Processing method of spherical lens optical fiber

Abstract

The invention discloses a processing method of a spherical lens optical fiber, which is characterized in that the spherical lens optical fiber is processed by fusing one end of a coreless optical fiber to form a segment, and the following relational expressions exist: # imgabs0 # imgabs1 # L is the length of the coreless optical fiber after fusing the segment along the axial direction of a single-mode optical fiber, and L0 is the axial length of the coreless optical fiber before fusing; r is the spherical radius of the segment; r is the cladding radius of the coreless optical fiber before melting; theta 1 is half of the divergence angle of the laser emitted from the single-mode fiber in the segment, and n is the refractive index of the cladding of the coreless fiber. The relation among the size of the coreless optical fiber before fusing, the size of the spherical segment formed by fusing and the laser divergence angle is limited, and laser cannot escape from the side face of the coreless optical fiber.

Description

Technical Field

[0001] The invention belongs to the field of optical devices, and more specifically, relates to a method for processing a spherical lens optical fiber. Background Art

[0002] Lens fiber is a key component of semiconductor lasers. Generally, a conical or cylindrical lens is processed on the end face of the fiber, and the laser is directly coupled into the fiber through the end lens. Compared with discrete lens coupling, the device structure is more compact.

[0003] For lens optical fibers used in lasers, the distance between the laser chip and the lens is generally only about 10um. A longer working distance requires a larger radius of curvature, so a spherical lens optical fiber is needed. Spherical lens optical fiber generally uses multimode optical fiber or other large-core optical fiber, which is suitable for higher-power application scenarios.

[0004] The curvature radius of the spherical lens optical fiber on the market is difficult to control. During the melting process, the internal components of the optical fiber diffuse, causing the light spot to deform abnormally. These factors make the effect of the spherical lens optical fiber unsatisfactory.

[0005] The patent "A method for making a spherical lens optical fiber" (application number 201010202407.4) fuses a multimode optical fiber or a coreless optical fiber at the end face of a single-mode optical fiber to melt a spherical lens. However, if the multimode optical fiber is melted, since the diameter of the core layer of the multimode optical fiber is relatively large and since its core layer and cladding have relatively obvious stratification, after the multimode optical fiber is melted, the materials of its core layer and cladding are mixed together, and the internal material components diffuse, resulting in material inhomogeneity, which can easily cause uneven light output, abnormal light beams, and poor light output quality. For the use of coreless optical fiber for melting, since there is no core-clad structure to form an optical waveguide, the light confinement ability is poor. When melting the coreless optical fiber to make a spherical lens optical fiber, the beam quality often decreases, and the transmission and focusing performance of the beam decreases, affecting the normal use of the laser. Summary of the invention

[0006] In view of the above defects or improvement needs of the prior art, the present invention provides a method for processing a spherical lens optical fiber, which limits the axial length of the coreless optical fiber before and after melting, establishes a geometric relationship between the axial length of the coreless optical fiber and the divergence angle of the coreless optical fiber and the spherical notch formed by melting, and can improve the light output quality and transmission quality of the laser of the processed spherical lens optical fiber, thereby solving the technical problems in the prior art of using coreless optical fiber to make spherical lens optical fiber, such as reduced beam quality, reduced transmission and focusing performance of the beam.

[0007] To achieve the above object, according to the present invention, a method for processing a spherical lens optical fiber is provided, wherein a spherical notch is formed by melting one end of a coreless optical fiber from which a coating layer is removed and fused to a single-mode optical fiber, thereby processing the spherical lens optical fiber, wherein the following relationship exists:

[0008]

[0009] in:

[0010] L is the length of the coreless fiber along the axial direction of the single-mode fiber after the spherical notch is melted out, L0 is the axial length of the coreless fiber before melting, R is the spherical radius of the spherical notch, r is the cladding radius of the coreless fiber before melting, θ1 is half of the divergence angle of the laser emitted from the single-mode fiber in the spherical notch, and:

[0011]

[0012] n0 is the refractive index of the core of the single-mode optical fiber, θ0 is half the divergence angle of the laser emitted from the core of the single-mode optical fiber in air, and λ is the wavelength of the laser light in the core of the single-mode optical fiber, ω is half the mode field diameter of the single-mode optical fiber, and n is the refractive index of the cladding of the coreless optical fiber.

