A remote gain unit, loss detection method and a remote pumping transmission system

Abstract

The present application relates to the technical field of optical communication, in particular to a remote gain unit, an attenuation detection method and a remote pumping transmission system, the present application separates and transmits the measuring light and the signal light through corresponding optical path design, so as to realize the transmission of the measuring light skipping the amplification optical fiber, and avoid the absorption of the measuring light by the amplification optical fiber, which can be used for the direct measurement of the cable span loss in the remote pumping transmission system, and is applicable to the measuring light of any wavelength, completely solves the problem that the span loss in the remote pumping transmission system cannot be directly measured, and provides great help for the operation and maintenance of the remote pumping transmission system.

Description

Technical Field

[0001] This invention relates to the field of optical communication technology, and in particular to a remote gain unit, an attenuation detection method, and a remote pumping transmission system. Background Technology

[0002] With the development of science and technology and communication technology, ultra-long-distance repeaterless transmission systems are increasingly used in ocean communication, island communication, and power communication. Remote pumping transmission technology is one of the most common optical amplification technologies in repeaterless communication systems. Because remote pumping transmission technology can greatly increase the repeaterless transmission distance, it is widely used in ultra-long-distance repeaterless transmission systems. A remote pumping system consists of a remote pumping unit and a remote gain unit. The remote gain unit contains erbium-doped fiber. Since erbium-doped fiber has significant loss without pump light excitation, the optical signal cannot pass through the remote gain unit without pumping. Therefore, in remote pumping transmission systems, optical cable loss is measured in two sections: before and after the remote gain unit. However, in practical applications, because the remote gain unit is placed in the middle of the line and already connected to the optical cable, the two-section measurement method is not feasible. Therefore, existing remote pumping transmission systems cannot accurately measure the loss of the entire system's transmission optical cable.

[0003] Therefore, overcoming the shortcomings of the existing technology is an urgent problem to be solved in this technical field. Summary of the Invention

[0004] The technical problem to be solved by this invention is how to solve the problem that existing remote pumping transmission systems cannot perform full-link optical cable cross-loss measurement after operation.

[0005] The present invention adopts the following technical solution:

[0006] In a first aspect, a remote gain unit is provided, which is suitable for a remote pumping transmission system and includes: a first circulator 1, a first wavelength division multiplexer 2, an amplifying optical fiber 3, a second circulator 4, and a second wavelength division multiplexer 5.

[0007] The first port of the first circulator 1 is connected to the input terminal of the remote gain unit, the second port of the first circulator 1 is connected to the transmission terminal of the first wavelength division multiplexer 2, and the third port of the first circulator 1 is connected to the transmission terminal of the second wavelength division multiplexer 5.

[0008] The reflecting end of the first wavelength division multiplexer 2 is connected to the reflecting end of the second wavelength division multiplexer 5, and the common end of the first wavelength division multiplexer 2 is connected to one end of the amplifying optical fiber 3; the first port of the second circulator 4 is connected to the other end of the amplifying optical fiber 3, the second port of the second circulator 4 is connected to the output end of the remote gain unit, and the third port of the second circulator 4 is connected to the common end of the second wavelength division multiplexer 5.

[0009] The second wavelength division multiplexer 5 is used to transmit the pump light from the output of the remote gain unit to the first wavelength division multiplexer 2; it is also used to transmit the measurement light from the output of the remote gain unit to the first circulator 1 so that the measurement light bypasses the amplifying fiber 3.

[0010] Preferably, the remote gain unit further includes a reflector 6, which is disposed between the other end of the amplifying fiber 3 and the first port of the second circulator 4; the reflector 6 is used to reflect the pump light from the amplifying fiber 3 to improve the utilization efficiency of the pump light.

[0011] Preferably, the center wavelength of the reflector 6 is in the range of 1450nm-1650nm.

[0012] Preferably, when the wavelengths of the signal light and the measurement light are unchangeable and the wavelength difference between the signal light and the measurement light is greater than 40 nm, the first circulator 1 is replaced by the third wavelength division multiplexer 7;

[0013] The transmission end of the third wavelength division multiplexer 7 is connected to the input end of the remote gain unit, the common end of the third wavelength division multiplexer 7 is connected to the transmission end of the first wavelength division multiplexer 2, and the reflection end of the third wavelength division multiplexer 7 is connected to the transmission end of the second wavelength division multiplexer 5.

