A fiber optic communication passive repeater system and method

Abstract

The application discloses an optical fiber communication passive relay system and method, belonging to the field of optical fiber communication, comprising a first end station and a second end station located at both ends of a communication link, and a passive gain unit located in the middle of the communication link, wherein the first end station and the passive gain unit are connected in series through anti-resonant hollow optical fibers, and the second end station and the passive gain unit are also connected in series through anti-resonant hollow optical fibers; the passive gain unit comprises a solid doped optical fiber and two mode field adapters arranged at both ends of the solid doped optical fiber and used for connecting the anti-resonant hollow optical fibers; the first end station is used for transmitting signal light and pump light to the passive gain unit through the anti-resonant hollow optical fibers; and the passive gain unit amplifies the signal light by using the received pump light and transmits the amplified signal light to the second end station through the anti-resonant hollow optical fibers. The application can amplify the signal light by using the passive gain unit, does not need power supply, simplifies the structure of a submarine cable, reduces the cost, and improves the single-fiber transmission capacity and distance.

Description

Technical Field

[0001] This application relates to the field of optical fiber communication, specifically to an optical fiber communication passive repeater system and method. Background Technology

[0002] Ultra-long-distance submarine optical cable communication forms the backbone of the global internet. Signals weaken during transmission through optical fibers due to attenuation, necessitating the placement of optical repeaters (or optical amplifiers) along the route for signal amplification. Currently, the core technology for transoceanic communication is an active repeater system based on erbium-doped fiber amplifiers (EDFAs). After transmitting approximately 60-100 kilometers in traditional solid-core single-mode fiber (SSMF), signals attenuate and require a repeater for optical-electrical-optical regeneration or all-optical amplification. Traditional repeaters based on EDFA technology require power to supply power to their internal pump lasers and electronic control units. In the deep-sea environment, power is transmitted over long distances through copper conductors in the cable, and the conductor's resistance leads to significant power loss.

[0003] Due to this power supply bottleneck, the number of repeaters a single submarine cable can support is limited, directly restricting the further extension of repeaterless transmission distance. Although repeaterless systems can achieve longer distances by using ultra-high power pump sources and ultra-low loss optical fibers, they are costly and complex in design. Therefore, there is an urgent need for a new method that can significantly reduce the power demand of repeater links to overcome the limitations of transmission distance. Summary of the Invention

[0004] This application provides a passive repeater system and method for optical fiber communication based on anti-resonant hollow-core fiber (AR-HCF) and solid-core doped fiber, which can solve the technical problems in the prior art that are limited by power supply bottlenecks, the number of repeaters supported by a single submarine cable is limited, and signal light is difficult to transmit over long distances.

[0005] In a first aspect, embodiments of this application provide a passive optical fiber communication repeater system. The passive optical fiber communication repeater system includes a first end station and a second end station located at both ends of the communication link, and a passive gain unit located in the middle of the communication link. Anti-resonant hollow optical fibers are connected in series between the first end station and the passive gain unit, and between the second end station and the passive gain unit. The passive gain unit includes a solid doped optical fiber and two mode field adapters disposed at both ends of the solid doped optical fiber for connecting with the anti-resonant hollow optical fiber. The first terminal station is used to transmit the signal light and pump light to the passive gain unit through the anti-resonant hollow optical fiber; The passive gain unit amplifies the signal light using the received pump light and transmits the amplified signal light to the second end station through an anti-resonant hollow optical fiber.

[0006] In conjunction with the first aspect, in one embodiment, both the first terminal station and the second terminal station include a signal transceiver and a pump laser. The signal transceiver is used to transmit and receive signal light, and the pump light exciter is used to transmit and receive pump light.

[0007] In conjunction with the first aspect, in one embodiment, both the first and second terminal stations include a wavelength division multiplexer connected to a transceiver and a pump light exciter for coupling the pump laser and signal light into an anti-resonant hollow fiber.

[0008] In conjunction with the first aspect, in one embodiment, the wavelength division multiplexer employs solid optical fiber.

[0009] In conjunction with the first aspect, in one embodiment, the solid doped optical fiber is a rare earth doped optical fiber.

[0010] In conjunction with the first aspect, in one embodiment, the rare earth-doped optical fiber is an erbium-doped optical fiber, a ytterbium-doped optical fiber, or an erbium-ytterbium co-doped optical fiber.

