Low-noise full-band fiber amplifier and signal transmission system

Abstract

The present invention relates to the technical field of communications, and provides a low-noise full-band fiber amplifier and a signal transmission system. The low-noise full-band fiber amplifier comprises a first wavelength division multiplexing component, a wavelength combining component, a first gain module, and a second gain module. The first wavelength division multiplexing component demultiplexes a full-band optical signal to obtain a first half-band optical signal and a second half-band optical signal. The first gain module performs forward doped fiber amplification and backward Raman amplification on the first half-band optical signal to obtain a first half-band gain signal; and the second gain module performs forward doped fiber amplification and backward Raman amplification on the second half-band optical signal to obtain a second half-band gain signal. The wavelength combining component multiplexes the first half-band gain signal and the second half-band gain signal to obtain a full-band gain signal. In the present invention, the entire band is divided into two major bands, and the two major bands are amplified respectively to equalize insertion losses of sub-bands; and by introducing backward Raman amplification, the low-noise full-band fiber amplifier is realized, and the backward Raman amplification is used to facilitate subsequent signal demodulation.

Description

Low-noise full-band optical fiber amplifier and signal transmission system

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the following patent application:

[0003] (1) Chinese patent application No. 202410596052.3, filed on May 14, 2024, entitled "Low-noise full-band optical fiber amplifier and signal transmission system". TECHNICAL FIELD

[0004] The present application relates to the field of communication technology, in particular to a low-noise full-band optical fiber amplifier and signal transmission system. BACKGROUND

[0005] With the rapid evolution of new telecommunication services such as 5G, video on demand, virtual reality (VR), mobile Internet of Things, DCI data communication, etc., the demand for bandwidth construction of backbone transmission network is becoming higher and higher. In the era of single-wavelength 400Gbit / s of backbone network, in order to meet the requirement of optical signal noise ratio (OSNR) of the system, the baud rate of channel modulation will reach 130Gbit / s, so the channel spacing will reach 150GHz, and to realize the transmission of 80 channels, 12THz bandwidth will be needed. Since the erbium-doped fiber amplifier cannot realize 12THz amplification at the same time, it can only amplify in bands, and the entire amplification wavelength covers 1524-1627nm, a total bandwidth of 103nm, which is difficult to meet the full-band signal amplification. In order to meet the demand for higher bandwidth, single wavelength will evolve to 800Gbit / s and 1.2Tbit / s. The channel spacing will reach 200GHz or higher bandwidth, so in the single-wavelength 800Gbit / s or 1.2Tbit / s system, to realize the transmission of 80 channels, it is necessary to expand to the S band, and in large network application scenarios such as data centers, the demand for network bandwidth will be higher, thus requiring amplification of all bands of O band, S band, C band, L band and U band.

[0006] Therefore, it is urgent to overcome the defects of the prior art in the technical field.

[0007] CONTENT OF THE APPLICATION

[0008] The technical problem to be solved by the present application is that the prior art cannot amplify full-band signals with low noise.

[0009] The present application adopts the following technical solutions:

[0010] The application provides a low-noise full-waveband optical fiber amplifier, which comprises a first wavelength division multiplexing component 1, a combining component 2 and at least two gain modules; based on different connection positions, the two gain modules are divided into a first gain module 31 and a second gain module 32;

[0011] The first gain module 31 is connected between the transmission end of the first wavelength division multiplexing component 1 and the first input end of the combining component 2, and the second gain module 32 is connected between the reflection end of the first wavelength division multiplexing component 1 and the second input end of the combining component 2; the common end of the first wavelength division multiplexing component 1 is a signal input end; and the output end of the combining component 2 is a signal output end;

[0012] The first wavelength division multiplexing component 1 is used for dividing the full-waveband light from the signal input end into first half-waveband light and second half-waveband light;

[0013] The first gain module 31 is used for performing forward doped fiber amplification and backward Raman amplification on the first half-waveband light to obtain first half-waveband gain signals; and the second gain module 32 is used for performing forward doped fiber amplification and backward Raman amplification on the second half-waveband light to obtain second half-waveband gain signals;

[0014] The combining component 2 is used for combining the first half-waveband gain signals and the second half-waveband gain signals to obtain full-waveband gain signals.

[0015] Preferably, the first gain module 31 comprises a first ring component 311, a first Raman pump component 312 and a first amplification component 313.

[0016] The first port of the first ring component 311 is connected with the first Raman pump component 312, the second port of the first ring component 311 is the input end of the first gain module 31, the third port of the first ring component 311 is connected with the signal input end of the first amplification component 313, and the signal output end of the first amplification component 313 is the output end of the first gain module 31.

[0017] The first ring component 311 is used for transmitting the first half-waveband light to the first amplification component 313 in a forward direction, and the first amplification component 313 is used for performing doped fiber amplification on the first half-waveband light.

[0018] The first Raman pump component 312 is used for outputting first Raman light matched with the first half-waveband light.

[0019] The first ring assembly 311 is also used to reversely transmit the first Raman light to the transmission end of the first wavelength division multiplexing assembly 1, so that the first wavelength division multiplexing assembly 1 combines the first Raman light and the second Raman light to obtain full Raman light, and reversely transmits the full Raman light to the far-end transmission fiber 4 at the signal input end, so that the full-band light is backward Raman amplified using the full Raman light in the far-end transmission fiber 4.

[0020] Preferably, the first amplification assembly 313 comprises a first splitting unit 3131, a first combining unit 3132 and a plurality of first amplification units 3133.

[0021] The input end of the first splitting unit 3131 is the signal input end of the first amplification assembly 313.

[0022] Between each output end of the first splitting unit 3131 and the corresponding input end of the first combining unit 3132, a first amplification unit 3133 is connected.

[0023] The first splitting unit 3131 is used to split the first half-band light to obtain a plurality of sub-band lights, the first amplification unit 3133 is used to forwardly amplify the corresponding sub-band light by doped fiber to obtain a sub-band gain signal, and the first combining unit 3132 is used to combine the plurality of sub-band gain signals to obtain a first half-band gain signal.

[0024] Preferably, when the fiber amplifier comprises N amplification units, the fiber amplifier further comprises a second wavelength division multiplexing assembly 5, a first coupling assembly 6 and a first fiber pump assembly 7.

[0025] The common end of the second wavelength division multiplexing assembly 5 is connected to the signal output end of the i-th amplification unit, the transmission end of the second wavelength division multiplexing assembly 5 is coupled on the signal transmission path, and the reflection end of the second wavelength division multiplexing assembly 5 is connected to the first input port of the first coupling assembly 6.

[0026] The first fiber pump assembly 7 is connected to the second input port of the first coupling assembly 6, and each output port of the first coupling assembly 6 is connected to the pump input end of the corresponding amplification unit.

[0027] The first fiber pump assembly 7 is used to generate pump light.

[0028] The second wavelength division multiplexing assembly 5 is used to split the signal light and the pump leakage light from the output light of the i-th amplification unit, so that the signal light continues to transmit on the signal transmission path, and the pump leakage light is transmitted to the first coupling assembly 6.

