A wavelength stabilization control method of a semiconductor laser

Abstract

The application relates to the technical field of semiconductor laser control, and discloses a wavelength stabilization control method of a semiconductor laser, which comprises the following steps: constructing an equivalent heat transfer model of a multi-section semiconductor laser; monitoring the radio frequency data stream duty cycle of a gain section, switching the injection path of a low-frequency pilot signal to extract a global equivalent low-frequency thermal resistance, updating a time-varying low-frequency physical RC node parameter set; combining the transient heat power of the gain section and the equivalent heat transfer model to deduce full-frequency section junction temperature observation data, and decomposing the full-frequency section junction temperature observation data into an extremely low-frequency direct current component, a medium-low-frequency fluctuation component and an extremely transient high-frequency fluctuation component; driving a thermoelectric refrigeration component according to the extremely low-frequency direct current component; generating a medium-low-frequency feedback compensation current according to the medium-low-frequency fluctuation component, combining the extremely transient high-frequency fluctuation component to generate a feedforward compensation current; and injecting the medium-low-frequency feedback compensation current and the feedforward compensation current into a grating section after being combined. The application realizes multi-frequency section decoupling control and improves wavelength stability.

Description

Technical Field

[0001] This invention relates to the field of semiconductor laser control technology, specifically to a method for wavelength stabilization control of semiconductor lasers. Background Technology

[0002] As the core light source in optical communication and optical sensing systems, the stability of the output wavelength of semiconductor lasers directly affects the overall performance of the system. In actual operation, the heat generation power inside the laser will undergo transient changes with the high-speed injection current, resulting in fluctuations in the junction temperature of the active region and causing wavelength drift.

[0003] Existing wavelength stabilization schemes typically rely on external thermoelectric cooling components for global temperature regulation. However, due to the thermal inertia of the physical structure, the response bandwidth of these components is extremely low, making it impossible to suppress transient high-frequency junction temperature fluctuations caused by high-speed communication data streams. To compensate for the hysteresis of the actuator, some existing technologies have introduced current compensation mechanisms based on internal fixed equivalent thermal models, using predicted junction temperature changes to generate compensation current. However, as the laser operates for extended periods, the interface between its epitaxial layer and heat sink degrades, causing drift in the actual internal thermal resistance and thermal capacity parameters. The fixed heat transfer model cannot dynamically track and update these parameters, resulting in a gradual increase in junction temperature estimation errors over time, ultimately leading to wavelength compensation failure. Furthermore, conventional electrical compensation strategies typically superimpose the compensation current directly onto the laser's gain band. This operation directly alters the carrier density in the active region while tuning the wavelength, inevitably interfering with the light emission process in the gain band and generating severe amplitude modulation crosstalk, causing abnormal fluctuations in the output optical power when the laser is stabilizing its wavelength.

[0004] Therefore, this invention proposes a wavelength stabilization control method for semiconductor lasers to address the shortcomings of existing technologies. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a wavelength stabilization control method for semiconductor lasers, which solves the problems of wavelength compensation gradually failing due to the inability of the internal solidified heat transfer model to track device aging, and the tendency of conventional current compensation to directly inject into the gain segment to cause amplitude modulation crosstalk in the output optical power.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for wavelength stabilization control of a semiconductor laser, comprising the following steps:

[0007] An equivalent heat transfer model for a multi-segment semiconductor laser is constructed, the equivalent heat transfer model including a static high-frequency physical RC node parameter set and a time-varying low-frequency physical RC node parameter set;

[0008] Monitor the duty cycle of the RF data stream of the gain segment of the multi-segment semiconductor laser, extract the global equivalent low-frequency thermal resistance by switching the injection path of the low-frequency pilot signal, and update the set of time-varying low-frequency physical RC node parameters.

[0009] By combining the transient heating power of the gain band with the updated equivalent heat transfer model, the junction temperature observation data of the entire frequency band is deduced, and the junction temperature observation data of the entire frequency band is decomposed into extremely low frequency DC component, medium and low frequency fluctuation component and extremely transient high frequency fluctuation component.

[0010] The thermoelectric cooling component is driven according to the extremely low frequency DC component; a medium-low frequency feedback compensation current is generated according to the medium-low frequency fluctuation component, and a feedforward predistortion compensation current is generated in combination with the extremely transient high frequency fluctuation component; the medium-low frequency feedback compensation current and the feedforward predistortion compensation current are linearly synthesized and injected into the grating segment of the multi-segment semiconductor laser.

[0011] Preferably, the construction of the equivalent heat transfer model for the multi-segment semiconductor laser includes:

[0012] The epitaxial physical region of the multi-segment semiconductor laser is assigned fixed extreme transient thermal resistance and extreme transient thermal capacity according to the number of discretized layers to generate the static high-frequency physical RC node parameter set.

[0013] A comprehensive degradation factor is calculated based on the cumulative operating power-on time and historical temperature jump cycle number of the multi-segment semiconductor laser. The low-frequency thermal resistance and low-frequency thermal capacity of the heat sink packaging physical region are scaled using the comprehensive degradation factor to generate the time-varying low-frequency physical RC node parameter set.

[0014] The static high-frequency physical RC node parameter set and the time-varying low-frequency physical RC node parameter set are cascaded according to their physical spatial locations to construct a continuous thermal trapezoidal topology as the equivalent heat transfer model.

[0015] Preferably, after generating the equivalent heat transfer model, a step to prevent computational overflow is also included:

[0016] Detect whether the multi-segment semiconductor laser is in steady-state DC operating condition;

[0017] If the multi-segment semiconductor laser is detected to be in steady-state DC operation, when discretizing the equivalent heat transfer model, the complex frequency domain admittance terms corresponding to each heat capacity are forcibly set to zero, and the pure algebraic scalar cumulative values ​​of each thermal resistance are directly output to replace the calculus derivation calculation.

[0018] Preferably, the step of extracting the global equivalent low-frequency thermal resistance by switching the injection path of the low-frequency pilot signal includes:

[0019] The duty cycle of the radio frequency data stream is compared with a preset duty cycle threshold.

[0020] When the duty cycle of the radio frequency data stream is less than or equal to the duty cycle threshold, the low-frequency pilot signal is injected into the gain segment to extract the true low-frequency thermal resistance.

[0021] When the duty cycle of the radio frequency data stream is greater than the duty cycle threshold, the low-frequency pilot signal is switched and injected into the grating segment to extract the proxy low-frequency thermal resistance.

[0022] Preferably, the specific process of extracting the actual low-frequency thermal resistance and the proxy low-frequency thermal resistance includes:

[0023] When injecting a low-frequency pilot signal into the gain segment, a digital mask function synchronized with the main communication pulse is constructed. Equivalent time undersampling is triggered only during the period when the digital mask function outputs a high level. Discrete voltage samples are obtained and reconstructed into low-frequency AC voltage amplitude in the digital domain. The actual low-frequency thermal resistance is then obtained by dividing the product of the constant injected power and the absolute value of the junction voltage drop temperature coefficient.

[0024] When injecting a low-frequency pilot signal into the grating segment, continuous-time phase-locked sampling sequence extraction is performed on the voltage nodes at both ends of the grating segment, and the proxy low-frequency thermal resistance is extracted based on the thermal resistance calculation principle derived from Ohm's law.

[0025] Preferably, updating the time-varying low-frequency physical RC node parameter set includes:

[0026] During the communication frame gaps of the communication protocol, the actual low-frequency thermal resistance of the gain segment and the proxy low-frequency thermal resistance of the grating segment at the current absolute time node are synchronously obtained using hardware timestamps.

[0027] The real low-frequency thermal resistance acquired synchronously is divided by the proxy low-frequency thermal resistance to obtain the dynamic mapping coefficient, and the dynamic mapping coefficient is subjected to numerical range clamping processing.

[0028] When the low-frequency pilot signal is switched and injected into the grating segment, the real-time acquired proxy low-frequency thermal resistance is multiplied by the dynamic mapping coefficient after numerical interval clamping processing to obtain the global equivalent low-frequency thermal resistance. The drift of the global equivalent low-frequency thermal resistance is then reverse-mapped according to spatial weight to the last-order dynamic thermal resistance and dynamic thermal capacity in the time-varying low-frequency physical RC node parameter set.

