Optical fiber preform, optical fiber, optical amplification unit and device

Abstract

An optical fiber preform, optical fiber, optical amplification unit, and device are disclosed, belonging to the field of optical communication technology. The optical fiber preform includes a cladding and multiple fiber cores; each fiber core is encased within the cladding, and the fiber cores are arranged in parallel and spaced intervals, including at least two types of fiber cores; the fiber cores are used to receive signal light and pump light, and to amplify the power of the signal light according to the pump light. This application solves the problem of poor power amplification effect for L-band signal light in related technologies, and is used for signal light amplification.

Description

Technical Field

[0001] This application relates to the field of optical communication technology, and in particular to an optical fiber preform, an optical fiber, an optical amplification unit, and a device. Background Technology

[0002] With the development of optical communication technology, the wavelengths of signal light used for communication have been gradually expanded. For example, the wavelength range of the C band (1530 nm to 1565 nm) has been expanded to the C+L band (1530 nm to 1625 nm), where the wavelength range of the L band is 1565 nm to 1625 nm.

[0003] In related technologies, signal light requires power amplification using an optical amplifier during transmission. This optical amplifier includes an optical fiber, which amplifies the power of the signal light transmitted through its core based on a pump light.

[0004] However, the fiber core is currently suitable for power amplification of C-band signals, but not for power amplification of L-band signals. Therefore, the power amplification effect of L-band signals in related technologies is poor. Summary of the Invention

[0005] This application provides an optical fiber preform, an optical fiber, an optical amplification unit, and a device, which can solve the problem of poor power amplification effect for L-band signal light in related technologies.

[0006] In a first aspect, an optical fiber preform is provided, the optical fiber preform comprising a cladding and multiple fiber cores; the multiple fiber cores are all encased within the cladding and are arranged in parallel and spaced apart, the multiple fiber cores comprising at least two types of fiber cores; each fiber core is used to receive signal light and pump light, and to amplify the power of the signal light according to the pump light.

[0007] Since the optical fiber preform includes at least two types of cores, the optical fiber drawn from it also includes at least two types of cores. Furthermore, because different types of cores are suitable for power amplification of signal light at different wavelengths, the optical fiber drawn from this preform can be used to amplify the power of signal light at least two wavelengths, thus solving the problem that a single core cannot amplify the power of signal light at different wavelengths. Moreover, the power amplification effect of this optical fiber on signal light at different wavelengths is comparable to the power amplification effect of using different single-core optical fibers with different cores on signal light at different wavelengths.

[0008] Optionally, different types of fiber cores may have different parameters in at least one of the following: material, refractive index distribution, structure, and cross-sectional dimensions, wherein the cross-section is perpendicular to the fiber core axis.

[0009] Optionally, the multiple fiber cores include at least one of the following: erbium-doped fiber core, bismuth-doped fiber core, erbium-bismuth-doped fiber core, and nonlinear fiber core.

[0010] Optionally, the cladding includes a first sub-cladding and a second sub-cladding, with the first sub-cladding enclosing the second sub-cladding, and multiple fiber cores enclosing within the second sub-cladding; this configuration is suitable for cladding-pumped pumped light. Alternatively, the cladding is not divided into a first sub-cladding and a second sub-cladding, in which case multiple fiber cores are enclosing within the cladding; this configuration is suitable for core-pumped pumped light.

[0011] In a second aspect, an optical fiber is provided, which is drawn from an optical fiber preform as described in any of the designs in the first aspect.

[0012] Thirdly, an optical amplification unit is provided, comprising: a passive device group and at least one optical fiber; each optical fiber includes a cladding and multiple fiber cores encased within the cladding, the multiple fiber cores being arranged in parallel and spaced apart, and the at least one optical fiber including at least two types of fiber cores; for example, each optical fiber in the at least one optical fiber includes at least two types of fiber cores. The n target fiber cores in the aforementioned at least one optical fiber are used to receive n corresponding signal beams, where n≥1; the passive device group is used to couple the pump light corresponding to each target fiber core into the optical fiber containing that target fiber core; the target fiber core is used to amplify the received signal light based on the corresponding pump light and then output it.

[0013] The optical amplification unit provided in this application includes a passive device group and at least one optical fiber. This at least one optical fiber contains at least two types of fiber cores. Different types of fiber cores are suitable for power amplification of signal light in different wavelength bands. Therefore, this optical amplification unit supports power amplification of signal light in different wavelength bands using different target fiber cores, thus effectively amplifying the power of signal light in different wavelength bands. Furthermore, the power amplification effect of using the optical amplification unit provided in this application to amplify signal light in different wavelength bands is comparable to the power amplification effect of using different single-core optical fibers with different fiber cores to amplify signal light in different wavelength bands.

[0014] Furthermore, when at least one target fiber core includes multiple target fiber cores belonging to the same optical fiber, compared to the case where the multiple target fiber cores belong to different optical fibers, the multiple target fiber cores can share the passive devices set on the same optical fiber. Therefore, the number of passive devices included in the passive device group is smaller, the maintenance complexity is lower, and the cost is also lower.

[0015] Optionally, different types of fiber cores may have different parameters in at least one of the following: material, refractive index distribution, structure, and cross-sectional dimensions, wherein the cross-section is perpendicular to the fiber core axis.

[0016] Optionally, the aforementioned at least one optical fiber includes: a rare-earth-doped fiber core and / or a nonlinear fiber core (such as a highly nonlinear fiber core, which is suitable for Raman amplification). The rare-earth-doped fiber core may include: erbium-doped fiber core, bismuth-doped fiber core, erbium-bismuth-doped fiber core, thulium-doped fiber core, neodymium-doped fiber core, etc. This application can select some technologically mature fiber cores based on technological developments to ensure the power amplification effect of the fiber core on the signal light. For example, the fiber core may be at least one of erbium-doped fiber core, bismuth-doped fiber core, and nonlinear fiber core.

