Tunable semiconductor laser wavelength tuning method and system based on photoelectric feedback

Abstract

The invention relates to the technical field of optical fiber sensing and optical communication, and discloses a tunable semiconductor laser wavelength tuning system based on photoelectric feedback, which comprises a user control module, a modulation grating Y laser, a user application optical path, an optical splitter, an optical isolator, a photoelectric conversion circuit, a negative feedback amplification circuit and an adjustable current source circuit, and output light of the modulation grating Y laser passes through the optical splitter, one part of the output light enters the optical isolator and then enters the user application light path, and the other part of the output light enters the photoelectric conversion circuit and is input into the negative feedback amplification circuit, so that the adjustable current source circuit is controlled, SOA current is controlled to be output to the modulation grating Y laser, and the output light power is changed. In the calibration and normal working process of the modulation grating Y laser, the optical power output by the laser is collected in real time through the optical splitter, negative feedback is formed at the SOA current, and only the left current, the right current and the phase current need to be input, and the proper SOA current is automatically matched for power compensation.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber sensing and optical communication, and in particular to a method and system for tuning the wavelength of a tunable semiconductor laser based on photoelectric feedback. Background Art

[0002] Tunable semiconductor lasers are one of the most commonly used light sources in digital coherent optical communications and fiber-optic sensing systems. Continuously tunable wavelengths within the ITU channel or C-band, along with high precision, high power, and low cost, are key requirements for tunable lasers. Modulated grating Y lasers meet all of these requirements, making them widely used in fiber-optic sensing and optical communications.

[0003] Currently, the wavelength calibration method for modulated grating Y lasers is to scan the left current, right current, and phase current, select the left, right, and phase current values ​​corresponding to the required wavelength, and then adjust the SOA current to compensate for the output optical power so that the optical power stability of all wavelength outputs meets the requirements. However, the modulation method and structure of the modulated grating Y laser cause the change in SOA current to have a slight effect on the laser output wavelength, resulting in wavelength variation. At this time, it is necessary to fine-tune the phase current to make the wavelength meet the requirements. Fine-tuning the phase current will cause the output optical power of the laser to change. The SOA current needs to be adjusted again for optical power calibration. At this time, although the SOA current adjustment range is smaller than the first adjustment and has less impact on the wavelength, the phase current needs to be adjusted again to calibrate the output wavelength. Similarly, the range of the second fine-tuning of the phase current will also be smaller than the first adjustment, but it will also affect the output optical power. Therefore, after the first rough calibration is completed, the existing modulation method of the modulated grating Y laser needs to repeatedly adjust the phase current and SOA current for cyclic calibration for each output wavelength to ensure that the wavelength accuracy and power output meet the requirements.

[0004] The above is the current counting level, which mainly has the following shortcomings:

[0005] 1. Since the phase current and SOA current of the modulated grating Y laser will affect the output wavelength and output optical power, the existing method of adjusting a current individually and cyclic calibration cannot make the output wavelength and output optical power fully meet the target requirements, and can only approximate them step by step.

[0006] 2. In the field of optical communications, the ITU-T G.692 standard defines the center wavelength of 40-wave or 80-wave systems in the C band. In the field of fiber optic sensing, especially the fiber Bragg grating demodulation system, the modulated grating Y laser needs to output more than 4,000 wavelengths. Therefore, the existing method of cyclically calibrating the phase current and SOA current results in a very large workload and a very long time required for the calibration of the modulated grating Y laser. Summary of the Invention

[0007] The present invention provides a method and system for tuning the wavelength of a tunable semiconductor laser based on photoelectric feedback. During the calibration and normal operation of a modulated grating Y laser, the photoelectric feedback loop collects the optical power output by the laser in real time through a spectrometer, forming negative feedback at the SOA current. Only the left current, right current, and phase current need to be input, and the photoelectric feedback device will automatically match the appropriate SOA current for power compensation. At the same time, the photoelectric feedback device loop includes an adjustable potentiometer, which can manually adjust the required output optical power.

