Optical fiber beam expanding equipment and optical fiber processing system

Abstract

The utility model relates to the technical field of optical fiber processing, in particular to optical fiber beam expanding equipment and an optical fiber processing system. The optical fiber beam expanding equipment comprises a detection laser which is located at one end of a to-be-expanded optical fiber and is used for providing detection laser for the to-be-expanded optical fiber; the beam expanding assembly is located in a beam expanding area of the to-be-expanded optical fiber, is used for performing beam expanding operation on the to-be-expanded optical fiber, and comprises a beam expanding laser used for emitting beam expanding laser and a polarization-maintaining welding machine used for controlling the spatial position of the to-be-expanded optical fiber; the spectrum detector is located at the other end of the to-be-expanded optical fiber and used for receiving the detection spectrum of the detection laser transmitted by the to-be-expanded optical fiber, and the spectrum detector is connected with the beam expanding laser and the polarization maintaining welding machine. According to the utility model, the beam expanding finished product yield can be improved, the production efficiency is improved, and the production cost is reduced.

Description

Technical Field

[0001] This utility model relates to the field of optical fiber processing technology, and in particular to an optical fiber beam expander and an optical fiber processing system. Background Technology

[0002] Fiber expansion involves increasing the core diameter or mode field diameter (MFD) of an optical fiber using physical or optical means to meet specific needs in different scenarios. However, traditional fiber expansion methods, such as mechanical stretching, chemical etching, laser etching, and flame burning, while achieving some expansion effect, have many limitations.

[0003] These methods lack real-time monitoring during processing and cannot dynamically adjust processing parameters to ensure the beam characteristics meet expectations, resulting in significant uncertainty in the processing results. Furthermore, traditional methods heavily rely on operator experience, and differences in operator skill can easily lead to inconsistent product quality and low yield rates. In addition, because multiple adjustments and trials are required to achieve the desired effect, traditional methods have long processing times, making them unsuitable for large-scale production, resulting in low production efficiency and high costs. Utility Model Content

[0004] The technical problem to be solved by this utility model embodiment is to provide an optical fiber expansion device and an optical fiber processing system to solve the problems of large uncertainty in processing results, low yield, low production efficiency and high cost in the prior art.

[0005] This utility model discloses an optical fiber beam expander for expanding optical fibers to be expanded.

[0006] The fiber optic beam expander includes:

[0007] Optionally, a probe laser is located at one end of the optical fiber to be expanded, and is used to provide probe laser to the optical fiber to be expanded;

[0008] A beam expanding assembly, located in the beam expanding region of the fiber to be expanded, is used to perform beam expanding operations on the fiber to be expanded, including a beam expanding laser for emitting beam expanding laser and a polarization maintaining fusion splicer for controlling the spatial position of the fiber to be expanded.

[0009] A spectrometer, located at the other end of the fiber to be expanded, is used to receive the detection spectrum of the detection laser transmitted through the fiber to be expanded. The spectrometer is connected to the beam expander laser and the polarization-maintaining fusion splicer.

[0010] Optionally, the beam expander laser is a carbon dioxide laser.

[0011] Optionally, the angle between the optical path of the carbon dioxide laser and the fiber axis of the fiber to be expanded is 30°-60°.

[0012] Optionally, the beam expander includes a collimator located at the output end of the beam expander, which is used to shape the expanded laser beam into a high-order Gaussian spot.

[0013] Optionally, the angle adjustment range of the polarization-maintaining welding machine is ±5°.

[0014] Optionally, the axial offset distance of the polarization-maintaining fusion splicer corresponds to the beam expansion region.

[0015] Optionally, the detection laser is an amplified spontaneous emission source.

[0016] Optionally, the detection laser emitted by the detection laser has a wavelength of 1120-1650nm.

[0017] Optionally, the fiber optic beam expander further includes a fiber optic coupler, through which the spectral detector is connected to the other end of the beam expander fiber.

[0018] This utility model also discloses an optical fiber processing system, including the optical fiber beam expander as described above.

