Cladding light resistance detection method

Abstract

The application provides a cladding light resistance detection method, and relates to the technical field of optical fibers, and the method comprises the following steps: providing a cladding light forming device, a power generator and a to-be-detected device; the cladding light forming device comprises a second optical fiber, the second optical fiber comprises a second fiber core and a second cladding, the second fiber core has a hollow structure, and light in the second fiber core is emitted into the second cladding through the hollow structure and forms cladding light; obtaining the cladding light conversion rate of the cladding light forming device; sequentially connecting the power generator, the cladding light forming device and the to-be-detected device; applying an optical signal to the power generator so that the cladding light forming device outputs cladding light to the to-be-detected device; if the to-be-detected device is not broken down, gradually reducing the curvature radius of the second optical fiber to increase the cladding light conversion rate of the cladding light forming device until a preset state is reached; the optical signal and the cladding light conversion rate are used to obtain the cladding light resistance of the to-be-detected device.

Description

Technical Field

[0001] This invention relates to the field of optical fiber technology, and in particular to a method for detecting cladding light tolerance. Background Technology

[0002] When testing the tolerance of cladding light strippers, cladding light needs to be generated. Current technology directly projects a flat-top beam into the device under test (DUT), which requires complex area calculations and results in some energy not being used for testing. Another approach uses spatial light for coupling, requiring a coupling mirror. Adjusting the mirror's angle allows light to penetrate the cladding, reducing the core light output energy to zero. This method is costly and difficult to adjust, significantly increasing time costs. Summary of the Invention

[0003] The purpose of this invention is to provide a method for detecting cladding light tolerance, so as to alleviate the technical problems of the cumbersome and costly method of forming cladding light in the prior art.

[0004] In a first aspect, the present invention provides a method for detecting cladding photoresistivity, the method being used to obtain the cladding photoresistivity of a device under test, the method comprising:

[0005] A cladding light forming device, a power generator, and a device under test are provided; the cladding light forming device includes a second optical fiber, the second optical fiber includes a second core and a second cladding, the second core has a hollow structure, and light in the second core passes through the hollow structure and enters the second cladding to form cladding light;

[0006] Obtain the cladding light conversion efficiency of the cladding light forming device;

[0007] Connect the power generator, the cladding light forming device, and the device under test in sequence;

[0008] An optical signal is applied to the power generator so that the cladding light forming device outputs cladding light to the device under test;

[0009] If the device under test is not broken down, the radius of curvature of the second optical fiber is gradually reduced to increase the cladding light conversion efficiency of the cladding light forming device until a preset state is reached; the preset state includes the device under test being broken down or the cladding light power meeting a preset value.

[0010] Based on the optical signal and the cladding light conversion efficiency, the cladding light tolerance of the device under test is obtained.

[0011] Furthermore, the second optical fiber is an optical fiber formed after the optical fiber is fused together.

[0012] Furthermore, the portion of the hollow structure near the tail end of the second fiber core forms a variable diameter section, with the inner diameter of the variable diameter section gradually decreasing from the head end of the second fiber core toward the tail end of the second fiber core.

[0013] Furthermore, a portion of the hollow structure near the first end of the second fiber core forms a sizing section;

[0014] Along the axial direction, the inner diameter of the fixed-diameter section remains unchanged, and the inner diameter of the fixed-diameter section is equal to the maximum inner diameter of the variable-diameter section;

[0015] The tail end of the fixed-diameter section is connected to the head end of the variable-diameter section.

[0016] Furthermore, the maximum diameter D of the hollow structure satisfies: D1>D≤λ / n eff1 Where λ is the wavelength of the light introduced into the cladding light forming device; n eff1 The phase velocity of light is slowed down relative to vacuum as it propagates in the waveguide; the axial length L of the hollow structure is L = k * D; where k is a proportionality constant, 1.5 ≤ k ≤ 2.0; the cone angle e at the rear end of the variable diameter section of the hollow structure ranges from 10° to 30°; the radial position Q of the center point of the hollow structure is Q = D1 / 2 ± Doffset; where D1 is the diameter of the second fiber core, and Doffset is the offset of the center of the hollow structure relative to the axis of the second fiber core, D1 > (D / 2 + Doffset) * 2.

