Surface encapsulated micro-nano fiber based on evanescent field photocuring and surface coating preparation device and method

By coating low-refractive-index UV adhesive onto the surface of micro/nano optical fibers using evanescent field curing, the problems of increased sensor volume and reduced sensitivity caused by large-area encapsulation layers are solved, enabling the fabrication of miniaturized and high-resolution sensors. The coating parameters are adjustable and suitable for pre-drawn micro/nano optical fibers.

CN121857133BActive Publication Date: 2026-08-04ZHEJIANG UNIV
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Patent Information

Application Number
CN202610319992.7
Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Filing Date
2026-03-17
Publication Date
2026-08-04
Estimated Expiration
2046-03-17

AI Technical Summary

Technical Problem

In existing technologies, the encapsulation layer of micro-nano fiber optic sensors typically has a large area, which increases the sensor volume and limits spatial resolution and sensitivity. At the same time, the encapsulation process may introduce unnecessary structural changes, and the encapsulation parameters are roughly controlled, making it impossible to achieve rapid real-time adjustment.

Method used

A low-refractive-index UV adhesive is coated onto the surface of a micro/nano optical fiber using an evanescent field curing method. The scanning of the UV adhesive droplets is controlled by a three-dimensional adjustment frame and an electrically controlled displacement stage to form a UV adhesive coating with a thickness of 2-3 μm and a length of 5-10 mm. Rapid curing is achieved using a UV laser, and the scanning speed and power are adjustable to precisely control the coating thickness and length.

Benefits of technology

It achieves miniaturization and high spatial resolution of micro/nano fiber optic sensors. The coating is thin and smooth, reducing the impact on sensor sensitivity. It supports rapid packaging, and the coating parameters are adjustable. It is suitable for pre-drawn micro/nano fibers, and the packaging process does not affect the fiber structure.

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Abstract

This invention discloses a micro / nano optical fiber and surface coating preparation device and method based on evanescent field photocuring for surface encapsulation. The device includes standard optical fibers at both ends, a middle waist fiber, and two transition fiber sections connecting the standard and waist fibers. An ultraviolet (UV) adhesive coating is attached to the waist fiber. Low-refractive-index UV adhesive is cured in situ using an evanescent field transmitted on the outer surface of the micro / nano optical fiber, forming a surface coating that conforms to the fiber's own structure. The coating thickness is as low as the micrometer level. This effectively isolates the evanescent field and avoids surface contamination of the optical fiber, while reducing the size of the micro / nano optical fiber sensor, achieving a spatial resolution at the micrometer level, which is beneficial for miniaturization and integration. The use of low-refractive-index UV adhesive as the coating material ensures that the coating refractive index is lower than that of the optical fiber, allowing the optical signal transmission to meet the total internal reflection waveguide condition, ensuring low-loss transmission. Furthermore, the UV adhesive cures instantaneously within 0.1–1 s under UV light irradiation, supporting the formation of the surface coating during rapid movement.
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