Hollow-core optical fiber mode field diameter testing device and method based on far field method

Abstract

The invention discloses a hollow-core optical fiber mode field diameter testing device and method based on a far field method, and relates to the technical field of hollow-core optical fiber testing, a control unit is mainly responsible for work and time sequence of all devices in the whole device, and a light source is an injection light source when a hollow-core optical fiber to be tested. The hollow-core optical fiber automatic coupling unit can automatically couple light emitted by the light source into a to-be-tested hollow-core optical fiber, the multifunctional displacement table can move in the X direction, the Y direction and the Z direction at the tested end of the to-be-tested hollow-core optical fiber, and the vertical rotating platform is a moving device for scanning the power of the end face of the to-be-tested hollow-core optical fiber. The power detection unit collects end face power of a to-be-detected hollow-core optical fiber, the hollow-core optical fiber end face image collection unit collects a detected end face image of the to-be-detected hollow-core optical fiber, and the signal analysis unit analyzes and processes collected power signals. According to the invention, the optical fiber end face image observation unit is matched with the multifunctional displacement table, so that automatic, efficient and multi-dimensional hollow-core optical fiber mode field diameter testing can be realized.

Description

Technical Field

[0001] This invention relates to the field of hollow fiber testing technology, specifically to a device and method for testing the mode field diameter of hollow fiber based on the far-field method. Background Technology

[0002] The mode field diameter of hollow optical fibers is an important performance indicator, making its measurement crucial. The core of a hollow optical fiber is made of air, vacuum, or an inert gas, and the mode pattern distribution is polygonal. Therefore, the mode field diameter needs to be measured in multiple dimensions, but currently available fiber mode field diameter testing systems lack multi-dimensional testing capabilities. Summary of the Invention

[0003] This invention provides a device and method for testing the mode field diameter of hollow optical fibers based on the far-field method. By using an optical fiber end-face image observation unit and a multi-functional displacement stage, automatic, efficient, and multi-dimensional testing of the mode field diameter of hollow optical fibers can be achieved.

[0004] In a first aspect, the present invention provides a hollow fiber mode field diameter testing device based on the far-field method, comprising: a control unit, a light source, an automatic coupling unit for hollow fiber, a hollow fiber end face position detection unit, a multi-functional displacement stage, a vertical rotation platform, a power detection unit, a hollow fiber end face image acquisition unit, and a signal analysis unit. The control unit is used to control the operation and timing of each device. The light source provides injection light for the testing of the hollow-core optical fiber under test; The hollow fiber automatic coupling unit is used to place one end of the hollow fiber to be tested and automatically couple the light emitted by the light source into the hollow fiber to be tested. The hollow fiber end face position detection unit controls the movement of the multi-functional displacement stage under the management of the control unit based on the end face position information of the hollow fiber under test, so that the end face of the hollow fiber under test is at the center of the axis of the vertical rotating platform. The multifunctional displacement stage is used to place the other end of the hollow fiber under test, and can realize the movement of the hollow fiber under test in the X, Y and Z directions and 360° rotation. The vertical rotating platform is a motion device for scanning the end face power of the hollow fiber to be tested; The power detection unit is used to acquire the power signal of the end face of the hollow fiber under test; The hollow fiber end face image acquisition unit is used to acquire images of the end face of the hollow fiber under test and observe them in real time. The signal analysis unit is used to analyze and process the acquired power signal to obtain the mode field diameter of the hollow fiber under test.

[0005] In some instances, both the hollow fiber automatic coupling unit and the multifunctional displacement stage are designed to resist ambient light interference.

[0006] In some instances, based on the end-face image acquired by the hollow fiber end-face image acquisition unit, the movement of the multi-functional displacement stage makes the end-face image of the hollow fiber under test clearer, and the rotation of the multi-functional displacement stage makes the power detection unit scan a suitable sector at the center of the hollow fiber under test.

[0007] In some instances, the positions of the two intersection points of the straight line passing through the center of the hollow fiber and the fiber core polygon are determined by the end-face image acquired by the hollow fiber end-face image acquisition unit. Then, the hollow fiber is rotated by a multi-functional displacement stage to control the position of the two intersection points of the straight line passing through the center of the hollow fiber and the fiber core polygon. The measured mode field diameter is different depending on the position of the intersection point, thereby testing the mode field diameter at different positions.