[0017] Furthermore, the n target fiber cores to which the aforementioned n signal beams are transmitted can be of the same or different types. For example, the aforementioned n signal beams can be divided into multiple groups of signal beams. Each group of signal beams includes at least one signal beam (such as one signal beam or multiple signal beams) with a specific wavelength band. Different groups of signal beams have different wavelength bands, and each group of signal beams corresponds to a specific type of target fiber core. Different groups of signal beams correspond to different types of target fiber cores. In this way, signal beams of different wavelength bands are transmitted to different types of target fiber cores, enabling the different types of target fiber cores to effectively amplify the power of the signal beams of different wavelength bands.

[0018] The n target fiber cores corresponding to the aforementioned multiple sets of signal lights can belong to one or more optical fibers. For example, the aforementioned multiple sets of signal lights correspond to target fiber cores in one optical fiber. Alternatively, each of the aforementioned multiple sets of signal lights corresponds to a target fiber core in one optical fiber, and different sets of signal lights correspond to target fiber cores in different optical fibers.

[0019] Optionally, the optical amplification unit includes a first transmission connector. The first transmission connector can be a passive or active device. When the first transmission connector is a passive device, it is included in the passive device group. The first transmission connector is used to receive m signal lights, obtain the aforementioned n signal lights based on the m signal lights, and transmit the n signal lights one-to-one to the aforementioned n target fiber cores. Therefore, without the first transmission connector, the optical amplification unit is suitable for amplifying the n signal lights; with the first transmission connector, the optical amplification unit is suitable for amplifying the m signal lights. Where n > m ≥ 1, one of the n signal lights includes at least a portion of the wavelength bands of the signal light in one of the m signal lights. Optionally, the m signal lights include multiple signal lights with the same wavelength band, or the m signal lights include multiple signal lights with different wavelength bands, or the m signal lights include one signal light.

[0020] Optionally, the optical amplification unit includes a second transmission connector; the second transmission connector can be a passive or active device. When the second transmission connector is a passive device, it is included in the passive device group. The second transmission connector is used to receive the signal light (power-amplified signal light) output from the n target fiber cores, and output the power-amplified m-channel signal light according to the signal light received by the second transmission connector. Therefore, without the second transmission connector, the optical amplification unit outputs n-channel amplified signal light; with the second transmission connector, the optical amplification unit outputs m-channel amplified signal light.

[0021] The pump light corresponding to the target fiber core can be core-pumped, cladding-pumped, or a combination of core-pumped and cladding-pumped; this application does not limit this. Specifically, when the target fiber core is a nonlinear fiber core, the pump light in the core-pumped mode is a Raman-amplified pump light.

[0022] The following explanation will take the i-th target fiber core out of the above n target fiber cores as an example to illustrate the pump light corresponding to the target fiber core.

[0023] When the pump light corresponding to the i-th target fiber core is in the form of a core pump, the above-mentioned passive device group is used to couple the pump light corresponding to the i-th target fiber core to the i-th target fiber core.

[0024] When the pump light corresponding to the cladding pump of the i-th target fiber core is used, the cladding of the i-th target fiber core among the n target fiber cores includes a first sub-cladding and a second sub-cladding. The first sub-cladding wraps the second sub-cladding, and the i-th target fiber core is wrapped inside the second sub-cladding, where n > i ≥ 1. The passive device group is used to couple the pump light corresponding to the i-th target fiber core to the second sub-cladding.

[0025] When the pump light corresponding to the i-th target fiber core is in the form of a core pump + cladding pump, the above-mentioned passive device group is used to simultaneously couple the pump light corresponding to the i-th target fiber core to the i-th target fiber core and the above-mentioned second sub-cladding.

[0026] When the pump light corresponding to the i-th target fiber core includes a cladding pump, the pump light corresponding to the i-th target fiber core can be a multimode pump light. Since the pump source providing multimode pump light has lower cost and simpler structure, when the optical amplification unit includes this pump source, the optical amplification unit has lower cost and simpler structure.

[0027] Optionally, the optical amplification unit may also include a pump source corresponding to the target fiber core, which provides pump light for the target fiber core. Alternatively, the optical amplification unit may not include this pump source, in which case the optical amplification unit will be smaller and have a simpler structure.

[0028] Optionally, the n signal beams include signal beams from at least two of the following wavelength bands: 1530 nm to 1565 nm, 1565 nm to 1625 nm, 1360 nm to 1460 nm, and 1460 nm to 1530 nm. Of course, the aforementioned n signal beams may also include signal beams from other wavelength bands besides these, and this application does not limit this.

[0029] Fourthly, this application provides an optical amplification device, which includes: a plurality of cascaded optical amplification units, at least one of which is an optical amplification unit as described in any of the designs in the third aspect; the optical amplification unit is used to amplify the power of the received signal light, and the j-th optical amplification unit among the plurality of optical amplification units is used to transmit the output signal light to the (j+1)-th optical amplification unit, where j≥1.

[0030] The effects of the corresponding designs in the first to fourth aspects mentioned above can be referenced from each other, and will not be elaborated upon here. Attached Figure Description

[0031] Figure 1 A schematic diagram illustrating the gain wavelength of a fiber core doped with different elements, provided as an embodiment of this application;

[0032] Figure 2 This is a schematic diagram illustrating how multiple optical amplifiers amplify signal light of different wavelength bands, as provided in an embodiment of this application.

[0033] Figure 3 A schematic diagram of an ErBi-doped fiber core provided for an embodiment of this application;

[0034] Figure 4 This is a schematic diagram of the structure of the optical amplification unit provided in the embodiments of this application;

[0035] Figure 5 A schematic diagram of a cross-section of an optical fiber provided in an embodiment of this application;

[0036] Figure 6 A schematic cross-sectional view of another optical fiber provided in an embodiment of this application;

[0037] Figure 7 A schematic cross-sectional view of another optical fiber provided in an embodiment of this application;

[0038] Figure 8 A schematic cross-sectional view of another optical fiber provided in an embodiment of this application;

[0039] Figure 9 A schematic cross-sectional view of another optical fiber provided in an embodiment of this application;

[0040] Figure 10This is a schematic diagram of another optical amplification unit provided in an embodiment of this application;

[0041] Figure 11 This is a schematic diagram of another optical amplification unit provided in an embodiment of this application;

[0042] Figure 12 This is a schematic diagram of another optical amplification unit provided in an embodiment of this application;

[0043] Figure 13 A schematic diagram of a cladding layer provided in an embodiment of this application;

[0044] Figure 14 This is a schematic diagram of the structure of an optical amplification device provided in an embodiment of this application. Detailed Implementation

[0045] In optical communication, a single band of signal light is typically used for communication, such as the C-band (1530 nm to 1565 nm).