[0008] The present invention provides a tunable semiconductor laser wavelength tuning system based on photoelectric feedback, comprising a user control module, a modulated grating Y laser, a photoelectric feedback device, and a user application optical path, wherein the user control module is connected to the modulated grating Y laser, the modulated grating Y laser is connected to the photoelectric feedback device, and the photoelectric feedback device is connected to the user application optical path;

[0009] The photoelectric feedback device includes an optical splitter, an optical isolator, a photoelectric conversion circuit, a negative feedback amplifier circuit, and an adjustable current source circuit. The optical splitter and the adjustable current source circuit are both connected to the modulated grating Y laser. The optical splitter is also connected to the optical isolator and the photoelectric conversion circuit. The optical isolator is connected to the user application optical path. The photoelectric conversion circuit is connected to the negative feedback amplifier circuit, and the negative feedback amplifier circuit is connected to the adjustable current source circuit.

[0010] The user control module inputs left current, right current, phase current, and gain current to the modulated grating Y laser. The output light of the modulated grating Y laser passes through a spectrometer. According to the splitting ratio of the spectrometer, a part of the output light enters the optical isolator and then enters the user application optical path, and the other part of the output light enters the photoelectric conversion circuit to convert the feedback optical signal into a feedback electrical signal. The feedback electrical signal is input into the negative feedback amplifier circuit, and then controls the adjustable current source circuit to control the SOA current output to the modulated grating Y laser, thereby changing the output optical power.

[0011] Furthermore, the photoelectric conversion circuit, negative feedback amplifier circuit, and adjustable current source circuit specifically include:

[0012] Constant current source I3, capacitor C1, first resistor R1, second resistor R3, third resistor R4, fourth resistor R5, fifth resistor R6, sixth resistor R10, first operational amplifier X8, second operational amplifier X9, third operational amplifier X10, 2N3904 transistor Q1, light-emitting diode D1;

[0013] One end of the constant current source I3 is grounded, and the other end is connected to one end of the capacitor C1, one end of the first resistor R1, and the inverting input end of the first operational amplifier X8. The other end of the capacitor C1 and the other end of the first resistor R1 converge and are connected to the output end of the first operational amplifier X8 and the non-inverting input end of the second operational amplifier X9. The non-inverting input end of the first operational amplifier X8 is grounded. The inverting input end and output end of the second operational amplifier X9 are both connected to one end of the second resistor R3. The other end of the second resistor R3 is connected to the inverting input end of the third operational amplifier X10 and one end of the fifth resistor R6. A non-inverting input terminal of the third operational amplifier X10 is connected to one end of the third resistor R4 and one end of the fourth resistor R5. The other end of the third resistor R4 is connected to a power supply. The other end of the fourth resistor R5 is grounded. The other end of the fifth resistor R6 and the output terminal of the third operational amplifier X10 are both connected to the base of the 2N3904 transistor Q1. The collector of the 2N3904 transistor Q1 is connected to a power supply. The emitter of the 2N3904 transistor Q1 is connected to one end of the sixth resistor R10. The other end of the sixth resistor R10 is connected to the anode of the light-emitting diode D1. The cathode of the light-emitting diode D1 is grounded.

[0014] Furthermore, the optical splitter is a 1x2 optical splitter with a splitting ratio of 1:99, 99% of the outgoing light enters the optical isolator, and 1% of the outgoing light enters the photoelectric conversion circuit.

[0015] Furthermore, in the photoelectric feedback device,

[0016] The optical isolator is used to prevent the return light in the user application from interfering with the photoelectric feedback system;

[0017] The negative feedback amplifier circuit is used to reverse and amplify the feedback electrical signal. The reverse effect is that when the output optical power of the modulated grating Y laser decreases, the 1% feedback light decreases, and the corresponding feedback electrical signal decreases. At this time, the SOA current needs to be increased, and the adjustable current source circuit needs to be controlled to increase the output; the amplification effect is that the fluctuation range of the feedback optical signal is largely matched with the input range of the adjustable current source circuit.

[0018] Furthermore, the modulated grating Y laser includes a left sampled grating, a right sampled grating, a multimode interference coupler, a phase adjustment module, a gain control module, and an SOA semiconductor optical amplifier. The left sampled grating and the right sampled grating are both connected to the multimode interference coupler, and the multimode interference coupler is connected to the phase adjustment module. The phase adjustment module, the gain control module, and the SOA semiconductor optical amplifier are connected in sequence.

