Inscribing system of fiber bragg grating

Abstract

The utility model relates to an inscribing system of a fiber Bragg grating, and the system comprises a femtosecond laser which is used for transmitting femtosecond laser; the spatial light modulator is used for modulating the femtosecond laser into a cylindrical lens linear light field; and the inscribing platform is used for receiving the linear light field of the cylindrical lens and providing an inscribing space of the fiber bragg grating. Mainly, femtosecond laser (in a focus state) is modulated into a cylindrical lens linear light field through a spatial light modulator, the fiber bragg grating is inscribed based on the cylindrical lens linear light field, and the inscribing is a surface processing technology, so that the method has the advantages of high inscribing quality and high inscribing efficiency; the problems that an existing inscribing system of the fiber bragg grating is low in inscribing quality and inscribing efficiency are solved.

Description

Technical Field

[0001] The present application relates to the field of micro-nano manufacturing, and in particular to a fiber Bragg grating writing system. Background Art

[0002] Fiber Bragg grating (FBG) has important application value in the field of optical fiber communication. It can be used as wavelength division multiplexer, gain flattener of optical fiber amplifier, dispersion compensator, uplink and downlink of all-optical network, wavelength routing, optical switching, etc. In the traditional method, the fiber Bragg grating is mainly written on the photosensitive optical fiber using ultraviolet continuous or excimer laser. The fiber Bragg grating prepared in this way has the disadvantages of poor thermal stability, easy to be erased under high temperature conditions, cumbersome fiber hydrogen pretreatment and unsuitable for high temperature environment. Correspondingly, the fiber Bragg grating prepared by femtosecond laser micro-nano processing technology can overcome the above-mentioned shortcomings of fiber Bragg grating to a certain extent.

[0003] In the femtosecond laser point-by-point writing system, the limited target area generated by a single pulse will lead to local effects, resulting in strong cladding mode loss, which in turn reduces the writing quality of the fiber Bragg grating. At the same time, the femtosecond laser point-by-point writing system has the problem of low writing efficiency. Utility Model Content

[0004] The utility model provides a fiber Bragg grating writing system and system, and a grating writing control method to solve the problems of low writing quality and low writing efficiency in the current fiber Bragg grating writing system.

[0005] In a first aspect, the utility model provides a fiber Bragg grating writing system, the writing system comprising:

[0006] A femtosecond laser, used for emitting femtosecond laser;

[0007] A spatial light modulator, used for modulating the femtosecond laser into a cylindrical lens linear light field;

[0008] The writing platform is used to receive the linear light field of the cylindrical lens and provide a writing space for the fiber Bragg grating.

[0009] In some of the embodiments, the spatial light modulator is a dynamic spatial light modulator.

[0010] In some of the embodiments, the dynamic spatial light modulator is configured to modulate the femtosecond laser into a cylindrical lens linear light field according to a cylindrical wave hologram.

[0011] In some of the embodiments, the writing system further comprises:

[0012] An energy control device disposed at the output side of the femtosecond laser, used for controlling the energy of the femtosecond laser;

[0013] A beam expander, used for expanding the energy-controlled femtosecond laser and transmitting the expanded femtosecond laser to the spatial light modulator;

[0014] The spatial light modulator is arranged at the output side of the beam expander.

[0015] In some of the embodiments, the energy regulation device includes a half-wave plate and a polarization beam splitter;

[0016] The half-wave plate is arranged at the output side of the femtosecond laser, and the polarization beam splitter is arranged at the output side of the half-wave plate.

[0017] In some of the embodiments, the writing system further comprises:

[0018] The objective lens is used to focus the linear light field of the cylindrical lens and transmit the focused linear light field of the cylindrical lens to the writing platform.

[0019] In some of the embodiments, the writing system further comprises:

[0020] An illumination light source disposed on one side of the writing platform;

[0021] An image detection device, used to detect the linear light field of the cylindrical lens;

[0022] A dichroic mirror disposed at the output side of the spatial light modulator, used to transmit the linear light field of the cylindrical lens to the objective lens and transmit the reflected light field of the writing platform to the image detection device;

[0023] The objective lens is disposed on the output side of the dichroic mirror.

