Self-growing fiber grating preparation method and self-growing fiber grating sensor

Abstract

The invention discloses a self-growing fiber bragg grating preparation method and a self-growing fiber bragg grating sensor, and relates to the technical field of fiber sensing, and the method comprises the steps: coating a preset distance between a first fiber and a second fiber with an ultraviolet glue, forming suspension droplets by using the tension of the glue, and irradiating for a preset time through an ultraviolet light source connected with the first fiber, a refractive index self-growing structure is obtained; in the preparation process, the ultraviolet glue is alternately coated with two different refractive indexes, after the output end of the first optical fiber is updated to be of a refractive index self-growing structure, the steps of moving the second optical fiber, gluing and irradiating are repeated till the total length of the self-growing structure reaches the preset grating length, and the self-growing optical fiber grating is obtained. According to the invention, the periodic modulation of the refractive index of the fiber grating is realized by alternately coating the ultraviolet adhesives with different refractive indexes and accurately controlling irradiation, and the prepared fiber grating sensor has the characteristics of controllable reflection or transmission characteristics, flexible preparation, low cost and excellent biocompatibility, and is suitable for large-scale commercial production.

Description

Technical Field

[0001] The present application relates to the field of optical fiber sensing technology, and in particular to a method for preparing a self-grown optical fiber Bragg grating (FBG) and a self-grown optical fiber Bragg grating (FBG) sensor. Background Art

[0002] Fiber optic sensing technology is one of the key technologies currently being developed in the field of sensing and detection. It is now highly mature and widely used in a wide range of fields and industries to detect various physical quantities and biochemical substances, playing a pivotal role in each field. For example, in the production field, it detects physical quantities such as temperature, stress, and magnetic fields; in the environmental protection field, it detects gases and biochemical substances (such as heavy metal ions); and in the biomedical field, it detects biological tissue cells, viruses, and bacteria.

[0003] Fiber Bragg grating (FBG) sensing technology, a key branch of the fiber optic sensing field, has been widely used in monitoring physical quantities such as temperature and strain in complex environments due to its advantages such as high sensitivity, rapid response, and resistance to electromagnetic interference. However, the preparation of fiber Bragg gratings in related technologies requires complex processes and demanding equipment, such as femtosecond lasers. Maintaining the grating period also places high demands on the equipment used to write the gratings. The preparation of micro-FBGs is even more difficult, requiring even higher equipment requirements and increasing costs.

[0004] Nowadays, with the rapid development of the Internet of Things, smart medical and other fields, the demand for miniaturization, low cost and biocompatibility of fiber Bragg grating sensors has become increasingly prominent. There is an urgent need to develop a fiber Bragg grating preparation method with simplified process, low equipment dependence, controllable cost and excellent biocompatibility. Summary of the Invention

[0005] The purpose of this application is to provide a self-grown fiber Bragg grating preparation method and a self-grown fiber Bragg grating sensor, which can reduce dependence on equipment, simplify the preparation process, reduce costs, and improve biocompatibility, thereby realizing the commercial preparation and wide application of micro fiber Bragg gratings.

[0006] To achieve the above objectives, this application provides the following solutions:

[0007] In a first aspect, the present application provides a method for preparing a self-grown fiber Bragg grating, comprising:

[0008] Fix the first optical fiber and the second optical fiber horizontally respectively, and make the cores of the first optical fiber and the second optical fiber be located in the same horizontal plane;

[0009] Moving the second optical fiber horizontally so that the output end of the first optical fiber maintains a preset distance from the input end of the second optical fiber;

[0010] UV glue is applied at a preset distance between the output end of a first optical fiber and the input end of a second optical fiber, and the UV glue is suspended at the preset distance to form droplets by utilizing the tension of the glue liquid; a UV light source is used to irradiate the UV glue through the first optical fiber for a preset time to obtain a refractive index self-growing structure; the UV light source is connected to the input end of the first optical fiber; the UV glue includes a first refractive index UV glue and a second refractive index UV glue; the second refractive index is greater than the first refractive index; and the refractive index of the UV glue applied each time is different from that of the previous application;

[0011] Update the first optical fiber output end to a refractive index self-growing structure, and return to step "horizontally move the second optical fiber so that the first optical fiber output end and the second optical fiber input end maintain a preset distance" until the total length of all refractive index self-growing structures reaches the preset grating length to obtain a self-grown fiber grating.

[0012] In a second aspect, the present application provides a self-grown fiber Bragg grating sensor, comprising:

[0013] Light source module, transmission optical fiber, fiber Bragg grating sensor module, environment module containing the object to be measured, optical circulator, signal processing module and host computer;

[0014] A light source module, used for providing an input optical signal;

[0015] Transmission optical fiber, used to connect the light source module, optical circulator, fiber Bragg grating sensor module and signal processing module, and transmit input optical signals;

[0016] The fiber Bragg grating sensing module is located in the environment module containing the object to be measured and is used to reflect the input light signal to generate a reflected light signal containing the characteristic reflection wavelength of the object to be measured;

[0017] The input end of the optical circulator is connected to the light source module through a transmission optical fiber; the bidirectional transmission interface is connected to the fiber grating sensor module through a transmission optical fiber, used to transmit the light source signal and collect the reflected light signal; the output interface is connected to the signal processing module through a transmission optical fiber, used to transmit the reflected light signal to the signal processing module;

[0018] A signal processing module, configured to generate spectral data according to the received reflected light signal; the spectral data including the reflection peak wavelength value;

[0019] The host computer is used to obtain the detection result of the object to be tested based on the spectral data and the calibration relationship between the change in the reflection peak wavelength and the measured value of the object to be tested; the measured value includes temperature and concentration.