[0017] Furthermore, along the axial direction, there are multiple hollow structures; adjacent hollow structures are spaced apart, and / or adjacent hollow structures are spaced apart and the volume of the first hollow structure is greater than the volume of the second hollow structure; wherein, the first hollow structure is the hollow structure closer to the beginning end of the second fiber core among two adjacent hollow structures; the second hollow structure is the hollow structure closer to the end of the fiber core among two adjacent hollow structures; the maximum diameter of the first hollow structure is greater than or equal to the maximum diameter of the second hollow structure.

[0018] Furthermore, the axial distance between two adjacent hollow structures is T = M; where M is greater than or equal to the maximum diameter of the second hollow structure and M is less than or equal to the maximum diameter of the first hollow structure.

[0019] Furthermore, the cladding light forming device further includes a first optical fiber, the tail end of which is connected to the head end of the second optical fiber and the optical path is connected. The first optical fiber and the second optical fiber are integrally formed, or the first optical fiber is fused to the second optical fiber; and / or, if the device under test is not broken down, the radius of curvature of the first optical fiber is gradually reduced to increase the cladding light conversion efficiency of the cladding light forming device.

[0020] Furthermore, the first optical fiber includes a first fiber core, the cross-sectional area of ​​the first fiber core is less than or equal to the cross-sectional area of ​​the second fiber core, the tail end face of the first fiber core is connected to the head end face of the second fiber core, and the tail end face of the first fiber core is located inside the head end face of the second fiber core.

[0021] Furthermore, the method further includes: gradually reducing the radius of curvature of the target fiber segment to increase the cladding light conversion efficiency of the cladding light forming device; the radius of curvature R of the target fiber segment and the cladding light conversion efficiency satisfy the following formula:

[0022]

[0023] Where α is the cladding light conversion efficiency;

[0024] ; ; ; ; ;

[0025] n0 is the refractive index of the core of the target fiber segment; eff2 n is the effective refractive index of the guided mode; n1 is the refractive index of the cladding of the target fiber segment; α is the radius of the core of the target fiber segment; V is the normalized frequency; K m-1 It is an m-1 order modified Bessel function of the second kind, where m is the angular order of the fiber mode, (R+ɑ). eff For the effective bending radius, (R+ɑ) eff ≈1.28R; wherein, gradually reducing the radius of curvature of the target fiber segment to increase the cladding light conversion efficiency of the cladding light forming device includes: gradually reducing the radius of curvature of the solid core segment of the second fiber to increase the cladding light conversion efficiency of the cladding light forming device, wherein the solid core segment includes fiber segments in the second fiber other than the fiber segments corresponding to the hollow structure; and / or, gradually reducing the radius of curvature of the first fiber to increase the cladding light conversion efficiency of the cladding light forming device.

[0026] This invention has at least the following advantages or beneficial effects:

[0027] The present invention provides a cladding light tolerance testing method for obtaining the cladding light tolerance of a device under test. The method includes: providing a cladding light forming device, a power generator, and a device under test; the cladding light forming device includes a second optical fiber, the second optical fiber including a second core and a second cladding, the second core having a hollow structure, light within the second core passing through the hollow structure and entering the second cladding to form cladding light; obtaining the cladding light conversion efficiency of the cladding light forming device; sequentially connecting the power generator, the cladding light forming device, and the device under test; applying an optical signal to the power generator to cause the cladding light forming device to output cladding light to the device under test; if the device under test is not broken down, gradually reducing the radius of curvature of the second optical fiber to increase the cladding light conversion efficiency of the cladding light forming device until a preset state is reached; the preset state includes the device under test being broken down or the cladding light power meeting a preset value; obtaining the cladding light tolerance of the device under test based on the optical signal and the cladding light conversion efficiency.

[0028] The two ends of the cladding optical forming device are connected to a power generator and the device under test, respectively. Light emitted from the power generator enters the cladding optical forming device and is incident on the hollow structure. When the incident angle exceeds the critical angle, the light will not undergo total internal reflection but will instead enter the second cladding. The cladding optical forming device converts the light into cladding light and guides it into the device under test. If the device under test is not broken down, the radius of curvature of the second optical fiber is gradually reduced, thereby increasing the cladding optical conversion efficiency of the cladding optical forming device until a preset state is reached. The preset state includes either the device under test being broken down or the cladding optical power meeting a preset value. Based on the optical signal and the cladding optical conversion efficiency, the cladding optical tolerance of the device under test is obtained. During the detection process, there is no need to manually estimate the stripping energy, and there is no energy waste. High-cost equipment such as spatial couplers is not required, reducing costs. Extensive time is not required for adjusting the spatial coupler, resulting in significant time decay. Furthermore, during the testing process, the radius of curvature is gradually reduced until a preset state is reached, so that the tested tolerance performance is closer to the true value, avoiding the problem of inflated tolerance. Attached Figure Description

[0029] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0030] Figure 1This is a schematic diagram showing the connection between the cladding light forming device and the device under test in the initial conditions of the cladding light tolerance detection method provided in the embodiment of the present invention.

