Distributed fiber grating writing device and writing method based on roll-to-roll

Abstract

The present invention belongs to the field of optical fiber writing, and specifically relates to a distributed optical fiber grating writing device and writing method based on roll-to-roll, wherein the device includes an optical fiber transmission mechanism, a femtosecond laser optical fiber writing mechanism and an online monitoring mechanism; the optical fiber transmission mechanism includes an unwinding roller, an optical fiber guiding mechanism and a winding roller arranged in sequence, and the optical fiber guiding mechanism is used to move the optical fiber in a straight line direction in the writing area; the online monitoring mechanism includes a light source and a spectrometer, the light source rotates synchronously with the unwinding roller and is connected to the head end of the optical fiber in the unwinding roller, and the spectrometer rotates synchronously with the winding roller and is connected to the tail end of the optical fiber in the winding roller. The present invention arranges a light source to rotate synchronously on the unwinding roller, arranges a spectrometer to rotate synchronously on the winding roller, injects optical information into the optical fiber through the light source, receives optical signals through the spectrometer, and feeds back whether the operation of writing is normal, thereby monitoring the writing status in real time.

Description

Technical Field

[0001] The invention belongs to the field of optical fiber writing, and in particular relates to a distributed optical fiber grating writing device and a writing method based on roll-to-roll. Background Art

[0002] Distributed fiber grating array is an advanced sensing technology. It plays an important role in the field of sensing by utilizing the characteristics of fiber Bragg grating (FBG). Distributed fiber grating array technology is widely used in the detection of physical quantities such as temperature, strain and vibration in harsh environments due to its high sensitivity, anti-electromagnetic interference, small size and easy multiplexing. In the field of laser, distributed fiber grating array technology also shows great potential. Through the femtosecond laser automatic preparation technology, high-efficiency automatic preparation of large-scale series / parallel integrated fiber grating (including weak reflection points) arrays at the kilometer level and roll-to-roll can be achieved in single-core and multi-core optical fibers.

[0003] At present, there are several main ways to prepare distributed fiber grating arrays: distributed fiber grating array writing technology based on online drawing tower phase mask, roll-to-roll distributed fiber grating array writing system based on excimer laser, roll-to-roll distributed fiber grating array writing system based on femtosecond laser direct writing, etc. Online drawing tower preparation technology is a process that integrates fiber drawing and grating writing processes. After heating the glass preform, the fiber is stretched and formed. At the same time, the fiber is grating-written by excimer laser and phase mask. The drawing speed is controlled by pulse selector, and the FBGs in the fiber can be accurately located. However, this system is bulky, expensive, and requires high coordination of various components of the system, which restricts the popularization of grating array preparation. The roll-to-roll distributed fiber grating array writing system based on excimer laser reduces the size of the device to the laboratory level. It mainly uses ultraviolet light generated by excimer laser to irradiate the optical fiber, and forms a periodic refractive index change in the optical fiber by interference or direct writing, thereby forming a fiber grating. However, due to the characteristics of excimer lasers, the coating of the optical fiber needs to be stripped before the preparation of the fiber grating array, which greatly reduces the tensile strength of the optical fiber, making it easy to break and affecting its subsequent use. At the same time, the optical fiber needs to be treated with hydrogen before grating writing, which increases the time cost and safety hazards. Excimer lasers also involve toxic gases and various inflation operations, which further increase the operating cost of excimer lasers. The roll-to-roll distributed fiber grating array writing system based on femtosecond laser direct writing utilizes the nonlinear process of femtosecond laser and transparent medium to achieve direct writing with coating layer. The grating period, length, angle and other parameters can be flexibly controlled by moving the optical fiber through a high-precision displacement stage. However, the femtosecond laser direct writing method requires that the writing beam must be focused to a very dense point, which requires a complex focusing optical system. This high-precision focusing requirement limits the writing speed. At the same time, the laser pulse of femtosecond laser direct writing can only write a very small point on the optical fiber each time, and it takes a long time to prepare the entire fiber grating array. At the same time, the stability and precision of the equipment are required to be high. Any slight vibration or position deviation of the equipment may affect the writing quality of the grating, which in turn leads to poor repeatability and consistency of the optical fiber. The high-precision control equipment in the system is expensive, such as the air guide electric platform that controls the movement of the optical fiber, making the equipment cost of the entire system extremely high.

[0004] In addition, in order to improve the writing efficiency, more and more writing devices are currently developing in the direction of automatic loading. For example, the Chinese patent application: "CN113655562A-A femtosecond laser writing fiber grating automatic loading device and writing processing steps" designs a fiber grating automatic loading device for automatic loading. Then, after the automatic loading device is deployed, it is difficult to monitor the writing of the optical fiber in real time and it is difficult to ensure the quality of the optical fiber writing. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a roll-to-roll distributed fiber grating writing device and writing method which can monitor the writing quality in real time.

[0006] The present invention provides a roll-to-roll distributed fiber grating writing device, comprising a fiber transmission mechanism, a femtosecond laser fiber writing mechanism and an online monitoring mechanism;

[0007] The optical fiber transmission mechanism comprises an unwinding roller, an optical fiber guiding mechanism and a winding roller which are arranged in sequence, and the optical fiber guiding mechanism is used to move the optical fiber in a straight line direction in the writing area;

[0008] The femtosecond laser fiber writing mechanism is used to write to the optical fiber in the writing area using a femtosecond laser phase mask method;

[0009] The online monitoring mechanism includes a light source and a spectrometer. The light source or spectrometer rotates synchronously with the unwinding roller and is connected to the head end of the optical fiber in the unwinding roller. The spectrometer or light source rotates synchronously with the winding roller and is connected to the tail end of the optical fiber in the winding roller.

[0010] Furthermore, the unwinding roller and the winding roller each include a roller body, a roller surface of the roller body is provided with an optical fiber inlet, a side wall of the roller body is provided with an optical fiber outlet, and the optical fiber inlet is connected to the optical fiber outlet;

[0011] The head end of the optical fiber is connected to a light source or a spectrometer through the optical fiber outlet of the unwinding roller;

[0012] The tail end of the optical fiber is connected to a spectrometer or a light source through the optical fiber outlet of the winding roller.