[0046] With the development of optical communication technology, the communication bands have gradually expanded. For example, from the C-band to the C+L band and E+S band, the L-band ranges from 1565 nm to 1625 nm, the E-band from 1360 nm to 1460 nm, and the S-band from 1460 nm to 1530 nm. The C+L band spectrum has increased to 12 terahertz (THz). From the C-band to the C+L band, and then to the E+S band, each generation represents an expansion of the previous generation to adapt to the increasing demands of data transmission. The development of C+L band transmission technology with a transmission rate of 400 gigabits per second (Gbps) marks the beginning of the ultra-wideband era for optical fiber communication, supporting wider spectrum and achieving higher speeds and greater capacity.

[0047] Band expansion, also known as fiber optic spectrum spreading, increases the number of transmission bands in an optical fiber, enabling the transmission of more signals on a single fiber and thus significantly increasing capacity. This not only improves fiber optic utilization efficiency and reduces costs but also supports the development of emerging technologies such as 5G and the Internet of Things (IoT). Simultaneously, fiber optic spectrum spreading enhances network flexibility and scalability, and has a positive impact on environmental sustainability. In short, fiber optic spectrum spreading is key to building future communication networks, meeting bandwidth demands, and driving technological advancement. Fiber optic spectrum spreading enables fiber optic capacity expansion, which is crucial for handling surges in internet traffic, especially with the increasing prevalence of bandwidth-intensive applications such as cloud computing, big data, and high-definition video. Fiber optic capacity expansion improves data transmission rates, meets bandwidth requirements, and ensures network smoothness and a better user experience.

[0048] During signal light transmission in optical fibers, power amplification is typically required. For example, this can be achieved using an optical amplifier in a laser before transmission, or in an amplification base station during transmission. An optical amplifier usually consists of an optical fiber, a pump source, and a pump coupler. The pump coupler couples the pump light from the pump source to the fiber core. The signal light to be amplified is transmitted to the fiber core, where it is then amplified by the pump light before being output. The fiber core is related to the amplified signal light; for example, in the case of C-band signal light, the fiber core is typically erbium-doped (Er) core.

[0049] However, with the expansion of wavelengths, some problems have arisen in the power amplification of signal light. For example, traditional fiber cores used for power amplification of C-band signal light cannot meet the amplification requirements of signal light in other wavelengths (such as L-band). If Er-doped fiber cores suitable for power amplification of L-band signal light are used, then these Er-doped fiber cores cannot meet the amplification requirements of C-band signal light. It is clear that different fiber cores are needed to meet the amplification requirements of signal light in different wavelength bands.

[0050] For example, the gain wavelength of fiber cores doped with different elements is as follows: Figure 1 As shown, the horizontal axis represents the gain wavelength in nanometers; the vertical axis represents the doping elements, namely holmium (Ho), thulium (Tm), erbium (Er), bismuth (Bi), ytterbium (Yb), and neodymium (Nd). Figure 1 It can be seen that the gain wavelength of the Er-doped fiber core is located in the C-band (1530 nm to 1565 nm), while the gain wavelength of the Bi-doped fiber core is located in the L-band (1565 nm to 1625 nm). Therefore, Er-doped fiber cores are suitable for power amplification of C-band signal light, while Bismuth-doped fiber cores are suitable for power amplification of L-band signal light.

[0051] If it is necessary to amplify the power of the spread spectrum signal light, then the signal light of different bands can be separated, and then the signal light of different bands can be amplified by optical amplifiers with different fiber cores. Finally, the signal light of these bands after power amplification can be combined.

[0052] However, in addition to optical fibers, pump sources, and pump couplers, optical amplifiers also include passive components such as isolators, gain flattening filters (GFFs), and variable optical attenuators (VOAs). As the number of wavelength bands increases, the number of optical amplifiers also increases, and the number of passive components required increases exponentially with the number of wavelength bands, leading to increased maintenance complexity and higher costs.

[0053] For example, such as Figure 2 As shown, after the C+L band signal light is transmitted to the first fiber interface unit (FIU), it is split into C-band and L-band signal light by the FIU. Then, the C-band signal light is transmitted to a C120 optical amplifier (C120 OA) for power amplification, and the L-band signal light is transmitted to an L120 optical amplifier (L120 OA) for power amplification. Afterwards, the amplified C-band and L-band signal lights are respectively transmitted to the second FIU for output. Therefore, a total of two optical amplifiers, C120 OA and L120 OA, are required. Each optical amplifier requires one set of passive components, and the two optical amplifiers require two sets of passive components in total.

[0054] Therefore, there is an urgent need for an integrated amplifier. An integrated amplifier only requires a single optical fiber and a set of passive components, and it can effectively amplify signals from different wavelengths, meeting the amplification requirements of signals from different wavelengths. Therefore, the number of passive components can be reduced.

[0055] In related technologies, integrated optical amplifiers suitable for amplifying C+L band signal light use ErBi-doped fiber cores; these fibers are called ErBi-doped fibers. The Er element in the ErBi-doped core amplifies the power of C-band signal light, while the Bi element, when combined with other elements (such as germanium (Ge), silicon (Si), phosphorus (P), and Al), amplifies the power of L-band signal light. Er and Bi elements are co-doped (uniform doping) or cyclic doping (Er element surrounding Bi element, or Bi element surrounding Er element) into the same fiber core. Taking cyclic doping as an example... Figure 3 As shown, an ErBi-doped fiber comprises: an Er-doped core, a Bi-doped core, an inner cladding, and an outer cladding. The Er-doped core encloses the Bi-doped core, with the Er-doped cores separated by the inner cladding, and the outer cladding surrounds the Er-doped core.

