Multi-core optical fiber, optical cable and communication system

Abstract

The invention provides a multi-core optical fiber, an optical cable and a communication system. The communication system can comprise a signal transmitter, a signal receiver, a first multi-core optical fiber and a second multi-core optical fiber. The first multi-core optical fiber comprises a first wrapping layer, at least one first fiber core and at least one second fiber core, wherein the first fiber core and the second fiber core are wrapped in the first wrapping layer, and the dispersion value of each second fiber core is smaller than that of any first fiber core. The second multi-core optical fiber comprises a second cladding, and at least one first fiber core and at least one second fiber core which are wrapped in the second cladding. The end part of the first multi-core optical fiber is welded with the end part of the second multi-core optical fiber, the first fiber core in the first multi-core optical fiber is connected with the second fiber core in the second multi-core optical fiber, and the second fiber core in the first multi-core optical fiber is connected with the first fiber core in the second multi-core optical fiber. According to the technical scheme provided by the invention, the dispersion accumulation of the optical fiber can be reduced, and the dispersion compensation power consumption of the digital signal processing module is further reduced.

Description

Technical Field

[0001] This application relates to the field of communication technology, and in particular to a multi-core optical fiber, optical cable and communication system. Background Technology

[0002] With the rapid development of communication technology, optical fiber communication, as a high-bandwidth, low-transmission-loss communication technology, can meet the needs of communication systems for large-capacity, high-speed data transmission, enabling large amounts of data to be transmitted quickly and stably.

[0003] However, dispersion in optical fibers causes pulse broadening, degrading transmission performance. In some applications, signal light needs to be transmitted over long distances in optical fibers, and as the transmission distance increases, dispersion in the fiber accumulates. Furthermore, the higher the optical transmission rate of the communication system, the more pronounced the dispersion problem becomes. Therefore, optical fiber dispersion is one of the main factors affecting the long-distance transmission performance of communication systems. In related communication systems, dispersion is compensated for using a digital signal processing (DSP) module. The complexity of dispersion compensation is proportional to the square of the baud rate. Increasing the baud rate leads to increased logic circuit complexity, which in turn increases the power consumption of the dispersion compensation process, resulting in higher power consumption for the DSP module. Summary of the Invention

[0004] This application provides a multi-core optical fiber, optical cable, and communication system to reduce dispersion accumulation in the transmission link, thereby reducing the complexity and power consumption of the digital signal processing module in the communication system.

[0005] In a first aspect, embodiments of this application provide a communication system. The communication system provided in this application embodiment may include: a signal transmitter, a signal receiver, and a first multi-core optical fiber and a second multi-core optical fiber connected between the signal transmitter and the signal receiver. The first multi-core optical fiber may include: a first cladding, and at least one first fiber core and at least one second fiber core encased within the first cladding, wherein the dispersion value of each second fiber core is less than the dispersion value of any of the first fiber cores. The second multi-core optical fiber may include: a second cladding, and at least one first fiber core and at least one second fiber core encased within the second cladding. The ends of the first multi-core optical fiber and the ends of the second multi-core optical fiber are fused together; the first fiber core in the first multi-core optical fiber is connected to the second fiber core in the second multi-core optical fiber; and the second fiber core in the first multi-core optical fiber is connected to the first fiber core in the second multi-core optical fiber.

[0006] In this embodiment, the dispersion value of each second fiber core is less than that of any first fiber core. Typically, the dispersion value of an optical fiber (or fiber core) is related to its effective area; that is, in this embodiment, the effective area of ​​the second fiber core is less than that of the first fiber core. However, reducing the dispersion value of the optical fiber sacrifices its effective area. The smaller the effective area of ​​the optical fiber, the greater the nonlinear accumulation during signal light transmission. Due to the smaller effective area of ​​the second fiber core, if the optical power of the signal light in the second fiber core is high, a large nonlinear accumulation will occur, resulting in poor signal light performance. In this embodiment, the signal light transmission in the communication system is directional. During the transmission of the signal light in the first and second multi-core optical fibers, the signal light first passes through the first fiber core and then through the second fiber core connected to the first fiber core. After transmission in the first fiber core, the optical power of the signal light will attenuate to a certain extent. Thus, the optical power of the signal light entering the second fiber core is smaller, the nonlinear accumulation of the signal light in the second fiber core is smaller, and there will be no significant performance degradation. Furthermore, the second fiber core has a lower dispersion value, which can significantly reduce the dispersion accumulation of the transmission link. Therefore, the technical solution provided in this application embodiment can significantly reduce the dispersion accumulation of the transmission link without significant degradation in transmission link performance, thus alleviating the dispersion compensation power consumption of the digital signal processing module. This frees up more space in the digital signal processing module to support higher-speed signal transmission. Furthermore, the reduction in link dispersion helps reduce equalization-enhanced phase noise (EEPN). In addition, the optical fiber in this application embodiment is a multi-core optical fiber, with multiple cores encased within its cladding. Each core can function as an independent transmission channel, allowing multiple optical signals to be transmitted in different cores of the same fiber, increasing the number of channels in the link and expanding the transmission capacity of a single optical fiber. Therefore, the communication system in this application embodiment is suitable for scenarios involving long-distance transmission, high-capacity, and high-speed data transmission.

[0007] Since the signal light passes through the first fiber core and then the second fiber core connected to the first fiber core during transmission, in this embodiment of the application, both the first multi-core fiber and the second multi-core fiber integrate the first fiber core and the second fiber core. After splicing the first multi-core fiber and the second multi-core fiber, the communication system can achieve bidirectional transmission.

[0008] In one possible implementation, the first and second multi-core optical fibers can be placed in the same span of the communication system, where a span refers to the distance between two adjacent fiber amplifiers. The lengths and splice positions of the first and second multi-core optical fibers can be set according to actual needs, for example, based on the optical parameters of the first and second fibers and the performance of the communication system.

[0009] In practice, various methods can be used to determine whether a fiber core is the first or second fiber core. For example, an optical inspection instrument can be used to measure the effective area and dispersion value of the fiber core; another method is to photograph the end face of the fiber core and measure its geometric structure; yet another method is to utilize the directionality of signal light transmission to detect the connection between the receiving and transmitting fibers—the one connected to the transmitting end is the first fiber core, and the one connected to the receiving end is the second fiber core. Of course, other methods can also be used to determine whether a fiber core is the first or second fiber core, which will not be listed here.

[0010] The basic structure of the communication system in some embodiments of this application has been introduced above. The specific implementation of the first multi-core optical fiber and the second multi-core optical fiber in the above communication system is described in detail below.

[0011] The multi-core optical fiber (which can be either the first multi-core optical fiber or the second multi-core optical fiber described above) in this embodiment may include: a cladding (which can be either the first cladding or the second cladding), and at least one first fiber core and at least one second fiber core enclosed within the cladding. The dispersion value of each second fiber core is less than the dispersion value of any of the first fiber cores. The multi-core optical fiber in this embodiment integrates two fiber cores with different dispersion values. By fusion splicing the two multi-core optical fibers in this embodiment, the signal light can pass through the first fiber core first, and then through the second fiber core with the lower dispersion value during transmission. This significantly reduces the dispersion accumulation in the transmission link without substantial degradation of the transmission link performance.

[0012] In practical implementation, the dispersion value of the optical fiber (or fiber core) is related to the effective area. If the dispersion value of the optical fiber is reduced, the effective area of ​​the optical fiber will be sacrificed. That is, in the embodiments of this application, the effective area of ​​each second fiber core is less than the effective area of ​​any first fiber core.

[0013] Among them, the effective area A of the fiber mode eff It can be characterized by the distribution of the electric field in the fiber core, and can be calculated using the following formula:

[0014]

[0015] Where E is the wavelength-dependent electric field, and r is the distance between the axis and the point where the electric field is distributed.