[0029] The first coupling component 6 is used for coupling and transmitting the pump light and the pump leakage light to the pump input end of the corresponding amplification unit, so as to guide the pump leakage light of the i th amplification unit to the corresponding amplification unit for optical amplification; wherein the amplification unit is the first amplification unit 3133 and / or the second amplification unit 3233.

[0030] Preferably, the first splitting unit 3131 comprises a plurality of mutually cascaded wave splitters.

[0031] Preferably, when the full-band light comprises 6 band lights, the first splitting unit 3131 comprises 2 mutually cascaded wave splitters, which are respectively a first wave splitter 31311 and a second wave splitter 31312.

[0032] The first output end of the first wave splitter 31311 is connected with the input end of the second wave splitter 31312.

[0033] The input end of the first wave splitter 31311 is the input end of the first splitting unit 3131; the second output end of the first wave splitter 31311, the first output end of the second wave splitter 31312 and the second output end of the second wave splitter 31312 are the respective output ends of the first splitting unit 3131.

[0034] The first wave splitter 31311 is used for splitting the first half-band light to obtain the first sub-band light and the remaining band light, and the second wave splitter 31312 is used for splitting the remaining band light to obtain the second sub-band light and the third sub-band light.

[0035] Preferably, the first combining unit 3132 comprises a plurality of mutually cascaded wave combiners.

[0036] Preferably, when the full-band light comprises 6 band lights, the first combining unit 3132 comprises 2 mutually cascaded wave combiners, which are respectively a first wave combiner 31321 and a second wave combiner 31322.

[0037] The output end of the first wave combiner 31321 is connected with the first input end of the second wave combiner 31322.

[0038] The first input end of the first wave combiner 31321, the second input end of the first wave combiner 31321 and the second input end of the second wave combiner 31322 are the respective input ends of the first combining unit 3132; the output end of the second wave combiner 31322 is the output end of the first combining unit 3132.

[0039] The first combiner 31321 is configured to combine the first sub-band gain signal and the second sub-band gain signal to obtain a partial band gain signal, and the second combiner 31322 is configured to combine the partial band gain signal and a third sub-band gain signal to obtain a first half band gain signal.

[0040] Preferably, the full band light includes one or more of O band, E band, S band, C band, L band and U band.

[0041] Preferably, when the full band light includes O band, E band, S band, C band, L band and U band, the first half band light includes O band, E band and S band, and the second half band light includes C band, L band and U band.

[0042] Compared with the prior art, the present application has the following beneficial effects: the present application divides the whole band (full band light) into two large bands, and then amplifies the two large bands respectively, so that the insertion loss of each sub-band is relatively average. The present application introduces Raman amplification, realizes a low-noise full band fiber amplifier by mixing a distributed Raman fiber amplifier and a doped fiber amplifier, and realizes the low-noise full band fiber amplifier by using backward Raman amplification, that is, the Raman pump wavelength is transmitted in the opposite direction of the signal, so as to facilitate subsequent signal demodulation. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0044] Fig. 1 is a structural schematic diagram of a first low-noise full band fiber amplifier according to an embodiment of the present application;

[0045] Fig. 2 is a structural schematic diagram of a second low-noise full band fiber amplifier according to an embodiment of the present application;

[0046] Fig. 3 is a structural schematic diagram of a third low-noise full band fiber amplifier according to an embodiment of the present application;

[0047] Fig. 4 is a structural schematic diagram of a fourth low-noise full band fiber amplifier according to an embodiment of the present application;

[0048] Fig. 5 is a structural schematic diagram of a fifth low-noise full band fiber amplifier according to an embodiment of the present application;

[0049] Fig. 6 is a structural schematic diagram of a sixth low-noise full-band optical fiber amplifier according to an embodiment of the present application;

[0050] Fig. 7 is a structural schematic diagram of a seventh low-noise full-band optical fiber amplifier according to an embodiment of the present application;

[0051] Fig. 8 is a structural schematic diagram of an eighth low-noise full-band optical fiber amplifier according to an embodiment of the present application;

[0052] Fig. 9 is a structural schematic diagram of a ninth low-noise full-band optical fiber amplifier according to an embodiment of the present application;

[0053] Fig. 10 is a structural schematic diagram of a tenth low-noise full-band optical fiber amplifier according to an embodiment of the present application;

[0054] Fig. 11 is a structural schematic diagram of an eleventh low-noise full-band optical fiber amplifier according to an embodiment of the present application;

[0055] Fig. 12 is a structural schematic diagram of a twelfth low-noise full-band optical fiber amplifier according to an embodiment of the present application;

[0056] Fig. 13 is a structural schematic diagram of a thirteenth low-noise full-band optical fiber amplifier according to an embodiment of the present application;

[0057] Fig. 14 is a structural schematic diagram of a first amplification unit in a low-noise full-band optical fiber amplifier according to an embodiment of the present application;

[0058] Fig. 15 is a structural schematic diagram of a fourteenth low-noise full-band optical fiber amplifier according to an embodiment of the present application;

[0059] Fig. 16 is a structural schematic diagram of a signal transmission system according to an embodiment of the present application.

[0060] In all the drawings, the same reference signs are used to denote the same elements or structures, wherein:

[0061] 1, first wavelength division multiplexing component; 2, combining component; 31, first gain module; 311, first ring component; 312, first Raman pump component; 313, first amplification component; 3131, first splitting unit; 31311, first splitter; 31312, second splitter; 3132, first combining unit; 31321, first combiner; 31322, second combiner; 3133, first amplification unit; 31331, first amplification unit of S band; 31332, first amplification unit of E band; 31333, first amplification unit of O band; 32, second gain module; 321, second ring component; 322, second Raman pump component; 323, second amplification component; 3231, second splitting unit; 32311, third splitter; 32312, fourth splitter; 3232, second combining unit; 32321, third combiner; 32322, fourth combiner; 3233, second amplification unit; 32331, second amplification unit of C band; 32332, second amplification unit of L band; 32333, second amplification unit of U band; 4, remote transmission optical fiber; 5, second wavelength division multiplexing component; 6, first coupling component; 7, first fiber pump component; 8, second fiber pump component; 9, isolator; 10, flat filter; 11, third wavelength division multiplexing component; 12, fourth wavelength division multiplexing component; 131, fiber amplification stage; 132, optical switch; 133, fifth wavelength division multiplexing component; 134, second coupling component; 135, third fiber pump component; 136, sixth wavelength division multiplexing component; 137, seventh wavelength division multiplexing component; 138, fourth fiber pump component. DETAILED DESCRIPTION

[0062] In order to make the objects, technical solutions and advantages of the present application clearer, the following further describes the present application with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application.

[0063] In the description of the present application, the terms "inner", "outer", "longitudinal", "transverse", "upper", "lower", "top", "bottom" and the like indicate the orientation or positional relationship shown in the drawings and are only used to facilitate the description of the present application and should not be understood as a requirement that the present application must be constructed and operated in a particular orientation, therefore should not be understood as a limitation of the present application.

