A fiber amplifier and optical communication device
By combining analog feedforward control modules and digital feedforward feedback modules, the problem of insufficient gain fluctuation suppression capability of EDFA in optical communication systems is solved, achieving fast response and high-precision gain control, and improving the stability and adaptability of the system.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- O NET COMM (SHENZHEN) LTD
- Filing Date
- 2025-06-06
- Publication Date
- 2026-06-02
AI Technical Summary
Existing EDFAs in optical communication systems suffer from delays caused by analog-to-digital and digital-to-analog conversion, which affect their ability to respond quickly to sudden increases or decreases in channel signal strength and limit their ability to suppress gain fluctuations.
The control method combines analog feedforward control module and digital feedforward and feedback module. The output power of pump laser is quickly adjusted by analog circuit and the error is compensated by digital feedback function, so as to achieve control with almost no delay.
It enhances the ability to suppress sudden increases and decreases in the channel, improves the system's fast response and long-term accuracy, and ensures the stability and adaptability of the gain.
Smart Images
Figure CN224319365U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of optical fiber communication technology, and in particular to an optical fiber amplifier and an optical communication device. Background Technology
[0002] EDFA (Erbium-Doped Fiber Amplifier) plays a very important role in optical communication systems, used to amplify optical signals to compensate for the attenuation of optical signals during transmission.
[0003] In optical communication systems, the intensity and wavelength of optical signals may change. To cope with these changes, EDFAs need to respond quickly to adjust their operating state to maintain system stability. Utilizing an FPGA (Field-Programmable Gate Array) to rapidly sample the signals from the input and output photodetectors, and then adjusting the pump power based on this signal using digital feedforward and digital feedback control algorithms, can suppress gain fluctuations caused by sudden increases or decreases in channel signal strength.
[0004] However, the process of converting the analog signal obtained from the photodetector into the digital signal controlling the pump requires analog-to-digital and digital-to-analog conversion. Multiple conversions will cause a certain delay, which will affect the system's ability to respond quickly to sudden increases or decreases in the channel, thus limiting the ability to suppress gain fluctuations. Utility Model Content
[0005] This invention provides an optical fiber amplifier and an optical communication device to solve the problem of weak gain fluctuation suppression capability in the prior art.
[0006] This utility model discloses an optical fiber amplifier, comprising:
[0007] A photodetector is used to acquire the input optical power and / or output optical power of the fiber amplifier;
[0008] Pump laser assembly for emitting pump laser;
[0009] An analog feedforward control module is connected to the photodetector and the pump laser assembly respectively, and is used to control the output power of the pump laser;
[0010] The analog feedforward control module includes a transimpedance amplifier, a multiplier, and an adder connected in sequence. The transimpedance amplifier is connected to the photodetector, and the adder is connected to the pump laser assembly.
[0011] Optionally, the fiber amplifier further includes:
[0012] The controller is connected to the photodetector;
[0013] A digital feedforward and feedback module, connected to the controller and the pump laser assembly, is used to control the output power of the pump laser.
[0014] Optionally, the fiber amplifier further includes:
[0015] A digital control component, connected to the controller, is used to control the fiber optic amplifier to operate in a stable state.
[0016] Optionally, the digital control component includes a thermoelectric cooler, a variable optical attenuator, and a heater, which are respectively connected to the controller.
[0017] Optionally, the digital control component further includes: a digital-to-analog converter, with its input connected to the controller and its output connected to the thermoelectric cooler, the variable light attenuator, and the heater, respectively.
[0018] Optionally, the fiber amplifier further includes:
[0019] The optical switch driver circuit is connected to the controller.
[0020] Optionally, the controller further includes multiple input terminals and multiple input ports;
[0021] The fiber amplifier also includes:
[0022] The input / output ports are connected to the plurality of output terminals via latches and to the plurality of input terminals via buffers.
[0023] Optionally, the fiber amplifier further includes:
[0024] A resetter is connected to both the buffer and the controller.
[0025] Optionally, the pump laser assembly includes:
[0026] A pump laser and a pump drive circuit connected to the pump laser.