[0016] In one possible implementation, when the operating wavelength of the multi-core fiber is 1550 nm, the dispersion value of the first core can be less than 23 ps / (nm·km), and the effective area of ​​the first core can be greater than or equal to 100 μm. 2 The dispersion value of the second fiber core can be greater than 4 ps / (nm·km), and the effective area of ​​the second fiber core can be greater than or equal to 60 μm. 2In this embodiment, the dispersion values ​​of the first fiber core and the second fiber core are both positive. Therefore, the optical fiber link composed of the first fiber core and the second fiber core does not have a zero dispersion point and will not produce four-wave mixing phenomenon.

[0017] In one possible implementation, the number of first cores in a multi-core fiber is equal to the number of second cores, and the first and second cores are alternately distributed on concentric rings of the cladding. This arrangement facilitates accurate end-to-end splicing of two multi-core fibers. Furthermore, the different parameters of adjacent cores in a multi-core fiber can reduce signal crosstalk between adjacent cores.

[0018] Taking a multi-core optical fiber with two first cores and two second cores as an example, two multi-core optical fibers are designated as the first multi-core optical fiber and the second multi-core optical fiber, respectively. During the optical cable laying process, the first and second multi-core optical fibers can be rotated relative to each other by a certain angle, aligning the first core of one multi-core optical fiber with the second core of the other, thereby accurately connecting the ends of the two multi-core optical fibers. In this embodiment, the number of first cores and the number of second cores in the multi-core optical fiber are equal, that is, the total number N of first and second cores in the multi-core optical fiber is an even number. Each first core and each second core in the multi-core optical fiber can be placed on the same concentric ring layer of the cladding. Thus, during installation, the two multi-core optical fibers can be accurately connected by rotating relative to each other by 360° / N.

[0019] In practical implementation, the number of the first and second cores in a multi-core optical fiber can be reasonably set according to actual needs. In some cases, when there are many first and second cores in a multi-core optical fiber, the first and second cores can be distributed on multiple concentric ring layers, as long as the two multi-core optical fibers can be accurately connected.

[0020] Furthermore, in some cases, the number of the first core and the number of the second core in a multi-core optical fiber may not be equal. That is, the total number of the first and second cores in a multi-core optical fiber may also be an odd number. In practical applications, the number of the first and second cores in a multi-core optical fiber can be reasonably set according to actual needs, as long as the two multi-core optical fibers can be accurately connected.

[0021] In one possible implementation, the first core may include a first core layer and a first channel layer surrounding the first core layer. The refractive index n1 of the first core layer is greater than the refractive index n0 of the cladding, and the refractive index n0 of the cladding is greater than the refractive index n2 of the first channel layer, i.e., n1 > n0 > n2.

[0022] The relative refractive index difference Δ1 between the first channel layer and the first core layer can satisfy: -0.7% ≤ Δ1 ≤ -0.3%, and the relative refractive index difference Δ1 is defined as:

[0023]

[0024] The relative refractive index difference Δ2 between the cladding and the first core layer can satisfy: -0.5% ≤ Δ2 ≤ -0.2%, and the relative refractive index difference Δ2 is defined as:

[0025]

[0026] The radius r1 of the first core layer and the outer diameter r2 of the first channel layer can satisfy: 5.0μm≤r1≤7.0μm, r1<r2≤25.0μm.

[0027] In some other implementations of this application, the first fiber core may further include an inner cladding layer. That is, the first fiber core may include: a first core layer, an inner cladding layer surrounding the first core layer, and a first channel layer surrounding the inner cladding layer. The refractive index n1 of the first core layer is greater than the refractive index n7 of the inner cladding layer. The refractive index n7 of the inner cladding layer may be greater than or equal to the refractive index n0 of the cladding layer, and the refractive index n0 of the cladding layer is greater than the refractive index n2 of the first channel layer, i.e., n1 > n7 ≥ n0 > n2. The radius r1 of the first core layer, the outer diameter r2 of the first channel layer, and the outer diameter r7 of the inner cladding layer may satisfy: 5.0 μm ≤ r1 ≤ 7.0 μm, r1 ≤ r7 ≤ 14.0 μm, and r7 < r2 ≤ 25.0 μm.

[0028] In this embodiment, the second fiber core may include a second core layer and a second channel layer surrounding the second core layer. The second core layer may include at least three sub-core layers, specifically: a first sub-core layer, a second sub-core layer surrounding the first sub-core layer, and a third sub-core layer surrounding the second sub-core layer. The refractive index n3 of the first sub-core layer is greater than the refractive index n4 of the second sub-core layer, and the refractive index n4 of the second sub-core layer is greater than the refractive index n5 of the second channel layer, i.e., n3 > n4 > n5. Furthermore, the refractive index n3 of the first sub-core layer is greater than the refractive index n6 of the third sub-core layer, and the refractive index n6 of the third sub-core layer is greater than the refractive index n5 of the second channel layer, i.e., n3 > n6 > n5. By setting at least three sub-core layers in the second core layer and appropriately setting the refractive index of each sub-core layer, the dispersion value of the second fiber core can be controlled.

[0029] The radius r3 of the first sub-core layer satisfies: 1.4μm ≤ r3 ≤ 2.6μm; the outer diameter r4 of the second sub-core layer satisfies: 6.0μm ≤ r4 ≤ 8.0μm; the outer diameter r5 of the third sub-core layer and the outer diameter r6 of the second channel layer satisfy: 6.5μm ≤ r5 ≤ 11.0μm, r5 < r6 ≤ 25.0μm. The relative refractive index difference Δ3 between the first and second sub-core layers satisfies: 0.43% ≤ Δ3 ≤ 0.55%; the relative refractive index difference Δ4 between the second and third sub-core layers satisfies: -0.17% ≤ Δ4 ≤ -0.05%; the relative refractive index difference Δ5 between the third and third sub-core layers satisfies: -0.35% ≤ Δ5 ≤ 0.13%; and the relative refractive index difference Δ6 between the second channel layer and the first core layer satisfies: -0.7% ≤ Δ6 ≤ -0.3%. The relative refractive index differences Δ3, Δ4, Δ5, and Δ6 are defined as follows:

[0030] and

[0031] In the embodiments of this application, by reasonably setting the refractive index and radius of each layer in the first fiber core and the second fiber core, the first fiber core can have a large effective area and the second fiber core can have a low dispersion value, so as to significantly reduce the dispersion accumulation of the transmission link.

[0032] The preceding text detailed the specific implementation methods of the first and second multi-core optical fibers in the aforementioned communication system. In some cases, the communication system can also incorporate more multi-core optical fibers. For example, a third multi-core optical fiber can be fused to the end of the second multi-core optical fiber furthest from the first multi-core optical fiber; similarly, a fourth multi-core optical fiber can be fused to the end of the first multi-core optical fiber furthest from the second multi-core optical fiber. In specific configurations, the dispersion value of each fiber core can be appropriately set according to actual needs. Alternatively, the communication system can employ multiple interconnected first and second multi-core optical fibers, configured according to actual signal transmission requirements.

[0033] Secondly, embodiments of this application also provide a multi-core optical fiber. The multi-core optical fiber provided in this application embodiment may include: a cladding, and at least one first fiber core and at least one second fiber core encased within the cladding. The dispersion value of each second fiber core is less than the dispersion value of any of the first fiber cores. The multi-core optical fiber in this application embodiment integrates two fiber cores with different dispersion values. By fusion splicing the two multi-core optical fibers in this application embodiment, the signal light can pass through the first fiber core first, and then through the second fiber core with the lower dispersion value during transmission. Therefore, a significant reduction in transmission link dispersion accumulation can be achieved without significant degradation of transmission link performance.

[0034] The specific implementation method of the multi-core optical fiber in the second aspect can be implemented with reference to the multi-core optical fiber (first multi-core optical fiber or second multi-core optical fiber) in the first aspect above. The repeated parts will not be repeated.