[0031] Figure 2 Optical path diagram of the second optical fiber of the cladding light forming device in the cladding light tolerance detection method provided in the embodiments of the present invention;

[0032] Figure 3 This is a schematic flowchart of the cladding light tolerance detection method provided in an embodiment of the present invention.

[0033] Icons: 1-First optical fiber; 2-Second optical fiber; 3-Device under test; 4-Hollow structure; 5-Second fiber core. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0035] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0036] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0037] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0038] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," not that the structure must be completely horizontal, but can be slightly tilted.

[0039] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0040] like Figures 1-3 As shown, the cladding light tolerance detection method provided by the present invention is used to obtain the cladding light tolerance of the device 3 to be tested, wherein the device 3 to be tested can be a cladding light stripping device (CPS) or related devices.

[0041] The method includes:

[0042] A cladding light forming device as described above is provided, along with a power generator and a device under test 3. The cladding light forming device can form cladding light. By forming an optical path using only the cladding light forming device, detecting the injected light power and the output light power, the initial cladding light conversion efficiency of the cladding light forming device is obtained.

[0043] The power generator, the cladding light forming device, and the device under test 3 are sequentially fused together end to end.

[0044] An optical signal is applied to the power generator to cause the cladding optical forming device to output cladding light to the device under test 3. It should be noted that when selecting a usable cladding optical forming device, there are certain requirements for its initial cladding optical conversion efficiency and its minimum cladding optical conversion efficiency after bending; that is, there are certain requirements for the second optical fiber, and not all optical fibers with a hollow structure can be used for testing tolerance. Specifically, the device under test 3 must not be broken down at the initial cladding optical conversion efficiency.

[0045] If the device under test 3 is not broken down, the radius of curvature of the second optical fiber is gradually reduced, thereby increasing the cladding light conversion efficiency of the cladding light forming device and increasing the output cladding light power until the device under test 3 is broken down or the cladding light power meets the preset value. Based on the optical signal and the cladding light conversion efficiency at that time, the cladding light tolerance of the device under test is obtained.

[0046] During the testing process, there is no need for manual estimation of stripping energy, and there is no energy waste. There is no need to purchase high-cost equipment such as spatial couplers, reducing costs. Extensive time is not required for adjusting the spatial coupler, preventing significant time decay. Furthermore, during the testing process, the radius of curvature is gradually reduced until the device under test 3 is broken down or the cladding optical power meets the preset value, resulting in a more accurate measurement of the tolerance performance and avoiding the problem of artificially inflated tolerance.

[0047] Once the cladding light tolerance of the device under test 3 is obtained, it can be determined whether the tolerance of the device under test 3 meets the standard. For the device under test 3 that does not meet the standard, it is necessary to redesign the product of the device under test 3 to optimize its tolerance. Therefore, the above method can provide a basis for the production and preparation of the device under test 3.

[0048] In one embodiment, before testing the cladding light tolerance of the device under test 3, if the cladding light tolerance of the device under test 3 is known to be within a preset range, the accurate cladding light tolerance of the device under test 3 can be determined within the preset range according to the test sequence from low to high cladding light power. This can prevent damage to the device under test 3 and is beneficial to obtaining the accurate cladding light tolerance of the device under test 3.

[0049] In one embodiment, if the cladding light power output by the cladding light forming device is limited by a minimum cladding light power, and the cladding light tolerance of the device under test 3 (i.e., when the cladding light power that the device under test 3 can withstand is less than the minimum cladding light power) is such that a cladding light consumption unit can be added between the cladding light forming device and the device under test 3 to consume a portion of the cladding light power output by the cladding light forming device before testing the device under test 3.

[0050] In one embodiment, the method further includes: when applying an optical signal to the power generator to cause the cladding light forming device to output cladding light to the device under test 3, it should be ensured that the device under test will not be damaged due to being unable to withstand the cladding light power output by the cladding light forming device.

[0051] In practical application scenarios, such as Figure 1 and Figure 2 As shown, the cladding light forming device provided by the present invention includes: a second optical fiber 2, the second optical fiber 2 including a second fiber core 5 and a second cladding (the second cladding is not shown in the diagram to show the second fiber core 5), the second fiber core 5 having a hollow structure 4, the light in the second fiber core 5 passing through the hollow structure 4 and then entering the second cladding to form cladding light.

