Optical amplification system and control method thereof

Abstract

The present application relates to the technical field of optical fiber communication, more particularly, to an optical amplification system and a control method thereof. The system comprises an optical amplification module, which is optically coupled with a gain section of a multi-core optical fiber; and an optional optical attenuation module, which is arranged at an output end of the gain section of the module and is capable of performing parallel and adjustable attenuation on each channel optical signal output from the gain section. The optical amplification system can modulate the optical amplification module and / or the optical attenuation module based on output optical signal information from the gain section or the optical attenuation module and a control logic algorithm, so that the multi-channel optical signals transmitted in the multi-core optical fiber can achieve dynamic, parallel and adjustable amplification.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical fiber communication technology, and more particularly, to an optical amplification system and a control method thereof. BACKGROUND

[0002] In the field of optical fiber communication technology, three types of optical amplifiers are commonly used in optical communication links: rare-earth-doped fiber amplifiers (REDFA), Raman amplifiers (RA), and semiconductor optical amplifiers (SOA). These amplifiers have their own advantages in terms of working principle, gain bandwidth, noise characteristics, and application scenarios, and have become indispensable key components in modern optical communication systems.

[0003] As one of the most widely used optical amplification solutions in current optical communication systems, single-core rare-earth-doped fiber amplifiers (SM-REDFA) have the advantages of high gain, low noise, and strong compatibility, and have been widely used in various commercial optical communication links. However, this type of traditional single-core single-mode amplifier has gradually shown limitations in meeting the future demand for high-speed and large-capacity transmission. On the one hand, its single-core structure limits the spatial multiplexing capability, making it difficult to achieve multi-channel parallel amplification in a limited fiber cross-section, which is not conducive to further improving the system capacity. On the other hand, its simple structure makes it difficult to efficiently couple with emerging multi-core and multi-mode fiber devices, limiting its scalability in space division multiplexing (SDM) communication systems. In addition, to improve gain uniformity and bandwidth coverage, complex pumping schemes and gain compensation designs are usually required, which further increases the overall complexity and cost of the system. Therefore, although single-core amplifiers are mature and stable in performance, their adaptability to high-density integration and ultra-large capacity transmission has become a bottleneck.

[0004] With the continuous growth of the capacity demand of modern optical communication systems, traditional single-core rare-earth-doped fiber amplifiers can only amplify single-channel signals, which greatly limits the scalability of the system. In contrast, parallel amplifiers based on multi-core erbium-doped fibers can simultaneously amplify multiple single-mode fiber links in a single amplifier structure, thereby significantly improving the system integration and transmission channel density. This parallel amplification method can effectively increase the number of amplification channels while maintaining a compact device size, and therefore has become one of the key technologies to support space division multiplexing (SDM) communication systems. However, this technology still faces many challenges in practical applications. For example, uneven distribution of pump power among multiple cores can lead to inconsistent gains among channels, and the multi-core structure itself also imposes higher requirements on coupling precision and component coordination, further increasing the complexity of system design and packaging.

[0005] Furthermore, multi-core rare-earth-doped fiber parallel amplifiers also face technical challenges in pump scheme design, gain equalization control, and thermal management. Since the pump source needs to be shared or distributed among multiple amplification channels, achieving efficient coupling and balanced distribution of pump light across different fiber cores becomes a key factor limiting overall amplification efficiency and performance stability. Simultaneously, long-distance amplification in multi-channel systems may also lead to issues such as signal crosstalk and cross-core gain drift, placing higher demands on the precise design and control of the amplifier. Nevertheless, due to its significant advantages in increasing system capacity and reducing bit cost, this technology has become one of the important directions for the development of fiber optic communication amplifiers. Summary of the Invention

[0006] The present invention aims to solve the technical problem that the existing technology still cannot overcome in achieving dynamic, parallel and adjustable amplification of signals in multi-channel optical fiber communication, and provides an optical amplification system and its control method, which can realize dynamic, parallel and adjustable amplification of multi-channel optical signals transmitted in multi-core optical fibers.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0008] In a first aspect, the present invention provides an optical amplification system that can be used to dynamically, in parallel, and tunably amplify multi-channel optical signals transmitted in a multi-core optical fiber.

[0009] The optical amplification system includes an optical amplification module, and optionally an optical attenuation module. The optical amplification module is optically coupled to the gain section of a multi-core optical fiber and configured to adjustably amplify the multi-channel optical signals transmitted in the gain section. The optical attenuation module is located at the output end of the gain section, along the transmission direction of the optical signal, and is configured to perform parallel and adjustable attenuation of each channel optical signal output from the gain section. The optical amplification system can modulate the optical amplification module and / or the optical attenuation module based on the output optical signal information from the gain section or the optical attenuation module and control logic, thereby achieving parallel and adjustable amplification of multi-channel optical signals in the multi-core optical fiber. It should be noted that the optional inclusion of an optical attenuation module means that the system can choose to include or exclude an optical attenuation module; different choices correspond to different implementation methods.

[0010] In some embodiments, the optical amplification system further includes a sensor module and a controller module. The sensor module detects information about the output optical signal and sends the output optical signal information to the controller module; the controller module then modulates the optical amplification module and / or the optical attenuation module based on the received output optical signal information and control logic.

[0011] In this invention, the optical amplification system can have different structural configurations, specifically embodied in several embodiments: (1) In one embodiment, the system does not include an optical attenuation module, the controller module is communicatively connected to the optical amplification module, and modulates the optical amplification module based on the output optical signal information from the gain section and control logic. (2) In another embodiment, the system includes an optical attenuation module, but the controller module is not connected to the optical amplification module, but only communicatively connected to the optical attenuation module, and modulates it according to the output signal information from the optical attenuation module and control logic. (3) In yet another embodiment, the system also includes an optical attenuation module, and the controller module is communicatively connected to both the optical amplification module and the optical attenuation module, and modulates one or both of them according to the output signal information from the optical attenuation module and control logic.

[0012] In some embodiments, the optical amplification module includes multiple pump sources, each optically coupled to a gain segment and independently modulated to provide adjustable pump light for amplifying multi-channel optical signals. These pump sources can be optically coupled to the pump cladding portion of the gain segment via at least one pump fiber.

[0013] In some embodiments, the optical attenuation module includes multiple attenuation sub-modules, each located at the output end of a core segment corresponding to the gain segment. Each attenuation sub-module includes a fixed optical attenuator or a variable optical attenuator (VOA). The VOA type can be a variable neutral density filter type, a liquid crystal type, or an air gap type, and each sub-module is electrically adjustable.

[0014] In all the above embodiments, the output optical signal information may include its optical power and / or wavelength. The optical amplification system may further include an optical power meter (OPM) or an optical wavelength meter (OWM) to detect these parameters.

[0015] In this invention, the control logic can be preset or automatically set based on a strategy such as PID control.

[0016] In some embodiments, the optical amplification system further includes a temperature sensor for detecting the temperature of the gain section, and modulating the optical amplification module and / or the optical attenuation module if the temperature exceeds a first threshold.

[0017] In other embodiments, the optical amplification system includes a current sensor for detecting the operating current of each pump source and modulating the corresponding pump source when the current exceeds a second threshold.

[0018] In a second aspect, the present invention also provides a control method for realizing dynamic, parallel, and adjustable amplification of multi-channel optical signals in a multi-core optical fiber, the method using the optical amplification system described in the first aspect.

