Forming method for stripping opening of optical fiber coating layer
By combining laser chain breaking, mechanical thinning, and laser finishing methods, the problems of high cost or poor quality in fiber coating stripping are solved, achieving efficient, low-cost, and non-destructive fiber coating stripping with stripping smoothness at the molecular level, thus improving the performance of the pump combiner.
Patent Information
- Application Number
- CN202511979385.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-25
- Publication Date
- 2026-02-13
AI Technical Summary
Existing fiber coating stripping methods suffer from high costs or poor quality, especially for fiber coatings with surface passivation layers, which are easily damaged by mechanical cutting, while laser cutting is costly and inefficient.
A combination of laser chain breaking, mechanical scraping, laser finishing and peeling is used. The passivation layer chemical bonds are broken by laser, mechanical scraping is performed to a preset distance, the chemical bonds of the residual coating layer are finished by laser, and finally the residual coating layer is cleaned to achieve a peeling surface that is non-damaging and highly flat.
It achieves efficient and low-cost fiber coating stripping with molecular-level stripping smoothness and almost no thermal impact, improving the performance and reliability of the pump combiner, with a yield of up to 99.5%.
Smart Images
Figure CN121522808A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of optical fiber processing technology, and specifically to a method for forming a stripped edge of an optical fiber coating. Background Technology
[0002] An optical fiber comprises a core and a cladding and a coating layer that sequentially surround the core. The coating layer includes a standard coating layer and a passivation layer formed by passivating the surface of the standard coating layer. The passivation layer is a dense, chemically inert thin layer formed on the surface of the standard coating layer to improve the environmental stability of the optical fiber.
[0003] The smooth stripping of the fiber coating is a key process in the manufacturing of pump combiners. Among these processes, the shaping of the stripping edge is particularly critical; the cross-section of the stripped edge should be as perpendicular as possible to the fiber axis to avoid heat-affected zones caused by light in the coating at the stripping point. Current technologies often employ simple mechanical cutting or laser cutting for shaping the fiber coating, such as... Figure 2 As shown, the peeling surface obtained by the existing method is not smooth enough and has a certain slope, and the light in the coating layer is prone to heat effect at the peeling point.
[0004] Mechanical cutting uses a tool or wire to physically cut the coating layer to form a stripped edge, such as through diamond wire cutting. While mechanical cutting is less expensive, it can easily cause pulling, uneven residue, and microscopic damage to coatings with good toughness or passivation layers. This results in uneven cuts, excessive burrs, rough stripped edges, and the risk of damaging the optical fiber.
[0005] Laser cutting uses laser beams such as CO2 lasers and femtosecond lasers to thermally cut the coating layer, causing the coating layer to vaporize directly to form a cut. Although laser cutting has high precision, the heat generated may cause hidden damage to the cladding or surrounding areas. In addition, the equipment cost is high, and it is expensive to process the entire thick coating layer. It is also inefficient for thick coatings and there are still edge residues.
[0006] In summary, for the formation of fiber coating stripping, mechanical cutting alone is low in cost but produces poor stripping quality; while laser cutting alone is highly precise but more expensive and less efficient. Summary of the Invention
[0007] In view of this, the present invention provides a method for forming a stripping edge of an optical fiber coating, which aims to strip the optical fiber coating with a surface passivation layer in an economical, efficient and high-quality manner to obtain a stripping edge with no damage and high flatness.
[0008] To solve the above technical problems, the technical solution adopted by the present invention is as follows: A method for forming a stripped edge of an optical fiber coating includes the following steps: S1 Laser breaking of the coating: irradiating the passivation layer with a laser in the circumferential direction of the optical fiber to break the main chain chemical bonds of the passivation layer at the irradiation point, forming an annular breakage zone; S2 Mechanical thinning of the coating: scraping the coating at the annular breakage zone with mechanical cutting until a predetermined distance from the cladding surface is reached; S3 Laser finishing of the coating: breaking the main chain chemical bonds of the coating remaining on the cladding surface at the annular breakage zone with a laser; S4 Peeling off the coating and cleaning the residual coating: peeling the coating on one side of the annular breakage zone from the cladding, leaving the coating on the other side intact; then cleaning the residual coating at the annular breakage zone to obtain the stripped edge.