[0020] According to the specific embodiments provided in this application, this application has the following technical effects:

[0021] The present application provides a method for preparing a self-growing fiber Bragg grating and a self-growing fiber Bragg grating sensor. By fixing a first optical fiber and a second optical fiber horizontally and placing their cores on the same horizontal plane, precise alignment between the optical fibers is achieved. By moving the second optical fiber horizontally and applying ultraviolet glue of different refractive indices, using the tension of the glue to form droplets and irradiating them with ultraviolet light, the problems of high equipment dependence and complex production in the existing fiber Bragg grating preparation are solved, and the simple preparation of a miniature fiber Bragg grating is achieved. By applying ultraviolet glue of different refractive indices multiple times and gradually constructing a refractive index self-growing structure, the problem that the traditional method is difficult to accurately control the grating structure is solved, and precise regulation of the grating length and structure is achieved. The fiber Bragg grating sensor prepared by the above method solves the problem of low biocompatibility of existing sensors and realizes its wide application in biomedicine and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 A schematic diagram of a process for preparing a self-grown fiber Bragg grating according to an embodiment of the present application;

[0024] Figure 2 A schematic flow chart of a method for preparing a self-grown fiber Bragg grating according to another embodiment of the present application;

[0025] Figure 3 A schematic structural diagram of a self-grown fiber Bragg grating sensor provided in one embodiment of the present application; Figure 3 (a) is a schematic diagram of the structure of a reflective self-grown fiber Bragg grating sensor; Figure 3 (b) is a schematic diagram of the structure of a transmission-type self-grown fiber Bragg grating sensor;

[0026] Figure 4 A diagram illustrating the optical transmission principle of a self-grown fiber Bragg grating according to an embodiment of the present application; Figure 4 (a) is a diagram showing the optical transmission principle of a fiber Bragg grating (FBG); Figure 4 (b) is the spectrum of the light source; Figure 4 (c) is the reflection spectrum of the self-grown fiber Bragg grating; Figure 4 (d) is the transmission spectrum of the self-grown fiber Bragg grating;

[0027] Figure 5 A schematic diagram of the biosensing principle of a self-grown fiber Bragg grating provided in one embodiment of the present application; Figure 5(a) Schematic diagram of the biosensing principle of self-grown fiber Bragg grating; Figure 5 (b) is the biosensing reflection spectrum of the self-grown fiber Bragg grating; Figure 5 (c) is the biosensing transmission spectrum through the self-grown fiber Bragg grating;

[0028] Figure 6 A schematic diagram of the structure of a computer device provided in one embodiment of the present application.

[0029] Figure 1: 1-signal processing module; 2-light source module; 3-optical circulator; 4-transmission optical fiber; 5-fiber Bragg grating sensing module; 6-environmental module containing the object to be measured; 7-host computer; 8-first refractive index ultraviolet glue; 9-fiber clamp and base; 10-ultraviolet light source; 11-fiber core; 12-first refractive index self-grown microstructure; 13-second refractive index ultraviolet glue; 14-second refractive index self-grown microstructure; 15-reflected light; 16-reflection spectrum; 17-broadband optical signal; 18-transmitted light; 19-transmission spectrum; 20-object to be measured; 21-sensitive object to the object to be measured. DETAILED DESCRIPTION

[0030] First, the technical terms involved in this application are introduced.

[0031] The core of fiber Bragg grating (FBG) sensing technology is to utilize the characteristics of fiber Bragg grating (FBG) to achieve accurate measurement of target parameters through changes in reflected wavelength. Fiber Bragg grating (FBG) sensing technology has the advantages of compact structure, easy integration and multi-point multiplexing, and can meet the needs of multi-point and distributed monitoring in modern industry. At present, fiber Bragg grating (FBG) sensing technology is mainly divided into Bragg grating-based sensing technology and long-period fiber grating (LPFG)-based sensing technology. Grating-based sensing technology mainly measures parameters such as temperature, strain or magnetic field by monitoring the offset of reflected wavelength / transmitted wavelength. It has high sensitivity and good linear response characteristics, is suitable for high-precision monitoring scenarios, and is widely used in physical quantity monitoring in various fields. In addition, fiber Bragg grating sensing technology is also often used in biochemical sensing. Modifying different sensitive substances at the location of the grating can detect heavy metal ions, pollutants, and even biological secretions, viruses and bacteria in organisms. In the field of life sciences, it can even detect human cell secretions to monitor human health. Miniaturized fiber Bragg grating sensors perform particularly well in these fields. Therefore, miniaturization has also become one of the mainstream directions of fiber Bragg grating sensing development, which can enable fiber Bragg grating sensing to be applied to more fields and have better performance.

[0032] However, the preparation of fiber Bragg gratings in related technologies requires complex processes and demanding equipment, such as femtosecond lasers. Ensuring the grating period also places high demands on the equipment used to write the gratings. The preparation of micro-fiber Bragg gratings is even more difficult, requiring even higher equipment requirements and increasing costs. These factors have hindered the commercialization and widespread application of microstructured fiber Bragg grating sensors. Only by overcoming the shortcomings of high cost, high equipment requirements, and strong dependence can micro-fiber Bragg grating sensors achieve more commercial production and widespread application in the future. Against this backdrop, the continuous development of fiber optic sensors with simple processes, novel structures, low costs, and good performance is a major focus.

[0033] This application can self-grow a low-refractive-index photosensitive polymer microstructure on the end face of an optical fiber through ultraviolet curing. A high-refractive-index photosensitive polymer microstructure can then be grown using the same method based on the already grown polymer microstructure. Repeated growth of multiple photosensitive polymer microstructures with alternating high and low refractive indices can form a periodic grating structure. A reflective fiber Bragg grating sensor can be constructed based on its reflected wavelength, or a transmissive fiber Bragg grating sensor can be constructed by connecting a transmission optical fiber to the end of the photosensitive polymer grating periodic grating structure. The sensor can be used to measure various physical quantities, and biochemical sensing can also be achieved by modifying sensitive substances on the photosensitive polymer grating.

