Hollow-core fiber connector and optical connection system

Abstract

A hollow-core fiber connector (230) and an optical connection system. The hollow-core fiber connector (230) comprises a first ferrule (110), a mode field matching component (120) and a hollow-core fiber (130), wherein the mode field matching component (120) is at least partially arranged in an inner hole of the first ferrule (110); a first recess (111) is provided in one end of the first ferrule (110); and the mode field matching component (120) comprises a first end (121) and a second end (122), the second end (122) being connected to the hollow-core fiber (130), the connection position between the second end (122) and the hollow-core fiber (130) being located within the first recess (111) or protruding from the first recess (111), and the mode field size of the second end (122) corresponding to that of the hollow-core fiber (130). Thus, by means of the provision of the recess in one end of the ferrule, the filling of a fixing material (e.g., dispensing) during butt-joint of a mode field adapter fiber and the hollow-core fiber (130) is facilitated, thereby improving the connection reliability of the connector.

Description

Hollow core fiber connector and optical connection system

[0001] This application claims priority to the Chinese patent application No. 202410458819.6, filed on April 16, 2024, and entitled "Hollow core fiber connector and optical connection system", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the field of optical communication, in particular to a hollow core fiber connector and optical connection system. BACKGROUND

[0003] With the wide application of 5G, artificial intelligence and other technologies, the demand for bandwidth is further increasing, and optical communication is facing a data density revolution. The performance of devices, optical modules and connection components in optical communication architecture needs to be further improved. In the current optical connection system, traditional solid core optical fibers are still widely used. The performance of solid core optical fibers in terms of latency, nonlinearity and dispersion is relatively low, and they cannot meet the needs of future optical connection systems with low cost, low power consumption and long transmission distance. Recently, the development of hollow core fiber (HCF) technology has become mature. The dispersion of hollow core fiber can reach 2-3 ps / nm / km, the latency can be reduced by about 1.5 us / km, the nonlinearity can be reduced by 1000 times, and the insertion loss is <0.2 dB / km. Compared with solid core optical fibers, hollow core fibers can promote the further development of optical communication.

[0004] However, so far, only part of the optical fibers in the optical connection system have been replaced by hollow core fibers, which cannot be compatible with existing communication devices, optical modules and chips. In order to ensure the compatibility of the optical connection system and further improve the communication rate and expand the bandwidth, an adapter and a connector for optical fibers are needed to realize the connection of other optical fibers and hollow core fibers. However, the mode field size of the hollow core fiber does not match that of other optical fibers, and the existing connectors cannot be directly matched. In addition, the end face of the hollow core fiber is an air core, which is extremely sensitive to dust, water vapor and other factors. Therefore, how to realize reliable and low-loss connection between hollow core fibers and other optical fibers has become a major challenge and an industrial demand. SUMMARY

[0005] The present application provides a fiber connector and optical connection system, by providing a mode field matching component in the ferrule, and providing a groove at the connection between the mode field matching component and the hollow core fiber, thereby improving the connection reliability of the hollow core fiber and the solid core fiber, and reducing the optical transmission loss.

[0006] In a first aspect, a hollow-core fiber connector is provided, comprising a first ferrule, a mode field matching component, and a hollow-core fiber, wherein: the mode field matching component is at least partially disposed in an inner hole of the first ferrule, and one end of the first ferrule is provided with a first recess; the mode field matching component comprises a first end and a second end, and the second end is connected with the hollow-core fiber, and the connection position of the second end with the hollow-core fiber is located in the first recess or protrudes from the first recess; and the mode field size of the second end corresponds to the mode field size of the hollow-core fiber. Thus, by providing the recess at one end of the ferrule, the filling of the fixing material (such as glue) is facilitated when the mode field matching fiber is butt-jointed with the hollow-core fiber, and the connection reliability of the connector is improved.

[0007] In combination with the first aspect, in some implementations of the first aspect, a housing and an interface are further included, wherein: the housing is used to accommodate the first ferrule; and the interface is used to be butt-jointed with an adapter, and the other end of the first ferrule is disposed in the interface.

[0008] In combination with the first aspect, in some implementations of the first aspect, the mode field matching component is of a type of thermal diffusion fiber or refractive index gradient fiber, and the mode field size of the first end is larger than the mode field size of the second end. Thus, the mode field size of the mode field matching component is expanded from the first end to the second end.

[0009] In combination with the first aspect, in some implementations of the first aspect, the second end has an inclination angle and / or is provided with an anti-reflection film. Thus, the reflection generated after the second end is butt-jointed with the hollow-core fiber is reduced.

[0010] In combination with the first aspect, in some implementations of the first aspect, the first recess is in a conical shape, and the inner diameter of the conical shape increases from the first end to the second end. Thus, the stability is further enhanced when the fixing material (such as glue) is filled after butt-joint.

[0011] In combination with the first aspect, in some implementations of the first aspect, the mode field matching component is of a type of solid-core fiber. Thus, after the other end of the mode field matching component is butt-jointed with the solid-core fiber, the coupling loss is reduced.

[0012] In a second aspect, a light connection system is provided, comprising a light module, an adapter, and the hollow-core fiber connector of the first aspect and any possible implementation thereof, wherein: the light module comprises a second ferrule and a first fiber, and the first fiber is at least partially disposed in an inner hole of the second ferrule; the adapter comprises a sleeve, and the sleeve is used to fix the second ferrule and the first ferrule, so that the first fiber and the mode field matching fiber are coaxially arranged; and the mode field size of the first fiber corresponds to the mode field size of the first end, and the first fiber is of a type of hollow-core fiber or solid-core fiber.

[0013] In the current fiber connector scheme, in order to realize the butt joint of the hollow optical fiber and the first optical fiber, an optical fiber or a waveguide needs to be additionally added at the butt joint of the first ferrule and the second ferrule, which causes additional insertion loss at the interface and the adapter due to twice coupling, and increases the overall size of the connector. However, by using the connector of the present application, the efficient coupling of the first optical fiber and the hollow optical fiber can be realized by directly inserting the first optical fiber on the butt joint side into the second ferrule, the optical loss is reduced, and the small-size optical connection is facilitated.

[0014] In a third aspect, an optical connection system is provided, comprising a first fiber connector, an adapter, and the hollow optical fiber connector of the first aspect and any possible implementation thereof, wherein: the first fiber connector comprises a second ferrule and a first optical fiber, the first optical fiber is at least partially arranged in the inner hole of the second ferrule; the adapter comprises a sleeve, the sleeve is used to fix the second ferrule and the first ferrule, so that the first optical fiber and the mode field matching optical fiber are coaxially arranged; wherein the mode field size of the first optical fiber corresponds to the mode field size of the first end, and the first optical fiber is of a hollow optical fiber type or a solid optical fiber type.