[0019] The method includes the following steps:

[0020] Step S1: Provide an optical amplification system conforming to any of the above embodiments, and configure it to work in connection with a multi-core optical fiber;

[0021] Step S2: Obtain the output optical signal information from the gain section or optical attenuation module;

[0022] Step S3: Based on this information and control logic, modulate the optical amplification module and / or optical attenuation module.

[0023] Step S1, “Configure working connection with multi-core fiber”, includes: optically coupling the optical amplification module to the gain section of the multi-core fiber, and setting the optical attenuation module at the output end of the gain section.

[0024] This method has multiple implementations, each corresponding to a specific configuration of the optical amplification system:

[0025] If the optical amplification system does not have an optical attenuation module, the controller module communicates with the amplification module. The method includes obtaining the output optical information of the gain segment from the sensor and modulating the amplification module by the controller module.

[0026] If the optical amplification system has an optical attenuation module but does not communicate with it, the controller module only modulates the attenuation module. The method includes acquiring the output information from the optical attenuation module and modulating accordingly.

[0027] If the controller module in the optical amplification system is connected to both the optical attenuation module and the optical amplification module, then in the method, the controller modulates one or both of them based on the output signal of the optical attenuation module.

[0028] The control logic can be preset or automatically generated based on PID control.

[0029] The control logic may include: determining whether the output optical signal meets the preset conditions; if it does, no modulation is performed; otherwise, modulation is performed on the optical amplification module and / or the optical attenuation module.

[0030] Optionally, the preset conditions include the following control modes: output power equalization mode (maximum output power deviation does not exceed the threshold); custom power allocation mode (the output power or power ratio of some channels reaches the preset value); dynamic response mode.

[0031] In some embodiments, the optical amplification system is equipped with a temperature sensor, and the controller module determines whether to modulate the optical attenuation module and the optical amplification module based on the temperature.

[0032] In other embodiments, the optical amplification system includes a current sensor, and the controller determines whether to modulate the corresponding pump light source based on the pump current.

[0033] In a third aspect, the present invention also provides an optical amplification module that can be used in the above-mentioned system or method to realize dynamic, parallel, and adjustable amplification of multi-channel signals in a multi-core optical fiber.

[0034] The multi-core optical fiber used in this amplification module includes a gain section comprising multiple cores and a first cladding. The first cladding covers the exterior of each core and has a lower refractive index than the core. At least one core is doped with rare-earth elements. The optical amplification module includes multiple pump light sources, each optically coupled to the gain section through the first cladding, to excite pump light from rare-earth ions within the core.

[0035] In some embodiments, each pump light source is optically coupled to the gain section via a pump fiber, and the pump fiber is in direct contact with the first cladding, allowing light to propagate into the interior of the first cladding. Optionally, the pump fiber is connected to the first cladding via fusion splicing.

[0036] In some embodiments, the two pump light incident points on the first cladding may be located at different positions along the gain segment axis or at different cross sections perpendicular to the multi-core fiber axis.

[0037] Some of the cores may be symmetrically distributed in a ring around the central axis of the optical fiber. Preferably, the pump contact point is located in a fan-shaped region between two adjacent cores and is equidistant from the two cores.

[0038] Alternatively, the gain segment may include N (N>1) cores evenly distributed on the ring structure, and a central core coaxial with the optical fiber, with multiple pump light sources connected to it through N coupling points.

[0039] For example:

[0040] In some embodiments, N = 6, and the optical amplification module includes 6 pump light sources, each coupled to the first cladding through 6 pump optical fibers;

[0041] In other embodiments, N = 4, and the module includes 4 pump light sources, also using 6 pump optical fibers to access the first cladding.

[0042] In some embodiments, at least one core is further covered with a second cladding layer, which is surrounded by the first cladding layer and has a higher refractive index than the first cladding layer.

[0043] In other embodiments, the cross-sectional shape of the first cladding layer is non-circular.

[0044] Compared with the prior art, the beneficial effects of the present invention are:

[0045] The optical amplification system and its control method provided by this invention can achieve dynamic, parallel and adjustable amplification of multi-channel optical signals transmitted in multi-core optical fibers. By combining an optical amplification module, a sensor module, a controller module and an optional optical attenuation module, precise feedback control is achieved, ensuring power balance between channels and overall system stability. Attached Figure Description

[0046] Figures 1A-1C These are structural diagrams of the optical amplification system in three different embodiments of the present invention;

[0047] Figure 2A shows a schematic diagram of a variable optical attenuator (VOA) used in an optical amplification system according to some embodiments of the present disclosure;

[0048] Figure 2B is a schematic diagram of a variable optical attenuator (VOA) used in an optical attenuation module of an optical amplification system according to some embodiments of the present disclosure, which can be applied to the optical attenuator module of an optical amplification system according to some embodiments of the present disclosure;

[0049] Figure 3 This is a circuit diagram of the controller module used in some embodiments of the optical amplification system;

[0050] Figure 4 This is a flowchart of the steps included in the control method in some embodiments;

[0051] Figure 5 These are control logic instructions used in the optical amplification system or its control method in some embodiments;

[0052] Figure 6 This is a flowchart illustrating the control logic of the optical amplification system based on gain segment temperature information in some embodiments.

[0053] Figure 7 This is a flowchart illustrating the control logic of the optical amplification system based on the pump source operating current information in some embodiments.

[0054] Figure 8 This is a structural diagram of the optical amplification module in some embodiments;

[0055] Figure 9A and Figure 9B The diagrams illustrate cross-sectional and longitudinal sections of the multi-core fiber gain section in certain embodiments, as well as the position of the pump fiber contact point relative to the pump light source.

[0056] Figure 9C This diagram illustrates a cross-sectional view of the gain segment of a multi-core fiber with a double-clad structure and the relative positions of the pump fiber contact points in certain embodiments.

[0057] Figures 10A-10E A schematic diagram illustrating various arrangements of the contact points between the core and pump fiber in the gain section of a multi-core optical fiber;

[0058] Figure 11 This is a schematic diagram of the optical amplification system structure using a parallel seven-core doped fiber amplifier as the optical amplification module in Example 1.

[0059] Figure 12 A cross-sectional view of a seven-core doped gain fiber and the relative positions of the six multimode fibers are shown.

[0060] Figure 13 The image is a photograph illustrating the process of fusion splicing the pump fiber and the cladding of the seven-core fiber in Example 1;

[0061] Figure 14 The pump coupling efficiency curve of the optical amplification system in Example 1 is shown.

[0062] Figures 15A-15C The end face view, cladding pump light distribution, and core spontaneous emission energy diagram of the seven-core erbium-doped fiber amplifier in Example 1 are shown respectively.

[0063] Figure 16A and Figure 16B The seven cores in Example 1 are illustrated in the C-band (…). Figure 16A ) and L-band ( Figure 16B Gain curves for parallel amplification;

[0064] Figure 17 This diagram illustrates the structure of an optical amplification system using a parallel four-core doped fiber amplifier as the optical amplification module in Embodiment 2 of this disclosure.

[0065] Figures 18A and 18B show the cross-sectional view and refractive index distribution curve of a four-core erbium-doped fiber, respectively.

