A high-sensitivity optical fiber sensing device and a high-sensitivity optical fiber sensing device manufacturing method

Abstract

The present application relates to a kind of high sensitivity fiber sensing device and high sensitivity fiber sensing device manufacturing method, by setting end face reflection layer in the end face of optical fiber, optical fiber is inserted into insertion sleeve, and the flexible film reflection layer of the other end of insertion sleeve forms the optical concave mirror of convex, the reflectivity of light is improved using the light convergence effect of concave mirror, the efficiency of the light coupling back to optical fiber of the light emitted from optical fiber is improved, and then the fineness and Q value of interference spectrum are improved, higher spectral sensitivity is achieved.Meanwhile, the change rate of sensing device with the change of external physical quantity is improved using the softness of flexible film reflection layer, so that the present device considers spectral sensitivity and mechanical sensitivity, and further improves sensing performance.

Description

Technical Field

[0001] This invention relates to the field of fiber optic sensor technology, and in particular to a high-sensitivity fiber optic sensing device and a method for manufacturing the high-sensitivity fiber optic sensing device. Background Technology

[0002] Fiber optic sensors are widely used in precision measurement across industries. One type is the fiber optic sensor based on the Fabry-Perot interferometer, which can sense and measure multiple physical parameters, including but not limited to strain, temperature, pressure, and sound waves. It is highly favored due to its excellent performance.

[0003] Traditional diaphragm-based fiber Fabry-Perot sensors, such as flat diaphragm structures and protrusion structures, suffer from a limited sensitivity in their reflectivity as the optical fiber emits light. This is because the light emitted from the optical fiber has a certain divergence angle, and these flat diaphragm structures cannot effectively couple the reflected light back into the optical fiber. Consequently, the number of interferences in the fiber Fabry-Perot interferometer is low, resulting in low spectral precision. This limits the sensitivity of the sensor to changes in reflectivity with the resonant cavity.

[0004] Therefore, it is necessary to provide a high-sensitivity fiber optic sensing device and a method for manufacturing the high-sensitivity fiber optic sensing device, so as to further improve the sensitivity of fiber optic sensors. Summary of the Invention

[0005] In view of this, it is necessary to provide a high-sensitivity fiber optic sensing device and a method for manufacturing the high-sensitivity fiber optic sensing device, so as to improve the sensitivity of existing fiber optic sensors.

[0006] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a highly sensitive fiber optic sensing device, comprising:

[0008] Socket;

[0009] An optical fiber, one end of which is inserted into one end of the insert;

[0010] An end-face reflective layer is disposed on the end face of one end of the optical fiber;

[0011] A flexible thin-film reflective layer is disposed at the other end of the insert and protrudes from the insert in a direction away from the optical fiber. The flexible thin-film reflective layer, the insert, and one end of the optical fiber form a sealed cavity.

[0012] Furthermore, the sealed cavity is filled with a gaseous medium.

[0013] Furthermore, the end-face reflective layer covers at least one end of the optical fiber core region.

[0014] Furthermore, the materials of the end-face reflective layer and the flexible thin-film reflective layer include at least one of metal, semiconductor, dielectric material and polymer.

[0015] In a second aspect, the present invention also provides a method for manufacturing a high-sensitivity fiber optic sensing device, for manufacturing the high-sensitivity fiber optic sensing device as described in any of the preceding claims, the method comprising:

[0016] An end-face reflective layer is provided on the end face of one end of the optical fiber;

[0017] The flexible thin-film reflective layer is disposed at the other end of the insert.

[0018] Insert the optical fiber into one end of the insert, seal the connection between the optical fiber and the end face of the insert, and continue to advance the optical fiber so that the flexible thin film reflective layer protrudes from the insert in the direction away from the optical fiber;

[0019] Secure the optical fiber and the insert.

[0020] Furthermore, the step of inserting the optical fiber from one end of the insert, sealing the connection between the optical fiber and the end face of the insert, and continuing to advance the optical fiber so that the flexible thin-film reflective layer protrudes from the insert in a direction away from the optical fiber, includes:

[0021] Insert the optical fiber into one end of the ferrule, and the distance between one end of the optical fiber and the other end of the ferrule is the initial cavity length;

[0022] Seal one end of the optical fiber and the ferrule;

[0023] The optical fiber is advanced to the other end of the insert until the distance between one end of the optical fiber and the other end of the insert is the target cavity length, and the flexible thin film reflective layer protrudes from the insert in the direction away from the optical fiber.

