Optical amplifier and communication system

Abstract

The present application belongs to the technical field of optical communications. Provided are an optical amplifier and a communication system. The optical amplifier comprises a multiplexer component, a first optical fiber array, a second optical fiber array and a first gain optical fiber, the multiplexer component being arranged on the optical path between the first optical fiber array and the second optical fiber array, and the two ends of the first gain optical fiber being respectively connected to the first optical fiber array and the second optical fiber array. The optical amplifier is used for amplifying N paths of optical signals, wherein the first optical fiber array is used for inputting optical signals, the second optical fiber array is used for outputting optical signals, and the first gain optical fiber is used for amplifying optical signals. When N paths of optical signals undergo multi-stage amplification in the optical amplifier, amplified optical signals are output from the second optical fiber array, and then are returned to the first gain optical fiber for re-amplification. Thus, a passive optical device in the optical amplifier can be multiplexed, such that there is no need to use a plurality of optical amplifiers during multi-stage amplification of one or more paths of optical signals.

Description

Optical amplifiers and communication systems

[0001] This application claims priority to Chinese patent application No. 202311808443.9, filed on December 25, 2023, with invention name “Optical Amplifier and Communication System,” the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of optical communication technology, and in particular to an optical amplifier and a communication system. Background Art

[0003] In the field of optical communications, during the transmission of optical signals, an optical amplifier is usually required to amplify the gain of the optical signal. For example, an optical amplifier is an erbium-doped fiber amplifier (EDFA). An optical amplifier includes a pump laser, a gain fiber, a wavelength division multiplexer, and an isolator. The pump laser is the component that provides energy in the optical amplifier, and the gain fiber is the medium for energy conversion, which can convert the power of the pump light output by the pump laser into the power of the optical signal to be amplified. The function of the isolator is to suppress the passage of reverse amplified spontaneous emission (ASE) light in the optical amplifier, making the light of the optical amplifier unidirectional, which can reduce the noise figure of the optical amplifier.

[0004] In order to increase the gain saturation optical power, two or more optical amplifiers are usually used for amplification, so multiple optical amplifiers are needed.

[0005] Summary of the Invention

[0006] The present application provides an optical amplifier and a communication system, which can save the number of amplifiers.

[0007] In a first aspect, the present application provides an optical amplifier for amplifying N optical signals, where N is greater than or equal to 1. The optical amplifier includes a combining component, a first optical fiber array, a second optical fiber array, and a first gain optical fiber. The combining component is located on the optical path between the first optical fiber array and the second optical fiber array, the first optical fiber array is connected to one end of the first gain optical fiber, and the second optical fiber array is connected to the other end of the first gain optical fiber. The first optical fiber array is used to receive the j-th optical signal of the i-th optical signal in the N optical signals, and input the j-th optical signal to the second optical fiber array. The j-th optical signal is an unamplified optical signal of the i-th optical signal or an amplified optical signal. j is greater than or equal to 1 and less than or equal to n. n is the first amplification level of the i-th optical signal, and i is less than or equal to N. The combining component is used to receive A j-th level pump light signal is received, and the j-th level pump light signal is input into the first gain fiber through the first fiber array and / or the second fiber array. The j-th level pump light signal is used to provide pump excitation for the j-th level light signal. The second fiber array is used to input the j-th level light signal into the first gain fiber, so that the first gain fiber inputs the j+1-th level light signal into the first fiber array. The j+1-th level light signal is an optical signal obtained by amplifying the j-th level light signal. The first fiber array is further used to input the j+1-th level light signal into the second fiber array. The second fiber array is further used to output the j+1-th level light signal.

[0008] In the solution described in this application, the optical amplifier is used to amplify N optical signals. The first optical fiber array is used to input optical signals, the second optical fiber array is used to output optical signals, and the first gain fiber is used to amplify the optical signals. When the N optical signals undergo multi-stage amplification in the optical amplifier, the amplified optical signals are output from the second optical fiber array and returned to the first gain fiber for further amplification. This allows for multiplexing of the passive optical components in the optical amplifier. This eliminates the need for multiple optical amplifiers when achieving multi-stage amplification of one or more optical signals. In particular, when amplifying multiple optical signals, the need for multiple optical amplifiers is eliminated, which not only reduces the size of the multi-stage amplifier but also reduces the cost of the optical amplifier.

[0009] In one optional embodiment, when j equals 1, the jth optical signal comes from an external input optical fiber connected to the first optical fiber array, and when j is greater than 1, the jth optical signal comes from the first gain optical fiber. The second optical fiber array is further configured to input the j+1th optical signal to the first gain optical fiber to perform a first amplification process when j is less than n, and output the j+1th optical signal when j equals n. In this way, the first gain optical fiber can be used to cyclically amplify the optical signal.

[0010] In an optional manner, the optical amplifier further includes a second gain fiber and a transmission fiber for the i-th optical signal, two ends of the second gain fiber are connected to the second optical fiber array, and two ends of the transmission fiber are connected to the first optical fiber array; the combining component is further used to receive the m-th level pump light signal and input the m-th level pump light signal to the second optical fiber array, the m-th level pump light signal is used to provide pump excitation for the m-th level optical signal, m is greater than or equal to 1 and less than or equal to d, d is the second amplification level of the i-th optical signal, and the m-th level optical signal comes from the first optical fiber array; the second optical fiber array is further used to input the m-th level pump light signal and the m-th level optical signal to the second gain fiber, receive the m+1-th level optical signal from the second gain fiber, and input the m+1-th level optical signal to the combining component, the m+1-th level optical signal being the optical signal after the m-th level optical signal is amplified; the combining component is further used to input the m+1-th level optical signal to the first optical fiber array; the first optical fiber array is further used to input the m+1-th level optical signal to the transmission optical fiber. The second optical fiber array is further configured to, when m is less than d, input the m+1th level optical signal to the first gain fiber or the second gain fiber to perform the first amplification process or the second amplification process, and when m is equal to d, output the m+1th level optical signal.

[0011] In the solution presented in this application, the optical amplifier also includes a second gain fiber, the two ends of which are connected to a second fiber array to implement reverse pumping to amplify the optical signal. Furthermore, when implementing multi-stage amplification through reverse pumping, the amplified optical signal is output from the second fiber array and returned to the second gain fiber for further amplification. This allows for multiplexing of the passive optical components in the optical amplifier. This eliminates the need for multiple optical amplifiers when implementing multi-stage secondary amplification of one or more optical signals. Furthermore, the simultaneous presence of forward and reverse pumping prevents the situation where a single pumping method fails to achieve the required power.

[0012] In one optional embodiment, when m equals 1 and j equals n, the mth-order optical signal is the j+1th-order optical signal. The second optical fiber array is further configured to, when m is less than d, input the m+1th-order optical signal into the second gain fiber to perform a second amplification process. In this way, the optical signal, having undergone the first amplification, undergoes a further second amplification process to further amplify the first-amplified optical signal through reverse pumping.

[0013] In an optional manner, the first optical fiber array includes first input ends and first output ends of each level for the i-th optical signal, the second optical fiber array includes second input ends, second output ends and d+1-th output end of each level for the i-th optical signal, the transmission optical fiber includes transmission sub-optical fibers of each level corresponding to the i-th optical signal, the second gain optical fiber includes second gain sub-optical fibers of each level corresponding to the i-th optical signal, and the combining component includes first combining modules of each level corresponding to the i-th optical signal; one end of the m-th transmission sub-optical fiber is connected to the m-th first input end, and the other end is connected to the m-th first output end; one end of the m-th second gain sub-optical fiber is connected to the m-th second input end, and the other end is connected to the m-th second output end; the m-th first combining module is located on the optical path between the m-th first output end and the m-th second input end; and the d+1-th output end is located on the output optical path of the d-th first input end.

[0014] In an optional manner, the m-th level first multiplexing module is used to receive the m-th level pump light signal and input the m-th level pump light signal to the m-th level second input end; the m-th level second input end is used to input the m-th level pump light signal to the m-th level second gain sub-fiber; the m-th level second output end is used to input the m-th level light signal to the m-th level second gain sub-fiber; the m-th level second input end is further used to receive the m+1-th level light signal from the m-th level second gain sub-fiber and input the m+1-th level light signal to the m-th level first multiplexing module; the m-th level first multiplexing module is further used to input the m-th level pump light signal to the m-th level first output end. The m+1th level optical signal; the m+1th level first output end is used to input the m+1th level optical signal to the m+1th level transmission sub-fiber; the m+1th level first input end is used to receive the m+1th level optical signal from the m+1th level transmission sub-fiber, and when m is less than d, input the m+1th level optical signal to the m+1th level second output end; when m is equal to d, input the m+1th level optical signal to the d+1th level output end; the m+1th level second output end is used to input the m+1th level optical signal to the m+1th level second gain sub-fiber to perform the second amplification processing; the d+1th level output end is used to output the m+1th level optical signal.

[0015] In the solution shown in the present application, after the optical signal is amplified by forward pumping, the optical signal is further amplified by reverse pumping, which can make up for the defect that the optical signal cannot be amplified to the required power during forward pumping amplification.

[0016] In an optional manner, when the first gain optical fiber is used for amplification, the first optical fiber array includes input ends at various levels for the i-th optical signal, the second optical fiber array includes output ends at various levels for the i-th optical signal, the first gain optical fiber includes first gain sub-optical fibers at various levels corresponding to the i-th optical signal, and the combining component includes second combining modules at various levels corresponding to the i-th optical signal; the j-th second combining module is located on the optical path between the j-th input end and the j-th output end, the j+1-th input end is connected to one end of the j-th first gain sub-optical fiber, and the j-th output end is connected to the j+1-th input end. The output end is connected to the other end of the j-th level first gain sub-fiber, and the n+1-th level output end is located on the output optical path of the n+1-th level input end; or, the 1-th level output end is located on the output optical path of the 1-th level input end, the j-th level second multiplexing module is located on the optical path between the j+1-th level input end and the j+1-th level output end, the j+1-th level input end is connected to one end of the j-th level first gain sub-fiber, the j-th level output end is connected to the other end of the j-th level first gain sub-fiber, and the n+1-th level output end is located on the output optical path of the n-th level second multiplexing module.

