Hermetic Carbon-Coated Fiber Bragg Gratings for Harsh Environments
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Fiber-based devices, such as fiber Bragg gratings, face reliability and mechanical robustness issues in harsh environments like high humidity or hydrogen-rich conditions, requiring shielding to maintain performance.
Innovation Solution
A method for fabricating gratings in carbon-coated optical fibers using a hermetic carbon coating that allows inscription of refractive index modulations through the carbon layer, enabling the creation of fiber Bragg gratings that can withstand harsh environments by protecting against water and hydrogen ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fiber Bragg gratings are used in harsh environments (humid or hydrogen-rich), then optical functionality is compromised, but adding shielding increases device complexity
Solution Approach 1:
The patent applies a hermetic carbon coating (thin film) on the optical fiber to provide environmental protection against humidity and hydrogen. This thin film barrier prevents harmful substances from penetrating to the grating structure, ensuring optical reliability without requiring complex multi-layer shielding systems.
2Reliability
If a hermetic carbon coating is applied to protect the fiber, then environmental resistance improves, but the complexity of the coating process increases
Solution Approach 1:
The patent combines the carbon coating application with the existing optical fiber drawing process. The carbon coating is deposited on the fiber as it is being drawn from the preform, integrating two manufacturing steps into one continuous process. This eliminates the need for separate coating equipment and process steps, maintaining ease of manufacture while providing hermetic protection.
3Manufacturing precision
If refractive index modulations are inscribed through the carbon layer, then grating fabrication is enabled, but there is a risk of breaching the hermetic seal
Solution Approach 1:
The patent uses a UV laser to inscribe the refractive index modulations through the carbon coating. The laser energy is absorbed by the glass core, creating the grating structure without mechanical contact. This non-contact method allows precise grating fabrication while maintaining the integrity of the carbon coating, as the laser wavelength and power are controlled to modify only the glass refractive index without compromising the hermetic seal.
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 solution provides fiber Bragg gratings with improved fatigue resistance and optical reliability in harsh environments, maintaining mechanical strength and optical performance without breaching the hermetic seal, enabling their use in humid and hydrogen-rich conditions.
Implementation Method 1
a laser having a beam output that is configured to inscribe one or more refractive index modulations into the optical fiber through the hermetic carbon layer
Implementation Method 2
inscribe one or more optical devices into the optical fiber through the hermetic carbon layer
Data Source
AI summary
A technique is described for fabricating one or more optical devices in a carbon-coated optical fiber. A photosensitive optical fiber is provided having a hermetic carbon coating. Further provided is a laser having a beam output that is configured to inscribe one or more refractive index modulations into the optical fiber through the hermetic carbon layer while leaving the hermetic carbon layer intact. The laser is used to inscribe one or more optical devices into the optical fiber through the hermetic carbon layer.