Stable light source power adjustable external driving circuit and light power adjusting method

Abstract

The invention relates to the technical field of radio frequency optical fibers, in particular to a stable light source power adjustable external driving circuit and an optical power adjusting method.The external driving circuit comprises a positive voltage reset channel and a negative voltage reset channel, the external driving circuit receives optical signals of a laser through a detector and converts the optical signals into electric signals; the voltage of the detector and the set reference voltage are subjected to real-time differential amplification to obtain a state signal, the state signal is fed back to the control circuit, and the control circuit outputs proper bias voltage to the external modulator, so that the optical power of the laser is changed, and a stable laser light source with corresponding power can be obtained by changing the reference voltage; when the bias voltage drifts out of the maximum control voltage range and the minimum control voltage range of the system, the reset circuit resets the working state of the external drive and sets the bias voltage to be zero, and the external drive circuit works again until the output power of the laser is equal to the reference optical power.

Description

Technical Field

[0001] The present invention relates to the field of radio frequency optical fiber technology, and in particular to an external driving circuit with adjustable power of a stable light source and an optical power regulation method. Background Art

[0002] In the field of optoelectronics, the regulation of optical power is crucial to ensure the quality of optical signals. Application scenarios such as lithography, spectral analysis, and optical communications all require precise control of light intensity. As a key step in the application of optical technology, optical power regulation not only improves the accuracy of scientific research, but also promotes the development of industries such as communications, medical treatment, and manufacturing. Stable laser light source output is the key to ensuring the stability of optical signal intensity and phase, which is crucial for the reliability of data transmission. With the development of analog signal optical fiber transmission technology, the frequency of optical signal transmission is getting higher and higher, and has now reached the Ka band. In this case, the performance of laser compression point and noise coefficient deteriorates, and direct modulation can no longer meet the performance index requirements. It is necessary to use an electro-optical modulation device intensity external modulator. However, the external modulator is an extremely sensitive device, and temperature fluctuations will have a greater impact on its working state. In addition, the electro-optical modulation device intensity external modulator requires a bias voltage forced reset function to prevent the bias voltage from exceeding the control voltage range of the drive circuit, thereby affecting the accuracy and stability of the power output of the entire system.

[0003] At present, the commonly used reset method is to use a single-chip microcomputer to monitor the bias voltage. When the voltage exceeds the maximum bias range of the system, a forced reset command is issued to the system to reset the bias voltage. The biggest disadvantage of this method is that the single-chip microcomputer itself and the peripheral circuits are complex, which is not conducive to miniaturization and integration. In addition, the single-chip microcomputer requires a crystal oscillator to provide a frequency source, and the introduced frequency signal is difficult to shield and eliminate, which affects the signal transmission quality and the overall performance of the system. Summary of the invention

[0004] The purpose of the present invention is to provide an external driving circuit with adjustable stable light source power and an optical power regulation method, aiming to achieve stable and controllable output optical power of the laser through a simple architecture without electromagnetic interference of the frequency source.

[0005] To achieve the above-mentioned object, the present invention provides an external driving circuit for a stable light source with adjustable power, comprising a positive voltage reset channel and a negative voltage reset channel, wherein the positive voltage reset channel of the device comprises a first RC integration circuit, a first comparator, an N-type MOS tube and a second RC integration circuit connected in sequence, and the negative voltage reset channel comprises a first RC integration circuit, a second comparator, a P-type MOS tube and a third RC integration circuit connected in sequence, wherein the first RC integration circuit is shared by the positive voltage reset channel and the negative voltage reset channel;

[0006] The first comparator and the second comparator adopt a dual rail-to-rail operational amplifier chip including two groups of operational amplifiers, the N-type MOS tube and the P-type MOS tube adopt a dual MOS tube chip including two groups of MOS tubes, and the integral output end of the first RC integral circuit is simultaneously connected to the first comparator, the second comparator, the first diode, the second diode and the external modulator bias BIAS interface.