[0014] The third wavelength division multiplexer 7 is used to receive signal light from the outside and transmit the signal light to the first wavelength division multiplexer 2;

[0015] The third wavelength division multiplexer 7 is also used to transmit the measurement light to the input of the remote gain unit to measure the fiber attenuation in the remote pumping transmission system based on the measurement light.

[0016] Preferably, the amplifying optical fiber 3 is an erbium-doped optical fiber, a praseodymium-doped optical fiber, or a rubidium-doped optical fiber.

[0017] Preferably, the wavelength range of the transmission end of the first wavelength division multiplexer 2 and the second wavelength division multiplexer 5 is 1525nm to 1560nm; the wavelength range of the reflection end of the first wavelength division multiplexer 2 and the second wavelength division multiplexer 5 is 1450nm to 1500nm.

[0018] Preferably, the isolation between each port on the first circulator 1 and the second circulator 4 is greater than or equal to 50dB, and the insertion loss between each port is less than or equal to 0.5dB.

[0019] In a second aspect, an attenuation detection method is provided, the method being applicable to a remote gain unit as described in the first aspect, the attenuation detection method comprising:

[0020] When the pump light is input from the output of the remote gain unit, the first circulator 1 receives the signal light from the outside and transmits the signal light to the first wavelength division multiplexer 2;

[0021] The second circulator 4 receives pump light and measurement light from the output of the remote gain unit and transmits the pump light and measurement light to the second wavelength division multiplexer 5. The second wavelength division multiplexer 5 transmits the pump light to the first wavelength division multiplexer 2 and the measurement light to the first circulator 1.

[0022] When the pump light is input from the input terminal of the remote gain unit, the first circulator 1 receives the signal light and the pump light, and transmits the signal light and the pump light to the first wavelength division multiplexer 2;

[0023] The first wavelength division multiplexer 2 transmits the signal light and the pump light to the amplifying fiber 3 to amplify the signal light, and the second circulator 4 transmits the amplified signal light to the output of the remote gain unit;

[0024] The first circulator 1 transmits the measurement light to the input of the remote gain unit to measure the fiber attenuation in the remote pumping transmission system based on the measurement light.

[0025] Thirdly, a remote pumping transmission system is provided, comprising a remote gain unit, a detection unit, and a pumping unit as described in the first aspect; the pumping unit is connected to the input or output of the remote gain unit; the detection unit is connected to the input of the remote gain unit.

[0026] When the pump unit is connected to the output of the remote gain unit, the pump unit is used to emit the pump light. The pump light passes through the second circulator 4, the second wavelength division multiplexer 5 and the first wavelength division multiplexer 2 in sequence and is transmitted together with the signal light to the amplifying fiber 3 to amplify the signal light.

[0027] The detection unit is used to receive measurement light from the input of the remote gain unit and to obtain the fiber attenuation in the remote pumping transmission system based on the measurement light.

[0028] Preferably, when the pump unit is connected to the input terminal of the remote gain unit, the pump unit is used to emit the pump light. The pump light and the signal light are simultaneously input to the input terminal of the remote gain unit. The pump light and the signal light pass through the first circulator 1 and the first wavelength division multiplexer 2 in sequence, and then are input together into the amplifying fiber 3 to amplify the signal light.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] This invention separates the measurement light from the signal light through appropriate optical path design, thereby enabling the measurement light to bypass the amplifying fiber 3 for transmission. This avoids the absorption of the measurement light by the amplifying fiber 3, which can be used not only for the direct measurement of optical cable cross-loss in remote pumping transmission systems, but also for measurement light of any wavelength. It completely solves the problem that cross-loss cannot be directly measured in remote pumping transmission systems, and provides great assistance for the operation and maintenance of remote pumping transmission systems. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the structure of a remote gain unit provided in an embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of the optical path transmission of a remote gain unit provided in an embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of another optical path transmission for a remote gain unit provided in an embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of a specific structure of a remote gain unit provided in an embodiment of the present invention;

[0036] Figure 5 This is a schematic diagram of another structure of a remote gain unit provided in an embodiment of the present invention;

[0037] Figure 6 This is a schematic flowchart of a decay detection method provided in an embodiment of the present invention;

[0038] Figure 7 This is a schematic diagram of the structure of a remote pumping transmission system provided in an embodiment of the present invention;

[0039] Figure 8 This is a schematic diagram of another structure of a remote pumping transmission system provided in an embodiment of the present invention;

[0040] Figure 9 This is a schematic diagram of a specific structure of a remote pumping transmission system provided in an embodiment of the present invention;

[0041] Figure 10 This is a schematic diagram of another specific structure of a remote pumping transmission system provided in an embodiment of the present invention.

