Optical amplifier system and optical communication system

Abstract

The present application relates to the technical field of optical communications, and is used for ameliorating the problem of costs of optical amplifier systems being relatively high. Provided are an optical amplifier system and an optical communication system. The optical amplifier system comprises multiple stages of optical amplifiers, which are connected in sequence, wherein at least one stage of optical amplifier is a double-pass optical amplifier, and a pump bidirectional bypass is provided between a first optical amplifier and a second optical amplifier from among the multiple stages of optical amplifiers; and the pump bidirectional bypass, which is used for directing residual pump light in the first optical amplifier into the second optical amplifier or directing residual pump light in the second optical amplifier into the first optical amplifier. At least one stage of double-pass optical amplifier is used in the optical amplifier system provided in the embodiments of the present application, such that the pump conversion efficiency can be improved and the residual pump can be reduced; and by means of providing a pump bidirectional bypass between different stages of optical amplifiers, and sharing residual pump light between two stages of optical amplifiers, the pump conversion efficiency can be improved, and the costs of the optical amplifier system can then be reduced by means of reducing the pump power or reducing the pump consumption.

Description

Optical amplifier system and optical communication system

[0001] This application claims priority to Chinese Patent Application No. 202411673233.8, filed on November 20, 2024, entitled "Optical Amplifier System and Optical Communication System", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of optical communication technology, and in particular to an optical amplifier system and an optical communication system. Background Technology

[0003] Optical communication systems refer to communication systems that use light as the carrier and optical fiber as the transmission medium. Optical communication systems have advantages such as high bandwidth, high capacity, and low latency, and are widely used for transmitting large amounts of data. Higher-speed code patterns and broadened spectrum can be used in optical communication systems to increase communication capacity, but these require higher-power signal light and higher-power optical amplifiers.

[0004] The pump laser accounts for a large proportion of the cost of optical amplifiers, so improving conversion efficiency and reducing power consumption and cost of optical amplifiers have become urgent problems to be solved. Summary of the Invention

[0005] This application provides an optical amplifier system and an optical communication system to address the issue of high cost in optical amplifier systems.

[0006] To achieve the above objectives, the technical solutions adopted in the embodiments of this application are as follows:

[0007] In a first aspect, an optical amplifier system is provided, comprising a multi-stage optical amplifier connected in sequence, the multi-stage optical amplifier including a first optical amplifier and a second optical amplifier, the optical amplifier system further comprising a pump bidirectional bypass, the first optical amplifier and the second optical amplifier being connected via the pump bidirectional bypass, the pump bidirectional bypass being used to guide residual pump light from the first optical amplifier into the second optical amplifier, and to guide residual pump light from the second optical amplifier into the first optical amplifier.

[0008] The optical amplifier system provided in this application provides a bidirectional pump bypass between different stages of optical amplifiers. The bidirectional pump bypass can achieve the sharing of residual pump light between the two stages of optical amplifiers. For example, the residual pump light of the first optical amplifier can be absorbed again in the second optical amplifier, and the residual pump light in the second optical amplifier can also be absorbed again in the first optical amplifier. This can increase the proportion of pump light absorbed and improve the pump conversion efficiency. With the improvement of pump conversion efficiency, the cost of the optical amplifier system can be reduced by reducing the pump power or the amount of pump used.

[0009] In one implementation of the first aspect, each of the multi-stage optical amplifiers includes a pump input device and a gain fiber. The pump input device is used to input pump light into the gain fiber to amplify the input signal light. The bidirectional pump bypass includes a first pump input / output device, a second pump input / output device, and an optical waveguide. Both the first pump input / output device and the second pump input / output device include a common end and a first end. The common end of the first pump input / output device is coupled to the gain fiber of the first optical amplifier, and the common end of the second pump input / output device is coupled to the gain fiber of the second optical amplifier. The first end of the first pump input / output device is coupled to the first end of the second pump input / output device through the optical waveguide. The second pump input / output device is used to input the residual pump light output by the first pump input / output device into the gain fiber of the second optical amplifier through the common end. The first pump input / output device is used to input the residual pump light output by the second pump input / output device into the gain fiber of the first optical amplifier through the common end.

[0010] In one implementation of the first aspect, the first pump input / output device further includes a second end. If the transmission direction of the pump light in the first optical amplifier is opposite to the transmission direction of the signal light, the second end of the first pump input / output device is used to receive the signal light to be amplified by the first optical amplifier; if the transmission direction of the pump light in the first optical amplifier is the same as the transmission direction of the signal light, the second end of the first pump input / output device is used to output the signal light amplified by the first optical amplifier. The second pump input / output device further includes a second end. If the transmission direction of the pump light in the second optical amplifier is opposite to the transmission direction of the signal light, the second end of the second pump input / output device is used to receive the signal light to be amplified by the second optical amplifier; if the transmission direction of the pump light in the second optical amplifier is the same as the transmission direction of the signal light, the second end of the second pump input / output device is used to output the signal light amplified by the first optical amplifier.

[0011] In one implementation of the first aspect, at least one stage of the multi-stage optical amplifier is a two-way optical amplifier. In the two-way optical amplifier, the signal light can pass through the gain fiber twice. When passing through the gain fiber for the first time, the pump light can be absorbed to achieve amplification. When passing through the gain fiber for the second time, the pump light in the gain fiber can be absorbed again to achieve amplification. The pump light in the gain fiber is utilized twice, which can reduce pump residue, improve pump conversion efficiency, thereby reducing the power requirement of the pump light source of the optical amplifier and reducing the cost of the optical amplifier system.

[0012] In one implementation of the first aspect, the optical amplifier system includes an input terminal and an output terminal. The input terminal is connected to the output terminal through an m-stage single-pass optical amplifier, an n-stage double-pass optical amplifier, and a k-stage single-pass optical amplifier connected in sequence, where m, n, and k are integers greater than or equal to 1.

[0013] In one implementation of the first aspect, the n-stage double-pass optical amplifier includes a first optical amplifier, and the m-stage single-pass optical amplifier includes a second optical amplifier; or, the n-stage double-pass optical amplifier includes a first optical amplifier, and the k-stage single-pass optical amplifier includes a second optical amplifier. Since the gain fiber of the double-pass optical amplifier is relatively short and has a large amount of residual pump light, a bidirectional pump bypass can be set between a portion of the double-pass optical amplifiers and the preceding single-pass optical amplifiers to ensure a low noise figure for the optical amplifier system. Another portion of the double-pass optical amplifiers can be bidirectionally bypassed with the subsequent single-pass optical amplifiers to ensure high pump conversion efficiency.

