Filtering-adjustable optical fiber amplifier suitable for satellite laser communication

Abstract

The utility model provides a filtering-adjustable optical fiber amplifier suitable for satellite laser communication, which comprises a shell, an input optical fiber and an output optical fiber are arranged on the shell, and a circuit board, a first-stage amplification unit, a second-stage amplification unit and an adjustable optical filtering unit are arranged in the shell. The circuit board is electrically connected with the first-stage amplification unit, the second-stage amplification unit and the adjustable light filtering unit; the first-stage amplification unit is used for pre-amplifying an input optical signal, and the adjustable optical filtering unit is used for filtering the pre-amplified optical signal; and the second-stage amplification unit performs high-power amplification on the optical signal processed by the adjustable optical filtering unit and outputs the optical signal through an output optical fiber. By arranging the first-stage amplification unit, the second-stage amplification unit and the adjustable light filtering unit in the shell, stage-by-stage amplification and adjustable filtering processing of input light signals are achieved, meanwhile, the system size is reduced through the integrated design, and the light path stability and the system reliability are improved.

Description

Technical Field

[0001] The utility model relates to the field of satellite laser communication, and particularly relates to a fiber amplifier with adjustable filtering applicable to satellite laser communication. Background Art

[0002] In the development process of fiber optic communication systems, fiber amplifiers, as core devices to ensure long-distance and high-quality transmission of optical signals, directly affect the overall performance of communication systems. With the rapid development of emerging technologies such as 5G communication, the Internet of Things, and satellite laser communication, more stringent requirements are put forward for the power output and precise wavelength regulation of fiber amplifiers. Especially in the field of satellite laser communication, due to the signal attenuation problem caused by extremely long transmission links, the transmitting end must provide a sufficiently large signal output optical power to ensure the signal quality after long-distance transmission, which poses higher requirements for the power output and stability of fiber amplifiers.

[0003] However, fiber amplifiers in the prior art generally have problems such as complex structures, large volumes, and low integration levels. For example, a "multi-stage EDFA amplifier" adopts a combination of discrete filters and multi-stage amplification structures, which not only results in an overly large device volume and is difficult to meet the strict restrictions on volume and weight of satellite payloads, but also significant insertion losses (>3dB) and amplified spontaneous emission (ASE) noise are introduced by multi-stage discrete components, reducing signal quality. In addition, there is also a miniaturized tunable optical filter technology in the prior art, which has advantages such as small size and flexible filtering characteristics, but it has not been effectively combined with a high-power two-stage amplification structure and is difficult to meet the dual requirements of wavelength tunability and high-power output (>36dBm) simultaneously, restricting its application in demanding scenarios such as satellite laser communication. Summary of the Utility Model

[0004] To solve the above problems, the utility model provides a fiber amplifier with adjustable filtering applicable to satellite laser communication, including:

[0005] A housing, on which an input optical fiber and an output optical fiber are provided. Inside the housing, there are a circuit board, a first-stage amplification unit, a second-stage amplification unit, and a tunable optical filtering unit. The circuit board is electrically connected to the first-stage amplification unit, the second-stage amplification unit, and the tunable optical filtering unit;

[0006] The first-stage amplification unit pre-amplifies the input optical signal, and the tunable optical filtering unit filters the pre-amplified optical signal; the second-stage amplification unit highly amplifies the optical signal processed by the tunable optical filtering unit and outputs it through the output optical fiber;

[0007] Among them, the first-stage amplification unit includes a first gain fiber and a single-mode pump source coupled to the first gain fiber; the second-stage amplification unit includes a second gain fiber and a multi-mode pump source coupled to the second gain fiber.

[0008] Further, the tunable optical filtering unit includes a tunable optical filter.

[0009] Further, both the single-mode pump source and the multi-mode pump source are fixed in the housing. One end of each pump source is a power supply end electrically connected to the circuit board, and the other end is an optical fiber end coupled to the corresponding gain fiber.

[0010] Further, the circuit board includes an upper circuit board and a lower circuit board connected to each other;

[0011] The lower circuit board is provided with a plurality of fixing holes. The single-mode pump source and the multi-mode pump source respectively pass through the fixing holes and are fixed on the housing.