[0042] In all the accompanying drawings, the same reference numerals denote the same structure, wherein:

[0043] First circulator 1, first wavelength division multiplexer 2, amplifying fiber 3, second circulator 4, second wavelength division multiplexer 5, reflector 6, third wavelength division multiplexer 7, fourth wavelength division multiplexer 8, fifth wavelength division multiplexer 9. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0045] Unless the context otherwise requires, throughout the specification and claims, the term "comprising" is interpreted as openly inclusive, meaning "including, but not limited to." In the description of the specification, terms such as "one embodiment," "some embodiments," "exemplary embodiment," "example," "specific example," or "some examples" are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this disclosure. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics mentioned may be included in any suitable manner in any one or more embodiments or examples; that is, although they may be incorporated into embodiments or examples using the above terms for reasons such as order and position, it does not limit them to be incorporated in combination by a single embodiment or example.

[0046] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this disclosure, unless otherwise stated, "a plurality of" means two or more. Furthermore, for example, the description may use the prefix "A" or "B" to describe the same type of nouns as two independent entities. In this case, the corresponding features defined with "A" and "B" are used only to distinguish between similar entities and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features.

[0047] In describing some embodiments, the terms "coupled," "coupled," and "connected," and their derivative expressions, may be used. For example, the term "connected" may be used in describing some embodiments to indicate that two or more components have direct physical or electrical contact with each other. Similarly, the term "coupled" may be used in describing some embodiments to indicate that two or more components have direct physical or electrical contact. However, the terms "connected" or "coupled" may also refer to two or more components that do not have direct contact with each other but still cooperate or interact with each other, such as "optical coupling," "wireless connection," etc. The embodiments disclosed herein are not necessarily limited to the scope of this invention.

[0048] Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0049] Example 1:

[0050] In remote pumping transmission systems, due to the long communication distance and the inability of optical signals to pass through remote gain units without pump light, the detection of fiber attenuation in remote pumping transmission systems becomes complex. It is usually divided into front-end detection of doped fiber and back-end detection of doped fiber. However, in actual situations, remote gain units have already been connected to optical cables. Therefore, the method of detection in two segments is not applicable in practical application scenarios.

[0051] To address the aforementioned problems, this embodiment provides a remote gain unit, such as... Figure 1As shown, the remote gain unit is suitable for a remote pumping transmission system and includes: a first circulator 1, a first wavelength division multiplexer 2, an amplifying fiber 3, a second circulator 4, and a second wavelength division multiplexer 5; the first port 1b of the first circulator 1 is connected to the input terminal In of the remote gain unit, the second port 1c of the first circulator 1 is connected to the transmission terminal 2a of the first wavelength division multiplexer 2, and the third port 1a of the first circulator 1 is connected to the transmission terminal 5a of the second wavelength division multiplexer 5; the reflection terminal 2c of the first wavelength division multiplexer 2 is connected to the reflection terminal 5c of the second wavelength division multiplexer 5, and the first wavelength division multiplexer 2... The common terminal 2b is connected to one end of the amplifying optical fiber 3; the first port 4a of the second circulator 4 is connected to the other end of the amplifying optical fiber 3, the second port 4b of the second circulator 4 is connected to the output terminal Out of the remote gain unit, and the third port 4c of the second circulator 4 is connected to the common terminal 5b of the second wavelength division multiplexer 5; the second wavelength division multiplexer 5 is used to transmit the pump light from the output terminal of the remote gain unit to the first wavelength division multiplexer 2; it is also used to transmit the measurement light from the output terminal of the remote gain unit to the first circulator 1 so that the measurement light bypasses the amplifying optical fiber 3.

