WO2021184717A1

WO2021184717A1 - Method for manufacturing electrically-controlled fiber grating

Info

Publication number: WO2021184717A1
Application number: PCT/CN2020/117471
Authority: WO
Inventors: 刘申; 王义平; 赵媛媛; 罗俊贤; 陈燕苹; 杨勇
Original assignee: 深圳大学
Priority date: 2020-03-19
Filing date: 2020-09-24
Publication date: 2021-09-23
Also published as: CN111338021A

Abstract

A method for manufacturing an electrically-controlled fiber grating system, comprising: step S1: pre-processing optical fibers (11), to manufacture and cover an electromagnetic induction material layer (12) on a normal grating modulation region in which the optical fibers (11) are axially distributed, so as to form a fiber grating element (1); step S2: using an alternating magnetic field to interact with the electromagnetic induction material layer (12), so that the electromagnetic induction material layer (12) generates heat, and then heats the normal grating modulation region of the optical fibers (11), so as to change the refractive index of the normal grating modulation region, thereby forming a fiber grating. The method for manufacturing an electrically-controlled fiber grating system does not require an expensive instrument device, greatly reducing device costs and simplifying the manufacturing process; the fiber grating element (1) is heated only when placed in an alternating magnetic field, and then the security coefficient is greatly improved, and the writing spectrum of the fiber grating can be modulated in real time, resulting in a higher yield and a controllable manufacturing time, thereby facilitating batch production as well as the recycling and reuse of fiber grating elements (1) for manufacturing different fiber gratings.

Description

Method for preparing electronically controlled fiber grating

Technical field

The invention relates to optical fiber sensing technology, in particular to a method for preparing an electrically controlled optical fiber grating.

Background technique

Fiber grating has the advantages of small size, low splicing loss, full compatibility with optical fibers, and ability to embed smart materials, and its resonance wavelength is sensitive to changes in the external environment such as temperature, strain, refractive index, and concentration. Therefore, it is used in optical fiber communication and The sensing field has been widely used. The existing fiber grating preparation methods mainly include CO2 laser etching, arc discharge, HF wet etching, periodic deformation, amplitude masking, and femtosecond laser direct writing. As an illustration, the typical processing methods are as follows:

CO2 laser etching method: a single laser pulse passes through a focusing mirror and irradiates the fiber, and an imaging system is set up on the fiber to observe whether the light is deformed during the grating writing process. The grating is written point by point by a single-sided laser, and is controlled by a switch The on-off of the laser, after irradiating one position, move the position of the fiber axially to write the next grating area. This writing technology has obvious advantages. It does not need to increase the sensitivity of the optical fiber. The laser movement track can be conveniently controlled by the computer. However, there are certain defects. During the writing process, the computer operates the on and off of the laser and the displacement of the optical fiber, which makes it difficult to ensure the focused laser. The accuracy of each alignment between the light spot and the optical fiber is not conducive to the stability and consistency of grating writing.

Amplitude mask method: The key to this method is the amplitude reticle. When the ultraviolet light passes through the amplitude reticle to expose the optical fiber laterally, it can induce periodic refractive index changes inside the optical fiber to form a long-period grating structure. Since the period of the long-period fiber grating is relatively large, the manufacturing accuracy of the reticle can be ensured, and it is easy to obtain a grating with high consistency that meets the spectral requirements. Therefore, this method has been used and is in the mainstream of the manufacturing process. However, this method also has many disadvantages. First, photosensitive fiber must be used, and the finished product must be unstable at high temperature. Annealing treatment must be adopted for LPG to ensure that it can be used at high temperature. The cycle is fixed, and there is no way to flexibly adjust the cycle length according to the demand, which greatly increases the preparation cost.

Femtosecond laser direct writing method: The focal point of the femtosecond laser focused by the objective lens is incident into the germanium-doped fiber core, the refractive index of the area irradiated by the laser will increase, and the parallel movement of the fiber will form a periodicity inside the glass The waveguide structure. Using femtosecond lasers to write fiber gratings directly, no phase (amplitude) mask is needed. Any type of fiber grating can be prepared by controlling the relative position of the spot focus on the fiber core, but it is used to prepare long periodicity. The fiber grating process is very complicated, difficult to operate, and costly.

