Cerium Co-Doped Phosphosilicate Fiber Radiation Hardening
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Solution Overview
Problem
Rare earth doped optical fibers, particularly those with a phosphosilicate matrix, are highly sensitive to ionizing radiation, leading to significant attenuation and reduced transmission capabilities, making them unsuitable for use in radiative environments such as space or nuclear facilities.
Innovation Solution
Incorporating cerium co-doping into the core of the optical fiber, along with potential additional steps like fluorine co-doping and hydrogenation, to enhance radiation resistance, specifically for erbium-ytterbium co-doped fibers, which reduces radiation-induced attenuation and improves long-term performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rare earth doped optical fibers are used in radiative environments, then electromagnetic immunity and wide bandwidth are improved, but radiation-induced attenuation increases significantly
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition of the optical fiber core through cerium co-doping. Specifically, cerium ions (Ce3+) are introduced into the phosphosilicate glass matrix alongside rare earth dopants (erbium, ytterbium, neodymium, or thulium). This compositional parameter change transforms the fiber's radiation response characteristics, enabling it to withstand ionizing radiation while maintaining optical transmission properties.
Solution Approach 2:
The patent employs composite materials by creating a multi-component doped glass system. The core consists of phosphosilicate glass containing multiple dopants: rare earth ions for optical amplification/lasing, phosphorus for glass matrix modification, and cerium for radiation hardening. This composite approach combines the beneficial properties of each component to achieve both optical functionality and radiation resistance.
2Ease of manufacture
If phosphorus is added to the silica core to modify glass properties, then manufacturing flexibility is improved, but radiation-induced attenuation increases due to POHC and P1 defect centers
Solution Approach 1:
The patent uses cerium ions as an intermediary element that mediates between the phosphorus-doped glass matrix and the rare earth dopants. Cerium acts as a radiation hardening agent that specifically targets and mitigates the harmful effects of phosphorus-related defect centers (POHC and P1) while preserving the beneficial optical properties provided by phosphorus and rare earth dopants. The cerium ions interact with radiation-induced defects to prevent their formation or reduce their impact on optical transmission.
3Illumination intensity
If conventional optical fibers are exposed to ionizing radiation, then initial transmission is maintained, but long-term performance degrades due to accumulated radiation damage
Solution Approach 1:
The patent applies preliminary action by incorporating cerium dopants into the optical fiber core during the manufacturing process, before the fiber is deployed in radiative environments. This pre-doping approach proactively prepares the glass matrix to resist radiation damage, rather than attempting to repair or mitigate effects after exposure. The cerium ions are positioned within the glass structure in advance to intercept and neutralize radiation-induced defects as they form, preventing cumulative degradation over time.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The cerium co-doped optical fibers exhibit significantly reduced degradation under ionizing radiation, maintaining over 80% of initial power output even after high radiation doses, and show signs of partial recovery post-irradiation, making them suitable for applications in radiative environments.
Implementation Method 1
the cerium codoping makes it possible to reduce the sensitivity of the optical fiber to radiation, and in particular to ionizing radiation
Implementation Method 2
the exposure of an optical fiber to radiation induces a degradation of the optical performance, in particular an increase in the linear attenuation of the fiber (known as attenuation induced by irradiation or RIA for Radiation Induced Attenuation)
Implementation Method 3
Optical fibers have known a very strong development because of their high-speed information transmission properties
Data Source
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AI summary
The present invention relates to radiation-resistant optical fibre comprising at least one core and at least one first cladding surrounding said core. According to the invention, said core comprises a phosphosilicate matrix, said core being rare-earth doped, the rare earth being chosen from erbium, ytterbium, neodymium, thulium or erbium-ytterbium or thulium-holmium codoped and said core is cerium codoped. The invention also relates to a method for radiation-hardening an optical fibre comprising the core having a phosphosilicate matrix, said core being rare-earth doped, the earth being chosen from erbium, ytterbium, neodymium and thulium, or erbium-ytterbium or thulium-holmium codoped, and including a step of cerium codoping the core of said fibre.