[0052] The first circulator 1 and the second circulator 4 are both three-port circulators, which can only turn light waves in two directions. The isolation between each port on the first circulator 1 and the second circulator 4 is greater than or equal to 50dB, and the insertion loss between each port is less than or equal to 0.5dB.

[0053] In one embodiment, the wavelength range of the transmission ends of the first wavelength division multiplexer 2 and the second wavelength division multiplexer 5 is 1525nm to 1560nm; the wavelength range of the reflection ends of the first wavelength division multiplexer 2 and the second wavelength division multiplexer 5 is 1450nm to 1500nm.

[0054] In one embodiment, the pump light used to excite the amplifying fiber 3 can be sourced from two sources, such as... Figure 2As shown, the first approach involves the pump light and signal light being transmitted via different fibers. That is, when the pump light is input from the output of the remote gain unit, the first circulator 1 receives the signal light from the outside and transmits the signal light to the first wavelength division multiplexer 2; the second circulator 4 receives the pump light and measurement light from the output of the remote gain unit and transmits the pump light and measurement light to the second wavelength division multiplexer 5. The second wavelength division multiplexer 5 transmits the pump light to the first wavelength division multiplexer 2 and also transmits the measurement light to the first circulator 1. The specific transmission path of the pump light at this time is as follows: the pump light is input through the second port 4b of the second circulator 4, then transmitted through the third port 4c of the second circulator 4 to the common port 5b of the second wavelength division multiplexer 5, then transmitted through the reflection port 5c of the second wavelength division multiplexer 5 to the reflection port 2c of the first wavelength division multiplexer 2, and finally transmitted through the common port 2b of the second wavelength division multiplexer 5 to the amplifying fiber 3 to amplify the signal light from the first circulator 1.

[0055] Another transmission path for the pump light is co-fiber transmission with the signal light, such as... Figure 3 As shown, when the pump light is input from the input terminal of the remote gain unit, the first circulator 1 receives the signal light and the pump light, and transmits the signal light and the pump light to the first wavelength division multiplexer 2; the first wavelength division multiplexer 2 transmits the signal light and the pump light to the amplifying fiber 3 to amplify the signal light; the second circulator 4 transmits the amplified signal light to the output terminal of the remote gain unit; the first circulator 1 also transmits the measurement light to the input terminal of the remote gain unit to measure the fiber attenuation in the remote pumping transmission system based on the measurement light.

[0056] In this second transmission path, the pump light is input from the input terminal of the remote gain unit, transmitted from the first port 1b of the first circulator 1 to the second port 1c of the first circulator 1, then input into the first wavelength division multiplexer 2 via the transmission terminal 2a, and finally transmitted from the common terminal 2b of the first wavelength division multiplexer 2 to the amplifying fiber 3 to amplify the signal light from the first circulator 1. Compared to the first transmission path, in this second transmission path, the pump light and signal light are transmitted in the same fiber. Besides the amplifying fiber 3 amplifying the signal light, the pump light also provides some Raman amplification to the signal light. In the first transmission path, the pump light and signal light are on different fibers, so there is no Raman amplification of the signal light. However, the pump light and signal light do not interfere with each other, which is beneficial for increasing the effective transmission distance of the high-power pump light.

[0057] In one embodiment, such as Figure 4 As shown, the remote gain unit also includes a reflector 6, which is disposed between the other end of the amplifying fiber 3 and the first port of the second circulator 4; the reflector 6 is used to reflect the pump light from the amplifying fiber 3 to improve the utilization efficiency of the pump light.

[0058] The pump light is used to amplify the signal light in the amplifying fiber 3. However, due to insertion loss and other non-ideal factors in the amplifying fiber 3, some pump light is always lost during amplification. This problem can be partially solved by placing a reflector 6 at the other end of the amplifying fiber 3. The reflector 6 reflects the excess pump light back, allowing more pump light energy to be reused for further amplification of the signal light. In one embodiment, the center wavelength of the reflector 6 is in the range of 1450nm-1650nm. Specifically, the process is roughly as follows:

[0059] In one embodiment, the amplifying fiber 3 is an erbium-doped fiber, a praseodymium-doped fiber, or a rubidium-doped fiber. The doping particles (such as erbium or thulium) in the amplifying fiber 3 absorb the energy of the pump light and convert it into the energy of the signal light, thereby amplifying the signal light. The amplified signal light propagates together with the remaining pump light. When the signal light and pump light reach the other end of the amplifying fiber 3, the excess pump light is reflected back by the reflector 6. The reflected pump light can pass through the amplifying fiber 3 again, further enhancing the amplification effect of the signal light. In this way, the reflector 6 helps to improve the utilization rate of the pump light, thereby improving the performance of the entire remote pumping transmission system.