[0015] In the current fiber connector scheme, in order to realize the butt joint of the hollow optical fiber and the first optical fiber, an optical fiber or a waveguide needs to be additionally added at the butt joint of the first ferrule and the second ferrule, which causes additional insertion loss at the interface and the adapter due to twice coupling, and increases the overall size of the connector. However, by using the connector of the present application, the efficient coupling of the first optical fiber and the hollow optical fiber can be realized by directly inserting the first optical fiber on the butt joint side into the second ferrule, the optical loss is reduced, and the small-size optical connection is facilitated.

[0016] In a fourth aspect, a hollow optical fiber connector is provided, comprising a first ferrule, a first mode field matching unit, and a hollow optical fiber, wherein: one end of the first ferrule is provided with a first recess, the first mode field matching unit is at least partially arranged in the first recess, and the hollow optical fiber is at least partially arranged in the inner hole of the first ferrule, wherein the first mode field matching unit comprises a first end and a second end, the second end is connected with the hollow optical fiber, and the connection position of the second end with the hollow optical fiber is located in the first recess; wherein the mode field size of the second end corresponds to the mode field size of the hollow optical fiber. By arranging the recess at one end of the ferrule and arranging the butt joint of the mode field matching unit and the hollow optical fiber in the recess, the filling of the fixing material (such as glue dispensing) is facilitated, and the reliability of the adapter is improved.

[0017] In combination with the fourth aspect, in some implementations of the fourth aspect, a housing and an interface are further included, wherein: the housing is used to accommodate the first ferrule; the interface is used to butt joint with the adapter, and one end of the first ferrule is arranged in the interface.

[0018] In some implementations of the fourth aspect, the first mode field matching unit is any one of a graded-index fiber, a graded-index prism, a thermal diffusion coefficient fiber, or a tapered waveguide, and the mode field size at the first end is smaller than the mode field size at the second end. Thus, the mode field size is expanded.

[0019] In some implementations of the fourth aspect, the first groove is tapered, and the inner diameter of the tapered groove decreases from the first end to the second end. Thus, the stability is further enhanced when the filling of the fixing material (e.g., glue) is performed after the abutment.

[0020] In the fifth aspect, an optical connection system is provided, which includes an optical module, an adapter, and the hollow optical fiber connector of the fourth aspect and any possible implementation thereof, wherein: the optical module includes a second ferrule and a first optical fiber, and the first optical fiber is at least partially arranged in the inner hole of the second ferrule; the adapter includes a sleeve, and the sleeve is used to fix the second ferrule and the first ferrule so that the first optical fiber and the hollow optical fiber are coaxially arranged; and the mode field size of the first optical fiber corresponds to the mode field size at the first end, and the first optical fiber is of a hollow optical fiber type or a solid optical fiber type.

[0021] In the current connector scheme of the optical fiber, in order to realize the abutment of the hollow optical fiber and the first optical fiber, an optical fiber or a waveguide needs to be additionally added at the abutment position of the first ferrule and the second ferrule, which causes additional insertion loss at the interface and the adapter due to the twice coupling and increases the overall size of the connector. However, by using the connector of the present application, the first optical fiber at the abutment side can be directly inserted into the second ferrule, the efficient coupling of the first optical fiber and the hollow optical fiber is realized, the optical loss is reduced, and the small-size optical connection is facilitated.

[0022] In some implementations of the fifth aspect, the second ferrule and the first ferrule are adjacent, and the pitch of the first mode field matching unit is 0.25 x K, where K is a positive integer. Thus, the mode field size is expanded.

[0023] In some implementations of the fifth aspect, the adapter further includes a second mode field matching unit, the second mode field matching unit is arranged between the second ferrule and the first ferrule, and the second mode field matching unit is any one of a graded-index fiber, a graded-index prism, a thermal diffusion coefficient fiber, or a tapered waveguide. Thus, the mode field size is expanded.

[0024] In some implementations of the fifth aspect, the pitch of the second mode field matching unit is 0.25 x S, and the pitch of the first mode field matching unit is 0.5 x L, where S is a positive integer and L is a positive integer. Thus, the mode field size is expanded.

[0025] In some implementations of the fifth aspect, the first fiber connector further includes a third mode field matching unit, wherein: one end of the second ferrule is provided with a second groove, the second groove is adjacent to the first ferrule, the third mode field matching unit is at least partially disposed in the second groove, and one end of the first optical fiber is connected to one end of the third mode field matching unit; and the third mode field matching unit is any one of a graded index fiber, a graded index prism, a thermal diffusion coefficient fiber, or a tapered waveguide.

[0026] In some implementations of the fifth aspect, the pitch of the third mode field matching unit is 0.25xP, and the pitch of the first mode field matching unit is 0.25xQ, P is a positive integer, and Q is a positive integer. Thus, the mode field size is expanded.

[0027] In the sixth aspect, an optical connection system is provided, including a first fiber connector, an adapter, and the hollow core fiber connector of the fourth aspect and any possible implementation thereof, wherein: the first fiber connector includes a second ferrule and a first optical fiber, and the first optical fiber is at least partially disposed in the inner hole of the second ferrule; the adapter includes a sleeve for fixing the second ferrule and the first ferrule to coaxially arrange the first optical fiber and the hollow core fiber; and the mode field size of the first optical fiber corresponds to the mode field size of the first end, and the first optical fiber is of a hollow core fiber type or a solid core fiber type. Thus, the mode field size is expanded.

[0028] In the current fiber connector scheme, in order to realize the butt joint of the hollow core fiber and the first optical fiber, an optical fiber or a waveguide needs to be additionally added at the butt joint of the first ferrule and the second ferrule, which will cause additional insertion loss due to two couplings at the interface and the adapter, and increase the overall size of the connector. However, by using the connector of the present application, the first optical fiber on the butt joint side can be directly inserted into the second ferrule to realize efficient coupling of the first optical fiber and the hollow core fiber, reduce optical loss, and facilitate small-size optical connection.

[0029] In some implementations of the sixth aspect, the second ferrule is adjacent to the first ferrule, the pitch of the first mode field matching unit is 0.25xK, and K is a positive integer. Thus, the mode field size is expanded.

[0030] In some implementations of the sixth aspect, the adapter further includes a second mode field matching unit, the second mode field matching unit is disposed between the second ferrule and the first ferrule, and the second mode field matching unit is any one of a graded index fiber, a graded index prism, a thermal diffusion coefficient fiber, or a tapered waveguide. Thus, the mode field size is expanded.

[0031] In some implementations of the sixth aspect, in combination with the sixth aspect, a pitch of the second mode field matching unit is 0.25*S, a pitch of the first mode field matching unit is 0.5*L, S is a positive integer, and L is a positive integer. Thus, the mode field size is expanded.

[0032] In some implementations of the sixth aspect, in combination with the sixth aspect, the first fiber connector further includes a third mode field matching unit, wherein: one end of the second ferrule is provided with a second groove, the second groove is adjacent to the first ferrule, the third mode field matching unit is at least partially disposed in the second groove, and one end of the first optical fiber is connected to one end of the third mode field matching unit; and the third mode field matching unit is any one of a graded index fiber, a graded index prism, a thermal diffusion coefficient fiber, or a tapered waveguide. Thus, the mode field size is expanded.

