Waveform shaping circuit for laser driving circuit, laser driving circuit, and laser

Abstract

The present application provides a waveform shaping circuit for a laser driving circuit, a laser driving circuit, and a laser. The pulse start waveform is attenuated to a lower power, and the original pulse power is output after the delay, so that laser relaxation oscillation disappears or occurs at a low power of light emission. The amplitude and the occurrence probability of the laser relaxation oscillation are reduced, so that the abnormal power at the pulse working moment is reduced, and thus the optical fiber is prevented from being damaged due to overheating.

Description

Waveform shaping circuit of laser driving circuit, laser driving circuit and laser

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application number 2023110932923 filed with the China Patent Office on August 25, 2023, entitled “Waveform shaping circuit for laser driving circuit, laser driving circuit and laser”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of laser technology, and in particular to a waveform shaping circuit of a laser driving circuit, a laser driving circuit, and a laser. Background Art

[0004] The driving circuit of the existing laser is generally input with an analog DC signal or a pulse signal from the front end, and the pulse signal is basically an ordinary square wave signal.

[0005] A laser outputs a corresponding pulsed light wave in response to an input pulse signal. However, most lasers utilize multiple laser diodes (LDs) rather than just a single one. This requires the output fibers to be connected in parallel. This configuration can easily lead to fiber burnout when the laser is operating at high power. Fiber burnout occurs due to large relaxation oscillations at the start of the pulse. This oscillation, combined with the high current corresponding to high power, causes the fiber to experience several times the normal power at the moment the pulse begins, far exceeding the rated power of the fiber, causing it to rapidly heat up and burn out.

[0006] Application Contents

[0007] The purpose of the present application is to solve the problem that a large relaxation oscillation phenomenon at the beginning of an existing laser pulse causes overheating and damage to the optical fiber.

[0008] To solve the above problems, the present application provides a waveform shaping circuit for a laser driving circuit, comprising a signal input interface, a trigger start unit, a delayed power supply control unit, a delay unit, an attenuation control unit, a constant voltage control unit, a signal coupling unit, and a signal output interface; the signal input interface is respectively connected to the trigger start unit and the signal coupling unit, and the input signal is divided into two paths after passing through the signal input interface and is respectively sent to the trigger start unit and the signal coupling unit; the signal coupling unit and the attenuation control unit are respectively connected to the signal output interface; the trigger start unit is configured to control the delayed power supply control unit to be turned on when the voltage of the input signal is greater than a preset trigger comparison voltage; when the delayed power supply control unit is turned on, the delay unit turns on the attenuation control unit, so that the input signal after passing the signal coupling unit is attenuated by the constant voltage control unit, and after the delay time, the delay unit turns off the attenuation control unit, and the input signal after passing the signal coupling unit is not attenuated; the constant voltage control unit is connected to the attenuation control unit and is configured to control the attenuation size of the input signal.

[0009] Optionally, when the input signal ends, the trigger start unit is triggered to flip, the delayed power supply control unit is turned off, and the attenuation control unit is turned off.

[0010] Optionally, the trigger start unit includes a first operational amplifier, a first resistor and a first adjustable resistor; the upper end of the first resistor is connected to the power supply voltage, the lower end is connected to the upper end of the first adjustable resistor, and the lower end of the first adjustable resistor is grounded; the positive pole of the first operational amplifier is connected to the signal input interface, the negative pole is connected to the lower end of the first resistor and the center tap of the first adjustable resistor, and the output end is connected to the delayed power supply control unit.

[0011] Optionally, the delay unit includes a first capacitor and a second adjustable resistor; the upper end of the second adjustable resistor is connected to the power supply voltage through the delayed power supply control unit, the lower end of the second adjustable resistor is connected to the upper end of the first capacitor, and the lower end of the first capacitor is grounded; the upper end of the second adjustable resistor and the center tap of the second adjustable resistor are both connected to the attenuation control unit, configured to supply power to the attenuation control unit to turn on the attenuation control unit; the lower end of the second adjustable resistor is connected to the attenuation control unit, configured to trigger the attenuation control unit to turn off based on the voltage boost of the first capacitor.

