EDFA control circuit with high precision and wide gain adjustment range

Abstract

The utility model discloses an EDFA (erbium doped fiber amplifier) control circuit with high precision and wide gain adjusting range, which relates to the field of EDFA control circuits and comprises an MCU (microprogrammed control unit). The input optical power detection module is used for generating an input optical power signal according to the input optical power of the EDFA; the output optical power detection module is used for generating an output optical power signal according to the output optical power of the EDFA; the MCU is connected with the first input end of the gain control module, and the input optical power detection module is connected with the second input end of the gain control module; a PID control module; a pumping control module; the MCU controls the gain control module to output a target gain signal to the PID control module according to the target gain; and based on the target gain signal and the output optical power signal, the PID control module controls the gain of the EDFA through the pumping control module, so that the gain of the EDFA is equal to the target gain. The EDFA control circuit has high gain control precision and a wide gain adjusting range.

Description

Technical Field

[0001] The utility model relates to the field of EDFA control circuits, in particular to an EDFA control circuit with high precision and wide gain adjustment range. Background Art

[0002] Erbium-doped Optical Fiber Amplifiers (EDFAs) are key components in optical transmission and are widely used in optical backbone communication networks, metropolitan area networks (MANs), and data center interconnects. In backbone communication networks, the EDFA's gain and optical power output often require precise adjustment based on transmission distance and signal loss to ensure stable signal transmission. In existing technologies, EDFA gain is typically adjusted by adjusting the resistance of a digital potentiometer in the gain control circuit using an MCU.

[0003] Figure 1 The schematic diagram of the existing gain control circuit is shown. In the circuit, U1B is a digital potentiometer with 1024 taps and 10K ohm end-to-end resistance. R2 is a resistor with a resistance of 300 ohms. By adjusting the resistance of the digital potentiometer, Figure 1 The maximum gain adjustment range of the EDFA controlled by the gain control circuit shown is only about 15dB. While maintaining a resolution of 0.1dB, the gain adjustment range is only 13.93dB. Given the rapid development of high-speed, high-capacity, and long-distance optical fiber communication systems, current gain control circuits are no longer able to meet the requirements of EDFA gain control. Both their gain control accuracy and gain adjustment range need to be further improved. Utility Model Content

[0004] In response to the above problems and technical requirements, the applicant has proposed an EDFA control circuit with high precision and wide gain adjustment range.

[0005] The technical solution of the utility model is as follows:

[0006] The utility model proposes a high-precision EDFA control circuit with a wide gain adjustment range, which is characterized by comprising:

[0007] MCU;

[0008] An input optical power detection module is used to generate an input optical power signal according to the input optical power of the EDFA;

[0009] An output optical power detection module is used to generate an output optical power signal according to the output optical power of the EDFA;

[0010] A gain control module, wherein the MCU is connected to a first input terminal of the gain control module, and the input optical power detection module is connected to a second input terminal of the gain control module;

[0011] A PID control module, wherein the output end of the gain control module is connected to the control setting end of the PID control module, and the output optical power detection module is connected to the control feedback end of the PID control module;

[0012] A pump control module, wherein the output end of the PID control module is connected to the input end of the pump control module;

[0013] The MCU is used to control the gain control module to output a target gain signal to the PID control module according to the target gain; based on the target gain signal and the output optical power signal, the PID control module controls the gain of the EDFA through the pump control module to make the gain of the EDFA equal to the target gain.

[0014] A further technical solution is that the input optical power detection module includes an operational amplifier U1, a capacitor CIN1, a capacitor CIN2, a capacitor CF1 and a resistor RF1, wherein:

[0015] The inverting input terminal of the operational amplifier U1 is connected to the input photodetector in the EDFA;

[0016] The inverting input terminal of the operational amplifier U1 is grounded through capacitors CIN1 and CIN2 . The output terminal of the operational amplifier U1 is connected to the inverting input terminal of the operational amplifier U1 through resistor RF1 . The capacitor CF1 is connected in parallel with the resistor RF1 .

[0017] A further technical solution is that the gain control module includes a resistor R1, a resistor R2, a digital potentiometer U2A, an operational amplifier U2B and a capacitor C1, wherein:

[0018] One end of the resistor R1 is connected to the output end of the operational amplifier U1 as the second input end of the gain control module, and the other end of the resistor R1 is connected to the non-inverting input end of the operational amplifier U2B and the first resistor end of the digital potentiometer U2A;

[0019] The second resistance end of the digital potentiometer U2A is connected to the inverting input end of the operational amplifier U2B, and the sliding end of the digital potentiometer U2A is connected to the MCU as the first input end of the gain control module; the output end of the operational amplifier U2B is connected to the inverting input end of the operational amplifier U2B through the capacitor C1, and the resistor R2 is connected in parallel with the capacitor C1.