[0024] Furthermore, the step of inserting the optical fiber from one end of the insert, sealing the connection between the optical fiber and the end face of the insert, and continuing to advance the optical fiber so that the flexible thin-film reflective layer protrudes from the insert in a direction away from the optical fiber, further includes:

[0025] Obtain the target cavity length, and obtain the initial cavity length based on the target cavity length.

[0026] Furthermore, obtaining the target cavity length and obtaining the initial cavity length based on the target cavity length includes:

[0027] The target cavity length is obtained, and the simulation coupling coefficient of the high-sensitivity fiber optic sensing device under different simulated propulsion amounts is obtained based on the target cavity length.

[0028] The optimal propulsion amount is obtained based on the simulated coupling coefficient;

[0029] The initial cavity length is obtained based on the optimal propulsion amount and the target cavity length.

[0030] Furthermore, sealing one end of the optical fiber and the ferrule includes:

[0031] UV-curable adhesive is applied between the periphery of the optical fiber and one end of the insert.

[0032] Furthermore, fixing the optical fiber and the insert includes:

[0033] The UV-curable adhesive is then cured.

[0034] This invention provides a high-sensitivity fiber optic sensing device and its manufacturing method. By setting an end-face reflective layer on the end face of the optical fiber, inserting the fiber into a ferrule, and forming a convex concave optical mirror with a flexible thin-film reflective layer at the other end of the ferrule, the light-convexity of the concave mirror is improved through its light-convexity focusing effect. This enhances the efficiency of coupling the emitted light back into the fiber, thereby improving the precision and Q-value of the interference spectrum and achieving higher spectral sensitivity. Simultaneously, the flexibility of the thin-film reflective layer increases the rate of change of the sensing device with respect to changes in external physical quantities, enabling the device to balance spectral and mechanical sensitivity, further improving its sensing performance. Attached Figure Description

[0035] Figure 1 A schematic diagram of the structure of an embodiment of the high-sensitivity fiber optic sensing device provided by the present invention;

[0036] Figure 2 A flowchart illustrating an embodiment of the manufacturing method for a high-sensitivity fiber optic sensing device provided by the present invention;

[0037] Figure 3 for Figure 2 The flowchart of step S203 in the text;

[0038] Figure 4 for Figure 3 The flowchart of step S304 in the text;

[0039] Figure 5 A theoretical simulation diagram showing the relationship between propulsion amount and coupling coefficient in one embodiment of the manufacturing method of the high-sensitivity fiber optic sensing device provided by the present invention;

[0040] Figure 6 A comparison of the reflectance spectrum experimental results of the high-sensitivity fiber optic sensing device provided by this invention and a conventional flat film structure sensor. Detailed Implementation

[0041] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0042] In the description of this application, "multiple" means two or more, unless otherwise expressly and specifically defined.

[0043] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0044] This invention provides a high-sensitivity fiber optic sensing device and a corresponding manufacturing method for the high-sensitivity fiber optic sensing device. By making the flexible thin-film reflective layer convex, the coupling rate of light after reflection and coupling back to the optical fiber is improved. In addition, the flexible thin-film reflective layer itself has flexible properties, thus achieving a combined improvement in the spectral sensitivity and mechanical sensitivity of the sensing device.

[0045] This invention provides a high-sensitivity fiber optic sensing device and a method for manufacturing the high-sensitivity fiber optic sensing device, which will be described below.

[0046] Combination Figure 1 As shown in the figure, a specific embodiment of the present invention discloses a highly sensitive fiber optic sensing device, which includes a insert 1, an optical fiber 2, an end-face reflective layer 3, and a flexible thin-film reflective layer 4. One end of the optical fiber 2 is inserted into one end of the insert 1, the end-face reflective layer 3 is disposed on the end face of one end of the optical fiber 2, located inside the insert 1, and the flexible thin-film reflective layer 4 is disposed at the other end of the insert 1 and protrudes from the insert 1 in a direction away from the optical fiber 2. The flexible thin-film reflective layer 4, the insert 1, and one end of the optical fiber 2 form a sealed cavity.

[0047] In this embodiment, the insert 1, the end-face reflective layer 3, and the flexible thin-film reflective layer 4 constitute an optical Fabry-Perot cavity. Light emitted from the optical fiber 2 is reflected by the flexible thin-film reflective layer 4 and the end-face reflective layer 3, and then coupled back into the optical fiber 2. When an external force is applied to the flexible thin-film reflective layer 4, the flexible thin-film reflective layer 4 deforms, causing a corresponding change in the light coupled back into the optical fiber 2, thus achieving sensing. Compared with the prior art, this invention utilizes the light-converging effect of a concave mirror to improve the reflectivity of light, thereby improving the efficiency of coupling the light emitted from the optical fiber 2 back into the optical fiber 2, and thus improving the fineness and Q value of the interference spectrum, achieving higher spectral sensitivity.