[0008] In some instances, the main control board of the control unit adopts a design combining MCU, FPGA and DSP, integrating electrical drive, image processing and signal processing functions, and is equipped with a Linux operating system, so that measurement can be completed without the participation of a computer.

[0009] In some instances, the device is suitable for measuring the mode field diameter of all hollow optical fibers with cladding diameters ranging from 100 μm to 1 mm, by using the hollow optical fiber automatic coupling unit and the multifunctional displacement stage to adjust hollow optical fibers of different sizes to the target axis position.

[0010] Secondly, the present invention provides a method for testing the mode field diameter of hollow optical fiber based on any of the above-described devices, comprising: One end of the hollow fiber to be tested is fixed on the multi-functional displacement stage with a fiber clamp, and the other end is placed on the hollow fiber automatic coupling unit. The power signal detected by the power detection unit is used as a basis to ensure that the coupling efficiency between the hollow fiber under test and the light source meets the measurement requirements. Start the measurement, adjust the position and angle of the hollow fiber under test by the multi-functional displacement stage, scan the end face power by the vertical rotation platform, and simultaneously acquire the end face image by the hollow fiber end face image acquisition unit. The power signal is processed by the signal analysis unit to obtain the measurement result of the mode field diameter and record and display it.

[0011] In some instances, the multifunctional displacement stage only adjusts and rotates the position of one end of the hollow fiber under test, while the automatic coupling unit of the hollow fiber at the other end remains fixed.

[0012] In some instances, the hollow fiber automatic coupling unit can respond to commands from the control unit to ensure that the light injection state meets the measurement accuracy requirements, and the operation process does not require manual intervention for coupling alignment.

[0013] In some instances, full light injection is achieved through an automatic coupling unit using hollow fiber.

[0014] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects: (1) Through the optical fiber end face image observation unit, and in conjunction with the multi-functional displacement stage, automatic, efficient and multi-dimensional hollow fiber mode field diameter testing can be achieved. (2) This device not only has high stability, but also can accurately measure the mode field diameter parameter of hollow fiber. At the same time, it is highly automated and easy to operate. Simply clamp the two ends of the hollow fiber to be tested with the hollow fiber clamp and place it in the corresponding position of the testing device. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the structure of the device provided in the embodiment of the present invention; Figure 2 This is a flowchart illustrating the testing method provided in an embodiment of the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] In the following description, specific embodiments of the invention will be illustrated with reference to steps and symbols performed by one or more computers, unless otherwise stated. Therefore, these steps and operations will be referred to several times as being performed by a computer, and computer execution as referred to herein includes operations by a computer processing unit representing electronic signals of data in a structured format. This operation transforms the data or maintains it at a location in the computer's memory system, which can be reconfigured or otherwise alter the operation of the computer in a manner well known to those skilled in the art. The data structure maintained by the data is the physical location of the memory, which has specific characteristics defined by the data format. However, the principles of the invention described above are not intended to be limiting, and those skilled in the art will understand that many of the following steps and operations can also be implemented in hardware.

[0019] The terms "module" or "unit" as used herein can be considered as software objects executing on the computing system. Different components, modules, engines, and services described herein can be considered as implementations on the computing system. The apparatus and methods described herein are preferably implemented in software, but can also be implemented in hardware, both of which are within the scope of this invention.

[0020] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when we say an element is “connected” or “coupled” to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements. Furthermore, “connected” or “coupled” as used herein can include wireless connections or wireless coupling. The term “and / or” as used herein includes all or any units and all combinations of one or more associated listed items.

[0021] This invention provides a device for measuring the mode field diameter of hollow optical fibers, capable of multi-dimensional measurement of the mode field diameter of the hollow optical fiber core. For example... Figure 1 As shown, 1 is the control unit, 2 is the light source, 3 is the hollow fiber automatic coupling unit, 4 is the hollow fiber end face position detection unit, 5 is the multi-functional displacement stage, 6 is the vertical rotation platform, 7 is the power detection unit, 8 is the hollow fiber end face image acquisition unit, 9 is the signal analysis unit, and 10 is the hollow fiber under test.