[0012] Optionally, the first adjustable resistor and the second adjustable resistor are potentiometers or variable resistors.

[0013] Optionally, the attenuation control unit includes a detection control chip and a first switching element; the power supply end of the detection control chip is connected to the upper end of the second adjustable resistor and the center tap of the second adjustable resistor, and the input end of the detection control chip is connected to the lower end of the second adjustable resistor; the output end of the detection control chip is connected to the base of the first switching element, the collector of the first switching element is connected to the signal coupling unit and the signal output interface, and the emitter of the first switching element is grounded.

[0014] Optionally, the detection control chip is configured to control the on and off of the first switching element.

[0015] Optionally, the constant voltage control unit includes a second operational amplifier, a second resistor, a third resistor, a fourth resistor and a third adjustable resistor; the positive electrode of the second operational amplifier is connected to the power supply voltage through the second resistor and to ground through the third adjustable resistor, the negative electrode is grounded through the third resistor and the fourth resistor, and the output end is connected between the third resistor and the fourth resistor; the emitter of the first switching element is connected between the third resistor and the fourth resistor and to ground through the fourth resistor.

[0016] Optionally, the delayed power supply control unit includes a second switching element; the base of the second switching element is connected to the output end of the first operational amplifier, the emitter is connected to the power supply voltage, and the collector is connected to the upper end of the second adjustable resistor.

[0017] Optionally, the signal coupling unit includes a fifth resistor, and the fifth resistor is connected between the signal input interface and the signal output interface.

[0018] The present application provides a laser driving circuit, comprising a waveform shaping circuit of any of the above-mentioned laser driving circuits.

[0019] Optionally, when the input signal ends, the trigger start unit is triggered to flip, the delayed power supply control unit is turned off, and the attenuation control unit is turned off.

[0020] Optionally, the trigger start unit includes a first operational amplifier, a first resistor and a first adjustable resistor; the upper end of the first resistor is connected to the power supply voltage, the lower end is connected to the upper end of the first adjustable resistor, and the lower end of the first adjustable resistor is grounded; the positive pole of the first operational amplifier is connected to the signal input interface, the negative pole is connected to the lower end of the first resistor and the center tap of the first adjustable resistor, and the output end is connected to the delayed power supply control unit.

[0021] Optionally, the delay unit includes a first capacitor and a second adjustable resistor; the upper end of the second adjustable resistor is connected to the power supply voltage through the delayed power supply control unit, the lower end of the second adjustable resistor is connected to the upper end of the first capacitor, and the lower end of the first capacitor is grounded; the upper end of the second adjustable resistor and the center tap of the second adjustable resistor are both connected to the attenuation control unit, configured to supply power to the attenuation control unit to turn on the attenuation control unit; the lower end of the second adjustable resistor is connected to the attenuation control unit, configured to trigger the attenuation control unit to turn off based on the voltage boost of the first capacitor.

[0022] Optionally, the first adjustable resistor and the second adjustable resistor are potentiometers or variable resistors.

[0023] The present application provides a laser, comprising any one of the above-mentioned laser driving circuits.

[0024] The embodiment of the present application attenuates the pulse starting waveform to a lower power and then outputs the original pulse power after a delay, so that the laser relaxation oscillation disappears or occurs at a lower power of the output light, and its amplitude and generation probability are reduced, thereby reducing the abnormal power at the moment of pulse operation and preventing the optical fiber from overheating and damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without any creative work.

[0026] FIG1 is a schematic structural diagram of a waveform shaping circuit of a laser driving circuit in an embodiment of the present application;

[0027] FIG2 is a circuit diagram of a waveform shaping circuit of a laser driving circuit in an embodiment of the present application;

[0028] FIG3 is a waveform diagram of the laser output without the waveform shaping circuit provided in the embodiment of the present application;

[0029] FIG4 is a diagram showing the output waveform of a laser with the waveform shaping circuit provided in an embodiment of the present application added. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned objectives, features and advantages of the present application more clearly understood, the following detailed description of the specific embodiments of the present application is given in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application.