[0066] Figure 19 The parallel amplification gain curve of the four cores in the C-band is shown in Example 2;

[0067] Figure 20 A schematic diagram of the dynamic gain control system (i.e., optical amplification system) in Embodiment 3;

[0068] Figure 21 The control circuit diagram of the real-time feedback node (i.e., controller module) used in the dynamic gain control system in illustrative embodiment 3;

[0069] Figure 22 A detailed algorithm flowchart for dynamic gain control in illustrative embodiment 3 is shown. Detailed Implementation

[0070] The present invention will be further described below with reference to specific embodiments. The accompanying drawings are for illustrative purposes only, representing schematic diagrams rather than actual physical objects, and should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0071] First Embodiment

[0072] Figure 1A A schematic diagram of an optical amplification system according to a first embodiment is shown. Figure 1A As shown, the first embodiment 001A of the optical amplification system includes an optical amplification module 100, a controller module 200, and a sensor module 300. Both the optical amplification module 100 and the sensor module 300 are communicatively connected to and controlled by the controller module 200.

[0073] The optical amplification module 100 is optically coupled to the gain section 20 (the patterned block portion in the figure) of the multi-core optical fiber 10 (shown by thick lines in the figure), and is configured to amplify the optical signal transmitted in the multi-core optical fiber 10 in parallel and adjustable manner under the control of the controller module 200. The sensor module 300 is configured to detect the output optical signal information output from the gain section 20, and then send the detected output optical signal information to the controller module 200. The controller module 200 is configured to modulate the optical amplification module 100 based on the output optical signal information detected by the sensor module 300 and preset control logic.

[0074] By using sensor module 300 to detect the output optical signal information from gain section 20, and then using controller module 200 to adjust and control optical amplification module 100 based on the information detected by sensor module 300 and preset control logic, the first embodiment 001A of this optical amplification system essentially realizes feedback control of optical amplification module 100, thereby allowing dynamic control of the gain of optical signal for each channel.

[0075] Second Embodiment

[0076] Figure 1B A schematic diagram of an optical amplification system according to a second embodiment is shown. Figure 1ACompared to the first embodiment 001A of the optical amplification system shown, the second embodiment 001B of this optical amplification system also includes an optical amplification module 100, a controller module 200, and a sensor module 300, but further includes an optical attenuation module 400. This optical attenuation module 400 is arranged substantially downstream of the gain section 20 along the optical signal transmission direction of the multi-core optical fiber 10 (input optical signals are indicated by thin arrows, and output optical signals by thick arrows), and is also communicatively connected to the controller module 200. The optical attenuation module 400 is configured to independently and adjustablely attenuate the optical signal of each channel transmitted through the gain section 20 under the control of the controller module 200.

[0077] In the second embodiment 001B of the optical amplification system, the sensor module 300 is configured to detect the output optical signal information output from the optical attenuation module 400, and then send the detected output optical signal information to the controller module 200. The controller module 200 is configured to modulate one or both of the optical amplification module 100 and / or the optical attenuation module 400 based on the output optical signal information detected by the sensor module 300 and preset control logic.

[0078] By using sensor module 300 to detect the output optical signal information from optical attenuation module 400, and then using controller module 200 to adjustably control optical amplification module 100 and / or optical attenuation module 400 based on the information detected by sensor module 300 and preset control logic, the second embodiment 001B of the optical amplification system also implements similar feedback control. Compared with the first embodiment 001A of the optical amplification system, the second embodiment 001B of the optical amplification system can achieve finer control over the gain of the optical signal of each channel. This is because, based on the output optical signal information detected by sensor module 300, controller module 200 can not only modulate the operation of optical amplification module 100 as in the first embodiment 001A, but also modulate the operation of optical attenuation module 400, which can independently and adjustably attenuate the optical signal of each channel that has been amplified by gain segment 20.

[0079] Third Embodiment

[0080] Figure 1C A schematic diagram of an optical amplification system according to a third embodiment of the present disclosure is shown. Figure 1C As shown, the third embodiment 001C of this optical amplification system and Figure 1B Similar to the second embodiment 001B of the optical amplification system shown above, it also includes an optical attenuation module 400 arranged downstream of the gain section 20 along the optical signal transmission direction of the multi-core optical fiber 10, and is also communicatively connected to the controller module 200. However, unlike the second embodiment 001B, the controller module 200 of the third embodiment 001C of this optical amplification system is not communicatively connected to the optical amplification module 100.

[0081] In the third embodiment 001C of this optical amplification system, the sensor module 300 is configured to detect the output optical signal information output from the optical attenuation module 400, and then send the detected output optical signal information to the controller module 200. The controller module 200 is configured to modulate the optical attenuation module 400 based on the output optical signal information detected by the sensor module 300 and preset control logic.

[0082] By using sensor module 300 to detect the output optical signal information from optical attenuation module 400, and then using controller module 200 to adjust and control optical attenuation module 400 based on the information detected by sensor module 300 and preset control logic, the third embodiment 001C of the optical amplification system can also achieve feedback control similar to the first and second embodiments 001A and 001B of the optical amplification system described above.

[0083] Terminology Definition

[0084] Module: As used herein, the terms "module," "submodule," or similar terms refer to an entity designed to perform a specified function. Depending on the circumstances, such an entity may comprise a set of hardware components, a set of software components, or both, assembled or organized together to perform one or more functions. For example, an optical amplification module as used herein may include one or more pump lasers and their driving control software, which work together to optically amplify optical signals transmitted in the fiber gain segment. A controller module may include hardware components (such as processors, memory, buses, I / O interfaces, etc.) and software components (such as software programs or instructions) stored and executable on some of the hardware components, which work together to communicate with other devices or modules or modulate the operation of other devices or modules.

[0085] Gain Section: As used in this invention, the term "gain section" refers to a segment of optical fiber used to amplify optical signals transmitted in the optical fiber. Within the scope of this invention, the optical fiber may be a single-core fiber, or more preferably a multi-core fiber having multiple cores that essentially provide multiple channels for optical signal transmission. The gain section comprises multiple core portions corresponding to multiple cores (or channels) of the multi-core fiber. In the gain section, at least one, or possibly all, of the multiple core portions is doped with a dopant that allows the optical signal channels transmitted through the doped core portions to be amplified in the gain section by an optical amplifier (such as optical amplification module 100).

[0086] Dynamic control: The term "dynamic" as used in this invention means that the optical amplification system can monitor one or more parameters of the gain segment, multi-core optical fiber, or various functional modules in the system in a periodic, real-time, or operational manner, and can responsively modulate the operation of various functional modules in the system based on the monitoring results, so that the multi-channel optical signals transmitted in the multi-core optical fiber can be tunably amplified.

[0087] Parallel amplification: The term "parallel" as used in this invention means that at least two, possibly all, of the multi-channel optical signals (i.e., input optical signals, shown as "input" in the figure) transmitted in the multi-core optical fiber 10 are amplified separately at the gain section 20 by the optical amplification module 100, thereby becoming amplified optical signals (i.e., output optical signals, shown as "output" in the figure) output from the gain section 20.

[0088] Adjustable control: As used in this invention, the term "adjustable" means that the device can be controlled to adjust or change one or more parameters, such that the operation of the device can be modulated. Within the scope of this disclosure, the device may be an optical amplification module 100, which can be controlled to adjust or change one or more parameters of the pump light from its output to the gain section. These parameters may include the on-off state of the pump source, drive current (to change the beam power), wavelength, pulse width, or duty cycle, etc. The device may also be an optical attenuation module 400, whose parameters can be changed so that the on-off state and / or drive current of the actuator submodule (for the optical signal of each channel) can be modulated to change its optical signal attenuation level.

[0089] Preset control logic: As used in this invention, "preset control logic" refers to a set of rules and instructions prescribed to manage the operation of a specific functional module, which determine how the module operates and responds to specific inputs. Within the scope of this disclosure, preset control logic may be stored in a controller module to manage how the optical amplification module and / or optical attenuation module are modulated in response to certain inputs (such as output optical signal information, gain segment temperature, and other information related to the operating state of certain functional modules, such as the operating current of the pump light source in the optical amplification module).