[0017] In an optional manner, the j-th input end is used to input the j-th optical signal to the j-th second combining module; the j-th second combining module is used to receive the j-th optical signal and the j-th pump optical signal, combine the j-th optical signal and the j-th pump optical signal into a combined signal, and input the combined signal to the j-th output end; the j-th output end is used to input the combined signal to the j-th first gain sub-fiber; the j+1-th input end is used to receive the j+1-th optical signal from the j-th first gain sub-fiber, and when j is less than n, input the j+1-th optical signal to the j+1-th second combining module to perform the first amplification process, and when j is equal to n, input the j+1-th optical signal to the n+1-th output end; and the n+1-th output end is used to output the j+1-th optical signal.

[0018] In the solution shown in the present application, during forward pumping, the optical signal to be amplified and the pump optical signal are combined into a combined signal after passing through the second multiplexing module. The combined signal is transmitted in the first gain optical fiber. After the optical signal to be amplified is amplified, it passes through the next-stage input end and enters the first gain optical fiber again to be amplified until a fully amplified optical signal is obtained.

[0019] In an optional embodiment, the first-stage input end is used to input the first-stage optical signal to the first-stage output end; the j-th-stage second multiplexing module is used to receive the j-th-stage pump optical signal and input the j-th-stage pump optical signal to the j+1-th-stage input end; the j+1-th-stage input end is used to input the j-th-stage pump optical signal to the j-th-stage first gain sub-fiber; the j-th-stage output end is used to input the j-th-stage optical signal to the j-th-stage first gain sub-fiber, where the j-th-stage optical signal comes from the j-th-stage input end; the j+1-th-stage input end is further used to receive the j+1-th-stage optical signal from the j-th-stage first gain sub-fiber and input the j+1-th-stage optical signal to the j-th-stage second multiplexing module; the j-th-stage second multiplexing module is further used to input the j+1-th-stage optical signal to the j+1-th-stage output end; the j+1-th-stage output end is used to, when j is less than n, input the j+1-th-stage optical signal to the j+1-th-stage first gain sub-fiber to perform the first amplification process, and when j is equal to n, output the j+1-th-stage optical signal.

[0020] In the solution shown in the present application, during reverse pumping, the optical signal to be amplified and the pump optical signal are transmitted in opposite directions in the first gain optical fiber. After the optical signal to be amplified is amplified, it passes through the next-stage input end and enters the first gain optical fiber again to be amplified until a fully amplified optical signal is obtained.

[0021] In an optional manner, the first amplification stages of the N optical signals are the same, and the amplification stages of the N optical signals are equal to K divided by N, where K is equal to the number of input terminals of the i-th optical signal minus N.

[0022] In an optional manner, the first optical fiber array is used to input the j-th order optical signal to the multiplexing component, and the multiplexing component is further used to input the j-th order optical signal to the second optical fiber array.

[0023] In one optional embodiment, the optical amplifier further includes a splitter assembly and a monitoring assembly. The splitter assembly is located in the optical path between the first optical fiber array and the combiner assembly, while the monitoring assembly and the combiner assembly are located on mutually perpendicular output optical paths of the splitter assembly. Thus, when monitoring the amplification function of the optical signal, the monitoring assembly and the combiner assembly are located on separate optical paths. Even if reverse ASE light returns, it will not reach the monitoring assembly, thereby maintaining monitoring accuracy and reducing the need for isolators.

[0024] In one optional embodiment, the optical amplifier further includes a first collimator assembly, a second collimator assembly, and a third collimator assembly. The first collimator assembly is located in the optical path between the first fiber array and the combiner assembly, the second collimator assembly is located in the optical path between the combiner assembly and the second fiber array, and the third collimator assembly is located in the incident optical path of the combiner assembly. Thus, by providing the collimator assemblies, the amplified optical signal can be transmitted over long distances.

[0025] In one optional embodiment, the optical amplifier further includes a flattening filter assembly located in the optical path between the first optical fiber array and the combiner assembly, or located in the optical fiber link between the first gain fiber and the first optical fiber array. Thus, by providing the flattening filter assembly, the optical signal can be flattened, resulting in a flattened amplified optical signal.

[0026] In one optional embodiment, in order to appropriately adjust the power when the optical signal is over-amplified, the optical amplifier further includes a variable optical attenuation component, one end of the variable optical attenuation component is connected to the first optical fiber array, and the other end of the variable optical attenuation component is connected to the second optical fiber array. The variable optical attenuation component is configured to receive the j+1th level optical signal from the second optical fiber array, attenuate the j+1th level optical signal to obtain an attenuated optical signal, and input the attenuated optical signal to the first optical fiber array, so that the first optical fiber array inputs the attenuated optical signal to the second optical fiber array.

[0027] In one optional embodiment, the optical amplifier further includes an isolator assembly located on a first optical path between the first and second optical fiber arrays. The first optical path is the path through which the first optical fiber array inputs the optical signal to be amplified. This prevents reverse ASE light from being transmitted in the opposite direction, reducing its impact on the input end.

[0028] In a second aspect, the present application provides a communication system comprising a first communication device, an optical amplifier as described in the first aspect or its optional manner, and a second communication device; the first communication device is used to send N optical signals to the optical amplifier; the optical amplifier is used to amplify the N optical signals to obtain an amplified optical signal, and send the amplified optical signal to the second communication device; the second communication device is used to receive the amplified optical signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG1 is a schematic diagram of a first structure of an optical amplifier provided by an exemplary embodiment of the present application;

[0030] FIG2 is a schematic diagram of a port of a first structure provided by an exemplary embodiment of the present application;

[0031] FIG3 is a schematic diagram of a second structure of an optical amplifier provided by an exemplary embodiment of the present application;

[0032] FIG4 is a schematic diagram of a port of a second structure provided by an exemplary embodiment of the present application;

[0033] FIG5 is a schematic diagram of a third structure of an optical amplifier provided by an exemplary embodiment of the present application;

[0034] FIG6 is a schematic diagram of a port of a third structure provided by an exemplary embodiment of the present application;

[0035] FIG7 is a schematic diagram of a fourth structure of an optical amplifier provided by an exemplary embodiment of the present application;

[0036] FIG8 is a schematic diagram of a port of a fourth structure provided by an exemplary embodiment of the present application;

[0037] FIG9 is a schematic diagram of a fifth structure of an optical amplifier provided by an exemplary embodiment of the present application;

[0038] FIG10 is a schematic diagram of a port of a fifth structure provided by an exemplary embodiment of the present application;

[0039] FIG11 is a schematic diagram of a port of a sixth structure provided by an exemplary embodiment of the present application;

[0040] FIG12 is a schematic diagram of a port of a seventh structure provided by an exemplary embodiment of the present application;

[0041] FIG13 is a schematic diagram of a port of an eighth structure provided by an exemplary embodiment of the present application;

[0042] FIG14 is a schematic structural diagram of a light splitting component provided by an exemplary embodiment of the present application;

[0043] FIG15 is a schematic structural diagram of an optical amplifier provided by an exemplary embodiment of the present application;

[0044] FIG16 is a schematic structural diagram of an optical amplifier provided by another exemplary embodiment of the present application;

[0045] FIG17 is a schematic structural diagram of an optical amplifier provided by yet another exemplary embodiment of the present application;

[0046] FIG18 is a schematic structural diagram of an optical amplifier provided by yet another exemplary embodiment of the present application;

[0047] FIG19 is a schematic structural diagram of an optical amplifier provided by yet another exemplary embodiment of the present application;

[0048] FIG20 is an equivalent schematic diagram of a multi-channel optical signal amplification of an optical amplifier provided by an exemplary embodiment of the present application;

[0049] FIG21 is a schematic structural diagram of a two-stage amplification optical amplifier provided by an exemplary embodiment of the present application;

[0050] FIG22 is a schematic structural diagram of a three-stage amplification optical amplifier provided by an exemplary embodiment of the present application. DETAILED DESCRIPTION

[0051] In order to make the objectives, technical solutions and advantages of this application clearer, the implementation methods of this application will be further described in detail below with reference to the accompanying drawings.

[0052] In an embodiment of the present application, an optical amplifier is provided. The amplifier is connected to a reconfigurable optical add-drop multiplexer (ROADM). After the ROADM outputs one or more optical signals, the optical amplifier is used to amplify the one or more optical signals. The amplifier can also be used in a metropolitan area ring network to amplify optical signals transmitted in multiple directions within the metropolitan area ring network. These are two possible scenarios; the optical amplifier provided in the embodiments of the present application can be used in any scenario requiring optical signal amplification.

[0053] In the embodiments of the present application, optical amplifiers are divided into three types: forward-pumped optical amplifiers, reverse-pumped optical amplifiers, and bidirectionally pumped optical amplifiers. Forward pumping refers to the transmission direction of the pumping light signal and the optical signal to be amplified in the gain fiber being the same, also known as forward pumping. Reverse pumping refers to the transmission direction of the pumping light signal and the optical signal to be amplified in the gain fiber being opposite, also known as backward pumping. Bidirectional pumping refers to the presence of pumping light signals in the gain fiber that have both opposite and identical transmission directions as the optical signal to be amplified. For example, in an optical amplifier, the pumping light signal in one portion of the gain fiber has the same transmission direction as the optical signal to be amplified, while the pumping light signal in another portion of the gain fiber has opposite transmission directions to the optical signal to be amplified.

[0054] The gain fiber is any kind of doped fiber, for example, the gain fiber is erbium-doped fiber or ytterbium-doped fiber.

[0055] In the embodiments of the present application, optical fiber connection can be understood as optical fiber fusion splicing. An optical fiber array can also be understood as an array formed by a bunch of optical fibers arranged together, which can be one-dimensional or multi-dimensional.

[0056] In an embodiment of the present application, an optical amplifier is configured to amplify N optical signals, where N is greater than or equal to 1. The N optical signals are optical signals to be amplified, and each of the N optical signals can be a single-wavelength optical signal or a multi-wavelength optical signal. N is the maximum number of optical signals that the optical amplifier can amplify. When N is greater than 1, while the optical amplifier can amplify N optical signals, in actual use, the optical amplifier can also input and amplify T optical signals, where T is less than or equal to N.