[0056] However, amplifying the power of signals from different wavelengths within the same fiber core is extremely difficult. Fibers doped with different materials in the same core are challenging to model theoretically, resulting in long and uncertain development cycles. For example, ErBi-doped fiber cores have been studied for over a decade, but their practical application still faces numerous difficulties.

[0057] When Er and Bi elements are co-doped into the same fiber core, the elements interfere with each other, their concentrations restrict each other, and decoupling is impossible, affecting the amplification efficiency of C-band and L-band signal light. Even when using... Figure 3 The cyclic doping scheme shown, which separates Er and Bi, cannot avoid performance degradation. For example, when Er and Bi are cyclically doped into the same fiber core, aluminum (Al) will also be doped into the Er-doped core; germanium (Ge), silicon (Si), phosphorus (P), and Al will also be doped into the Bi-doped core. The Al in the Er-doped core will diffuse into the Bi-doped core, affecting the bonding of Bi with germanium (Ge), silicon (Si), phosphorus (P), and Al in the Bi-doped core, thereby affecting the power amplification efficiency of the Bi-doped core for L-band signal light.

[0058] Furthermore, Er is non-volatile at high temperatures, while Bi is highly volatile, leading to an imbalance in the Er-to-Bi ratio in ErBi-doped fibers. Simply increasing the Bi doping concentration can cause cluster quenching, increasing unsaturated loss (background loss) and reducing the efficiency of the optical amplifier.

[0059] It is evident that the performance of current ErBi-doped optical fibers is relatively poor, and the power amplification effect of ErBi-doped fibers for the C-band and L-band remains insufficient to meet requirements. Furthermore, more than a decade has passed since the initial research on ErBi-doped optical fibers began, yet they have not been used in products. Even disregarding the performance of ErBi-doped optical fibers, whether they meet the long-term reliability requirements in the communications field remains unknown.

[0060] This application provides an optical amplification unit (also called an optical amplifier) ​​that can amplify the power of signal light in different bands. In some embodiments, the optical amplification unit uses a single optical fiber (called an integrated optical fiber). In this case, the number of passive devices (such as isolators, VOAs, etc.) required by the optical amplification unit is small, the maintenance complexity is low, and the cost is also low.

[0061] For example, Figure 4 This is a schematic diagram of the structure of the optical amplification unit provided in the embodiments of this application, as shown below. Figure 4 As shown, the optical amplification unit includes: a passive device group 01 and at least one optical fiber 02; Figure 4Taking one optical fiber 02 as an example, it can be understood that the number of optical fibers 02 can also be greater than 1, such as 2, 3, 4, etc.

[0062] Figure 5 This is a schematic cross-sectional view of an optical fiber 02 provided in an embodiment of this application. The cross-section is perpendicular to the fiber core axis. Figure 5 As shown, the optical fiber 02 includes a cladding 021 and multiple fiber cores 022 wrapped within the cladding 021. The multiple fiber cores 022 are arranged in parallel and spaced apart. The first optical fiber 02 is an integrated optical fiber. Figure 5 Taking optical fiber 02 as an example, which includes two fiber cores 022, optical fiber 02 may optionally include more fiber cores 022. For example, when optical fiber 02 includes 3, 7, or 13 fiber cores 022, the schematic diagram of the cross-section of optical fiber 02 can be shown as follows. Figure 6 , Figure 7 , Figure 8 , Figure 9 As shown. From Figures 5 to 9 As can be seen from this, when optical fiber 02 includes multiple fiber cores 022, these fiber cores 022 can be evenly distributed within the cladding 021.

[0063] The aforementioned at least one optical fiber 02 includes at least two types of fiber cores 022. For example, each of the aforementioned at least one optical fiber 02 includes at least two types of fiber cores 022; or, each of the aforementioned at least one optical fiber 02 includes one type of fiber core 022, and different optical fibers 02 include different types of fiber cores 022.

[0064] Different types of fiber cores (022) exhibit varying power amplification effects and gains for signal light of the same wavelength. Different types of fiber cores (022) can be used to amplify the power of signal light in different wavelength bands. For example, different types of fiber cores (022) differ in at least one parameter, such as material, refractive index distribution, structure, cross-sectional dimensions, and doping concentration distribution. The structural difference of the fiber core (022) could be that one type is a hollow, annular core, while another type is a solid core. Here, "different types of fiber cores (022)" does not include cases where the same designed fiber core is manufactured into different cores due to different manufacturing processes.

[0065] The n target fiber cores 022 in at least one optical fiber 02 are used to receive n signal beams in a one-to-one correspondence, where n ≥ 1; the n signal beams can be one signal beam or multiple signal beams, and the wavelengths of the different signal beams can be the same or different. The n target fiber cores 022 can belong to one optical fiber 02 or multiple optical fibers 02, and the one optical fiber 02 and the multiple optical fibers 02 can be some or all of the optical fibers 02 in the optical amplification unit.

[0066] The passive device group 01 is used to couple the pump light corresponding to the target fiber core 022 to the optical fiber 02 where the target fiber core 022 is located. The target fiber core 022 is used to amplify the power of the received signal light based on the corresponding pump light before outputting it. The passive device group 01 includes at least a pump coupler corresponding to each target fiber core 022. The pump couplers corresponding to different target fiber cores 022 can be the same or different. There can be one or more pump couplers corresponding to each target fiber core 022. The passive device group 01 may also include at least one other passive device besides the pump coupler, such as an isolator, GFF, VOA, etc.

[0067] Optionally, the pump light corresponding to the target fiber core 022 can be generated by the pump light source corresponding to the target fiber core 022. Figure 4 (Not shown in the image) The pump light source corresponding to different target fiber cores 022 can be the same or different. The optical amplification unit may or may not include the pump light source, and this application embodiment does not limit this.