[0090] Detailed explanation of the optical amplification module:

[0091] In order to achieve parallel and tunable amplification of multi-channel optical signals transmitted in multi-core optical fiber 10, some embodiments of the present invention include an optical amplification module 100 comprising a plurality of pump light sources configured to tunably amplify optical signals transmitted in a plurality of fiber core portions of gain segment 20.

[0092] The output optical signal information detected by sensor module 300 and sent to controller module 200 may include optical power information and / or wavelength information of the output optical signal.

[0093] Depending on the specific information to be detected and utilized, sensor module 300 may include an optical power meter (OPM) capable of detecting the power level of each output optical signal, and / or may include an optical wavelength meter (OWM or "wavelength meter") capable of detecting the wavelength of each output optical signal.

[0094] Optical attenuation module: The term "optical attenuation module" generally refers to a device or apparatus for reducing the power intensity of an optical signal. Within the scope of this invention, it may more specifically refer to an assembly comprising multiple optical attenuator submodules, each for reducing the optical signal transmitted through one channel of multiple cores in a multi-core optical fiber. Depending on the embodiment, each optical attenuator submodule may be of a different type, such as a fixed attenuator or an adjustable attenuator (e.g., continuous or stepped), may be of a different category (e.g., based on absorption, reflection, polarization, etc.), and / or may be of a different form (e.g., a microelectromechanical system (MEMS) attenuator, a liquid crystal optical attenuator, a thermo-optical attenuator, a gap loss attenuator, or a doped fiber attenuator).

[0095] Preferably, each optical attenuator submodule in the optical attenuation module 400 includes a variable optical attenuator (VOA) that allows for adjustable reduction of the optical signal in the corresponding channel. Examples of VOAs may include MEMS-based VOAs, liquid crystal VOAs, thermo-optical VOAs, magneto-optical VOAs, acousto-optic VOAs, etc. More preferably, the VOA is electronically tunable / adjustable, and further according to some embodiments, the VOA is a MEMS attenuator.

[0096] Figure 2A A schematic diagram of a VOA used as an optical attenuation submodule according to some embodiments of the present disclosure is shown. As shown, the VOA mainly includes a variable neutral density (ND) filter 401 disposed in the optical signal propagation path, between a collimating lens 402 and a focusing lens 403. The variable ND filter 401 is configured to be adjustable along a predetermined direction (as indicated by the bidirectional arrows in the figure), thereby realizing continuous adjustment of the beam power entering the output fiber. Optionally, the variable ND filter 401 can be an absorptive or reflective type and can be selectively mounted on a filter wheel.

[0097] Figure 2B Structural details of a variable neutral density (ND) filter 401 according to some embodiments of the present disclosure are further shown. As shown, the variable ND filter 401 is essentially a disk-shaped structure with a central aperture of Φ8 mm and an outer diameter of Φ50 mm. The shading pattern on the disk represents a variable optical density distribution, thereby achieving continuous attenuation as the filter rotates. The side view shows two distinct sections, S1 and S2, corresponding to different optical density regions. The rightmost schematic diagram shows a 90° sector mark for reference during assembly and positioning.

[0098] Controller module hardware architecture:

[0099] like Figure 3As shown, the hardware components of the controller module 200 include at least one processor 201 and a memory 202, which are communicatively connected via a bus 206. The memory 202 is configured to store one or more software programs (i.e., computer code or executable instructions), and the at least one processor 201 is configured to perform calculations based on the software programs stored in the memory 202, thereby performing tasks to perform specified functions to another functional module (i.e., the optical amplification module 100, the sensor module 300, and / or the optical attenuation module 400).

[0100] The controller module 200 may further include one or more I / O interfaces 203, one or more communication interfaces 204, or one or more storage devices 205, each configured to communicate with each other and with at least one processor 201 and memory via bus 206.

[0101] Control methods:

[0102] In another aspect, the present invention further provides a method for dynamically, in parallel and tunably amplifying multi-channel optical signals transmitted in a multi-core optical fiber.

[0103] like Figure 4 As shown, the method includes the following steps S100-S300:

[0104] S100: Provides an optical amplification system, configured to allow the optical amplification system to be operatively connected to a multi-core optical fiber;

[0105] S200: Acquire output optical signal information;

[0106] S300: Based on the output optical signal information and preset control logic, modulate one or both of the optical amplification module and / or optical attenuation module.

[0107] Preset control logic implementation:

[0108] In any of the above embodiments, the preset control logic can be as follows: Figure 5 The settings shown include the following instructions:

[0109] Determine whether the preset conditions are met based on the output optical signal information; if so, acquire the output optical signal information; otherwise, modulate one or both of the optical amplification module and / or optical attenuation module.

[0110] The preset conditions are essentially the target conditions for achieving feedback control using the above methods. They can be configured according to different operating modes that depend on different actual needs, such as output power balance mode, customized power allocation mode, or dynamic response mode.

[0111] Output power balance mode:

[0112] According to some embodiments, preset conditions are configured in output power balancing mode. In one possible scenario, output power balancing mode requires that the output power of the optical signals in all channels be substantially the same. Therefore, the preset conditions can be configured such that the maximum output power deviation (i.e., the output power difference between the highest and lowest channels) is no greater than a preset threshold (e.g., 0.5 dB).

[0113] Custom power allocation mode:

[0114] According to some other embodiments, preset conditions are configured in a customized power allocation mode. Possible scenarios include determining whether the output power or output power ratio of a subset of optical signal channels meets a preset target value.

[0115] Temperature monitoring and protection:

[0116] According to some embodiments, the control method may selectively be further based on temperature information of the gain segment. By monitoring the temperature of the gain segment and modulating the optical attenuation module and / or the optical attenuation module when the temperature exceeds a preset threshold, the optical amplification system can be additionally used to provide a protection mechanism to prevent fiber overheating.

[0117] Optical amplification module architecture:

[0118] Figure 8 A schematic diagram of an optical amplification module 100 according to some embodiments of the present invention is shown. This module is used for optical amplification of multi-channel optical signals transmitted in a multi-core optical fiber.

[0119] Multi-channel optical signals (i.e., input optical signals, represented by multiple optical fibers 11 in the figure) are individually input into multi-core optical fibers 10 through fan-in device 12, further optically amplified in gain section 20 by optical amplification module 100 optically coupled to gain section 20, and then output as output optical signals through fan-out device 13. Both fan-in device 12 and fan-out device 13 can be fan-in / fan-out (FIFO) devices, serving as both input and output terminals.

[0120] The multi-core optical fiber 10 includes multiple cores, each responsible for transmitting an optical signal for one channel. The gain section 20 includes multiple core portions, each corresponding to one channel of optical signal transmitted through the multi-core optical fiber 10. The gain section 20 is configured such that at least one, or possibly all, of the multiple core portions is doped with an optically excitable dopant, which may include one or more rare-earth elements such as erbium, neodymium, ytterbium, praseodymium, or thulium. The gain section 20 also includes a first cladding portion located around each core.

[0121] Core arrangement and pumping scheme:

[0122] In this invention, "located on the periphery" means that the first cladding portion can be directly covered on the periphery of the core, or that one or more other cladding layers are sandwiched between the core and the first cladding portion.