[0014] In one implementation of the first aspect, the m-stage single-pass optical amplifier includes a first optical amplifier, and the k-stage single-pass optical amplifier includes a second optical amplifier; or, n is an integer greater than or equal to 2, and the n-stage double-pass optical amplifier includes a first optical amplifier and a second optical amplifier. In this embodiment, a pump bidirectional bypass is provided between the earlier m-stage optical amplifier and the later k-stage optical amplifier to provide more residual pump light from the earlier m-stage optical amplifier to the later k-stage optical amplifier, thereby improving pump conversion efficiency; a pump bidirectional bypass can also be provided between the n-stage optical amplifiers in the middle section to further improve pump conversion efficiency.

[0015] In one implementation of the first aspect, the optical amplifier system includes an input terminal and an output terminal. The input terminal is connected to the output terminal via an m-stage single-pass optical amplifier and an n-stage double-pass optical amplifier connected in sequence, where m and n are integers greater than or equal to 1.

[0016] In one implementation of the first aspect, the m-level single-pass optical amplifier includes a first optical amplifier, and the n-level double-pass optical amplifier includes a second optical amplifier.

[0017] In one implementation of the first aspect, n is an integer greater than or equal to 2, and the n-stage two-way optical amplifier includes a first optical amplifier and a second optical amplifier.

[0018] In one implementation of the first aspect, the optical amplifier system includes an input terminal and an output terminal. The input terminal is connected to the output terminal via an m-stage double-pass optical amplifier and an n-stage single-pass optical amplifier connected in sequence, where m and n are integers greater than or equal to 1. Setting the earlier stages of the optical amplifier system as double-pass optical amplifiers can improve pump conversion efficiency, reduce residual pump light in the first m-stage optical amplifiers, and improve the pump conversion efficiency of the entire optical amplifier system.

[0019] In one implementation of the first aspect, the m-stage two-way optical amplifier includes a first optical amplifier and the n-stage one-way optical amplifier includes a second optical amplifier, so as to reuse the residual pump light in each stage of the optical amplifier and improve the pump conversion efficiency.

[0020] In one implementation of the first aspect, all multi-stage optical amplifiers are two-way optical amplifiers. The multi-stage optical amplifier architecture composed of two-way optical amplifiers can achieve higher pump conversion efficiency.

[0021] In one implementation of the first aspect, the optical amplifier system includes an m-stage double-pass optical amplifier, an n-stage single-pass optical amplifier, and a k-stage double-pass optical amplifier connected in sequence, wherein m, n, and k are integers greater than or equal to 1.

[0022] In one implementation of the first aspect, the optical amplifier further includes a pump source for outputting pump light. Each optical amplifier can be equipped with an independent pump source. Since the optical amplifier system in this scheme is equipped with a bidirectional pump bypass, the pump conversion efficiency can be improved by setting the bidirectional pump bypass, thereby reducing the power requirements of the optical amplifier on the pump source and reducing the system cost.

[0023] In one implementation of the first aspect, the optical amplifier system further includes a pump light source and a beam splitter. The pump light source is used to output pump light, and the beam splitter is used to split the pump light into beams so that the pump light is output to at least two optical amplifiers in the multi-stage optical amplifier. Since the multi-stage optical amplifier system provided in this application embodiment can reduce the amount of pump by setting a bidirectional pump bypass, different stages of optical amplifiers can share the same pump light source, thereby reducing costs.

[0024] In a second aspect, an optical communication system is provided, comprising a first communication device, a second communication device, and an optical amplification system as provided in the first aspect and any implementation thereof; the first communication device is connected to the second communication device via the optical amplification system. Attached Figure Description

[0025] Figure 1 is a schematic diagram of an optical communication system provided in an embodiment of this application;

[0026] Figure 2 is a schematic diagram of a multi-stage optical amplifier provided in an embodiment of this application;

[0027] Figure 3 is a schematic diagram of the structure of an optical amplifier provided in an embodiment of this application;

[0028] Figure 4 is a schematic diagram of an optical amplifier system provided in an embodiment of this application;

[0029] Figure 5 is a schematic diagram of another optical amplifier system provided in an embodiment of this application;

[0030] Figure 6 is a schematic diagram of another optical amplifier system provided in an embodiment of this application;

[0031] Figure 7 is a schematic diagram of another optical amplifier system provided in an embodiment of this application;

[0032] Figure 8 is a schematic diagram of another optical amplifier system provided in an embodiment of this application;

[0033] Figure 9 is a schematic diagram of the two-way optical amplifier provided in an embodiment of this application;

[0034] Figure 10 is a schematic diagram of another optical amplifier system provided in an embodiment of this application;

[0035] Figure 11 is a schematic diagram of another optical amplifier system provided in an embodiment of this application;

[0036] Figure 12 is a schematic diagram of another optical amplifier system provided in an embodiment of this application;

[0037] Figure 13 is a schematic diagram of another optical amplifier system provided in an embodiment of this application;

[0038] Figure 14 is a schematic diagram of another optical amplifier system provided in an embodiment of this application;

[0039] Figure 15 is a schematic diagram of another optical amplifier system provided in an embodiment of this application;

[0040] Figure 16 is a schematic diagram of another optical amplifier system provided in an embodiment of this application;

[0041] Figure 17 is a schematic diagram of another optical amplifier system provided in an embodiment of this application;

[0042] Figure 18 is a schematic diagram of another optical amplifier system provided in an embodiment of this application. Detailed Implementation

[0043] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0044] Hereinafter, the terms "first," "second," etc., are used for descriptive convenience only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "multiple" means two or more. For example, multiple processing units refer to two or more processing units.

[0045] In the embodiments of this application, unless otherwise explicitly specified and limited, the terms "coupling" and "connection" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a direct connection or an indirect connection through an intermediate medium, such as a connection achieved through optical fiber or other devices.

[0046] In this embodiment of the application, "and / or" describes the relationship between associated objects, indicating that there can be three kinds of relationships. For example, A and / or B can represent: A exists alone, B exists alone, and A and B exist simultaneously.

[0047] In this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" or "for example" in this application should not be construed as being better or more advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0048] The technical solutions provided in this application can be applied to optical communication systems, which are communication systems that use light as the carrier and optical fiber as the transmission medium. Optical communication systems have advantages such as high bandwidth, high capacity, and low latency, and are widely used for transmitting large amounts of data. With the rapid development of data center interconnect (DCI) and computing cluster applications, the demand for communication capacity in optical communication systems is becoming increasingly urgent.