[0013] Furthermore, the light source is fixedly arranged on the side wall of the roller body of the unwinding roller or the winding roller;

[0014] The spectrometer is fixedly arranged on the roller body side wall of the winding roller or the unwinding roller.

[0015] Furthermore, the online monitoring mechanism also includes a light source roller and a spectrometer roller;

[0016] The light source roller is coaxial with the unwinding roller or the winding roller and rotates synchronously, the light source is fixedly arranged on the light source roller, and the optical fiber connection end of the light source is coaxial with the optical fiber outlet of the unwinding roller or the winding roller;

[0017] The spectrometer roller is coaxial with the winding roller or the unwinding roller and rotates synchronously, the spectrometer is fixedly arranged on the spectrometer roller, and the optical fiber connection end of the spectrometer is coaxial with the optical fiber outlet of the winding roller or the unwinding roller.

[0018] Furthermore, the optical fiber guiding mechanism comprises two transmission inserts arranged in sequence;

[0019] The transmission insert core includes an optical fiber guide hole, an optical fiber transition hole and an optical fiber guide hole arranged in sequence;

[0020] The size of the optical fiber guide hole is adapted to the optical fiber, the size of the optical fiber guide hole is larger than the size of the optical fiber guide hole, and the optical fiber transition hole is a tapered hole, one end of which transitions to the optical fiber guide hole and the other end of which transitions to the optical fiber guide hole;

[0021] The optical fiber guide holes of the two transmission inserts are both arranged downstream in the moving direction of the optical fiber, and the position between the two transmission inserts is the writing area.

[0022] Furthermore, the two transmission inserts are arranged on a six-dimensional high-precision displacement platform.

[0023] Furthermore, a guide wheel is provided between the transmission insert located upstream and the unwinding roller;

[0024] A tension regulator and a cable arrangement mechanism are provided between the transmission insert located downstream and the winding roller;

[0025] The cable arrangement mechanism includes a linear module and a guide block arranged on the output end of the linear module. The optical fiber enters the winding roller after passing through the guide block, so that the optical fiber is arranged flatly and orderly on the winding roller.

[0026] Furthermore, the femtosecond laser fiber writing mechanism includes a femtosecond laser, a beam shaping mechanism, an electronic shutter, a galvanometer, a focusing lens and a phase mask which are arranged in sequence.

[0027] Furthermore, the beam shaping mechanism includes a collimating lens, a pinhole aperture and a beam expander lens which are arranged in sequence.

[0028] The present invention also provides a roll-to-roll distributed fiber Bragg grating writing method, using the roll-to-roll distributed fiber Bragg grating writing device, comprising the following steps:

[0029] S1, the femtosecond laser fiber writing mechanism writes the optical fiber in the writing area;

[0030] S2, after completing S1, the unwinding roller and the winding roller rotate synchronously, so that the upstream of the optical fiber where the writing is completed enters the writing area, and enters step S1;

[0031] Cycle S1 and S2 to complete the axial writing of the optical fiber. During the writing process, the light source transmits light from one end of the optical fiber to the other end. The spectrometer at the other end receives the optical signal in real time and determines the writing state according to the state of the received optical signal.

[0032] The beneficial effect of the present invention is that the present invention sets a light source or a spectrometer on the unwinding roller for synchronous rotation, and sets a spectrometer or a light source on the winding roller for synchronous rotation, injects light information into the optical fiber through the light source, and receives light signals through the spectrometer to feedback whether the writing operation is normal, thereby monitoring the writing status in real time, and providing data support for adjusting the optical fiber transmission mechanism and the femtosecond laser optical fiber writing mechanism. During the entire process of monitoring the writing status, the online monitoring mechanism can adapt the position and angle of the head and tail ends of the optical fiber, so that the light source and the spectrometer are relatively statically connected to the end of the optical fiber, avoiding torsional stress between the end of the optical fiber and the light source and the spectrometer during the rotation of the unwinding roller and the winding roller, and realizing the monitoring of the optical fiber during rotation. The problem that online monitoring cannot be achieved in the current optical fiber roll-to-roll continuous writing device is solved.

[0033] In addition, the present invention adopts a femtosecond laser fiber writing mechanism. On the one hand, by utilizing the unique properties of the femtosecond laser, the fiber grating preparation can be completed through the coating layer of the optical fiber; on the other hand, by utilizing the advantages of the femtosecond laser phase mask method system, which has reliable stability and good repeatability, the consistency of the distributed fiber grating array is improved, and the grating preparation efficiency is also improved. In addition, by cooperating with the fiber transmission mechanism, the transmission of the optical fiber can be realized, and the fiber transmission and exposure time are controlled by the controller, and finally the automatic writing of the fiber grating distributed array is realized. That is, the femtosecond laser fiber writing mechanism adopts the technology of combining the femtosecond laser and the phase mask, so that the distributed fiber grating writing device based on roll-to-roll has reliable stability, good repeatability and will have the advantages of high efficiency and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Attached Figure 1 It is a front view of a roll-to-roll distributed fiber Bragg grating writing device;

[0035] Attached Figure 2 A top view of a roll-to-roll distributed fiber Bragg grating writing device;

[0036] Attached Figure 3 It is a local schematic diagram of the writing area in a roll-to-roll distributed fiber Bragg grating writing device;

[0037] Attached Figure 4 It is a schematic diagram of the focusing process of the laser of the roll-to-roll distributed fiber Bragg grating writing device after passing through the focusing lens;

[0038] Attached Figure 5 It is a schematic diagram of the structure of an unwinding roller or a winding roller in a roll-to-roll distributed fiber Bragg grating writing device;

[0039] Attached Figure 6It is a schematic diagram of the structure of a light source roller or a spectrometer roller in a roll-to-roll distributed fiber Bragg grating writing device;

[0040] Attached Figure 7 A schematic diagram of the connection between a light source roller or a spectrometer roller and an unwinding roller or a winding roller in a roll-to-roll distributed fiber Bragg grating writing device;

[0041] Attached Figure 8 It is a front cross-sectional view of a transmission insert in a roll-to-roll distributed fiber Bragg grating writing device;

[0042] Attached Fig. 9 It is a front view of a vertical mounting plate in a roll-to-roll distributed fiber Bragg grating writing device;

[0043] Attached Fig.10 It is a side view of a vertical mounting plate in a roll-to-roll distributed fiber Bragg grating writing device;

[0044] Attached Fig.11 A top view of a base in a roll-to-roll distributed fiber Bragg grating writing device;

[0045] Attached Fig.12 It is a structural schematic diagram of a wiring mechanism in a roll-to-roll distributed fiber Bragg grating writing device;

[0046] Attached Fig.13 This is a schematic diagram of the structure of the guide block in a roll-to-roll distributed fiber Bragg grating writing device.

