenuation in the CYTOP fiber.

Conclusions:

• CYTOP FBGs demonstrate a linear response to gamma radiation, indicating potential for dosimetry.
• Temperature dependence of sensitivity necessitates compensation for accurate measurements in practical applications.
• Radiation-induced attenuation in the CYTOP fiber affects signal strength, requiring consideration for sensor design.