[0034] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0035] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0036] In an exemplary embodiment, Figure 1 As shown, a method for preparing a self-grown fiber Bragg grating is provided, comprising the following steps 101 to 104. In which:

[0037] Step 101 : fix the first optical fiber and the second optical fiber horizontally respectively, and make the cores of the first optical fiber and the second optical fiber be located in the same horizontal plane.

[0038] Step 102: horizontally move the second optical fiber so that the output end of the first optical fiber maintains a preset distance from the input end of the second optical fiber.

[0039] Step 103, applying ultraviolet glue at a preset distance between the output end of the first optical fiber and the input end of the second optical fiber, using the tension of the glue to suspend the ultraviolet glue at the preset distance to form droplets; and using an ultraviolet light source to irradiate the ultraviolet glue through the first optical fiber for a preset time to obtain a refractive index self-growing structure; the ultraviolet light source is connected to the input end of the first optical fiber; the ultraviolet glue includes a first refractive index ultraviolet glue and a second refractive index ultraviolet glue; the second refractive index is greater than the first refractive index; the refractive index of the ultraviolet glue applied each time is different from the previous time.

[0040] Step 104: update the first optical fiber output end to a refractive index self-grown structure, and return to step 102 until the total length of all refractive index self-grown structures reaches a preset grating length, thereby obtaining a self-grown fiber Bragg grating.

[0041] By implementing the above steps 101 to 104, the present application can effectively reduce the dependence of the fiber Bragg grating preparation process on complex equipment. Through simple horizontal fixing and moving operations, combined with the refractive index change of UV glue and UV light irradiation, the self-growth preparation of micro fiber Bragg gratings is achieved.

[0042] As an optional implementation, ultraviolet glue (polymer) is dripped on the end faces of two optical fibers, and ultraviolet light with a wavelength of 350-400nm is input at one end. The ultraviolet light is emitted from the optical fiber core coated with ultraviolet glue and irradiates the ultraviolet glue to achieve photocuring and grow polymer microstructures. The repeated growth of polymer microstructures with high and low refractive indices and the same length and diameter can form a periodic micro-grating structure to constitute a self-grown micro-fiber grating. The length of the microstructure growth can be controlled by adjusting the power of the ultraviolet light and the illumination time to form self-grown micro-gratings of different periods. The shape of the generated structure can be changed by changing the properties of the incident light to achieve self-grown micro-gratings of different shapes and different sensitivities.

[0043] In another exemplary embodiment of the present application, the method for preparing a self-grown fiber Bragg grating further includes:

[0044] Adjust the structural parameters of the self-grown fiber Bragg grating by the following operations:

[0045] The longitudinal length of the self-grown fiber grating is adjusted by blocking the input end or the output end of the first optical fiber.

[0046] Alternatively, a filter is placed at the input end or output end of the first optical fiber to adjust the longitudinal length or period of the self-grown optical fiber grating.

[0047] Alternatively, a mask is provided at the input end or output end of the first optical fiber to adjust the shape, lateral size and quantity of the self-grown optical fiber grating.

[0048] In another exemplary embodiment of the present application, adjusting the structural parameters of the self-grown fiber Bragg grating further includes:

[0049] The optical power of the ultraviolet light source and the preset time for the ultraviolet light source to irradiate the ultraviolet glue are adjusted to adjust the longitudinal length of the self-grown fiber grating.

[0050] Or the refractive index of the UV glue can be adjusted to adjust the effective refractive index of the self-grown fiber grating.

[0051] As an optional implementation, the UV glue used for photocuring can be divided into UV glues with high and low refractive indices, which can be adjusted according to the characteristic reflection wavelength. The type or composition of the UV glue can regulate the effective refractive index of the self-grown micro-grating periodic structure to regulate the characteristic reflection wavelength. Similarly, more types of periodic structure fiber gratings can be prepared by using UV glues with more different refractive indices or gradient refractive indices.

[0052] In another exemplary embodiment of the present application, the UV adhesive further comprises a UV adhesive or UV-curable hydrogel doped with a special functional substance, such as a magnetic substance, a heavy metal ion-sensitive substance, or a biocompatible substance. This not only enhances the self-grown fiber Bragg grating's sensitivity to substances such as magnetic fields and heavy metal ions, and its sensitivity to physical quantities such as temperature and stress, but also imparts additional properties such as good biocompatibility and hydrophilicity, enabling a wider range of applications.

[0053] In another exemplary embodiment of the present application, Figure 2The figure shows a flow chart for the preparation of self-grown fiber gratings. Self-grown fiber gratings are prepared by self-growth through ultraviolet curing. Two sections of transmission optical fiber 4 (multimode optical fiber, core 11 with a diameter of 50 μm and a cladding diameter of 125 μm) are placed on the optical fiber holder and base 9 for fixation. The cores 11 of the two sections of transmission optical fiber 4 are aligned on the same horizontal plane to facilitate the growth of gratings. First, the first refractive index ultraviolet glue (low refractive index ultraviolet glue) 8 is applied to the ends of the two sections of transmission optical fiber. The first refractive index ultraviolet glue is suspended between the two optical fibers using its own tension to form a droplet. Then, an ultraviolet light source 10 is connected from the other end of the transmission optical fiber 4 to propagate the ultraviolet light signal along the core 11 and output from the end of the optical fiber to irradiate the first refractive index ultraviolet glue (low refractive index ultraviolet glue) 8 for about 2-3 minutes to complete the photocuring, forming a first refractive index self-grown microstructure along the shape of the light transmission trajectory. 12, whose shape changes according to the shape of the end face of the fiber core 11; after completing the first first refractive index self-grown microstructure 12, self-growth continues on the basis, and the second refractive index ultraviolet glue 13 (higher than the first refractive index ultraviolet glue 8) is coated between the first refractive index self-grown microstructure 12 and the end face of the transmission optical fiber at the other end, and is suspended between the first refractive index self-grown microstructure 12 and the end face of the optical fiber by using its tension, and then the ultraviolet light signal is propagated along the fiber core 11 and the first refractive index self-grown microstructure 12 through the ultraviolet light source 10 and emitted to irradiate the second refractive index ultraviolet glue 13 for about 2-3 minutes to complete light curing, thereby forming a second refractive index self-grown microstructure 14 along the shape of the light transmission trajectory.