[0020] A further technical solution is that the output optical power detection module includes an operational amplifier U3, a capacitor COUT1, a capacitor COUT2, a capacitor CF2 and a resistor RF2, wherein:

[0021] The inverting input terminal of the operational amplifier U3 is connected to the output photodetector in the EDFA;

[0022] The inverting input terminal of the operational amplifier U3 is grounded through capacitors COUT1 and COUT2 . The output terminal of the operational amplifier U3 is connected to the inverting input terminal of the operational amplifier U3 through resistor RF2 . The capacitor CF2 is connected in parallel with the resistor RF2 .

[0023] A further technical solution is that the PID control module includes a resistor R3, a resistor R4, a resistor R5, a capacitor C2 and an operational amplifier U4, wherein:

[0024] One end of the resistor R3 is connected to the output end of the operational amplifier U2B as the control given end of the PID control module, and the other end of the resistor R3 is connected to the non-inverting input end of the operational amplifier U4. One end of the resistor R4 is connected to the output end of the operational amplifier U3 as the control feedback end, and the other end of the resistor R4 is connected to one end of the resistor R5 and the inverting input end of the operational amplifier U4. The other end of the resistor R5 is connected to the output end of the operational amplifier U4 through the capacitor C2, and the output end of the operational amplifier U4 is connected to the input end of the pump control module.

[0025] A further technical solution is that the resistance value of the resistor R1 is 10KΩ, and the resistance value of the resistor R2 is 80KΩ.

[0026] A further technical solution is that the model of the digital potentiometer U2A is MAX5484.

[0027] The beneficial technical effects of the utility model are:

[0028] The EDFA control circuit provided by the utility model has the characteristics of high gain control accuracy and a wide gain adjustment range, and can ensure the power stability of the optical signal during transmission, thereby extending the communication transmission distance, improving the sensitivity of the optical receiver and the transmission quality of the access network, and can meet the gain control requirements of EDFA in high-speed, large-capacity, and long-distance optical fiber communication systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the existing gain control circuit provided by the utility model.

[0030] Figure 2 It is a structural diagram of the EDFA provided by the utility model.

[0031] Figure 3 This is a structural block diagram of an embodiment of the EDFA control circuit provided by the utility model.

[0032] Figure 4 This is a circuit diagram of an embodiment of an input optical power detection module provided by the present utility model.

[0033] Figure 5 This is a circuit diagram of an embodiment of a gain control module provided by the present utility model.

[0034] Figure 6 This is a circuit diagram of an embodiment of an output optical power detection module provided by the utility model.

[0035] Figure 7 This is a circuit diagram of an embodiment of a PID control module provided by the present utility model.

[0036] Figure 8 This is a curve showing the relationship between the number of taps and the EDFA gain under the control of the existing gain control circuit provided by the utility model.

[0037] Figure 9 This is a curve showing the relationship between the number of taps and the EDFA gain under the control of the EDFA control circuit provided by the utility model. DETAILED DESCRIPTION

[0038] The specific implementation of the present utility model will be further described below with reference to the accompanying drawings.

[0039] The utility model provides a high-precision EDFA control circuit with a wide gain adjustment range. Figure 3 As shown, the EDFA control circuit includes:

[0040] MCU;

[0041] An input optical power detection module is used to generate an input optical power signal according to the input optical power of the EDFA;

[0042] An output optical power detection module is used to generate an output optical power signal according to the output optical power of the EDFA;

[0043] A gain control module, wherein the MCU is connected to a first input terminal of the gain control module, and the input optical power detection module is connected to a second input terminal of the gain control module;

[0044] A PID control module, wherein the output end of the gain control module is connected to the control setting end of the PID control module, and the output optical power detection module is connected to the control feedback end of the PID control module;

[0045] A pump control module, wherein the output end of the PID control module is connected to the input end of the pump control module;

[0046] The MCU is used to control the gain control module to output a target gain signal to the PID control module according to the target gain; based on the target gain signal and the output optical power signal, the PID control module controls the gain of the EDFA through the pump control module to make the gain of the EDFA equal to the target gain.