[0033] In some implementations of the sixth aspect, in combination with the sixth aspect, a pitch of the third mode field matching unit is 0.25*P, a pitch of the first mode field matching unit is 0.25*Q, P is a positive integer, and Q is a positive integer. Thus, the mode field size is expanded.

[0034] In a seventh aspect, an optical module is provided, including an optical chip and the hollow optical fiber connector of the first aspect and any possible implementation thereof, wherein the optical chip is optically coupled with the optical fiber connector.

[0035] In an eighth aspect, an optical module is provided, including an optical chip and the hollow optical fiber connector of the fourth aspect and any possible implementation thereof, wherein the optical chip is optically coupled with the optical fiber connector.

[0036] In a ninth aspect, an optical connection system is provided, including an optical module and the hollow optical fiber connector of the first aspect and any possible implementation thereof, wherein: the hollow optical fiber connector is connected to an optical interface of the optical module, the optical module is internally provided with an optical chip, and the optical chip is optically coupled with the optical fiber connector.

[0037] In a tenth aspect, an optical connection system is provided, including an optical module and the hollow optical fiber connector of the fourth aspect and any possible implementation thereof, wherein: the hollow optical fiber connector is connected to an optical interface of the optical module, the optical module is internally provided with an optical chip, and the optical chip is optically coupled with the optical fiber connector. BRIEF DESCRIPTION OF DRAWINGS

[0038] FIG. 1 is a schematic diagram of a hollow optical fiber connector according to an embodiment of the present application.

[0039] FIG. 2 is a schematic diagram of an optical connection system according to an embodiment of the present application.

[0040] FIG. 3 is a schematic diagram of another optical connection system according to an embodiment of the present application.

[0041] Fig. 4 is a schematic diagram of a first hollow-core fiber connector according to an embodiment of the present application.

[0042] Fig. 5 is a schematic diagram of a second hollow-core fiber connector according to an embodiment of the present application.

[0043] Fig. 6 is a schematic diagram of an optical connection system according to an embodiment of the present application.

[0044] Fig. 7 is a schematic diagram of an optical connection system according to an embodiment of the present application.

[0045] Fig. 8 is a schematic diagram of a second hollow-core fiber connector according to an embodiment of the present application.

[0046] Fig. 9 is a schematic diagram of an optical communication system according to an embodiment of the present application.

[0047] Fig. 10 is a schematic diagram of an optical communication system according to an embodiment of the present application. DETAILED DESCRIPTION

[0048] The technical solutions in the present application will be described below with reference to the accompanying drawings.

[0049] First, the terms "comprising" and "having" and any variations thereof in the embodiments of the present application shown below are intended to cover the inclusions that are not exclusive, for example, the processes, methods, systems, products or devices comprising a series of steps or units do not have to be limited to those steps or units clearly listed, but can include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0050] Second, in the embodiments of the present application, the words "exemplarily" or "for example" are used to represent examples, illustrations or descriptions, and the embodiments or design schemes described as "exemplarily" or "for example" should not be interpreted as more preferred or more advantageous than other embodiments or design schemes. The words "exemplarily" or "for example" are used to present the relevant concepts in a specific manner and facilitate understanding.

[0051] Third, in the following embodiments of the present application, the terms "first", "second" and the like and various numerical numbers in the textual description or the drawings are only used for differentiation for convenience of description, and do not have to be used to describe a specific order or sequence, and do not limit the scope of the embodiments of the present application.

[0052] With the wide application of 5G, artificial intelligence and other technologies, the demand for bandwidth is further increasing, and optical communication is facing a data density revolution. The performance of devices, optical modules and connector devices in the optical communication architecture needs to be further improved. In the current optical connection system, traditional solid core optical fibers are still widely used. The performance of solid core optical fibers in terms of delay, nonlinearity and dispersion is low, and they cannot meet the needs of future low-cost, low-power and long-distance optical connection systems. Recently, the development of hollow core fiber (HCF) technology has matured. The dispersion of hollow core fiber can reach 2-3 ps / nm / km, the delay can be reduced by about 1.5 us / km, the nonlinearity is reduced by 1000 times, and the insertion loss is <0.2 dB / km. Compared with solid core optical fibers, hollow core fibers can further promote the development of optical communication.

[0053] However, so far, only part of the optical fibers in the optical connection system have been replaced by hollow core fibers, which cannot be compatible with existing communication devices, optical modules and chips. In order to ensure the compatibility of the optical connection system and further improve the communication rate and expand the bandwidth, an adapter and a connector of the optical fiber are needed to realize the matching connection of other optical fibers and hollow core fibers. However, the mode field size of the hollow core fiber does not match other optical fibers, and it cannot be directly matched by using the existing connector. In addition, the end face of the hollow core fiber is an air core, which is extremely sensitive to dust, water vapor and other influences. Therefore, how to realize the reliable and low-loss connection of the hollow core fiber and other optical fibers has become a great challenge and an industrial demand. In view of this, the embodiments of the present application provide an optical fiber connector and an optical connection system, which improve the connection reliability of the hollow core fiber and the solid core fiber and reduce the optical transmission loss by setting a mode field matching component in the ferrule and setting a groove at the connection between the mode field matching component and the hollow core fiber.

[0054] First, the first optical fiber connector and the optical connection system provided by the present application will be described in conjunction with FIGS. 1 to 4.

[0055] FIG. 1 is a schematic view of a hollow core fiber connector according to an embodiment of the present application. As shown in FIG. 1, the hollow core fiber connector includes a first ferrule 110, a mode field matching component 120 and a hollow core fiber 130.

[0056] The mode field matching component 120 is at least partially disposed in the inner hole of the first ferrule 110, and one end of the first ferrule 110 is provided with a groove. The mode field matching component 120 can be a mode field matching optical fiber.

[0057] The mode field matching component 120 includes a first end 121 and a second end 122, and the second end 122 is connected with the hollow core fiber 130. In some implementations, as shown in (a) of FIG. 1, the connection position of the second end 122 with the hollow core fiber 130 is located within the first groove 111. In some implementations, as shown in (b) of FIG. 1, the connection position of the second end 122 with the hollow core fiber 130 protrudes out of the first groove 111. In this case, the protruding size of the connection position relative to the first groove 111 is less than a first threshold.

[0058] The mode field matching component 120 is used to match the mode field of the first optical fiber and the hollow core fiber 130. The mode field size of the first end 121 is smaller than the mode field size of the second end 122. The mode field size of the first end 121 can correspond to the mode field size of the first optical fiber, and the mode field size of the second end 122 can correspond to the mode field size of the hollow core fiber 130. In this case, the first optical fiber can be of a hollow core fiber type or a solid core fiber type. The mode field size correspondence can specifically refer to that the mode field sizes are equal, or the difference between the mode field sizes is less than or equal to a fixed threshold.