[0049] Figure 1 is a schematic diagram of an optical communication system provided in an embodiment of this application. The optical communication system includes a first communication device 101, a second communication device 102, and an optical amplifier 103. The first communication device 101 can be a transmitting device in the optical communication system, and the second communication device 102 can be a receiving device in the optical communication system. Alternatively, the first communication device 101 and the second communication device 102 can be any two devices between the transmitting device and the receiving device in the optical communication system.

[0050] In one example, the optical amplifier 103 can serve as a repeater amplifier in an optical communication system, located between the first communication device 101 and the second communication device 102, amplifying the signal between them. In another example, the optical amplifier 103 can serve as a preamplifier in an optical communication system, located before the second communication device 102, amplifying the signal light entering the second communication device 102. In yet another example, the optical amplifier 103 can serve as a postamplifier in an optical communication system, located after the first communication device 101, amplifying the signal light output from the first communication device 101.

[0051] To increase the communication capacity of an optical communication system, higher-speed code patterns or spectral broadening can be employed. Both of these methods require higher-power signal light and higher-power optical amplifiers. To meet output power requirements, existing optical amplifiers typically employ a multi-stage cascaded approach, as shown in Figure 2. Figure 2 illustrates a schematic diagram of a multi-stage optical amplifier, comprising multiple cascaded optical amplifiers. The input signal light is amplified sequentially by these multi-stage amplifiers before being output, thus increasing the amplification gain.

[0052] Commonly used optical amplifiers include erbium-doped fiber amplifiers (EDFAs). Referring to Figure 3, Figure 3a shows a schematic diagram of an optical amplifier structure, which includes a pump source 21, a pump input device 22, and a gain fiber 23. The pump source 21 can be a pump laser, used to generate pump light, which is the energy source that excites the gain medium. The pump input device 22 couples the pump light into the gain fiber 23. Typically, a wavelength division multiplexer (WDM), a combiner, or other devices with similar functions can be used. Taking a WDM as an example, the pump input device 22 includes a common terminal C, a first terminal P1, and a second terminal P2. The common terminal C is coupled to the first terminal G1 of the gain fiber 23. The second terminal P2 receives the input signal light, and the first terminal P1 receives the pump light. The signal light can propagate between the second terminal P2 and the common terminal C, and the pump light can propagate between the first terminal P1 and the common terminal C. Gain fiber 23 can be erbium-doped fiber (EDF). Gain fiber 23 is the gain medium of the optical amplifier. After absorbing pump light, erbium ions will transition to an excited state. When the signal photon passes through, stimulated emission will occur, generating photons with the same frequency, direction, and polarization as the signal photon, thus amplifying the signal light. The amplified signal light is output through the second end G2 of gain fiber 23.

[0053] Optical amplifiers typically also include an isolator 24, which blocks light traveling in the opposite direction of the signal light transmission from passing through. By blocking light traveling in the opposite direction of the signal light transmission through the isolator 24, the reverse-direction light of the signal light can be prevented from affecting the optical amplifier. The signal light travels unidirectionally in the optical amplifier, passing through the gain fiber 23 only once. Such an optical amplifier is called a single-pass optical amplifier.

[0054] In the aforementioned optical amplifier, the propagation direction of the pump light is the same as that of the signal light, which is called co-directional pumping. Figure 3b shows a schematic diagram of another type of optical amplifier. The first end G1 of the gain fiber 23 is used to receive the signal light, the common end C of the pump input device 22 is coupled to the second end G2 of the gain fiber 23, the first end P1 of the pump input device 22 is used to receive the pump light, and the second end P2 of the pump input device 22 is used to output the amplified signal light. In this case, the propagation direction of the pump light is opposite to that of the signal light, which is called reverse pumping.

[0055] In the above multi-stage optical amplifier architecture, the absorption of pump light by the gain fiber in each stage of the optical amplifier is incomplete. The signal light travels through the gain fiber only once, resulting in low utilization efficiency of the pump light and a significant amount of residual pump light, i.e., low pump conversion efficiency. Here, pump conversion efficiency can be understood as the efficiency of amplifying the signal light using the pump light. Equation (1) shows one way to calculate pump conversion efficiency: R = (P out -P in ) / P pump (1)

[0056] In equation (1), R represents the pump conversion efficiency, and P out P represents the power of the output signal light after amplification by the optical amplifier. in P is the power of the signal light input to the optical amplifier. pump This refers to the power of the pump light. For multi-stage optical amplifier architectures, the higher the output power requirement, the more stages the optical amplifier has, and the more residual pump light there is, resulting in lower pump conversion efficiency, typically below 10%.

[0057] Due to the low pump conversion efficiency, higher pump power is required to increase the output signal light power, resulting in a larger pump quantity. In optical amplifiers, the cost of the pump light source accounts for a large proportion of the overall cost of the optical amplifier. The higher the power of the pump light source, the higher the cost. How to maintain a low cost of optical amplifiers while increasing the output power has become an urgent problem to be solved.

[0058] To address the issues of high pump usage, low conversion efficiency, and high cost in existing optical amplifier architectures, this application provides an optical amplifier system employing a multi-stage cascaded optical amplifier architecture. At least one stage of the optical amplifier is a two-way optical amplifier, where the signal light passes twice in the gain fiber, enhancing pump light absorption and reducing pump light residue. Simultaneously, a bidirectional pump bypass is established between different stages of the optical amplifiers to couple residual pump light to other stages, thereby increasing pump light absorption and reducing pump power and cost.

[0059] Please refer to Figure 4, which illustrates an optical amplifier system provided in an embodiment of this application. The optical amplifier system includes multiple stages of optical amplifiers connected in sequence. For example, the illustrated optical amplifier system shows optical amplifiers 31, 32, 33, and 34. The multi-stage optical amplifier includes a first optical amplifier and a second optical amplifier. A pump bidirectional bypass is provided between the first and second optical amplifiers. The pump bidirectional bypass is used to guide residual pump light from the first optical amplifier into the second optical amplifier, and to guide residual pump light from the second optical amplifier into the first optical amplifier. For example, a pump bidirectional bypass is provided between optical amplifiers 32 and 33, and between optical amplifiers 31 and 34.