[0009] In some alternative embodiments, the coating layer is made of an acrylate material; in the laser chain breaking step of the S1 coating layer, the chemical bonds broken are C-C bonds.
[0010] In some optional embodiments, during the laser chain breaking step of the S1 coating, the optical fiber is positioned in an annular mask; the annular mask has an annular slit with a width of 50 μm to 200 μm in the circumferential direction, and a laser with a wavelength of 150 nm to 300 nm is used to irradiate the coating through the annular slit to break the main chain chemical bonds of the coating.
[0011] In some optional embodiments, in the laser chain breaking step of the S1 coating, the laser and the optical fiber used rotate relative to each other in the circumferential direction for one revolution, with a rotation speed of 1 rpm to 10 rpm or an irradiation time of 5 s to 60 s; the spot width of the laser used is 50 μm to 200 μm, and the power density is 10 mW / cm² to 100 mW / cm².
[0012] In some optional implementations, in the mechanical thinning step of the S2 coating, N diamond cutting lines that can reciprocate radially along the optical fiber are used to surround the optical fiber. The projections of the N diamond cutting lines on the axial direction of the optical fiber are located on the sides of a regular N-gon to form a scraping unit. The scraping unit and the optical fiber can rotate relative to each other in the circumferential direction, and the coating at the annular fracture zone is scraped by the diamond cutting lines corresponding to the inscribed circle of the scraping unit. N is an integer ≥3.
[0013] In some alternative implementations, the diamond cutting line in the scraping unit near the side of the coating to be retained is perpendicular to the optical fiber axis.
[0014] In some optional embodiments, the diameter of the diamond cutting wire is 20 μm to 50 μm, the particle size of the diamond powder is 3 μm to 10 μm, the radial feed rate is 0.1 mm / s to 2 mm / s, and the tension is 2 N to 5 N.
[0015] In some optional embodiments, during the mechanical thinning step of the S2 coating, the coating is scraped to a preset distance of 5 μm to 20 μm from the surface of the coating.
[0016] In some optional embodiments, in the laser finishing step of the S3 coating, the laser and optical fiber used rotate relative to each other in the circumferential direction for one revolution, with a rotation speed of 1 rpm to 10 rpm or an irradiation time of 3 s to 30 s; the wavelength of the laser used is 150 nm to 300 nm, the spot width is 50 μm to 200 μm, and the power density is 5 mW / cm² to 50 mW / cm².
[0017] In some alternative implementations, the working distance of the laser used in the laser chain breaking step of the S1 coating layer and the laser finishing step of the S3 coating layer is ≤5mm.
[0018] In summary, compared with the prior art, the present invention has the following advantages and beneficial effects: the entire processing of the method introduced in the present invention is "cold processing", which hardly produces heat effects, so that the residual coating layer is "pulverized" or "de-adhesive" through molecular chain scission, completely removing the extremely thin coating layer remaining after mechanical scraping, and achieving interface de-adhesion through photochemical action to obtain a molecularly smooth peel. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of the process of the present invention.
[0020] Figure 2 This is a magnified microscopic image of the peeling surface obtained by the existing molding method.
[0021] Figure 3 This is a magnified microscopic view of the peeling surface obtained by the molding method described in this invention. Detailed Implementation
[0022] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to specific embodiments.
[0023] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. 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. Therefore, they should not be construed as limiting this invention.
[0024] In the description of this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," "exceeding," etc. are understood to exclude the stated number, while "above," "below," "within," etc. are understood to include the stated number. If terms such as "first," "second," etc., are used only to distinguish technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.
[0025] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.