[0047] Specifically, the Figure 2 A typical structural diagram of an EDFA (erbium-doped fiber amplifier) ​​is shown in FIG. Figure 2 As shown, the EDFA includes an input optical splitter, an input photodetector (represented by PIN1), an input isolator, a wavelength division multiplexer (WDM), a pump laser, an erbium-doped fiber (EDF), an output isolator, an output optical splitter, and an output photodetector (represented by PIN2), wherein,

[0048] The input end of the input optical splitter receives an input optical signal, the main optical splitter end of the input optical splitter is connected to the input end of the input isolator, and the slave optical splitter end of the input optical splitter is connected to the input photodetector. The output end of the input isolator is connected to the first input end of the wavelength division multiplexer, the pump laser is connected to the second input end of the wavelength division multiplexer, the output end of the wavelength division multiplexer is connected to the input end of the output isolator via an erbium-doped fiber, the output isolator is connected to the input end of the output optical splitter, the slave optical splitter end of the output optical splitter is connected to the output photodetector, and the main optical splitter end of the output optical splitter outputs the output optical signal.

[0049] The splitting ratio between the main splitting end and the slave splitting end of the input optical splitter is 98:2, and the splitting ratio between the main splitting end and the slave splitting end of the output optical splitter is 99:1.

[0050] The pump laser injects pump light into the erbium-doped fiber through a wavelength division multiplexer, amplifying the optical signal. The input photodetector detects the optical power of the output optical signal, i.e., the input optical power Pin. The output photodetector detects the optical power of the output optical signal, i.e., the output optical power Pout. The EDFA gain Gain = Pout / Pin.

[0051] The PID control module controls the EDFA's gain through the pump control module. Specifically, the control voltage Vpid output by the PID control module is applied to the pump control module. The pump control module then controls the power of the pump laser to control the EDFA's output optical power, thereby stabilizing the EDFA's gain at the target gain. The pump control module can be designed in accordance with existing technology to meet the requirements for controlling the pump laser's operating power. The detailed structure and operating principles of the input optical power detection module, output optical power detection module, gain control module, and PID control module are described below.

[0052] Furthermore, if Figure 4As shown, the input optical power detection module includes an operational amplifier U1, a capacitor CIN1, a capacitor CIN2, a capacitor CF1 and a resistor RF1, wherein:

[0053] The inverting input terminal of the operational amplifier U1 is connected to the input photodetector in the EDFA;

[0054] The inverting input terminal of the operational amplifier U1 is grounded through capacitors CIN1 and CIN2 . The output terminal of the operational amplifier U1 is connected to the inverting input terminal of the operational amplifier U1 through resistor RF1 . The capacitor CF1 is connected in parallel with the resistor RF1 .

[0055] Specifically, the input optical power detection module constitutes a transimpedance amplifier, which is used to convert the input optical power Pin detected by the input photodetector into a voltage, namely, the input optical power signal Vin (mV). The input optical power signal Vin can be expressed as: Vin = Pin × a1 × b1 × RF1, where RF1 represents the resistance value of resistor RF1 (Ω), a1 represents the splitting coefficient of the input photodetector, and b1 represents the responsivity of the input photodetector (mA / mW). Both a1 and b1 are constant parameters that can be determined based on the splitting ratio of the input splitter and the fixed parameters of the input photodetector.

[0056] Furthermore, the gain control module includes a resistor R1, a resistor R2, a digital potentiometer U2A, an operational amplifier U2B and a capacitor C1, wherein:

[0057] One end of the resistor R1 is connected to the output end of the operational amplifier U1 as the second input end of the gain control module, and the other end of the resistor R1 is connected to the non-inverting input end of the operational amplifier U2B and the first resistor end of the digital potentiometer U2A;

[0058] The second resistance end of the digital potentiometer U2A is connected to the inverting input end of the operational amplifier U2B, and the sliding end of the digital potentiometer U2A is connected to the MCU as the first input end of the gain control module; the output end of the operational amplifier U2B is connected to the inverting input end of the operational amplifier U2B through the capacitor C1, and the resistor R2 is connected in parallel with the capacitor C1.

[0059] Specifically, in this embodiment, the resistance of resistor R1 is 10K ohms, and the resistance of resistor R2 is 80K ohms. Optionally, the digital potentiometer U2A may be a MAX5484, which provides 1024 tap positions and an end-to-end resistance of 10K ohms, enabling fine resistance adjustment via the MCU. The target gain signal Vin1 = K1 × Vin, where K1 is the gain factor.

[0060] The MCU is used to control the gain control module to output a target gain signal to the PID control module according to the target gain. Specifically, the MCU adjusts the gain coefficient by adjusting the resistance value from the sliding end to the first end / second end of the digital potentiometer, thereby controlling the size of the target gain signal.

