A method of making a fiber optic connector and a fiber optic ferrule

Abstract

The application provides a fiber connector and a fiber ferrule preparation method. The connector comprises a first fiber connector, a second fiber connector and an adapter pair. The first fiber connector comprises a first fiber ferrule with a central axis through hole structure, and a first fiber can pass through the first fiber ferrule. The second fiber connector comprises a second fiber ferrule with a central axis through hole structure, and a second fiber can pass through the second fiber ferrule. The two adapters in the adapter pair are used to realize the butt joint of the first fiber and the second fiber inside the adapter pair. The head of the first fiber ferrule comprises a first fiber limiting structure, which is used to fix the head of the first fiber in the first fiber ferrule, and / or the head of the second fiber ferrule comprises a second fiber limiting structure, which is used to fix the head of the second fiber in the second fiber ferrule, so as to reduce the fiber butt joint loss and improve the coupling efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical fiber assemblies, and more particularly, to an optical fiber connector and a method for preparing a fiber optic ferrule. BACKGROUND

[0002] Hollow core fiber is a waveguide with an air core, a microstructure arranged in the cladding, and a cross section extending longitudinally, which performs long-distance flexible light transmission in air medium (also known as hollow microstructure fiber or hollow photonic crystal fiber). Currently, there are mainly two types of light guiding types of hollow core fiber: photonic bandgap type and anti-resonance type. Unlike the total internal reflection guiding mechanism of traditional solid core fiber, the photonic bandgap type hollow core fiber is based on the photonic bandgap effect, and the anti-resonance type hollow core fiber is based on the anti-resonance reflection effect. Compared with traditional optical fiber, hollow core fiber has the characteristics of low delay, high damage threshold, weak nonlinearity, low dispersion, and potential ultra-low loss, and has important application prospects in optical fiber communication, light and gas or liquid interaction, optical fiber sensing, high-power laser transmission, pulse compression, etc.

[0003] Currently, the connection technologies for hollow core fiber mainly include hot fusion technology, fiber array butt joint technology, and fiber connector technology. However, these technologies either damage the microstructure of the hollow core fiber itself, or cannot be repeatedly plugged and used, or lack the adjustment freedom to improve the alignment efficiency, or require expensive fusion / connection equipment. These shortcomings result in large insertion loss of the hollow core fiber connector in actual use, which cannot be plug-and-play, and cannot reduce the cost. SUMMARY

[0004] The present application provides an optical fiber connector and a method for preparing a fiber optic ferrule, which proposes a fiber connector preparation technology based on a ferrule with a limiting structure in the head and a multi-key groove, circumferential angle rotation adjustable fiber connector, which can not pollute and damage the end face of the optical fiber during the preparation of the connector, and at the same time, the transverse offset of the two optical fibers to be connected is controlled at a low level, thereby realizing low-loss, pluggable, and low-cost connection of the hollow core fiber to another hollow core fiber or another solid core fiber.

[0005] In a first aspect, a fiber connector is provided, comprising: a first fiber connector, a second fiber connector, and an adapter pair, the first fiber connector comprising a first fiber ferrule having a central axis through hole structure, a first fiber being capable of passing through the first fiber ferrule; the second fiber connector comprising a second fiber ferrule having a central axis through hole structure, a second fiber being capable of passing through the second fiber ferrule; the adapter pair being fixed by a first adapter and a second adapter being oppositely connected, the two adapters in the adapter pair being used for plugging the first fiber connector and the second fiber connector, so that the first fiber and the second fiber are connected in the adapter pair, wherein a head of the first fiber ferrule comprises a first fiber limiting structure for fixing the head of the first fiber in the first fiber ferrule, and / or a head of the second fiber ferrule comprises a second fiber limiting structure for fixing the head of the second fiber in the second fiber ferrule.

[0006] In the present application, the first fiber connector can adopt the scheme provided in the present application, the second fiber connector can adopt the connector in the prior art, or both the first connector and the second connector adopt the scheme provided in the present application, which is not limited.

[0007] Based on the above technical scheme, the fiber connector provided in the present application can fix the head of the fiber, thereby reducing the connection loss (also known as insertion loss) of the fiber when connected.

[0008] In combination with the first aspect, in some embodiments of the first aspect, the first fiber limiting structure and / or the second fiber limiting structure is a groove structure of the head of the fiber ferrule along the central axis direction, the groove structure being used for accommodating a material having a bonding property, so as to fix the head of the fiber in the fiber ferrule.

[0009] Based on the above technical scheme, the limiting structure in the present application can be a groove structure of the head of the fiber ferrule, the groove structure can fix the head of the fiber in the ferrule by accommodating a material having a bonding property, thereby reducing the connection loss of the fiber when connected.