[0060] In the optical amplifier system provided in this application embodiment, a pump bidirectional bypass is set between the first optical amplifier and the second optical amplifier. For example, taking the pump bidirectional bypass between optical amplifier 32 and optical amplifier 33 as an example, through this pump bidirectional bypass, the residual pump light in optical amplifier 32 can be coupled to optical amplifier 33, and the residual pump light in optical amplifier 33 can also be coupled to optical amplifier 32, so that optical amplifier 32 and optical amplifier 33 can share the residual pump light. The residual pump light in optical amplifier 32 can be reused by optical amplifier 33. The pump light input to optical amplifier 32 is absorbed and utilized twice in optical amplifier 32 and optical amplifier 33, which can reduce pump light residue. The pump light input to optical amplifier 33 can also be absorbed and utilized twice, thus improving the pump conversion efficiency. Under the premise of improving the pump conversion efficiency, the power requirements of optical amplifier 32 and optical amplifier 33 for pump light can be reduced, thereby reducing the cost of the optical amplifier system.

[0061] Referring to Figure 5, which shows a schematic diagram of an optical amplifier system provided in an embodiment of this application, the optical amplifier system includes a first optical amplifier and a second optical amplifier. The following description uses optical amplifier 32 as the first optical amplifier and optical amplifier 33 as the second optical amplifier as an example to illustrate the solution provided in this embodiment.

[0062] The first optical amplifier 32 includes a first pump-introducing device 322 and a first gain fiber 323. The first pump-introducing device 322 is used to introduce pump light and signal light into the first gain fiber 323 to amplify the signal light. For example, the first pump-introducing device 322 includes a common terminal C, a first terminal P1, and a second terminal P2. The first terminal P1 is used to receive pump light. The common terminal C of the first pump-introducing device 322 is coupled to the first terminal G1 of the first gain fiber 323. The second terminal G2 of the first gain fiber 323 is used to output the amplified signal light.

[0063] The second optical amplifier 33 includes a second pump-introducing device 332 and a second gain fiber 333. The second pump-introducing device 332 is used to introduce pump light and signal light into the second gain fiber 333 to amplify the signal light. The structure and principle of the second optical amplifier 33 are very similar to those of the first optical amplifier 32, and will not be described in detail here.

[0064] The bidirectional pump bypass includes a first pump input / output device 41, a second pump input / output device 42, and an optical waveguide (e.g., optical fiber). Both the first pump input / output device 41 and the second pump input / output device 42 include a common terminal C, a first terminal P1, and a second terminal P2. Taking the first pump input / output device 41 as an example, signal light can be transmitted between the common terminal C and the second terminal P2, for example, input from the common terminal C and output from the second terminal P2, or input from the second terminal P2 and output from the common terminal C; pump light can be transmitted between the common terminal C and the first terminal P1, for example, input from the common terminal C and output from the first terminal P1, or input from the first terminal P1 and output from the common terminal C.

[0065] The common end C of the first pump input / output device 41 is coupled to the gain fiber (i.e., the first gain fiber 323) of the first optical amplifier 32, and the common end C of the second pump input / output device 42 is coupled to the gain fiber (i.e., the second gain fiber 333) of the second optical amplifier 33. The first end P1 of the first pump input / output device 41 is coupled to the first end P1 of the second pump input / output device 42 through an optical waveguide (e.g., an optical fiber).

[0066] Due to limited pump conversion efficiency, some residual pump light will remain in the first gain fiber 323 and the second gain fiber 333. The first pump input / output device 41 is used to export the residual pump light in the first gain fiber 323 through its first end P1. The second pump input / output device 42 is used to export the residual pump light in the second gain fiber 333 through its first end P1.

[0067] The first end P1 of the first pump input / output device 41 and the first end P1 of the second pump input / output device 42 are coupled via optical fiber. Thus, the first pump input / output device 41 can output the residual pump light in the first gain fiber 323 to the second pump input / output device 42. The residual pump light in the first gain fiber 323 is then input into the second gain fiber 333 via the common end C of the second pump input / output device 42. In this way, the residual pump light in the first optical amplifier 32 can be reused in the second optical amplifier 33, improving the pump light conversion efficiency. Similarly, the second pump input / output device 42 can also output the residual pump light in the second gain fiber 333 to the first pump input / output device 41. The residual pump light in the second gain fiber 333 is then input into the first gain fiber 323 via the common end C of the first pump input / output device 41, improving the pump light conversion efficiency of the second optical amplifier 33. While improving the pump light conversion efficiency, the pump light power of the first optical amplifier 32 and the second optical amplifier 33 can be appropriately reduced, thereby reducing power consumption and cost.

[0068] For the multi-stage optical amplifier in the optical amplifier system provided in the embodiments of this application, it can be pumped in reverse or in the same direction, and the embodiments of this application do not limit it in this way.

[0069] If the transmission direction of the pump light in the first optical amplifier 32 is opposite to the transmission direction of the signal light, the second terminal P2 of the first pump input / output device 41 is used to receive the signal light to be amplified by the first optical amplifier 32; if the transmission direction of the pump light in the first optical amplifier 32 is the same as the transmission direction of the signal light, the second terminal P2 of the first pump input / output device 41 is used to output the signal light amplified by the first optical amplifier 32; if the transmission direction of the pump light in the second optical amplifier 33 is opposite to the transmission direction of the signal light, the second terminal P2 of the second pump input / output device 42 is used to receive the signal light to be amplified by the second optical amplifier 33; if the transmission direction of the pump light in the second optical amplifier 33 is the same as the transmission direction of the signal light, the second terminal P2 of the second pump input / output device 42 is used to output the signal light amplified by the first optical amplifier 32.

[0070] For example, taking the direction of signal light transmission from the first optical amplifier 32 to the second optical amplifier 33 as an example, the first end G1 of the first gain fiber 323 is the signal light input end and the second end G2 is the signal light output end; the first end G1 of the second gain fiber 333 is the signal light input end and the second end G2 is the signal light output end.

[0071] As shown in Figure 5, in the first optical amplifier 32, the first pump input device 322 is coupled to the first end G1 of the first gain fiber 323, and the common end C of the first pump input output device 41 is coupled to the second end G2 of the first gain fiber 323. The transmission direction of the pump light in the first optical amplifier 32 is the same as the transmission direction of the signal light. The first optical amplifier 32 is a co-pumped optical amplifier. The signal light amplified by the first optical amplifier 32 is output through the second end P2 of the first pump input output device 41. Similarly, the second pump input device 332 is coupled to the first end G1 of the second gain fiber 333, and the common end C of the second pump input output device 42 is coupled to the second end G2 of the second gain fiber 333. The transmission direction of the pump light in the second optical amplifier 33 is the same as the transmission direction of the signal light. The second optical amplifier 33 is a co-pumped optical amplifier. The signal light amplified by the second optical amplifier 33 is output through the second end P2 of the second pump input output device 42.