[0007] Among them, the positive potential reset circuit in the positive voltage reset channel is provided with a first diode D1, an N-type MOS tube and a resistor R2, the cathode of the first diode D1 is connected to the drain of the N-type MOS tube, the gate of the N-type MOS tube is connected to the resistor R5, the source of the N-type MOS tube is connected to the resistor R2, the other end of the resistor R2 is grounded, and the resistance of the resistor R2 is 1kΩ.

[0008] The first RC integration circuit is composed of a resistor R8 and a capacitor C3. One end of the resistor R8 is connected to the state signal V, and the other end is connected in series with the capacitor C3. The other end of the capacitor C3 is grounded, and the series end with the resistor is connected to the external modulator, the anode of the first diode D1, and the cathode of the second diode D2. At the same time, the series resistor R7 is connected to the 3rd pin of the first comparator, and the series resistor R 11 Connect to pin 5 of the second comparator.

[0009] Wherein, the first comparator is provided with a first operational amplifier U1A, resistors R1, R3, R4, R6 and R7, and a capacitor C1, wherein pin 8 of the first operational amplifier U1A is connected to +12V, pin 4 is connected to -12V, one end of the resistor R1 is connected to the +12V power supply, and the other end is connected in series with resistors R3, R4 and capacitor C1, the other ends of the resistor R4 and capacitor C1 are grounded, the other end of the resistor R3 is connected to pin 2 of the first comparator, pin 1 of the first comparator is connected to resistor R6, and the other end of the resistor R6 is connected to resistor R5 and capacitor C2 at the same time.

[0010] The second RC integration circuit is composed of a resistor R8 and a capacitor C2, one end of the capacitor C2 is grounded, and the other end is connected to the resistor R5, and the connecting end is also connected to R6, the other end of the resistor R5 is connected to the gate of the N-type MOS tube, the resistance of the resistor R5 is 1kΩ, and the capacitance of the capacitor C3 is 10μF.

[0011] The negative potential reset circuit in the negative voltage reset channel is provided with a second diode D2, a P-type MOS tube and a resistor R 15 The anode of the second diode D2 is connected to the drain of the P-type MOS tube, the gate of the P-type MOS tube is connected to the resistor R9, and the source of the P-type MOS tube is connected to the resistor R 15 Connect the resistor R 15 The other end is grounded.

[0012] The second comparator is provided with a second operational amplifier U1B, a resistor R 10 , R 11 , R 12 , R 13 and R 14 , capacitor C5, the 8th pin of the first operational amplifier U1B is connected to +12V, the 4th pin is connected to -12V, the resistor R 12 One end is connected to -12V power supply, and the other end is connected to resistor R 13 , R 14 , capacitor C5 in series, resistor R 14 and the other end of capacitor C5 is grounded, resistor R 13 The other end is connected to the 6th foot of the second comparator, and the 7th foot of the second comparator is connected to the resistor R10. 10 The other end is connected to resistor R9 and capacitor C4 at the same time.

[0013] The third RC integration circuit is composed of a resistor R9 and a capacitor C4. One end of the capacitor C4 is grounded, and the other end is connected to the resistor R9. 10 The other end of the resistor R9 is connected to the gate of the P-type MOS tube, the resistance of the resistor R9 is 1kΩ, and the capacitance of the capacitor C4 is 10μF.

[0014] The present invention also proposes a light power adjustment method with adjustable power of a stable light source, which adopts the external driving circuit with adjustable power of the stable light source, and comprises the following steps:

[0015] Step 1: Set the reference optical power, which corresponds to a unique reference voltage value;

[0016] Step 2: The laser outputs an optical signal, and the detector receives the optical signal for photoelectric conversion. Different optical power outputs correspond to unique detector voltage values.

[0017] Step 3: The detector voltage and the reference voltage are differentially amplified and output as a state signal V. The external modulator adjusts the laser output optical power to the reference optical power according to the state signal.

[0018] Step 4: Change the reference voltage value, and the external driving device adjusts the laser output optical power to be equal to the reference optical power.