[0010] In some embodiments of the first aspect, the first fiber connector is provided with a first key, the first adapter of the adapter pair is provided with a first component for fixing the first fiber connector, and the first component is provided with at least two first key grooves on the side wall of the first component, and the first key can be inserted into each of the at least two first key grooves, and the at least two first key grooves are distributed along the circumference of the first component, and / or the second fiber connector is provided with a second key, the second adapter of the adapter pair is provided with a second component for fixing the second fiber connector, and the second component is provided with at least two second key grooves on the side wall of the second component, and the second key can be inserted into each of the at least two second key grooves, and the at least two second key grooves are distributed along the circumference of the second component.

[0011] Based on the above technical solution, the fiber connector provided in the present application can reduce the connection loss of the fiber when being connected by fixing the fiber head and switching the key groove, and can significantly improve the coupling efficiency of the hollow fiber. Moreover, the adapter can realize the repeated plugging connection between the fibers, without the need for complex processes and equipment, thereby reducing the manufacturing cost and improving the work efficiency.

[0012] In some embodiments of the first aspect, the first adapter and the second adapter of the adapter pair are connected together through the flanges of the respective outer edges.

[0013] Based on the above technical solution, the adapters in the present application can be connected together through the flanges, and can be disassembled and fixed again.

[0014] In some embodiments of the first aspect, the fiber in the fiber connector comprises a microstructured fiber.

[0015] The "microstructured fiber" in the present application can refer to various fibers with a cladding containing air holes, and the core thereof can be solid or air. For example, hollow microstructured fiber (also known as hollow fiber), solid microstructured fiber.

[0016] Based on the above technical solution, the connection between the microstructured fibers (for example, hollow fibers) can be realized in the present application, the connection loss of the microstructured fibers when being connected can be reduced, and the coupling efficiency can be improved.

[0017] In some embodiments of the first aspect, if the fiber in the fiber ferrule is a full solid fiber, the end face of the full solid fiber can be polished and coated with an anti-reflection film.

[0018] The "full solid fiber" in the present application can refer to a fiber with a solid cladding and a solid core, for example, a solid core silica fiber.

[0019] Based on the above technical solution, the application can further reduce the reflection of the interface between the hollow optical fiber and the all-solid optical fiber, and improve the coupling efficiency of the optical fiber butt joint by polishing the end face of the all-solid optical fiber ferrule and coating an anti-reflection film.

[0020] In a second aspect, a method for preparing an optical fiber ferrule is provided, which includes: obtaining a ferrule with a groove structure at a head portion; inserting an optical fiber into the ferrule; flattening the end face of the optical fiber that is inserted out of the ferrule; coating a material with adhesive properties on the side of the optical fiber that is inserted out of the ferrule; the groove structure accommodates the material with adhesive properties, and after the adhesive is cured, the head portion of the optical fiber is fixed in the optical fiber ferrule.

[0021] Based on the above technical solution, the optical fiber ferrule prepared in the application can stably fix the head portion of the optical fiber and reduce the connection loss. Compared with the prior art, which needs to polish the end face of the ceramic ferrule and remove the glue, the technical solution provided in the application does not damage and contaminate the end face of the head portion of the hollow optical fiber, and does not need to remove the glue. That is, the microstructure of the hollow optical fiber itself is not damaged, and the connection loss is reduced.

[0022] In combination with the second aspect, in some embodiments of the second aspect, the method further includes: flattening the end face of the head portion of the optical fiber and the end face of the outer edge of the head portion of the ferrule, so that the groove structure accommodates the material with adhesive properties.

[0023] Based on the above technical solution, the material with adhesive properties can be made to fall into the groove structure along the side of the optical fiber by pulling (or pushing) the optical fiber, so as to fix the head portion of the optical fiber and reduce the connection loss.

[0024] In combination with the second aspect, in some embodiments of the second aspect, the optical fiber includes: a microstructured optical fiber.

[0025] In combination with the second aspect, in some embodiments of the second aspect, if the optical fiber is an all-solid optical fiber, the method further includes: polishing the end face of the all-solid optical fiber ferrule and coating an anti-reflection film.

