CN113548797A

CN113548797A - Preparation method of elliptical core optical fiber

Info

Publication number: CN113548797A
Application number: CN202110750226.3A
Authority: CN
Inventors: 马一巍; 苏春博; 李晓飏; 易杨; 耿涛; 孙伟民
Original assignee: Harbin Engineering University
Current assignee: Harbin Engineering University
Priority date: 2021-07-02
Filing date: 2021-07-02
Publication date: 2021-10-26

Abstract

The invention provides a method for preparing an elliptical core optical fiber, which comprises the steps of firstly, taking a section of long circular core optical fiber, carrying out double-sided polishing on the optical fiber part without a protective layer by using an optical fiber polishing device, grinding the optical fiber into a sheet shape, and observing the polishing depth condition of the optical fiber by using a microscopic observation device; heating the optical fiber sheet region by using a device for heating the optical fiber, and applying small tension to the heating part by using an electric precision displacement table; at the moment, the optical fiber sheet is heated to be in a molten state, and due to the tension on the surface of the optical fiber, the material distribution of the sheet structure is rearranged, so that the structural section shape of the optical fiber sheet is changed into a circular shape from the whole body, and meanwhile, the circular core is changed into an elliptical core, and the elliptical core optical fiber is obtained. The invention can accurately control the core layer ovality of the elliptical core optical fiber, and because the material is the single-mode optical fiber which is easy to obtain and has lower cost, large-scale manufacturing equipment such as an optical fiber drawing tower and the like is not needed.

Description

Preparation method of elliptical core optical fiber

Technical Field

The invention belongs to the technical field of optical fiber preparation, and particularly relates to a preparation method of an elliptical core optical fiber, which can be applied to the fields of optical fiber communication, optoelectronic devices and optical fiber sensing.

Background

The optical fiber gyroscope can measure the direction of a moving object, is a navigation instrument widely used in the field of modern aerospace, and has been commercially successful. In order to achieve an accurate measurement of the state of motion of an object, a fiber optic gyroscope typically includes three sensing loops of polarization maintaining fiber, each loop corresponding to a desired degree of freedom. Due to the polarization maintaining characteristic, the elliptical core optical fiber can be used as a core device of the optical fiber gyroscope. Therefore, the elliptical core fiber has great potential in the application of the future fiber optic gyroscope.

At present, the main methods for preparing the elliptical core optical fiber are a grinding method and a reduced pressure sintering method. The elliptical core optical fiber is prepared by a grinding method, firstly, a cladding and a core rod are deposited according to requirements, arcs on two sides of the core rod are ground to be flat, and then, high-temperature wire drawing is carried out, so that the elliptical core optical fiber can be obtained. In the method, the processing surface of the prefabricated rod is approximate to an ellipse, so that polishing and grinding processing difficulty is high, the cross section of the drawn optical fiber is not uniform, and longitudinal uniformity is not easy to guarantee. The elliptical core optical fiber perform is prepared by a decompression sintering method, a cladding layer and a core layer are deposited on the inner wall of a substrate tube by utilizing a vapor deposition process, then the air pressure in the tube is reduced to ensure that the air pressure in the deposition tube is smaller than that of the external environment, then the temperature is increased, and the core layer is fused into an ellipse under the action of the environment with low pressure and high temperature, so that the elliptical core optical fiber perform can be obtained. The process of preparing the elliptical core optical fiber preform by applying the decompression sintering shrinkage method has multiple steps and high difficulty, and needs a precise processing instrument, so that the preparation cost and the difficulty of the elliptical core optical fiber are greatly improved. Meanwhile, due to processing errors, the preparation method is difficult to accurately ensure the ovality of the fiber core.

In the three forms of matter (solid, liquid and gas), liquid and gas share a common characteristic-the flowability, and are collectively referred to as fluids. From a mechanical point of view, a fluid is an object that deforms continuously under any slight shear force. As long as this force continues to exist, the deformation does not stop. To characterize the properties of a fluid, it is usually described in terms of physical quantities such as density, pressure, temperature and velocity.

Due to the attractive forces between the molecules, a slight pulling force is created at the interface between the liquid and the gas, which force is called "surface tension" and causes the liquid surface to shrink as much as possible. The direction of the surface tension is tangential to the liquid surface and perpendicular to the boundary between any two parts of the liquid surface.

Disclosure of Invention

The invention aims at the defects in the preparation process of the traditional special optical fiber with the elliptical core, such as: the method has multiple steps and high difficulty, needs large-scale optical fiber drawing equipment, and provides the method for manufacturing the elliptical core optical fiber with the controllable fiber core ellipticity. The raw material is the round core optical fiber, so that the preparation cost of the special elliptical core optical fiber is greatly reduced.

The purpose of the invention is realized as follows:

a method for preparing an elliptical core optical fiber comprises the following steps:

(1) removing a coating layer of a section of single-mode fiber, wiping the coating layer with absolute ethyl alcohol, polishing and grinding a cladding of the round-core fiber by using a fiber grinding device, wherein the single-mode fiber comprises the cladding and a core layer, the width of the fused cladding is about 60 mu m, and the fused parts are mutually symmetrical to form a preprocessed formed product.