[0011] In conjunction with the first aspect, in one embodiment, the first and second terminal stations further include a monitoring unit based on an optical time-domain reflectometer or an optical frequency-domain reflectometer, used for real-time loss monitoring and fault location of the entire link.

[0012] In conjunction with the first aspect, in one embodiment, the passive gain unit is hermetically encapsulated within an armored container.

[0013] Secondly, embodiments of this application provide a passive optical fiber communication repeater method, the passive optical fiber communication repeater method comprising: Signal light and pump light are emitted from the first end station and transmitted to a passive gain unit using an anti-resonant hollow fiber. The mode field adapter in the passive gain unit, located near the first end station, performs mode field characteristic conversion on the signal light and pump light before transmitting them into a solid doped fiber. The solid doped fiber amplifies the signal light using the pump light. The mode field adapter in the passive gain unit, located near the second end station, performs mode field characteristic conversion on the amplified signal light before transmitting it into the solid doped fiber, where the amplified signal light is received by the second end station.

[0014] In conjunction with the second aspect, in one embodiment, the method further includes the step of injecting probe light into the link through a monitoring unit in the first and / or second end station and analyzing its backscattered signal to monitor system performance and operating status in real time.

[0015] The beneficial effects of the technical solutions provided in this application include: The middle section of the system (from coast to coast) is completely passive, with no electronic components or power supply equipment. This completely eliminates the biggest source of failure, active repeaters, and the system's mean time between failures (MTBF) theoretically depends only on the lifespan of the optical fiber itself, resulting in an order-of-magnitude improvement in reliability. Using hollow optical fiber to transmit both signal light and pump light simultaneously, and completing the optical amplification of the signal light within the gain unit, the repeater becomes passive, simplifying the submarine cable structure (eliminating the need for high-voltage power supply conductors), manufacturing process, shipboard deployment process, and post-maintenance complexity, resulting in a significant reduction in total cost. It fully leverages the potential of AR-HCF, providing an absolute advantage for latency-sensitive applications such as finance and AI through near-vacuum light speed transmission; negligible nonlinearity allows for higher power injection; and extremely low transmission loss enables high pump power even over long distances.

[0016] The bidirectional pump structure enables the pump light to be efficiently superimposed at the center of the gain medium, resulting in high energy utilization and the ability to achieve higher amplification gain. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the architecture of an embodiment of the passive repeater system for optical fiber communication of this application; Figure 2 This is a schematic diagram of the architecture of an embodiment of the passive gain unit of this application. Detailed Implementation

[0018] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0019] First, some of the technical terms used in this application will be explained to help those skilled in the art understand this application.

[0020] Anti-resonant hollow fiber (AR-HCF) confines light to the air through its microstructure cladding, supporting wideband transmission, near-light-speed-in-a-vacuum propagation, theoretically extremely low transmission loss, and negligible nonlinear effects. AR-HCF itself cannot provide optical gain and cannot be directly used for ultra-long-distance transmission requiring energy compensation. However, due to its wideband transmission capability, AR-HCF can simultaneously transmit signal light and the pump light band required by optical amplifiers.

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0022] In one aspect, embodiments of this application provide a passive repeater method for ultra-high reliability, ultra-low latency, and ultra-large capacity marine optical fiber communication. This method utilizes anti-resonant hollow-core optical fiber for ultra-long-distance signal and pump light transmission, and employs one or more segments of solid-core doped optical fiber for remote unidirectional or bidirectional pump amplification. The aim is to completely eliminate all active devices in the submarine cable link, achieving repeaterless transmission over transoceanic distances through an extremely simplified single-point amplification architecture.

[0023] In one embodiment, reference is made to Figure 1 and Figure 2 , Figure 1 This is a schematic diagram of the architecture of the first embodiment of the passive repeater system for optical fiber communication in this application. Figure 2 This is a schematic diagram of the architecture of an embodiment of the passive gain unit 106 of this application. Figure 1 and Figure 2 As shown, the optical fiber communication passive repeater system includes a first end station and a second end station located at both ends of the communication link, and a passive gain unit 106 located in the middle of the communication link. Anti-resonant hollow optical fibers are connected in series between the first end station and the passive gain unit 106, and between the second end station and the passive gain unit 106. The passive gain unit 106 includes a solid doped optical fiber 105 and two mode field adapters 104 disposed at both ends of the solid doped optical fiber 105 for connecting with the anti-resonant hollow optical fiber.

[0024] The aforementioned first terminal station is used to transmit signal light and pump light to passive gain unit 106 via anti-resonant hollow optical fiber.