[0123] The optical amplification module 100 includes a plurality of pump light sources 101. Each pump light source 101 is optically coupled to the gain section 20 via a pump fiber 102, which is in optical contact with a first cladding portion of the gain section 20, and is configured to provide pump light capable of optically exciting dopants in a plurality of core portions of the gain section 20.

[0124] There are various ways to arrange the core portions in the gain segment 20. Optionally, at least some, all the core portions may be arranged in a substantially cyclically symmetrical manner around the central axis of the multi-core fiber 10. According to different embodiments of spatial arrangement of the core portions, each contact between the pump fiber 102 and the first cladding portion is arranged within a fan-shaped region formed by the axes of two adjacent core portions and the central axis of the multi-core fiber 10. Preferably, each contact is arranged to be substantially equidistant from the axes of the two adjacent core portions.

[0125] Figures 9A and 9C show cross-sectional schematic diagrams of two different embodiments of the multi-core fiber gain segment 20. In the embodiment shown in Figure 9A, each core 22 in the gain segment 20 is directly surrounded by a first cladding portion 24, and the refractive index of the first cladding portion 24 is lower than that of the core 22, so that the optical signal transmitted in the core 22 can achieve total internal reflection at the interface between the core and the first cladding portion.

[0126] In another embodiment shown in Figure 9C, each core 22 is first surrounded by a second cladding portion 23, and the second cladding portion 23 is then surrounded by a first cladding portion 24. The refractive index of the second cladding portion 23 is lower than that of the core 22, allowing total internal reflection of the optical signal at the interface between the core and the second cladding portion 23.

[0127] As further shown in Figure 8, the optical amplification module 100 includes a plurality of pump light sources 101. Each pump light source 101 is optically coupled to the gain section 20 via a pump fiber 102 that is optically in contact with the first cladding portion 24 of the gain section 20 (in either the embodiment shown in Figure 9A or Figure 9C), and is configured to provide pump light capable of optically exciting dopants in a plurality of cores of the gain section 20. The pump fiber 102 allows pump light from the pump light source 101 to be coupled into the first cladding portion 24 through contact coupling, thus in the gain section 20, the first cladding portion 24 substantially serves as the pump cladding in any embodiment for transmitting pump light from the plurality of pump light sources.

[0128] It should be noted that, for the gain segment embodiment that simultaneously includes a second cladding portion 23 (immediately adjacent to the core portion 22) and a first cladding portion 24 (located around the second cladding portion 23) (as shown in FIG. 9C), the cross-sectional shape of the first cladding portion 24 may optionally be non-circular, so as to better utilize the pump light compared to a circular cross-section. In the specific embodiment shown in FIG. 9C, the cross-sectional shape of the first cladding portion 24 is fan-shaped (i.e., a circle missing a portion). Other cross-sectional shapes may also include triangles, squares, pentagons, hexagons, etc.

[0129] In pump light injection schemes from multiple pump sources, various methods are possible. Optionally, each pump light can be injected into the pump cladding via end-face pumping or side pumping. Preferably, the pump light uses side pumping, i.e., the pump fiber 102 from the pump source is fused to the first cladding portion 24 of the gain section 20. Further optionally, the pump light can be transmitted via forward pumping or reverse pumping (where the pump light propagates in the opposite direction to the signal light after entering the pump cladding).

[0130] The contact positions between the pump fiber 102 and the pump cladding portion (i.e., the first cladding portion 24) can also be arranged in various ways. Optionally, as shown in Figure 9A, at least two contact points 26 are located at different positions on the same cross section perpendicular to the longitudinal axis of the gain segment 20; or as shown in Figure 9B, at least two contact points 26 are located at different positions along the longitudinal axis of the gain segment 20.

[0131] There are various ways to arrange the cores in gain segment 20. Optionally, at least some (or all) of the cores are arranged in a basically annular symmetrical distribution around the central axis of the multi-core fiber 10. "Annular symmetry" as described in this disclosure means that the appearance of an object (such as a multi-core fiber) remains unchanged after rotating around its central axis at a fixed angle, typically 360° / n, where n is the order of symmetry. In the example shown in Figure 10A, gain segment 20 contains three cores 22a, 22b, and 22c (represented by shaded circles), surrounded by the first cladding portion 24. The three cores are arranged in a ring around the central axis O, and the angle between the central axes of adjacent cores is 120° (i.e., 360° / 3).

[0132] In the relevant example shown in Figure 10B, in addition to the three annular cores 22a–22c, the gain segment 20 also includes a central core 22d, whose central axis coincides with the central axis O of the gain segment. The four cores are also basically distributed in a circular symmetrical pattern.

[0133] Other examples include: the four- or five-core layout shown in Figure 10C (with or without a central core), the five- or six-core layout shown in Figure 10D, and the six- or seven-core layout shown in Figure 10E. It should be noted that these embodiments are for illustrative purposes only and do not constitute a limitation on the scope of this disclosure.

[0134] In any of the above embodiments with a ring-shaped core distribution, the contact point between each pump fiber 102 and the first cladding portion 24 is located within a fan-shaped region formed by the central axes of two adjacent cores and the central axis of the multi-core fiber 10, and preferably at equidistant positions from the two core central axes. This spatial arrangement allows the pump light entering the first cladding portion 24 to be fully utilized to amplify the optical signal transmitted in the core 22 of the gain section 20.

[0135] For example, in the three-core structure shown in Figure 10A, the three contact points 26a–26c are located in the three sectors OA–OB, OB–OC, and OC–OA, respectively, and the contact points are preferably located at equidistant lines (e.g., point D satisfies DA = DB). In the four-core structure shown in Figure 10B, the three contact points are located in the three sectors OA–OB, OB–OC, and OC–OA, respectively.

[0136] For a four / five-core (Figure 10C) annular symmetrical structure, four contact points can be arranged in each of the four sectors; for a five / six-core (Figure 10D) annular symmetrical structure, five contact points can be arranged; and for a six / seven-core (Figure 10E) annular symmetrical structure, six contact points can be arranged.

[0137] In summary, for a gain segment containing N (N>1) cores uniformly distributed on a ring structure (optionally including a central core), multiple pump light sources from the optical amplification module 100 can be optically coupled to the gain segment 20 through N contact points arranged in N sectors.

[0138] In any of the above-described optical amplification module 100 embodiments, each core may be configured to have a second cladding portion 23 around its periphery, the second cladding portion 23 being surrounded by a first cladding portion 24, and the refractive index of the second cladding portion 23 being higher than that of the core and higher than that of the first cladding portion 24.

[0139] The following three specific examples will be provided to further illustrate the invention disclosed herein.

[0140] Example 1: Parallel 7-core Erbium-doped Fiber Amplifier

[0141] In this embodiment, a parallel 7-core erbium-doped fiber amplifier is described in detail, which essentially represents a specific embodiment of the aforementioned optical amplification module.

[0142] Figure 11 A schematic diagram of an optical amplification system using a parallel seven-core erbium-doped fiber amplifier as the optical amplification module is shown. As shown, the system includes a pair of seven-input FIFO devices (shown as "FIFO" in the figure), used as input devices (i.e., "input FIFO") and output devices (i.e., "output FIFO"), respectively. The input FIFO (i.e., the FIFO device on the left) is connected to the input end of the seven-core erbium-doped fiber (i.e., the left end, shown as "multi-core fiber" in the figure, which is actually the gain section of the optical coupling of the optical amplification module), and the output end of the seven-core erbium-doped fiber (i.e., the right end) is connected to the output FIFO (i.e., the FIFO device on the right).

