Optical module wide temperature range double current compensation method based on open loop control

Abstract

The application discloses a kind of wide temperature range double current compensation methods of optical module based on open-loop control, belong to optical module current compensation technical field, it includes using micro control unit to collect the output voltage of temperature sensor in laser driver chip, the temperature of laser driver chip is calculated as the current temperature T of optical module driving chip;According to current temperature, find the modulation current, bias current, threshold current and threshold current variation of current temperature T in temperature-current compensation table;Read the coupling coefficient of each channel of optical module in temperature-current compensation table, and using and calculate the modulation current of each channel, using and calculate the bias current of each channel;The modulation current and bias current of each channel are written into the laser driver of corresponding channel, to drive the open-loop double current compensation of corresponding channel of optical module.

Description

Technical Field

[0001] This invention relates to the field of optical module current compensation technology, specifically to a wide-temperature-range dual-current compensation method for optical modules based on open-loop control. Background Technology

[0002] With the rapid development of artificial intelligence big data models, cloud computing, and high-performance computing technologies, global data traffic is growing exponentially, placing unprecedentedly stringent demands on the transmission capacity, bandwidth density, and energy efficiency of optical communication systems. Multi-channel optical modules, by integrating multiple independent optical transmission and reception channels and achieving parallel signal transmission within a single package, have become a core component for breaking through the physical limits of single-channel speeds and meeting the interconnection needs of ultra-large-scale data centers and intelligent computing centers.

[0003] Temperature is a key environmental factor affecting the core performance parameters of the transmitter of a multi-channel optical module. It directly causes nonlinear drift in the emitted light power and extinction ratio by changing the photoelectric characteristics of the semiconductor laser.

[0004] Regarding emitted optical power, increasing temperature causes the laser's threshold current to increase exponentially, while significantly reducing the slope efficiency. Under a fixed drive current, the output optical power decreases monotonically with increasing temperature, and the different coupling efficiencies of different channels exacerbate the imbalance of optical power between channels, leading to a further reduction in the consistency of the received signal.

[0005] Regarding extinction ratio, increased temperature reduces the differential gain of the laser, thus decreasing modulation efficiency. If the bias current and modulation current are not dynamically adjusted with temperature, the power difference between logic "1" and "0" will decrease, leading to a deterioration in the extinction ratio. Furthermore, temperature changes cause the laser's operating point to shift. When the operating point approaches the threshold, the fluctuation range of the extinction ratio increases sharply, directly increasing the system's bit error rate and becoming a core bottleneck restricting the wide-temperature operating range of multi-channel optical modules.

[0006] Open-loop compensation methods are mainly divided into two types: linear fitting and temperature-current compensation tables. Linear fitting involves applying a linear fit to the collected sample data and then compensating in the optical module using the fitted formula. While this method has low complexity, its compensation accuracy is relatively low because the photoelectric effect of the laser changes non-linearly under temperature. Temperature compensation tables, on the other hand, write the bias current values ​​corresponding to the target optical power at different temperatures and then compensate in the optical module by looking up the table. This method offers higher compensation accuracy, but in multi-channel optical modules, the coupling efficiency between different channels varies, resulting in different bias current values ​​for the same optical power in different channels. This necessitates writing a large amount of temperature compensation table data to multi-channel optical modules. Further increasing modulation current compensation, the number of channels, or the temperature compensation range can easily lead to insufficient Flash storage space in the module, increasing additional hardware costs. Summary of the Invention

[0007] To address the aforementioned shortcomings in existing technologies, the optical module wide-temperature-range dual-current compensation method based on open-loop control provided by this invention solves the problems of low compensation accuracy and large memory usage of temperature-current compensation meters, which increase hardware costs in existing open-loop compensation methods.