[0057] a. Forward-pumped optical amplifier.

[0058] Figure 1 provides a schematic diagram of a first structural embodiment of an optical amplifier. Referring to Figure 1 , the optical amplifier includes a first fiber array, a second fiber array, a combiner assembly, and a first gain fiber. The combiner assembly is located in the optical path between the first and second fiber arrays. The first fiber array is connected to one end of the first gain fiber, and the second fiber array is connected to the other end of the first gain fiber. The first fiber array serves as the input fiber array of the optical amplifier, and the second fiber array serves as the output fiber array of the optical amplifier.

[0059] The following description is made by taking the i-th optical signal among N optical signals as an example, where i is greater than or equal to 1 and less than or equal to N.

[0060] The first fiber array is connected to an external input fiber. The first fiber array receives the first-order optical signal of the i-th optical signal from the external input fiber. The first-order optical signal is the unamplified i-th optical signal and is input to the second fiber array. The combiner receives the first-order pump optical signal, which provides pump excitation for the first-order optical signal. The combiner combines the first-order pump optical signal with the first-order optical signal to generate a first-order combined signal, which is then input to the second fiber array. The second fiber array inputs the first-order combined signal to the first gain fiber. The first-order combined signal is transmitted through the first gain fiber, where it is amplified to generate an optical signal after the first-order optical signal is amplified, i.e., the second-order optical signal. The first gain fiber inputs the second-order optical signal to the first fiber array.

[0061] If the first amplification stage is 1, that is, the optical amplifier performs one stage of amplification on the i-th optical signal, the second-stage optical signal is the optical signal after the i-th optical signal has been amplified. The first optical fiber array inputs the second-stage optical signal to the second optical fiber array, and the second optical fiber array outputs the second-stage optical signal. For example, the second optical fiber array is connected to an external output optical fiber and inputs the second-stage optical signal to the external output optical fiber.

[0062] If the first amplification stage number is greater than 1, that is, the optical amplifier performs multi-stage amplification on the i-th optical signal, and the second-stage optical signal is the optical signal to be amplified, the first fiber array inputs the second-stage optical signal to the combiner assembly. The combiner assembly receives the second-stage pump optical signal and the second-stage optical signal. The second-stage pump optical signal is used to provide pump excitation for the second-stage optical signal. The second-stage pump optical signal and the second-stage optical signal are combined to generate a second-stage combined signal, which is then input to the second fiber array. The second fiber array inputs the second-stage combined signal to the first gain fiber. The second-stage combined signal is transmitted through the first gain fiber, where it is amplified until the n+1-th stage optical signal is input to the first fiber array. The first fiber array then inputs the n+1-th stage optical signal to the second fiber array, which then outputs the n+1-th stage optical signal, where n is the first amplification stage number. For example, the second fiber array is connected to an external output fiber and inputs the n+1-th stage optical signal to the external output fiber.

[0063] It should be noted that Figure 1 shows two-stage amplification of the i-th optical signal. In the above description, when the first optical fiber array inputs the n+1-th optical signal to the second optical fiber array, it can pass through the multiplexing component or not, and this embodiment of the application is not limited thereto.

[0064] In one optional embodiment, Figure 2 provides a port diagram of a first structure. Referring to Figure 2 , the first fiber array includes input ports at various stages corresponding to the i-th optical signal, the second fiber array includes output ports at various stages corresponding to the i-th optical signal, the first gain fiber includes first gain sub-fibers at various stages corresponding to the i-th optical signal, and the multiplexing assembly includes second multiplexing modules at various stages corresponding to the i-th optical signal.

[0065] The first-stage input is connected to an external input fiber, and the n+1-stage output is connected to an external output fiber. The j-stage second multiplexing module is located on the optical path between the j-stage input and the j-stage output. The j+1-stage input is connected to one end of the j-stage first gain sub-fiber, and the j-stage output is connected to the other end of the j-stage first gain sub-fiber. The n+1-stage output is located on the output optical path of the n+1-stage input.

[0066] The first-stage input end receives the first-stage optical signal of the i-th optical signal from the external input fiber and inputs the first-stage optical signal to the first-stage second multiplexing module. The first-stage second multiplexing module receives the first-stage pump optical signal and combines the first-stage optical signal with the first-stage pump optical signal to obtain a first-stage combined signal. The first-stage second multiplexing module inputs the first-stage combined signal to the first-stage output end. The first-stage output end inputs the first-stage combined signal to the first-stage first gain sub-fiber. The first-stage combined signal is transmitted in the first-stage first gain sub-fiber, where it is amplified to obtain an optical signal after the first-stage optical signal is amplified, i.e., the second-stage optical signal. The first-stage first gain sub-fiber inputs the second-stage optical signal to the second-stage input end.

[0067] If the first amplification stage is equal to 1, that is, the optical amplifier performs one-stage amplification on the i-th optical signal, the second-stage optical signal is the optical signal after the i-th optical signal is amplified, the second-stage input end inputs the second-stage optical signal to the second-stage output end, and the second-stage output end inputs the second-stage optical signal to the external output optical fiber.

[0068] If the first amplification stage number is greater than 1, that is, the optical amplifier performs multi-stage amplification on the i-th optical signal, the second-stage optical signal is the optical signal to be amplified. The second-stage input terminal inputs the second-stage optical signal to the second-stage second multiplexing module. The second-stage second multiplexing module receives the second-stage pump optical signal and the second-stage optical signal, combines the second-stage pump optical signal with the second-stage optical signal to generate a second-stage combined signal, and inputs the second-stage combined signal to the second-stage output terminal. The second-stage output terminal inputs the second-stage combined signal to the second-stage first gain sub-fiber. The second-stage combined signal is transmitted in the second-stage first gain sub-fiber, where it is amplified until it inputs the n+1th-stage optical signal to the n+1th-stage input terminal. The n+1th-stage input terminal inputs the n+1th-stage optical signal to the n+1th-stage output terminal, and the n+1th-stage output terminal inputs the n+1th-stage optical signal to the external output fiber.

[0069] Optionally, the multiplexing assembly further includes an n+1-stage second multiplexing module, which is located in the optical path between the n+1-stage input and the n+1-stage output. Thus, the n+1-stage input receives the n+1-stage optical signal and inputs the n+1-stage optical signal to the n+1-stage second multiplexing module. The n+1-stage second multiplexing module inputs the n+1-stage optical signal to the n+1-stage output, and the n+1-stage output inputs the n+1-stage optical signal to an external output optical fiber. Thus, when designing an optical amplifier, a second multiplexing module can be provided between the input and output of each stage, eliminating the need to consider the final optical path separately.

[0070] Optionally, the n+1-th stage second multiplexing module receives the n+1-th stage pump light signal, the n+1-th stage second multiplexing module inputs the n+1-th stage pump light signal to the n+1-th stage input end, and the n+1-th stage input end inputs the n+1-th stage pump light signal to the n-th stage first gain sub-fiber. In this way, it is equivalent to that in the n-th stage first gain sub-fiber, the pump light signal and the n-th stage light signal are transmitted in the same direction, and the pump light signal and the n-th light signal are transmitted in opposite directions, indicating that bidirectional pumping is used when amplifying the n-th stage light signal.

[0071] Figure 3 provides a schematic diagram of a second optical amplifier structure. Referring to Figure 3, the optical amplifier includes a first fiber array, a second fiber array, a combiner assembly, a second gain fiber, and a transmission fiber. The combiner assembly is located in the optical path between the first and second fiber arrays. The second fiber array is connected to both ends of the second gain fiber, and the first fiber array is connected to both ends of the transmission fiber. The transmission fiber is an ordinary optical fiber and does not amplify optical signals. Of course, the transmission fiber can also be a gain fiber. Since the gain fiber does not contain a pump light signal, it is only used to transmit optical signals. The transmission fiber discussed below is similar and will not be described in detail.

[0072] The following description is made by taking the i-th optical signal among N optical signals as an example.

[0073] The first fiber array is connected to an external input fiber. The first fiber array receives the first-order optical signal of the i-th optical signal from the external input fiber and inputs the first-order optical signal to a combiner assembly. The combiner assembly receives the first-order pump optical signal, combines the first-order pump optical signal with the first-order optical signal to generate a first-order combined signal, and inputs the first-order combined signal to a second fiber array. The second fiber array inputs the first-order combined signal to a second gain fiber. The first-order combined signal is transmitted through the second gain fiber, where it is amplified to generate an optical signal after amplification of the first-order optical signal, i.e., a second-order optical signal. The second gain fiber inputs the second-order optical signal to the second fiber array, and the second fiber array inputs the second-order optical signal to the first fiber array. The first fiber array inputs the second-order optical signal to the connected transmission fiber, and the transmission fiber inputs the second-order optical signal to the first fiber array.

[0074] If the first amplification level is equal to 1, that is, the optical amplifier performs one-stage amplification on the i-th optical signal, the second-stage optical signal is the optical signal after the i-th optical signal is amplified, the first optical fiber array inputs the second-stage optical signal to the second optical fiber array, and the second optical fiber array inputs the second-stage optical signal to the external output optical fiber.

[0075] If the first amplification stage number is greater than 1, that is, the optical amplifier performs multi-stage amplification on the i-th optical signal, the second-stage optical signal is the optical signal to be amplified. The first optical fiber array inputs the second-stage optical signal to the combiner assembly. The combiner assembly receives the second-stage pump optical signal and the second-stage optical signal, combines them to generate a second-stage combined signal, and inputs the second-stage combined signal to the second optical fiber array. The second optical fiber array inputs the second-stage combined signal to the second gain fiber. The second-stage combined signal is transmitted through the second gain fiber, where it is amplified until the second optical fiber array inputs the n+1-th optical signal to the first optical fiber array. The first optical fiber array inputs the n+1-th optical signal to the transmission fiber, and the transmission fiber inputs the n+1-th optical signal to the first optical fiber array. The first optical fiber array inputs the n+1-th optical signal to the second optical fiber array, and the second optical fiber array inputs the n+1-th optical signal to the external output fiber.