[0025] The passive gain unit 106 amplifies the signal light using the received pump light and transmits the amplified signal light to the second terminal station through an anti-resonant hollow optical fiber.

[0026] In this embodiment, the first and second end stations located at both ends of the communication link are equipped with an optical signal transmitter (i.e., a transceiver 101) and a high-power pump laser 102. The optical transmission direction can be from the first end station to the second end station or from the second end station to the first end station. The passive gain unit 106 supports bidirectional transmission. Furthermore, the signal light emitted from the first end station can be amplified within the passive gain unit 106 using the pump light emitted from the first end station, or it can be amplified using the pump light emitted from both the first and second end stations bidirectionally. Similarly, the signal light emitted from the second end station can be amplified within the passive gain unit 106 using the pump light emitted from the second end station, or it can be amplified using the pump light emitted from both the first and second end stations bidirectionally.

[0027] The signal and pump light coupling assembly (i.e., wavelength division multiplexer 103), located at the first and second end stations at both ends of the communication link, is used to couple the pump laser and signal light into the anti-resonant hollow fiber.

[0028] The first anti-resonant hollow fiber segment and the second anti-resonant hollow fiber segment, connected in series, together constitute the main signal transmission channel.

[0029] The passive gain unit 106 has its input end optically connected to the output end of the first anti-resonant hollow fiber segment, and its output end optically connected to the input end of the second anti-resonant hollow fiber segment.

[0030] The passive gain unit 106 is used to receive two pump lights from both ends and use the energy generated by their convergence within the unit to amplify the passing communication signal light.

[0031] In summary, the mid-section of the system (from coast to coast) is completely passive, without any electronic components or power supply equipment. This completely eliminates the biggest source of failure—active repeaters—and the system's mean time between failures (MTBF) theoretically depends only on the lifespan of the optical fiber itself, resulting in an order-of-magnitude improvement in reliability.

[0032] Using hollow-core optical fiber to transmit both signal light and pump light simultaneously, and completing the optical amplification of the signal light within the gain unit 106, the repeater becomes passive, simplifying the submarine cable structure (eliminating the need for high-voltage power supply conductors), manufacturing process, shipboard deployment procedures, and post-maintenance complexity, resulting in a significant reduction in total cost.

[0033] It fully leverages the potential of AR-HCF, providing a significant advantage for latency-sensitive applications such as finance and AI through near-vacuum-speed transmission. Negligible nonlinearity allows for higher power injection. Extremely low transmission loss enables high pump power even over long distances.

[0034] The bidirectional pump structure enables the pump light to be efficiently superimposed at the center of the gain medium, resulting in high energy utilization and the ability to achieve higher amplification gain.

[0035] Furthermore, in one embodiment, both the first and second terminal stations mentioned above include a signal transceiver 101 and a pump laser.

[0036] The aforementioned transceiver 101 is used to transmit and receive signal light, and the aforementioned pump light exciter is used to transmit and receive pump light.

[0037] In this embodiment, the signal and pump light, coupled by the signal and pump light coupling component, are emitted from the first end station and transmitted through the first anti-resonant hollow fiber segment to the passive gain unit 106. When the communication signal light reaches the passive gain unit 106, the pump light energy is used to amplify the communication signal light. The amplified communication signal light then enters the second anti-resonant hollow fiber segment for further transmission and is finally received by the second end station.

[0038] This system can be bidirectional, meaning that the signal and pump light, coupled by a signal and pump light coupling component, are emitted from the second end station and transmitted through the second anti-resonant hollow fiber segment to the passive gain unit 106. When the communication signal light reaches the passive gain unit 106, it is amplified using pump light energy. The amplified communication signal light then enters the first anti-resonant hollow fiber segment for further transmission and is ultimately received by the first end station.

[0039] Furthermore, in one embodiment, both the first and second end stations include a wavelength division multiplexer 103, which is connected to a signal transceiver 101 and a pump light exciter, and is used to couple the pump laser and signal light into an anti-resonant hollow fiber. The wavelength division multiplexer 103 uses solid fiber.

[0040] In this embodiment, the wavelength division multiplexer 103 is a solid fiber independent of the anti-resonant hollow fiber.

[0041] Furthermore, in one embodiment, the solid doped optical fiber 105 is a rare-earth doped optical fiber. The rare-earth doped optical fiber is erbium-doped, ytterbium-doped, or a co-doped erbium-ytterbium optical fiber.