[0052] like Figure 2As shown, the two ends of the cladding light forming device are connected to a power generator and the device under test (DUT) 3, respectively. Light emitted from the power generator enters the cladding light forming device and then into the hollow structure 4. When the incident angle exceeds the critical angle, the light will not undergo total internal reflection but will instead enter the second cladding. The cladding light forming device converts the light into cladding light and guides it into the DUT 3. By adjusting the power of the power generator, the tolerance of the DUT 3 is tested. During the testing process, there is no need to manually estimate the stripping energy, and there is no energy waste. It eliminates the need to purchase high-cost equipment such as spatial couplers, reducing costs. It also eliminates the need to spend a significant amount of time adjusting the spatial coupler, resulting in minimal time decay.

[0053] The second optical fiber 2 can be an intentionally fabricated structure or an unintentionally fabricated structure, i.e., waste material from other processes, which can be reused. For example, the second optical fiber 2 can be an optical fiber with quartz as the matrix material that has experienced fiber fusion, with a hollow core structure 4, and a transparent and undamaged outer cladding structure. Fiber fusion refers to the phenomenon where, under specific conditions, the optical fiber undergoes localized melting or carbonization due to high-power light injection or physical damage, leading to abnormal fiber performance or breakage. Such fused optical fibers generally need to be discarded, causing economic losses to enterprises. However, in this solution, the fused optical fiber, i.e., the second optical fiber 2, can be reused to form cladding optical fibers.

[0054] Upon inspection, most of the broken optical fibers can form a hollow structure 4 to form cladding light.

[0055] Specifically, the portion of the hollow structure 4 near the tail end of the second fiber core 5 forms a variable-diameter section, with the inner diameter gradually decreasing from the head end of the second fiber core 5 towards its tail end. This gradual decrease in inner diameter creates a structure resembling a conical surface. In optical fibers, light can be "locked" in the core because the refractive index of the core is higher than that of the cladding, and the angle at which the light encounters the boundary during propagation is large enough to cause "total internal reflection." In this design, the hollow structure 4 has an inwardly inclined conical surface with its tip pointing towards the center of the second fiber core 5. When light propagates to this point, the angle at which it encounters this conical surface becomes very small (equivalent to an increased incident angle), exceeding the critical angle. Total internal reflection no longer occurs, and the light exits from the second fiber core 5 and enters the second cladding.

[0056] The hollow structure 4 is bullet-shaped. A portion of the hollow structure 4 near the beginning of the second fiber core 5 forms a sizing section. Along the axial direction, the inner diameter of the sizing section remains constant, and its inner diameter is equal to the maximum inner diameter of the variable-diameter section. The end of the sizing section is connected to the beginning of the variable-diameter section. Existing fused optical fibers can automatically form the hollow structure 4 described above to create cladding light.

[0057] In this scheme, to optimize the light output effect, the required second optical fiber is obtained, which, in a straight state, fails to achieve breakdown in initial optical power but can achieve breakdown during bending. For example, assuming the approximate range of the breakdown optical power of the device under test 3 is known to be MA-MB, then the initial optical power of the required second optical fiber is less than MA, and when the second optical fiber 2 and / or the first optical fiber 1 are bent to their maximum extent, their optical power is greater than MB. The specific structure of the hollow structure 4 can be optimized, and the hollow structure 4 can be modified by in-discharge welding using a fusion splicer.

[0058] The maximum diameter D of the hollow structure 4 is set to satisfy: D1>D≤λ / n eff1 Where λ is the wavelength of the light introduced into the cladding light forming device; n eff1 This represents the degree to which the phase velocity of light slows down relative to the vacuum as it propagates in the waveguide. When this relationship is satisfied, the hollow structure 4 can excite Mie resonances of electric or magnetic dipoles, which is the physical basis for strong scattering; if the diameter is too small, scattering will be weak, and if the diameter is too large, it will excite higher-order modes and have poor directionality.

[0059] The axial length L of the hollow structure 4 is L = k * D; where k is a proportionality constant, 1.5 ≤ k ≤ 2.0, balancing directivity and space occupancy, providing forward enhancement and low echo. k represents the aspect ratio and shape factor of the hollow structure 4. When k is less than 1, the hollow structure 4 is close to a sphere, with weak directivity and near-isotropic scattering; when k = 1, the hollow structure 4 is spherical, with no directivity and strong echo; when k is greater than 2.5, the hollow structure 4 is close to a needle shape, with limited improvement in directivity.