[0029] Preferably, the step of combining the transient heating power of the gain band with the updated equivalent heat transfer model to extrapolate the junction temperature observation data across the entire frequency band includes:

[0030] The operating voltage, injection current, and output optical power of the gain band are synchronously acquired using a parallel sampling bus. The total electrical power is obtained by multiplying the operating voltage and injection current. The energy difference between the total electrical power and the output optical power is calculated to obtain the transient heating power.

[0031] The equivalent heat transfer model is converted into a state-space observer in the discrete time domain, and a regularization constant is applied to the diagonal elements when constructing the discrete state transition matrix for diagonal loading.

[0032] The transient heating power is used as the control input of the state-space observer, and the full-band junction temperature observation data is derived through discrete iterative calculation.

[0033] The full-band junction temperature observation data is fed in parallel into a digital filter bank with flat group delay characteristics. The full-band junction temperature observation data is orthogonally decomposed into an extremely low-frequency DC component, a mid-to-low-frequency fluctuation component, and an extremely transient high-frequency fluctuation component according to a preset cutoff frequency.

[0034] Preferably, the step of generating a low-frequency feedback compensation current based on the low-frequency fluctuation component includes:

[0035] The low- and mid-frequency fluctuation components are converted into basic wavelength compensation quantities by using a preset temperature-current wavelength tuning mapping table.

[0036] Calculate the first-order differential rate of change of the basic wavelength compensation amount within multiple consecutive discrete sampling periods, and perform moving average processing to obtain the transient rate of change;

[0037] When the absolute value of the transient rate of change exceeds the preset mode transition safety slope threshold, the output increment of the current cycle is truncated and clamped to the mode transition safety slope threshold, and the low-frequency feedback compensation current is output.

[0038] Preferably, the step of generating a feedforward predistortion compensation current by combining the extremely transient high-frequency fluctuation components includes:

[0039] The discretized dynamic parameters inside the equivalent heat transfer model are called, and the minimum mean square error approximation inverse operation based on the Tikhonov regularization factor is introduced to construct the thermodynamic inverse transfer function.

[0040] The transient high-frequency fluctuation component is mapped into a refractive index transient distortion by means of the thermodynamic inverse transfer function, and the refractive index transient distortion is converted into a thermal chirp cancellation amount based on the refractive index and carrier current plasma response mapping table.

[0041] The thermal chirp cancellation amount is subjected to high-pass digital filtering and mean zeroing processing to generate a feedforward predistortion compensation current.

[0042] Preferably, the step of linearly combining the low-frequency feedback compensation current and the feedforward predistortion compensation current and then injecting them into the grating segment of the multi-segment semiconductor laser includes:

[0043] Before performing linear synthesis, the low-frequency feedback compensation current and the feedforward predistortion compensation current are respectively sent to the digital delay line in the underlying computing architecture to compensate for the pipeline time difference between computing channels and achieve time series alignment.

[0044] The aligned low-frequency feedback compensation current and the feedforward predistortion compensation current are algebraically added to obtain a composite compensation current, which is then injected into the grating segment to isolate the modulation crosstalk on the output optical power of the gain segment.

[0045] This invention provides a method for wavelength stabilization control of a semiconductor laser. It has the following beneficial effects:

[0046] 1. This invention constructs an equivalent heat transfer model that includes static high-frequency and time-varying low-frequency parameters, and switches the injection path of the low-frequency pilot signal according to the duty cycle of the RF data stream in the gain segment, thereby extracting the low-frequency thermal resistance to update the model parameters in real time. This design can adapt to the test conditions of lasers under different communication conditions, compensate for the physical parameter drift caused by long-term aging of the device, eliminate the calculation error generated by the fixed parameter model over a long time, and improve the accuracy of system junction temperature observation.

[0047] 2. This invention decomposes the full-band junction temperature observation data derived from transient heating power into extremely low-frequency DC components, mid-to-low-frequency fluctuation components, and extremely transient high-frequency fluctuation components, which are then used to drive thermoelectric cooling components and generate feedback and feedforward compensation currents, respectively. This multi-band decoupling approach matches the control strategy with the physical response bandwidth of different actuators, solving the response hysteresis and regulation overshoot problems that easily occur when a single control loop faces broadband thermal disturbances, and improving the dynamic tracking capability of the wavelength control system.

[0048] 3. This invention combines the low-to-medium frequency feedback compensation current with the feedforward predistortion compensation current and then directionally injects it into the grating segment of a multi-segment semiconductor laser. Since the grating segment mainly utilizes changes in carrier concentration to alter the refractive index and tune the wavelength, this directionally injected structure, while implementing electrical wavelength compensation, isolates the direct interference of the compensation current on the light emission process of the gain segment. This prevents incidental fluctuations in the output optical power amplitude caused by wavelength drift suppression, thus ensuring the stability of the laser output signal. Attached Figure Description

[0049] Figure 1 This is a diagram showing the overall architecture of the wavelength-stabilized composite control system of the present invention.

[0050] Figure 2This is a schematic diagram of the method flow of the present invention;

[0051] Figure 3 This is a schematic diagram of the center wavelength drift comparison curve under long-term thermal aging conditions according to the present invention;

[0052] Figure 4 This is a timing diagram showing the comparison of transient frequency offset under burst communication pulses according to the present invention;

[0053] Figure 5 This is a schematic diagram illustrating the evolution trend of the dynamic mapping coefficient and low-frequency thermal resistance in this invention.

[0054] Among them, 100 is a multi-segment semiconductor laser; 101 is a gain segment; 102 is a grating segment; 103 is a shared heat sink; 200 is a digital signal processor; 300 is an analog-to-digital converter; 400 is a digital-to-analog converter; 500 is a thermoelectric cooling component; 10 is a thermal model construction module; 20 is a sensor extraction module; 30 is a state reconstruction module; and 40 is a decoupling compensation module. Detailed Implementation

[0055] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] See attached document Figure 1 , Figure 1 This is a schematic diagram of the overall architecture of a wavelength-stabilized composite control system according to an embodiment of the present invention. The present invention provides a wavelength-stabilized control method for a semiconductor laser, which is implemented based on a wavelength-stabilized composite control system. The wavelength-stabilized composite control system includes a multi-segment semiconductor laser 100 and digital control hardware components electrically connected to the multi-segment semiconductor laser 100.

[0057] The multi-segment semiconductor laser 100 includes a gain segment 101 and a grating segment 102. The gain segment 101 and the grating segment 102 are disposed on the same substrate and share a common heat sink 103 at the bottom. The digital control hardware components include a digital signal processor 200, an analog-to-digital converter 300, a digital-to-analog converter 400, and a thermoelectric cooling assembly 500. The digital signal processor 200 acquires the operating status parameters of the multi-segment semiconductor laser 100 through the analog-to-digital converter 300 and outputs control commands through the digital-to-analog converter 400 and the thermoelectric cooling assembly 500.

[0058] The wavelength-stabilized composite control system includes a thermal model construction module 10, a sensor extraction module 20, a state reconstruction module 30, and a decoupling compensation module 40 at the logical level. The core control logic is physically manifested as firmware code, logic gates, or microcode instruction sets configured within a field-programmable gate array, digital signal processor 200, or microcontroller.

[0059] See attached document Figure 2 , Figure 2 This is a flowchart of a wavelength stabilization control method for a semiconductor laser according to an embodiment of the present invention. The present invention provides a wavelength stabilization control method for a semiconductor laser, comprising the following steps:

[0060] S100, the thermal model construction module 10 establishes an equivalent heat transfer model based on the physical stacked structure of the multi-segment semiconductor laser 100, and transforms the high-frequency physical node characteristics of the epitaxial layer and the low-frequency physical node characteristics of the shared heat sink 103 into initial thermal impedance parameters.

[0061] S200, the sensing extraction module 20 monitors the modulation state of the radio frequency data stream of the gain segment 101, switches the measurement signal routing path according to the duty cycle characteristics, and extracts the low-frequency thermal resistance characteristic value of the multi-segment semiconductor laser 100.

[0062] S300, the state reconstruction module 30 receives the low-frequency thermal resistance characteristic value and performs online updates on the low-frequency physical node parameters. Combined with the transient heating power of the multi-segment semiconductor laser 100, it reconstructs full-band junction temperature observation data containing different frequency components.