[0060] In one embodiment, such as Figure 5As shown, the measurement light supports full-band wavelengths and allows the measurement light and signal light to have the same wavelength. When the wavelength of the signal light changes, in order to accurately measure the optical cable loss value in the remote pumping transmission system at the corresponding signal light wavelength, it is necessary to use a measurement light with the same wavelength as the signal light to test the optical cable loss of the remote pumping transmission system. The remote gain unit can support the passage of probe light of different wavelengths, and there is a special scenario where the requirements for the measurement results are not high, that is, when the wavelengths of the signal light and the measurement light cannot be changed and the wavelength difference between the signal light and the measurement light is greater than 40nm, the first circulator 1 is replaced by the third wavelength division multiplexer 7. The transmission end 7b of the third wavelength division multiplexer 7 is connected to the input end In of the remote gain unit; the common end 7c of the third wavelength division multiplexer 7 is connected to the transmission end 2a of the first wavelength division multiplexer 2; and the reflection end 7a of the third wavelength division multiplexer 7 is connected to the transmission end 5a of the second wavelength division multiplexer 5. The third wavelength division multiplexer 7 is used to receive signal light from the outside and transmit the signal light to the first wavelength division multiplexer 2. The third wavelength division multiplexer 7 is also used to transmit the measurement light to the input end of the remote gain unit to measure the fiber attenuation in the remote pumping transmission system based on the measurement light.

[0061] This embodiment separates the measurement light from the signal light through appropriate optical path design, thereby enabling the measurement light to bypass the amplifying fiber 3 for transmission. This avoids the absorption of the measurement light by the amplifying fiber 3, which can be used not only for the direct measurement of optical cable cross-loss in remote pumping transmission systems, but also for measurement light of any wavelength. It completely solves the problem that cross-loss cannot be directly measured in remote pumping transmission systems, and provides great assistance for the operation and maintenance of remote pumping transmission systems.

[0062] Example 2:

[0063] In Example 1, a remote gain unit was proposed. In this example, an attenuation detection method will be proposed. This method is applicable to the remote gain unit as described in Example 1, such as... Figure 6 As shown, the attenuation detection method includes:

[0064] Step 101: When the pump light is input from the output of the remote gain unit, the first circulator 1 receives the signal light from the outside and transmits the signal light to the first wavelength division multiplexer 2.

[0065] Among them, reference Figure 2The specific transmission path of the pump light at this time is as follows: the pump light is input through the second port 4b of the second circulator 4, then transmitted through the third port 4c of the second circulator 4 to the common port 5b of the second wavelength division multiplexer 5, then transmitted through the reflection port 5c of the second wavelength division multiplexer 5 to the reflection port 2c of the first wavelength division multiplexer 2, and finally transmitted through the common port 2b of the second wavelength division multiplexer 5 to the amplifying fiber 3 to amplify the signal light from the first circulator 1. The signal light is input through the input port In of the remote gain unit to the first port 1b of the first circulator 1, and then transmitted through the second port 1c of the first circulator 1 to the transmission port 2a of the first wavelength division multiplexer 2.

[0066] Step 102: The second circulator 4 receives the pump light and measurement light from the output of the remote gain unit, and transmits the pump light and measurement light to the second wavelength division multiplexer 5. The second wavelength division multiplexer 5 transmits the pump light to the first wavelength division multiplexer 2, and the second wavelength division multiplexer 5 transmits the measurement light to the first circulator 1.

[0067] Specifically, the second port 4b of the second circulator 4 receives pump light and measurement light from the output of the remote gain unit, and transmits the pump light and measurement light to the common port 5b of the second wavelength division multiplexer 5 through the third port 4c of the second circulator 4. The measurement light is then transmitted to the third port 1a of the first circulator 1 through the transmission port 5a of the second wavelength division multiplexer 5, and the pump light is transmitted to the reflection port 2c of the first wavelength division multiplexer 2 through the reflection port 5c of the second wavelength division multiplexer 5.