[0064] In the present application, the terms "first", "second" and the like are only for descriptive purposes and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" and the like can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise stated, the meaning of "multiple" is two or more.

[0065] In the present application, unless otherwise explicitly specified and limited, the term "connection" should be understood broadly, for example, "connection" can be fixed connection, or detachable connection, or integral; can be directly connected, or indirectly connected through intermediate medium. In addition, the term "coupling" can be electrical connection for signal transmission or a way to form a light transmission path.

[0066] In addition, the technical features involved in each of the embodiments of the application described below can be combined with each other as long as there is no conflict between them.

[0067] Embodiment 1:

[0068] Embodiment 1 of the present application provides a low-noise full-band optical fiber amplifier, as shown in FIG. 1, comprising a first wavelength division multiplexing component 1, a combining component 2, a first gain module 31 and a second gain module 32; in actual application scenarios, the first wavelength division multiplexing component 1 and the combining component 2 are both wavelength division multiplexers.

[0069] The first gain module 31 is connected between the transmission end of the first wavelength division multiplexing component 1 and the first input end of the combining component 2, and the second gain module 32 is connected between the reflection end of the first wavelength division multiplexing component 1 and the second input end of the combining component 2; the common end of the first wavelength division multiplexing component 1 is a signal input end; and the output end of the combining component 2 is a signal output end.

[0070] The first wavelength division multiplexing component 1 is used to divide the full-band light from the signal input end into first half-band light and second half-band light; wherein the first half-band light and the second half-band light contain the same number of wavebands, so as to divide the entire waveband (full-band light) into two large wavebands (first half-band light and second half-band light), and then amplify the two large wavebands respectively, so that the insertion loss of each sub-waveband is relatively average.

[0071] The full-band light includes one or more of O-band, E-band, S-band, C-band, L-band and U-band. In an optional embodiment, the full-band light includes O-band, E-band, S-band, C-band, L-band and U-band, and when the full-band light includes O-band, E-band, S-band, C-band, L-band and U-band, the first half-band light includes O-band, E-band and S-band, and the second half-band light includes C-band, L-band and U-band.

[0072] The first gain module 31 is used for forward doped fiber amplification and backward Raman amplification of the first half-waveband light to obtain a first half-waveband gain signal; the second gain module 32 is used for forward doped fiber amplification and backward Raman amplification of the second half-waveband light to obtain a second half-waveband gain signal; wherein the doped fiber amplification refers to amplification of light by a doped fiber amplifier, and the type of the doped fiber amplifier is obtained by analysis of the waveband of the light to be amplified by a person skilled in the art, and in actual use, the doped fiber amplifier can be an erbium-doped fiber amplifier, a bismuth-doped fiber amplifier, etc.

[0073] The combining assembly 2 is used for combining the first half-waveband gain signal and the second half-waveband gain signal to obtain a full-waveband gain signal.

[0074] In view of the fact that different doped fiber gain media and more combining and dividing devices are used in each sub-waveband in the full-waveband communication system, the noise index of the full-waveband amplifier is relatively large, in order to effectively reduce the noise index of the full-waveband amplifier, the embodiment introduces Raman amplification, and a low-noise full-waveband fiber amplifier is realized by a hybrid distributed Raman fiber amplifier and a doped fiber amplifier, but since the waveband of the full-waveband amplifier is too wide, the Raman pump wavelength (i.e. Raman light) coincides with the sub-waveband signal waveband, if the Raman light is directly added to the sub-waveband signal for forward amplification, it is difficult to distinguish the mixed Raman light and signal light, which leads to difficulty in subsequent wave division, in order to solve this problem, the embodiment adopts a backward Raman amplification mode, that is, the Raman pump wavelength is transmitted in the opposite direction of the signal.

[0075] In order to ensure that the backward Raman amplification does not affect the normal transmission of light, the embodiment further provides an optional implementation, as shown in FIG. 2, the first gain module 31 comprises a first ring assembly 311, a first Raman pump assembly 312 and a first amplification assembly 313; the first port of the first ring assembly 311 is connected with the first Raman pump assembly 312, the second port of the first ring assembly 311 is the input end of the first gain module 31, the third port of the first ring assembly 311 is connected with the signal input end of the first amplification assembly 313, and the signal output end of the first amplification assembly 313 is the output end of the first gain module 31; the first ring assembly 311 is used for transmitting the first half-waveband light forward to the first amplification assembly 313, and the first amplification assembly 313 is used for amplifying the first half-waveband light by a doped fiber; the first Raman pump assembly 312 is used for outputting the first Raman light matched with the first half-waveband light; the first ring assembly 311 is further used for transmitting the first Raman light backward to the transmission end of the first wavelength division multiplexing assembly 1, so that the first wavelength division multiplexing assembly 1 combines the first Raman light and the second Raman light to obtain full Raman light, and transmits the full Raman light backward to the far-end transmission fiber 4 located at the signal input end, so that the full-waveband light is amplified by the full Raman light backward in the far-end transmission fiber 4. The second Raman light is generated in the second gain module 32 and transmitted backward to the second output end of the wavelength division multiplexing assembly.

[0076] The structure of the second gain module 32 and the structure of the first gain module 31 are realized on the basis of the same concept, that is, the second gain module 32 comprises a second ring assembly 321, a second Raman pump assembly 322 and a second amplification assembly 323.

[0077] The first port of the second ring assembly 321 is connected with the second Raman pump assembly 322, the second port of the second ring assembly 321 is the input end of the second gain module 32, the third port of the second ring assembly 321 is connected with the signal input end of the second amplification assembly 323, and the signal output end of the second amplification assembly 323 is the output end of the second gain module 32.

[0078] The second ring assembly 321 is used for transmitting the second half-waveband light forward to the second amplification assembly 323, and the second amplification assembly 323 is used for amplifying the second half-waveband light by a doped fiber.

[0079] The second Raman pump assembly 322 is used for outputting the second Raman light matched with the second half-waveband light; and the second ring assembly 321 is further used for transmitting the second Raman light backward to the reflection end of the first wavelength division multiplexing assembly 1.

[0080] In actual use, the first and second ring-shaped components 311 and 321 can be circulators, i.e., the first ring-shaped component 311 is a circulator and the second ring-shaped component 321 is a circulator. The first, second and third ports of the ring-shaped component are described based on the common knowledge of those skilled in the art, i.e., the deflection direction of the ring-shaped component is to deflect the input of the first port to the output of the second port, deflect the input of the second port to the output of the third port, and deflect the input of the third port to the output of the first port.

[0081] When the first half-waveband light includes O, E and S wavebands, the first Raman light includes light of wavelengths of 10xx nm, 12xx nm, 13xx nm and 14xx nm, and when the second half-waveband light includes C, L and U wavebands, the second Raman light includes light of a wavelength of 15xx nm.