[0059] In the optical fiber connector as shown in FIG. 1, by providing a groove at one end of the ferrule, the filling of the fixing material (such as glue) is facilitated when the mode field adapter optical fiber is connected with the hollow core fiber 130, and the connection reliability of the connector is improved.

[0060] In some implementations, the first groove 111 is in a conical shape, and the inner diameter of the conical shape increases from the first end 121 to the second end 122. Thus, the stability is further enhanced when the fixing material (such as glue) is filled after the connection. In addition, the first groove 111 can also be in a cylindrical shape, a conical shape, a wedge shape, etc., which is determined according to the actual situation, and the present application does not make any limitation in this regard.

[0061] In some implementations, the mode field matching component 120 is of a thermal expansion coefficient (TEC) fiber or a graded-index (grin) fiber. The TEC fiber, which can also be referred to as a lens fiber or a beam expanding fiber, is obtained by high-temperature sintering, so as to realize the expansion of the mode field size from the first end 121 to the second end 122 of the mode field matching component 120. The grin fiber, which can also be referred to as a self-focusing fiber, is obtained due to the non-uniformity of the refractive index in the radial direction, so as to realize the expansion of the mode field size from the first end 121 to the second end 122 of the mode field matching component 120. In addition, the mode field matching component 120 can also be specifically understood as a mode field adapter optical fiber, a mode field adapter, a mode field matching component, etc.

[0062] In some implementations, the second end 122 of the mode field matching component 120 has an inclination angle, and / or is provided with an anti-reflection (AR) film. Thus, the reflection after the second end 122 is butted against the hollow core fiber 130 is reduced.

[0063] In some implementations, the mode field matching component 120 is of a solid core fiber type, so that the coupling loss is reduced after the other end of the mode field matching component 120 is butted against a solid core fiber.

[0064] In some implementations, the first groove is filled with glue.

[0065] In some implementations, the hollow core fiber connector further includes a housing and an interface. The housing is used to accommodate the first ferrule 110. The interface is used to butt against an adapter, and the other end of the first ferrule 110 is arranged in the interface. The fiber connector can be of a lucent connector (LC) type, an MT-RJ type, a square connector (SC) type, a ferrule connector (FC) type, a multi-fiber push on (MPO) type, a mini connector (MC) type, a miniature unit (MU) type, a straight trip (ST) type, etc. The housing and the specific interface arrangement can be determined according to the above types. For example, the housing can further include a pin key, a switch, a pin, a spring body, a limiting body, etc. The interface can also specifically refer to a male head or a female head according to actual conditions.

[0066] In addition, the hollow core fiber connector can further include a pigtail protection sleeve, etc. which is determined according to actual conditions.

[0067] FIG. 2 is a schematic diagram of an optical connection system according to an embodiment of the present application. As shown in FIG. 2, the optical connection system includes an optical module 210, an adapter 220 and a hollow core fiber connector 230.

[0068] The optical module 210 includes a second ferrule 211 and a first optical fiber 212, and the first optical fiber 212 is at least partially arranged in the inner hole of the second ferrule 211. The first optical fiber can be of a hollow core fiber type or a solid core fiber type.

[0069] The adapter 220 can be part of the optical module 210 or a separate element from the optical module 210. The adapter 220 includes a sleeve for fixing the second ferrule 211 and the first ferrule 231 to arrange the first optical fiber 212 and the mode field matching component coaxially. The adapter 220 can be provided with a fixing member to fix the sleeve. The sleeve can be a ceramic C-ring.

[0070] The hollow core fiber connector 230 is similar to that described in FIG. 1 and will not be described again here.

[0071] The optical module 210 can be an interface pluggable optical module, for example, the optical module can also be a small form-factor pluggable (SFP), enhanced SFP, rate enhanced SFP+, 10G SFP, SFP29, four-channel SFP, etc., which is determined according to actual conditions.

[0072] In the current fiber connector scheme, in order to realize the butt joint of the hollow core fiber 250 and the first optical fiber 212, an optical fiber or a waveguide needs to be additionally added at the butt joint of the first ferrule 231 and the second ferrule 211, which will cause additional insertion loss at the interface and the adapter 220 due to two couplings, and increase the overall size of the connector. By using the connector of the present application, the efficient coupling of the first optical fiber 212 and the hollow core fiber 250 can be realized by directly inserting the first optical fiber 212 on the butt joint side into the second ferrule 211, the optical loss is reduced, and the small size of the optical connection is beneficial.

[0073] In some implementations, as shown in (a) of FIG. 2, the first ferrule 231 and the second ferrule 211 have a spacing therebetween. (b) of FIG. 2 shows the mode field sizes of the corresponding parts in the optical connection system. Corresponding to (a) of FIG. 2, the first optical fiber 212 has a first mode field size (e.g., 9 μm). The first end of the mode field matching component 240 has the first mode field size (e.g., 9 μm), and the second end has a second mode field size (e.g., 20 μm). The hollow core fiber 250 has the second mode field size (e.g., 20 μm).

[0074] In some implementations, as shown in (c) of FIG. 2, the first ferrule 231 and the second ferrule 211 are in contact and butt joint. (d) of FIG. 2 shows the mode field sizes of the corresponding parts in the optical connection system. Corresponding to (c) of FIG. 2, the first optical fiber 212 has a first mode field size (e.g., 9 μm). The first end of the mode field matching component 240 has the first mode field size (e.g., 9 μm), and the second end has a second mode field size (e.g., 20 μm). The hollow core fiber 250 has the second mode field size (e.g., 20 μm).

[0075] In some implementations, the second ferrule 211 is provided with a second groove 213 at an end opposite to the first ferrule 231. Thus, it is convenient to fill the fixing material (e.g., glue) after the first optical fiber 212 is arranged, and the reliability of the butt joint between the optical fibers is improved.

[0076] FIG. 3 is a schematic diagram of another optical connection system according to an embodiment of the present application. As shown in FIG. 3, the optical connection system includes a first optical fiber 313 connector 310, an adapter 320, and the hollow optical fiber connector 330 shown in FIG. 1.

[0077] The first optical fiber 313 connector 310 includes a second ferrule 311 and a first optical fiber 313, and the first optical fiber 313 is at least partially arranged in the inner hole of the second ferrule 311. The first optical fiber can be a hollow optical fiber type or a solid optical fiber type.

[0078] The adapter 320 includes a sleeve for fixing the second ferrule 311 and the first ferrule 331, so that the first optical fiber 313 and the mode field matching component are coaxially arranged. The adapter 320 can be provided with a fixing member to fix the sleeve. The sleeve can be a ceramic C-ring.

[0079] The hollow optical fiber connector 330 is similar to that described in FIG. 1, and will not be described here again.