[0035] Thirdly, embodiments of this application also provide another communication system, which may include: a signal transmitter, a signal receiver, and a first multi-core optical fiber and a second multi-core optical fiber connected between the signal transmitter and the signal receiver. The first multi-core optical fiber may include: a first cladding, and a plurality of first fiber cores encased within the first cladding. The second multi-core optical fiber may include: a second cladding, and a plurality of second fiber cores encased within the second cladding. The dispersion value of each second fiber core is less than the dispersion value of any of the first fiber cores. The ends of the first multi-core optical fiber and the ends of the second multi-core optical fiber are fused together, and the first fiber cores in the first multi-core optical fiber are connected to the second fiber cores in the second multi-core optical fiber.

[0036] In this embodiment, the dispersion value of each second fiber core is less than that of any first fiber core. Typically, the dispersion value of an optical fiber (or fiber core) is related to its effective area. Reducing the dispersion value of the fiber sacrifices its effective area; that is, in this embodiment, the effective area of ​​the second fiber core is less than that of the first fiber core. However, the smaller the effective area of ​​the optical fiber, the greater the nonlinear accumulation during signal light transmission. Due to the smaller effective area of ​​the second fiber core, if the optical power of the signal light in the second fiber core is high, a large nonlinear accumulation will occur, resulting in poor signal light performance. In this embodiment, the signal light transmission in the communication system is directional. During the transmission of the signal light in the first and second multi-core optical fibers, the signal light first passes through the first fiber core and then through the second fiber core connected to the first fiber core. After transmission in the first fiber core, the optical power of the signal light will attenuate to a certain extent. Thus, the optical power of the signal light entering the second fiber core is smaller, the nonlinear accumulation of the signal light in the second fiber core is smaller, and there will be no significant performance degradation. Furthermore, the second fiber core has a lower dispersion value, which can significantly reduce the dispersion accumulation of the transmission link. Therefore, the technical solution provided in this application embodiment can significantly reduce the dispersion accumulation of the transmission link without significant degradation of the transmission link performance, thereby alleviating the dispersion compensation power consumption of the digital signal processing module.

[0037] Because the dispersion values ​​of the cores in the first and second multi-core optical fibers are different, splicing them together connects the first core of the first multi-core fiber to the second core of the second multi-core fiber, allowing unidirectional signal light transmission. In practical applications, two sets of multi-core optical fibers with different transmission directions can be arranged side-by-side to enable bidirectional transmission in the communication system.

[0038] In this embodiment, the specific configuration of the first multi-core optical fiber and the second multi-core optical fiber can be implemented with reference to the above description, and the repeated parts will not be described again.

[0039] Fourthly, embodiments of this application also provide a multi-core optical fiber, which may include: a second cladding, and a plurality of second cores encased in the second cladding. When the operating wavelength of the multi-core optical fiber is 1550 nm, the dispersion value of each second core is greater than 4 ps / (nm·km), and the dispersion value of each second core is less than 23 ps / (nm·km). That is, the multi-core optical fiber in the fourth aspect can be the second multi-core optical fiber in the third aspect. The specific implementation of the multi-core optical fiber in the fourth aspect can be referred to the description of the second multi-core optical fiber in the third aspect above, and repeated details will not be elaborated further.

[0040] Fifthly, embodiments of this application also provide an optical cable. The optical cable in this application embodiment may include: a sheath, and at least one multi-core optical fiber as described in the second or fourth aspect above, with the sheath encasing at least one multi-core optical fiber. The optical cable in this application embodiment can be a normal-sized optical cable, or it can be a thinner micro-cable. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the communication system framework in the embodiments of this application;

[0042] Figure 2 This is a schematic diagram of the communication system provided in an embodiment of this application;

[0043] Figure 3 This is a schematic diagram illustrating the accumulation of optical fiber dispersion over transmission distance.

[0044] Figure 4 This is a schematic diagram of the cross-section of the multi-core optical fiber in an embodiment of this application;

[0045] Figure 5 for Figure 4 The diagram shows the structural design of the first and second cores in a multi-core optical fiber.

[0046] Figure 6 This is another cross-sectional schematic diagram of the multi-core optical fiber in the embodiments of this application;

[0047] Figure 7 for Figure 6 The diagram shows the structural design of the first and second cores in a multi-core optical fiber.

[0048] Figure 8 This is another cross-sectional schematic diagram of the multi-core optical fiber in the embodiments of this application;

[0049] Figure 9Another schematic diagram of the communication system provided in the embodiments of this application;

[0050] Figure 10 This is a schematic diagram of another cross-section of the multi-core optical fiber in an embodiment of this application.

[0051] Figure label:

[0052] 11-Signal transmitter; 12-Signal receiver; 13-Multi-core optical fiber; 131-First multi-core optical fiber; 132-Second multi-core optical fiber; 14-First wavelength division multiplexer; 15-Second wavelength division multiplexer; 16-Fiber amplifier; 17-Fan-in device; 18-Fan-out device; 200-Cladding; 201-First cladding; 202-Second cladding; 203-First fiber core; 204-Second fiber core; 301-First core layer; 302-First channel layer; 303-Inner cladding; 41-Second core layer; 411-First sub-core layer; 412-Second sub-core layer; 413-Third sub-core layer; 42-Second channel layer. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this application clearer, the application will now be described in further detail with reference to the accompanying drawings.

[0054] It should be noted that the accompanying drawings in this application are for illustrative purposes only and do not represent actual scale. The same reference numerals in the accompanying drawings denote the same or similar structures, and therefore, repeated descriptions of them will be omitted.

[0055] The terms describing position and direction used in this application, such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," are merely illustrative examples based on the orientation or positional relationships shown in the accompanying drawings. They are intended solely for the convenience of describing this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Changes may be made as needed, and all such changes are included within the scope of protection of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0056] This application provides a multi-core optical fiber, optical cable, and communication system. The multi-core optical fiber provided in this application has a low dispersion value. Based on the low dispersion accumulation in the transmission link of this multi-core optical fiber, applying it to a communication system can reduce the power consumption of the digital signal processing module, freeing up more space to support higher-speed signal transmission. Furthermore, the optical fiber in this application is a multi-core optical fiber, with multiple cores encased within its cladding. Each core can function as an independent transmission channel, allowing multiple optical signals to be transmitted in different cores of the same fiber, increasing the number of channels in the link and expanding the transmission capacity of a single optical fiber. Therefore, the communication system in this application is suitable for scenarios involving long-distance transmission, high-capacity, and high-speed data transmission.

[0057] To facilitate understanding of the technical solution of this application, the structure of the communication system in the embodiment of this application will be described below with reference to the accompanying drawings.

[0058] Figure 1 This is a schematic diagram of the communication system framework in an embodiment of this application, such as... Figure 1 As shown, the communication system provided in this application embodiment may include: a signal transmitter 11, a signal receiver 12, and a multi-core optical fiber 13 connecting the signal transmitter 11 and the signal receiver 12. The transmitting modules TX1, TX2, TX3...TXn in the signal transmitter 11 transmit signal light with wavelengths λ1, λ2, λ3...λn, respectively. The first wavelength division multiplexer 14 can split the signal light of different wavelengths and couple the signal light of different wavelengths into different cores of the multi-core optical fiber 13. After transmission through the multi-core optical fiber 13, the signal light of different wavelengths is input into the second wavelength division multiplexer 15. The second wavelength division multiplexer 15 separates the signal light of different wavelengths and outputs the signal light of different wavelengths from different ports, so that the signal light of different wavelengths is received by the receiving modules RX1, RX2, RX3...RXn in the signal receiver 12.

[0059] Because the multi-core optical fiber 13 has loss characteristics, the signal light is gradually lost during transmission within it, causing the signal light intensity to gradually decrease. To increase the signal light intensity, the communication system in this embodiment may further include an optical fiber amplifier 16, which can be used to amplify the signal light. Exemplarily, the optical fiber amplifier 16 can be an array of multiple single-mode optical fiber amplifiers, or it can be an integrated optical fiber amplifier. In a specific configuration, multiple spans of multi-core optical fibers 13 can be configured in the communication system, and an optical fiber amplifier 16 can be placed at the input end of each multi-core optical fiber 13, thereby amplifying the signal light before it enters each span for transmission.