[0076] Figure 4 provides a port diagram of the second structure. Referring to Figure 4 , the first fiber array includes first inputs and outputs at each level for the i-th optical signal, as well as an input at the (n+1)th level. The second fiber array includes second inputs and outputs at each level for the i-th optical signal, as well as an output at the (n+1)th level. The second gain fiber includes second gain sub-fibers at each level corresponding to the i-th optical signal. The multiplexing assembly includes second multiplexing modules at each level corresponding to the i-th optical signal. The transmission fiber includes transmission sub-fibers at each level.

[0077] The first input of the first stage is connected to an external input fiber, and the output of the (n+1) stage is connected to an external output fiber. The second multiplexing module of the jth stage is located in the optical path between the first input of the jth stage and the second output of the jth stage. The second input of the jth stage is connected to one end of the second gain sub-fiber of the jth stage, the second output of the jth stage is connected to the other end of the second gain sub-fiber of the jth stage, the first output of the jth stage is connected to one end of the transmission sub-fiber of the jth stage, and the input of the j+1th stage is connected to the other end of the transmission sub-fiber of the jth stage. The output of the n+1th stage is located in the output optical path of the n+1th stage input.

[0078] The first input end of the first stage receives the first optical signal of the i-th optical signal from the external input optical fiber. The first input end of the first stage inputs the first optical signal to the second multiplexing module of the first stage. The second multiplexing module of the first stage receives the first pump optical signal and combines the first optical signal with the first pump optical signal to obtain a first combined signal. The second multiplexing module of the first stage inputs the first combined signal to the second output end of the first stage. The second output end of the first stage inputs the first combined signal to the second gain sub-fiber of the first stage. The first combined signal is transmitted in the second gain sub-fiber of the first stage, where the first optical signal is amplified to obtain an optical signal after the amplification of the first optical signal, i.e., the second optical signal. The second gain sub-fiber of the first stage inputs the second optical signal to the second input end of the first stage. The second input end of the first stage inputs the second optical signal to the first output end of the first stage. The first output end of the first stage inputs the second stage optical signal to the first stage transmission sub-fiber, and the first stage transmission sub-fiber inputs the second stage optical signal to the first input end of the second stage.

[0079] If the first amplification stage is equal to 1, that is, the optical amplifier performs one-stage amplification on the i-th optical signal, the second-stage optical signal is the optical signal after the i-th optical signal is amplified, the second-stage first input end inputs the second-stage optical signal to the second-stage second output end (that is, the second-stage output end), and the second-stage second output end inputs the second-stage optical signal to the external output optical fiber.

[0080] If the first amplification stage number is greater than 1, that is, the optical amplifier performs multi-stage amplification on the i-th optical signal, the second-stage optical signal is the optical signal to be amplified. The second-stage first input terminal inputs the second-stage optical signal to the second-stage second multiplexing module. The second-stage second multiplexing module receives the second-stage pump optical signal and the second-stage optical signal, combines the second-stage pump optical signal with the second-stage optical signal to obtain a second-stage combined signal, and inputs the second-stage combined signal to the second-stage second output terminal. The second-stage second output terminal inputs the second-stage combined signal to the second-stage second gain sub-fiber. The second-stage combined signal is transmitted in the second-stage second gain sub-fiber, where it is amplified until the n-stage second input terminal inputs the n+1-th-stage optical signal to the n-stage first output terminal, the n-stage first output terminal inputs the n+1-th-stage optical signal to the n-stage transmission sub-fiber, and the n-stage transmission sub-fiber inputs the n+1-th-stage optical signal to the n+1-th-stage input terminal. The n+1th level input end inputs the n+1th level optical signal to the n+1th level output end, and the n+1th level output end inputs the n+1th level optical signal to the external output optical fiber.

[0081] Optionally, a second multiplexing module is further included in the optical path between the j-th stage second input end and the j-th stage first output end. The second multiplexing module is configured to input a pump light signal to the j-th stage second input end, and the j-th stage second input end inputs the pump light signal to the j-th stage second gain sub-fiber, thereby achieving bidirectional pumping in the j-th stage gain sub-fiber. Here, the value of j can be all or part of 1 to n.

[0082] It should be noted that in a forward-pumped optical amplifier, the power of each pump optical signal is set according to actual needs. In addition, if N is greater than 1, the wavelengths of different optical signals in the N optical signals may be different, and pump optical signals of different wavelengths may be used.

[0083] b. Reverse pumped optical amplifier.

[0084] Figure 5 provides a third schematic diagram of the structure of an optical amplifier. Referring to Figure 5, the optical amplifier includes a first fiber array, a second fiber array, a combiner assembly, and a first gain fiber. The combiner assembly is located in the optical path between the first and second fiber arrays. The first fiber array is connected to one end of the first gain fiber, and the second fiber array is connected to the other end of the first gain fiber. The first fiber array serves as the input fiber array of the optical amplifier, and the second fiber array serves as the output fiber array of the optical amplifier.

[0085] The following description is made by taking the i-th optical signal among N optical signals as an example.

[0086] The first fiber array is connected to an external input fiber. The first fiber array receives the first-order optical signal of the i-th optical signal from the external input fiber and inputs the first-order optical signal to the second fiber array. The combiner receives the first-order pump optical signal, which provides pump excitation for the first-order optical signal, and inputs the first-order pump optical signal to the first fiber array. The second fiber array inputs the first-order optical signal to the first gain fiber. The first-order optical signal and the first-order pump optical signal propagate in opposite directions in the first gain fiber. The first-order optical signal is amplified during transmission, resulting in an optical signal that is an amplified version of the first-order optical signal, i.e., the second-order optical signal. The first gain fiber inputs the second-order optical signal to the first fiber array.

[0087] If the first amplification stage is 1, meaning the optical amplifier performs one stage of amplification on the i-th optical signal, the second stage optical signal is the amplified i-th optical signal. The first optical fiber array inputs the second stage optical signal to the multiplexing assembly. The multiplexing assembly inputs the second stage optical signal to the second optical fiber array, which then outputs the second stage optical signal. For example, the second optical fiber array is connected to an external output optical fiber, inputting the second stage optical signal to the external output optical fiber.

[0088] If the first amplification stage number is greater than 1, that is, the optical amplifier performs multi-stage amplification on the i-th optical signal, the second-stage optical signal is the optical signal to be amplified. The first fiber array inputs the second-stage optical signal to the multiplexing assembly. The multiplexing assembly inputs the second-stage optical signal to the second fiber array. The multiplexing assembly receives the second-stage pump light signal and inputs the second-stage pump light signal to the first fiber array. The first fiber array inputs the second-stage pump light signal to the first gain fiber. The second-stage pump light signal and the second-stage optical signal propagate in opposite directions in the first gain fiber, where the second-stage optical signal is amplified until the n+1-stage optical signal is input to the first fiber array. The first fiber array then inputs the n+1-stage optical signal to the multiplexing assembly, which then inputs the n+1-stage optical signal to the second fiber array. The second fiber array then outputs the n+1-stage optical signal, where n is the first amplification stage number. For example, the second fiber array is connected to an external output fiber and inputs the n+1-stage optical signal to the external output fiber.

[0089] It should be noted that Figure 5 shows two-stage amplification of the i-th optical signal. In the above description, when the first optical fiber array inputs the first-stage optical signal to the second optical fiber array, it can pass through the multiplexing component or not, and this embodiment of the application is not limited thereto.

[0090] In an optional embodiment, Figure 6 provides a schematic diagram of the ports in the third structure. Referring to Figure 6 , the first fiber array includes input ports at various stages corresponding to the i-th optical signal, the second fiber array includes output ports at various stages corresponding to the i-th optical signal, the first gain fiber includes first gain sub-fibers at various stages corresponding to the i-th optical signal, and the multiplexing assembly includes second multiplexing modules at various stages corresponding to the i-th optical signal.

[0091] The first-stage input end is connected to an external input optical fiber, and the n+1-stage output end is connected to an external output optical fiber. The j-stage second multiplexing module is located on the optical path between the j+1-stage input end and the j+1-stage output end. The j+1-stage input end is connected to one end of the j-stage first gain sub-fiber, and the j-stage output end is connected to the other end of the j-stage first gain sub-fiber. The n+1-stage output end is located on the output optical path of the n-stage second multiplexing module.

[0092] The first-stage input receives the first-stage optical signal of the i-th optical signal from the external input fiber and inputs the first-stage optical signal to the first-stage output. The first-stage second multiplexing module receives the first-stage pump optical signal and inputs the first-stage pump optical signal to the second-stage input. The first-stage output inputs the first-stage optical signal to the first-stage first gain sub-fiber. The first-stage pump optical signal and the first-stage optical signal are amplified in the first-stage first gain sub-fiber, resulting in an optical signal after the first-stage optical signal is amplified, i.e., the second-stage optical signal. The first-stage first gain sub-fiber inputs the second-stage optical signal to the second-stage input.

[0093] If the first amplification stage is 1, that is, the optical amplifier performs one stage of amplification on the i-th optical signal, the second-stage optical signal is the optical signal after the amplification of the i-th optical signal. The second-stage input end inputs the second-stage optical signal to the first-stage second multiplexing module. The first-stage second multiplexing module inputs the second-stage optical signal to the second-stage output end, and the second-stage output end inputs the second-stage optical signal to the external output fiber.

[0094] If the first amplification stage number is greater than 1, that is, the optical amplifier performs multi-stage amplification on the i-th optical signal, the second-stage optical signal is the optical signal to be amplified. The second-stage input terminal inputs the second-stage optical signal to the first-stage second multiplexing module. The first-stage second multiplexing module inputs the second-stage optical signal to the second-stage output terminal. The second-stage second multiplexing module receives the second-stage pump optical signal and inputs the second-stage pump optical signal to the third-stage input terminal. The third-stage input terminal inputs the second-stage pump optical signal to the second-stage first gain sub-fiber. The second-stage pump optical signal and the second-stage optical signal are transmitted in the first-stage first gain sub-fiber. The second-stage optical signal is amplified during transmission until the n+1-stage input terminal inputs the n+1-stage optical signal. The n+1-stage input terminal inputs the n+1-stage optical signal to the n-stage multiplexing module. The n-stage multiplexing module inputs the n+1-stage optical signal to the n+1-stage output terminal. The n+1-stage output terminal inputs the n+1-stage optical signal to the external output fiber.