[0047] In the figure, 1-fiber transmission mechanism; 11-unwinding roller; 12-winding roller; 13-transmission ferrule; 131-fiber guide hole; 132-fiber transition hole; 133-fiber guide hole; 14-six-dimensional high-precision displacement platform; 15-transmission ferrule mounting piece; 151-base; 1511-six-dimensional displacement platform positioning hole; 1512-vertical mounting plate positioning hole; 152-vertical mounting plate; 1521-mounting seam; 1522-ferrule clamping and fixing hole; 1523-fastening hole; 1524-base mounting hole; 16-guide wheel; 17-tension regulator; 18-cable arrangement mechanism; 181-linear module; 18 2-guide block; 1821-conical through hole; 19-roller; 110-optical fiber entrance; 111-optical fiber exit; 2-femtosecond laser fiber writing mechanism; 21-femtosecond laser; 22-collimating lens; 23-pinhole aperture; 24-beam expanding lens; 25-reflector I; 26-reflector II; 27-electronic shutter; 28-galvanometer; 29-focusing lens; 210-phase mask; 3-online monitoring mechanism; 31-light source; 32-spectrometer; 33-light source roller; 34-spectrometer roller; 4-controller; 5-CCD sensor; 6-optical fiber; 61-core; 62-cladding; 63-coating. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0050] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0051] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0052] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0053] As attached Figure 1 -Attached Fig.13As shown, the present invention provides a distributed fiber Bragg grating writing device based on roll-to-roll, comprising a fiber transmission mechanism 1, a femtosecond laser fiber writing mechanism 2 and an online monitoring mechanism 3, wherein the fiber transmission mechanism 1 is used to achieve stable transmission of the optical fiber 6, so that the femtosecond laser fiber writing mechanism 2 sequentially performs writing operations on the axial direction of the optical fiber 6, the femtosecond laser fiber writing mechanism 2 is used to write on the optical fiber 6, and the online monitoring mechanism 3 is used to detect the writing state of the optical fiber 6 in real time, and adjust the fiber transmission mechanism 1 and the femtosecond laser fiber writing mechanism 2 in real time according to the monitoring result to ensure normal writing;

[0054] The optical fiber transmission mechanism 1 includes an unwinding roller 11, an optical fiber guiding mechanism and a winding roller 12 which are arranged in sequence. An extra-long optical fiber 6 is wound on the unwinding roller 11, and is wound on the winding roller 12 after passing through the optical fiber guiding mechanism. The unwinding roller 11 and the winding roller 12 rotate synchronously, so that the optical fiber 6 on the unwinding roller 11 can be transferred to the winding roller 12. The optical fiber guiding mechanism is used to move the optical fiber 6 in a straight line within the writing area, that is, the optical fiber guiding mechanism enables the optical fiber 6 to move in a straight line within the writing area, so as to avoid the optical fiber 6 from being offset when being transferred between the unwinding roller 11 and the winding roller 12, so that the femtosecond laser optical fiber writing mechanism 2 can accurately write on the optical fiber 6.

[0055] The femtosecond laser fiber writing mechanism 2 is used to write to the optical fiber 6 in the writing area by using a femtosecond laser phase mask method. When the femtosecond laser fiber writing mechanism 2 writes to the optical fiber 6, the optical fiber transmission mechanism 1 stops working, and the optical fiber 6 remains stationary. The femtosecond laser fiber writing mechanism 2 writes to the optical fiber 6 in the writing area. After the writing of this part of the optical fiber 6 is completed, the optical fiber transmission mechanism 1 continues to work, so that the optical fiber 6 moves forward a certain distance, so that the written part of the optical fiber 6 leaves the writing area, and the downstream unwritten part enters the writing area, and enters the next round of writing operation;

[0056] The online monitoring mechanism 3 includes a light source 31 and a spectrometer 32;

[0057] The light source 31 rotates synchronously with the unwinding roller 11 and is connected to the head end of the optical fiber 6 in the unwinding roller 11. The light source 31 is used to inject light into the entire optical fiber 6 through the head end of the optical fiber 6. The spectrometer 32 rotates synchronously with the winding roller 12 and is connected to the tail end of the optical fiber 6 in the winding roller 12. The spectrometer 32 is used to receive the light signal emitted by the light source 31 at the tail end of the optical fiber 6.

[0058] Alternatively, the light source 31 rotates synchronously with the winding roller 12 and is connected to the tail end of the optical fiber 6 in the winding roller 12, and the light source 31 is used to inject light into the entire optical fiber 6 through the tail end of the optical fiber 6, and the spectrometer 32 rotates synchronously with the unwinding roller 11 and is connected to the head end of the optical fiber 6 in the unwinding roller 11, and the spectrometer 32 is used to receive the light signal emitted by the light source 31 at the head end of the optical fiber 6;

[0059] The spectrometer 32 can accurately measure and distinguish tiny wavelength differences according to the writing situation, and can quickly measure dynamically changing optical signals, provide feedback on whether the writing operation is normal, and monitor the writing status in real time.

[0060] The present invention synchronously rotates by setting a light source 31 or a spectrometer 32 on the unwinding roller 11, and synchronously rotates by setting a spectrometer 32 or a light source 31 on the winding roller 12, injecting light information into the optical fiber 6 through the light source 31, and receiving light signals through the spectrometer 32, and feedback whether the writing operation is normal, thereby monitoring the writing state in real time, and providing data support for adjusting the optical fiber transmission mechanism 1 and the femtosecond laser optical fiber writing mechanism 2. During the entire process of monitoring the writing state, the online monitoring mechanism 3 can adapt the position and angle of the head end and the tail end of the optical fiber 6, so that the light source 31 and the spectrometer 32 are relatively statically connected to the end of the optical fiber 6, avoiding the torsional stress between the end of the optical fiber 6 and the light source 31 and the spectrometer 32 during the rotation of the unwinding roller 11 and the winding roller 12, and realizing the monitoring of the optical fiber 6 during the rotation process. The problem that online monitoring cannot be achieved in the current roll-to-roll continuous writing device of the optical fiber 6 is solved.