[0026] In a third aspect, a fiber connector is provided, comprising: a first fiber ferrule, a second fiber ferrule, and a ferrule matching sleeve, wherein a first optical fiber is packaged in the first fiber ferrule, a second optical fiber is packaged in the second fiber ferrule, the ferrule matching sleeve is used to connect and hold the first fiber ferrule and the second fiber ferrule, so that the first optical fiber and the second optical fiber are butted, the first fiber ferrule and the second fiber ferrule can be rotated at any angle in the circumferential direction in the ferrule matching sleeve, wherein a head portion of the first fiber ferrule comprises a first fiber limiting structure used to fix the head portion of the first optical fiber in the first fiber ferrule, and / or a head portion of the second fiber ferrule comprises a second fiber limiting structure used to fix the head portion of the second optical fiber in the second fiber ferrule.

[0027] Based on the above technical solution, the fiber connector (which can be referred to as a circumferential full-angle adjustable fiber connector) provided in the present application removes the above-mentioned fiber connector and multi-key groove adapter pair, and only retains the fiber ferrule in the fiber connector and the ferrule matching sleeve inside the multi-key groove adapter pair, which makes the rotation adjustment of the fiber connector no longer limited by the number of keys on the adapter pair, and the two connected optical fibers can be rotated at a full angle in the circumferential direction, so that the transverse offset between the two connected optical fibers can be further reduced. Moreover, the head portion of the optical fiber is fixed, which can reduce the connection loss and improve the coupling efficiency of the optical fiber butt joint. In addition, the fiber connector greatly reduces the volume and weight of the connector.

[0028] In combination with the third aspect, in some embodiments of the third aspect, the first fiber limiting structure and / or the second fiber limiting structure is a groove structure in the direction of the central axis, which is used to accommodate the material with adhesive properties, so as to fix the head portion of the optical fiber in the fiber ferrule.

[0029] Based on the above technical solution, the circumferential full-angle adjustable fiber connector provided in the present application can accommodate the material with adhesive properties by designing the head portion groove structure, so as to fix the head portion of the optical fiber in the fiber ferrule and reduce the connection loss.

[0030] In combination with the third aspect, in some embodiments of the third aspect, the optical fiber in the fiber ferrule comprises a microstructured optical fiber.

[0031] Based on the above technical solution, the circumferential full-angle adjustable fiber connector provided in the present application can realize the butt joint of microstructured optical fibers, reduce the connection loss when the microstructured optical fibers are butt jointed, and improve the coupling efficiency.

[0032] In combination with the third aspect, in some embodiments of the third aspect, if the optical fiber in the fiber ferrule is a full solid optical fiber, the end face of the full solid optical fiber ferrule can be polished and coated with an anti-reflection film.

[0033] Based on the above technical solution, in the circumferential full-angle adjustable optical fiber connector provided by the application, the end face of the full solid optical fiber ferrule is polished and coated with an anti-reflection film, which can further reduce the reflection at the interface between the hollow optical fiber and the full solid optical fiber, and improve the coupling efficiency of the optical fiber butt joint. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is a schematic diagram of the head groove type optical fiber ferrule provided by the application.

[0035] Figure 2 is a schematic diagram of the optical fiber ferrule preparation method provided by the application.

[0036] Figure 3 is a schematic diagram of the optical fiber ferrule preparation process provided by the application.

[0037] Figure 4 is a structure of the multi-key groove optical fiber adapter pair and the optical fiber connector provided by the application.

[0038] Figure 5 is a schematic diagram of the connection method of the optical fiber connector and the adapter pair provided by the application.

[0039] Figure 6 is a connection state real object diagram of the optical fiber connector and the adapter pair provided by the application.

[0040] Figure 7 is a scanning electron microscope diagram of the hollow optical fiber used in the application.

[0041] Figure 8 is a microscope photo of the preparation process of the hollow optical fiber ceramic ferrule.

[0042] Figure 9 is the actual measurement result of the butt joint of the hollow optical fiber and the hollow optical fiber.

[0043] Figure 10 is a photo of the fusion of the solid core single mode optical fiber and the graded index multimode optical fiber.

[0044] Figure 11 is an end face microscope photo of the prepared hollow optical fiber ceramic ferrule.

[0045] Figure 12 is a preparation process and an end face microscope photo of the solid core single mode optical fiber ceramic ferrule fused with the graded index multimode optical fiber.

[0046] Figure 13are the mode field imaging diagrams of the hollow core fiber and the single mode fiber before and after the mode field expansion.

[0047] Figure 14 are the back reflection spectra of the solid core fiber before and after the anti-reflection film coating.

[0048] Figure 15 are the photos of the circumferential full-angle adjustable fiber connector provided in the present application. DETAILED DESCRIPTION

[0049] The technical solutions in the present application will be described below in combination with the drawings.

[0050] Before introducing the technical solutions in the present application, first, the basic devices used for connecting the optical fibers will be briefly introduced.