[0027] This utility model also discloses an optical communication device, including the fiber optic amplifier described above.
[0028] Compared with the prior art, the beneficial effects of the fiber optic amplifier provided by this utility model embodiment are as follows:
[0029] The output power of the pump laser is adjusted based on the input optical power using an analog feedforward control module. The analog feedforward control module is an analog circuit with a faster response speed, which can process and feed back the input signal in a shorter time. It can achieve almost zero-delay control, thereby adjusting the output power of the pump laser more quickly to improve the suppression of channel bursts and fluctuations. Attached Figure Description
[0030] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments. In the accompanying drawings:
[0031] Figure 1 This is a schematic diagram of the structure of an embodiment of the fiber optic amplifier provided by this utility model;
[0032] Figure 2 This is a schematic diagram of an embodiment of the analog feedforward control module provided by this utility model.
[0033] The labels for the attached figures are as follows:
[0034] 10. Fiber Optic Amplifier; 11. Photodetector; 12. Pump Laser Assembly; 121. Pump Laser; 122. Pump Driver Circuit; 13. Analog Feedforward Control Module; 131. Transimpedance Amplifier; 132. Multiplier; 133. Adder; 14. Controller; 141. Output Terminal; 142. Input Terminal; 15. Digital Feedforward and Feedback Module; 16. Digital Control Components; 161. Digital-to-Analog Converter; 162. Thermoelectric Cooler; 163. Variable Optical Attenuator; 164. Heater; 17. Optical Switch Driver Circuit; 18. Input / Output Port; 19. Resetter; 20. Power Tree. Detailed Implementation
[0035] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The preferred embodiments of this utility model will now be described in detail with reference to the accompanying drawings.
[0036] Please refer to the following: Figure 1 and Figure 2 , Figure 1 This is a schematic diagram of one embodiment of the fiber optic amplifier provided by this utility model. Figure 2 This is a schematic diagram of an embodiment of the analog feedforward control module provided by this utility model.
[0037] In one embodiment, the fiber amplifier 10 includes a photodetector 11, a pump laser assembly 12, and an analog feedforward control module 13. The photodetector 11 is used to acquire the input optical power and / or output optical power of the fiber amplifier 10. The pump laser assembly 12 includes a pump laser 121 and a pump drive circuit 122 connected to the pump laser 121. In an EDFA, erbium-doped fiber is used to amplify the optical signal, while the pump laser 121 provides energy to excite erbium ions in the erbium-doped fiber, thereby amplifying the signal. The output power of the pump laser 121 is closely related to the amplification effect of the EDFA. The higher the power provided by the pump laser 121, the more energy it can provide to excite erbium ions in the erbium-doped fiber, thus achieving a higher amplification effect. The analog feedforward control module 13 is connected to both the photodetector 11 and the pump laser assembly 12, and can control the output power of the pump laser 121 based on the detection results of the photodetector 11. Specifically, the analog feedforward control module 13 includes a transimpedance amplifier 131, a multiplier 132, and an adder 133 connected in sequence. The transimpedance amplifier 131 is connected to the photodetector 11, and the adder 133 is connected to the pump drive circuit 122.
[0038] The photodetector 11 can detect the input optical power of the fiber amplifier 10 and output a current signal based on the detected input optical power. In other implementations, the photodetector 11 can also detect the output optical power of the fiber amplifier 10. The transimpedance amplifier 131 receives the output current signal from the photodetector 11 and converts the current signal into a voltage signal. The multiplier 132 has a preset scaling factor K, and the adder 133 has a preset bias amount B. K represents the amount of pump power adjustment required per unit change in input optical power, reflecting the gain efficiency of the EDFA. B represents the pump power required when the input optical power is zero, used to maintain the fundamental population inversion of the erbium-doped fiber.
