Development of a Miniaturized and Radiation-Hardened Optoelectronic Acquisition Chain for Radioluminescent Fiber Dosimeters in Space Environments

*****Context and challenges*****

Reliable measurement of ionizing radiation is a strategic challenge in the space sector. Satellites, scientific instruments, and crewed missions are exposed to complex radiation environments (protons, electrons, gamma rays, neutrons) that can degrade electronic components, alter sensors, or compromise mission safety.

To address these constraints, CNES is developing onboard dosimetry solutions capable of monitoring radiation levels in real time, while meeting the stringent mass, power, and robustness requirements of space applications.

Among emerging technologies, optical fiber dosimeters based on radioluminescence (RIL) stand out due to their lightweight design, ease of integration, and ability to detect extremely low radiation fluxes (a sensitivity down to 200 µGy/h has already been demonstrated in the laboratory).

Recent joint work by TRAD, CNES, and the Hubert Curien Laboratory, including the publication by Selyan Acid [doi: 10.1109/JSEN.2025.3549154], has highlighted both the strong potential and the current limitations of this approach for space deployment. These studies show that the RIL signal depends on several physical parameters: temperature, fiber composition, and irradiation conditions all influence the emitted signal. Moreover, parasitic phenomena such as thermoluminescence can overlap with the pure radioluminescence signal, leading to errors in dose-rate estimation. These effects make the optical signal calibration environment-dependent, thus requiring a multi-parameter calibration approach.

These findings emphasize both the need and the feasibility of developing an advanced optoelectronic acquisition chain, capable of measuring the light signal with very high sensitivity while dynamically characterizing thermal influences to ensure reliable dosimetry. The development of such a miniaturized, radiation-hardened, and multiparameter-calibrated system constitutes the core objective of this PhD project.

*****PhD objectives*****

Building upon the expertise of the CNES and UJM partners, the goal of this PhD is to design, model, and validate an integrated optoelectronic acquisition chain for the readout of radioluminescent fiber dosimeters, using high-sensitivity photon detectors such as SPADs (Single Photon Avalanche Diodes) or SiPMs (Silicon Photomultipliers).

The doctoral candidate will aim to transfer laboratory-grade performance (sensitivity, dynamic range, stability) to a space-compatible embedded system, combining:

• Miniaturization and low power consumption,

• Radiation and thermal hardening, and

• Multiparameter calibration to correct parasitic effects (thermoluminescence, temperature, aging).

*****Scientific program*****

1. Development of the optoelectronic acquisition chain

• Design of a detection head integrating SPAD or SiPM detectors, low-noise front-end electronics, thermal management, and optical filtering.

• Development of the photon acquisition chain: amplification, counting, gain control, and embedded processing on microcontroller or FPGA.

• Optimization for low power consumption, compactness, and radiation tolerance.

2. Benchmarking and experimental validation

• Comparative evaluation against laboratory-grade measurement systems (photodiodes, PMTs, spectrometers).

• Sensitivity, linearity, noise, and thermal stability testing, as well as performance under irradiation.

• Environmental qualification campaigns (thermal cycling, vibration) in collaboration with CNES to validate prototype robustness.

3. Modeling and multiparameter calibration

• Development of a model combining the effects of dose, temperature, fiber type, and irradiation conditions.

• Separation of RIL, thermoluminescence, and other parasitic contributions using temporal and spectral analysis.

• Construction of a multiparameter calibration curve and implementation of correction algorithms within the embedded system firmware.

*****Work environment*****

The PhD candidate will be hosted primarily at CNES, with working periods at the Hubert Curien Laboratory, both renowned for their expertise in optoelectronics under radiation and photonics instrumentation.

CNES will provide its expertise in space system design, radiation hardening, and environmental qualification while LabHC will provide its expertise in dosimetry and the access to its new PETRA platform (3 X-ray machines optimized for dosimetry studies)

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For more Information about the topics and the co-financial partner (found by the lab!); contact Directeur de thèse - sylvain.girard@univ-st-etienne.fr

Then, prepare a resume, a recent transcript and a reference letter from your M2 supervisor/ engineering school director and you will be ready to apply online before March 13th, 2026 Midnight Paris time!