[0026] like Figure 1 As shown, this invention introduces a method for forming a stripped fiber coating, which mainly includes the following steps: laser breaking of the coating layer S1, mechanical scraping of the coating layer S2, laser finishing of the coating layer S3, and peeling and cleaning of the coating layer S4 and residual coating layer.
[0027] In the laser chain breaking step of the S1 coating layer, the passivation layer is irradiated with a laser in the circumferential direction of the optical fiber to break the main chain chemical bonds of the passivation layer at the irradiation point, forming a ring-shaped destruction zone.
[0028] For example, in passivation layers made of acrylate materials, the main chain chemical bonds are predominantly C-C bonds. Laser-induced breakage of these C-C bonds reduces the molecular weight of the acrylate, causing the material to disintegrate and become easier to scrape. Because acrylate materials have a certain degree of transparency, the laser can penetrate the passivation layer and break the single-bonded carbon chains, creating a ring-shaped fracture zone that runs the entire passivation layer and is easily scraped off. The location of this ring-shaped fracture zone is also the location of the subsequent peeling surface.
[0029] In the laser chain breaking step of the S1 coating, the optical fiber can be located in an annular mask. The annular mask has an annular slit with a width of 50 μm to 200 μm in the circumferential direction. A laser with a wavelength of 150 nm to 300 nm is used to irradiate the passivation layer through the annular slit to break the main chain chemical bonds of the passivation layer.
[0030] In the laser chain breaking step of the S1 coating layer, it is preferable to use a deep ultraviolet excimer lamp (e.g., a xenon excimer lamp) with a wavelength of 172 nm, whose light is projected onto the passivation layer through an annular slit on a mask. The laser spot width is preferably 50 μm to 200 μm, and the power density is preferably 10 mW / cm² to 100 mW / cm². The photon energy of the 172 nm laser is high (approximately 7.2 eV), higher than the main chain chemical bond energy of acrylate materials (CC bond energy approximately 3.45 eV), and can directly break the main chain chemical bonds of acrylate materials, causing the CC bonds to break.
[0031] Compared to the common 248 nm excimer laser, the 172 nm deep ultraviolet light used in this invention has higher photon energy, which can more efficiently break the C-C backbone bonds in the acrylate coating. At the same time, due to its shorter wavelength and higher absorption rate, the energy can be more strictly confined to the extremely thin surface layer, thereby further reducing or even eliminating the thermal impact and potential damage to the underlying glass cladding, achieving interface debonding with higher precision and reliability.
[0032] The laser and optical fiber used rotate relative to each other in the circumferential direction of the optical fiber for one revolution, with a rotation speed of 1 rpm to 10 rpm or an irradiation time of 5 s to 60 s. After one revolution of the laser and optical fiber relative to each other, the position on the passivation layer irradiated by the laser is determined, and the stripping position is determined, providing an accurate positioning reference for subsequent scraping. Alternatively, the optical fiber can be fixed, and the laser can rotate around the circumference of the optical fiber; or the laser can be fixed, and the optical fiber can rotate.
[0033] For passivation layers made of polyimide materials, the main chain chemical bonds of polyimide materials are mainly CO bonds (bond energy about 3.7 eV). The CO bonds can be broken by using a 248 nm KrF (krypton fluoride) excimer laser (photon energy about 5.0 eV) or a 193 nm ArF (argon fluoride) excimer laser (photon energy about 6.4 eV).
[0034] In the mechanical thinning step of the S2 coating, the coating at the annular destruction zone is scraped by mechanical cutting until it reaches a preset distance from the cladding surface.
[0035] In the mechanical thinning step of the S2 coating, N diamond cutting wires that can reciprocate radially along the fiber can be used to surround the fiber. The projections of the N diamond cutting wires onto the axial direction of the fiber are located on the sides of a regular N-gon to form a scraping unit. N is an integer ≥ 3.
[0036] The scraping unit and the optical fiber can rotate relative to each other in the circumferential direction of the optical fiber, and the coating layer at the annular fracture zone is scraped by the diamond cutting line corresponding to the inscribed circle of the scraping unit.