[0051] The optical fiber connectors are generally connected through a pair of adapters. The two adapters can be connected together through the flanges on the outer edges of the adapters to form a pair of adapters. The optical fiber connectors include fiber ferrules with central axis through hole structures, and the optical fibers can pass through the fiber ferrules. The pair of adapters is internally provided with a ferrule matching sleeve, and the two adapters in the pair of adapters can be inserted into the fiber ferrules, that is, the optical fibers are connected in the pair of adapters. Generally, the fiber ferrules in the optical fiber connectors are ceramic ferrules.

[0052] The insertion loss of the optical fiber connector refers to the optical power loss caused by the optical fiber connector to the optical fiber link connected through the pair of adapters. This loss is mainly caused by the geometric misalignment between the two connected optical fibers, the mismatch of the optical mode field, and the reflection on the interface of different optical fiber materials. In the case of matching the optical fiber mode field, if the two connected optical fibers are arranged in a straight line, that is, the lateral offset and the tilt angle of the two connected optical fibers are zero, the insertion loss is the smallest. However, in actual application, when the two optical fiber connectors are connected, there is inevitably a lateral offset and a slight angular tilt between them, which is mainly caused by the fact that the inner diameter of the through hole of the fiber ferrule is slightly larger than the outer diameter of the optical fiber, resulting in that the optical fiber is not coaxial with the ceramic ferrule.

[0053] The optical fiber connector and the preparation method of the fiber ferrule in the present application will be introduced first.

[0054] It should be noted that the technical solutions in the present application are applicable to various types of optical fibers in the prior art, and of course, are also applicable to “microstructured optical fibers”. The “microstructured optical fiber” in the present application can refer to various optical fibers with air holes in the cladding, and the core can be solid or air. For example, hollow microstructured optical fiber (also known as hollow core fiber), solid core microstructured optical fiber. The “full solid optical fiber” in the present application can refer to an optical fiber with solid cladding and core, for example, solid core silica optical fiber.

[0055] The following embodiments in the present application are exemplified by taking the optical fiber ferrule as a ceramic ferrule. For other types of optical fiber ferrules, such as glass ferrules, metal ferrules, etc., their structures and preparation methods are similar, and also fall within the protection scope of the present application.

[0056] The following embodiments in the present application are exemplified by taking the optical fiber as an "hollow core fiber". For other types of optical fibers, the technical solutions of the present application are also applicable, and also fall within the protection scope of the present application.

[0057] The "hollow core fiber" mentioned in the present embodiment can be various types of hollow core fibers, such as photonic bandgap type hollow core fiber, anti-resonant type hollow core fiber, without limitation.

[0058] The head of the optical fiber ferrule provided by the present application comprises a limiting structure for fixing the head of the optical fiber in the optical fiber ferrule. As an example, Figure 1 is a schematic diagram of the optical fiber ceramic ferrule provided by the present application. In this example, the optical fiber limiting structure is a groove structure in the head of the optical fiber ferrule along the central axis direction, which can be used to accommodate materials with adhesive properties (such as glue, ultraviolet curing glue, etc.) to fix the head of the optical fiber in the optical fiber ferrule. Optionally, the tail of the ceramic ferrule can also have a groove to facilitate the insertion of the hollow core fiber into the ceramic ferrule.

[0059] Figure 2 is a schematic diagram of the preparation method of the hollow core fiber ceramic ferrule provided by the present application. As an example, in the present application, the head of the ceramic ferrule has a groove. First, the hollow core fiber can be inserted from the tail of the ceramic ferrule and pulled out from the head, then the end face of the head of the hollow core fiber pulled out of the ceramic ferrule is cut flat, and the material with adhesive properties (such as ultraviolet curing glue) is coated on the side of the hollow core fiber, then the end face of the head of the optical fiber is taken flat with the end face of the outer edge of the head of the ceramic ferrule (for example, the hollow core fiber can be pulled back from the tail of the ceramic ferrule), so that the groove structure accommodates the material with adhesive properties (for example, the ultraviolet curing glue can enter the groove along the side of the hollow core fiber pulled back (or pushed forward)), and after the adhesive curing (for example, the glue is cured by using ultraviolet light), the hollow core fiber is fixed in the ceramic ferrule. In the present embodiment, the amount of ultraviolet curing glue can be controlled during the process, so that the glue does not overflow the groove, avoiding the pollution of the end face of the hollow core fiber, that is, the microstructure of the hollow core fiber itself is not damaged, and the connection loss is reduced.