[0012] Further, the tunable optical filtering unit is fixed on the lower circuit board through a fixing bracket and is electrically connected to the lower circuit board;

[0013] The single-mode pump source is coupled to the first gain fiber through a first beam combiner;

[0014] The multi-mode pump source is coupled to the second gain fiber through a second beam combiner.

[0015] Further, a wavelength division multiplexer is provided between the input optical fiber and the first-stage amplification unit;

[0016] An optical isolator is provided between the output end of the first-stage amplification unit and the tunable optical filtering unit;

[0017] A signal transmission optical fiber is provided between the output end of the tunable optical filtering unit and the second-stage amplification unit.

[0018] Further, a control module is provided on the lower circuit board. The control module is electrically connected to the tunable optical filtering unit, the first-stage amplification unit, and the second-stage amplification unit, and is used to adjust the filtering characteristics of the tunable optical filtering unit and the pump power of the two-stage amplification units.

[0019] Further, an output monitoring unit connected to the output end of the second-stage amplification unit is further included. The output monitoring unit is used to convert a part of the output optical signal into an electrical signal and transmit it to the control module. The control module monitors the output optical power in real time according to the electrical signal and adjusts the working states of the first-stage amplification unit and the second-stage amplification unit.

[0020] Further, a high-power isolator is also provided between the output end of the second-stage amplification unit and the output monitoring unit. The high-power isolator is connected to the output optical fiber and is used to prevent the reflected light from returning to the second-stage amplification unit.

[0021] Compared with the prior art, the present utility model has at least the following beneficial effects: By providing the first-stage amplification unit, the second-stage amplification unit and the tunable optical filter unit in the housing, the step-by-step amplification and tunable filtering processing of the input optical signal are realized, solving the technical problem of difficult spectral control in the high-power output of traditional optical fiber amplifiers. It not only ensures high-power output but also realizes precise adjustment of spectral characteristics. At the same time, this integrated design reduces the system volume, improves the optical path stability and system reliability. Description of the Drawings

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained as provided in the drawings.

[0023] Figure 1 It is a schematic diagram of the internal structure of the housing of the optical fiber amplifier in an embodiment of the present utility model;

[0024] Figure 2 It is a top view of the internal structure of the housing of the optical fiber amplifier in an embodiment of the present utility model;

[0025] Figure 3 It is another schematic diagram of the internal structure of the housing of the optical fiber amplifier in an embodiment of the present utility model;

[0026] Figure 4 It is a basic optical path schematic diagram of the optical fiber amplifier in an embodiment of the present utility model;

[0027] Figure 5 It is an optical path schematic diagram of the optical fiber amplifier in an embodiment of the present utility model;

[0028] Figure 6 It is an optical path schematic diagram of the optical fiber amplifier in another embodiment of the present utility model;

[0029] Figure 7 It is an optical path schematic diagram of the optical fiber amplifier in yet another embodiment of the present utility model.

[0030] Wherein, 1 - input optical fiber; 2 - output optical fiber; 3 - tunable optical filtering unit; 4 - upper circuit board; 5 - lower circuit board; 6 - output monitoring unit; 11 - single-mode pump source; 12 - first beam combiner; 21 - first multimode pump source; 22 - second multimode pump source; 23 - third multimode pump source; 24 - fourth multimode pump source; 25 - second beam combiner. Detailed implementation mode

[0031] The present invention will be described in more detail below with reference to the schematic diagrams, in which the preferred embodiments of the present invention are shown. It should be understood that those skilled in the art can modify the present invention described herein while still achieving the advantageous effects of the present invention. Therefore, the following description should be understood as being widely known to those skilled in the art and not as a limitation on the present invention.

[0032] It should be noted that, in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device.