[0022] Among them, the control unit 1 is mainly responsible for the operation and timing of various devices in the whole device. The light source 2 is the light source injected into the hollow fiber under test. The hollow fiber automatic coupling unit 3 can automatically couple the light emitted by the light source 2 into the hollow fiber under test. The hollow fiber end face position detection unit 4, under the management of the control unit 1, controls the movement of the multi-functional displacement stage 5 according to the fiber end face position information, so that the end face of the hollow fiber under test is at the center of the vertical rotating platform. The multi-functional displacement stage 5 can move the tested end of the hollow fiber under test in three directions: X, Y and Z. The vertical rotating platform 6 is a motion device for scanning the power of the end face of the hollow fiber under test. The power detection unit 7 collects the power of the end face of the hollow fiber under test. The hollow fiber end face image acquisition unit 8 collects the image of the tested end face of the hollow fiber under test. The signal analysis unit 9 analyzes and processes the collected power signal to obtain the mode field diameter.

[0023] In another specific example, the hollow fiber end-face image acquisition unit 8 can observe the end-face image of the hollow fiber under test in real time, and then move or rotate the hollow fiber under test with the multi-functional displacement stage 5. Moving the hollow fiber under test is to make the image of the tested end face of the hollow fiber under test clearer, and rotating the hollow fiber under test is to make the power detection unit scan over a suitable sector in the center of the fiber.

[0024] In another specific example, the multi-functional displacement stage 5 used in this device can not only move the hollow fiber forward, backward, left, right, and up and down, but also rotate the hollow fiber clockwise or counterclockwise 360°.

[0025] In another specific example, the acquired end-face image and a multi-functional displacement stage can be used to measure the mode field diameter at any position on the end face of the hollow fiber under test. Specifically, the acquired end-face image is used to determine the positions of the two intersection points between the straight line passing through the center of the hollow fiber and the fiber core polygon. Then, the multi-functional displacement stage 5 is used to rotate the hollow fiber under test, thereby controlling the positions of the two intersection points. Different intersection points result in different measured mode field diameters. By rotating the hollow fiber under test to different positions, the mode field diameter at different locations can be measured.

[0026] In another specific example, the optical injection of the hollow fiber under test uses the hollow fiber automatic coupling unit 3. The optical injection state of the hollow fiber under test will seriously affect the measurement results. If the light is not fully injected, it will lead to an asymmetrical power curve, or the detected power will be too low to calculate the accurate mode field diameter of the hollow fiber. Moreover, this hollow fiber automatic coupling system is quick, convenient and stable to use.

[0027] In another specific example, this device employs an ambient light interference-proof design. To ensure the accuracy of measurement results and the stability of the device, both the automatic hollow fiber coupling unit 3 and the multi-functional displacement stage 5 are designed to resist ambient light interference. After the hollow fiber to be tested is placed, the automatic hollow fiber coupling unit 3 automatically closes its cover, ensuring that the coupling and measurement processes of the hollow fiber are conducted in a completely dark environment. After the hollow fiber to be tested is placed, the multi-functional displacement stage 5 is manually covered with a light-shielding plate, ensuring that the light detection part of the device is completely in a dark environment.

[0028] In another specific example, control unit 1 is designed using an MCU+FPGA+DSP architecture. Control unit 1 integrates electrical drive, image processing, signal processing, and a Linux-based operating system. This device can measure the mode field diameter of hollow optical fibers without the need for a computer, and is more portable and economical.

[0029] In another specific example, the mode field diameter can be measured for all hollow optical fibers currently on the market. Through the hollow optical fiber automatic coupling unit 3 and the multi-functional displacement stage 5, hollow optical fibers of different sizes can be adjusted to the ideal axis position. As long as the diameter of the hollow optical fiber cladding is in the range of 100um~1mm, it can be measured.

[0030] In another embodiment of the present invention, a method for measuring the mode field diameter of a hollow-core optical fiber is proposed. The specific test procedure for measuring the mode field diameter of a hollow-core optical fiber is as follows: Figure 2 As shown. The specific workflow of this method is as follows: Prepare the hollow fiber to be tested, ensuring that both ends of the fiber are clean and flat. Clamp one end of the hollow fiber to be tested with a hollow fiber clamp and place it on the multi-functional displacement stage 5 on the right side of the device. After the device indicates that the hollow fiber to be tested is properly placed, place the other end of the hollow fiber to be tested on the hollow fiber automatic coupling unit 3. Then, based on the power detected by the power detection unit 7, ensure that the coupling efficiency between the hollow fiber to be tested and the laser source 2 is high. At this point, the device will indicate that the measurement operation can be performed. Finally, press the start measurement button on the device to begin measuring the mode field diameter of the hollow fiber. After the measurement is completed, the device will record and display the measurement results.