[0060] Specifically, the preparation process of the hollow core fiber ceramic ferrule is as follows Figure 3As shown. As an example, first, a ceramic ferrule with a grooved head is selected or prepared. The hollow fiber is inserted into the ceramic ferrule from the tail and exits from the head. Next, the end face of the hollow fiber exiting the ceramic ferrule is flattened, as shown. Figure 3 As shown in (a) above. A small amount of UV-curable adhesive is applied to the side of the hollow fiber. Then, the hollow fiber is pulled from the tail end of the ceramic ferrule, drawing the adhesive into the groove at the head of the ceramic ferrule, as shown. Figure 3 As shown in (b) above. Finally, after the end face of the hollow fiber is flush with the end face of the ceramic ferrule head, the adhesive is cured using ultraviolet light, and the hollow fiber is fixed in the ceramic ferrule, as shown in (b). Figure 3 As shown in (c) above. The hollow-core fiber ceramic ferrule prepared according to this method can stably fix the hollow-core fiber head. Furthermore, compared to existing technologies that require polishing and removing adhesive from the fiber end face of the ceramic ferrule, the technical solution provided in this application does not damage or contaminate the hollow-core fiber head end face, and therefore does not require adhesive removal. That is, it does not damage the microstructure of the hollow-core fiber itself, thus reducing connection loss.

[0061] The fiber optic adapter pair provided in this application (e.g., the adapter pair includes adapter #A and adapter #B) has a first component for fixing a fiber optic connector on each adapter. At least two first keyways are provided on the sidewall of the first component, and these at least two first keyways are distributed circumferentially along the first component. The fiber optic connector in this application has a first key that can be embedded in each of the at least two first keyways.

[0062] As an example, Figure 4 This is a schematic diagram of the structure of the multi-keyway adapter pair and fiber optic connector provided in this application, as shown below. Figure 4 As shown in (a) in this embodiment, the two adapters of the adapter pair each have m and n keyways (m and n are integers greater than 1, where m and n can be equal or unequal). Therefore, the fiber connectors on the left and right sides can be rotated m and n positions respectively. By rotating, the lateral offset between the connected fibers can be reduced, thereby improving the fiber coupling efficiency. Figure 4 (b) is a structural schematic diagram of an optical fiber connector provided in this application, as shown in Figure 1. Figure 4As shown in (b) of FIG. 1, the fiber connector #B contains a fiber ceramic ferrule #B with a central axis hole structure, the hollow core fiber can pass through the fiber ceramic ferrule, and the fiber connector #B is provided with a key #B. Correspondingly, the structure of the fiber connector #A is similar to that of the fiber connector #B, which will not be described again. Among them, each ceramic ferrule can be inserted into the ferrule matching pipe in each adapter, and the two adapters in the adapter pair are used for plugging the two fiber connectors to realize the butt joint of the hollow core fiber and the solid core fiber inside the adapter pair. In this application, the left and right adapters of the adapter pair can also be connected together through the flanges on the outer edges. As described above, according to the method of the embodiment, the repeated pluggable connection between the fibers can also be realized.

[0063] The application also provides a connection method for reducing the transverse offset of the fiber, as shown in Figure 5 After the preparation of the hollow core fiber connector and the multi-key groove fiber adapter pair is completed, the tail of each fiber connector to be butt jointed is connected to a light source and an optical power meter respectively, and then the two fiber connectors are inserted into different key grooves of the fiber adapter pair. The size of the output optical power of the fiber connector when connecting different key grooves is measured by the optical power meter, and when the optical power is maximum, the two fiber connectors and the adapter pair can be fixed.

[0064] As an example, as shown in Figure 6 The tail of the fiber #A is connected to a light source; the tail of the fiber #B is connected to an optical power meter. First, randomly select a key groove on the left side of the adapter pair, insert the connector of the fiber #A into the key groove and fix it with a nut. Then, insert the connector of the fiber #B into different key grooves on the right side of the adapter pair respectively, and record the optical power value when inserting each key groove. Then, change the key groove of the fiber #A connector and fix it again, and then insert the fiber #B connector into different key grooves on the right side of the adapter pair respectively, and record the optical power value when inserting each key groove. Finally, select the left and right key groove positions with the maximum optical power value, and finally fix the two fiber connectors to realize the butt joint of the fibers.

