Data transmission apparatus and data transmission method based on cpo chip

Abstract

The application discloses a data transmission device and method based on a CPO chip. The data transmission device comprises an electric chip, an optical receiver and at least an even number of lasers. The optical receiver is in communication connection with the electric chip. The at least even number of lasers are arranged in pairs. Each pair comprises a first laser and a second laser. The laser beams emitted by the first laser and the second laser in the same pair are arranged at a first included angle in space. The value of the first included angle satisfies a constructive interference condition, so that the light intensity of the laser beams emitted by the first laser and the second laser in the same pair is enhanced. The laser beams emitted by the first laser and the second laser are in constructive interference, so that the laser beams entering the optical receiver are coherently enhanced. The total light intensity is greater than the sum of the light intensities of the two laser beams, thereby improving the output light power attenuation phenomenon of a single laser caused by various factors.

Description

Technical Field

[0001] This application relates to the field of optoelectronic integration technology, and in particular to a data transmission device and data transmission method based on a CPO chip. Background Technology

[0002] Co-packaged optics (CPO) is an advanced optoelectronic integration technology. Its core lies in integrating an optical engine with a switching chip or computing chip onto the same substrate using advanced packaging technologies (such as 2.5D / 3D packaging). This significantly shortens the electrical signal transmission distance, reduces power consumption, and increases bandwidth density. The optical chip uses a laser to emit optical signals, replacing traditional copper wire electrical signal transmission, enabling high-speed data communication between chips or between a chip and external devices. As the core active optical device, the stability of the laser's output optical power directly determines the quality and reliability of the entire data transmission link.

[0003] However, prolonged continuous operation of a laser will cause the output optical power to gradually decrease (i.e., the light source weakens) due to factors such as increased temperature, material aging, and drift of the driving current. When the light intensity drops below a certain threshold, the light flux received by the receiver is insufficient, resulting in a decrease in the signal-to-noise ratio (SNR) of the electrical signal after photoelectric conversion, which in turn leads to signal transmission distortion, increased bit error rate (BER), and even communication link interruption.

[0004] It should be noted that the above introduction to the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of this application and facilitating understanding by those skilled in the art. It should not be assumed that these technical solutions are known to those skilled in the art simply because they have been described in the background section of this application. Summary of the Invention

[0005] The purpose of this application is to provide a data transmission device and data transmission method based on a CPO chip. This application utilizes the constructive interference formed by the laser beams emitted by the first laser and the second laser to coherently enhance the laser beam entering the optical receiver, so that the total light intensity is greater than the sum of the light intensities of the two laser beams, thereby improving the phenomenon of output light power attenuation caused by various factors of a single laser.

[0006] This application discloses a data transmission device based on a CPO chip. The data transmission device includes an electrical chip, an optical receiver, and at least an even number of lasers. The electrical chip is used for data signal processing and control. The optical receiver is communicatively connected to the electrical chip and is used to convert the received optical signal into an electrical signal and output it to the electrical chip. The at least an even number of lasers are arranged in pairs and groups. Each group includes a first laser and a second laser. The laser beams emitted by the first laser and the second laser in the same group are arranged in space at a first angle. The value of the first angle satisfies the constructive interference condition, so as to enhance the light intensity of the laser beams emitted by the first laser and the second laser in the same group.

[0007] Optionally, the data transmission device further includes a light monitoring unit for monitoring the light intensity value of the laser beam emitted by the first laser in each group; when the light intensity value of the laser beam emitted by the first laser is lower than a preset light intensity threshold, the electronic chip controls the second laser in the same group to start.

[0008] Optionally, the light monitoring unit is disposed within the electrical chip; the preset light intensity threshold is the minimum light flux required by the light receiver.

[0009] Optionally, the data transmission device further includes a connector, wherein a first optical waveguide channel and a second optical waveguide channel are disposed therein. The first optical waveguide channel is used to receive the laser beam emitted by the first laser in the same group, and the second optical waveguide channel is used to receive the laser beam emitted by the second laser in the same group. The first optical waveguide channel and the second optical waveguide channel are disposed at the first included angle, and the end of the first optical waveguide channel near the optical receiver and the end of the second optical waveguide channel near the optical receiver converge to the same output port.