[0019] The left sampled grating, right sampled grating, phase adjustment module, gain control module, and SOA semiconductor optical amplifier are all driven by constant current. The left sampled grating and right sampled grating serve as reflectors and are two comb gratings with multiple reflection peaks. The two comb gratings form a vernier effect, so that the multimode interference coupler returns a reflection peak of a specific wavelength after superposition, and then inputs it into the gain control module for longitudinal mode screening. The phase adjustment module is used to achieve longitudinal mode movement and broaden the spectral range tuned under each longitudinal mode. The SOA semiconductor amplifier is used for optical power compensation to ensure that the optical power output within the set range is within the tuning range.

[0020] The present invention also provides a method for tuning the wavelength of a tunable semiconductor laser based on photoelectric feedback. Based on the tunable semiconductor laser wavelength tuning system described above, the method specifically includes:

[0021] S1, the user control module inputs left current, right current, phase current, and gain current to the modulated grating Y laser;

[0022] S2. In the modulated grating Y laser, the left and right sampled gratings are used as comb gratings. The two comb gratings form a vernier effect, so that the multimode interference coupler returns a reflection peak of a specific wavelength after superposition. The input gain control module performs longitudinal mode screening, the phase adjustment module realizes longitudinal mode shift, and broadens the spectral range tuned under each longitudinal mode. The SOA semiconductor amplifier performs optical power compensation and outputs optical power within a set range.

[0023] S3, the output light of the modulated grating Y laser passes through the optical splitter, the splitting ratio of the optical splitter is 1:99, and 99% of the output light enters the optical isolator and then enters the user application optical path;

[0024] S3, 1% of the output light enters the photoelectric conversion circuit to convert the feedback light signal into a feedback electrical signal, and the feedback electrical signal is input into the negative feedback amplifier circuit;

[0025] S4, the negative feedback amplifier circuit reverses and amplifies the feedback electrical signal;

[0026] Reverse: When the output optical power of the modulated grating Y laser decreases, the 1% feedback light decreases, and the corresponding feedback electrical signal decreases. At this time, the SOA current is increased to control the adjustable current source circuit to increase the output;

[0027] Amplification: The fluctuation range of the feedback optical signal is closely matched to the input range of the adjustable current source circuit;

[0028] S5. The feedback electrical signal output by the negative feedback amplifier circuit controls the adjustable current source circuit to control the SOA current output to the modulated grating Y laser, thereby changing the output optical power.

[0029] The beneficial effects of the present invention are:

[0030] In the present invention, during the calibration and normal operation of the modulated grating Y laser, each time the user control module inputs the left current, right current, phase current, and GAIN current, the photoelectric feedback system automatically generates the corresponding SOA current. During the calibration process, the introduction of the photoelectric feedback device is equivalent to inputting a phase current, and the phase current and SOA current are adjusted at the same time for coordinated control, so that the phase current and SOA current can be precisely calibrated together, thereby achieving precise calibration of the output wavelength and optical power. There is no need for the phase current and SOA current to cyclically approximate the calibration, which improves the calibration accuracy and reduces the calibration time. At the same time, an adjustable potentiometer is designed in the negative feedback amplifier circuit to adjust the negative feedback amplification factor, thereby adjusting the output optical power during calibration; in actual application, the left current, right current, phase current, and gain current are output according to the calibrated current, and the output optical power is automatically matched with the SOA current during calibration after being modulated by the photoelectric feedback device, thereby achieving the output wavelength and optical power during calibration. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The diagram is a structural diagram of the wavelength tuning system of a tunable semiconductor laser based on photoelectric feedback of the present invention.

[0032] Figure 2 Schematic diagram of the structure of the modulated grating Y laser in the present invention.

[0033] Figure 3 This is an application circuit diagram of the photoelectric conversion circuit, negative feedback amplifier circuit, and adjustable current source circuit in the present invention.

[0034] Figure 4 It is a schematic diagram of simulation results of the photoelectric conversion circuit, negative feedback amplifier circuit, and adjustable current source circuit in the present invention.