[0072] The first pump-in device 322 couples the pump light to the first gain fiber 323, and the first pump-out device 41 expels residual pump light from the first gain fiber 323. Therefore, the first pump-in device 322 and the second pump-out device 41 are located on different sides of the first gain fiber 323. For example, the first pump-in device 322 is coupled to the first end G1 of the first gain fiber 323, and the first pump-out device 41 is coupled to the second end G2 of the first gain fiber 323. Similarly, the second pump-in device 332 and the second pump-out device 42 are also located on different sides of the second gain fiber 333.

[0073] Referring to Figure 6, which illustrates another optical amplifier system provided in this embodiment, taking the direction of signal light transmission from the first optical amplifier 32 to the second optical amplifier 33 as an example, the first pump input device 322 is coupled to the first end G1 of the first gain fiber 323, and the first pump input output device 41 is coupled to the second end G2 of the first gain fiber 323. The transmission direction of the pump light in the first optical amplifier 32 is consistent with the transmission direction of the signal light, making the first optical amplifier 32 a co-pumped optical amplifier. The second pump input device 332 is coupled to the second end G2 of the second gain fiber 333, and the second pump input output device 42 is coupled to the first end G1 of the second gain fiber 333. The transmission direction of the pump light in the second optical amplifier 33 is opposite to the transmission direction of the signal light, making the second optical amplifier 33 a reverse-pumped optical amplifier.

[0074] In the optical amplifier system shown in Figure 6, the transmission direction of the pump light in the first optical amplifier 32 is the same as the transmission direction of the signal light. The signal light amplified by the first optical amplifier 32 is output through the second terminal P2 of the first pump input / output device 41. The transmission direction of the signal light in the second optical amplifier 33 is opposite to the transmission direction of the pump light. The second terminal P2 of the second pump input / output device 42 is used to receive the signal light to be amplified and couples the signal light to the second gain fiber 333 for amplification through the common terminal C.

[0075] Referring to Figure 7, which illustrates another optical amplifier system provided in an embodiment of this application, taking the direction of signal light transmission from the first optical amplifier 32 to the second optical amplifier 33 as an example, the first pump input device 322 is coupled to the second end G2 of the first gain fiber 323, and the first pump input output device 41 is coupled to the first end G1 of the first gain fiber 323. The transmission direction of the pump light in the first optical amplifier 32 is opposite to the transmission direction of the signal light, making the first optical amplifier 32 a reverse-pumped optical amplifier. The second pump input device 332 is coupled to the second end G2 of the second gain fiber 333, and the second pump input output device 42 is coupled to the first end G1 of the second gain fiber 333. The transmission direction of the pump light in the second optical amplifier 33 is opposite to the transmission direction of the signal light, making the second optical amplifier 33 a reverse-pumped optical amplifier.

[0076] In the optical amplifier system shown in Figure 7, the transmission direction of the pump light in the first optical amplifier 32 is opposite to the transmission direction of the signal light. The second end P2 of the first pump input / output device 41 is used to receive the signal light to be amplified. The signal light is coupled to the first gain fiber 323 for amplification through the common end C. The signal light amplified by the first gain fiber 323 is output through the second end P2 of the first pump input device 322. In the second optical amplifier 33, the transmission direction of the signal light is opposite to the transmission direction of the pump light. The second end P2 of the second pump input / output device 42 is used to receive the signal light to be amplified. The signal light is coupled to the second gain fiber 333 for amplification through the common end C. The signal light amplified by the second gain fiber 333 is output through the second end P2 of the second pump input device 332.

[0077] Referring to Figure 8, which illustrates another optical amplifier system provided in an embodiment of this application, taking the direction of signal light transmission from the first optical amplifier 32 to the second optical amplifier 33 as an example, the first pump input device 322 is coupled to the second end G2 of the first gain fiber 323, and the first pump input output device 41 is coupled to the first end G1 of the first gain fiber 323. The transmission direction of the pump light in the first optical amplifier 32 is opposite to the transmission direction of the signal light, making the first optical amplifier 32 a reverse-pumped optical amplifier. The second pump input device 332 is coupled to the first end G1 of the second gain fiber 333, and the second pump input output device 42 is coupled to the second end G2 of the second gain fiber 333. The transmission direction of the pump light in the second optical amplifier 33 is consistent with the transmission direction of the signal light, making the second optical amplifier 33 a co-pumped optical amplifier.

[0078] In the optical amplifier system shown in Figure 8, the transmission direction of the pump light in the first optical amplifier 32 is opposite to the transmission direction of the signal light. The second end P2 of the first pump input / output device 41 is used to receive the signal light to be amplified. The signal light is coupled to the first gain fiber 323 for amplification through the common end C. The signal light amplified by the first gain fiber 323 is output through the second end P2 of the first pump input device 322. The transmission direction of the pump light in the second optical amplifier 33 is the same as the transmission direction of the signal light. The signal light amplified by the second optical amplifier 33 is output through the second end P2 of the second pump input / output device 42.

[0079] Setting up a bidirectional pump bypass can improve pump conversion efficiency. The signal light is amplified sequentially through multiple stages of optical amplifiers. The power of the signal light is relatively low when passing through the earlier stages, especially the first stage. The more stages of optical amplifiers the signal light passes through, the greater its power, reaching its maximum at the last stage. When the signal light power is low, its absorption of pump light is weak, resulting in more residual pump light in the earlier stages. Conversely, when the signal light power is high, its absorption of pump light is strong, leading to less residual pump light or potential under-pumping in later stages. Therefore, the bidirectional pump bypass can be flexibly adjusted to maximize the utilization of residual pump light and improve pump conversion efficiency. For example, a bidirectional pump bypass can be set between the first m-stage optical amplifier and the last k-stage optical amplifier to provide more residual pump light from the first m-stage optical amplifier to the last k-stage optical amplifier, thereby improving the pump conversion efficiency. A bidirectional pump bypass can also be set between the n-stage optical amplifiers in the middle section to further improve the pump conversion efficiency.

[0080] The above describes the pump bidirectional bypass configuration provided in the embodiments of this application, which can improve pump conversion efficiency and reduce the requirements for the pump light source. The optical amplifier system provided in the embodiments of this application includes multiple optical amplifiers, and at least one of the optical amplifiers is a two-way optical amplifier, which can further improve pump conversion efficiency, reduce the cost of the pump light source, and thus reduce the cost of the optical amplifier system.