[0061] In addition, the present invention adopts a femtosecond laser fiber writing mechanism 2. On the one hand, by utilizing the unique properties of the femtosecond laser, the fiber grating preparation can be completed through the coating layer 63 of the optical fiber 6; on the other hand, by utilizing the advantages of the femtosecond laser phase mask method system, the stability is reliable and the repeatability is good, which improves the consistency of the distributed fiber grating array and the grating preparation efficiency. In addition, by cooperating with the optical fiber transmission mechanism 1, the transmission of the optical fiber 6 can be realized, and the transmission and exposure time of the optical fiber 6 can be controlled by the controller 4, and finally the automatic writing of the fiber grating distributed array is realized. That is, the femtosecond laser fiber writing mechanism 2 adopts the technology of combining the femtosecond laser 21 with the phase mask 210, so that the distributed fiber grating writing device based on roll-to-roll has reliable stability, good repeatability and will have the advantages of high efficiency and low cost.

[0062] In one embodiment, the unwinding roller 11 and the winding roller 12 have the same structure. Both the unwinding roller 11 and the winding roller 12 include a roller body 19. A fiber entrance 110 is provided on the roller surface of the roller body 19. A fiber exit 111 is provided on the side wall of the roller body 19. The fiber entrance 110 is connected to the fiber exit 111. Preferably, the fiber entrance 110 and the fiber exit 111 are connected holes arranged in an L shape. Preferably, the fiber exit 111 is coaxial with the roller body 19. Preferably, the fiber entrance 110 is provided on one side of the roller surface so that the head and tail ends of the optical fiber 6 are wound around the side of the roller body 19.

[0063] The head end of the optical fiber 6 is connected to the light source 31 through the optical fiber outlet 111 of the unwinding roller 11, that is, the head end of the optical fiber 6 passes through the optical fiber inlet 110 and the optical fiber outlet 111 on the unwinding roller 11 and then is connected to the light source 31, and the tail end of the optical fiber 6 is connected to the spectrometer 32 through the optical fiber outlet 111 of the winding roller 12, that is, the tail end of the optical fiber 6 passes through the optical fiber inlet 110 and the optical fiber outlet 111 on the winding roller 12 and then is connected to the spectrometer 32;

[0064] Alternatively, the head end of the optical fiber 6 is connected to the spectrometer 32 through the optical fiber outlet 111 of the unwinding roller 11, that is, the head end of the optical fiber 6 passes through the optical fiber entrance 110 and the optical fiber outlet 111 on the unwinding roller 11 and is connected to the spectrometer 32, and the tail end of the optical fiber 6 is connected to the light source 31 through the optical fiber outlet 111 of the winding roller 12, that is, the tail end of the optical fiber 6 passes through the optical fiber entrance 110 and the optical fiber outlet 111 on the winding roller 12 and is connected to the light source 31.

[0065] In this embodiment, by arranging the fiber entrance 110 on the roller body 19 of the unwinding roller 11 and the winding roller 12, and providing the fiber exit 111 connected to the fiber entrance 110 on the side wall of the roller body 19, it is convenient for the end of the optical fiber 6 to be led out parallel to the axial direction of the unwinding roller 11 and the winding roller 12 through the fiber entrance 110 and the fiber exit 111, and then relatively statically connected with the light source 31 and the spectrometer 32, eliminating the angular rotation of the optical fiber 6. In addition, by introducing the end of the optical fiber 6 into the fiber entrance 110, the stability of the end of the optical fiber 6 on the roller body 19 can be ensured, and the orderliness of the winding can be improved.

[0066] In one embodiment, the light source 31 is fixedly disposed on the side wall of the roller body 19 of the unwinding roller 11, and the spectrometer 32 is fixedly disposed on the side wall of the roller body 19 of the winding roller 12;

[0067] Alternatively, the light source 31 is fixedly disposed on the side wall of the roller body 19 of the winding roller 12 , and the spectrometer 32 is fixedly disposed on the side wall of the roller body 19 of the unwinding roller 11 .

[0068] In this embodiment, the light source 31 and the spectrometer 32 are directly fixed to the roller body 19, which can ensure the synchronous rotation of the light source 31, the spectrometer 32 and the roller body 19, thereby improving the accuracy and reliability of monitoring.

[0069] In another embodiment, the online monitoring mechanism 3 further includes a light source roller 33 and a spectrometer roller 34;

[0070] The light source roller 33 is coaxial with the unwinding roller 11 and rotates synchronously. The light source 31 is fixedly arranged on the light source roller 33. Preferably, the optical fiber connection end of the light source 31 is coaxial with the optical fiber outlet 111 of the unwinding roller 11, so that the optical fiber 6 can be directly connected to the light source 31 after being led out. In other embodiments, refer to the attached Figure 7 The optical fiber connection end of the light source 31 and the optical fiber outlet 111 of the unwinding roller 11 may also be coaxial, and the light source 31 may be arranged on the wheel surface of the light source roller 33 to simplify the installation difficulty of the light source 31. The spectrometer roller 34 is coaxial with the winding roller 12 and rotates synchronously. The spectrometer 32 is fixedly arranged on the spectrometer roller 34. Preferably, the optical fiber connection end of the spectrometer 32 is coaxial with the optical fiber outlet 111 of the winding roller 12, so that the optical fiber 6 can be directly connected to the spectrometer 32 after being led out. In other embodiments, refer to the attached Figure 7 The optical fiber connection end of the spectrometer 32 and the optical fiber outlet 111 of the winding roller 12 may also be not coaxial, and the spectrometer 32 may be arranged on the wheel surface of the spectrometer roller 34 to simplify the installation difficulty of the spectrometer 32;

[0071] Alternatively, the light source roller 33 is coaxial with the winding roller 12 and rotates synchronously, the light source 31 is fixedly set on the light source roller 33, preferably, the optical fiber connection end of the light source 31 is coaxial with the optical fiber outlet 111 of the winding roller 12, the spectrometer roller 34 is coaxial with the unwinding roller 11 and rotates synchronously, the spectrometer 32 is fixedly set on the spectrometer roller 34, preferably, the optical fiber connection end of the spectrometer 32 is coaxial with the optical fiber outlet 111 of the unwinding roller 11.