[0033] In the following paragraphs, the present invention will be described more specifically by way of example with reference to the accompanying drawings. As will be described below, the advantages and features of the present invention will be more clearly understood. It should be noted that the drawings are all in a very simplified form and use non-precise scales, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0034] This embodiment provides a fiber amplifier with tunable filtering applicable to satellite laser communication. Please refer to Figures 1-4 , including:

[0035] A housing, on which an input optical fiber 1 and an output optical fiber 2 are provided. Inside the housing, there are a circuit board, a first-stage amplification unit, a second-stage amplification unit and a tunable optical filtering unit 3. The circuit board is electrically connected to the first-stage amplification unit, the second-stage amplification unit and the tunable optical filtering unit 3;

[0036] The first-stage amplification unit pre-amplifies the input optical signal, and the tunable optical filtering unit 3 filters the pre-amplified optical signal; the second-stage amplification unit highly amplifies the optical signal processed by the tunable optical filtering unit 3 and outputs it through the output optical fiber 2.

[0037] Specifically, the housing can be made of metal or high-strength plastic, and its internal space layout needs to meet the requirements for the installation and heat dissipation of optical components. The input optical fiber 1 and the output optical fiber 2 are preferably single-mode optical fibers or multi-mode optical fibers, which are specifically selected according to the application scenario. The circuit board is a printed circuit board or a flexible circuit board, which is used to provide power supply and signal transmission. The first-stage amplification unit can be implemented by an erbium-doped fiber amplifier or a Raman amplifier to achieve the pre-amplification function. The tunable optical filtering unit 3 is used to filter out the ASE noise and select the target wavelength. The second-stage amplification unit is preferably of a double-clad fiber amplifier structure to achieve high-power output. The optical path connection between the functional units can be realized by fiber splicing or free-space optical path.

[0038] By integrating the tunable optical filtering unit 3 between the two-stage amplification structure, the problems of excessive volume and insertion loss caused by the traditional discrete structure are effectively solved. The first-stage pre-amplification can enhance the signal intensity to compensate for the filtering loss. The tunable filtering unit can accurately select the target wavelength and suppress the ASE noise. The second-stage high-power amplification ensures the final output power. Among them, the cooperative work of the tunable optical filtering unit 3 and the two-stage amplification realizes the unity of wavelength tunability and high-power output.

[0039] Furthermore, the tunable optical filtering unit 3 includes a tunable optical filter (TOF). In this embodiment, the tunable optical filtering unit 3 can be an ETOF or an MTOF.

[0040] Specifically, the MTOF includes a MEMS micromirror and / or a Bragg grating and / or a Fabry-Perot-like thin film cavity. The MEMS micromirror is a micro mirror based on microelectromechanical system technology, and the mirror surface angle is adjusted by electrostatic drive or electromagnetic drive, thereby changing the optical path transmission direction. The Bragg grating is an optical fiber device with periodic refractive index modulation, and its reflection wavelength is determined by the grating period. Exemplarily, the combination implementation of the MEMS micromirror and the Bragg grating includes: fixing the Bragg grating on the end face of the optical fiber, setting the MEMS micromirror at the optical path turning point, and changing the incident angle of the incident light on the Bragg grating by adjusting the deflection angle of the micromirror, thereby realizing continuous tuning of the reflection wavelength. As a preferred implementation mode, the driving voltage range of the MEMS micromirror is 0 - 50V. Further, the Bragg grating can be fabricated by ultraviolet laser writing method, and the central reflection wavelength is designed in the 1200nm - 1600nm band according to the system requirements.

[0041] In contrast, ETOF utilizes the change in material properties caused by an electric field to achieve wavelength-selective regulation. ETOF generally includes electro-optic crystal materials (such as lithium niobate, lithium tantalate, or liquid crystal) and corresponding electrode structures. By changing the magnitude of the applied voltage, the refractive index of the material can be adjusted, thereby changing the transmission characteristics of the optical signal. In this embodiment, ETOF is mainly constructed using liquid crystal materials. The liquid crystal molecules are rearranged under the action of an electric field, changing their refractive characteristics for optical signals of different wavelengths. Exemplarily, this ETOF adopts a cascaded structure of multiple liquid crystal cells and can achieve continuously adjustable wavelength selection in the wavelength band of 1520 nm - 1620 nm. As a preferred implementation, the driving voltage range of ETOF is 0 - 10 V, which is lower than the driving voltage required by MTOF, reducing the power consumption of the system. Further, the response time of ETOF is 1 - 10 ms, meeting the requirements of the fiber optic communication system for wavelength tuning speed.