Technical solutions

In order to solve the above-mentioned shortcomings of the prior art, the present invention provides a method for preparing an electronically controlled fiber grating system, which does not need to use expensive equipment, greatly saves equipment costs, and simplifies the preparation process. It can be heated in a magnetic field, and the safety factor is greatly improved. The writing spectrum of the fiber grating can be modulated in real time, the yield rate is higher, and the preparation time is controllable, which is conducive to mass production, and the fiber grating components can be recycled and reused for preparation. Different fiber gratings.

The technical problem to be solved by the present invention is realized through the following technical solutions:

A method for preparing an electronically controlled fiber grating includes the following steps:

Step S1: pre-processing the optical fiber to form an electromagnetic induction material layer on the normal position grating modulation area distributed along the axial direction of the optical fiber to form a fiber grating element;

Step S2: Use an alternating magnetic field to interact with the electromagnetic induction material layer to heat the electromagnetic induction material layer to heat the normal grating modulation area of the optical fiber to change the refraction of the normal grating modulation area Rate, forming a fiber grating.

Beneficial effect

The invention has the following beneficial effects: the preparation method uses electromagnetic induction material layers with different distribution laws to perform electromagnetic induction, and different fiber gratings can be prepared without the use of expensive equipment, which greatly saves equipment costs and simplifies the preparation process. Fiber grating components can only be heated when placed in an alternating magnetic field. The safety factor is greatly improved. The writing spectrum of fiber gratings can be modulated in real time, yielding higher yields, and controllable preparation time, which is conducive to mass production and can be recycled. Reuse.

Description of the drawings

Fig. 1 is a block diagram of the steps of the method for preparing the electronically controlled fiber grating provided by the present invention;

2 is a schematic diagram of a fiber grating element of a long-period fiber grating provided by the present invention;

Fig. 3 is a transmission spectrum diagram of the long-period fiber grating shown in Fig. 2;

4 is a schematic diagram of a fiber grating element of a short-period fiber grating provided by the present invention;

Fig. 5 is a reflection spectrum diagram of the short-period fiber grating shown in Fig. 4;

6 is a schematic diagram of a fiber grating element of aperiodic fiber grating provided by the present invention;

FIG. 7 is a reflection spectrum diagram of the aperiodic fiber grating shown in FIG. 6;

FIG. 8 is a schematic diagram of the preparation system of the electronically controlled fiber grating provided by the present invention;

Fig. 9 is a schematic diagram of another preparation system of an electrically controlled fiber grating provided by the present invention;

FIG. 10 is a block diagram of the steps of the preprocessing method of the electronically controlled fiber grating provided by the present invention; FIG.

FIG. 11 is a block diagram of step S1.2 in the preprocessing method of the electronically controlled fiber grating shown in FIG. 10;

FIG. 12 is a block diagram of another step S1.2 in the preprocessing method of the electronically controlled fiber grating shown in FIG. 10;

FIG. 13 is a block diagram of another step S1.2 in the preprocessing method of the electronically controlled fiber grating shown in FIG. 10.

Embodiments of the present invention

The present invention will be described in detail below with reference to the drawings and embodiments.

As shown in Figures 1, 2, 4, and 6, a method for preparing an electronically controlled fiber grating includes the following steps:

Step S1: preprocessing the optical fiber 11 to form an electromagnetic induction material layer 12 on the normal position grating modulation area distributed along the axial direction of the optical fiber 11 to form the optical fiber grating element 1.

In this step S1, the electromagnetic induction material layer 12 can be made of metals such as iron, nickel, cobalt, or oxides or alloys containing such metals, such as iron oxide, silicon steel, stainless steel, iron-cobalt alloy, nickel-cobalt alloy, etc. Such metals, metal oxides and alloys not only have good electrical conductivity, but also good magnetic permeability. In addition, rare earths or oxides or alloys containing rare earths can also be used to make the electromagnetic induction material layer 12.

Step S2: Use an alternating magnetic field to interact with the electromagnetic induction material layer 12 to cause the electromagnetic induction material layer 12 to generate heat to heat the normal position grating modulation area of the optical fiber 11 to change the normal position grating modulation The refractive index of the region, forming a fiber grating.

In this step S2, when the alternating magnetic field acts on the electromagnetic induction material layer 12, based on the principle of electromagnetic induction, a current eddy current can be formed inside the electromagnetic induction material layer 12, and the current eddy current has a thermal effect. The electromagnetic induction material layer 12 is heated, and based on the photothermal effect of the optical fiber, the refractive index of the normal position grating modulation area changes under the heating of the electromagnetic induction material layer 12 to form the optical fiber grating.