[0035] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0036] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0037] like Figure 1As shown, the present invention provides a tunable semiconductor laser wavelength tuning system based on photoelectric feedback. During the calibration and normal operation of the modulated grating Y laser, the photoelectric feedback loop collects the optical power output by the laser in real time through the optical splitter, and forms negative feedback at the SOA current. Only the left current, right current, and phase current need to be input, and the feedback system will automatically match the appropriate SOA current for power compensation. The photoelectric feedback loop contains an adjustable potentiometer, which can manually adjust the required output optical power. Figure 1 The figure shows a block diagram of a modulated grating Y laser application system, which includes a user control module, a modulated grating Y laser, a photoelectric feedback device, and a user application optical path. The user control module is connected to the modulated grating Y laser, the modulated grating Y laser is connected to the photoelectric feedback device, and the photoelectric feedback device is connected to the user application optical path.

[0038] (1) Modulated grating Y laser

[0039] like Figure 2 As shown, the modulated grating Y laser includes a left sampling grating, a right sampling grating, a multimode interference (MMI) 1X2 coupler, a phase adjustment module, a gain control module, and an SOA semiconductor optical amplifier. The left sampling grating and the right sampling grating are both connected to the multimode interference coupler, and the multimode interference coupler is connected to the phase adjustment. The phase adjustment module, the gain control module, and the SOA semiconductor optical amplifier are connected in sequence.

[0040] The left sampled grating, right sampled grating, phase adjustment module, gain control module, and SOA semiconductor optical amplifier are all driven by constant current. The left sampled grating and the right sampled grating serve as reflectors and are two comb-shaped gratings with multiple reflection peaks. The intervals between the comb teeth reflection peaks are slightly different. The two comb-shaped gratings form a vernier effect, so that the reflection peak of a specific wavelength is returned after the coupler is superimposed. The peak is then input into the gain control area for longitudinal mode screening. The phase adjustment module is used to achieve longitudinal mode movement and broaden the spectral range tuned under each longitudinal mode. The SOA semiconductor amplifier is used for optical power compensation to ensure a high optical power output within the tuning range and high stability.

[0041] (2) Photoelectric feedback device

[0042] The photoelectric feedback device includes a splitter (1x2 optical splitter with a splitting ratio of 1:99), an optical isolator, a photoelectric conversion circuit, a negative feedback amplifier circuit, and an adjustable current source circuit. The splitter and the adjustable current source circuit are both connected to the modulated grating Y laser. The splitter is also connected to the optical isolator and the photoelectric conversion circuit. The optical isolator is connected to the user application optical path, the photoelectric conversion circuit is connected to the negative feedback amplifier circuit, and the negative feedback amplifier circuit is connected to the adjustable current source circuit.

[0043] When the system is working, the user control module inputs left current, right current, phase current, and GAIN current (gain current) to the modulated grating Y laser. The output light of the modulated grating Y laser passes through a splitter with a splitting ratio of 1:99. 99% of the output light enters the optical isolator and then enters the user application optical path; 1% of the output light enters the photoelectric conversion circuit to convert the feedback optical signal into a feedback electrical signal. The feedback electrical signal is input into the negative feedback amplifier circuit, and then controls the adjustable current source circuit to control the SOA current output to the modulated grating Y laser, thereby changing the output optical power.

[0044] in,

[0045] The optical isolator is used to prevent the return light in the user application from interfering with the photoelectric feedback system;

[0046] The main function of the photoelectric conversion circuit is to convert the feedback optical signal into an electrical signal;

[0047] The negative feedback amplifier circuit is used to reverse and amplify the feedback electrical signal. The reverse effect is that when the output optical power of the modulated grating Y laser decreases, the 1% feedback light decreases, and the corresponding feedback electrical signal decreases. At this time, the SOA current needs to be increased, and the adjustable current source circuit needs to be controlled to increase the output; the amplification effect is mainly to ensure that the fluctuation range of the feedback optical signal matches the input range of the adjustable current source circuit.