[0037] This explanation uses a scraping unit consisting of three diamond cutting wires as an example. The three diamond cutting wires are arranged in space at 60° angles to each other, forming a scraping unit containing an equilateral triangle. The projections of the three diamond cutting wires onto the axial direction of the optical fiber lie on the three sides of the equilateral triangle. The optical fiber passes through the center of this equilateral triangle.
[0038] A platform can be used as the mounting base for the diamond wire. Optionally, the platform has a slider that can move radially back and forth, with a positioning post screwed onto the slider. The end of the diamond wire is wound around the positioning post, and the tension of the diamond wire is adjusted by rotating the positioning post.
[0039] The platform has a through-hole at its center for optical fibers to pass through. Diamond cutting wires are evenly distributed around this through-hole.
[0040] The radial position of the slider on the platform can be adjusted by a telescopic cylinder or a lead screw and nut assembly.
[0041] The platform itself can rotate via gear pairs, such as a motor.
[0042] When scraping the coating at the annular damage zone, the tension of the diamond wire is first adjusted to a suitable level by rotating the positioning pin. Then, the platform is driven to rotate by a motor and gear pair, causing the diamond wire to rotate circumferentially relative to the coating. Next, the radial position of the slider is adjusted to move the diamond wire radially relative to the coating. Once the diamond wire contacts the coating, scraping begins.
[0043] During scraping, the diamond cutting wire corresponding to the inscribed circle of the scraping unit first physically cuts the passivation layer. Because the main chain chemical bonds of the passivation layer are broken after being irradiated by the laser in the laser chain breaking step of the S1 coating layer, the molecular weight decreases and the material disintegrates, the diamond cutting wire is less likely to be pulled when physically cutting the passivation layer, resulting in a smoother cut with almost no burrs.
[0044] After the passivation layer is completely cut, continue to move the slider radially to cut the standard coating layer until it is cut to a preset distance from the cladding surface, such as 5 μm to 20 μm from the cladding surface.
[0045] This invention enables efficient and uniform scraping of the coating layer by controlling the radial movement of each diamond cutting line in the scraping unit, thereby reducing the thickness of the coating layer to an extremely thin and controllable level.
[0046] Furthermore, since the scraping unit includes more than three diamond cutting wires, and the diamond cutting wires are evenly surrounding the optical fiber, the optical fiber is subjected to the force of multiple diamond cutting wires, which can effectively avoid the optical fiber shaking and swaying during single-wire cutting, achieve uniform and stable material removal, and ensure the uniformity of scraping thickness.
[0047] Optionally, to improve the perpendicularity of the stripped surface, the diamond cutting wire in the scraping unit near the side of the coating layer to be retained is perpendicular to the optical fiber axis. In this way, as the diamond cutting wire moves radially, the cross-section of the coating layer cut by the diamond cutting wire will be perpendicular to the optical fiber axis, thereby resulting in a higher flatness and perpendicularity of the final stripped surface.
[0048] For coatings made of acrylate materials, the preferred diamond cutting wire is electroplated diamond cutting wire with a diameter of 20 μm to 50 μm, a diamond powder particle size of 3 μm to 10 μm, a radial feed rate of 0.1 mm / s to 2 mm / s, and a tension of 2 N to 5 N. The diamond cutting wire should be inspected for wear regularly and replaced with a new wire every 1000 optical fibers processed.
[0049] Alternatively, during the mechanical thinning step of the S2 coating, a tool with a width of 40 μm to 150 μm can be used to cut the coating. In this case, the optical fiber should be stably and reliably supported in the annular fracture zone to prevent the optical fiber from swaying or deflecting during cutting.
[0050] In the laser finishing step of the S3 coating, the main chain chemical bonds of the residual coating on the cladding surface at the annular destruction zone are broken by laser.
