A multi-core optical fiber end face multi-parameter sensor and preparation method thereof

Abstract

The present invention belongs to the field of optical fiber sensing technology, specifically a multi-core optical fiber end face multi-parameter sensor and a preparation method thereof. The present invention includes: a multi-core optical fiber with multiple cores; a multi-terminal micro-cantilever located at the end face of the multi-core optical fiber, which is printed on the end face of the multi-core optical fiber by femtosecond laser two-photon polymerization technology; functional materials located on the upper surface of multiple terminals of the micro-cantilever, which are modified on the upper surface of the micro-cantilever by magnetron sputtering coating technology and micro-manipulator coating process. The multi-core optical fiber end face multi-parameter sensor and the preparation method thereof proposed by the present invention can select functional materials that are sensitive to different physical quantities, so that each micro-cantilever terminal has a single selective response to different physical quantities, and realizes the simultaneous measurement of multiple physical quantities. It has the characteristics of small size, flexible design, and high sensitivity, and effectively solves the problem of multi-parameter measurement in complex environments.

Description

Technical Field

[0001] The present invention belongs to the technical field of fiber optic sensing, and particularly relates to a multi-core fiber end face multi-parameter sensor and a preparation method thereof. Background Art

[0002] Fiber optic sensors have many advantages such as high sensitivity, small size, strong flexibility, and remote monitoring, and have become an efficient and low-cost solution in many industries. In addition, fiber optic sensors can still be used under harsh environmental conditions such as strong electromagnetic fields, high voltages, nuclear radiation, explosive or chemically corrosive media, and high temperatures. However, the existing research on fiber optic sensing mainly focuses on single-core fiber sensing technology. A single-core fiber usually can only demodulate a certain parameter such as strain, temperature, bending, displacement, etc. separately. When using existing fiber optic sensors for multi-parameter perception, acquisition, and demodulation, it is often necessary to deploy multiple single-core fiber sensors and their respective independent acquisition systems separately, resulting in a complex structure and a significant increase in cost.

[0003] With the improvement of fiber preparation level and technological development, in order to increase the space utilization rate of a single fiber and improve the communication capacity, the research and application of multi-core fibers have developed rapidly. A multi-core fiber can integrate several independent cores into one fiber. Each core is an independent path, with low crosstalk between cores and consistent signal attenuation, having extremely high application potential in the field of space division multiplexing communication transmission and also having significant advantages in sensing applications such as spatial structure, transmission integration, and temperature synchronous compensation. However, currently, multi-parameter sensors based on multi-core fibers are usually realized by refractive index modulation of the cores in the fiber axial direction, with relatively limited achievable micro-nano structures and functional materials that can be modified, and the measurable parameters mainly focus on physical quantities such as temperature, torsion, and bending.

[0004] By integrating functional materials and micro-nano structures onto the end face of an optical fiber, various multifunctional photonic devices can be formed. The flat end face of an optical fiber is a unique unconventional platform with a micron-sized cross-sectional area and a large aspect ratio, enabling rich and complex micro-nano structures. It has been widely studied in the fields of remote optical sensing, imaging, shaping, etc. In the current research on micro-nano structures on the end face of optical fibers, single-core optical fibers with only one coupling channel are mostly used. However, in the process of designing the end face structure of an optical fiber, the way of coupling light out of the fiber and collecting it back into the fiber must be considered, which is very difficult for the end face of a single-core optical fiber. Therefore, there are great limitations in the design of micro-nano structures. On the end face of a multi-core optical fiber, each core can serve as a port for coupling light into or out of the optical fiber, which greatly expands the design space for functional optical configurations on the end face of the optical fiber. By using precise three-dimensional processing technology, tiny micro-nano structures can be fabricated on the end face of a multi-core optical fiber. Utilizing the advantage of spatial division multiplexing of multiple cores, simultaneous measurement of multiple parameters can be achieved, and the method of functional modification of the end face is simpler and more flexible than that of the side of the optical fiber. Summary of the Invention

[0005] The object of the present invention is to provide a multi-parameter sensor for the end face of a multi-core optical fiber with small size, flexible design and high sensitivity, and a preparation method thereof.