[0031] The improved design in the embodiments of this application reduces the initial pulse waveform to the minimum power of the laser emission, then outputs the corresponding pulse power after a delay, allowing laser relaxation oscillation to occur at the lowest output power. This allows the pulse power to be output normally without relaxation oscillation, significantly reducing the power generated by relaxation oscillation. The driver circuit using this new solution has been verified to significantly improve the amplitude and probability of relaxation oscillation generated by the laser output, and prevents fiber burnout.

[0032] Referring to the structural schematic diagram of a waveform shaping circuit of a laser driving circuit shown in Figure 1, it is shown that the waveform shaping circuit includes a signal input interface, a trigger start unit, a delayed power supply control unit, a delay unit, an attenuation control unit, a constant voltage control unit, a signal coupling unit, and a signal output interface.

[0033] The waveform shaping circuit described above can serve as a pre-stage circuit for the driver circuit of a semiconductor laser device. Specifically, the signal input interface is connected to the trigger start unit and the signal coupling unit. After passing through the signal input interface, the input signal is split into two paths, which are respectively sent to the trigger start unit and the signal coupling unit. The signal coupling unit and the attenuation control unit are respectively connected to the signal output interface.

[0034] The trigger start unit is configured to control the delayed power supply control unit to conduct when the voltage of the input signal is greater than a preset trigger comparison voltage. By adjusting the trigger comparison voltage, the trigger signal amplitude can be adjusted, which is flexible in application.

[0035] When the delayed power supply control unit is on, the delay unit turns on the attenuation control unit, causing the input signal after the signal coupling unit to be attenuated by the constant voltage control unit. After a preset delay, the delay unit turns off the attenuation control unit, and the input signal after the signal coupling unit is no longer attenuated. The constant voltage control unit attenuates the input signal to the minimum power required for laser emission, minimizing the power while ensuring emission. This results in a low power level during laser relaxation oscillation, preventing overheating of the optical fiber. The delay unit's delay duration is adjustable, allowing for flexible application.

[0036] The constant voltage control unit is connected to the attenuation control unit and is configured to control the attenuation of the input signal. The constant voltage potential is adjustable and can output an attenuation signal of a preset magnitude.

[0037] The waveform shaping circuit of the laser driving circuit provided in the embodiment of the present application attenuates the pulse starting waveform to a lower power and then outputs the original pulse power after a delay, so that the laser relaxation oscillation disappears or occurs at a lower power of the output light, and its amplitude and generation probability are reduced, thereby reducing the abnormal power at the moment of pulse operation and preventing the optical fiber from overheating and damage.

[0038] Furthermore, when the input signal ends, the trigger start unit flips, the delayed power supply control unit turns off, and the attenuation control unit turns off. When the input signal ends and returns to zero, the waveform shaping circuit returns to its initial state.

[0039] Exemplarily, the signal from the front stage or external input is divided into two paths after passing through the signal input interface, one of which is sent to the trigger start unit. After being triggered, the delayed power supply control unit is controlled to turn on, and then the output voltage is used to power the delay unit and the attenuation control unit respectively. At the beginning of the power supply, the attenuation control unit is turned on due to the control of the delay unit, so that the signal of the signal input interface after passing through the signal coupling unit is attenuated, wherein the constant voltage control unit controls the attenuation of the signal. After the delay time is up, the attenuation control unit is turned off, and the signal from the signal coupling unit maintains the original value without attenuation, and is sent to the laser drive through the signal output interface to drive the laser LD to emit light. When the signal ends and returns to zero, the circuit returns to its initial state.

[0040] In the PWM (Pulse Width Modulation) signal mode, the above process is repeated so that each pulse is preceded by a threshold voltage of a certain length and amplitude. By adjusting and setting the required time and amplitude, the relaxation oscillation disappears or occurs at the beginning of the threshold voltage waveform, ensuring the normal output power of the pulse main waveform.