[0024] In some of the embodiments, the writing system further comprises:

[0025] A computer electrically connected to the spatial light modulator is used to provide a cylindrical lens hologram to the spatial light modulator.

[0026] In some of the embodiments, the writing system further comprises:

[0027] A reflector disposed at the output side of the energy regulating device, used to adjust the propagation path of the femtosecond laser after energy regulation;

[0028] The beam expander is arranged at the output side of the reflector.

[0029] In some of the embodiments, the writing system further comprises:

[0030] An energy control device disposed at the output side of the femtosecond laser, used for controlling the energy of the femtosecond laser;

[0031] A reflector disposed at the output side of the energy regulating device, used to adjust the propagation path of the femtosecond laser after energy regulation;

[0032] A beam expander provided at the output side of the reflector, for expanding the energy-controlled femtosecond laser beam and transmitting the expanded femtosecond laser beam to the spatial light modulator;

[0033] The spatial light modulator is arranged at the output side of the beam expander;

[0034] An objective lens, used for focusing the linear light field of the cylindrical lens and transmitting the focused linear light field of the cylindrical lens to the writing platform;

[0035] An illumination light source disposed on one side of the writing platform;

[0036] An image detection device, used to detect the linear light field of the cylindrical lens;

[0037] A dichroic mirror disposed at the output side of the spatial light modulator, used to transmit the linear light field of the cylindrical lens to the objective lens and transmit the reflected light field of the writing platform to the image detection device;

[0038] The objective lens is disposed on the output side of the dichroic mirror.

[0039] Compared with the related art, the fiber Bragg grating writing system provided by the utility model modulates the femtosecond laser (focused state) into a cylindrical lens linear light field through a spatial light modulator, and writes the fiber Bragg grating based on the cylindrical lens linear light field. Since the writing is a surface processing process, it has the advantages of high writing quality and high writing efficiency, which solves the problems of low writing quality and low writing efficiency in the current fiber Bragg grating writing system.

[0040] Details of one or more embodiments of the present application are set forth in the following drawings and description to make other features, objects, and advantages of the present application more readily apparent. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a structural diagram of a fiber Bragg grating writing system provided in a specific embodiment of the utility model;

[0042] Figure 2 It is a display diagram of cylindrical wave holograms at different angles in some embodiments of the utility model;

[0043] Figure 3 It is a display diagram of the linear light field of cylindrical lenses at different angles in some embodiments of the utility model;

[0044] Figure 4 It is a display diagram of fiber Bragg gratings at different angles in some embodiments of the utility model;

[0045] Figure 5 It is a transmission spectrum diagram of a fiber Bragg grating in one embodiment of the utility model;

[0046] Figure 6 It is a transmission spectrum diagram of a fiber Bragg grating in another embodiment of the utility model. DETAILED DESCRIPTION

[0047] In order to more clearly understand the purpose, technical solutions and advantages of the present application, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments.

[0048] Unless otherwise defined, the technical terms or scientific terms involved in this application shall have the general meaning understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "a", "a", "the", "these" and the like in this application do not represent quantitative restrictions, and they can be singular or plural. The terms "include", "comprise", "have" and any variants thereof involved in this application are intended to cover non-exclusive inclusions; for example, a process, method and system, product or device comprising a series of steps or modules (units) is not limited to the listed steps or modules (units), but may include unlisted steps or modules (units), or may include other steps or modules (units) inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether directly or indirectly. The "multiple" involved in this application refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, "A and / or B" can mean: A exists alone, A and B exist at the same time, and B exists alone. Usually, the character " / " indicates that the objects associated with each other are in an "or" relationship. The terms "first", "second", "third", etc. involved in this application are only used to distinguish similar objects and do not represent a specific ordering of the objects.

[0049] The utility model also provides a fiber Bragg grating writing system, which is used for the fiber Bragg grating writing system provided by the utility model.

