Pump recovery-based amplifier system and amplification method

Abstract

The invention relates to an amplifier system based on pumping recovery, and the system comprises a pumping laser unit which is used for generating pumping light; the input end of the pump light distribution unit is connected with the pump laser unit, and the pump light distribution unit is used for receiving the pump light and distributing the pump light to a plurality of parallel light paths; the multi-core gain optical fiber unit is used for providing optical gain for the signal light; the signal reflection unit is arranged on one side of the multi-core gain optical fiber unit and is used for transmitting the pump light and reflecting signal light; and the pumping recovery unit is arranged on the other side of the multi-core gain optical fiber unit and is used for transmitting the signal light and reflecting the pumping light. According to the invention, signal reflection and pumping recovery are realized by using the multi-core fiber bragg grating, discrete isolators and combiners which are massively used in the traditional scheme are replaced, and the number of optical devices and welding points are reduced, so that the insertion loss of the system is reduced, and the working stability is improved.

Description

Technical Field

[0001] This invention relates to the field of optical communication technology, and specifically to an amplifier system and amplification method based on pump recovery. Background Technology

[0002] The rapid development and widespread adoption of global mobile internet, short videos, the Internet of Things, cloud computing, and 5G / 6G communication technologies have placed an almost insatiable demand on the transmission capacity of fiber optic communication networks. Limited by the nonlinear Shannon limit of single-mode fiber, its transmission capacity is nearing its theoretical ceiling. Against this backdrop, space division multiplexing (SDM) technology based on multi-core fibers is considered a key path to overcome capacity bottlenecks and expand the capacity of next-generation trunk transmission systems. The practical application of SDM technology not only requires solving the fabrication and connection problems of multi-core fibers themselves, but also relies on a crucial device capable of efficiently and synchronously amplifying weakened signals in all fiber cores within the transmission link—the multi-core erbium-doped fiber amplifier.

[0003] Traditional multi-core fiber amplifiers typically employ a parallel amplification architecture, where each fiber core is equipped with an independent and complete amplification unit, including a pump laser, wavelength division multiplexer, isolator, and corresponding erbium-doped fiber segment. While this architecture is simple in principle, it results in a large system size, high cost, and significant power consumption. Furthermore, due to the use of numerous fusion splices and discrete optical components, the overall system insertion loss is high, and reliability faces challenges. To simplify the system, the industry has proposed solutions such as pump combining to reduce the number of pump sources, but this still requires independent combining and isolating devices for each fiber core, limiting the improvement in integration. In addition, regardless of whether it is a parallel architecture or a combining solution, the pump light is discarded after passing through the gain medium once, resulting in generally low energy utilization. This not only causes unnecessary energy waste but also limits further improvements in amplifier output power and efficiency. Therefore, there is an urgent need in the field for an innovative multi-core fiber amplifier system that can fundamentally overcome the drawbacks of existing solutions, such as numerous components and low pump utilization, while simultaneously achieving signal light gain and pump light recycling. Summary of the Invention

[0004] This application provides an amplifier system and amplification method based on pump recovery to solve the above-mentioned problems.

[0005] In a first aspect, embodiments of this application provide an amplifier system based on pump recovery, comprising: Pump laser unit, used to generate pump light; A pump light distribution unit, whose input end is connected to the pump laser unit, is used to receive the pump light and distribute it to multiple parallel optical paths; Multi-core gain fiber unit, used to provide optical gain for signal light; A signal reflection unit is disposed on one side of the multi-core gain fiber unit and is used to transmit the pump light and reflect the signal light. A pump recovery unit is disposed on the other side of the multi-core gain fiber unit, which is used to transmit the signal light and reflect the pump light; A multi-core fiber optic path is used to connect the pump light distribution unit, the multi-core gain fiber unit, the signal reflection unit, and the pump recovery unit. The signal input / output unit includes an input port, an output port, and a coupling port. The input port is used to input the signal light to be amplified, the output port is used to output the amplified signal light, and the coupling port is coupled to the multi-core optical fiber path. The signal reflection unit and the pump recovery unit are configured such that after the signal light is input from the signal input / output unit, it can sequentially pass through the pump recovery unit, the multi-core gain fiber unit, be reflected by the signal reflection unit, pass through the multi-core gain fiber unit again, and then return to the signal input / output unit after passing through the pump recovery unit, and be output from the output port of the signal input / output unit.

[0006] In conjunction with the first aspect, in one embodiment, the pump light distribution unit includes a single-core optical fiber, one end of which is connected to the output end of the pump laser unit, and the other end is fused to the pump light input end of the multi-core optical fiber path to form a tapered coupling structure.