[0042] In this embodiment, the aforementioned central passive gain unit 106 includes a section of rare-earth-doped optical fiber, as well as a first mode field adapter and a second mode field adapter for realizing low-loss connection between the anti-resonant hollow optical fiber and the solid-core doped optical fiber.

[0043] Furthermore, in one embodiment, the first and second terminal stations also include a monitoring unit based on an optical time-domain reflectometer or an optical frequency-domain reflectometer, used for real-time loss monitoring and fault location of the entire link.

[0044] In this embodiment, the system performance and operating status are monitored in real time by injecting probe light into the link through the monitoring unit in the terminal station and analyzing its backscattered signal.

[0045] Furthermore, in one embodiment, the passive gain unit 106 is sealed and encapsulated in an armored container.

[0046] In this embodiment, the passive gain unit 106 is sealed and encapsulated in a high-pressure, watertight armored container and deployed in the submarine link.

[0047] In one specific embodiment, the terminal station facility includes a first terminal station and a second terminal station located at both ends of the communication link (i.e., land A and land B). Each terminal station is equipped with a signal transceiver 101, a high-power pump laser 102, and a monitoring unit.

[0048] The signal transceiver 101 is used to generate, modulate, transmit, and receive communication signal light (λs).

[0049] The high-power pump laser 102 is used to generate pump light (λp1, λp2) of a specific wavelength, the power of which can be adjusted according to the total link loss, typically ranging from hundreds of mW to several W.

[0050] The monitoring unit is based on the principles of optical time-domain reflectometer (OTDR) and optical frequency-domain reflectometer (OFDR) and is used to monitor the loss characteristics of the entire link in real time, locate fault points, and evaluate the gain status of the central gain unit 106.

[0051] The system's main transmission media are a first anti-resonant hollow fiber segment and a second anti-resonant hollow fiber segment, which are connected in series to form the main signal transmission channel that runs through the entire ocean link. Its length can be designed according to the transoceanic distance, with a single segment length ranging from 1500 km to 4000 km.

[0052] The central passive gain unit 106 is the only solid-core fiber in the system, sealed within a high-pressure, watertight armored container and deployed at the geographical center of the submarine link. This unit specifically includes: a rare-earth-doped fiber: a section of high-gain erbium-doped fiber (EDF), which can also be ytterbium-doped fiber (YDF) or erbium-ytterbium co-doped fiber (EYDF), with an optimized length (e.g., several meters to tens of meters) to provide sufficient gain to compensate for the overall link loss under bidirectional pumping; and a first-mode field adapter and a second-mode field adapter: used to achieve a low-loss optical connection between the anti-resonant hollow-core fiber and the solid-core erbium-doped fiber. This adapter can be a tapered fiber, a microlens, or a specific mode field conversion fiber to match the air-core mode of the AR-HCF with the silicon-based solid-core mode of the EDF.

[0053] Secondly, embodiments of this application also provide a passive optical fiber communication repeater method based on anti-resonant hollow optical fiber and solid doped optical fiber.

[0054] In one embodiment, the above-mentioned passive repeater method for optical fiber communication based on anti-resonant hollow fiber and solid doped fiber includes: Signal light and pump light are emitted from the first end station and transmitted to the passive gain unit 106 via anti-resonant hollow fiber. The mode field adapter 104 in the passive gain unit 106, located near the first end station, performs mode field characteristic conversion on the signal light and pump light before transmitting them to the solid doped fiber 105. The solid doped fiber 105 amplifies the signal light using the pump light. The mode field adapter 104 in the passive gain unit 106, located near the second end station, performs mode field characteristic conversion on the amplified signal light before transmitting it to the solid doped fiber 105, where the amplified signal light is received by the second end station.

[0055] In this embodiment, the first and second end stations located at both ends of the communication link are equipped with an optical signal transmitter (i.e., a transceiver 101) and a high-power pump laser 102. The optical transmission direction can be from the first end station to the second end station or from the second end station to the first end station. The passive gain unit 106 supports bidirectional transmission. Furthermore, the signal light emitted from the first end station can be amplified within the passive gain unit 106 using the pump light emitted from the first end station, or it can be amplified using the pump light emitted from both the first and second end stations bidirectionally. Similarly, the signal light emitted from the second end station can be amplified within the passive gain unit 106 using the pump light emitted from the second end station, or it can be amplified using the pump light emitted from both the first and second end stations bidirectionally.