[0068] Step 103: When the pump light is input from the input terminal of the remote gain unit, the first circulator 1 receives the signal light and the pump light, and transmits the signal light and the pump light to the first wavelength division multiplexer 2. The first wavelength division multiplexer 2 transmits the signal light and the pump light to the amplifying fiber 3 to amplify the signal light. The second circulator 4 transmits the amplified signal light to the output terminal of the remote gain unit.

[0069] Reference Figure 3In this case, the specific transmission path of the pump light is as follows: the pump light is input from the input terminal of the remote gain unit, transmitted from the first port 1b of the first circulator 1 to the second port 1c of the first circulator 1, then input into the first wavelength division multiplexer 2 through the transmission terminal 2a, and finally transmitted from the common terminal 2b of the first wavelength division multiplexer 2 to the amplifying fiber 3 to amplify the signal light from the first circulator 1. Compared with the first transmission path of the pump light, in the second transmission path, the pump light and the signal light are transmitted in the same fiber. In addition to the amplifying fiber 3 amplifying the signal light, the pump light also plays a certain role in Raman amplification of the signal light. For the first transmission path, the pump light and the signal light are on different fibers, so there is no Raman amplification effect on the signal light. However, the pump light and the signal light do not interfere with each other, which is beneficial to improving the effective transmission distance of the high-power pump light.

[0070] In this process, both the pump light from the input end of the remote gain unit and the pump light from the output end of the remote gain unit are input into the amplifying fiber 3 to amplify the signal light.

[0071] Step 104: The first circulator 1 transmits the measurement light to the input of the remote gain unit to measure the fiber attenuation in the remote pumping transmission system based on the measurement light.

[0072] After the measurement light is received at the third port 1a of the first circulator 1, the measurement light is transmitted to the external detection unit by the first port 1b of the first circulator 1 and the remote gain unit to measure the fiber attenuation in the remote pumping transmission system.

[0073] For the specific structure of the remote gain unit, please refer to Embodiment 1, which will not be repeated in this embodiment.

[0074] Example 3:

[0075] In Example 1, a remote gain unit was proposed. In this example, a remote pumping transmission system will be proposed, such as... Figure 7 and Figure 8 As shown, it includes a remote gain unit (RGU), a detection unit, and a pump unit (RPU) as described in Embodiment 1; the pump unit is connected to the input or output of the remote gain unit; the detection unit is connected to the input of the remote gain unit.

[0076] In one embodiment, such as Figure 7 and Figure 9As shown, when the pump unit is connected to the output of the remote gain unit, the pump unit emits the pump light, which is transmitted to the amplifying fiber 3 along with the signal light after passing through the second circulator 4, the second wavelength division multiplexer 5, and the first wavelength division multiplexer 2 in sequence, so as to amplify the signal light; the detection unit receives the measurement light from the input of the remote gain unit and obtains the fiber attenuation in the remote pumping transmission system based on the measurement light.

[0077] The detection unit is located at the TX end of the remote pump transmission system.

[0078] Since the measurement light and pump light come from different light sources, the measurement light needs to bypass the pump unit. In one embodiment, the remote pumping transmission system further includes a fourth wavelength division multiplexer 8 and a fifth wavelength division multiplexer 9. When the pump unit is connected to the output of the remote gain unit, the common terminal 8b of the fourth wavelength division multiplexer 8 is connected to the input of the pump unit, the common terminal 9b of the fifth wavelength division multiplexer 9 is connected to the output of the pump unit, the transmission terminal 8a of the fourth wavelength division multiplexer 8 is connected to the RX terminal of the remote pumping transmission system, the transmission terminal 9a of the fifth wavelength division multiplexer 9 is connected to the output of the remote gain unit, and the reflection terminal 8c of the fourth wavelength division multiplexer 8 and the reflection terminal 9c of the fifth wavelength division multiplexer 9 are connected.

[0079] The transmission end 8a of the fourth wavelength division multiplexer 8 is used to receive the measurement light from the RX end of the remote pumping transmission system. The reflection end 8c of the fourth wavelength division multiplexer 8 is used to transmit the measurement light to the reflection end 9c of the fifth wavelength division multiplexer 9, and then the measurement light is transmitted to the output end of the remote gain unit through the transmission end 9a of the fifth wavelength division multiplexer 9. After passing through the remote gain unit, the measurement light is transmitted to the TX end of the remote pumping transmission system for detection.