[0081] Unlike single-pass optical amplifiers, two-way optical amplifiers, as illustrated in Figures 3 and 9, contain an isolator to prevent the transmission of light in the opposite direction to the signal light, allowing the signal light to pass through the gain fiber only once. Figure 9 shows a schematic diagram of a two-way optical amplifier, including a pump source 21, a pump input device 22, a gain fiber 23, and a reflector 25. In a two-way optical amplifier, there is no isolator; instead, the reflector 25 is connected to the second end G2 of the gain fiber 23. After the signal light is amplified by the gain fiber 23, it reaches the reflector 25 and is reflected back into the gain fiber 23. Thus, the signal light passes through the gain fiber 23 twice, absorbing pump light energy and amplifying it both times. This improves pump conversion efficiency, increases pump light absorption, and reduces residual pump light.

[0082] The two-way optical amplifier requires additional devices such as a circulator 26 to separate the input and output signals. For example, the circulator 26 includes a first port, a second port and a third port. The input signal light enters the circulator 26 through the first port and is coupled to the two-way optical amplifier through the second port of the circulator 26. The signal amplified by the two-way optical amplifier enters the circulator through the second port of the circulator 26 and is then output through the third port of the circulator 26.

[0083] This application embodiment also provides another optical amplifier system, which includes optical amplifiers connected in sequence. The multi-stage optical amplifier includes at least one two-way optical amplifier. The multi-stage optical amplifier includes a first optical amplifier and a second optical amplifier. A pump bidirectional bypass is provided between the first optical amplifier and the second optical amplifier. For example, referring to FIG10, as an example, the optical amplifier system includes a first optical amplifier and a second optical amplifier. A pump bidirectional bypass is provided between the first optical amplifier and the second optical amplifier, wherein the second optical amplifier can be a two-way optical amplifier.

[0084] In the optical amplifier system provided in this application embodiment, for the first optical amplifier and the second optical amplifier connected by a pump bidirectional bypass, there may be the following situations: the first optical amplifier is a two-way optical amplifier and the second optical amplifier is a one-way optical amplifier; or the first optical amplifier is a one-way optical amplifier and the second optical amplifier is a two-way optical amplifier; or both the first optical amplifier and the second optical amplifier can be two-way optical amplifiers.

[0085] Based on this, the optical amplifier system provided in this application embodiment can have various different structures. For example, referring to Figure 11, as an example, the optical amplifier system includes an m-stage single-pass optical amplifier, an n-stage double-pass optical amplifier, and a k-stage single-pass optical amplifier connected in sequence to the output terminal, where m, n, and k are integers greater than or equal to 1. As mentioned in the foregoing example, the multi-stage optical amplifier includes a first optical amplifier and a second optical amplifier, with a pump bidirectional bypass provided between the first and second optical amplifiers to share residual pump light.

[0086] In this embodiment, a pump bidirectional bypass can be set between the intermediate n-stage double-pass optical amplifier and the first m-stage single-pass optical amplifier, or a pump bidirectional bypass can be set between the intermediate n-stage double-pass optical amplifier and the last k-stage single-pass optical amplifier, or a pump bidirectional bypass can be set between the intermediate n-stage double-pass optical amplifier and the first m-stage single-pass optical amplifier, and a pump bidirectional bypass can be set between the intermediate n-stage double-pass optical amplifier and the last k-stage single-pass optical amplifier.

[0087] For example, the first optical amplifier is included in the n-stage two-way optical amplifier, and the second optical amplifier is included in the m-stage one-way optical amplifier. For example, referring to Figure 11, in one possible implementation, the optical amplifier 32 in the n-stage two-way optical amplifier and the optical amplifier 31 in the m-stage one-way optical amplifier are connected by a pump bidirectional bypass.

[0088] Alternatively, the n-stage two-way optical amplifier includes a first optical amplifier, and the k-stage one-way optical amplifier includes a second optical amplifier. For example, referring to Figure 11, in one possible implementation, optical amplifier 33 in the n-stage two-way optical amplifier is connected to optical amplifier 34 in the k-stage one-way optical amplifier.

[0089] The gain fiber of a two-way optical amplifier is relatively short, resulting in more residual pump light. Therefore, a bidirectional pump bypass can be set between a portion of the two-way optical amplifiers and the preceding single-way optical amplifiers to ensure a low noise figure for the optical amplifier system. Another portion of the two-way optical amplifiers can be set with a bidirectional pump bypass between the following single-way optical amplifiers to ensure higher pump conversion efficiency.

[0090] In another implementation, referring to Figure 12, a pump bidirectional bypass can be set between the first m-stage single-pass optical amplifiers and the last k-stage single-pass optical amplifiers, and a pump bidirectional bypass can be set between the intermediate n-stage double-pass optical amplifiers. For example, the first m-stage single-pass optical amplifiers include the first optical amplifier described above, and the last k-stage single-pass optical amplifiers include the second optical amplifier described above. For example, referring to Figure 12, the optical amplifier 31 in the first m-stage single-pass optical amplifiers and the optical amplifier 31 in the last k-stage single-pass optical amplifiers are connected by a pump bidirectional bypass.

[0091] Alternatively, n is an integer greater than or equal to 2, and the intermediate n-stage double-pass optical amplifier includes a first optical amplifier and a second optical amplifier. For example, referring to Figure 12, the intermediate n-stage double-pass optical amplifier includes optical amplifier 32 and optical amplifier 33, and a pump bidirectional bypass is provided between optical amplifier 32 and optical amplifier 33.

[0092] In the optical amplifier system provided in this application embodiment, the signal light is amplified by multiple stages of optical amplifiers in sequence. The power of the signal light is relatively small when it passes through the first m-stage optical amplifier, especially when it passes through the first stage optical amplifier. The more stages of optical amplifiers the signal light passes through, the greater the power of the signal light, especially when it passes through the last stage optical amplifier, the power of the signal light reaches its maximum.

[0093] When the signal light power is low, the absorption capacity for pump light is weak, resulting in a large amount of residual pump light in the initial m-stage optical amplifiers. When the signal light power is high, the absorption capacity for pump light is strong, resulting in less residual pump light in the subsequent k-stage optical amplifiers, or potential pump insufficiency in the subsequent k-stage optical amplifiers. The optical amplifier system provided in this application embodiment sets a bidirectional pump bypass between the initial m-stage optical amplifiers and the subsequent k-stage optical amplifiers, providing the abundant residual pump light from the initial m-stage optical amplifiers to the subsequent k-stage optical amplifiers to improve pump conversion efficiency. A bidirectional pump bypass can also be set between the intermediate n-stage optical amplifiers to further improve pump conversion efficiency.