[0143] Cladding pumping is provided by a pump module comprising six pump submodules (i.e., pump lasers, shown as "Pump 1", "Pump 2", "Pump 3", "Pump 4", "Pump 5", and "Pump 6" in the figure), which is essentially the optical amplification module of the aforementioned optical amplification system. In this specific embodiment, six multimode fibers (i.e., pump fibers, such as...) from the six pump submodules... Figure 11 The curve connecting the six pump sub-modules to the seven-core erbium-doped fiber (as shown in the figure) is tapered and fused to the surface of the stripped-out seven-core erbium-doped fiber for coupling. The six pump fibers are distributed in basically the same longitudinal position, spaced about 60° apart.

[0144] The specific locations of the six pump fibers are as follows: Figure 12 As shown, this figure provides a cross-sectional view of a seven-core doped fiber in contact with six pump fibers on the outer surface of the fiber. As illustrated, within the fiber cladding, six cores (C1-C6) are arranged in a cyclically symmetrical ring structure, with a seventh core (C7) located at the center of the fiber. The six pump fibers (F1-F6) are distributed substantially uniformly on the outer surface of the fiber, spaced approximately 60° apart. Each pump fiber is positioned to contact the cladding on the outer surface of the fiber, around every two adjacent ring cores (i.e., C1-C6). For example, pump fiber F2 contacts the fiber near the contact positions of two adjacent ring cores C1 and C2, pump fiber F3 contacts the fiber near the contact positions of two adjacent ring cores C2 and C3, and so on. This spatial arrangement helps control the gain value.

[0145] To establish contact between each pump fiber and the outer surface of the fiber, fusion taper technology (such as...) can be used. Figure 13 (As shown in the photo), this allows for optical coupling between the pump submodule and the fiber cladding. Figure 14 The coupling efficiency of this arrangement is approximately 90%. The six pump fibers are driven by six pump lasers, and the output power allocation of each laser is used to independently control the gain of each fiber core.

[0146] When the pump light enters the erbium-doped fiber, spontaneous emission energy is excited. After the pump laser is filtered out in the cladding, the 980 nm pump light is absorbed by the fiber core and undergoes further energy level transitions, thus generating spontaneous emission in the C / L band. The end-face diagram of the seven-core erbium-doped fiber amplifier, the cladding pump light distribution, and the spontaneous emission energy of the fiber core after filtering out the cladding pump light are shown below. Figure 15A , 15B As shown in Figure 15C, each FIFO input signal can be discretely amplified through each fiber core.

[0147] The gain of each fiber core is dynamically adjusted by controlling the input values ​​of six pump lasers. In this example, the goal is to minimize the gain difference between each channel. Due to variations in the manufacturing process, each fiber core has different absorption and emission coefficients, and the same pump power would amplify these differences equally. By independently controlling the six pump lasers, higher pump power is provided to the cores with poorer absorption, and lower pump power is provided to the cores with better absorption, thus balancing the gain values ​​of all channels. In this example, the pump power configuration is set as follows: Pump 1 = Pump 2 = 5 W; Pump 3 = Pump 4 = 9 W; Pump 5 and Pump 6 are off.

[0148] By changing the fiber length or rare-earth doping, the same structure and methods described above can be used to amplify other communication bands. The amplification result in the L-band is as follows: Figure 16B As shown, its fiber length is that of a C-band amplifier (its amplification result is as follows). Figure 16A (as shown) is six times that of the previous year.

[0149] Example 2: Parallel 4-core doped fiber amplifier

[0150] In this embodiment, a parallel 4-core doped fiber amplifier is described in detail, which represents another embodiment of the above-described optical amplification module.

[0151] Figure 17 A schematic diagram of an optical amplification system using a parallel 4-core doped fiber amplifier as an optical amplification module is shown. As shown in the figure, the system includes a pair of N-input FIFO devices (shown as "FIFO" in the figure), which are used as input devices (i.e., "input FIFO") and output devices (i.e., "output FIFO"), respectively. The input FIFO is connected to the input end of the four-core erbium-doped fiber (i.e., the left end, shown as "multi-core fiber" in the figure, which is actually the gain section that can be operatively coupled to the optical amplification module), and the output end of the four-core erbium-doped fiber (i.e., the right end) is connected to the four-core VOA[1] (shown as "VOA" in the figure, Variable Optical Attenuator), which can be operatively connected to the output FIFO.

[0152] The cladding pump is provided with excitation energy by a pump module comprising four multimode fiber pump sub-modules (shown in the figure as "Pump 1", "Pump 2", "Pump 3", and "Pump 4"), which is essentially the optical amplification module of the aforementioned optical amplification system. The four multimode fibers are tapered and fused to the surface of a four-core erbium-doped fiber. More specifically, the four multimode fibers are positioned in pairs, with Pump 1 and Pump 2 longitudinally spaced 30 cm apart along the optical signal transmission direction on the four-core erbium-doped fiber, and Pump 3 and Pump 4 positioned 180° relative to Pump 1 and Pump 2. This spatial arrangement aims to enhance the pump light energy in the cladding and improve amplification efficiency.

[0153] Figures 18A and 18B show cross-sectional views of a four-core erbium-doped fiber, which is essentially a double-clad structure. The refractive indices of the four cores 4 are all approximately 1.467, matching the refractive index of a standard single-mode fiber. Each core 4 is immediately surrounded by a high-refractive-index cladding 3 (approximately 1.456), which serves as a pedestal. The outer surface of each cladding 3 is further covered by a non-circular cladding 2 (approximately 1.444). A coating layer 1 (approximately 1.421) is then applied to the outside of cladding 2.

[0154] Cladding 2 is designed as the pump cladding (i.e., the cladding portion from which pump light from the four multimode pump fibers connected by pump sources pump 1, pump 2, pump 3, and pump 4 enters and propagates). Its non-circular structure aims to improve the core-cladding ratio and enhance pump utilization efficiency. The high-refractive-index cladding 3, located between core 4 and pump cladding 2, is designed to effectively concentrate and guide the pump light from cladding 2 to the core region, thereby further improving pump utilization efficiency.

[0155] In this example, VOA employs an integrated variable neutral density filter bank as the optical attenuation component, combined with a collimating lens group and multi-core input / output fibers to form an optically tunable attenuation structure. The input signal light exits from the input fiber, is collimated by the first collimating lens group, passes through the tunable filter, and is then recoupled into the output fiber by the second lens group, achieving transmission and power adjustment of the signal light in each channel.

[0156] The neutral density filter is configured to move vertically to adjust its effective absorption area in the beam path, thereby achieving continuous output power adjustment. Because the channels are independently arranged and remain isolated, this structure allows for discrete attenuation and precise gain control of the output signal of each fiber in the multi-core amplifier. For example... Figure 19 As shown, by manually adjusting the VOA, uniform amplification of the four channels (i.e., C1, C2, C3 and C4) can be achieved with a gain difference of less than 0.5 dB.

[0157] Example 3: Dynamic Gain Control System

[0158] This embodiment illustrates a dynamic gain control system for amplifying multi-channel optical signals transmitted in a multi-core optical fiber, and further illustrates a method for dynamically, in parallel, and tunably controlling the gain of multi-channel optical signals using this control system. This dynamic gain control system essentially represents a specific embodiment of the aforementioned optical amplification system, which is operatively coupled to an N-core erbium-doped fiber and substantially utilizes optical amplification and attenuation modules to achieve dynamic, parallel, and tunable gain control of the multi-channel optical signals.