Since the refractive index of the modulation area of the normal position grating changes with its temperature change, the writing spectrum of the fiber grating can be modulated by controlling the heating value of the electromagnetic induction material layer 12. Therefore, after step S2, the preparation method further includes:

Step S3: modulate the real-time writing spectrum of the fiber grating to a required writing spectrum by controlling the alternating magnetic field.

In this step S3, the purpose of controlling the alternating magnetic field can be achieved by controlling the alternating current that generates the alternating magnetic field. The current and voltage intensity and alternating frequency of the alternating current respectively correspond to the alternating current. The magnetic field strength and alternating frequency of the magnetic field jointly determine the heat generation of the electromagnetic induction material layer 12, thereby determining the grating modulation amount of the normal position grating modulation area, that is, the resonant peak wavelength and loss peak of the fiber grating The preparation and modulation time is negatively related to the current and voltage intensity and alternating frequency of the alternating current. The greater the current and voltage intensity and the alternating frequency of the alternating current, the longer the preparation and modulation time of the fiber grating Less, and vice versa, the greater.

Therefore, the resonant peak wavelength and loss peak of the fiber grating can be modulated by controlling the current and voltage intensity and/or alternating frequency of the alternating current (that is, the magnetic field intensity and/or alternating frequency of the alternating magnetic field). At least one of intensity and preparation time.

Specifically, in this step S3, the step of modulating the real-time writing spectrum of the fiber grating to the required writing spectrum is as follows:

Step S3.1: Couple a detection beam into the fiber grating element 1.

In this step S3.1, the detection beam coupled into the fiber grating element 1 is preferably a super-continuous broadband beam, and its detection spectrum continuously covers a larger wavelength range.

Step S3.2: receiving the light beam transmitted or reflected from the fiber grating element 1 to obtain the real-time writing spectrum of the fiber grating.

In this step S3.2, during the transmission process of the detection beam in the fiber grating element 1, when the detection beam passes through the normal position grating modulation area, a part of the detection beam will be reflected by the fiber grating and return to the original path, forming Reflect the beam to obtain a reflection spectrum, another part of the detection beam can be transmitted through the fiber grating to continue forward to form a transmission beam to obtain a transmission spectrum, wherein the reflection spectrum and the transmission spectrum are complementary, and the complementary constitutes step S3. 1 is the spectrum of the detection beam coupled into the fiber grating element 1.

The real-time writing spectrum and the required writing spectrum of the fiber grating can be represented by the reflection spectrum or the transmission spectrum.

Step S3.3: Control the alternating magnetic field, and modulate the real-time writing spectrum of the fiber grating to the required writing spectrum.

In this step S3.3, the real-time writing spectrum of the fiber grating is compared with the required writing spectrum, if they are the same, the modulation ends, and if they are different, the alternating magnetic field is controlled to change, and step S3 is repeated. .1-S3.3, until the real-time writing spectrum of the fiber grating is the same as the required writing spectrum, the modulation is ended.

Since the refractive index of the normal grating modulation area changes with its temperature, the fiber grating is non-permanent. When the alternating magnetic field is removed, the temperature of the normal grating modulation area returns to normal Later, the fiber grating will also disappear, and the fiber grating element 1 is equivalent to an ordinary optical fiber. Therefore, before each use, the fiber grating element 1 needs to be modulated to have all the characteristics of the fiber grating element 1 through steps S2 and S3. The optical fiber grating of the spectrum needs to be written, and the alternating magnetic field cannot be removed during use. The optical fiber grating needs to be modulated while being used to avoid the temperature change in the modulation area of the normal position grating causing the real-time optical fiber grating. The writing spectrum has deviated.

The preparation method can produce long-period fiber gratings, short-period fiber gratings or non-periodic fiber gratings.