[0041] In CW (Continuous Wave) continuous output mode, based on the above process, only a threshold voltage delay waveform is added at the beginning of the waveform. The subsequent continuous main waveform maintains normal output power, and also avoids the superposition effect of the relaxation oscillation waveform on the main waveform power.

[0042] Therefore, the above technical solution can be used for both PWM pulse signal and continuous signal laser driving circuits, avoiding the burning of optical fibers due to relaxation oscillation problems and improving the safety of the equipment.

[0043] Exemplarily, the trigger start unit includes a first operational amplifier, a first resistor, and a first adjustable resistor. The upper end of the first resistor is connected to a power supply voltage, the lower end is connected to the upper end of the first adjustable resistor, and the lower end of the first adjustable resistor is grounded. The positive electrode of the first operational amplifier is connected to a signal input interface, the negative electrode is connected to the lower end of the first resistor and the center tap of the first adjustable resistor, and the output end is connected to the delayed power supply control unit.

[0044] The first resistor and the first adjustable resistor form a voltage divider circuit, which serves as the negative input of the first operational amplifier. The input signal serves as the positive input of the first operational amplifier, and the two are compared. For example, the adjustable resistor in this embodiment can be a potentiometer, a variable resistor, or other components. By adjusting the first adjustable resistor to adjust the trigger comparison voltage, the trigger signal amplitude can be adjusted, which provides flexible application.

[0045] Exemplarily, the above delay unit includes a first capacitor and a second adjustable resistor; the upper end of the second adjustable resistor is connected to the power supply voltage through the delay power supply control unit, the lower end of the second adjustable resistor is connected to the upper end of the first capacitor, and the lower end of the first capacitor is grounded; the upper end of the second adjustable resistor and the center tap of the second adjustable resistor are both connected to the attenuation control unit, configured to supply power to the attenuation control unit to turn on the attenuation control unit; the lower end of the second adjustable resistor is connected to the attenuation control unit, configured to trigger the attenuation control unit to turn off based on the boost of the first capacitor.

[0046] When the input signal is input, the attenuation control unit is triggered to turn on. Then, the RC delay circuit composed of a capacitor and a resistor is used for delay. When the voltage at the capacitor rises to the set voltage, the attenuation control unit is triggered to turn off. The delay time is adjustable, which is flexible in application.

[0047] Exemplarily, the above-mentioned attenuation control unit includes a detection control chip and a first switching element; the power supply end of the detection control chip is connected to the upper end of the second adjustable resistor and the center tap of the second adjustable resistor, and the input end of the detection control chip is connected to the lower end of the second adjustable resistor; the output end of the detection control chip is connected to the base of the first switching element, the collector of the first switching element is connected to the signal coupling unit and the signal output interface, and the emitter of the first switching element is grounded.

[0048] The detection control chip can control the on and off of the first switch element, thereby controlling whether to attenuate the input signal.

[0049] Exemplarily, the above-mentioned constant voltage control unit includes a second operational amplifier, a second resistor, a third resistor, a fourth resistor and a third adjustable resistor; the positive pole of the second operational amplifier is connected to the power supply voltage through the second resistor and to the ground through the third adjustable resistor, the negative pole is grounded through the third resistor and the fourth resistor, and the output end is connected between the third resistor and the fourth resistor; the emitter of the first switching element is connected between the third resistor and the fourth resistor and to the ground through the fourth resistor.

[0050] The constant voltage control unit includes an operational amplifier, and through the above connection method, the voltage outputted from its output terminal can be kept constant, thus achieving a constant voltage output. The above input signal is attenuated and limited to the voltage drop of the above fourth resistor.

[0051] Exemplarily, the delayed power supply control unit includes a second switching element; the base of the second switching element is connected to the output end of the first operational amplifier, the emitter is connected to the power supply voltage, and the collector is connected to the upper end of the second adjustable resistor.

[0052] The second switch element is controlled by the output signal of the first operational amplifier, and its on-off state can control the charging of the delay unit and the power supply of the attenuation control unit.

