Optical fiber, optical fiber structure and forming method therefor

Abstract

An optical fiber, an optical fiber structure (100) and a forming method therefor. The optical fiber structure (100) comprises an optical fiber body, which comprises a fiber core (1) and a cladding (2) covering the fiber core (1), wherein a grating structure (11) is provided inside the fiber core (1), and a stripper structure (21) is provided on the cladding (2); and in the optical-path propagation direction inside the optical fiber body, light passes through the grating structure (11) and the stripper structure (21) in sequence.

Description

Optical fiber, optical fiber structure and its forming method

[0001] This application claims priority to Chinese patent application No. 202410499529.6, filed on April 24, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of optical fiber structure technology, and in particular to an optical fiber, an optical fiber structure, and a method for forming the same. Background Technology

[0003] Due to the unique oscillation frequency selection function of fiber gratings, their application in fiber lasers is primarily as cavity mirrors. However, when the power of a fiber laser reaches tens of millions of kilowatts or more in the signal light range, the extremely high power density in the fiber core leads to nonlinear effects and broadening of the output laser spectrum. This nonlinear effect limits further power increases. The filtering characteristics of special fiber gratings can suppress this nonlinear effect. The mechanism involves radiating the spectral components in the nonlinear effect band to the cladding using the special grating, transforming them into cladding radiation modes, and then using a mode stripper to remove these cladding mode lights. Regarding output laser spectrum broadening, special cavity mirror gratings can suppress it.

[0004] Although the introduction of the aforementioned optical components enables the power of fiber lasers to be further increased, it also increases the number of fusion splices in the optical system, resulting in increased insertion loss. Furthermore, the stacking of optical components introduces new challenges to the optical module in terms of thermal design management and volume compression. Technical issues

[0005] The main purpose of this application is to provide an optical fiber, an optical fiber structure, and a method for forming the same, in order to solve the problem of insufficient integration in optical fiber structures. Technical solutions

[0006] To achieve the above objectives, this application provides an optical fiber structure, including an optical fiber body. The optical fiber body includes a fiber core and a cladding covering the fiber core. A grating structure is disposed inside the fiber core, and a stripper structure is disposed on the cladding. Along the optical path propagation direction within the optical fiber body, light passes sequentially through the grating structure and the stripper structure.

[0007] In one embodiment, the grating structure and the stripper structure are spaced apart along the optical path propagation direction within the optical fiber body.

[0008] In one embodiment, multiple grating structures are provided, and the multiple grating structures are arranged at intervals along the optical path propagation direction;

[0009] At least one of the grating structures is located within the projection of the stripper structure onto the fiber core. In one embodiment, the grating structure is located within the projection of the stripper structure onto the fiber core.

[0010] In one embodiment, the grating structure includes any one of a cavity mirror grating, a chirped tilt grating, a tilt grating, or a long-period grating.

[0011] In one embodiment, a plurality of etching grooves are formed on the outer sidewall of the cladding, and the plurality of etching grooves form the stripper structure.

[0012] This application also provides an optical fiber, the optical fiber comprising the optical fiber structure according to any one of the foregoing claims.

[0013] This application also provides a method for forming an optical fiber structure, wherein the method for forming the optical fiber structure according to any one of the above-described methods includes the following steps:

[0014] The grating structure is formed by etching on the core of the optical fiber;

[0015] The stripper structure is formed by etching on the cladding of the optical fiber, thereby forming the optical fiber structure, wherein, along the optical path propagation direction within the optical fiber body, the light rays sequentially pass through the grating structure and the stripper structure.

[0016] In one embodiment, before etching the stripper structure onto the cladding of the optical fiber, the process includes: annealing the optical fiber to remove hydrogen, and cleaning the annealed optical fiber.