[0050] Figure 11 is a structural diagram of a fiber Bragg grating writing system provided in a specific embodiment of the utility model. Figure 1 The writing system includes a femtosecond laser 1, a spatial light modulator 6 and a writing platform 9.

[0051] Among them, the femtosecond laser 1 is used to emit femtosecond laser; the spatial light modulator 6 is used to modulate the femtosecond laser into a cylindrical lens linear light field; the writing platform 9 is used to receive the cylindrical lens linear light field and provide a writing space for the fiber Bragg grating.

[0052] During the operation of the above-mentioned writing system, the femtosecond laser 1 emits a femtosecond laser to the spatial light modulator 6, and the spatial light modulator 6 modulates the femtosecond laser into a cylindrical lens linear light field and transmits it to the writing platform 9. The fiber Bragg grating is written on the writing platform 9 based on the cylindrical lens linear light field. Specifically, the stripped single-mode optical fiber is first fixed on the writing platform 9, and then the position of the cylindrical lens linear light field in the single-mode optical fiber is adjusted, and finally the writing platform 9 is controlled to drive the single-mode optical fiber to move. In this process, the cylindrical lens linear light field modulates the refractive index of the single-mode optical fiber, thereby forming a fiber Bragg grating.

[0053] The key point in the above scheme is that the spatial light modulator 6 is used to modulate the femtosecond laser into a cylindrical lens linear light field, and the cylindrical lens linear light field is irradiated on the writing platform 9, which can be used to write the fiber Bragg grating. Among them, modulating the femtosecond laser into a cylindrical lens linear light field can make greater use of the energy of the femtosecond laser 1 and improve the energy utilization efficiency. At the same time, writing the fiber Bragg grating based on the cylindrical lens linear light field on the writing platform 9 is a surface processing. Compared with the existing femtosecond laser point-by-point writing system, it will not produce strong cladding mode loss, thereby improving the writing quality of the fiber Bragg grating and the writing efficiency of the fiber Bragg grating.

[0054] In summary, the fiber Bragg grating writing system provided by the utility model mainly modulates the femtosecond laser (focused state) into a cylindrical lens linear light field through the spatial light modulator 6, and writes the fiber Bragg grating based on the cylindrical lens linear light field. Since the writing is a surface processing technology, it has the advantages of high writing quality and high writing efficiency, which solves the problems of low writing quality and low writing efficiency in the current fiber Bragg grating writing system.

[0055] Furthermore, the spatial light modulator 6 adopts a dynamic spatial light modulator (adjustable spatial light modulator), and this type of spatial light modulator 6 can realize different modulations of the femtosecond laser according to different control information input from the outside, thereby outputting different cylindrical lens linear light fields. Among them, the control information of the spatial light modulator 6 can be a cylindrical wave hologram, that is, the dynamic spatial light modulator is configured to modulate the femtosecond laser into a cylindrical lens linear light field according to the cylindrical wave hologram.

[0056] Therefore, in some of the embodiments, the method for modulating the femtosecond laser into a cylindrical lens linear light field includes: modulating the femtosecond laser into a cylindrical lens linear light field according to a cylindrical lens hologram.

[0057] In the above embodiment, the required cylindrical wave hologram can be generated by a computer and loaded into the spatial light modulator 6. At this time, different cylindrical wave holograms can be generated by adjusting the parameters of the cylindrical wave hologram, thereby realizing flexible control of the linear light field of the cylindrical lens, and conveniently writing tilted fiber Bragg gratings of different angles.

[0058] Figure 2 It is a display diagram of cylindrical wave holograms at different angles in some embodiments of the utility model. Figure 3 It is a display diagram of the linear light field of cylindrical lenses at different angles in some embodiments of the utility model. Figure 4 It is a display diagram of fiber Bragg gratings at different angles in some embodiments of the utility model.