[0065] Assuming that the distances between the fiber core and the central axis of the ceramic ferrule of the two fiber connectors prepared in this embodiment are d and d', respectively, the maximum transverse misalignment distance that can occur during mating is d+d', which can be greatly reduced by the above-mentioned rotation and switching key slot method, and the minimum transverse misalignment distance that can be adjusted is |d-d'|. The more the number of adapter key slots on the left and right sides (i.e., the larger m and n), the more likely the transverse offset of the fiber in the fiber connector is reduced to a minimum, i.e., the higher the efficiency of fiber mating. The fiber adapter in the current technology has only one key slot on each side, so the transverse offset of the fiber in the fiber connector (0~2d) occurs randomly and cannot be adjusted. The hollow fiber connector, multi-key slot adapter pair, and connection method of the hollow fiber connector and the multi-key slot adapter pair provided by the present application can solve the problem of unadjustable transverse offset during the preparation of the hollow fiber connector and the fiber mating process, and can significantly improve the coupling efficiency of the hollow fiber. In addition, the hollow fiber connection method proposed by the present application is convenient and fast, low in time consumption, and can realize repeated plugging and unplugging without complex processes and equipment, thereby reducing the manufacturing cost and improving the work efficiency.

[0066] The above technical solution can be applied to the connection between hollow fibers, and also to the connection between solid quartz fibers (single-mode, multi-mode, and large-mode field) and fibers made of different materials (e.g., sapphire fibers, soft glass fibers, and plastic fibers).

[0067] As an example, the technical solution of the present application can be applied to the connection between hollow fibers. Specifically, a hollow anti-resonant fiber with an outer diameter of 210 µm is selected in this embodiment, and the end face structure thereof is as shown in Figure 7 A batch of fiber ceramic ferrules with a hole diameter of about 220 µm can be purchased. Since the tail of the ceramic ferrule originally has a groove (which can also be understood as "funnel-shaped"), for the sake of convenience, the ceramic ferrule can be used upside down, i.e., the ceramic ferrule with a groove at the head. First, the above-mentioned hollow fiber is inserted into the inverted ceramic ferrule, then the end face of the hollow fiber protruding out of the ceramic ferrule is cut flat, then the ceramic ferrule is fixed, and the end face and side face of the ceramic ferrule are observed in real time under an optical microscope using two charge coupled devices (CCD) cameras, for example, the end face and side face of the ceramic ferrule at this time are as shown in Figure 8 (a) of 8 (b). Then, a small amount of ultraviolet curing glue is adhered to the side face of the hollow fiber protruding out of the ceramic ferrule, as shown in Figure 8 (c) of 8. Then, the fiber is pulled down using a precision displacement platform, so that the glue flows into the groove of the ceramic ferrule along the side face of the hollow fiber, and the pulling of the hollow fiber continues until the end face of the hollow fiber is flush with the outer edge end face of the ceramic ferrule, and the process is as shown in Figure 8As shown in (d) and (e) in the diagram. Next, the UV-curing adhesive is cured using UV light. At this point, the hollow fiber is fixed in the ceramic ferrule, and the end face of the fixed hollow fiber ceramic ferrule is as shown in the diagram. Figure 8 As shown in (f), the hollow-core fiber ceramic ferrule is finally assembled into the fiber optic connector. After the hollow-core fiber optic connector is prepared, a multi-keyboard adapter is used to connect the two hollow-core fiber optic connectors. For example, the two connected hollow-core fiber optic connectors can be inserted into different keyboards on both sides of the adapter pair, and the optical power of the hollow-core fiber optic connectors inserted into different keyboards of the adapter can be measured and recorded. When the optical power reaches its maximum, the connector and the adapter pair can be fixed with a nut.

[0068] Figure 9 (a) shows the experimental results of connecting hollow-core optical fibers using the above method. It can be seen that by selecting a suitable keyway position, the lateral offset (loss) between the two connected hollow-core optical fibers can be reduced. The highest coupling efficiency between the hollow-core optical fibers obtained in the experiment was 97%, i.e., the connection loss was 0.13 dB. As described above, the technical solution provided in this application can also achieve reusable insertion and removal, such as... Figure 9 Figure (b) shows the experimental results of 10 repeated insertions and removals of the hollow fiber connector described above. It can be seen that after multiple insertions and removals of the connector, the coupling efficiency between the hollow fibers can still be maintained above 95%.