[0006] The multi-parameter sensor for the end face of a multi-core optical fiber proposed by the present invention includes:

[0007] A multi-core optical fiber, that is, multiple parallel cores are contained in the cladding of a single optical fiber;

[0008] A microcantilever beam, including a support block and multiple microcantilever beam terminals;

[0009] The microcantilever beam is located on the end face of the multi-core optical fiber, and the support block connects the end face of the optical fiber and multiple microcantilever beam terminals; the microcantilever beam on the end face of the multi-core optical fiber is obtained by one-time printing on the end face of the multi-core optical fiber through femtosecond laser two-photon polymerization technology; the multiple microcantilever beam terminals block each core, forming multiple Fabry-Perot interferometer sensing core components;

[0010] Functional materials sensitive to different physical quantities are modified on each microcantilever beam terminal, so that each microcantilever beam terminal has a single-selective response to different parameters. Utilizing the advantage of multiple channels of the multi-core optical fiber, simultaneous measurement of multiple parameters is achieved; the physical quantities here include the temperature, humidity, etc. of the environment, as well as the composition of gases, etc.

[0011] Furthermore:

[0012] The support block is located at the geometric center of the microcantilever beam structure and at the position of the middle core of the multi-core optical fiber to connect the microcantilever beam and the end face of the optical fiber;

[0013] The number of cores of the multi-core optical fiber is N, where N≥2;

[0014] The number of terminals of the microcantilever beam is M, where M≥2;

[0015] The support block is not limited to a cylindrical shape and has a length of 5 - 150 μm;

[0016] The width, length, and position of each terminal of the microcantilever beam are adjusted according to the core diameter and core pitch of the multi-core optical fiber used, so that the formed Fabry - Perot interferometer has a high-quality spectrum;

[0017] The thickness of the terminal of the microcantilever beam is 2 - 10 μm.

[0018] The present invention also provides a preparation method for the multi-parameter sensor at the end face of the above multi-core optical fiber. The specific steps are as follows:

[0019] (1) Design a matching microcantilever beam structure according to the core diameter and core pitch of the multi-core optical fiber;

[0020] (2) Use an optical fiber fixture to assemble the multi-core optical fiber onto a 3D lithography machine platform, adjust the focusing platform, focus femtosecond laser through a high numerical aperture objective lens, and cooperate with a precision displacement platform to print the microcantilever beam designed in step (1);

[0021] (3) Place the microcantilever beam printed in step (2) in a developing solution to remove the uncured photoresist, and irradiate the developed microcantilever beam with ultraviolet light to further strengthen the curing;

[0022] (4) Use magnetron sputtering technology or micro-manipulator coating process to modify the upper surface of the terminal of the microcantilever beam strengthened in step (3) with a functional material.

[0023] The multi-parameter sensor at the end face of the multi-core optical fiber and its preparation method proposed by the present invention realize the single-fiber end-face integration of multiple parallel Fabry - Perot interferometers by using femtosecond laser two-photon polymerization technology to print microcantilever beams at the end face of the multi-core optical fiber at one time. By selecting functional materials sensitive to different parameters to modify the terminals of each microcantilever beam, each terminal of the microcantilever beam has a single-selective response to different parameters. Utilizing the advantages of multi-channels of the multi-core optical fiber, simultaneous measurement of multiple parameters is realized, which has the characteristics of small size, flexible design, and high sensitivity, and effectively solves the problem of measuring multiple parameters in a complex environment. Description of the Drawings

[0024] Figure 1 It is a schematic structural diagram of Embodiment 1 of the present invention.

[0025] Figure 2 It is a schematic diagram of the end face of the multi-core optical fiber and the microcantilever beam structure in Embodiment 1 of the present invention.

[0026] Figure 3 This is a schematic structural diagram of Embodiment 2 of the present invention.