[0082] The first wavelength division multiplexing component 1 not only divides the full-waveband light for forward transmission, but also combines the first and second Raman light for reverse transmission. In the far-end transmission optical fiber 4, the first Raman light is actually still used for Raman amplification of the first half-waveband light in the full-waveband light, and the second Raman light is actually still used for Raman amplification of the second half-waveband light in the full-waveband light.

[0083] It should be understood that, in actual transmission, the signal actually transmitted to the signal input end is a signal having part of the gain due to the backward Raman amplification. After the first and second amplification components 313 and 323, the signal having part of the gain is further amplified. For ease of description, the embodiment still describes the amplification process based on the full-waveband light without gain.

[0084] The embodiment integrates the Raman pump wavelengths of each sub-waveband as much as possible to form a unified Raman pump component, and then couples the Raman pump wavelengths into the line through a circulator, so that the reverse transmission of the Raman light does not affect the forward transmission amplification of the signal, thereby facilitating subsequent signal demodulation.

[0085] In an actual application scenario, as shown in FIG. 3, the first amplification component 313 includes a first splitting unit 3131, a first combining unit 3132 and a plurality of first amplification units 3133; an input end of the first splitting unit 3131 is a signal input end of the first amplification component 313; an output end of the first combining unit 3132 is a signal output end of the first amplification component 313; between each output end of the first splitting unit 3131 and a corresponding input end of the first combining unit 3132, a first amplification unit 3133 is connected; the first splitting unit 3131 is configured to split the first half-waveband light to obtain a plurality of sub-waveband lights; the first amplification unit 3133 is configured to perform forward doped fiber amplification on the corresponding sub-waveband light to obtain a sub-waveband gain signal; and the first combining unit 3132 is configured to combine the plurality of sub-waveband gain signals to obtain a first half-waveband gain signal.

[0086] In actual use, the first splitting unit 3131 can be a one-to-many wavelength division multiplexer, and there is also an embodiment in which the first splitting unit 3131 includes a plurality of cascaded splitters. As shown in FIG. 4, when the full-waveband light includes six waveband lights, the first splitting unit 3131 includes two cascaded splitters, namely a first splitter 31311 and a second splitter 31312; a first output end of the first splitter 31311 is connected to an input end of the second splitter 31312; an input end of the first splitter 31311 is an input end of the first splitting unit 3131; a second output end of the first splitter 31311, a first output end of the second splitter 31312 and a second output end of the second splitter 31312 serve as respective output ends of the first splitting unit 3131; the first splitter 31311 is configured to split the first half-waveband light to obtain a first sub-waveband light and a remaining waveband light; and the second splitter 31312 is configured to split the remaining waveband light to obtain a second sub-waveband light and a third sub-waveband light.

[0087] In actual use, the first combining unit 3132 can be a multipair one-way wavelength multiplexer, and there is also an embodiment in which the first combining unit 3132 comprises a plurality of combined wave devices connected in series. As shown in FIG. 4, when the full-band light comprises 6 band lights, the first combining unit 3132 comprises two combined wave devices connected in series, which are a first combined wave device 31321 and a second combined wave device 31322; the output end of the first combined wave device 31321 is connected with the first input end of the second combined wave device 31322; the first input end of the first combined wave device 31321, the second input end of the first combined wave device 31321 and the second input end of the second combined wave device 31322 are divided as the input ends of the first combining unit 3132; the output end of the second combined wave device 31322 is the output end of the first combining unit 3132; the first combined wave device 31321 is used for combining the first sub-band gain signal and the second sub-band gain signal to obtain a partial-band gain signal, and the second combined wave device 31322 is used for combining the partial-band gain signal with the third sub-band gain signal to obtain a first half-band gain signal.

[0088] That is, when the full-band light comprises 6 band lights, the number of output ends of the first splitting unit 3131 in the first amplification assembly 313 is 3, the number of first amplification units 3133 in the first amplification assembly 313 is 3, and the number of input ends of the first combining unit 3132 in the first amplification assembly 313 is 3, and one first amplification unit 3133 is connected between each output end of the first splitting unit 3131 and the corresponding input end of the first combining unit 3132.

[0089] The structure of the second amplification assembly 323 and the structure of the first amplification assembly 313 are based on the same concept, and as shown in FIG. 4, the second amplification assembly 323 comprises a second splitting unit 3231, a second combining unit 3232 and a plurality of second amplification units 3233 in an optional embodiment, wherein the second splitting unit 3231 comprises a third splitting wave device 32311 and a fourth splitting wave device 32312 connected in series, and the second combining unit 3232 comprises a third combined wave device 32321 and a fourth combined wave device 32322 connected in series.

[0090] The input end of the third splitter 32311 is connected with the third port of the second ring assembly 321, the first output end of the third splitter 32311 is connected with the input end of the fourth splitter 32312, the second output end of the third splitter 32311, the first output end of the fourth splitter 32312 and the second output end of the fourth splitter 32312 are respectively connected with the signal input end of a second amplification unit 3233, the signal output end of each second amplification unit 3233 is respectively connected with the first input end of the third combiner 32321, the second input end of the fourth combiner 32322 and the first input end of the fourth combiner 32322, each second amplification unit 3233 is used for amplifying the fourth sub-band light, the fifth sub-band light and the sixth sub-band light, the output end of the third combiner 32321 is connected with the second input end of the fourth combiner 32322, and the output end of the fourth combiner 32322 is connected with the second input end of the combiner assembly 2.

[0091] The first sub-band light, the second sub-band light, the third sub-band light, the fourth sub-band light, the fifth sub-band light and the sixth sub-band light are all single-band lights, for example, the first sub-band light is S-band light, the second sub-band light is O-band light, the third sub-band light is E-band light, the fourth sub-band light is C-band light, the fifth sub-band light is L-band light, and the sixth sub-band light is U-band light.

[0092] The first splitter 31311, the second splitter 31312, the third splitter 32311, the fourth splitter 32312, the first combiner 31321, the second combiner 31322, the third combiner 32321 and the fourth combiner 32322 can be wavelength division multiplexers in actual use. The first amplification unit 3133 and the second amplification unit 3233 can be corresponding doped fiber amplifiers, such as erbium doped fiber amplifiers (EDFA) or bismuth doped fiber amplifiers, and the corresponding doped elements of the first amplification unit 3133 and the second amplification unit 3233 connected at different positions can also be different, and the specific doped elements can be obtained by a person skilled in the art based on the wavelength requirement analysis of the light to be amplified on the path.

[0093] It should be noted that, for a doped fiber amplifier, corresponding pump light input is also required for optical amplification, that is, the first amplification unit 3133 and the second amplification unit 3233 are both connected with corresponding pump inputs. In order to make the drawings clear, the pump inputs of the first amplification unit 3133 and the second amplification unit 3233 are hidden in the drawings 1-5.