[0053] Exemplarily, the signal coupling unit includes a fifth resistor connected between the signal input interface and the signal output interface.

[0054] Referring to the circuit diagram of a waveform shaping circuit of a laser driving circuit shown in FIG2 , a signal input interface 01 , a signal coupling unit 02 , a signal output interface 03 , a trigger start unit 04 , a delayed power supply control unit 05 , a delay unit 06 , an attenuation control unit 07 , and a constant voltage control unit 08 are shown.

[0055] Among them, the signal input interface 01 includes a signal input interface CH1_IN, which is respectively connected to the lower end of the resistor R1 of the signal coupling unit 02 and connected to the pin pin5 of the operational amplifier U3-B through the input of the trigger starting unit 04 (see the arrow in Figure 2).

[0056] The trigger start unit 04 input network is connected to pin5 of U3-B, the lower end of the potentiometer VR1 is grounded, the upper end of the resistor R4 is connected to the power supply VCC, the pin 6 of U3-B is connected to the lower end of R4, the upper end of VR1 and the center tap respectively, and the pin 7 of U3-B is connected to the control end of the delayed power supply control unit 05.

[0057] The B pole of the switch tube Q3 of the delayed power supply control unit 05 is the control end, the E pole power supply end is connected to the power supply VCC, and the C pole of Q3 is the voltage output end, which are respectively connected to the upper end and the center tap of the potentiometer VR2 of the delay unit 06, and the detection control component of the attenuation control unit 07.

[0058] The lower end of VR2 in the delay unit 06 is respectively connected to the upper end of the capacitor C1 and the detection control component of the attenuation control unit 07, and the lower end of C1 is grounded.

[0059] The attenuation control unit 07 includes a detection control chip, whose output is connected to the B pole of the switch tube Q2, the E pole of Q2 is respectively connected to the upper end of the resistor R11 of the constant voltage control unit 08, the left end of the resistor R13 and the resistor R14, and the C pole of Q2 is respectively connected to the upper end of the resistor R1 of the signal coupling unit 02 and the signal output interface CH1_OUT.

[0060] The lower end of the resistor R11 of the constant voltage control unit 08 is grounded, the right end of the resistor R14 is connected to pin 2 of the operational amplifier U3-A, the right end of the resistor R13 is connected to pin 1 of U3-A, pin 4 of U3-A is grounded, pin 3 of U3-A is connected to the lower end of the resistor R15, the upper end of VR3 and the center tap respectively, the lower end of VR3 is grounded, pin 8 of U3-A, the upper end of R15 and the upper end of the capacitor C2 are respectively connected to the power supply VCC, and the lower end of C2 is grounded.

[0061] The working process of the above circuit is as follows:

[0062] 1) The input signal is input from CH1_IN and divided into two paths and sent to R1 and trigger start unit 04 input network respectively;

[0063] 2) The signal is input to pin 5 of U3 through the input network. When the voltage on pin 5 is greater than the voltage divided by R4 and VR1 on pin 6, the pin 7 output of op amp U3 drives Q3 to turn on.

[0064] 3) After Q3 is turned on, one path drives Q2 to turn on through the detection and control component; the other path charges C1 through VR2. When C1 is charged to the set voltage, the detection and control component controls Q2 to turn off.

[0065] 4) The voltage divider formed by R15 and VR3 is input to U3-A. Due to the rail-to-rail characteristics of the op amp, the voltage of R11 remains the same as the voltage of VR3. When the external signal is superimposed on R11, through the feedback of R14, the output of pin 1 of U3-A changes to keep the voltage of R11 unchanged.

[0066] 5) The input signal reaches the signal output after passing through R1 and is controlled by Q2. When Q2 is turned on, the signal is attenuated and limited to the voltage drop of R11 (that is, the set voltage value of VR3). When Q2 is turned off, the output signal amplitude remains unchanged with the input signal.

[0067] 6) VR2 and C1 form an RC delay circuit. By adjusting VR2, the on-time of Q2 can be set to set the output signal threshold time. The threshold time refers to the minimum driving signal amplitude holding time for the laser to just emit light.