[0010] Optionally, the electrical chip is equipped with a timer, which has a preset working duration threshold. When the cumulative working duration of the first laser reaches the working duration threshold, the electrical chip controls the second laser in the same group to start.

[0011] Optionally, prisms are respectively provided on the side of the first optical waveguide channel near the first laser and on the side of the second optical waveguide channel near the second laser. The prisms are used to collimate the laser beam emitted by the first laser and the laser beam emitted by the second laser, respectively.

[0012] Optionally, the first laser in the same group is the main laser, and the second laser is the auxiliary laser; when the light intensity of the laser beam emitted by the main laser is lower than a preset light intensity threshold or the cumulative working time reaches the working time threshold, the auxiliary laser is activated.

[0013] Optionally, the optical receiver includes a photodetector and a transimpedance amplifier, and the electrical chip includes a switching chip or a computing chip.

[0014] Optionally, the constructive interference condition includes the optical path difference between the laser beam emitted by the first laser and the laser beam emitted by the second laser being an integer multiple of the wavelength or the phase difference being an integer multiple of 2π.

[0015] This application also discloses a data transmission method for a data transmission device, wherein the data transmission device is as described above regarding the data transmission device based on a CPO chip, and the data transmission method includes the following steps: Start the first laser in each group; Monitor the cumulative operating time or the intensity of the emitted laser beam of each of the first lasers; Compare the monitored cumulative working time with the working time threshold or compare the monitored light intensity value with the preset light intensity threshold; When the monitored cumulative working time is greater than or equal to the working time threshold, or when the monitored light intensity value is lower than the preset light intensity threshold, the second laser in the same group is started to work.

[0016] This application addresses the issue of single lasers experiencing output power attenuation by grouping multiple lasers into pairs. When one laser experiences output power attenuation, the other laser is simultaneously activated, causing constructive interference between their emitted beams. This coherently enhances the beam entering the optical receiver, resulting in a total light intensity greater than the sum of the two beams. This mitigates the output power attenuation caused by various factors in a single laser. Furthermore, this application utilizes mutual compensation between the two lasers in each group. When one laser in the same group experiences power attenuation, the other laser can compensate, preventing a drop in the signal-to-noise ratio (SNR) of the photoelectric converted signal due to the light intensity reaching the optical receiver falling below a threshold. This avoids signal transmission distortion, increased bit error rate (BER), and even communication link interruptions, thereby improving the signal transmission stability of the data transmission device and enhancing product quality. Attached Figure Description

[0017] The accompanying drawings, which form part of the specification, are used to provide a further understanding of the embodiments of this application and illustrate the implementation methods of this application, together with the textual description, to explain the principles of this application. Obviously, the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without creative effort. In the drawings: Figure 1 This is a schematic diagram of a data transmission device based on a CPO chip according to an embodiment of this application; Figure 2 This is a schematic diagram of the steps of the data transmission method of the data transmission apparatus of this application; Figure 3 This is a schematic diagram of a data transmission device based on a CPO chip according to another embodiment of this application; Figure 4 This is a schematic diagram of the steps of a data transmission method of a data transmission apparatus according to another embodiment of this application.

[0018] Among them, 100 is a data transmission device; 110 is an electrical chip; 120 is an optical receiver; 130 is a first laser; 131 is a second laser; 140 is an optical monitoring unit; 141 is a timer; 150 is a connector; 151 is a first optical waveguide channel; and 152 is a first optical waveguide channel. Detailed Implementation

[0019] It should be understood that the terminology, specific structural and functional details used herein are merely for describing particular embodiments and are representative. However, this application can be implemented in many alternative forms and should not be construed as being limited to the embodiments set forth herein. It should be emphasized that the term "comprising / including" as used herein refers to the presence of a feature, unit, step, or component, but does not exclude the presence or addition of one or more other features, units, steps, or components.

[0020] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating relative importance or implying the number of technical features indicated. Therefore, unless otherwise stated, a feature specified as "first" or "second" may explicitly or implicitly include one or more of that feature; "multiple" means two or more. Furthermore, terms such as "upper," "lower," "left," "right," "vertical," and "horizontal," indicating orientation or positional relationships, are based on the orientation or relative positional relationships shown in the accompanying drawings and are only for the purpose of simplifying the description of this application, not indicating that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting this application. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0021] The present application will now be described in detail with reference to the accompanying drawings and optional embodiments.