[0007] In conjunction with the first aspect, in one embodiment, the multi-core gain fiber unit is a multi-core fiber doped with rare earth ions.

[0008] In conjunction with the first aspect, in one embodiment, the rare earth ion is an erbium ion.

[0009] In conjunction with the first aspect, in one embodiment, the signal reflection unit includes a first multi-core fiber Bragg grating, which is fused to the multi-core fiber optical path.

[0010] In conjunction with the first aspect, in one embodiment, the pump recovery unit includes a second multi-core fiber Bragg grating, which is fused to the multi-core fiber optical path.

[0011] In conjunction with the first aspect, in one embodiment, the signal input / output unit includes a circulator and a fan-in / fan-out device. The first port of the circulator is the input port of the signal light, the third port is the output port of the signal light, and the second port is connected to the fan-in / fan-out device. The fan-in / fan-out device is used to realize signal coupling between the multi-core optical fiber path and the circulator.

[0012] In conjunction with the first aspect, in one embodiment, a gain flattening unit is further included, which is disposed between the coupling port of the pump recovery unit and the signal input / output unit.

[0013] In conjunction with the first aspect, in one embodiment, the gain flattening unit is a gain flattening filter.

[0014] Secondly, embodiments of this application provide an amplification method for an amplifier system based on pump recovery, comprising the following steps: Pump light is generated by the pump laser unit and distributed to multiple parallel optical paths via the pump light distribution unit; The signal light to be amplified is introduced through the input port of the signal input / output unit, so that it is transmitted along the multi-core optical fiber path and passes through the multi-core gain optical fiber unit for the first time to obtain the first amplification; The signal light after the first amplification is transmitted to the signal reflection unit, which reflects the signal light. The reflected signal light is then transmitted in the opposite direction and passes through the multi-core gain fiber unit again to obtain a second amplification. At the pump recovery unit, the pump light that is not absorbed after passing through the multi-core gain fiber unit is reflected back to the multi-core gain fiber unit for reuse; while the signal light after the second amplification is conducted back to the signal input / output unit and output from its output port.

[0015] The beneficial effects of the technical solutions provided in this application include: 1. This application achieves unified pumping of multi-core gain fiber by combining a single pump laser unit with a pump light distribution unit. This can significantly reduce the number of pump sources required for the entire system, thereby reducing costs. At the same time, the multi-core fiber grating is used to realize signal reflection and pump recovery, replacing the discrete isolators and multiplexers used extensively in traditional solutions. This reduces the number of optical components and fusion splices, thereby reducing system insertion loss and improving operational stability.

[0016] 2. This application enables the signal light to travel back and forth twice in the multi-core gain fiber unit through the multi-core gain fiber path, thereby achieving bidirectional amplification and obtaining a higher total gain. Secondly, through the pump recovery unit, the unabsorbed remaining pump light can be reflected back into the multi-core gain fiber unit for reuse, thereby significantly improving the utilization rate of pump light and helping to improve the overall energy efficiency and output performance of the system. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the system connection of the present invention; Figure 2 This is a schematic diagram of the system operation process in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the conical coupling structure of the present invention; Figure 4 This is a flowchart of the method steps in Embodiment 2 of the present invention. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0020] Example 1: Please see Figure 1 This application provides an amplifier system based on pump recovery, comprising: Pump laser unit: It is used to generate pump light. In this embodiment, a semiconductor laser is preferably used as the pump light source. Pump light distribution unit: Its input end is connected to the pump laser unit, and it is used to receive pump light and distribute it to multiple parallel optical paths; Specifically: The pump light distribution unit includes a single-core fiber, one end of which is connected to the output end of the pump laser unit, and the other end is fused to the pump light input end of the multi-core fiber optical path to form a tapered coupling structure. The conical coupling structure is formed as follows: Figure 3 As shown, the end of the single-mode fiber is aligned and fused with the pump input end of the multi-core fiber optical path. Then, the fused area is heated and bidirectionally stretched to form a tapered coupling region with a smooth transition as a power divider. This structure can efficiently and uniformly distribute the pump light transmitted in the single-mode fiber to each core of the multi-core fiber optical path.

[0021] Multi-core gain fiber unit: It is fused onto the multi-core fiber optical path. It is a multi-core fiber doped with rare earth ions and is used to provide optical gain for signal light. In this embodiment, multi-core erbium-doped fiber is used as the gain medium. Its fiber core arrangement is matched with the above-mentioned multi-core fiber optical path, and low-loss connection is achieved through fusion splicing. Under pump light excitation, this fiber can provide optical gain for signal light.