[0017] In one embodiment, after etching the stripper structure onto the cladding of the optical fiber, the process includes encapsulating the optical fiber structure. Beneficial effects

[0018] This application provides an optical fiber structure that integrates a grating structure and a stripper structure into a single optical fiber. The grating structure converts the non-signal laser spectral components transmitted through the fiber core into cladding mode light. Subsequently, the cladding mode stripper removes the cladding light, thereby further increasing the output laser power. The grating structure and the stripper structure are sequentially arranged in the same optical fiber and integrated into a whole, greatly reducing the number of fusion splices between devices and increasing the system integration. This makes the optical fiber structure easier to design for thermal management and reduce its size. Attached Figure Description

[0019] Figure 1 is a schematic diagram of the first embodiment of the optical fiber structure (cavity mirror grating) provided in the embodiments of this application;

[0020] Figure 2 is a schematic diagram of the structure 30 of the first embodiment of the optical fiber structure (tilted grating) provided in the embodiments of this application;

[0021] Figure 3 is a schematic diagram of the first embodiment of the optical fiber structure (long-period grating) provided in the embodiments of this application;

[0022] Figure 4 is a schematic diagram of the second embodiment of the optical fiber structure (cavity mirror grating and chirped tilt grating) provided in the embodiments of this application;

[0023] Figure 5 is another structural schematic diagram of the second embodiment of the optical fiber structure (cavity mirror grating and chirped tilt grating) provided by the embodiments of this application;

[0024] Figure 6 is a schematic diagram of the second embodiment of the optical fiber structure (tilted grating and chirped tilted grating) provided in the embodiments of this application;

[0025] Figure 7 is another structural schematic diagram of the second embodiment of the optical fiber structure (tilted grating and chirped tilted grating) provided by the embodiments of this application;

[0026] Figure 8 is a schematic diagram of the second embodiment of the optical fiber structure (cavity mirror grating and long-period grating) provided in the embodiments of this application;

[0027] Figure 9 is another structural schematic diagram of the second embodiment of the optical fiber structure (cavity mirror grating and long period grating) provided by the embodiments of this application;

[0028] Figure 10 is a schematic diagram of the third embodiment (cavity mirror grating) of the optical fiber structure provided in the embodiments of this application;

[0029] Figure 11 is a schematic diagram of the third embodiment (tilted grating) of the optical fiber structure provided in this application;

[0030] Figure 12 is a schematic diagram of the third embodiment (long-period grating) of the optical fiber structure provided in this application.

[0031] Figure 13 is a spectral diagram of the optical fiber structure provided in the embodiment of this application.

[0032] Explanation of icon numbers:

[0033] Label Name Label Name 100 Fiber Structure a Cavity Mirror Grating 1 Fiber Core b Chirped Tilt Grating 11 Grating Structure c Tilt Grating 2 Cladding d Long Period Grating 21 Stripper Structure

[0034] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Embodiments of the present invention

[0035] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application.

[0036] This does not encompass all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments described in this application without inventive effort are within the scope of protection of this application.

[0037] It should be noted that if any directional indications (such as up, down, left, right, forward, backward, etc.) are involved in the embodiments of this application, then such directional indications are only used to explain the situation under a specific posture (as shown in the attached figure).

[0038] The relative positions and movements of the components will change accordingly if the specific posture changes.

[0039] Furthermore, if the embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" or "second" can...

[0040] The inclusion of at least one of the features is explicit or implicit. Furthermore, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution that simultaneously satisfies A and B. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of a person skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0041] Please refer to Figure 1. This application provides an optical fiber structure 100, which includes an optical fiber body. The optical fiber body includes a fiber core 1 and a cladding 2 covering the fiber core 1. A grating structure 11 is disposed inside the fiber core 1, and a stripper structure 21 is disposed on the cladding 2. Along the optical path propagation direction inside the optical fiber body, the light passes through the grating structure 11 and the stripper structure 21 in sequence.