[0008] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: A wide-temperature-range dual-current compensation method for optical modules based on open-loop control is provided, comprising the following steps: S1. The output voltage of the temperature sensor in the laser driver chip is collected by the microcontroller unit, and the temperature of the laser driver chip is calculated as the current temperature T of the optical module driver chip. S2. Based on the current temperature, find the modulation current for the current temperature T in the temperature-current compensation table. Bias current Threshold current and threshold current change ; S3. Read the coupling coefficient of each channel of the optical module in the temperature-current compensation table. and adopt and Calculate the modulation current for each channel, using , , and Calculate the bias current for each channel; S4. Write the modulation current and bias current of each channel into the laser driver of the corresponding channel to drive the open-loop dual current compensation of the corresponding channel of the optical module.

[0009] In one possible implementation, the expressions for calculating the modulation current and bias current of each channel are as follows: , in, and These are the modulation current and bias current of channel k of the optical module at the current temperature T, respectively. This is the laser threshold current at room temperature.

[0010] The beneficial effect of the above technical solution is that this solution splits the bias current into a threshold portion that is independent of the coupling efficiency. + ) and the portion above the threshold that is inversely proportional to efficiency ( This effectively solves the problem of output optical power deviation caused by neglecting the differences in threshold currents between channels in existing linear fitting methods under wide temperature range conditions. The threshold current component corresponds to the lower limit of the current required for the laser to reach the stimulated emission critical state; its value is determined solely by the inherent properties of the laser chip and is unrelated to the optical path coupling efficiency of the channel. The portion above the threshold current is the additional current used to generate the target output optical power, and its value is related to the coupling efficiency of the corresponding channel. Inversely proportional; the lower the coupling efficiency of a channel, the larger the current required to compensate for the optical power loss during the optical path coupling process.

[0011] In one possible implementation, the method for obtaining the coupling coefficient of each channel in the optical module includes: S31. Use the COC testing platform to test lasers of the same batch and record their target optical power at room temperature. and its corresponding bias current ; S32. At room temperature, the same current value is sent to each channel of the optical module. And measure the output optical power of each channel. ; S33, Based on the target optical power and output optical power Calculate the coupling coefficient of the channel. .

[0012] The beneficial effects of the above technical solution are as follows: This solution utilizes the physical characteristic that the differences between channels mainly stem from the different optical coupling efficiencies, and calibrates the coupling coefficient of each channel at room temperature. This approach unifies the temperature compensation requirements of multiple channels onto a single reference lookup table, eliminating the need for channel-by-channel full-temperature scanning. Its working mechanism lies in the fact that the mesa structure of laser chips from the same batch is essentially identical, and the intrinsic luminescence characteristics of each channel under the same driving current differ minimally. The actual differences in optical power between channels are mainly determined by the differences in coupling efficiency introduced by manufacturing processes such as lens alignment and fiber coupling. Therefore, by simply applying the same current value to each channel at room temperature and measuring the output optical power, the coupling coefficient of each channel can be calculated. This eliminates the need for full-temperature-range bias and modulation current scanning for each channel individually. During subsequent operation, a single reference table, along with the coupling coefficients of each channel, can achieve wide-temperature-range dual-current compensation for all channels, significantly reducing calibration time and testing costs, while also substantially reducing the storage space requirements of the temperature-current compensation table.

[0013] In one possible implementation, step S2 further includes: S21. Determine if there is a temperature node in the temperature-current compensation table that equals the current temperature T. If so, read the corresponding... , , and Otherwise, proceed to step S22; S22. Select the temperature node closest to the current temperature T. , , and ;or These are the two adjacent temperature nodes where the current temperature T is located. , , and Perform linear interpolation, and round the interpolation result to the nearest integer value based on the minimum current step size of the laser driver chip. , , and .