[0068] 7) VR1 can adjust and set the trigger comparison voltage amplitude of the circuit of this application.

[0069] 8) Adjust VR3 to set the output signal threshold amplitude. The threshold amplitude refers to the minimum amplitude of the driving signal that can just emit laser light.

[0070] The above circuit provided in this embodiment has adjustable trigger signal amplitude, adjustable delay time, and adjustable constant voltage potential, and is flexible in application. A delayed constant voltage waveform is added before the main pulse waveform, so that the relaxation oscillation moves to the delayed constant voltage waveform, and its amplitude and generation probability are reduced, thereby reducing the abnormal power at the moment of pulse operation and preventing the optical fiber from overheating and damage. It has good versatility and is suitable for PWM mode waveforms, but the CW continuous DC drive mode does not affect normal operation.

[0071] Figure 3 shows the laser output waveform without the waveform shaping circuit provided in the embodiments of the present application, and Figure 4 shows the laser output waveform with the waveform shaping circuit provided in the embodiments of the present application. The top portion of Figure 4 shows the drive current waveform, and the bottom portion shows the laser waveform. Comparing Figures 3 and 4, it can be seen that the initial power is lower after the waveform shaping circuit is added, and the laser relaxation oscillation is suppressed.

[0072] Although the present application is disclosed as above, the present application is not limited thereto. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be based on the scope defined by the claims.

[0073] Finally, it should be noted that, in this document, relational terms such as first and second, etc., are used only 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 "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or device comprising the element.

[0074] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present application. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein. Industrial Applicability

[0075] The waveform shaping circuit, laser driving circuit and laser of the laser driving circuit provided in the embodiments of the present application have the pulse initial waveform attenuated to a lower power, and then output the original pulse power after a delay, so that the laser relaxation oscillation disappears or occurs at a lower power of the output light, and its amplitude and generation probability are reduced, thereby reducing the abnormal power at the moment of pulse operation, preventing the optical fiber from overheating and damage, and having significant economic benefits.

Claims

1. A waveform shaping circuit for a laser driving circuit, characterized in that: It includes a signal input interface, a trigger start unit, a delayed power supply control unit, a delay unit, an attenuation control unit, a constant voltage control unit, a signal coupling unit, and a signal output interface; The signal input interface is connected to the trigger start unit and the signal coupling unit respectively. The input signal is divided into two paths after passing through the signal input interface and sent to the trigger start unit and the signal coupling unit respectively; the signal coupling unit and the attenuation control unit are connected to the signal output interface respectively; The trigger start unit is configured to control the delayed power supply control unit to be turned on when the voltage of the input signal is greater than a preset trigger comparison voltage; When the delayed power supply control unit is turned on, the delay unit turns on the attenuation control unit, so that the input signal after the signal coupling unit is attenuated by the constant voltage control unit. After the delay time, the delay unit turns off the attenuation control unit, and the input signal after the signal coupling unit is not attenuated. The constant voltage control unit is connected to the attenuation control unit and is configured to control the attenuation magnitude of the input signal.

2. The waveform shaping circuit according to claim 1, characterized in that: When the input signal ends, the trigger start unit is triggered to flip, the delayed power supply control unit is turned off, and the attenuation control unit is turned off.

3. The waveform shaping circuit according to claim 1 or 2, characterized in that: The trigger start unit includes a first operational amplifier, a first resistor and a first adjustable resistor; The upper end of the first resistor is connected to the power supply voltage, the lower end is connected to the upper end of the first adjustable resistor, and the lower end of the first adjustable resistor is grounded; the positive pole of the first operational amplifier is connected to the signal input interface, the negative pole is connected to the lower end of the first resistor and the center tap of the first adjustable resistor, and the output end is connected to the delayed power supply control unit.