[0072] In this embodiment, a light source roller 33 and a spectrometer roller 34 are added to install the light source 31 and the spectrometer 32 respectively, so that the light source 31 and the spectrometer 32 are independent of the unwinding roller 11 and the winding roller 12, thereby facilitating the replacement of the unwinding roller 11 and the winding roller 12. After one long optical fiber 6 is engraved, the next long optical fiber 6 can be engraved by replacing the unwinding roller 11 and the winding roller 12.

[0073] In one embodiment, the optical fiber guiding mechanism includes two transmission inserts 13 arranged in sequence;

[0074] The transmission insert 13 includes a fiber guide hole 131, a fiber transition hole 132 and a fiber guide hole 133 arranged in sequence;

[0075] The size of the optical fiber guide hole 133 is adapted to the optical fiber 6, the size of the optical fiber guide hole 131 is larger than the size of the optical fiber guide hole 133, and the optical fiber transition hole 132 is a tapered hole, one end of which transitions to the optical fiber guide hole 133, and the other end of which transitions to the optical fiber guide hole 133, that is, the size of the large end of the tapered hole is consistent with the size of the optical fiber guide hole 133, and the size of the small end is consistent with the size of the optical fiber guide hole 133;

[0076] The optical fiber guide holes 133 of the two transmission cores 13 are both arranged downstream in the moving direction of the optical fiber 6 , and the position between the two transmission cores 13 is a writing area.

[0077] In this embodiment, the optical fiber 6 passes through two transmission inserts 13, which can ensure that the optical fiber 6 in the writing area can only move in a straight line, wherein the optical fiber guide hole 131 is used to guide the optical fiber 6 to insert into the transmission insert 13, and the optical fiber guide hole 133 is used to clamp the optical fiber 6, so that the moving direction of the optical fiber 6 remains constant, and the optical fiber transition hole 132 facilitates the optical fiber 6 to enter the optical fiber guide hole 133 from the optical fiber guide hole 131, reduces the stress concentration of the optical fiber 6 when passing through the transmission insert 13, and prevents the optical fiber 6 from being damaged or broken due to excessive local pressure. Preferably, the slope of the optical fiber transition hole 132 is 60°.

[0078] In one of the embodiments, the two transmission inserts 13 are arranged on a six-dimensional high-precision displacement platform 14. The six-dimensional high-precision displacement platform 14 fine-tunes the positions and angles of the two transmission inserts 13 to achieve detailed fine-tuning of the positions and angles of the writing area, thereby facilitating the alignment of the femtosecond laser fiber writing mechanism 2 and the optical fiber 6 and improving the writing effect.

[0079] In one of the preferred embodiments, the transmission insert 13 is set on the six-dimensional high-precision displacement platform 14 through the transmission insert mounting member 15. The transmission insert mounting member 15 includes a base 151 and a vertical mounting plate 152. The base 151 is used to connect the six-dimensional high-precision displacement platform 14 and the vertical mounting plate 152, and the vertical mounting plate 152 is used to install the transmission insert 13.

[0080] Specifically, a six-dimensional displacement platform positioning hole 1511 is provided on the base 151, and the six-dimensional displacement platform positioning hole 1511 can be used to accurately and stably match the base 151 on the six-dimensional high-precision displacement platform 14 through fasteners. A vertical mounting plate positioning hole 1512 is also provided on the base 151, and a base mounting hole 1524 is provided on the vertical mounting plate 152. By assembling fasteners on the vertical mounting plate positioning hole 1512 and the base mounting hole 1524, high-precision matching of the vertical mounting plate 152 and the base 151 is achieved, thereby improving the installation accuracy of the transmission plug 13. The vertical mounting plate 152 is provided with a mounting slit 1521, and ferrule clamping and fixing holes 1522 and fastening holes 1523 are correspondingly provided on both sides of the mounting slit 1521. The outer wall of the transmission ferrule 13 is embedded in the ferrule clamping and fixing holes 1522, and the fastening holes 1523 are used to install fasteners, so that the mounting slits 1521 are brought closer to each other, so that the ferrule clamping and fixing holes 1522 clamp and fix the transmission ferrule 13, providing stable, reliable and high-position fixation of the transmission ferrule 13. Preferably, a plurality of vertical mounting plate positioning holes 1512 are provided along the length direction, so that the mounting position of the vertical mounting plate 152 can be adjusted, thereby finely controlling the tension of the optical fiber 6 during the transmission process.

[0081] In one embodiment, a guide wheel 16 is provided between the upstream transmission plug 13 and the unwinding roller 11, and a plurality of guide wheels 16 may be provided, so as to make the optical fiber 6 coaxial with the transmission plug 13 before entering the upstream transmission plug 13, thereby reducing the squeezing force between the optical fiber 6 and the upstream transmission plug 13;

[0082] A tension regulator 17 and a cable arrangement mechanism 18 are provided between the transmission plug 13 located downstream and the winding roller 12. The tension regulator 17 is used to ensure that the optical fiber 6 is coaxial with the transmission plug 13 when leaving the downstream transmission plug 13, thereby reducing the squeezing force between the optical fiber 6 and the downstream transmission plug 13. On the other hand, the tension of the entire optical fiber 6 is increased, and the tension of the optical fiber 6 during the transmission process is finely adjusted to maintain the tension of the optical fiber 6 on the transmission path within a safe threshold, thereby preventing the optical fiber 6 from breaking due to excessive tension and transmission instability caused by too low tension. Preferably, the tension regulator 17 can dynamically adjust the tension of the optical fiber 6, and ensure the reliability and stability of the optical fiber 6 during the transmission process through dynamic adjustment;

[0083] The cable arrangement mechanism 18 includes a linear module 181 and a guide block 182 disposed on the output end of the linear module 181. The guide block 182 is provided with a tapered through hole 1821 for the optical fiber 6 to pass through. After passing through the guide block 182, the optical fiber 6 enters the winding roller 12, so that the optical fiber 6 is arranged flatly and orderly on the winding roller 12. In this embodiment, by adding the cable arrangement mechanism 18, the problem that the winding roller 12 accumulates with the transmission of the optical fiber 6, the optical fiber 6 will accumulate continuously at the same position of the optical fiber disk, and the diameter of the optical fiber 6 at this position will continue to increase, thereby affecting the stress and tension of the entire optical fiber 6 is solved. In specific use, the output end of the linear module 181 will move back and forth with the transmission of the optical fiber 6, so that the optical fiber 6 can be tightly and orderly wound on the winding roller 12, so that the optical fiber 6 can be arranged flatly, tightly and orderly on the winding roller 12.