[0019] The present invention provides an external driving circuit and optical power regulation method with adjustable power of a stable light source, including a positive voltage reset channel and a negative voltage reset channel. The external driving circuit receives the optical signal of the laser through a detector, converts the optical signal into an electrical signal, obtains a state signal by performing real-time differential amplification between the voltage of the detector and a set reference voltage, and feeds it back to a control circuit. The control circuit outputs a suitable bias voltage to an external modulator, thereby changing the optical power of the laser. By changing the reference voltage, a stable laser light source of corresponding power can be obtained; when the bias voltage drifts out of the maximum and minimum control voltage range of the system, the reset circuit resets the working state of the external drive and sets the bias voltage to 0, and the external driving circuit works again until the output power of the laser is equal to the reference optical power. The present invention realizes the regulation of the control voltage by charging and discharging the capacitor, and has the characteristics of simple architecture and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 It is a structural schematic diagram of an external driving circuit with adjustable power of a stable light source of the present invention.

[0022] Figure 2 It is a schematic diagram of the implementation principle of an external driving circuit with adjustable power of a stable light source of the present invention. DETAILED DESCRIPTION

[0023] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0024] See also Figure 1The present invention proposes an external driving circuit with adjustable power of a stable light source, including a positive voltage reset channel and a negative voltage reset channel. The positive voltage reset channel of the device includes a first RC integration circuit, a first comparator, an N-type MOS tube and a third RC integration circuit connected in sequence, and the negative voltage reset channel includes a first RC integration circuit, a second comparator, a P-type MOS tube and a third RC integration circuit connected in sequence. The first comparator and the second comparator use a dual-rail-to-rail operational amplifier chip containing two groups of operational amplifiers, and the N-type MOS tube and the P-type MOS tube use a dual MOS tube chip containing two groups of MOS tubes. The integral output end of the first RC integration circuit is simultaneously connected to the first comparator, the second comparator, the first diode, the second diode and the external modulator bias BIAS interface.

[0025] The positive potential reset circuit in the positive voltage reset channel is provided with a first diode D1, an N-type MOS tube and a resistor R2, the cathode of the first diode D1 is connected to the drain of the N-type MOS tube, the gate of the N-type MOS tube is connected to the resistor R5, the source of the N-type MOS tube is connected to the resistor R2, the other end of the resistor R2 is grounded, and the resistance value of the resistor R2 is 1kΩ.

[0026] The first RC integration circuit is composed of a resistor R8 and a capacitor C3, wherein one end of the resistor R8 is connected to the state signal V, and the other end is connected in series with the capacitor C3, the other end of the capacitor C3 is grounded, and the series end with the resistor is connected to the external modulator, the anode of the first diode D1, and the cathode of the second diode D2, and the series resistor R7 is connected to the 3rd pin of the first comparator, and the series resistor R 11 Connected to the 5th pin of the second comparator. The resistance of resistor R8 is 100kΩ, the resistance of R7 is 0Ω, and R 11 The resistance value of is 0Ω, the capacitance value of capacitor C3 is 10μF, and the models of the first diode D1 and the second diode D2 are both 1N4148.

[0027] The first comparator is provided with a first operational amplifier U1A, resistors R1, R3, R4, R6 and R7, and a capacitor C1, wherein the 8th pin of the first operational amplifier U1A is connected to +12V, the 4th pin is connected to -12V, one end of the resistor R1 is connected to the +12V power supply, and the other end is connected in series with the resistors R3, R4, and the capacitor C1, the other ends of the resistor R4 and the capacitor C1 are grounded, the other end of the resistor R3 is connected to the 2nd pin of the first comparator, the 1st pin of the first comparator is connected to the resistor R6, and the other end of the resistor R6 is connected to the resistor R5 and the capacitor C2 at the same time. The resistance value of the resistor R1 is 2kΩ, the resistance value of R3 is 2kΩ, the resistance value of R1 is 10kΩ, and the capacitance value of the capacitor C1 is 0.1μF.