[0063] S400, the decoupling compensation module 40 receives full-band junction temperature observation data and outputs feedforward control commands and feedback control commands to the thermoelectric cooling component 500 and the grating segment 102 of the multi-segment semiconductor laser 100 respectively according to the frequency components.

[0064] To further clarify the implementation of each technical aspect of the present invention, the following will provide a detailed description of the implementation of each functional module involved above and its internal processing flow.

[0065] In this embodiment, the equivalent heat transfer model construction step specifically includes the following sub-steps:

[0066] S101, calibrate the operating environment parameters and physical profile boundaries of the multi-segment semiconductor laser 100. Specifically, the thermal model construction module 10 needs to obtain the ambient temperature reference value and temperature control accuracy range of the wavelength-stabilized composite control system. Considering the normal operating conditions of an actual optical communication equipment room, and combining the linear cooling efficiency range of the thermoelectric cooling component 500 and the junction temperature safety threshold of the semiconductor material, this embodiment sets the base operating temperature range of the control system to 15℃ to 35℃. At the same time, to ensure the stability of the wavelength tuning mechanism, the steady-state temperature control accuracy is strictly set to ±0.1℃. Under this environmental reference, the thermal model construction module 10 divides the multi-segment semiconductor laser 100 into an epitaxial layer physical region and a heat sink packaging physical region from top to bottom, based on the actual vertical physical stacking structure of the multi-segment semiconductor laser 100, thereby providing a physical spatial mapping basis for the subsequent establishment of a mathematical model.

[0067] S102, the boundary of the aforementioned epitaxial physical region is defined, thereby generating a set of static high-frequency physical RC node parameters. Since this epitaxial physical region typically includes an active region, a waveguide layer, and a cladding, long-term engineering tests have shown that the solid-state semiconductor lattice structure possesses extremely strong physical stability as long as the injected current does not exceed the limiting threshold. In other words, the geometric dimensions of the epitaxial physical region and the thermal conductivity of the semiconductor material itself remain essentially constant throughout the entire lifecycle of the multi-segment semiconductor laser 100. Based on this physical fact, the thermal model construction module 10 directly defines its corresponding extreme transient thermal resistance and extreme transient thermal capacity as constants that do not drift over time. In specific operation, the thermal model construction module 10 discretizes the epitaxial physical region according to its actual spatial thickness, dividing it into multiple finite element sub-layers, and assigns a fixed thermal impedance value to each finite element sub-layer, thus forming a set of static high-frequency physical RC node parameters. It should be noted that the specific number of discrete finite element sub-layers is not arbitrarily set, but strictly depends on the highest cutoff frequency that the control algorithm needs to cover. As for how to use the thermal conductivity of the material and the cross-sectional area of ​​the structure to calculate the basic thermal resistance and basic heat capacity of a single layer, those skilled in the art can refer to the standard heat transfer theory to derive it. The conversion of these physical dimensions is a well-known technique in this field and will not be elaborated here.

[0068] S103, after clarifying the relatively stable top-level structure, this embodiment further defines the physical boundary of the shared heat sink 103 to address the long-term thermal aging problem at the bottom of the device, in order to generate a set of time-varying low-frequency physical RC node parameters. The thermal model construction module 10 classifies the shared heat sink 103 and the bottom bonding layer that connects it to the multi-segment semiconductor laser 100 as the heat sink packaging physical region. In actual laser service scenarios, the bottom bonding layer will inevitably experience solder voiding or even internal material delamination under long-term thermal cycling stress. This microscopic physical damage will directly lead to the continuous evolution of the interface thermal impedance of the entire heat sink packaging physical region. Therefore, the thermal model construction module 10 defines the low-frequency thermal resistance and low-frequency thermal capacitance in this region as time-varying parameters characterizing the aging state of the device, and establishes the initial set of time-varying low-frequency physical RC node parameters accordingly. To ensure sufficient engineering accuracy in this aging condition assessment, the time-varying parameter does not solely rely on the power-on duration. Instead, it employs a two-dimensional weighted logic for mathematical representation, combining the device's cumulative operating power-on time and the number of historical temperature jump cycles. Specifically, the control system records the device's cumulative operating power-on time and the number of cycles crossing a preset temperature difference threshold in its internal registers. These two values ​​are then linearly added together using corresponding empirical weighting coefficients to calculate a comprehensive degradation factor reflecting the degree of aging. The system uses this comprehensive degradation factor to proportionally scale the initially fixed low-frequency thermal resistance and low-frequency thermal capacity, thereby achieving dynamic updates to the time-varying parameter. This multi-dimensional evaluation method effectively avoids misjudgments of aging condition caused by long-term device power-on with stable junction temperatures.

[0069] S104, after obtaining the parameters of the high-frequency and low-frequency physical nodes, the thermal model construction module 10 constructs a continuous thermal trapezoidal topology based on the distributed parameter heat transfer theory. As an equivalent heat transfer mathematical model that can strictly map the vertical physical stacking order of semiconductor devices, the continuous thermal trapezoidal topology is the core bridge connecting the hardware physical entity and the software compensation algorithm. The thermal model construction module 10 cascades the previously established static high-frequency physical RC node parameter set and the time-varying low-frequency physical RC node parameter set strictly according to their physical spatial positions from top to bottom in reality. In this way, the system generates a global equivalent transient thermal impedance formula that reflects the one-dimensional heat flow conduction characteristics. This formula is specifically expressed as:

[0070] ;

[0071] In the formula, This represents the global equivalent transient thermal impedance of the system in the Laplace domain. Represents the Laplace operator. This indicates the operating aging time of the multi-segment semiconductor laser 100. This represents the first-order curing thermal resistance in the static high-frequency physical RC node parameter set. This represents the first-order curing heat capacity in the static high-frequency physical RC node parameter set. Represents the first in the set of time-varying low-frequency physical RC node parameters. Dynamic thermal resistance, Represents the first in the set of time-varying low-frequency physical RC node parameters. The dynamic heat capacity of the first order, where It is a positive integer, representing the total number of time-varying low-frequency physical layers divided according to the required observation accuracy.

[0072] The ellipsis in the denominator of the formula represents the continuous cascaded terms of the intermediate-level physical structure. At the engineering implementation level, when the digital signal processor 200 performs discretization from the frequency domain to the time domain based on the above cascaded formula, it faces a typical low-level computational risk. If the system is in steady-state DC operation, the Laplace operator... Approaching zero, direct substitution into calculations risks computational overflow due to the denominator approaching zero. To address this computational anomaly, this embodiment forcibly introduces steady-state impedance approximation logic into the underlying firmware. Once a DC condition is detected, the system directly applies the thermal capacitance complex frequency domain admittance terms. By setting the thermal resistance to zero (i.e., physically treating it as an open circuit in the thermal capacity branch), complex calculus calculations are skipped, and the pure algebraic scalar sum of the thermal resistances of each order is directly output. This algorithmic-level safeguard mechanism completely avoids the division-by-zero overflow anomaly in floating-point operations, ensuring the mathematical completeness and executability of the equivalent heat transfer model under full-band operating conditions.

[0073] S105, to ensure the stable operation of the abstract mathematical model at the hardware level, the thermal model construction module 10 configures a data register array within the hardware carrier of the wavelength-stabilized composite control system to complete the lower-level physical mapping of the model. As a preferred approach, the thermal model construction module 10 allocates a dedicated storage block within the contiguous memory address space of the digital signal processor 200. This block maps and stores all the solidified thermal resistances, solidified thermal capacities, and time-varying dynamic thermal resistances and dynamic thermal capacities derived from the formulas as floating-point numerical variables in the corresponding memory addresses. For system operational security, the thermal model construction module 10 performs write protection locking on the register addresses corresponding to the static high-frequency physical RC nodes, retaining only continuous read and write permissions for the addresses corresponding to the time-varying low-frequency physical RC nodes. This biased memory access management, on the one hand, provides a low-level data update framework for the subsequent adaptive boundary condition calibration of the control system, and on the other hand, fundamentally ensures that the core static reference parameters of the device will not be erroneously overwritten by occasional abnormal interference signals when dealing with complex future RF communication service flows.