[0039] The values of K and B need to be obtained through pre-calibration. A fixed target gain G (e.g., 20dB) is set based on preset gain conditions. The input optical power is set to a series of known values (e.g., 0.01mW, 0.1mW, 1mW). For each input optical power, the output power of the pump laser 121 is manually adjusted so that the output power = G * input power. Multiple sets of input and output optical powers are recorded, and linear fitting is performed to obtain the linear equation:
[0040] P pump =K×P in +B
[0041] Among them, P pump P is the output power of the pump laser 121. in Given the input optical power, the specific values of K and B can be obtained using this formula.
[0042] The voltage signal is multiplied by K after passing through multiplier 132, and then added by B after passing through adder 133 to obtain the driving signal. The driving signal is input into pump drive circuit 122. Pump drive circuit 122 drives pump laser 121 to output pump laser based on the driving signal, so that the power of the pump laser can meet the preset gain requirements.
[0043] In this embodiment, an analog circuit (analog feedforward control module 13) is used to adjust the output power of the pump laser based on the input optical power. The analog circuit has a faster response speed and can process and feedback the input signal in a shorter time, which can achieve almost zero-delay control. This allows for faster adjustment of the output power of the pump laser 121 to improve the suppression of channel bursts and fluctuations.
[0044] Please continue reading. Figure 1 In one embodiment, the fiber amplifier 10 further includes a controller 14 and a digital feedforward and feedback module 15 connected to the controller 14. The controller 14 is connected to a photodetector 11, and the digital feedforward and feedback module 15 is connected to a pump laser assembly 12. The photodetector 11 acquires the input optical power and / or output optical power of the fiber amplifier 10 and generates a corresponding current signal. The controller 14 acquires the current signal and generates a corresponding control signal based on the current signal. The digital feedforward and feedback module 15 outputs a corresponding drive signal based on the control signal. The pump drive circuit 122 adjusts the output power of the pump laser 121 based on the drive adjustment signal.
[0045] Specifically, after the controller 14 acquires the current signal corresponding to the input optical signal, it converts the current signal into a digital signal and transmits the digital signal to the digital feedforward and feedback module 15. The FPGA in the digital feedforward and feedback module 15 performs calculations using logic gates based on the digital signal and the pre-stored K and B values to obtain the corresponding digital drive signal. After converting the digital drive signal into an analog drive signal, it sends it to the pump drive circuit 122, so that the pump drive circuit 122 can drive the pump laser 121 to emit pump laser according to the analog drive signal.
[0046] Digital feedforward typically offers higher accuracy than analog feedforward. Digital feedforward uses an ADC to convert analog signals into digital values, and all calculations are performed in the digital domain, unaffected by analog noise (thermal noise, power supply ripple, electromagnetic interference). Therefore, in this embodiment, a digital feedforward and feedback module 15 is added. While the analog feedforward control module 13 rapidly responds to signal changes and makes adjustments, digital feedforward can also achieve higher precision adjustments.
[0047] Since the calibration parameters K and B cannot fully match complex operating conditions such as nonlinearity and temperature changes, this embodiment provides a digital feedback function to compensate for the error. After the controller 14 obtains the current signal corresponding to the output optical signal, it obtains the corresponding digital signal based on the current signal, calculates the actual gain of the output optical signal based on the digital signal, obtains the gain error based on the pre-stored target gain and the actual gain, obtains the corresponding adjustment signal based on the gain error, and sends the adjustment signal to the digital feedforward and feedback module 15. The digital feedforward and feedback module 15 can generate a corresponding analog adjustment signal based on the adjustment signal, and then send the analog adjustment signal to the pump drive circuit 122. Thus, the pump drive circuit 122 can drive the pump laser 121 to emit pump laser according to the analog adjustment signal.
[0048] Pure feedforward control (open loop) is affected by model errors, device aging, temperature drift, etc., and long-term operation will cause the gain to deviate from the target value. Therefore, this embodiment sets up a digital feedforward and feedback module 15 to provide digital feedback function, which can eliminate low-frequency disturbances (such as slow drift) and suppress high-frequency noise (such as sudden power changes), thereby improving the long-term accuracy and adaptability of the fiber amplifier 10.