[0051] Similar to the laser chain breaking step of the S1 coating, in the laser finishing step of the S3 coating, the main chain chemical bonds of the residual coating are broken by laser irradiation at the annular destruction zone in the circumferential direction of the optical fiber. This reduces the molecular weight of the polymer molecules in the coating, causing the material to disintegrate and making it easier to peel off later.
[0052] In the laser finishing step of the S3 coating, the laser and optical fiber used rotate relative to each other in the circumferential direction for one revolution, with a rotation speed of 1 rpm to 10 rpm or an irradiation time of 3 s to 30 s.
[0053] The wavelength of the laser used is 150 nm to 300 nm, preferably light emitted by a deep ultraviolet excimer lamp (e.g., a xenon excimer lamp) with a wavelength of 172 nm. The spot width is 50 μm to 200 μm and the power density is 5 mW / cm² to 50 mW / cm².
[0054] Because the residual coating is thin, a low-power laser can penetrate the entire thickness and act at the interface between the residual coating and the cladding, breaking the interfacial adhesion and causing the residual coating to detach from the cladding, making it easy to separate.
[0055] Because lasers travel a short distance in air, the working distance of the laser must be controlled within 5mm (inclusive) in the laser chain breaking step of the S1 coating layer and the laser finishing step of the S3 coating layer.
[0056] In the steps of peeling off the S4 coating and cleaning up the residual coating, the coating on one side of the annular damage zone is peeled off from the cladding, while the coating on the other side is retained; then the residual coating at the annular damage zone is cleaned up to obtain the peeling opening.
[0057] The unwanted coating can be peeled off from the cladding by pulling or cutting. Then, the peeled area can be wiped with a soft material such as polyester or nylon microfiber cloth to loosen any remaining coating and prevent large particles from splashing during subsequent purging. Afterward, nitrogen gas at a pressure of 0.5 MPa to 2 MPa can be used at a purging angle of 30° to 60° to blow away the damaged coating residue.
[0058] All steps of this invention should be performed in a clean environment, with a cleanliness level of 1000 recommended.
[0059] In summary, this invention utilizes laser chain breaking with an S1 coating to process various surface-passivated optical fibers, broadening its application range. Laser chain breaking with the S1 coating disrupts the surface passivation layer, facilitating subsequent mechanical processing. Furthermore, laser chain breaking with the S1 coating can mark the stripping location, solving the problem of insufficient stripping accuracy in traditional methods.
[0060] This invention utilizes mechanical scraping of the S2 coating layer to efficiently remove the entire passivation layer and most of the coating layer. This allows expensive lasers to process only a very thin residual coating layer, significantly shortening laser processing time, reducing the system's power requirements, and thus controlling overall costs. Furthermore, the mechanical scraping of the S2 coating layer enables uniform and controllable coating thickness removal, minimizing the adverse effects of uneven residual coating layers.
[0061] This invention enables precise and non-destructive removal of extremely thin residual coating layers through laser finishing of the S3 coating, thereby controlling overall costs while ensuring high-quality stripping. The final stripping is formed by laser photochemical action, achieving a flatness at the near-molecular level without any mechanical damage or thermal impact, greatly improving the performance and reliability of the pump combiner.
[0062] In summary, the entire processing of the method described in this invention is a "cold process," generating almost no heat impact. This allows the residual coating layer to be "pulverized" or "de-adhesive" through molecular chain scission, thoroughly removing the extremely thin coating layer remaining after mechanical scraping. Furthermore, interfacial de-adhesion is achieved through photochemical action, resulting in a molecularly smooth peel. For example... Figure 3 As shown, the average roughness Ra of the stripped area is <0.1 μm, the cladding damage rate is <0.01%, the processing efficiency is 30-60 seconds / fiber, and the yield is >99.5%. Its multi-line thinning system has good stability, the laser process parameters are precisely controllable, and the entire process has extremely high repeatability.