[0094] Figure 13 illustrates another optical amplifier system provided in an embodiment of this application, including m-stage single-pass optical amplifiers and n-stage double-pass optical amplifiers connected in sequence, where m and n are integers greater than or equal to 1. As can be seen from Figure 13, in the optical amplifier system provided in this embodiment, except for the first m-stage optical amplifiers which are single-pass optical amplifiers, all subsequent optical amplifiers are double-pass optical amplifiers. Double-pass optical amplifiers have higher pump conversion efficiency, and setting multiple stages of double-pass optical amplifiers can improve the pump conversion efficiency of the entire optical amplifier system. In some possible examples, n is greater than m.

[0095] In the optical amplifier system shown in Figure 13, a bidirectional pump bypass can also be set between different optical amplifiers to share residual pump light and improve pump conversion efficiency. For example, a bidirectional pump bypass can be set between the first m-stage optical amplifier and the last n-stage optical amplifier, or a bidirectional bypass can be set between the last n-stage optical amplifiers.

[0096] For example, the first m-stage single-pass optical amplifier includes optical amplifier 31, and the subsequent n-stage double-pass optical amplifier includes optical amplifier 32, with a pump bidirectional bypass between optical amplifier 31 and optical amplifier 32. Alternatively, if n is an integer greater than or equal to 2, the subsequent n-stage double-pass optical amplifier includes optical amplifier 33 and optical amplifier 34, with a pump bidirectional bypass between optical amplifier 33 and optical amplifier 34.

[0097] Alternatively, a pump bidirectional bypass can be set between the first m-stage optical amplifier and the last n-stage optical amplifier, and a pump bidirectional bypass can be set between the last n-stage optical amplifiers.

[0098] Figure 14 illustrates another optical amplifier system provided in this embodiment, including m-stage two-way optical amplifiers and n-stage one-way optical amplifiers connected in sequence, where m and n are integers greater than or equal to 1. Referring to Figure 14, the optical amplifier system provided in this embodiment includes a first m-stage two-way optical amplifier and a subsequent n-stage one-way optical amplifier. As mentioned in the previous examples, in a two-way optical amplifier, the signal light passes through the gain fiber twice, resulting in higher pump conversion efficiency. Moreover, in a multi-stage optical amplifier architecture, the fewer stages the signal light passes through, the lower its power; the more stages the signal light passes through, the higher its power. Therefore, setting the first m-stage optical amplifiers in the optical amplifier system as two-way optical amplifiers can improve pump conversion efficiency, reduce residual pump light in the first m-stage optical amplifiers, and improve the overall pump conversion efficiency of the optical amplifier system.

[0099] In the optical amplifier system provided in this application embodiment, a bidirectional pump bypass can also be set between the first m-stage optical amplifiers and the subsequent n-stage optical amplifiers to reuse the residual pump light in each stage of the optical amplifiers and improve the pump conversion efficiency. For example, the first m-stage double-pass optical amplifiers include optical amplifier 31, and the subsequent n-stage single-pass optical amplifiers include optical amplifier 33, with a bidirectional pump bypass set between optical amplifier 31 and optical amplifier 33.

[0100] Alternatively, m and n can be integers greater than or equal to 2, so a pump bidirectional bypass can be set between the first m stages of two-way optical amplifiers, and a pump bidirectional bypass can be set between the last n stages of one-way optical amplifiers.

[0101] Figure 15 illustrates another optical amplifier system provided in an embodiment of this application, including a multi-stage optical amplifier connected in sequence. Each stage of the multi-stage optical amplifier is a two-way optical amplifier. The multi-stage optical amplifier architecture composed of two-way optical amplifiers can have higher pump conversion efficiency.

[0102] In the optical amplifier system provided in this application embodiment, a bidirectional pump bypass can also be set between different stages of optical amplifiers to share residual pump light between different stages of optical amplifiers, thereby improving pump conversion efficiency.

[0103] Figure 16 illustrates another optical amplifier system provided in an embodiment of this application, including an m-stage double-pass optical amplifier, an n-stage single-pass optical amplifier, and a k-stage double-pass optical amplifier connected in sequence. The multi-stage optical amplifier includes a first optical amplifier and a second optical amplifier. The first optical amplifier and the second optical amplifier are connected by a pump bidirectional bypass, for example, optical amplifier 31 and optical amplifier 33 are connected by a pump bidirectional bypass.

[0104] The above examples only list some possible implementations. In the optical amplifier system provided in this application embodiment, a pump bidirectional bypass can be set between pairs of optical amplifiers as needed to improve pump conversion efficiency, reduce pump usage, and reduce costs.

[0105] As can be seen from the foregoing embodiments, the optical amplifier system provided in this application can improve pump conversion efficiency by setting at least one stage of two-way optical amplifier and setting a pump bidirectional bypass between different stages of optical amplifier. Given a fixed output power, improving pump conversion efficiency means that a lower power pump light source can be used.

[0106] For example, if the pump light emitted by the pump source in an optical amplifier has a power of A and the pump conversion efficiency is 10%, and the pump conversion efficiency of the optical amplifier is increased to 20%, which is twice the original conversion efficiency, then under the premise of meeting the same signal light output power, the power of the pump light can be reduced to A / 2, and the same signal gain can still be achieved. Since the pump source accounts for the largest proportion of the cost in the optical amplifier, if the number of pumps used in each optical amplifier is reduced, the cost can be reduced by reducing the power of the pump source; or, the power of the pump source can not be reduced, but the number of pump sources can be reduced. Multi-stage optical amplifiers can share the same pump source, which can also reduce the cost of the optical amplifier system.

[0107] Referring to Figures 3 and 17, in the optical amplifier system provided in this application embodiment, each optical amplifier includes a pump light source 21. For example, referring to Figure 17, the optical amplifier system includes a first optical amplifier 32 and a second optical amplifier 33. The first optical amplifier 32 includes a pump light source 321, and the second optical amplifier 33 includes a pump light source 331. The first optical amplifier 32 and the second optical amplifier 33 are connected by a pump bidirectional bypass. Since the pump conversion efficiency is improved by setting a pump bidirectional bypass and a two-way optical amplifier, the demand for pump light power is reduced. Therefore, the optical amplifier can use a pump light source with lower power, which can reduce the cost of the optical amplifier system.

[0108] Alternatively, in this embodiment, some optical amplifiers may not have separate pump sources, but multiple optical amplifiers may share the same pump source, thereby reducing the number of pump sources and lowering the cost of the optical amplifier system.