[0074] In this embodiment, the adaptive sensing and feature extraction step specifically includes the following sub-steps:

[0075] S201, the sensor extraction module 20 monitors the RF data stream status of the gain segment 101 and performs routing path switching. In actual optical communication services, due to the highly bursty and time-varying characteristics of the underlying communication data stream, the modulation state of the multi-segment semiconductor laser 100 exhibits significant differences in operating conditions at different time points. Specifically, the sensor extraction module 20 accurately counts the RF data stream duty cycle within a preset time window using a hardware counter configured inside the digital signal processor 200. The length of this preset time window is not fixed but dynamically adaptively matched according to the frame period of the underlying communication protocol. The aforementioned RF data stream duty cycle, as a core evaluation parameter, is directly used to measure the proportion of time that the gain segment 101 is in a high-frequency data-intensive modulation state. To prevent frequent switching oscillations of the underlying physical routing switch caused by a single judgment condition under critical conditions, this embodiment constructs a two-dimensional weighted judgment logic that integrates the duty cycle value and the continuous duration of the high-frequency envelope.

[0076] As a preferred approach, the sensor extraction module 20 pre-defines the duty cycle threshold and its corresponding state switching hysteresis range. The calibration benchmark for this duty cycle threshold is determined by the minimum sampling setup time of the analog-to-digital converter (ADC) 300, typically constrained to within 15% to 20% of the communication cycle to ensure sufficient charging integration time for the underlying hardware capacitor network. When the physical RF idle time window is shorter than the aforementioned sampling setup time, the ADC 300 will be unable to acquire a stable effective voltage sample at the hardware level. During system operation, the sensor extraction module 20 continuously compares the real-time calculated RF data stream duty cycle with the aforementioned duty cycle threshold. Based on the dynamic comparison results, the sensor extraction module 20 directionally triggers the underlying digital routing switch to physically switch the low-frequency pilot signal injection path. When the RF data stream duty cycle falls within a range less than or equal to the duty cycle threshold, the control system determines that the current physical condition is operating during a pulse idle period, and the underlying digital routing switch then directionally injects the low-frequency pilot signal losslessly into the gain segment 101. Conversely, when the duty cycle of the radio frequency data stream exceeds the duty cycle threshold and exceeds the hysteresis interval, the control system determines that it is currently operating in the continuous dense modulation period, and the digital routing switch switches the injection path of the low-frequency pilot signal to the grating segment 102.

[0077] S202, when the control system is in the aforementioned pulse idle period, the sensor extraction module 20 initiates an equivalent time undersampling feature extraction operation for the gain segment 101. Based on the undersampling reconstruction principle in classical signal processing theory, for high-frequency disturbed signals within a limited time window, the system can extract discrete phase points in multiple different periods and then combine them into a complete low-frequency envelope in the digital domain. Specifically applied to the scenario of this embodiment, even within the macroscopic pulse idle period, sporadic RF transition edges can still induce strong electromagnetic intermodulation interference. Such physical parasitic phenomena can lead to the risk of large-scale data failure for conventional continuous-time sampling methods. To completely avoid the nonlinear interference caused by RF transition edges, the sensor extraction module 20 constructs a digital mask function that is strictly synchronized with the main communication pulse within the digital clock domain. This digital mask function maintains a high-level output state in the steady-state flat-top region of the RF pulse, while forcibly outputting a low-level state in the establishment region before and after the RF transition edge. Relying on a global clock system phase-locked with the RF data stream, the sensor extraction module 20 triggers the analog-to-digital converter 300 to perform discrete undersampling only during the high-level period of the digital mask function output. This precise time-domain gating mechanism successfully acquires clean discrete voltage samples that effectively avoid edge-jumping interference.

[0078] Considering that the duration of the steady-state flat-top region of a single RF pulse is on the order of nanoseconds, it cannot physically accommodate even a complete low-frequency pilot signal cycle. The sensing extraction module 20 continuously pushes discrete voltage samples spanning multiple communication service cycles into a designated memory address sequence. The digital signal processor 200 performs modulo-modulo operations on the original absolute sampling time of each discrete voltage sample according to the inherent period of the low-frequency pilot signal, and rearranges all discrete voltage samples in memory based on the new time stamp generated after the modulo operation, thereby completing the seamless analog-time stitching of the discrete samples. The stitched discrete sample sequence needs to be further fed into a multi-period moving average filter for smoothing. This filtering process effectively removes high-frequency discrete noise components caused by the jitter triggered by the underlying hardware clock, reconstructing the rearranged sequence into a smooth low-frequency voltage sinusoidal envelope with an extremely high signal-to-noise ratio.

[0079] Subsequently, the sensing extraction module 20 performs digital phase-locked integration on the equivalent low-frequency voltage sinusoidal envelope to accurately extract the low-frequency AC voltage amplitude, and then calculates the current true low-frequency thermal resistance of the gain segment 101. Before delving into the specific mathematical derivation, it is important to clarify that, based on the electrothermal coupling physical mechanism of semiconductor PN junctions, the continuous injection of low-frequency constant power will inevitably cause periodic perturbations in the internal junction temperature. This micro-temperature fluctuation will be linearly converted into the low-frequency AC envelope of the voltage across the two ends through the inherent bandgap temperature property of the semiconductor material. Based on this established physical correlation mechanism, the formula for calculating the true low-frequency thermal resistance is expressed as:

[0080] ;

[0081] In the formula, Indicates the device aging time The actual low-frequency thermal resistance of the extracted gain band 101, This represents the low-frequency AC voltage amplitude extracted through digital phase-locked loop integration. This represents the absolute value of the junction voltage drop temperature coefficient of a semiconductor material. This represents the constant injected electrical power of the low-frequency pilot signal.

[0082] The junction voltage drop temperature coefficient (JDC) is an inherent physical constant characterizing the linear negative correlation between the forward bias voltage drop of a semiconductor PN junction and ambient temperature. As a preferred engineering implementation parameter, the JDC's conventional range is calibrated to -1.0 mV / ℃ to -2.5 mV / ℃. Its precise value is permanently stored in the system's non-volatile memory after being cyclically calibrated in a constant temperature bath before the multi-segment semiconductor laser 100 leaves the factory. Regarding the aforementioned division operation logic, to prevent the denominator from approaching zero and causing a floating-point overflow anomaly in the underlying processor, the control system forcibly configures a closed-loop constant power control hardware mechanism in the underlying pilot signal generation loop, ensuring a constant injected power. The lower limit of the value is strictly constrained to a safe range that is more than ten times the system's background electromagnetic noise power, thus cutting off the potential path for software to crash due to division by zero from the source of the physical circuit.

[0083] S203, when the control system determines that it is currently operating in a continuous dense modulation period, the effective duty cycle of the high-level output of the digital mask function shrinks sharply and approaches zero. Under this timing condition, the equivalent time undersampling mechanism cannot acquire discrete voltage samples that meet the Nyquist reconstruction condition due to the lack of a sufficiently effective time observation window. The sensor extraction module 20 then starts the spatial proxy sensing operation mode. The underlying digital routing switch redirects the low-frequency pilot signal and injects it into the interior of the passive waveguide structure, i.e., the grating segment 102, which does not carry any RF data modulation. Since there is no high-speed RF signal transition edge on the physical level of the grating segment 102, the analog-to-digital converter 300 can directly perform maskless continuous-time phase-locked sampling on the voltage nodes at both ends. Based on the acquired continuous voltage data sequence, the sensor extraction module 20 uses the thermal resistance calculation principle derived from Ohm's law to directly extract the proxy low-frequency thermal resistance of the grating segment 102 in the current state. The core technical motivation for introducing grating segment 102 as a space proxy sensor in the system architecture is that this specific structure can achieve high impedance electrical isolation from the amplitude modulation channel of the main communication optical path in three-dimensional physical space, thereby suppressing nonlinear electromagnetic crosstalk of high-power modulation signals to the weak low-frequency feature extraction process from the source of physical structure.