[0022] Signal reflection unit: It is disposed on one side of the multi-core gain fiber unit and connected to the multi-core fiber optical path by fusion splicing. In this embodiment, it is preferably a multi-core fiber Bragg grating, namely the first multi-core fiber Bragg grating, which is used to transmit pump light and reflect signal light. Pump recovery unit: It is located on the other side of the multi-core gain fiber unit and is connected to the multi-core fiber optical path by fusion splicing. In this embodiment, it is preferably a multi-core fiber Bragg grating, that is, a second multi-core fiber Bragg grating, which is used to transmit signal light and reflect pump light. The signal input / output unit includes an input port, an output port, and a coupling port. The input port is used to input the signal light to be amplified, the output port is used to output the amplified signal light, and the coupling port is coupled to the multi-core optical fiber path. Specifically, the signal input / output unit consists of a circulator with three ports and a fan-in / fan-out device. The first port of the circulator serves as the input port for the signal light, and the third port serves as the output port for the amplified signal light. The second port of the circulator is connected to the single-core end of the fan-in / fan-out device, and the multi-core end of the fan-in / fan-out device is coupled to the multi-core optical fiber path, thereby realizing the conversion between single-channel and multi-channel signals.

[0023] Also includes: In a preferred embodiment, a gain flattening unit is connected in series in the optical path between the pump recovery unit and the signal input / output unit. This unit is used to eliminate gain differences between wavelength channels to ensure gain consistency across all wavelength channels. Specifically: Gain flattening unit: In this embodiment, a gain flattening filter is preferably disposed between the pump recovery unit and the signal input / output unit coupling port; The system works as follows: Please see Figure 2 In the diagram, the blue route represents a single-core fiber, and the red route represents a multi-core fiber optical path. The signal light to be amplified is input from the first port of the circulator, output from its second port, and then coupled through the fan-in and fan-out devices to pass through the gain flattening filter, the second multi-core fiber Bragg grating, and is amplified for the first time at the multi-core erbium-doped fiber before reaching the first multi-core fiber Bragg grating. After being amplified once, the signal light is reflected by the first multi-core fiber Bragg grating and then reversed. The reverse-propagated signal light passes through the multi-core erbium-doped fiber again to obtain a second amplification. After being amplified twice, the signal light passes through the second multi-core fiber Bragg grating and is then optimized for spectral shape by a gain flattening filter. Finally, it is collected by a fan-in fan-out device and coupled back to the second port of the circulator, and finally output from its third port, thus completing the entire signal light amplification process. In this process, the signal light is amplified twice by the multi-core erbium-doped fiber, thereby obtaining a higher total gain. Meanwhile, the pump light generated by the laser is uniformly injected into the multi-core fiber optical path through the power divider and enters the multi-core erbium-doped fiber in the direction of right transmission, providing energy for signal amplification. The remaining pump light that is not completely absorbed by the multi-core erbium-doped fiber is efficiently reflected back into the multi-core erbium-doped fiber when it is transmitted to the second multi-core fiber Bragg grating, and is used for secondary or even multiple times until the energy is fully absorbed, thereby significantly improving the utilization efficiency of the pump light.

[0024] This embodiment achieves the combined effects of multi-core amplification, bidirectional signal gain, and pump recycling using a single laser through the above-described specific configuration. The system has a compact structure, low loss, and high efficiency.

[0025] Example 2: Please see Figure 4 This second embodiment provides a signal optical amplification method based on a pump recovery amplifier system. The method uses the pump recovery amplifier system as described in the first embodiment, and specifically includes the following steps: S1. Pump light generation and distribution: The pump laser unit is activated to generate pump light, which is then transmitted to the input of the pump light distribution unit. The pump light distribution unit then distributes the pump light power evenly to multiple parallel optical paths, which are then injected into the multi-core fiber optic path of the system. S2, Signal light input and forward amplification: The input signal light to be amplified is introduced into the system through the input port of the signal input / output unit. The signal light enters the multi-core fiber optical path through the coupling port of the signal input / output unit and is transmitted along the optical path. During the transmission process, the signal light passes through the multi-core gain fiber unit for the first time and realizes the first optical amplification by using the energy provided by the pump light. S3. Signal light reflection and reverse amplification: After the first amplification, the signal light continues to travel along the optical path and reaches the signal reflection unit. Utilizing the high reflectivity of the signal light wavelength, the signal light is reflected. The reflected signal light reverses its transmission direction, travels in the opposite direction along the optical path, and passes through the multi-core gain fiber unit again, thus obtaining the second optical amplification. S4, Pump Light Recovery: During the signal amplification process described above, after the pump light excites the gain fiber, the residual portion that is not completely absorbed will continue to be transmitted to the pump recovery unit. Utilizing the high reflectivity of this unit to the pump light wavelength, this portion of the pump light is reflected back into the multi-core gain fiber unit for reuse or even multiple uses, thereby realizing the recovery of pump light and improving energy utilization. S5, Signal light output: The signal light, after being amplified a second time, continues to be transmitted in reverse and passes through the pump recovery unit. It is then received by the signal input / output unit and finally output from its output port, completing the entire amplification process.