[0069] As another example, the technical solution of this application can be applied to the connection between hollow-core optical fiber and solid-core single-mode fiber (SMF). Specifically, the hollow-core optical fiber can continue to use, as... Figure 7 The hollow-core antiresonant fiber shown can be replaced with a solid-core single-mode fiber, such as SMF-28. The hollow-core fiber has a mode field diameter of approximately 20 µm at 1550 nm, while the SMF-28 has a mode field diameter of approximately 10 µm at the same wavelength. The coupling loss introduced solely by the mode field diameter mismatch is approximately 2 dB. Therefore, the mode field of the fiber needs to be shaped to match the mode field diameters of both fibers to reduce connection loss. In this embodiment, as... Figure 10 As shown, a section of graded index multimode fiber (GIF) (e.g., GI62.5 / 125) can be fused to the end of an SMF-28 fiber, utilizing the multimode interference effect in the GIF to expand the mode field emitted from the SMF-28. By precisely cutting and controlling the length of the GIF (e.g., 267 µm), the mode field diameter of the light emitted from the SMF-28 can be expanded to be comparable to the mode field of the hollow fiber used, such as... Figure 13 As shown. Figure 11 Microscopic images of the prepared hollow-core optical fiber ceramic ferrule. Among them, Figure 11Figure (a) in the figure is a side view of the prepared hollow-core fiber ceramic ferrule, Figure 11 Figure (b) in the figure is a top view of the prepared hollow-core fiber ceramic ferrule. Figure 12 Figure (a) in the figure is a microscope photo of the preparation process of the solid-core SMF-28 ceramic ferrule. Among them, Figure 12 Figure (a) in the figure shows that a small amount of ultraviolet curing glue is adhered to the side of the optical fiber that penetrates the ceramic ferrule, Figure 12 Figure (b) in the figure shows a side view of the ceramic ferrule when the optical fiber is pulled down, Figure 12 Figures (c) and (d) in the figure are side view and end view of the SMF-28 ceramic ferrule after a small piece of GIF is fused. Figure 13 Figure (a) in the figure is the mode field diagram of the solid-core SMF-28 before mode field shaping, Figure 13 Figure (b) in the figure is the mode field diagram of the solid-core SMF-28 after connecting a 267 µm long piece of GIF for mode field shaping, Figure 13 Figure (c) in the figure is the mode field diagram of the above-mentioned hollow-core fiber at a wavelength of 1550 nm. As can be seen, by using GIF for mode field shaping, the mode field of the solid-core SMF-28 and the mode field of the hollow-core fiber are basically matched. After completing the matching of the mode fields of the hollow-core fiber and the solid-core SMF-28, they are respectively inserted into the inverted (for example, head groove structure) ceramic ferrule, and the optical fiber is packaged inside the ceramic ferrule using the same method as described above. Then, the prepared fiber ceramic ferrule is respectively assembled into the fiber connector. Finally, the prepared hollow-core / solid-core fiber connector is respectively inserted into the left and right key slots of the multi-key slot adapter pair, and the fiber connector is rotated and inserted into different key slots and the output optical power is measured. When the optical power reaches the maximum, the left and right fiber connectors are fixed with the multi-key slot adapter pair.

[0070] According to the method provided by the embodiment, a coupling efficiency of 83.3% between the hollow-core fiber and the solid-core SMF-28 can be achieved, that is, the connection loss is 0.8 dB.

[0071] Further, we use another "hot expansion core" method to expand the fiber core and mode field of SMF-28, and polish and coat an anti-reflection film on the end face of the hot expansion core SMF-28 (SMF-28, an example of a full solid optical fiber). Based on the same rotary connection method, we achieve a butt joint loss of 0.4 dB, and the back reflection light is greatly suppressed by coating an anti-reflection film, as shown in Figure 14 .

[0072] The application also provides another circumferential full-angle adjustable optical fiber connector, as shown in Figure 15As shown, in the optical fiber connector, the optical fiber connector and the multi-key groove adapter pair are removed, only the optical fiber ceramic ferrule in the optical fiber connector and the ferrule matching sleeve in the multi-key groove adapter pair are reserved, which makes the rotation adjustment of the optical fiber connector no longer limited by the number of keys on the adapter pair, and the two connected optical fibers can be adjusted in the circumferential full angle, so that the transverse offset between the two connected optical fibers can be further reduced. In addition, the optical fiber connector greatly reduces the volume and weight of the connector.

[0073] According to the technical scheme provided in the present application, the problems of end face pollution and damage in the preparation process of the hollow core optical fiber connector and the unadjustable transverse offset in the butt joint process of the hollow core optical fiber can be solved. As can be seen from the above embodiments, the technical scheme provided in the present application can realize the connection between various different types of optical fibers, and the connection loss is low. The optimized connector can be continuously adjustable in the circumferential full angle, realize lower connection loss, and has small volume and light weight. In addition, the hollow core optical fiber connection method provided in the present application is convenient and fast, low in time consumption, and can realize repeated plugging and unplugging, without complex process and equipment, greatly reducing the manufacturing cost and improving the operation efficiency.