[0084] S204, the sensor extraction module 20 further combines the actual measurement values ​​of the underlying communication frame gaps to perform online adaptive updates to the dynamic mapping coefficients within the system. During the long-term high-frequency service life of the multi-segment semiconductor laser 100, the gain segment 101 continuously bears extremely high transient electrical injection heat density, resulting in a significant physical spatial asymmetry in the heat sink area at its bottom and the thermomechanical stress borne by the bottom of the grating segment 102. This long-term stress asymmetry inevitably evolves into a severe deviation in the aging and deterioration of the solder layer materials at the bottom of both segments. If the system uses only the parameters of the grating segment 102 for fixed-ratio substitution calculations throughout its entire lifespan, the control system will quickly fall into a measurement blind zone and severe reference temperature drift caused by the physical spatial asymmetry. To correct this spatial aging deviation online, the sensor extraction module 20 utilizes the microsecond-level communication frame gaps inherent in the underlying standard communication protocol to perform precise high-frequency online data alignment and idle-state time-division multiplexing extraction. When the RF circuit state machine inside the sensing extraction module 20 captures the moment the communication frame gap arrives, the system will forcibly trigger the underlying hardware array to temporarily switch back to the equivalent time undersampling mode unique to the pulse idle period, so as to obtain the true low-frequency thermal resistance of the gain segment 101 at the current absolute time node with the fastest response speed. To ensure the rigor and absolute causal alignment of multi-source heterogeneous data in spatial comparison operations, the digital signal processor 200 calls the internal high-precision system clock and uses the hardware timestamp mechanism to perform nanosecond-level alignment and binding of the obtained true low-frequency thermal resistance of the gain segment 101 and the proxy low-frequency thermal resistance of the grating segment 102, effectively eliminating the systematic temperature drift error introduced by the time-division acquisition time misalignment.

[0085] Subsequently, the sensor extraction module 20 uses the timestamp-aligned real low-frequency thermal resistance and performs a division mapping operation with the surrogate low-frequency thermal resistance continuously extracted within the same extremely narrow time window to generate dynamic mapping coefficients for correcting physical space deviations. In this calculation, since the fundamental thermal resistance of semiconductor materials is always a strictly positive real number greater than zero within the normal safe operating temperature range, and the sensor extraction module 20 has a pre-defined maximum clamping isolation logic at the algorithm level to address probe open-circuit faults, this division operation is naturally immune to any form of division-to-zero overflow anomaly. The update formula for the dynamic mapping coefficients and the derivation formula for the global equivalent low-frequency thermal resistance are expressed as follows:

[0086] ;

[0087] ;

[0088] In the formula, Indicates aging time The dynamic mapping coefficients are calculated and updated online adaptively. This indicates the use of grating segment 102 to continuously extract the proxy low-frequency thermal resistance. This represents the global equivalent low-frequency thermal resistance of the multi-segment semiconductor laser 100 after calibration using dynamic spatial mapping. In this embodiment, to prevent extreme radio frequency interference from causing distortion and divergence in the mapping coefficient calculation, the dynamic mapping coefficient... The legal update range is strictly limited to a value range of 0.5 to 5.0. Any calculation result outside this range will be directly discarded by the system, and the historical valid value of the previous cycle will be retained. When the inter-frame gap detection ends and the operation phase re-enters the pure continuous dense modulation period, the sensor extraction module 20 only needs to multiply the proxy low-frequency thermal resistance collected in real time by the grating segment 102 by the dynamic mapping coefficient that was successfully updated and locked in the previous communication inter-frame gap. This allows for real-time and high-frequency calculation of the extremely accurate global equivalent low-frequency thermal resistance. This online calibration and safety clamping logic based on physical inter-frame gaps ensures the absolute safety of engineering operations and guarantees that the control system can still seamlessly acquire baseline thermal resistance characteristic parameters that highly match its actual microscopic aging state even when the gain segment 101 is in the physical measurement blind zone for a long time.

[0089] In this embodiment, the physical node update and state reconstruction steps specifically include the following sub-steps:

[0090] S301, the state reconstruction module 30 reverse maps the low-frequency thermal resistance characteristic values ​​extracted in the previous step to the time-varying low-frequency physical RC nodes to complete the baseline calibration of the equivalent heat transfer model. Based on the physical concentration law of thermal degradation of semiconductor devices, material voids and interface delamination caused by long-term thermal cycling mainly occur at the bottom welding interface of the shared heat sink 103. Based on this physical causal relationship, the state reconstruction module 30 in this embodiment does not need to perform global blind correction on the RC parameters of all levels, but instead maps the drift of the global equivalent low-frequency thermal resistance to the last-order dynamic thermal resistance and dynamic thermal capacity of the corresponding bottom physical structure according to spatial weight. In order to avoid misjudgment of aging state caused by sporadic measurement noise or single extreme value, the state reconstruction module 30 does not directly use the extreme value drift of a single measurement, but uses a weighted moving average logic based on multi-cycle historical data to calculate the final effective drift. To ensure the absolute mathematical stability of the closed-loop control system, the state reconstruction module 30 internally sets a parameter update step size limiting mechanism. When the weighted thermal resistance drift exceeds a preset safety step size threshold, the system will forcibly clamp it to that threshold. As a preferred approach, the conventional engineering value for this safety step size threshold is set between 0.5% and 1.5% of the initial calibrated thermal resistance value. This limiting logic effectively prevents accidental external electromagnetic interference from causing sudden changes or even divergence in model parameters. Through the aforementioned inverse mapping and limiting update, the state reconstruction module 30 constructs a dynamic equivalent heat transfer model that accurately reflects the current underlying physical degradation state of the multi-segment semiconductor laser 100.

[0091] S302, the state reconstruction module 30 calculates the energy difference between the real-time injected electrical power and the output optical power of the gain segment 101, thereby accurately extracting the transient heating power. Based on the law of conservation of energy, part of the electrical energy entering the semiconductor lattice is converted into photons that escape from the device, while the remaining part is inevitably converted into phonons that induce lattice thermal vibrations. Since the accuracy of the transient heating power directly determines the benchmark reliability of subsequent temperature state observations, the digital signal processor 200 uses a high-speed parallel sampling bus to synchronously and continuously acquire the driving voltage, injected current, and optical power data fed back by the backlight detector of the gain segment 101. To eliminate the inherent phase delay differences in the multi-channel analog-to-digital conversion hardware link, the state reconstruction module 30 incorporates a hardware delay alignment mechanism based on a ring buffer at the underlying register level. Simultaneously, to ensure strict alignment of multi-source heterogeneous data in the operating condition dimension, the state reconstruction module 30 in this embodiment only latches the aforementioned physical quantities within the effective time window of the underlying RF pulse's steady-state flat-top period. This mechanism forces the sampling clock of each physical quantity to be coupled to the same high-precision system clock, ensuring that all measured parameters achieve strict time series alignment under the same microsecond-level timestamp. Based on the aligned multi-source physical quantities, the formula for calculating transient heating power is expressed as:

[0092] ;

[0093] In the formula, Indicates the first Transient heating power in a discrete sampling period, Indicates the first The measured operating voltage of gain segment 101 during each discrete sampling period. Indicates the first The measured injection current of gain segment 101 in a discrete sampling period Indicates the first The measured output optical power for each discrete sampling period. This formula clarifies the source of the net power actually converted into lattice heat energy, and its technical purpose is to accurately extract the non-thermal energy portion that has been carried out of the system by photons from the total electrical power.

[0094] S303, combining the transient heating power after multi-source alignment with the updated equivalent heat transfer model, the state reconstruction module 30 deduces the full-band junction temperature observation data through state-space equations and time-domain convolution operations. Specifically, state-space theory uses the set of state variables within the system to describe the dynamic differential relationship between multidimensional inputs and outputs. This mechanism can fit the time-domain physical derivation of multi-order RC thermal trapezoidal topology. In this derivation process, the state reconstruction module 30 converts the continuous Laplace domain equivalent heat transfer model into a discrete-time domain state-space observer. When performing discretization matrix operations, the control system faces underlying arithmetic risks. Extremely small discrete sampling step sizes can easily cause the state transition matrix to approach an ill-conditioned singular matrix during inversion or long-period iteration. To avoid this algorithmic defect, the state reconstruction module 30 forcibly applies a small regularization constant to the diagonal elements of the matrix for diagonal loading. As a preferred method, the value range of this regularization constant is specified as 10. -6 Up to 10 -4 The basis for this determination is to suppress the introduced static steady-state temperature error of the system to below one-thousandth of a °C while breaking the linear dependence of the matrix. This matrix dimensionality reduction and regularization prevention logic eliminates the potential risk of arithmetic collapse in complex matrix space operations. The state-space equations for discrete-domain junction temperature derivation are specifically expressed as follows:

[0095] ;

[0096] ;

[0097] In the formula, Indicates the first Internal temperature node state column vector for each discrete sampling period Indicates the first Internal temperature node state column vector for each discrete sampling period This represents the discrete state transition matrix after regularization to prevent singularities. Indicates the input control matrix. This indicates the output observation matrix. The deduced first Full-band junction temperature observation data of a discrete sampling period multi-segment semiconductor laser 100. This indicates the base reference temperature of the multi-segment semiconductor laser 100. Input control matrix. With output observation matrix The specific internal elements depend on the spatial cascade order and corresponding values ​​of the physical RC parameters of each order in the equivalent heat transfer model. Specifically, after the digital signal processor 200 transforms the equivalent heat transfer model into a continuous-time differential equation system based on Kirchhoff's heat flux law, it can solve for the above-mentioned regularized and anti-singularity discrete state transition matrix using standard discretization algorithms such as zero-order hold (ZOH) or bilinear transform. Input control matrix With output observation matrix .