[0059] Reference Figure 2 , the tilt angles of the cylindrical wave holograms from left to right are -1°, 4°, 9° and 14° respectively. When the tilt angle of the spatial light modulator 6 is 1°, the cylindrical lens linear light field generated by the spatial light modulator 6 is as follows: Figure 3 See Figure 3 The inclination angles of the cylindrical lens linear light field from left to right are 0°, 5°, 10° and 15° respectively. The final fiber Bragg grating formed by writing is as follows Figure 4 See Figure 4 ,The tilt angles of the fiber Bragg gratings from left to right are 0°, 5°, 10° and 15° respectively.

[0060] Correspondingly, in other embodiments, the spatial light modulator 6 may also be a static spatial light modulator (fixed spatial light modulator) or a modulation element (digital reflective micromirror, cylindrical lens, binary diffraction plate and liquid crystal phase plate). In these embodiments, different cylindrical lens linear light fields can be generated by replacing different spatial light modulators 6, and tilted fiber Bragg gratings of different angles can also be written.

[0061] Furthermore, in addition to the key parts including the femtosecond laser 1, the spatial light modulator 6 and the writing platform 9, the writing system usually also needs to include an energy control device, a beam expander 5 and an objective lens 8.

[0062] The energy control device is arranged on the output side of the femtosecond laser 1, and is used to control the energy of the femtosecond laser; the beam expander 5 is used to expand the femtosecond laser after energy control, and transmit the expanded femtosecond laser to the spatial light modulator 6; the spatial light modulator 6 is arranged on the output side of the beam expander 5; the objective lens 8 is used to focus the linear light field of the cylindrical lens and transmit the focused linear light field of the cylindrical lens to the writing platform 9.

[0063] During the operation of the above-mentioned writing system, the femtosecond laser emitted by the femtosecond laser 1 first passes through the energy control device, then passes through the beam expander 5, and then reaches the spatial light modulator 6. The cylindrical lens linear light field emitted by the spatial light modulator 6 is focused by the objective lens 8 and then transmitted to the writing platform 9.

[0064] In some of the embodiments, the energy control device includes a half-wave plate 2 and a polarization beam splitter 3. The half-wave plate 2 is arranged at the output side of the femtosecond laser 1, and the polarization beam splitter 3 is arranged at the output side of the half-wave plate 2. The femtosecond laser emitted by the femtosecond laser 1 first passes through the half-wave plate 2, then passes through the polarization beam splitter 3, and then is transmitted to the beam expander 5.

[0065] It should be noted that the combination of the half-wave plate 2 and the polarization beam splitter 3 is only a specific form of the energy control device. In other embodiments, the energy control device can also be a gradient filter.

[0066] In order to monitor the writing process, in some embodiments, the writing system also includes an illumination light source 10 arranged on one side of the writing platform 9, an image detection device 12 and a dichroic mirror 7 arranged on the output side of the spatial light modulator, and the objective lens 8 is arranged on the output side of the dichroic mirror 7.

[0067] The image detection device 12 is used to detect the linear light field of the cylindrical lens; the dichroic mirror 7 is used to transmit the linear light field of the cylindrical lens to the objective lens 8 and transmit the reflected light field of the writing platform 9 to the image detection device 12. Among them, the dichroic mirror 7 has the characteristic of only reflecting light of a specific wavelength, that is, when the wavelength of light is within a specific range, it will be reflected by the dichroic mirror, and when the wavelength of light is outside the specific range, it will directly pass through the dichroic mirror. Moreover, the light reflection / projection characteristics of the dichroic mirror 7 are related to its own structure, that is, dichroic mirrors 7 of different structures have different reflection wavelength ranges. In this embodiment, the linear light field of the cylindrical lens and the reflected light field of the writing platform 9 have different wavelengths, so the corresponding reflection / transmission requirements are met by selecting a suitable dichroic mirror 7. Specifically, in one embodiment, the dichroic mirror 7 reflects the linear light field of the cylindrical lens and allows the reflected light field of the writing platform 9 to be transmitted. In another embodiment, the dichroic mirror 7 reflects the reflected light field of the writing platform 9 to be transmitted and allows the linear light field of the cylindrical lens to be transmitted. It should be noted that the dichroic mirror 7 needs to be at an acute angle to the propagation path of the reflected light field of the writing platform 9 or the linear light field of the cylindrical lens rather than being completely perpendicular, such as at an angle of 45°.