[0084] In one embodiment, the femtosecond laser fiber writing mechanism 2 includes a femtosecond laser 21, a beam shaping mechanism, an electronic shutter 27, a galvanometer 28, a focusing lens 29 and a phase mask 210 which are arranged in sequence.

[0085] Among them, the femtosecond laser 21 is a light source for preparing fiber gratings. The femtosecond pulse laser has a very high peak power and a very short pulse width. The nonlinear effect causes the refractive index of the material to change permanently, thereby forming a periodic refractive index change in the optical fiber 6, that is, a fiber grating.

[0086] The beam shaping mechanism is used to perform beam shaping on the laser light emitted by the femtosecond laser 21 .

[0087] The electronic shutter 27 is used to control the time of femtosecond laser exposure of the optical fiber 6. During the transmission of the optical fiber 6, the electronic shutter 27 is closed to block the entry of the laser. When the optical fiber 6 moves to the corresponding position to start the fiber grating production, the electronic shutter 27 opens to allow the laser to enter the subsequent optical system.

[0088] The galvanometer 28 is a high reflective mirror with an angle adjustment function. Through slight angle adjustment, the femtosecond laser exposure area can be expanded and the refractive index modulation range can be expanded. The angle vibration of the galvanometer 28 can make the femtosecond laser scan up and down to expose the optical fiber 6 area.

[0089] The focusing lens 29 plays a role of focusing the femtosecond laser light on the core 61 of the optical fiber 6 .

[0090] The phase mask 210 is a surface relief grating, which mainly forms a periodic refractive index modulation in the core 61 of the optical fiber 6 by generating an interference pattern.

[0091] In this embodiment, the coating needs to be stripped in the online drawing tower preparation technology in the preparation of the current distributed fiber grating array, the consistency and repeatability of the grating prepared by the femtosecond laser direct writing method are unstable, and the preparation efficiency is low, and the high cost of many high-precision control equipment is solved. A femtosecond laser fiber writing mechanism 2 based on the femtosecond laser phase mask template method is proposed. On the one hand, by utilizing the unique properties of the femtosecond laser, the preparation of the fiber grating can be completed through the coating layer 63 of the optical fiber 6; on the other hand, by utilizing the advantages of reliable stability and good repeatability of the phase mask template method system, the consistency of the distributed fiber grating array is improved, and the grating preparation efficiency is also improved. In addition, by cooperating with the optical fiber transmission mechanism 1, the transmission of the optical fiber 6 can be realized, and the relative position relationship between the high-stability optical fiber 6 and the phase mask template 210 can be guaranteed during the transmission process, and the demand for high-precision control equipment is greatly reduced, reducing the equipment cost. The transmission and exposure time of the optical fiber 6 are controlled by the controller 4, and finally the automatic writing of the fiber grating distributed array is realized. That is, the femtosecond laser fiber writing mechanism 2 adopts the technology of combining a femtosecond laser 21 with a phase mask 210, so that the distributed fiber grating writing device based on roll-to-roll has reliable stability, good repeatability and the advantages of high efficiency and low cost.

[0092] In one embodiment, the beam shaping mechanism includes a collimating lens 22, a pinhole aperture 23 and a beam expander lens 24 which are arranged in sequence.

[0093] In this embodiment, the collimating lens 22 converts the divergent laser light emitted by the femtosecond laser 21 into a parallel light beam, the pinhole aperture 23 can intercept the part of the parallel light beam with the most uniform energy density distribution, and the beam expander lens 24 amplifies the uniform light spot intercepted from this section to complete the beam shaping of the laser. Preferably, a reflector I 25 and a reflector II 26 are also provided between the beam shaping mechanism and the electronic shutter 27, and the reflector I 25 and the reflector II 26 are coated with a high-reflection film to redirect the propagation direction of the light path, so that the structure of the entire femtosecond laser fiber writing mechanism 2 is tightly arranged.

[0094] This embodiment has the following advantages: 1. Using a femtosecond laser light source to write a fiber Bragg grating can achieve writing through the cladding 62 and the coating 63 (the optical fiber 6 includes a core 61, a cladding 62 and a coating 63 arranged in sequence from the inside to the outside). 2. Using a femtosecond laser phase mask method can not only ensure good repeatability and consistency of the fiber Bragg grating, but also greatly improve the preparation efficiency of writing distributed fiber Bragg gratings.

[0095] In one of the embodiments, the roll-to-roll distributed fiber grating writing device also includes a controller 4, which is connected to the rotation drive mechanism of the unwinding roller 11 and the winding roller 12 and the electronic shutter 27. By accurately setting the rotation parameters of the rotation drive mechanism and the trigger timing of the electronic shutter 27, precise coordinated control of the grating writing and optical fiber 6 transmission process is achieved.

[0096] Specifically, in the controller 4 program, precise coordinated control of the opening and closing timing of the electronic shutter 27, the rotation drive mechanism of the unwinding roller 11, and the rotation parameters of the rotation drive mechanism of the winding roller 12 is the key to the distributed fiber grating preparation and writing process.

[0097] In one embodiment, the roll-to-roll distributed fiber grating writing device further includes a CCD sensor 5, which is used to monitor the distance between the optical fiber 6 and the phase mask 210 in real time to ensure optimal alignment accuracy.