[0060] In some cases, such as when the fiber amplifier 16 is an array of multiple single-mode fiber amplifiers, the communication system in this embodiment may further include a fan-in device 17 and a fan-out device 18. The fan-in device 17 can be used to fan the signal light into each core of the multi-core fiber 13, and the fan-out device 18 can be used to fan the signal light out from each core of the multi-core fiber 13. Specifically, the fiber amplifier 16 and the fan-in device 17 can be set at the input end of the multi-core fiber 13, and the fan-out device 18 can be set at the output end of the multi-core fiber 13. During signal light transmission, the signal light amplified by the fiber amplifier 16 can be fanned into each core of the multi-core fiber 13 through the fan-in device 17. After transmission through one span of the multi-core fiber 13, the signal light is fanned out by the fan-out device 18, amplified again by the next-stage fiber amplifier 16, and then fanned into the next span of the multi-core fiber 13 through the next-stage fan-in device 17, and so on. After transmission and amplification through multiple spans, the signal light is received by the signal receiver 12.

[0061] In related technologies, optical fibers typically exhibit dispersion. For example, commercial optical fibers often have positive dispersion values ​​in the 1550nm band. Dispersion in optical fibers causes pulse broadening, degrading transmission performance. In some applications, signal light needs to be transmitted over long distances in optical fibers. Dispersion accumulates with increasing transmission distance, and the higher the optical transmission rate of the communication system, the more pronounced the dispersion problem becomes. Therefore, optical fiber dispersion is one of the main factors affecting the long-distance transmission performance of communication systems. In related communication systems, dispersion compensation is performed using digital signal processing (DSP) modules. However, the dispersion compensation process consumes a significant amount of power, resulting in high power consumption for the DSP modules.

[0062] Based on this, in order to reduce dispersion accumulation in the transmission link and thus reduce the complexity and power consumption of the digital signal processing module in the communication system, the technical solution of the embodiments of this application improves the structure of the multi-core optical fiber and the communication system. The technical solution provided by the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0063] Figure 2 This is a schematic diagram of the communication system provided in the embodiments of this application, such as... Figure 2 As shown, in some embodiments of this application, the communication system may include: a signal transmitter, a signal receiver, and a first multi-core optical fiber 131 and a second multi-core optical fiber 132 connected between the signal transmitter and the signal receiver. The signal transmitter and signal receiver are in... Figure 2 The settings for the signal transmitter and receiver are not shown in the diagram. Please refer to [reference needed]. Figure 1As shown. The first multi-core optical fiber 131 may include: a first cladding 201, and at least one first fiber core 203 and at least one second fiber core 204 enclosed within the first cladding 201, wherein the dispersion value of each second fiber core 204 is less than the dispersion value of any one of the first fiber cores 203. The second multi-core optical fiber 132 may include: a second cladding 202, and at least one first fiber core 203 and at least one second fiber core 204 enclosed within the second cladding 202. The ends of the first multi-core optical fiber 131 and the ends of the second multi-core optical fiber 132 are fused together, the first fiber core 203 in the first multi-core optical fiber 131 is connected to the second fiber core 204 in the second multi-core optical fiber 132, and the second fiber core 204 in the first multi-core optical fiber 131 is connected to the first fiber core 203 in the second multi-core optical fiber 132.

[0064] In this embodiment, the dispersion value of each second fiber core 204 is less than that of any first fiber core 203. Typically, the dispersion value of an optical fiber (or fiber core) is related to its effective area; that is, in this embodiment, the effective area of ​​the second fiber core 204 is less than that of the first fiber core 203. However, reducing the dispersion value of the optical fiber sacrifices its effective area. The smaller the effective area of ​​the optical fiber, the greater the nonlinear accumulation during signal light transmission. Because the effective area of ​​the second fiber core 204 is small, if the optical power of the signal light in the second fiber core 204 is large, a large nonlinear accumulation will occur, resulting in poor signal light performance. In this embodiment, the signal light transmission in the communication system is directional. During the transmission of the signal light in the first multi-core optical fiber 131 and the second multi-core optical fiber 132, the signal light first passes through the first fiber core 203 and then through the second fiber core 204 connected to the first fiber core 203. After the signal light propagates in the first fiber core 203, its optical power attenuates to a certain extent. Therefore, the optical power of the signal light entering the second fiber core 204 is relatively low, resulting in less nonlinear accumulation during transmission in the second fiber core 204 and preventing significant performance degradation. Furthermore, the second fiber core 204 has a lower dispersion value, which significantly reduces dispersion accumulation in the transmission link. Therefore, the technical solution provided in this application can significantly reduce dispersion accumulation in the transmission link without significant performance degradation, alleviating the power consumption of dispersion compensation in the digital signal processing module. This frees up more space in the digital signal processing module to support higher-speed signal transmission. Moreover, the reduction in link dispersion helps reduce equalization-enhanced phase noise (EEPN).

[0065] Continue to refer to Figure 2Since both the first multi-core optical fiber 131 and the second multi-core optical fiber 132 integrate two types of fiber cores with different dispersion values, splicing the first multi-core optical fiber 131 and the second multi-core optical fiber 132 enables bidirectional transmission in the communication system. The first fiber core 203 in the first multi-core optical fiber 131 is connected to the second fiber core 204 in the second multi-core optical fiber 132, allowing the signal light to travel along... Figure 2 The signal is transmitted in the direction of the dashed arrow F1. The second core 204 in the first multi-core fiber 131 is connected to the first core 203 in the second multi-core fiber 132, allowing the signal light to travel along... Figure 2 The direction of transmission is indicated by the dashed arrow F2.

[0066] In one possible implementation, the first multi-core optical fiber 131 and the second multi-core optical fiber 132 can be arranged in the same span of the communication system, where a span refers to the distance between two adjacent optical fiber amplifiers 16. The lengths and splice positions of the first multi-core optical fiber 131 and the second multi-core optical fiber 132 can be set according to actual needs, for example, based on the optical parameters of the first fiber core 203 and the second fiber core 204 and the performance of the communication system.

[0067] Figure 3 This is a schematic diagram illustrating the accumulation of optical fiber dispersion over transmission distance. Figure 3 In the diagram, curve S1 represents the variation of the dispersion value of the optical fiber with transmission distance in this embodiment, and curve S2 represents the variation of the dispersion value of the optical fiber with transmission distance in the comparative example. In this embodiment, the ends of the first multi-core optical fiber and the second multi-core optical fiber are fused together. During signal light transmission, the light passes through the first core first, and then through the second core with a lower dispersion value. In the comparative example, the optical fiber contains only the first core with a single dispersion value. Comparing curves S1 and S2, it is clear that compared to the technical solution in the comparative example, the multi-core optical fiber in this embodiment exhibits less dispersion accumulation as the transmission distance increases. The technical solution in this embodiment can significantly reduce dispersion accumulation in the optical fiber.

[0068] In practice, various methods can be used to determine whether a fiber core is the first or second fiber core. For example, an optical inspection instrument can be used to measure the effective area and dispersion value of the fiber core; another method is to photograph the end face of the fiber core and measure its geometric structure; yet another method is to utilize the directionality of signal light transmission to detect the connection between the receiving and transmitting fibers—the one connected to the transmitting end is the first fiber core, and the one connected to the receiving end is the second fiber core. Of course, other methods can also be used to determine whether a fiber core is the first or second fiber core, which will not be listed here.

[0069] The basic structure of the communication system in some embodiments of this application has been described above. The following, in conjunction with the accompanying drawings, details the specific implementation of the first multi-core optical fiber and the second multi-core optical fiber in the above communication system.

