Silicon Fiber-Optic Sensor Fabry-Pérot Cavity Temperature Resolution

The patent creates a composite structure by attaching a silicon layer or silicon pillar to the tip of a fused silica optical fiber. The silicon component provides high thermo-optic coefficient and thermal diffusivity for improved temperature sensitivity and response time, while the fused silica fiber maintains compatibility with standard optical fiber infrastructure. This composite approach combines the advantages of both materials to resolve the contradiction between ease of manufacture and measurement precision.

The invention applies local quality modification by concentrating the high-performance silicon sensing element at the tip of the optical fiber where temperature measurement is required. The bulk of the optical fiber remains as fused silica for mechanical strength and optical transmission, while only the local sensing region uses silicon to achieve high temperature sensitivity without requiring the entire fiber structure to be made of silicon.

The composite structure combines fused silica optical fiber with a silicon sensing element at the tip. Silicon's high thermal diffusivity (approximately 90 times greater than fused silica) enables rapid heat conduction and quick thermal equilibrium, achieving response times of 0.51 ms compared to seconds for pure fused silica sensors, while maintaining compatibility with standard optical fiber systems.

The silicon sensing element is localized at the fiber tip where temperature measurement occurs. This local substitution of material with superior thermal properties allows fast response time without requiring the entire optical fiber to be made of silicon, preserving the mechanical and optical advantages of fused silica while achieving rapid thermal response at the sensing location.

The patent achieves high temperature resolution (6×10−4° C) by changing the material parameter at the sensing location from fused silica to silicon, which has a much higher thermo-optic coefficient. The silicon layer or pillar creates a Fabry-Pérot cavity that enhances the temperature sensing capability through interference patterns, allowing precise measurement while managing the added complexity through systematic attachment methodologies.

The silicon layer acts as an intermediary element between the optical fiber and the temperature field. It converts thermal changes into optical phase changes within the Fabry-Pérot cavity, enabling high-resolution temperature measurement. The structured attachment processes (fusion splicing, ultraviolet-curable glue bonding) provide systematic methods to manage the complexity of integrating this intermediary component.

The attachment process is segmented into distinct stages: first, fusion splicing is used to attach the silicon layer to the optical fiber tip; second, ultraviolet-curable glue bonding is applied to secure the structure. This segmentation allows each attachment method to be optimized for its specific function while providing clear process control and quality assurance points, managing manufacturing complexity through systematic division of the attachment process.

The patent employs preliminary actions in the manufacturing process by first performing fusion splicing to establish the primary optical and thermal connection, then applying ultraviolet-curable glue bonding to reinforce and secure the structure. The preliminary fusion splicing creates a stable foundation that enables subsequent glue bonding to be more effective, and both steps are designed to be performed in sequence to achieve the desired temperature sensitivity while managing process complexity through predetermined process steps.