[0098] S304, the state reconstruction module 30 uses its internally configured digital filter bank to perform orthogonal decomposition processing on the full-band junction temperature observation data obtained from the above deduction. The internal junction temperature evolution of the multi-segment semiconductor laser 100 under complex high-speed communication modulation is a deeply coupled process involving multiple physical quantities with an extremely wide bandwidth. If a single-dimensional broadband reverse compensation is performed on the full-band junction temperature, it will inevitably lead to a strong closed-loop conflict between low-frequency temperature drift calibration and high-frequency transient compensation. Based on the engineering control principle of frequency decoupling, the state reconstruction module 30 feeds the full-band junction temperature observation data in parallel into a finite impulse response digital filter bank with flat group delay characteristics. This digital filter bank finely cuts and orthogonally decomposes the extremely wide temperature bandwidth into three independent physical characteristic components.

[0099] In this embodiment, the first cutoff frequency of the filter bank is set to 0.1Hz, and the second cutoff frequency is set to 10kHz. The cutoff frequency division is based on the physical critical point between the low-frequency thermal time constant boundary of the heat sink and the high-frequency thermal time constant of the epitaxial layer. Specifically, the extremely low-frequency DC component below 0.1Hz mainly characterizes the slow drift of the substrate ambient temperature and the cumulative thermal effect of long-term packaging aging; the mid-to-low frequency fluctuation component between 0.1Hz and 10kHz reflects the structural thermal accumulation process caused by the thermal capacitance charging and discharging of the heat sink packaging physical region; and the extremely transient high-frequency fluctuation component above 10kHz corresponds entirely to the nanosecond-level lattice transient thermal response triggered by the dense modulation of radio frequency data in the epitaxial layer physical region. By safely decomposing the complex temperature signal with broadband aliasing into the above three non-overlapping orthogonal components, the state reconstruction module 30 provides a data input source with a clear physical causal orientation for the subsequent control system to perform targeted frequency division decoupling compensation.

[0100] In this embodiment, the multidimensional orthogonal decoupling compensation execution step specifically includes the following sub-steps:

[0101] S401, the decoupling compensation module 40 generates a closed-loop adjustment signal based on the extremely low-frequency DC component, driving the thermoelectric cooling component 500 to lock the system boundary reference temperature. The long-term drift of the reference wavelength of the multi-segment semiconductor laser 100 is strongly dependent on the overall thermal accumulation state of the underlying substrate. For the conventional proportional-integral-derivative control logic of the thermoelectric cooling component 500, those skilled in the art can directly implement it based on classical control theory, and its supporting hardware driver architecture is a well-known technology in the field, which will not be described in detail here. In this embodiment, the decoupling compensation module 40 only extracts the extremely low-frequency DC component below 0.1Hz as the feedback input reference of the thermoelectric cooling component 500. The physical relevance of selecting this specific frequency band as the input parameter lies in the fact that the inherent thermal time constant of the large-volume mechanical heat sink structure is far greater than 10 seconds, and high-frequency signals cannot be physically responded to by it. The core technical purpose of this setting is to effectively filter out high-frequency transient thermal disturbance signals from the temperature control loop, thereby preventing parasitic thermal oscillations in the underlying layer of the cooling array caused by frequent local charging and discharging of the mechanical heat sink structure.

[0102] S402, the decoupling compensation module 40 calculates the basic wavelength compensation amount based on the low- and mid-frequency fluctuation components and forcibly introduces a phase transition slope limiting algorithm to output a low- and mid-frequency feedback compensation current that suppresses plasma mode jumps. In the carrier tuning mechanism of semiconductor lasers, drastic changes in the injected current can cause nonlinear variations in the refractive index inside the waveguide material. If the time-domain tracking rate of the compensation current with low- and mid-frequency temperature fluctuations is too large, the transient plasma effect accumulated in the gain cavity will destroy the original longitudinal mode phase matching condition, thereby causing a discontinuous jump phenomenon in the lasing wavelength. To suppress this jump phenomenon at the physical level, the decoupling compensation module 40 in this embodiment calculates the ideal basic wavelength compensation amount by looking up a preset temperature-current wavelength tuning mapping table, and then further executes a phase transition slope limiting algorithm based on first-order difference calculation. In this embodiment, the temperature-current wavelength tuning mapping table is a data table calibrated by a temperature-controlled tuning experiment and stored in non-volatile memory before the device leaves the factory. It represents the reference compensation current value required to maintain the target wavelength under different ambient temperatures. Considering the inherent sensitivity of differential operations to high-frequency measurement noise, to avoid single glitches triggering erroneous amplitude limiting in the control system, the system does not rely solely on extreme difference in a single sampling period. Instead, it extracts the rate of change of compensation from multiple consecutive discrete sampling periods and performs moving average weighting to obtain a truly smooth transient rate of change. When the absolute value of this transient rate of change exceeds a preset mode-jump safety slope threshold, the control system forcibly truncates the output increment of the current period and clamps it to this mode-jump safety slope threshold. As a preferred approach, the physical value of this mode-jump safety slope threshold is determined by a combination of the intrinsic dispersion coefficient of the laser grating material and the physical cavity length, with its conventional engineering constraint range set to 0.05 mA to 0.15 mA per microsecond. Through the aforementioned rigorous slope limiting processing, the decoupling compensation module 40 outputs a smooth and continuous mid-to-low frequency feedback compensation current. This current sequence effectively offsets the heat sink's accumulated temperature drift while ensuring the spectral purity of the device's single-mode lasing state.

[0103] S403, the decoupling compensation module 40 calculates the thermal chirp cancellation amount by combining the extremely transient high-frequency fluctuation component with the inverse thermodynamic transfer function, generating a feedforward predistortion compensation current with high-pass zero-mean characteristics. During the dense modulation of communication RF data, the epitaxial lattice inside the gain section 101 continuously generates severe thermal oscillations on a nanosecond timescale. These thermal oscillations cause severe high-frequency thermal chirp distortion in the output optical signal through an electrothermal coupling mechanism. Due to the inherent physical thermal impedance phase delay in the spatial conduction of heat from the heating region to the wavelength tuning region, conventional closed-loop control relying on error feedback cannot catch up with the transient thermal evolution process in time. Based on the forward reconstruction principle of causal time series, the decoupling compensation module 40 constructs the inverse thermodynamic transfer function by calling the discretized dynamic parameters inside the equivalent heat transfer model. The system uses this inverse thermodynamic transfer function to map the extremely transient high-frequency fluctuation component in advance to the corresponding transient refractive index distortion. At the mathematical implementation level, since directly inverting the transfer function of a physical system can easily cause the system gain to approach infinity near its high-frequency transmission zero, thus leading to the risk of division by zero overflow, the decoupling compensation module 40 in this embodiment forcibly introduces the minimum mean square error approximation inversion algorithm based on Tikhonov regularization factor when constructing the inverse transfer function.