[0022] Figure 1 This is a schematic diagram of a data transmission device based on a CPO chip according to an embodiment of this application. See also... Figure 1 As shown, this application discloses a data transmission device 100 based on a CPO chip. The data transmission device 100 includes an electrical chip 110, an optical receiver 120, and at least an even number of lasers. The electrical chip 110 is used for data signal processing and control. The optical receiver 120 is communicatively connected to the electrical chip 110 and is used to convert the received optical signal into an electrical signal and output it to the electrical chip 110. The at least an even number of lasers are arranged in pairs and groups. Each group includes a first laser 130 and a second laser 131. The laser beams emitted by the first laser 130 and the second laser 131 in the same group are arranged in space at a first angle θ. The value of the first angle θ satisfies the constructive interference condition, so as to enhance the light intensity of the laser beams emitted by the first laser 130 and the second laser 131 in the same group.

[0023] This application arranges multiple lasers in pairs, with two lasers in each pair. When one laser experiences output power attenuation, the other laser is simultaneously activated, causing constructive interference between their emitted beams. This coherently enhances the laser beam entering the optical receiver 120, resulting in a total light intensity greater than the sum of the two laser beam intensities. This improves the output power attenuation phenomenon caused by various factors in a single laser. Furthermore, this application utilizes mutual compensation between the two lasers in each pair. When one laser in the same pair experiences power attenuation, the other laser can compensate, preventing a decrease in the signal-to-noise ratio (SNR) of the photoelectric converted signal due to the light intensity reaching the optical receiver 120 falling below a threshold. This avoids problems such as signal transmission distortion, increased bit error rate (BER), and even communication link interruption, thereby improving the signal transmission stability of the data transmission device 100 and enhancing product quality.

[0024] It is understandable that the laser beams emitted by the first laser 130 and the second laser 131 in the same group converge at the receiving position of the optical receiver 120 and enter the optical receiver 120. The converged laser beams of the two satisfy constructive interference, so that the laser beam with enhanced light intensity after convergence enters the optical receiver 120.

[0025] In one embodiment, in a normal working environment, only one of the first laser 130 and the second laser 131 in the same group is working. The working laser is the main laser, and the other is the auxiliary laser.

[0026] The normal operating environment includes situations where the power of the laser beam emitted by the laser does not attenuate, the ambient temperature of the laser is low, the laser does not age, the driving circuit corresponding to the laser does not drift, or the optical path between the laser and the optical receiver 120 does not shift.

[0027] This application uses the first laser 130 as the main laser and the second laser 131 as the auxiliary laser in the same group as an example for illustration.

[0028] In one embodiment, the auxiliary laser is activated when the intensity of the laser beam emitted by the main laser is lower than a preset intensity threshold or the cumulative working time reaches the working time threshold.

[0029] The main factors contributing to laser power attenuation include: Laser emission generates heat, and prolonged high-power operation leads to increased threshold current, reduced slope efficiency, or decreased output power. Laser aging effects occur, such as a decrease in internal quantum efficiency in the active region of the semiconductor over time. The accuracy of the laser's drive current drifts with temperature and time, causing the actual injected current to deviate from the set value. Optical path misalignment between the laser and the optical receiver 120 results in lower actual received light intensity. For example, packaging stress or thermal expansion can cause micrometer-level misalignment in the coupling alignment between the laser and the optical waveguide or fiber, reducing coupling efficiency.

[0030] In exemplary technologies, the drive current can be adjusted based on the intensity of the laser beam emitted by the laser, thereby maintaining a stable output optical power. However, increasing the drive current over a long period can actually accelerate laser aging. When the laser is nearing the end of its lifespan or experiences a sudden failure, even a significant increase in the drive current may not be enough to maintain a constant output optical power, and the lost coupling efficiency cannot be recovered. Regarding temperature, semiconductor coolers can typically be used to maintain the laser's operating temperature at an optimal value, mitigating thermal degradation. However, this also increases system complexity and cannot address the permanent decrease in optical intensity caused by aging when the laser is nearing the end of its lifespan or experiences a sudden failure.