[0061] Furthermore, the output optical power detection module includes an operational amplifier U3, a capacitor COUT1, a capacitor COUT2, a capacitor CF2 and a resistor RF2, wherein:

[0062] The inverting input terminal of the operational amplifier U3 is connected to the output photodetector in the EDFA;

[0063] The inverting input terminal of the operational amplifier U3 is grounded through capacitors COUT1 and COUT2 . The output terminal of the operational amplifier U3 is connected to the inverting input terminal of the operational amplifier U3 through resistor RF2 . The capacitor CF2 is connected in parallel with the resistor RF2 .

[0064] Specifically, similar to the input optical power detection module, the output optical power detection module also constitutes a transimpedance amplifier for converting the output optical power Pout detected by the output photodetector into a voltage, namely, an output optical power signal Vout (mV). The output optical power signal Vout can be expressed as: Vout = Pout × a2 × b2 × RF2, where RF2 represents the resistance value of resistor RF2 (Ω), a2 represents the splitting coefficient of the output photodetector, and b2 represents the responsivity of the output photodetector (mA / mW). Both a2 and b2 are constant parameters that can be determined based on the splitting ratio of the output splitter and the fixed parameters of the output photodetector.

[0065] Furthermore, the PID control module includes a resistor R3, a resistor R4, a resistor R5, a capacitor C2 and an operational amplifier U4, wherein:

[0066] One end of the resistor R3 is connected to the output end of the operational amplifier U2B as the control given end of the PID control module, and the other end of the resistor R3 is connected to the non-inverting input end of the operational amplifier U4. One end of the resistor R4 is connected to the output end of the operational amplifier U3 as the control feedback end, and the other end of the resistor R4 is connected to one end of the resistor R5 and the inverting input end of the operational amplifier U4. The other end of the resistor R5 is connected to the output end of the operational amplifier U4 through the capacitor C2, and the output end of the operational amplifier U4 is connected to the input end of the pump control module.

[0067] The PID control module forms a negative feedback circuit, which can control the pump control module by controlling the voltage Vpid, so that the gain of the EDFA is stabilized at the target gain, that is, Vout=Vin1=K1×Vin, that is, Pout×a2×b2×RF2=K1×Pin×a1×b1×RF1.

[0068] After simplification, we can obtain: Pout / Pin=(K1×a1×b1×RF1) / (a2×b2×RF2)=Gain. From the above description, we can know that a1, a2, b1, and b2 are all constant parameters. K1 is determined by the MCU by adjusting the digital potentiometer according to the target gain. That is, after the target gain is determined, Gain is a constant, so that the gain of the EDFA can be stabilized at the target gain.

[0069] The utility model also tests the maximum gain adjustment range that can be achieved by the EDFA control circuit to control the EDFA, as well as the gain adjustment range under the condition of maintaining a resolution of 0.1 in conventional applications. Table 1 shows some experimental parameters corresponding to the adjustment of the number of taps of the digital potentiometer, the experimental parameters include the resistance value of DCP terminal 10, the resistance value of DCP terminal 12, the gain coefficient K1, the gain and the gain resolution, where "DCP terminal 10 resistance" refers to the gain of the digital potentiometer from the sliding end to the Figure 5 The resistance value of terminal 10 in the middle; "DCP terminal 12 resistance value" means the resistance value of the digital potentiometer sliding end to Figure 5 The resistance value of terminal 12.

[0070] Table 1 Some test parameters corresponding to the tap number adjustment of the digital potentiometer in the EDFA control circuit

[0071]

[0072] As can be seen from Table 1, when the digital potentiometer is applied with 1 tap, the gain of the EDFA is -20.56; when the digital potentiometer is applied with 1023 taps, the gain of the EDFA is 36.12, that is, under the control of the EDFA control circuit provided in this application, the maximum gain adjustment range that the EDFA can achieve is about 56dB. When the digital potentiometer is applied with 42 taps, the gain of the EDFA is -4.34; when the digital potentiometer is applied with 982 taps, the gain of the EDFA is 19.82. In practical applications, the resolution usually needs to be maintained at 0.1dB. When the resolution is maintained at about 0.1dB, the number of taps of the digital potentiometer is within the usage range of 42-982, and the adjustment range of the EDFA gain can reach 19.84-(-4.34)=24.19dB, indicating that the EDFA control circuit provided in this application has a wider gain adjustment range than the traditional control circuit.