[0070] Figure 4 This is a schematic cross-sectional view of the multi-core optical fiber in an embodiment of this application, as shown below. Figure 4 As shown, the multi-core optical fiber 13 in this embodiment (which can be either the first multi-core optical fiber or the second multi-core optical fiber) may include: a cladding 200 (which can be either the first cladding or the second cladding), and at least one first fiber core 203 and at least one second fiber core 204 enclosed within the cladding 200. The dispersion value of each second fiber core 204 is less than the dispersion value of any of the first fiber cores 203. The multi-core optical fiber in this embodiment integrates two fiber cores with different dispersion values. By fusion splicing the two multi-core optical fibers in this embodiment, the signal light can pass through the first fiber core first, and then through the second fiber core with the lower dispersion value during transmission. This significantly reduces the dispersion accumulation in the transmission link without significant degradation of the transmission link performance.

[0071] In practical implementation, the dispersion value of the optical fiber (or fiber core) is related to the effective area. If the dispersion value of the optical fiber is reduced, the effective area of ​​the optical fiber will be sacrificed. That is, in the embodiments of this application, the effective area of ​​each second fiber core 204 is less than the effective area of ​​any first fiber core 203.

[0072] Among them, the effective area A of the fiber mode eff It can be characterized by the distribution of the electric field in the fiber core, and can be calculated using the following formula:

[0073]

[0074] Where E is the wavelength-dependent electric field, and r is the distance between the axis and the point where the electric field is distributed.

[0075] In one possible implementation, when the operating wavelength of the multi-core fiber 13 is 1550 nm, the dispersion value of the first core 203 can be less than 23 ps / (nm·km), and the effective area of ​​the first core 203 can be greater than or equal to 100 μm. 2 The dispersion value of the second core 204 can be greater than 4 ps / (nm·km), and the effective area of ​​the second core 204 can be greater than or equal to 60 μm. 2 In this embodiment, the dispersion values ​​of the first fiber core 203 and the second fiber core 204 are both positive. Therefore, the optical fiber link composed of the first fiber core 203 and the second fiber core 204 does not have a zero dispersion point and will not produce a four-wave mixing phenomenon.

[0076] Continue to refer to Figure 4In one possible implementation, the number of first cores 203 and second cores 204 in the multi-core fiber 13 are equal, and the first cores 203 and second cores 204 in the multi-core fiber 13 are alternately distributed on the concentric ring layer of the cladding 200. This arrangement facilitates accurate end-to-end splicing of two multi-core fibers 13. Furthermore, the different parameters of adjacent cores in the multi-core fiber 13 can reduce signal crosstalk between adjacent cores.

[0077] Combination Figure 2 and Figure 4 Taking a multi-core optical fiber 13 with two first fiber cores 203 and two second fiber cores 204 as an example, the two multi-core optical fibers 13 are designated as the first multi-core optical fiber 131 and the second multi-core optical fiber 132, respectively. During the optical cable laying process, the first multi-core optical fiber 131 and the second multi-core optical fiber 132 can be rotated relative to each other by a certain angle, so that the first fiber core 203 in one multi-core optical fiber 13 is aligned with the second fiber core 204 in the other multi-core optical fiber 13, thereby accurately connecting the ends of the two multi-core optical fibers 13. In this embodiment, the number of first fiber cores 203 in the multi-core optical fiber 13 is equal to the number of second fiber cores 204, that is, the total number N of first fiber cores 203 and second fiber cores 204 in the multi-core optical fiber 13 is an even number. Each first fiber core 203 and each second fiber core 204 in the multi-core optical fiber 13 can be arranged on the same concentric ring layer of the cladding 200. In this way, during the installation process, the two multi-core optical fibers 13 can be accurately connected by rotating relative to each other by 360° / N.

[0078] exist Figure 2 and Figure 4 Taking a multi-core optical fiber 13 with two first fiber cores 203 and two second fiber cores 204 as an example, in specific implementation, the number of first fiber cores 203 and second fiber cores 204 in the multi-core optical fiber 13 can be reasonably set according to actual needs. In some cases, when the number of first fiber cores 203 and second fiber cores 204 in the multi-core optical fiber 13 is large, the first fiber cores 203 and the second fiber cores 204 in the multi-core optical fiber 13 can also be distributed on multiple concentric ring layers, as long as the two multi-core optical fibers 13 can be accurately connected.

[0079] Furthermore, in some cases, the number of first cores 203 and the number of second cores 204 in the multi-core optical fiber 13 may not be equal. That is, the total number of first cores 203 and second cores 204 in the multi-core optical fiber 13 may also be an odd number. In practical applications, the number of first cores 203 and second cores 204 in the multi-core optical fiber 13 can be reasonably set according to actual needs, as long as the two multi-core optical fibers 13 can be accurately connected.

[0080] In this application embodiment, the first fiber core and the second fiber core can be implemented in various ways. The specific implementation methods of the first fiber core and the second fiber core in this application embodiment will be described in detail below with reference to the accompanying drawings.

[0081] Example 1

[0082] Figure 5 for Figure 4 The diagram shown illustrates the structural design of the first and second cores in a multi-core optical fiber. Figure 4 and Figure 5 In this embodiment of the application, the multi-core optical fiber 13 may include: a cladding 200, and at least one first fiber core 203 and at least one second fiber core 204 enclosed within the cladding 200. Figure 4 The multi-core optical fiber 13 is illustrated using an example of having two first fiber cores 203 and two second fiber cores 204. In one possible implementation, the first fiber core 203 may include a first core layer 301 and a first channel layer 302 surrounding the first core layer 301. The refractive index n1 of the first core layer 301 is greater than the refractive index n0 of the cladding 200, and the refractive index n0 of the cladding 200 is greater than the refractive index n2 of the first channel layer 302, i.e., n1 > n0 > n2.

[0083] The relative refractive index difference Δ1 between the first channel layer 302 and the first core layer 301 can satisfy: -0.7% ≤ Δ1 ≤ -0.3%, and the relative refractive index difference Δ1 is defined as:

[0084]

[0085] The relative refractive index difference Δ2 between the cladding layer 200 and the first core layer 301 can satisfy: -0.5% ≤ Δ2 ≤ -0.2%, and the relative refractive index difference Δ2 is defined as:

[0086]

[0087] The radius r1 of the first core layer 301 and the outer diameter r2 of the first channel layer 302 can satisfy: 5.0μm≤r1≤7.0μm, r1<r2≤25.0μm.

[0088] In this embodiment, the second core 204 may include a second core layer 41 and a second channel layer 42 surrounding the second core layer 41. The second core layer 41 may include at least three sub-core layers: a first sub-core layer 411, a second sub-core layer 412 surrounding the first sub-core layer 411, and a third sub-core layer 413 surrounding the second sub-core layer 412. The refractive index n3 of the first sub-core layer 411 is greater than the refractive index n4 of the second sub-core layer 412, and the refractive index n4 of the second sub-core layer 412 is greater than the refractive index n5 of the second channel layer 42, i.e., n3 > n4 > n5. Furthermore, the refractive index n3 of the first sub-core layer 411 is greater than the refractive index n6 of the third sub-core layer 413, and the refractive index n6 of the third sub-core layer 413 is greater than the refractive index n5 of the second channel layer 42, i.e., n3 > n6 > n5. By setting at least three sub-core layers in the second core layer 41 and reasonably setting the refractive index of each sub-core layer, the dispersion value of the second fiber core 204 can be controlled.