[0048] It should be noted that, in this embodiment, the quality factor of the Fabry-Perot cavity, i.e., the quality of the sensing device, can be evaluated by the Q value. This value can be obtained by the ratio of the center wavelength of the trough in the reflection spectrum to the half-width at half-maximum (FWHM) at the trough. The formula for calculating the Q value is:

[0049]

[0050] In the formula, λ0 is the center wavelength of the valley in the reflection spectrum, and Δλ is the half-width at half-maximum (WHM) at the valley.

[0051] Furthermore, the present invention utilizes the flexibility of the flexible thin film reflective layer 4 to improve the rate of change of the sensing device with changes in external physical quantities, enabling the device to balance spectral sensitivity and mechanical sensitivity, thereby further enhancing the sensing performance.

[0052] In a preferred embodiment, the insert 1 in this embodiment is a ceramic insert 1, also known as a ceramic ferrule. Furthermore, it is readily understood that the optical fiber 2 in this embodiment is a general term for a cable including a core and a cladding. The core extends along the axis of the cladding to conduct light, and the outer peripheral surface of the cladding is used to connect to the inner wall of the insert 1. The optical fiber 2 can be connected to an interferometer, allowing this high-sensitivity optical fiber sensing device to be used as the probe part of the interferometer, or it can be directly connected to other structures to make this high-sensitivity optical fiber sensing device an independent sensor.

[0053] In a preferred embodiment, the end-face reflective layer 3 in this embodiment covers at least the core region of one end of the optical fiber 2. The end-face reflective layer 3 has optical reflective capability, and its material composition includes, but is not limited to, metals, semiconductors, dielectric materials, polymers, etc., and can be a composite material composed of one or more of the above materials.

[0054] Furthermore, as a preferred embodiment, the flexible thin film reflective layer 4 in this embodiment is similar to the end face reflective layer 3, and it has optical reflective capability. When implemented, its material composition includes, but is not limited to, metals, semiconductors, dielectric materials, polymers, etc., and can be a composite material composed of one or more of the above materials. However, it is worth noting that the flexible thin film reflective layer 4 needs to be able to deform with external force in order to realize sensing.

[0055] As a preferred embodiment, in the high-sensitivity fiber optic sensing device of this embodiment, the insert 1, the end face reflective layer 3, and the flexible thin film reflective layer 4 together form a Fabry-Perot cavity, abbreviated as FP cavity. In this embodiment, the Fabry-Perot cavity is filled with gas as the cavity medium, the main component of which is air, which minimizes the limitation of the rate of change of the cavity medium with the change of external physical parameters and improves the sensitivity.

[0056] The present invention also provides a method for manufacturing a high-sensitivity fiber optic sensing device, specifically, in conjunction with... Figure 2 As shown, in a preferred embodiment, the manufacturing method includes:

[0057] S201. An end-face reflective layer is provided on the end face of one end of the optical fiber;

[0058] S202, The flexible thin film reflective layer is provided at the other end of the insert;

[0059] S203. Insert the optical fiber from one end of the insert, seal the connection between the optical fiber and the end face of the insert, and continue to push the optical fiber in so that the flexible thin film reflective layer protrudes from the insert in the direction away from the optical fiber.

[0060] S204. Fix the optical fiber and the insert.

[0061] The above method adjusts the air pressure inside the Fabry-Perot cavity by varying the depth of fiber insertion, thereby enabling the flexible thin-film reflective layer to achieve the desired degree of convexity.

[0062] Specifically, in combination Figure 3 As shown, in a preferred embodiment, step S203 of this embodiment, inserting the optical fiber from one end of the insert, sealing the connection between the optical fiber and the end face of the insert, and continuing to advance the optical fiber so that the flexible thin-film reflective layer protrudes from the insert in the direction away from the optical fiber, specifically includes:

[0063] S301. Insert the optical fiber into one end of the insert, until the distance between one end of the optical fiber and the other end of the insert is the initial cavity length;

[0064] S302. Seal one end of the optical fiber and the ferrule;

[0065] S303. Push the optical fiber to the other end of the insert until the distance between one end of the optical fiber and the other end of the insert is the target cavity length, and make the flexible thin film reflective layer protrude from the insert in the direction away from the optical fiber.