[0094] Embodiment 2:

[0095] Based on the basis of embodiment 1, this embodiment uses an erbium-doped fiber amplifier as the first amplification unit 3133 and the second amplification unit 3233, and in order to ensure normal transmission of signals, an isolator 9 or a gain flattening filter 10 can also be added at the signal input end of each first amplification unit 3133 and each second amplification unit 3233. However, in actual use, when higher output power is required, higher power pump light needs to be input to the erbium-doped fiber amplifier. However, with the use of high-power pump lasers, there is a problem of relatively large pump leakage light (such as greater than 20 mW) in a certain section of fiber in a specific optical path design. If the excessively high pump leakage light is not specially processed and directly input to the subsequent device (such as the isolator 9 or the isolator 9 plus the gain flattening filter 10), the following problems will occur: Since the wavelength of the pump light is relatively short (such as 980 nm), the photon energy is relatively high, and local absorption in the device causes the device to rise, affecting the performance of the device. Especially when working under high temperature conditions, the pump leakage light will cause the local temperature of the isolator 9 to be particularly high, and long-term work under this condition will cause device failure and shorten the service life, affecting the reliability of the high-temperature and high-power output of the EDFA. In order to solve this problem, the following preferred embodiments are provided in this embodiment, which specifically include:

[0096] When the fiber amplifier contains N amplification units, as shown in FIG. 6, the fiber amplifier further includes a second wavelength division multiplexing component 5, a first coupling component 6, and a first fiber pump component 7.

[0097] The common end of the second wavelength division multiplexing component 5 is connected to the signal output end of the i-th amplification unit, the transmission end of the second wavelength division multiplexing component 5 is coupled on the signal transmission path, and the reflection end of the second wavelength division multiplexing component 5 is connected to the first input port of the first coupling component 6; Specifically on the signal transmission path: when the second wavelength division multiplexing component 5 is not connected, the second wavelength division multiplexing component 5 has an original signal transmission path, and the signal light is transmitted on the signal transmission path.

[0098] The first fiber pump component 7 is connected to the second input port of the first coupling component 6, and each output port of the first coupling component 6 is connected to the pump input end of the corresponding amplification unit; The corresponding amplification unit can be any one or more amplification units (which can include the i-th amplification unit).

[0099] The first fiber pump assembly 7 is used to generate pump light; the second wavelength division multiplexing assembly 5 is used to separate the signal light and the pump leakage light from the output light of the ith amplification unit, so that the signal light continues to transmit on the signal transmission path, and the pump leakage light is transmitted to the first coupling assembly 6; wherein the pump leakage light can be understood as the remaining pump light when the signal is amplified by the ith amplification unit using the pump light.

[0100] The first coupling assembly 6 is used to couple and transmit the pump light and the pump leakage light to the pump input end of the corresponding amplification unit, so as to guide the pump leakage light of the ith amplification unit to the corresponding amplification unit for optical amplification; wherein the amplification unit is the first amplification unit 3133 and / or the second amplification unit 3233, as shown in FIG. 6, there are 3 first amplification units 3133 and 3 second amplification units 3233, so N is 6, i is a positive integer, and i is less than or equal to N, N can be understood as the total number of the first amplification unit 3133 and the second amplification unit 3233, and the specific value of i can be obtained by those skilled in the art according to the demand analysis.

[0101] The amplification unit whose corresponding pump input end is not connected with the first coupling assembly 6 can directly use the second fiber pump assembly 8 to supply pump light, that is, the pump input end of the amplification unit is connected with the second fiber pump assembly 8.

[0102] The embodiment can be understood as that each first amplification unit 3133 and each second amplification unit 3233 are understood as an amplification unit, the second wavelength division multiplexing assembly 5 is connected to the signal output end of any one or more amplification units, and the first coupling assembly 6 and the first fiber pump assembly 7 are connected in the above-mentioned manner, each output port of the first coupling assembly 6 is connected to the pump input end of the corresponding one or more amplification units, so that the pump leakage light of the corresponding amplification unit is separated out by the second wavelength division multiplexing assembly 5 and transmitted to the amplification unit by the first coupling assembly 6, realizing the reuse of the pump leakage light and effectively improving the noise coefficient and the output power of the amplification unit. The output port of the first coupling assembly 6 can also be connected to the pump input end of the ith amplification unit, so that the pump leakage light of itself flows back to itself for reuse, and the splitting ratio of the first coupling assembly 6 can be obtained by those skilled in the art according to the demand analysis.

[0103] It should be noted that the above-mentioned embodiment is described on the premise that the ith amplification unit adopts a forward pumping structure, in which the pump leakage light is transmitted together with the amplified signal light, that is, output from the signal output end of the ith amplification unit.

[0104] When the i-th amplification unit adopts the backward pumping structure, the pumping leakage light and the signal light are in opposite transmission directions. In this case, the common end of the second wavelength division multiplexing component 5 is connected to the signal input end of the i-th amplification unit, the transmission end of the second wavelength division multiplexing component 5 is coupled on the signal transmission path, and the reflection end of the second wavelength division multiplexing component 5 is connected to the first input port of the first coupling component 6. The first fiber pumping component 7 is connected to the second input port of the first coupling component 6, and each output port of the first coupling component 6 is connected to the pumping input end of the corresponding amplification unit, as shown in FIG. 7.

[0105] FIG. 6 is an example in which the i-th amplification unit adopts the forward pumping structure. In order to more clearly describe the amplification units, the three first amplification units 3133 in FIG. 6 are referred to as the S-band first amplification unit 31331, the E-band first amplification unit 31332, and the O-band first amplification unit 31333, respectively, and the three second amplification units 3233 are referred to as the C-band second amplification unit 32331, the L-band second amplification unit 32332, and the U-band second amplification unit 32333, respectively, to form a schematic diagram as shown in FIG. 8. The arrangement order of the six amplification units is the order of the S-band first amplification unit 31331, the E-band first amplification unit 31332, the O-band first amplification unit 31333, the C-band second amplification unit 32331, the L-band second amplification unit 32332, and the U-band second amplification unit 32333. Taking i equal to 2 as an example, the signal output end of the second amplification unit (i.e., the E-band first amplification unit 31332) is connected to the common end of the second wavelength division multiplexing component 5, and a 2*2 coupler is used as the first coupling component 6. The two output ends of the first coupling component 6 are connected to the pumping input end of the S-band first amplification unit 31331 and the pumping input end of the E-band first amplification unit 31332, respectively.

[0106] It should be noted that FIGS. 6 and 8 are only examples and do not mean that the common end of the second wavelength division multiplexing component 5 must be connected to the signal output end of the E-band first amplification unit 31332, or the output ends of the first coupling component 6 must be connected to the pumping input end of the S-band first amplification unit 31331 and the pumping input end of the E-band first amplification unit 31332. In other application scenarios, the common end of the second wavelength division multiplexing component 5 can be connected to the signal output end of the U-band second amplification unit 32333, and the two output ends of the first coupling component 6 can be connected to the pumping input end of the S-band first amplification unit 31331 and the pumping input end of the O-band first amplification unit 31333, as shown in FIG. 9.

