CN118465913A - Fiber Bragg grating writing method and system, grating writing control method - Google Patents

Abstract

The present application relates to a method and system for writing a fiber Bragg grating, and a method for controlling grating writing, wherein the writing method comprises: emitting a femtosecond laser through a femtosecond laser; modulating the femtosecond laser into a cylindrical lens linear light field through a spatial light modulator; and writing a fiber Bragg grating based on the cylindrical lens linear light field. The femtosecond laser (focused state) is mainly modulated into a cylindrical lens linear light field through a spatial light modulator, and a fiber Bragg grating is written 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, and solves the problems of low writing quality and low writing efficiency in the current writing method of a fiber Bragg grating.

Description

Fiber Bragg grating writing method and system, grating writing control method

Technical Field

The present application relates to the field of micro-nano manufacturing, and in particular to a method and system for writing a fiber Bragg grating, and a grating writing control method.

Background Art

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.

In the femtosecond laser point-by-point writing method, 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 method has the problem of low writing efficiency.

Summary of the invention

The present invention provides a fiber Bragg grating writing method 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 method.

In a first aspect, the present invention provides a method for writing a fiber Bragg grating, the method comprising:

emitting femtosecond laser light by a femtosecond laser;

Modulating the femtosecond laser into a cylindrical lens linear light field through a spatial light modulator;

The fiber Bragg grating is written based on the cylindrical lens linear light field.

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

In a second aspect, the present invention provides a fiber Bragg grating writing system for implementing the fiber Bragg grating writing method described in the first aspect, the writing system comprising:

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.

In some embodiments, the method for modulating the femtosecond laser into a cylindrical lens linear light field includes:

It is used to modulate the femtosecond laser into a cylindrical lens linear light field according to the cylindrical lens hologram.

In some of the embodiments, the writing system further comprises:

An energy control device, used for controlling the energy of the femtosecond laser;

The beam expander is used to expand the energy-controlled femtosecond laser and transmit the expanded femtosecond laser to the spatial light modulator.

In some of the embodiments, the energy regulation device includes a half-wave plate and a polarization beam splitter.

In some of the embodiments, the writing system further comprises:

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.

In some of the embodiments, the writing system further comprises:

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 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.

In some of the embodiments, the writing system further comprises:

A computer is used to provide a cylindrical lens hologram to the spatial light modulator.

In a third aspect, the present invention provides a grating writing control method, which is applied to a computer in a fiber Bragg grating writing system described in some embodiments of the second aspect, and the grating writing control method comprises:

In response to the parameter input of the cylindrical lens hologram, a target cylindrical lens hologram is generated;

The target cylindrical lens hologram is loaded into the spatial light modulator of the writing system of the fiber Bragg grating described in the second aspect.

Compared with the related art, the fiber Bragg grating writing method and system provided by the present invention 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 method.

The 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

FIG1 is a structural diagram of a fiber Bragg grating writing system provided in a specific embodiment of the present invention;

FIG2 is a display diagram of cylindrical wave holograms at different angles in some embodiments of the present invention;

FIG3 is a diagram showing linear light fields of cylindrical lenses at different angles in some embodiments of the present invention;

FIG4 is a diagram showing fiber Bragg gratings at different angles in some embodiments of the present invention;

FIG5 is a transmission spectrum diagram of a fiber Bragg grating according to an embodiment of the present invention;

FIG. 6 is a transmission spectrum diagram of a fiber Bragg grating in another embodiment of the present invention.

DETAILED DESCRIPTION

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.

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 before and after 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.

A method for writing a fiber Bragg grating is provided in the present invention. FIG. 1 is a flow chart of the method for writing a fiber Bragg grating provided in the present invention. As shown in FIG. 1 , the process includes steps S110, S120 and S130.

S110, emitting femtosecond laser light through a femtosecond laser.

S120, modulating the femtosecond laser into a cylindrical lens linear light field through a spatial light modulator.

S130, writing a fiber Bragg grating based on a cylindrical lens linear light field.