[0159] Figure 20 A schematic diagram of this dynamic gain control system is shown. As shown, the system includes a pair of N-input FIFO devices (displayed as "FIFO" in the figure), used as the input FIFO (fan-in, fan-out) and output FIFO, respectively. The input FIFO is connected to the input end of an N-core erbium-doped fiber (i.e., the left end, shown as "multi-core fiber" in the figure, which is essentially the gain section that can be operatively coupled in the optical amplification system), and the output end of the N-core erbium-doped fiber (i.e., the right end) is connected to an electrically controlled VOA (displayed as "VOA" in the figure), which is further operatively connected to the output FIFO. Here, the VOA is essentially the optical attenuation module of the aforementioned optical amplification system.

[0160] Cladding pumping is powered by a pump module comprising two multimode fiber pump submodules (shown as "Pump 1" and "Pump 2" in the diagram), which is essentially the optical amplification module of the aforementioned optical amplification system. Two pump fibers from the two pump submodules are optically coupled to an N-core fiber via tapered fusion splices. The real-time feedback node (essentially the controller module of the aforementioned optical amplification system) communicates with the VOA and the two pump submodules via three serial ports (i.e., "Serial Port 1," "Serial Port 2," and "Serial Port 3" in the diagram), thus forming a closed-loop feedback system. Each FIFO device at the output end is equipped with a 99:1 optical splitter (not shown), configured to direct 1% of the power to the real-time feedback node for power monitoring.

[0161] In this illustrative example, the N-core fiber contains four cores (i.e., N = 4), and each of the two pump submodules has a power of 15 W and emits pump light at a wavelength of 980 nm. The two pump submodules are positioned at different locations along the N-core fiber: pump 1 is placed 30 cm from the fiber input end, and pump 2 is placed 30 cm from the fiber midpoint. This configuration allows for more efficient control of the gain distribution of each fiber core, thus providing finer modulation capabilities. The pump laser of each pump submodule can be adjusted from 0-100% output power with a resolution of 0.1% and a response time of less than 1 ms via control circuitry.

[0162] Figure 21The control circuit diagram of the real-time feedback node (i.e., the controller module) of the dynamic gain control system is shown. As shown, the controller module is equipped with a 32-bit ARM (Advanced RISC Machine) processor running at 120 MHz as its core, and further equipped with 12-bit analog-to-digital converter (ADC) and digital-to-analog converter (DAC) submodules. The ADC submodule acquires four-channel optical power signals from the optical splitter at a sampling rate of 100 Hz and a resolution of 0.05 dB. The controller module includes two DAC submodules: one for controlling the attenuation of the VOA, and the other for adjusting the pump laser output power of the pump module. Based on the acquired optical power data and the preset control algorithm (or control logic), the ARM processor calculates the required VOA attenuation level and the required pump power adjustment level, and then transmits the corresponding control signals through the DAC submodules.

[0163] The control circuit employs a dual-power supply design, featuring a 5V main power supply and a 3.3V auxiliary power supply, ensuring stable operation in complex electromagnetic environments. The controller module also incorporates overvoltage protection and temperature monitoring. Upon detecting an anomaly, a protection mode is automatically triggered to prevent damage to the control circuit.

[0164] The electrically controlled VOA employs MEMS (Micro-Electro-Mechanical Systems) technology. Specifically, a movable mirror is used on the MEMS chip to suppress the coupling between the input laser power and the output fiber. The tilt angle of the mirror can be controlled by applying a voltage to achieve the desired attenuation level. The MEMS VOA in this embodiment operates in the C-band (1525-1570 nm) with an attenuation range of 0-40 dB, featuring normally-on attenuation and steplessly adjustable resolution. The VOA has an attenuation response time of less than 5 ms, insertion loss of less than 0.7 dB, polarization-dependent loss of less than 0.2 dB@15 dB, and return loss of greater than 45 dB. It operates at 5V with a power consumption of less than 0.5 mW and can handle a maximum input optical power of 500 mW. The device complies with Telcordia 1209 and 1221 standards, exhibiting excellent shock and vibration resistance, making it suitable for long-term stable operation in harsh environments. The MEMS VOA's drive circuit uses a high-precision operational amplifier design with low noise and high linearity characteristics, ensuring precise attenuation control.

[0165] The control logic of the real-time feedback node (i.e., the controller module) is based on an improved PID control strategy and further combined with an adaptive parameter adjustment mechanism. It can automatically optimize control parameters based on the real-time operating conditions of the system, thereby achieving more precise gain adjustment.

[0166] The dynamic gain control system in this embodiment supports multiple operating modes, such as output power balancing mode, customized power allocation mode, and dynamic response mode. In output power balancing mode, the system ensures that the output power of the four channels remains consistent, with a maximum allowable power deviation of ±0.2 dB. When the power difference between any channel exceeds a threshold, the system... Figure 22 The flowchart shown illustrates the control decisions made. If the power deviation is less than 1 dB, the system prioritizes fine-tuning via VOA attenuation (i.e., through the optical attenuation module); if the power deviation is greater than 1 dB, the system adjusts the output power of the pump laser (i.e., through the optical amplification module). This hierarchical control strategy is employed because VOA-based adjustments typically offer faster response and higher accuracy, but have a limited adjustment range, while pump power adjustments, although slower, enable greater gain adjustment. Through this coordination, the system maintains high accuracy when handling various complex operating conditions.

[0167] In custom power allocation mode, users can set target output power or power ratio for each channel via the control interface. For example, the power ratio between channel 1 and channel 2 can be set to 2:1, or the output power of channel 3 can be set to 20 dBm and channel 4 to 18 dBm. The system uses the same control logic to automatically adjust VOA attenuation and pump power configuration to achieve the user-specified power allocation. This mode is particularly suitable for wavelength division multiplexing systems that require specific power levels for each wavelength channel, or spatial diversity systems that require differentiated amplification of different spatial modes.

[0168] Figure 22 A detailed flowchart of the dynamic gain control algorithm is shown. Upon startup, the system first initializes, setting the initial pump power configuration (Pump 1 = 10 W, Pump 2 = 10 W) and initial VOA attenuation values ​​(5 dB for all channels). The system then collects the initial output power of each channel to establish baseline data. During the real-time monitoring phase, the system samples the power values ​​of the four output channels at a frequency of 100 Hz, calculates the deviation between the current power value and the target value, and determines whether the deviation exceeds a preset threshold. If the deviation exceeds the threshold, the system enters the control decision phase, selecting an appropriate adjustment method based on the deviation. If the deviation is less than 1 dB, the system performs VOA fine-tuning; if the deviation is greater than or equal to 1 dB, the pump power is adjusted. If a channel reaches the upper limit (attenuation > 35 dB) or lower limit (attenuation < 1 dB) of the VOA adjustment, the system triggers a reconfiguration of the pump power.

[0169] In the specific implementation of the above embodiments, the technical features can be combined in any non-contradictory way. For the sake of brevity, not all possible combinations of the above technical features are described. However, as long as the combination of these technical features is not contradictory, it should be considered to be within the scope of this specification.