[0066] In this embodiment, after inserting the optical fiber, the optical fiber and the ferrule are sealed while ensuring that the optical fiber and the ferrule can move relative to each other. By adjusting the insertion depth of the optical fiber, the pressure of the Fabry-Perot cavity can be changed, thereby adjusting the degree of convexity of the flexible thin film reflective layer.

[0067] Specifically, as a preferred embodiment, step S302, sealing one end of the optical fiber and the insert, specifically includes:

[0068] UV-curable adhesive is applied between the periphery of the optical fiber and one end of the insert.

[0069] UV-curable adhesive can act as a sealant, but it does not restrict the relative movement of the optical fiber and the ferrule before it is cured by UV light.

[0070] Understandably, after sealing, the different depths the optical fiber penetrates will affect the unevenness of the flexible thin-film reflective layer, thus affecting the coupling degree between light reflection and the optical fiber. Therefore, in order to achieve optimal accuracy in this high-sensitivity optical fiber sensing device, it is necessary to control the distance the optical fiber travels inside the ferrule after sealing, i.e., control the amount of optical fiber advancement.

[0071] Therefore, please refer to [the relevant document / reference]. Figure 3 The present invention also provides a preferred embodiment in which the manufacturing method of the high-sensitivity fiber optic sensing device further includes step S203:

[0072] S304. Obtain the target cavity length and obtain the initial cavity length based on the target cavity length.

[0073] The initial cavity length refers to the distance between the end face of the optical fiber and the other end of the insert at the position where the optical fiber is located after being inserted into the insert and sealed, before it continues to advance. The target cavity length is the final distance between the end face of the optical fiber and the other end of the insert after the optical fiber has advanced to the required depth from the position corresponding to the initial cavity length, i.e., after the high-sensitivity optical fiber sensing device is manufactured.

[0074] The above relationship can be expressed by the following formula:

[0075] Ll=L2+ΔL

[0076] In the formula, L1 is the initial cavity length, L2 is the target cavity length, and ΔL is the propulsion amount. In this embodiment, by controlling the initial cavity length, the propulsion amount is controlled, thereby controlling the unevenness of the flexible thin-film reflective layer.

[0077] The above steps can be performed before step S301, specifically, in conjunction with Figure 4 As shown, in a preferred embodiment, step S304, obtaining the target cavity length and obtaining the initial cavity length based on the target cavity length, specifically includes:

[0078] S401. Obtain the target cavity length, and obtain the simulation coupling coefficient of the high-sensitivity fiber optic sensing device under different simulated propulsion amounts based on the target cavity length.

[0079] S402. Based on the simulated coupling coefficient, the optimal propulsion amount is obtained;

[0080] S403. The initial cavity length is obtained based on the optimal propulsion amount and the target cavity length.

[0081] Step S401 in the above process can be simulated by simulation software. The simulation result obtained in this embodiment is as follows: Figure 5 As shown, Figure 5 The vertical axis represents the coupling coefficient, which is the proportion of light intensity that can be coupled back into the original fiber for transmission after being reflected from the end face of the optical fiber. The larger the value, the better. Figure 5 L2 in the figure represents the target cavity length. Figure 5 The x-coordinate of a point on the curve represents the coupling coefficient achievable by the high-sensitivity fiber optic sensing device after reaching the target cavity length with a specific propulsion amount. The figure simulates the coupling coefficients achievable for multiple target cavity lengths under different propulsion amounts ΔL. How to perform simulations to obtain the above data is a technique that can be directly implemented by those skilled in the art, and will not be discussed in detail here.

[0082] In step S402, based on the above simulation results, i.e. Figure 5 Knowing the optimal propulsion amount to achieve the target cavity length and thus the best coupling coefficient, the propulsion amount corresponding to this coupling coefficient is taken as the optimal propulsion amount. Step S403 then yields the required initial cavity length. The initial cavity length obtained through this process optimizes the performance of the final high-sensitivity fiber optic sensing device.

[0083] Furthermore, as a preferred embodiment, step S204 of this embodiment, fixing the optical fiber and the insert, specifically includes:

[0084] The UV-curable adhesive is then cured.

[0085] Combination Figure 6 As shown in the figure, the experimental results of the reflection spectrum of this high-sensitivity fiber optic sensing device and the ordinary flat film structure sensor are compared. It can be seen from the figure that the Q value achieved by this high-sensitivity fiber optic sensing device is much better than that of the traditional flat film structure, and it has excellent performance.