[0107] In actual use, a signal transmission path where a signal output end of the corresponding amplification unit is located is also connected with an isolator 9 or a flat filter 10, specifically, the isolator 9 or the flat filter 10 is connected to a transmission end of the second wavelength division multiplexing component 5, that is, the transmission end of the second wavelength division multiplexing component 5 is also connected with the isolator 9 or the flat filter 10, as shown in FIG. 10 and FIG. 11.

[0108] In a preferred embodiment, as shown in FIG. 12, the amplifier further comprises a third wavelength division multiplexing component 11; a common end of the third wavelength division multiplexing component 11 is connected to a reflection end of the second wavelength division multiplexing component 5, a reflection end of the third wavelength division multiplexing component 11 is connected to a first input port of the first coupling component 6, and a transmission end of the third wavelength division multiplexing component 11 is idle and is subjected to anti-reflection treatment, such as being knotted around a small circle, to increase the isolation degree for signal light (also called signal wavelength light).

[0109] In other embodiments, a common end of a fourth wavelength division multiplexing component 12 can also be connected to a signal output end of the corresponding amplification unit, a transmission end of the fourth wavelength division multiplexing component 12 is coupled on a signal transmission path, and a reflection end of the fourth wavelength division multiplexing component 12 is connected to the corresponding amplification unit, as shown in FIG. 13, so as to transmit the pump leakage light of one amplification unit to the corresponding amplification unit for reuse.

[0110] In actual use, when the signal demand of the corresponding waveband is higher, the above-mentioned amplification units can also be connected in cascade, and the pump light supply mode among the amplification units can also adopt the above-mentioned modes, that is, three different pump light supply modes can be obtained by combining the above-mentioned modes:

[0111] The first mode is that the pump laser is directly connected to the pump input end of the corresponding doped fiber amplifier to provide pump light for the doped fiber amplifier.

[0112] The second mode is that a wavelength division multiplexing component is connected to the signal output end of the doped fiber amplifier, and a reflection end of the wavelength division multiplexing component is connected to the pump input end of the corresponding doped fiber amplifier, so as to use the pump leakage light to provide pump light for the doped fiber amplifier.

[0113] The third mode is that a wavelength division multiplexing component is connected to the signal output end of the doped fiber amplifier, a reflection end of the wavelength division multiplexing component is connected to a first input end of a coupling component, a second input end of the coupling component is connected to a pump laser, and an output end of the coupling component is connected to the pump input end of the corresponding doped fiber amplifier, so as to use the pump leakage light and the output of the pump laser to jointly provide pump light for the doped fiber amplifier.

[0114] The three supply modes can be applied to the same amplification unit simultaneously, and any first amplification unit 3133 is implemented by cascading multiple doped fiber amplifiers in sequence. For example, the structure of the first amplification unit 3133 is shown in FIG. 14. The first amplification unit 3133 includes M fiber amplification stages 131, which are cascaded in sequence. Each fiber amplification stage 131 is a doped fiber amplifier. In an optional embodiment, the first amplification unit 3133 further includes an optical switch 132, a fifth wavelength division multiplexing component 133, a second coupling component 134, a third fiber pumping component 135, a sixth wavelength division multiplexing component 136, a seventh wavelength division multiplexing component 137, and a fourth fiber pumping component 138.

[0115] The signal output end of the k-1th fiber amplification stage 131 is connected to the first port of the optical switch 132. The second port of the optical switch 132 is connected to the common port of the fifth wavelength division multiplexing component 133. The transmission end of the fifth wavelength division multiplexing component 133 is connected to the signal input end of the k+1th fiber amplification stage 131. The reflection end of the fifth wavelength division multiplexing component 133 is connected to the first input end of the second coupling component 134. The second input end of the second coupling component 134 is connected to the third fiber pumping component 135. The output end of the second coupling component 134 is connected to the corresponding erbium fiber amplification stage. In FIG. 14, the two output ends of the second coupling component 134 are respectively connected to the third erbium fiber amplification stage and the fourth erbium fiber amplification stage.

[0116] In addition, the sixth wavelength division multiplexing component 136 is connected between the fifth wavelength division multiplexing component 133 and the second coupling component 134. Specifically, the common end of the sixth wavelength division multiplexing component 136 is connected to the reflection end of the fifth wavelength division multiplexing component 133. The reflection end of the sixth wavelength division multiplexing component 136 is connected to the first input port of the second coupling component 134. The transmission end of the sixth wavelength division multiplexing component 136 is idle and is subjected to anti-reflection treatment, such as being tied in a small circle, to increase the isolation degree for signal light (also called signal wavelength light).

[0117] The third port of the optical switch 132 is connected to the common end of the seventh wavelength division multiplexing component 137. The transmission end of the seventh wavelength division multiplexing component 137 is connected to the signal input end of the kth fiber amplification stage 131. The fourth port of the optical switch 132 is connected to the signal output end of the kth fiber amplification stage 131.

[0118] The remaining fiber amplification stages 131 (including the first k-1th fiber amplification stage 131 and the fiber amplification stages 131 that are not connected to the output end of the second coupling component 134) are pumped by the fourth fiber pumping component 138.

[0119] As shown in Fig. 14, M is 4 and k is 2. When the optical switch 132 is adjusted to pass between the first port and the second port, only three optical fiber amplifier stages 131 are used in the optical path, i.e., the first optical fiber amplifier stage 131, the third optical fiber amplifier stage 131 and the fourth optical fiber amplifier stage 131 in Fig. 14. The fifth wavelength division multiplexing component 133 is used to separate the pump leakage light of the first optical fiber amplifier stage 131, and the pump leakage light of the first optical fiber amplifier stage 131 is transmitted to the third optical fiber amplifier stage 131 and the fourth optical fiber amplifier stage 131 through the second coupling component 134. When the optical switch 132 is adjusted to pass between the first port and the fourth port and pass between the second port and the third port, four optical fiber amplifier stages 131 are used in the optical path, i.e., the first optical fiber amplifier stage 131, the second optical fiber amplifier stage 131, the third optical fiber amplifier stage 131 and the fourth optical fiber amplifier stage 131 in Fig. 14. The seventh wavelength division multiplexing component 137 is used to separate the pump leakage light of the first optical fiber amplifier stage 131 for the second optical fiber amplifier stage 131. The fifth wavelength division multiplexing component 133 is used to separate the pump leakage light of the second optical fiber amplifier stage 131, and the pump leakage light of the second optical fiber amplifier stage 131 is transmitted to the third optical fiber amplifier stage 131 and the fourth optical fiber amplifier stage 131 through the second coupling component 134. k is less than N and greater than or equal to 2.

[0120] Embodiment 3:

[0121] Based on the amplifier described in embodiment 1, the application combines specific application scenarios and describes the implementation process in the specific scenario of the application by using technical expressions in the relevant scenario.