[0060] The rear cone angle e of the variable diameter section of the hollow structure 4 ranges from 10° to 30°. The smaller the angle, the sharper the cone, resulting in stronger forward scattering and better backward suppression. However, when the rear cone angle e is less than 10°, the processing difficulty is high, and when it is greater than 30°, the directional advantage weakens.

[0061] The radial position of the center point of the hollow structure 4 is Q = D1 / 2 ± Doffset; where D1 is the diameter of the second fiber core 5, and Doffset is the offset of the center of the hollow structure 4 relative to the axis of the second fiber core 5. D1 > (D / 2 + Doffset) * 2. Doffset is how far the hollow structure 4 is from the center of the second fiber core 5. It must be close enough to the inside to couple light, but not too far to the outside to avoid structural fragility. Therefore, the hollow structure 4 is close to the inner surface to be in the high field strength region of the waveguide mode (especially for higher order modes), and the hollow structure 4 is far from the outer wall to avoid the hollow structure 4 penetrating or the structure becoming weak, so that the scattered light can escape into the second cladding.

[0062] The electromodification process is as follows: Step 1: Prepare the sample; place the second optical fiber 2 with the hollow structure 4 in the fixture of the optical fiber fusion splicer, ensuring that the target hollow structure 4 region is located at the discharge center between the electrodes. Keep the second optical fiber 2 clean to avoid contamination affecting discharge stability.

[0063] Step 2: Set discharge parameters; Set the following key parameters through the fusion splicer's operating interface: Discharge intensity (Power): Controls the arc energy. It is recommended to set the initial value to 60–80 (fusion splicer units) to avoid excessively high values ​​that could cause structural collapse; Discharge time (Time): The duration of a single discharge. It is recommended to set it to 0.1–2.0 seconds, as shorter pulses are easier to control; Number of discharges (Pulses): Can be set to 1–10 repeated discharges. Multiple low-energy pulses are better than a single high-energy pulse, which helps with fine-tuning; Electrode gap (Gap): Keep the default equipment value or fine-tune it according to the diameter of the second fiber 2 to ensure that the arc uniformly covers the target area.

[0064] Step 3: Perform the discharge; activate the "discharge shaping" or "pre-melting" function of the welding machine to begin the discharge. Observe the real-time image from the built-in microscope of the equipment, paying attention to whether the hollow structure 4 shows signs of melting, shrinkage, or rounding. If the structural changes are not obvious, the energy can be gradually increased or the discharge can be repeated.

[0065] Step 4: Evaluation and Iteration; After the discharge is complete, remove the sample and observe the changes in structural morphology using an optical microscope or scanning electron microscope (SEM). Evaluate whether the expected results have been achieved (e.g., smooth edges, reduced aperture, optimized shape, etc.). If not, re-clamp the sample and perform the next round of discharge to gradually approach the ideal shape. Take care to avoid overheating, which could lead to cavity closure or structural damage.

[0066] Along the axial direction, there are multiple hollow structures 4, thereby achieving scattering at multiple locations. Periodic hollow structures 4 are formed inside the second core 5, scattering more light into the second cladding and reducing light reflection in the second cladding.

[0067] Furthermore, adjacent hollow structures 4 can be spaced apart, with the volume of the first hollow structure 4 being larger than that of the second hollow structure 4. The first hollow structure 4 is the one closest to the beginning of the second fiber core 5 among the two adjacent hollow structures 4; the second hollow structure 4 is the one closest to the end of the fiber core among the two adjacent hollow structures 4; the maximum diameter of the first hollow structure 4 is greater than or equal to the maximum diameter of the second hollow structure 4. Along the axial direction, from the beginning to the end, the size of the hollow structure 4 increases, increasing the reflection path of the fiber core light and making it easier for the fiber core light to enter the second cladding.

[0068] The axial distance between two adjacent hollow structures 4 is T = M; where M is greater than or equal to the maximum diameter of the second hollow structure 4 and M is less than or equal to the maximum diameter of the first hollow structure 4.

[0069] Beneficial effects: This design offers significant advantages in optical microstructure systems. From a physical perspective, this geometric relationship effectively achieves phase matching of the optical field, thereby improving the overall performance of the device.