[0068] In summary, the optical amplification unit provided in this application includes a passive device group and at least one optical fiber. Each optical fiber includes multiple fiber cores. The passive device group can couple pump light corresponding to the target fiber cores to the optical fibers containing the n target fiber cores in the at least one optical fiber. The target fiber cores can amplify the power of the received signal light according to the corresponding pump light and then output it. Furthermore, there are at least two types of fiber cores in the at least one optical fiber. Different types of fiber cores are suitable for amplifying the power of signal light in different wavelength bands. Therefore, this optical amplification unit supports using different target fiber cores to amplify the power of signal light in different wavelength bands, thus effectively amplifying the power of signal light in different wavelength bands. Moreover, the power amplification effect of using the optical amplification unit provided in this application to amplify the power of signal light in different wavelength bands is comparable to the power amplification effect of using different single-core optical fibers with different fiber cores to amplify the power of signal light in different wavelength bands.

[0069] Furthermore, when at least one target fiber core includes multiple target fiber cores belonging to the same optical fiber, compared to the case where the multiple target fiber cores belong to different optical fibers, the multiple target fiber cores can share passive devices (such as isolators, VOAs, etc.) set on the same optical fiber. Therefore, the number of passive devices included in the passive device group is smaller, the maintenance complexity is lower, and the cost is also lower.

[0070] For example, suppose that the aforementioned at least one target fiber core includes a C-core and an L-core in an optical fiber. The C-core is suitable for power amplification of C-band signal light, and the L-core is suitable for power amplification of L-band signal light. The C-core and L-core belong to the same optical fiber, have the same length, and can share a set of passive devices on the optical fiber.

[0071] Furthermore, based on this, the doping concentration of elements in the C-core and L-core can be designed to make the power amplification effect of the C-core for C-band signal light and the L-core for L-band signal light comparable.

[0072] Optionally, the aforementioned at least one optical fiber 02 includes: a rare-earth-doped fiber core and / or a nonlinear fiber core (such as a highly nonlinear fiber core, which is suitable for Raman amplification). The rare-earth-doped fiber core may include: erbium-doped fiber core, bismuth-doped fiber core, erbium-bismuth-doped fiber core, thulium-doped fiber core, neodymium-doped fiber core, etc. This application can select some technologically mature fiber cores based on technological developments to ensure the power amplification effect of the fiber core on the signal light. For example, the fiber core may be at least one of erbium-doped fiber core, bismuth-doped fiber core, and nonlinear fiber core.

[0073] Optionally, the fiber cores suitable for power amplification of C-band signal light and the fiber cores suitable for power amplification of L-band signal light can both be erbium-doped fiber cores. The fiber cores suitable for power amplification of E-band signal light, the fiber cores suitable for power amplification of S-band signal light, and the fiber cores suitable for power amplification of U-band signal light can all be bismuth-doped or erbium-bismuth-doped fiber cores.

[0074] Optionally, the aforementioned n signal beams include signal beams from at least one of the following bands: C-band, L-band, E-band, and S-band (e.g., at least two). The bands of the different signal beams can be the same or different. Of course, the aforementioned n signal beams may also include signal beams from other bands besides C-band, L-band, E-band, and S-band; this application embodiment does not limit this.

[0075] Furthermore, the n target fiber cores to which the aforementioned n signal beams are transmitted can be of the same or different types. For example, the aforementioned n signal beams can be divided into multiple groups of signal beams. Each group of signal beams includes at least one signal beam (such as one signal beam or multiple signal beams) with a specific wavelength band. Different groups of signal beams have different wavelength bands, and each group of signal beams corresponds to a specific type of target fiber core. Different groups of signal beams correspond to different types of target fiber cores. In this way, signal beams of different wavelength bands are transmitted to different types of target fiber cores, enabling the different types of target fiber cores to effectively amplify the power of the signal beams of different wavelength bands.

[0076] The n target fiber cores corresponding to the aforementioned multiple sets of signal lights can belong to one or more optical fibers. For example, the aforementioned multiple sets of signal lights correspond to target fiber cores in one optical fiber. Alternatively, each of the aforementioned multiple sets of signal lights corresponds to a target fiber core in one optical fiber, and different sets of signal lights correspond to target fiber cores in different optical fibers.

[0077] Optionally, the optical amplification unit includes a first transmission connector ( Figure 4 (Not shown in the image); the first transmission connector can be a passive or active device, and this application embodiment does not limit this. When the first transmission connector is a passive device, it is included in the passive device group 01. The first transmission connector is used to receive m signal lights, obtain the above-mentioned n signal lights based on the m signal lights, and transmit the n signal lights one-to-one to the above-mentioned n target fiber cores; it can be seen that when the first transmission connector is not included, the optical amplification unit is suitable for amplifying the n signal lights; when the first transmission connector is included, the optical amplification unit is suitable for amplifying the m signal lights. Wherein, n>m≥1, one of the n signal lights includes at least a portion of the wavebands of the signal light in one of the m signal lights. It can be seen that the first transmission connector can split at least one of the m signal lights to obtain the above-mentioned n signal lights by wavelength division. These n signal lights include multiple signal lights obtained by splitting at least one signal light. When at least one signal light is a portion of the m signal lights, the n signal lights also include another portion of the m signal lights.

[0078] Optionally, the m-channel signal light includes multiple signal light channels with the same wavelength, or the m-channel signal light includes multiple signal light channels with different wavelengths, or the m-channel signal light includes one signal light channel.

[0079] Optionally, the optical amplification unit includes a second transmission connector ( Figure 4 (Not shown in the diagram); the second transmission connector can be either a passive or active device, and this application embodiment does not limit this. When the second transmission connector is a passive device, it is included in the passive device group 01. The second transmission connector is used to receive the signal light (power-amplified signal light) output from the n target fiber cores 022, and output the power-amplified m-channel signal light according to the signal light received by the second transmission connector. It can be seen that when the second transmission connector is not included, the optical amplification unit is used to output n-channel amplified signal light; when the second transmission connector is included, the optical amplification unit is used to output m-channel amplified signal light.

[0080] Both the first and second transmission connectors can be devices with similar functions, such as wavelength division multiplexing (WDM), beam splitters, beam combiners, and fan-in / fan-out (FIFO) devices. Optionally, at least one of the first and second transmission connectors can be multiplexed as a pump coupler; of course, the pump coupler can also be different from both the first and second transmission connectors.