[0122] The embodiment takes the scene of amplifying full-band light containing O-band, E-band, S-band, C-band, L-band and U-band as an example, and provides a low-noise full-band optical fiber amplifier, as shown in FIG. 5, which comprises a far-end transmission optical fiber 4, a first wavelength division multiplexing component 1 (a wavelength division multiplexer in an actual application scene) for separating the full-band from the middle, a first ring component 311 (a circulator in an actual application scene) with a center wavelength of 13xx band for coupling the Raman pump light of 10xx, 12xx, 13xx and 14xx with overlapping parts of short sub-wavelength together, wherein the common port (port 2, i.e. the second port) of the first ring component 311 is connected with the reflection or transmission end of the first wavelength division multiplexing component 1, the port 1 (i.e. the first port) of the first ring component 311 is connected with the 10xx, 12xx, 13xx and 14xx Raman pump source (i.e. the first Raman pump component 312 in the embodiment 1), and the port 3 (i.e. the third port) of the first ring component 311 is connected with the common port of the first wave divider 31311, the first wave divider 31311 is used for separating the S-band amplifier from the O+E-band amplifier (actually separating the light of S-band from the light of O+E-band, and the separated light enters the corresponding amplifier respectively), the reflection or transmission end of the first wave divider 31311 enters the S-band amplifier, and the other port is connected with the common port of the second wave divider 31312, the second wave divider 31312 is used for separating the O-band amplifier from the E-band amplifier, the reflection or transmission end of the second wave divider 31312 enters the O-band amplifier, and the other port is connected with the E-band amplifier. The signal amplified by the O-band amplifier and the signal amplified by the E-band amplifier are combined by the first combiner 31321, and the O+E-band amplifier is formed, the signal amplified by the S-band amplifier and the O+E-band signal combined by the first combiner 31321 are combined by the second combiner 31322, and the S+O+E-band amplifier is formed.

[0123] The long wave part port of the first wavelength division multiplexing component 1 separating the full wave band from the middle part is connected to the second ring component 321, and the center wavelength of the second ring component 321 is 1550nm wave band. The common port (port 2, i.e. the second port) of the second ring component 321 is connected to the other port of the first wavelength division multiplexing component 1, the port 1 (the first port) of the second ring component 321 is connected to the 15xx Raman pump source (i.e. the second Raman pump component 322 in the embodiment 1), the port 3 (the third port) of the second ring component 321 is connected to the common port of the third splitter 32311, the third splitter 32311 is used to separate the C-band amplifier from the L+U wave band amplifier, the reflection end or the transmission end of the third splitter 32311 enters the C-band amplifier, and the other port is connected to the common port of the second amplification unit 3233, the second amplification unit 3233 is used to separate the L-band amplifier from the U-band amplifier, the reflection end or the transmission end of the second amplification unit 3233 enters the L-band amplifier, and the other port is connected to the U-band amplifier. The signal amplified by the C-band amplifier and the signal amplified by the L-band amplifier are combined by the third combiner 32321 to form a C+L wave band amplifier, and the signal amplified by the U-band amplifier and the C+L wave band signal combined by the third combiner 32321 are combined by the fourth combiner 32322 to form a C+L+U wave band amplifier. The S+O+E wave band amplifier and the C+L+U wave band amplifier are combined by the combining component 2 to form an O+E+S+C+L+U full wave band optical fiber amplifier.

[0124] In the actual application scene, the combining component 2, the first splitter 31311, the second splitter 31312, the third splitter 32311, the fourth splitter 32312, the first combiner 31321, the second combiner 31322, the third combiner 32321 and the fourth combiner 32322 are all wavelength division multiplexers.

[0125] In view of the different doped optical fiber gain media and more combining and splitting devices used in each sub-band of the full-band communication system, the noise figure of the full-band amplifier is relatively large. In order to effectively reduce the noise figure of the full-band amplifier, in the embodiment, firstly, the entire band is divided into two large bands in the combining and splitting mode, and then the small bands are divided in the two large bands. In this way, the insertion loss of each sub-band is relatively average. The combining and splitting is completed by the dielectric film filter. Then, by introducing the Raman pump wavelength and through the mixed distributed Raman fiber amplifier and doped fiber amplifier, the low-noise full-band fiber amplifier is realized. However, due to the wide band of the full-band amplifier, the Raman pump wavelength coincides with the sub-band signal wavelength, which causes great difficulty in the combining process. In the embodiment, the Raman pump wavelengths of each sub-band are integrated together as a unified Raman pump unit. Since the Raman pump wavelength coincides with the signal wavelength, the Raman pump wavelength is transmitted in the opposite direction of the signal. The Raman pump wavelength is coupled into the line through the circulator, so as not to affect the demodulation of the signal.

[0126] In the embodiment, the Raman pump light of each sub-band is integrated together. On the one hand, the combining of the same wavelength in different transmission directions can be realized through one circulator. On the other hand, the power of the corresponding Raman pump wavelength can be automatically adjusted through the signal power of each sub-band, so as to overcome the conflict between the full-band Raman pump wavelength and the signal wavelength, and realize the low-noise full-band fiber amplifier.

[0127] In an optional embodiment, as shown in FIG. 15, the amplifier further includes a microcontroller unit (MCU), which is connected with the control ends of the amplification units. The MCU adjusts the pump power and the Raman pump power of each amplification unit according to the input conditions of each sub-band amplifier.

[0128] On the basis of the above-mentioned embodiments, the embodiment further provides a signal transmission system using the above-mentioned low-noise full-band fiber amplifier for signal amplification. As shown in FIG. 16, the signal transmission system can include optical transmitters (Tx 1, Tx 2, …, Tx N in FIG. 16), an optical multiplexer (OM in FIG. 16), the above-mentioned low-noise full-band fiber amplifier (OA in FIG. 16), an optical demultiplexer (OD in FIG. 16), and optical receivers (Rx 1, Rx 2, …, Rx N in FIG. 16) connected in sequence.

[0129] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A low-noise all-band optical fiber amplifier, characterized by, The first wavelength division multiplexing component (1), a combining component (2), a first gain module (31) and a second gain module (32); The first gain module (31) is connected between the transmission end of the first wavelength division multiplexing component (1) and the first input end of the combining component (2), and the second gain module (32) is connected between the reflection end of the first wavelength division multiplexing component (1) and the second input end of the combining component (2); the common end of the first wavelength division multiplexing component (1) is a signal input end; and the output end of the combining component (2) is a signal output end; The first wavelength division multiplexing component (1) is used for dividing the full-band light from the signal input end to obtain first half-band light and second half-band light; The first gain module (31) is used for forward doped fiber amplification and backward Raman amplification of the first half-band light to obtain first half-band gain signals; and the second gain module (32) is used for forward doped fiber amplification and backward Raman amplification of the second half-band light to obtain second half-band gain signals; The combining component (2) is used for combining the first half-band gain signals and the second half-band gain signals to obtain full-band gain signals.