[0031] In this embodiment, the auxiliary laser compensates for the attenuation of the laser beam caused by the attenuation of the main laser. For example, when the main laser attenuates to 60% of its rated power, the auxiliary laser emits at the same 60% power. At this time, through coherent interference of the light beams, the optical receiver 120 can receive the laser beam at its rated power, thereby improving the signal transmission distortion, increased bit error rate (BER), and even communication link interruption caused by laser attenuation.

[0032] In one embodiment, the electrical chip 110 includes a switching chip or a computing chip. The computing chip includes a SerDes / PHY control unit, which converts the parallel digital signals processed internally by the electrical chip 110 into serial analog / digital mixed signals suitable for transmission over high-speed channels. Specifically, the CPO includes two signals: a high-speed modulation signal for the modulator to carry data; and a DC bias / control signal for interference control.

[0033] The optical receiver 120 includes a photodetector and a transimpedance amplifier. The photodetector receives the laser beams emitted by the first laser 130 and the second laser 131, converting the optical signal into an electrical signal based on the photoelectric effect. Since the current of the electrical signal output by the photodetector is very weak, typically only tens of μA to a few mA, it cannot directly drive subsequent circuits. The transimpedance amplifier amplifies the electrical signal to a sufficient amplitude, typically reaching hundreds of mV to V levels.

[0034] The constructive interference condition includes that the laser beams of the first laser 130 and the second laser 131 satisfy a phase difference that is an integer multiple of 2π or an optical path difference that is an integer multiple of the wavelength.

[0035] In one embodiment, the data transmission device 100 further includes a light monitoring unit 140 for monitoring the light intensity value of the laser beam emitted by the first laser 130 in each group. When the light intensity value of the laser beam emitted by the first laser 130 is lower than a preset light intensity threshold, the electronic chip 110 controls the second laser 131 in the same group to start.

[0036] The optical monitoring unit 140 can be a splitter / tap and a photodetector (PD). The splitter extracts a light sample and separates a small portion of the light (e.g., 1% to 5%) from the main optical path, which is then transmitted to the PD. The PD converts this light into a current signal proportional to the optical power.

[0037] In this embodiment, a light monitoring unit 140 is used to monitor the light intensity value emitted by the main laser. The electrical chip 110 compares the monitored light intensity value with a preset light intensity threshold. If the light intensity emitted by the first laser 130 is lower than the threshold, the electrical chip 110 immediately activates the second laser 131 belonging to the same group as the first laser 130. The auxiliary laser emitted by the second laser 131 and the main laser of the first laser 130 satisfy the interference angle condition in space. The two beams undergo constructive interference in the transmission path, and the combined light intensity is significantly enhanced when they reach the receiver. The receiver converts the enhanced combined light signal into an electrical signal and outputs it to the electrical chip 110 for processing.

[0038] The optical monitoring unit 140 is disposed within the electrical chip 110. The preset optical intensity threshold is the minimum optical flux required by the optical receiver 120, also known as the minimum received optical power of the optical receiver, which can be obtained through link budget calculation.

[0039] Figure 2 This is a schematic diagram of the data transmission method of the data transmission apparatus of this application, see below. Figure 2 As shown, based on the aforementioned data transmission device 100, the corresponding data transmission method includes the following steps: S101: Start the first laser in each group; S102: Monitor the light intensity value of the laser beam emitted by each of the first lasers; S103: Compare the monitored light intensity value with the preset light intensity threshold; S104: When the detected light intensity value is lower than the preset light intensity threshold, start the second laser in the same group.

[0040] In step S110, the first laser 130 and the second laser 131 in the same group can also be driven as main lasers, so that the first laser 130 and the second laser 131 in the same group work alternately.

[0041] When one of the lasers experiences optical power attenuation, it is identified as the auxiliary laser and the main laser operates independently. When the optical intensity of the main laser subsequently becomes low, the auxiliary laser is activated to compensate.

[0042] Of course, another control strategy could be for the two lasers to operate alternately. During the first period, the first laser 130 and the second laser 131 in the same group operate alternately, and during the second period, they operate together at low power. For example, during the first period, the first laser 130 and the second laser 131 are driven alternately at constant power, and during the second period, the first laser 130 and the second laser 131 each operate at 60% of their constant power. Under this control strategy, the triggering condition for the second period can be limited to a temperature rise or the cumulative operating time reaching a threshold.