[0089] Among them, the radius r3 of the first sub-core layer 411 can satisfy: 1.4μm≤r3≤2.6μm, the outer diameter r4 of the second sub-core layer 412 satisfies: 6.0μm≤r4≤8.0μm, the outer diameter r5 of the third sub-core layer 413 and the outer diameter r6 of the second channel layer 42 satisfy: 6.5μm≤r5≤11.0μm, r5<r6≤25.0μm. The relative refractive index difference Δ3 between the first sub-core layer 411 and the first core layer 301 can satisfy: 0.43% ≤ Δ3 ≤ 0.55%; the relative refractive index difference Δ4 between the second sub-core layer 412 and the first core layer 301 can satisfy: -0.17% ≤ Δ4 ≤ -0.05%; the relative refractive index difference Δ5 between the third sub-core layer 413 and the first core layer 301 can satisfy: -0.35% ≤ Δ5 ≤ 0.13%; and the relative refractive index difference Δ6 between the second channel layer 42 and the first core layer 301 can satisfy: -0.7% ≤ Δ6 ≤ -0.3%. The relative refractive index differences Δ3, Δ4, Δ5, and Δ6 are defined as follows:

[0090] and

[0091] In this embodiment, by reasonably setting the refractive index and radius of each layer in the first fiber core 203 and the second fiber core 204, the first fiber core 203 can have a larger effective area, and the second fiber core 204 can have a lower dispersion value, thereby significantly reducing dispersion accumulation in the transmission link. The specific setting parameters of the first fiber core 203 and the second fiber core 204 in Embodiment 1 can be found in Table 1. In the technical solution of Embodiment 1 of this application, by reasonably setting the refractive index and radius of each layer in the first fiber core 203 and the second fiber core 204, the effective area A of the first fiber core 203 at 1550nm can be increased. eff Approximately 112 μm2 The dispersion value CD of the second fiber core 204 at 1550 nm is approximately 7.9 ps / (nm·km), and the cutoff wavelength λ of the first fiber core 203 is... c The cutoff wavelength λ of the second fiber core 204 is 1530nm. c It is 1420nm.

[0092] Table 1. Specific setting parameters of the first and second fiber cores in Example 1

[0093]

[0094] Example 2

[0095] Figure 6 This is another cross-sectional schematic diagram of the multi-core optical fiber in an embodiment of this application. Figure 7 for Figure 6 The diagram shown illustrates the structural design of the first and second cores in a multi-core optical fiber. Figure 6 and Figure 7 In this embodiment of the application, the multi-core optical fiber 13 may include: a cladding 200, and at least one first fiber core 203 and at least one second fiber core 204 enclosed within the cladding 200. Figure 6 The multi-core optical fiber 13 is illustrated using an example of having two first fiber cores 203 and two second fiber cores 204. In other implementations of this application, the first fiber core 203 may include: a first core layer 301, an inner cladding layer 303 surrounding the first core layer 301, and a first channel layer 302 surrounding the inner cladding layer 303. The refractive index n1 of the first core layer 301 is greater than the refractive index n7 of the inner cladding layer 303. The refractive index n7 of the inner cladding layer 303 may be greater than or equal to the refractive index n0 of the cladding layer 200, and the refractive index n0 of the cladding layer 200 is greater than the refractive index n2 of the first channel layer 302, i.e., n1 > n7 ≥ n0 > n2.

[0096] The relative refractive index difference Δ1 between the first channel layer 302 and the first core layer 301 can satisfy: -0.7% ≤ Δ1 ≤ -0.3%, and the relative refractive index difference Δ2 between the cladding layer 200 and the first core layer 301 can satisfy: -0.5% ≤ Δ2 ≤ -0.2%. The definitions of the relative refractive index differences Δ1 and Δ2 are as follows:

[0097]

[0098] The radius r1 of the first core layer 301, the outer diameter r2 of the first channel layer 302, and the outer diameter r7 of the inner cladding can satisfy: 5.0μm≤r1≤7.0μm, r1≤r7≤14.0μm, and r7<r2≤25.0μm.

[0099] In this embodiment, the second core 204 may include a second core layer 41 and a second channel layer 42 surrounding the second core layer 41. The second core layer 41 may include at least three sub-core layers: a first sub-core layer 411, a second sub-core layer 412 surrounding the first sub-core layer 411, and a third sub-core layer 413 surrounding the second sub-core layer 412. The refractive index n3 of the first sub-core layer 411 is greater than the refractive index n4 of the second sub-core layer 412, and the refractive index n4 of the second sub-core layer 412 is greater than the refractive index n5 of the second channel layer 42, i.e., n3 > n4 > n5. Furthermore, the refractive index n3 of the first sub-core layer 411 is greater than the refractive index n6 of the third sub-core layer 413, and the refractive index n6 of the third sub-core layer 413 is greater than the refractive index n5 of the second channel layer 42, i.e., n3 > n6 > n5. By setting at least three sub-core layers in the second core layer 41 and reasonably setting the refractive index of each sub-core layer, the dispersion value of the second fiber core 204 can be controlled.

[0100] Among them, the radius r3 of the first sub-core layer 411 can satisfy: 1.4μm≤r3≤2.6μm, the outer diameter r4 of the second sub-core layer 412 can satisfy: 6.0μm≤r4≤8.0μm, the outer diameter r5 of the third sub-core layer 413 and the outer diameter r6 of the second channel layer 42 can satisfy: 6.5μm≤r5≤11.0μm, r5<r6≤25.0μm. The relative refractive index difference Δ3 between the first sub-core layer 411 and the first core layer 301 can satisfy: 0.43% ≤ Δ3 ≤ 0.55%; the relative refractive index difference Δ4 between the second sub-core layer 412 and the first core layer 301 can satisfy: -0.17% ≤ Δ4 ≤ -0.05%; the relative refractive index difference Δ5 between the third sub-core layer 413 and the first core layer 301 can satisfy: -0.35% ≤ Δ5 ≤ 0.13%; and the relative refractive index difference Δ6 between the second channel layer 42 and the first core layer 301 can satisfy: -0.7% ≤ Δ6 ≤ -0.3%. The relative refractive index differences Δ3, Δ4, Δ5, and Δ6 are defined as follows:

[0101] and

[0102] In this embodiment, by reasonably setting the refractive index and radius of each layer in the first fiber core 203 and the second fiber core 204, the first fiber core 203 can have a larger effective area, and the second fiber core 204 can have a lower dispersion value, thereby significantly reducing dispersion accumulation in the transmission link. The specific setting parameters of the first fiber core 203 and the second fiber core 204 in Embodiment Two can be found in Table 2. In the technical solution of Embodiment Two of this application, by reasonably setting the refractive index and radius of each layer in the first fiber core 203 and the second fiber core 204, the effective area A of the first fiber core 203 at 1550nm can be increased. eff Approximately 112 μm2 The dispersion value CD of the second fiber core 204 at 1550 nm is approximately 8.3 ps / (nm·km), and the cutoff wavelength λ of the first fiber core 203 is... c The cutoff wavelength λ of the second fiber core 204 is 1520nm. c It is 1460nm.

[0103] Table 2 shows the specific setting parameters of the first and second fiber cores in Example 2.

[0104]

[0105] Example 3

[0106] Figure 8 This is another cross-sectional schematic diagram of the multi-core optical fiber in an embodiment of this application. Figure 8 The specific structural designs of the first and second fiber cores can be referred to Figure 7 , combined Figure 7 and 8 In this embodiment of the application, the multi-core optical fiber 13 may include: a cladding 200, and at least one first fiber core 203 and at least one second fiber core 204 enclosed within the cladding 200. Figure 8 The multi-core optical fiber 13 is illustrated using an example of a first fiber core 203 and a second fiber core 204. In other implementations of this application, the first fiber core 203 may include: a first core layer 301, an inner cladding layer 303 surrounding the first core layer 301, and a first channel layer 302 surrounding the inner cladding layer 303. The refractive index n1 of the first core layer 301 is greater than the refractive index n7 of the inner cladding layer 303. The refractive index n7 of the inner cladding layer 303 may be greater than or equal to the refractive index n0 of the cladding layer 200, and the refractive index n0 of the cladding layer 200 is greater than the refractive index n2 of the first channel layer 302, i.e., n1 > n7 ≥ n0 > n2.

[0107] The relative refractive index difference Δ1 between the first channel layer 302 and the first core layer 301 can satisfy: -0.7% ≤ Δ1 ≤ -0.3%, and the relative refractive index difference Δ2 between the cladding layer 200 and the first core layer 301 can satisfy: -0.5% ≤ Δ2 ≤ -0.2%. The definitions of the relative refractive index differences Δ1 and Δ2 are as follows:

[0108]

[0109] The radius r1 of the first core layer 301, the outer diameter r2 of the first channel layer 302, and the outer diameter r7 of the inner cladding can satisfy: 5.0μm≤r1≤7.0μm, r1≤r7≤14.0μm, and r7<r2≤25.0μm.