[0104] As a preferred approach, the value of this regularization factor is determined based on the ratio of the system's high-frequency background white noise power to the effective thermal signal power, and is typically constrained to 10. -5 Up to 10 -3 Between. This algorithmic defense physically limits the upper limit of the gain of the high-frequency compensation channel, effectively avoiding the uncontrolled divergence of the compensation current caused by the denominator of the inverse polynomial approaching zero. Subsequently, based on the pre-stored refractive index and carrier current plasma response mapping table, the system calculates the thermal chirp cancellation amount that is equal to the physical amplitude of the transient thermal response and has the exact opposite mathematical phase. The refractive index and carrier current plasma response mapping table is also extracted and generated from the dynamic parameter test during the laser's manufacturing stage, characterizing the corresponding physical relationship between the carrier injection concentration inside the grating segment and the change in the equivalent refractive index. Considering that the high-frequency predistortion compensation only performs local time-domain repair on the RF transition edge and should not change the overall static operating bias point of the laser, the decoupling compensation module 40 performs high-pass digital filtering and mean zeroing processing on the calculated thermal chirp cancellation amount in the final output stage to generate the final feedforward predistortion compensation current. The lower limit of the frequency band of the feedforward predistortion compensation current is strictly locked above 10kHz to avoid destructive closed-loop coupling conflict with the mid-to-low frequency feedback control loop in the energy band.

[0105] In S404, the decoupling compensation module 40 performs digital linear synthesis of the low-frequency feedback compensation current and the feedforward predistortion compensation current, and outputs the synthesis command directionally to the grating segment 102 of the multi-segment semiconductor laser 100. Since the spatially separated multi-segment semiconductor laser 100 has completely independent carrier injection channels in its physical structure, the grating segment 102, as a passive wavelength tuning region, naturally does not participate in the direct lasing amplification process of the main optical power. The core technical advantage of injecting the synthesized compensation current containing complex full-band information separately and precisely into the grating segment 102 is that it effectively isolates the direct modulation crosstalk of the compensation current action on the baseline of the output optical power amplitude of the gain segment 101. To ensure that the compensation currents calculated in different frequency bands have strict operating conditions and timing alignment when performing hardware superposition, the decoupling compensation module 40 is configured with a first-in-first-out depth-adjustable digital delay line in its underlying computing architecture. This mechanism forcibly compensates for the nanosecond-level pipeline time difference caused by the difference in algorithm complexity between the low-frequency calculation channel and the high-frequency feedforward calculation channel. In the specific execution phase, the decoupling compensation module 40 calls the underlying high-precision digital-to-analog converter to perform algebraic addition at the register level with the time series of the aligned mid-to-low frequency feedback compensation current and the feedforward predistortion compensation current, based on the principle of time-domain superposition. The digital linear synthesis formula is expressed as:

[0106] ;

[0107] In the formula, Indicates the first The digital linear synthesized current is output directionally to the grating segment 102 in a discrete sampling period. Indicates the first The low-to-medium frequency feedback compensation current output after processing by the phase transition slope limiting algorithm for each discrete sampling period. Indicates the first The feedforward predistortion compensation current with high-pass zero-mean characteristics is generated by the derivation of discrete sampling periods. By re-orthogonally synthesizing the decomposed and decoupled cross-frequency current in the digital domain and implementing three-dimensional spatial fixed-point injection, this control system completes high-fidelity inverse cancellation of full-band transient thermal drift in a closed loop at the underlying physical execution level.

[0108] To further aid in understanding the technical solution of this invention, a detailed description is provided below in conjunction with specific application embodiments and experimental verification data. Relevant experimental test data are acquired and exported in real time through the underlying hardware platform, and then visualized and charted offline using numerical analysis tools.

[0109] This embodiment uses a multi-segment DBR semiconductor laser in a coherent optical communication module as an example. The multi-segment semiconductor laser 100 includes a gain segment 101 and a grating segment 102, and is bonded to a common heat sink 103 via a bottom substrate. The control system hardware employs a digital signal processor 200 with a main frequency of 800MHz, and the sampling rate of the analog-to-digital converter 300 and the digital-to-analog converter 400 is configured to 100MS / s.

[0110] When the system starts up, the base temperature is set to 25℃. The thermal model construction module 10 divides the physical region of the epitaxial layer into a third-order static high-frequency RC network and the physical region of the heat sink encapsulation into a second-order time-varying low-frequency RC network. When the system is detected to be in steady-state DC operation, the system sets the complex frequency domain admittance term to zero and directly outputs the pure algebraic scalar summation value of each order of thermal resistance. The frame period of the underlying communication protocol is set to 20 microseconds and the frame gap is 2 microseconds. The low-frequency pilot signal frequency is set to 1kHz and the current amplitude is 2mA. When the sensing extraction module 20 detects that the duty cycle of the RF data stream in the gain segment 101 exceeds 15%, the system injects the pilot signal into the grating segment 102 to obtain the proxy low-frequency thermal resistance; within the 2-microsecond physical frame gap, the system switches to the equivalent time undersampling mode to obtain the true low-frequency thermal resistance of the gain segment 101 and calculates and updates the dynamic mapping coefficients within this time window.

[0111] The state reconstruction module 30 performs discrete iterative calculations in 10-nanosecond steps. The derived full-band junction temperature observation data enters the digital filter bank and is decomposed into: an extremely low-frequency DC component below 0.1Hz, a mid-to-low-frequency fluctuation component between 0.1Hz and 10kHz, and an extremely transient high-frequency fluctuation component above 10kHz. The decoupling compensation module 40 outputs the extremely low-frequency DC component to the thermoelectric cooling component 500 for reference temperature locking; converts the mid-to-low-frequency fluctuation component into a basic wavelength compensation amount and performs phase transition slope limiting processing; and simultaneously calculates the feedforward predistortion compensation current in conjunction with the extremely transient high-frequency fluctuation component. The mid-to-low-frequency feedback compensation current and the feedforward predistortion compensation current are digitally linearly synthesized and then directionally injected into the grating segment 102 to complete the composite compensation.

[0112] To verify the actual effect of the wavelength-stabilized composite control system, this embodiment built an optoelectronic joint hardware test platform and set up a comparison with a traditional control group that uses conventional proportional-integral-derivative temperature control and lookup table compensation.

[0113] See attached document Figure 3 The multi-segment semiconductor laser 100 was subjected to a 1000-hour accelerated aging test at 85°C. Figure 3The dashed line represents the traditional control group. Because it cannot detect the gradual increase in the interface thermal resistance of the shared heat sink 103, the center wavelength exhibits a single shift trend with aging time, reaching approximately +18 pm after 1000 hours. The solid line represents the wavelength-stabilized composite control system of this invention. The sensor extraction module 20 captures the change in interface thermal resistance through online adaptive calculation of dynamic mapping coefficients, and the state reconstruction module 30 corrects the equivalent heat transfer model accordingly. Throughout the aging cycle, the center wavelength drift is limited to a deviation band of ±1.5 pm, verifying the system's ability to compensate for time-varying low-frequency thermal resistance caused by package aging.

[0114] See attached document Figure 4 A high-speed burst modulation signal was injected into the gain section 101 to test the high-frequency transient compensation effect. Figure 4 In the initial stage of a burst pulse arrival, traditional control groups experience a high-peak transient frequency shift (reaching approximately 850 MHz) due to physical thermal conduction delay, known as thermal chirp. In the wavelength-stabilized composite control system of this invention, the decoupling compensation module 40 utilizes the inverse thermodynamic transfer function to inject a feedforward pre-distortion compensation current into the grating segment 102 in advance. The synthesized compensation current controls the peak-to-peak value of the transient frequency shift at the burst transition edge to within 90 MHz, reducing it by nearly an order of magnitude compared to the traditional group, thus improving the lasing spectrum stability of the laser under burst communication conditions.

[0115] See attached document Figure 5 During the continuous dense modulation stage of radio frequency, the system uses physical frame gaps to extract thermal resistance feature data and generate dual Y-axis trend curves. Figure 5 The left axis reflects the evolution of the discrete difference between the actual low-frequency thermal resistance of gain segment 101 and the surrogate low-frequency thermal resistance of grating segment 102 under different environmental stress cycles, caused by the underlying spatial asymmetry; the right axis reflects the convergence process of the dynamic mapping coefficients in the system's adaptive calculation. The data show that the dynamic mapping coefficients converge dynamically within the range of 1.15 to 1.38. This calibration mechanism avoids spatial proxy measurement bias caused by long-term continuous modulation, ensuring the continuity and accuracy of the globally equivalent low-frequency thermal resistance extraction results.