[0056] The signal and pump light coupling assembly (i.e., wavelength division multiplexer 103), located at the first and second end stations at both ends of the communication link, is used to couple the pump laser and signal light into the anti-resonant hollow fiber.

[0057] The first anti-resonant hollow fiber segment and the second anti-resonant hollow fiber segment, connected in series, together constitute the main signal transmission channel.

[0058] The passive gain unit 106 has its input end optically connected to the output end of the first anti-resonant hollow fiber segment, and its output end optically connected to the input end of the second anti-resonant hollow fiber segment.

[0059] The passive gain unit 106 is used to receive two pump lights from both ends and use the energy generated by their convergence within the unit to amplify the passing communication signal light.

[0060] In summary, the mid-section of the system (from coast to coast) is completely passive, without any electronic components or power supply equipment. This completely eliminates the biggest source of failure—active repeaters—and the system's mean time between failures (MTBF) theoretically depends only on the lifespan of the optical fiber itself, resulting in an order-of-magnitude improvement in reliability.

[0061] Using hollow-core optical fiber to transmit both signal light and pump light simultaneously, and completing the optical amplification of the signal light within the gain unit 106, the repeater becomes passive, simplifying the submarine cable structure (eliminating the need for high-voltage power supply conductors), manufacturing process, shipboard deployment procedures, and post-maintenance complexity, resulting in a significant reduction in total cost.

[0062] It fully leverages the potential of AR-HCF, providing a significant advantage for latency-sensitive applications such as finance and AI through near-vacuum-speed transmission. Negligible nonlinearity allows for higher power injection. Extremely low transmission loss enables high pump power even over long distances.

[0063] The bidirectional pump structure enables the pump light to be efficiently superimposed at the center of the gain medium, resulting in high energy utilization and the ability to achieve higher amplification gain.

[0064] The functions of each module in the aforementioned passive optical fiber repeater device correspond to the steps in the aforementioned passive optical fiber repeater method embodiment, and their functions and implementation processes will not be described in detail here.

[0065] In one specific embodiment, the optical fiber passive repeater method utilizing the above-described optical fiber passive repeater system includes the following steps: The signal transmission steps include transmitting a communication signal light (λs) carrying information from the first terminal station, which then enters the first anti-resonant hollow fiber segment for transmission. The signal light, thanks to the ultra-low loss and low nonlinearity characteristics of the anti-resonant hollow fiber (AR-HCF), can transmit over extremely long distances.

[0066] The bidirectional pump initiation process includes the simultaneous emission of pump light (λp1, λp2) from high-power pump lasers 102 at both the first and second end stations. The pump light is transmitted remotely through the same anti-resonant hollow fiber AR-HCF.

[0067] The concentrated energy amplification step involves the communication signal light and pump light, after power attenuation during transmission through the first segment of anti-resonant hollow fiber (AR-HCF), converging in the erbium-doped fiber within the passive gain unit 106. The pump light achieves extremely high population inversion in the erbium-doped fiber, thereby amplifying the passing communication signal light (primarily due to the amplification effect of the remotely pumped erbium-doped fiber), compensating for all losses in the upstream link.

[0068] The signal continues to be transmitted and received, including the significantly amplified communication signal light entering the second anti-resonant hollow fiber segment through the second mode field adapter, and continuing to be transmitted to the second end station thanks to the excellent characteristics of AR-HCF, and finally being detected and demodulated by the receiver at the second end station with a sufficiently high signal-to-noise ratio.

[0069] The reverse communication step, including the communication process from the second end station to the first end station, is a mirror image of the above process, amplified by the same gain unit 106, and the principle is exactly the same.

[0070] The system monitoring steps include the monitoring unit in the terminal station periodically injecting low-power probe light into the link, analyzing the backscatter signal, monitoring the loss changes of the entire link in real time, locating any potential microbends or damage points, evaluating the gain performance of the central gain unit 106, and remotely adjusting the power of the high-power pump laser 102 to optimize the system status when necessary.

[0071] For example, consider a transoceanic link with a total length of L: During the link design phase, the entire link is divided into two equal-length anti-resonant hollow fiber segments, each approximately L / 2 in length.

[0072] During the deployment phase of the gain unit 106, a waterproof and pressure-resistant sealed container is deployed at a distance of L / 2 from both ends on the seabed, and the passive gain unit 106 is encapsulated inside.

[0073] In the pump scheme, the pump light emitted by both ends of the station has the same wavelength (e.g., 980 nm), and the power needs to be precisely calculated to ensure that it can provide enough gain to compensate for the L / 2 distance loss after the gain unit 106 is combined.