[0014] In one possible implementation, the method for constructing a temperature-current compensation table includes: A1. At the target optical power, the COC test platform was used to test multiple channels of the same batch of laser chips within the module's operating temperature range, and the bias current corresponding to each temperature node was obtained. ; A2. At the target extinction ratio, multiple channels of the same laser chip were tested within the module's operating temperature range using a COC testing platform to obtain the modulation current corresponding to each temperature node. ; A3. Using the COC testing platform, lasers from the same batch were tested to obtain their threshold current at room temperature and the threshold current at each temperature node within the module's operating temperature range. ; A4. Based on the threshold current at room temperature and the threshold current at each temperature node, calculate the change in threshold current at each temperature node. ; A5. Calculate the coupling coefficient of each channel in the optical module and the temperature nodes at all temperature points within the module's operating temperature range. , , and The corresponding node temperature is stored in the temperature-current compensation table; A6. Write the temperature-current compensation table into the Flash memory of the MCU of the same batch of optical modules.

[0015] In one possible implementation, the module operates in a temperature range of -40°C to 85°C, and all temperature nodes are determined in 2°C increments.

[0016] In one possible implementation, a step between A4 and A5 is also included. , , and The final result is obtained by rounding down the chip based on the minimum current step size of the optical module driver chip. , , and .

[0017] Compared with existing open-loop compensation methods, the advantages of this invention are as follows: A dual-current compensation mechanism ensures high signal transmission quality. This method simultaneously compensates for the bias current and modulation current at temperature, enabling the laser to not only stably maintain the target average optical power across a wide temperature range but also lock the target extinction ratio. Bias current compensation prevents signal amplitude distortion caused by optical power fluctuations, while modulation current compensation prevents eye diagram closure and increased bit error rate due to extinction ratio degradation. The synergistic effect of both ensures consistent high-quality signal transmission characteristics across the entire temperature range, offering superior signal integrity compared to schemes that compensate only for a single current.

[0018] The introduction of the coupling coefficient significantly reduces the amount of stored data. In other lookup table compensation methods, each channel needs to independently store the bias and modulation current lookup values ​​across the entire temperature range. Taking a 16-channel optical module as an example, under the industrial-grade wide temperature range requirement of -40℃ to 85℃, if a high-precision temperature-current compensation table is established with a 2℃ step size, each channel needs to store 63 sets of bias and modulation current data. Calculated at 2 bytes per value, the 16 channels would occupy approximately 4032 bytes of storage space. This solution, however, only needs to store a reference table of the same size (252 bytes) and the coupling coefficient and threshold deviation for each channel (32 bytes in total), compressing the total storage requirement to 284 bytes, reducing the data volume by more than 92%. For microcontrollers with limited Flash capacity, this effectively reduces costs and shortens calibration time, while also ensuring compensation accuracy compared to linear fitting compensation methods.

[0019] Open-loop control eliminates hardware dependence. This method is based entirely on temperature feedforward and pre-programmed lookup tables for compensation, eliminating the need for backlight monitoring photodiodes and corresponding closed-loop control loops in each channel. This not only simplifies optical and circuit design and reduces the number of components and material costs, but also avoids the limitation of closed-loop bandwidth on burst modes or high-speed modulation scenarios. It is particularly suitable for multi-channel parallel optical modules with dense channel counts and strict size requirements, significantly improving system integration and reliability. Attached Figure Description

[0020] Figure 1 This is a flowchart of a wide-temperature-range dual-current compensation method for optical modules based on open-loop control. Detailed Implementation

[0021] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0022] refer to Figure 1 , Figure 1 A flowchart of a wide-temperature-range dual-current compensation method for optical modules based on open-loop control is shown; as follows: Figure 1 As shown, the method S includes steps S1 to S4.

[0023] In step S1, the output voltage of the temperature sensor in the laser driver chip is acquired by the microcontroller unit, and the temperature of the laser driver chip is calculated as the current temperature T of the optical module driver chip. Since the driver chip and the laser chip are often on the same heat dissipation layer in the optical module and their temperatures are similar, the temperature of the laser chip is used as the temperature of the driver chip in the optical module.

[0024] In step S2, based on the current temperature, the modulation current for the current temperature T is looked up in the temperature-current compensation table. Bias current Threshold current and threshold current change .