[0110] In this embodiment, the second core 204 may include a second core layer 41 and a second channel layer 42 surrounding the second core layer 41. The second core layer 41 may include at least three sub-core layers: a first sub-core layer 411, a second sub-core layer 412 surrounding the first sub-core layer 411, and a third sub-core layer 413 surrounding the second sub-core layer 412. The refractive index n3 of the first sub-core layer 411 is greater than the refractive index n4 of the second sub-core layer 412, and the refractive index n4 of the second sub-core layer 412 is greater than the refractive index n5 of the second channel layer 42, i.e., n3 > n4 > n5. Furthermore, the refractive index n3 of the first sub-core layer 411 is greater than the refractive index n6 of the third sub-core layer 413, and the refractive index n6 of the third sub-core layer 413 is greater than the refractive index n5 of the second channel layer 42, i.e., n3 > n6 > n5. By setting at least three sub-core layers in the second core layer 41 and reasonably setting the refractive index of each sub-core layer, the dispersion value of the second fiber core 204 can be controlled.

[0111] Among them, the radius r3 of the first sub-core layer 411 can satisfy: 1.4μm≤r3≤2.6μm, the outer diameter r4 of the second sub-core layer 412 can satisfy: 6.0μm≤r4≤8.0μm, the outer diameter r5 of the third sub-core layer 413 and the outer diameter r6 of the second channel layer 42 can satisfy: 6.5μm≤r5≤11.0μm, r5<r6≤25.0μm. The relative refractive index difference Δ3 between the first sub-core layer 411 and the first core layer 301 can satisfy: 0.43% ≤ Δ3 ≤ 0.55%; the relative refractive index difference Δ4 between the second sub-core layer 412 and the first core layer 301 can satisfy: -0.17% ≤ Δ4 ≤ -0.05%; the relative refractive index difference Δ5 between the third sub-core layer 413 and the first core layer 301 can satisfy: -0.35% ≤ Δ5 ≤ 0.13%; and the relative refractive index difference Δ6 between the second channel layer 42 and the first core layer 301 can satisfy: -0.7% ≤ Δ6 ≤ -0.3%. The relative refractive index differences Δ3, Δ4, Δ5, and Δ6 are defined as follows:

[0112] and

[0113] In this embodiment, by reasonably setting the refractive index and radius of each layer in the first fiber core 203 and the second fiber core 204, the first fiber core 203 can have a larger effective area, and the second fiber core 204 can have a lower dispersion value, thereby significantly reducing dispersion accumulation in the transmission link and improving the transmission performance of the signal light. The specific setting parameters of the first fiber core 203 and the second fiber core 204 in Embodiment 3 can be found in Table 3. In the technical solution of Embodiment 3 of this application, by reasonably setting the refractive index and radius of each layer in the first fiber core 203 and the second fiber core 204, the effective area A of the first fiber core 203 at 1550nm can be increased. effApproximately 131 μm 2 The dispersion value CD of the second fiber core 204 at 1550 nm is approximately 7.9 ps / (nm·km), and the cutoff wavelength λ of the first fiber core 203 is... c The cutoff wavelength λ of the second fiber core 204 is 1530nm. c It is 1530nm.

[0114] Table 3. Specific setting parameters of the first and second fiber cores in Example 3

[0115]

[0116] The above describes the specific implementation of the first and second fiber cores in the embodiments of this application, using examples one to three. In actual implementation, the radius and refractive index of each layer in the first and second fiber cores can be reasonably set according to actual needs, and will not be listed one by one here.

[0117] The preceding text detailed the specific implementation methods of the first and second multi-core optical fibers in the aforementioned communication system. In some cases, the communication system can also incorporate more multi-core optical fibers. For example, a third multi-core optical fiber can be fused to the end of the second multi-core optical fiber furthest from the first multi-core optical fiber; similarly, a fourth multi-core optical fiber can be fused to the end of the first multi-core optical fiber furthest from the second multi-core optical fiber. In specific configurations, the dispersion value of each fiber core can be appropriately set according to actual needs. Alternatively, the communication system can employ multiple interconnected first and second multi-core optical fibers, configured according to actual signal transmission requirements.

[0118] Based on the same technical concept, this application also provides another communication system. Figure 9 Another schematic diagram of the communication system provided in the embodiments of this application is shown below. Figure 9 As shown, in some other embodiments of this application, the communication system may include: a signal transmitter, a signal receiver, and a first multi-core optical fiber 131 and a second multi-core optical fiber 132 connected between the signal transmitter and the signal receiver. The signal transmitter and signal receiver are in... Figure 9 The settings for the signal transmitter and receiver are not shown in the diagram. Please refer to [reference needed]. Figure 1As shown. The first multi-core optical fiber 131 may include a first cladding 201 and a plurality of first fiber cores 203 enclosed within the first cladding 201. The second multi-core optical fiber 132 may include a second cladding 202 and a plurality of second fiber cores 204 enclosed within the second cladding 202. The dispersion value of each second fiber core 204 is less than the dispersion value of any of the first fiber cores 203. The ends of the first multi-core optical fiber 131 and the ends of the second multi-core optical fiber 132 are fused together, and the first fiber cores 203 in the first multi-core optical fiber 131 are connected to the second fiber cores 204 in the second multi-core optical fiber 132.

[0119] In this embodiment, the dispersion value of each second fiber core 204 is less than the dispersion value of any first fiber core 203. Typically, the dispersion value of an optical fiber (or fiber core) is related to its effective area. Reducing the dispersion value of the optical fiber sacrifices its effective area; that is, in this embodiment, the effective area of ​​the second fiber core 204 is less than the effective area of ​​the first fiber core 203. However, the smaller the effective area of ​​the optical fiber, the greater the nonlinear accumulation during signal light transmission. Due to the smaller effective area of ​​the second fiber core 204, if the optical power of the signal light in the second fiber core 204 is high, a large nonlinear accumulation will occur, resulting in poor signal light performance. In this embodiment, the signal light transmission in the communication system is directional. During the transmission of the signal light in the first multi-core optical fiber 131 and the second multi-core optical fiber 132, the signal light first passes through the first fiber core 203 and then through the second fiber core 204 connected to the first fiber core 203. After the signal light propagates in the first fiber core 203, its optical power attenuates to a certain extent. Therefore, the optical power of the signal light entering the second fiber core 204 is relatively low, resulting in less nonlinear accumulation during transmission in the second fiber core 204 and preventing significant performance degradation. Furthermore, the second fiber core 204 has a lower dispersion value, which significantly reduces dispersion accumulation in the transmission link. Therefore, the technical solution provided in this application embodiment can significantly reduce dispersion accumulation in the transmission link without significant performance degradation, thus alleviating the power consumption of dispersion compensation in the digital signal processing module.

[0120] Continue to refer to Figure 9 Because the dispersion values ​​of the cores in the first multi-core fiber 131 and the second multi-core fiber 132 are different, after fusion splicing the first multi-core fiber 131 and the second multi-core fiber 132, the first core 203 in the first multi-core fiber 131 is connected to the second core 204 in the second multi-core fiber 132, allowing the signal light to travel along... Figure 9 The direction of transmission is indicated by the dashed arrow F1. In practical implementation, it can be... Figure 9 Based on the structure shown, a first multi-core optical fiber 131 and a second multi-core optical fiber 132 are added and interconnected, with the signal light transmission direction opposite to that of arrow F1, thereby enabling bidirectional transmission in the communication system. Of course, it is also possible to... Figure 9 Based on the structure shown, more first multi-core optical fibers 131 and second multi-core optical fibers 132 can be added. The configuration can be adjusted according to actual needs and is not limited here.

[0121] In this embodiment, the specific configuration of the first multi-core optical fiber 131 and the second multi-core optical fiber 132 can be implemented with reference to the above description, and the repeated parts will not be described again.