In a specific embodiment, as shown in FIG. 2, the fiber grating is a long-period fiber grating, the grating period Λ=0.5mm, and the grating order is N. The long-periodity is first calculated using the phase matching formula The position of the resonant wavelength of the fiber grating to determine the position of the normal position grating modulation area periodically distributed along the axial direction of the optical fiber 11, and then the N method periodically distributed along the axial direction of the optical fiber 11 at 0.5 mm The electromagnetic induction material layer 12 is fabricated on the position grating modulation area to obtain the fiber grating element 1, and then the alternating magnetic field is used to interact with the electromagnetic induction material layer 12 to perform the processing on the normal position grating modulation area. The heating causes the fiber grating element 1 to form a long-period fiber grating, and finally the real-time writing spectrum of the long-period fiber grating is modulated into a transmission spectrum as shown in FIG. 3.

In another specific embodiment, as shown in FIG. 4, the fiber grating is a short-period fiber grating, the grating period Λ=0.1mm, and the grating order is N. The short period is first calculated using the phase matching formula The resonant wavelength position of the optical fiber grating is used to determine the position of the normal position grating modulation area periodically distributed along the axial direction of the optical fiber 11, and then the N number periodically distributed along the axial direction of the optical fiber 11 at 0.1 mm The electromagnetic induction material layer 12 is fabricated on the normal position grating modulation area to obtain the fiber grating element 1, and then the alternating magnetic field is used to interact with the electromagnetic induction material layer 12 to affect the normal position grating modulation area Heating is performed to make the fiber grating element 1 form a short-period fiber grating, and finally the real-time writing spectrum of the short-period fiber grating is modulated into a reflection spectrum as shown in FIG. 5.

In another specific embodiment, as shown in FIG. 6, the fiber grating is a non-periodic fiber grating, the aperiodic grating pitch is Λ1, Λ2, ... Λn, and the grating order is N, and the same , First use the phase matching formula to calculate the resonant wavelength position of the non-periodic fiber grating to determine the non-periodically distributed position of the normal grating modulation area along the axis of the optical fiber 11, and then The electromagnetic induction material layer 12 is fabricated on the N normal grating modulation regions with a non-periodically distributed pitch of Λ1, Λ2,...Λn in the axial direction of the optical fiber 11 to obtain the fiber grating element 1, and then use the The alternating magnetic field acts on the electromagnetic induction material layer 12 to heat the normal position grating modulation area to make the fiber grating element 1 form a non-periodic fiber grating, and finally the non-periodic fiber grating is real-time The writing spectrum is modulated as the reflection spectrum shown in Figure 7.

As shown in Figs. 10, 2, 4, and 6, a pretreatment method for electronically controlled fiber gratings, which can be used as step S1 of the preparation method described in the first embodiment, includes the following steps:

Step S1.1: According to the phase matching formula, determine the position of the normal position grating modulation area of the required fiber grating distributed along the axial direction of the optical fiber 11.

In this step S1.1, according to the phase matching formula corresponding to the long-period, short-period or aperiodic fiber grating, the resonance peak position of the corresponding fiber grating can be calculated. The phase matching formula is common knowledge in the art, so this embodiment only uses a short-period grating fiber for the following description:

The phase matching formula of the short-period grating fiber is m*λ _B = 2*n _eff *Λ, where m is the grating order _{of the required fiber grating, λ B} is the central reflection wavelength of the required fiber grating, n _eff is the effective refractive index of the fiber core, and Λ is the grating period (grating pitch) of the required fiber grating. According to the phase matching formula, when the grating period Λ and the grating order m of the required fiber grating are _{determined, the central reflection wavelength λ B} of the required fiber grating can be calculated, and conversely, after determining the required fiber grating In the case of the central reflection wavelength λ _B , the relationship between the grating period Λ of the required fiber grating and the grating order m can be calculated.

Step S1.2: forming an electromagnetic induction material layer 12 on the normal position grating modulation area of the optical fiber 11 distributed along the axial direction.

In a specific embodiment, as shown in FIG. 11, step S1.2 includes the following steps:

Step S1.2.1: making an insulating and heat-insulating material layer on the surface of the optical fiber 11.

In this step S1.2.1, the insulating and heat-insulating material layer can be, but not limited to, organic materials such as rubber, silica gel, or plastic. Such organic materials not only have good insulating ability, but also have good heat-insulating ability.

Step S1.2.2: peel off the insulating and heat-insulating material layer covering the normal position grating modulation area, so that the normal position grating modulation area is exposed from the insulating and heat-insulating material layer.

In this step S1.2.2, the insulating material layer may be partially peeled off by cutting or CO2 laser etching.

Step S1.2.3: forming a layer 12 covering the electromagnetic induction material on the exposed normal position grating modulation area.