[0054] Repeating the above operation to form a self-grown microstructure with alternating first and second refractive indices can form a periodic grating structure and finally form a self-grown fiber Bragg grating. According to the characteristic reflection wavelength formula of Bragg grating λ=2n eff Λ can be used to know the characteristic reflection wavelength λ of the self-grown fiber Bragg grating and the effective refractive index n of the self-grown fiber Bragg grating. eff The period Λ of the self-grown fiber Bragg grating is related to the grating period Λ of the self-grown fiber Bragg grating. By adjusting the light curing time and the optical power of the ultraviolet light source 10, the length of the first refractive index self-grown microstructure 12 and the second refractive index self-grown microstructure 14 can be controlled to control the period Λ of the self-grown fiber Bragg grating and thus the characteristic reflection wavelength λ of the self-grown fiber Bragg grating. The effective refractive index n of the self-grown fiber Bragg grating can also be controlled by adjusting the refractive index of the first refractive index ultraviolet glue 8 and the second refractive index ultraviolet glue 13. eff The characteristic reflection wavelength λ of the self-grown fiber Bragg grating can then be controlled. Compared to traditional fiber Bragg grating preparation, the control of the characteristic reflection wavelength λ of the self-grown fiber Bragg grating is more convenient and requires less equipment precision.

[0055] Based on the same inventive concept, embodiments of the present application also provide a self-grown fiber Bragg grating sensor for implementing the aforementioned method for preparing a self-grown fiber Bragg grating. The solution provided by this device is similar to the solution described in the aforementioned method. Therefore, the specific limitations of one or more of the following self-grown fiber Bragg grating sensor embodiments can be found in the aforementioned limitations of the self-grown fiber Bragg grating preparation method and will not be further elaborated here.

[0056] In an exemplary embodiment, Figure 3 As shown in (a), a self-grown fiber Bragg grating sensor is provided, which includes: a light source module 2, a transmission optical fiber 4, a fiber Bragg grating sensing module 5, an environment module 6 containing a test object, an optical circulator 3, a signal processing module 1 and a host computer 7.

[0057] The light source module 2 is used to provide an input optical signal.

[0058] The transmission optical fiber 4 is used to connect the light source module 2, the optical circulator 3, the fiber Bragg grating sensor module 5 and the signal processing module 1 to transmit the input optical signal.

[0059] The fiber Bragg grating sensing module 5 is located in the environment module 6 containing the object to be measured, and is used to reflect the input optical signal to generate a reflected optical signal containing a characteristic reflection wavelength of the object to be measured.

[0060] The input end of the optical circulator 3 is connected to the light source module 2 through the transmission optical fiber 4; the bidirectional transmission interface is connected to the fiber grating sensor module 5 through the transmission optical fiber 4, which is used to transmit the light source signal and collect the reflected light signal; the output interface is connected to the signal processing module 1 through the transmission optical fiber 4, which is used to transmit the reflected light signal to the signal processing module 1. Specifically, the optical circulator 3 is an optical fiber device required for a reflective optical fiber sensor. The input end is connected to the input light source of the light source module 2 through the transmission optical fiber 4, and the bidirectional transmission interface is connected to the fiber grating sensor module 5 through the transmission optical fiber 4. The input light signal of the light source module 2 is input into the fiber grating sensor module 5 and its reflected light signal is collected and transmitted back to the optical circulator 3. The output interface is connected to the signal processing module 1 through the transmission optical fiber 4, and the reflected light signal is transmitted to the signal processing module 1 for processing. The signal processing module 1 includes a fiber spectrometer, which is mainly used to receive the reflected light signal (and perform demodulation processing to form a spectrum).

[0061] The signal processing module 1 is used to generate spectrum data according to the received reflected light signal; the spectrum data includes the reflection peak wavelength value.

[0062] The host computer 7 is used to obtain the detection result of the object to be tested based on the spectral data and the calibration relationship between the change in the reflection peak wavelength and the measured value of the object to be tested; the measured value includes temperature, concentration, pH value, pressure, electric field strength or magnetic field strength.