[0081] The following examples illustrate this point. In these examples, the first transmission connector is included in the passive device group. It can be understood that when the first transmission connector uses an active device, the first transmission connector can also be located outside the passive device group.

[0082] Example 1: The m-channel signal light received by the first transmission connector includes one channel signal light with multiple wavelengths. The first transmission connector splits this channel signal light into n channels corresponding to the multiple wavelengths, and then transmits each of the n channels to a single optical fiber 02, specifically to n distinct target fiber cores 022. Each of the n channels forms a group of signal lights.

[0083] like Figure 10 As shown, the first transmission connector (including) Figure 10 Within the passive device group 01, an optical fiber 02 is connected. This optical fiber 02 has two distinct target fiber cores 022. One target fiber core 022 (referred to as the C-core 022) is used for power amplification of C-band signal light, and the other target fiber core 022 (referred to as the L-core 022) is used for power amplification of L-band signal light. For example, the first target fiber core 022 is an Er-doped fiber core, and the other target fiber core 022 is a Bi-doped fiber core. A first transmission connector receives a C+L band signal light. The first transmission connector can transmit the C-band signal light from this C+L band signal light to the C-core 022, and the L-band signal light from this C+L band signal light to the L-core 022. These two fiber cores 022 will amplify the power of the received signal light according to their respective pump lights.

[0084] Example 2: The m-channel signal light received by the first transmission connector includes multiple signal light channels. Each of the m signal light channels has multiple wavelength bands, and the wavelength bands of different signal light channels are the same. The first transmission connector divides each of these m signal light channels into multiple signal light channels corresponding one-to-one with the multiple wavelength bands. The m signal light channels are divided into multiple groups of signal light channels (a total of n signal light channels), each group of signal light channels includes the signal light of the corresponding wavelength band from each of the m signal light channels. Then, the first transmission connector transmits the n signal light channels to the n target fiber cores in an optical fiber. The target fiber cores corresponding to different groups of signal light channels are of different types, while the target fiber cores corresponding to the same group of signal light channels are of the same type.

[0085] like Figure 11 As shown, the first transmission connector (including) Figure 11 Within the passive device group 01, an optical fiber 02 is connected. This optical fiber 02 has four target fiber cores 022, two of which are C-band fiber cores 022, and the other two are L-band fiber cores 022. A first transmission connector receives two C+L band signal beams. The first transmission connector can transmit the two C-band signal beams from the two C+L band signal beams one-to-one to the two C-band fiber cores 022, and the two L-band signal beams from the two C+L band signal beams one-to-one to the two L-band fiber cores 022. Each of the four fiber cores 022 amplifies the power of the received signal beam according to its corresponding pump light.

[0086] Example 3: Based on Example 2, the aforementioned single optical fiber 02 is replaced with multiple first optical fibers 02 that correspond one-to-one with the aforementioned multiple groups of signal light. In Example 2, each group of signal light in the n-way signal light is transmitted to the target fiber core in the corresponding optical fiber 02.

[0087] like Figure 12 As shown, the first transmission connector (including) Figure 12 Within the passive device group 01, two optical fibers 02 are connected. Each optical fiber 02 has four target fiber cores 022. One optical fiber 02 has all C-band target fiber cores 022, and the other optical fiber 02 has all L-band target fiber cores 022. The first transmission connector receives four C+L band signal lights. The first transmission connector can transmit the four C-band signal lights from the four C+L band signal lights one-to-one to the four C-band fiber cores 022 in one optical fiber 02, and the four L-band signal lights from the four C+L band signal lights one-to-one to the four L-band fiber cores 022 in the other optical fiber. These eight fiber cores 022 will amplify the power of the received signal light according to their corresponding pump light.

[0088] Optionally, each target fiber core 022 in each fiber 02 in Example 3 can use the same pump source (one or more pump sources). Target fiber cores 022 in different fibers 02 use pump light of different wavelengths and different pump sources. For example, the erbium-doped bismuth fiber core uses 14XX nm pump light, while the erbium-doped fiber core uses 976 nm pump light; where X can be any value from 0 to 9, for example, 14XX nm could be 1459 nm, 1432 nm, etc.

[0089] Example 4: The first transmission connector receives m signal beams, including one signal beam. The first transmission connector transmits this signal beam to one target fiber core 022 within an optical fiber 02. In this case, the number of optical fibers 02 can be equal to one or greater than one. The number of fiber cores 022 in all optical fibers 02 can be equal to one or greater than one.

[0090] As described above, the aforementioned n target fiber cores 022 are some or all of the fiber cores in the at least one optical fiber 02. In this embodiment, regardless of the number of target fiber cores 022, and regardless of whether the aforementioned n target fiber cores 022 are some or all of the fiber cores in the at least one optical fiber 02, all fiber cores 022 of the optical fiber are prepared when preparing each optical fiber 02. Furthermore, the n signal beams can be transmitted to the corresponding n target fiber cores according to the current application scenario. In this way, it avoids preparing optical fibers with different numbers of fiber cores to adapt to different application scenarios. The optical fiber in this embodiment can be applied to different application scenarios, and by mass-producing the optical fiber provided in this application, costs can be reduced, the process can be made more stable, and high reliability can be achieved.

[0091] Optionally, the aforementioned different bands refer to at least two of the following bands: C-band, L-band, E-band, S-band, C+L-band, C+E-band, C+S-band, L+E-band, L+S-band, E+S-band, C+L+E-band, C+L+S-band, and L+E+S-band.

[0092] The pump light corresponding to the target fiber core 022 can be in the form of core pump, cladding pump, or core pump + cladding pump; this application embodiment does not limit this. Wherein, when the target fiber core 022 is a nonlinear fiber core, the pump light in the core pump mode is a Raman amplified pump light.

[0093] The pump light corresponding to the target fiber core 022 will be explained below using the i-th target fiber core 022 among the above n target fiber cores 022 as an example. n>i≥1, the i-th target fiber core 022 is any one of the n target fiber cores 022.