[0042] In the fiber optic structure 100 provided in this application, the grating structure 11 and the stripper structure 21 are integrated into one fiber. The grating structure 11 converts the non-signal laser spectral components transmitted in the fiber core into cladding mode light. Then, the cladding mode stripper removes the cladding light, thereby further improving the output laser power. The grating structure 11 and the stripper structure 21 are sequentially arranged in the same fiber and integrated into a whole. The number of fusion splices between the devices is greatly reduced, the system integration is higher, and the fiber optic structure 100 is easier to design in terms of thermal management and volume compression.

[0043] Referring to Figures 1 to 3, in the first embodiment provided in this application, the grating structure 11 and the stripper structure 21 are spaced apart along the optical path propagation direction within the optical fiber body. The light propagating within the optical fiber body first passes through the grating structure 11, where it is converted into cladding mode light, and then continues to propagate forward, entering the stripper structure 21 for cladding light removal, thereby increasing power. In this embodiment, by spaced apart and arranged along the light propagation path, production resources can be effectively saved.

[0044] Please refer to Figures 4 to 9. In the second embodiment provided in this application, multiple grating structures 11 are provided, and the multiple grating structures 11 are arranged sequentially at intervals along the optical path propagation direction; at least one of the grating structures is located within the projection of the stripper structure 21 on the fiber core. In this embodiment, multiple grating structures 11 are provided. Different transmission effects can be achieved through multiple grating structures 11. At the same time, at least one grating structure 11 is arranged corresponding to the stripper structure 21, so that the laser emitted from the grating structure 11 can directly enter the stripper structure 21 to facilitate the removal of cladding light.

[0045] Please refer to Figures 10 to 12. In the third embodiment provided in this application, the grating structure 11 is located within the projection of the stripper structure 21 onto the fiber core 1. In this embodiment, the grating structure 11 and the stripper structure 21 are connected in parallel to ensure that the light emitted from the grating structure 11 can be completely received by the stripper structure 21, removing the cladding light and increasing the output laser power.

[0046] It should be noted that the grating structure 11 includes any one of the following: cavity mirror grating a, chirped tilt grating b, tilt grating c, or long period grating d.

[0047] Specifically, for the cavity mirror grating a, the optical axis within the optical fiber body and the grating plane of the cavity mirror grating form an angle of 0°, and the cavity mirror grating can achieve cavity mirror frequency selection.

[0048] Regarding the chirped tilted grating b, there is an angle between the optical axis within the fiber body and the grating plane of the chirped tilted grating. This angle reflects the laser light from the nonlinear effect spectrum back to the cladding, making the reflection spectrum undetectable by the spectrometer. Furthermore, the transmission spectrum, which originally contained many separate curves, is broadened by the introduction of the chirp factor, forming a broadband filter.

[0049] Regarding the tilted grating c, there is an angle between the optical axis within the optical fiber body and the grating plane of the tilted grating. The presence of such an angle causes the reflection spectrum to have dips at both ends, and the transmission spectrum to have many separation curves.

[0050] For the long-period grating d, the angle between the optical axis within the fiber body and the grating plane of the long-period grating is found to be 0°. Although this angle of 0° is similar to that of a conventional cavity mirror, the grating period here is typically on the order of 500 μm, while the period of a conventional cavity mirror is on the order of 700 nm. The long-period grating is used here for mode conversion, that is, to convert the nonlinear spectral components transmitted in the fiber core into cladding radiation modes.

[0051] On the other hand, multiple etching grooves are formed on the outer wall of the cladding 2, and these etching grooves form the stripper structure. In this embodiment, the total internal reflection condition of the cladding mode light is broken by the etching grooves.

[0052] Based on the aforementioned optical fiber structure 100, this application provides the following specific embodiments.

[0053] Please refer to Figures 1 to 3. In the first embodiment provided in this application, the grating structure 11 and the stripper structure 21 are arranged at intervals. The grating structure 11 can be any one of the following: cavity mirror grating a, tilted grating c, chirped tilted grating b, or long period grating d.