[0013] Preferably, one end of the coreless optical fiber is cut flat or ground into a plane perpendicular to the axis of the coreless optical fiber by a cutting knife, and then the spherical notch is melted out of this end.

[0014] Preferably, one end of the coreless optical fiber is melted by discharging through two electrodes arranged opposite to each other, and the distances from the coreless optical fiber to the two electrodes are equal.

[0015] Preferably, the axis of the single-mode optical fiber is perpendicular to the line connecting the two electrodes, and while the two electrodes are discharging, the coreless optical fiber rotates around its own axis and feeds along its own axial direction to melt the end of the coreless optical fiber into a desired spherical notch.

[0016] Preferably, a beam quality analyzer is used to test the light-emitting spot of the spherical lens optical fiber online, and when the light-emitting spot reaches a set curvature radius, the two electrodes stop discharging and melting.

[0017] Preferably, the two electrodes adopt an intermittent discharge mode, that is, each time the discharge is performed, the coreless optical fiber rotates a set angle, and the coreless optical fiber intermittently rotates multiple full circles;

[0018] Alternatively, the two electrodes are discharged continuously and the coreless optical fiber is rotated continuously for multiple full revolutions.

[0019] Preferably, the spherical diameter of the spherical segment is 0.5 to 3 times the cladding diameter of the coreless optical fiber.

[0020] Preferably, the end of the coreless optical fiber to be melted is processed into a truncated cone shape.

[0021] Preferably, an optical fiber clamp is used to clamp the single-mode optical fiber and / or the coreless optical fiber.

[0022] Preferably, the diameter of the single-mode optical fiber is equal to the outer diameter of the coreless optical fiber.

[0023] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0024] The present invention discloses a method for processing a spherical lens optical fiber. After a coreless optical fiber is fused onto a single-mode optical fiber, the end of the coreless optical fiber is burned into a desired spherical notch. Since the coreless optical fiber does not have obvious stratification such as a core layer and a cladding layer as the single-mode optical fiber and the multi-mode optical fiber, the material of the spherical notch is uniform after the burning process to form the spherical notch, which can avoid direct burning of the single-mode optical fiber or burning of the multi-mode optical fiber so that different components inside diffuse to form uneven materials and cause abnormal light beams.

[0025] In addition, by melting out the spherical notch to produce a spherical lens optical fiber, the laser will gradually diffuse when entering the coreless optical fiber, while the present invention limits the relationship between the axial length of the coreless optical fiber before and after melting and the spherical radius of the spherical notch and the radius of the coreless optical fiber itself, and also considers the influence of the divergence angle of the laser emitted from the single-mode optical fiber into the spherical notch, and accurately associates and limits the relationship between the size of the coreless optical fiber before and after melting and the divergence angle, so that the laser will not escape from the side of the coreless optical fiber, especially from the unmelted section of the coreless optical fiber, so as not to reduce the light transmission power and cause power loss, thereby solving the problems of reduced beam quality, poor transmission and focusing of the beam existing in the spherical lens optical fiber in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of processing spherical lens optical fiber on the production line;

[0027] Figure 2 This is a schematic diagram of the processed spherical lens optical fiber emitting laser. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0029] Reference Figure 1 , Figure 2 , a method for processing a spherical lens optical fiber, wherein one end of a coreless optical fiber 5 having a coating removed and fused to a single-mode optical fiber 1 is melted into a spherical segment to produce the spherical lens optical fiber (refer to Figure 1The spherical structure formed by melting is actually a spherical segment. When calculating the following relationship, the spherical segment is treated as a complete sphere). The axis of the single-mode optical fiber 1 passes through the center of the spherical segment. The coreless optical fiber 5 uses acrylic resin to form a coating layer, solid quartz to form a cladding layer, and has no core layer. Before melting the coreless optical fiber, the coating layer of the coreless optical fiber needs to be removed, and only the cladding layer of the coreless optical fiber remains.