[0068] During the operation of the above-mentioned writing system, the illumination light source 10 is turned on, and the cylindrical lens linear light field emitted by the spatial light modulator 6 is irradiated on the dichroic mirror 7, and enters the objective lens 8 after being reflected by the dichroic mirror 7. The cylindrical lens linear light field focused by the objective lens 8 is irradiated on the optical fiber on the writing platform 9, and the light field is reflected and passed through the dichroic mirror 7 again to be collected by the image detection device 12. Among them, a lens 11 can be set between the dichroic mirror 7 and the image detection device 12. The image detection device 12 can use a CCD (Charge Coupled Device).

[0069] In order to control the writing system, the writing system further includes a computer 13. The computer 13 is at least used to control the movement of the writing platform 9, so as to achieve writing of the optical fiber on the writing platform 9.

[0070] In the embodiment where the spatial light modulator 6 adopts a dynamic spatial light modulator (adjustable spatial light modulator 6), the computer 13 is electrically connected to the spatial light modulator 6, and is also used to provide the cylindrical lens hologram to the spatial light modulator 6, that is, the computer 13 generates the cylindrical lens hologram according to the user input and records it in the spatial light modulator 6. At this time, different cylindrical wave holograms can be generated by adjusting the parameters of the cylindrical wave hologram, thereby realizing flexible regulation of the cylindrical lens linear light field, and conveniently writing tilted fiber Bragg gratings of different angles.

[0071] In an embodiment where the writing system further includes an illumination light source 10 , an image detection device 12 and a dichroic mirror 7 arranged on one side of the writing platform 9 , the computer 13 is also used to control the image detection device 12 .

[0072] It should be noted that the specific positional relationship between the various components in the writing system is determined according to the matching relationship of the various components, mainly to ensure that the next component can receive the light emitted by or passing through the previous component. In order to compact the writing system, in some embodiments, the writing system also includes: a reflector 4 arranged on the output side of the energy control device, used to adjust the propagation path of the femtosecond laser after energy control; a beam expander 5 is arranged on the output side of the reflector 4.

[0073] As described above, at least one embodiment of each part of the fiber Bragg grating writing system provided by the present invention has been described. It should be noted that the various parts of the fiber Bragg grating writing system can be combined in different embodiments to form different embodiments of the fiber Bragg grating writing system.

[0074] For example, in a specific overall embodiment, the writing system of the fiber Bragg grating includes a femtosecond laser 1, an energy control device, a reflector 4, a beam expander 5, a spatial light modulator 6, a dichroic mirror 7, an objective lens 8, a writing platform 9, an illumination light source 10, a lens 11, an image detection device 12, and a computer. Among them, the spatial light modulator 6 adopts a dynamic spatial light modulator.

[0075] The femtosecond laser 1 is used to emit femtosecond laser; the spatial light modulator 6 is used to modulate the femtosecond laser into a cylindrical lens linear light field; the writing platform 9 is used to receive the cylindrical lens linear light field and provide a writing space for the fiber Bragg grating. An energy control device is arranged at the output side of the femtosecond laser 1, and is used for energy control of the femtosecond laser; a reflector 4 is arranged at the output side of the energy control device, and is used for adjusting the propagation path of the femtosecond laser after energy control; a beam expander 5 is arranged at the output side of the reflector 4, and is used for beam expansion of the femtosecond laser after energy control, and for transmitting the expanded femtosecond laser to the spatial light modulator 6; the spatial light modulator 6 is arranged at the output side of the beam expander 5; the objective lens 8 is used for focusing the linear light field of the cylindrical lens and transmitting the focused linear light field of the cylindrical lens to the writing platform 9; the illumination light source 10 is arranged at one side of the writing platform 9; the image detection device 12 is used for detecting the linear light field of the cylindrical lens; the dichroic mirror 7 is arranged at the output side of the spatial light modulator 6, and is used for transmitting the linear light field of the cylindrical lens to the objective lens 8 and for transmitting the reflected light field of the writing platform 9 to the image detection device 12.