[0019] Compared with the prior art, the beneficial effects of the fiber optic beam expanding device provided by this utility model embodiment are as follows: By adding a probe laser and a spectrometer, the probe laser emitted by the probe laser is transmitted to the spectrometer through the fiber to be expanded, so that the spectrometer can perform spectral analysis on the probe laser and analyze the current beam expansion status of the fiber to be expanded based on the obtained probe spectrum. This allows for timely detection of whether the fiber to be expanded has reached the preset beam expansion target. The current beam expansion status can be understood in real time through the probe spectrum, thereby timely controlling the beam expansion operation of the beam expanding component, effectively avoiding beam expansion defects, improving the yield of expanded finished products, eliminating the need for multiple adjustments, improving production efficiency, and reducing production costs. Attached Figure Description

[0020] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0021] Figure 1 This is a schematic diagram of the structure of an embodiment of the optical fiber beam expander provided by this utility model;

[0022] Figure 2 A schematic diagram of the detection spectrum in one embodiment of this utility model;

[0023] Figure 3This is a schematic diagram of an embodiment of the optical fiber processing system provided by this utility model.

[0024] The labels for the attached figures are as follows:

[0025] 10. Fiber optic beam expander; 11. Probe laser; 12. Beam expander assembly; 121. Beam expander laser; 1211. Collimator; 122. Polarization-maintaining fusion splicer; 13. Spectrometer detector; 14. Fiber optic coupler; 20. Fiber optic processing system; 21. Fiber cutting equipment. Detailed Implementation

[0026] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The preferred embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0027] Please see Figure 1 , Figure 1 This is a schematic diagram of an embodiment of the fiber optic beam expander provided by this utility model. The fiber optic beam expander 10 is used to expand the fiber to be expanded, and includes a probe laser 11, a beam expander assembly 12, and a spectral detector 13. First, a beam expander region is set for the fiber to be expanded, so that the beam expander assembly 12 can perform beam expander operation on the beam expander region. The beam expander region is a bare fiber segment without damage or contamination to ensure uniform thermal field and stress distribution.

[0028] The two ends of the beam-expanding region are designated as the beam-expanding front end and the beam-expanding back end, respectively. The probe laser 11 is located at the beam-expanding front end, allowing the probe laser to be emitted from it. The spectrometer 13 is located at the beam-expanding back end. The probe laser is transmitted through the optical fiber of the beam-expanding region to the spectrometer 13. When the probe laser 11 emits a laser beam, the beam passes through the beam-expanding region, and its intensity, wavelength distribution, and mode characteristics change in real time with the beam-expanding deformation. The spectrometer 13 can analyze the received probe laser to obtain the spectral changes of the probe laser (including power attenuation, multimode interference fringes, and mode coupling characteristics). Power attenuation originates from the scattering / bending loss of the beam-expanding region, directly reflecting the deformation uniformity. The multimode interference fringes are caused by the multimode resonator formed by the beam-expanding cone region, and its free spectral range (FSR) is inversely proportional to the effective interference length, allowing the calculation of the geometric parameters of the beam-expanding region. Mode coupling characteristics are manifested as new loss peaks at specific wavelengths (e.g., 1620 nm), indicating the excitation of higher-order modes (e.g., LP11). These changes collectively constitute a fingerprint of beam expansion quality—power attenuation reflects macroscopic deformation, interference fringes reveal phase accumulation, and mode coupling indicates abrupt changes in waveguide structure. Real-time monitoring of the beam expansion can be achieved through spectral analysis. The detected spectrum can be fed back to the user, allowing them to understand the beam expansion status in real time and adjust the operating parameters of the beam expansion component accordingly. This ensures effective beam expansion, effectively avoids defects, improves product yield and efficiency, reduces production costs, and increases production efficiency.

[0029] In this embodiment, the spectral detector 13 acquires the multimode interference (MMI) spectrum during the beam expansion process. During beam expansion, a phase difference is introduced in the cone region, causing periodic oscillations in the spectrum (such as comb-like interference fringes). The power change at a specific wavelength (such as 1550 nm) is marked in real time. When the interference contrast at 1550 nm reaches the target value (such as >15 dB), the beam expansion is stopped and the system is cooled.

[0030] For example, if the beam expansion operation causes the fiber core diameter in the expanded region to change from 5μm to 20μm, and the mode field diameter (MFD) of the probe laser (1550nm) increases, and a new peak (LP11 mode excitation) appears near 1620nm, then the beam expansion status of the current expanded region can be known.