In the above scheme, a femtosecond laser is used to provide a femtosecond laser, and the fiber Bragg grating obtained by femtosecond laser writing has better thermal stability than the fiber Bragg grating obtained by writing on a photosensitive optical fiber based on a UV continuous or excimer laser. The key point in the above scheme is that a spatial modulator 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, which can be used to write the fiber Bragg grating. Among them, modulating the femtosecond laser into a cylindrical lens linear light field can maximize the use of the energy of the femtosecond laser 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 is a surface processing. Compared with the existing femtosecond laser point-by-point writing method, 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.

In summary, the method for writing a fiber Bragg grating provided by the present invention mainly modulates a femtosecond laser (in a focused state) into a cylindrical lens linear light field through a spatial light modulator, and writes a 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, and solves the problems of low writing quality and low writing efficiency in the current method for writing a fiber Bragg grating.

Furthermore, the spatial light modulator uses a dynamic spatial light modulator (adjustable spatial light modulator), which 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. The control information of the spatial light modulator can be a cylindrical wave hologram.

Therefore, in some of the embodiments, a cylindrical wave hologram is loaded into the spatial light modulator, and the spatial light modulator is configured to modulate the femtosecond laser into a cylindrical lens linear light field according to the cylindrical wave hologram.

In the above embodiment, the required cylindrical wave hologram can be generated by a computer and loaded into the spatial light modulator. 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.

Correspondingly, in other embodiments, the spatial light modulator 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, and tilted fiber Bragg gratings of different angles can also be written.

The present invention also provides a fiber Bragg grating writing system, which is used in the fiber Bragg grating writing method provided by the present invention.

Fig. 1 is a structural diagram of a fiber Bragg grating writing system provided in a specific embodiment of the present invention. Referring to Fig. 1 , the writing system includes a femtosecond laser 1 , a spatial light modulator 6 and a writing platform 9 .

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.

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.

Furthermore, the spatial light modulator 6 adopts a dynamic spatial light modulator 6 (adjustable spatial light modulator 6), 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.

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.

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.

Figure 2 is a diagram showing cylindrical wave holograms at different angles in some embodiments of the present invention. Figure 3 is a diagram showing linear light fields of cylindrical lenses at different angles in some embodiments of the present invention. Figure 4 is a diagram showing fiber Bragg gratings at different angles in some embodiments of the present invention.

Referring to Figure 2, the tilt angles of the cylindrical wave hologram 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 shown in Figure 3. Referring to Figure 3, the tilt angles of the cylindrical lens linear light field from left to right are 0°, 5°, 10° and 15° respectively. The fiber Bragg grating finally formed by the writing is shown in Figure 4. Referring to Figure 4, the tilt angles of the fiber Bragg grating from left to right are 0°, 5°, 10° and 15° respectively.

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.

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.

The energy control device 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 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.

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.

In some embodiments, the energy control device includes a half-wave plate 2 and a polarization beam splitter 3. 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.

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.

In order to monitor the writing process, in some embodiments, 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 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°.

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 then passes through the dichroic mirror 7 again to be collected by the image detection device 12. Among them, a lens 11 can be arranged between the dichroic mirror 7 and the image detection device 12. The image detection device 12 can use a CCD (Charge Coupled Device).

In order to realize the control of the writing system, the writing system specifically further includes a computer. The computer is at least used to control the movement of the writing platform 9, so as to realize the writing of the optical fiber on the writing platform 9.

In the embodiment where the spatial light modulator 6 adopts a dynamic spatial light modulator 6 (adjustable spatial light modulator 6), the computer is also used to provide a cylindrical lens hologram to the spatial light modulator 6, that is, the computer generates a cylindrical lens hologram according to 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 control of the cylindrical lens linear light field, and conveniently writing tilted fiber Bragg gratings of different angles.

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 system is also used to control the image detection device 12 .