[0054] The optical device integrating the cavity mirror grating a or the tilted grating c with the stripper structure 21 results in a purer output signal light or compressed linewidth. The optical device integrating the long-period grating d with the stripper structure 21, where the long-period grating d is used as the laser's output cavity mirror, not only possesses the frequency oscillation characteristics of a traditional cavity mirror but can also filter specific modes of light. For example, if a ring-shaped light spot output is required, a long-period grating can be used to participate in the resonance. This conversion can lead to mode leakage into the cladding, which is removed using a cladding mode stripper.

[0055] Please refer to Figures 4 to 9. In the second embodiment provided in this application, multiple grating structures 11 are provided. Specifically, two grating structures 11 are provided, which are sequentially cavity mirror grating a and chirped tilt grating b, or tilt grating c and chirped tilt grating b, or cavity mirror grating a and long-period grating d. Among them, all of the multiple grating structures 11 may be located in the projection of the stripper structure, or only one of the tail ends may be located in the projection of the stripper structure.

[0056] In Figures 4 and 5, the cavity mirror grating a, the chirped tilt grating b, and the stripper structure are integrated into a single structure. The chirped tilt grating converts the non-signal laser spectral components transmitted through the fiber core into cladding mode light. Then, the stripper structure removes the cladding light, thereby further increasing the output laser power.

[0057] In Figures 6 and 7, the tilted grating c, the chirped tilted grating b, and the stripper structure are integrated into a single structure. This means that the tilted grating replaces the traditional cavity mirror grating, providing both the frequency selection function of a traditional cavity mirror and compression of the output laser spectrum. Simultaneously, the chirped tilted grating converts the non-signal laser spectral components transmitted through the fiber core into cladding mode light, which is then removed by the stripper structure, thereby further increasing the output laser power.

[0058] In Figures 8 and 9, the cavity mirror grating a, the long-period grating d, and the stripper structure are integrated into a single structure. The long-period grating enables mode conversion, that is, it converts the fundamental mode signal beam transmitted in the fiber core into higher-order mode signal light. Non-signal laser spectral components are converted into cladding mode light and non-specific mode laser spot patterns, and the stripper structure removes the cladding light.

[0059] Please refer to Figures 10 to 12. In the third embodiment provided in this application, one grating structure 11 is provided, and one grating structure 11 is completely located in the projection of the stripper structure; wherein, the grating structure 11 is any one of cavity mirror grating a, tilted grating c, chirped tilted grating b, or long period grating d.

[0060] Based on the aforementioned optical fiber structure 100, this application also provides an optical fiber, including the aforementioned optical fiber structure 100, that is, it also has all the technical features of the aforementioned optical fiber structure 100, and therefore also has the technical effects brought about by all the aforementioned technical features, which will not be elaborated here.

[0061] Based on the above-described optical fiber structure 100, this application also provides a method for forming an optical fiber structure, the method comprising the following steps:

[0062] S10. The grating structure is formed by etching on the core of the optical fiber;

[0063] In this process, the angle between the optical axis and the normal to the grating plane in the fiber core is adjusted, and the grating structure is inscribed in the fiber core. Depending on the angle between the optical axis and the normal to the grating plane, different types of gratings can be inscribed, including any one of cavity mirror gratings, tilted gratings, chirped tilted gratings, or long-period gratings.

[0064] S20. The stripper structure is etched on the cladding of the optical fiber to form the optical fiber structure, wherein, along the optical path propagation direction within the optical fiber body, the light passes sequentially through the grating structure and the stripper structure.

[0065] Specifically, by etching the cladding layer, the total internal reflection condition of the cladding mode light is broken, thereby increasing the roughness of the cladding surface and breaking the total internal reflection condition of the cladding mode light, thus realizing the fabrication of the stripper structure.