[0031] In one implementation scenario, spectral information corresponding to fiber optic cavities of different sizes can be obtained first using a truncation method, and the corresponding spectral features can be extracted to determine the target size of the fiber to be expanded and the target spectral features corresponding to that target size. A spectral detector 13 is connected to the beam-expanding laser 121 and the polarization-maintaining fusion splicer 122. When the spectral detector 13 detects that the current spectral features match the target spectral features, it can be considered that the fiber to be expanded has been properly expanded. A target signal can be sent to the beam-expanding assembly 12, and the beam-expanding assembly 12 stops the beam-expanding operation based on this target signal.

[0032] The beam expanding assembly 12 includes a beam expanding laser 121 and a polarization-maintaining fusion splicer 122. The beam expanding laser 121 provides the energy required for local heating of the optical fiber material. The thermal effect of the beam expanding laser emitted by the beam expanding laser 121 softens the optical fiber material to be expanded, facilitating core diameter expansion through mechanical stretching. The polarization-maintaining fusion splicer 122 is responsible for the spatial positioning and motion control of the optical fiber to be expanded, including adjusting the position, stretching speed, and angle of the optical fiber in the expansion cavity to ensure the geometric symmetry of the expansion process.

[0033] When the expanding laser heats the optical fiber, the fiber core diameter is gradually increased by controlling the temperature gradient and stretching force. A spectrometer 13 monitors the expanding process in real time. In one implementation scenario, the expanding laser power (heating rate), mechanical stretching speed, or fiber torsion angle can be dynamically adjusted based on the detected spectral feedback to ensure that the numerical aperture (NA) and mode field diameter of the expanded fiber meet the target requirements. The closed-loop control of spectral monitoring and mechanical control can correct deviations during the expanding process in real time, avoiding overstretching or mode distortion and improving expanding consistency.

[0034] In one implementation scenario, the beam expander 121 is a carbon dioxide laser. The high energy density of carbon dioxide lasers enables rapid local heating, shortening the time required for traditional thermal beam expansion processes. Large-core fiber expansion typically requires heating the fiber end to near its softening point (e.g., the softening temperature of quartz glass is approximately 1600°C) to allow for controlled deformation under mechanical tension. Carbon dioxide lasers have a wavelength of 10.6 μm, and quartz fiber has a high absorption rate in the 10.6 μm band, allowing laser energy to be efficiently converted into heat energy, achieving rapid local heating. Carbon dioxide lasers can achieve continuous output at the W (watt) level. This W-level continuous output (e.g., 1W to 100W) provides a stable heat source, avoiding drastic temperature fluctuations caused by pulsed lasers, ensuring a uniform and controllable beam expansion process, and reaching the target temperature within milliseconds to seconds. This is suitable for rapid industrial processing while avoiding fiber vaporization or structural damage due to excessive power (e.g., kW level).

[0035] In one implementation scenario, the beam expander 121 includes a collimator 1211 located at the output end of the beam expander 121, used to shape the expanded laser beam into a high-order Gaussian spot. When the order n of the high-order Gaussian beam is greater than 1.6, the beam center tends to be top-hat, with a steep drop at the edges. The flat-hat spot has a uniform energy distribution and sharp edges, with small intensity fluctuations in the central region, avoiding local overheating caused by the central hot spot of a standard Gaussian beam. The fiber end face is heated more uniformly, avoiding core collapse or bubble formation caused by excessively high central temperature in traditional Gaussian beams. It also reduces the heat-affected zone (HAZ), reducing the risk of damage to the non-expanded areas of the fiber to be expanded. The flat-hat spot reduces mode coupling perturbations caused by thermal gradients, making the expanded fiber mode closer to the design target (e.g., increased fundamental mode ratio). The uniform thermal field allows for faster stretching speeds (e.g., 1 mm / s) without concern about uneven local deformation.

[0036] In one embodiment, the polarization-maintaining fusion splicer 122 is a Fujikura 100P series polarization-maintaining fiber fusion splicer, equipped with a high-resolution CCD and motor control system, capable of adjusting the three-dimensional position (X / Y / Z axes) of the fiber to ±0.1μm, meeting the deformation control requirements of the expansion process. By using a rotating fixture (0–360°) and polarization axis detection, it is ensured that the birefringence characteristics of the fiber are not damaged after expansion (crucial for polarization-maintaining fiber expansion). During fiber expansion, the core purpose of using the alignment fusion mode of the polarization-maintaining fusion splicer 122 (i.e., alignment and splicing of two independent fibers of the same type) is to ensure a seamless transition in geometric, modal, and mechanical properties of the fiber end faces before and after expansion through high-precision calibration.