[0027] Figure 4 This is a flowchart of the preparation method of the multi-core fiber end multi-parameter sensor in the present invention.

[0028] Reference numerals in the figure: 1 is a multi-core fiber, 2 is a microcantilever beam, 21 is a support block, 22 is the end of the microcantilever beam, and 23 is a functional material modified on the upper surface of the end of the microcantilever beam. Specific embodiments

[0029] In order to more clearly illustrate the purpose and advantages of the present invention, the present invention will be further elaborated in detail below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention. Embodiment

[0030] The structure of the multi-core fiber end multi-parameter sensor in this embodiment is shown in Figure 1 as follows and includes:

[0031] A multi-core fiber 1 and a microcantilever beam 2, and the microcantilever beam 2 includes a support block 21, an end 22 of the microcantilever beam, and a functional material 23 modified on the upper surface of the end of the microcantilever beam.

[0032] As Figure 2 shown, the number of cores of the multi-core fiber is 7, the outer cores are distributed in a hexagonal shape, and the middle core is located at the center of the hexagon. The number of ends of the microcantilever beam is 6, and the support block is located at the geometric center of the microcantilever beam structure and at the position of the middle core of the multi-core fiber to connect the microcantilever beam and the fiber end face.

[0033] The length of the end of the microcantilever beam is adjusted according to the core pitch D, and the width is adjusted according to the core diameter R, so that the formed Fabry-Perot interferometer has a high-quality spectrum.

[0034] The thickness of the end of the microcantilever beam should be as thin as possible without causing deformation of the end of the microcantilever beam, so as to make it have higher sensitivity. Embodiment

[0035] As Figure 3 shown, this is a schematic structural diagram of the multi-core fiber end multi-parameter sensor in another embodiment. The multi-core fiber end multi-parameter sensor proposed in this embodiment includes:

[0036] A multi-core fiber 1 and a microcantilever beam 2, and the microcantilever beam 2 includes a support block 21, an end 22 of the microcantilever beam, and a functional material 23 modified on the upper surface of the end of the microcantilever beam.

[0037] The multi-core optical fiber has 3 cores, and the cores are arranged in a linear pattern. The middle core is located at the center of the optical fiber. The number of terminals of the microcantilever beam is 2. The support block is located at the geometric center of the microcantilever beam structure and at the position of the middle core of the multi-core optical fiber to connect the microcantilever beam and the optical fiber end face.

[0038] The length of the terminal of the microcantilever beam is adjusted according to the core pitch D, and the width is adjusted according to the core diameter R, so that the formed Fabry-Perot interferometer has a high-quality spectrum.

[0039] The thickness of the terminal of the microcantilever beam should be as thin as possible without causing deformation of the terminal of the microcantilever beam, so as to make it have higher sensitivity. Embodiment

[0040] This embodiment provides a preparation method for a multi-parameter sensor at the end face of a multi-core optical fiber, as Figure 4 shown, the specific steps include:

[0041] (1) Design a matching microcantilever beam structure according to the core diameter and core pitch of the multi-core optical fiber;

[0042] In this step, by measuring the core distribution, core diameter and core pitch of the multi-core optical fiber, determine the appropriate position, length and width of the terminal of the microcantilever beam, and use software to perform solid modeling on the designed three-dimensional microcantilever beam structure;

[0043] (2) Use an optical fiber fixture to assemble the multi-core optical fiber to the 3D lithography machine platform, adjust the focusing platform, focus the femtosecond laser through a high numerical aperture objective lens, and cooperate with the precision displacement platform to print the microcantilever beam designed in step (1);

[0044] In this step, use an optical fiber fixture to vertically assemble the multi-core optical fiber to the 3D lithography machine platform. The cover glass is located above the end face of the optical fiber, and the distance is adjusted to several hundred micrometers. Fill the photoresist in this gap to immerse the entire end face of the optical fiber; Drop the refractive index matching oil on the upper surface of the cover glass and immerse the high numerical aperture oil lens; Adjust the focusing plane to the end face of the optical fiber through the observation CCD, and program to control the precision displacement platform and the femtosecond laser switch, and optimize processing parameters such as the scanning path, laser energy, line spacing, and layer spacing to realize the printing of the microcantilever beam structure;