In this step S1.2.3, the electromagnetic induction material layer 12 can be made by vacuum coating, magnetron sputtering or spraying. During production, the electromagnetic induction material layer 12 may only cover the exposed normal grating modulation area, or simultaneously cover the exposed normal grating modulation area and the insulating and heat-insulating material layer. Due to the insulation and heat insulation properties of the insulating and heat-insulating material layer, the current and heat generated by the electromagnetic induction material layer 12 in the alternating magnetic field will not diffuse outward.

In another specific embodiment, as shown in FIG. 12, step S1.2 includes:

Step S1.2.1: making a coating material layer on the surface of the optical fiber 11.

In this step S1.2.1, the coating material layer needs to meet the requirement that the electromagnetic induction material layer 12 can be removed by a different solution, that is, there is a solution that can dissolve or corrode the coating material layer, The electromagnetic induction material layer 12 cannot be dissolved or corroded. For example, if the coating material layer is made of organic materials such as rubber, silica gel, or plastic, it will be easily dissolved by organic solvents, while metals such as iron, nickel, cobalt, or other materials are used. The electromagnetic induction material layer 12 of oxides or alloys of this type of metal is difficult to dissolve in organic solvents.

Step S1.2.2: peeling off the coating material layer covering the normal position grating modulation area, so that the normal position grating modulation area is exposed from the coating material layer.

In this step S1.2.2, the coating material layer may be partially peeled off by means of cutting or CO2 laser.

In this step S1.2.3, the electromagnetic induction material layer 12 can be made by vacuum coating, magnetron sputtering or spraying. During production, the electromagnetic induction material layer 12 may only cover the exposed normal grating modulation area, or simultaneously cover the exposed normal grating modulation area and the coating material layer.

Step S1.2.4: peel off the remaining coating material layer.

In this step S1.2.4, while the remaining coating material layer is peeled off, the electromagnetic induction material layer 12 covering it can be taken away, leaving only the layer covering the normal grating modulation area. Electromagnetic induction material layer 12.

As mentioned above, the organic solvent can dissolve the coating material layer using organic materials such as rubber, silica gel or plastic, but it is difficult to dissolve the electromagnetic induction material layer 12. Therefore, in this step S1.2.4, an organic solvent can be used to dissolve the remaining The coating material layer is peeled off.

In another specific embodiment, as shown in FIG. 13, step S1.2 includes:

Step S1.2.1: forming a layer 12 covering the electromagnetic induction material on the surface of the optical fiber 11.

In this step S1.2.1, the electromagnetic induction material layer 12 can be made by vacuum coating, magnetron sputtering or spraying.

Step S1.2.2: making a photosensitive material layer covering the surface of the electromagnetic induction material layer.

In this step S1.2.2, the photosensitive material layer can be a positive photoresist or a negative photoresist, which is made by coating.

Step S1.2.3: Expose and develop the photosensitive material layer, so that the electromagnetic induction material layer 12 covering the modulation area of the normal position grating is exposed from the photosensitive material layer.

In this step S1.2.3, the photosensitive material layer is exposed by ultraviolet light through a photolithography mask, and then the exposed or unexposed part of the photosensitive material layer is removed by a developer. The exposed part of the photoresist can be removed by the developer, and the unexposed part of the negative photoresist can be removed by the developer.

Step S1.2.4: the exposed electromagnetic induction material layer 12 is etched and removed.

In this step S1.2.4, if the electromagnetic induction material layer 12 uses metals such as iron, nickel, cobalt, or oxides or alloys containing such metals, the exposed electromagnetic induction material layer 12 can be engraved with an acid solution. It is removed by etching, and the remaining photosensitive material layer is difficult to be corroded by the acid solution.

Step S1.2.5: peel off the remaining photosensitive material layer.

In this step S1.2.5, an alkaline solution can be used to peel off the remaining photosensitive material layer, and the electromagnetic induction material layer 12 using metals such as iron, nickel, cobalt, or oxides or alloys of such metals is difficult to be alkaline Corrosion of the sexual solution.

As shown in Figures 2, 4 and 6, a fiber grating element 1 includes an optical fiber 11 and an electromagnetic induction material layer 12. The electromagnetic induction material layer 12 is prepared to cover the optical fiber 11 along the axial distribution of the normal position grating modulation District.