[0043] Figure 3 This is a schematic diagram of a data transmission device based on a CPO chip according to another embodiment of this application. See also... Figure 3 As shown, the data transmission device 100 further includes a connector 150, in which a first optical waveguide channel 151 and a second optical waveguide channel 152 are provided. The first optical waveguide channel 151 is used to receive the laser beam emitted by the first laser 130 in the same group, and the second optical waveguide channel 152 is used to receive the laser beam emitted by the second laser 131 in the same group.

[0044] The first optical waveguide channel 151 and the second optical waveguide channel 152 are set at the first included angle θ, and the end of the first optical waveguide channel 151 near the optical receiver 120 and the end of the second optical waveguide channel 152 near the optical receiver 120 converge to the same output port.

[0045] Compared to the previous embodiment, this embodiment additionally includes a connector 150. The connector 150 contains a first optical waveguide channel 151 and a second optical waveguide channel 152. The input ends of the two channels receive the output laser beams from the main laser and the auxiliary laser, respectively, and converge at the output end to form a single emission port. The geometric axes along the length directions of the two channels are spatially set at a first angle θ. This first angle θ satisfies the constructive interference condition, i.e., the phase difference is an integer multiple of 2π or the optical path difference is an integer multiple of the wavelength.

[0046] In one embodiment, the electrical chip 110 is provided with a timer 141, which is preset with a working duration threshold. When the cumulative working duration of the first laser 130 reaches the working duration threshold, the electrical chip 110 controls the second laser 131 in the same group to start.

[0047] In this embodiment, the working time threshold (Tdelay) inside the timer 141 was obtained through previous experimental testing. It corresponds to the average working time required for the output optical power of the laser of this test model to decay to the critical threshold under rated operating conditions. Taking the first laser 130 as the main laser as an example, when the accumulated working time of the main laser is reached, the electrical chip 110 controls the auxiliary laser (i.e., the second laser 131 in the same group). The beams of the main laser and the auxiliary laser undergo constructive interference at the output end through the first optical waveguide channel 151 and the second optical waveguide channel 152 of the connector 150, under the condition of satisfying the interference angle. After the combined light intensity is enhanced, it is transmitted to the optical receiver 120. The optical receiver 120 converts the enhanced combined light signal into an electrical signal for output.

[0048] It is understood that the timer 141 can also be used in the previous embodiment, in conjunction with the light monitoring unit 140. Of course, the light monitoring unit 140 in the previous embodiment can also be used in this embodiment.

[0049] In one embodiment, prisms are respectively provided on the side of the first optical waveguide channel 151 near the first laser 130 and on the side of the second optical waveguide channel 152 near the second laser 131. The prisms are used to collimate the laser beam emitted by the first laser 130 and the laser beam emitted by the second laser 131, respectively.

[0050] Figure 4 This is a schematic diagram illustrating the steps of a data transmission method using a data transmission apparatus according to another embodiment of this application. See also... Figure 4 As shown, the data transmission device is as described above, and the data transmission method includes the following steps: S111: Start the first laser in each group; S112: Monitor the cumulative operating time of each of the first lasers; S113: Compare the monitored cumulative working time with the working time threshold; S114: When the monitored cumulative working time is greater than or equal to the working time threshold, start the second laser in the same group to work.

[0051] In this embodiment, the first laser 130 serves as the main laser. A timer 141 continuously monitors the operating time of the main laser. When the accumulated operating time of the main laser reaches a certain threshold, the electrical chip 110 controls the auxiliary laser (i.e., the second laser 131 in the same group). The beams from the main laser and the auxiliary laser, via the first optical waveguide channel 151 and the second optical waveguide channel 152 of the connector 150, undergo constructive interference at the output end under the condition of satisfying the interference angle. The combined beam intensity is enhanced and then transmitted to the optical receiver 120. The optical receiver 120 converts the enhanced combined beam signal into an electrical signal for output.