[0042] Further, the first-stage amplification unit includes a first gain fiber and a single-mode pump source 11 coupled to the first gain fiber.

[0043] The second-stage amplification unit includes a second gain fiber and a multi-mode pump source coupled to the second gain fiber.

[0044] Specifically, the first gain fiber can be an erbium-doped fiber or a ytterbium-doped fiber, and its length range is preferably 1 - 5 meters to achieve preliminary amplification of the input optical signal. The working wavelength range of the single-mode pump source 11 can be 980 nm or 1480 nm, and the output power is controlled between 100 - 500 mW, and wavelength stability is achieved through a fiber Bragg grating. The coupling of the single-mode pump source 11 to the first gain fiber can be achieved by fusion splicing or through a micro-lens group. The second gain fiber is a large-mode-area double-clad fiber, and the core diameter range is 10 - 25 μm to support the transmission of high-power optical signals. The multi-mode pump source adopts a single-tube fiber-coupled output structure, and the output power range is 5 - 20 W, and the working temperature stability is maintained through a water-cooled heat dissipation device. The coupling of the multi-mode pump source to the second gain fiber is achieved by coupling the output optical power of the multi-mode pump source to the input end of the second combiner 25, and the output end of the second combiner 25 is coupled to the input end of the second gain fiber.

[0045] Solve the contradiction between high-power amplification and noise control through a hierarchical pumping design. The single-mode pump source 11 provides precise and controllable primary amplification to ensure signal quality; the multi-mode pump source realizes high-power output. The two work together to ensure both amplification efficiency and effectively suppress amplified spontaneous emission noise. Compared with the solution using a single pumping structure, this design increases the power conversion efficiency by more than 15% while controlling the noise figure below 5 dB. By optimizing the pump coupling structure, a compact package is achieved, and the overall volume is reduced by 40% compared to the traditional solution, which is especially suitable for application scenarios with limited space.

[0046] Furthermore, both the single-mode pump source 11 and the multi-mode pump source are fixed within the housing. One end of each pump source is the power supply end electrically connected to the circuit board, and the other end is the optical fiber end coupled to the corresponding gain fiber.

[0047] Specifically, each pump source has a dual-end structure - one end is the power supply end directly electrically connected to the circuit board to receive electrical energy and control signals; the other end is the optical fiber end coupled to the corresponding gain fiber (such as erbium-doped fiber or erbium-ytterbium co-doped double-clad fiber) to inject pump light into the gain medium. This design not only realizes the functional integration of electro-optical conversion and efficient injection of pump light but also greatly improves the system compactness and optical path stability through the built-in structure, effectively solving the problems of large volume and high coupling loss brought by traditional external pump sources.

[0048] Furthermore, the circuit board includes an upper circuit board 4 and a lower circuit board 5 connected to each other.

[0049] The lower circuit board 5 is provided with a plurality of fixing holes. The single-mode pump source 11 and the multi-mode pump source respectively pass through the plurality of fixing holes and are fixed on the housing.

[0050] Specifically, the aperture size is designed to be φ3 - 5 mm according to the outer diameter of the pump source, and the hole pitch is kept at 15 - 20 mm to ensure heat dissipation space. As a preferred implementation, a rubber anti-vibration ring can be provided on the inner wall of the fixing hole to achieve radial fixation of the pump source through elastic deformation. Further, the fixing holes can be arranged in a straight line or staggered arrangement, and the staggered arrangement can make more effective use of the circuit board space. During the assembly process, first place the lower circuit board 5, then place the pump source in the fixing hole, and then fix the pump source to the housing through a locking nut.

[0051] In this embodiment, the first-stage amplification unit includes a single-mode pump source 11, and the second-stage amplification unit includes a first multi-mode pump source 21, a second multi-mode pump source 22, a third multi-mode pump source 23, and a fourth multi-mode pump source 24. The above five pump sources are arranged in a staggered manner.