[0026] Through the above steps, this method achieves bidirectional and efficient amplification of multiple signal beams using a single pump source, and simultaneously completes the recycling of pump energy, achieving a comprehensive effect of simplifying system structure, improving gain efficiency and energy utilization.

[0027] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0028] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0029] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. An amplifier system based on pump recovery, characterized in that, include: Pump laser unit, used to generate pump light; A pump light distribution unit, whose input end is connected to the pump laser unit, is used to receive the pump light and distribute it to multiple parallel optical paths; Multi-core gain fiber unit, used to provide optical gain for signal light; A signal reflection unit is disposed on one side of the multi-core gain fiber unit and is used to transmit the pump light and reflect the signal light. A pump recovery unit is disposed on the other side of the multi-core gain fiber unit, which is used to transmit the signal light and reflect the pump light; A multi-core fiber optic path is used to connect the pump light distribution unit, the multi-core gain fiber unit, the signal reflection unit, and the pump recovery unit. The signal input / output unit includes an input port, an output port, and a coupling port. The input port is used to input the signal light to be amplified, the output port is used to output the amplified signal light, and the coupling port is coupled to the multi-core optical fiber path. The signal reflection unit and the pump recovery unit are configured such that after the signal light is input from the signal input / output unit, it can sequentially pass through the pump recovery unit, the multi-core gain fiber unit, be reflected by the signal reflection unit, pass through the multi-core gain fiber unit again, and then return to the signal input / output unit after passing through the pump recovery unit, and be output from the output port of the signal input / output unit.

2. The amplifier system based on pump recovery according to claim 1, characterized in that, The pump light distribution unit includes a single-core optical fiber. One end of the single-core optical fiber is connected to the output end of the pump laser unit, and the other end is fused to the pump light input end of the multi-core optical fiber path to form a tapered coupling structure.

3. The amplifier system based on pump recovery according to claim 1, characterized in that, The multi-core gain fiber unit is a multi-core fiber doped with rare earth ions.

4. The amplifier system based on pump recovery as described in claim 3, characterized in that, The rare earth ion is an erbium ion.

5. The amplifier system based on pump recovery as described in claim 1, characterized in that, The signal reflection unit includes a first multi-core fiber Bragg grating, which is fused to the multi-core fiber optical path.

6. The amplifier system based on pump recovery as described in claim 1, characterized in that, The pump recovery unit includes a second multi-core fiber Bragg grating, which is fused to the multi-core fiber optical path.

7. The amplifier system based on pump recovery as described in claim 1, characterized in that, The signal input / output unit includes a circulator and a fan-in / fan-out device. The first port of the circulator is the input port of the signal light, the third port is the output port of the signal light, and the second port is connected to the fan-in / fan-out device. The fan-in / fan-out device is used to realize signal coupling between the multi-core optical fiber path and the circulator.

8. The amplifier system based on pump recovery as described in claim 1, characterized in that, It also includes a gain flattening unit, which is disposed between the coupling port of the pump recovery unit and the signal input / output unit.

9. The amplifier system based on pump recovery as described in claim 8, characterized in that, The gain flattening unit is a gain flattening filter.

10. An amplification method based on the pump recovery-based amplifier system as described in claim 1, characterized in that, Includes the following steps: Pump light is generated by the pump laser unit and distributed to multiple parallel optical paths via the pump light distribution unit; The signal light to be amplified is introduced through the input port of the signal input / output unit, so that it is transmitted along the multi-core optical fiber path and passes through the multi-core gain optical fiber unit for the first time to obtain the first amplification; The signal light after the first amplification is transmitted to the signal reflection unit, which reflects the signal light. The reflected signal light is then transmitted in the opposite direction and passes through the multi-core gain fiber unit again to obtain a second amplification. At the pump recovery unit, the pump light that is not absorbed after passing through the multi-core gain fiber unit is reflected back to the multi-core gain fiber unit for reuse; while the signal light after the second amplification is conducted back to the signal input / output unit and output from its output port.

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