This review focuses on silica-based optical fibers, guiding light through the total internal reflection mechanism, that are currently used in telecommunications and sensor networks. Section I briefly introduces the fiber and fiber sensor technologies. Section II presents their various applications in radiation environments. In section III, the radiation effects on optical fibers are explained, first at a microscopic scale, with the description of point defects generated by irradiation. Then, the macroscopic consequences of the appearance of these point defects are discussed, in particular the phenomena of radiation-induced attenuation (RIA), radiation-induced emission (RIE) and radiation-induced refractive index change (RIRIC). RIA impacts nearly all applications under irradiation. We then detail the various parameters, intrinsic or extrinsic to the optical fibers that influence their amplitudes and kinetics. This improved knowledge paved the way for the radiation hardening of optical fibers through various approaches, either at material, component or system levels, that are described in section IV. Recent advances are presented for passive and for active rare-earth doped optical fibers and systems. Then, the use of fiber optic sensors is introduced, starting in section V with the latest advances in radiation-hardened point or distributed sensors. Then, the potential of this technology for radiation detection, beam instrumentation and dosimetry applications is assessed in section VI. Finally, the future prospects and the main challenges to be met in order to accelerate the implementation of this technology in the harshest environments are discussed.

We investigated the influence of modifying the voltage of an X-ray tube with a tungsten anode between 30 kV and 225 kV, and therefore its photon energy spectrum (up to 225 keV), on the Total Ionizing Dose deposited in a single-mode, phosphorus-doped optical fiber, already identified as a promising dosimeter. Simulation data, obtained using a toolchain combining SpekPy and Geant4 software, are compared to experimental results obtained on this radiosensitive optical fiber and demonstrate an increase of the deposited dose with operating voltage, at a factor of 4.5 between 30 kV and 225 kV, while keeping the same operating current of 20 mA. Analysis of simulation results shows that dose deposition in such optical fibers is mainly caused by the low-energy part of the spectrum, with 90% of the deposited energy originating from photons with an energy below 30 keV. Comparison between simulation and various experimental measurements indicates that phosphosilicate fibers are adapted for performing X-ray dosimetry at different voltages.

The potential of fiber-based sensors to monitor the fluence of atmospheric neutrons is evaluated through accelerated tests at the TRIUMF Neutron Facility (TNF) (BC, Canada), offering a flux approximatively 10⁹ higher than the reference spectrum observed under standard conditions in New York City, USA. The radiation-induced attenuation (RIA) at 1625 nm of a phosphorus-doped radiation sensitive optical fiber is shown to linearly increase with neutron fluence, allowing an in situ and easy monitoring of the neutron flux and fluence at this facility. Furthermore, our experiments show that the fiber response remains sensitive to the ionization processes, at least up to a fluence of 7.1 × 10¹¹ n cm⁻², as its radiation sensitivity coefficient (~3.36 dB km⁻¹ Gy⁻¹) under neutron exposure remains very similar to the one measured under X-rays (~3.8 dB km⁻¹ Gy⁻¹) at the same wavelength. The presented results open the way to the development of a point-like or even a distributed dosimeter for natural or man-made neutron-rich environments. The feasibility to measure the dose caused by the neutron exposure during stratospheric balloon experiments, or during outer space missions, is presented as a case study of a potential future application.

The authors report GaN pin photodetectors with very low dark currents (< 10 pA at –10 V), and high external quantum efficiencies (~35%). These photodetectors have a flat responsivity above the bandgap (measured at ~0.10 A/W) with a sharp, solar-blind cutoff at the band edge.

Total Ionizing Dose (TID) effects induced by different photon sources are studied in MOS devices. The Dose Factor (DF), defined as the ratio between dose deposition in dosimeter and actual dose deposition in MOS sensitive oxides, is estimated using Monte-Carlo simulations of energetic photons striking simple device structures. An effective TID approach is proposed to account for both the real ionizing dose depositions in small volumes and the charge yield. This method is applied to a Silicon-On-Insulator (SOI) technology using three photon sources: the usual ARACOR and 60Co sources, which deliver several tens of keV photons and 1.25 MeV photons respectively, and a third facility named ORIATRON, a 6 MeV electron linear accelerator that produces photons on a wide energy spectrum. This topic, investigated intensively in the literature a few decades ago, is revisited in the context of several evolutions including: new radiation sources, novel simulation tools and device scaling which all impact ionizing dose deposition in micro-sensitive volumes of current electronic technologies. Dedicated numerical simulations demonstrate the importance of taking into account the entire stack of materials in order to get the most accurate estimations of TID in the sensitive oxide. Descriptions of the Back-End-Of-Line (BEOL) layers (especially when the technology uses Copper), the polysilicon gate, the BOX (for SOI devices), but also of the substrate and package are mandatory in these simulations, since dose enhancement and/or backscattered photons can be a significant source of TID variation in the gate oxide. Also the package lid composition and its thickness can be major TID contributors. The results show that the use of a pre-filter with lead and aluminum can optimize ionizing dose deposition.