[0170] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. An optical amplification system, characterized in that, The system includes an optical amplification module, an optical attenuation module, a sensor module, and a controller module. The optical amplification module is optically coupled to the gain section of a multi-core optical fiber and configured to tunably amplify the multi-channel optical signals transmitted in the gain section. The optical attenuation module is located at the output end of the gain section along the optical signal transmission direction and is configured to perform parallel and tunable attenuation of each optical signal output from the gain section. The optical attenuation module includes multiple attenuation sub-modules, each located downstream of the corresponding core of the gain section, and each attenuation sub-module includes a fixed optical attenuator or a variable optical attenuator. Each attenuation sub-module can be adjusted by an electrical signal. The sensor module detects the output optical signal information and sends the output optical signal information to the controller module. The controller module modulates the optical amplification module and / or the optical attenuation module based on the received output optical signal information and control logic. The optical amplification system is configured to modulate the optical amplification module and / or the optical attenuation module based on the optical signal information output from the gain section or the optical attenuation module and control logic, thereby achieving parallel and tunable amplification of multi-channel optical signals in a multi-core optical fiber. The gain segment comprises multiple cores and a first cladding layer, the first cladding layer covering the periphery of the cores, the refractive index of the first cladding layer being lower than that of the cores; at least one core in the gain segment is also covered by a second cladding layer, the second cladding layer being covered by the first cladding layer and having a higher refractive index than the first cladding layer; at least one core is doped with rare earth elements; the optical amplification module comprises multiple pump light sources, each pump light source being optically coupled to the multi-core fiber through the first cladding layer of the gain segment, and providing pump light to excite the rare earth elements; each pump light source can be independently modulated to provide tunable pump light for optical amplification of the multi-channel optical signals transmitted in the gain segment; each pump light source is optically coupled to the gain segment through a pump fiber, the pump fiber being in contact with the first cladding layer, allowing the pump light to enter the first cladding layer; In addition, the contact positions between the pump fiber and the first cladding include: at least two contact points located at different positions on the same cross section perpendicular to the longitudinal axis of the gain segment; or at least two contact points located at different positions along the longitudinal axis of the gain segment; the spatial arrangement of the cores in the gain segment includes: at least a portion of the cores are symmetrically distributed in a ring around the central axis of the multi-core fiber; each contact point between the pump fiber and the first cladding is located within a fan-shaped region formed by the central axes of two adjacent cores and the central axis of the multi-core fiber; the gain segment includes N cores uniformly distributed on the ring structure, and also includes a central core coaxial with the multi-core fiber; multiple pump light sources are optically coupled to the gain segment through N contact points, where N > 1.

2. The optical amplification system according to claim 1, characterized in that, The controller module is not communicatively connected to the optical amplification module, but is communicatively connected to the optical attenuation module and is configured to modulate the optical attenuation module based on the optical signal information output from the optical attenuation module and control logic.

3. The optical amplification system according to claim 1, characterized in that, The controller module is communicatively connected to both the optical amplification module and the optical attenuation module, wherein the controller module is configured to modulate one or both of the optical amplification module and / or the optical attenuation module based on the optical signal information output from the optical attenuation module and control logic.

4. The optical amplification system according to claim 1, characterized in that, Each of the attenuation submodules includes a variable optical attenuator, which is of the following types: variable neutral density filter type, liquid crystal type, or air gap type.

5. The optical amplification system according to claim 1, characterized in that, The output optical signal information includes output optical power and / or output wavelength.

6. The optical amplification system according to claim 1, characterized in that, It also includes at least one of the following: an optical power meter for detecting the optical power of the output optical signal; and an optical wavelength meter for detecting the wavelength of the output optical signal.

7. The optical amplification system according to claim 1, characterized in that, The control logic is a preset logic, which is automatically set based on the PID control strategy.

8. The optical amplification system according to claim 1, characterized in that, The optical amplification system also includes a temperature sensor for detecting the temperature of the gain section. When the detected temperature is higher than a first threshold, the optical amplification system is configured to modulate the optical amplification module and / or the optical attenuation module.

9. The optical amplification system according to claim 1, characterized in that, The optical amplification system also includes a current sensor for detecting the operating current of each pump light source in the optical amplification module. When the current is higher than a second threshold, the optical amplification system is configured to modulate the corresponding pump light source.

10. The optical amplification system according to claim 1, characterized in that, The pump fiber is connected to the first cladding by fusion splicing.

11. A control method for an optical amplification system, characterized in that, To achieve dynamic, parallel, and tunable amplification of multi-channel optical signals in multi-core optical fibers, the following steps are included: S1. To provide an optical amplification system as described in any one of claims 1 to 10, and to configure the optical amplification system to be operatively connected to a multi-core optical fiber; S2. Acquire optical signal information output from the gain section or optical attenuation module; S3. Based on the output optical signal information and control logic, modulate the optical amplification module and / or optical attenuation module.

12. The control method for the optical amplification system according to claim 11, characterized in that, The optical amplification system configuration in step S1 includes: optically coupling the optical amplification module to the gain section of the multi-core optical fiber, and setting the optical attenuation module downstream of the gain section along the optical signal transmission direction.

13. The control method for the optical amplification system according to claim 11, characterized in that, The sensor module is configured to detect output optical signal information and send it to the controller module; the controller module is configured to modulate the optical amplification module and / or the optical attenuation module based on the received output optical signal information and control logic.

14. The control method for the optical amplification system according to claim 11, characterized in that, The controller module is configured to control the optical attenuation module without controlling the optical amplification module, specifically including: in step S1: connecting the controller module to the optical attenuation module for communication; in step S2: acquiring the optical signal information output by the optical attenuation module through the sensor module; in step S3: modulating the optical attenuation module according to the output optical signal information and control logic through the controller module.

15. The control method for the optical amplification system according to claim 11, characterized in that, The controller module is configured to control the optical amplification module and the optical attenuation module, specifically including: in step S1: the controller module is communicatively connected to both the optical amplification module and the optical attenuation module; in step S2: the optical signal information output by the optical attenuation module is acquired through the sensor module; in step S3: the optical amplification module and / or the optical attenuation module are modulated by the controller module according to the output optical signal information and control logic.

16. The control method for the optical amplification system according to claim 11, characterized in that, The control logic is a preset logic, which is automatically set based on the PID control strategy.

17. The control method for the optical amplification system according to claim 11, characterized in that, The control logic includes: determining whether the output optical signal meets a certain preset condition; if it does, acquiring the output information; otherwise, modulating the optical amplification module and / or the optical attenuation module.

18. The control method for the optical amplification system according to claim 11, characterized in that, The preset conditions are configured to one of the following modes: output power equalization mode, custom power allocation mode, or dynamic response mode.

19. The control method for the optical amplification system according to claim 18, characterized in that, The output power equalization mode includes: the maximum output power deviation does not exceed a preset threshold.

20. The control method for the optical amplification system according to claim 18, characterized in that, The custom power allocation mode includes at least one of the following: the output power of a selected subset of channels reaches a preset first target value; the power ratio of a selected subset of channels reaches a preset second target value.

21. The control method for the optical amplification system according to claim 11, characterized in that, In step S1, the optical amplification system includes a temperature sensor for detecting and sending the gain section temperature to the controller module; the controller module modulates the optical amplification module and / or the optical attenuation module based on the detected temperature information. Step S2 includes: obtaining the gain section temperature through the temperature sensor; Step S3 includes: if the temperature is higher than a first threshold, modulating the optical amplification module and / or the optical attenuation module through the controller module.

22. The control method for the optical amplification system according to claim 11, characterized in that, In step S1, the optical amplification system includes a current sensor for detecting and sending the operating current of each pump light source to the controller module; The controller module adjusts the corresponding pump light source according to the operating current. Step S2 includes: acquiring the operating current through the current sensor; Step S3 includes: if the current is higher than the second threshold, the controller module modulates the corresponding pump light source.

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