[0025] In implementation, the preferred step S2 of this scheme further includes: S21. Determine if there is a temperature node in the temperature-current compensation table that equals the current temperature T. If so, read the corresponding... , , and Otherwise, proceed to step S22; S22. Select the temperature node closest to the current temperature T. , , and ;or These are the two adjacent temperature nodes where the current temperature T is located. , , and Perform linear interpolation, and round the interpolation result to the nearest integer value based on the minimum current step size of the laser driver chip. , , and .

[0026] In step S3, the coupling coefficient of each channel of the optical module is read from the temperature-current compensation table. and adopt and Calculate the modulation current for each channel, using , , and Calculate the bias current for each channel.

[0027] In implementation, the preferred method for obtaining the coupling coefficient of each channel in the optical module includes: S31. Use the COC testing platform to test lasers of the same batch and record their target optical power at room temperature. and its corresponding bias current The module operates in a temperature range of -40℃ to 85℃, and all temperature nodes are determined in 2℃ increments.

[0028] S32. At room temperature, the same current value is sent to each channel of the optical module. And measure the output optical power of each channel. ; S33, Based on the target optical power and output optical power Calculate the coupling coefficient of the channel. .

[0029] This scheme utilizes the physical characteristic that the differences between channels mainly stem from varying optical coupling efficiencies, and extracts the coupling coefficient through single-temperature point calibration. This unifies the temperature compensation requirements of multiple channels onto a single reference lookup table, eliminating the need for channel-by-channel full-temperature scanning and reducing the complexity of optical module temperature compensation.

[0030] In this scheme, the preferred expressions for calculating the modulation current and bias current of each channel are as follows: , in, and These are the modulation current and bias current of channel k of the optical module at the current temperature T, respectively. This is the laser threshold current at room temperature.

[0031] In step S4, the modulation current and bias current of each channel are written into the laser driver of the corresponding channel to drive the open-loop dual current compensation of the corresponding channel of the optical module.

[0032] This scheme splits the bias current into a threshold portion that is independent of coupling efficiency and a portion above the threshold that is inversely proportional to efficiency. and Separate compensations were provided to resolve the optical power deviation problem caused by neglecting threshold differences in the linear fitting method over a wide temperature range.

[0033] In one embodiment of the present invention, the method for constructing a temperature-current compensation meter includes: A1. At the target optical power, the COC test platform was used to test multiple channels of the same batch of laser chips within the module's operating temperature range, and the bias current corresponding to each temperature node was obtained. ; A2. At the target extinction ratio, multiple channels of the same laser chip were tested within the module's operating temperature range using a COC testing platform to obtain the modulation current corresponding to each temperature node. ; A3. Using the COC testing platform, lasers from the same batch were tested to obtain their threshold current at room temperature and the threshold current at each temperature node within the module's operating temperature range. ; A4. Based on the threshold current at room temperature and the threshold current at each temperature node, calculate the change in threshold current at each temperature node. ; A5. Calculate the coupling coefficient of each channel in the optical module and the temperature nodes at all temperature points within the module's operating temperature range. , , and The corresponding node temperature is stored in the temperature-current compensation table; A6. Write the temperature-current compensation table into the Flash memory of the MCU of the same batch of optical modules.

[0034] In this solution, all channels of the optical module use the same [method / applicator] at the same temperature. , , and Combining coupling coefficients The calculation of modulation current and bias current for compensation reduces the amount of data required by the temperature-current compensation meter, thereby reducing hardware costs.

[0035] In implementation, this solution preferably includes a step between step A4 and step A5. , , and The final result is obtained by rounding down the chip based on the minimum current step size of the optical module driver chip. , , and .

[0036] This scheme quantizes the reference current value according to the minimum step size of the driver during the calibration stage and then writes it into the lookup table. During operation, the lookup table output can be directly adapted to the hardware resolution, avoiding accuracy loss or truncation error in real-time calculation and ensuring that the open-loop control accuracy is fully matched with the driver capability.