[0063] In this embodiment, the optical circulator 3 is mainly used for a reflective fiber Bragg grating sensor. The light source module includes a broadband light source, which provides a broadband optical signal 17 to enter the entire sensing system so that the self-grown fiber Bragg grating in the fiber Bragg grating sensing module 5 can generate a reflected light signal; thereby ensuring that the wavelength coverage range of the entire light source includes the characteristic reflection wavelength of the fiber Bragg grating sensing module 5; the transmission optical fiber 4 transmits the broadband optical signal 17 of the light source module 2 to the fiber Bragg grating sensing module 5 and collects the grating reflected light signal in the fiber Bragg grating sensing module 5; the grating of the fiber Bragg grating sensing module 5 is the end of the optical fiber. Self-grown microstructures are formed by self-curing with ultraviolet light. Interlaced microstructures of different refractive indices form a periodic structure with grating characteristics, forming a self-grown fiber Bragg grating. The characteristic reflection wavelength is calculated based on the grating period and the effective refractive index of the grating. The grating period can be changed by regulating the UV curing time and UV light power, and the effective refractive index of the grating can be controlled by adjusting the refractive index of the UV adhesive, thus producing a self-grown micro-grating with a characteristic reflection wavelength. The preparation process of self-grown micro-gratings does not require laser grating inscription, making the preparation rapid, highly controllable, and less dependent on equipment, greatly reducing production costs. Due to the characteristics of its periodic structure, light at its characteristic reflection wavelength and its nearby (extremely narrow) wavelengths has extremely high reflectivity; light at its non-characteristic reflection wavelength and its nearby wavelengths has extremely high transmittance, thus forming sharp reflection and transmission peaks. The external environment or sensitive substances can change the characteristic reflection wavelength of the grating by changing the period length or effective refractive index of the grating. The self-grown fiber Bragg grating sensor can realize qualitative and quantitative sensing of physical quantities or biochemical substances by detecting whether the reflection wavelength of the fiber Bragg grating sensing module 5 changes and the amount of change; the optical circulator 3 is mainly used for reflective fiber Bragg grating sensors, which can collect the reflected light signal reflected back by the fiber Bragg grating sensing unit in a unidirectional manner and transmit it to the signal processing module 1; the signal processing module 1 includes a fiber spectrometer, which collects the reflected light 15 of the fiber Bragg grating sensing unit and processes it, and transmits it to the host computer 7 after processing to form a spectrum; the host computer 7 can present the spectral image processed by the fiber spectrometer in the signal processing module, and can be calibrated according to the center wavelength drift of the sensor reflection peak / transmission peak and the mass of the physical quantity or biochemical substance to be measured, that is, by calculating the relationship between the reflection peak wavelength / transmission peak wavelength and the physical quantity or biochemical substance, a calibration equation is obtained. After the reflection peak wavelength / transmission peak wavelength is detected in the subsequent sensing detection, the qualitative and quantitative sensing detection of the physical quantity and biochemical substance can be realized according to the calibration relationship. The reflective self-grown fiber Bragg grating sensor can directly insert the fiber Bragg grating sensing module 5 into the environment to be detected for detection.

[0064] As an optional implementation, Figure 3As shown in (b), the self-grown fiber Bragg grating sensor further includes: a light source module 2, a transmission optical fiber 4, a fiber Bragg grating sensing module 5, an environment module 6 containing a test object, a signal processing module 4 and a host computer 7.

[0065] The light source module 2 is connected to the fiber grating sensor module 5 via the transmission optical fiber 4 and is used to provide an input optical signal.

[0066] The transmission optical fiber 4 is used to transmit the input optical signal. The transmission optical fiber 4 connects the light source module 2, the fiber Bragg grating sensor module 5 and the fiber spectrometer to form a transmission optical path, which is mainly used for collecting and transmitting the optical signal of the light source module 2 and the transmitted light of the self-grown fiber Bragg grating.

[0067] The fiber Bragg grating sensing module 5 is located in the environment module 6 containing the object to be measured and is connected to the signal processing module 1 through the transmission optical fiber 4. It is used to transmit the input optical signal and generate a transmission optical signal containing the characteristic transmission wavelength of the object to be measured.

[0068] The signal processing module 1 is also connected to the host computer 7 and is used to generate spectrum data according to the received transmitted light signal; the spectrum data includes the transmission peak wavelength value.

[0069] The host computer 7 is used to obtain the detection result of the object to be tested based on the spectral data and the calibration relationship between the change in the transmission peak wavelength and the measured value of the object to be tested; the measured value includes temperature, concentration, pH value, pressure, electric field strength or magnetic field strength.

[0070] The transmission type self-grown fiber Bragg grating sensor can perform detection by placing the fiber Bragg grating sensing module 5 in the environment to be detected.

[0071] As an optional implementation, the fiber Bragg grating sensing module 5 includes a self-grown fiber Bragg grating.

[0072] Using a sealed or open packaging structure, a self-grown fiber Bragg grating (FBG) is inserted and fixed into an environmental module containing the object to be detected. This packaging forms a detection cavity, and sensitive substances are modified on the periodic structure of the self-grown micro-grating to enable the detection of biochemical substances.

[0073] Specifically, the self-grown fiber Bragg grating can be inserted into an open cavity structure such as a capillary through packaging to reduce interference and noise generated by the external environment, thereby improving the signal-to-noise ratio and sensing accuracy of the reflection spectrum and transmission spectrum.

[0074] Among them, by implementing this embodiment, the fiber Bragg grating sensing module 5 can adopt multi-core optical fiber in combination with optical elements such as micro masks to realize the preparation of multiple self-grown fiber Bragg gratings at the same time and the preparation of multiple self-grown fiber Bragg gratings with different shapes, sizes and lengths. It can also grow multiple self-grown fiber Bragg gratings with different shapes, lengths and even effective refractive indices. The joint interference of the reflected light signals / transmitted light signals of multiple self-grown fiber Bragg gratings can improve the interference sensing performance of the fiber Bragg grating sensing module 5.

[0075] As an optional embodiment, the self-grown fiber Bragg grating includes a sensitive substance to be detected, which is modified on the self-grown fiber Bragg grating by silanization or electrostatic adsorption; the sensitive substance includes an antibody, bacteriophage, or enzyme. This enables the self-grown fiber Bragg grating sensor to detect biomolecules, viruses, bacteria, and microorganisms, broadening the application areas of fiber Bragg grating sensors based on self-grown micro-brackets.

[0076] As an optional embodiment, the self-grown fiber Bragg grating sensing module further includes a cascaded self-grown fiber Bragg grating (FBG); the cascaded FBG comprises multiple self-grown fiber Bragg gratings (FBGs) with different characteristic reflection wavelengths cascaded on a single optical fiber. By cascading multiple self-grown micro-FBGs with different periods, parameter compensation (such as temperature or magnetic field) and multi-parameter sensing are achieved, namely, multi-parameter sensing is achieved by shifting the different reflection peak wavelengths / transmission peak wavelengths in the spectrum.

[0077] As an optional implementation, the signal processing module includes a fiber optic spectrometer.

[0078] The optical fiber spectrometer is used to collect spectrum data of the object to be measured in real time and output the reflection peak wavelength value of the object to be measured.