[0048] Based on the photoelectric feedback device proposed in the present invention, during the calibration and normal operation of the modulated grating Y laser, each time the user control module inputs the left current, right current, phase current, and GAIN current (gain current), the photoelectric feedback system automatically generates the corresponding SOA current. During the calibration process, the introduction of the photoelectric feedback device proposed in the present invention is equivalent to inputting a phase current, and simultaneously adjusting the phase current and SOA current for coordinated control, which can achieve accurate calibration of the phase current and SOA current together, thereby achieving accurate calibration of the output wavelength and optical power, without the need for the phase current and SOA current to cyclically approximate the calibration, thereby improving the calibration accuracy and reducing the calibration time. At the same time, in the negative feedback amplifier circuit, the present invention designs an adjustable potentiometer to adjust the negative feedback amplification factor, thereby adjusting the output optical power during calibration; in actual application, the left current, right current, phase current, and GAIN current are output according to the calibrated current, and the output optical power is automatically matched with the SOA current during calibration after being modulated by the photoelectric feedback system, thereby achieving the output wavelength and optical power during calibration.

[0049] like Figure 3 The figure shows the application circuit diagram of the photoelectric conversion circuit, negative feedback amplifier circuit, and adjustable current source circuit, which specifically includes:

[0050] Constant current source I3, capacitor C1, first resistor R1, second resistor R3, third resistor R4, fourth resistor R5, fifth resistor R6, sixth resistor R10, first operational amplifier X8, second operational amplifier X9, third operational amplifier X10, 2N3904 transistor Q1, light-emitting diode D1;

[0051] One end of the constant current source I3 is grounded, and the other end is connected to one end of the capacitor C1, one end of the first resistor R1, and the inverting input end of the first operational amplifier X8. The other end of the capacitor C1 and the other end of the first resistor R1 converge and are connected to the output end of the first operational amplifier X8 and the non-inverting input end of the second operational amplifier X9. The non-inverting input end of the first operational amplifier X8 is grounded. The inverting input end and output end of the second operational amplifier X9 are both connected to one end of the second resistor R3. The other end of the second resistor R3 is connected to the inverting input end of the third operational amplifier X10 and one end of the fifth resistor R6. A non-inverting input terminal of the third operational amplifier X10 is connected to one end of the third resistor R4 and one end of the fourth resistor R5. The other end of the third resistor R4 is connected to a power supply. The other end of the fourth resistor R5 is grounded. The other end of the fifth resistor R6 and the output terminal of the third operational amplifier X10 are both connected to the base of the 2N3904 transistor Q1. The collector of the 2N3904 transistor Q1 is connected to a power supply. The emitter of the 2N3904 transistor Q1 is connected to one end of the sixth resistor R10. The other end of the sixth resistor R10 is connected to the anode of the light-emitting diode D1. The cathode of the light-emitting diode D1 is grounded.

[0052] like Figure 3 The circuit diagram shown is applicable to the following situations: the output optical power of the tuned grating Y laser is 20mW, the initial calibration optical power calibration range is ±2mW, the SOA standard current is 110mA, and the adjustable range is ±20mA. The circuit uses a current source to simulate the photoelectric acquisition tube, and a photoelectric tube to simulate the laser. After being split by a 1:99 optical splitter, the optical signal entering the feedback system is 0.18mW to 0.22mW. After being converted by the 1A / W photoelectric tube, the current is 0.18mA to 0.22mA. Therefore, the range of the simulated current source is 0.18mA to 0.22mA. Figure 4 Shown are the simulation results.

[0053] The present invention also provides a method for tuning the wavelength of a tunable semiconductor laser based on photoelectric feedback. Based on the tunable semiconductor laser wavelength tuning system described above, the method specifically includes:

[0054] S1, the user control module inputs left current, right current, phase current, and gain current to the modulated grating Y laser;

[0055] S2. In the modulated grating Y laser, the left and right sampled gratings are used as comb gratings. The two comb gratings form a vernier effect, so that the multimode interference coupler returns a reflection peak of a specific wavelength after superposition. The input gain control module performs longitudinal mode screening, the phase adjustment module realizes longitudinal mode shift, and broadens the spectral range tuned under each longitudinal mode. The SOA semiconductor amplifier performs optical power compensation and outputs optical power within a set range.