[0098] The present invention also provides a roll-to-roll distributed fiber Bragg grating writing method, using the roll-to-roll distributed fiber Bragg grating writing device, comprising the following steps:

[0099] S1, the femtosecond laser fiber writing mechanism 2 writes the optical fiber 6 in the writing area;

[0100] S2, after completing S1, the unwinding roller 11 and the winding roller 12 rotate synchronously, so that the upstream of the optical fiber 6 that has completed the writing part enters the writing area, and enters step S1;

[0101] Cycle S1 and S2 to complete the axial writing of the optical fiber 6. During the writing process, the light source 31 transmits light from one end of the optical fiber 6 to the other end. The spectrometer 32 at the other end receives the optical signal in real time and determines the writing state according to the state of the received optical signal, providing data support for adjusting the optical fiber transmission mechanism 1 and the femtosecond laser optical fiber writing mechanism 2 to ensure the quality and performance of the grating.

[0102] The specific use process of the present invention is as follows:

[0103] In actual use, before processing the fiber grating, it is necessary to adjust the various position and structural states of the fiber transmission mechanism 1, such as Figure 1As shown, the optical fiber 6 is wound on the unwinding roller 11, and the unwinding roller 11 is connected to the rotating shaft of the rotary drive mechanism (the rotary drive mechanism preferably adopts a servo motor) through a flange structure and a coupling. A section of the optical fiber 6 is led out, and after being turned by the guide wheel 16, it reaches the same height as the phase mask template 210, and the optical fiber 6 is inserted into the transmission plug 13 structure. In order to improve the stability of the optical fiber transmission, the transmission plug 13 is precisely mounted on the transmission plug mounting member 15. The transmission plug mounting member 15 is fixed on the six-dimensional high-precision displacement platform 14. Such a configuration ensures the rigidity and reliability of the entire system. After the optical fiber 6 successfully passes through the two transmission plugs 13, the relative position between the optical fiber 6 and the phase mask template 210 is precisely fine-tuned by adjusting the six-dimensional high-precision displacement platform 14 to ensure high-stability transmission of the optical fiber 6 at the position of the phase mask template 210. Specifically, after the installation of the optical fiber transmission mechanism 1 is completed, the six-dimensional high-precision displacement stage can be started to fine-tune the relative position of the optical fiber in the X and Y directions, that is, with the phase mask plate 210. Through the CCD sensor 5, the distance between the optical fiber 6 and the phase mask plate 210 can be monitored in real time. First, the optical fiber 6 is adjusted to be parallel to the phase mask plate 210, and then the optical fiber 6 is gradually moved closer to the phase mask plate 210. In subsequent operations, the distance between the optical fiber 6 and the phase mask plate 210 is continuously and accurately adjusted to ensure the best alignment accuracy. Next, the optical fiber 6 will pass through the tension regulator 17. After completing this step, the optical fiber 6 is wound onto the winding roller 12. The tension regulator 17 finely adjusts the tension of the optical fiber 6 during the transmission process to ensure the stability of the transmission of the optical fiber 6 and prevent the optical fiber 6 from breaking due to excessive tension.

[0104] After completing the installation and adjustment of the optical fiber transmission mechanism 1, the femtosecond laser optical fiber writing mechanism 2 is adjusted. Figure 2As shown, the light output by the femtosecond laser 21 first passes through the collimating lens 22 for beam collimation. When adjusting the collimating lens 22, the uniformity and symmetry of the light beam should be observed to ensure that the center of the light beam coincides with the center of the collimating lens 22. After the light beam passes through the collimating lens 22, the center of the light spot is aligned with the center of the collimating lens 22, and the light beam is evenly distributed, the light beam can then pass through the pinhole aperture 23. In this step, it is necessary to observe the light spot after the light beam passes through the pinhole to ensure that its energy density is uniform. After the light beam passes through the pinhole aperture 23, the center of the light spot is aligned with the center of the aperture, and the edge of the light spot is clear and the energy distribution is uniform, the light spot is enlarged by the beam expander lens 24, and the position of the beam expander lens 24 is adjusted to ensure that it is enlarged to the desired size and the light beam remains parallel. The light path is then turned by reflectors I 25 and II 26. In this step, a beam analyzer or CCD camera is required to observe the beam path in real time to ensure that the beam is accurately turned. Then, it is necessary to ensure that the light path is accurately located at the center of the electronic shutter 27. When the light beam passes through the electronic shutter 27 without obvious attenuation or deviation, the next step can be performed. The light beam then reaches the center of the galvanometer 28. During this process, a position sensor or CCD camera is required to monitor the alignment of the light beam and the galvanometer 28 in real time. When the light beam is accurately aligned with the center of the galvanometer 28 and the reflection of the light beam on the galvanometer 28 meets the expected path, it indicates that the alignment is complete.

[0105] When the focal length of the focusing lens 29 and the diameter of the optical fiber 6 are determined, the femtosecond laser focuses on different positions in the optical fiber 6, and there must be a corresponding diffraction spot shape. By finely adjusting the relative positions of the focusing lens 29, the phase mask 210, and the optical fiber 6, the beam state is finally adjusted to focus on the core 61 of the optical fiber through the real-time diffraction spot shape. The adjusted beam should be focused on the core 61 of the optical fiber after passing through the focusing lens 29 and the phase mask 210. The beam focusing state is as follows: Figure 4 At this time, the femtosecond laser fiber writing mechanism 2 is adjusted.

[0106] After the adjustment of the optical fiber transmission mechanism 1 and the femtosecond laser optical fiber writing mechanism 2 is completed, the optical fiber 6 can be written by the femtosecond laser phase mask method. The specific operation process is as follows:

[0107] S11, the femtosecond laser 21 continues to output a light beam, but when the program is not started, the electronic shutter 27 remains closed and the optical fiber transmission mechanism 1 is also in a stationary state.

[0108] S12, the optical fiber transmission mechanism 1 is started, and after the optical fiber 6 is transmitted to the writing area, the optical fiber transmission mechanism 1 is paused, and the electronic shutter 27 is opened immediately to start the grating writing process on the optical fiber 6.

[0109] S21. Once the grating processing at this position is completed, the electronic shutter 27 is closed and the optical fiber transmission mechanism 1 is started again.

[0110] S22, the optical fiber 6 is moved to the next specified position or distance, the upstream unwritten part of the optical fiber 6 enters the writing area, the optical fiber transmission mechanism 1 is paused, and then the electronic shutter 27 is opened again to start the femtosecond laser optical fiber writing mechanism 2.

[0111] The above steps are repeated until the entire distributed fiber grating array is completed.