[0030] Reference Figure 2 , through n0sinθ0=nsinθ1 and Calculate θ1:

[0031] Calculate θ2 using the refraction formula n = sin(θ1+θ2) / sinθ2: θ2 is an intermediate variable, obtained through θ1;

[0032] Using the triangle side length formula, we can obtain L≤R×sinθ2 / sinθ1+R;

[0033] The axial length of the coreless optical fiber 5 before melting is calculated by taking into account the unchanged volume of the spherical segment before and after melting, and obtaining

[0034] in:

[0035] L is the axial length of the coreless optical fiber 5 after the spherical notch is melted out along the single-mode optical fiber 1, and L0 is the axial length of the coreless optical fiber 5 before melting;

[0036] R is the radius of the spherical segment, that is, the radius of the complete sphere after the spherical segment is supplemented into a complete sphere;

[0037] r is the cladding radius of the coreless optical fiber 5 before melting;

[0038] θ1 is half of the divergence angle of the laser emitted from the single-mode optical fiber 1 in the spherical segment;

[0039] n0 is the refractive index of the core of the single-mode optical fiber 1, θ0 is half the divergence angle of the laser emitted from the core of the single-mode optical fiber 1 in the air, and λ is the wavelength of the laser light in the core of the single-mode optical fiber 1 , ω is half the mode field diameter of the single-mode optical fiber 1 , and n is the refractive index of the cladding of the coreless optical fiber 5 .

[0040] See also Figure 2 The arrowed line in the middle is the laser beam emitted after being transmitted and diverged in the coreless optical fiber 5. The laser beam emitted from the single-mode optical fiber 1 covers a part of the surface of the spherical segment (this part of the surface is actually a spherical cap), and the half of the arc angle obtained by the plane passing through the axis of the single-mode optical fiber 1 to cut this part of the surface (the spherical segment) is γ, γ = θ1 + θ2, so n = sinγ / sinθ2.

[0041] If a coreless optical fiber is fused to a single-mode optical fiber and the size of the coreless optical fiber after melting is not restricted, the laser will also leak out from the side of the coreless optical fiber, especially from the unmelted cylindrical part of the coreless optical fiber, causing the transmitted light power to be lower than the preset value. As for the problem of laser leakage from the side of the coreless optical fiber and how to prevent the laser from leaking from the side of the coreless optical fiber, the present invention restricts the dimensional relationship of the coreless optical fiber 5 before and after melting, and considers the influence of the divergence angle in the spherical notch, so that the laser will not escape from the side of the coreless optical fiber 5, especially from the unmelted section of the coreless optical fiber. The present invention can accurately control the melting of the coreless optical fiber 5 by restricting the dimensional parameter relationship of the coreless optical fiber 5 before and after melting, thereby preventing light from leaking from the side of the coreless optical fiber 5.

[0042] Furthermore, one end of the coreless optical fiber 5 is cut flat or ground into a plane perpendicular to the axis of the coreless optical fiber 5 by a cutting knife, and then sintered to facilitate regular flow of materials to form the spherical segment.

[0043] Furthermore, one end of the coreless optical fiber 5 is melted by discharging two electrodes 3 arranged opposite to each other, and the distance between the coreless optical fiber 5 and the two electrodes 3 is equal, which is easy to operate and process, and is convenient for manufacturing a spherical segment with a large radius.

[0044] Furthermore, the axis of the single-mode optical fiber 1 is perpendicular to the line connecting the two electrodes 3, and while the two electrodes 3 are discharging, the coreless optical fiber 5 rotates around its own axis and feeds along its own axial direction to melt the end of the coreless optical fiber 5 into the required spherical notch.

[0045] Furthermore, the light spot of the spherical lens optical fiber is tested online using a beam quality analyzer 4. When the light spot reaches a set curvature radius, the electrode 3 stops discharging and melting. Therefore, the radius of the spherical notch can be calculated by the size of the light spot, thereby conveniently and accurately controlling the size of the spherical notch.

[0046] Furthermore, the two electrodes 3 adopt an intermittent discharge mode, that is, each time the discharge occurs, the coreless optical fiber 5 rotates a set angle, and ensures that the coreless optical fiber 5 rotates multiple full circles. The intermittent discharge allows the discharge device to pause for heat dissipation, thereby extending the service life of the discharge device.

[0047] Alternatively, the two electrodes 3 adopt a continuous discharge mode to continuously rotate the coreless optical fiber 5 for multiple full circles; if the discharge device has good heat dissipation, the discharge can be connected to improve the processing efficiency.

[0048] Both of the above-mentioned two discharge modes can ensure discharge uniformity, so that the outer surface quality of the formed spherical segment is good.