[0122] Figure 10 This is another cross-sectional schematic diagram of the multi-core optical fiber in an embodiment of this application, with reference to... Figure 10 A multi-core optical fiber in this embodiment may include: a second cladding 202, and a plurality of second cores 204 encased in the second cladding 202. When the operating wavelength of the multi-core optical fiber is 1550 nm, the dispersion value of each second core 204 is greater than 4 ps / (nm·km), and the dispersion value of each second core 204 is less than 23 ps / (nm·km). That is, Figure 10 The multi-core optical fiber shown can be Figure 9 The second multi-core fiber 132, Figure 10 The specific implementation method of the multi-core optical fiber shown can be referred to the above. Figure 9 The description of the second multi-core fiber 132 is repeated here, and the details will not be repeated.

[0123] Based on the same technical concept, this application also provides an optical cable. The optical cable in this application embodiment may include: a sheath, and at least one multi-core optical fiber (either the first multi-core optical fiber or the second multi-core optical fiber), with the sheath covering the at least one multi-core optical fiber. The optical cable in this application embodiment can be a normal-sized optical cable, or it can be a thinner micro-cable.

[0124] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0125] Obviously, those skilled in the art can make various modifications and variations to the embodiments of this application without departing from the spirit and scope of the embodiments of this application. Therefore, if these modifications and variations to the embodiments of this application fall within the scope of the claims of this application and their equivalents, this application also intends to include these modifications and variations.

Claims

1. A multi-core optical fiber, characterized in that, include: Cladding; At least one first fiber core and at least one second fiber core are enclosed within the cladding layer; The dispersion value of each of the second fiber cores is less than the dispersion value of any of the first fiber cores.

2. The multi-core optical fiber as described in claim 1, characterized in that, In the multi-core optical fiber, the number of the first fiber cores is equal to the number of the second fiber cores; The first and second cores of the multi-core optical fiber are alternately distributed on the concentric ring layer of the cladding.

3. The multi-core optical fiber as described in claim 1 or 2, characterized in that, When the operating wavelength of the multi-core optical fiber is 1550nm, the dispersion value of the first core is less than 23ps / (nm·km), and the dispersion value of the second core is greater than 4ps / (nm·km).

4. The multi-core optical fiber as described in any one of claims 1 to 3, characterized in that, The effective area of ​​each second fiber core is smaller than the effective area of ​​any first fiber core.

5. The multi-core optical fiber as described in claim 4, characterized in that, When the operating wavelength of the multi-core optical fiber is 1550 nm, the effective area of ​​the first core is greater than or equal to 100 μm. 2 The effective area of ​​the second fiber core is greater than or equal to 60 μm. 2 .

6. The multi-core optical fiber as described in any one of claims 1 to 5, characterized in that, The first fiber core includes: a first core layer, and a first channel layer wrapped around the outside of the first core layer; The refractive index of the first core layer is greater than that of the cladding layer, and the refractive index of the cladding layer is greater than that of the first channel layer.

7. The multi-core optical fiber as described in claim 6, characterized in that, The relative refractive index difference Δ1 between the first channel layer and the first core layer satisfies: -0.7% ≤ Δ1 ≤ -0.3%, and the relative refractive index difference Δ2 between the cladding layer and the first core layer satisfies: -0.5% ≤ Δ2 ≤ -0.2%. The radius r1 of the first core layer and the outer diameter r2 of the first channel layer satisfy: 5.0μm≤r1≤7.0μm, r1<r2≤25.0μm.

8. The multi-core optical fiber as described in claim 6, characterized in that, The first fiber core further includes: an inner cladding layer wrapped around the outside of the first core layer, and the first channel layer wrapped around the outside of the inner cladding layer; The refractive index of the inner cladding is less than that of the first core layer, and the refractive index of the inner cladding is greater than or equal to that of the cladding.

9. The multi-core optical fiber as described in claim 8, characterized in that, The relative refractive index difference Δ1 between the first channel layer and the first core layer satisfies: -0.7% ≤ Δ1 ≤ -0.3%, and the relative refractive index difference Δ2 between the cladding layer and the first core layer satisfies: -0.5% ≤ Δ2 ≤ -0.2%. The radius r1 of the first core layer, the outer diameter r2 of the first channel layer, and the outer diameter r7 of the inner cladding layer satisfy the following conditions: 5.0μm≤r1≤7.0μm, r1≤r7≤14.0μm, and r7<r2≤25.0μm.

10. The multi-core optical fiber according to any one of claims 1 to 9, characterized in that, The second fiber core includes: a second core layer, and a second channel layer wrapped around the outside of the second core layer; The second core layer includes: a first sub-core layer, a second sub-core layer wrapped around the outside of the first sub-core layer, and a third sub-core layer wrapped around the outside of the second sub-core layer; The refractive index of the first sub-core layer is greater than that of the second sub-core layer, the refractive index of the first sub-core layer is greater than that of the third sub-core layer, the refractive index of the second sub-core layer is greater than that of the second channel layer, and the refractive index of the third sub-core layer is greater than that of the second channel layer.

11. The multi-core optical fiber as described in claim 10, characterized in that, The radius r3 of the first sub-core layer satisfies: 1.4μm≤r3≤2.6μm, the outer diameter r4 of the second sub-core layer satisfies: 6.0μm≤r4≤8.0μm, and the outer diameter r5 of the third sub-core layer and the outer diameter r6 of the second channel layer satisfy: 6.5μm≤r5≤11.0μm, r5<r6≤25.0μm; The relative refractive index difference Δ3 between the first sub-core layer and the first core layer satisfies: 0.43% ≤ Δ3 ≤ 0.55%; the relative refractive index difference Δ4 between the second sub-core layer and the first core layer satisfies: -0.17% ≤ Δ4 ≤ -0.05%; the relative refractive index difference Δ5 between the third sub-core layer and the first core layer satisfies: -0.35% ≤ Δ5 ≤ 0.13%; and the relative refractive index difference Δ6 between the second channel layer and the first core layer satisfies: -0.7% ≤ Δ6 ≤ -0.3%.

12. A communication system, characterized in that, include: A signal transmitter, a signal receiver, and a first multi-core optical fiber and a second multi-core optical fiber connected between the signal transmitter and the signal receiver; The first multi-core optical fiber includes: a first cladding, and at least one first core and at least one second core wrapped within the first cladding, wherein the dispersion value of each second core is less than the dispersion value of any of the first cores; The second multi-core optical fiber includes: a second cladding, and at least one first core and at least one second core enclosed within the second cladding; The ends of the first multi-core optical fiber and the second multi-core optical fiber are fused together. The first core of the first multi-core optical fiber is connected to the second core of the second multi-core optical fiber, and the second core of the first multi-core optical fiber is connected to the first core of the second multi-core optical fiber.

13. A communication system, characterized in that, include: A signal transmitter, a signal receiver, and a first multi-core optical fiber and a second multi-core optical fiber connected between the signal transmitter and the signal receiver; The first multi-core optical fiber includes: a first cladding, and a plurality of first fiber cores enclosed within the first cladding; The second multi-core optical fiber includes: a second cladding, and a plurality of second fiber cores enclosed within the second cladding; The dispersion value of each of the second fiber cores is less than the dispersion value of any of the first fiber cores; The end of the first multi-core optical fiber is fused to the end of the second multi-core optical fiber, and the first core of the first multi-core optical fiber is connected to the second core of the second multi-core optical fiber.

14. A multi-core optical fiber, characterized in that, include: Second cladding; Multiple second fiber cores enclosed within the second cladding layer; When the operating wavelength of the multi-core optical fiber is 1550nm, the dispersion value of each second fiber core is greater than 4ps / (nm·km), and the dispersion value of each second fiber core is less than 23ps / (nm·km).

15. An optical cable, characterized in that, The optical cable includes: a sheath, and at least one multi-core optical fiber as described in any one of claims 1 to 11; or, the optical cable includes: a sheath, and at least one multi-core optical fiber as described in claim 14. The sheath encloses the at least one multi-core optical fiber.

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