4. The waveform shaping circuit according to claim 3, characterized in that: The delay unit includes a first capacitor and a second adjustable resistor; The upper end of the second adjustable resistor is connected to the power supply voltage through the delayed power supply control unit, the lower end of the second adjustable resistor is connected to the upper end of the first capacitor, and the lower end of the first capacitor is grounded; The upper end of the second adjustable resistor and the center tap of the second adjustable resistor are both connected to the attenuation control unit, and are configured to supply power to the attenuation control unit to turn on the attenuation control unit; The lower end of the second adjustable resistor is connected to the attenuation control unit, and is configured to boost the voltage based on the first capacitor. The attenuation control unit is turned off.

5. The waveform shaping circuit according to claim 4, characterized in that: The first adjustable resistor and the second adjustable resistor are potentiometers or variable resistors.

6. The waveform shaping circuit according to claim 4 or 5, characterized in that: The attenuation control unit includes a detection control chip and a first switch element; The power supply end of the detection control chip is connected to the upper end of the second adjustable resistor and the center tap of the second adjustable resistor, and the input end of the detection control chip is connected to the lower end of the second adjustable resistor; The output end of the detection control chip is connected to the base of the first switch element, the collector of the first switch element is connected to the signal coupling unit and the signal output interface, and the emitter of the first switch element is grounded.

7. The waveform shaping circuit according to claim 6, characterized in that: The detection control chip is configured to control the on and off of the first switch element.

8. The waveform shaping circuit according to claim 6 or 7, characterized in that: The constant voltage control unit includes a second operational amplifier, a second resistor, a third resistor, a fourth resistor and a third adjustable resistor; The positive electrode of the second operational amplifier is connected to the power supply voltage through the second resistor and is grounded through the third adjustable resistor, the negative electrode is grounded through the third resistor and the fourth resistor, and the output end is connected between the third resistor and the fourth resistor; The emitter of the first switch element is connected between the third resistor and the fourth resistor, and is grounded through the fourth resistor.

9. The waveform shaping circuit according to any one of claims 4 to 8, characterized in that: The delayed power supply control unit includes a second switch element; The base of the second switch element is connected to the output end of the first operational amplifier, the emitter is connected to the power supply voltage, and the collector is connected to the upper end of the second adjustable resistor.

10. The waveform shaping circuit according to any one of claims 1 to 8, characterized in that: The signal coupling unit includes a fifth resistor, and the fifth resistor is connected between the signal input interface and the signal output interface.

11. A laser driving circuit, characterized in that: A waveform shaping circuit comprising the laser driving circuit according to claim 1.

12. The laser driving circuit according to claim 11, characterized in that: When the input signal ends, the trigger start unit is triggered to flip, the delayed power supply control unit is turned off, and the attenuation control unit is turned off.

13. The laser driving circuit according to claim 11 or 12, characterized in that: The trigger start unit includes a first operational amplifier, a first resistor and a first adjustable resistor; The upper end of the first resistor is connected to the power supply voltage, the lower end is connected to the upper end of the first adjustable resistor, and the lower end of the first adjustable resistor is grounded; the positive pole of the first operational amplifier is connected to the signal input interface, the negative pole is connected to the lower end of the first resistor and the center tap of the first adjustable resistor, and the output end is connected to the delayed power supply control unit.

14. The laser driving circuit according to claim 13, characterized in that: The delay unit includes a first capacitor and a second adjustable resistor; The upper end of the second adjustable resistor is connected to the power supply voltage through the delayed power supply control unit, the lower end of the second adjustable resistor is connected to the upper end of the first capacitor, and the lower end of the first capacitor is grounded; The upper end of the second adjustable resistor and the center tap of the second adjustable resistor are both connected to the attenuation control unit, and are configured to supply power to the attenuation control unit to turn on the attenuation control unit; The lower end of the second adjustable resistor is connected to the attenuation control unit and is configured to trigger the attenuation control unit to be turned off based on the voltage boost of the first capacitor.

15. The laser driving circuit according to claim 14, characterized in that: The first adjustable resistor and the second adjustable resistor are potentiometers or variable resistors.

16. A laser, characterized in that: The laser driving circuit comprises the laser driving circuit as described in any one of claims 11 to 15.

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