2. The low noise all-band optical fiber amplifier according to claim 1, characterized by, The first gain module (31) comprises a first ring component (311), a first Raman pump component (312) and a first amplification component (313); The first port of the first ring component (311) is connected with the first Raman pump component (312), the second port of the first ring component (311) is the input end of the first gain module (31), the third port of the first ring component (311) is connected with the signal input end of the first amplification component (313), and the signal output end of the first amplification component (313) is the output end of the first gain module (31); The first ring component (311) is used for transmitting the first half-band light forwardly to the first amplification component (313), and the first amplification component (313) is used for amplifying the first half-band light by doped fiber; The first Raman pump component (312) is used for outputting first Raman light matched with the first half-band light; The first ring component (311) is also used for transmitting the first Raman light reversely to the transmission end of the first wavelength division multiplexing component (1), so that the first wavelength division multiplexing component (1) combines the first Raman light and second Raman light to obtain full Raman light, and reversely transmits the full Raman light to the far-end transmission optical fiber (4) located at the signal input end, so that the full-band light is amplified by the full Raman light in the far-end transmission optical fiber (4).

3. The low noise, all-band optical fiber amplifier of claim 2, wherein, The first amplification component (313) comprises a first splitting unit (3131), a first combining unit (3132) and a plurality of first amplification units (3133); The input end of the first splitting unit (3131) is the signal input end of the first amplification component (313); A first amplification unit (3133) is connected between each output end of the first splitting unit (3131) and a corresponding input end of a first combining unit (3132); The first splitting unit (3131) is configured to split the first half-waveband light to obtain a plurality of sub-waveband lights, the first amplification unit (3133) is configured to perform forward doped fiber amplification on the corresponding sub-waveband light to obtain a sub-waveband gain signal, and the first combining unit (3132) is configured to combine the plurality of sub-waveband gain signals to obtain a first half-waveband gain signal.

4. The low noise, all-band optical fiber amplifier as claimed in claim 3, wherein, When the fiber amplifier comprises N amplification units, the fiber amplifier further comprises a second wavelength division multiplexing assembly (5), a first coupling assembly (6), and a first fiber pump assembly (7); The common end of the second wavelength division multiplexing assembly (5) is connected to the signal output end of the i-th amplification unit, the transmission end of the second wavelength division multiplexing assembly (5) is coupled on the signal transmission path, and the reflection end of the second wavelength division multiplexing assembly (5) is connected to the first input port of the first coupling assembly (6); The first fiber pump assembly (7) is connected to the second input port of the first coupling assembly (6), and each output port of the first coupling assembly (6) is connected to the pump input end of the corresponding amplification unit; The first fiber pump assembly (7) is configured to generate pump light. The second wavelength division multiplexing assembly (5) is configured to split the output light of the i-th amplification unit to obtain signal light and pump leakage light, so that the signal light continues to transmit on the signal transmission path, and the pump leakage light is transmitted to the first coupling assembly (6); The first coupling assembly (6) is configured to couple and transmit the pump light and the pump leakage light to the pump input end of the corresponding amplification unit, so as to guide the pump leakage light of the i-th amplification unit to the corresponding amplification unit for optical amplification; wherein the amplification unit is the first amplification unit (3133) and / or the second amplification unit (3233).

5. The low noise, all-band optical fiber amplifier of claim 4, wherein, The transmission end of the second wavelength division multiplexing assembly (5) is further connected with an isolator (9) or a flat filter (10).

6. The low noise, all-band optical fiber amplifier of claim 3, wherein, The first splitting unit (3131) comprises a plurality of cascaded splitters.

7. The low noise, all-band optical fiber amplifier of claim 6, wherein, When the full-waveband light comprises six waveband lights, the first splitting unit (3131) comprises two cascaded splitters, i.e., a first splitter (31311) and a second splitter (31312); The first output end of the first splitter (31311) is connected to the input end of the second splitter (31312); The input end of the first splitter (31311) is the input end of the first splitting unit (3131), the second output end of the first splitter (31311), the first output end of the second splitter (31312), and the second output end of the second splitter (31312) are the output ends of the first splitting unit (3131); The first splitter (31311) is configured to split the first half-waveband light into a first sub-waveband light and a residual waveband light, and the second splitter (31312) is configured to split the residual waveband light into a second sub-waveband light and a third sub-waveband light.

8. The low noise, all-band optical fiber amplifier of claim 3, wherein, The first combining unit (3132) comprises a plurality of combiners connected in cascade.

9. The low noise, all-band optical fiber amplifier of claim 8, wherein, When the full-waveband light comprises six waveband lights, the first combining unit (3132) comprises two combiners connected in cascade, namely a first combiner (31321) and a second combiner (31322). The output end of the first combiner (31321) is connected to the first input end of the second combiner (31322). The first input end of the first combiner (31321), the second input end of the first combiner (31321) and the second input end of the second combiner (31322) are input ends of the first combining unit (3132), and the output end of the second combiner (31322) is an output end of the first combining unit (3132). The first combiner (31321) is configured to combine the first sub-waveband gain signal and the second sub-waveband gain signal to obtain a partial waveband gain signal, and the second combiner (31322) is configured to combine the partial waveband gain signal and the third sub-waveband gain signal to obtain the first half-waveband gain signal.

10. The low noise, all-band optical fiber amplifier of claim 3, wherein, The first amplifying unit (3133) is an erbium-doped fiber amplifier or a bismuth-doped fiber amplifier.

11. The low noise, all-band optical fiber amplifier of claim 2, wherein, The first ring assembly (311) is an optical circulator.

12. The low noise, all-band optical fiber amplifier of claim 1, wherein, The second gain module (32) comprises a second ring assembly (321), a second Raman pump assembly (322) and a second amplifying assembly (323). The first port of the second ring assembly (321) is connected to the second Raman pump assembly (322), the second port of the second ring assembly (321) is an input end of the second gain module (32), the third port of the second ring assembly (321) is connected to the signal input end of the second amplifying assembly (323), and the signal output end of the second amplifying assembly (323) is an output end of the second gain module (32). The second ring assembly (321) is configured to forward transmit the second half-waveband light to the second amplifying assembly (323), and the second amplifying assembly (323) is configured to amplify the second half-waveband light by using a doped optical fiber. The second Raman pump assembly (322) is configured to output a second Raman light matched with the second half-waveband light. The second ring assembly (321) is further configured to backward transmit the second Raman light to the reflection end of the first wavelength division multiplexer (1).

13. The low noise, all-band optical fiber amplifier of claim 12, wherein, The second ring assembly (321) is an optical circulator.

14. The low noise all-band optical fiber amplifier as claimed in any one of claims 1 to 13, characterized in that, The full-waveband light comprises one or more of O waveband, E waveband, S waveband, C waveband, L waveband and U waveband, the first half-waveband light comprises O waveband, E waveband and S waveband, and the second half-waveband light comprises C waveband, L waveband and U waveband.

15. The low noise all-band optical fiber amplifier as claimed in any one of claims 1 to 13, wherein, The first wavelength division multiplexer (1) is a wavelength division multiplexer.

16. The low noise all-band optical fiber amplifier as claimed in any one of claims 1 to 13, wherein, The multiplexing assembly (2) is a wavelength division multiplexer.

17. A signal transmission system, characterized by Signal amplification is performed using the low-noise full-band optical fiber amplifier according to any one of claims 1-16.

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