[0052] Further, the tunable optical filtering unit 3 is fixed on the lower circuit board 5 through a fixing bracket and electrically connected to the lower circuit board 5.

[0053] The single-mode pump source 11 is coupled to the first gain fiber through a first beam combiner 12.

[0054] The multi-mode pump source is coupled to the second gain fiber through a second beam combiner 25.

[0055] Specifically, the first beam combiner 12 and the second beam combiner 25 are respectively fixed on two sides of the lower circuit board 5. The fixing bracket is made of aluminum alloy. Its top is provided with a U-shaped card slot for fixing the tunable optical filtering unit 3, and its bottom is provided with conductive contacts for fixing to the lower circuit board 5 and realizing electrical connection. The first beam combiner 12 adopts a double-clad fiber fused taper structure. Its input ends are respectively connected to the fiber end of the single-mode pump source 11 and the input signal fiber, and its output end is fusion spliced to the first gain fiber. The second beam combiner 25 adopts an end-pumping coupling structure, including a multi-mode fiber array and a micro-lens group or a fusion splicing and tapering coupling method. After the output fiber of the multi-mode pump source passes through the second beam combiner 25, it is focused or coupled to the cladding of the second gain fiber.

[0056] Further, a wavelength division multiplexer is provided between the input fiber 1 and the first-stage amplification unit.

[0057] An optical isolator is provided between the output end of the first-stage amplification unit and the tunable optical filtering unit 3.

[0058] A signal transmission fiber is provided between the output end of the tunable optical filtering unit 3 and the second-stage amplification unit.

[0059] The wavelength division multiplexer is used to combine input optical signals of multiple wavelengths and transmit them to the first-stage amplification unit. A thin-film filter type or arrayed waveguide grating type wavelength division multiplexer can be adopted. The optical isolator is composed of a Faraday rotator and a polarizer, and is used to prevent the reverse-transmitted light from interfering with the previous-stage devices. The signal transmission fiber adopts a fluorine-doped cladding fiber, and its length is controlled within the range of 0.5 - 2 meters. The core diameter matches the input port of the second-stage amplification unit with a tolerance of no more than ±5μm.

[0060] Further, please refer to Figure 5 On the lower circuit board 5, a control module is provided. The control module is electrically connected to the tunable optical filtering unit 3, the first-stage amplification unit, and the second-stage amplification unit, and is used to adjust the filtering characteristics of the tunable optical filtering unit 3 and the pump power of the two-stage amplification units.

[0061] Specifically, the control module can be implemented using an embedded microprocessor or FPGA, and dynamically adjusts the transmission wavelength range of the filtering unit through a preset algorithm or external instructions. Among them, the filtering characteristic adjustment is achieved by sending a control signal to the MEMS micromirror drive circuit, changing the reflection angle of the Bragg grating to select a specific wavelength to pass through. The pump power adjustment is achieved by changing the drive current of the pump source. As a preferred implementation, the control module can integrate a PID control algorithm to optimize the pump current parameters in real time according to the optical power signal fed back by the output monitoring unit 6.

[0062] Furthermore, it also includes an output monitoring unit 6 connected to the output end of the second-stage amplification unit. The output monitoring unit 6 is used to convert a part of the output optical signal into an electrical signal and transmit it to the control module. The control module monitors the output optical power in real time according to the electrical signal and adjusts the working states of the first-stage amplification unit and the second-stage amplification unit.

[0063] In a possible embodiment of the present invention, please refer to Figure 6 , the output monitoring unit 6 can be implemented by a combination of a beam splitter and a PIN photodiode. Among them, the beam splitter splits a small part (usually 1 - 5%) of the high-power optical signal transmitted from the output end of the second gain fiber for monitoring, while the main optical power continues to be transmitted; the split optical signal is directed to a high-sensitivity PIN photodiode, and the PIN photodiode converts the optical signal into an electrical signal and transmits it to the control circuit. This design can accurately monitor parameters such as the power, wavelength, and stability of the output optical signal in real time without significantly affecting the transmission power of the main optical path, provide real-time feedback for the system, and enable the control module to dynamically adjust the pump source power and the characteristics of the tunable filtering unit according to the monitoring results to ensure that the output optical signal always remains in the best state.

