Berruti, Gaia Maria Scherino, Lorenzo Vaiano, Patrizio Zuppolini, Simona Zotti, Aldobenedetto Quero, Giuseppe Zarrelli, Mauro Borriello, Anna Petagna, Paolo Cusano, Andrea Consales, Marco J. Lightwave Technol. 10.1109/JLT.2025.3650002 2858-2865 44 7 Radiation effects Fiber gratings Sensors Neutrons Temperature sensors Inductors Gratings Optical fiber sensors Coatings Optical fibers Optical Fiber Harsh Environments Fiber Bragg Grating Neutron Irradiation Optical Grating Operating Conditions Femtosecond Laser Wavelength Shift Monitoring Platform Neutron Flux Real Operating Conditions Redshift Blue Shift Radiation Exposure Electromagnetic Interference Nuclear Power Plant Power Variation Inscription Fabrication Techniques Shielding Effect Resonance Wavelength Resonance Wavelength Shift Visible Reduction Reactor Core Resonance Shift Irradiation Experiments Radiation Shielding Reactor Operation Radiation Sensitivity Types Of Radiation FBG LPG nanoscale coating neutron irradiation optical fiber sensors radiation effects radiation shielding 2026 2026 Monitoring in radiation-intensive environments poses major challenges for conventional sensing technologies, which often suffer from performance degradation, high maintenance demands and limited long-term stability. In this context, optical fiber (OF) sensors represent a promising alternative. However, their deployment in such applications requires a systematic qualification of their radiation response under realistic operating conditions. In this work we report on results collected during the first neutron irradiation campaign of both bare and titanium dioxide-coated UV-written Long Period Gratings (LPGs), as well as Fiber Bragg Gratings (FBGs) inscribed by UV and femtosecond laser techniques, in photosensitive B-Ge doped fibers. The LPGs were exposed to a cumulative neutron fluence of ∼3.4 × 1015 n/cm2, while the FBGs to a higher fluence of ∼8.6 × 1015 n/cm2. The spectral response of the investigated samples under neutron irradiation was analyzed with respect to wavelength shifts and visibility variations. Collected results clearly demonstrate the robustness of OF devices in neutron environments and highlight the potential of nanoscale coatings to design radiation-hardened optical sensors. Moreover, such advances enable strategies for the development of enhanced OF sensing platforms for environmental monitoring in nuclear and high-energy physics applications.