[0073] like Figure 8 and Figure 9As shown, the present invention also compares the relationship curve between the number of taps and EDFA gain under the control of the existing gain control circuit when using a digital positioner with the same model parameters. According to the comparison, it can be seen that compared with the traditional gain control circuit, the gain adjustment accuracy and gain adjustment range of the EDFA control circuit provided by the present application can be greatly improved.

[0074] The above description is only a preferred embodiment of the present invention, and the present invention is not limited to the above embodiment. It is understood that other improvements and variations directly derived or imagined by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included in the scope of protection of the present invention.

Claims

1. A high-precision EDFA control circuit with a wide gain adjustment range, characterized in that: include: MCU; An input optical power detection module is used to generate an input optical power signal according to the input optical power of the EDFA; An output optical power detection module is used to generate an output optical power signal according to the output optical power of the EDFA; A gain control module, wherein the MCU is connected to a first input terminal of the gain control module, and the input optical power detection module is connected to a second input terminal of the gain control module; A PID control module, wherein the output end of the gain control module is connected to the control setting end of the PID control module, and the output optical power detection module is connected to the control feedback end of the PID control module; A pump control module, wherein the output end of the PID control module is connected to the input end of the pump control module; The MCU is used to control the gain control module to output a target gain signal to the PID control module according to the target gain; based on the target gain signal and the output optical power signal, the PID control module controls the gain of the EDFA through the pump control module to make the gain of the EDFA equal to the target gain.

2. The high-precision EDFA control circuit with a wide gain adjustment range according to claim 1, characterized in that: The input optical power detection module includes an operational amplifier U1, a capacitor CIN1, a capacitor CIN2, a capacitor CF1 and a resistor RF1, wherein: The inverting input terminal of the operational amplifier U1 is connected to the input photodetector in the EDFA; The inverting input terminal of the operational amplifier U1 is grounded through capacitors CIN1 and CIN2 . The output terminal of the operational amplifier U1 is connected to the inverting input terminal of the operational amplifier U1 through resistor RF1 . The capacitor CF1 is connected in parallel with the resistor RF1 .

3. The high-precision EDFA control circuit with a wide gain adjustment range according to claim 2, characterized in that: The gain control module includes a resistor R1, a resistor R2, a digital potentiometer U2A, an operational amplifier U2B and a capacitor C1, wherein: One end of the resistor R1 is connected to the output end of the operational amplifier U1 as the second input end of the gain control module, and the other end of the resistor R1 is connected to the non-inverting input end of the operational amplifier U2B and the first resistor end of the digital potentiometer U2A; The second resistance end of the digital potentiometer U2A is connected to the inverting input end of the operational amplifier U2B, and the sliding end of the digital potentiometer U2A is connected to the MCU as the first input end of the gain control module; the output end of the operational amplifier U2B is connected to the inverting input end of the operational amplifier U2B through the capacitor C1, and the resistor R2 is connected in parallel with the capacitor C1.

4. The high-precision EDFA control circuit with a wide gain adjustment range according to claim 3, characterized in that: The output optical power detection module includes an operational amplifier U3, a capacitor COUT1, a capacitor COUT2, a capacitor CF2 and a resistor RF2, wherein: The inverting input terminal of the operational amplifier U3 is connected to the output photodetector in the EDFA; The inverting input terminal of the operational amplifier U3 is grounded through capacitors COUT1 and COUT2 . The output terminal of the operational amplifier U3 is connected to the inverting input terminal of the operational amplifier U3 through resistor RF2 . The capacitor CF2 is connected in parallel with the resistor RF2 .

5. The high-precision EDFA control circuit with a wide gain adjustment range according to claim 4, characterized in that: The PID control module includes a resistor R3, a resistor R4, a resistor R5, a capacitor C2 and an operational amplifier U4, wherein: One end of the resistor R3 is connected to the output end of the operational amplifier U2B as the control given end of the PID control module, and the other end of the resistor R3 is connected to the non-inverting input end of the operational amplifier U4. One end of the resistor R4 is connected to the output end of the operational amplifier U3 as the control feedback end, and the other end of the resistor R4 is connected to one end of the resistor R5 and the inverting input end of the operational amplifier U4. The other end of the resistor R5 is connected to the output end of the operational amplifier U4 through the capacitor C2, and the output end of the operational amplifier U4 is connected to the input end of the pump control module.

6. The high-precision EDFA control circuit with a wide gain adjustment range according to claim 3, characterized in that: The resistance value of the resistor R1 is 10KΩ, and the resistance value of the resistor R2 is 80KΩ.

7. The high-precision EDFA control circuit with a wide gain adjustment range according to claim 3, characterized in that: The model of the digital potentiometer U2A is MAX5484.

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