[0080] The pump unit is used to output pump light and output the pump light to the common terminal 9b of the fifth wavelength division multiplexer 9. Finally, the pump light is transmitted to the output terminal of the remote gain unit through the transmission terminal 9a of the fifth wavelength division multiplexer 9.

[0081] In one embodiment, such as Figure 8 and Figure 10 As shown, when the pump unit is connected to the input terminal of the remote gain unit, the pump unit is used to emit the pump light. The pump light and the signal light are simultaneously input to the input terminal of the remote gain unit. The pump light and the signal light pass through the first circulator 1 and the first wavelength division multiplexer 2 in sequence, and then are input together into the amplifying fiber 3 to amplify the signal light.

[0082] At this point, the positions of the fourth wavelength division multiplexer 8, the fifth wavelength division multiplexer 9, and the pump unit change. The measurement light has now passed through the remote gain unit and is output from its input. The common terminal 8b of the fourth wavelength division multiplexer 8 is connected to the input of the pump unit, the common terminal 9b of the fifth wavelength division multiplexer 9 is connected to the output of the pump unit, the transmission terminal 8a of the fourth wavelength division multiplexer 8 is connected to the TX terminal of the remote pumping transmission system, the transmission terminal 9a of the fifth wavelength division multiplexer 9 is connected to the input of the remote gain unit, and the reflection terminal 8c of the fourth wavelength division multiplexer 8 is connected to the reflection terminal 9c of the fifth wavelength division multiplexer 9.

[0083] The transmission end 9a of the fifth wavelength division multiplexer 9 is used to receive the measurement light from the input end of the remote gain unit. The reflection end 9c of the fifth wavelength division multiplexer 9 is used to transmit the measurement light to the reflection end 8c of the fourth wavelength division multiplexer 8. Then, the measurement light is transmitted to the TX end of the remote pumping transmission system for detection through the transmission end 8a of the fourth wavelength division multiplexer 8.

[0084] At this time, the pump unit is used to output pump light and output the pump light to the common terminal 9b of the fifth wavelength division multiplexer 9. Finally, the pump light is transmitted to the input terminal of the remote gain unit through the transmission terminal 9a of the fifth wavelength division multiplexer 9.

[0085] Specifically, after the remote pumping transmission system is completed and put into operation, if service performance deteriorates, a high-power measurement light of known power can be sent directly to the RX end of the remote pumping system. The power of the measurement light can be detected at the TX end of the remote pumping transmission system, thereby measuring the fiber loss value in the remote pumping transmission system. The measured value is compared with the design value to determine whether the fiber link has deteriorated.

[0086] For the specific structure of the remote gain unit, please refer to Embodiment 1, which will not be repeated in this embodiment.

[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A remote gain unit, characterized in that, The remote gain unit is suitable for remote pumping transmission systems and includes: a first circulator (1), a first wavelength division multiplexer (2), an amplifying optical fiber (3), a second circulator (4), and a second wavelength division multiplexer (5). The first port of the first circulator (1) is connected to the input of the remote gain unit, the second port of the first circulator (1) is connected to the transmission end of the first wavelength division multiplexer (2), and the third port of the first circulator (1) is connected to the transmission end of the second wavelength division multiplexer (5). The reflecting end of the first wavelength division multiplexer (2) is connected to the reflecting end of the second wavelength division multiplexer (5), and the common end of the first wavelength division multiplexer (2) is connected to one end of the amplifying optical fiber (3); the first port of the second circulator (4) is connected to the other end of the amplifying optical fiber (3), the second port of the second circulator (4) is connected to the output end of the remote gain unit, and the third port of the second circulator (4) is connected to the common end of the second wavelength division multiplexer (5); The second wavelength division multiplexer (5) is used to transmit the pump light from the output of the remote gain unit to the first wavelength division multiplexer (2); it is also used to transmit the measurement light from the output of the remote gain unit to the first circulator (1) so that the measurement light bypasses the amplifying fiber (3).