[0094] When the pump light corresponding to the i-th target fiber core 022 is in the form of a core pump, the passive device group 01 is used to couple the pump light corresponding to the i-th target fiber core 022 to the i-th target fiber core 022.

[0095] like Figure 13 As shown, when the pump light corresponding to the cladding pump of the i-th target fiber core 022 is in the form of a cladding pump, the cladding 021 surrounding the i-th target fiber core 022 includes a first sub-cladding 0211 and a second sub-cladding 0212. The first sub-cladding 0211 surrounds the second sub-cladding 0212, and the i-th target fiber core 022 is surrounded by the second sub-cladding 0212. The passive device group 01 is used to couple the pump light corresponding to the i-th target fiber core 022 to the second sub-cladding 0212.

[0096] When the pump light corresponding to the i-th target fiber core 022 is in the form of core pump + cladding pump, the passive device group 01 is used to simultaneously couple the pump light corresponding to the i-th target fiber core 022 to the i-th target fiber core 022 and the second sub-cladding 0212.

[0097] The pump light forms (such as core-pumped, cladding-pumped, or core-pumped + cladding-pumped) corresponding to different target fiber cores 022 (e.g., target fiber cores 022 in different optical fibers 02, or different target fiber cores 022 in the same optical fiber 02) can be the same or different. When the pump light corresponding to different target fiber cores 022 is the same, these different target fiber cores 022 can share the same pump light. Furthermore, the pump light corresponding to the target fiber core 022 can come from one pump source or multiple pump sources; this embodiment does not limit this.

[0098] Furthermore, when the pump light corresponding to the i-th target fiber core 022 includes a cladding pump type, the pump light corresponding to the i-th target fiber core 022 can be at least one of single-mode pump light and multi-mode pump light. When the pump light corresponding to the i-th target fiber core 022 includes multi-mode pump light, since the pump source providing multi-mode pump light has lower cost and simpler structure, the optical amplification unit has lower cost and simpler structure when it includes this pump source. When the pump light corresponding to the i-th target fiber core 022 does not include a cladding pump type, the pump light corresponding to the i-th target fiber core 022 can be a single-mode pump light.

[0099] Furthermore, embodiments of this application also provide an optical amplification device, such as... Figure 14 As shown, the optical amplification device includes multiple cascaded optical amplification units 10. Figure 14 Taking three cascaded optical amplification units 10 as an example, the j-th optical amplification unit in the plurality of optical amplification units is used to transmit the output signal light to the (j+1)-th optical amplification unit, where j≥1.

[0100] An optical amplification unit is used to amplify the power of the received signal light. At least one of the plurality of optical amplification units 10 is an optical amplification unit provided in the embodiments of this application. For example, all of the plurality of optical amplification units 10 are optical amplification units provided in the embodiments of this application. Alternatively, some of the plurality of optical amplification units may be optical amplification units provided in the embodiments of this application, while others may differ from those provided in the embodiments of this application. These other optical amplification units may use a single-core optical fiber to amplify the power of the signal light received by the optical amplification unit based on pump light.

[0101] The signal light received by the first optical amplification unit in the plurality of optical amplification units 13 can come from one or more input optical fibers. When the first optical amplification unit receives multiple signal lights and the multiple signal lights come from one input optical fiber, the input optical fiber is a multi-core optical fiber, such as a space division multiplexing (SDM) fiber or a few-mode space division multiplexing (FSDM) fiber.

[0102] The first optical amplification unit among the above-mentioned multiple optical amplification units can be called a power amplifier (PA), and the last optical amplification unit can be called a boost amplifier (BA).

[0103] For example, assuming that the optical amplification unit provided in this application embodiment introduces high noise, then in scenarios where the noise factor (NF) is more sensitive, the BA can use the optical amplification unit provided in this application embodiment, while the PA still uses an optical amplification unit that uses a single-core fiber to amplify the power of signal light in different bands. If the noise introduced by the optical amplification unit provided in this application embodiment is mitigated, then both the PA and BA can use the optical amplification unit provided in this application embodiment.

[0104] In addition, this application embodiment also provides an optical fiber preform, which is used to fabricate the optical fiber in the optical amplification unit provided in this application embodiment. For example, the optical fiber preform includes: a cladding and multiple fiber cores; the multiple fiber cores are all encased within the cladding, and the multiple fiber cores are arranged in parallel and spaced apart, including at least two types of fiber cores; the fiber cores are used to receive signal light and pump light, and to amplify the power of the signal light according to the pump light. Optionally, the different types of fiber cores have different parameters in terms of material, refractive index distribution, structure, and cross-sectional dimensions, wherein the cross-section is perpendicular to the fiber core axis. Optionally, the multiple fiber cores include: erbium-doped fiber cores, bismuth-doped fiber cores, erbium-bismuth-doped fiber cores, and / or nonlinear fiber cores.

[0105] Optionally, the cladding includes a first sub-cladding and a second sub-cladding, with the first sub-cladding enclosing the second sub-cladding, and multiple fiber cores enclosing within the second sub-cladding; this configuration is suitable for cladding-pumped pumped light. Alternatively, the cladding is not divided into a first sub-cladding and a second sub-cladding, in which case multiple fiber cores are enclosing within the cladding; this configuration is suitable for core-pumped pumped light.

[0106] This application embodiment also provides an optical fiber, which is drawn from the aforementioned optical fiber preform. This optical fiber can be the optical fiber in the aforementioned optical amplification unit. For example, the optical fiber includes a cladding and multiple fiber cores encased within the cladding. The multiple fiber cores are arranged in parallel and spaced intervals, and at least one optical fiber includes at least two types of fiber cores. Optionally, the different types of fiber cores have different parameters in terms of material, refractive index distribution, structure, and cross-sectional dimensions, wherein the cross-section is perpendicular to the fiber core axis. The optical fiber may include: erbium-doped fiber cores, bismuth-doped fiber cores, erbium-bismuth-doped fiber cores, and / or nonlinear fiber cores. Optionally, the cladding includes a first sub-cladding and a second sub-cladding, the first sub-cladding encasing the second sub-cladding, and multiple fiber cores encased within the second sub-cladding; this is suitable for cladding-pumped pump light. Alternatively, the cladding is not divided into a first sub-cladding and a second sub-cladding; in this case, multiple fiber cores are encased within the cladding, which is suitable for core-pumped pump light.