[0080] In the current optical fiber connector scheme, in order to realize the butt joint of the hollow optical fiber and the first optical fiber 313, an optical fiber or a waveguide needs to be additionally added at the butt joint of the first ferrule 331 and the second ferrule 311, which will cause additional insertion loss at the interface and the adapter 320 due to two couplings, and increase the overall size of the connector. However, by using the connector of the present application, the efficient coupling of the first optical fiber 313 and the hollow optical fiber can be realized by directly inserting the first optical fiber 313 at the butt joint into the second ferrule 311, the optical loss is reduced, and the small-size optical connection is facilitated.

[0081] In some implementations, as shown in FIG. 3(a), the first ferrule 331 and the second ferrule 311 have a spacing therebetween. FIG. 3(b) shows the mode field sizes of the corresponding parts in the optical connection system. Corresponding to FIG. 3(a), the first optical fiber 313 has a first mode field size (e.g., 9 μm). The first end of the mode field matching component has a first mode field size (e.g., 9 μm), and the second end has a second mode field size (e.g., 20 μm). The hollow optical fiber has a second mode field size (e.g., 20 μm).

[0082] In some implementations, as shown in (c) of FIG. 3, the first ferrule 331 is in contact with the second ferrule 311. (d) of FIG. 3 shows the corresponding mode field sizes of the parts in the optical connection system. Corresponding to (c) of FIG. 3, the first optical fiber 313 has a first mode field size (e.g., 9 pm). The first end of the mode field matching component has a first mode field size (e.g., 9 pm), and the second end has a second mode field size (e.g., 20 pm). The hollow core fiber has the second mode field size (e.g., 20 pm).

[0083] In some implementations, the second ferrule 311 is provided with a second groove 314 at the end opposite to the first ferrule 331. Thus, it is convenient to fill the fixing material (e.g., glue) after the first optical fiber 313 is arranged, and the reliability of the butt joint between the optical fibers is improved.

[0084] FIG. 4 is a schematic diagram of a specific processing implementation method of a first hollow core fiber connector provided by the present application.

[0085] ①Preparation of a mode field matching component.

[0086] ②AR film is coated on the second end of the mode field matching component, and / or the second end of the mode field matching component is made to have an inclined angle. The upper part of (2) of FIG. 4 shows the case where the second end is coated with an AR film, and the lower part shows the case where the second end has an inclined angle.

[0087] ③Connection of the mode field matching component and the hollow core fiber. The connection mode can be adhesive connection, or heating and melting connection by using an electric arc. In some implementations, the connection mode can be femtosecond laser welding, so as to reduce the optical loss at the connection by using the cold processing process of femtosecond, and ensure the connection reliability.

[0088] ④Assembly of the mode field matching component connected with the hollow core fiber into the first ferrule.

[0089] ⑤Filling of glue at the groove at the end of the first ferrule, and grinding of the other end of the first ferrule.

[0090] ⑥Assembly of the first ferrule and other components, so as to form a standard optical fiber connector. For example, the first ferrule, the second ferrule, the sleeve and other components can be assembled to form a standard optical fiber connector.

[0091] Next, the second optical fiber connector and the optical connection system provided by the present application will be described in combination with FIGS. 5 to 8.

[0092] FIG. 5 is a schematic diagram of a second hollow core fiber connector provided by an embodiment of the present application. As shown in FIG. 5, the hollow core fiber 530 connector includes a first ferrule 510, a first mode field matching unit 520 and a hollow core fiber 530.

[0093] The first end of the first ferrule 510 is provided with a first groove 511, and the first mode field matching unit 520 is at least partially arranged in the first groove 511. The hollow core fiber 530 is at least partially arranged in the inner hole of the first ferrule 510. The first mode field matching unit 520 includes a first end and a second end, and the second end is connected with the hollow core fiber 530. The connection position of the second end with the hollow core fiber 530 is located in the first groove 511.

[0094] The first mode field matching unit 520 is used for mode field matching of the first optical fiber and the hollow core fiber 530. The mode field size of the first end is smaller than the mode field size of the second end. The mode field size of the first end can correspond to the mode field size of the first optical fiber, and the mode field size of the second end can correspond to the mode field size of the hollow core fiber 530. The mode field size correspondence can specifically refer to that the mode field sizes are equal, or the difference between the mode field sizes is less than or equal to a fixed threshold. The first optical fiber can be a hollow core fiber type or a solid core fiber type.

[0095] The first mode field matching unit 520 can be any one of a graded-index fiber, a graded-index prism, a thermal diffusion coefficient fiber, or a tapered waveguide. The graded-index fiber and the graded-index prism realize mode field size expansion by using the gradient of the refractive index. The thermal diffusion coefficient fiber, also known as a lens fiber or a beam expanding fiber, realizes mode field size expansion by high-temperature sintering. The tapered waveguide realizes mode field size expansion by setting different geometric cross sections at two ends.

[0096] In the adapter as shown in FIG. 5, by setting a groove at one end of the ferrule and arranging the connection position of the mode field matching unit and the hollow core fiber 530 in the groove, the filling of the fixing material (such as glue) is facilitated, and the reliability of the adapter is improved.

[0097] In some implementations, the first groove 511 is in a conical shape, and the inner diameter of the conical shape decreases from the first end to the second end. Thus, the stability is further enhanced when the fixing material (such as glue) is filled after the connection. In addition, the first groove 511 can also be in a cylindrical shape, a conical shape, a wedge shape, etc., which is determined according to the actual situation, and the application does not limit this.

[0098] In some implementations, the hollow optical fiber connector further includes a housing and an interface. The housing is configured to accommodate the first ferrule 510. The interface is configured to mate with an adapter, and the other end of the first ferrule 510 is disposed in the interface. The optical fiber connector can be a lucent connector (LC), an MT-RJ, a square connector (SC), a ferrule connector (FC), a multi-fiber push on (MPO), a mini connector (MC), a miniature unit (MU), a straight trip (ST), or the like. The housing and the specific interface arrangement can be determined according to the type. For example, the housing can further include a pin key, a switch, a pin, a spring body, a limiting body, or the like. The interface can specifically refer to a male or female head according to the actual situation.

[0099] In addition, the hollow optical fiber connector can further include a pigtail protection sleeve, and the like, which is determined according to the actual situation.

[0100] FIG. 6 is a schematic diagram of an optical connection system according to an embodiment of the present application. As shown in FIG. 6, the optical connection system includes an optical module 610, an adapter, and a hollow optical fiber connector 630.

[0101] The optical module 610 includes a second ferrule 611 and a first optical fiber 612, and the first optical fiber 612 is at least partially disposed in the inner hole of the second ferrule 611. The adapter can be provided with a fixing member to fix a sleeve. The sleeve can be a ceramic C-ring. The first optical fiber can be a hollow optical fiber type or a solid optical fiber type.

[0102] The adapter includes a sleeve configured to fix the second ferrule 611 and the first ferrule 631, so that the second ferrule 611 and the first ferrule 631 are coaxially arranged.