[0049] Furthermore, the diameter of the spherical segment is 0.5 to 3 times the cladding diameter of the coreless optical fiber 5. When light is output through a large radius of curvature, it has a longer focal length, reaching the millimeter level, and is more suitable for long focal length imaging and coupling applications.

[0050] Furthermore, the end of the coreless optical fiber 5 to be melted is processed into a truncated cone shape to remove the edge damage during cutting, which is more suitable for making a spherical lens with a smaller diameter.

[0051] Furthermore, the optical fiber clamp 2 is used to clamp the single-mode optical fiber 1 and / or the coreless optical fiber 5, so as to facilitate the rotation and feeding of the coreless optical fiber 5 to form the spherical segment.

[0052] Therefore, on the production line, components such as the optical fiber clamp 2, the electrode 3 and the beam quality analyzer 4 are needed, and the optical fiber clamp 2 also needs to be able to rotate around the axis of the single-mode optical fiber 1 and feed along the axial direction of the single-mode optical fiber 1.

[0053] Furthermore, the diameter of the single-mode optical fiber 1 is equal to the outer diameter of the coreless optical fiber 5 , which facilitates fusion splicing and also facilitates the transmission of laser light from the single-mode optical fiber 1 to the coreless optical fiber 5 .

[0054] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for processing a spherical lens optical fiber, wherein a spherical notch is formed by melting one end of a coreless optical fiber from which a coating layer has been removed and fused to a single-mode optical fiber, thereby processing the spherical lens optical fiber, wherein: The following relationship exists: in: L is the length of the coreless fiber along the axial direction of the single-mode fiber after the spherical notch is melted out, L0 is the axial length of the coreless fiber before melting, R is the spherical radius of the spherical notch, r is the cladding radius of the coreless fiber before melting, θ1 is half of the divergence angle of the laser emitted from the single-mode fiber in the spherical notch, and: n0 is the refractive index of the core of the single-mode optical fiber, θ0 is half the divergence angle of the laser emitted from the core of the single-mode optical fiber in air, and λ is the wavelength of the laser light in the core of the single-mode optical fiber, ω is half the mode field diameter of the single-mode optical fiber, and n is the refractive index of the cladding of the coreless optical fiber.

2. The method for processing a spherical lens optical fiber according to claim 1, characterized in that: One end of the coreless optical fiber is cut flat or ground into a plane perpendicular to the axis of the coreless optical fiber by a cutting knife, and then the spherical notch is melted out of this end.

3. The method for processing a spherical lens optical fiber according to claim 1, characterized in that: One end of the coreless optical fiber is melted by discharging through two electrodes arranged opposite to each other, and the distances from the coreless optical fiber to the two electrodes are equal.

4. The method for processing a spherical lens optical fiber according to claim 3, characterized in that: The axis of the single-mode optical fiber is perpendicular to the line connecting the two electrodes, and while the two electrodes are discharging, the coreless optical fiber rotates around its own axis and feeds along its own axial direction to melt the end of the coreless optical fiber into a desired spherical notch.

5. The method for processing a spherical lens optical fiber according to claim 3, characterized in that: The light spot of the spherical lens optical fiber is tested online using a beam quality analyzer, and when the light spot reaches the set curvature radius, the two electrodes stop discharging and melting.

6. The method for processing a spherical lens optical fiber according to claim 3, characterized in that: The two electrodes adopt an intermittent discharge mode, that is, each time the discharge is performed, the coreless optical fiber rotates a set angle, and the coreless optical fiber intermittently rotates multiple full circles; Alternatively, the two electrodes are discharged continuously, and the coreless optical fiber is rotated continuously for multiple full revolutions.

7. The method for processing a spherical lens optical fiber according to claim 1, characterized in that: The spherical diameter of the spherical segment is 0.5 to 3 times the cladding diameter of the coreless optical fiber.

8. The method for processing a spherical lens optical fiber according to claim 1, characterized in that: One end of the coreless optical fiber to be melted is processed into a truncated cone shape.

9. The method for processing a spherical lens optical fiber according to claim 1, characterized in that: The single-mode optical fiber and / or the coreless optical fiber is clamped by using an optical fiber clamp.

10. The method for processing a spherical lens optical fiber according to claim 1, characterized in that: The diameter of the single-mode optical fiber is equal to the outer diameter of the coreless optical fiber.

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