[0079] As an optional embodiment, the optical path connected by the transmission optical fiber can be coated with corresponding noise absorbing materials to reduce the error caused by the environment to the sensor during the sensing detection process, thereby improving the signal-to-noise ratio and detection accuracy of the sensor.

[0080] In summary, if Figure 3 (a) and Figure 3As shown in Figure (b), the self-grown fiber Bragg grating (SFG) sensor based on SFG includes a light source module 2, a transmission fiber 4, a fiber Bragg grating (FBG) sensing module 5, an optical circulator 3, a signal processing module 1, and a host computer 7. The light source module 2 inputs a broadband optical signal 17 (650nm-1700nm) into the entire SFG sensor via the transmission fiber 4. The transmission fiber 4 connects the light source module 2, the FBG sensing module 5, the optical circulator 3 (for a reflective SFG sensor), and the signal processing module 1 to complete the optical path of the entire sensor. The broadband optical signal 17 is transmitted to the FBG sensing module 5, and the reflected and transmitted optical signals are collected and transmitted to the information processing module 1 for processing. The fiber Bragg grating sensing unit 5 is composed of a self-grown fiber Bragg grating (FBG) in which a plurality of microstructures are sequentially grown on the end face of the optical fiber by ultraviolet curing to form a periodic structure. When a broadband optical signal 17 is input into the self-grown fiber Bragg grating in the fiber Bragg grating sensing module 5, a narrowband optical signal near the characteristic reflection wavelength of the self-grown micro Bragg grating will be reflected back, and light with a non-characteristic reflection wavelength will be transmitted through and enter the next periodic structure, repeatedly forming a superposition of reflected light and transmitted light. The entire fiber Bragg grating sensing module 5 is placed in an environmental module 6 containing the object to be tested for detection. The environment can be a physical quantity detection environment (such as an electromagnetic field, an oven, etc.) or a biochemical environment (such as a heavy metal ion solution, a microbial culture medium, etc.).

[0081] The optical circulator 3 serves as a unidirectional transmission fiber element for the reflected light signal in the reflective self-grown fiber Bragg grating sensor. Its input end (which can only input light but not output light) is connected to the light source module 2 via a transmission fiber 4 to receive the broadband light signal 17. Its bidirectional end (which can both output and receive light) is connected to the fiber Bragg grating sensor module 5 via a transmission fiber 4, transmitting the broadband light signal 17 from the light source module 2 to the fiber Bragg grating sensor module 5 and receiving the reflected light signal generated thereby. Its output end (which can only output light but not input light) is connected to the signal processing module 1 via a transmission fiber 4 and transmits the reflected light 15 signal there for collection and processing. The signal processing module 1 includes a fiber spectrometer. The reflected light 15 signal / transmitted light 18 signal is transmitted via the transmission fiber 4 to this module for collection and processing to form a spectrum. The spectrum information is then displayed on a display by a host computer 7. The relationship between the reflection peak wavelength / transmission peak wavelength and the amount of the physical quantity / biological substance to be measured can be calculated and calibrated. Subsequently, qualitative and quantitative detection of the amount of the physical quantity / biological substance to be measured can be achieved based on the calibration relationship. Fiber Bragg grating sensors based on self-grown micro-gratings can be used to build transmission sensing systems as well as reflection sensing systems, and have good flexibility.

[0082] In another exemplary embodiment of the present application, Figure 4 (a) and Figure 4(b) shows the principle diagram of self-grown micro-grating light transmission and the spectrum of the broadband light signal 17 of the light source module. The two sides of the self-grown micro-grating are connected to the end face of the transmission fiber through UV glue curing. The cores 11 of the transmission fibers on both sides are horizontally aligned with the self-grown fiber grating. After the broadband light signal 17 is input from the light source module 2 at one end and enters the fiber grating sensing module 5, the narrowband light near the characteristic reflection wavelength of the self-grown fiber grating is reflected back to the direction of the broadband light signal 17 after each cycle, forming the reflected light 15. After all the cycles, the reflected light 15 is converged and the intensity is superimposed to form the reflection spectrum 16. Figure 4 As shown in (c), the specific reflection spectrum image will show a sharp reflection peak near the characteristic reflection wavelength; each time the light of the non-characteristic reflection wavelength passes through a period of self-grown micro-grating, it will be transmitted to form a transmitted light 18. After all the periods of transmitted light 18 converge, the loss and superposition are emitted to form a transmission spectrum 19, as shown in Figure 4 As shown in (d), the specific transmission spectrum image will show a sharp loss peak near the characteristic reflection wavelength. During the sensing process, sensing can be achieved based on the changes in the characteristic reflection wavelength and non-characteristic reflection wavelength.

[0083] In another exemplary embodiment of the present application, Figure 5 Figure (a) shows the principle diagram of self-grown fiber Bragg grating (FBG) biosensing. Using self-grown fiber Bragg grating (FBG) for biosensing, a sensitive analyte 21 (antibody, bacteriophage, enzyme, etc.) can be modified onto the FBG through silanization, electrostatic adsorption, or other methods to form a self-grown fiber Bragg grating (FBG)-based FBG biosensor. The sensing portion of the self-grown fiber Bragg grating (FBG) biosensor, i.e., the FBG sensing module 5, is placed in a liquid or gaseous environment containing an analyte 20 (bacteria, viruses, biomolecules, etc.). Upon encounter, the analyte 20 and the sensitive analyte 21 undergo specific binding to form a complex.