[0028] The second RC integration circuit is composed of a resistor R8 and a capacitor C2. One end of the capacitor C2 is grounded, and the other end is connected to the resistor R5. The connecting end is also connected to R6. The other end of the resistor R5 is connected to the gate of the N-type MOS tube. The resistance of the resistor R5 is 1kΩ, and the capacitance of the capacitor C3 is 10μF.

[0029] The negative potential reset circuit in the negative voltage reset channel is provided with a second diode D2, a P-type MOS tube and a resistor R 15 The anode of the second diode D2 is connected to the drain of the P-type MOS tube, the gate of the P-type MOS tube is connected to the resistor R9, and the source of the P-type MOS tube is connected to the resistor R 15 Connect the resistor R 15 The other end is grounded.

[0030] The second comparator is provided with a second operational amplifier U1B, a resistor R 10 , R 11 , R 12 , R 13 and R 14 , capacitor C5, wherein the 8th pin of the first operational amplifier U1B is connected to +12V, the 4th pin is connected to -12V, the resistor R 12 One end is connected to -12V power supply, and the other end is connected to resistor R 13 , R 14 , capacitor C5 in series, resistor R 14 and the other end of capacitor C5 is grounded, resistor R 13 The other end is connected to the 6th pin of the second comparator, and the 7th pin of the second comparator is connected to the resistor R 10 Connect the resistor R 10 The other end is connected to resistor R9 and capacitor C4 at the same time. The resistance of resistor R1 is 2kΩ, the resistance of R3 is 2kΩ, the resistance of R1 is 10kΩ, and the capacitance of capacitor C1 is 0.1μF.

[0031] The third RC integration circuit is composed of a resistor R9 and a capacitor C4. One end of the capacitor C4 is grounded, and the other end is connected to the resistor R9. 10 The other end of the resistor R9 is connected to the gate of the P-type MOS tube, the resistance of the resistor R9 is 1kΩ, and the capacitance of the capacitor C4 is 10μF.

[0032] like Figure 2As shown, the implementation principle of the external drive of the present invention for stable light source with adjustable power is as follows: a differential amplification is performed according to the laser output optical power and the reference optical power to output a state signal V, and the voltage control circuit outputs a bias voltage to the external modulator according to the state signal. When the bias voltage of the voltage control circuit exceeds the maximum or minimum control voltage value of the system, the reset circuit sets the bias voltage to 0, and the state of the voltage control circuit is reset and the circuit is restarted until the laser output optical power is equal to the reference optical power.

[0033] In view of this, the present invention also proposes a method for forcibly resetting the bias voltage of an external modulator implemented by an external driver with adjustable power of a stable light source, comprising the following steps:

[0034] 1) The external modulator bias voltage forced reset device receives the state signal V, integrates the state signal V, and outputs the RC integrated voltage at five ports, respectively to the positive voltage reset channel connected to the first comparator and the first diode, the external modulator bias control, and the negative voltage reset channel connected to the second comparator and the second diode;

[0035] 2) The voltage across the resistor R4 is approximately 10V. The first comparator determines whether the output voltage of the first RC integration circuit is greater than 10V. When the integration voltage is greater than 10V, the first operational amplifier U1A outputs a level of +12V. When the integrator voltage is less than 10V, the first operational amplifier U1A outputs a level of -12V. The first diode D1 has a voltage output when the forward voltage is greater than +0.7V. When the output voltage of the first RC integration circuit is greater than 0.7V, D1 is turned on, and the drain of the N-type MOS tube is connected to the first integration circuit. When the output voltage of the first RC integration circuit is less than 0.7V, D1 is not turned on, and the drain of the N-type MOS tube is equivalent to being disconnected from the first RC integration circuit.

[0036] 3) The second RC integration circuit integrates the output voltage of the first comparator. When the first comparator outputs a low level of -12V, the second RC integration circuit starts to integrate, that is, the output voltage of the second RC integrator starts to decrease. When the first comparator outputs a high level of +12V, the second RC integration circuit starts to integrate, that is, the output voltage of the second RC integrator starts to increase.