[0107] In this application, the terms "first" and "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The term "and / or" merely describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0108] It should be noted that all signal lights involved in this application are obtained with the authorization of the user or with full authorization from all parties, and the collection, use, and processing of the relevant signal lights must comply with the relevant laws, regulations, and standards of the relevant countries and regions. For example, the signal lights involved in this application were all obtained under full authorization.

[0109] The above description is merely an embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An optical fiber preform, characterized in that, include: Cladding and multiple fiber cores; The multiple fiber cores are all wrapped within the cladding layer. The multiple fiber cores are arranged in parallel and spaced apart. The multiple fiber cores include at least two types of fiber cores. The fiber core is used to receive signal light and pump light, and to amplify the power of the signal light according to the pump light.

2. The optical fiber preform according to claim 1, characterized in that, Different types of fiber cores differ in at least one of the following parameters: material, refractive index distribution, structure, and cross-sectional dimensions, wherein the cross-section is perpendicular to the fiber core axis.

3. The optical fiber preform according to claim 1 or 2, characterized in that, The multiple fiber cores include: erbium-doped fiber cores, bismuth-doped fiber cores, erbium-bismuth-doped fiber cores, and / or nonlinear fiber cores.

4. The optical fiber preform according to any one of claims 1 to 3, characterized in that, The cladding includes a first sub-cladding and a second sub-cladding, the first sub-cladding wraps around the second sub-cladding, and the multiple fiber cores are all wrapped within the second sub-cladding.

5. An optical fiber, characterized in that, The optical fiber is drawn from an optical fiber preform as described in any one of claims 1 to 4.

6. An optical amplification unit, characterized in that, include: A passive device assembly and at least one optical fiber; the optical fiber includes a cladding and multiple fiber cores encased within the cladding, the multiple fiber cores being arranged in parallel and spaced apart, and the at least one optical fiber including at least two types of fiber cores; The n target fiber cores in the at least one optical fiber are used to receive n signal light in a one-to-one correspondence, where n≥1; The passive device group is used to couple the pump light corresponding to the target fiber core to the optical fiber where the target fiber core is located; The target fiber core is used to amplify the power of the received signal light based on the corresponding pump light before outputting it.

7. The optical amplification unit according to claim 6, characterized in that, Each of the at least one optical fiber comprises at least two types of fiber cores.

8. The optical amplification unit according to claim 6 or 7, characterized in that, The different types of fiber cores have different parameters in at least one of the following: material, refractive index distribution, structure, and cross-sectional dimensions, wherein the cross-section is perpendicular to the fiber core axis.

9. The optical amplification unit according to any one of claims 6 to 8, characterized in that, The at least one optical fiber includes: an erbium-doped fiber core, a bismuth-doped fiber core, an erbium-bismuth-doped fiber core, and / or a nonlinear fiber core.

10. The optical amplification unit according to any one of claims 6 to 9, characterized in that, The n-channel signal light includes multiple groups of signal light, each group of signal light includes at least one signal light with a wavelength band, the different groups of signal light have different wavelength bands, and the different groups of signal light correspond to different types of target fiber cores.

11. The optical amplification unit according to claim 10, characterized in that, The multiple sets of signal lights correspond to the target fiber core in a single optical fiber.

12. The optical amplification unit according to claim 10, characterized in that, Each of the multiple groups of signal light corresponds to the target fiber core in an optical fiber; different groups of signal light correspond to the target fiber cores in different optical fibers.

13. The optical amplification unit according to any one of claims 6 to 12, characterized in that, The passive device group is used to couple the corresponding pump light to the i-th target fiber core among the n target fiber cores, where n > i ≥ 1.

14. The optical amplification unit according to any one of claims 6 to 13, characterized in that, The cladding of the i-th target fiber core among the n target fiber cores includes a first sub-cladding and a second sub-cladding. The first sub-cladding wraps the second sub-cladding, and the i-th target fiber core is wrapped inside the second sub-cladding, where n > i ≥ 1. The passive device group is used to couple the pump light corresponding to the i-th target fiber core to the second sub-cladding.

15. The optical amplification unit according to claim 14, characterized in that, The pump light corresponding to the i-th target fiber core includes multimode pump light.

16. The optical amplification unit according to any one of claims 6 to 15, characterized in that, The optical amplification unit also includes a pump light source corresponding to the target fiber core, which is used to provide pump light corresponding to the target fiber core.

17. The optical amplification unit according to any one of claims 6 to 16, characterized in that, The n-channel signal light includes signal light from at least two of the following wavelengths: 1530 nm to 1565 nm, 1565 nm to 1625 nm, 1360 nm to 1460 nm, and 1460 nm to 1530 nm.

18. The optical amplification unit according to any one of claims 6 to 17, characterized in that, The optical amplification unit includes: a first transmission connector; The first transmission connector is used to receive m signal beams, obtain n signal beams based on the m signal beams, and transmit the n signal beams one by one to the n target fiber cores; n > m ≥ 1, and one of the n signal beams includes at least a portion of the wavelength bands of the signal beams in one of the m signal beams.

19. The optical amplification unit according to claim 18, characterized in that, The optical amplification unit includes: a second transmission connector; The second transmission connector is used to receive the signal light output from the n target fiber cores, and output the m-channel signal light with amplified power according to the received signal light.

20. An optical amplification device, characterized in that, include: A plurality of cascaded optical amplification units, wherein at least one of the plurality of optical amplification units is the optical amplification unit according to any one of claims 6 to 19; The optical amplification unit is used to amplify the power of the received signal light, and the j-th optical amplification unit in the plurality of optical amplification units is used to transmit the output signal light to the (j+1)-th optical amplification unit, where j≥1.

Images