[0045] (3) Place the microcantilever beam printed in step (2) in the developer to remove the uncured photoresist, and irradiate the developed microcantilever beam with ultraviolet light to further strengthen the curing;

[0046] In this step, the aggregated sample is taken out from the optical fiber fixture, placed in the developer for development, and by controlling the solution composition and development time of the developer, the effect of fully removing the uncured photoresist is achieved without damaging the structure; the developed microcantilever is irradiated with ultraviolet light to achieve the effect of further strengthening the curing;

[0047] (4) Modify the upper surface of the terminal of the microcantilever strengthened in step (3) with functional materials by using magnetron sputtering technology and micro-manipulator coating process;

[0048] In this step, the strengthened sample is placed in an optical fiber magnetron sputtering coater, and selective plating of some functional metal materials is carried out on the upper surface of the terminal of the microcantilever, and other functional materials are selectively coated by using the tip probe of the micro-manipulator.

[0049] Finally, the above specific implementation can be locally adjusted by those skilled in the art in different ways without departing from the principles and purposes of the present invention, and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A multi-core optical fiber end face multi-parameter sensor, characterized in that: include: A multi-core optical fiber and a micro-cantilever beam located at the end surface of the multi-core optical fiber; the micro-cantilever beam comprises a support block and a plurality of micro-cantilever beam terminals; The support block connects the optical fiber end face and a plurality of micro-cantilever beam terminals; the multi-core optical fiber end face micro-cantilever beam is obtained by one-time printing on the multi-core optical fiber end face through femtosecond laser two-photon polymerization technology; the plurality of micro-cantilever beam terminals shield each optical fiber core to form a plurality of Fabry-Perot interferometer sensing core components; Each micro-cantilever terminal is modified with functional materials that are sensitive to different physical factors, so that each micro-cantilever terminal has a single selective response to different parameters, and utilizes the advantages of multi-core optical fiber and multi-channel to achieve simultaneous measurement of multiple parameters.

2. The multi-core optical fiber end face multi-parameter sensor according to claim 1, characterized in that: The support block is located at the geometric center of the micro-cantilever structure and at the position of the middle core of the multi-core optical fiber to connect the micro-cantilever and the end face of the optical fiber.

3. The multi-core optical fiber end face multi-parameter sensor according to claim 2, characterized in that: The number of cores of the multi-core optical fiber is N, where N≥2; The number of terminals of the micro cantilever beam is M, M≥2; The support block is cylindrical or square, and has a length of 5 to 150 μm.

4. The multi-core optical fiber end face multi-parameter sensor according to claim 3, characterized in that: The width, length and position of each terminal of the micro-cantilever beam are adjusted according to the core diameter and core spacing of the multi-core optical fiber used, so that the formed Fabry-Perot interferometer has a high-quality spectrum.

5. The multi-core optical fiber end face multi-parameter sensor according to claim 3, characterized in that: The thickness of the micro cantilever beam terminal is 2-10 μm.

6. The method for preparing a multi-core optical fiber end face multi-parameter sensor according to any one of claims 1 to 5, characterized in that: The specific steps are: (1) designing a matching micro-cantilever beam structure according to the core diameter and core spacing of the multi-core optical fiber; (2) Use a fiber optic fixture to assemble the multi-core optical fiber onto the 3D lithography machine platform, adjust the focusing platform, focus the femtosecond laser through a high numerical aperture objective lens, and use a precision displacement platform to print the micro cantilever designed in step (1); (3) placing the micro cantilever beam printed in step (2) in a developer to remove the uncured photoresist, and irradiating the developed micro cantilever beam with ultraviolet light to further enhance the curing; (4) Using magnetron sputtering technology or micromanipulator coating process to modify the functional material on the upper surface of the micro cantilever beam terminal reinforced in step (3).

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