[0037] 4) The positive potential reset circuit has two states: when the gate of the N-type MOS tube is at a negative voltage, the MOS tube is not turned on; when the gate of the N-type MOS tube is at a positive voltage, the MOS tube is turned on. At this time, one end of the capacitor C3 of the first RC integration circuit is grounded, and the other end is grounded through the first diode D1 and the N-type MOS tube that is turned on, and then through the resistor R2;

[0038] 5) Resistor R 14The voltage obtained by the above division is about -10V. The second comparator determines whether the output voltage of the first integration circuit is less than -10V. When the integration voltage is less than -10V, the second operational amplifier U1B outputs a level of -12V. When the RC integrator voltage is greater than -10V, the second operational amplifier U1B outputs a level of +12V. The second diode D2 has a voltage output when the forward voltage is greater than +0.7V. When the output voltage of the first RC integration circuit is less than -0.7V, D2 is turned on, and the drain of the P-type MOS tube is connected to the first RC integration circuit. When the output voltage of the first RC integration circuit is greater than -0.7V, D2 is not turned on, and the drain of the P-type MOS tube is equivalent to being disconnected from the first RC integration circuit.

[0039] 6) The third RC integration circuit integrates the output voltage of the second comparator. When the second comparator outputs a low level of -12V, the third RC integration circuit starts to integrate, that is, the output voltage of the third RC integrator starts to decrease. When the second comparator outputs a high level of +12V, the third RC integration circuit starts to integrate, that is, the output voltage of the second RC integrator starts to increase.

[0040] 7) The negative potential reset circuit has two states: when the gate of the P-type MOS tube is at a positive voltage, the MOS tube is not turned on; when the gate of the P-type MOS tube is at a negative voltage, the MOS tube is turned on. At this time, one end of the capacitor C3 of the first RC integration circuit is grounded, and the other end is connected through the conductive second diode D2 and the conductive P-type MOS tube through the resistor R 15 Grounding;

[0041] 8) When the output voltage V b Satisfy -10V<V b When the output voltage of the first comparator is -12V, the output voltage of the second comparator is +12V. At this time, the first RC integration circuit works normally and does not perform the reset function. When the output voltage V b Meet V b >+10V, the output voltage of the first comparator is 12V, at this time, the N-type MOS tube is turned on, the first diode is turned on, one end of the capacitor of the first RC integration circuit is grounded, and the other end is grounded through the first diode D1 and the N-type MOS tube, through the resistor R2, the capacitor is discharged, and the output voltage of the first RC integrator is forced to reset to 0; when the output voltage V b Meet V b When the voltage is less than -10V, the output voltage of the second comparator is -12V. At this time, the P-type MOS tube is turned on, the second diode is turned on, one end of the capacitor of the first RC integrator circuit is grounded, and the other end is connected to the ground through the turned-on second diode D2 and the turned-on P-type MOS tube, through the resistor R 15Grounded, the capacitor is discharged, and the output voltage of the first RC integrator is forced to reset to 0.

[0042] Furthermore, the present invention also proposes a method for adjusting the optical power of a stable light source with adjustable power, using the external driving circuit of the stable light source with adjustable power, comprising the following steps:

[0043] Step 1: Set the reference optical power, which corresponds to a unique reference voltage value;

[0044] Step 2: The laser outputs an optical signal, and the detector receives the optical signal for photoelectric conversion. Different optical power outputs correspond to unique detector voltage values.

[0045] Step 3: The detector voltage and the reference voltage are differentially amplified and output as a state signal V. The external modulator adjusts the laser output optical power to the reference optical power according to the state signal.

[0046] Step 4: Change the reference voltage value, and the external driving device adjusts the laser output optical power to be equal to the reference optical power.