[0095] Optionally, the multiplexing component further includes a 0th-stage second multiplexing module, which is located in the optical path between the 1st-stage input end and the 1st-stage output end. Thus, the 1st-stage input end receives the 1st-stage optical signal of the i-th optical signal and inputs the 1st-stage optical signal to the 0th-stage second multiplexing module, which then inputs the 1st-stage optical signal to the 1st-stage output end.

[0096] Optionally, the 0th-stage second combining module receives the 0th-stage pump light signal, combines the 0th-stage pump light signal and the 1st-stage optical signal into a combined signal, and the 0th-stage second combining module inputs the combined signal to the 1st-stage output end. In this way, it is equivalent to that in the 1st-stage first gain sub-fiber, the pump light signal and the 1st-stage optical signal are transmitted in the same direction, and the pump light signal and the 1st-stage optical signal are transmitted in opposite directions, indicating that bidirectional pumping is used when amplifying the 1st-stage optical signal.

[0097] Figure 7 provides a schematic diagram of a fourth optical amplifier structure. Referring to Figure 7, the optical amplifier includes a first fiber array, a second fiber array, a combiner assembly, a second gain fiber, and a transmission fiber. The combiner assembly is located in the optical path between the first and second fiber arrays. The second fiber array is connected to both ends of the second gain fiber, and the first fiber array is connected to both ends of the transmission fiber. The transmission fiber is a standard optical fiber and does not amplify optical signals.

[0098] The following description is made by taking the i-th optical signal among N optical signals as an example.

[0099] The first fiber array is connected to an external input fiber. The first fiber array receives the first-order optical signal of the i-th optical signal from the external input fiber and inputs the first-order optical signal to the second fiber array. The combiner assembly receives the first-order pump optical signal and inputs the first-order pump optical signal to the second fiber array. The second fiber array inputs the first-order optical signal and the first-order pump optical signal to the second gain fiber. The first-order pump optical signal and the first-order pump optical signal are transmitted in opposite directions in the second gain fiber. The first-order optical signal is amplified during transmission, resulting in an optical signal amplified from the first-order optical signal, i.e., the second-order optical signal. The second gain fiber inputs the second-order optical signal to the second fiber array, which in turn inputs the second-order optical signal to the combiner assembly. The combiner assembly inputs the second-order optical signal to the first fiber array. The first fiber array inputs the second-order optical signal to the connected transmission fiber, which in turn inputs the second-order optical signal to the first fiber array.

[0100] If the first amplification level is equal to 1, that is, the optical amplifier performs one-stage amplification on the i-th optical signal, the second-stage optical signal is the optical signal after the i-th optical signal is amplified, the first optical fiber array inputs the second-stage optical signal to the second optical fiber array, and the second optical fiber array inputs the second-stage optical signal to the external output optical fiber.

[0101] If the first amplification stage number is greater than 1, that is, the optical amplifier performs multi-stage amplification on the i-th optical signal, the second-stage optical signal is the optical signal to be amplified, and the first fiber array inputs the second-stage optical signal to the second fiber array. The multiplexing assembly receives the second-stage pump optical signal and inputs the second-stage pump optical signal to the second fiber array. The second fiber array inputs the second-stage pump optical signal and the second-stage optical signal to the second gain fiber. The second-stage pump optical signal and the second-stage optical signal propagate in opposite directions in the second gain fiber, where the second-stage optical signal is amplified during transmission until the second fiber array inputs the n+1-th optical signal to the first fiber array, the first fiber array inputs the n+1-th optical signal to the transmission fiber, and the transmission fiber inputs the n+1-th optical signal to the first fiber array. The first fiber array inputs the n+1-th optical signal to the second fiber array, and the second fiber array inputs the n+1-th optical signal to the external output fiber.

[0102] Figure 8 provides a port diagram of a fourth structure. Referring to Figure 8 , the first fiber array includes first inputs and outputs at each stage, and an input at the (n+1)th stage, for the i-th optical signal. The second fiber array includes second inputs, outputs, and an output at each stage, for the i-th optical signal. The second gain fiber includes second gain sub-fibers at each stage corresponding to the i-th optical signal. The multiplexing assembly includes second multiplexing modules at each stage corresponding to the i-th optical signal. The transmission fiber includes transmission sub-fibers at each stage.

[0103] The first input end of the first stage is connected to an external input fiber, and the output end of the (n+1) stage is connected to an external output fiber. The second multiplexing module of the jth stage is located in the optical path between the second input end of the jth stage and the first output end of the jth stage. The second input end of the jth stage is connected to one end of the second gain sub-fiber of the jth stage, the second output end of the jth stage is connected to the other end of the second gain sub-fiber of the jth stage, the first output end of the jth stage is connected to one end of the transmission sub-fiber of the jth stage, and the first input end of the j+1th stage is connected to the other end of the transmission sub-fiber of the jth stage. The output end of the n+1th stage is located in the output optical path of the n+1th stage input end.

[0104] The amplification process of the optical signal here is similar to that described in FIG4 , except that the position of the j-th stage combining module is different, and the pump optical signal and the optical signal to be amplified are not combined into a combined signal, which will not be described again here.

[0105] Optionally, a second multiplexing module is further included in the optical path between the j-th stage first input end and the j-th stage second output end. The second multiplexing module is configured to input a pump light signal to the j-th stage second output end, and the j-th stage second output end inputs the pump light signal to the j-th stage second gain sub-fiber, thereby achieving bidirectional pumping in the j-th stage gain sub-fiber. Here, the value of j can be all or part of 1 to n.

[0106] It should be noted that in a reverse-pumped optical amplifier, the power of each pump optical signal is set according to actual needs. In addition, if N is greater than 1, the wavelengths of different optical signals in the N optical signals may be different, and pump optical signals of different wavelengths may be used.

[0107] c. Bidirectionally pumped optical amplifier.

[0108] Figure 9 provides a fifth schematic diagram of the optical amplifier structure. Referring to Figure 9, the optical amplifier includes a first fiber array, a second fiber array, a combiner assembly, a first gain fiber, a second gain fiber, and a transmission fiber. The combiner assembly is located in the optical path between the first and second fiber arrays. The first fiber array is connected to one end of the first gain fiber, the second fiber array is connected to the other end of the first gain fiber, both ends of the second gain fiber are connected to the second fiber array, and both ends of the transmission fiber are connected to the first fiber array.

[0109] The first gain fiber is forward pumped. When the optical signal is amplified in the first gain fiber, the transmission path of the optical signal is the first fiber array, the combiner assembly, the second fiber array, the first gain fiber, and the first fiber array, until it is output from the optical amplifier. The transmission path of the pump light signal is the combiner assembly, the second fiber array, and the first gain fiber.

[0110] The second gain fiber is reversely pumped. When the optical signal is amplified in the second gain fiber, the optical signal's transmission path is through the first fiber array, the second fiber array, the second gain fiber, the second fiber array, the combiner, and the first fiber array, until it is output from the optical amplifier. The pump light signal's transmission path is through the combiner, the second fiber array, and the second gain fiber.

[0111] It should be noted that for each optical signal, the locations of forward pumping and reverse pumping can be set according to actual needs. For example, forward pumping amplification can be performed first in the first gain fiber to obtain an amplified optical signal, and then reverse pumping amplification can be performed in the second gain fiber. In another example, reverse pumping amplification can be performed first in the second gain fiber to obtain an amplified optical signal, and then forward pumping amplification can be performed in the first gain fiber. In another example, forward pumping amplification and reverse pumping amplification can be performed alternately.

[0112] The forward pumping process is described in the previous Figures 1 and 2. The reverse pumping of the m-th level optical signal of the i-th optical signal is used as an example for explanation. m is greater than or equal to 1 and less than or equal to d, where d is the second amplification level of the i-th optical signal, and the second amplification level is the amplification level of the reverse pumping.

[0113] The first fiber array inputs the mth-order optical signal to the second fiber array. The combiner assembly receives the mth-order pump optical signal and inputs the mth-order pump optical signal to the second fiber array. The second fiber array inputs the mth-order pump optical signal and the mth-order optical signal to the second gain fiber. The mth-order pump optical signal and the mth-order optical signal are transmitted in opposite directions in the second gain fiber. The mth-order optical signal is amplified during transmission, resulting in an amplified optical signal of the mth-order optical signal, i.e., the m+1th-order optical signal. The second gain fiber inputs the m+1th-order optical signal to the second fiber array. The second fiber array inputs the m+1th-order optical signal to the combiner assembly, which in turn inputs the m+1th-order optical signal to the first fiber array. The first fiber array inputs the m+1th-order optical signal to the transmission fiber. The transmission fiber inputs the m+1th-order optical signal to the first fiber array. The first fiber array inputs the m+1th-order optical signal to the second fiber array. When m is less than d, the m+1th optical signal continues to be amplified and is input to the second gain fiber. Simultaneously, the multiplexing component also inputs the m+1th pump optical signal to the second fiber array, and the second fiber array also inputs the m+1th pump optical signal to the second gain fiber, performing reverse pump amplification, i.e., secondary amplification. When m is equal to d, the m+1th optical signal has been amplified and the second fiber array outputs the m+1th optical signal, for example, to an external output fiber, or to the first gain fiber, or to the variable optical attenuation component described below.

[0114] When m is less than d, if forward and reverse pump amplification are performed alternately, the first fiber array inputs the m+1th optical signal to the combiner assembly. The combiner assembly receives the m+1th pump optical signal, combines the m+1th optical signal with the m+1th pump optical signal, and generates a combined signal, which is then input to the second fiber array. The second fiber array inputs the combined signal to the first gain fiber for forward pump amplification, i.e., the first amplification. After receiving the forward pump optical signal, the first fiber array then inputs the forward pump optical signal to the second fiber array for reverse pump amplification, i.e., the second amplification.