[0049] In this embodiment, an analog feedforward control module 13 and a digital feedforward and feedback module 15 are combined. The analog feedforward control module 13 controls the output power of the pump laser 121 through pure hardware circuits (such as analog multipliers 132 and adders 133). It has an extremely short response time and can quickly adjust the output power to prevent gain overshoot and maintain system gain stability when the input optical power changes abruptly. The digital feedforward can store multiple (K, B) combinations and is unaffected by external factors, resulting in higher output accuracy. The digital feedback function compensates for the residual error of the feedforward model by real-time monitoring of the output optical power, making the steady-state gain error approach zero.
[0050] In one embodiment, controller 14 is a ZYNQ chip. The ZYNQ chip combines a Xilinx FPGA and an ARM processor, featuring a high degree of integration. The FPGA portion provides flexible programmable logic, enabling customized digital signal processing and control functions, while the ARM processor portion provides general-purpose processing capabilities, suitable for running control algorithms and handling complex control logic. Furthermore, the ZYNQ chip boasts high operating speed and real-time performance, enabling rapid response to input signals and real-time adjustment of output control signals, making it suitable for applications requiring fast response and precise control.
[0051] Please continue reading. Figure 1 The fiber optic amplifier 10 also includes a digital control component 16, which is connected to the controller 14 and is used to control the fiber optic amplifier 10 to be in a stable working state.
[0052] The digital control component 16 includes: a digital-to-analog converter 161 (DAC) connected to the controller 14; a thermoelectric cooler 162, a variable optical attenuator 163, and a heater 164, each connected to the digital-to-analog converter 161.
[0053] The digital-to-analog converter 161 is used to convert digital signals into analog signals. The digital signals received from the controller 14 can be converted into corresponding analog control signals by the DAC. This conversion enables the controller 14 to send control commands in digital form, which are then converted into analog signals by the DAC to control other components, such as the thermoelectric cooler 162, the variable optical attenuator 163, and the heater 164.
[0054] Heater 164 provides heat and can adjust the temperature of fiber amplifier 10 according to a control signal to keep the device within a suitable operating temperature range. For example, it can supplement heating in low-temperature environments to ensure the cooling efficiency of the TEC (the cooling capacity of the TEC decreases at low temperatures) or to maintain the temperature stability of the erbium fiber (some designs require isothermal optimization of gain efficiency).
[0055] The variable optical attenuator 163 is used to adjust the intensity of the optical signal. The optical power level output by the fiber amplifier 10 can be adjusted by a control signal. The attenuation is controlled by the voltage provided by the DAC to balance the output optical power of the EDFA and prevent saturation or gain competition.
[0056] Thermoelectric cooler 162 is a device for temperature control, which can adjust the temperature of fiber amplifier 10 according to a control signal. Based on the Peltier effect, cooling or heating is determined by the voltage polarity provided by the DAC, maintaining a constant temperature for pump laser 121 or erbium fiber, with a temperature control accuracy of ±0.01℃. This can prevent wavelength drift of pump laser 121 (e.g., a 980nm pump wavelength drift of approximately 0.3nm / ℃) and reduce the temperature dependence of the erbium fiber gain spectrum (especially in the C / L band).
[0057] In summary, the thermoelectric cooler 162 is used to suppress pump wavelength drift, ensure gain consistency, and stabilize pump efficiency. The variable optical attenuator 163 can quickly equalize the power of multiple channels and avoid saturation. The heater 164 is used to cope with extreme environmental conditions and compensate for the performance limitations of the thermoelectric cooler 162 in extreme environments.
[0058] Please continue reading. Figure 1The fiber amplifier 10 also includes an optical switch driver circuit 17, which controls the switching state of the optical switch, i.e., controls the light transmission path, enabling the switching and routing of optical signals between different channels or fibers. Specifically, it converts the low-voltage digital signal (e.g., 3.3L VCMOS) from the controller 14 (e.g., the GPIO or DAC output of a ZYNQ) into the high-voltage / high-current drive signal required by the optical switch. This can be used to switch to a backup pump when the main pump laser 121 fails. Alternatively, it can be used to dynamically select the gain fiber path in a two-stage EDFA. It can also be used to switch the EDFA output optical path to an OSA spectrometer.