[0076] During the operation of the above-mentioned writing system, the femtosecond laser emitted by the femtosecond laser 1 first passes through the energy control device, then passes through the beam expander 5, and then reaches the spatial light modulator 6. The spatial light modulator 6 modulates the femtosecond laser into a cylindrical lens linear light field. The cylindrical lens linear light field emitted by the spatial light modulator 6 is irradiated on the dichroic mirror 7, and enters the objective lens 8 after being reflected by the dichroic mirror 7. The cylindrical lens linear light field focused by the objective lens 8 is irradiated into the optical fiber on the writing platform 9. After the light field is reflected, it passes through the dichroic mirror 7 again and is collected by the image detection device 12. In this process, the cylindrical lens linear light field modulates the refractive index of the single-mode optical fiber, thereby forming a fiber Bragg grating. The computer is used to control the writing platform 9, the image detection device 12 and the spatial light modulator 6.

[0077] In combination with the fiber Bragg grating writing system provided in the above specific embodiments, two embodiments of the fiber Bragg grating writing method are introduced as follows (the tilt angle of the spatial light modulator 6 is 1°).

[0078] In one embodiment, a method for writing a fiber Bragg grating includes:

[0079] 1. Sample preparation: The material of the sample is single-mode optical fiber. A refractive index matching liquid with a refractive index of 1.47 is dropped on a glass slide and then fixed on the writing platform 9.

[0080] 2. Sample processing: irradiate the femtosecond laser on the spatial light modulator 6, load the -1° cylindrical lens hologram on the spatial light modulator 6, adjust the processing energy to 137uw, and set the frequency to 100Hz through the laser control software on the computer.

[0081] 3. Fix the stripped single-mode optical fiber on the writing platform 9, turn on the illumination light source 10, adjust the position of the cylindrical lens linear light field in the single-mode optical fiber, use a computer to control the writing platform 9 to move on the plane at a speed of 0.107 mm / s, and complete the processing of a fiber Bragg grating with a length of 6 mm under a 60x objective lens 8.

[0082] After processing, the transmission spectrum of the grating can be obtained through a spectrometer and a broadband light source, such as Figure 5 As shown. Fiber Bragg gratings have important application value in the field of optical fiber communications. They can be used as wavelength division multiplexers, gain flatteners of optical fiber amplifiers, dispersion compensators, uplink and downlink of all-optical networks, wavelength routing, optical switching, etc. Since the method in this case does not require point-by-point scanning, and only requires linear light field exposure to complete the processing, this method is more flexible, efficient and fast than traditional methods.

[0083] In another embodiment, a method for writing a fiber Bragg grating includes:

[0084] 1. Sample preparation: The material of the sample is single-mode optical fiber. A refractive index matching liquid with a refractive index of 1.47 is dropped on a glass slide and then fixed on a moving platform.

[0085] 2. Sample processing: irradiate the femtosecond laser on the spatial light modulator 6, load the 9° cylindrical lens hologram on the spatial light modulator 6, adjust the processing energy to 137uw, and set the frequency to 100Hz through the laser control software on the computer.

[0086] 3. Fix the stripped single-mode optical fiber on the writing platform 9, turn on the illumination light source 10, adjust the position of the cylindrical lens linear light field in the single-mode optical fiber, use a computer to control the writing platform 9 to move on the plane at a speed of 0.107 mm / s, and complete the processing of a 10° inclined fiber Bragg grating with a length of 6 mm under a 60x objective lens 8.

[0087] After processing, the transmission spectrum of the grating can be obtained through a spectrometer and a broadband light source, such as Figure 6 As shown. In the field of optical fiber sensing, tilted fiber Bragg gratings have been widely used in the measurement of parameters such as bending, temperature, vibration, and refractive index. At the same time, it has important application value in the field of optical fiber communication. Tilted fiber Bragg gratings can be used as gain flatteners, dispersion compensation devices, fiber filters, and wavelength division multiplexers of erbium-doped fiber amplifiers. Since the method in this case does not require point-by-point scanning, the processing can be completed only through linear light field exposure, so the processing of this method is more flexible, efficient, and fast than the traditional method.