[0115] It should be noted that when m is 1, the mth-order optical signal can be any optical signal output during forward pumping, or can be unamplified optical signal input from an external input fiber. For example, the first-order optical signal is the first-order optical signal input from an external input fiber. For another example, the first-order optical signal is the optical signal after the i-th optical signal has undergone at least one round of forward pumping amplification.

[0116] In an optional manner, reverse pump amplification is performed after the forward pump amplification is completed. The reverse pump amplification can supplement the amplification of the optical signal after the forward pump amplification, and the m-th level optical signal is the n+1-th level optical signal. In this case, Figure 10 provides a port schematic diagram of the fifth structure. Referring to Figure 10, the first optical fiber array includes the first input end and the first output end of each level of the i-th optical signal, the second optical fiber array includes the second input end, the second output end and the d+1-th level output end of each level of the i-th optical signal, the transmission optical fiber includes the transmission sub-fibers at each level corresponding to the i-th optical signal, the second gain optical fiber includes the second gain sub-fibers at each level corresponding to the i-th optical signal, and the combining component includes the first combining modules at each level corresponding to the i-th optical signal. One end of the m-th level transmission sub-fiber is connected to the m-th level first input end, and the other end is connected to the m-th level first output end. One end of the m-th level second gain sub-fiber is connected to the m-th level second input end, and the other end is connected to the m-th level second output end. The m-th level first multiplexing module is located on the optical path between the m-th level first output end and the m-th level second input end, and the d+1-th level output end is located on the output optical path of the d-th level first input end.

[0117] The forward pumping process is described above. After the forward pumping is completed, the n+1th optical signal is output. The second output end of the first stage in the second fiber array inputs the first-stage optical signal (i.e., the n+1th optical signal) into the first-stage second gain sub-fiber. The second input end of the first stage inputs the first-stage optical signal into the first-stage second gain sub-fiber. The first-stage first multiplexing module receives the first-stage pump optical signal and inputs the first-stage pump optical signal into the first-stage second input end. The first-stage second input end inputs the first-stage pump optical signal into the first-stage second gain sub-fiber. The first-stage pump optical signal and the first-stage optical signal are transmitted in opposite directions in the first-stage second gain sub-fiber. During transmission, the first-stage optical signal is amplified to obtain an optical signal after the amplification of the first-stage optical signal, i.e., the second-stage optical signal. The first-stage second gain sub-fiber inputs the second-stage optical signal into the first-stage second input end. The second input end of the first stage inputs the second-stage optical signal to the first multiplexed mode of the first stage, and the first multiplexed mode of the first stage inputs the second-stage optical signal to the first output end of the first stage. The first output end of the first stage inputs the second-stage optical signal to the first-stage transmission sub-fiber. The first-stage transmission sub-fiber inputs the second-stage optical signal to the first input end of the first stage. The first input end of the first stage inputs the second-stage optical signal to the second output end of the second stage.

[0118] Assuming d is greater than 1, this indicates that the second-stage optical signal continues to be amplified. The second-stage second output end inputs the second-stage optical signal to the second-stage second gain sub-fiber. Simultaneously, the second-stage second multiplexing module also inputs the second-stage pump optical signal to the second-stage second input end. The second-stage second input end also inputs the second-stage pump optical signal to the second-stage second gain sub-fiber. This continues with two-stage amplification until the d-th-stage second input end inputs the d+1-th-stage optical signal to the d-th-stage first output end. The d-th-stage first output end inputs the d+1-th-stage optical signal to the d-th-stage transmission sub-fiber. The d-th-stage transmission sub-fiber inputs the d+1-th-stage optical signal to the d-th-stage first input end. The d-th-stage first input end inputs the d+1-th-stage optical signal to the d+1-th-stage output end. The d+1-th-stage output end inputs the d+1-th-stage optical signal to the external output fiber.

[0119] It should be noted that Figures 9 and 10 illustrate three-stage amplification as an example. In actual use, the number of amplification stages can be arbitrarily set, and the order of forward and reverse pumping amplification can be adjusted arbitrarily. For example, the first optical signal can be reverse pumped first and then reverse pumped, while the second optical signal can be forward pumped first and then reverse pumped.

[0120] In addition, when N is greater than 1, part of the optical signal may be subjected to forward pump amplification, part of the optical signal may be subjected to reverse pump amplification, and part of the optical signal may be subjected to both forward pump amplification and reverse pump amplification.

[0121] Figure 11 provides a sixth structural schematic diagram of an optical amplifier. Referring to Figure 11 , bidirectional pumping is implemented in the first gain fiber. The combining assembly includes a first subassembly and a second subassembly. The first subassembly includes various levels of reverse combining modules corresponding to the i-th optical signal. The second subassembly includes various levels of forward combining modules corresponding to the i-th optical signal. The third fiber array includes a first fiber subarray and a second fiber subarray. The third fiber array is used to input pump light signals into the combining assembly. The first fiber array is located on the output optical path of the first subassembly, and the second fiber array is located on the output optical path of the second subassembly.

[0122] The first subassembly is used to provide a reverse pumping optical signal during each amplification stage, and the second subassembly is used to provide a forward pumping optical signal during each amplification stage. Both the reverse pumping optical signal and the forward pumping optical signal are transmitted through the first gain fiber to achieve bidirectional pumping. The amplification process of the i-th optical signal is described above and will not be repeated here.

[0123] It should be noted that, based on the ideas of the embodiments of the present application, optical amplifiers of various structures can be combined. For example, Figure 12 provides a seventh structural schematic diagram of an optical amplifier. Referring to Figure 12, the optical amplifier includes a first optical fiber array, a second optical fiber array, a combining component, a second gain optical fiber, and a transmission optical fiber. The combining component is located on the optical path between the first optical fiber array and the second optical fiber array, the two ends of the second gain optical fiber are connected to the second optical fiber array, and the two ends of the transmission optical fiber are connected to the first optical fiber array. In Figure 12, the second gain optical fiber includes multiple stages of second gain sub-fibers, some of the second gain sub-fibers are used for reverse pumping, and other parts of the second gain sub-fibers are used for forward pumping.

[0124] For another example, Figure 13 provides an eighth structural schematic diagram of an optical amplifier. Referring to Figure 13, the optical amplifier includes a first fiber array, a second fiber array, a combining component, a first gain fiber, a second gain fiber, and a transmission fiber. The combining component is located on the optical path between the first fiber array and the second fiber array. One end of the first gain fiber is connected to the first fiber array, and the other end of the first gain fiber is connected to the second fiber array. Both ends of the second gain fiber are connected to the second fiber array, and both ends of the transmission fiber are connected to the first fiber array. In Figure 13, the first gain fiber is used for forward pumping. The second gain fiber includes multiple stages of second gain sub-fibers, some of which are used for reverse pumping amplification, and other parts of which are used for forward pumping amplification.

[0125] In an optional manner, for each optical amplifier described above, the optical amplifier further includes a third optical fiber array, which is used to input pump optical signals of various levels of the i-th optical signal into the multiplexing component. The number of input ends of the third optical fiber array is greater than , p i Indicates the amplification level of the i-th optical signal.

[0126] In one optional embodiment, for each optical amplifier described above, the optical amplifier further includes a pump source, which is used to output a pump light signal. For N optical signals, the pump sources for different optical signals may be different. For example, the optical amplifier includes N pump sources, which are used to provide pump light signals for the N optical signals. If the i-th optical signal undergoes multi-stage amplification, then multiple pump light signals are required. A splitter is provided after the pump source of the i-th optical signal. The splitter splits the pump light signal output by the pump source into multiple pump light signals, and the power of the multiple pump light signals is set according to the actual power required. For another example, the optical amplifier includes P pump sources, and P is less than N, indicating that different optical signals use the same pump source.

[0127] In an optional manner, for the optical amplifiers shown in Figures 1 and 3 above, the first amplification stages of the N optical signals can be the same, and the first amplification stages of the N optical signals are equal to K divided by N, where K is equal to the number of input ends of the i-th optical signal minus N.

[0128] Alternatively, for each optical amplifier described above, at least two of the N optical signals have different first amplification stages. For example, if N is 3, the first amplification stage of the first optical signal is 2, and the first amplification stage of the second and third optical signals is 3.

[0129] In an optional embodiment, for the optical amplifier shown in Figure 9 above, when N is greater than 1, the first amplification level of the N optical signals is the same, the second amplification level is the same, or the amplification level of at least two of the N optical signals is different, and the amplification level is equal to the sum of the first amplification level and the second amplification level.

[0130] In an optional manner, in order to facilitate monitoring of the amplification of the optical signal, the optical amplifier further includes a splitter component and a monitoring component, and the splitter component is located on the optical path between the first optical fiber array and the combining component. Referring to FIG14 , the monitoring component and the combining component are located on mutually perpendicular outgoing optical paths of the splitter component, the monitoring component is located on the reflected optical path of the splitter component, and the combining component is located on the transmitted optical path of the splitter component. In this way, the monitoring component and the combining component are not on the same optical path, so that the reverse ASE optical signal will not enter the monitoring component, thereby enabling the use of a single-stage isolator, thereby reducing insertion loss and improving the performance of the optical amplifier. In FIG14 , the dotted line represents the optical path of the reverse ASE optical signal. In addition to the different reflections on the splitter component, it actually overlaps with the transmission optical path of the forward optical signal. FIG14 is used to illustrate the separation of the two.

[0131] For example, the optical splitter component receives each optical signal from the first optical fiber array and splits each optical signal into a first sub-optical signal and a second sub-optical signal. The power of the first sub-optical signal is significantly lower than the power of the second sub-optical signal. For example, the power ratio of the first sub-optical signal to the second sub-optical signal is 3:97. The transmission directions of the first sub-optical signal and the second sub-optical signal are perpendicular. The optical splitter component inputs the first sub-optical signal to the monitoring component and the second sub-optical signal to the combining component. The combining component inputs the second sub-optical signal to the second optical fiber array.

[0132] The optical splitting component includes multiple optical splitting modules corresponding to N optical signals, and the monitoring component includes multiple monitoring modules corresponding to N optical signals. The multiple optical splitting modules correspond to the multiple monitoring modules in a one-to-one manner.