It should be noted that the specific position 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 laser or light field emitted by or penetrating the previous component. In order to compact the writing system, a reflector 4 can be set between the energy control device and the beam expander 5 to change the propagation path of the femtosecond laser after energy control.

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 separately. 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.

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

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.

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.

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°).

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

1. Sample preparation: The material of the sample is a 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.

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.

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.

After processing, the transmission spectrum of the grating can be obtained through a spectrometer and a broadband light source, as shown in Figure 5. 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, and all-optical network uplinks, wavelength routing, optical switching, etc. Since the method in this case does not require point-by-point scanning, and processing can be completed only through linear light field exposure, this method is more flexible, efficient, and fast than traditional methods.

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

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.

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.

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.

After processing, the transmission spectrum of the grating can be obtained by a spectrometer and a broadband light source, as shown in Figure 6. In the field of fiber optic 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 fiber optic communications. Tilted fiber Bragg gratings can be used as gain flatteners, dispersion compensation devices, fiber filters, and wavelength division multiplexers for 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 this method is more flexible, efficient, and fast than traditional methods.

The present invention also provides a grating writing control method, which is applied to a computer in a fiber Bragg grating writing system provided by the present invention. The grating writing control method includes:

In response to the parameter input of the cylindrical lens hologram, a target cylindrical lens hologram is generated; and the target cylindrical lens hologram is loaded into the spatial light modulator 6 in the writing system of the fiber Bragg grating provided by the present invention.

Specifically, the grating writing control method is executed by a computer in the writing system of the fiber Bragg grating. The computer can generate different cylindrical lens holograms according to different parameters of the cylindrical lens hologram set by the user and load them into the spatial light modulator 6. Therefore, different cylindrical wave holograms can be generated by adjusting the parameters of the cylindrical wave hologram, thereby realizing flexible control of the cylindrical lens linear light field, and conveniently writing tilted fiber Bragg gratings of different angles.

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.

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 (10)

1. A method for writing a fiber Bragg grating, characterized in that the writing method comprises: emitting femtosecond laser light by a femtosecond laser; Modulating the femtosecond laser into a cylindrical lens linear light field through a spatial light modulator; The fiber Bragg grating is written based on the cylindrical lens linear light field. 2. The method for writing a fiber Bragg grating according to claim 1 is characterized in that a cylindrical wave hologram is loaded in the spatial light modulator, and the spatial light modulator is configured to modulate the femtosecond laser into a cylindrical lens linear light field according to the cylindrical wave hologram. 3. A fiber Bragg grating writing system, characterized in that it is used to implement the fiber Bragg grating writing method according to claim 1, and 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. 4. The fiber Bragg grating writing system according to claim 3, characterized in that the method for modulating the femtosecond laser into a cylindrical lens linear light field comprises: It is used to modulate the femtosecond laser into a cylindrical lens linear light field according to the cylindrical lens hologram. 5. The fiber Bragg grating writing system according to claim 3, characterized in that the writing system further comprises: An energy control device, used for controlling the energy of the femtosecond laser; The beam expander is used to expand the energy-controlled femtosecond laser and transmit the expanded femtosecond laser to the spatial light modulator. 6 . The fiber Bragg grating writing system according to claim 5 , wherein the energy control device comprises a half-wave plate and a polarization beam splitter. 7. The fiber Bragg grating writing system according to claim 3, characterized in that the writing system further comprises: 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. 8. The fiber Bragg grating writing system according to claim 7, characterized in that the writing system further comprises: 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 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. 9. The fiber Bragg grating writing system according to claim 3, characterized in that the writing system further comprises: A computer is used to provide a cylindrical lens hologram to the spatial light modulator. 10. A grating writing control method, characterized in that it is applied to a computer in the fiber Bragg grating writing system of claim 9, and the grating writing control method comprises: In response to the parameter input of the cylindrical lens hologram, a target cylindrical lens hologram is generated; The target cylindrical lens hologram is loaded into the spatial light modulator in the writing system of the fiber Bragg grating according to claim 9.