[0088] It should be understood that the specific embodiments described herein are only used to explain the application, rather than to limit it. Based on the embodiments provided in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of this application.

[0089] Obviously, the drawings are only some examples or embodiments of the present application. For ordinary technicians in the field, the present application can also be applied to other similar situations based on these drawings without creative work. In addition, it is understandable that although the work done in this development process may be complicated and lengthy, for ordinary technicians in the field, certain changes in design, manufacturing or production based on the technical content disclosed in this application are only conventional technical means and should not be regarded as insufficient content disclosed in this application.

Claims

1. A fiber Bragg grating writing system, characterized in that: The writing system comprises: A femtosecond laser, used for emitting femtosecond laser; A spatial light modulator, used for modulating the femtosecond laser into a cylindrical lens linear light field; The writing platform is used to receive the linear light field of the cylindrical lens and provide a writing space for the fiber Bragg grating.

2. The fiber Bragg grating writing system according to claim 1, characterized in that: The spatial light modulator is a dynamic spatial light modulator.

3. The fiber Bragg grating writing system according to claim 2, characterized in that: The dynamic spatial light modulator is configured to modulate the femtosecond laser into a cylindrical lens linear light field according to a cylindrical wave hologram.

4. The fiber Bragg grating writing system according to claim 1, characterized in that: The writing system also includes: An energy control device disposed at the output side of the femtosecond laser, used for controlling the energy of the femtosecond laser; A beam expander, used for expanding the energy-controlled femtosecond laser and transmitting the expanded femtosecond laser to the spatial light modulator; The spatial light modulator is arranged at the output side of the beam expander.

5. The fiber Bragg grating writing system according to claim 4, characterized in that: The energy regulation device includes a half-wave plate and a polarization beam splitter; The half-wave plate is arranged at the output side of the femtosecond laser, and the polarization beam splitter is arranged at the output side of the half-wave plate.

6. The fiber Bragg grating writing system according to claim 1, characterized in that: The writing system also includes: The objective lens is used to focus the linear light field of the cylindrical lens and transmit the focused linear light field of the cylindrical lens to the writing platform.

7. The fiber Bragg grating writing system according to claim 6, characterized in that: The writing system also includes: An illumination light source disposed on one side of the writing platform; An image detection device, used to detect the linear light field of the cylindrical lens; The dichroic mirror arranged at the output side of the spatial light modulator is used to transmit the linear light field of the cylindrical lens to the objective lens and transmit the reflected light field of the writing platform to the image detection device.

8. The fiber Bragg grating writing system according to claim 1, characterized in that: The writing system also includes: A computer electrically connected to the spatial light modulator is used to provide a cylindrical lens hologram to the spatial light modulator.

9. The fiber Bragg grating writing system according to claim 4, characterized in that: The writing system also includes: A reflector disposed at the output side of the energy regulating device, used to adjust the propagation path of the femtosecond laser after energy regulation; The beam expander is arranged at the output side of the reflector.

10. The fiber Bragg grating writing system according to claim 1, characterized in that: The writing system also includes: An energy control device disposed at the output side of the femtosecond laser, used for controlling the energy of the femtosecond laser; A reflector disposed at the output side of the energy regulating device, used to adjust the propagation path of the femtosecond laser after energy regulation; A beam expander provided at the output side of the reflector, for expanding the energy-controlled femtosecond laser beam and transmitting the expanded femtosecond laser beam to the spatial light modulator; The spatial light modulator is arranged at the output side of the beam expander; An objective lens, used for focusing the linear light field of the cylindrical lens and transmitting the focused linear light field of the cylindrical lens to the writing platform; An illumination light source disposed on one side of the writing platform; An image detection device, used to detect the linear light field of the cylindrical lens; The dichroic mirror arranged at the output side of the spatial light modulator is used to transmit the linear light field of the cylindrical lens to the objective lens and transmit the reflected light field of the writing platform to the image detection device.

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