[0047] In this embodiment, when the output voltage of the first RC integration circuit, that is, the bias voltage of the external modulator, is greater than -10V and less than +10V, the second RC integration circuit and the third RC integration circuit integrate -12V and +12V respectively, the output voltage of the second RC integration circuit is -12V, and the output voltage of the third RC integration circuit is +12V, and the bias voltage output is in the non-reset area at this time; when the output voltage of the first RC integration circuit, that is, the bias voltage of the external modulator is higher than the forced reset voltage +10V, the second RC integration circuit integrates +12V, and the N-type MOS tube is turned on at this time, one end of the capacitor of the first RC integration circuit is grounded, and the other end is grounded through the turned-on first diode D1 and the turned-on N-type MOS tube through the resistor R2, the capacitor is discharged and reset, the bias voltage is set to 0, and the device is reset.

[0048] According to the calculation of the integration circuit in the basics of analog electronic technology, the time constant of the charging time of the first RC integration circuit satisfies the following relationship:

[0049] τ=R8×C3

[0050] In the formula, R8 is 400000Ω, C3 is 0.001F (10μF), and the time constant of capacitor charging can be calculated to be 4s.

[0051] The relationship between the voltage and time when the first RC integration circuit is charged satisfies the following relationship:

[0052]

[0053] In the formula, V0 is the initial voltage value, V is the state signal of the difference amplification between the reference voltage and the detector voltage, and the voltage value is +12V or -12V. According to the analysis, when the initial voltage value is 0, if the voltage of the integration circuit reaches +10V or -10V, the external modulator bias voltage forced reset device starts, and the time t used at this time is 3.3s.

[0054] When the voltage of the integration circuit reaches +10V or -10V, the forced reset device is activated, one end of the capacitor of the first RC integration circuit is grounded, and the other end is grounded through a conducting diode and MOS tube, and then through a resistor. The capacitor is discharged. According to the previous analysis of the RC integration circuit, the discharge time constant is 0.04s. After 3 to 5 time constants, the capacitor discharge ends, that is, 0.2s after the forced reset is started, the external modulator bias voltage is reset to 0V.

[0055] In summary, compared with the prior art, the technical solution of the present invention has the following characteristics:

[0056] 1. By changing the reference voltage, a corresponding stable light source can be obtained. The method is simple and practical.

[0057] 2. There is no frequency source in the circuit, which avoids the introduction of interference signals.

[0058] 3. The control voltage is adjusted by charging and discharging the capacitor, with a simple architecture and low cost.

[0059] 4. The chip is an operational amplifier and MOS tube, which is small in size and easy to integrate.

[0060] What is disclosed above is only a preferred embodiment of the present invention, and it certainly cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. An external driving circuit with adjustable power of a stable light source, characterized in that: The positive voltage reset channel comprises a positive voltage reset channel and a negative voltage reset channel, wherein the positive voltage reset channel comprises a first RC integration circuit, a first comparator, an N-type MOS transistor, and a second RC integration circuit connected in sequence, and the negative voltage reset channel comprises a first RC integration circuit, a second comparator, a P-type MOS transistor, and a third RC integration circuit connected in sequence, wherein the first RC integration circuit is shared by the positive voltage reset channel and the negative voltage reset channel; The first comparator and the second comparator adopt a dual rail-to-rail operational amplifier chip including two groups of operational amplifiers, the N-type MOS tube and the P-type MOS tube adopt a dual MOS tube chip including two groups of MOS tubes, and the integral output end of the first RC integral circuit is simultaneously connected to the first comparator, the second comparator, the first diode, the second diode and the external modulator bias BIAS interface.

2. The external driving circuit with adjustable power of a stable light source as claimed in claim 1, characterized in that: The positive potential reset circuit in the positive voltage reset channel is provided with a first diode D1, an N-type MOS tube and a resistor R2, the cathode of the first diode D1 is connected to the drain of the N-type MOS tube, the gate of the N-type MOS tube is connected to the resistor R5, the source of the N-type MOS tube is connected to the resistor R2, the other end of the resistor R2 is grounded, and the resistance value of the resistor R2 is 1kΩ.