[0070] Specifically, when light propagates in a vacuum hollow channel, its behavior is modulated by the surrounding periodic structures. Each "bullet-shaped" hollow structure 4 acts as a tiny scattering center, scattering a portion of the guided light. If the axial spacing between adjacent hollow structures 4 is exactly equal to their maximum diameter, and this size is close to the effective wavelength of light in the channel, then the scattered light emitted from each hollow structure 4 will tend to be in phase in the forward direction. This in-phase superposition forms constructive interference, significantly enhancing the intensity of the forward scattered light, making the emitted beam more concentrated and bright, thereby improving light energy utilization and directional control.

[0071] Furthermore, this design is equivalent to constructing a one-dimensional periodic structure at the subwavelength scale, similar to a simplified photonic crystal or distributed feedback structure. It can effectively control the propagation characteristics of light without introducing complex geometric changes. Because the size and arrangement period of the hollow structure 4 are uniform, the symmetry and periodicity of the system are enhanced, which helps suppress unwanted back reflections, reduce energy loss, and avoid the formation of parasitic resonances or interference signals.

[0072] From an engineering perspective, this significantly simplifies structural design and manufacturing processes. By controlling only a single core length parameter, the size and arrangement density of the hollow structure 4 can be determined simultaneously, reducing the complexity of multi-parameter optimization. When using micro-nano fabrication technologies such as femtosecond laser direct writing, repeatable patterns are easier to achieve, and manufacturing errors are easier to control, which helps improve device consistency and yield.

[0073] In summary, this approach not only offers physical advantages for achieving coherent enhancement and directional optimization of forward scattering, but also provides benefits in terms of design simplicity and ease of implementation. It is an excellent design principle that balances performance and manufacturability.

[0074] In one embodiment, the second optical fiber 2 is arranged to bend and coil in an arc shape with a radius of curvature R to increase the scattering effect, thereby enabling more light to form cladding light and increasing the cladding light conversion efficiency.

[0075] The step of gradually reducing the radius of curvature of the second optical fiber 2 to increase the cladding light conversion efficiency of the cladding light forming device until a preset state is reached includes:

[0076] The radius of curvature of the solid core segment of the second optical fiber 2 is gradually reduced to increase the cladding light conversion efficiency of the cladding light forming device, thereby increasing the cladding light conversion efficiency output by the cladding light forming device; wherein, the solid core segment includes the optical fiber segment in the second optical fiber 2 other than the optical fiber segment corresponding to the hollow structure 4, that is, the region between two adjacent hollow structures.

[0077] Specifically, the radius of curvature R of the second optical fiber 2 satisfies the following formula:

[0078]

[0079] Where α is the cladding light conversion efficiency;

[0080] ; ; ; ; n0 is the refractive index of the second fiber core 5; n eff2 n is the effective refractive index of the guided mode; n1 is the refractive index of the second cladding; α is the radius of the second core 5; V is the V-parameter (normalized frequency) of the second fiber; K m-1 It is an m-1 order modified Bessel function of the second kind, where m is the angular order of the fiber mode, (R+ɑ). eff For the effective bending radius, (R+ɑ) eff ≈1.28R. The radius of curvature R and the cladding optical conversion efficiency satisfy the above relationship. Therefore, given the radius of curvature R, the cladding optical conversion efficiency α can be calculated. The output cladding optical power of the second fiber 2 is determined based on the output power of the second fiber 2 and the cladding optical conversion efficiency. It should be understood that in this application, the radius of curvature R of the second fiber 2 (including the fiber segment corresponding to the hollow structure 4) can be reduced, or the radius of curvature R of the second fiber 2 (excluding the fiber segment corresponding to the hollow structure 4) can be reduced. Compared to changing the radius of curvature R of the entire second fiber 2, changing only the radius of curvature R of the solid core segment of the second fiber 2 provides greater control over the cladding optical conversion efficiency.

[0081] The cladding light forming device further includes a first optical fiber 1, the tail end of which is connected to the head end of the second optical fiber 2, and the optical path is open. The first optical fiber 1 is a common optical fiber and serves as a connector. In this embodiment, the first optical fiber 1 and the second optical fiber 2 are fused together. In other feasible solutions, the first optical fiber 1 and the second optical fiber 2 can be integrally formed, that is, a part of a normal optical fiber is fused to form the second optical fiber 2, while the normal part forms the first optical fiber 1. When the cladding light forming device also includes the first optical fiber 1, if the device under test 3 is not broken down, the cladding light conversion efficiency of the cladding light forming device can be increased by gradually reducing the radius of curvature of the first optical fiber 1. It should be understood that the fact that the device under test 3 is not broken down in this application can be understood as the device under test 3 not being damaged due to excessive optical power of the cladding light it receives.