2. The remote gain unit according to claim 1, characterized in that, The remote gain unit also includes a reflector (6), which is disposed between the other end of the amplifying fiber (3) and the first port of the second circulator (4); the reflector (6) is used to reflect the pump light from the amplifying fiber (3) to improve the utilization efficiency of the pump light.

3. The remote gain unit according to claim 2, characterized in that, The center wavelength of the reflector (6) is in the range of 1450nm-1650nm.

4. The remote gain unit according to claim 1, characterized in that, When the wavelengths of the signal light and the measurement light are not changeable and the wavelength difference between the signal light and the measurement light is greater than 40 nm, the first circulator (1) is replaced by the third wavelength division multiplexer (7). The transmission end of the third wavelength division multiplexer (7) is connected to the input end of the remote gain unit, the common end of the third wavelength division multiplexer (7) is connected to the transmission end of the first wavelength division multiplexer (2), and the reflection end of the third wavelength division multiplexer (7) is connected to the transmission end of the second wavelength division multiplexer (5). The third wavelength division multiplexer (7) is used to receive signal light from the outside and transmit the signal light to the first wavelength division multiplexer (2). The third wavelength division multiplexer (7) is also used to transmit the measurement light to the input of the remote gain unit to measure the fiber attenuation in the remote pumping transmission system based on the measurement light.

5. The remote gain unit according to any one of claims 1-4, characterized in that, The amplifying optical fiber (3) is an erbium-doped optical fiber, a praseodymium-doped optical fiber, or a rubidium-doped optical fiber.

6. The remote gain unit according to any one of claims 1-4, characterized in that, The wavelength range of the transmission end of the first wavelength division multiplexer (2) and the second wavelength division multiplexer (5) is 1525nm~1560nm; the wavelength range of the reflection end of the first wavelength division multiplexer (2) and the second wavelength division multiplexer (5) is 1450nm~1500nm.

7. The remote gain unit according to any one of claims 1-4, characterized in that, The isolation between each port on the first circulator (1) and the second circulator (4) is greater than or equal to 50dB, and the insertion loss between each port is less than or equal to 0.5dB.

8. A method for detecting attenuation, characterized in that, The method is applicable to the remote gain unit as described in any one of claims 1-7, and the attenuation detection method includes: When the pump light is input from the output of the remote gain unit, the first circulator (1) receives the signal light from the outside and transmits the signal light to the first wavelength division multiplexer (2). The second circulator (4) receives pump light and measurement light from the output of the remote gain unit and transmits the pump light and measurement light to the second wavelength division multiplexer (5). The second wavelength division multiplexer (5) transmits the pump light to the first wavelength division multiplexer (2) and the second wavelength division multiplexer (5) transmits the measurement light to the first circulator (1). When the pump light is input from the input terminal of the remote gain unit, the first circulator (1) receives the signal light and the pump light, and transmits the signal light and the pump light to the first wavelength division multiplexer (2). The first wavelength division multiplexer (2) transmits the signal light and the pump light to the amplifying fiber (3) to amplify the signal light, and the second circulator (4) transmits the amplified signal light to the output of the remote gain unit; The first circulator (1) transmits the measurement light to the input of the remote gain unit to measure the fiber attenuation in the remote pumping transmission system based on the measurement light.

9. A remote pumping transmission system, characterized in that, It includes a remote gain unit, a detection unit, and a pumping unit as described in any one of claims 1-7; the pumping unit is connected to the input or output of the remote gain unit; the detection unit is connected to the input of the remote gain unit; When the pump unit is connected to the output of the remote gain unit, the pump unit is used to emit the pump light. The pump light passes through the second circulator (4), the second wavelength division multiplexer (5) and the first wavelength division multiplexer (2) in sequence and is transmitted together with the signal light to the amplifying fiber (3) to amplify the signal light. The detection unit is used to receive measurement light from the input of the remote gain unit and to obtain the fiber attenuation in the remote pumping transmission system based on the measurement light.

10. The remote pumping transmission system according to claim 9, characterized in that, When the pump unit is connected to the input terminal of the remote gain unit, the pump unit is used to emit the pump light. The pump light and the signal light are simultaneously input to the input terminal of the remote gain unit. The pump light and the signal light pass through the first circulator (1) and the first wavelength division multiplexer (2) in sequence, and then are input together into the amplifying fiber (3) to amplify the signal light.

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