The electromagnetic induction material layer 12 can be made of metals such as iron, nickel, cobalt, or oxides or alloys containing such metals, such as iron oxide, silicon steel, stainless steel, iron-cobalt alloys, nickel-cobalt alloys, etc., such metals and metals Oxides and alloys have both good electrical conductivity and good magnetic permeability. In addition, rare earths or oxides or alloys containing rare earths can also be used to make the electromagnetic induction material layer 12.

As shown in Figures 8 and 9, an electronically controlled fiber grating system includes the fiber grating element 1 and the magnetic field generating device 2 described in the third embodiment. The alternating magnetic field acting together causes the electromagnetic induction material layer 12 to generate heat to heat the normal grating modulation area of the optical fiber 11 to change the refractive index of the normal grating modulation area to form a fiber grating.

The electronically controlled fiber grating system also includes an input connector and an output connector. The input connector is provided at one end of the fiber grating element 1, and the output connector is provided at the other end of the fiber grating element 1, or the input The connector and the output connector are arranged at the same end of the fiber grating element 1.

The magnetic field generating device 2 includes a magnetic field transmitter 21 and a power supply control module 22. The power supply control module 22 is electrically connected to the magnetic field transmitter 21 to output an alternating current to the magnetic field transmitter 21 so as to make the The magnetic field transmitter 21 generates the alternating magnetic field.

In this embodiment, the magnetic field transmitter 21 includes an electromagnetic coil that surrounds the fiber grating element 1 in the axial direction.

The input connector is used to connect the light source generating device 3 for the light source generating device 3 to couple the detection beam into the fiber grating element 1; the output connector is used to connect the spectrum detection device 4 to provide the spectrum The detection device 4 receives the light beam transmitted or reflected from the fiber grating element 1 to obtain the real-time writing spectrum of the fiber grating.

When the input connector and the output connector are located at the same end of the fiber grating element 1, the electronically controlled fiber grating system further includes a coupling device 5, and the input connector and the output connector are connected to the coupling device 5 through the coupling device 5. At the same end of the fiber grating element 1, the coupling device 5 can couple the incident detection light beam into the fiber grating element 1, and couple the reflected light beam into the spectrum detection device 4.

As shown in Figures 8 and 9, an electronically controlled fiber grating preparation system is not limited to being applied to the preparation method described in Example 1, including the electronically controlled fiber grating system described in Example 4, and

The light source generating device 3 is used for coupling a detection light beam into the fiber grating element 1;

The spectrum detection device 4 is used to receive the light beam transmitted or reflected from the fiber grating element 1 to obtain the real-time writing spectrum of the fiber grating.

The light source generating device 3 is connected to the input connector of the electronically controlled fiber grating system, and the spectrum detection device 4 is connected to the output connector of the electronically controlled fiber grating system.

In a specific implementation, as shown in FIG. 8, the light source generating device 3 is connected to one end of the fiber grating element 1, and the spectrum detection device 4 is connected to the other end of the fiber grating element 1. During the transmission process of the detection light beam in the fiber grating element 1, when passing through the normal position grating modulation area, part of the detection light beam will pass through the fiber grating and continue to be transmitted forward, and the spectrum detection device 4 transmits through the reception The transmission spectrum is obtained as the real-time writing spectrum of the fiber grating.

In another specific implementation, as shown in FIG. 9, the light source generating device 3 and the spectrum detecting device 4 are connected to the same end of the fiber grating element 1, and the detection beam is in the fiber grating element 1. During the transmission process, when passing through the normal position grating modulation area, part of the detected light beam will be reflected by the fiber grating and returned. The spectrum detection device 4 receives the reflected light beam to obtain the reflection spectrum as the value of the fiber grating Write spectrum in real time.

At this time, preferably, the light source generating device 3 and the spectrum detecting device 4 are connected to the same end of the fiber grating element 1 through a coupling device 5, and the coupling device 5 can couple the incident detection beam to the fiber grating In the element 1, the reflected light beam is coupled into the spectrum detection device 4.

When modulating the real-time writing spectrum of the light grating, the technician can manually control the power control module 22 in the magnetic field generating device 2 according to the real-time writing spectrum obtained by the spectrum detection device 4 to control the power supply The alternating current output by the control module 22 further controls the alternating magnetic field generated by the magnetic field transmitter 21, and finally modulates the real-time writing spectrum of the fiber grating to the required writing spectrum.