[0082] The first optical fiber 1 includes a first fiber core, the cross-sectional area of ​​the first fiber core is less than or equal to the cross-sectional area of ​​the second fiber core 5, the tail end face of the first fiber core is connected to the head end face of the second fiber core 5, and the tail end face of the first fiber core is located inside the head end face of the second fiber core 5.

[0083] The first end of the first fiber 1 is connected to the power generator. The light first passes through the first fiber 1 and then enters the second fiber 2. The tail end face of the first fiber core is located inside the head end face of the second fiber core 5, so that all the light in the first fiber core can enter the second fiber core 5.

[0084] Both the first optical fiber 1 and the second optical fiber 2 can be 220 / 242 multimode optical fibers.

[0085] In one embodiment, once the second optical fiber 2 is fabricated, the power / energy of the cladding light formed by the second optical fiber 2 remains unchanged without altering its radius of curvature (e.g., the second optical fiber 2 is straight). By adjusting the radius of curvature of the second optical fiber, the output power of the cladding light forming device can be adjusted, thereby enabling the detection of devices under test with different cladding light tolerances.

[0086] In one embodiment, to increase the cladding light conversion efficiency of the cladding light forming device, the method further includes: gradually reducing the radius of curvature of the first optical fiber 1 to increase the cladding light conversion efficiency of the cladding light forming device.

[0087] The radius of curvature R of the first optical fiber 1 and the cladding light conversion efficiency satisfy the following formula:

[0088]

[0089] Where α is the cladding light conversion efficiency;

[0090] ; ; ; ; ;

[0091] n0 is the refractive index of the core of the first optical fiber 1; eff2 n is the effective refractive index of the guided mode; n1 is the refractive index of the cladding of the first fiber 1; α is the radius of the core of the first fiber 1; V is the normalized frequency; K m-1 It is an m-1 order modified Bessel function of the second kind, where m is the angular order of the fiber mode, (R+ɑ). eff For the effective bending radius, (R+ɑ) eff ≈1.28R;

[0092] In one embodiment, the method further includes: generating different radii of curvature for target fiber segments, generating curvature sets for target fiber segments; forming different second fibers 2 (i.e., changing the dimensions of the hollow structure 4 of the second fiber 2), generating a size set for the second fiber 2; generating data sets based on the radii of curvature in any curvature set and the dimensions in any size set, and obtaining the cladding optical power corresponding to each data set; generating simulation sets based on the data set and the cladding optical power; training, predicting, and optimizing a preset cladding optical power acquisition model based on the training and validation sets generated by the simulation sets, and finally determining the target cladding optical power acquisition model. Therefore, when it is necessary to determine the dimensions and radii of curvature of the second fiber 2, the cladding optical power of the cladding optical forming device can be quickly determined. The target fiber segment includes a first fiber, a solid core segment of the second fiber 2, and / or the entire second fiber 2.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for detecting cladding light tolerance, characterized in that, The method is used to obtain the cladding light tolerance of the device under test (3), and the method includes: A cladding light forming device is provided, as well as a power generator and a device to be detected (3); the cladding light forming device includes a second optical fiber (2), the second optical fiber (2) includes a second fiber core (5) and a second cladding, the second fiber core (5) has a hollow structure (4), and the light in the second fiber core (5) passes through the hollow structure (4) and enters the second cladding to form cladding light; Obtain the cladding light conversion efficiency of the cladding light forming device; The power generator, the cladding light forming device, and the device under test (3) are connected in sequence; An optical signal is applied to the power generator so that the cladding light forming device outputs cladding light to the device under test (3); If the device under test (3) is not broken down, the radius of curvature of the second optical fiber (2) is gradually reduced to increase the cladding light conversion efficiency of the cladding light forming device until a preset state is reached; the preset state includes the device under test being broken down or the cladding light power meeting a preset value; Based on the optical signal and the cladding light conversion efficiency, the cladding light tolerance of the device under test (3) is obtained; The portion of the hollow structure (4) near the tail end of the second fiber core (5) forms a variable diameter section, with the inner diameter of the variable diameter section gradually decreasing from the head end of the second fiber core (5) toward the tail end of the second fiber core (5). A portion of the hollow structure (4) near the first end of the second fiber core (5) forms a sizing section; Along the axial direction, the inner diameter of the fixed-diameter section remains unchanged, and the inner diameter of the fixed-diameter section is equal to the maximum inner diameter of the variable-diameter section; The tail end of the fixed-diameter section is connected to the head end of the variable-diameter section.