[0103] The hollow optical fiber connector 630 is similar to that described in FIG. 5, and will not be described here.

[0104] The optical module 610 can be an interface pluggable optical module. For example, the optical module can be a small form-factor pluggable (SFP), an enhanced SFP, an SFP+, a 10G SFP, an SFP29, a four-channel SFP, or the like, which is determined according to the actual situation.

[0105] In the current fiber connector scheme, in order to realize the butt joint of the hollow core fiber and the first fiber 612, an additional fiber or waveguide needs to be added at the butt joint of the first ferrule 631 and the second ferrule 611, which will cause additional insertion loss at the interface and adapter due to two couplings, and increase the overall size of the connector. However, by using the connector of the present application, the efficient coupling of the first fiber 612 and the hollow core fiber can be realized by directly inserting the first fiber 612 on the butt joint side into the second ferrule 611, which reduces the optical loss and is beneficial to small size optical connection.

[0106] In some implementations, the second ferrule 611 is provided with a second groove 613 at the end opposite to the first ferrule 631. Thus, it is convenient to fill the fixing material (such as glue) after the first fiber 612 is arranged, and the butt joint reliability between the fibers is improved.

[0107] In some implementations, as shown in (a) of FIG. 6, the second ferrule 611 and the first ferrule 631 are adjacent. (b) of FIG. 6 shows the mode field size of each part in the optical connection system. Corresponding to (a) of FIG. 6, the first fiber 612 has a first mode field size (for example, 9 μm). The first end of the first mode field matching unit has the first mode field size (for example, 9 μm), and the second end has a second mode field size (for example, 20 μm). The hollow core fiber has the second mode field size (for example, 20 μm). (c) of FIG. 6 shows a schematic diagram of the transmission light path in the first mode field matching unit. The vertical coordinate is the radial direction of the first mode field matching unit, and the horizontal coordinate is the refractive index corresponding to the radial direction in the first mode field matching unit. In some implementations, the pitch of the first mode field matching unit is 0.25×K, K is a positive integer, so as to realize the expansion of the mode field size. Wherein, the length of the beam propagating along the sinusoidal trajectory to complete one sinusoidal wave period is called a pitch.

[0108] In some implementations, as shown in (d) of FIG. 6, the adapter further includes a second mode field matching unit 640 arranged between the second ferrule 611 and the first ferrule 631. The second mode field matching unit 640 is any one of a graded index fiber, a graded index prism, a thermal diffusion coefficient fiber, or a tapered waveguide. One end of the second mode field matching unit 640 corresponds to the mode field size of the first fiber 612, and the other end of the second mode field matching unit 640 corresponds to the mode field size of the first end of the first mode field matching unit. One end of the second mode field matching unit 640 is adjacent to one end of the first fiber 612, and the other end of the second mode field matching unit 640 is adjacent to one end of the hollow core fiber. As shown in (e) of FIG. 6, the pitch of the second mode field matching unit 640 can be 0.25×S, and the pitch of the first mode field matching unit can be 0.5×L, S is a positive integer, and L is a positive integer, so as to realize the expansion of the mode field size.

[0109] In some implementations, as shown in (f) of FIG. 6, the first optical fiber 612 connector further comprises a third mode field matching unit 615. Wherein one end of the second ferrule 611 is provided with a second groove 614 613, and the third groove 614 is adjacent to the first ferrule 631. The third mode field matching unit 615 is at least partially disposed in the third groove 614, and one end of the first optical fiber 612 is connected to one end of the third mode field matching unit 615. Wherein the third mode field matching unit 615 is any one of a graded index fiber, a graded index prism, a thermal diffusion coefficient fiber, or a tapered waveguide. Wherein the mode field size of one end of the third mode field matching unit 615 corresponds to the mode field size of the first optical fiber 612, and the mode field size of the other end of the third mode field matching unit 615 corresponds to the mode field size of the first end of the first mode field matching unit. As shown in (g) of FIG. 6, wherein the pitch of the third mode field matching unit 615 is 0.25XP, the pitch of the first mode field matching unit is 0.25XQ, P is a positive integer, and Q is a positive integer.

[0110] FIG. 7 is a schematic diagram of an optical connection system according to an embodiment of the present application. As shown in FIG. 7, the optical connection system comprises a first optical fiber first optical fiber connector 710, an adapter, and a hollow core optical fiber connector 730.

[0111] The first optical fiber first optical fiber connector 710 comprises a second ferrule 711 and a first optical fiber 712, and the first optical fiber 712 is at least partially disposed in the inner hole of the second ferrule 711. The adapter can be provided with a fixing member to fix the sleeve. The sleeve can be a ceramic C-ring. Wherein the first optical fiber can be a hollow core optical fiber type or a solid core optical fiber type.

[0112] The adapter comprises a sleeve for fixing the second ferrule 711 and the first ferrule 731 so that the second ferrule 711 and the first ferrule 731 are coaxially arranged.

[0113] Wherein the hollow core optical fiber connector 730 is similar to that described in FIG. 5, and will not be described here.

[0114] In the current optical fiber connector scheme, in order to realize the butt joint of the hollow core optical fiber and the first optical fiber 712, an optical fiber or a waveguide needs to be additionally added at the butt joint of the first ferrule 731 and the second ferrule 711, which will cause additional insertion loss due to two couplings at the interface and the adapter, and increase the overall size of the connector. However, by using the connector of the present application, the first optical fiber 712 can be directly inserted into the second ferrule 711 at the butt joint side to realize efficient coupling of the first optical fiber 712 and the hollow core optical fiber, reduce optical loss, and facilitate small-size optical connection.

[0115] In some implementations, the second ferrule 711 is provided with a second groove 713 at an end opposite to the first ferrule 731. Thus, it is convenient to fill the fixing material (e.g., glue) after the first optical fiber 712 is arranged, and the reliability of the butt joint between the optical fibers is improved.

[0116] In some implementations, as shown in (a) of FIG. 7, the second ferrule 711 is adjacent to the first ferrule 731. (b) of FIG. 7 shows the mode field sizes of the corresponding parts in the optical connection system. Corresponding to (a) of FIG. 7, the first optical fiber 712 has a first mode field size (e.g., 9 μm). The first end of the first mode field matching unit has the first mode field size (e.g., 9 μm), and the second end has a second mode field size (e.g., 20 μm). The hollow core optical fiber has the second mode field size (e.g., 20 μm). (c) of FIG. 7 shows a schematic diagram of the transmission path in the first mode field matching unit. The vertical coordinate is the radial direction of the first mode field matching unit, and the horizontal coordinate is the refractive index corresponding to the radial direction in the first mode field matching unit. In some implementations, the pitch of the first mode field matching unit is 0.25×K, K is a positive integer, so as to realize the expansion of the mode field size. The length of the beam propagating along the sinusoidal trajectory to complete one sinusoidal wave period is called a pitch.