[0084] Therefore, when the broadband optical signal 17 is input from the fiber core 11 into the self-grown fiber Bragg grating of the fiber Bragg grating sensor module 5, according to the characteristic reflection wavelength formula of the Bragg grating λ=2n eff Λ, the characteristic reflection wavelength λ will be determined by the effective refractive index n eff and the grating period Λ. When the sensitive object 21 of the self-grown fiber grating is combined with the object 20 to form a combination, the effective refractive index of the self-grown microstructure at the corresponding position will change, thereby affecting the effective refractive index n of the self-grown fiber grating. eff , according to the change of effective refractive index, the characteristic reflection wavelength λ of the self-grown fiber Bragg grating will drift. Figure 5 (b) and Figure 5As shown in (c), the reflection peak wavelength and loss peak wavelength on the reflection spectrum 16 and the transmission spectrum 19 will change, and their peak positions will also drift. The specific drift direction and wavelength change direction depend on the effective refractive index n of the self-grown fiber Bragg grating after the sensitive object 21 of the object to be measured is combined with the object to be measured 20. eff The change in characteristic reflection wavelength λ can be calculated and calibrated with the known concentration of the analyte 20. Based on the calibration relationship, the change in characteristic reflection wavelength λ can be directly calculated to achieve qualitative and quantitative biochemical / biological sensing of the concentration of the unknown analyte 20.

[0085] This application has the following advantages:

[0086] 1. The present application adopts the method of self-growing micro-gratings on the end face of optical fiber through ultraviolet curing to build a fiber grating sensor. Utilizing the characteristics of optical waveguide transmission of optical fiber core, ultraviolet glue is coated on the ends of two optical fibers with aligned cores, ultraviolet light is transmitted through one of the optical fibers and output from the end of the optical fiber coated with ultraviolet glue to irradiate the ultraviolet glue for photocuring. According to the transmission direction of the optical waveguide, the cured ultraviolet glue forms a micro-polymer structure, and then ultraviolet glue with different refractive indices is replaced to continue to grow micro-polymer structures with different refractive indices on the basis of the original micro-polymer structure. Repeated growth multiple times forms a periodic structure to constitute a self-grown micro-grating. The fiber grating sensor prepared by this method does not require a laser to write the grating, and is faster to prepare than the preparation of traditional fiber grating sensors, which greatly reduces the cost and dependence on equipment.

[0087] 2. The present application adopts a method of preparing self-grown micro-gratings by ultraviolet curing on the end face of the optical fiber. The self-grown micro-gratings of corresponding shape, size and number can be self-grown according to the shape, size and number of the optical fiber core. The optical fiber input end or the input end can also be temporarily blocked, and filters and masks can be placed on the input end to achieve the simultaneous self-growth of self-grown micro-gratings of different shapes, sizes and even different numbers and lengths at the end of the optical fiber. Compared with the preparation of traditional special optical fiber gratings, this method for preparing micro-gratings has the advantages of being simpler, more flexible, more efficient and lower cost.

[0088] 3. This community uses self-grown micro-gratings as the sensing unit of self-grown fiber Bragg grating sensors. During the preparation process, the grating period can be controlled by controlling the power of the ultraviolet light and the time of light curing to produce self-grown micro-gratings with different periods. UV glues with different refractive indices can be used to prepare the self-grown micro-gratings, thereby controlling the effective refractive index of the self-grown micro-gratings and, in turn, regulating the characteristic reflection wavelength to achieve control of the optical signal. Compared with the preparation of traditional fiber Bragg gratings, this method has higher flexibility and controllability and is simpler to operate. In addition, by replacing different types of UV glue (doped with different substances, such as Fe3O4, or UV-cured hydrogels) with different properties, different physical quantities and biochemical substances can be sensed and detected, and special functionalities such as biocompatibility and hydrophilicity can be given to the self-grown micro-gratings. A reflective self-grown fiber Bragg grating sensor can be constructed based on its reflection wavelength; or a transmissive self-grown fiber Bragg grating sensor can be constructed by connecting a transmission optical fiber to the end of a photosensitive polymer grating periodic grating structure; the fiber Bragg grating sensor prepared by this method does not require writing gratings on the optical fiber core, and the preparation is fast, which reduces the cost of preparing traditional fiber Bragg grating sensors and has lower equipment requirements. The prepared sensor can be used to measure various physical quantities, and modifying sensitive substances on the photosensitive polymer grating can also realize biochemical sensing, which can enable the sensor to achieve a wider range of sensing and detection applications.

[0089] In an exemplary embodiment, a computer device is provided. The computer device may be a server or a terminal. The internal structure diagram thereof may be as follows: Figure 6 As shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, abbreviated as I / O) and a communication interface. The processor, the memory and the input / output interface are connected via a system bus, and the communication interface is connected to the system bus via the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store spectral data of the object to be measured. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal via a network connection.

[0090] Those skilled in the art will understand that Figure 6The structure shown in the figure is merely a block diagram of a portion of the structure related to the solution of the present application and does not constitute a limitation on the computer device to which the solution of the present application is applied. A specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement. In an exemplary embodiment, a computer device is provided, including a memory and a processor. The memory stores a computer program, and the processor implements the steps of the above-mentioned method embodiments when executing the computer program.

[0091] In an exemplary embodiment, a computer-readable storage medium is provided, storing a computer program. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments are implemented.

[0092] In an exemplary embodiment, a computer program product is provided, including a computer program. When the computer program is executed by a processor, the steps in the above method embodiments are implemented.

[0093] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0094] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, database or other media used in the embodiments provided in this application may include at least one of non-volatile and volatile memory. Non-volatile memory may include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory may include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM may be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0095] The databases involved in the various embodiments provided herein may include at least one of a relational database and a non-relational database. Non-relational databases may include, but are not limited to, distributed databases based on blockchains. The processors involved in the various embodiments provided herein may include, but are not limited to, general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic units, data processing logic units based on quantum computing, and the like.