Of course, the preparation system may also include a processing control host (not shown in the figure), and the processing control host is communicatively connected between the spectrum detection device 4 and the magnetic field generation device 2, and is used to detect the spectrum according to the spectrum. 4 The obtained real-time writing spectrum automatically controls the power control module 22 of the magnetic field generating device 2 to automatically modulate the real-time writing spectrum of the fiber grating to the required writing spectrum.

The above-mentioned embodiments only express the implementation of the present invention. The description is more specific and detailed, but it should not be understood as a limitation on the patent scope of the present invention. However, all technical solutions obtained by equivalent substitutions or equivalent transformations , Should fall within the protection scope of the present invention.

Claims

A method for preparing an electronically controlled fiber grating, which is characterized in that it comprises the following steps:

S1: preprocessing the optical fiber to form an electromagnetic induction material layer on the normal grating modulation area distributed along the axial direction of the optical fiber to form a fiber grating element;

S2: Use an alternating magnetic field to interact with the electromagnetic induction material layer to heat the electromagnetic induction material layer and heat the normal grating modulation area of the optical fiber to change the refractive index of the normal grating modulation area , Forming a fiber grating.
The method for preparing an electronically controlled fiber grating according to claim 1, characterized in that, after S2, the method further comprises the following steps:

S3: modulate the real-time writing spectrum of the fiber grating to a required writing spectrum by controlling the alternating magnetic field.
The method for preparing an electronically controlled fiber grating according to claim 2, wherein S3 includes the following steps:

S3.1: Couple a detection beam into the fiber grating element;

S3.2: receiving the light beam transmitted or reflected from the fiber grating element to obtain the real-time writing spectrum of the fiber grating;

S3.3: Control the alternating magnetic field to modulate the real-time writing spectrum of the fiber grating into a required writing spectrum.
The method for preparing an electronically controlled fiber grating according to claim 2 or 3, wherein the resonant peak wavelength and loss of the fiber grating are modulated by controlling the magnetic field strength and/or the alternating frequency of the alternating magnetic field. The peak intensity is at least the same as the preparation time.
The method for preparing an electronically controlled fiber grating according to claim 2 or 3, wherein the alternating magnetic field is controlled by controlling the alternating current that generates the alternating magnetic field.
The method for preparing an electronically controlled fiber grating according to claim 5, wherein the resonant peak wavelength and loss peak of the fiber grating are modulated by controlling the current and voltage intensity and/or the alternating frequency of the alternating current. The intensity is at least the same as in the preparation time.
The method for preparing an electronically controlled fiber grating according to claim 1, wherein S1 comprises the following steps:

S1.1: According to the phase matching formula, determine the position of the normal position grating modulation area of the required fiber grating distributed along the optical fiber axis;

S1.2: fabricating a layer covering the electromagnetic induction material on the normal position grating modulation area of the optical fiber distributed along the axial direction.
The method for preparing an electronically controlled fiber grating according to claim 7, wherein S1.2 comprises the following steps:

S1.2.1: Making an insulating and heat-insulating material layer on the surface of the optical fiber;

S1.2.2: peeling off the insulating and heat-insulating material layer covering the normal position grating modulation area, so that the normal position grating modulation area is exposed from the insulating and heat-insulating material layer;

S1.2.3: Making a layer covering the electromagnetic induction material on the exposed normal position grating modulation area.
The method for preparing an electronically controlled fiber grating according to claim 7, wherein S1.2 comprises the following steps:

S1.2.1: Making a coating material layer on the surface of the optical fiber;

S1.2.2: peeling off the coating material layer covering the normal position grating modulation area, so that the normal position grating modulation area is exposed from the coating material layer;

S1.2.3: Making a layer covering the electromagnetic induction material on the exposed normal position grating modulation area;

S1.2.4: peel off the remaining coating material layer.
The method for preparing an electronically controlled fiber grating according to claim 7, wherein S1.2 comprises the following steps:

S1.2.1: Making a layer covering the electromagnetic induction material on the surface of the optical fiber;

S1.2.2: making a photosensitive material layer covering the surface of the electromagnetic induction material layer;

S1.2.3: Expose and develop the photosensitive material layer, so that the electromagnetic induction material layer covering the modulation area of the normal position grating is exposed from the photosensitive material layer;

S1.2.4: Etch the exposed electromagnetic induction material layer.