[0037] In one implementation scenario, the spectrometer 13 is a high-resolution spectrometer (<0.1nm), and the detection laser 11 emits a detection laser with a wavelength of 1120-1650nm. This wavelength range of 1120-1650nm covers the main operating bands of single-mode / multimode fibers, making it suitable for monitoring polarization-maintaining fiber expansion. The spectrometer 13 is connected to the other end of the fiber to be expanded via an optical fiber coupler 14. The combination of an ultra-wideband light source and a high-resolution spectrometer enables multi-dimensional and high-precision monitoring of the fiber expansion process. The 1120-1650nm monitoring ensures compatibility with the needs of different application scenarios (communication / sensing / laser), and the high-resolution spectrometer has sub-nanometer resolution, enabling accurate identification of mode transitions, micro-losses, and stress birefringence effects.

[0038] Furthermore, the probe laser 11 is an ASE broadband light source (Erbium-doped fiber amplified spontaneous emission): covering 1520-1620nm, suitable for high-precision monitoring in the C / L band. ASE (Amplified Spontaneous Emission) light source is a broadband light source based on stimulated amplification. Its core principle is to amplify spontaneously emitted light in the gain medium (such as doped fiber) to generate high-brightness, broadband output light. The conical structure of the beam expansion region introduces multimode interference. The broadband characteristics of ASE can clearly present the interference fringe period (FSR), and the length and uniformity of the beam expansion region can be inferred through Fourier transform. The short coherence length (<1mm) of the ASE light source avoids parasitic interference (such as noise caused by end-face Fresnel reflection), ensuring that the probe spectrum truly reflects the transmission characteristics of the fiber to be expanded. During the rapid stretching phase of thermal beam expansion (e.g., 0.2mm / s), the ASE light source can provide continuous and stable spectral input, avoiding data breaks.

[0039] In one embodiment, after the fiber to be expanded is fixed on the fixture of the polarization-maintaining fusion splicer 122, the expanding laser is driven to be incident at an oblique angle of 30°-60°. This means the angle between the optical path of the carbon dioxide laser and the fiber axis of the fiber to be expanded is 30°-60°. When the light enters the fiber at an oblique angle, the heat is more concentrated on a specific part of the fiber (the expansion region), thus allowing for more precise control of the heating and softening process. By asymmetrically heating and softening the fiber, while the polarization-maintaining fusion splicer 122 precisely stretches the fiber at a speed of 0.1-2 mm / s with a displacement accuracy of 0.1 μm, sub-micron-level morphology control of the expansion region can be achieved, improving the smoothness of the tapered transition. The angle adjustment range is ±5°, and this ±5° angle fine-tuning can compensate for the axial deviation of the polarization fiber. This improves the expansion quality and stability of the fiber, reduces optical loss, and ensures the efficiency and reliability of the expansion process.

[0040] In one implementation scenario, the polarization-maintaining fusion splicer 122 must be strictly set with alignment parameters according to the fiber type (e.g., PM1550) and diameter (e.g., 125μm) to ensure precise alignment of the core axis / polarization axis (error <0.1μm). The taper function should be disabled to avoid unintended deformation, and an axial offset distance (Offset = 50μm) should be preset based on the expansion area range (e.g., 100μm) to ensure the expansion area is completely outside the splice point. Simultaneously, the fiber overlap should be set to 0μm to ensure a tight, gapless fit between the splice ends.

[0041] The spectrometer 13 acquires the detection spectrum at a high frequency of 10Hz. Interference contrast is analyzed using FFT. When the mode field diameter of the fiber to be expanded is changed through thermal expansion, its corresponding detection spectrum exhibits characteristic absorption changes, such as… Figure 2 As shown. When this absorption change meets the preset criteria (such as...) Figure 2As shown in the red circle, this indicates that the beam expansion operation has been completed. The power of the beam-expanding laser is then reduced by 10% (e.g., from 30W to 27W) to suppress mode degradation caused by overheating. The polarization-maintaining fusion splicer 122 is then fine-tuned in the reverse direction by 0.5μm (accuracy 0.1μm) to compensate for deformation shift caused by thermal strain. 10Hz sampling and millisecond-level feedback significantly improve the production yield of the fiber to be expanded compared to traditional open-loop processes.