[0074] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An optical fiber connector, characterized by, The application relates to a fiber connector, comprising: a first fiber connector, a second fiber connector and an adapter pair, the first fiber connector comprises a first fiber ferrule with a central axis through hole structure, and a first fiber can pass through the first fiber ferrule; the second fiber connector comprises a second fiber ferrule with a central axis through hole structure, and a second fiber can pass through the second fiber ferrule; the adapter pair is formed by the opposite connection and fixation of a first adapter and a second adapter, and the two adapters in the adapter pair are used for the plug-in of the first fiber connector and the second fiber connector, so that the first fiber and the second fiber are connected in the adapter pair, wherein the head of the first fiber ferrule comprises a first fiber limiting structure for fixing the head of the first fiber in the first fiber ferrule, and / or the head of the second fiber ferrule comprises a second fiber limiting structure for fixing the head of the second fiber in the second fiber ferrule, and at least one of the first fiber and the second fiber is a microstructure fiber, and the microstructure fiber comprises a hollow microstructure fiber and a solid microstructure fiber.

2. The fiber optic connector of claim 1, wherein, The first fiber limiting structure and / or the second fiber limiting structure are groove structures in the central axis direction of the head of the fiber ferrule, and the groove structures are used for accommodating materials with adhesive properties, so that the head of the fiber is fixed in the fiber ferrule.

3. The fiber connector according to claim 1 or 2, wherein a first key is arranged on the first fiber connector, a first component for fixing the first fiber connector is arranged on the first adapter of the adapter pair, at least two first key grooves are arranged on the side wall of the first component, the first key can be embedded in each of the at least two first key grooves, and the at least two first key grooves are distributed in the circumferential direction of the first component, and / or a second key is arranged on the second fiber connector, a second component for fixing the second fiber connector is arranged on the second adapter of the adapter pair, at least two second key grooves are arranged on the side wall of the second component, the second key can be embedded in each of the at least two second key grooves, and the at least two second key grooves are distributed in the circumferential direction of the second component.

4. The fiber optic connector of any one of claims 1-3, wherein, The first adapter and the second adapter in the adapter pair are connected together through the flanges of the respective outer edges.

5. The fiber optic connector of any one of claims 1-4, wherein, If the fiber in the fiber ferrule is a full solid fiber, the ferrule end face of the full solid fiber is polished and coated with an anti-reflection film.

6. A method of making a fiber ferrule, the method comprising: The application relates to a fiber connector, comprising: obtaining a ferrule with a groove structure on the head; passing a fiber into the ferrule; cutting the fiber end face out of the ferrule; coating a material with adhesive properties on the side of the fiber out of the ferrule; the groove structure accommodates the material with adhesive properties, and after the adhesive is cured, the head of the fiber is fixed in the fiber ferrule; wherein the fiber comprises a microstructure fiber, and the microstructure fiber comprises a hollow microstructure fiber and a solid microstructure fiber.

7. The method of claim 6, wherein, The method further comprises: The head end face of the optical fiber is leveled with the outer edge end face of the ferrule head, so that the groove structure accommodates the material with adhesive properties.

8. The method according to claim 6 or 7, characterized in that, If the optical fiber is a full solid optical fiber, the method further comprises: Polishing and coating an anti-reflection film on the ferrule end face of the full solid optical fiber.

9. An optical fiber connector, characterized by, Comprise: A first optical fiber ferrule, a second optical fiber ferrule and a ferrule matching sleeve, Wherein, a first optical fiber is packaged in the first optical fiber ferrule, and a second optical fiber is packaged in the second optical fiber ferrule, The ferrule matching sleeve is used to connect the first optical fiber ferrule and the second optical fiber ferrule to butt the first optical fiber and the second optical fiber, and the first optical fiber ferrule and the second optical fiber ferrule can be rotated at any angle in the circumferential direction in the ferrule matching sleeve, Wherein, the head of the first optical fiber ferrule comprises a first optical fiber limiting structure for fixing the head of the first optical fiber in the first optical fiber ferrule, and / or the head of the second optical fiber ferrule comprises a second optical fiber limiting structure for fixing the head of the second optical fiber in the second optical fiber ferrule, at least one of the first optical fiber and the second optical fiber is a microstructure optical fiber, and the microstructure optical fiber comprises an air-core microstructure optical fiber and a solid-core microstructure optical fiber.

10. The fiber optic connector of claim 9, wherein, The first optical fiber limiting structure and / or the second optical fiber limiting structure is a groove structure in the direction of the central axis, and the groove structure is used to accommodate a material with adhesive properties to fix the head of the optical fiber in the optical fiber ferrule.

11. The fiber optic connector of claims 9 or 10, wherein, If the optical fiber in the optical fiber ferrule is a full solid optical fiber, the ferrule end face of the full solid optical fiber is polished and coated with an anti-reflection film.

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