[0133] For each of the N optical signals, multiple optical splitting modules are located between the first optical fiber array and the second optical fiber array, on the transmission optical path of each optical signal, and before the isolator assembly. For example, in the optical amplifier shown in Figure 1, multiple optical splitting modules are located on the optical path between the f-th stage input end and the f-th stage second multiplexing module, where f is greater than or equal to 1 and less than or equal to n+1.

[0134] Optionally, the monitoring component includes a detector array, which can reduce monitoring costs and improve integration.

[0135] Optionally, the monitoring component is connected to an external device, and the monitoring component sends monitored data to the external device, and the external device determines the amplification status of the optical signal based on the data.

[0136] Optionally, a light splitting component is provided on each optical path between the first optical fiber array and the second optical fiber array, so as to monitor the power of the optical signal transmitted on each optical path.

[0137] In one optional embodiment, for each of the aforementioned optical amplifiers, to enable long-distance transmission of optical signals with reduced divergence, the optical amplifier further includes a first collimation component, a second collimation component, and a third collimation component. The first collimation component is located in the optical path between the first optical fiber array and the combiner assembly, the second collimation component is located in the optical path between the combiner assembly and the second optical fiber array, and the third collimation component is located in the optical path between the third optical fiber array and the combiner assembly. The first collimation component, the second collimation component, and the third collimation component are all used to collimate the input optical signal to reduce divergence during long-distance transmission of the optical signal.

[0138] Optionally, the first collimating assembly and the first optical fiber array are separate components, or the first collimating assembly and the first optical fiber array are integrated together to form a fiber array unit (FAU).

[0139] Optionally, the second collimating assembly and the second optical fiber array are separate components, and the second collimating assembly and the second optical fiber array are integrated together to form a FAU.

[0140] Optionally, the third collimating assembly and the third optical fiber array are separate components, and the third collimating assembly and the third optical fiber array are integrated together to form a FAU.

[0141] In one optional embodiment, for each of the aforementioned optical amplifiers, to achieve gain flattening of the amplified optical signal, the optical amplifier further includes a flattening filter assembly for performing flattening filtering on the amplified optical signal. Referring to FIG15 , the flattening filter assembly is located in the optical path between the first optical fiber array and the combiner assembly, or in the optical fiber link between the first gain fiber and the first optical fiber array (see FIG16 ).

[0142] Optionally, assuming the number of amplification stages for the i-th optical signal is n+d (when no second gain fiber is present, d is 0), the flattening filter assembly performs flattening filtering on the k-th optical signal of the i-th optical signal, where k is greater than 1 and less than or equal to n+d. For example, if n+d is 4, the flattening filter assembly performs flattening filtering on the third and fourth optical signals. The specific level of optical signal to be flattened can be set according to actual needs.

[0143] In one optional embodiment, for each of the aforementioned optical amplifiers, in order to reduce the gain of the amplified optical signal when the gain of the optical signal is significantly amplified, the optical amplifier further includes a variable optical attenuation component, one end of which is connected to the first optical fiber array and the other end to the second optical fiber array. For example, the variable optical attenuation component is connected to a first transmission optical fiber and a second transmission optical fiber at its ends, respectively, with the first transmission optical fiber connected to the first optical fiber array and the second transmission optical fiber connected to the second optical fiber array. Figure 17 provides a schematic diagram of an optical amplifier including a variable attenuation component.

[0144] The variable optical attenuation assembly is located on the optical fiber link from which the second optical fiber array outputs the j+1th level optical signal. The second optical fiber array inputs the j+1th level optical signal to the variable optical attenuation assembly, which then attenuates the j+1th level optical signal to produce an attenuated optical signal. The variable optical attenuation assembly inputs the attenuated optical signal to the first optical fiber array. The first optical fiber array then inputs the attenuated optical signal to the second optical fiber array for output or further amplification.

[0145] Optionally, the variable optical attenuation component includes N variable optical attenuation modules, and the N optical signals correspond one-to-one to the N variable optical attenuation modules. The N variable optical attenuation modules attenuate the j+1th optical signal of the N optical signals. For example, if the N optical signals have the same number of amplification stages, namely n, the N variable optical attenuation modules attenuate the n+1th optical signal of the N optical signals. Alternatively, the variable optical attenuation module corresponding to the i-th optical signal attenuates the i-th optical signal after the p-th stage of amplification, and the variable optical attenuation module corresponding to the g-th optical signal attenuates the q-th optical signal, where p is not equal to q.

[0146] Optionally, the variable optical attenuation component includes L variable optical attenuation modules, and L is smaller than N, indicating that at least one optical signal does not correspond to a variable optical attenuation module.

[0147] In one optional embodiment, for each of the aforementioned optical amplifiers, to prevent reverse ASE light from transmitting in the opposite direction, the optical amplifier further includes an isolator assembly. The isolator assembly is located in a first optical path between a first fiber array and a second fiber array. The first optical path is the optical path through which the first fiber array transmits the optical signal to be amplified to the second fiber array. The isolator assembly is capable of preventing reverse ASE light from transmitting from the second fiber array to the first fiber array. Figure 18 provides a schematic diagram of an optical amplifier including an isolator assembly.

[0148] Optionally, for a forward-pumped or reverse-pumped optical amplifier, the isolator assembly includes n isolators, and the n isolators are located on an incident optical path of an optical signal to be amplified.

[0149] Optionally, for the optical amplifier shown in FIG9 , the isolator assembly includes n+d isolators, and the n+d isolators are located on the incident optical path of the optical signal to be amplified.

[0150] In an optional manner, for each optical amplifier mentioned above, the optical path for forward pumping of the optical signal is shown in FIG19 . The various optical amplifiers mentioned above are displayed in the YZ plane, and the optical path shown in FIG19 is displayed in the XZ plane.

[0151] Optionally, both the first and second multiplexing modules are dichroic mirrors. The dichroic mirror is a glass sheet with a filter coating on its rear surface. The filter coating reflects the pump light signal but transmits the optical signal to be amplified. For example, the wavelength of the pump light signal is 980 nm, and the wavelength of the optical signal to be amplified is 1550 nm.

[0152] In an optional manner, FIG20 also provides a schematic diagram of an equivalent optical path of the optical amplifier shown in FIG1 . In FIG20 , multiple optical signals are amplified by one optical amplifier.

[0153] In an optional manner, Figure 21 also provides a schematic diagram of an optical amplifier performing two-stage amplification on two optical signals. Figure 22 also provides a schematic diagram of an optical amplifier performing three-stage amplification on three optical signals.

[0154] In an optional manner, the first fiber array and the second fiber array can be implemented using gain fibers. Then the first fiber array is connected to the gain fibers, and the second fiber array is connected to the gain fibers. In fact, the gain fibers serve as both fiber arrays and gain fibers.

[0155] In the embodiments of the present application, the optical amplifier utilizes multi-channel spatial integration technology, enabling multiplexing of passive components and reducing the cost and size of the optical amplifier. In particular, when amplifying multi-channel optical signals, there is no need to deploy multiple optical amplifiers, which not only reduces the size of the multi-stage amplifier but also reduces the cost of optical amplification.

[0156] It should be noted that, in the embodiment of the present application, the lengths of the first gain fiber and the second gain fiber can be set according to actual needs. Based on the above description, various optical amplifier structures can be combined, all of which fall within the scope of protection of this application and will not be described here.

[0157] In an embodiment of the present application, a communication system is further provided. The communication system includes a first communication device, an optical amplifier, and a second communication device. The first communication device and the second communication device are both different ROADMs, and the optical amplifier is any of the optical amplifiers described above. The first communication device inputs T optical signals into the optical amplifier, where T is less than or equal to N. The optical amplifier amplifies the T optical signals to obtain an amplified optical signal, and transmits the amplified optical signal to the second communication device. The second communication device receives the amplified optical signal.

[0158] In this application, the terms "first" and "second" are used to distinguish between identical or similar items having substantially the same effects and functions. It should be understood that there is no logical or temporal dependency between "first" and "second," nor is there a limitation on quantity or order of execution. It should also be understood that although the following description uses the terms first and second, etc. to describe various elements, these elements should not be limited by the terms. These terms are merely used to distinguish one element from another. For example, without departing from the scope of the various examples, a first optical fiber array may be referred to as a second optical fiber array, and similarly, a second optical fiber array may be referred to as a first optical fiber array. Both the first optical fiber array and the second optical fiber array may be optical fiber arrays, and in some cases, may be separate and different optical fiber arrays.

[0159] The term "at least one" in this application means one or more, and the term "plurality" in this application means two or more.

[0160] In this application, the term "and / or" includes three cases. For example, A and / or B includes A, B and A and B.

[0161] The above description is merely an exemplary embodiment of the present application, but the scope of protection of the present 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 such modifications or substitutions should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. An optical amplifier, characterized in that, For amplifying N optical signals, where N is greater than or equal to 1, the optical amplifier includes a multiplexing component, a first fiber array, a second fiber array, and a first gain fiber; The multiplexing component is located on the optical path between the first fiber array and the second fiber array. One end of the first fiber array is connected to the first gain fiber, and the other end of the second fiber array is connected to the first gain fiber; The first fiber array is configured to receive the j-th level optical signal of the i-th optical signal among the N optical signals and input the j-th level optical signal to the second fiber array. The j-th level optical signal is the unamplified optical signal or the amplified optical signal of the i-th optical signal. j is greater than or equal to 1 and less than or equal to n, where n is the first amplification stage number of the i-th optical signal, and i is less than or equal to N; The multiplexing component is configured to receive the j-th level pump optical signal and input the j-th level pump optical signal to the first gain fiber through the first fiber array and / or the second fiber array. The j-th level pump optical signal is used to provide pump excitation for the j-th level optical signal; The second fiber array is configured to input the j-th level optical signal to the first gain fiber, so that the first gain fiber inputs the (j + 1)-th level optical signal to the first fiber array. The (j + 1)-th level optical signal is the amplified optical signal of the j-th level optical signal; The first fiber array is further configured to input the (j + 1)-th level optical signal to the second fiber array; The second fiber array is further configured to output the (j + 1)-th level optical signal.