[0096] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0097] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the method and core concept of this application. At the same time, for those skilled in the art, based on the concept of this application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A method for preparing a self-grown fiber Bragg grating, characterized in that: The method for preparing the self-grown fiber Bragg grating comprises: Fix the first optical fiber and the second optical fiber horizontally respectively, and make the cores of the first optical fiber and the second optical fiber be located in the same horizontal plane; Moving the second optical fiber horizontally so that the output end of the first optical fiber maintains a preset distance from the input end of the second optical fiber; UV glue is applied at a preset distance between the output end of a first optical fiber and the input end of a second optical fiber, and the UV glue is suspended at the preset distance to form droplets by utilizing the tension of the glue liquid; a UV light source is used to irradiate the UV glue through the first optical fiber for a preset time to obtain a refractive index self-growing structure; the UV light source is connected to the input end of the first optical fiber; the UV glue includes a first refractive index UV glue and a second refractive index UV glue; the second refractive index is greater than the first refractive index; and the refractive index of the UV glue applied each time is different from that of the previous application; Update the first optical fiber output end to a refractive index self-grown structure, and return to step "horizontally move the second optical fiber so that the first optical fiber output end and the second optical fiber input end maintain a preset distance" until the total length of all refractive index self-grown structures reaches the preset grating length, thereby obtaining a self-grown fiber Bragg grating.

2. The method for preparing a self-grown fiber Bragg grating according to claim 1, wherein: The method for preparing the self-grown fiber Bragg grating further includes: Adjust the structural parameters of the self-grown fiber Bragg grating by the following operations: Adjusting the longitudinal length of the self-grown fiber grating by blocking the input end or the output end of the first optical fiber; or by placing a filter at the input end or output end of the first optical fiber to adjust the longitudinal length or period of the self-grown fiber grating; Alternatively, a mask is provided at the input end or output end of the first optical fiber to adjust the shape, lateral size and quantity of the self-grown optical fiber grating.

3. The method for preparing a self-grown fiber Bragg grating according to claim 2, wherein: The adjusting of the structural parameters of the self-grown fiber Bragg grating further includes: Adjusting the optical power of the ultraviolet light source and the preset time for the ultraviolet light source to irradiate the ultraviolet glue, and adjusting the longitudinal length of the self-grown fiber grating; Or the refractive index of the UV glue can be adjusted to adjust the effective refractive index of the self-grown fiber grating.

4. The method for preparing a self-grown fiber Bragg grating according to claim 1, wherein: The UV glue further includes: UV glue doped with special functional substances or UV curing hydrogel, wherein the special functional substances include magnetic substances, heavy metal ion sensitive substances or bio-affinity substances.

5. A self-grown fiber Bragg grating sensor, characterized in that: The self-grown fiber Bragg grating sensor comprises: a light source module, a transmission optical fiber, a fiber Bragg grating sensing module, an environment module containing a test object, an optical circulator, a signal processing module and a host computer; A light source module, used for providing an input optical signal; Transmission optical fiber, used to connect the light source module, optical circulator, fiber Bragg grating sensor module and signal processing module, and transmit input optical signals; The fiber Bragg grating sensing module is located in the environment module containing the object to be measured and is used to reflect the input light signal to generate a reflected light signal containing the characteristic reflection wavelength of the object to be measured; The input end of the optical circulator is connected to the light source module through a transmission optical fiber; the bidirectional transmission interface is connected to the fiber grating sensor module through a transmission optical fiber, used to transmit the light source signal and collect the reflected light signal; the output interface is connected to the signal processing module through a transmission optical fiber, used to transmit the reflected light signal to the signal processing module; A signal processing module, configured to generate spectral data according to the received reflected light signal; the spectral data including the reflection peak wavelength value; The host computer is used to obtain the detection result of the object to be tested based on the spectral data and the calibration relationship between the change in the reflection peak wavelength and the measured value of the object to be tested; the measured value includes temperature, concentration, pH value, pressure, electric field strength or magnetic field strength.

6. The self-grown fiber Bragg grating sensor according to claim 5, characterized in that: The self-grown fiber Bragg grating sensor further comprises: a light source module, a transmission optical fiber, a fiber Bragg grating sensing module, an environment module containing an object to be measured, a signal processing module and a host computer; The light source module is connected to the fiber grating sensor module via a transmission optical fiber and is used to provide an input optical signal; Transmission optical fiber, used to transmit input optical signals; The fiber Bragg grating sensing module is located in the environment module containing the object to be measured and is connected to the signal processing module via a transmission optical fiber. It is used to transmit the input optical signal and generate a transmitted optical signal containing the characteristic transmission wavelength of the object to be measured. The signal processing module is also connected to the host computer and is used to generate spectrum data according to the received transmission light signal; the spectrum data includes the transmission peak wavelength value; The host computer is used to obtain the detection result of the object to be tested based on the spectral data and the calibration relationship between the change in the transmission peak wavelength and the measured value of the object to be tested; the measured value includes temperature, concentration, pH value, pressure, electric field strength or magnetic field strength.

7. The self-grown fiber Bragg grating sensor according to claim 5, characterized in that: The self-grown fiber Bragg grating sensing module includes a self-grown fiber Bragg grating; A sealed or open packaging structure is used to insert and fix the self-grown fiber Bragg grating into an environmental module containing the object to be measured.

8. The self-grown fiber Bragg grating sensor according to claim 7, characterized in that: The self-grown optical fiber grating includes a sensitive substance to be detected which is modified on the self-grown optical fiber grating by silanization or electrostatic adsorption; the sensitive substance includes an antibody, a bacteriophage or an enzyme.

9. The self-grown fiber Bragg grating sensor according to claim 7, characterized in that: The fiber Bragg grating sensing module further comprises: a cascaded self-grown fiber Bragg grating; the cascaded self-grown fiber Bragg grating is a cascade of multiple self-grown fiber Bragg gratings with different characteristic reflection wavelengths on the same optical fiber.

10. The self-grown fiber Bragg grating sensor according to claim 5, characterized in that: The signal processing module includes a fiber optic spectrometer; The optical fiber spectrometer is used to collect spectrum data of the object to be measured in real time and output the reflection peak wavelength value of the object to be measured.

Images