[0042] In one implementation scenario, during the heating phase, the fiber to be expanded is softened by a beam-expanding laser (30-50W) at a gradient temperature of 0.1-0.5 mm / s to 1600℃. This is combined with a polarization-maintaining fusion splicer 122 for beam expansion. The real-time beam expansion status is obtained by monitoring the detection spectrum through a spectrometer 13. After entering the stabilization phase, the temperature is maintained at ±2℃ for 5-8 seconds to fully release the deformation stress in the expanded area. Finally, during the annealing phase, the fiber is slowly cooled to room temperature at a rate of 10℃ / s to eliminate more than 90% of the residual stress, achieving a fiber breaking strength of 5N.

[0043] As described above, in this embodiment, by adding a probe laser and a spectral detector, the probe laser emitted by the probe laser is transmitted to the spectral detector through the fiber to be expanded. The spectral detector can then perform spectral analysis on the probe laser and determine the current expansion status of the fiber based on the acquired spectral analysis. This allows for timely detection of whether the fiber has reached the preset expansion target. The real-time monitoring of the expansion status through the spectral analysis enables timely control of the expansion operation of the expansion component, effectively preventing expansion defects, improving the yield of expanded products, eliminating the need for multiple adjustments, increasing production efficiency, and reducing production costs.

[0044] Please see Figure 3 , Figure 3 This is a schematic diagram of an embodiment of the optical fiber processing system provided by this utility model. The optical fiber processing system 20 includes an optical fiber expander 10 as described above and a fiber cutting device 21 located downstream of the optical fiber expander, used for laser precision cutting after the fiber is expanded, requiring the optical fiber end face tilt angle to be <0.5° and ensuring insertion loss <0.1dB.

[0045] It should be understood that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Those skilled in the art can modify the technical solutions described in the above embodiments, or make equivalent substitutions for some of the technical features; and all such modifications and substitutions should fall within the protection scope of the appended claims of this utility model.

Claims

1. An optical fiber beam expander, characterized in that, Used for expanding the fiber optic cable to be expanded. The fiber optic beam expander includes: A probe laser is located at one end of the optical fiber to be expanded, and is used to provide a probe laser to the optical fiber to be expanded. A beam expanding assembly, located in the beam expanding region of the fiber to be expanded, is used to perform beam expanding operations on the fiber to be expanded, including a beam expanding laser for emitting beam expanding laser and a polarization maintaining fusion splicer for controlling the spatial position of the fiber to be expanded. A spectrometer, located at the other end of the fiber to be expanded, is used to receive the detection spectrum of the detection laser transmitted through the fiber to be expanded. The spectrometer is connected to the beam expander laser and the polarization-maintaining fusion splicer.

2. The fiber optic beam expander according to claim 1, characterized in that, The beam expander laser is a carbon dioxide laser.

3. The fiber optic beam expander according to claim 2, characterized in that, The angle between the optical path of the carbon dioxide laser and the fiber axis of the fiber to be expanded is 30°-60°.

4. The fiber optic beam expander according to claim 2, characterized in that, The beam expander laser includes a collimator located at the output end of the beam expander laser, which is used to shape the expanded laser beam into a high-order Gaussian spot.

5. The fiber optic beam expander according to claim 1, characterized in that, The angle adjustment range of the polarization-maintaining welding machine is ±5°.

6. The fiber optic beam expander according to claim 5, characterized in that, The axial offset distance of the polarization-maintaining fusion splicer corresponds to the beam expansion region.

7. The fiber optic beam expander according to claim 1, characterized in that, The detection laser is an amplified spontaneous emission source.

8. The fiber optic beam expander according to claim 7, characterized in that, The detection laser emitted by the detection laser has a wavelength of 1120-1650nm.

9. The fiber optic beam expander according to claim 1, characterized in that, The fiber optic beam expander also includes a fiber optic coupler, through which the spectral detector is connected to the other end of the fiber to be expanded.

10. An optical fiber processing system, characterized in that, Includes the fiber optic beam expander as described in any one of claims 1-9.

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