[0056] S3, the output light of the modulated grating Y laser passes through the optical splitter, the splitting ratio of the optical splitter is 1:99, and 99% of the output light enters the optical isolator and then enters the user application optical path;

[0057] S3, 1% of the output light enters the photoelectric conversion circuit to convert the feedback light signal into a feedback electrical signal, and the feedback electrical signal is input into the negative feedback amplifier circuit;

[0058] S4, the negative feedback amplifier circuit reverses and amplifies the feedback electrical signal;

[0059] Reverse: When the output optical power of the modulated grating Y laser decreases, the 1% feedback light decreases, and the corresponding feedback electrical signal decreases. At this time, the SOA current is increased to control the adjustable current source circuit to increase the output;

[0060] Amplification: The fluctuation range of the feedback optical signal is closely matched to the input range of the adjustable current source circuit;

[0061] S5. The feedback electrical signal output by the negative feedback amplifier circuit controls the adjustable current source circuit to control the SOA current output to the modulated grating Y laser, thereby changing the output optical power.

[0062] The present invention uses optoelectronic data to collect the output optical power and feeds it back to the SOA current for automatic matching, thereby achieving coordinated optical power tuning. The optoelectronic feedback device is used to adjust the output optical power. This system can achieve precise wavelength and optical power calibration, particularly during the calibration of a tuned grating Y laser. Furthermore, the calibration time is reduced from cyclic successive approximation calibration to a single calibration, achieving precise wavelength and optical power, thus improving calibration efficiency.

[0063] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, apparatus, article, or method comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, apparatus, article, or method. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, apparatus, article, or method comprising the element.

[0064] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A tunable semiconductor laser wavelength tuning system based on photoelectric feedback, characterized in that: It includes a user control module, a modulated grating Y laser, a photoelectric feedback device, and a user application optical path, wherein the user control module is connected to the modulated grating Y laser, the modulated grating Y laser is connected to the photoelectric feedback device, and the photoelectric feedback device is connected to the user application optical path; The photoelectric feedback device includes an optical splitter, an optical isolator, a photoelectric conversion circuit, a negative feedback amplifier circuit, and an adjustable current source circuit. The optical splitter and the adjustable current source circuit are both connected to the modulated grating Y laser. The optical splitter is also connected to the optical isolator and the photoelectric conversion circuit. The optical isolator is connected to the user application optical path. The photoelectric conversion circuit is connected to the negative feedback amplifier circuit, and the negative feedback amplifier circuit is connected to the adjustable current source circuit. The user control module inputs left current, right current, phase current, and gain current to the modulated grating Y laser. The output light of the modulated grating Y laser passes through a spectrometer. According to the splitting ratio of the spectrometer, a part of the output light enters the optical isolator and then enters the user application optical path, and the other part of the output light enters the photoelectric conversion circuit to convert the feedback optical signal into a feedback electrical signal. The feedback electrical signal is input into the negative feedback amplifier circuit, and then controls the adjustable current source circuit to control the SOA current output to the modulated grating Y laser, thereby changing the output optical power.

2. The tunable semiconductor laser wavelength tuning system based on photoelectric feedback according to claim 1, characterized in that: The photoelectric conversion circuit, negative feedback amplifier circuit, and adjustable current source circuit specifically include: Constant current source I3, capacitor C1, first resistor R1, second resistor R3, third resistor R4, fourth resistor R5, fifth resistor R6, sixth resistor R10, first operational amplifier X8, second operational amplifier X9, third operational amplifier X10, 2N3904 transistor Q1, light-emitting diode D1; One end of the constant current source I3 is grounded, and the other end is connected to one end of the capacitor C1, one end of the first resistor R1, and the inverting input end of the first operational amplifier X8. The other end of the capacitor C1 and the other end of the first resistor R1 converge and are connected to the output end of the first operational amplifier X8 and the non-inverting input end of the second operational amplifier X9. The non-inverting input end of the first operational amplifier X8 is grounded. The inverting input end and output end of the second operational amplifier X9 are both connected to one end of the second resistor R3. The other end of the second resistor R3 is connected to the inverting input end of the third operational amplifier X10 and one end of the fifth resistor R6. A non-inverting input terminal of the third operational amplifier X10 is connected to one end of the third resistor R4 and one end of the fourth resistor R5. The other end of the third resistor R4 is connected to a power supply. The other end of the fourth resistor R5 is grounded. The other end of the fifth resistor R6 and the output terminal of the third operational amplifier X10 are both connected to the base of the 2N3904 transistor Q1. The collector of the 2N3904 transistor Q1 is connected to a power supply. The emitter of the 2N3904 transistor Q1 is connected to one end of the sixth resistor R10. The other end of the sixth resistor R10 is connected to the anode of the light-emitting diode D1. The cathode of the light-emitting diode D1 is grounded.