[0066] In this embodiment, the grating structure 11 and the stripper structure 21 are integrated into a single optical fiber. The grating structure 11 converts the non-signal laser spectral components transmitted in the fiber core into cladding mode light. Subsequently, the cladding mode stripper removes the cladding light, thereby further increasing the output laser power. The grating structure 11 and the stripper structure 21 are sequentially arranged in the same optical fiber and integrated into a whole. This greatly reduces the number of fusion splices between devices, resulting in higher system integration and making the optical fiber structure 100 easier to design for thermal management and reduce its size.

[0067] Please refer to Figure 13. In the grating structure 11 and the stripper structure 21, when the grating structure 11 consists of a tilted grating and a chirped tilted grating arranged sequentially, and the chirped tilted grating is within the projection of the stripper structure 21, the spectrum of the tilted grating and the spectrum of the chirped tilted grating are shown.

[0068] Furthermore, prior to step S20, the following steps are included:

[0069] S201. Anneal the optical fiber to remove hydrogen, and then clean the annealed optical fiber.

[0070] Additionally, after step S20, the following is included:

[0071] S30 encapsulates the optical fiber structure.

[0072] In a specific embodiment provided in this application, the method for forming the optical fiber structure includes the following steps:

[0073] Provide optical fibers, remove the coating layer from the optical fibers, and perform cleaning treatment;

[0074] Adjust the angle between the optical axis of the optical fiber and the normal of the plane to be inscribed, and complete the inscription of cavity mirror grating, tilt grating, chirped tilt grating or long period grating in the core of the optical fiber.

[0075] The written grating is then annealed and cleaned.

[0076] The surface of the cladding is etched using a Q-switched laser or an etchant to obtain the stripper structure.

[0077] Different packaging methods are selected based on different power ranges and the length of integrated optical devices. These packaging methods include glass tube packaging and housing packaging.

[0078] The above are merely optional embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. An optical fiber structure, wherein, The optical fiber structure includes an optical fiber body, which includes a fiber core and a cladding covering the fiber core. A grating structure is disposed inside the fiber core, and a stripper structure is disposed on the cladding. Along the optical path propagation direction within the optical fiber body, the light passes sequentially through the grating structure and the stripper structure.

2. The optical fiber structure according to claim 1, wherein, Along the optical path propagation direction within the optical fiber body, the grating structure and the stripper structure are arranged at intervals.

3. The optical fiber structure according to claim 1, wherein, Multiple grating structures are provided, and the multiple grating structures are arranged at intervals along the optical path propagation direction; At least one of the grating structures is located within the projection of the stripper structure onto the fiber core.

4. The optical fiber structure according to claim 1, wherein, The grating structure is located within the projection of the stripper structure onto the fiber core.

5. The optical fiber structure according to claim 1, wherein, The grating structure includes any one of a cavity mirror grating, a chirped tilt grating, a tilt grating, or a long-period grating.

6. The optical fiber structure according to claim 1, wherein, Multiple etching grooves are formed on the outer wall of the cladding, and the multiple etching grooves form the stripper structure.

7. An optical fiber, wherein, The optical fiber includes the optical fiber structure according to any one of claims 1 to 6.

8. A method for forming an optical fiber structure, used to form the optical fiber structure according to any one of claims 1 to 6, wherein, The method for forming the optical fiber structure includes the following steps: The grating structure is formed by etching on the core of the optical fiber; The stripper structure is formed by etching on the cladding of the optical fiber, thereby forming the optical fiber structure, wherein, along the optical path propagation direction within the optical fiber body, the light rays sequentially pass through the grating structure and the stripper structure.

9. The method for forming an optical fiber structure according to claim 8, wherein, Before etching the stripper structure onto the cladding of the optical fiber, the process includes: The optical fiber is subjected to annealing to remove hydrogen, and then the annealed optical fiber is cleaned.

10. The method for forming an optical fiber structure according to claim 8, wherein, After etching the stripper structure onto the cladding of the optical fiber, the process includes: The optical fiber structure is then encapsulated.

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