[0063] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0064] The above preferred embodiments should not be considered as limitations on the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. For those skilled in the art, various improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for forming a stripped edge of an optical fiber coating, characterized in that, Includes the following steps: Laser chain breaking of S1 coating: Laser irradiation of the passivation layer in the circumferential direction of the optical fiber breaks the main chain chemical bonds of the passivation layer at the irradiation point, forming a ring-shaped destruction zone. Mechanical thinning of S2 coating: The coating at the annular damage zone is scraped off by mechanical cutting until a preset distance from the cladding surface is reached; Laser finishing of S3 coating: The main chain chemical bonds of the residual coating on the cladding surface at the annular destruction zone are broken by laser. S4 Coating Peeling and Residual Coating Cleaning: Peel the coating on one side of the annular damage zone from the cladding, leaving the coating on the other side; then clean the residual coating at the annular damage zone to obtain the peeling opening.
2. The method for forming the stripping edge of an optical fiber coating as described in claim 1, characterized in that: The coating layer is made of an acrylic ester material; In the laser chain breaking step of the S1 coating, the chemical bond broken is the C-C bond.
3. The method for forming the stripping edge of an optical fiber coating as described in claim 1, characterized in that: In the laser chain breaking step of the S1 coating, the optical fiber is placed in an annular mask. The annular mask has an annular slit with a width of 50 μm to 200 μm in the circumferential direction. A laser with a wavelength of 150 nm to 300 nm is used to irradiate the coating through the annular slit to break the main chain chemical bonds of the coating.
4. The method for forming the stripping edge of an optical fiber coating as described in claim 3, characterized in that: In the laser chain breaking step of the S1 coating, the laser and the optical fiber used rotate relative to each other in the circumferential direction for one revolution, with a rotation speed of 1 rpm to 10 rpm or an irradiation time of 5 s to 60 s. The laser used has a spot width of 50 μm to 200 μm and a power density of 10 mW / cm² to 100 mW / cm².
5. The method for forming the stripping edge of an optical fiber coating as described in claim 1, characterized in that: In the mechanical thinning step of the S2 coating layer N diamond cutting wires that can reciprocate radially around the optical fiber are used to form a scraping unit. The projections of the N diamond cutting wires on the axial direction of the optical fiber are located on the sides of a regular N-gon. The scraping unit and the optical fiber can rotate relative to each other in the circumferential direction, and the coating layer at the annular fracture zone is scraped by the diamond cutting line corresponding to the inscribed circle of the scraping unit. N is an integer greater than or equal to 3.
6. The method for forming the stripping edge of an optical fiber coating as described in claim 5, characterized in that: In the scraping unit, the diamond cutting line near the side of the coating layer to be retained is perpendicular to the optical fiber axis.
7. The method for forming the stripping edge of an optical fiber coating as described in claim 5, characterized in that: The diameter of the diamond cutting wire is 20 μm to 50 μm, the particle size of the diamond micro powder is 3 μm to 10 μm, the radial feed speed is 0.1 mm / s to 2 mm / s, and the tension is 2 N to 5 N.
8. A method for forming the stripping edge of an optical fiber coating as described in any one of claims 1, 5-7, characterized in that: In the mechanical thinning step of the S2 coating, the coating is scraped to a preset distance of 5 μm to 20 μm from the surface of the coating.
9. The method for forming the stripping edge of an optical fiber coating as described in claim 1, characterized in that: In the laser finishing step of the S3 coating, the laser and optical fiber used rotate relative to each other in the circumferential direction for one revolution, with a rotation speed of 1 rpm to 10 rpm or an irradiation time of 3 s to 30 s. The wavelength of the laser used is 150 nm to 300 nm, the spot width is 50 μm to 200 μm, and the power density is 5 mW / cm² to 50 mW / cm².
10. The method for forming a stripped edge of an optical fiber coating as described in claim 1, characterized in that: In the laser chain breaking step of the S1 coating layer and the laser finishing step of the S3 coating layer, the working distance of the laser used is ≤5mm.