[0117] In some implementations, as shown in (d) of FIG. 7, the adapter further includes a second mode field matching unit 740 arranged between the second ferrule 711 and the first ferrule 731. The second mode field matching unit 740 is any one of a graded-index optical fiber, a graded-index prism, a thermal diffusion coefficient optical fiber, or a tapered waveguide. One end of the second mode field matching unit 740 corresponds to the mode field size of the first optical fiber 712, and the other end of the second mode field matching unit 740 corresponds to the mode field size of the first end of the first mode field matching unit. One end of the second mode field matching unit 740 is adjacent to one end of the first optical fiber 712, and the other end of the second mode field matching unit 740 is adjacent to one end of the hollow core optical fiber. As shown in (e) of FIG. 7, the pitch of the second mode field matching unit 740 can be 0.25×S, and the pitch of the first mode field matching unit can be 0.5×L, S is a positive integer, and L is a positive integer, so as to realize the expansion of the mode field size.

[0118] In some implementations, as shown in (f) of FIG. 7, the first optical fiber 712 connector further includes a third mode field matching unit 715. Wherein one end of the second ferrule 711 is provided with a third groove 714, the third groove 714 is adjacent to the first ferrule 731. The third mode field matching unit 715 is at least partially disposed in the third groove 714, and one end of the first optical fiber 712 is connected to one end of the third mode field matching unit 715. Wherein the third mode field matching unit 715 is any one of a graded-index fiber, a graded-index prism, a thermal diffusion coefficient fiber, or a tapered waveguide. Wherein the mode field size of one end of the third mode field matching unit 715 corresponds to the mode field size of the first optical fiber 712, and the mode field size of the other end of the third mode field matching unit 715 corresponds to the mode field size of the first end of the first mode field matching unit. As shown in (g) of FIG. 7, wherein the pitch of the third mode field matching unit 715 is 0.25xP, the pitch of the first mode field matching unit is 0.25xQ, P is a positive integer, and Q is a positive integer.

[0119] FIG. 8 is a specific processing implementation method schematic diagram of a second hollow optical fiber connector provided by the present application.

[0120] ①The first mode field matching unit 810 is coupled and fixed with the hollow optical fiber 820, and an AR film 830 is arranged at the coupling and fixing position.

[0121] ②The first mode field matching unit 810 and the hollow optical fiber 820 after coupling and fixing are placed in the first ferrule 840.

[0122] ③The first groove is filled with glue, and the fifth end surface of the first ferrule 840 is ground.

[0123] ④The first ferrule 840 and other components are assembled, thereby forming a standard optical fiber connector.

[0124] FIG. 9 is a schematic diagram of an optical communication system provided by an embodiment of the present application. As shown in FIG. 9, the optical communication system includes a first optical module 910 and a second optical module 920. Wherein the first optical module 910 and the second optical module 920 are connected through an optical fiber cable 930. Wherein the optical fiber cable 930 includes one or more hollow optical fibers.

[0125] The optical connection system can be an active optical cable (AOC) optical communication scenario. The first optical module 910 and the second optical module 920 are used for transmitting and / or receiving signal light, and the optical fiber cable 930 is used for transmitting signal light.

[0126] The optical module can be the first optical module 910 or the second optical module 920. The hollow-core fiber connector can be the hollow-core fiber connector shown in FIG. 1 or FIG. 5.

[0127] Alternatively, the optical communication system includes an optical connection system. The optical connection system includes an optical module and a hollow-core fiber connector. The hollow-core fiber connector is connected to the optical interface of the optical module. The optical module is internally provided with an optical chip, and the optical chip is optically coupled with the fiber connector. The optical module can be the first optical module 910 or the second optical module 920. The hollow-core fiber connector can be the hollow-core fiber connector shown in FIG. 1 or FIG. 5.

[0128] FIG. 10 is a schematic diagram of an optical communication system according to an embodiment of the present application. As shown in FIG. 10, the optical communication system includes a first optical connection system 1010, a second optical connection system 1020, and an optical fiber cable. The optical fiber cable is optically connected to the first optical connection system 1010 at one end and optically connected to the second optical connection system 1020 at the other end.

[0129] The first optical connection system 1010 is configured to transmit a first optical signal to the second optical connection system 1020, and the second optical connection system 1020 is configured to receive the first optical signal. And / or the second optical connection system 1020 is configured to transmit a second optical signal to the first optical connection system 1010, and the second optical connection system 1020 is configured to receive the second optical signal.

[0130] The optical fiber cable is used for optical signal transmission between the first optical connection system 1010 and the second optical connection system 1020. The optical fiber cable includes one or more hollow-core fibers. The optical fiber cable 1032 or one end 1031, 1033 of the optical fiber cable can be coupled with the fiber connector shown in any of the above figures.

[0131] The first optical connection system and the second optical connection system can be optical access equipment, optical transmission equipment, optical terminal equipment, etc., and can be specifically optical modem, router, access point, switch, optical line terminal (OLT), optical network unit (ONU), optical distribution network (ODN), etc. The applicable network can be specifically passive optical network (PON), such as next-generation PON (NG-PON), NG-PON1, NG-PON2, gigabit-capable PON (GPON), wavelength-division multiplexing (WDM) PON, time-and wavelength-division multiplexing (TWDM) PON, point-to-point (P2P) WDM PON (P2P-WDM PON), etc. The actual situation is determined.

[0132] In addition, the embodiment of the present application further provides an optical fiber cable. The optical fiber cable is used for optical signal transmission between optical communication equipment and optical modules. One or more hollow core optical fibers can be arranged in the optical fiber cable, and the actual situation is determined.

[0133] The optical fiber cable or one end of the optical fiber cable can be coupled with the optical fiber connector shown in any of the above figures.

[0134] The optical fiber cable or one end of the optical fiber cable can be coupled with the optical fiber connector shown in any of the above figures.

[0135] Those skilled in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be realized by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to realize the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0136] The above merely provides the specific implementation of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by 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. A hollow core optical fiber connector, characterized by, The hollow-core fiber connector comprises a first ferrule, a mode field matching component and a hollow-core fiber, wherein: the mode field matching component is at least partially arranged in the inner hole of the first ferrule, and one end of the first ferrule is provided with a first recess; the mode field matching component comprises a first end and a second end, and the second end is connected with the hollow-core fiber, and the connection position of the second end with the hollow-core fiber is located in the first recess or protrudes from the first recess; wherein the mode field size of the second end corresponds to the mode field size of the hollow-core fiber.

2. The hollow-core fiber connector of claim 1, wherein, The hollow-core fiber connector further comprises a housing and an interface, wherein: the housing is used for accommodating the first ferrule; the interface is used for being connected with an adapter, and the other end of the first ferrule is arranged in the interface.

3. The hollow-core fiber connector of claim 1 or 2, wherein, The mode field matching component is of a type of thermal diffusion coefficient fiber or refractive index gradient fiber, and the mode field size of the first end is larger than the mode field size of the second end.