[0052] Of course, this embodiment can also employ a control strategy that includes alternating operation of the two lasers. During the first period, the first laser 130 and the second laser 131 in the same group operate alternately, and during the second period, they operate together at low power. For example, during the first period, the first laser 130 and the second laser 131 are driven alternately at constant power, and during the second period, the first laser 130 and the second laser 131 operate at 60% of their constant power. Under this control strategy, the triggering condition for the second period can be limited to a temperature rise or the cumulative operating time reaching a threshold. The timer 141 monitors the cumulative operating time of both lasers, and when the cumulative operating time of one of them reaches the threshold, both lasers are started simultaneously.

[0053] It should be noted that the inventive concept of this application can form many embodiments, but due to the limited space of the application documents, they cannot all be listed. Therefore, without conflict, the embodiments described above or the technical features can be arbitrarily combined to form new embodiments. After the embodiments or technical features are combined, the original technical effect will be enhanced.

[0054] The above description, in conjunction with specific optional embodiments, provides a further detailed explanation of this application and should not be construed as limiting the specific implementation of this application to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of this application, and all such modifications or substitutions should be considered within the scope of protection of this application.

Claims

1. A data transmission device based on a CPO chip, characterized in that, include: Electrical chips are used for data signal processing and control. An optical receiver, which is communicatively connected to the electrical chip, is used to convert the received optical signal into an electrical signal and output it to the electrical chip. At least an even number of lasers are arranged in pairs, each pair containing a first laser and a second laser. The laser beams emitted by the first laser and the second laser in the same pair are arranged in space at a first angle. The value of the first angle satisfies the constructive interference condition, so as to enhance the light intensity of the laser beams emitted by the first laser and the second laser in the same pair.

2. The data transmission device according to claim 1, characterized in that, The data transmission device further includes an optical monitoring unit for monitoring the light intensity of the laser beam emitted by the first laser in each group; When the light intensity of the laser beam emitted by the first laser is lower than a preset light intensity threshold, the electronic chip controls the second laser in the same group to start.

3. The data transmission device according to claim 2, characterized in that, The optical monitoring unit is disposed within the electrical chip; The preset light intensity threshold is the minimum light flux required by the optical receiver.

4. The data transmission device according to claim 1, characterized in that, The data transmission device further includes a connector, which has a first optical waveguide channel and a second optical waveguide channel. The first optical waveguide channel is used to receive the laser beam emitted by the first laser in the same group, and the second optical waveguide channel is used to receive the laser beam emitted by the second laser in the same group. The first optical waveguide channel and the second optical waveguide channel are arranged at the first included angle, and the end of the first optical waveguide channel near the optical receiver and the end of the second optical waveguide channel near the optical receiver converge to the same output port.

5. The data transmission device according to claim 4, characterized in that, The electrical chip is equipped with a timer, which has a preset working duration threshold. When the cumulative working duration of the first laser reaches the working duration threshold, the electrical chip controls the second laser in the same group to start.

6. The data transmission device according to claim 4, characterized in that, A prism is provided on the side of the first optical waveguide channel near the first laser and on the side of the second optical waveguide channel near the second laser, respectively. The prism is used to collimate the laser beam emitted by the first laser and the laser beam emitted by the second laser, respectively.

7. The data transmission apparatus according to claim 2 or 4, characterized in that, In the same group, the first laser is the main laser, and the second laser is the auxiliary laser; The auxiliary laser is activated when the intensity of the laser beam emitted by the main laser is lower than the preset intensity threshold or the cumulative working time reaches the working time threshold.

8. The data transmission device according to claim 1, characterized in that, The optical receiver includes a photodetector and a transimpedance amplifier, and the electrical chip includes a switching chip or a computing chip.

9. The data transmission device according to claim 1, characterized in that, The constructive interference condition includes the optical path difference between the laser beam emitted by the first laser and the laser beam emitted by the second laser being an integer multiple of the wavelength or the phase difference being an integer multiple of 2π.

10. A data transmission method of a data transmission device, characterized in that, The data transmission device is a data transmission device based on a CPO chip as described in any one of claims 1 to 9, and the data transmission method includes the following steps: Start the first laser in each group; Monitor the cumulative operating time or the intensity of the emitted laser beam of each of the first lasers; Compare the monitored cumulative working time with the working time threshold or compare the monitored light intensity value with the preset light intensity threshold; When the monitored cumulative working time is greater than or equal to the working time threshold, or when the monitored light intensity value is lower than the preset light intensity threshold, the second laser in the same group is started to work.

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