[0116] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for wavelength stabilization control of a semiconductor laser, characterized in that, Includes the following steps: An equivalent heat transfer model for a multi-segment semiconductor laser is constructed, the equivalent heat transfer model including a static high-frequency physical RC node parameter set and a time-varying low-frequency physical RC node parameter set; Monitor the duty cycle of the RF data stream of the gain segment of the multi-segment semiconductor laser, extract the global equivalent low-frequency thermal resistance by switching the injection path of the low-frequency pilot signal, and update the set of time-varying low-frequency physical RC node parameters. By combining the transient heating power of the gain band with the updated equivalent heat transfer model, the junction temperature observation data of the entire frequency band is deduced, and the junction temperature observation data of the entire frequency band is decomposed into extremely low frequency DC component, medium and low frequency fluctuation component and extremely transient high frequency fluctuation component. The thermoelectric cooling component is driven according to the extremely low frequency DC component; a medium-low frequency feedback compensation current is generated according to the medium-low frequency fluctuation component, and a feedforward predistortion compensation current is generated in combination with the extremely transient high frequency fluctuation component; the medium-low frequency feedback compensation current and the feedforward predistortion compensation current are linearly synthesized and injected into the grating segment of the multi-segment semiconductor laser.

2. The wavelength stabilization control method for a semiconductor laser according to claim 1, characterized in that, The construction of the equivalent heat transfer model for the multi-segment semiconductor laser includes: The epitaxial physical region of the multi-segment semiconductor laser is assigned fixed extreme transient thermal resistance and extreme transient thermal capacity according to the number of discretized layers to generate the static high-frequency physical RC node parameter set. A comprehensive degradation factor is calculated based on the cumulative operating power-on time and historical temperature jump cycle number of the multi-segment semiconductor laser. The low-frequency thermal resistance and low-frequency thermal capacity of the heat sink packaging physical region are scaled using the comprehensive degradation factor to generate the time-varying low-frequency physical RC node parameter set. The static high-frequency physical RC node parameter set and the time-varying low-frequency physical RC node parameter set are cascaded according to their physical spatial locations to construct a continuous thermal trapezoidal topology as the equivalent heat transfer model.

3. The wavelength stabilization control method for a semiconductor laser according to claim 2, characterized in that, After generating the equivalent heat transfer model, the method also includes steps to prevent computational overflow: Detect whether the multi-segment semiconductor laser is in steady-state DC operating condition; If the multi-segment semiconductor laser is detected to be in steady-state DC operation, when discretizing the equivalent heat transfer model, the complex frequency domain admittance terms corresponding to each heat capacity are forcibly set to zero, and the pure algebraic scalar cumulative values ​​of each thermal resistance are directly output to replace the calculus derivation calculation.

4. The wavelength stabilization control method for a semiconductor laser according to claim 1, characterized in that, The step of extracting the global equivalent low-frequency thermal resistance by switching the injection path of the low-frequency pilot signal includes: The duty cycle of the radio frequency data stream is compared with a preset duty cycle threshold. When the duty cycle of the radio frequency data stream is less than or equal to the duty cycle threshold, the low-frequency pilot signal is injected into the gain segment to extract the true low-frequency thermal resistance. When the duty cycle of the radio frequency data stream is greater than the duty cycle threshold, the low-frequency pilot signal is switched and injected into the grating segment to extract the proxy low-frequency thermal resistance.

5. The wavelength stabilization control method for a semiconductor laser according to claim 4, characterized in that, The specific process of extracting the actual low-frequency thermal resistance and the surrogate low-frequency thermal resistance includes: When injecting a low-frequency pilot signal into the gain segment, a digital mask function synchronized with the main communication pulse is constructed. Equivalent time undersampling is triggered only during the period when the digital mask function outputs a high level. Discrete voltage samples are obtained and reconstructed into low-frequency AC voltage amplitude in the digital domain. The actual low-frequency thermal resistance is then obtained by dividing the product of the constant injected power and the absolute value of the junction voltage drop temperature coefficient. When injecting a low-frequency pilot signal into the grating segment, continuous-time phase-locked sampling sequence extraction is performed on the voltage nodes at both ends of the grating segment, and the proxy low-frequency thermal resistance is extracted based on the thermal resistance calculation principle derived from Ohm's law.

6. The wavelength stabilization control method for a semiconductor laser according to claim 5, characterized in that, The updating of the time-varying low-frequency physical RC node parameter set includes: During the communication frame gaps of the communication protocol, the actual low-frequency thermal resistance of the gain segment and the proxy low-frequency thermal resistance of the grating segment at the current absolute time node are synchronously obtained using hardware timestamps. The real low-frequency thermal resistance acquired synchronously is divided by the proxy low-frequency thermal resistance to obtain the dynamic mapping coefficient, and the dynamic mapping coefficient is subjected to numerical range clamping processing. When the low-frequency pilot signal is switched and injected into the grating segment, the real-time acquired proxy low-frequency thermal resistance is multiplied by the dynamic mapping coefficient after numerical interval clamping processing to obtain the global equivalent low-frequency thermal resistance. The drift of the global equivalent low-frequency thermal resistance is then reverse-mapped according to spatial weight to the last-order dynamic thermal resistance and dynamic thermal capacity in the time-varying low-frequency physical RC node parameter set.

7. The wavelength stabilization control method for a semiconductor laser according to claim 1, characterized in that, The method of combining the transient heating power of the gain band with the updated equivalent heat transfer model to extrapolate the junction temperature observation data across the entire frequency band includes: The operating voltage, injection current, and output optical power of the gain band are synchronously acquired using a parallel sampling bus. The total electrical power is obtained by multiplying the operating voltage and injection current. The energy difference between the total electrical power and the output optical power is calculated to obtain the transient heating power. The equivalent heat transfer model is converted into a state-space observer in the discrete time domain, and a regularization constant is applied to the diagonal elements when constructing the discrete state transition matrix for diagonal loading. The transient heating power is used as the control input of the state-space observer, and the full-band junction temperature observation data is derived through discrete iterative calculation. The full-band junction temperature observation data is fed in parallel into a digital filter bank with flat group delay characteristics. The full-band junction temperature observation data is orthogonally decomposed into an extremely low-frequency DC component, a mid-to-low-frequency fluctuation component, and an extremely transient high-frequency fluctuation component according to a preset cutoff frequency.

8. The wavelength stabilization control method for a semiconductor laser according to claim 1, characterized in that, The step of generating a low-frequency feedback compensation current based on the low-frequency fluctuation components includes: The low- and mid-frequency fluctuation components are converted into basic wavelength compensation quantities by using a preset temperature-current wavelength tuning mapping table. Calculate the first-order differential rate of change of the basic wavelength compensation amount within multiple consecutive discrete sampling periods, and perform moving average processing to obtain the transient rate of change; When the absolute value of the transient rate of change exceeds the preset mode transition safety slope threshold, the output increment of the current cycle is truncated and clamped to the mode transition safety slope threshold, and the low-frequency feedback compensation current is output.

9. The wavelength stabilization control method for a semiconductor laser according to claim 1, characterized in that, The step of generating a feedforward predistortion compensation current by combining the extremely transient high-frequency fluctuation components includes: The discretized dynamic parameters inside the equivalent heat transfer model are called, and the minimum mean square error approximation inverse operation based on the Tikhonov regularization factor is introduced to construct the thermodynamic inverse transfer function. The transient high-frequency fluctuation component is mapped into a refractive index transient distortion by means of the thermodynamic inverse transfer function, and the refractive index transient distortion is converted into a thermal chirp cancellation amount based on the refractive index and carrier current plasma response mapping table. The thermal chirp cancellation amount is subjected to high-pass digital filtering and mean zeroing processing to generate a feedforward predistortion compensation current.

10. The wavelength stabilization control method for a semiconductor laser according to claim 1, characterized in that, The step of linearly combining the low-frequency feedback compensation current and the feedforward predistortion compensation current and then injecting them into the grating segment of the multi-segment semiconductor laser includes: Before performing linear synthesis, the low-frequency feedback compensation current and the feedforward predistortion compensation current are respectively sent to the digital delay line in the underlying computing architecture to compensate for the pipeline time difference between computing channels and achieve time series alignment. The aligned low-frequency feedback compensation current and the feedforward predistortion compensation current are algebraically added to obtain a composite compensation current, which is then injected into the grating segment to isolate the modulation crosstalk on the output optical power of the gain segment.

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