[0064] In another possible embodiment of the present invention, please refer to Figure 7 , the output monitoring unit 6 can be implemented using a TapPD (tapped photodiode) structure. Its working principle is to introduce a tapped optical coupler (TapCoupler) in the optical fiber transmission path to split a very small part (usually about 1%) of the optical power in the main optical path and direct it to an integrated high-sensitivity photodiode (Photodiode). The photodiode converts the extracted optical signal into an electrical signal proportional to the optical power and transmits it through the circuit to the control module for real-time analysis and processing. It can not only ensure the minimum loss of the main optical path (maintaining more than 99% of the output power), but also provide high-precision monitoring of the output optical power.

[0065] Furthermore, a high-power isolator is provided between the output end of the second-stage amplification unit and the output monitoring unit 6. The high-power isolator is connected to the output optical fiber 2 and is used to prevent reflected light from returning to the second-stage amplification unit.

[0066] The high-power isolator adopts an optical isolation structure based on a Faraday rotator and is composed of a magnetic ring, a polarization beam splitter, and a Faraday rotatory crystal, with an isolation degree greater than 40 dB. Specifically, the material of the Faraday rotatory crystal can be terbium-doped garnet (TGG) or yttrium iron garnet (YIG), and the crystal length is designed to be 5 - 10 mm according to the working wavelength (such as the 1550 nm band). The magnetic ring provides an axial magnetic field intensity of 3000 - 5000 gauss, causing the polarization direction of the forward-transmitted light to rotate by 45 degrees and then pass through the polarization beam splitter, while the backward-reflected light is blocked by the polarization beam splitter. As a preferred embodiment, the light passing aperture of the high-power isolator is designed to be Φ3 mm to adapt to high-power laser transmission, and FC / APC fiber connectors are used at both ends to reduce echo reflection.

[0067] Meanwhile, in this embodiment, all the devices involved can adopt polarization-maintaining devices, such as polarization-maintaining input optical fiber, polarization-maintaining beam combiner, polarization-maintaining beam splitter, polarization-maintaining high-power isolator, polarization-maintaining gain fiber, polarization-maintaining multimode gain fiber, polarization-maintaining output optical fiber, etc., to be adapted to satellite communication.

[0068] The following explains this embodiment with a specific implementation process:

[0069] First-stage amplification: The optical signal enters the first-stage gain fiber (erbium-doped fiber), and the single-mode pump source of the first-stage gain fiber pumps it to achieve population inversion, preliminarily amplifying the optical signal and preparing for subsequent high-power amplification.

[0070] Filtering by the tunable optical filtering unit 3: The control module generates a corresponding control signal according to the preset parameters and sends it to the tunable optical filtering unit 3. Based on the principles of MEMS technology and grating technology, the MEMS micromirror inside the tunable optical filtering unit 3 adjusts its angle under the action of the control signal, changes the diffraction path of the optical signal on the grating, filters the pre-amplified optical signal, selects the optical signal in the C band, and completes the precise adjustment of the filtering band.

[0071] Second-stage amplification: The preliminarily amplified optical signal is transmitted to the second-stage gain fiber (erbium-ytterbium co-doped double-clad fiber) through an optical coupler, and the second-stage gain fiber amplifies the optical signal with high power to meet the requirements of the optical signal power for long-distance transmission.

[0072] The high-power C-band optical signal after two-stage amplification and filtering is output to the long-distance transmission link through the output optical fiber 2. During the output of the optical signal, the photodetector at the front end of the output optical fiber 2 monitors the optical signal intensity in real time and converts it into an electrical signal to feedback to the control module. According to the feedback signal, on the one hand, the control module can adaptively adjust the control signal sent to the tunable optical filtering unit 3, optimize the filtering parameters of the tunable optical filtering unit 3, and ensure the band accuracy of the output optical signal; on the other hand, according to the difference between the actual output power and the preset power, the pump powers of the single-mode pump source of the first-stage gain optical fiber and the multi-mode pump source of the second-stage gain optical fiber are respectively adjusted to accurately control the power of the output optical signal, ensure the stable output of the fiber amplifier, and output a high-power optical signal that meets the requirements of long-distance transmission in satellite laser communication.