4. The hollow-core fiber connector of any of claims 1-3, wherein, The second end has an inclination angle and / or is provided with an anti-reflection film.

5. The hollow-core fiber connector of any of claims 1-4, wherein, The first recess is in a conical shape, and the inner diameter of the conical shape increases from the first end to the second end.

6. The hollow-core fiber connector of any of claims 1-5, wherein, The mode field matching component is of a type of solid-core fiber.

7. An optical connection system, characterized by The optical module comprises a second ferrule and a first optical fiber, the first optical fiber is at least partially arranged in the inner hole of the second ferrule; The adapter comprises a sleeve, the sleeve is used for fixing the second ferrule and the first ferrule, so that the first optical fiber and the mode field matching component are coaxially arranged; wherein the mode field size of the first optical fiber corresponds to the mode field size of the first end, and the first optical fiber is of a type of hollow-core fiber or solid-core fiber. The first optical fiber connector comprises a second ferrule and a first optical fiber, the first optical fiber is at least partially arranged in the inner hole of the second ferrule; 8. An optical connection system, characterized by The adapter comprises a sleeve, the sleeve is used for fixing the second ferrule and the first ferrule, so that the first optical fiber and the mode field matching component are coaxially arranged; wherein the mode field size of the first optical fiber corresponds to the mode field size of the first end, and the first optical fiber is of a type of hollow-core fiber or solid-core fiber. The hollow-core fiber connector comprises a first ferrule, a first mode field matching unit and a hollow-core fiber, wherein: one end of the first ferrule is provided with a first recess, the first mode field matching unit is at least partially arranged in the first recess, and the hollow-core fiber is at least partially arranged in the inner hole of the first ferrule, wherein the first mode field matching unit comprises a first end and a second end, and the second end is connected with the hollow-core fiber, and the connection position of the second end with the hollow-core fiber is located in the first recess; 9. A hollow core optical fiber connector, characterized by, wherein the mode field size of the second end corresponds to the mode field size of the hollow-core fiber. The hollow-core fiber connector further comprises a housing and an interface, wherein: the housing is used for accommodating the first ferrule; 10. The hollow-core fiber connector of claim 9, wherein, the interface is used for being connected with an adapter, and one end of the first ferrule is arranged in the interface. ​ ​ 11. The hollow-core fiber connector of claim 9 or 10, wherein, The first mode field matching unit is any one of a graded-index fiber, a graded-index prism, a thermal diffusion coefficient fiber, or a tapered waveguide, and a mode field size of the first end is smaller than a mode field size of the second end.

12. The hollow-core fiber connector of any of claims 9-11, wherein, The first recess is tapered, and an inner diameter of the tapered recess decreases from the first end to the second end.

13. An optical connection system, characterized by The optical module, the adapter, and the hollow fiber connector of any one of claims 9-12 are included, wherein: The optical module includes a second ferrule and a first optical fiber, and the first optical fiber is at least partially disposed in a bore of the second ferrule; The adapter includes a sleeve configured to secure the second ferrule and the first ferrule to coaxially align the first optical fiber and the hollow fiber; The mode field size of the first optical fiber corresponds to the mode field size of the first end, and the first optical fiber is a hollow fiber type or a solid fiber type.

14. The optical connection system of claim 13, wherein, The second ferrule and the first ferrule are adjacent, and a pitch of the first mode field matching unit is 0.25 x K, where K is a positive integer.

15. The optical connection system of claim 13, wherein, The adapter further includes a second mode field matching unit disposed between the second ferrule and the first ferrule, and the second mode field matching unit is any one of a graded-index fiber, a graded-index prism, a thermal diffusion coefficient fiber, or a tapered waveguide.

16. The optical connection system of claim 15, wherein, A pitch of the second mode field matching unit is 0.25 x S, and a pitch of the first mode field matching unit is 0.5 x L, where S is a positive integer and L is a positive integer.

17. The optical connection system of claim 13, wherein, The first fiber connector further includes a third mode field matching unit, wherein: One end of the second ferrule is provided with a second recess adjacent to the first ferrule, and the third mode field matching unit is at least partially disposed in the second recess, and one end of the first optical fiber is connected to one end of the third mode field matching unit. The third mode field matching unit is any one of a graded-index fiber, a graded-index prism, a thermal diffusion coefficient fiber, or a tapered waveguide.

18. The optical connection system of claim 17, wherein, A pitch of the third mode field matching unit is 0.25 x P, and a pitch of the first mode field matching unit is 0.25 x Q, where P is a positive integer and Q is a positive integer.

19. An optical connection system, characterized by The first fiber connector, the adapter, and the hollow fiber connector of any one of claims 9-12 are included, wherein: The first fiber connector includes a second ferrule and a first optical fiber, and the first optical fiber is at least partially disposed in a bore of the second ferrule; The adapter includes a sleeve configured to secure the second ferrule and the first ferrule to coaxially align the first optical fiber and the hollow fiber; The mode field size of the first optical fiber corresponds to the mode field size of the first end, and the first optical fiber is a hollow fiber type or a solid fiber type.

20. The optical connection system of claim 19, wherein, The second ferrule and the first ferrule are adjacent, and a pitch of the first mode field matching unit is 0.25 x K, where K is a positive integer.

21. The optical connection system of claim 19, wherein, The adapter further comprises a second mode field matching unit, which is arranged between the second ferrule and the first ferrule, and is any one of a graded-index fiber, a graded-index prism, a thermal diffusion coefficient fiber, or a tapered waveguide.

22. The optical connection system of claim 21, wherein, The pitch of the second mode field matching unit is 0.25×S, and the pitch of the first mode field matching unit is 0.5×L, S is a positive integer, and L is a positive integer.

23. The optical connection system of claim 19, wherein, The first fiber connector further comprises a third mode field matching unit, wherein: One end of the second ferrule is provided with a second groove adjacent to the first ferrule, and the third mode field matching unit is at least partially arranged in the second groove, and one end of the first fiber is connected to one end of the third mode field matching unit. The third mode field matching unit is any one of a graded-index fiber, a graded-index prism, a thermal diffusion coefficient fiber, or a tapered waveguide.

24. The optical connection system of claim 23, wherein, The pitch of the third mode field matching unit is 0.25×P, and the pitch of the first mode field matching unit is 0.25×Q, P is a positive integer, and Q is a positive integer.

25. An optical module characterized by comprising: The optical chip is optically coupled to the hollow fiber connector.

26. An optical module characterized by comprising: The optical chip is optically coupled to the hollow fiber connector.

27. An optical connection system, characterized by The optical module is internally provided with an optical chip, and the optical chip is optically coupled to the hollow fiber connector. The optical module is internally provided with an optical chip, and the optical chip is optically coupled to the hollow fiber connector.

28. An optical connection system, characterized by ​ ​

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