3. The external driving circuit with adjustable power of a stable light source as claimed in claim 2, characterized in that: The first RC integration circuit is composed of a resistor R8 and a capacitor C3. One end of the resistor R8 is connected to the state signal V, and the other end is connected in series with the capacitor C3. The other end of the capacitor C3 is grounded, and the series end with the resistor is connected to the external modulator, the anode of the first diode D1, and the cathode of the second diode D2. At the same time, the series resistor R7 is connected to the 3rd pin of the first comparator, and the series resistor R 11 Connect to pin 5 of the second comparator.

4. The external driving circuit with adjustable power of a stable light source as claimed in claim 3, characterized in that: The first comparator is provided with a first operational amplifier U1A, resistors R1, R3, R4, R6 and R7, and a capacitor C1, wherein pin 8 of the first operational amplifier U1A is connected to +12V, pin 4 is connected to -12V, one end of the resistor R1 is connected to a +12V power supply, and the other end is connected in series with resistors R3, R4 and capacitor C1, the other ends of the resistor R4 and capacitor C1 are grounded, the other end of the resistor R3 is connected to pin 2 of the first comparator, pin 1 of the first comparator is connected to resistor R6, and the other end of the resistor R6 is connected to resistor R5 and capacitor C2 at the same time.

5. The external driving circuit with adjustable power of a stable light source as claimed in claim 4, characterized in that: The second RC integration circuit is composed of a resistor R8 and a capacitor C2. One end of the capacitor C2 is grounded, and the other end is connected to the resistor R5. The connecting end is also connected to R6. The other end of the resistor R5 is connected to the gate of the N-type MOS tube. The resistance of the resistor R5 is 1kΩ, and the capacitance of the capacitor C3 is 10μF.

6. The external driving circuit with adjustable power of a stable light source as claimed in claim 5, characterized in that: The negative potential reset circuit in the negative voltage reset channel is provided with a second diode D2, a P-type MOS tube and a resistor R 15 The anode of the second diode D2 is connected to the drain of the P-type MOS tube, the gate of the P-type MOS tube is connected to the resistor R9, and the source of the P-type MOS tube is connected to the resistor R 15 Connect the resistor R 15 The other end is grounded.

7. The external driving circuit with adjustable power of a stable light source as claimed in claim 6, characterized in that: The second comparator is provided with a second operational amplifier U1B, a resistor R 10 , R 11 , R 12 , R 13 and R 14 , capacitor C5, the 8th pin of the first operational amplifier U1B is connected to +12V, the 4th pin is connected to -12V, the resistor R 12 One end is connected to -12V power supply, and the other end is connected to resistor R 13 , R 14 , capacitor C5 in series, resistor R 14 and the other end of capacitor C5 is grounded, resistor R 13 The other end is connected to the 6th foot of the second comparator, and the 7th foot of the second comparator is connected to the resistor R10. 10 The other end is connected to resistor R9 and capacitor C4 at the same time.

8. The external driving circuit with adjustable power of a stable light source as claimed in claim 7, characterized in that: The third RC integration circuit is composed of a resistor R9 and a capacitor C4. One end of the capacitor C4 is grounded, and the other end is connected to the resistor R9. 10 The other end of the resistor R9 is connected to the gate of the P-type MOS tube, the resistance of the resistor R9 is 1kΩ, and the capacitance of the capacitor C4 is 10μF.

9. A method for adjusting light power of a stable light source with adjustable power, using the external driving circuit of the stable light source with adjustable power as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1: Set the reference optical power, which corresponds to a unique reference voltage value; Step 2: The laser outputs an optical signal, and the detector receives the optical signal for photoelectric conversion. Different optical power outputs correspond to unique detector voltage values. Step 3: The detector voltage and the reference voltage are differentially amplified and output as a state signal V. The external modulator adjusts the laser output optical power to the reference optical power according to the state signal. Step 4: Change the reference voltage value, and the external driving device adjusts the laser output optical power to be equal to the reference optical power.

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