[0059] Please continue reading. Figure 1 The controller 14 also includes multiple output terminals 141 and multiple input terminals 142. Input / output ports 18 are connected to the multiple output terminals via latches and to the multiple input terminals 142 via buffers. The output terminals are used to send status signals (such as optical power, temperature, and alarms) to external devices (such as monitoring systems or host computers), including pump status (ON / OFF), gain mode (fixed / adaptive), and PD detection voltage (which requires DAC conversion before output). The input terminals 142 are used to receive external control commands or configuration parameters (such as target gain and pump power limits), including enable signals, reset commands, and external reference voltages (for calibration).
[0060] Input / output port 18 uses standardized connectors (such as DB9, RJ45, and fiber optic LC interfaces) to ensure compatibility and enable successful communication between the external system and controller 14. Latches (outputs) and buffers (inputs) isolate controller 14 from the external environment, improving anti-interference capabilities. Specifically, the latches maintain output signal stability during controller 14 update intervals, preventing jitter. The buffers enhance the driving capability of the input signals, avoiding attenuation over long transmission lines. Resetter 19 connects the buffer output to the controller 14 reset pin, triggering a hardware reset of controller 14 when the input signal is abnormal (e.g., a sustained low level). Through this structure, the latches and buffers ensure signal integrity and timing consistency, while the reset provides hardware-level protection, reducing the risk of system downtime.
[0061] Input / output port 18 is also connected to power tree 20 to realize power management, status monitoring and fault protection. Power tree is the distributed power management network of EDFA, which is responsible for converting input power (such as 48V DC) into multiple regulated power supplies for use by various modules (such as pump laser 121, thermoelectric cooler 162, controller 14, etc.).
[0062] This utility model also provides an optical communication device, which includes the optical fiber amplifier as described above.
[0063] It should be understood that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Those skilled in the art can modify the technical solutions described in the above embodiments, or make equivalent substitutions for some of the technical features; and all such modifications and substitutions should fall within the protection scope of the appended claims of this utility model.
Claims
1. An optical fiber amplifier, characterized by, include: A photodetector is used to acquire the input optical power and / or output optical power of the fiber amplifier; Pump laser assembly for emitting pump laser; An analog feedforward control module is connected to the photodetector and the pump laser assembly respectively, and is used to control the output power of the pump laser; The analog feedforward control module includes a transimpedance amplifier, a multiplier, and an adder connected in sequence. The transimpedance amplifier is connected to the photodetector, and the adder is connected to the pump laser assembly.
2. The fiber amplifier of claim 1, wherein, The fiber amplifier also includes: The controller is connected to the photodetector; A digital feedforward and feedback module, connected to the controller and the pump laser assembly, is used to control the output power of the pump laser.
3. The fiber amplifier of claim 2, wherein, The fiber amplifier also includes: A digital control component, connected to the controller, is used to control the fiber optic amplifier to operate in a stable state.
4. The fiber amplifier of claim 3, wherein, The digital control components include a thermoelectric cooler, a variable light attenuator, and a heater, which are respectively connected to the controller.
5. The fiber amplifier of claim 4, wherein, The digital control component also includes: The digital-to-analog converter has its input connected to the controller and its output connected to the thermoelectric cooler, the variable light attenuator, and the heater, respectively.
6. The fiber amplifier of any of claims 2-5, wherein, The fiber amplifier also includes: The optical switch driver circuit is connected to the controller.
7. The fiber optic amplifier according to any one of claims 2-5, characterized in that, The controller also includes multiple input terminals and multiple input ports; The fiber amplifier also includes: The input / output ports are connected to the plurality of output terminals via latches and to the plurality of input terminals via buffers.
8. The fiber optic amplifier according to claim 7, characterized in that, The fiber amplifier also includes: A resetter is connected to both the buffer and the controller.
9. The fiber optic amplifier according to claim 1, characterized in that, The pump laser assembly includes: A pump laser and a pump drive circuit connected to the pump laser.
10. An optical communication device, comprising: Includes the fiber optic amplifier as described in any one of claims 1-9.