[0074] The total signal loss from point A to point B is approximately equal to (hollow fiber loss × L / 2 + insertion loss of gain unit 106 + hollow fiber loss × L / 2). The gain provided by gain unit 106 must be greater than this total loss, with sufficient system margin.

[0075] It should be noted that the sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0076] The terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus. The terms "first," "second," and "third," etc., are used to distinguish different objects, etc., and do not indicate a sequence, nor do they limit "first," "second," and "third" to different types.

[0077] In the description of the embodiments of this application, terms such as "exemplary," "for example," or "for instance" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "exemplary," "for example," or "for instance" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary," "for example," or "for instance" is intended to present the relevant concepts in a concrete manner.

[0078] In the description of the embodiments of this application, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. The "and / or" in the text is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of this application, "multiple" means two or more.

[0079] In some processes described in the embodiments of this application, multiple operations or steps are included in a specific order. However, it should be understood that these operations or steps may not be executed in the order they appear in the embodiments of this application, or they may be executed in parallel. The sequence number of the operation is only used to distinguish different operations, and the sequence number itself does not represent any execution order. In addition, these processes may include more or fewer operations, and these operations or steps may be executed sequentially or in parallel, and these operations or steps may be combined.

[0080] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes several instructions to cause a terminal device to execute the methods described in the various embodiments of this application.

[0081] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A passive repeater system for optical fiber communication, characterized in that, The optical fiber communication passive repeater system includes a first terminal station and a second terminal station located at both ends of the communication link, and a passive gain unit located in the middle of the communication link. Anti-resonant hollow optical fibers are connected in series between the first terminal station and the passive gain unit, and between the second terminal station and the passive gain unit. The passive gain unit includes a solid doped optical fiber and two mode field adapters disposed at both ends of the solid doped optical fiber for connecting with the anti-resonant hollow optical fiber. The first terminal station is used to transmit the signal light and pump light to the passive gain unit through the anti-resonant hollow optical fiber; The passive gain unit amplifies the signal light using the received pump light and transmits the amplified signal light to the second end station through an anti-resonant hollow optical fiber.

2. The passive optical fiber communication repeater system as described in claim 1, characterized in that, Both the first and second terminal stations include a signal transceiver and a pump laser; The signal transceiver is used to transmit and receive signal light, and the pump light exciter is used to transmit and receive pump light.

3. The passive optical fiber communication repeater system as described in claim 2, characterized in that, Both the first and second end stations include a wavelength division multiplexer, which connects a signal transceiver and a pump light exciter to couple the pump laser and signal light into an anti-resonant hollow fiber.

4. The passive optical fiber communication repeater system as described in claim 3, characterized in that, The wavelength division multiplexer uses solid optical fiber.

5. The passive optical fiber communication repeater system as described in claim 1, characterized in that, The solid doped optical fiber is a rare earth doped optical fiber.

6. The passive optical fiber communication repeater system as described in claim 5, characterized in that, The rare earth-doped optical fiber is an erbium-doped optical fiber, a ytterbium-doped optical fiber, or an erbium-ytterbium co-doped optical fiber.

7. The passive optical fiber communication repeater system as described in claim 1, characterized in that, The first and second terminal stations also include monitoring units based on optical time-domain reflectometers or optical frequency-domain reflectometers, used for real-time loss monitoring and fault location of the entire link.

8. The passive optical fiber communication repeater system as described in claim 1, characterized in that, The passive gain unit is sealed and encapsulated in an armored container.

9. A passive repeater method for optical fiber communication, characterized in that, The passive repeater method for optical fiber communication includes: Signal light and pump light are emitted from the first end station and transmitted to a passive gain unit using an anti-resonant hollow fiber. The mode field adapter in the passive gain unit, located near the first end station, performs mode field characteristic conversion on the signal light and pump light before transmitting them into a solid doped fiber. The solid doped fiber amplifies the signal light using the pump light. The mode field adapter in the passive gain unit, located near the second end station, performs mode field characteristic conversion on the amplified signal light before transmitting it into the solid doped fiber, where the amplified signal light is received by the second end station.

10. The passive repeater method for optical fiber communication as described in claim 9, characterized in that, The method further includes the step of injecting probe light into the link through a monitoring unit in the first and / or second end station and analyzing its backscattered signal to monitor system performance and operating status in real time.

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