[0109] For example, referring to Figure 18, the optical amplifier system includes a first optical amplifier 32 and a second optical amplifier 33. Here, the first optical amplifier 32 and the second optical amplifier 33 do not have pump light sources. The optical amplifier system also includes a pump light source 51 and a beam splitter 52. The pump light source 51 is used to output pump light, and the beam splitter 52 is used to split the pump light into beams so that the pump light is output to at least two optical amplifiers in the multi-stage optical amplifier. For example, referring to Figure 18, the pump light after being split by the beam splitter 52 is output to the first optical amplifier 32 and the second optical amplifier 33, which reduces the number of pump light sources and reduces the cost of the optical amplifier system.

[0110] This application also provides an optical communication system, such as the optical communication system shown in Figure 1. The optical communication system includes a first communication device, a second communication device, and the optical amplification system provided in the foregoing embodiments. The first communication device is connected to the second communication device through the optical amplification system. The first communication device can be a transmitting device in the optical communication system, and the second communication device can be a receiving device in the optical communication system. Alternatively, the first communication device and the second communication device can be any two devices between the transmitting device and the receiving device in the optical communication system.

[0111] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An optical amplifier system, characterized in that, The optical amplifier system includes multiple stages of optical amplifiers connected in sequence; The multi-stage optical amplifier includes a first optical amplifier and a second optical amplifier. The optical amplifier system also includes a pump bidirectional bypass. The first optical amplifier and the second optical amplifier are connected through the pump bidirectional bypass. The pump bidirectional bypass is used to guide residual pump light from the first optical amplifier into the second optical amplifier and to guide residual pump light from the second optical amplifier into the first optical amplifier.

2. The optical amplifier system according to claim 1, characterized in that, Each of the multi-stage optical amplifiers includes a pump-introducing device and a gain fiber. The pump-introducing device is used to introduce pump light into the gain fiber so that the gain fiber amplifies the signal light input to the gain fiber. The pump bidirectional bypass includes a first pump input / output device, a second pump input / output device, and an optical waveguide; Both the first pump-in / out device and the second pump-in / out device include a common end and a first end; the common end of the first pump-in / out device is coupled to the gain fiber of the first optical amplifier, the common end of the second pump-in / out device is coupled to the gain fiber of the second optical amplifier, and the first end of the first pump-in / out device is coupled to the first end of the second pump-in / out device through the optical waveguide. The second pump input / output device is used to input the residual pump light exported by the first pump input / output device into the gain fiber of the second optical amplifier through a common terminal; The first pump import / export device is used to import the residual pump light exported by the second pump import / export device into the gain fiber of the first optical amplifier through a common terminal.

3. The optical amplifier system according to claim 2, characterized in that, The first pump input / output device further includes a second end. If the transmission direction of the pump light in the first optical amplifier is opposite to the transmission direction of the signal light, the second end of the first pump input / output device is used to receive the signal light to be amplified by the first optical amplifier; if the transmission direction of the pump light in the first optical amplifier is the same as the transmission direction of the signal light, the second end of the first pump input / output device is used to output the signal light amplified by the first optical amplifier. The second pump input / output device further includes a second end, wherein if the transmission direction of the pump light in the second optical amplifier is opposite to the transmission direction of the signal light, the second end of the second pump input / output device is used to receive the signal light to be amplified by the second optical amplifier; If the transmission direction of the pump light in the second optical amplifier is the same as the transmission direction of the signal light, the second end of the second pump input / output device is used to output the signal light amplified by the first optical amplifier.

4. The optical amplifier system according to any one of claims 1 to 3, characterized in that, At least one stage of the multi-stage optical amplifier is a two-way optical amplifier.

5. The optical amplifier system according to claim 4, characterized in that, The optical amplifier system includes an m-stage single-pass optical amplifier, an n-stage double-pass optical amplifier, and a k-stage single-pass optical amplifier connected in sequence, where m, n, and k are integers greater than or equal to 1.

6. The optical amplifier system according to claim 5, characterized in that, The n-stage double-pass optical amplifier includes the first optical amplifier, and the m-stage single-pass optical amplifier includes the second optical amplifier; or, the n-stage double-pass optical amplifier includes the first optical amplifier, and the k-stage single-pass optical amplifier includes the second optical amplifier.

7. The optical amplifier system according to claim 5, characterized in that, The m-level single-pass optical amplifier includes the first optical amplifier, and the k-level single-pass optical amplifier includes the second optical amplifier; Alternatively, n is an integer greater than or equal to 2, and the n-stage double-pass optical amplifier includes the first optical amplifier and the second optical amplifier.

8. The optical amplifier system according to claim 4, characterized in that, The optical amplifier system includes an m-stage single-pass optical amplifier and an n-stage double-pass optical amplifier connected in sequence, where m and n are integers greater than or equal to 1.

9. The optical amplifier system according to claim 8, characterized in that, The m-level single-pass optical amplifier includes the first optical amplifier, and the n-level double-pass optical amplifier includes the second optical amplifier.

10. The optical amplifier system according to claim 8, characterized in that, The n is an integer greater than or equal to 2, and the n-stage two-way optical amplifier includes the first optical amplifier and the second optical amplifier.

11. The optical amplifier system according to claim 4, characterized in that, The optical amplifier system includes an m-stage double-pass optical amplifier and an n-stage single-pass optical amplifier connected in sequence, where m and n are integers greater than or equal to 1.

12. The optical amplifier system according to claim 10, characterized in that, The m-stage double-pass optical amplifier includes the first optical amplifier, and the n-stage single-pass optical amplifier includes the second optical amplifier.

13. The optical amplifier system according to claim 4, characterized in that, All of the multi-stage optical amplifiers are two-way optical amplifiers.

14. The optical amplifier system according to claim 4, characterized in that, The optical amplifier system includes an m-stage double-pass optical amplifier, an n-stage single-pass optical amplifier, and a k-stage double-pass optical amplifier connected in sequence, where m, n, and k are integers greater than or equal to 1.

15. The optical amplifier system according to claim 2, characterized in that, The optical amplifier also includes a pump light source for outputting the pump light.

16. The optical amplifier system according to any one of claims 1 to 14, characterized in that, The optical amplifier system further includes a pump light source and a beam splitter. The pump light source is used to output pump light, and the beam splitter is used to split the pump light into beams so that the pump light is output to at least two optical amplifiers in the multi-stage optical amplifier.

17. An optical communication system, characterized in that, The optical communication system includes a first communication device, a second communication device, and an optical amplifier system as described in any one of claims 1 to 16; the first communication device is connected to the second communication device through the optical amplifier system.

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