[0086] This invention provides a high-sensitivity fiber optic sensing device and its manufacturing method. By setting an end-face reflective layer on the end face of the optical fiber, inserting the fiber into a ferrule, and forming a convex concave optical mirror with a flexible thin-film reflective layer at the other end of the ferrule, the light-convexity of the concave mirror is improved through its light-convexity focusing effect. This enhances the efficiency of coupling the emitted light back into the fiber, thereby improving the precision and Q-value of the interference spectrum and achieving higher spectral sensitivity. Simultaneously, the flexibility of the thin-film reflective layer increases the rate of change of the sensing device with respect to changes in external physical quantities, enabling the device to balance spectral and mechanical sensitivity, further improving its sensing performance.

[0087] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A highly sensitive fiber optic sensing device, characterized in that, include: Socket; An optical fiber, one end of which is inserted into one end of the insert; An end-face reflective layer is disposed on the end face of one end of the optical fiber; A flexible thin-film reflective layer is disposed at the other end of the insert. During the insertion of the optical fiber into the insert, the flexible thin-film reflective layer protrudes from the insert in a direction away from the optical fiber. The flexible thin-film reflective layer, the insert, and one end of the optical fiber form a sealed cavity.

2. The high-sensitivity fiber optic sensing device according to claim 1, characterized in that, The sealed cavity is filled with a gaseous medium.

3. The high-sensitivity fiber optic sensing device according to claim 1, characterized in that, The end-face reflective layer covers at least one end of the optical fiber core region.

4. The high-sensitivity fiber optic sensing device according to claim 1, characterized in that, The materials of the end-face reflective layer and the flexible thin-film reflective layer include at least one of metal, semiconductor, dielectric material and polymer.

5. A method for manufacturing a high-sensitivity fiber optic sensing device, used to manufacture the high-sensitivity fiber optic sensing device as described in any one of claims 1 to 4, characterized in that, The method includes: An end-face reflective layer is provided on the end face of one end of the optical fiber; The flexible thin-film reflective layer is disposed at the other end of the insert. Insert the optical fiber into one end of the insert, seal the connection between the optical fiber and the end face of the insert, and continue to advance the optical fiber so that the flexible thin film reflective layer protrudes from the insert in the direction away from the optical fiber; Secure the optical fiber and the insert.

6. The method for manufacturing a high-sensitivity fiber optic sensing device according to claim 5, characterized in that, The process of inserting the optical fiber from one end of the insert, sealing the connection between the optical fiber and the end face of the insert, and continuing to advance the optical fiber so that the flexible thin-film reflective layer protrudes from the insert in a direction away from the optical fiber includes: Insert the optical fiber into one end of the ferrule, and the distance between one end of the optical fiber and the other end of the ferrule is the initial cavity length; Seal one end of the optical fiber and the ferrule; The optical fiber is advanced to the other end of the insert until the distance between one end of the optical fiber and the other end of the insert is the target cavity length, and the flexible thin film reflective layer protrudes from the insert in the direction away from the optical fiber.

7. The method for manufacturing a high-sensitivity fiber optic sensing device according to claim 6, characterized in that, The process of inserting the optical fiber from one end of the insert, sealing the connection between the optical fiber and the end face of the insert, and continuing to advance the optical fiber so that the flexible thin-film reflective layer protrudes from the insert in a direction away from the optical fiber, further includes: Obtain the target cavity length, and obtain the initial cavity length based on the target cavity length.

8. The method for manufacturing a high-sensitivity fiber optic sensing device according to claim 7, characterized in that, The step of obtaining the target cavity length and obtaining the initial cavity length based on the target cavity length includes: The target cavity length is obtained, and the simulation coupling coefficient of the high-sensitivity fiber optic sensing device under different simulated propulsion amounts is obtained based on the target cavity length. The optimal propulsion amount is obtained based on the simulated coupling coefficient; The initial cavity length is obtained based on the optimal propulsion amount and the target cavity length.

9. The method for manufacturing a high-sensitivity fiber optic sensing device according to claim 6, characterized in that, The sealing of one end of the optical fiber and the ferrule includes: UV-curable adhesive is applied between the periphery of the optical fiber and one end of the insert.

10. The method for manufacturing a high-sensitivity fiber optic sensing device according to claim 9, characterized in that, The fixing of the optical fiber and the insert includes: The UV-curable adhesive is then cured.

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