3. The tunable semiconductor laser wavelength tuning system based on photoelectric feedback according to claim 2, characterized in that: The optical splitter is a 1x2 optical splitter with a splitting ratio of 1:

99. 99% of the outgoing light enters the optical isolator, and 1% of the outgoing light enters the photoelectric conversion circuit.

4. The tunable semiconductor laser wavelength tuning system based on photoelectric feedback according to claim 3, characterized in that: In the photoelectric feedback device, The optical isolator is used to prevent the return light in the user application from interfering with the photoelectric feedback system; The negative feedback amplifier circuit is used to reverse and amplify the feedback electrical signal. The reverse effect is that when the output optical power of the modulated grating Y laser decreases, the 1% feedback light decreases, and the corresponding feedback electrical signal decreases. At this time, the SOA current needs to be increased, and the adjustable current source circuit needs to be controlled to increase the output; the amplification effect is that the fluctuation range of the feedback optical signal is largely matched with the input range of the adjustable current source circuit.

5. The tunable semiconductor laser wavelength tuning system based on photoelectric feedback according to claim 4, characterized in that: The modulated grating Y laser includes a left sampled grating, a right sampled grating, a multimode interference coupler, a phase adjustment module, a gain control module, and an SOA semiconductor optical amplifier. The left sampled grating and the right sampled grating are both connected to the multimode interference coupler, and the multimode interference coupler is connected to the phase adjustment module. The phase adjustment module, the gain control module, and the SOA semiconductor optical amplifier are connected in sequence. The left sampled grating, right sampled grating, phase adjustment module, gain control module, and SOA semiconductor optical amplifier are all driven by constant current. The left sampled grating and right sampled grating serve as reflectors and are two comb gratings with multiple reflection peaks. The two comb gratings form a vernier effect, so that the multimode interference coupler returns a reflection peak of a specific wavelength after superposition, and then inputs it into the gain control module for longitudinal mode screening. The phase adjustment module is used to achieve longitudinal mode movement and broaden the spectral range tuned under each longitudinal mode. The SOA semiconductor amplifier is used for optical power compensation to ensure that the optical power output within the set range is within the tuning range.

6. A method for wavelength tuning of a tunable semiconductor laser based on photoelectric feedback, characterized in that: Based on the tunable semiconductor laser wavelength tuning system according to claim 5, the method specifically comprises: S1, the user control module inputs left current, right current, phase current, and gain current to the modulated grating Y laser; S2. In the modulated grating Y laser, the left and right sampled gratings are used as comb gratings. The two comb gratings form a vernier effect, so that the multimode interference coupler returns a reflection peak of a specific wavelength after superposition. The input gain control module performs longitudinal mode screening, the phase adjustment module realizes longitudinal mode shift, and broadens the spectral range tuned under each longitudinal mode. The SOA semiconductor amplifier performs optical power compensation and outputs optical power within a set range. S3, the output light of the modulated grating Y laser passes through the optical splitter, the splitting ratio of the optical splitter is 1:99, and 99% of the output light enters the optical isolator and then enters the user application optical path; S3, 1% of the output light enters the photoelectric conversion circuit to convert the feedback light signal into a feedback electrical signal, and the feedback electrical signal is input into the negative feedback amplifier circuit; S4, the negative feedback amplifier circuit reverses and amplifies the feedback electrical signal; Reverse: When the output optical power of the modulated grating Y laser decreases, the 1% feedback light decreases, and the corresponding feedback electrical signal decreases. At this time, the SOA current is increased to control the adjustable current source circuit to increase the output; Amplification: The fluctuation range of the feedback optical signal is closely matched to the input range of the adjustable current source circuit; S5. The feedback electrical signal output by the negative feedback amplifier circuit controls the adjustable current source circuit to control the SOA current output to the modulated grating Y laser, thereby changing the output optical power.

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