2. The cladding light tolerance detection method according to claim 1, characterized in that, The second optical fiber (2) is an optical fiber formed after the optical fiber is fused.

3. The cladding light tolerance detection method according to claim 1, characterized in that, The maximum diameter D of the hollow structure (4) satisfies: D1>D≤λ / n eff1 Where λ is the wavelength of the light introduced into the cladding light forming device; n eff1 This indicates the degree to which the phase velocity of light slows down relative to a vacuum as it propagates in a waveguide. The axial length L of the hollow structure (4) is k * D; where k is a proportionality constant, 1.5 ≤ k ≤ 2.0; The range of the cone angle e at the rear end of the variable diameter section of the hollow structure (4) is 10°-30°. The radial position of the center point of the hollow structure (4) is Q = D1 / 2 ± Doffset; where D1 is the diameter of the second fiber core (5), Doffset is the offset of the center of the hollow structure (4) relative to the axis of the second fiber core (5), and D1 > (D / 2 + Doffset) * 2.

4. The cladding light tolerance testing method according to claim 1, 2 or 3, characterized in that, Along the axial direction, there are multiple hollow structures (4); The two adjacent hollow structures (4) are spaced apart, and / or the two adjacent hollow structures (4) are spaced apart and the volume of the first hollow structure (4) is greater than the volume of the second hollow structure (4); Wherein, the first hollow structure (4) is the hollow structure (4) closer to the head end of the second core (5) among two adjacent hollow structures (4); the second hollow structure (4) is the hollow structure (4) closer to the tail end of the core among two adjacent hollow structures (4); the maximum diameter of the first hollow structure (4) is greater than or equal to the maximum diameter of the second hollow structure (4).

5. The cladding light tolerance testing method according to claim 4, characterized in that, The axial distance between two adjacent hollow structures (4) is T = M; where M is greater than or equal to the maximum diameter of the second hollow structure (4) and less than or equal to the maximum diameter of the first hollow structure (4).

6. The cladding light tolerance testing method according to claim 1, 2, 3 or 5, characterized in that, The cladding optical forming device further includes a first optical fiber (1), the tail end of the first optical fiber (1) is connected to the head end of the second optical fiber (2) and the optical path is connected. The first optical fiber (1) and the second optical fiber (2) are integrated, or the first optical fiber (1) is fused to the second optical fiber (2). And / or, if the device under test (3) is not broken down, the radius of curvature of the first optical fiber (1) is gradually reduced to increase the cladding light conversion efficiency of the cladding light forming device.

7. The cladding light tolerance testing method according to claim 6, characterized in that, The first optical fiber (1) includes a first fiber core, the cross-sectional area of ​​the first fiber core is less than or equal to the cross-sectional area of ​​the second fiber core (5), the tail end face of the first fiber core is connected to the head end face of the second fiber core (5), and the tail end face of the first fiber core is located inside the head end face of the second fiber core (5).

8. The cladding light tolerance testing method according to claim 7, characterized in that, The method further includes: gradually reducing the radius of curvature of the target fiber segment to increase the cladding light conversion efficiency of the cladding light forming device; The radius of curvature R of the target optical fiber segment and the cladding optical conversion efficiency satisfy the following formula: Where α is the cladding light conversion efficiency; ； ； ； ； ； n0 is the refractive index of the core of the target fiber segment; eff2 n is the effective refractive index of the guided mode; n1 is the refractive index of the cladding of the target fiber segment; α is the radius of the core of the target fiber segment; V is the normalized frequency; K m-1 It is an m-1 order modified Bessel function of the second kind, where m is the angular order of the fiber mode, (R+ɑ). eff For the effective coiling radius, (R+ɑ) eff ≈1.28R; The process of gradually reducing the radius of curvature of the target fiber segment to increase the cladding light conversion efficiency of the cladding light forming device includes: Gradually reduce the radius of curvature of the solid core segment of the second optical fiber (2) to increase the cladding light conversion efficiency of the cladding light forming device, wherein the solid core segment includes the optical fiber segment in the second optical fiber (2) excluding the optical fiber segment corresponding to the hollow structure (4); and / or gradually reduce the radius of curvature of the first optical fiber (1) to increase the cladding light conversion efficiency of the cladding light forming device.

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