[0031] The foregoing has provided a detailed description of a hollow fiber mode field diameter testing device and method based on the far-field method provided by the embodiments of the present invention. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A device for testing the mode field diameter of hollow optical fiber based on the far-field method, characterized in that, include: Control unit, light source, hollow fiber automatic coupling unit, hollow fiber end face position detection unit, multi-functional displacement stage, vertical rotation platform, power detection unit, hollow fiber end face image acquisition unit and signal analysis unit; The control unit is used to control the operation and timing of each device. The light source provides injection light for the testing of the hollow-core optical fiber under test; The hollow fiber automatic coupling unit is used to place one end of the hollow fiber to be tested and automatically couple the light emitted by the light source into the hollow fiber to be tested. The hollow fiber end face position detection unit controls the movement of the multi-functional displacement stage under the management of the control unit based on the end face position information of the hollow fiber under test, so that the end face of the hollow fiber under test is at the center of the axis of the vertical rotating platform. The multi-functional displacement stage is used to place the other end of the hollow fiber under test, and can realize the movement of the hollow fiber under test in the X, Y and Z directions and 360° rotation. The vertical rotating platform is a motion device for scanning the end face power of the hollow fiber to be tested; The power detection unit is used to acquire the power signal of the end face of the hollow fiber under test; The hollow fiber end face image acquisition unit is used to acquire images of the end face of the hollow fiber under test and observe them in real time. The signal analysis unit is used to analyze and process the acquired power signal to obtain the mode field diameter of the hollow fiber under test.

2. The apparatus according to claim 1, characterized in that, Both the hollow fiber automatic coupling unit and the multifunctional displacement stage are designed to resist ambient light interference.

3. The apparatus according to claim 2, characterized in that, Based on the end-face image acquired by the hollow fiber end-face image acquisition unit, the movement of the multi-functional displacement stage makes the end-face image of the hollow fiber under test clearer, and the rotation of the multi-functional displacement stage makes the power detection unit scan the appropriate sector of the center of the hollow fiber under test.

4. The apparatus according to claim 3, characterized in that, The end-face image acquired by the hollow fiber end-face image acquisition unit is used to determine the positions of the two intersection points of the straight line passing through the center position of the hollow fiber under test and the fiber core polygon. Then, the hollow fiber under test is rotated by a multi-functional displacement stage, thereby controlling the position of the two intersection points of the straight line passing through the center position of the hollow fiber under test and the fiber core polygon. The measured mode field diameter is different depending on the position of the intersection point, and thus the mode field diameter at different positions is tested.

5. The apparatus according to claim 4, characterized in that, The main control board of the control unit adopts a design combining MCU, FPGA and DSP, integrating electrical drive, image processing and signal processing functions, and is equipped with Linux operating system, so that measurement can be completed without the participation of computer.

6. The apparatus according to claim 5, characterized in that, The device is suitable for measuring the mode field diameter of all hollow optical fibers with cladding diameters in the range of 100um to 1mm. The device adjusts hollow optical fibers of different sizes to the target axis position through the hollow optical fiber automatic coupling unit and the multifunctional displacement stage.

7. A method for testing the mode field diameter of hollow optical fiber based on the apparatus described in any one of claims 1 to 6, characterized in that, include: One end of the hollow fiber to be tested is fixed on the multi-functional displacement stage with a fiber clamp, and the other end is placed on the hollow fiber automatic coupling unit. The power signal detected by the power detection unit is used as a basis to ensure that the coupling efficiency between the hollow fiber under test and the light source meets the measurement requirements. Start the measurement, adjust the position and angle of the hollow fiber under test by the multi-functional displacement stage, scan the end face power by the vertical rotation platform, and simultaneously acquire the end face image by the hollow fiber end face image acquisition unit. The power signal is processed by the signal analysis unit to obtain the measurement result of the mode field diameter and record and display it.

8. The method according to claim 7, characterized in that, The multi-functional displacement stage only adjusts and rotates the position of one end of the hollow fiber under test, while the automatic coupling unit of the hollow fiber at the other end of the hollow fiber under test remains fixed.

9. The method according to claim 8, characterized in that, The hollow fiber automatic coupling unit can respond to the instructions of the control unit to ensure that the light injection state meets the measurement accuracy requirements, and the operation process does not require manual intervention for coupling alignment.

10. The method according to claim 9, characterized in that, Full light injection is achieved through an automatic coupling unit using hollow optical fibers.

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