[0112] While the distributed fiber grating is being written, the transmission spectrum characteristics are monitored in real time by the spectrometer 32, and the fiber transmission mechanism 1 and the femtosecond laser fiber writing mechanism 2 are adjusted in real time based on these data to ensure the quality and performance of the grating.

[0113] The above is only an embodiment and does not limit the present invention in any way. Any person skilled in the art can use the above disclosed technical contents to make many possible changes, modifications or modifications to the technical solutions of the present invention into equivalent embodiments of equivalent changes without departing from the scope of the technical solutions of the present invention. Therefore, any simple modification, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the scope of protection of the technical solutions of the present invention.

Claims

1. A roll-to-roll distributed fiber Bragg grating writing device, characterized in that: It comprises an optical fiber transmission mechanism (1), a femtosecond laser optical fiber writing mechanism (2) and an online monitoring mechanism (3); The optical fiber transmission mechanism (1) comprises an unwinding roller (11), an optical fiber guiding mechanism and a winding roller (12) which are arranged in sequence, and the optical fiber guiding mechanism is used to move the optical fiber (6) in a straight line direction within the writing area; The femtosecond laser optical fiber writing mechanism (2) is used to write on the optical fiber (6) in the writing area using a femtosecond laser phase mask method; The online monitoring mechanism (3) comprises a light source (31) and a spectrometer (32); the light source (31) or the spectrometer (32) rotates synchronously with the unwinding roller (11) and is connected to the head end of the optical fiber (6) in the unwinding roller (11); the spectrometer (32) or the light source (31) rotates synchronously with the winding roller (12) and is connected to the tail end of the optical fiber (6) in the winding roller (12); The light source (31) is fixedly arranged on the side wall of the roller body (19) of the unwinding roller (11) or the winding roller (12), and the spectrometer (32) is fixedly arranged on the side wall of the roller body (19) of the winding roller (12) or the unwinding roller (11); or, further comprising a light source roller (33) and a spectrometer roller (34), wherein the light source roller (33) is coaxial with and rotates synchronously with the unwinding roller (11) or the winding roller (12), and the light source (31) is fixedly arranged on the light source roller ( The optical fiber connecting end of the light source (31) is coaxial with the optical fiber outlet (111) of the unwinding roller (11) or the winding roller (12); the spectrometer roller (34) is coaxial with the winding roller (12) or the unwinding roller (11) and rotates synchronously; the spectrometer (32) is fixedly arranged on the spectrometer roller (34); and the optical fiber connecting end of the spectrometer (32) is coaxial with the optical fiber outlet (111) of the winding roller (12) or the unwinding roller (11).

2. The roll-to-roll distributed fiber Bragg grating writing device according to claim 1, characterized in that: The unwinding roller (11) and the winding roller (12) both comprise a roller body (19); a fiber inlet (110) is provided on the roller surface of the roller body (19); a fiber outlet (111) is provided on the side wall of the roller body (19); and the fiber inlet (110) is in communication with the fiber outlet (111); The head end of the optical fiber (6) is connected to a light source (31) or a spectrometer (32) via an optical fiber outlet (111) of an unwinding roller (11); The tail end of the optical fiber (6) is connected to a spectrometer (32) or a light source (31) via an optical fiber outlet (111) of a winding roller (12).

3. The roll-to-roll distributed fiber Bragg grating writing device according to claim 1 or 2, characterized in that: The optical fiber guiding mechanism comprises two transmission inserts (13) arranged in sequence; The transmission insert (13) comprises an optical fiber guide hole (131), an optical fiber transition hole (132) and an optical fiber guide hole (133) which are arranged in sequence; The size of the optical fiber guide hole (133) is adapted to the optical fiber (6), the size of the optical fiber guide hole (131) is larger than the size of the optical fiber guide hole (133), and the optical fiber transition hole (132) is a tapered hole, one end of which transitions to the optical fiber guide hole (133) and the other end of which transitions to the optical fiber guide hole (133); The optical fiber guide holes (133) of the two transmission inserts (13) are both arranged downstream in the moving direction of the optical fiber (6), and the position between the two transmission inserts (13) is a writing area.

4. The roll-to-roll distributed fiber Bragg grating writing device according to claim 3, characterized in that: The two transmission inserts (13) are arranged on a six-dimensional high-precision displacement platform (14).

5. The roll-to-roll distributed fiber Bragg grating writing device according to claim 3, characterized in that: A guide wheel (16) is provided between the transmission insert (13) located upstream and the unwinding roller (11); A tension regulator (17) and a wire arrangement mechanism (18) are provided between the transmission insert (13) located downstream and the winding roller (12); The cable arrangement mechanism (18) comprises a linear module (181) and a guide block (182) arranged on the output end of the linear module (181); the optical fiber (6) passes through the guide block (182) and enters the winding roller (12), so that the optical fiber (6) is arranged on the winding roller (12) in a flat and orderly manner.

6. The roll-to-roll distributed fiber Bragg grating writing device according to any one of claims 1 to 5, characterized in that: The femtosecond laser optical fiber writing mechanism (2) comprises a femtosecond laser (21), a beam shaping mechanism, an electronic shutter (27), a galvanometer (28), a focusing lens (29), and a phase mask (210) which are arranged in sequence.

7. The roll-to-roll distributed fiber Bragg grating writing device according to claim 6, characterized in that: The beam shaping mechanism comprises a collimating lens (22), a pinhole aperture (23) and a beam expanding lens (24) which are arranged in sequence.

8. A distributed fiber Bragg grating writing method based on roll-to-roll, characterized in that: Using the roll-to-roll distributed fiber Bragg grating writing device as described in any one of claims 1 to 7 comprises the following steps: S1, the femtosecond laser optical fiber writing mechanism (2) writes on the optical fiber (6) in the writing area; S2, after completing S1, the unwinding roller (11) and the winding roller (12) rotate synchronously, so that the upstream of the inscribed portion of the optical fiber (6) enters the inscribed area, and enters step S1; Cycle S1 and S2 to complete the axial writing of the optical fiber (6), and during the writing process, the light source (31) transmits light from one end of the optical fiber (6) to the other end, and the spectrometer (32) at the other end receives the optical signal in real time and determines the writing state according to the state of the received optical signal.

Images