(2) And (2) placing the preprocessed formed product in the step (1) on high-temperature heating equipment, fixing two ends of the preprocessed formed product on an optical fiber clamp on an electric translation table, placing cladding layers of the preprocessed formed product in parallel and symmetrical positions on the center of an omega-shaped graphite heating resistor for high-temperature melting, wherein the heating temperature is about 1200 ℃.

(3) And (3) stretching the pre-processed formed product in the molten state in the step (2), controlling two hand electric translation stages of the tapering machine to move in the same direction according to actual requirements, and stretching to obtain a finished product by generating a speed difference due to different speeds, wherein the elliptical core optical fiber comprises a cladding layer and a core layer.

(4) Observing the ovality of the elliptical core optical fiber prepared in the step (3) by using an optical fiber side observation device, if the ovality is not met, returning to the step (3) to reheat and draw, and if the ovality is met, coating the finished elliptical core optical fiber by using an optical fiber coating device.

Compared with the prior art, the invention has the beneficial effects that:

the invention can accurately control the core layer ovality of the elliptical core optical fiber, and because the material is the single-mode optical fiber which is easy to obtain and has lower cost, large-scale manufacturing equipment such as an optical fiber drawing tower and the like is not needed.

The invention simplifies the preparation process of the elliptical core optical fiber and realizes the preparation of the elliptical core optical fiber with adjustable ellipticity on the basis of commercial finished round core optical fiber; the elliptical core optical fiber prepared by the invention can be widely applied to the aspects of optical fiber power sensing, optical fiber magnetic field sensing and the like.

Drawings

FIG. 1 is a schematic cross-sectional view of a pre-processed shaped article processed in an embodiment of the present invention;

FIG. 2 is a schematic cross-sectional view of a partially oval core optical fiber product according to an embodiment of the present invention;

FIG. 3 is a three-dimensional schematic diagram of a double-side polished optical fiber according to an embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

First, a long segment of round core optical fiber is taken, and the optical fiber part with the protective layer removed is polished on both sides by an optical fiber polishing device. The optical fiber is ground into a sheet shape, and the polishing depth condition of the optical fiber can be observed by a microscopic observation device;

a method for manufacturing an elliptical core optical fiber using a device for heating the optical fiber such as: an oxyhydrogen flame heating device, a graphite heating device, a laser heater or the like, which heats the optical fiber sheet region and applies a small pulling force to the heating part by using an electric precision displacement table; at the moment, the optical fiber sheet is heated to be in a molten state, and due to the tension on the surface of the optical fiber, the material distribution of the sheet structure is rearranged, so that the structural section shape of the optical fiber sheet is changed into a circular shape from the whole body, and meanwhile, the circular core is changed into an elliptical core, and the elliptical core optical fiber is obtained.

According to the method for preparing the elliptical core optical fiber, under the condition of certain heating temperature, the ellipticity of the fiber core can be controlled by the polishing and grinding amount of the optical fiber. When more substances are thrown off from two sides, the ovality of the fiber core is larger after the optical fiber sheet is reshaped into a circle under the action of heating and stretching, and the ovality is smaller otherwise. Therefore, under the condition of accurately controlling the polishing amount, the ovality of the elliptical core can be adjusted.

Example 1: a method for preparing an elliptical core optical fiber comprises the following steps:

(1) removing a coating layer of a section of single-mode fiber, wiping the coating layer with absolute ethyl alcohol, and polishing and grinding a cladding of the round-core fiber by using a fiber grinding device, wherein the single-mode fiber comprises a cladding layer 1 and a core layer 2, the width of the fused cladding layer 1 is about 60 mu m, and the fused parts are symmetrical to each other to form a preprocessed formed product, as shown in figure I.

(3) And (3) stretching the pre-processed formed product in the molten state in the step (2), controlling two hand electric translation stages of a tapering machine to move in the same direction according to actual requirements, and stretching the product to obtain a finished product by generating speed difference due to different speeds, wherein the elliptical core optical fiber comprises a cladding layer 3 and a core layer 4 as shown in fig. 2.

Claims

1. A method for preparing an elliptical core optical fiber is characterized by comprising the following steps:

(1) removing a coating layer of a section of single-mode fiber, wiping the coating layer with absolute ethyl alcohol, polishing and grinding a cladding of the round-core fiber by using a fiber grinding device, wherein the single-mode fiber comprises a first cladding and a first core layer, the width of the fused cladding is about 60 mu m, and the fused parts are mutually symmetrical to form a preprocessed formed product;

(2) placing the preprocessed formed product in the step (1) on high-temperature heating equipment, fixing two ends of the preprocessed formed product on an optical fiber clamp on an electric translation table, placing cladding layers of the preprocessed formed product in parallel and symmetrical positions on the center position of an omega-shaped graphite heating resistor for high-temperature melting, wherein the heating temperature is about 1200 ℃;

(3) stretching the pre-processed formed product in the molten state in the step (2), controlling two hand electric translation stages of a tapering machine to move in the same direction according to actual requirements, and controlling the speeds to be different to generate speed difference to stretch the product to obtain a finished product, wherein the elliptical core optical fiber comprises a second cladding layer and a second core layer;