[0037] In summary, the compensation method provided in this solution can perform precise compensation of the optical power and extinction ratio of the optical module through a temperature lookup table, and solve the differences between different channels through the coupling coefficient, thereby achieving dual-current compensation for multi-channel optical modules with low data volume, high accuracy, and wide temperature range.

Claims

1. A wide-temperature-range dual-current compensation method for optical modules based on open-loop control, characterized in that, Including the following steps: S1. The output voltage of the temperature sensor in the laser driver chip is collected by the microcontroller unit, and the temperature of the laser driver chip is calculated as the current temperature T of the optical module driver chip. S2. Based on the current temperature, find the modulation current for the current temperature T in the temperature-current compensation table. Bias current Threshold current and threshold current change ; S3. Read the coupling coefficient of each channel of the optical module in the temperature-current compensation table. and adopt and Calculate the modulation current for each channel, using , , and Calculate the bias current for each channel; S4. Write the modulation current and bias current of each channel into the laser driver of the corresponding channel to drive the open-loop dual current compensation of the corresponding channel of the optical module.

2. The wide-temperature-range dual-current compensation method for optical modules according to claim 1, characterized in that, The expressions for calculating the modulation current and bias current of each channel are as follows: ， in, and These are the modulation current and bias current of channel k of the optical module at the current temperature T, respectively. This is the laser threshold current at room temperature.

3. The wide-temperature-range dual-current compensation method for optical modules according to claim 1, characterized in that, The methods for obtaining the coupling coefficient of each channel in the optical module include: S31. Use the COC testing platform to test lasers of the same batch and record their target optical power at room temperature. and its corresponding bias current ; S32. At room temperature, the same current value is sent to each channel of the optical module. And measure the output optical power of each channel. ; S33, Based on the target optical power and output optical power Calculate the coupling coefficient of the channel. .

4. The wide-temperature-range dual-current compensation method for optical modules according to claim 1, characterized in that, Step S2 further includes: S21. Determine if there is a temperature node in the temperature-current compensation table that equals the current temperature T. If so, read the corresponding... , , and Otherwise, proceed to step S22; S22. Select the temperature node closest to the current temperature T. , , and ;or These are the two adjacent temperature nodes where the current temperature T is located. , , and Perform linear interpolation, and round the interpolation result to the nearest integer value based on the minimum current step size of the laser driver chip. , , and .

5. The wide-temperature-range dual-current compensation method for optical modules according to claim 3, characterized in that, Methods for constructing temperature-current compensation tables include: A1. At the target optical power, the COC test platform was used to test multiple channels of the same batch of laser chips within the module's operating temperature range, and the bias current corresponding to each temperature node was obtained. ; A2. At the target extinction ratio, multiple channels of the same laser chip were tested within the module's operating temperature range using a COC testing platform to obtain the modulation current corresponding to each temperature node. ; A3. Using the COC testing platform, lasers from the same batch were tested to obtain their threshold current at room temperature and the threshold current at each temperature node within the module's operating temperature range. ; A4. Based on the threshold current at room temperature and the threshold current at each temperature node, calculate the change in threshold current at each temperature node. ; A5. Calculate the coupling coefficient of each channel in the optical module and the temperature nodes at all temperature points within the module's operating temperature range. , , and The corresponding node temperature is stored in the temperature-current compensation table; A6. Write the temperature-current compensation table into the Flash memory of the MCU of the same batch of optical modules.

6. The wide-temperature-range dual-current compensation method for optical modules according to claim 5, characterized in that, The module operates in a temperature range of -40℃ to 85℃, and all temperature nodes are determined in 2℃ increments.

7. The wide-temperature-range dual-current compensation method for optical modules according to claim 5, characterized in that, Between step A4 and step A5, there is also a... , , and The final result is obtained by rounding down the chip based on the minimum current step size of the optical module driver chip. , , and .

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