2. The optical amplifier according to claim 1, wherein When j is equal to 1, the j-th level optical signal comes from the external input fiber connected to the first fiber array. When j is greater than 1, the j-th level optical signal comes from the first gain fiber; The second fiber array is further configured to input the (j + 1)-th level optical signal to the first gain fiber to perform the first amplification process when j is less than n, and output the (j + 1)-th level optical signal when j is equal to n.

3. The optical amplifier according to claim 1, characterized in that, The optical amplifier further includes a second gain fiber and a transmission fiber for the i-th optical signal. Both ends of the second gain fiber are connected to the second fiber array, and both ends of the transmission fiber are connected to the first fiber array; The multiplexing component is further configured to receive the m-th level pump optical signal and input the m-th level pump optical signal to the second fiber array. The m-th level pump optical signal is used to provide pump excitation for the m-th level optical signal. m is greater than or equal to 1 and less than or equal to d, where d is the second amplification stage number of the i-th optical signal, and the m-th level optical signal comes from the first fiber array; The second fiber array is further configured to input the m-th level pump optical signal and the m-th level optical signal to the second gain fiber, receive the (m + 1)-th level optical signal from the second gain fiber, and input the (m + 1)-th level optical signal to the multiplexing component. The (m + 1)-th level optical signal is the amplified optical signal of the m-th level optical signal; The multiplexing component is further configured to input the (m + 1)-th level optical signal to the first fiber array; The first optical fiber array is further configured to input the (m + 1)-th level optical signal into the transmission optical fiber, receive the (m + 1)-th level optical signal from the transmission optical fiber, and input the (m + 1)-th level optical signal into the second optical fiber array; The second optical fiber array is further configured to, when m is less than d, input the (m + 1)-th level optical signal into the first gain optical fiber or the second gain optical fiber to perform the first amplification process or the second amplification process, and when m is equal to d, output the (m + 1)-th level optical signal.

4. The optical amplifier according to claim 3, characterized in that, When m is equal to 1 and j is equal to n, the m-th level optical signal is the (j + 1)-th level optical signal; The second optical fiber array is further configured to, when m is less than d, input the (m + 1)-th level optical signal into the second gain optical fiber to perform the second amplification process.

5. The optical amplifier according to claim 4, wherein The first optical fiber array includes the first input ends and the first output ends of all levels of the i-th optical signal, the second optical fiber array includes the second input ends, the second output ends of all levels of the i-th optical signal, and the (d + 1)-th level output end, the transmission optical fiber includes the transmission sub-fibers of all levels corresponding to the i-th optical signal, the second gain optical fiber includes the second gain sub-fibers of all levels corresponding to the i-th optical signal, and the multiplexing component includes the first multiplexing modules of all levels corresponding to the i-th optical signal; One end of the m-th level transmission sub-fiber is connected to the m-th level first input end, and the other end is connected to the m-th level first output end; One end of the m-th level second gain sub-fiber is connected to the m-th level second input end, and the other end is connected to the m-th level second output end; The m-th level first multiplexing module is located on the optical path between the m-th level first output end and the m-th level second input end; The (d + 1)-th level output end is located on the outgoing optical path of the d-th level first input end.

6. The optical amplifier according to claim 5, wherein The m-th level first multiplexing module is configured to receive the m-th level pump optical signal and input the m-th level pump optical signal into the m-th level second input end; The m-th level second input end is configured to input the m-th level pump optical signal into the m-th level second gain sub-fiber; The m-th level second output end is configured to input the m-th level optical signal into the m-th level second gain sub-fiber; The m-th level second input end is further configured to receive the (m + 1)-th level optical signal from the m-th level second gain sub-fiber and input the (m + 1)-th level optical signal into the m-th level first multiplexing module; The m-th level first multiplexing module is further configured to input the (m + 1)-th level optical signal into the m-th level first output end; The m-th level first output end is configured to input the (m + 1)-th level optical signal into the m-th level transmission sub-fiber; The m-th level first input end is configured to receive the (m + 1)-th level optical signal from the m-th level transmission sub-fiber, when m is less than d, input the (m + 1)-th level optical signal into the (m + 1)-th level second output end, and when m is equal to d, input the (m + 1)-th level optical signal into the (d + 1)-th level output end; The (m + 1)-th level second output end is configured to input the (m + 1)-th level optical signal into the (m + 1)-th level second gain sub-fiber to perform the second amplification process; The (d + 1)-th level output terminal is configured to output the (m + 1)-th level optical signal.

7. The optical amplifier according to any one of claims 1 to 6, characterized in that, The first optical fiber array includes input terminals at all levels of the i-th optical signal, the second optical fiber array includes output terminals at all levels of the i-th optical signal, the first gain optical fiber includes first gain sub-fibers at all levels corresponding to the i-th optical signal, and the multiplexing component includes second multiplexing modules at all levels corresponding to the i-th optical signal; The j-th level second multiplexing module is located on the optical path between the j-th level input terminal and the j-th level output terminal. The (j + 1)-th level input terminal is connected to one end of the j-th level first gain sub-fiber, the j-th level output terminal is connected to the other end of the j-th level first gain sub-fiber, and the (n + 1)-th level output terminal is located on the outgoing optical path of the (n + 1)-th level input terminal; or, The first level output terminal is located on the outgoing optical path of the first level input terminal. The j-th level second multiplexing module is located on the optical path between the (j + 1)-th level input terminal and the (j + 1)-th level output terminal. The (j + 1)-th level input terminal is connected to one end of the j-th level first gain sub-fiber, the j-th level output terminal is connected to the other end of the j-th level first gain sub-fiber, and the (n + 1)-th level output terminal is located on the outgoing optical path of the n-th level second multiplexing module.

8. The optical amplifier according to claim 7, wherein The j-th level input terminal is configured to input the j-th level optical signal to the j-th level second multiplexing module; The j-th level second multiplexing module is configured to receive the j-th level optical signal and the j-th level pump optical signal, combine the j-th level optical signal and the j-th level pump optical signal into a combined signal, and input the combined signal to the j-th level output terminal; The j-th level output terminal is configured to input the combined signal to the j-th level first gain sub-fiber; The (j + 1)-th level input terminal is configured to receive the (j + 1)-th level optical signal from the j-th level first gain sub-fiber. When j is less than n, input the (j + 1)-th level optical signal to the (j + 1)-th level second multiplexing module to perform a first amplification process. When j is equal to n, input the (j + 1)-th level optical signal to the (n + 1)-th output terminal; The (n + 1)-th output terminal is configured to output the (j + 1)-th level optical signal.

9. The optical amplifier according to claim 7, wherein The first level input terminal is configured to input the first level optical signal to the first level output terminal; The j-th level second multiplexing module is configured to receive the j-th level pump optical signal and input the j-th level pump optical signal to the (j + 1)-th level input terminal; The (j + 1)-th level input terminal is configured to input the j-th level pump optical signal to the j-th level first gain sub-fiber; The j-th level output terminal is configured to input the j-th level optical signal, which comes from the j-th level input terminal, to the j-th level first gain sub-fiber; The (j + 1)-th level input terminal is further configured to receive the (j + 1)-th level optical signal from the j-th level first gain sub-fiber and input the (j + 1)-th level optical signal to the j-th level second multiplexing module; The j-th level second multiplexing module is further configured to input the (j + 1)-th level optical signal to the (j + 1)-th level output terminal; The (j + 1)-th level output end is configured to, when j is less than n, input the (j + 1)-th level optical signal to the first gain sub-fiber of the (j + 1)-th level to perform the first amplification process, and when j is equal to n, output the (j + 1)-th level optical signal.

10. The optical amplifier according to any one of claims 7 to 9, characterized in that, The first amplification levels of the N optical signals are the same, and the amplification level of the N optical signals is equal to K divided by N, where K is equal to the number of input ends of the i-th optical signal minus N.

11. The optical amplifier according to any one of claims 1 to 10, characterized in that, The first optical fiber array is configured to input the j-th level optical signal to the multiplexing component. The multiplexing component is further configured to input the j-th level optical signal to the second optical fiber array.

12. The optical amplifier according to any one of claims 1 to 11, characterized in that, The optical amplifier further includes a beam splitting component and a monitoring component. The beam splitting component is located on the optical path between the first optical fiber array and the multiplexing component. The monitoring component and the multiplexing component are located on the mutually perpendicular output optical paths of the beam splitting component.

13. The optical amplifier according to any one of claims 1 to 12, characterized in that, The optical amplifier further includes a first collimation component, a second collimation component, and a third collimation component. The first collimation component is located on the optical path between the first optical fiber array and the multiplexing component, the second collimation component is located on the optical path between the multiplexing component and the second optical fiber array, and the third collimation component is located on the incident optical path of the multiplexing component.

14. The optical amplifier according to any one of claims 1 to 13, characterized in that, The optical amplifier further includes a flat filtering component. The flat filtering component is located on the optical path between the first optical fiber array and the multiplexing component, or on the optical fiber link between the first gain optical fiber and the first optical fiber array.

15. The optical amplifier according to any one of claims 1 to 14, characterized in that, The optical amplifier further includes a variable optical attenuation component. One end of the variable optical attenuation component is connected to the first optical fiber array, and the other end of the variable optical attenuation component is connected to the second optical fiber array. The variable optical attenuation component is configured to receive the (j + 1)-th level optical signal from the second optical fiber array, perform attenuation processing on the (j + 1)-th level optical signal to obtain an attenuated optical signal, and input the attenuated optical signal to the first optical fiber array, so that the first optical fiber array inputs the attenuated optical signal to the second optical fiber array.

16. The optical amplifier according to any one of claims 1 to 15, characterized in that, The optical amplifier further includes an isolator component. The isolator component is located on the first optical path between the first optical fiber array and the second optical fiber array, and the first optical path is the optical path for the first optical fiber array to input the optical signal to be amplified to the second optical fiber array.

17. A communication system, characterized in that, Comprising a first communication device, an optical amplifier according to any one of claims 1 to 16, and a second communication device. The first communication device is configured to send T optical signals to the optical amplifier, where T is less than or equal to N. The optical amplifier is configured to perform amplification processing on the T optical signals to obtain amplified optical signals, and send the amplified optical signals to the second communication device. The second communication device is configured to receive the amplified optical signals.

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