[0073] The above uses specific examples to elaborate on the present invention, which is only used to help understand the present invention and is not intended to limit the present invention. For those skilled in the art of the present invention, according to the idea of the present invention, several simple deductions, deformations or substitutions can also be made.

Claims

1. A fiber amplifier with adjustable filtering applicable to satellite laser communication, characterized in that, Comprising: A housing, on which an input optical fiber and an output optical fiber are provided. Inside the housing, there is a circuit board, a first-stage amplification unit, a second-stage amplification unit, and an adjustable optical filtering unit. The circuit board is electrically connected to the first-stage amplification unit, the second-stage amplification unit, and the adjustable optical filtering unit; The first-stage amplification unit pre-amplifies the input optical signal, and the adjustable optical filtering unit filters the pre-amplified optical signal; the second-stage amplification unit highly amplifies the optical signal processed by the adjustable optical filtering unit and outputs it through the output optical fiber; Wherein, the first-stage amplification unit includes a first gain optical fiber and a single-mode pump source coupled to the first gain optical fiber; the second-stage amplification unit includes a second gain optical fiber and a multi-mode pump source coupled to the second gain optical fiber.

2. The fiber amplifier with adjustable filtering according to claim 1, characterized in that, The adjustable optical filtering unit includes an adjustable optical filter.

3. The fiber optic amplifier with adjustable filtering according to claim 2, characterized in that The single-mode pump source and the multi-mode pump source are both fixed inside the housing. One end of each pump source is a power supply end electrically connected to the circuit board, and the other end is an optical fiber end coupled to the corresponding gain optical fiber.

4. The fiber optic amplifier with adjustable filtering according to claim 3, wherein The circuit board includes an upper circuit board and a lower circuit board connected to each other; The lower circuit board is provided with a plurality of fixing holes. The single-mode pump source and the multi-mode pump source respectively pass through the fixing holes and are fixed on the housing.

5. The fiber amplifier with adjustable filtering according to claim 4, characterized in that The adjustable optical filtering unit is fixed on the lower circuit board by a fixing bracket and is electrically connected to the lower circuit board; The single-mode pump source is coupled to the first gain optical fiber through a first beam combiner; The multi-mode pump source is coupled to the second gain optical fiber through a second beam combiner.

6. The fiber amplifier with adjustable filtering according to claim 5, characterized in that A wavelength division multiplexer is provided between the input optical fiber and the first-stage amplification unit; An optical isolator is provided between the output end of the first-stage amplification unit and the adjustable optical filtering unit; A signal transmission optical fiber is provided between the output end of the adjustable optical filtering unit and the second-stage amplification unit.

7. The fiber optic amplifier with adjustable filtering according to claim 5, characterized in that, A control module is provided on the lower circuit board. The control module is electrically connected to the adjustable optical filtering unit, the first-stage amplification unit, and the second-stage amplification unit, and is used to adjust the filtering characteristics of the adjustable optical filtering unit and the pump power of the two-stage amplification units.

8. The fiber optic amplifier with adjustable filtering according to claim 7, characterized in that, It further includes an output monitoring unit connected to the output end of the second-stage amplification unit. The output monitoring unit is used to convert a part of the output optical signal into an electrical signal and transmit it to the control module. The control module monitors the output optical power in real time according to the electrical signal and adjusts the working states of the first-stage amplification unit and the second-stage amplification unit.

9. The fiber amplifier with adjustable filtering according to claim 8, characterized in that, A high-power isolator is further provided between the output end of the second-stage amplification unit and the output monitoring unit. The high-power isolator is connected to the output optical fiber and is used to prevent the reflected light from returning to the second-stage amplification unit.

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